Bacterial Colonization is a Potential Pathogenesis of Keloids and Hypertrophic Scars

Abstract

Background: Keloids and hypertrophic scars are pathological scars that result from aberrant wound healing. The etiology of pathological scar formation remains elusive, but it causes great physical and psychological pain to patients. This study aimed to determine bacterial colonization in keloids and hypertrophic scars and further investigate the pathogenesis of their formation. Methods: 23 normal skin controls, 53 keloids and 35 hypertrophic scars (without any other previous treatments) were included in the study. After collecting the surgically removed samples, gram staining, immunofluorescence, immunohistochemical analysis, immunoelectron microscopy, microbiological culture and a 16S ribosome DNA real-time quantitative Polymerase Chain Reaction (16S rDNA RT-qPCR) were used to detect the presence of bacteria. PICRUSt2 tool and BugBase were used to map the 16S rDNA sequencing to the pathways, genes and phenotypic differences. Results: In normal skin tissues, the colonizing bacteria were only found in skin appendages, while extracellular and intracellular bacteria were widely distributed in keloids and hypertrophic scars, and intracellular bacteria mainly existed in the cytoplasm of macrophages and fibroblasts. A total of 2260 bacterial species were detected in keloids and hypertrophic scars, mainly concentrated in Clostridiales, Burkholderiales, Actinomycetales and Bacteroidales. The pathogenicity and athletic ability of colonizing bacteria were positively correlated with the degree of hyperplasia and invasions of scars. Conclusions: The difference in the species and number of colonizing bacteria in pathological scars may cause the heterogeneity of clinical manifestations, providing a new strategy for preventing and treating keloids and hypertrophic scars.