Abstract: TH-OR014
Targeted Inhibition of Cathepsin L Attenuates Renal Fibrosis
Session Information
- CKD: Exploring Intertwined Mechanisms of Disease Progression
November 06, 2025 | Location: Room 362A, Convention Center
Abstract Time: 05:10 PM - 05:20 PM
Category: CKD (Non-Dialysis)
- 2303 CKD (Non-Dialysis): Mechanisms
Authors
- Chen, Huini, State Key Laboratory of Multi-organ Injury Prevention and Treatment, National Clinical Research Center of Kidney Disease, Renal Division, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
- Chen, Yudan, State Key Laboratory of Multi-organ Injury Prevention and Treatment, National Clinical Research Center of Kidney Disease, Renal Division, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
- Liu, Jixing, Centre for Artificial Intelligence Driven Drug Discovery, Macao Polytechnic University, Macao SAR, China
- Liang, Dongning, State Key Laboratory of Multi-organ Injury Prevention and Treatment, National Clinical Research Center of Kidney Disease, Renal Division, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
- Fu, Haiyan, State Key Laboratory of Multi-organ Injury Prevention and Treatment, National Clinical Research Center of Kidney Disease, Renal Division, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
Background
Renal fibrosis is a hallmark of chronic kidney disease (CKD), driven in part by maladaptive repair of renal tubular epithelial cells (TECs). This study investigates Cathepsin L (CTSL), a lysosomal enzyme aberrantly overexpressed in proximal TECs in CKD. Using animal and cell models and clinical samples, we examined the pathological role and mechanisms of CTSL in renal fibrosis and evaluate natural-product-derived CTSL inhibitors as potential CKD therapeutics.
Methods
Proximal tubule-specific CTSL knockout and pharmacologically inhibited mice were used in IRI- and UUO-induced CKD models. Multi-omics and proteolytic screening identified CTSL downstream targets, validated in vivo. Through molecular docking, molecular dynamics, free energy calculations, mutagenesis, and microscale thermophoresis, CTSL-specific inhibitors were identified. Key binding sites were mapped, and therapeutic efficacy was confirmed in vivo and in vitro.
Results
CTSL is upregulated in renal TECs in both clinical CKD specimens and murine models. Genetic deletion or pharmacologic inhibition of CTSL in proximal tubules reduced inflammation and fibrosis and improved TEC integrity in IRI and UUO models. In cultured TECs, blocking CTSL attenuated TGF-β-induced G2/M arrest, inflammation, and partial epithelial-mesenchymal transition (pEMT). Multi-omics and functional studies identified six CTSL substrates aberrantly cleaved in the cytoplasm and nucleus, contributing to tubular injury via degradation-dependent dysregulation. Virtual screening of 60,000 natural compounds identified limonin as a CTSL inhibitor. Docking, free energy calculations, mutagenesis, and thermal shift assays confirmed its direct binding to key active-site residues (Trp26, Leu69, Met70, Met161), thereby occluding the catalytic site and inhibiting CTSL activity. In vitro and in vivo, limonin inhibited CTSL activity, protected TECs, reduced inflammation, and mitigated renal fibrosis, slowing CKD progression.
Conclusion
Kidney injury induces aberrant CTSL overexpression and lysosomal leakage, driving CKD progression. CTSL impairs tubular repair by degrading cell-cycle regulators and protective factors, promoting inflammation and fibrosis. The natural CTSL inhibitor limonin mitigates these effects, offering protection across diverse CKD causes.
Funding
- Government Support – Non-U.S.