Hasegawa N, et al. - Researchers investigated healthy subjects (n=127) to determine the link between aging-induced increase in serum complement C1q (C1q), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) levels and arterial stiffness. Middle-aged and older subjects (≥40 years) vs young subjects (<40 years) exhibited significantly higher serum C1q, TNF-α, and IL-6 levels and carotid-femoral pulse wave velocity (cfPWV; arterial stiffness index). Following adjustment for 11 confounders, an independent contribution of C1q level to the cfPWV variation was reported. After the age of 30 years, a slow rise in cfPWV, along with an increase in circulating C1q level, was seen. A rise in TNF-α and IL-6 levels was evident after age 50 years, later than the increase in C1q. Based on these findings, the aging-related elevation of arterial stiffness could be indicated by serum C1q level. The potential of serum C1q level as a new biomarker of arterial stiffness was also suggested in this study.