Effects of type II collagen epitope carbamylation and citrullination in human leucocyte antigen (HLA)-DR4(+) monozygotic twins discordant for rheumatoid arthritis.

The aim of this study is to investigate the effect of the native, citrullinated or carbamylated type II human collagen T cell- and B cell-epitopes on the adaptive immune response in rheumatoid arthritis (RA). Peripheral blood T and B cells obtained from a human leucocyte D4-related (antigen DR4(-) HLA-DR4)(+) woman with early RA, her healthy monozygotic twin and an unrelated HLA-DR3(+) woman with early RA were analysed for activation (CD154/CD69), apoptosis (annexin/7-aminoactinomycin), cytokine production [interferon (IFN)γ/interleukin (IL)-17/IL-4/IL-10/IL-6] and functional phenotype (CD45Ra/CCR7) after stimulation with the collagen native T cell epitope (T261-273), the K264 carbamylated T cell epitope (carT261-273), the native B cell epitope (B359-369) or the R360 citrullinated B cell epitope (citB359-369), and the combinations of these. The T cell memory compartment was activated by T cell epitopes in both discordant DR4(+) twins, but not in the DR3(+) RA. The collagen-specific activation of CD4(+) T cells was induced with both the native and carbamylated T cell epitopes only in the RA twin. Both T cell epitopes also induced IL-17 production in the RA twin, but a greater IL-4 and IL-10 response in the healthy twin. The citrullinated B cell epitope, particularly when combined with the carbamylated T cell epitope, induced B cell activation and an increased IL-6/IL-10 ratio in the RA twin compared to a greater IL-10 production in the healthy twin. Our data suggest that circulating collagen-specific T and B cells are found in HLA-DR4(+) subjects, but only RA activated cells express co-stimulatory molecules and produce proinflammatory cytokines. Carbamylation and citrullination further modulate the activation and cytokine polarization of T and B cells.

Gamma-delta T lymphocytes and 25-hydroxy vitamin D levels as key factors in autoimmunity and inflammation: the case of zoledronic acid-induced acute phase reaction.

Zoledronic acid (ZA) infusion for osteoporosis is frequently associated with the onset of an acute phase reaction (APR) secondary to the activation of γδ T cell receptor (TCR) lymphocytes (γδ T cells) and to low vitamin D levels, similar to what is observed in chronic inflammation and autoimmunity. In this study we investigated whether the phenotype of γδ T cells is associated with APR and 25-OH vitamin D (25-OHvD) levels. For flow-cytometry analysis, peripheral blood samples were obtained from 52 osteoporotic women prior to 5 mg ZA intravenous infusion and from nine women (five with APR) one week later. Twenty-six/52 (50%) patients reported APR and APR+ cases had a higher percentage of central memory Th1-like γδ T cells. One week after ZA infusion, APR was associated with a decreased percentage of central memory Th1-like γδ T cells, an increase in the percentage and activation of effector memory Th1-like γδ T cells, and an increase in Th17-like γδ T cells. Lower 25-OHvD levels were significantly associated with APR, but no correlation was found between 25-OHvD level and γδ T cell percentage or subsets. In conclusion, patients experiencing APR related to ZA infusion have lower 25-OHvD levels and we suggest that the higher percentage of central memory Th1-like γδ T cells and the expansion of effector memory Th1-like and Th17-like γδ T cells are associated with the occurrence of APR.

X chromosome gene methylation in peripheral lymphocytes from monozygotic twins discordant for scleroderma.

Scleroderma (SSc) is a rare connective tissue disease characterized by fibrosis, microvasculopathy and autoimmune features. The role of genetics is limited in SSc, as suggested by similar concordance rates in monozygotic and dizygotic twin pairs, while environmental factors may act through epigenetic changes, as demonstrated for specific genes. Further, sex chromosome changes have been reported in SSc and may explain the female preponderance. In the present study we compared the methylation profile of all X chromosome genes in peripheral blood mononuclear cells from monozygotic twins discordant (n=7) and concordant (n=1) for SSc. Methylated DNA immunoprecipitations from each discordant twin pair were hybridized to a custom-designed array included 998 sites encompassing promoters of all X chromosome genes and randomly chosen autosomal genes. Biostatistical tools identified sites with an elevated probability to be consistently hypermethylated (n=18) or hypomethylated (n=25) in affected twins. Identified genes include transcription factors (ARX, HSFX1, ZBED1, ZNF41) and surface antigens (IL1RAPL2, PGRMC1), and pathway analysis suggests their involvement in cell proliferation (PGK1, SMS, UTP14A, SSR4), apoptosis (MTM1), inflammation (ARAF) and oxidative stress (ENOX2). In conclusion, we propose that X chromosome genes with different methylation profiles in monozygotic twin pairs may constitute candidates for SSc susceptibility.