Cold exposure aggravates vein occlusion through non-shivering thermogenesis-induced thrombocytopoiesis

Vein occlusion (VO), including deep venous thrombosis (DVT) and retinal vein occlusion (RVO), is a common cause of multiple diseases that severely compromise the quality of life of affected individuals. Epidemiological evidence indicates that VO prevalence increases in cold seasons, yet the underlying mechanism remains unknown. Here, we show that cold exposure markedly elevates peripheral platelet counts, thereby aggravating VO in mouse models. Cold-augmented thrombocytopoiesis depends on the activation of adipose thermogenesis and subsequent increase in circulating free fatty acid (FFA) levels. Mechanistically, FFA-β-oxidation promotes acetyl-CoA production, which upregulates and stabilizes C/EBPα by shifting the balance between p300 acetyltransferase and SIRT1 deacetylase. Acetyl-C/EBPα transcriptionally upregulates GATA-1 and NF-E2 for megakaryocyte maturation and platelet production. Depletion of adipose triglyceride lipase PNPLA2, megakaryocyte-specific knockout of key β-oxidation enzyme CPT1α, or pharmacological inhibition of CPT1α and p300 abolishes cold-augmented thrombocytopoiesis and alleviates DVT and RVO in mouse models. In healthy volunteers, tolerable cold exposure activates adipose thermogenesis, increases circulating FFA levels, and increases platelet counts. Moreover, a retrospective cohort study of 425 patients reveals elevated platelet counts and higher DVT incidence during cold seasons. Similarly, increased platelet counts are observed in 448 patients with RVO at the time of diagnosis in cold seasons. Our study provides novel mechanistic insights into the increased VO risk induced by cold exposure and proposes a new therapeutic paradigm for VO by targeting megakaryocyte metabolism.