Glycated and Non-Glycated Human Alpha-1 Antitrypsin in Hyperglycemic Wound Healing: In Vivo and In Vitro Models

Impaired wound healing is a major cause of morbidity among patients with diabetes. Human α1-antitrypsin (hAAT) promotes the resolution of injured tissues. In hyperglycemic conditions, circulating hAAT is likely to undergo glycation, yet it is unknown whether its reparative properties are preserved. We hypothesized that clinical-grade hAAT treatment, but not deliberately glycated hAAT (gly-hAAT), would promote wound repair under hyperglycemic conditions. Mice were rendered hyperglycemic, excisional wounding was performed, and wounds were treated with topical albumin or hAAT every three days. The wound area was assessed, and samples were collected for histology and gene expression analysis. Gly-hAAT was generated from clinical-grade hAAT, after which in vitro RAW 264.7 macrophage responses and re-epithelialization of A549 cells were assessed. Gap closure was further assessed using sera from a human cohort (prospective samples from 10 patients with poorly controlled diabetes at Soroka University Medical Center, Beer-Sheva, Israel, 2018). Group comparisons were performed using one-way ANOVA with Tukey's post hoc test. hAAT accelerated in vivo wound closure and in vitro A549 cell gap closure, accompanied by an anti-inflammatory IL-1Ra/IL-1β gene expression profile. In contrast, gly-hAAT inhibited normoglycemic mouse wound closure, evoked an inflammatory response in macrophages, and interfered with A549 cell gap closure; concomitant hAAT treatment improved gap closure. Similarly, patient serum inhibited A549 gap closure, and concomitant hAAT treatment improved gap closure. Importantly, inferential statistical analysis was not performed on this outcome due to the small and heterogeneous human cohort. In conclusion, hAAT accelerated wound closure in hyperglycemic mice and in A549 cells, whereas gly-hAAT promoted inflammatory responses and impaired wound closure, a trend reversed by native hAAT. These findings support the concept that glycation undermines the beneficial functions of circulating hAAT and provides a mechanistic insight into the pathophysiology of diabetic wound healing. Further studies are warranted to evaluate clinical-grade hAAT as a potential therapeutic for hyperglycemia-associated impaired wound healing.