Deep single-cell RNA sequencing-based analysis of early transcriptional responses in inflammatory and non-inflammatory podocyte disease

• Applicant: Dr. Linus Butt
• Subject Area: Nephrology
• Term: from 2023 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 521176426

Chronic kidney diseases affect more than 10% of the world’s population, constituting a major health care burden. As its incidence increases with age and co-morbidities like diabetes and hypertension, Western societies face a growing need for patient-centered care. Etiologically, kidney diseases are diverse, yet the majority originate from the glomerulus, the site of kidney ultrafiltration. Ultrafiltration requires an elaborate filtration barrier as the filter almost entirely restricts filtration of albumin and other macromolecules and maintains permselectivity over decades. The filtration barrier consists of a fenestrated endothelium, the glomerular basement membrane (GBM) and podocytes, specialized visceral epithelial cells. Loss of podocytes is the hallmark of a histopathological diagnosis called focal and segmental glomerulosclerosis (FSGS). Primary FSGS is presumably triggered by a circulating factor that drives morphological changes in podocytes ultimately leading to podocyte loss. Histologically, FSGS is not characterized by inflammatory infiltrates. Several other glomerulopathies result from circulating mediators, antibodies or immune complexes, some of which are clinically particularly relevant as they are associated with rapidly progressive glomerulonephritis (RPGN), which is characterized by massive inflammatory infiltrates. The most common underlying diseases in RPGN are systemic lupus erythematosus, anti-GBM disease or ANCA-associated vasculitis. Even though podocytes are not the primary target in these diseases, they also respond to the mediator with massive cytoskeletal reorganization. Current treatments for non-inflammatory and inflammatory glomerular diseases have limited efficacy and significant side effects, and there are no specific therapies available to date. Podocyte-specific responses to the underlying mediators such as circulating factors or immune complexes are still ill-defined. The overarching goal of this project is to decipher the cell-specific early response to injury in RPGN (inflammatory) and FSGS (non-inflammatory) by investigating both conditions in mouse models as well as the FSGS-model in a pre-clinical model using human kidneys. To achieve this, I will focus on generating single-cell RNA-sequencing-based atlases of the transcriptional changes in glomerular cells. In addition to using established animal models, the host institution has access to human kidneys undergoing ex vivo normothermic perfusion (EVNP). Human kidneys rejected for transplantation in the University of Cambridge Transplantation Program will be recruited into the study. EVNP kidneys declined for transplantation will be challenged with FSGS patient serum to mimic the early phase of primary FSGS.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professorin Menna Clatworthy