Research Descriptions

Allergy

Research in my laboratory is focused on the role of infection in chronic diseases, especially arthritis and asthma. Work is proceeding on a research grant to explore immune responses to mycoplasma infection in normal and asthmatic children with particular emphasis on possible effects of the organism on mast cells and the IgE system. My recent graduate student Kristie Hoek found that Mycoplasma pneumoniae is able to activate mast cells to produce IL-4, a finding with potential implications in the pathogenesis of asthma. Work is currently proceeding under a new grant to characterize the mechanism of cellular activation by M. pneumoniae. I am also actively engaged in the development of rational strategies to determine the molecular basis for unidentified immunodeficiencies in patients in my weekly clinic at Children’s Hospital. Such patients may represent natural “knockouts” or dominant negative mutations in signaling molecules and provide valuable insights into critical steps in receptor signaling in the human immune system.

J. Edwin Blalock, PhD

The overall objective of our current research is to delineate certain genetic rules that govern the shape and function of proteins and peptides. Specifically, nucleic acids encode amino acid sequences in a binary fashion with regard to hydropathy. We and others have provided compelling evidence that the exact pattern of polar and nonpolar amino acids, rather than the precise identity of particular R groups, is an important driving for protein shape. Structural proof for this idea is being pursued through determination of the 3-dimensional structures of peptides with dissimilar primary amino acid sequences but identical binary codes. These design principles are being used: 1) to make synthetic peptides specifically targeted to act as agonists and antagonists of Ca++ channels involved in human immunodeficiency virus-mediated apoptosis and 2) to make synthetic peptide vaccines as immunotherapeutic agents against autoimmune diseases of the nervous system such as myasthenia gravis (MG) and multiple sclerosis (MS). Additional research areas include: First, together with colleagues at the University of Utrecht, we are evaluating the aforementioned peptide regulators of Ca++ channels for utility in models of asthma. Second, together with Dick Marchase's group, we are elucidating the structure and function of a novel Ca++ influx factor (CIF) which is a key signal for store-operated Ca++ entry. Third, we are studying the role of these CIF-operated channels, as well as their regulation by glucosamine in diabetes.

Craig A. Elmets, MD

Dr. Elmets’ research focuses on the interaction of environmental agents with the skin. His research has particular relevance to skin cancer and cutaneous allergic reactions. In the area of skin cancer, his interests are on skin cancer chemoprevention and therapy. He has played a key role in defining the mechanisms by which the immune system controls the development of skin cancers. More recent studies have centered on the identification of new agents that can protect against skin cancer and on the non-surgical treatment of these malignancies. These include the arthritis drug celecoxib and extracts of green tea. He has also played a major role in the development of photodynamic therapy as a treatment for cancer. Photodynamic therapy utilizes light activated drugs to eradicate cancer. Dr. Elmets’ other area of research is on allergic contact dermatitis, of which poison ivy is the best-known example. He is evaluating better and more accurate diagnostic techniques for contact allergies. His studies have shown that certain proteins called cytokines are synthesized in skin cells from allergic individuals exposed to contact allergens but not in those obtained from people who are the not allergic. These findings provide the conceptual framework for the development of a diagnostic test for skin allergy testing, which can used by physicians and by industry as an alternative to animal testing prior to the introduction of new products into the marketplace.

Lisa Schwiebert, PhD

The major research interests of the laboratory include studying the physiology and pathophysiology of immune responses within the lung. These interests encompass the study of respiratory disorders in order to understand the cellular and molecular mechanisms that underlie airway inflammation. On-going projects examine how surface molecules, such as CFTR and CD40, regulate the airway epithelial expression of pro-inflammatory mediators, including chemokines and adhesion molecules, that initiate and exacerbate leukocyte migration. In addition, we are examining the anti-inflammatory effects of aerobic exercise on asthma-related immune responses. Through increased understanding of the mechanisms that trigger airway inflammation, we hope to develop novel therapeutic agents that combat airway inflammatory diseases such as cystic fibrosis and asthma.

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Autoimmunity

Scott R. Barnum, PhD

My research interests have been on the production and regulation of several components in the complement system. These interests focused on the central nervous system (CNS) based on growing evidence for a role for complement in CNS diseases. This led us to examine for the production and cytokine-mediated regulation of additional activation components, as well as, complement regulatory proteins. It is now clear that, at least in vitro, most if not all complement proteins can be synthesized by astrocytes, microglia, and to our surprise, neurons. Since these initial observations, we have moved into in vivo models systems. Using a variety of disease models, including bacterial meningitis, brain trauma, experimental allergic encephalomyelitis (EAE) and a murine stroke model, we have demonstrated that a number of complement proteins and receptors are widely produced in the intact CNS under pathological conditions. We have recently expanded our interest in complement in the CNS to include C-reactive protein (CRP) and beta2-integrins and several of their ligands. We are examining the role of these molecules in EAE using several complement and adhesion molecule knock-out mice. In addition, we are using mice transgenic for CRP and several transgenic mouse lines that express either the complement regulatory protein (sCrry) or the complement anaphylatoxins, C3a or C5a, only in the CNS under the control of an astrocyte-specific promoter. Our data suggest that targeting these molecules has therapeutic value.

In other studies, we are examining the role of gamma/delta T cells in autoimmune disease in the CNS with a particular interest in trafficking and activation mechanisms. We have recently shown that these cells are critical to the development of EAE, but surprisingly little is known about the function of these cells in the pathogenesis of demyelinating disease.

Elizabeth E. Brown, PhD

Using models of autoimmunity and immune-suppression, the work in our laboratory is targeted toward understanding the natural history of viral infections and aberrant immune function common to inflammatory-mediated chronic diseases. Of particular interest is the genetic basis of select host-pathogen interactions, virally-associated cancers, select lymphomas, systemic lupus erythematosus (SLE) and systemic vasculitis, each with underlying B cell pathologies. Within this purview, we use a multi-disciplinary functional genomics approach to explore pathways involved in chronic immune perturbation, B cell homeostasis, cytokine signaling as modifiers of disease, mucosal immunity and immune senescence as markers of complex disease susceptibility, morbidity and mortality. The goal of this research is to identify and validate molecular biomarkers of clinical outcomes, which may be used to target high-risk populations to prevent or reduce disease burden.

Robert H. Carter, MD

B lymphocytes are central players in the immune response. They make antibodies that fight infections. However, normal B cell development also leads to production of B cells that make antibodies that react with the body’s own tissues (“autoantibodies”). If these aren’t controlled properly, the autoantibodies cause tissue damage and disease. B cells are triggered by binding of microbes or tissue that their antibodies react with, but the response of the B cell to this trigger is controlled by other cell-surface proteins. Dr. Carter's lab is focused on understanding how these cell-surface molecules control what the B cell does in the normal immune system and in autoimmune disease. The basic work has studied one of these proteins, CD19. CD19 knockouts have significant abnormalities in B cell differentiation and in antibody responses. Recent work has focused on how CD19 interacts with cytoplasmic signaling proteins, including structural analysis (protein binding analysis, Biacore). Dr. Carter's group has used this information to construct trangenes with mutations in the amino acids that have been found to have important functions in the structural analysis. They study immune responses in the transgenic mice to study the effect of point mutants on signaling in vivo and B cell physiology. Thus, this work links structure to signal transduction to whole animal, immune system biology. Dr. Carter's lab has translated this understanding of B cell biology to the study of human disease, particularly lupus. This is a disease mediated by abnormal B cell activation and autoantibodies. This project studies the abnormal activation of B cells in lupus. They are using the findings to develop new, biologic therapies for lupus that target the activated B cells without harming normal cells, using both animal models of disease as well as cells from lupus patients. Thus, they welcome anyone interested in protein-protein interactions, signal transduction, lymphocyte cell biology, normal and disrupted immune responses in mice, and autoimmune diseases.

Hui-Chen Hsu, PhD

Dr. Hsu’s main research interests are to identify the molecular pathogenic mechanisms and the immune defects associated with the development of generalized autoimmune disease and chronic erosive arthritis in the polygenic BXD2 autoimmune mouse model. Dr. Hsu also carries out the genetic linkage analysis to identify and segregate the genetic loci leading to lupus and/or arthritis in the BXD2 mouse model. Dr. Hsu also studies properties of senescent T cells from mice and humans. This includes defects in T-cell activation, activation-induced cell death (AICD) and signaling pathways including CD28, Akt, forkhead and Fas ligand.

Robert P. Kimberly, MD

Our laboratory is interested in the role of genetic factors in the normal function of the immune system and in development of autoimmune and immune-mediated inflammatory diseases such as systemic lupus erythematosus and systemic vasculitis. Our approach has focused on receptors for immunoglobulin as a model system and has explored molecular mechanisms of receptor signaling and the molecular basis for receptor polymorphisms in humans. Studies in cell lines and in normal donors have demonstrated that despite the common theme of receptor-induced tyrosine phosphorylation the various human Fc receptors engage of different signaling elements which are reflected in important distinctions in function. Similarly, allelic variations in receptor structure profoundly affect receptor function, and certain low-binding alleles are enriched in SLE patients. More active alleles are over-represented in patients with vasculitis and severe renal disease. Other genes and gene families are being pursued as they are identified as candidate genes through genome scans, family studies and linkage studies. These genes include complement receptors, cytokine genes and their promoters, signal transduction molecules, and members of the TNF superfamily.

Xiaoli Li, PhD

Research focused on signaling and functional regulation mediated by Fcgamma Receptors. Dr. Li's major goals are (1) to define the unique cytoplasmic domain binding partners of the Fc gamma-chain associated CD16A and to define their contributions to receptor signaling and function; (2) to identify contributions of the unique Fcgamma Receptor gamma-chain cytoplasmic domains to specific signaling capacities and immunological functions.

Michele Marron, PhD

Dr. Marron's laboratory research focuses on understanding the role of MHC class I molecules, and the CD8 T cells which recognize them, in susceptibility to type 1 diabetes (T1D). The development of T1D results from autoimmune destruction of the insulin-secreting beta-cells of pancreatic islets. T1D is a complex disease involving greater than 20 genetic loci and interactions with unknown environmental factors. The primary genetic susceptibility has been mapped to the major histocompatibility (MHC) locus. While unusual MHC class II alleles contribute to type 1 diabetes (T1D) susceptibility, MHC class I restricted CD8 T cells are critical for initiation of the autoimmune process. Therefore, it is important to identify the antigens recognized by autoreactive CD8 T cells if tolerogenic protocols to prevent T1D in humans are to be developed. Since these studies are not possible in humans, Dr. Marron has taken the alternative approach of expressing human MHC class I alleles in non-obese diabetic (NOD) mice. Epidemiological studies indicate HLA-A2 and HLA-A24 contribute to T1D susceptibility when expressed in conjunction with high risk class II alleles. Our studies have demonstrated NOD mice transgenically expressing HLA-A2.1 have accelerated T1D onset. Furthermore, T1D develops in a NOD stock in which human HLA-A2.1 is the only MHC class I molecule expressed, indicating HLA-A2.1 restricted CD8 T cell responses are sufficient for the initiation of T1D. Studies are currently underway to identify the antigens which are recognized by islet-infiltrating CD8 T cells in this transgenic model, and to identify the non-MHC genes which are involved in allowing development of such autoreactive effectors.

John D. Mountz, MD, PhD

The major focus of the laboratory is analysis of T cell tolerance loss and regulation of autoantibody production. The BXD2 recombinant inbred strain of mouse produces multireactive pathogenic autoantibodies that can cause arthritis and glomerulonephritis. The T cell tolerance loss mechanisms, including upregulation of IL-17 and T follicular helper cell factors, and their effects on B cell development, immunoglobulin somatic hypermutation and class switch recombination are being investigated. One key molecule that is upregulated is activation induced cytidine deaminase (AID). Inhibitors of the AID activation pathway and AID inhibitors are being investigated.

A second focus of Dr. Mountz's laboratory is the investigation of longevity assurance genes (LAG). A defect in apoptosis with aging occurs as a process of replicative senescence in all replicating cells, including T cells. Therefore, apoptosis molecules, such as Fas and Fas ligand have been proposed as LAGs. In mice, an age-related defect, in activation-induced cell death (AICD) is associated with a defect in Fas ligand production. In humans, there is also an age-related AICD defect associated with constitutive upregulation of Fas, and a defect in Fas apoptosis signaling.

A third focus of the lab is to develop strategies to subvert the immune response to gene therapy. The vectors being tested include wild-type adenovirus, as well as E1-deleted Ad containing different cytokines. A second gene therapy vector is adeno-associated virus engineered to produce human factor IX (F.IX). The immune response is being analyzed in BXD RI strains of mice, as well as knockout strains of mice to investigate the CTL response and antibody response to virus capsid and transgenes in both systems. The generation of specific CTLs is being investigated using MHC class I specific peptides and tetramers to analyze the generation kinetics of specific CTLs to the vector and transgene.

Jan Novak, PhD

Research interests involve a wide area of biologically active compounds of natural origin (multidisciplinary approaches to identification, isolation, and analyses of novel compounds, studies on their structure, biosynthesis, and genetics, mode of action and mechanism of resistance), biochemistry and genetics of post-translationally modified peptides and proteins, enzymes and pathways of primary and secondary metabolism and cellular regulations, intercellular communication and signaling, and glycosylated compounds. Of particular interest more recently are studies on glycosylation of immunoglobulins in health and disease in humans (IgA nephropathy, chronic inflammatory diseases, Kawasaki syndrome) and regulation of immunoglobulin glycosylation.

The hallmark of IgA nephropathy (IgAN), the most common glomerulonephritis in the world, is deposition of IgA1-containing immune complexes into the glomerular mesangium. Proliferation of mesangial cells (MC) and extracellular matrix (ECM) expansion occurs from early stages, progressing into glomerulosclerosis and development of end stage renal disease. High levels of IgA1-containing circulating immune complexes (CIC) are often observed in IgAN patients indicating a defect in CIC clearance. Galactose (Gal) -deficient O-glycans were detected in the hinge region of IgA1 molecules in CIC in IgAN patients. These Gal-deficient IgA1 molecules are complexed with IgG (IgA1) antibodies with anti-GalNAc specificity. Importantly, Gal-deficient IgA1 is also found in kidney immune deposits in IgAN patients. Dr. Novak's group hypothesizes that the glycosylation aberrance of a fraction of IgA1 molecules results in formation of CIC that ultimately deposit in the mesangium, leading to IgAN. Based on preliminary results, they postulate that the CIC bind to MC through a novel IgA receptor and possibly other receptors, and trigger signaling events resulting in proliferation of MC and ECM expansion. The group has studied interactions of CIC with MC using various approaches, including for example confocal laser scanning microscopy, differential gene and protein expression using DNA arrays and proteomics approaches, respectively. The ultimate goal of these studies is to understand how CIC form, what are major factors inducing aberrant IgA glycosylation, and how CIC trigger pathological response of MC leading to IgAN. We are hopeful that a better understanding of this chronic disease may open new ways for diagnosis or even treatment.

Chander Raman, PhD

The overall research focus of the laboratory is the elucidation of mechanisms that regulate generation and maintenance of immune tolerance in T and B lymphocytes. Autoimmunity and predisposition to development of leukemias are the often of the outcomes of alterations in generation and/or maintenance of tolerance. The development of inability of T and B lymphocytes to respond to self antigens while maintaining the ability to respond to self antigens is an active process in which the signals initiated by the engagement of the T cell antigen receptor (TCR) or B cell antigen receptor (BCR) are regulated by a complex of other lymphocyte surface molecules. Signaling cascades initiated by these lymphocyte surface molecules range form those that directly alter the quality and quantity of antigen receptor signals to those that promote cell survival or initiate programmed cell death or apoptosis. Dr. Raman's experimental approaches include in vitro structure function studies to define protein-protein interactions to the use of animal models of disease that naturally occur or are genetically created. Currently, the lab's focus is on the cell surface receptors CD5, DR6 and the family of receptors that bind to lignads Blys and April. Each of these receptors plays a key role in regulating lymphocyte function and homeostasis and alterations in their signaling activities leads to diverse pathologies. The ultimate goal of these studies is to identify key targets for the development of therapeutic strategies for the treatment of leukemias and autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus.

Kaihong Su, PhD

The immunoglobulin (Ig) Fc receptors play an important role in bridging innate and adaptive immunity. We focus our study on the tissue-specific regulation and signaling of Ig Fc receptors and their role in the development of autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). Besides the molecular and cellular approach, we also use genetic approach including association and linkage analyses to further study the role of Fc receptors in SLE pathogenesis. We have characterized single nucleotide polymorphisms (SNPs) in the inhibitory FcgammaRIIb and identified FcgammaRIIb as a susceptibility gene for the development of SLE. We also examine the function of DNA repair pathway in SLE and characterize the potential disease-causative polymorphisms in DNA repair genes.

Jianming (Jimmy) Wu, DMV, PhD

Dr. Wu and colleagues study the human autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosis (SLE) using molecular, cellular, and biochemical technologies. Their major research interests focus on molecular genetics of human autoimmune diseases. Specific interests include the discovery and characterization of single nucleotide polymorphisms of human immune related genes such as Fcgamma receptor family members (CD32B, CD32C, and CD16A), Fcalpha receptor I (CD89), Fas (CD95), FasL (CD95L), complement receptor 1 (CD35), and C-reactive protein (CRP), and their roles in the pathogenesis of autoimmune diseases such as SLE and RA. The laboratory studies human immunoglobulin receptor biology, mRNA editing and gene regulation. They have made several important discoveries in that direction. These studies will provide important insight into the pathogenesis of autoimmune diseases, and help to offer guidelines for prevention or treatment of autoimmune diseases.

Huang-Ge Zhang, DVM, MD, PhD

Dr. Zhang's research is recently focused upon understanding how the ubiquitin pathway regulates intracellular signal transduction pathways that transfer key information from the extracellular to the intracellular environment, resulting in coordinated cellular responses. More specifically, he is interested in the ubiquitin pathway’s role of apoptosis in 1) autoimmune diseases and 2) cancer immunosuppresssion.

In cancer immunosuppression, Dr. Zhang's research focuses on the elucidation of the cellular and molecular basis for the role of tumor exosomes and exosomal tumor antigens in the development of T- cell dependent breast cancer and the mechanism underlying tumor immunosuppression mediated by tumor excreted exosomes.

In autoimmune diseases, TNF-alpha plays a critical role in the progression of rheumatoid arthritis. Constant activation of TNF-alpha signaling results in chronic inflammation and erosive arthritis, as confirmed in the human TNF-alpha transgenic mice model. Dr. Zhang and colleagues' research focuses on how Jab1 regulates TNF-alpha anti- and pro- apoptosis pathways in rheumatoid arthritis synovial fibroblasts.

The group also develops strategies for deletion of antigen specific auto-reactive T cells, using antigen presenting cells pulsed with an auto-antigen and armed with apoptosis molecules such as Fas ligand or TRAIL antigen. Strategies to ultimately treat T cell mediated autoimmune diseases are actively sought.

Tong Zhou, MD

Dr. Zhou’s research is centered on the characterization of apoptotic pathways with a view to therapeutic manipulation in autoimmune and inflammatory disease. In the first approach, Drs. Zhou has collaborated closely with Dr. Mountz, to demonstrate that strategies centered on Fas ligand might prove useful in the therapeutic regulation of autoimmune disease. To by-pass the toxic effect of soluble Fas ligand, Dr. Zhou, in close collaboration with Dr. Mountz, has used cell-gene therapy consisting of an antigen presenting cell transfected with AdFas ligand to eliminate chronic inflammation and autoimmune disease in a number of murine models of these disease. The utility of this approach is being improved by the incorporation of elements that permit timed induction of discrete levels of Fas ligand to eliminate activated T cells in an antigen-specific manner. This APC-Fas L cell-gene therapy approach has proven useful in the experimental analysis of Fas-mediated apoptosis and antigen-induced cell death in autoimmune disease and may prove useful as a therapeutic strategy in the prevention of post-infectious chronic inflammation or organ-specific disease. In the second approach, Dr. Zhou has developed agonistic and antagonistic monoclonal antibodies that discriminate the DR5 TRAIL receptor and is using these to characterize the distribution of this receptor among T cell populations during activation responses as well as the associated signal transduction events. The ability of these monoclonal antibodies to specifically inhibit autoimmune reactions is being analyzed in various murine models, including models of SLE, collagen II-induced arthritis, and experimental allergic encephalitis. Similar approaches are now being used to characterize the role of B lymphocyte stimulator (BLyS) in SLE in a coordinated effort involving collaboration with Drs. Alarcon, Fessler, and Kimberly.

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Cancer Immunology

Donald J. Buchsbaum, PhD

The Comprehensive Cancer Center and the Department of Radiation Oncology established the Division of Radiation Biology in October, 1990. Donald J. Buchsbaum, Ph.D. was recruited from the University of Michigan to be the Division Director and develop an experimental radioimmunotherapy program using radiolabeled antibodies that bind to antigens expressed on the surface of cancer cells. The Division has grown to include 4 additional Ph.D. faculty, 3 postdoctoral fellows, and technicians totaling 25 full-time employees. The Division has developed innovative approaches to radioimmunotherapy of cancer using novel targeting molecules. This research has contributed to the funding of Ovarian and Breast Cancer Specialized Programs of Research Excellence (SPORE) at UAB by the National Cancer Institute, and funding to the Cancer Center from the Avon Products Research Foundation for breast cancer research. In addition, the Division of Radiation Biology has been in the forefront of research into the treatment of cancer in experimental models with a combination of gene therapy and radiation therapy. This has resulted in a SPORE in Brain Cancer and grants and contracts from the National Cancer Institute, the Department of Energy, and the Department of Defense, with emphasis on colon, ovarian, and prostate cancer. Another significant finding was unlabeled antibody against epidermal growth factor receptor resulted in increased sensitivity of head and neck cancer to radiation. This was translated into a very successful clinical phase I trial in head and neck cancer at UAB. A phase III trial testing this new combination therapy with UAB as the lead institution showed significantly increased local tumor control and survival in patients with head and neck cancer. Recently he has been investigating the treatment of breast, colon, lung, pancreatic, and brain cancer with death receptor antibodies in combination with chemotherapy and radiation therapy with very promising results. This has resulted in funding of a Pancreatic SPORE. Thus, very innovative and clinically relevant research is being carried out in the Division of Radiation Biology.

David T. Curiel, MD, PhD

My current research interest relates to the development of vector systems for the achievement of targeted, cell-specific gene delivery. This central field mandate is being addressed via the development of adenoviral vector systems, which embody genetic capsid modifications allowing tropism modification. In addition, the parallel study of the biologic dictates of adenovirus entry is currently being endeavored.

Craig A. Elmets, MD

Vithal K. Ghanta, PhD

The research interests of our group are the treatment of cancer at multiple modality levels, quantitation of tumor load, follow-up of the response of tumors to different agents and modalities, understanding the interactions between the immune and central nervous systems, and the changes that take place in the immune system with age. I am interested in developing new approaches for the treatment of cancer, including combination treatments like passive therapy, immune stimulation, and chemotherapy. Secondly, our group has developed a conditioning paradigm for an increase in natural killer cell and cytotoxic T-lymphocyte activities. The model is used extensively in our laboratory to study the mechanisms of central nervous and the immune system interactions and the mechanisms of conditioned regulation of tumor growth.

G. Yancey Gillespie, PhD

The main thrust of Dr. Gillespie's research is to develop and test specific therapies for treatment of malignant brain tumors in adults and children. One current focus is construction of replication conditional herpes simplex viruses that are both oncolytic for glioma cells and express foreign therapeutic genes. Gene transfer includes both pro-drug converting enzymes and cytokines under different promoter systems. Pro-drug enzyme systems currently being studied are cytosine deaminase (CD) alone or as a fusion protein with uracil phosphoribosyl transferase (UPRT) and purine nucleoside phosphorylase (PNP). A second focus involves studies with the CD and CDUPRT systems in both replication incompetent adenovirus and conditionally replication competent adenovirus. Adenoviruses targeted to cell surface receptors on glioma cells are being constructed to provide tumor specificity. Cytokines expressed from replication competent HSV that are being studied include TNFa, IL-2, IL-4, IL-5, IL-10, IL12, IL-16. These systems are validated by in vitro assays first before being advanced to safety and efficacy assessment in a variety of murine models of intracranial malignant gliomas. These models include transplantable intracranial gliomas of human origin (in immunocompromised scid or nude mice) or mouse origin (in syngeneic conventional mice). Dr. Gillespie's group also has acquired 2 transgenic glioma mouse models and use high-field strength (8.5T) magnetic resonance imaging to detect and monitor tumor growth in transgenic mice. One intriguing observation is the fact that many of these viral oncolytic and transgene therapies are markedly enhanced by modest doses of whole brain irradiation. This phenomenon is being studied at the cellular and molecular levels to determine how it can be best employed as a therapeutic strategy. Vectors that are to be advanced to clinical trials are tested for neurotoxicity in non-human primates. Finally, small peptides that exert an anti-angiogenic effect on tumor neovasculature or that induce apoptosis in human glioma cells are being studied as therapeutic agents in vitro and in animal models of malignant brain tumors.

Judith A. Kapp, PhD

Dr. Kapp's research focuses on identifying mechanisms of inducing and abrogating immunological tolerance. Our long-term goal is to translate our findings into novel therapies for preventing graft rejection and augmenting tumor immunity.

Dr. Kapp's ongoing, studies are directed to basic and clinical aspects of immune regulation by T cells. We have recently focused on the regulatory role of γδ T cells in tolerance. Depletion of γδ T cells prevents tolerance as measured by antibody, CD4+, and CD8+ effector T cell responses induced by oral administration of antigen (Ke, Y., K. Pearce, J. P. Lake, K. Ziegler, and J.A. Kapp. J. Immunol. 158:3610-3618, 1997). To determine whether intraepithelial γδ T cells in the small intestine play a role in oral tolerance, her group has cloned them and found that they are highly immunosuppressive (Kapp, J.A., L.M. Kapp, K.C. McKenna, and J.P. Lake. Submitted). These observations suggested that γδ T cells play a critical, active role in tolerance induced by orally administered antigen. Their studies also show that the immunoregulatory role of γδ T cells is not limited to oral tolerance but extends to systemic tolerance induced by delivery of antigen into the anterior chamber of the eye (Xu, Y. and J.A. Kapp. Immunol. 104:142-148, 2001; Xu, Y. and J.A. Kapp. Invest. Opthalmol. Vis. Sci. 43:3473-3479, 2002), an immunologically privileged site.

Dr. Kapp and colleagues are interested in whether γδ T cells might also play a role in the failure of the immune system to control tumor growth in spite of the fact that many tumors express specific antigens. The failure of tumors to stimulate effective immune responses has been attributed, in part, to their lack of co-stimulatory molecules. Tumors lacking co-stimulatory molecules may induce tolerance rather than immunity leading to progressive tumor growth. As a model system, we used the ovalbumin (OVA) transfected EL4 tumor, called E.G7-OVA, which grows progressively in syngeneic mice even though it can be rejected if the mice are immunized with OVA in adjuvant. E.G7-OVA grew more rapidly in immunodeficient Rag-1 knockout mice than in immunocompetent mice suggesting that normal mice make an abortive immune response to this tumor. Depletion of γδ T cells augmented the ability of mice to reject E.G7-OVA. Moreover, spleen cells from normal, but not IL-10 knockout, mice reconstituted rapid tumor growth in γδ T cell-deficient mice. Thus, we conclude that γδ T cells play an important role in preventing immune elimination of this tumor by a mechanism that directly or indirectly involves IL-10 (Ke, Y., L.M. Kapp, and J.A. Kapp. Cell. Immunol. 221:107-114, 2003).

To test whether E.G7-OVA induced tumor-specific tolerance in the presence of normal γδ T cells, the group used drug therapy to ablate the tumors before testing for tolerance. The alkaloid, noscapine, was used because it has been determined to be a novel anti-mitotic drug that induces tumor regression (Ye, K., Y. Ke, N. Keshava, J. Shanks, J.A. Kapp, R.R. Tekmal, J. Petros, and H.C. Joshi. Proc. Nat. Acad. Sci. 95:1601-1606, 1998). Noscapine, given parenterally or in the drinking water, induces apoptosis of E.G7-OVA and causes regression of this tumor without adverse effects on normal tissues or inhibition of immune responses (Ke, Y., K. Ye, H.E. Grossniklaus, D.R. Archer, H.C. Joshi, and J.A. Kapp. Cancer Immunol. Immunother. 49: 217-225, 2000). These results form the basis of a Provisional Patent Application (No. 60/057,037).

The majority of tumors in the mice that received noscapine disappeared and did not return during continuous treatment with the drug. After four months, the surviving mice and untreated control B6 mice were injected with OVA in adjuvant to test whether the tumor had induced tolerance to OVA. The noscapine treated mice developed OVA antibody and CD4+ T cell responses equivalent to normal mice but OVA-specific CD8+ CTL responses that were 10- to 30-fold greater than the responses of controls. Although these results do not allow determination of whether the tumor induced tolerance in the absence of noscapine, they raise the interesting possibility that noscapine may have potent adjuvant activity for CTL in addition to its anti-mitotic effects. Dr. Kapp is particularly interested in testing the efficacy of noscapine in the treatment of other types of tumors. In addition, her group is investigating the possibility that its adjuvant effects may promote tumor specific immune responses using CD4+ and CD8+ T cells from transgenic mice expressing OVA-specific TCR to track specific cellular interactions in vivo using the same approach that we used for studying ocular tolerance (McKenna, K.C., Y. Xu, and J.A. Kapp. J. Immunol. 169:5630-5637, 2002). If noscapine serves as an adjuvant, it may be used clinically to augment endogenous immune responses in tumor bearing recipients or in conjunction with tumor vaccines. Augmentation of anti-tumor immunity would be particularly valuable in preventing metastasis of the original tumor or re-emergence of a dormant tumor.

Christopher Klug, PhD

Dr. Klug's laboratory focuses on a number of interrelated projects that deal with the genetic control of hematopoietic stem cell (HSC) self-renewal and differentiation and how normal developmental programs are subverted in the context of acute leukemias. They are also interested in understanding the underlying molecular events that control lineage commitment decisions within the hematopoietic system. The regulatory factors that are under current investigation for controlling lymphoid-lineage specification from HSC include the interleukin 7 receptor, early B-cell factor and Pax5. Acute leukemia is studied by introducing commonly observed chromosomal translocations into mouse stem cells using retroviral vectors. Two of the translocations that we have modeled in mice, the inv(16) and the t(8;21), are found in 25% of acute myeloid leukemia (AML) cases in man. AML accounts for 80% of all human acute leukemia and is thought to be a disease that is sustained by an abnormal HSC population that also bears the translocation. In a recently published paper, we have shown that the t(8;21) translocation causes HSC to expand in vivo to numbers that are 30-fold greater than what is typically seen in normal mice. Current efforts are underway to understand how the t(8;21) is affecting HSC self-renewal using microarrays and RNA interference technologies. The group is also beginning to use animal models to test the efficacy of novel treatment approaches to acute leukemia.

Huan H. Nguyen, PhD

During the millions of years of coexistence with their hosts, viruses have learned how to manipulate our immune control mechanisms. One mechanism involves antigenic alteration that helps the virus expressing an altered antigen escape from existing host immune responses. However, a residual type of cross-reactive immunity remains, which offers certain level of immunity to the new viral variant. Dr. Nguyen and colleagues have studied in detail how the host circumvents the infection with novel viral variant. Heterosubtypic immunity (HSI) to influenza virus A infections is the classic model for this type of study. For instance, influenza viruses undergo periodic antigenic shifts in its two outer membrane glycoproteins, hemagglutinin (H) and neuraminidase (N), thereby abrogating cross-protective neutralization of different virus strains. However, infection with influenza virus of one subtype can induce a degree of cross-protection against subsequent challenge with other subtypes. This cross-protection between different subtypes of influenza A virus is mediated by HSI in the absence of preexisting virus neutralizing (VN) antibodies (Abs) to the challenge subtype. HSI has been thought to be mediated by serotype cross-reactive cytotoxic T lymphocytes (CTL), which recognize conserved epitopes of structural proteins, such as nucleoprotein (NP) or matrix (M) protein shared by influenza A virus subtypes. However, we have found recently that mice lacking CD8+ CTL are able to develop full HSI, while mice without B cells or CD4+ T cell failed to induce complete HSI. Gene expression analysis using oligonucleotide arrays (microarray) confirmed the importance of B cells in HSI and revealed that other components of the immune system play important roles in HSI. We are currently pursuing identification and characterization of novel components of immune system to understand the effector mechanisms of HSI to influenza virus A infections.

Other research interests include the immune responses to human papillomavirus (HPV) infections in cervical cancer (CC). CC represents the second most common cancer in women worldwide and is associated with HPV infections. Despite the high prevalence of HPV infections, the immunobiology of HPV infections is far from being fully understood. This is due to the innate complexities of mucosal immunity and the lack of a convenient and efficient in vitro system to recapitulate the HPV infectious cycle. However, the fact that patients who become immunocompromised have tumors that rapidly progress, suggests an important role for immune responses in control of HPV infection and therefore tumor growth. To better understand the role of the immune response for control of HPV infection, comprehensive studies on both mucosal and systemic immune responses to HPV infections in women with cervical carcinoma are in progress. Since HPV infection is necessary but not sufficient for development of CC, searching for other yet unidentified factor(s) using advanced technologies in molecular biology is being pursued by the laboratory.

Denise R. Shaw, PhD

Preclinical development of novel tumor vaccines.

Huang-Ge Zhang, DVM, MD, PhD

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Clinical/Translational Immunology

J. Edwin Blalock, PhD

Suresh B. Boppana, MD

Dr. Boppana’s laboratory is studying the pathogenesis of congenital cytomegalovirus (CMV) infections. Congenital CMV infection is the most frequent congenital infection and a leading cause of brain damage and sensorineural hearing loss in children. The focus of the work in our laboratory include: 1. Understanding the intrauterine transmission of CMV in women who were CMV seropositive before pregnancy. We recently showed that acquisition of a new CMV strain is associated with intrauterine transmission and damaging congenital infection in immune mothers. Our ongoing studies will attempt to define the role of maternal reinfection, maternal strain-specific immune responses and other factors in transplacental transmission and damaging congenital infections in infants born to immune mothers; 2. Definition of the mechanisms of hearing loss, in particular, the development of late onset and/or progressive hearing loss in children with congenital CMV infection. We are investigating the role of virus burden and characterizing the virus specific cellular immune responses in congenitally infected children to better delineate the pathogenesis of hearing loss in children with congenital CMV infection; 3. Understanding the virologic and immunologic characteristics of primary CMV infection.

S. Louis Bridges, Jr., MD, PhD

Genetic and racial/ethnic influences on susceptibility, severity, and treatment response in rheumatoid arthritis. We are currently examining the role of single nucleotide polymorphisms (SNPs) in genes encoding TNF-?, LT-?, TNF receptors, and other related proteins, as well as HLA DRB1 alleles, in clinical response of rheumatoid arthritis (RA) to the inhibitor etanercept. In addition, we are using the same strategy to identify genetic markers of treatment response or toxicity to the antifolate drug methotrexate. We are uniquely positioned in that we have access to several well-characterized cohort of patients with RA who have completed clinical trials or are part of registries. In addition, we are interested in racial/ethnic differences in disease severity of RA, defined by radiographic evidence of bony erosions and joint space narrowing. I am the co-Director of the NIH-funded Consortion for the Longitudinal Evaluation of African-Americans (A-A) with Early Rheumatoid Arthritis (CLEAR). This consortium is identifying and collecting 450 A-A with RA of less than 2 years disease duration and establishing a centralized clinical database, DNA, serum, and cell bank. The primary outcome will be the presence or absence of radiographic erosions of hands or feet at 3 years disease duration. The effect of polymorphisms in candidate genes will be analyzed in future studies. B Lymphocytes in Rheumatoid Arthritis and Chronic Hepatitis C Virus (HCV) Infection. Dr. Bridges has an active interest in the role of B lymphocytes in RA and HCV. In normal lymphoid organs, recombination activating genes (RAG)-1 and RAG-2 are expressed in a subset of germinal center B cells to allow replacement of autoreactive V gene sequences with non autoreactive V gene sequences, so-called receptor editing. Dr. Bridges and colleagues have demonstrated that this important mechanism of peripheral B-cell tolerance occurs in RA synovial B lymphocytes. This finding has important implications regarding the role of synovium as a lymphoid organ in RA and other chronic autoimmune diseases. Structures resembling germinal centers also occur in periportal tracts of liver in patients with chronic HCV. The role of these B cells in generating cryoglobulins, antibodies associated with vasculitis, are also being examined.

Donald J. Buchsbaum, PhD

Irshad H. Chaudry, PhD

Current research interests include determining the mechanisms responsible for cellular and subcellular alterations following soft tissue trauma, bone fracture, hemorrhage and sepsis. Additionally, the use of novel, readily available, FDA approved inexpensive therapeutic agents to attenuate such alterations in patients following trauma is planned. Other areas include evaluation of: (1) gender dimorphism and the mechanisms responsible for producing cardiovascular and hepatocellular dysfunction and immunological alterations following trauma-hemorrhage; (2) trauma-induced changes in the hypothalamus-pituitary-adrenal axis; (3) apoptosis of immune cells; and (4) wound healing. Specific research interests include determining the mechanism of regulation of estradiol levels by hypothalamic/pituitary factors, adrenals and steroidogenic enzyme activity and how differences in estradiol levels or the estradiol: androgen ratio due to the estrus cycle, ovariectomy, and age affect immune responses after trauma. Studies of T lymphocytes, macrophages and Kupffer cell functions using molecular biological techniques are being conducted to determine why low estradiol fails to maintain immune functions in aged females after trauma. The use of estradiol, Raloxifene, prolactin, metoclopramide, or flutamide to restore immune/cardiovascular functions following trauma should yield novel information and provide an innovative approach for improving the host responses and reducing mortality from sepsis following trauma in postmenopausal and in surgically ovariectomized patients with low estrogen activity. Additional interests encompass the mechanisms by which androgen depletion/androgen antagonists improve cardiac performance and other organ functions after trauma. These studies also examine whether androgen depletion/androgen antagonists affect the adrenals and modify the response of the heart, liver and vascular smooth muscle to catecholamines. The hemodynamic parameters and organ functions being measured include blood flow, circulating blood volume, cardiac output, left ventricular performance, vascular reactivity, liver, gut, adrenal and pulmonary functions. The integration of cardiac function with other organ functions and detailed mechanistic studies at the cellular and subcellular levels using physiological, pharmacological and molecular biology techniques to identify targets for novel treatment modalities using sex steroid antagonists/agonists or hormones should provide new information for the improved treatment of trauma victims with major blood loss and for decreasing the susceptibility to sepsis following trauma.

Noel K. Childers, DDS, MS, PhD

Dr. Childer's current studies involve investigations aimed at identifying safe and effective mucosal immunization delivery systems. Specifically, studies examine the characteristics of liposomes that are important in potentiating immune responses to orally or nasally administered S. mutans antigens. This involves in vitro studies of the physical characteristics of liposomal antigen preparations as well as in vivo studies into the uptake and processing of liposome preparations in rats. Following animals studies of the efficacy of liposomal S. mutans antigen vaccines, studies have been initiated for human FDA Phase I clinical trials studying the safety and immunogenicity of liposomal oral and nasal immunization. The overall goal of these studies are to identify a safe and effective oral immunization strategy which is protective against dental caries.

Clinical research interests also include studies to determine risk factors for oral complications in children with cancer and HIV infection. These studies have assessed various clinical and immunological factors involved in the development of oral lesions in medically compromised children. The goal of this research is to develop and test protocols that will prevent the occurrence or severity of oral complications in children identified to be at risk. Additionally, research efforts have involved assessment of the prevalence of dental disease in children as related to access to care. Related studies have assessed the effectiveness of dental sealants in prevention of dental caries using Medicaid claims as well as Jefferson County Department of Public Health records.

David T. Curiel, MD, PhD

David O. Freedman, MD

Dr. Freedman's research program encompasses four areas of investigation: 1) Development of global provider-based surveillance networks for characterization of infectious disease morbidity in travelers and migrants using innovative electronic communications modalities. Director of GeoSentinel, a CDC-funded global surveillance network of 33 travel/tropical medicine units on 6 continents; 2) Development of novel techniques for the clinical teaching of tropical medicine to graduate physicians from industrialized countries, on-site in the tropics while maintaining all traditional accreditation standards. Director of the Gorgas Courses in Clinical Tropical in Lima, Peru with 50 participants/years from 12-20 countries; 3) Development of novel strategies to track global trends in disease and occupational health risk among employees of multinational corporations; and 4) Development of a simple, low-cost diagnostic platform that performs multiple parallel bioassays (nucleic acid-based assays and immunoassays) at the point of care in the developing world using nanotechnnology.

Moon Nahm, MD

Dr. Nahm's laboratory is interested in vaccines against Streptococcus pneumoniae, an important human pathogen. Currently available pneumococcal vaccines use capsular polysaccharides themselves or the polysaccharides conjugated to carrier proteins. To evaluate these currently available vaccines, it is critical to be able to reliably measure the amount and protective capacities of the antibodies to capsular polysaccharides, which provide vaccine-induced protection. We have investigated the molecular structure and the protective capacity of the antibodies to pneumococcal capsular polysaccharides. His group has also improved and standardized the assays used to measure the protective capacity of these antibodies. To facilitate the adoption of these standardized assays worldwide, we are currently serving as the pneumococcal vaccine reference laboratory for the National Institute of Health and the World Health Organization.

Since the currently available pneumococcal vaccines have limitations, Dr. Nahm's laboratory is investigating pneumococcal lipoteichoic acid (LTA) as a new vaccine candidate. LTA is found on Gram-positive bacteria and is analogous to LPS from Gram-negative bacteria. LTA is an amphipathic molecule with a polysaccharide chain and two acyl chains. Because its purification has been difficult, its pathogenic role and its ability to stimulate the innate and adaptive immune systems are unknown. In view of this, they have developed a novel method of purifying LTA and are currently investigating its ability to stimulate innate immune responses as well as its role in pneumococcal adhesion to host cells. The group has shown that pneumococcal LTA stimulates cells via TLR2 and perhaps via the platelet-activating factor receptor as well. They are currently evaluating the role of LTA-induced lipid rafts in pneumococcal adhesion to host cells and its stimulation of these receptors.

Slevarangan Ponnazhagan, PhD

The major research interest of my lab is adeno-associated virus (AAV)-mediated gene therapy of human diseases. The areas that we are currently working with AAV vectors are anti-angiogenic gene therapy for solid tumors, dendritic cell-based vaccines for cancer immunotherapy, and gene therapy for metabolic bone diseases. In addition, the lab is also focused on basic biology of the vector and vector modifications to achieve high-efficiency gene transfer and targeting.

Tong Zhou, MD

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Fundamental Immunology

J. Edwin Blalock, PhD

R. Pat Bucy, MD, PhD

Dr. Bucy is interested in the regulation of immune responses by T cells, particularly the forms of regulation that develop in vivo in situations with chronic antigen presence. Conventional experimental systems have used model antigens given in discreet inoculations so that the clearance of antigen is the dominant overall control mechanism. In physiological situations such as solid organ transplantation, chronic viral diseases, and organ specific autoimmune diseases, antigen is usually not cleared, but the immune system develops various control mechanisms that limit immune damage. In addition to his role as the Director of the UAB Medical Scientist Training Program (joint MD/PhD training), Dr. Bucy's lab is engaged in a wide range of projects with a translational focus, that span the gamut of basic mechanistic studies in mice to active design of human clinical trials. Active current projects include use of TCR transgenic mice to study murine heart transplant tolerance, analysis of T cell population dynamics in response to various forms of immunization, studies of viral and cellular dynamics in SHIV infected Rhesus Macaques, and a substantial series of studies focused on therapeutic immunization of HIV infected people and assessment of changes in immune function in these people. In all of these systems, multiple techniques are used including flow cytometry, immunohistochemistry, cell culture techniques, production of novel transgenic mice, real-time RT-PCR,. and in situ hybridization analysis of viral and cellular RNA species.

Peter D. Burrows, PhD

Dr. Burrow's laboratory is interested in the development and function of B lymphocytes. Immunoglobulin gene rearrangements, as well as a number of poorly understood changes in gene expression, take place as cells progress through this differentiation pathway. We have been using both cellular and molecular approaches to characterize precursors of human B lineage cells and to identify novel genes whose expression is developmentally regulated. Defects in the expression of such genes could lead to immunodeficiency, whereas inappropriate expression might predispose a cell to malignant transformation. His lab has also begun to explore the function of the multifaceted cytokine, transforming growth factor-beta, in regulating B cell development and function and have identified a novel Fc receptor gene that appears to be expressed in the cytoplasm of germinal center B lymphocytes.

David D. Chaplin, MD, PhD

Cytokines of the TNF/lymphotoxin (LT) family signal the development of organized lymphoid tissues. Mice deficient in LT-alpha fail to form lymph nodes and Peyer's patches. They also show disturbed spleen white pulp structure, with failure to segregate B cell and T cell zones, and to form primary B cell follicles with clusters of follicular dendritic cells (FDC). TNF also is required for the formation of primary B cell follicles. Infusion of purified LT-expressing B cells restores development of FDC and primary follicle structure. This demonstrates an unexpected role of B cells as organizers of the lymphoid tissue microenvironment in which the B cells themselves ultimately mature. Normal lymphoid architecture is particularly important for the development of mature antibody responses. This manifests itself in failure of antibody affinity maturation in LT-deficient mice, including failure both to form and to express B cell memory responses. Future studies will define additional signals that establish the normal structure of lymphoid tissues and will define the ways this structure supports a properly regulated immune responses, particularly memory B cell responses. Other studies investigate cytokines as regulators of tissue inflammatory responses, particularly allergic inflammation. These studies have shown that in the skin, IL-1 beta is required for recognition that new antigens have penetrated the epidermis. Without IL-1 beta, there is no activation of Langerhans cells (LC), and these LC fail to deliver antigens from the epidermis to draining lymph nodes. These studies have also shown that in the lungs Th2 cell-dependent allergic inflammation is characterized by an influx of both Th1 and Th2 cells. In fact, Th1 and Th2 cells cooperate to elicit the eosinophil-predominant infiltrates that are characteristic of this response. The long-term aim of these studies is to define the signals that initiate recruitment of helper T cells to peripheral tissues and that modulate the character of the inflammatory response. A major signal for this recruitment is locally produced TNF, acting largely through activation of expression of endothelial adhesion proteins that then support Th cell recruitment.

Randall S. Davis, MD

Dr. Davis’ laboratory investigates pathways of normal lymphocyte differentiation to determine the mechanisms that contribute to lymphomagenesis, autoimmunity and immunodeficiency. This work largely focuses on an ancient family of Ig-like receptors with tyrosine-based activating or inhibitory signaling potential. A search for possible Fc receptor relatives identified several novel Ig superfamily genes in humans and mice termed Fc receptor-like molecules (FcRL). FcRL family members are preferentially expressed in B lymphocytes and differentially identified in B lineage malignancies. Follow-up studies have identified eight human and seven mouse relatives in total. The recognition of this family has significant implications for understanding connections between innate and adaptive humoral immunity, the regulation and terminal differentiation of B cells into memory and plasma cells, and possibly, the pathogenesis of B cell malignancies and autoimmunity. Their expression patterns, signaling potential, ligands, and translational potential are areas of active investigation.

Louis Justement, PhD

Analysis of the Molecular and Functional Role of the Adaptor Protein HSH2
Studies are ongoing to elucidate the functional role that the adaptor protein HSH2 plays in regulating B cell biology. HSH2 is selectively expressed in cells of the B lineage and its expression is up-regulated in response to agonists that promote B cell survival and differentiation, including CD40L, BLyS, LPS and CpG DNA. Studies have demonstrated that HSH2 is able to block BCR-induced apoptosis in the WEHI-231 B cell line, suggesting that this adaptor is expressed as part of a pro-survival program. Future studies will: 1) Identify important regions/motifs of HSH2 that are involved in its pro-survival function; 2) Identify interacting proteins in B lymphocytes and assess their functional importance; and 3) Generate transgenic and conditional knockout mice to examine the importance of HSH2 in regulation of B cell development, activation and differentiation.

Analysis of the Molecular and Functional Role of the Transmembrane Receptor Trem-Like Transcript 2 (TLT2) The genes encoding mouse and human TLT2 were cloned in our laboratory. Subsequent experiments demonstrated that TLT2 is expressed on B cells, neutrophils and macrophages. With respect to the B lineage, TLT2 is expressed early during development, prior to the BCR. Although TLT2 is expressed on all B cells in the periphery, its level is higher on transitional, marginal zone and B-1 B cells when compared to follicular B cells. Expression of TLT2 can be detected on peritoneal macrophages but not on macrophages in other tissues. Finally, TLT2 is expressed on neutrophils and is significantly up-regulated in response to inflammatory stimuli such as LPS. Future studies will: 1) Assess the functional role of TLT2 in immune responses to infectious organisms; 2) Identify the ligand(s) for TLT2 using molecular and biochemical approaches; and 3) Identify interacting signal transduction proteins and associated pathways that mediate TLT2 function in immune cells.

Analysis of Virulence Factors Produced by Mycobacterium tuberculosis
Mycobaterium tuberculosis (MTb) is a serious world-wide pathogen that has the ability to survive within host phagocytic cells such as macrophages (MØ). It has been shown that virulent strains of MTb actually secrete a wide range of proteins or virulence factors that presumably alter host cell function. Studies are ongoing to examine the functional role of two secreted virulence factors produced by MTb. The first protein being studied is a protein tyrosine phosphatase called mPtpb, which alters host cell function presumably by dephosphorylating one or more intracellular substrates. Studies will: 1) Identify the mechanism responsible for secretion of mPtpb from MTb; 2) Identify substrates of mPtpb; and 3) Determine the effect that mPtpb has on MØ function. Another protein that is secreted by MTb, called enhanced intracellular survival (Eis) protein, is a putative acetyltransferase. Thus, Eis may regulate transcription in host MØ through its ability to acetylate substrates in the nucleus. Studies will: 1) Determine if Eis is a functional acetyltransferase; 2) Identify substrates in MØ that are acetylated by Eis; and 3) Determine the functional effect that substrate acetylation has on MØ function.

John F. Kearney, PhD

The overall research plans of his laboratory are aimed at discovering fundamental cellular and molecular mechanisms involved in the development the development of T and B lymphocytes. The development and establishment of the B cell repertoire is the net result of both genetic and environmental forces. These are dynamic processes beginning with the earliest expression of immunoglobulins in fetal life and continuing throughout life. Immunoglobulin transgenic and knockout mice models are used to define the antigens involved in the selection process, to determine the phenotypes of B cells at different states of differentiation and selection, and to seek out the fetal and adult anatomical sites where positive and negative selection of B cells occurs. The impact of terminal deoxynucleotidyl transferase activity (Tdt) expression on the diversity of immunoglobulin CDR3 regions and the subsequent effects on fetal perinatal and adult B cells, is being addressed by the use of transgenic mice in which N region additions have been introduced during stages of B cell development when such additions are normally absent or minimal. The molecular and cellular differences between B cell subsets are compared in studies on precursor/progeny relationships using newly developed monoclonal antibodies as cellular markers, and the use of a variety of transgenic and knockout mice.

Based on his knowledge of the mechanisms of immune responses in mice he is also involved in understanding the mechanisms of B. anthracis spore-host interactions to facilitate the subsequent design and development of preventive, interventive and diagnostic procedures of the causative organism of Anthrax. He is using mouse models to define protective immune mechanisms against spore entry and to define mechanisms of immunopathology and immune evasion of the ungerminated spores in the host. Mechanisms of spore attachment, routes of spore entry into the body and spore -host interactions within the immune system are being studied. Emphasis is placed on understanding mechanisms of spore entry and immunoregulation in the skin, gastrointestinal tract, respiratory system and also spore passage in the blood. The experiments outlined in this area of research will aid in our understanding of the role that fetal and neonatal B cells play in establishment and maintenance of the normal immune system and will provide insight into their roles in autoimmune diseases, B cell neoplasia, immunodeficiency diseases and the development of more efficient vaccines against anthrax and other disease producing organisms.

Hiromi Kubagawa, MD

The main goal of Dr. Kubagawa's research is to define the development and differentiation of lymphoid- and myeloid-lineage cells in the context of exploring the diseases of the immune system. Several cell surface molecules expressed by these cell types are being studied with regard to their structure and function in adaptive and innate immunity. My colleagues and I are currently focusing on two Fc receptor-related molecules: (i) paired immunoglobulin-like receptors, PIR-A (A for activating) and PIR-B (B for braking or inhibitory), and (ii) the Fc receptor for IgA and IgM (Fcalpha/muR).

Previous findings in Dr. Kubagawa's lab and others' led to the hypothesis that PIR-A and PIR-B play specific regulatory roles in host defense, including inflammatory, coagulative, antigen-presenting, allergic and humoral immune responses. This hypothesis is currently being tested in the following aims: (i) to identify the PIR ligands and (ii) to determine the functional consequences of PIR-B deficiency in a gene-targeted mouse model.

After the serendipitous discovery of a murine cDNA that encodes a protein able to bind the Fc portion of both IgA and IgM, designated as Fcalpha/muR, Dr. Kubagawa's lab has sought to characterize the tissue distribution, structural signi and function of this receptor. Preliminary findings using receptor specific mAb and RT-PCR analysis indicate an interesting cellular distribution of the human Fcalpha/muR: germinal centers with the appearance of follicular dendritic cells (FDC) in tonsils, proximal tubular epithelial cells in kidneys and Paneth cells in small intestinal crypts. Another remarkable finding is that human Fcalpa/muR is expressed by a small subpopulation of B cells that reside in tonsils, but not in the circulation; hence the expression pattern differs from that of mouse Fcalpha/muR, which is expressed by both circulating and resident B cell populations. A novel splice variant that may encode a soluble form of Fcalpa/muR has been identified in the kidney. These findings led to the hypothesis that Fcalpha/muR plays multiple functional roles depending upon the cell types expressing it. Fcalpha/muR on FDC may trap IgM or IgA immune complexes and present the intact antigens to B cells in germinal centers. Fcalpha/muR expression by B cells may be closely linked with cellular activation. Fcalpha/muR in renal tubular epithelial cells and intestinal Paneth cells on the other hand may play a protective role at portals of entry for antigens and microorganisms. This hypothesis is currently tested by the following aims: (i) to determine the function of the membrane-bound Fcalpha/muR, (ii) to define the newly identified Fcalpha/muR splice variant as a soluble form of the receptor, and (iii) to employ an Fcalpha/muR-deficient mouse model to explore the in vivo function of the Fcalpha/muR.

Dennis F. Kucik, MD

White blood cell adhesion to blood vessel walls constitutes an essential early step in the defense against infection, without which an immune response cannot develop. On the other hand, too much adhesion can lead to atherosclerosis and other major health problems. Using a flow-cell system that mimics conditions in the blood vessel, dynamic adhesion is analyzed by high-time-resolution digital imaging and computer analysis. Cultured endothelium and leukocytes from knockout mice enable us to define the functions of specific adhesion molecules. We also use time-lapse imaging of migrating cells to understand endothelial wound healing, and a laser-tweezers-based system to measure adhesion molecule rearrangement on living cells. This work is also important to understand how cancer cells metastasize to distant sites via the bloodstream.

John D. Mountz, MD, PhD

Harry W. Schroeder, Jr., MD, PhD

Ultimately, it is the identity and specificity of the lymphocyte antigen receptor that determines the nature of the immune response to antigen. The mechanisms that underlie the diversification of the B- and T-cell antigen receptor repertoires appear to generate receptor diversity at random. However, repeated examples of near to absolute identity of receptor sequences between individuals suggest the existence of genetically programmed constraints that may be designed to bias the immune system to produce preferred, and perhaps optimal, repertoires. The implication is that violation of these programs could lead to immune dysfunction, and thus to disease. To test this hypothesis, we are developing mouse models wherein we force expression of altered, polyclonal repertoires that violate normal constraints on antigen receptor sequence or structure. In the first of these mice, where we have forced expression of arginine, histidine and asparagine in the HCDR3 interval of immunoglobulin H chains, we observed somatic selection against antigen binding sites that contained an excess number of these charged amino acids, yet the system ultimately failed to recapture the tyrosine and glycine residues normally encoded by wild-type germline sequence. B-cell development was impeded, immunity to influenza virus was impaired, and expression of IgG anti-DNA antibodies was enhanced. These results support the view that optimal distinction between self and non-self is a product of evolutionary selection.

Laura Timares, PhD

Specialized antigen-presenting cells, termed dendritic cells (DC), are critical components of the immune system. They are unique in their ability to instruct and activate a naive immune system to mount a particular kind of antigen-specific response. Because of this important function, DC hold tremendous promise as immunotherapeutic agents. The key will be in understanding how to effectively harness and control their abilities in vivo. By engineering DC, through the introduction of targeted genes, we may be able to directly control how immune responses are generated. The development of this technology will initially involve research in two areas: (1) the characterization of the immunogenic or tolerogenic properties generated by gene-modified DC and (2) the optimization of gene targeting into dendritic cells in vivo.

We are studing DC lines, as well as primary DC, to develop cell-engineering strategies that permit predictive control of DC function. The behavior of these genetically-modified DC in vivo is studied in mouse model systems that contain transgenic T cells. This model system permits the analysis of the interactions between engineered LC lines and naïve or differentiated transgenic T cells in vivo. Cellular and molecular approaches are used to study the fate of engineered DC and their impact on T cell activation and differentiation.

Recently, we have identified genes that specifically regulate DC apoptosis. DCs that do not express certain pro-apoptotic genes are resistant to T cell-induced death, and can orchestrate augmented immune responses. How such apoptosis-resistant DCs induce enhanced T cell responses, and what mechanism is used by T cells to induce DC death is under current investigation.

Trygve O. Tollefsbol, PhD

Telomerase, a ribonucleoprotein that maintains the ends of chromosomes, has been the subject of intense investigation due to its potential role in aging and neoplastic transformation. Human chromosomes contain telomeric 5'-TTAGGG-3' repeats for up to 15 kilobases which help preserve chromosomal integrity by preventing rearrangements, degradation and end-to-end fusions. Telomerase synthesizes telomeres and is of great interest because the absence of this enzyme, due to its down-regulation in early embryonic cellular differentiation, appears to contribute to cellular senescence. In normal somatic cells, each cell division is associated with the loss of 30-150 bps of telomeric DNA. This attrition continues with cellular proliferation until a critical minimum length associated with growth arrest and cellular senescence occurs. Strong support for a central role for telomerase in aging has come from studies in which differentiated cells transfected with vectors expressing the human telomerase catalytic subunit, hTERT, have been immortalized. These findings point to hTERT expression as the rate-limiting factor in telomerase activity and bring the study of hTERT gene expression to the forefront of telomerase and aging research. Moreover, cancer increases markedly during the aging process and telomerase is up-regulated in up to 95% of cancer cells which show no net loss of average telomere. Telomerase activity can be detected in the early stages of most common cancers; high levels of telomerase correlate with a poor prognosis for several types of cancers; and ablation of telomerase expression leads to telomeric attrition and growth inhibition of cultured neoplastic cells. It is clear that telomerase is linked to aging and cancer but the mechanisms controlling telomerase in these processes are unknown and constitute the focus of our work.

1) Regulation of the telomerase gene in aging cells. Telomerase is down-regulated during embryonic differentiation and reactivated in most cancer and immortalized cells indicating that this enzyme is reversibly controlled. In all examined cases, hTERT mRNA expression parallels telomerase activity, strongly implicating transcriptional mechanisms of telomerase regulation. Our studies are focusing on the mechanisms of telomerase gene control in aging cells. We have found that the hTERT gene is down-regulated in differentiating human teratocarcinoma cells through mechanisms such as histone deacetylation and DNA methylation. The promoter region of hTERT is currently being analyzed to elucidate the causes for its down-regulation during early embryonic differentiation.

2) Control of telomerase in neoplastic transformation. Although telomerase is active in most cancer cells and appears to be involved in the genesis of neoplastic transformation, the mechanisms of telomerase reactivation in cancer cells are unknown. Our studies are focusing on the role of c-Myc/Mad1 in control of hTERT gene regulation in cancer cells and the role of chromatin alterations and DNA methylation in modulating this process.

3) Cell Senescence Culture Facility. Our laboratory directs a Cell Senescence Culture Facility that provides various types of aging cells to investigators nationwide. This facility is only one of a few in the United States and is designed to not only facilitate studies of aging, but to also participate in new investigations in the mechanisms of cellular aging and age-related diseases such as cancer.

Mark R. Walter, PhD

Small protein molecules called cytokines play a large role in cellular communication. The cytokines transmit their signals by binding with high affinity to specific cell surface receptors. The cytokine-receptor interactions result in receptor clustering on the cell surface which initiates cellular responses. Using protein crystallography, the lab is defining the structural details of cytokines and cytokine-receptor interactions. Further studies are looking at the intracellular structural changes that occur upon receptor clustering. Systems of study include the interferons (a and g), interleukin-10 and interleukin-22. Remarkably, many viruses have captured these molecules in their genomes to subvert host immune function. The three-dimensional models obtained from our crystallographic studies provide a basis for additional biochemical and cell biology experiments that will assist in the production of "designer cytokines" with altered activities. These molecules have tremendous potential as new pharmaceuticals for treating several types of cancer, arthritis, AIDS, and other infectious diseases.

Casey Weaver, MD

The research in my laboratory concerns the mechanisms by which CD4 T cells control adaptive immunity. Major current projects are: the generation and characterization of transgenic and knock-in mouse models for tracking T cell fate during CD4 effector and memory T cell development (Saparov et al., Immunity 11:271, 1999; Hurez et al., J. Exp. Med., 198:123, 2003); studies defining mechanisms that induce development of the Th17 effector lineage (Harrington et al., Nature Immunology 6:1123, 2005); characterization of mechanisms by which dysregulation of CD4 T cells leads to inflammatory bowel disease (Iqbal et al., J. Exp. Med., 195:71, 2002; Elson et al., Curr. Opinion in Gastroenterology 20:360, 2004); delineation of the adhesion pathways that control effector T cell trafficking (Mangan et al., Amer. J. Pathology, in press); and, characterization of the genetic elements that regulate cytokine gene expression in Th1 and Th17 cells (Dzialo-Hatton et al., J. Immunol. 166:4534, 2001).

Huang-Ge Zhang, DVM, MD, PhD