Aldehyde dehydrogenase 2 promotes wound healing by regulating M2 macrophage polarization

ObjectiveTo verify the role of aldehyde dehydrogenase 2 (ALDH2) in wound healing and to explore the underlying mechanisms. MethodsA murine excisional wound model was developed and mice were randomly assigned to control group and Alda-1 (ALDH2 agonist) group. Wound healing rate and activity of ALDH2 were measured. Masson staining was used to observe the collagen fiber content, and immunohistochemistry was used to detect the expression of ALDH2 and α-smooth muscle actin (α-SMA). The expression of collagen type Ⅰ and Ⅲ (Col-Ⅰ, Col-Ⅲ), and the number of F4/80, inducible nitric oxide synthase (iNOS) and CD206 positive (F4/80+, iNOS+, CD206+) cells were analyzed using immunofluorescences. Furthermore, interleukin (IL)-4-stimulated RAW264.7 cells were treated with Alda-1 or CVT-10216 (an ALDH2 inhibitor) in vitro. The proportion of F4/80+CD206+ cells were analyzed using flow cytometry. Anti-inflammatory and pro-inflammatory cytokines were examined using ELISA. The expression of protein associated with the AKT/mTOR pathway were detected via western blotting. ResultsCompared with control group, the wound healing rate of mice in the Alda-1 group was significantly improved, and the expression of Col-Ⅰ, Col-Ⅲ, and α-SMA in the wound surface increased. Although the number of F4/80+ cells in wounds did not significantly differ, there was a decrease in iNOS+ cells and an increase in CD206+ cells. In vitro, compared to IL-4 group, IL-4+Alda-1 group exhibited an increased proportion of F4/80+CD206+ macrophages and higher levels of anti-inflammatory factors, alongside a reduction in levels of pro-inflammatory factors. Conversely, IL-4+CVT-10216 group demonstrated a decreased proportion of F4/80+CD206+ macrophages, lower levels of anti-inflammatory factors with a concomitant increase in pro-inflammatory factors. Additionally, the protein expressions of p-AKT and p-mTOR were significantly elevated in IL-4+Alda-1 group and diminished in IL-4+CVT-10216 group. ConclusionALDH2 induces M2 macrophage polarization via AKT/mTOR pathway to promote wound healing in mice.