Gut microbiota-associated leucine elevation promotes cold-induced atherosclerotic plaque formation and instability

Environmental factors such as cold exposure have been increasingly recognized as contributors to atherosclerosis progression, yet the underlying mechanisms linking environmental stress to vascular pathology remain incompletely understood. In particular, the role of the gut microbiota and microbiota-associated metabolites in cold-induced atherosclerosis has not been fully elucidated.

A cold exposure model was established in ApoE⁻/⁻ mice fed a Western diet. Integrated multi-omics analyses were combined with fecal microbiota transplantation (FMT) and mechanistic cellular assays to investigate gut microbiota remodeling, metabolic alterations, and immune regulation during cold-induced atherosclerosis.

In this study, we demonstrate that cold exposure accelerates atherosclerotic plaque growth and instability in parallel with pronounced gut microbiota dysbiosis and alterations in host metabolic profiles. FMT combined with metabolomic analyses showed that cold-associated gut microbiota is closely associated with elevated circulating leucine levels, suggesting that cold-induced microbial remodeling may participate in this process by modulating host systemic leucine availability. Mechanistically, increased leucine suppressed the Zic family member 2 (Zic2) in macrophages, leading to reduced expression of growth arrest-specific 6 (Gas6), a key mediator of efferocytosis. Impaired Gas6-dependent efferocytosis resulted in defective clearance of apoptotic cells, heightened vascular inflammation, and increased plaque instability. Importantly, supplementation with Lactobacillus johnsonii, a commensal bacterium depleted under cold exposure, normalized circulating leucine levels, restored Zic2-Gas6 signaling, enhanced macrophage efferocytosis, and attenuated atherosclerotic plaque progression. Conversely, leucine supplementation recapitulated the effects of cold exposure on plaque development and instability.

Collectively, these findings identify a previously unrecognized cold-microbiota-leucine-Zic2-Gas6-efferocytosis axis that links environmental stress to atherosclerosis progression. Targeting gut microbial regulation of host systemic leucine levels, including L. johnsonii-based interventions, may represent a promising therapeutic strategy for preventing cold-induced atherosclerotic cardiovascular disease.