Spontaneous and in vitro activation of synovial fluid and peripheral blood lymphocytes in rheumatoid arthritis

Th17 pathway in recent-onset autoimmune diabetes

AIMS

Evaluate the participation of IL-17 pathway in T1D pathogenesis. T helper 17 cells are potent, highly inflammatory cells that produce interleukin 17A (IL-17A), considered a mediator of various immune disorders. However, their role in Type 1 diabetes (T1D) pathogenesis in humans is not totally elucidated.

METHODS

The expression of IL-17 Receptor A (IL-17RA) in peripheral T lymphocytes and IL-17A serum levels in recent-onset patients with T1D were compared with healthy controls. IL-17A gene variants were evaluated in a greater cohort.

RESULTS

Patients with recent-onset T1D (less than 6 months of diagnosis) exhibited lower expression of IL-17RA in CD3+ T (% of cells = 31.3% × 43.6%; p = .041) and CD4+ T cells (11.1% × 25.2%; p = .0019) and lower number of IL-17RA in CD4+ T cells (MFI = 1.16 × 4.56; p = .03) than controls. IL-17RA expression in CD8+ T cells and IL-17A serum levels were similar in both groups. The coding regions and boundary intron sequences of IL17A were sequenced. Seventeen allelic variants, including three novel variants in exon 3 (3'UTR n) were identified, but no one was associated with T1D susceptibility, as well as the resulting haplotypes and diplotypes. The expression of IL-17RA was not correlated with metabolic variables (glucose and HbA1c levels) or pancreatic autoantibodies titers.

CONCLUSIONS

The lower expression of IL-17RA in CD3+ and CD4+ T cells suggests a reduced effect of IL-17A in immune response of recent-onset T1D patients, at least at peripheral tissues. IL-17A allelic variants were not related with T1D susceptibility.

Frequency of Th17 CD4+ T cells in early rheumatoid arthritis: a marker of anti-CCP seropositivity

Objective

To examine the frequency and phenotype of Th17 cells in the peripheral blood of early RA (eRA) patients.

Methods

CD4+ T cells were isolated from the peripheral blood of 33 eRA patients, 20 established RA patients and 53 healthy controls (HC), and from the synovial fluid of 20 established RA patients (RASF), by ficoll-hypaque gradient and magnetical negative selection. After polyclonal stimulation, the frequency of Th17 and Th1 cells was determined by flow cytometry and concentrations of IL-17, IFN-γ, TNF-α and IL-10 were measured by ELISA in cell-free supernatants.

Results

When all of our eRA patients were analyzed together, a significantly lower percentage of circulating Th17 cells and a lower CD4-derived IL-17 secretion were observed in comparison with HC. However, after stratifying by anti-CCP antibody status, circulating Th17 cells were decreased in anti-CCP(+) but not in anti-CCP(-)-eRA. All Th17 cells were CD45RO+CD45RA- and CCR6+. Dual Th17/Th1 cells were also exclusively decreased in anti-CCP(+)-eRA. Circulating Th17 and Th17/Th1 cells were negatively correlated with anti-CCP titres. When anti-CCP(+)-eRA patients were retested one year after initiating treatment with oral methotrexate, their circulating Th17 frequency was no longer different from HC. Of note, the percentage of circulating Th1 cells and the secretion of CD4-derived IFN-γ, TNF-α and IL-10 were not different between eRA patients and HC. In established RA patients, circulating Th17 and T17/Th1 cell frequencies were comparable to HC. In RASF, both Th17 and Th1 cells were increased when compared with blood of eRA patients, established RA patients and HC.

Conclusion

Decreased circulating Th17 levels in eRA seem to be a marker of anti-CCP seropositivity, and return to levels observed in healthy controls after treatment with methotrexate.

Enhanced chondrocyte destruction by lymphokine-activated killer cells. Possible role in rheumatoid arthritis

OBJECTIVE

The lysis of chondrocytes, the parenchymal cells of cartilage, by lymphocytes may provide a potent mechanism by which the immune system participates in sustaining joint damage in rheumatoid arthritis (RA). We studied the capability of lymphocytes from healthy individuals and patients with arthritis to lyse chondrocytes.

METHODS

Peripheral blood mononuclear cells (PMBC) were tested for their ability to lyse chondrocytes in a 51Cr-release assay. Enhancement of the chondrolytic activity was determined by preincubating the cells with T cell growth factor (TCGF) or recombinant interleukin-2 (rIL-2) before cytotoxic testing.

RESULTS

PBMC from healthy individuals possessed a low ability to lyse chondrocytes, whereas cells from the synovial fluid of patients with RA displayed higher chondrolytic activity. In RA, modulating factors must come into play because not all synovial fluid sample cells showed high chondrolytic activity and cells from synovial tissue had little or no lytic action on chondrocytes. Chondrolytic activities of cells from all sources, including PBMC from healthy subjects and patients with arthritis and cells isolated from synovial fluid or from the synovial tissue of RA patients, were greatly increased by incubating the cells with TCGF or rIL-2. In contrast, treatment of chondrocytes with interferon-gamma, which enhances major histocompatibility complex gene expression, decreased the susceptibility of chondrocytes to lysis.

CONCLUSION

These observations suggest a mechanism for joint damage in which the destruction of chondrocytes by lymphocytes is controlled by cytokines released during the inflammatory process in arthritic diseases.