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Coxsackie, adenovirus receptor may affect adipose tissue dysfunction in patients with obesity
Originally identified as a common receptor for coxsackie B viruses and type C adenoviruses, the coxsackie and adenovirus receptor could play a role in adipose tissue dysfunction, according to research published in The Journal of Clinical Endocrinology & Metabolism.
Marta Serrano, PhD, of the Girona Biomedical Research Institute in Spain, and colleagues observed an increased expression of coxsackie and adenovirus receptor (CAR) in adipose tissue in patients with obesity, mainly in stromal vascular cell fraction (SVF).
“Previous reports have linked CAR with the innate immune response to myocarditis and with activation of inflammatory cells in vitro,” the researchers wrote. “Our results broaden the spectrum of functions of CAR beyond its already known roles.”
The investigators conducted an ex vivo study using 91 visceral adipose tissue (VAT) and 109 subcutaneous adipose tissue (SAT) samples (61 paired). The tissues, collected during elective surgical procedures, were from patients recruited from the Endocrinology Service at Josep Trueta University Hospital.
CAR messenger RNA (mRNA) was measured in samples, then confirmed at protein level and in adipose tissue fractions. The inflammatory stimuli effects on CAR gene expression also were assessed.
CAR was 46-fold higher in VAT compared with SAT (P<.0001) in paired samples, and similarly elevated at protein level (P=.04); in both fat depots, CAR was seen mostly in SVF.
In patients with obesity vs. those without obesity, CAR mRNA (P=.006) and protein levels (P=.01) in VAT were higher. Further, CAR mRNA levels in SAT positively correlated with both BMI (r=0.26; P=.008) and percent fat mass (r=0.28; P=.004).
After adjusting for BMI and age, MGLL, FSP27, AKAP, omentin, TKT, S14 and FABP independently contributed to CAR mRNA variation in VAT. In mature adipocytes in vitro, macrophage-conditioned medium resulted in increased CAR gene expression.
“Our data provide evidence that CAR might be considered as a new marker of visceral adipose tissue regarding fat depot distinction in association with obesity-related [adipose tissue] dysfunction,” the researchers wrote. “Moreover, CAR might play an important role in the immune cells infiltration of adipose tissue. Additional work will be necessary to determine a causal role of CAR in modulating adiposity.”
Disclosure: This work was supported by the Spanish Ministry of Health and the Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition, an initiative from the Carlos III Health Institute.