Abstract
Glomerular diseases like focal and segmental glomerulosclerosis (FSGS) are the leading cause of chronic and end-stage kidney diseases. Although FSGS is associated with high morbidity and mortality, available treatments are limited, which emphasizes the need for novel therapy. We developed a dual inhibitor, PTUPB, that concurrently acts as a soluble epoxide hydrolase (sEH) inhibitor and a cyclooxygenase-2 (COX-2) inhibitor. In the current study, we investigated renal actions of PTUPB in a genetic renal hypoplasia FSGS model, ROP Os/+ mice. ROP Os/+ mice developed albuminuria and glomerular injury between 16 and 20 weeks of age with an 8-fold higher albumin/Cr ratio than wild-type ROP +/+ mice. Three groups were assessed: 20-week-old ROP +/+ mice, ROP Os/+ mice treated with vehicle, and ROP Os/+ mice treated with PTUPB (10 mg/kg/d, i.p.). After 4 weeks, urine, blood, and kidney tissue were collected in the mice groups for biochemical, molecular, and histological analysis. ROP Os/+ mice had 10-fold higher albuminuria than ROP +/+ mice, and PTUPB treatment markedly attenuated albuminuria in ROP Os/+ mice by 69 %. ROP Os/+ mice developed a glomerular injury with a 3-fold higher glomerular injury score and 10-fold higher glomerular expression of sclerotic marker fibronectin than ROP +/+ mice, and PTUPB treatment attenuated these by 40-50 %. We further demonstrated that there was significantly lower renal mRNA expression of nephrin, podocin, podoplanin, synaptopodin, and glomerular WT1 immunopositive cells in ROP Os/+ mice which was improved by PTUPB treatment in these mice. Glomerular permeability studies in isolated glomeruli determined that COX-2 metabolites of 8,9-epoxyeicosatrienoic acid (EET) increased glomerular permeability. PTUPB, 8,9-EET, or 8,9-EET analogs prevented angiotensin II-induced glomerular permeability and mesangial cell proliferation. These findings demonstrate that COX-2 metabolites harm the glomerulus, whereas 8,9-EET improves glomerular function. Lastly, kidney fibrosis and inflammation were increased in ROP Os/+ mice compared to ROP +/+ mice. PTUPB treatment to ROP Os/+ mice decreased kidney fibrosis and inflammation. These findings demonstrate that the dual inhibitor PTUPB that concurrently inhibits sEH and COX-2 is a potential treatment for FSGS and related glomerular diseases.