The accumulation of adipose tissue, especially visceral fat, represents a risk factor for reduced bone mineral density and spontaneous fractures. Several mechanisms have been proposed to explain the complex relationship between adipose tissue and bone. Obesity is associated with the production of inflammatory cytokines both by adipocytes and immune cells which may stimulate bone resorption and reduce bone strength. Studies in vitro and in vivo have reported that cherries have anti-inflammatory and antioxidant activity due to high content of polyphenols, expecially anthocianins. We aimed to investigate the effects of different concentrations of anthocyanins contained in extracts of three cherry varieties (Giorgia, Bigaretta, Ferrovia) on osteoclasts differentiation. We obtained peripheral blood monuclear cells (PBMCs) from 10 obese children and 10 normal weight controls (mean age 10.8±2.56 years) to evaluate the percentage of osteoclast precursors CD14+CD16+ and to perform cultures of osteoclasts. These cells were grown for about 25 days in the presence/absence of extracts of cherry varieties Giorgia, Bigaretta, Ferrovia at different concentrations of anthocyanins (75, 100 μg/ml). Multinucleated mature osteoclasts were identified by histochemical TRAP staining. Gene expression was evaluated by real-time PCR in PBMCs from obese children treated for 24 h with Giorgia, Bigaretta, Ferrovia at 100 μg/ml anthocyanins. The bone mineralization status of the patients was assessed by quantitative ultrasonography (QUS), by measuring BTT-Z score and Ad-Sos-Z-score. A reduction of bone mineral density was found in obese subjects compared to controls (P <0.01). A high percentage of CD14+CD16+ osteoclast precursors was measured in patients compared to controls. It was associated to the spontaneous formation of osteoclasts in PBMC cultures, in the absence of exogenous growth factors, unlike what occured in cultures of controls. This spontaneous osteoclastogenesis seems to be associated with the presence of pro-osteoclastogenic cytokines released from the same cells in culture, such as RANKL and TNFa. Consistently, the treatment with extracts from Giorgia, Bigaretta, Ferrovia determined a dose-dependent reduction in the formation of multinucleated TRAP+ osteoclasts as well as the reduction of the expression of RANKL and TNFa in PBMCs.
Conclusions: These results suggest that the anthocyanins present in the cherry extracts reduce the production of inflammatory cytokines in cultures and therefore the formation of osteoclasts. It can therefore be assumed that if introduced into the diet of obese children these compounds can have health-promoting effects and in particular can improve bone quality.
27 Sep 2018 - 29 Sep 2018