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Objective: Non-healing diabetic foot ulcers are a leading cause of disability and death in diabetic patients, which often results in lower limb amputation. This study aimed to investigate the impact of biomarkers on the healing of diabetic foot ulcers by utilizing dynamic serum proteomics and skin proteomic analysis, combined with clinical case follow-up studies. Methods: To analyze dynamic serum proteomic changes in four groups, age-matched normal subjects, diabetic patients, pretreatment diabetic foot ulcer patients, and healed diabetic foot ulcer patients were selected. The differential proteins were screened in conjunction with normal and diabetic foot ulcer skin proteomics. In this study, a total of 80 patients with diabetic foot ulcers were enrolled and monitored for 3–6 months during treatment. To verify the significance of the differential proteins, age-matched diabetic patients (240 patients) and healthy controls (160 patients) were included as controls. Results: Dynamic serum proteomics trend showed that the level of negative regulatory proteins related to endothelial cell migration, angiogenesis, and vascular development was significantly decreased after treatment of diabetic foot ulcer. GO enrichment analysis suggested that differentially expressed proteins were mainly enriched in protein activation cascade, immunoglobulin production, and complement activation. The researchers identified the core proteins APOA1, LPA, and APOA2 through a convergence of serum and skin proteomics screening. Clinical cases further validated that APOA1 levels are decreased in diabetic foot ulcer patients and are correlated with disease severity. In addition, animal experiments showed that APOA1 could promote wound healing in diabetic mice. Conclusions: Based on our dynamic proteomics and clinical case studies, our bioinformatic analysis suggests that APOA1 plays a critical role in linking coagulation, inflammation, angiogenesis, and wound repair, making it a key protein that promotes the healing of diabetic foot ulcers.

Purpose: Studies showed that TLR4 knockout (TLR4KO) could mitigate obesity and insulin resistance induced by high-fat diet in rats. In this study, we further investigated the effects of TLR4KOon islet function and pancreatic proteomics in obese rats by high-fat diet. Methods: PA-induced lipotoxicity β-cells, SD and TLR4KOrats were used in this study. iTRAQ was used to screen out meaningful differential proteins.The protein expression level was evaluated by Western blotting; the cell apoptosis was detected by TUNEL assay. Results: TLR4KOcould reduce inflammatory and regulate body composition in obese rats, and improve β-cells function. The quantitative analysis of protein revealed that TLR4KOrebalanced proteomics disorders in pancreas of obese rats. In addition, the pathways involved in differential proteins were mainly metabolic pathways, arachidonic acid metabolism, ECM–receptor interaction, pancreatic secretion, PI3K-Akt signaling pathway, and FoxO signaling pathway. Further analysis of protein–protein interaction (PPI) revealed that Stk39 and Ass1 interacting through Mapk14-Ywhae were node proteins and participated in inflammatory response, carboxylic acid metabolic process, and small molecule metabolic process. In vitro experiments we confirmed that silencing TLR4 can inhibit PA-induced β-cell apoptosis, insulin secretion disorders, and increase Ass1 expression. While, overexpression of Ass1 in β-cell inhibited PA or LPS-induced β-cell damage. Conclusions: Our study confirmed that TLR4KOcould improve dysfunction of β-cell, and the underlying mechanism might be involved in ebalancing proteomics disorders in pancreas, affecting the expression of Ass1.