Vascular structure and inflammation in a bi-ethnic South African population: the SABPA study

Abstract

Background: South Africa is experiencing a high incidence of cardiovascular disease (CVD). In addition to modifiable risk factors, inflammation was found to be an independent risk factor for CVD development. Inflammatory markers such as interleukin-6 (IL-6), C-reactive protein (CRP) and soluble urokinase plasminogen activation receptor (suPAR) have been linked to the pathogenesis of CVD's, including atherosclerosis and coronary artery disease. Despite this reality, there is still a measure of uncertainty regarding the effect that inflammation could have on early changes in vascular structure, as measured by intima-media thickness (IMT) and cross-sectional wall area (CSWA). The central aim of this study was therefore to determine whether vascular structure relates to inflammation in South Africans over three years. Objective: Our objectives for this study were to (i) assess the extent to which vascular structure (IMT and CSWA) and inflammation (suPAR, CRP and IL-6) changed over three years; and (ii) to explore whether three-year changes in vascular structure (IMT and CSWA) are associated with three-year changes in inflammation. Methods: This MHSc study forms part of the Sympathetic Activity and Ambulatory Blood Pressure in Africans study (SABPA). A total of 303 participants at baseline (in 2008-2009) and at follow-up (in 2011-2012) were included. The participants were teachers from the North-West Province, South Africa, aged between 20 and 65 years. A validated questionnaire about demographic and lifestyle information was completed. Standardised methods were used to determine plasma levels of inflammatory markers (IL-6, CRP and suPAR) and to obtain cardiovascular, anthropometric and other biochemical measurements. Results and conclusion: We found that IMT (5.13%, 95%CI: 3.75;6.51), CSWA (9.53%, 95%CI: 7.32;11.7), suPAR (4.93%, 95%CI: 0.81;9.06) and IL-6 (28.2%, 95%CI: 16.9;39.5) increased over the three years, while CRP decreased (3.31%, 95%CI: -16.0;9.42). After adjusting for conventional risk factors, percentage change in IMT inversely associated with percentage change in suPAR (β =-0.12, p=0.036; adjusted R2=0.16), while IMT did not associate with either CRP or IL-6. These results contradicted previous findings and warrant further investigation into the mechanisms linking vascular structure with inflammation, especially during the early stages of vascular structural change.