Mitochondria-derived reactive oxygen species contribute to synergistic interaction of diabetes and hypertension in causing chronic kidney injury

Diabetes (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. The combination of DM and HTN significantly accelerates development of renal injury; however, the underlying mechanisms of this synergy are still poorly understood. This study assessed whether mitochondria (MT) dysfunction is essential in developing renal injury in a rat model with combined DM and HTN. Type 1 DM was induced in Wistar rats by streptozotocin. HTN was induced 6 wk later by interrenal aorta constriction (AC) between the renal arteries, so that right kidneys were exposed to HTN while left kidneys were exposed to normotension. Kidneys exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion (UAE). In contrast, kidneys exposed to DM + 8-wk HTN had significantly increased UAE and glomerular structural damage with reduced glomerular filtration rate. Marked increases in MT-derived reactive oxygen species (ROS) were also observed in right kidneys exposed to HTN + DM. We further tested whether treatment with MT-targeted antioxidant (MitoTEMPO) after the onset of HTN attenuates renal injury in rats with DM + HTN. The results showed that kidneys in DM + AC + MitoTEMPO rats had lower UAE, less glomerular damage, and preserved MT function compared with untreated DM + AC rats. Our study indicates that MT-derived ROS play a major role in promoting kidney dysfunction when DM is combined with HTN. Preserving MT function might be a potential therapeutic approach to halt the development of renal injury when DM coexists with HTN.