Adipocyte C1QTNF5 expression is BMI-dependently related to early adipose tissue dysfunction and systemic CTRP5 serum levels in obese children.

BACKGROUND/OBJECTIVES: The recently identified adipocytokine C1QTNF5 (encodes for CTRP5) has been demonstrated to inhibit pro-metabolic insulin signaling in adipocytes. We hypothesized that adipocyte C1QTNF5 expression in subcutaneous (sc) adipose tissue (AT) would correlate with the degree of obesity, systemic CTRP5 serum levels, and early AT and metabolic dysfunction in children. SUBJECTS/METHODS: Sc AT samples were obtained from 33 healthy Caucasian lean children aged 10.06±4.84 years and 42 overweight and obese children aged 13.34±3.12 years. C1QTNF5 expression in sc AT as well as in investigated cell lines was assessed by quantitative real-time PCR. Systemic CTRP5 levels were assessed by ELISA. RESULTS: C1QTNF5 expression in sc adipocytes increased with body mass index (BMI) standard deviation score (SDS; R=0.48, P<0.001), body fat percentage (R=0.4, P=0.004), adipocyte number (R=0.69, P<0.001) and systemic CTRP5 serum levels (R=0.28, P=0.025) whereas expression in the stromal vascular fraction (SVF) was inversely correlated with BMI SDS (R=-0.24, P=0.04). Multiple regression analysis confirmed that BMI SDS was the strongest independent predictor for C1QTNF5 expression in sc adipocytes. SVF C1QTNF5 levels strongly correlated with SVF CD31 expression (R=0.54, P<0.001) indicating expression by endothelial cells. Primary human endothelial cells demonstrated stronger expression compared with human Simpson-Golahbi-Behmel syndrome pre-adipocytes and adipocytes. Adipocyte C1QTNF5 expression levels were BMI-dependently related to fasting insulin (R=0.3, P=0.03) and leptin serum levels (R=0.5, P<0.001). Sc AT samples containing crown-like structures (CLS) demonstrated increased adipocyte C1QTNF5 expression compared to CLS-negative samples (P=0.03). Functionally, tumor necrosis factor (TNF)α caused a fourfold induction of C1QTNF5 in human adipocytes (P<0.001) and a 50% reduction in primary human endothelial cells (P<0.001). CONCLUSIONS: In children adipocyte C1QTNF5 expression is already strongly related to the degree of obesity and is associated with obesity-related AT alterations, systemic CTRP5 serum levels as well as circulating markers of metabolic disease and is positively regulated by TNFα in vitro.

Vitamin D supplementation and its influence on muscle strength and mobility in community-dwelling older persons: a systematic review and meta-analysis.

BACKGROUND: It has been suggested that vitamin D status or supplementation is important for maintaining or improving muscle strength and mobility in older adults. The study results, however, do not provide consistent results. We therefore aimed to summarise the available evidence systematically, including only studies conducted in community-dwelling older persons. METHODS: A systematic search of the literature was performed in April of 2016. The systematic review includes studies that used vitamin D with or without calcium supplementation as the exposure variable and various measurements of muscle strength and mobility. The meta-analysis was limited to studies using hand grip strength (HGS) and timed-up-and-go test as the outcome variables. RESULTS: A total of 15 studies out of 2408 articles from the literature search were included in the systematic review, providing 2866 participants above the age of 65 years. In the majority of studies, no improvement in muscle strength and mobility was observed after administration of vitamin D with or without calcium supplements. In the meta-analysis, we observed a nonsignificant change in HGS [+0.2 kg (95% confidence interval = -0.25 to 0.7 kg; seven studies)] and a small, significant increase in the timed-up-and-go test [0.3 s (95% confidence interval = 0.1 to 0.5 s; five studies)] after vitamin D supplementation. The meta-analyses showed a high degree of heterogeneity between the studies. CONCLUSIONS: In conclusion, we observed no improvement in muscle strength after the administration of vitamin D with or without calcium supplements. We did find a small but significant deterioration of mobility. However, this is based on a limited number of studies and participants.