Mesenchymal stem cells regulate the Th17/Treg cell balance partly through hepatocyte growth factor in vitro

Qi-Hong Chen,Lei Liu,Fei Wu,Rui-Qiang Zheng,Han-Bing Chen,Hua-Ling Wang,Li-Na Yu

doi:10.1186/s13287-020-01612-y

Qi-Hong Chen, Lei Liu + Show 5 more

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https://doi.org/10.1186/s13287-020-01612-y

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Abstract

IntroductionMesenchymal stem cells (MSCs) exert immunomodulatory functions by inducing the development and differentiation of naive T cells into T cells with an anti-inflammatory regulatory T cell (Treg) phenotype. Our previous study showed that hepatocyte growth factor (HGF) secreted by MSCs had immunomodulatory effects in the context of lipopolysaccharide (LPS) stimulation. We hypothesized that HGF is a key factor in the MSC-mediated regulation of the T helper 17 (Th17) cell/regulatory T (Treg) cell balance.MethodsWe investigated the effects of MSCs on the differentiation of CD4+ T cells and the functions of Th17/Treg cells in response to LPS stimulation by performing in vitro coculture experiments. MSCs were added to the upper chambers of cell culture inserts, and CD4+ T cells were plated in the lower chambers, followed by treatment with LPS or an anti-HGF antibody. Th17 (CD4+CD3+RORrt+) and Treg (CD4+CD25+Foxp3+) cell frequencies were analysed by flow cytometry, and the expression of Th17 cell- and Treg cell-related cytokines in the CD4+ T cells or culture medium was measured by quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Neutrophil functions were determined by flow cytometry after a coculture with Th17/Treg cells.ResultsThe percentage of CD4+CD25+Foxp3+ cells was significantly increased in the CD4+ T cell population, while the percentage of CD4+CD3+RORrt+ cells was significantly decreased after MSC coculture. However, the MSC-induced effect was significantly inhibited by the anti-HGF antibody (p < 0.05). Furthermore, MSCs significantly inhibited the CD4+ T cell expression of IL-17 and IL-6 but increased the expression of IL-10 (p < 0.05 or p < 0.01); these effects were inhibited by the anti-HGF antibody (p < 0.05). In addition, CD4+ T cells cocultured with MSCs significantly inhibited neutrophil phagocytic and oxidative burst activities (p < 0.05 or p < 0.01); however, these MSC-induced effects were inhibited by the anti-HGF antibody (p < 0.05).ConclusionThese data suggested that MSCs induced the conversion of fully differentiated Th17 cells into functional Treg cells and thereby modulated the Th17/Treg cell balance in the CD4+ T cell population, which was partly attributed to HGF secreted by the MSCs.

Highlights

Mesenchymal stem cells (MSCs) exert immunomodulatory functions by inducing the development and differentiation of naive T cells into T cells with an anti-inflammatory regulatory T cell (Treg) phenotype
T helper 17 (Th17)/Regulatory T cell (Treg) cell differentiation of CD4+ T cells To clarify that MSCs regulate the expression of the transcription factor Foxp3 in CD25+ T cells and that of RORγt in CD3+ T cells, which control the development of Treg cells and Th17 cells, respectively, CD4+ T cells were cocultured with MSCs, and the percentages of CD4+CD25+Foxp3+ and CD4+CD3+RORγt+ cells were determined by flow cytometry
The results showed that the percentage of CD4+CD25+Foxp3+ cells was significantly increased in the CD4+ T cell population, while the percentage of CD4+CD3+RORrt+ cells was significantly decreased after MSC coculture

Summary

Introduction

Mesenchymal stem cells (MSCs) exert immunomodulatory functions by inducing the development and differentiation of naive T cells into T cells with an anti-inflammatory regulatory T cell (Treg) phenotype. Many studies have indicated that excessive activation of multiple inflammatory cell types and release of inflammatory mediators play vital roles in the development of ARDS [2, 3]. Among these cell types, CD4+ T cells play an important role in the pathogenesis of ARDS [4]. Regulatory T (Treg) cells have anti-inflammatory roles mainly mediated by contact-dependent suppression and the release of cytokines that impact other immune cells, including CD4+ T cells [5]. Studies have shown that the alveolar recruitment of Treg cells contributes to the resolution of lung inflammation in mice or patients with ARDS [6, 7]. Yu et al showed that the ratio of Th17/Treg cells was closely related to illness severity and 28-day mortality in ARDS patients [9]

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