Relationship of blood pressure and obesity with inflammatory cytokines among African Americans.

OBJECTIVES

Hypertension and obesity are major public health issues. Both conditions are highly prevalent among African Americans and contribute to the increased burden of cardiovascular disease in this group. Inflammation is considered to be an underlying process in both conditions. The authors sought to determine if there is an interaction between high blood pressure (HBP) and obesity that is associated with markedly elevated plasma levels of proinflammatory cytokines in African American adults.

METHODS

This study examined 484 African Americans, aged 18-45 years, including people with and without obesity, and also with and without HBP. People known to have diabetes were not enrolled. Plasma levels of high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), plasminogen activator inhibitor 1, tumor necrosis factor alpha (TNF-α), and adiponectin were measured. Participants also underwent an oral glucose tolerance test and measurement of blood pressure and body mass index (BMI).

RESULTS

There was no statistically significant interaction between obesity and HBP on plasma levels of adiponectin or the inflammatory cytokines. When both conditions were present, HBP and obesity had additive associations with the expected geometric mean ratios for IL-6 (1.44, 95% CI 1.18 to 1.75), TNF-α (1.31, 95% CI 1.11 to 1.53), hsCRP (2.55, 95% CI 1.99 to 3.26) and negative association with adiponectin (0.61, 95% CI 0.52 to 0.71). Compared with HBP, obesity had the predominant association with cytokine levels. An increase in cytokine plasma levels was detectable when BMI exceeded 25 kg/m2.

CONCLUSIONS

Biomarkers of inflammation in African Americans are strongly associated with BMI. A modest additive effect is found with HBP. Interventions to reduce obesity-related inflammation may impact cardiovascular disease outcomes.