BACKGROUND: In several reports C3 and C4 have been linked to diabetes and cardiovascular disease (CVD). Here we investigate this link and the degree of C3 activation in elderly individuals.
METHODS: In the present study, C3 and C4 and the activation fragment C3a-desArg were analyzed in 1016 subjects aged 70, in which blood pressure, lipid variables and fasting blood glucose were assessed.
RESULTS: C3 levels were related to all the investigated classical cardiovascular risk factors and the metabolic syndrome (BMI, waist circumference, fat distribution, blood pressure, blood glucose levels, TG) except total cholesterol and LDL-cholesterol in a highly significant fashion (Spearman up to 0,5; p<0.0001). C4 and C3a-desArg were associated in the same fashion but less significantly, while the ratios C4/C3 or C3a-desArg/C3 were not, indicating that the association was not directly related to complement activation. The levels C3 and to a lesser degree C4 and C3a-desArg, were associated particularly to CRP, but also to E-selectin and ICAM-1. In addition, C3 and C4 levels were shown to decline significantly in 15 female subjects enrolled in a weight-reduction program over 4 months.
CONCLUSION: A strong relation between C3, C4 and C3a-desArg levels, adipose tissue and risk factors of CVD was established. The data support that the adipose tissue produces complement components and generates initiators of inflammation, such as C3a and C5a, able to trigger a cyto/chemokine response, in proportion to the amount of adipose tissue. This corroborates the concept that complement contributes to the low-grade inflammation associated with obesity. This article is protected by copyright. All rights reserved.