Effect of interleukin (IL)-35 on IL-17 expression and production by human CD4+T cells.

Kosuke Okada,Akio Mitani,Yoshiaki Hasegawa,Eriko Miyake,Takeshi Kikuchi,Takeki Fujimura,Hisashi Goto,Makoto Aino,Iichiro Okabe,Yuki Iwamura,Yosuke Kamiya,Ario Izawa,Makio Mogi

doi:10.7717/peerj.2999

Abstract

BackgroundInterleukin (IL)-17 produced by mainly T helper 17 (Th17) cells may play an important destructive role in chronic periodontitis (CP). Thus, anti-inflammatory cytokines, such as IL-35, might have a beneficial effect in periodontitis by inhibiting differentiation of Th17 cells. Th17 differentiation is regulated by the retinoic acid receptor-related orphan receptor (ROR) α (encoded by RORA) and RORγt (encoded by RORC). However, the role of IL-35 in periodontitis is not clear and the effect of IL-35 on the function of Th17 cells is still incompletely understood. Therefore, we investigated the effects of IL-35 on Th17 cells.MethodsPeripheral blood mononuclear cells (PBMCs) were sampled from three healthy volunteers and three CP patients and were analyzed by flow cytometry for T cell population. Th17 cells differentiated by a cytokine cocktail (recombinant transforming growth factor-β, rIL-6, rIL-1β, anti-interferon (IFN)-γ, anti-IL-2 and anti-IL-4) from PBMCs were cultured with or without rIL-35. IL17A (which usually refers to IL-17), RORA and RORCmRNA expression was analyzed by quantitative polymerase chain reaction, and IL-17A production was determined by enzyme-linked immunosorbent assay.ResultsThe proportion of IL-17A+CD4+ slightly increased in CP patients compared with healthy controls, however, there were no significant differences in the percentage of IL-17A+CD4+ as well as IFN-γ+CD4+ and Foxp3+CD4+ T cells between healthy controls and CP patients. IL17A, RORA and RORC mRNA expression was significantly increased in Th17 cells induced by the cytokine cocktail, and the induction was significantly inhibited by addition of rIL-35 (1 ng/mL). IL-17A production in Th17 cells was significantly inhibited by rIL-35 addition (1 ng/mL).DiscussionThe present study suggests that IL-35 could directly suppress IL-17 expression via RORα and RORγt inhibition and might play an important role in inflammatory diseases such as periodontitis.

Highlights

Chronic periodontitis (CP) is the most common disease that causes destruction of periodontal tissue (Pihlstrom, Michalowicz & Johnson, 2005)
We found significantly decreased levels of IL-17A production in the rIL-35-treated groups compared with untreated T helper 17 (Th17) cells (P < 0.05)
Previous studies have reported that Th17 cells in human periodontal tissue were increased in chronic periodontitis (CP) patients compared with healthy controls (Adibrad et al, 2012; Cardoso et al, 2009)

Summary

Introduction

Chronic periodontitis (CP) is the most common disease that causes destruction of periodontal tissue (Pihlstrom, Michalowicz & Johnson, 2005). Gram-negative bacterial infection is the main cause for CP, and the host reaction following infection forms a basis for periodontitis In this regard, T cells, macrophages, epithelium cells and proinflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α (Lundqvist et al, 1994; Sandros et al, 2000) are related to immunoreaction and together function as an immunological barrier for pathogenic bacteria in periodontitis. IL17A, RORA and RORC mRNA expression was significantly increased in Th17 cells induced by the cytokine cocktail, and the induction was significantly inhibited by addition of rIL-35 (1 ng/mL). The present study suggests that IL-35 could directly suppress IL-17 expression via RORα and RORγ t inhibition and might play an important role in inflammatory diseases such as periodontitis

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Conclusion