Background Obesity and osteoarthritis are two multifactorial pathologies that are becoming major medical issues with the aging of the world population and which often appear together. The relationship of osteoarthritis with obesity is complex, involving metabolic and developmental links with inflammatory status in different tissues. Nutritional and pharmacological factors capable of simultaneously targeting the two conditions are of interest.

Objectives Our initial studies revealed interesting effects of a glycosaminoglycan (GAG) mixture on adipose cells differentiated in culture. Here, we aimed at testing in an animal study the potential of a commercial preparation rich in that particular GAG mixture and used in osteoarthritis management (Oralvisc™, Bioiberica S.A., Palafolls, Spain) as a co-adjuvant in weight loss strategies.

Methods 25-week-old C57BL6/J male mice made obese through high fat-diet feeding displaying a 22% excess body weight relative to controls at the start of the experiment were used. On day 0, the mice were switched to a normal-fat diet and distributed into two groups that received the vehicle (water, control group) or the GAG-rich preparation (treatment group), at a dose of 3 mg/mouse/day (n=7-8 animals/group) daily, by oral route. Body weight, body composition (using a non-invasive magnetic resonance system), and food intake were regularly monitored. The animals were sacrificed on day 32, and blood and tissues were collected. Q-PCR was used to measure the expression of selected genes in gonadal white adipose tissue (gWAT) and brown adipose tissue (BAT), as well as mitochondrial DNA content in gWAT.

Results Animals treated with the GAG-enriched preparation tended to lose more body weight and faster than those in the control group, and showed a higher and faster loss of body fat after switching to the normal-fat diet. At sacrifice, adiposity index was 30% lower and circulating leptin levels (which reflect body fat content) 40% lower in the animals treated with the GAG-enriched preparation, which also displayed reduced leptin gene expression in gWAT. Treated animals also showed signs of increased insulin sensitivity, with equal glucemia but lower insulinemia compared with controls. No differences between the two groups were found concerning cumulative energy intake during the 32 days experimental period and Ucp1 and Ppargc1a expression in BAT. However, gene expression of various thermogenic and oxidative metabolism-related genes (Ppara, Cpt1b, Cox5a, Ucp1) were higher in gWAT of treated animals, in which mitochondrial DNA content was also found elevated.

Conclusions The results suggest that the GAG rich preparation tested might be useful as a co-adjuvant in weight loss strategies, and may favor mitochondrial activity in WAT.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.5581