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

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-ß 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.

Serum CXCL4 increase in primary Sjögren's syndrome characterizes patients with microvascular involvement and reduced salivary gland infiltration and lymph node involvement.

CXCL4 is an antiangiogenic and immunomodulatory chemokine. We aimed to investigate serum levels of CXCL4 in primary Sjögren's syndrome (pSS), looking for associations with disease features. Thirty-nine consecutive pSS patients underwent clinical-serological assessment and nailfold videocapillaroscopy (NVC). Thirty-six patients and 30 controls affected by osteoarthritis were also investigated for serum levels of CXCL4 and soluble E-selectin (sE-selectin). CXCL4 was higher in pSS patients than in controls (1.79 [0.2-11.18] vs 1.023 ng/ml [0.02-14.45], p < 0.05), particularly in those without anti-La/SSB antibodies (2.89 [1.01-11.18] vs 1.69 ng/ml [0.2-2.72], p < 0.05), while it was lower in pSS patients with a focus score ≥1 at lip biopsy (1.44 [0.86-2.1] vs 2.24 ng/ml [1.64-3.25], p < 0.05) and clinically evident lymphadenopathy (1.53 [0.38-1.7] vs 2.08 ng/ml [1.45-3.03], p < 0.05). CXCL4 correlated with disease duration (r = 0.35, p < 0.05) and sE-selectin (r = 0.45, p < 0.01). Patients with Raynaud's phenomenon (RP) had more frequently abnormal CXCL4 levels than patients without RP (11/15 vs 3/21, p < 0.001), enlarged capillaries (14/16 vs 7/23, p < 0.001) and capillary loss at NVC (14/16 vs 6/23, p < 0.001). The hitherto unknown association of increased serum CXCL4 with features of microvascular impairment in pSS, along with the negative association with features of lymphocytic response (i.e., the absence of subset disease-specific autoantibodies, a low focus score, and the absence of lymphadenopathy) suggest clarifying the possible implication of this chemokine in pSS pathogenesis in larger studies.