TL1A increased the differentiation of peripheral Th17 in rheumatoid arthritis

- TL1A enhanced Th17 differentiation not Th17 maintenance.
- There was an increased DR3 expression on CD4+T cells in RA patients.
- Anti-TNF-α treatment impaired Th17 differentiation up-regulated by TL1A.
- TL1A promoted the expression of Th17 lineage-specific transcription factor RORc.

The interaction between TNF-like protein 1A (TL1A) and its receptors, death receptor-3 (DR3) may be involved in the pathogenesis of rheumatoid arthritis (RA) through the regulation of Th17. Our data here showed that TL1A could significantly promote Th17 differentiation and RORc mRNA expression from naive T cells and enhance IL-17A level in cell supernatant in RA patients. Anti-TNF-α treatment had suppressive effects on TL1A-mediated Th17 differentiation and RORc mRNA expression. In addition, The percentage of peripheral CD4+DR3+T cells of RA was significantly higher than that of healthy controls (HC), and this increased percentage of CD4+DR3+T cells was obviously up-regulated when stimulated with anti-CD3 and anti-CD28 antibody in RA patients. However, anti-CD3 and anti-CD28 antibody stimulation did not increase the percentage of CD4+DR3+IL-17A+T cells in RA patients. These results suggested that TL1A could promote Th17 differentiation in RA via the activation of RORc, and this effect may be mediated by the binding of TL1A with DR3.