The genetic background and vitamin D supplementation can affect irisin levels in Prader–Willi syndrome

Abstract

Background Prader–Willi syndrome (PWS) is associated to distinctive clinical symptoms, including obesity, cognitive and behavioral disorders, and bone impairment. Irisin is a myokine that acts on several target organs including brain adipose tissue and bone. The present study was finalized to explore circulating levels of irisin in children and adult PWS patients. Methods Seventy-eight subjects with PWS, 26 children (15 females, mean age 9.48 ± 3.6 years) and 52 adults (30 females, mean age 30.6 ± 10.7) were enrolled. Irisin serum levels were measured in patients and controls. Its levels were related with anthropometric and metabolic parameters, cognitive performance and bone mineral density either in pediatric or adult PWS. Multiple regression analysis was also performed. Results Irisin serum levels in PWS patients did not show different compared with controls. A more in-depth analysis showed that both pediatric and adult PWS with DEL15 displayed significantly reduced irisin levels compared to controls. Otherwise, no differences in irisin concentration were found in UPD15 patients with respect to controls. Our study revealed that in pediatric PWS the 25(OH) vitamin-D levels affected irisin serum concentration. Indeed, patients who were not supplemented with vitamin D showed lower irisin levels than controls and patients performing the supplementation. Multiple regression analysis showed that irisin levels in pediatric and adult PWS were predicted by the genetic background and 25(OH)-vitamin D levels, whereas in a group of 29 adult PWS also by intelligent quotient. Conclusion We demonstrated the possible role of genetic background and vitamin-D supplementation on irisin serum levels in PWS patients.

One Year of Recombinant Human Growth Hormone Treatment in Adults with Prader–Willi Syndrome Improves Body Composition, Motor Skills and Brain Functional Activity in the Cerebellum

“…Hirsch et al [ 32 ] found salivary irisin was markedly elevated in adults with PWS compared with healthy controls matched by BMI, but no differences in irisin levels after resistance exercise in a study of 11 young patients with PWS [ 58 ]. Our findings are at odds with those reported by Faienza et al [ 31 ], who found no difference in irisin levels between controls and a sample of 73 subjects with PWS, 52 of whom were adults, and with those reported by Mai et al [ 30 ], who found similar levels in obese individuals with PWS and lean healthy controls, but higher levels in obese individuals without PWS [ 30 ].…”

“…By contrast, irisin not only positively regulates muscle growth, but also can convert white adipose tissue to brown fat [ 28 ], increasing energy expenditure and improving glucose tolerance. Discordant myokine levels have been reported in studies in patients with PWS [ 29 , 30 , 31 , 32 ].…”

Irisin and Secondary Osteoporosis in Humans

“…Mai et al also reported that PWS patients and controls had similar circulating irisin levels [ 46 ]. More recently, hypovitaminosis D was found by our group in a cohort of PWS patients [ 47 ]. Interestingly, irisin levels of those not supplemented with 25(OH)-Vitamin D were lower than levels detected in both controls and supplemented patients.…”

“…Interestingly, irisin levels of those not supplemented with 25(OH)-Vitamin D were lower than levels detected in both controls and supplemented patients. Of note, a multiple regression analysis showed that irisin levels in both pediatric and adult PWS were predicted by genetic background and levels of 25(OH)-Vitamin D [ 47 ]. However, further studies are needed to understand the relationship between irisin and 25(OH)-Vitamin D and whether this interaction is influenced by disease type.…”

Growth hormone treatment for adults with Prader-Willi syndrome: another point of view

“…PWS individuals are protected to some degree from the adverse metabolic effects of VAT. Fatty liver is rare in PWS and PWS individuals have less insulin resistance compared to individuals with non-syndromic obesity [ 2 – 5 ]. Nutritional intervention even without growth hormone treatment has been shown to maintain VAT within the normal reference range [ 6 ].…”