XDH and metabolic syndrome: UA: uric acid; MetS: metabolic syndrome; NLRP3: NOD-like receptor family pyrin domain containing 3; AMPK-mTOR-mROS: adenosine monophosphate (AMP)-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR)-mitochondria-derived reactive oxygen species (mROS); HIF-1α: hypoxia-inducible factor 1-alpha; ROS-IRS1/Akt: reactive oxygen species-insulin receptor substrate-1 (IRS1)/serine or threonine kinase or protein kinase B; XO: xanthine oxide; NO: nitric oxide; XOR: xanthine oxidoreductase; NAFLD: nonalcoholic fatty liver disease; NA: not applicable