Macrophage Polarization and Endothelial Dysfunction in Response to Cigarette Smoke and Ketone Body Administration

introduction: Cigarette smoking is a major cardiovascular risk factor that induces endothelial dysfunction through chronic inflammation and macrophage-mediated vascular injury. Macrophages exhibit plasticity by polarizing into pro-inflammatory M1 or reparative M2 phenotypes. This polarization mechanism may represent a potential therapeutic target. Ketone bodies have been shown to improve endothelial function and reduce inflammation, but their combined effects with cigarette smoke exposure on macrophage polarization remain unclear. This study aimed to investigate the effects of cigarette smoke on macrophage polarization and assess whether ketone body administration can modulate these responses in an animal model. materials and methods: A randomized post-test-only control group design was conducted in 25 male Wistar rats, which were assigned to five groups: control, smoke-exposed without intervention, and smoke-exposed treated with ketone bodies at low (1.5 g/kg/day), medium (3 g/kg/day), or high (6 g/kg/day) doses. Rats were exposed to cigarette smoke (40 cigarettes/day) for 4 weeks, followed by ketone body administration. The M1/M2 ratio was calculated to assess polarization dominance. results: Cigarette smoke exposure increased M1 macrophage expression compared to the control group. The M1/M2 ratio indicated an M1-dominant phenotype across all groups. Administration of ketone bodies showed a trend toward reduced M1 and M2 macrophage counts relative to the control group and lowered the M1/M2 ratio, suggesting a shift toward an anti-inflammatory profile. The lowest M1/M2 ratio was observed at the highest ketone dose. discussion: This study reinforces the role of cigarette smoke in promoting M1 macrophage polarization and endothelial dysfunction via activation of inflammatory pathways such as NF-κB and MAPK. Administration of ketone bodies attenuated the inflammatory response by reducing both M1 and M2 macrophage counts and lowering the M1/M2 ratio, suggesting a shift toward an anti-inflammatory phenotype. These effects may be mediated through suppression of STAT1 activity, promotion of STAT6-mediated M2 polarization, and inhibition of the NLRP3 inflammasome. Interestingly, higher doses of ketone bodies increased overall macrophage counts but maintained a lower M1/M2 ratio, highlighting their potential to promote M2 dominance even under elevated immune activation. conclusion: Cigarette smoke exposure induced a pro-inflammatory M1-dominant macrophage polarization. Ketone body administration reduced both M1 and M2 macrophage expression and lowered the M1/M2 ratio. This suggests a shift toward a less inflammatory profile. Ketone bodies may help mitigate smoke-induced vascular inflammation by modulating macrophage polarization.