Session Type: Abstract Submissions (ACR)
Background/Purpose: Interleukin (IL)-13 is a pleiotropic cytokine involved in T helper type 2 cell immune response and in the development of fibrotic conditions such as liver cirrhosis, and pulmonary fibrosis and also implicated in systemic sclerosis (SSc). Although elevated serum levels of IL-13 has been reported in SSc and recently CD8 T cells was found as a producing subset of IL-13, IL-13 effect of effector phase in the skin fibroblasts has not been well characterized in SSc. The aim of the present study was to investigate the fibrotic effects of IL-13 on the collagen production by skin fibroblasts from patients with SSc. We also evaluated the signal transduction of IL-13 in the cultured skin fibroblasts.
Methods: We examined the expression of IL-13Rα1 and IL-13Rα2 on skin fibroblasts by flow cytometry and Western blot analyses. Skin fibroblasts from patients with diffuse cutaneous SSc were cultured with indicated concentrations of IL-13 and TNFα for various periods. Procollagen type I C-peptide and TGF-β1 levels were then measured using commercial ELISA kits. mRNA expression of COlA1, ColA2, TGF-b1, CTGF were also measured by standard real-time qPCR. The phosphorylation of STAT6 and various MAPK and Akt pathways have been evaluated by Phospho-Kinase Arrays. Various specific inhibitors for STAT6-mediated pathways, U0126 (Erk1/2 inhibitor), LY294002 (PI3K inhibitor), JAK inhibitor, and Tyk inhibitor (RO495) were used for evaluation of IL-13-mediated signaling.
Results: With the flow cytometric analysis, we revealed the expression of IL-13Ra2, but did’t detect IL-13 Ra1 with confirmation of the same Ra1 mAb detecting neutrophil expression of IL-13 Ra1. We also found that IL-13Rα2 expression was increased by TNF-α stimulation (13% vs 20%). On the contrary, Western blot analysis revealed both expression of IL-13 Ra1 and Ra2. With IL-13 stimulation, the phosphorylation of STAT6 and Akt was induced, and IL-13 plus Jak /Tyk inhibitor(s) suppressed the phosphorylation of STAT6, suggesting IL-13Rα1 was functional, though flow cytometry pattern does not show positive. Treatment with U0126 (Erk1/2 inhibitor) or LY294002 (PI3K inhibitor) did not suppress the phosphorylation of STAT6. We observed IL-13 increased collagen production in 72 hours (p = 0.009) compared to no stimuli. On the contrary, TNF-a decreased COLA1, COL A2, and CTGF mRNA compared to no stimuli.
Conclusion: Our results suggest that IL-13 may be a potent stimulator of collagen production in skin fibroblast derived from patients with SSc and IL-13 signaling pathway would be a potential target for the new treatment of SSc. TNF-a may have inhibitory effect on fibrotic development and the use of TNF blocking biological reagents in SSc would not be recommended in SSc.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/il-13-receptors-and-signaling-in-the-dermal-fibroblasts-from-patients-with-systemic-sclerosis/