Advanced Glycation Endproducts Delay Diabetic Wound Healing by OSR2/SPRR1B Signalling in Keratinocyte's Proliferation and Differentiation.

Abstract

Objective: The deposition of advanced glycation endproducts (AGEs) in skin tissue is a major risk factor leading to refractory diabetic wounds. However, the mechanism of AGEs in diabetic wounds remains unclear. This study aimed to investigate the mechanism and signalling pathway of AGEs in diabetic wound healing.

Methods: This study integrated bioinformatics analysis of the Gene Expression Omnibus data set (GSE80178) to identify differentially expressed genes between diabetic foot ulcer and non-diabetic foot ulcer tissues, with small proline-rich protein 1B (SPRR1B) validated as a key target in clinical specimens. Mechanistic investigations were conducted using AGE-stimulated HaCaT cells and db/db diabetic mouse models. We combined cellular functional assays (CCK-8, flow cytometry, western blotting, and immunofluorescence), chromatin immunoprecipitation, and in vivo short hairpin RNA knockdown to explore how the OSR2-SPRR1B axis regulates cell fate and affects diabetic wound healing.

Results: SPRR1B and OSR2 levels were upregulated in diabetic wound tissues and HaCat cells with AGE intervention. After knockdown of SPRR1B or OSR2 expression, keratinocyte proliferation was promoted and apoptosis was inhibited, the expression of CK5/CK14 and loricrin increased, and the expression of CK1/CK10 decreased significantly. SPRR1B expression was changed by OSR2 knockdown and overexpression. SPRR1B expression significantly increased with OSR2 inducing directly, as revealed by chromatin immunoprecipitation assays. SPRR1B, OSR2, and AGEs were highly expressed in db/db mice. Knockdown of SPRR1B accelerated diabetic wound healing, increased the Ki67-positive cell rate, decreased the apoptosis rate, increased CK5/CK14 expression in the basal layer and CK1/CK10 between the basal layer and horny layer, and increased loricrin in epidermal tissue in db/db mice.

Conclusions: SPRR1B was a key factor in diabetic wounds with AGE deposition, and OSR2 was an upstream control gene of SPRR1B. Inhibition of SPRR1B expression enhanced diabetic wound healing.