Open Access

ARTICLE

Effect of pro-inflammatory interleukin-17A on epithelial cell phenotype inversion in HK-2 cells in vitro

Li Liu^1,6, Fu-gang Li^1,6,a, Man Yang³, Li Wang^1,2, Yue Chen¹, Li Wang⁴, Wen Ji², Jun-ming Fan^1,2,5,6

1 Department of Nephrology, Affiliated Hospital of Luzhou Medical College, Luzhou City 646000,Sichuan Province, China
2 Department of Nephrology, West China Hospital of Sichuan University, Chengdu City610041, Sichuan Province, China
3 Department of Nephrology, Shanghai general hospital, Shanghai Jiao Tong University, Shanghai City 200080, China
4 Department of Central Service, West China Hospital of Sichuan University, Chengdu City 610041, Sichuan Province, China
5 State Key Laboratory of Biotherapy of Human Disease, West China Hospital, Sichuan University, Chengdu City 610041, Sichuan Province, China
6 People’s Hospital of Jianyang, Ziyang City 641400, Sichuan Province, China
a The authors contributed equally to this article

* Corresponding Author: Jun-ming Fan,

European Cytokine Network 2016, 27(2), 34-40. https://doi.org/10.1684/ecn.2016.0373

Abstract

Background: Renal interstitial fibrosis (RIF) is a pathological change common to a variety of chronic renal diseases, ultimately progressing to end-stage renal failure. It is believed that epithelial cell phenotype inversion plays an important role in RIF, which is characterized by expression of the mesenchymal maker α-SMA, loss of the epithelial maker E-cadherin, and enhanced secretion of extracellular matrix. IL-17, a newly discovered proinflammatory cytokine, has recently been reported to play an important role in tissue fibrosis, involving pulmonary, liver, intestine and skin tissues. This study aimed to investigate whether IL-17A, a member of the IL-17 family, can induce epithelial cell phenotype inversion, and to explore the molecular mechanism of this phenotype inversion, in vitro. Methods: HK-2 cells were cultured and incubated with IL-17A. Cell proliferation was measured by CCK-8 assay, and the secretion of types I and III collagen was detected by ELISA in dose-dependent and time-dependent experiments. To find out whether IL-17A can induce epithelial cell phenotype inversion, HK-2 cells were stimulated with 80 ng/mL of IL-17A and 10 ng/mL of TGF-β1 as a positive control, for 72 h. To explore the potential signaling pathway, anti-TGF-β1 antibody was added before IL-17A treatment. At the same time, anti-TGF-β1 antibody alone was added to the medium as the negative control group. The expression of types I and III collagen, α-SMA and E-cadherin proteins, and mRNA was measured by real-time PCR, western blotting and immuno-histochemistry. Results: IL-17A promoted the proliferation of HK-2 cells and secretion of types I and III collagen in a dose-dependent and time-dependent manner. Compared with the normal control, IL-17A could stimulate the expression of α-SMA, types I and III collagen, and suppressed the expression of E-cadherin in HK-2 cells. Incubation of IL-17A with TGF-β1 antibody decreased significantly the expression of α-SMA, but increased the expression of E-cadherin in HK-2 cells. Conclusion: Our results suggest that IL-17A might promote the proliferation of HK-2 cells and secretion of extracellular matrix, and induce epithelial cell phenotype inversion via a TGF-β1-dependent pathway. Blocking the pro-inflammatory cytokine IL-17A might be a potential target for the treatment of fibrotic kidney disease.

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