Initial Characterization of the Pig Skin Bacteriome and Its Effect on In Vitro Models of Wound Healing

Elucidating the roles and composition of the human skin microbiome has revealed a delicate interplay between resident microbes and wound healing. Evolutionarily speaking, normal cutaneous flora likely has been selected for because it potentiates or, at minimum, does not impede wound healing. While pigs are the gold standard model for wound healing studies, the porcine skin microbiome has not been studied in detail. Herein, we performed 16S rDNA sequencing to characterize the pig skin bacteriome at several anatomical locations. Additionally, we used bacterial conditioned-media with in vitro techniques to examine the paracrine effects of bacterial-derived proteins on human keratinocytes (NHEK) and fibroblasts (NHDF). We found that at the phyla level, the pig skin bacteriome is similar to that of humans and largely consists of Firmicutes (55.6%), Bacteroidetes (20.8%), Actinobacteria (13.3%), and Proteobacteria (5.1%) however species-level differences between anatomical locations exist. Studies of bacterial supernatant revealed location-dependent effects on NHDF migration and NHEK apoptosis and growth factor release. These results expand the limited knowledge of the cutaneous bacteriome of healthy swine, and suggest that naturally occurring bacterial flora affects wound healing differentially depending on anatomical location. Ultimately, the pig might be considered the best surrogate for not only wound healing studies but also the cutaneous microbiome. This would not only facilitate investigations into the microbiome’s role in recovery from injury, but also provide microbial targets for enhancing or accelerating wound healing.阐明人类皮肤微生物组的功能与组成，已揭示了常驻微生物与伤口愈合之间存在精妙的相互作用。从进化角度来看，正常皮肤菌群之所以被自然选择保留，大概率是因为其能够增强伤口愈合，至少也不会对其产生阻碍。尽管猪是伤口愈合研究的金标准动物模型，但目前学界对猪皮肤微生物组的研究仍不够深入。本研究通过16S核糖体DNA（16S rDNA）测序，对多个解剖部位的猪皮肤细菌组进行了解析。此外，本研究结合细菌条件培养基与体外实验技术，探究了细菌衍生蛋白对人角质形成细胞（NHEK）和成纤维细胞（NHDF）的旁分泌调控作用。研究结果显示，在门水平上，猪皮肤细菌组与人类皮肤细菌组具有相似性，主要由厚壁菌门（55.6%）、拟杆菌门（20.8%）、放线菌门（13.3%）和变形菌门（5.1%）构成，但不同解剖部位间存在物种水平的差异。细菌上清液实验结果表明，其对NHDF迁移、NHEK凋亡及生长因子释放的调控作用具有解剖部位依赖性。本研究结果拓展了学界对健康猪皮肤细菌组的有限认知，并表明天然定植菌群对伤口愈合的调控作用因解剖部位不同而存在差异。综上，猪不仅可作为伤口愈合研究的最优替代模型，同样也可作为皮肤微生物组研究的理想替代模型。这不仅将推动学界对微生物组在损伤修复中作用的研究，还可为增强或加速伤口愈合提供潜在的微生物干预靶点。