Intrarenal single cell sequencing of MPO-ANCA associated glomerulonephritis patients reveal novel targetable treatment options
The etiopathogenesis underlying myeloperoxidase anti-neutrophil cytoplasmic antibody associated glomerulonephritis (MPO-AAGN) remains incompletely understood. Furthermore, there are only limited treatment options and treatment resistance of MPO-AAGN is still a common problem. To identify new targeted treatment options, intrarenal single-cell RNA sequencing (scRNA-seq) was applied to kidney biopsies from MPO-AAGN patients and control health kidney tissues to define the transcriptomic landscape at single-cell resolution. Intrarenal scRNAseq was also applied to a pre-clinical mouse model of MPO-AAGN to show that this model of disease can be used to trial new targeted treatments. NF-?B pathway activation was confirmed in a variety of kidney cells in MPO-AAGN patients. Kidney infiltrating immune cells of MPO-AAGN patients were mainly enriched in inflammatory pathways including TNF signaling, IL-17 signaling and NOD-like receptor signaling. These findings were similar in our pre-clinical mouse model of MPO-AAGN. Furthermore, there was an overexpression of inflammasome related genes (AIM2, IFI16) in MPO-AAGN patients. A dynamic gene expression in glomerular resident cells was observed in MPO-AAGN, including increased expression of several genes, including CD9 and SPARC, which were closely related to parietal epithelial hyperplasia and crescent formation and lesion progression. Importantly, overexpression of HSP90AA1 in non-focal mesangial cells and endothelial cells was found and the expression of several chemokines (CCL20, CXCL3, CXCL8, CXCL1, CCL2) were upregulated in non-focal proximal tubule cells. Moreover, MPO-AAGN patients with treatment resistance had higher proportions of kidney infiltrating classical monocytes and CD8+ T cells. Elevated expression of SPARC and LAMA4 in mesangial cells, IL33 in endothelial cells, and CFL1 in several cell clusters (proximal tubule cells, loop of Helen, macrophages) were observed in MPO-AAGN patients with treatment resistance when compared with patients who achieved remission after induction therapy. These results offer new insight into the pathogenesis of the progression and treatment resistance MPO-AAGN. We have identified new therapeutic targets for MPO-AAGN that can be tested in a pre-clinical model of disease. Overall design: Single cell suspensions of mouse kidney were prepared from MPO-AAGN and healthy wild-type mice and scSeq was performed.