HDL cholesterol benefits reduced with high C-reactive protein

By Sally Robertson, B.Sc.Aug 21 2012

The cardioprotective effects of high-density lipoprotein (HDL) cholesterol are compromised in the presence of elevated high-sensitivity C-reactive protein (hsCRP), report researchers.

"We have demonstrated in a large sample of adults representative of the United States population that the protective association of HDL cholesterol with CHD [coronary heart disease] and CVD [cardiovascular disease] is diminished when the hs-CRP levels are >3 mg/L," say Nathan Wong (University of California, Los Angeles, USA) and colleagues.

In an analysis of 13,572 individuals who participated in the National Health and Nutrition Examination Survey 1999-2008, the team categorized individuals by known cutoffs for HDL cholesterol and hsCRP elevations (≥60 mg/dL and >3 mg/L, respectively) as well as by a history of self-reported CHD or CVD .

"C-reactive protein (CRP)… is associated with increased CHD risk and has been shown to add to the risk conferred by low-density lipoprotein (LDL) cholesterol," explains the team. "Yet it is not established whether elevated CRP levels may attenuate the protective relations of HDL cholesterol with CHD."

As reported in The American Journal of Cardiology, individuals with elevated levels of HDL cholesterol (≥60 mg/dL) but not of CRP (3 mg/L or less), had the lowest prevalence of CHD and CVD at 3.3% and 5.0%, respectively. Conversely, those without elevated HDL cholesterol but with raised hsCRP (>3 mg/L) had the greatest prevalence, at 7.7% and 10.8%, respectively.

The researchers also report that individuals who did not have high HDL cholesterol but did have a raised CRP had a significantly greater risk for CHD and CVD than those with raised HDL cholesterol but not raised hsCRP, at respective odds ratios (ORs) of 1.75 and 1.74.

Furthermore, those with both raised HDL cholesterol and raised hsCRP had similar odds of CHD and CVD as those without raised levels.

"It has been reported that the effects of systemic inflammation can impair the anti-inflammatory functions of HDL particles and that in patients with atherosclerosis or other inflammatory conditions, HDL particles can be modified in a way that increases recruitment and activation of macrophages and promotes the oxidation of LDL," explain the researchers.

"The CRP level might reflect underlying inflammation that contributes to dysfunctional HDL by mechanisms other than CRP or by mechanisms that also increase CRP."

Information on both HDL cholesterol and hsCRP might be important for CHD and CVD risk assessment, say Wong and team.

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