Compositions and methods for treating and preventing endoplasmic reticulum (ER) stress-mediated kidney diseases

1. A method of treating a subject in need thereof having an endoplasmic reticulum (ER) stress-mediated kidney disease comprising: administering a therapeutically effective amount of a pharmaceutical composition comprising K201 or mesencephalic astrocyte-derived neurotrophic factor (MANF) to the subject.

2. The method of claim 1 , wherein the therapeutically effective amount of K201 or MANF is an amount sufficient to reduce apoptosis and injury in podocytes or tubular cells or to stabilize ER calcium channels in podocytes or tubular cells, compared to a control or the subject prior to administration of K201 or MANF.

3. The method of claim 1 , wherein the therapeutically effective amount of K201 or MANF reduces RyR2 phosphorylation in podocytes or reduces calcium leaks in ER-stressed podocytes or tubular cells.

4. The method of claim 1 , wherein the therapeutically effective amount of K201 or MANF: inhibits ER stress-mediated pro-apoptotic pathways, suppressing ER stress-induced apoptosis; inhibits ER stress-induced calcium efflux from the ER to cytosol in kidney cells; inhibits ER calcium depletion; inhibits albuminuria; decreases urinary calpain activity; corrects leaky RyR2 calcium channels; inhibits podocyte or tubular cell injury; inhibits podocyte or tubular cell apoptosis; or decreases proteinuria, compared to a control or the subject prior to administration of K201 or MAN F.

5. The method of claim 1 , wherein K201 or MANF is a podocyte ER calcium channel stabilizing agent.

6. The method of claim 1 , wherein

the therapeutically effective amount of MANF is an amount sufficient to reduce RyR2 phosphorylation; block RyR2-Ser2808 phosphorylation-mediated ER calcium depletion, inhibit calpain 2 activation, decrease cleavage of spectrin and talin 1, suppress active cleaved caspase 12, reduce CHOP induction, and reduce early apoptotic rate in podocytes or tubular cells; or

the therapeutically effective amount of K201 is an amount sufficient to suppress phosphorylation of RyR2; block RyR2-Ser2808 phosphorylation-mediated ER calcium depletion; decrease proteinuria; or block or inhibit podocyte injury in ER-stressed podocytes.

7. The method of claim 1 , wherein the ER stress-mediated kidney disease is selected from the group consisting of: a podocyte ER stress-mediated glomerular disease; a diabetic nephropathy; a primary nephrotic syndrome; renal fibrosis; a tubular ER stress-mediated kidney disease; and chronic kidney disease caused by an ER stress-mediated kidney disease.

8. The method of claim 7 , wherein

(i) the primary nephrotic syndrome is selected from the group consisting of: focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), and minimal change disease (MCD);

(ii) the podocyte ER stress-mediated glomerular disease is selected from the group consisting of: minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), hereditary nephrotic syndrome, sporadic nephrotic syndrome, diabetic nephropathy (DN), Alport syndrome, chronic kidney disease (CKD) caused by nephrotic syndrome (NS), and podocyte ER stress-mediated diabetic nephropathy (DN); or

(iii) the tubular ER stress-mediated disease is selected from the group consisting of: autosomal dominant tubulointerstitial kidney disease (ADKTD), ischemic acute kidney injury, autosomal dominant polycystic kidney disease (ADPKD), and renal fibrosis.

9. The method of claim 8 , wherein the tubular ER stress-mediated disease is selected from the group consisting of renal fibrosis, autosomal dominant tubulointerstitial kidney disease (ADTKD), ischemic acute kidney injury, and autosomal dominant polycystic kidney disease (ADPKD).