Serum Lipopolysaccharide-binding Protein Levels and the Incidence of Metabolic Syndrome in a General Japanese Population: the Hisayama Study

Background: The association between chronic lipopolysaccharide exposure and the development of metabolic syndrome (MetS) is unclear. In this study we examined the association between serum lipopolysaccharide-binding protein (LBP) levels, an indicator of lipopolysaccharide exposure, and the development of MetS in a general Japanese population. Methods: 1,869 community-dwelling Japanese individuals aged ≥40 years without MetS at baseline examination in 2002–2003 were followed up by repeated examination in 2007–2008. MetS was defined according to the Japanese criteria. Serum LBP levels were classified into quartiles (quartiles 1–4: 2.20–9.56, 9.57–10.78, 10.79–12.18, and 12.19–24.34 µg/mL, respectively). Odds ratios (ORs) for developing MetS were calculated using a logistic regression model. Results: At the follow-up survey, 159 participants had developed MetS. Higher serum LBP levels were associated with greater risk of developing MetS after multivariable adjustment for age, sex, smoking, drinking, and exercise habits (OR [95% confidence interval] for quartiles 1–4: 1.00 [reference], 2.92 [1.59–5.37], 3.48 [1.91–6.35], and 3.86 [2.12–7.03], respectively; P for trend <0.001). After additional adjustment for homeostasis model assessment of insulin resistance, this association was attenuated but remained significant (P for trend = 0.007). On the other hand, no significant association was observed after additional adjustment for serum high-sensitivity C-reactive protein (P for trend = 0.07). Conclusion: In the general Japanese population, our findings suggest that higher serum LBP levels are associated with elevated risk of developing MetS. Low-grade endotoxemia could play a role in the development of MetS through systemic chronic inflammation and insulin resistance.