Rush University Medical Center, USA
Posters & Accepted Abstracts: J Diabetes Metab
Enhanced bacterial infection and microbiome shift towards pathogenic bacteria are major co-morbidities that contribute to impair wound healing in diabetic ulcer. The underlying reasons for the impaired infection control in diabetic wound remain poorly understood. We used the cutaneous full-thickness wound models in STZ-injected type 1 diabetic (T1D) rats and db/db T2D mice, to study the early dynamics of bacterial infection control in normal and diabetic wound tissues. Surprisingly, we have found that unlike chronic diabetic ulcers which suffer from persistent unresolved inflammation, the acute phase of inflammatory response which is needed for counter invading pathogens early after injury is significantly delayed in diabetic wounds, rendering these wounds susceptible to bacterial infection and healing impairment. Importantly, treatment with a pro-inflammatory chemokine jumpstarts inflammatory response and promotes healing in diabetic wound, indicating that inadequate inflammatory response early after injury in diabetic wound is just as harmful as the persistent inflammatory state that dominates these wounds as they become chronic. Our data further suggest that normal wound tissues express pathogen-specific antimicrobial peptides (ps-AMPs) that preferentially target pathogenic bacteria amongst commensals by recognizing specific virulence structure(s) that are only found in pathogenic bacteria. In contrast, pathogen-specific antimicrobial defenses are impaired in diabetic wounds, thus setting the stage for the microbiome shift towards pathogenic bacteria. We further show that the inability to control pathogenic bacteria leads to persistent inflammatory state and impaired healing in diabetic wound. We posit that inadequate chemokine expression in diabetic wound early after injury leads to delayed inflammatory response, which in turn results in reduced ps-AMPs, rendering diabetic wound vulnerable to infection with pathogenic bacteria, which exacerbate wound damage and drive diabetic wound toward persistent unresolved inflammatory state. We further propose that chemokine therapy can be used to jumpstart inflammatory response and restore antimicrobial defenses and stimulate healing in diabetic wound.
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