XDH and endothelial dysfunction: Endothelial dysfunction by XO is initiated when XO in the circulation bind to the sulfated GAG in the surface of endothelial cells [7, 11, 57], catalyzing the formation of uric acid and superoxide radicals, triggering the production of proinflammation cytokine [19, 21], which then independently trigger cell apoptosis [38], disturbing the permeability and the function of cell barrier [58], and finally causing the endothelial dysfunction.