36. Spironolactone Mitigates Fibrosis and Improves Healing of Burn Wounds

Abstract

Purpose: Adhesion, contracture, and the formation of disfiguring, hypertrophic scars remain some of the most recalcitrant problems in care of the burned patient. The central pathology driving fibrosis is an imbalance of extracellular matrix (ECM). The mineralocorticoid receptor (MR) is a nuclear receptor with shared ligand-activity from both its primary activator, aldosterone, and glucocorticoids and has cell specific effects on proliferation, migration, and ECM production in fibroblasts and keratinocytes. Here we demonstrate that MR-inhibition with FDA approved spironolactone enhances epithelialization healing and mitigates hypertrophic collagen deposition after burns in mice. Methods: Female athymic mice sustained bilateral 1 cm full-thickness thermal injury and were stratified into either a) vehicle, b) spironolactone, c) aldosterone, or d) aldosterone + spironolactone. Aldosterone applied via subcutaneous pump (Alzet) spironolactone delivered intraperitoneally. Mice followed photographically for 4-to-6-weeks. At sacrifice wound biopsies were collected for H&E, Trichrome, and protein. An additional subset of samples were assessed via Pentachrome staining to assess relative ratio of collagen, fibrin, and elastic fibers. Pentachrome samples were analyzed using ImageJ (RGB Hue threshold) to isolate elastin, GAG and collagen for quantification. Results: Histologic evaluation of healing wounds from burned mice demonstrated persistence of inflammation, wound edema, and immature ECM. In mice treated with spironolactone this effect if alleviated by 4-weeks post-injury concurrent with gross findings of rapid wound epithelialization. Spironolactone treatment additionally enhanced gross and histologic evidence of scar resolution and resulted in a decreased in collagen staining vs. controls. Conclusion: We found a significant early improvement in wound epithelialization with spironolactone therapy. This suggests a potentially distinct effect from the proposed ECM-modifying strategy hypothesized. More analysis is needed but this data supports that MR-inhibition may be a valuable new therapeutic in treatment of burn scars.