Abstract: BACKGROUND: Studies have shown that nucleotide binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, interleukin-18, and interleukin-1β levels can induce an inflammatory cascade response to release inflammatory factors, affect metabolic stress, and damage endothelial cells involved in the development and progression of diabetic foot ulcers, which can provide a reference for early infections.
OBJECTIVE: To investigate the predictive effect of peripheral blood mononuclear cell NLRP3 inflammasome, interleukin-18 and interleukin-1β levels on early infection after flap repair of diabetic foot ulcers. 
METHODS: A total of 147 patients with diabetic foot ulcers were selected and divided into infection group and non-infection group according to whether they were infected within 1 week after operation. Logistic regression was used to analyze the relationship between NLRP3 inflammasome, interleukin-18 and interleukin-1β levels in peripheral blood mononuclear cells and early postoperative infections, and to evaluate their predictive values. 
RESULTS AND CONCLUSION: In 147 patients with diabetic foot ulcers, 35 cases (23.81%) were infected within 1 week after operation, and 47 strains of pathogenic bacteria were isolated, including 25 strains of Gram-positive bacteria (53.19%) and 22 strains of Gram-negative bacteria (46.81%). Univariate analysis showed that Wagner grade, presence of comorbid diabetic nephropathy, operation time, peripheral blood NLRP3 mRNA, Caspase-1 mRNA, ASC mRNA, interleukin-18 and interleukin-1β levels were risk factors for early postoperative infections (all P < 0.05). Multivariate analysis suggested that Wagner grade, NLRP3 mRNA, Caspase-1 mRNA, ASC mRNA, high interleukin-18, interleukin-1β were independent risk factors (all P < 0.05). Receiver operator characteristic curve results showed that the area under the receiver operator characteristic curve of NLRP3 mRNA, Caspase-1 mRNA, ASC mRNA, interleukin-18 and interleukin-1β for early postoperative infections in patients with diabetic foot ulcers was 0.823, 0.705, 0.676, 0.811 and 0.853, respectively, and the area under the curve of combined predictive efficacy was 0.915. To conclude, patients with diabetic foot ulcers are mainly affected by Gram-positive bacteria, and the levels of NLRP3 inflammasome, interleukin-18 and interleukin-1β in peripheral blood mononuclear cells are independent risk factors for early postoperative infections. The combined prediction efficacy of these indicators is better and deserves further in-depth study.  

Key words: diabetic foot ulcer, flap repair, early postoperative infection, NLRP3, interleukin-18, interleukin-1β