Educational attainment and systemic inflammation: Evidence of a stable gradient from two measurements in the Tromsø...

Disadvantaged socioeconomic position (SEP) is associated with increased systemic inflammation. However, the mechanisms and potential persistence of these molecular differences remain poorly understood. We investigated the association between educational attainment, an indicator of SEP, and the levels of 52 plasma inflammatory proteins measured in the same individuals seven to eight years apart. We analyzed data from 909 participants of the sixth (2007-2008) and seventh (2015-2016) waves of the Tromsø Study, a longitudinal population-based study in Tromsø, Norway. Inflammatory protein levels were measured using the Olink Target 96 Inflammation panel and educational attainment was retrieved from questionnaires. Cross-sectional and longitudinal associations between educational attainment and inflammatory protein levels were assessed using multivariable linear models and linear mixed models, respectively. We identified a consistent association between higher educational attainment and lower levels of CCL20, CDCP1, and HGF, and higher levels of CST5 at both waves (FDR < 0.1). In addition, we observed that higher educational attainment was associated with lower levels of CCL19, IL-6, and OSM, and higher levels of FGF19 at the second wave only. Nonetheless, all associations were attenuated after adjustment for lifestyle factors, body-mass index, health conditions, and medication. Longitudinal analyses indicated a stable educational gradient across the two waves, with no significant changes in the association between educational attainment and inflammatory protein levels. Our findings indicate a stable educational gradient in the levels of several plasma proteins involved in cell migration, growth, and tissue remodeling in adults, across the seven-to-eight-year period, with modifiable lifestyle factors and body-mass index substantially attenuating the education-protein associations.