We studied the anti-angiogenic effect of interleukin-35 (IL-35) by investigating its effects on signal transmission through the Janus kinase signal transducer and activator of transcription (JAK-STAT) pathway in fibroblast-like synoviocytes (FLS).
Using the collagen-induced arthritis (CIA) model of rheumatoid arthritis (RA), we derived and cultured FLS, stimulated FLS with IL-35 at different concentrations and examined the expression levels of mRNA and protein of both vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), endostatin, TNF-α, and IL-6 using reverse transcription polymerase chain reaction (RT-PCR) and immunoblotting. We used Western blotting to study the effects of IL-35 on the function of the JAK-STAT pathway in FLS.
IL-35 treatment inhibited the expression of VEGF, FGF-2, TNF-α and IL-6, and increased the expression of endostatin in FLS. Western blotting showed that IL-35 treatment of CIA-derived FLS resulted in signalling through STAT1, but not through STAT3 or STAT5.
IL-35 signalling through STAT1 and inhibition of the expression of mediators of angiogenesis and inflammation in FLS provide a likely mechanism for anti-angiogenic effects seen in experimental models of RA. Our data suggest that IL-35 and its signalling pathway represent a therapeutic target for the treatment of RA and other angiogenesis-related diseases.