Diabetic Foot Ulcer (DFU) Biofilm Infection and Recurrence (DFU Biofilm)

Description

In the current standard of care (SoC), wound closure is defined (FDA) by wound area re-epithelialization without drainage. The investigators' pre-clinical large animal work demonstrates that wounds with a history of biofilm infection may meet above criteria but the repaired wound-site skin is deficient in barrier function. This has led to the concept of functional wound closure wherein the current clinical definition of wound closure is supplemented with a functional parameter - restoration of skin barrier function as measured by low trans-epidermal water loss (TEWL).

This study rests on DFU-patient based findings from a NIDDK-DIACOMP funded pilot study (Sen/Gurtner) showing that closed DFU with deficient barrier function are more likely to recur. Biofilm infection as assessed through Scanning electron microscopy and wheat germ aggluttin assay performed on debrided tissue causes faulty re-epithelialization, compromising skin barrier function at the closed wound site. Such defects are caused by biofilm-inducible miRs which silence junctional proteins necessary for skin barrier function. The IRB protocol associated with this study, rests on our novel patient-based observation that in wound-edge tissue catenin delta1/p120 catenin (CTNND1) is suppressed as measured through immunohistochemistry. CTNND1 is an essential regulator of E-cadherin stability which is regarded as a master organizer in epithelial phenotype and plays a critical role in maintaining the barrier integrity of skin. The investigators' prior study identified miR-9 is a biofilm induced microRNA that targets adherens junction protein E-cadherin. The investigators propose that miR-9 can target CTNND1. The validation of miR targeting will be performed quantitative real time PCR, Western blot analyses, Argonaute 2 pull down assay and on bead assay. Thus this proposal, fully based on the study of DFU patients, seeks to conduct a fully powered clinical study testing whether DFU with a history of biofilm infection closes with deficient barrier function (Aim 2). Aim 3 tests whether such functionally deficient wound closure, manifested as high TEWL, is associated with greater wound recurrence. Per FDA, the significance of association studies is heightened by support of a well-founded biological rationale provided by mechanistic studies. This proposal rests on such mechanisms that have been reported by us in pre-clinical large animal studies.

A chronic hyperglycemic diabetes increases the risk of developing Alzheimer's disease (AD) and vascular dementia (VaD), both in general and elderly population. With the age-related changes of the skin, there is an increased risk of adverse skin barrier function that is key to wound healing. Other age-related skin conditions, such as reduced water and altered lipid content, and lower production of sebum and natural moisturizing factors of the stratum corneum (SC) may also cause dry skin and itching. These conditions together with reduced immune responses, cause aging skin to be more susceptible to infections4. In light of these facts, there is paucity in studies that investigate the mechanism of how compromised skin barrier function plays a role in wound healing outcomes among Alzheimer's Disease and Related Dementias (AD/ADRD) patients.

The primary parent study will address molecular mechanisms implicated in biofilm-induced loss of skin epithelial barrier integrity in DFU patients. Within the parent study, an additional cohort of patients with a chronic wound that are diagnosed with Alzheimer's Disease and Related Dementias (AD/ADRD) will be studied to better understand the similarities and differences in molecular mechanisms and wound healing trajectory between this group and the parent cohort.

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