Novel PAR2 antagonist ameliorates progression of lupus nephritis in NZB/Z F1 mice

Abstract

Lupus nephritis (LN) is, the most frequent phenotype in patients with systemic lupus erythematosus (SLE), has a high rate of progression to end‐stage renal disease, even with intensive induction and maintenance therapies, approximately 20% of patients with LN progress to end‐stage renal disease. Recent evidence suggests that protease‐activated receptor‐2 (PAR2) is a therapeutic target for glomerulonephritis. In this study, we identified a novel PAR2 antagonist and evaluated the effect of the PAR2 antagonist on LN in lupus‐prone mouse model. To identify novel PAR2 antagonist, a cell‐based high‐throughput screening was performed. The effect of PAR2 antagonist on podocytes was observed in human podocyte cell line and LN was evaluated in NZB/W F1 mice. We identified punicalagin (PCG, a major polyphenol in pomegranate) as a novel potent PAR2 antagonist. In human podocyte cell line, PCG potently inhibited PAR2 (IC50 = 1.5 ± 0.03 μM) with ~30‐fold selectivity for PAR2 over PAR1 and significantly reduced the PAR2‐mediated activation of ERK1/2 and NF‐κB signaling pathway. In addition, PCG strongly decreased PAR2‐induced increases in ICAM‐1, VCAM‐1, IL‐6, IL‐8, IFN‐γ, and TNF‐α expression. Notably, in NZB/W F1 mice, which spontaneously develop severe autoimmune syndrome resembling human SLE and LN, the intraperitoneal administration of PCG significantly alleviated kidney injury and splenomegaly and reduced proteinuria and renal ICAM‐1 and VCAM‐1 expression. Our results suggest that PCG has beneficial effects on LN via inhibition of PAR2, and PCG is a potential therapeutic agent for LN.Support or Funding InformationThis research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A1B03029050), a faculty research grant of Yonsei University College of Medicine (6‐2016‐0159) to Sang‐Won Lee, NRF (2015R1D1A1A01057695 and 2018R1A6A1A03023718) to Wan Namkung, and NRF (2019R1I1A1A01061117) to Yohan Seo. This research was supported (in part) by the Yonsei University Research Fund (Post Doc. Researcher Supporting Program) of 2019 (project no.: 2019‐12‐0013).Schematic overview of inhibitory effect of Punicalagin (PCG) on lupus nephritis in human podocytes and NZB/W F1 mice.The inhibition of PAR2 by PCG reduced PAR2‐induced ERK1/2 and NF‐κB activation in human podocyte cell line. Notably, PCG ameliorated kidney injury, proteinuria, and splenomegaly in NZB/W F1 mice and reduced ICAM‐1 and VCAM‐1 levels via PAR2 inhibition.Figure 1