IL-10 alleviates lipopolysaccharide-induced skin scarring via IL-10R/STAT3 axis regulating TLR4/NF-κB pathway in dermal fibroblasts

Background: Hypertrophic scar (HS) is a serious fibrotic skin disease. The roles of bacterial contamination and prolonged inflammation in wound were considered to be significant. IL-10 plays a pivotal role in wound healing and scar formation. Here, we investigate whether IL-10 alleviates lipopolysaccharide (LPS)-induced inflammatory response and skin scarring, explore the possible mechanism in scar formation. Methods: RT-qPCR, Western blotting, histochemistry, immunostaining, ELISA array, electron microscope, fibroblast-populated collagen lattice (FPCL) and a rabbit ear scar model were used to investigate and validate the effect of IL-10 on LPS-stimulated scar formation. Findings: Our results showed that the expression of TLR4 and pp65 was higher in HS and HS-derived fibroblasts (HSFs) than their counterpart normal skin (NS) and NS-derived fibroblasts (NSFs). LPS could upregulate the expression of TLR4, pp65, Col I, Col III and α-SMA in NSFs, but IL-10 could downregulate their expression in both HSFs and LPS-induced NSFs. Blocking IL-10 receptor (IL-10R) or the phosphorylation of STAT3, their expression was upregulated. In addition, in vitro and in vivo models results showed that IL-10 could alleviate LPS-induced fibroblast-populated collagen lattice (FPCL) contraction and scar formation. Interpretation: Our study suggests that IL-10 may improve LPS-induced harmful to wound healing, reduce scar contracture and scar formation via IL-10R/STAT3 axis regulating TLR4/NF-κB pathway in dermal fibroblasts by reducing ECM proteins deposition and the conversion of HSFs to NSFs. Therefore, the downregulation of inflammation may be a better option for improving scar quality, and become potential therapeutic targets for scarring. Funding Statement: This research was supported by grants from the National Natural Science Foundation of China (81571914, and 81741105), and the Natural Science Foundation of Shaanxi Province (2018JQ8048). Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: Written consent was obtained from all participants before surgery. All protocols used in this study were approved by the Ethics Committee of Xijing Hospital, affiliated to the Fourth Military Medical University of China. Animal experiments were approved by the Experimental Animal Committee of the Fourth Military Medical University (Xi’an, China).