Background/Purpose:
JIA is the banner diagnosis for a heterogenous group of rheumatic conditions characterized by local inflammation and destruction of the joint space and systemic manifestations. ...Pro‐inflammatory cytokines derived from T cells are considered effectors of disease. Recent data has shown that some of these cytokines come directly from a distinct subset of T cells expressing CD31, an adhesion molecule expressed by granulocytes and endothelial cells. In the present work, we examined whether the array of cytokines in blood and synovial fluid of patients are the same array produced by T cells activation through CD31 ligation independent of the TCR. We propose that CD31‐driven cytokine production by T cells is a self‐perpetuating mechanism of local and systemic inflammation in JIA.
Methods:
Following informed consent/assent, blood and/or synovial fluid were collected from patients with oligoarticular and polyarticular JIA. Similar blood samples were also collected from healthy subjects. Cytokine composition of the plasma and/or fluid were subjected to multiplex analysis using the Luminex platform. Phenotypes of mononuclear cells in blood and synovial fluid were examined by multicolor flow cytometry. Drawing from the results of the Luminex assay, receptor crosslinking bioassays using primary CD31+ T cells (in blood and/or synovial fluid) and CD31+ T cell lines were conducted. Cytokine production by these cells were assessed by flow cytometry and/or by Luminex.
Results:
The overall cytokine signature of JIA characterized by the dominance of IL‐6, IL‐10 and TNFα. Unexpectedly, patients with oligoarticular disease showed higher levels of IFNγ and IL‐17 family cytokines than those with polyarticular disease. Both types of patients however showed a similar cellular signature characterized by the preponderance of T cells deficient in CD4, CD8, and CD28, but expressing CD31. Results of CD31 cross‐linking bioassays, using either specific antibody or its recombinant ligand CD38, showed high levels of induction of IL‐2, IL‐17 and IFNγ. Specificity of CD31‐driven, TCR‐dependent cytokine production was verified by similar bioassays using somatic somatic T cell line mutants Loucy and JRT3 that lack TCR and TCR/CD3, respectively, but are both CD31+. The observed cytokine production was associated with the phosphorylation of the signaling substrates ZAP70, cAbl, and p65‐NFKB.
Conclusion:
Our data show that the cytokine signature of oligoarticular JIA appears distinct with the dominance of IFNγ and IL17. TCR independent, CD31‐driven induction of these cytokines suggests maladaptive T cell function in JIA. Further investigation on the relevance of IFNγ and IL‐17 to disease activity/clinical outcomes, and the CD31 signaling pathway will pave way to innovations in immunotherapy in JIA.
To evaluate the disease-modulating role of HLA-DR2 and DR3 molecules, which have been associated with systemic lupus erythematosus, a humanized mouse model was examined. HLA-DR2 (DRB1*1502)- and DR3 ...(DRB1*0301)-transgenic mice were backcrossed to the New Zealand Mixed 2410 (NZM 2410, H2(z)) strain. Seventh generation DR2 and DR3 transgene-positive animals along with their transgene-negative littermates and the parental strain NZM2410 were monitored for proteinuria, azotemia, autoantibody production, development of nephritis, and mortality. The results showed no significant differences in proteinuria, azotemia, or mortality between the backcrosses with and without HLA-DR2 or HLA-DR3. However, the genetic analysis of different backcrosses showed that heterozygosity at the endogenous H2-E locus (E(z)/E(b)) was strongly linked with acceleration of lupus nephritis in both HLA-DR2 and HLA-DR3 transgenics. More importantly, the presence of the HLA-DR2, but not the HLA-DR3, transgene significantly enhanced the production of anti-dsDNA, but not anti-ssDNA, anti-histone-dsDNA complex, or anti-histone, Abs. In contrast, neither HLA-DR2 nor HLA-DR3 influenced the development of glomerulonephritis or the degree of immune complex deposition. Moreover, nephritic kidneys from mice with and without HLA-DR2 or HLA-DR3 transgenes showed similar patterns of cytokine expression. Collectively, these findings provide molecular evidence that the association of HLA-DR2 or HLA-DR3 with lupus susceptibility is related to the type of autoantibody rather than to disease mortality. The use of a humanized mouse model provides a way of dissecting the roles of human MHC genes in systemic lupus erythematosus pathogenesis.
Biology of T lymphocytes Vallejo, Abbe N; Davila, Eduardo; Weyand, Cornelia M ...
Rheumatic diseases clinics of North America,
02/2004, Letnik:
30, Številka:
1
Journal Article
Recenzirano
T cells constitute one arm of the adaptive immune system. The accumulating information on various aspects of T-cell biology shows the intricacies in the regulation of immune responses. How we ...translate the cellular and molecular details of this regulation into innovation and development of therapies for disease management remains a fundamental, but exciting, challenge.
Objective
Juvenile dermatomyositis (DM) is an autoimmune disease of childhood characterized by lesions in skin and muscle that are populated by plasmacytoid dendritic cells (PDCs) and lymphocyte ...infiltrates. We undertook this study to examine the cellular composition, organization, and molecular milieu of the cellular infiltrates in muscle in juvenile DM and to correlate the infiltrates with clinical disease manifestations.
Methods
Since PDCs and lymphocyte foci express CCL19 and CCL21, we investigated for in situ formation of lymphoid microstructures that could be sites of extranodal immune activation.
Results
Analyses of muscle biopsy samples from children with new‐onset juvenile DM showed 3 categories of lesions: diffuse infiltrates, lymphocytic aggregates lacking follicle‐like organization, and follicle‐like structures. The last of these exhibited elements of classic lymphoid follicles, including networks of follicular dendritic cells and high endothelial venules. They also expressed high levels of CXCL13 and lymphotoxins known to support lymphoid organogenesis. There were also resident naive CD45RA+ T cells and maternally derived B cells and PDCs. Patients with diffuse infiltrates or lymphocytic aggregates were responsive to standard therapy with steroids and methotrexate, but those with follicle‐like structures tended to have severe disease that required additional agents such as intravenous Ig or rituximab.
Conclusion
These data suggest that lymphoneogenesis is a component of the early disease process in juvenile DM. Ectopic lymphoid structures could indicate a severe course of disease; their early detection could be a tool for disease management.
CD4(+)CD28(null) T cells are oligoclonal lymphocytes rarely found in healthy individuals younger than 40 yr, but are found in high frequencies in elderly individuals and in patients with chronic ...inflammatory diseases. Contrary to paradigm, they are functionally active and persist over many years. Such clonogenic potential and longevity suggest altered responses to apoptosis-inducing signals. In this study, we show that CD4(+)CD28(null) T cells are protected from undergoing activation-induced cell death. Whereas CD28(+) T cells underwent Fas-mediated apoptosis upon cross-linking of CD3, CD28(null) T cells were highly resistant. CD28(null) T cells were found to progress through the cell cycle, and cells at all stages of the cell cycle were resistant to apoptosis, unlike their CD28(+) counterparts. Neither the activation-induced up-regulation of the IL-2R alpha-chain (CD25) nor the addition of exogenous IL-2 renders them susceptible to Fas-mediated apoptosis. These properties of CD28(null) T cells were related to high levels of Fas-associated death domain-like IL-1-converting enzyme-like inhibitory protein, an inhibitor of Fas signaling that is normally degraded in T cells following activation in the presence of IL-2. Consistent with previous data showing protection of CD28(null) cells from spontaneous cell death, the present studies unequivocally show dysregulation of apoptotic pathways in CD4(+)CD28(null) T cells that favor their clonal outgrowth and maintenance in vivo.
Despite the observed coordinate expression of HLA-A and -B antigens in somatic tissues, there is growing evidence that the A and B class I genes are differentially regulated at the transcriptional ...level. Previous studies indicate that this may be related to locus-specific structural differences in certain enhancer elements. We have recently examined the 5' proximal regulatory regions of the A and B homologs in the higher non-human primates and found pronounced differences between the loci. Sequence analysis shows the B-promoters are more homogeneous, whereas the A-locus promoters are divergent among the various species examined. The differences in A- and B-promoters is exemplified by the regulatory element referred to as the IFN-responsive element (IRE). While the B-locus IRE is conserved among all primates examined, the A-locus IRE are divergent and reveal different sequences in the human/chimpanzee, gorilla and orang-utan. In reporter gene bioassays, the B-locus IRE exhibited an enhancer activity in response to induction with IFN-beta and IFN-gamma. In contrast, all the variants of the A-locus IRE found in hominoid primates were unresponsive to IFN. One base substitution shared by all the primate IREs proved to be inactivating. These results provide a molecular basis of how duplicated gene loci encoding structurally and functionally similar antigen-presenting molecules may become differentially responsive to physiological stimulus.
Objective
The immune system of patients with rheumatoid arthritis (RA) is characterized by the accumulation of CD4+ T cells deficient in CD28 expression and the up‐regulation of tumor necrosis factor ...α (TNFα). Previous in vitro studies have shown that TNFα induces transcriptional silencing of the CD28 gene. Because reduced expression of CD28 in T cells compromises immunocompetence, we examined whether CD28 expression is reduced in patients with RA in vivo and whether the reduction is related to TNFα.
Methods
Patients with RA and age‐matched individuals were recruited. Peripheral blood mononuclear cells were stained for CD3, CD4, CD8, CD28, TNF receptor I (TNFRI), and TNFRII, and analyzed by quantitative flow cytometry. The number of CD28 and TNFR molecules was monitored in a subgroup of patients with RA undergoing treatment with anti‐TNFα.
Results
In addition to higher frequencies of CD28null T cells, patients with RA had significantly reduced numbers of CD28 and TNFRI molecules on CD4+,CD28+ T cells. Normal expression could be restored in vitro by overnight culture, suggesting that CD28 in patients was modulated by exogenous factors. In contrast, treatment with TNFα in vitro resulted in further down‐regulation. CD28 expression was normalized in patients undergoing TNFα‐neutralizing therapy.
Conclusion
Overproduction of TNFα in RA induces a global down‐regulation of CD28 in CD4+ T cells and may cause reduced sensitivity to costimulatory signals in T cell responses.
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