Effect of short-term high fat diet on resistin levels and expression of autophagy-related genes in the cartilage of male rats

Obesity is a significant risk factor for the development of knee osteoarthritis (KOA). However, the precise molecular mechanisms linking obesity to OA remain unclear. In the present study, we investigated the effect of short-term high-fat diet (HFD) on the development of OA and the possible role of the adipokine resistin and autophagy-related genes in mediating this effect. Thirty adult male Wistar rats were equally divided into 2 groups: control and obese groups. Body mass index (BMI), levels of lipid profile, glucose, insulin and HOMA-IR index were significantly higher in the obese group compared with control. Our results revealed significantly higher serum and cartilage resistin levels with a significant increase in the mRNA expressions of toll-like receptor 4 (TLR4), matrix metalloproteinase-9 (MMP-9) and interleukin-1β (IL-1β) as well as protein levels of IL-1β, matrix metalloproteinase-13 (MMP-13), ADAMTS 5 (aggrecanase-2) and caspase-3 in the cartilage of obese rats. The HFD induced a significant upregulation of autophagy related 5 (ATG5), beclin-1 and light chain 3 (LC3) mRNA expressions and a significant downregulation of mammalian target of rapamycin (mTOR) expression in cartilage. The protein levels of cartilage ATG5 were also significantly elevated in HFD-fed group. In conclusion, we suggested that increased levels of resistin and expression of autophagy-related genes may contribute in part, to OA development in HFD-fed rats. This provides a novel insight into the early molecular changes in the cartilage associated with obesity.