Elevated Circulating CD16+ Monocytes and TLR4+ Monocytes in Older Adults with Multiple Cardiometabolic Disease Risk Factors: A Cross-Sectional Analysis

ABSTRACT We endeavored to examine relationships between circulating monocyte phenotype and cardio-metabolic disease risk, in healthy, older adults. We performed a secondary data analysis on men and women, 55-75 yr, who were assigned to groups based on cardio-metabolic risk factors other than age. Subject in the low risk group (n=16, 12 females) had fewer than three risk factors. Subjects in the elevated risk group (n=29, 19 females) had three or more risk factors. Along with baseline screening for fitness and body composition, resting blood samples were assessed for markers of inflammation including: monocyte phenotype (inflammatory monocytes), monocyte cell-surface TLR4 expression, and serum C-reactive protein. The low risk group had a smaller (19.3% difference; p 0.05) between the low and elevated risk groups for BMI, serum cholesterol, fasting glucose, or leg press 1RM. The low risk group had lower CRP (114.7%, p=0.0002), higher CD14+CD16- (classical) monocytes (6.7%; p=0.0231) and fewer CD14+CD16+ (inflammatory) monocytes (46.2%; p=0.0243) than the elevated risk group. The low risk group also had a lower percentage of CD14+CD16+ monocytes that were positive for TLR4 (14.0%; p=0.0328). Older men and women with fewer cardio-metabolic risk factors had lower serum and cellular markers of inflammation and higher aerobic capacity.