Correlation between two markers of inflammation, serum C-reactive protein and interleukin 6, and indices of oxidative stress in patients with high risk of cardiovascular disease

Abstract

As evidence of the involvement of inflammation and oxidative damage in pathogenesis of age-related chronic diseases is growing, epidemiologists need to develop measures of both conditions to study their relationships in human populations. One way of searching for appropriate biomarkers is to examine correlations between different inflammatory markers and oxidative indices. We examined cross-sectional correlations between two inflammatory markers, serum C-reactive protein (CRP) and interleukin (IL)-6, and three oxidative indices, plasma levels of α-tocopherol and β-carotene, and urinary levels of 2,3-dinor-5,6-dihydro-15-F_2t-isoprostane (F₂-IsoP), in 60 individuals at high risk of cardiovascular disease. Correlations between the biomarkers were examined graphically and using the Pearson correlation coefficient. No correlation was found between plasma levels of α-tocopherol and either of the inflammatory markers. Plasma β-carotene inversely correlated with IL-6 (r=−0.46, p=0.0002) and CRP (r=−0.41, p=0.001). Although urinary F₂-IsoP did not correlate with IL-6, this biomarker positively correlated with CRP (r=0.31, p=0.002). As only urinary F₂-IsoP levels have been validated against known oxidative assaults, their positive association with CRP levels is interpreted as evidence of an interconnection between low-level inflammation and oxidative status. Urinary levels of F₂-IsoP and serum levels of CRP represent appropriate biomarkers for future studies of inflammation and oxidative status in humans.

Keywords: :

• Biological markers
• oxidative stress
• inflammation
• epidemiology