Role of the NF-kB Pathway in the Pathogenesis of Human
Disease States Pp. 287-296
Yumi Yamamoto and Richard B.
Gaynor
Molecular Characterization of the T Cell Repertoire Using
Immuno-scope Analysis and its Possible Implementation in Clinical Practice Pp. 297-304
F. Ria, P. van den Elzen L. T.
Madakamutil, J.E. Miller E. Maverakis
and E. E. Sercarz
Alternative Routes for the Formation of Immunochemically
Distinct Advanced Glycation End products In Vivo Pp. 305-315
Masayoshi Takeuchi and Zenji
Makita
Molecular Steps of Tumor Necrosis Factor Receptor-Mediated
Apoptosis Pp. 317-324
S. Gupta
Gene Therapy for Diabetes Mellitus Pp. 325-337
T. Yamaoka
Mechanisms of T Cell Receptor Antagonism: Implications in
the Treatment of Disease Pp. 339-355
Bonnie N. Dittel
Insights into the Pathogenesis of Type 1 Diabetes: A Hint
for Novel Immunospecific Therapies Pp.
357-378
Sofia Casares and Teodor-Doru Brumeanu
Pediatric Autoimmune Liver Diseases: The Molecular Basis of
Humoral and Cellular Immunity Pp. 379-389
Li Wen, Yun Ma, Dimitrios P.
Bogdanos, F. Susan Wong, Andrew Demaine, Giorgina Mieli-Vergani and Diego
Vergani
Directed Gene Modification via Triple Helix Formation Pp. 391-399
Linda Gorman and Peter M.
Glazer
[Back
to top] Role of the NF-kB Pathway in the Pathogenesis of
Human Disease States
The NF-kB family
consists of a group of inducible transcription factors, which regulate immune
and inflammatory responses and protect cells from undergoing apoptosis in
response to cellular stress. A number of signal transduction cascades can
activate the NF-kB pathway
to result in the translocation of the NF-kB proteins from the cytoplasm to the nucleus where they activate
the expression of specific cellular genes. In this review, we discuss cellular
genes, which are regulated by NF-kB and disease states, which are associated with constitutive
activation of the NF-kB pathway.
Strategies to prevent prolonged activation of the NF-kB pathway are also discussed.
[Back
to top] Molecular
Characterization of the T Cell Repertoire Using Immuno-scope Analysis and its
Possible Implementation in Clinical Practice
T lymphocytes play a central role in the pathogenesis of a large
number of human conditions including autoimmunity and graft rejection. Although
T cells are key players in mounting immune responses, the assessment of T cell
repertoires has yet to find an important role in clinical decision-making. In
this review, we discuss the “immunoscope” technique and its potential
diagnostic role in a variety of clinical scenarios. This is an RT-PCR based
approach that subdivides a bulk T cell population (i. e. from blood, lymph,
spleen, or tissue) into approximately 2800 groups based upon rearranged
variable beta (Vb)/joining
beta (Jb) gene
segments and the resulting length of the T cell receptor’s (TCR’s) third
complementarity determining region (CDR-3). This extensive subdivision, or
focusing, allows clonal expansions to be directly observed. Such a fine-tuned
analysis has revealed previously unappreciated aspects of the T cell
repertoire. For instance, an antigen-specific immune response can be divided
into both public and non-public components. The non-public repertoire contains
the majority of the expanding T cells which are unique to the individual
(private), or shared by only some (semi-private), while “public” T cells can be
found responding to the antigenic determinant in every individual. Although
they are often a minority of the response, the public T cell repertoire seems
to play a more important role in defining, as well as driving, the overall
immune phenotype in the animal. Immunoscope analysis has identified public and
non-public responses in human pathologies, such as multiple sclerosis. The
ability to characterize the driver T cells dictating the state of
immunity/autoimmunity in individual patients will be an important step towards
understanding autoimmunity and designing effective treatment for a variety of
conditions including rheumatoid arthritis and multiple sclerosis. We review the
current literature involving public and non-public repertoires and discuss the
prospect that immunoscope analysis may play a central role in the study and
perhaps the management of human autoimmune diseases, and cancer.
.
[Back
to top] Alternative
Routes for the Formation of Immunochemically Distinct Advanced Glycation End
products In Vivo
The advanced stage of the glycation process (also called the
“Maillard reaction”) that leads to the formation of advanced glycation
end-products (AGEs) plays an important role in the pathogenesis of angiopathy
in diabetic patients and in the aging process. AGEs elicit a wide range of
cell-mediated responses that might contribute to diabetic complications,
vascular disease, renal disease, and Alzheimer's disease. Recently, it has been
proposed that AGE are not only created from glucose per se, but also from
dicarbonyl compounds derived from glycation, sugar autoxidation, and sugar
metabolism. However, this advanced stage of glycation is still only partially
characterized and the structures of the different AGEs that are generated in
vivo have not been completely determined. Because of their heterogeneity and
the complexity of the chemical reactions involved, only some AGEs have been
characterized in vivo, including N-carboxymethyllysine (CML), pentosidine,
pyrraline, and crosslines. In this article, we provide a brief overview of the
pathways of AGE formation and of the immunochemical methods for detection of
AGEs, and we also provide direct immunological evidence for the existence of
five distinct AGE classes (designated as AGE-1 to -5) within the AGE-modified
proteins and peptides in the serum of diabetic patients on hemodialysis. We
also propose pathways for the in vivo formation of various AGEs by glycation,
sugar autoxidation, and sugar metabolism.
.
[Back
to top] Molecular Steps of Tumor Necrosis Factor Receptor-Mediated
Apoptosis
S. Gupta
Until recently it was believed that TNF-induced apoptosis is
mediated exclusively by TNF-RI because TNF-RII lacks death domain. However, it
has been demonstrated that TNF-RII enhances TNF-RI-mediated apoptosis. In this
review, I have discussed the evidence and mechanisms by which TNF-RII regulates
TNF-a-induced apoptosis. A role of
RIP is emphasized and novel mechanisms of FLIP-mediated inhibition of apoptosis
are discussed. In addition, various mechanisms of TNF-induced activation of
mitochondrial pathway of apoptosis have been reviewed.
[Back
to top] Gene Therapy for Diabetes Mellitus
There are diverse strategies for gene therapy of diabetes
mellitus. Prevention of b-cell autoimmunity is a specific gene therapy for
prevention of type 1 (insulin-dependent) diabetes in a preclinical stage,
whereas improvement in insulin sensitivity of peripheral tissues is a specific
gene therapy for type 2 (non-insulin-dependent) diabetes. Suppression of b-cell
apoptosis, recovery from insulin deficiency, and relief of diabetic
complications are common therapeutic approaches to both types of diabetes. Several approaches to insulin replacementby
gene therapy are currently employed: 1) stimulation of b-cell
growth, 2) induction of b-cell differentiation and regeneration, 3) genetic
engineering of non-b cells to produce insulin, and 4) transplantation of
engineered islets or b cells. In type 1 diabetes, the therapeutic effect of b-cell
proliferation and regeneration is limited as long as the autoimmune destruction
of b cells continues. Therefore, the utilization of engineered
non-b cells free from autoimmunity and islet transplantation
with immunological barriers is considered potential therapies for type 1
diabetes. Proliferation of the patients’ own b cells and
differentiation of the patients’ own non-b cells to b cells
are desirable strategies for gene therapy of type 2 diabetes because immunological
problems can be circumvented. At present, however, these strategies are
technically difficult, and transplantation of engineered b cells
or islets with immunological barriers is also a potential gene therapy for type
2 diabetes.
[Back
to top] Mechanisms of T Cell Receptor Antagonism: Implications in
the Treatment of Disease
The adaptive immune response is often required for the successful clearing of infectious pathogens. Antigen presenting cells (APC) present peptide antigens derived from pathogens to T cells via major histocompatibility complex (MHC) molecules. T cells then become activated and differentiate into effector cells with the capacity to kill infected cells or to induce an anti-pathogen antibody response. In autoimmunity, this T cell response is directed against self-antigens and often leads to deleterious effects on specific tissues. Likewise, T cell responses to allogeneic MHC molecules in transplants also lead to pathology. By introducing subtle changes in the antigenic peptide amino acid content, T cell activation can be inhibited, thereby preventing T cell effector functions. This strategy of TCR antagonism has been used successfully in vitro and in vivo to inhibit models of autoimmunity and allorecognition. In addition, a variety of pathogens that often result in chronic disease following infection, also have seemingly evolved natural mechanisms to inhibit T cell responses by antagonism. These microorganisms express natural variants of certain proteins, that when presented to T cells have the capacity to specifically inhibit T cell responses by functioning as antagonists or by modulating the nature of the T cell response. The understanding of how pathogens mediate this inhibition in vivo will be beneficial to ongoing studies in both autoimmunity and transplantation aimed at suppressing the harmful immune response, thereby controlling disease. TCR antagonism seems to have the potential to be used therapeutically to prevent or inhibit an undesired T cell response that will ultimately lead to disease.
[Back
to top] Insights into the Pathogenesis of Type 1 Diabetes: A Hint
for Novel Immunospecific Therapies
Type 1 diabetes is an organ-specific autoimmune disease whose incidence is increasing worldwide. At present, there is no effective therapy to prevent or cure this disease. The genetic background (MHC and non-MHC genes) and environmental factors (pathogens, drugs, and diet) are critical for the initiation of the autoimmune response against the pancreatic b-cells. Recognition of the pancreatic autoantigens by T cells in a predetermined environment of antigen-presenting cells, costimulation, and cytokines is crucial for the selective activation of diabetogenic or protective/regulatory T cells. Once the autoimmune process is triggered, epitope spreading and sustaining the autoimmune responses by continuous antigen stimulation leads to expansion of effector cells, which launch the attack on the b-cells. Despite of some controversy, most of the studies in humans and animal models suggest that CD4 (Th1) T cells are directly involved in the autoimmune attack by secretion of pro-inflammatory cytokines and recruitment of cytotoxic CD8 T cells. Secretion of anti-inflammatory cytokines by Th2 cells is protective against the disease. Therapy with peptides derived from major target antigens, such as glutamic acid decarboxylase 65 or proinsulin, can prevent the disease in animal models by rising protective Th2 cells. Herein, we review the recent progress in the immunopathogenesis of Type 1 diabetes and insights into the development of new diagnostic tools and antigen-specific immunomodulators, such as MHC-peptide chimeras.
[Back
to top] Pediatric Autoimmune Liver Diseases: The Molecular Basis of
Humoral and Cellular Immunity
Pediatric autoimmune liver disease is mainly represented
by two similar liver disorders: autoimmune hepatitis (AIH) and autoimmune
sclerosing cholangitis (ASC), both characterized by hypergammalobulinemia,
interface hepatitis and the presence of a wide range of circulating
autoantibodies. Although similar features are seen in AIH and inflammatory
bowel disease, histological biliary changes are more common in ASC. In addition
to their role as diagnostic markers, autoantibodies, such as anti-extractable
nuclear antigen (ENA) antibodies and liver kidney microsomal antibody type 1
(LKM1) may be involved directly in inducing aggressive liver diseases. Although
the cellular immune response in pediatric autoimmune liver disease has been
less intensively investigated than humoral immunity, the importance of antigen
specific T cells has been explored. Both ab
and gd T cells derived from either
peripheral blood or liver biopsies have highly heterogeneous TCR gene usage and
cytolytic activity has been demonstrated. There have been attempts to seek
triggers of liver autoimmunity and several sequences shared in common between
autoantigens and hepatotropic viruses, namely hepatitis B, C and
cytomegalovirus have been identified. The presence of cross-reactivity between
homologous sequences, especially between HCV and cytochromes, supports the
possibility that molecular mimicry plays a role in the induction of
autoantibodies and autoreactive cytotoxic T cells.
[Back
to top] Directed Gene Modification via Triple Helix Formation
Linda
Gorman and Peter M. Glazer
The ability to selectively target mammalian genes and disrupt or restore their function would represent an important advance in gene therapy. Mutation of a single nucleotide can often result in a non-functional gene product. Reversion of defective genes to their correct sequences could lead to permanent cures for patients with many genetic diseases. Molecules such as triplex forming oligonucleotides (TFOs) and peptide nucleic acids (PNAs) are currently being employed to bind to double-stranded DNA.Efficient targeting of genomic DNA with these molecules will be the initial step in gene modification.