Intermittent high altitude hypoxia induced liver and kidney injury leading to hyperuricemia

Abstract

About 140 million people worldwide live at an altitude above 2500 m. Studies have showed an increase of the incidence of hyperuricemia among plateau populations, but little is known about the possible mechanisms. This study aims to assess the effects of high altitude on hyperuricemia and explore the corresponding mechanisms at the histological, inflammatory and molecular levels. This study finds that intermittent hypobaric hypoxia (IHH) exposure results in an increase of serum uric acid level and a decrease of uric acid clearance rate. Compared with the control group, the IHH group shows significant increases in hemoglobin concentration (HGB) and red blood cell counts (RBC), indicating that high altitude hyperuricemia is associated with polycythemia. This study also shows that IHH exposure induces oxidative stress, which causes the injury of liver and renal structures and functions. Additionally, altered expressions of organic anion transporter 1 (OAT1) and organic cation transporter 1 (OCT1) of kidney have been detected in the IHH exposed rats. The adenosine deaminase (ADA) expression levels and the xanthione oxidase (XOD) and ADA activity of liver of the IHH exposure group have significantly increased compared with those of the control group. Furthermore, the spleen coefficients, IL-2, IL-1β and IL-8, have seen significant increases among the IHH exposure group. TLR/MyD88/NF-κB pathway is activated in the process of IHH induced inflammatory response in joints. Importantly, these results jointly show that IHH exposure causes hyperuricemia. IHH induced oxidative stress along with liver and kidney injury, unusual expression of the uric acid synthesis/excretion regulator and inflammatory response, thus suggesting a potential mechanism underlying IHH-induced hyperuricemia.