Abstract
Background: Systemic sclerosis (SSc) T cells can induce apoptosis of autologous skin fibroblasts in vitro. 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.Methods: T cells from diffuse SSc patients were co-cultured with autologous skin fibroblasts. IL17A mRNA was assessed by real-time PCR in co-cultured and control T cells, while IL17RA, CXCL1, CCL2, CCL3, COL1A1, COL3A1, CTGF, TGFBR2, and SMAD3 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 plus 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.Results: T cell–fibroblast co-cultures overexpressed IL17A and IL17RA. Furthermore, co-cultured fibroblasts upregulated IL-17A targets CXCL1, CCL2, and CCL3, while COL1A1, COL3A1, CTGF, and two key effectors of the TGF-β signaling, TGFBR2 and SMAD3, 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.Conclusion: 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.
Highlights
Systemic sclerosis (SSc) is a chronic multiorgan disease characterized by microvascular injury, autoimmune phenomena, and fibroblast activation, leading to uncontrolled extracellular matrix (ECM) deposition in the skin and visceral organs and increased mortality due to vital organ dysfunction [1, 2]
Chemokine concentrations were increased in co-culture supernatants, while procollagen type I (PCI) levels were reduced, especially after stimulation with ectopic IL-17A
Simultaneous α-IL-17RA mAb treatment restored PCI levels and reduced fibroblast apoptosis in IL-17A-stimulated co-cultures. 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
Summary
Systemic sclerosis (SSc) is a chronic multiorgan disease characterized by microvascular injury, autoimmune phenomena, and fibroblast activation, leading to uncontrolled extracellular matrix (ECM) deposition in the skin and visceral organs and increased mortality due to vital organ dysfunction [1, 2]. We demonstrated that SSc T cells co-cultured with autologous skin fibroblasts up to 10 days display the same clonotypes found in the skin of these patients and can induce fibroblast apoptosis in vitro [6]. In line with our observations, other authors reported that chemically pre-activated peripheral γδT cells from SSc patients can induce autologous fibroblast apoptosis after a shortterm exposure in vitro [7] In those experiments, both T cell– fibroblast interaction and activation of γδT cells was paralleled by a cytokine burst in which profibrotic cues were more prominent [5, 6, 8, 9]. We used a system based on T-cell-autologous fibroblast co-cultures to further investigate a possible role of IL-17A in SSc
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