Receptor interacting protein kinase 1 activation and triggering mesangial cells necroptosis in MRL/lpr mice model of lupus nephritis.

Abstract

Lupus nephritis (LN) is the most common complication of systemic lupus erythematosus (SLE) affecting the kidneys. Receptor-interacting protein kinase 1 (RIPK1) is involved in necroptosis and inflammatory signaling. Here, we investigate the role of RIPK1 kinase activity in the pathogenesis of LN. Immunofluorescent colocalization of necroptosis with podocyte, endothelial cells, and mesangial cells was detected in the kidney of MRL/lpr mice. In vivo studies used ZJU37 (a RIPK1 inhibitor) to treat MRL/lpr mice to evaluate LN pathological alterations. In vitro, mouse mesangial cells were stimulated with DMSO, serum from MRL/lpr mice, and serum + ZJU37 to detect cell viability, cell death status, expression of necroptosis-related molecular proteins, and significant pathway alterations accompanied by necroptosis. We also conducted functional assay to validate the biological significance of the pathway changed. Firstly, the involvement of RIPK1/RIPK3/MLKL-dependent necroptosis was shown in the mesangial cells of MRL/lpr mice. Secondly, we found that ZJU37 inhibited glomerulonephritis, tubulointerstitial lesions, and vasculitis by reducing the necroptosis of mesangial cells in MRL/lpr mice. Moreover, we discovered that mesangial cells are susceptible to necroptosis when stimulated with serum from MRL/lpr animals and identified the primary altered pathways, including cytokine-cytokine receptor interaction and the PI3K-Akt signaling pathway, which could be abolished by ZJU37. Functional assay showed ZJU37 could significantly increase the migration and cell proliferation ability of mesangial cells. RIPK1 activation triggered mesangial cell necroptosis was identified in the kidneys of MRL/lpr mice and Inhibition of RIPK1 could alleviate LN by reducing the necroptosis of mesangial cells.