sirolimus and Hyperkalemia

Pancreas-kidney transplant is an effective treatment for patients with insulin-dependent dabetes and chronic renal failure. Reduction in technical failure loss and early acute rejection rates contributed to prolong pancreas graft survival. However, drug toxicity affects negatively both short- and long-term follow-ups.. This article reviews the existing literature and knowledge of the immunosuppressive drugs that are frequently used in pancreas transplant, including calcineurin inhibitors, sirolimus, corticosteroids, and mycophenolate. The article also discusses the short- and long-term adverse effects of these drugs. The article also reports and discusses the most relevant in vitro studies, providing additional information to in vivo findings. Some clinically relevant drug interactions with immunosuppressive drugs are also highlighted. Over- and underimmunosuppression effects will not be addressed.. Immunosuppressive regimen after pancreas transplant is very effective and contributed to pancreas allograft survival. However, they present several side effects that are potentiated when drugs are combined. Modifiable and non-modifiable risk factors can aggravate metabolic and toxicological effects of immunosuppressive drugs. It is important to critically analyze the results of clinical studies and investigate new immunosuppressive drugs and/or novel drug combinations. It is equally important to comprehend and interpret experimental data. Therefore, minimization of side effects, based on safe approaches, can prolong pancreas allograft survival.

Topics: Adrenal Cortex Hormones; Bone Diseases; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Gastrointestinal Diseases; Graft Rejection; Graft Survival; Hematologic Diseases; Humans; Hyperkalemia; Hyperuricemia; Immunosuppressive Agents; Mycophenolic Acid; Nervous System Diseases; Pancreas Transplantation; Pneumonia; Renal Insufficiency, Chronic; Sirolimus

Mutation of TSC (encoding tuberous sclerosis complex protein) and activation of mammalian target of rapamycin (mTOR) have been implicated in the pathogenesis of several renal diseases, such as diabetic nephropathy and polycystic kidney disease. However, the role of mTOR in renal potassium excretion and hyperkalemia is not known. We showed that mice with collecting-duct (CD)-specific ablation of TSC1 (CDTsc1KO) had greater mTOR complex 1 (mTORC1) activation in the CD and demonstrated features of pseudohypoaldosteronism, including hyperkalemia, hyperaldosteronism, and metabolic acidosis. mTORC1 activation caused endoplasmic reticulum stress, columnar cell lesions, and dedifferentiation of CD cells with loss of aquaporin-2 and epithelial-mesenchymal transition-like phenotypes. Of note, mTORC1 activation also reduced the expression of serum- and glucocorticoid-inducible kinase 1, a crucial regulator of potassium homeostasis in the kidney, and decreased the expression and/or activity of epithelial sodium channel-α, renal outer medullary potassium channel, and Na(+), K(+)-ATPase in the CD, which probably contributed to the aldosterone resistance and hyperkalemia in these mice. Rapamycin restored these phenotypic changes. Overall, this study identifies a novel function of mTORC1 in regulating potassium homeostasis and demonstrates that loss of TSC1 and activation of mTORC1 results in dedifferentiation and dysfunction of the CD and causes hyperkalemia. The CDTsc1KO mice provide a novel model for hyperkalemia induced exclusively by dysfunction of the CD.

Topics: Animals; Cell Dedifferentiation; Endoplasmic Reticulum Stress; Epithelial Sodium Channels; Female; Homeostasis; Hyperkalemia; Immediate-Early Proteins; Kidney Tubules, Collecting; Male; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Knockout; Multiprotein Complexes; Phenotype; Potassium; Potassium Channels, Inwardly Rectifying; Protein Serine-Threonine Kinases; Sirolimus; Sodium-Potassium-Exchanging ATPase; TOR Serine-Threonine Kinases; Tuberous Sclerosis Complex 1 Protein; Tumor Suppressor Proteins