lithium-chloride and Diabetic-Nephropathies

Topics: Adjuvants, Immunologic; Animals; Diabetic Nephropathies; Glycogen Synthase Kinase 3 beta; Kidney; Lithium Chloride; RANK Ligand; Rats; Rats, Sprague-Dawley; Receptor Activator of Nuclear Factor-kappa B; Signal Transduction

Glycogen synthase kinase 3 (GSK3) plays an important role in the development of diabetes mellitus and renal injury. GSK3 inhibition increases glucose uptake in insulin-insensitive muscle and adipose tissue, while it reduces albuminuria and glomerulosclerosis in acute kidney injury. The effect of chronic GSK3 inhibition in diabetic nephropathy is not known. We tested the effect of lithium, the only clinical GSK3 inhibitor, on the development of diabetes mellitus and kidney injury in a mouse model of diabetic nephropathy. Twelve-week old female BTBR-ob/ob mice were treated for 12 weeks with 0, 10 and 40 mmol LiCl/kg after which the development of diabetes and diabetic nephropathy were analysed. In comparison to BTBR-WT mice, ob/ob mice demonstrated elevated bodyweight, increased blood glucose/insulin levels, urinary albumin and immunoglobulin G levels, glomerulosclerosis, reduced nephrin abundance and a damaged proximal tubule brush border. The lithium-10 and -40 diets did not affect body weight and resulted in blood lithium levels of respectively <0.25 mM and 0.48 mM. The Li-40 diet fully rescued the elevated non-fasting blood glucose levels. Importantly, glomerular filtration rate was not affected by lithium, while urine albumin and immunoglobulin G content were further elevated. While lithium did not worsen the glomerulosclerosis, proximal tubule function seemed affected by lithium, as urinary NGAL levels were significantly increased. These results demonstrate that lithium attenuates non-fasting blood glucose levels in diabetic mice, but aggravates urinary albumin and immunoglobulin G content, possibly resulting from proximal tubule dysfunction.

Topics: Albuminuria; Animals; Blood Glucose; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Drug Evaluation, Preclinical; Female; Glycogen Synthase Kinase 3; Hypoglycemic Agents; Kidney; Lithium Chloride; Mice, Obese

Epithelial-mesenchymal transition (EMT) is important for diabetic nephropathy (DN). Podocytes are specialized epithelial cells, which form a major component of the glomerular filtration barrier. Podocyte damage has been suggested to be the primary mechanism behind the albuminuria associated with DN. The present study aimed to determine the function of glycogen synthase kinase (GSK)‑3β in EMT and barrier dysfunction of mouse podocytes exposed to high glucose (HG) conditions. Matured and differentiated podocytes were treated with normal glucose (NG), HG or NG + mannitol. Podocytes were also transfected with a small interfering RNA (siRNA) against GSK‑3β or a scrambled siRNA, or were treated with lithium chloride (LiCl), a GSK‑3β inhibitor, under NG or HG conditions. The expression levels of the epithelial cell markers, nephrin and podocin, and the myofibroblast cell markers, α‑smooth muscle actin (SMA) and fibronectin, in podocytes by western blot analysis and immunofluorescence staining, respectively. The monolayer barrier function was assessed by albumin inflow. The phosphorylation and activity levels of GSK‑3β were also quantified. It was observed that HG promotes EMT in podocytes, due to the increased levels of podocin and nephrin expression and the reduced α‑SMA and fibronectin expression levels. HG also induced barrier dysfunction and increased the expression level of total GSK‑3β, Try216‑phosphorylated‑GSK‑3β and the GSK‑3β activity in podocytes. Transfection of GSK‑3β siRNA or treatment with LiCl reversed the HG‑induced EMT and barrier dysfunction in podocytes. In conclusion, the present study determined that GSK‑3β is required for EMT and barrier dysfunction in podocytes under HG conditions; therefore, GSK‑3β may be a novel target for the treatment of DN.

Topics: Actins; Animals; Diabetic Nephropathies; Disease Models, Animal; Epithelial-Mesenchymal Transition; Gene Expression Regulation; Glomerular Filtration Barrier; Glucose; Glycogen Synthase Kinase 3 beta; Humans; Intracellular Signaling Peptides and Proteins; Lithium Chloride; Membrane Proteins; Mice; Podocytes; RNA, Small Interfering