Nanobody-Based Treatment Strategies in Glomerulonephritis

Abstract

Glomerulonephritis is a diverse group of renal diseases characterized by immune-mediated damage of the glomerular structures. Without timely therapy, 10% to 15% of glomerulonephritis cases progress to end-stage renal disease, leading to dialysis or kidney failure. Due to the limited treatment options in nephrology, there is a huge need for novel therapies. Several studies have confirmed the involvement of immune cell membrane protein P2X7 in autoimmune and inflammatory diseases, including glomerulonephritis. Blocking of P2X7 or its genetic deletion in animal models has been shown to reduce glomerular damage. In this study, we investigate the therapeutic capacity of nano-bodies, single-domain antibodies of camelids, for blocking the P2X7 ion channel in the treatment of glomerulonephritis. Using P2X7 GFP-transgenic mice, this study showed that the expression level of P2X7 is highly increased by kidney resident cells (T cells and glomerular cells) under inflammatory conditions (nephrotoxic nephritis). The application of immunohistochemistry, flow cytometry, ELISA, and biochemical analysis of blood serum and urine of mice with severe and acute glomerulonephritis models showed no effect of P2X7 blockade on disease parameters. In addition, bulk RNA sequencing of renal T cells isolated from P2X7-blocking nanobody-treated healthy and nephrotic mice showed the upregulation of genes associated with survival, proliferation, cell spreading and migration, indicating involvement in the inflammatory processes. However, P2X7-blocking nanobody therapy of a slowly developing form of membranous nephropathy resulted in the reduction of disease manifestations, including enhanced survival, decreased proteinuria, mitigation of immunisation-related allergic reactions and cases of remission. These contrasting results suggest that while P2X7 blockade may not be sufficient in severe forms of GN, it could offer therapeutic benefits in milder and slowly developing forms of the disease.