Lithium induces Warburg‐like proliferation of principal cells in lithium‐induced Nephrogenic Diabetes Insipidus and underlies its collecting duct remodeling
Authors: Alsady Mohammad , van der Tholen Leunie , Bedford Jennifer , Walker Robert , de Groot Theun , Deen Peter 
Published: November 2023

IntroductionLithium is the first‐choice medication for treatment of bipolar disorder, but causes Nephrogenic Diabetes Insipidus (Li‐NDI), a urinary concentrating defect. Li‐NDI is characterized by polyuria, polydipsia and metabolic acidosis, and is caused by downregulation of principal cell AQP2 and an increased intercalated/principal cell ratio of the collecting duct (remodeling). Recently, others and we showed that lithium induces principal cell proliferation in vitro and in vivo, which can be due to aerobic glycolysis (Warburg effect), a condition in which the cells switch from oxidative phosphorylation to glycolysis to produce cell building blocks and ATP. Collecting duct remodeling has been ascribed to metabolic acidosis due to inhibition of α‐intercalated cells H‐ATPase and H/K‐exchangers, but, as aerobic glycolysis goes with increased lactate excretion, this may also underlie remodeling. This was investigated here.MethodsPolarized mpkCCD cells were cultured in transwells and exposed to LiCl chloride on the apical (10 mM) and basolateral side (1 mM) to mimic clinical conditions in patients. C57BL6/J mice were fed a normal rodent diet or a diet with lithium chloride in a concentration of 40 mmol/kg of chow. Rats were treated similarly with/without amiloride for 4 weeks. 24‐hrs water intake and urine output/osmolality was obtained. Kidneys were analyzed for remodeling.ResultsLithium induced proliferation in mpkCCD cells (increased PCNA levels) coincided with increased excretion of lactate, increased abundance of lactate dehydrogenase, hexokinase‐2, and a decreased ratio of phospho‐pyruvate dehydrogenase pPDH/PDH. These aerobic glycolysis characteristics were also found in the kidney and urine of mice treated for 10 days with lithium. Li‐induced increase in urinary lactate, however, was absent in mice lacking the epithelial sodium channel ENaC, the principal cell entry pathway for lithium. Moreover, 4‐weeks treatment of rats with lithium revealed NDI, lactate excretion and collecting duct remodeling, which where all attenuated in the presence of amiloride. In mpkCCD cells, inhibition of lithium‐induced glycolysis using 2‐deoxyglucose slightly attenuated lithium‐induced downregulation of AQP2 abundance and cell surface expression. 2‐deoxyglucose also significantly reduced the lithium‐induced increase in lactate production in 10‐day treated mice, but did not reduce urine volume or increase urine osmolality.Conclusionwe show that the ENaC‐mediated lithium influx in principal cells induces aerobic glycolysis in mpkCCD cells, mice and rats and that inhibition of principal cell lithium entry attenuates the extent of aerobic glycolysis and collecting duct remodeling. Inhibition of aerobic glycolysis, however, did not attenuate Li‐NDI. Our data indicate that the lithium‐induced aerobic glycolysis of principal cells and the consequent acidification of the micro‐environment underlies collecting duct remodeling.