Abstract: Objective To investigate the effects of galectin-3 (Gal3) on skin abscess development and activation of mast cells (MC) in mice infected with methicillin-resistant Staphylococcus aureus (MRSA). Methods Wild type mice and Gal3-knockout (Gal3- / -) mice, at 6 ~ 8 weeks of age, were divided into four groups: Wild type mice + PBS group,Wild type mice + MRSA group, Gal3- / - mice + PBS group, Gal3- / -mice + MRSA group, were subcutaneously injected with MRSA or the same volume of phosphate buffer saline, with five mice per group. The development and pathological changes of skin abscess were monitored and recorded. The bacterial load in skin tissues was compared, and the expression of associated cytokines, degranulation of MC, and the distribution of MC activation marker 5-hydroxytryptamine (5-HT) were detected. Results The skin of Wild type mice showed progressive abscesses after subcutaneous infection with MRSA, but the Gal3- / - mice showed smaller abscess areas. Compared to the Wild type mice + MRSA group, the Gal3- / -mice + MRSA group showed lower bacterial loading in the skin tissues (P<0. 01) and fewer infiltrating inflammatory cells with histopathological observation. The expression of cytokines, including IL-1β, TNF-α, IL-33, TGF-β, and IL-10, were significantly lower in Gal3- / - mice than Wild type mice (P<0. 05). The toluidine blue staining showed a large number of degranulated MCs in the skin tissues of the wild type mice + MRSA group, whereas only a few degranulated MCs were observed in the Gal3- / - mice + MRSA group. It was further found that the expression of 5-HT in Gal3- / - mice + MRSA group was significantly lower than that in wild-type mice + MRSA group with immunohistochemical staining. Conclusions Gal3 deficiency reduced the activation and degranulation of mouse skin MC after MRSA infection, resulting in changes to inflammatory responses and alleviating the severity of skin tissue abscesses.
