RON Kinase Inhibitor Ameliorates Podocytes Injury in Sickle Cell Disease Mouse Model

INTRODUCTION: Endothelial dysfunction is a major pathophysiological feature of sickle cell disease (SCD). We demonstrated that RON kinase signaling contributed to the renal endothelial injury in SCD mice. Treatment of SCD mice with RON inhibitor BMS777607 (RONi) reduced renal endothelial injury and glomeruli permeability and ameliorated glomerular disease. Podocytes play a key role in the maintenance of glomerular filtration barrier. HYPOTHESIS: We hypothesize that RONi reduces podocytes injury in SCD mice. METHODS: Five-month-old mice were injected daily with 10 mg/kg of body weight of RONi subcutaneously for 10 consecutive days. Control group was injected with 2% DMSO (vehicle). Four SCD and control (ctrl) mice per treatment were used. Paraffin embedded kidney sections were labeled with mouse anti-WT-1 (Thermo Scientific), rabbit anti-nephrin and rabbit-anti-podocin (both from Abcam) antibodies. Images were generated on Olympus Ix51 microscope with Olympus DP 72 camera and analyzed using ImageJ. Transmission electron microscopy (TEM) was performed in GW nanofabrication and imaging center (The George Washington University). Statistical analysis was performed using GraphPad Prism 7.05. Comparison of means for multiple groups was performed by two-way ANOVA with Bonferroni’s multiple-comparisons test. Comparisons between two groups was analyzed with Student’s t test and p<0.05 was considered statistically significant. RESULTS: The glomerular size (p=3x10 -8 ), capillary size (p=2x10 -7 ) and capillary congestion in SCD mice injected with RONi were significantly reduced compared to the SCD mice injected with vehicle. Number of WT-1 positive podocytes per glomeruli was lower in SCD mice injected with vehicle compared to Ctrl mice injected with vehicle (p=0.0005). RONi treatment did not alter the number of WT-1 positive podocytes in Ctrl and SCD mice. Nephrin and podocin expression in glomeruli of SCD mice injected with vehicle was lower than in Ctrl mice. RONi treatment increased nephrin and podocin expression in both Ctrl and SCD mice. TEM showed foot processes fusion and effacement, glomerular basement membrane thickening (p=0.012), and capillary congestion in SCD mice injected with vehicle. Treatment with RONi restored normal foot process structure and reduced the thickness of basement membrane to normal (p=0.067) and reduced capillary congestion. CONCLUSIONS: RONi treatment restored podocytes morphology in SCD mice without changing number of podocytes per glomeruli. These results suggest that ultra-structural changes in filtration barrier components may be associated with reduction of congestion and size of glomerular capillary. Future study is needed to evaluate whether RONi directly affects podocytes. This work was supported by NIH grants R01HL125005, U54MD007597, and SC1HL150685. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.