Interleukin-17 stimulates the release of pro-inflammatory cytokines by blood monocytes in patients with IgA nephropathy

OBJECTIVE: Interleukin-17 (IL-17) is a newly discovered cytokine implicated in the regulation of inflammation. The present study was designed to explore whether IL-17 is involved in the immunoregulatory response in IgA nephropathy (IgAN). MATERIAL AND METHODS: We examined the in vitro effect of recombinant human IL-17 (rhIL-17) on pro-inflammatory cytokine release by peripheral blood monocytes (PBM) from patients with IgAN. Measurement of IL-1beta and tumor necrosis factor-alpha (TNF-alpha) was performed by means of a sandwich enzyme-linked immunosorbent assay. RESULTS: IL-1beta and TNF-alpha release were upregulated by rhIL-17 in a dose- and time-dependent fashion. Treatment of PBM from patients with IgAN with lipopolysaccharide and rhIL-17 resulted in significant activation and release of IL-1beta and TNF-alpha protein. Levels of IL-1beta and TNF-alpha were significantly higher in IgAN patients with the nephrotic syndrome (NS) than in patients without NS or in healthy subjects. We also provide information indicating that there is excessive production of IL-17 in IgAN patients. When IL-17-activated PBM were incubated in the presence of IL-10, IL-10 exerted a significant suppressive effect on IL-1beta and TNF-alpha release in vitro. CONCLUSION: IL-17 can stimulate the release of pro-inflammatory cytokines from PBM in patients with IgAN.