Abstract: PO0367
Cilastatin Inhibits Renal Myoglobin Endocytosis and AKI Following Rhabdomyolysis
Session Information
- AKI: Mechanisms of Injury
November 04, 2021 | Location: On-Demand, Virtual Only
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Hebert, Jessica Faith, Oregon Health & Science University, Portland, Oregon, United States
- Burfeind, Kevin G., Oregon Health & Science University, Portland, Oregon, United States
- Nickerson, Megan N., Oregon Health & Science University, Portland, Oregon, United States
- Funahashi, Yoshio, Oregon Health & Science University, Portland, Oregon, United States
- Eiwaz, Mahaba B., Oregon Health & Science University, Portland, Oregon, United States
- Groat, Tahnee, Oregon Health & Science University, Portland, Oregon, United States
- Hutchens, Michael, Oregon Health & Science University, Portland, Oregon, United States
Background
Muscle-derived myoglobin, a renal toxin, causes rhabdomyolysis-induced acute kidney injury (AKI) via megalin-mediated endocytosis into proximal tubule cells (PTs). Endocytosis kinetics and inhibition are poorly understood. We characterized myoglobin uptake in vivo, hypothesizing cilastatin, a putative megalin inhibitor, would prevent endocytosis akin to megalin knockouts.
Methods
Procedures in wild-type (WT) male C57BL/6 mice and inducible, PT-specific megalin-deleted mice (iMegKO) were approved by OHSU or PVAMC IACUC. FITC-myoglobin (FMb) and cilastatin (200 mg/kg) were injected retroorbitally. Experimental rhabdomyolysis (ER) was induced via intramuscular injection of 50% glycerol (8 mL/kg). Glomerular filtration rate (GFR) was measured 24h later, and immunofluorescence and single-cell RNASeq were performed on renal tissue.
Results
FMb was observed in PTs 15 min post-injection in control mice; in iMegKO mice, FMb puncta were nearly absent (p<0.0001). FMb puncta were reduced in cilastatin-treated WTs without ER vs vehicle controls (p=0.0012). iMegKO prevented AKI following ER, with 24h GFR 5x control (p<0.001). Cilastatin injection did not affect GFR in iMegKO (p=0.89), but had a significant effect on ER-induced AKI in wild-type mice: GFR was 8x vehicle (p=0.03) while PT uptake of endogenous myoglobin decreased (p<0.05). A composite score of endocytosis related genes (endoscore) showed significant alterations (Figure 1).
Conclusion
Megalin interference prevents ER-induced AKI by reducing myoglobin endocytosis; cilastatin recapitulates the effect in a megalin-inhibitory fashion. Alteration of endocytosis-related genes confirms this process is critical in rhabdomyolysis, and may suggest additional therapeutic targets. Future studies will also include cilastatin delivery timing, dosage, and formulation.
Funding
- NIDDK Support