Targeted endothelial GTPCH1/BH4 pathway activation reverses vascular dysfunction in smoking-associated obesity

Obesity and cigarette smoking are two major cardiovascular risk factors that frequently coexist, yet their combined impact on vascular function and the underlying mechanisms remains insufficiently defined. Here, we show that short-term cigarette smoke (CS) exposure induces persistent endothelial dysfunction exclusively in obese mice, while having minimal vascular effects in lean mice. Obese mice exposed to CS exhibited severely impaired acetylcholine-induced vasodilation, elevated blood pressure, sustained vascular oxidative stress, and accelerated endothelial senescence. Integrated metabolomic and transcriptomic analyses revealed that CS superimposed on obesity drives a distinct metabolic and transcriptional reprogramming characterized by disrupted redox homeostasis and inflammatory signaling. Mechanistically, CS selectively suppressed endothelial GTP cyclohydrolase 1 (GTPCH1) expression in obese mice, resulting in tetrahydrobiopterin (BH4) depletion, endothelial nitric oxide synthase (eNOS) uncoupling, reduced nitric oxide bioavailability, and increased superoxide production. Endothelial-specific restoration of GTPCH1 expression or pharmacological treatment with sepiapterin restored eNOS coupling, normalized endothelial redox balance, and rescued vascular function. In summary, we demonstrate that CS leads to sustained endothelial dysfunction in the setting of obesity, a phenomenon that is associated with disruption of the GTPCH1/BH4/eNOS axis. This provides a mechanistic explanation for the heightened cardiovascular risk in obese smokers and identifies actionable molecular targets for intervention.