AUTHOR=Vettori Serena , Barra Giusi , Russo Barbara , Borgia Alessia , Pasquale Giuseppe , Pellecchia Luciana , Vicedomini Lucia , De Palma Raffaele 

TITLE=T-Cell Proapoptotic and Antifibrotic Activity Against Autologous Skin Fibroblasts in vitro Is Associated With IL-17A Axis Upregulation in Systemic Sclerosis

JOURNAL=Frontiers in Immunology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2020.00220

DOI=10.3389/fimmu.2020.00220

ISSN=1664-3224

ABSTRACT=<p><bold>Background:</bold> Systemic sclerosis (SSc) T cells can induce apoptosis of autologous skin fibroblasts <italic>in vitro</italic>. Th17 cells have been reported to increase in SSc patients, and interleukin-17A (IL-17A) has a profibrotic function. We used a system based on T-cell-autologous fibroblast co-cultures to further investigate a possible role of IL-17A in SSc.</p><p><bold>Methods:</bold> T cells from diffuse SSc patients were co-cultured with autologous skin fibroblasts. <italic>IL17A</italic> mRNA was assessed by real-time PCR in co-cultured and control T cells, while <italic>IL17RA, CXCL1, CCL2, CCL3, COL1A1, COL3A1, CTGF, TGFBR2</italic>, and <italic>SMAD3</italic> mRNAs were assessed in co-cultured and control fibroblasts. In subset experiments, co-cultures and control cells were treated with either IL-17A or IL-17A <italic>plus</italic> anti-IL17 receptor monoclonal antibody (α-IL-17RA mAb). Chemokine and procollagen type I (PCI) production was further investigated at the protein level in cell culture supernatants by multiple suspension immunoassay and sandwich ELISA, respectively. Co-cultured and control fibroblasts were also stained with Annexin V and analyzed by flow cytometry.</p><p><bold>Results:</bold> T cell–fibroblast co-cultures overexpressed <italic>IL17A</italic> and <italic>IL17RA</italic>. Furthermore, co-cultured fibroblasts upregulated IL-17A targets <italic>CXCL1, CCL2</italic>, and <italic>CCL3</italic>, while <italic>COL1A1, COL3A1, CTGF</italic>, and two key effectors of the TGF-β signaling, <italic>TGFBR2</italic> and <italic>SMAD3</italic>, were found downregulated. Consistently, chemokine concentrations were increased in co-culture supernatants, while PCI levels were reduced, especially after stimulation with ectopic IL-17A. Finally, simultaneous α-IL-17RA mAb treatment restored PCI levels and reduced fibroblast apoptosis in IL-17A-stimulated co-cultures.</p><p><bold>Conclusion:</bold> These data suggest that IL-17A upregulation might play a role in modulating T cell-mediated antifibrotic and proapoptotic effects in co-cultured autologous skin fibroblasts.</p>