Chettaphanin I ameliorates lipopolysaccharide-induced acute lung injury and is associated with suppression of Lactate-H4K8la-OMA1 signaling

Acute lung injury (ALI) is a clinically severe inflammatory lung disorder for which effective pharmacological interventions remain limited. Although natural products have shown promise in ALI, the protective effects of Chettaphanin I and its underlying mechanisms have not been systematically investigated. The anti-inflammatory and oxidative stress-modulating effects of Chettaphanin I were first evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Its in vivo protective effects were then assessed in an LPS-induced mouse model of ALI using histopathology, bronchoalveolar lavage fluid (BALF) analysis, inflammatory cytokine assays, oxidative stress-related measurements, and pulmonary barrier-associated evaluation. Mechanistically, RNA sequencing, single-cell RNA sequencing, chromatin immunoprecipitation sequencing (ChIP-seq), and OMA1 gain- and loss-of-function experiments were used to explore the involvement of mitochondrial dynamics and lactylation-associated signaling. Chettaphanin I showed no obvious cytotoxicity in vitro under the tested conditions and caused no overt short-term histopathological abnormalities in major organs in vivo. In RAW264.7 cells, Chettaphanin I significantly reduced LPS-induced ROS-associated fluorescence and the secretion of IL-6, TNF-α, and IL-1β. In LPS-challenged mice, Chettaphanin I alleviated histopathological lung injury, reduced inflammatory cell infiltration, decreased BALF protein content and lung wet-to-dry ratio, and suppressed inflammatory cytokine production. In parallel, Chettaphanin I attenuated oxidative stress-related signals and increased the levels of antioxidant-associated markers (SOD and GPX4) in lung tissue. Transcriptomic analysis suggested that its protective effects were associated with mitochondrial-related pathways. Chettaphanin I increased Mfn1, Mfn2, and Opa1 expression, decreased Drp1 and Fis1 expression, improved mitochondrial ultrastructural abnormalities, and partially restored tight junction-associated proteins. In addition, Chettaphanin I reduced lung lactate levels, decreased overall lysine lactylation and histone H4K8 lactylation (H4K8la), and was associated with reduced H4K8la enrichment in the OMA1 promoter region and downregulation of OMA1 expression. Functional experiments further supported the involvement of OMA1 in the effects of Chettaphanin I on mitochondrial dynamics-related proteins, oxidative stress-related changes, and tight junction-associated proteins. Chettaphanin I exerts protective effects against LPS-induced ALI. These effects may involve, at least in part, modulation of mitochondrial dynamics, suppression of lactate-associated H4K8la signaling, downregulation of OMA1 expression, and preservation of pulmonary barrier integrity.