Alleviation of taurine on lung injury in fatty liver hemorrhagic syndrome laying hens by improving antioxidant and anti-inflammatory capacity

Fatty liver hemorrhagic syndrome (FLHS), a common metabolism-associated fatty liver disease (MAFLD) in modern intensive laying hens, affects not only liver function but also other organs, including the lungs, causing lung impairment and susceptibility to respiratory ailments. Clinical investigations have revealed an independent association between MAFLD and diminished lung function. Previous studies have demonstrated that taurine enhances the body's antioxidant capacity and exerts a significant inhibitory effect on both acute and chronic inflammation. Additionally, taurine exhibits promising preventive and therapeutic efficacy in the occurrence and development of FLHS, significantly ameliorating liver damage in laying hens. However, whether taurine can mitigate FLHS-induced lung injury remains unexplored. This study investigated the effects of taurine on lung injury in FLHS laying hens induced by a high-energy and low-protein diet, and macrophage inflammation model stimulated by Lipopolysaccharide (LPS). The results showed that taurine treatment significantly reduced inflammatory cell infiltration in lung tissue and improved alveolar structure. Furthermore, antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), as well as the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and its downstream factors expression levels of quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), were significantly increased in the lungs and macrophages of laying hens following taurine administration. Taurine also effectively suppressed M1 macrophage polarization, reduced levels of proinflammatory cytokines, including inducible nitric oxide synthase (iNOS), nitric oxide (NO), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α), inhibited the activation of the LPS/TLR4/NF-κB signaling pathway, JAK2-STAT1 signaling pathway, and NLRP3 inflammasome. The results suggested that taurine can alleviate lung injury in FLHS laying hens by enhancing antioxidant capacity and inhibiting inflammatory response mediated by macrophage M1 polarization.