Arbutin alleviates Mycoplasma gallinarum-induced damage caused by pulmonary fibrosis via the JAK2/STAT3 pathway

Mycoplasma gallinarum (MG) can cause infectious respiratory diseases in poultry that are chronic. Arbutin (AR) possesses anti-inflammatory, bacteriostatic, antitussive, and expectorant pharmacological effects, but whether it exerts regulatory effects on MG-induced pneumonia and fibrosis remains unclear. The study results unveiled that pulmonary connective tissue hyperplasia, pulmonary capillary congestion, and inflammatory cell infiltration, as well as serum levels of cytokines (i.e., TNF-α, IL-1β, IL-6, and IL-10), were elevated after MG infection. Collagen fibers were significantly deposited in the lung tissue from MG-infected chicks. Furthermore, the expression levels of key factors in the JAK2/STAT3 and TGF-β/Smad pathways markedly increased. AR intervention significantly alleviated MG-induced pneumonic injury, and reduced collagen deposition and the expression of fibrosis markers in the lung tissue. AR reduced the degree of pulmonary fibrosis by regulating key factors of the JAK2/STAT3 signaling pathway in the MG-infected HD11 cells. Thus, AR effectively reduced the expression of inflammatory factors by regulating the JAK2/STAT3 signaling pathway, thereby improving lung inflammation and fibrosis.