A small group of adolescents with obesity who had low levels of the hormone spexin and high levels of the hormone leptin were significantly more likely to have higher concentrations of high sensitivity C-reactive protein and insulin, both markers for cardiovascular disease, according to findings from a pilot study.
Spexin, a recently identified peptide, is encoded by the most down-regulated gene in omental and subcutaneous adipose tissue, Seema Kumar, MD, associate professor of pediatrics in the department of pediatric and adolescent medicine at the Mayo Clinic, and colleagues wrote in the study background. Endocrine Today reported on a related study by the researchers finding that adolescents with obesity may have lower levels of spexin compared with normal-weight adolescents. However, the physiological significance of spexin remains mostly unclear.
“Although in a previous study in children we reported spexin’s ability to discriminate between lean and obese children, its potential physiological role in children and adolescents with obesity and/or its relationships with satiety hormones, biomarkers of CVD and endothelial dysfunction are less clear,” Kumar and colleagues wrote.
Researchers analyzed data from 19 adolescents with obesity but without hypertension or diabetes (mean age, 16 years; 12 boys; 89.5% white; mean BMI, 36.1 kg/m²), assessing spexin and leptin levels and various CVD biomarkers. Within the cohort, 11 adolescents had severe obesity, defined as BMI at least 35 kg/m². Endothelial function was assessed by high-resolution Doppler ultrasonography of the right brachial artery.
Researchers found that spexin concentration (median, 0.38 ng/mL) was inversely correlated with leptin (r = –0.5; P = .03). When participants were stratified by high spexin/low leptin (n = 8) and low spexin/high leptin (n = 11), researchers found that adolescents in the low spexin/high leptin group were 12.25 times more likely to have higher levels of high sensitivity C-reactive protein ( 3 mg/L; 95% CI, –1 to 139). Insulin levels were also higher in the group with low spexin/high leptin; however, the findings did not reach statistical significance.
The researchers observed no associations between spexin levels and measures of endothelial function.
The researchers noted that the difference in findings between the two subgroups may not necessarily prove a causative role for spexin in obesity or obesity-related comorbidities, such as diabetes and CVD.
“Overall, the data from the current study are intriguing and warrant further validation in larger diverse cohorts, not only to further validate the clinical significance of the findings, but also to delineate the underlying mechanisms involved as well,” the researchers wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.