Enhanced autophagy promotes the clearance of Pseudomonas aeruginosa in diabetic rats with wounds

BACKGROUND: To investigate the effects of the Pseudomonas aeruginosa (P. aeruginosa) type 3 secretion system (T3SS) on diabetic wound healing and autophagy-associated proteins. METHODS: P. aeruginosa and P. aeruginosa without T3SS were used to infect back wounds in 36 rats (18 normal and 18 diabetic). Followed infection with P. aeruginosa, another 36 rats (18 normal and 18 diabetic) with back wounds were treated with autophagy inducer rapamycin or gentamicin (positive control). Wound healing, colony count, HE and Masson staining were recorded. Western blot and immunofluorescent were used to determine the expression of the autophagy markers (LC3, beclin-1 and p62) in wound tissues. RESULTS: The number of P. aeruginosa colonies in infected wounds began to decrease on day 3 in normal rats and on day 7 in diabetic rats. The decrease was more apparent in P. aeruginosa without T3SS. The expression of LC3-II/LC3-I and beclin-1 gradually increased, and p62 gradually decreased in the wounds in of all groups; however, the changes were more dramatic in normal rats compared with diabetic rats on day 14. Rapamycin increased LC3-II/LC3-I and beclin-1 expression, and decreased p62 expression, gentamicin had no effect on their expression of autophagy markers. CONCLUSIONS: T3SS of P. aeruginosa inhibited the entire autophagy process in wounds. Thus inducing autophagy could enhance the clearance of P. aeruginosa in diabetic wounds and is expected to become a new method of anti-P. aeruginosa infection.