Ethnic and sex differences in circulating endotoxin levels: A novel marker of atherosclerotic and cardiovascular risk in a British multi-ethnic population.

BACKGROUND: Circulating endotoxin levels are associated with atherosclerosis. Moreover, ethnic differences in pro-inflammatory markers may be associated with ethnic differences in atherosclerotic and cardiovascular (CVD) and coronary heart disease (CHD) risk. OBJECTIVE AND METHODS: To investigate ethnic differences in circulating plasma endotoxin levels, its soluble receptor (sCD14), and high-sensitivity CRP (hs-CRP). 192 individuals, aged 40-59 years (61 white (30 women), 68 of African origin (33 women) and 63 South Asians (33 women)), free from coronary heart disease (CHD), stroke, CVD and diabetes were randomly selected from the UK 'Wandsworth Heart and Stroke Study'. RESULTS: Age-adjusted endotoxin levels were lower in women than in men (p=0.002) and were highest in South Asians (13.3EU/mL [95% CI 12.0-14.7]) and lowest in individuals of African origin (10.1EU/mL [9.1-11.1]) than in whites (p for linear trend <0.001). Endotoxin levels were positively associated with waist, waist-hip ratio, total cholesterol, serum triglycerides and serum insulin levels and negatively associated with serum HDL-cholesterol. Serum hs-CRP and plasma sCD14 varied by ethnic group (p<0.001) but was not associated with endotoxin. CONCLUSIONS: This study is the first to indicate a graded increase in endotoxin levels from black Africans to whites to South Asians, which is consistent with the ethnic difference in CHD risk. Whilst these findings support the concept that the innate immune system (IIS) may contribute significantly to the metabolic component underlying the development of CVD and CHD risk, further studies are required to see whether endotoxin levels are causally related to the development of CHD.