Correlation of circulating C1q and C1q-binding adiponectin concentrations with aging in males: a preliminary report

BACKGROUND Atherosclerosis is an age-related disease. Adiponectin and C1q form a protein complex in human blood, and that serum C1q and C1q-binding adiponectin (C1q-APN) concentrations can be measured. We investigated circulating C1q and C1q-APN levels in Japanese men including elderly men. FINDINGS The study subjects were 509 Japanese men including elderly men. Serum levels of total adiponectin (Total-APN), high-molecular weight-adiponectin (HMW-APN), C1q-APN and C1q were measured by enzyme-linked immunosorbent assay. Total-APN, HMW-APN and C1q-APN, but not C1q, correlated significantly and positively with aging (r=0.26, r=0.24, r=0.17, p<0.01, respectively). The HMW-APN/Total-APN ratio correlated significantly and positively with aging (r=0.14, p<0.01). The C1q-APN/Total-APN ratio and C1q-APN/HMW-APN ratio correlated significantly and negatively with aging (r=-0.17, p<0.01, r=-0.12, p=0.01). C1q-APN/C1q correlated significantly and positively with aging (r=0.09, p=0.03). Multiple regression analysis identified age and body mass index as significant determinants of C1q-APN. CONCLUSIONS The present study demonstrates that serum HMW-APN, C1q-APN, and Total-APN, but not C1q, correlated positively with aging. These preliminary results could form the basis for future research. TRIAL REGISTRATION CLINICAL TRIAL REGISTRATION NUMBER UMIN000004318.