Mechanistic insight into the norepinephrine-induced fibrosis in systemic sclerosis

Abstract

Raynaud’s phenomenon is frequently observed in systemic sclerosis (SSc) patients, and cold- or stress-induced norepinephrine (NE) has been speculated to be associated with vasoconstriction. Objective was to elucidate the role of NE in fibrosis in SSc. IL-6 is a potent stimulator of collagen production in fibroblasts. NE enhanced IL-6 production and proliferation more significantly in SSc fibroblasts than in normal fibroblasts. Furthermore, the production of IL-6 and phosphorylation of p38 in SSc fibroblasts was enhanced by adrenergic receptor (AR)β agonist, isoproterenol, but not ARα agonist, oxymetazoline. ARβ blocker, propranolol, inhibited NE-induced IL-6 production and phosphorylation of p38 in SSc fibroblasts. NE-induced IL-6 was significantly inhibited by p38 inhibitor, SB203580, suggesting that NE-induced phosphorylation of p38 via ARβ enhances IL-6 production in SSc fibroblasts. NE-induced phosphorylation of ERK1/2 via ARα inhibited IL-6 production in SSc fibroblasts. Combined treatment with NE and endothelin-1 resulted in an additive increase in IL-6 production in SSc fibroblasts. NE-induced IL-6/IL-6 receptor trans-signaling increased the production of collagen type I in SSc fibroblasts, and both propranolol and SB203580 inhibited NE-induced collagen production. These results suggest that cold exposure and/or emotional stress-induced NE might contribute to the skin fibrosis via potentiation of IL-6 production from fibroblasts in SSc.

Suppressive Regulation by MFG‐E8 of Latent Transforming Growth Factor β–Induced Fibrosis via Binding to αv Integrin: Significance in the Pathogenesis of Fibrosis in Systemic Sclerosis

“…IL‐6 signaling is also recognized as being involved in the development and progression of fibrosis in SSc . Expression of mRNA for type I collagen and IL‐6 in the lungs of MFG‐E8 –/– TSK/+ mice was significantly higher than that in the lungs of MFG‐E8 WT TSK/+ mice (Figure H).…”

“…Western blot analyses were performed according to previously described protocols . To examine the effect of rMFG‐E8 on TGFβ‐ or latent TGFβ–induced fibrosis–related protein expression in SSc fibroblasts, the cells were pretreated with rMFG‐E8 (100 ng/ml) for 1 hour and then stimulated with TGFβ1 (2 ng/ml) or latent TGFβ (2 ng/ml) for 48 hours.…”

The Regulation of Skin Fibrosis in Systemic Sclerosis by Extracellular ATP via P2Y2 Purinergic Receptor

“…We previously reported that phosphorylation of p38 was involved in the mechanism of the production of IL-6 in SSc fibroblasts (Uehara et al, 2016). Therefore, we next examined the phosphorylation of p38 in SSc fibroblasts treated with ATP.…”

“…ATP-induced IL-6/IL-6 receptor trans-signaling increased the production of collagen type I in SSc fibroblasts IL-6 trans-signaling is mediated in IL-6 receptore nonexpressing cells, including fibroblasts and ECs, by a complex of IL-6 and soluble IL-6 receptor through gp130 (Kawaguchi et al, 1999;Khan et al, 2012). Several studies reported that the complex of IL-6 and soluble IL-6 receptor increased the production of collagen type I in SSc fibroblasts in vitro (Kawaguchi et al, 1999;Uehara et al, 2016). At first, we confirmed that IL-6 receptor was not expressed in SSc fibroblasts and SSc fibroblast-conditioned medium without adding recombinant IL-6 receptor (rIL-6R) (Figure 4e).…”

“…In addition, anti-IL-6 receptor antibody (tocilizmab) treatment improved skin fibrosis in SSc patients (Khanna et al, 2016). We previously reported that norepinephrine (NE)-induced IL-6 from SSc fibroblasts and soluble IL-6 receptor trans-signaling increased the production of collagen type I in SSc fibroblasts in vitro, suggesting that IL-6 derived from dermal fibroblasts might be associated with skin fibrosis in SSc (Uehara et al, 2016). Therefore, we focused on the production of IL-6 in dermal fibroblasts, examined the mechanisms of ATP-induced IL-6 production in SSc fibroblasts, and aimed to clarify the role of ATP in the pathogenesis of fibrosis in SSc.…”