Identifying Cellular Surface Components in Mesangial Cells in IgA Nephropathy

Patients with IgA nephropathy (IgAN), a prevalent glomerulonephritis, commonly develop end-stage renal disease. More than one million individuals worldwide are impacted by IgAN. At present there is no disease-specific therapy for the treatment of IgAN, creating a need for the development of targeted therapeutic strategies for early diagnosis. IgAN is characterized by the predominant autoimmune complex deposition in the glomerular mesangium, but there are no clear definitions of the genetic regulators of the preferential accumulation of those IgAN immune complexes on the mesangial cells.

During a poster session at ASN Kidney Week 2024, researchers from Northwestern University, Evanston, Illinois, led by Ranjit Singh Atwal, PhD, presented results of a study designed to identify the cellular surface component(s) that drive the predominant accumulation of autoimmune complexes on the mesangial cells. The poster was titled Identification of Cellular Determinants Impacting Mesangial Cells in IgA Nephropathy.

The researchers utilized a magnetic ranking cytometry platform (LEAPFROG) in combination with genome-scale CRISPR/Cas9 pooled screening across primary mesangial cells and other nonimpacted/nonmesangial kidney cell types in parallel.

They used pooled surfaceome libraries to profile the impact of individual surface proteins on the sensitivity of galactose-deficient IgA induced IgAN complex deposition. They also utilized the commercially available monoclonal anti-Gd-IgA1 antibody or the in vitro purified IgAN complexes to enrich subpopulation of mesangial cells with either high or low levels of IgAN complex deposit phenotypes.

To date, the researchers have completed the lentiviral CRISPR guide RNA library targeting the cell surfaceome, encompassing 3,000 unique surface proteins, with a total of 12,450 unique guides. They have generated cosmic knock out DAKIKI cell line for production of galactose-deficient IgA. In combination with the KM555 antibody, the reagents are being used for phenotypic screening of primary mesangial cells to identify genetic determinants with an impact on IgAN.

In summary, the authors said, “Use of LEAPFROG-powered CRISPR-cas9 based loss-of-function phenotypic screening is anticipated to identify potentially druggable targets for IgAN.”

Source: Atwal RS, Quaggin SE, Munshi HH, Kelley SO. Identification of cellular determinants impacting mesangial cells in IgA Nephropathy. TH-PO540. Abstract of a poster presented at the American Society of Nephrology; October 24, 2024; San Diego, California.