S100 calcium-binding protein A9 promotes skin regeneration through toll-like receptor 4 during tissue expansion

Yu Zhang; Yajuan Song; Jing Du; Wei Liu; Chen Dong; Zhaosong Huang; Zhe Zhang; Liu Yang; Tong Wang; Shaoheng Xiong; Liwei Dong; Yaotao Guo; Juanli Dang; Qiang He; Zhou Yu; Xianjie Ma

doi:10.1093/burnst/tkad030

S100 calcium-binding protein A9 promotes skin regeneration through toll-like receptor 4 during tissue expansion

Burns Trauma. 2023 Oct 31:11:tkad030. doi: 10.1093/burnst/tkad030. eCollection 2023.

Authors

Yu Zhang¹, Yajuan Song¹, Jing Du¹, Wei Liu¹, Chen Dong¹, Zhaosong Huang¹, Zhe Zhang¹, Liu Yang¹, Tong Wang¹, Shaoheng Xiong¹, Liwei Dong¹, Yaotao Guo¹, Juanli Dang¹, Qiang He¹, Zhou Yu¹, Xianjie Ma¹

Affiliation

¹ Department of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, No.127 Changle West Road, Xi'an, Shaanxi Province 710032, China.

Abstract

Background: In plastic surgery, tissue expansion is widely used for repairing skin defects. However, low expansion efficiency and skin rupture caused by thin, expanded skin remain significant challenges in promoting skin regeneration during expansion. S100 calcium-binding protein A9 (S100A9) is essential in promoting wound healing; however, its effects on skin regeneration during tissue expansion remain unclear. The aim of the present study was to explore the role of S100A9 in skin regeneration, particularly collagen production to investigate its importance in skin regeneration during tissue expansion.

Methods: The expression and distribution of S100A9 and its receptors-toll-like receptor 4 (TLR-4) and receptor for advanced glycation end products were studied in expanded skin. These characteristics were investigated in skin samples of rats and patients. Moreover, the expression of S100A9 was investigated in stretched keratinocytes in vitro. The effects of S100A9 on the proliferation and migration of skin fibroblasts were also observed. TAK-242 was used to inhibit the binding of S100A9 to TLR-4; the levels of collagen I (COL I), transforming growth factor beta (TGF-β), TLR-4 and phospho-extracellular signal-related kinase 1/2 (p-ERK1/2) in fibroblasts were determined. Furthermore, fibroblasts were co-cultured with stretched S100A9-knockout keratinocytes by siRNA transfection and the levels of COL I, TGF-β, TLR-4 and p-ERK1/2 in fibroblasts were investigated. Additionally, the area of expanded skin, thickness of the dermis, and synthesis of COL I, TGF-β, TLR-4 and p-ERK1/2 were analysed to determine the effects of S100A9 on expanded skin.

Results: Increased expression of S100A9 and TLR-4 was associated with decreased extracellular matrix (ECM) in the expanded dermis. Furthermore, S100A9 facilitated the proliferation and migration of human skin fibroblasts as well as the expression of COL I and TGF-β in fibroblasts via the TLR-4/ERK1/2 pathway. We found that mechanical stretch-induced S100A9 expression and secretion of keratinocytes stimulated COL I, TGF-β, TLR-4 and p-ERK1/2 expression in skin fibroblasts. Recombined S100A9 protein aided expanded skin regeneration and rescued dermal thinning in rats in vivo as well as increasing ECM deposition during expansion.

Conclusions: These findings demonstrate that mechanical stretch promoted expanded skin regeneration by upregulating S100A9 expression. Our study laid the foundation for clinically improving tissue expansion using S100A9.

Keywords: Mechanical stretch; Regeneration; S100 calcium-binding protein A9; Skin, Soft tissue expansion.