Metrnl/IL-41 Alleviates Lipopolysaccharide-Induced Acute Lung Injury by Suppressing Inflammatory Responses through the AMPK/SIRT1 Signaling Pathway.

Introduction: Interleukin-41 (IL-41), also known as Metrnl, is a multifunctional adipokine recognized for its neurotrophic and anti-inflammatory properties that play a significant role in diseases such as sepsis and chronic obstructive pulmonary disease. Despite its crucial biological functions, the mechanisms by which IL-41 mitigates lipopolysaccharide (LPS)-induced acute lung injury (ALI) are not well understood. This study aimed to elucidate the protective effects of IL-41 against LPS-induced inflammation and apoptosis in a murine model and in vitro using bronchial epithelial cells (Beas-2b).

Methods: We administered recombinant IL-41 to mice subjected to LPS-induced ALI and observed changes in lung histopathology, inflammation, and apoptosis. Concurrently, Beas-2b cells were transfected with IL-41 constructs, and the role of the AMPK/SIRT1 pathway was investigated using specific inhibitors and agonists.

Results: Our results demonstrated that LPS-induced ALI is characterized by increased inflammatory cell chemotaxis in lung lavage fluid, enhanced phosphorylation of NFκB p65, and elevated Bax protein expression, coupled with a decrease in IL-41 protein levels. Treatment with recombinant IL-41 effectively mitigated these pathological changes by upregulating AMPK phosphorylation and SIRT1 expression and inhibiting IκB/NFκB p65 phosphorylation. In cellular assays, overexpression of IL-41 reversed LPS-induced oxidative stress, apoptosis, and the secretion of inflammatory cytokines, whereas suppression of IL-41 or inhibition of AMPK reversed these protective effects.

Conclusions: In conclusion, IL-41 exerts significant protective effects against ALI by activating the AMPK/SIRT1 signaling pathway and reducing excessive inflammation and apoptosis. These findings suggest that IL-41 holds promise as a therapeutic target for ALI, potentially allowing for personalized treatments based on serum IL-41 levels.