Work

05. Temporal Progression of Sex Hormone-mediated Immune Shifts and ECM Deposition During Wound Repair

Year: 2024

Type: article

Abstract: Purpose: An ideal wound healing process is a fine-tuned balance between tissue regeneration and inflammation. Our prior work has linked testosterone (T) treatment to undesirable wound healing (WH) and scarring outcomes in patients undergoing gender-affirming surgery. It is unclear how the effects of T act throughout the process of wound repair over time. To elucidate the temporal effects of sex hormones in the wound milieu, we sought to perform a multimodal comparative analysis between late-inflammatory and proliferative-stage wounds in our rodent model of testosterone-influenced WH. Methods: XX and XY Sprague-Dawley rats were surgically castrated and subdivided into experimental groups based on hormone regimen. Half of the rats received bi-weekly testosterone cypionate SC injections (+T). All rats received bilateral dorsal excisional wounds two weeks after gonadectomy. Wounds were harvested on POD5 or POD10 after cutaneous wounding and underwent analysis with planimetry, histology, and immunofluorescence. Wound cytokine levels (N=28) were processed via tissue homogenization and analyzed with Luminex Assay. Mixed effects regression analysis with random intercepts was used to analyze expression for twenty-seven immune/inflammatory cytokines and chemokines. Results: Planimetry data exhibited a significantly larger wound area in the +T group at POD5 (p<0.0001), with a similar but non-significant trend observed at POD10 (p=0.6338). Histological analysis demonstrated a significant rise in collagen density, granulation thickness, and epithelial gap in the +T group compared to no T at POD10. Positive cell quantification of macrophage surface markers revealed an elevated CD163+ cell population in the +T group. On protein assay, +T treatment led to significant changes in the various cytokines and chemokines expression, with significantly altered MIP (p=0.048) and MIP-α (p=0.017) chemokines expression on postoperative day five. Conclusions: Systemic administration of testosterone drives local dysregulation of wound healing, with delayed wound closure at an early time-point followed by later excessive extracellular matrix deposition by wound closure. Significant differences spanning both pro- and anti-inflammatory cytokines at the late-inflammatory phase suggest that rather than a solely pro-inflammatory effect, T shifts the wound immune milieu in a unique direction. Increases in the CD163+ macrophage population coupled with MIP and MIP-α alteration suggest these behaviors may be mediated through macrophage phenotype. These findings provide new insight into the complex and previously underappreciated interplay between immune cells and sex hormones in modulating tissue repair.

Source: Plastic & Reconstructive Surgery Global Open

DOI: 10.1097/01.gox.0001015112.50677.b2