Microbial Symbionts Accelerate Wound Healing via the Neuropeptide Hormone Oxytocin
(a) Microscopy of formalin-fixed, paraffinized wounded skin of aged C57BL/6 mice (at 3, 6, and 12 days post- wounding). Wound margins are delineated with yellow outlines. The healing time course is faster in mice consuming L. reuteri evidenced by reduced wound sizes. (b) Histopathology of wound healing timecourse shows wound epidermal gaps [indicated by black brackets]. Accelerated epidermal closure in mice consuming the purified lactic acid bacteria led to complete re-epithelialization of wounds in 8/12 female mice by the 6th day post-wounding. By contrast, zero of 12 control animals had complete epidermal wound closure at the same time-point. 12 days after biopsy, the newly formed epidermis in L. reuteri-treated mice was normal and lacked regenerative hyperplasia, indicating a rapid rate of epithelial remodeling. (c) Wound area at each of three time points decreases significantly in both male and female mice fed L. reuteri. Female mice fed L. reuteri exhibit more significant wound closure compared to controls versus male mice at 6 and 12 days. (d) Wound size diminishes more rapidly in mice fed L. reuteri with the increased rate of wound closure, accompanying a smaller epidermal gap in both male and female mice. Hematoxylin and Eosin. Scale bars: a = 250 µm. (3 day: Male: Control (n = 6), Control + LR (n = 7), Female: CD (n = 6), CD+LR (n = 8); 6 day: Male: Control (n = 12), Control + LR (n = 12); Female: Control (n = 12), Control + LR (n = 12); 12 day: Male: Control (n = 7), Control + LR (n = 7), Female: Control (n = 9), Control+LR (n = 8)).