Supported Research

Lay Abstract

Background: Kidneys act as a barrier that filters water and waste products into urine while retaining important proteins in blood. When this barrier is damaged, massive leakage of proteins into urine (proteinuria) occurs, leading to a condition known as nephrotic syndrome. Idiopathic nephrotic syndrome (INS) is a common cause of nephrotic syndrome in children, and it also affects adults. The precise cause of INS is unknown, and the disease is treated with non-specific broad immune-suppressive drugs such as glucocorticoids. While the initial response is usually excellent, more than half of affected persons experience many relapses of the disease, which necessitate repeated courses of immune-suppressive treatment. The cumulative side-effects of the non-specific immune-suppressive drugs have serious negative impacts on the health and the quality of life of the affected individuals, especially children. Therefore, to be able to provide personalized, specific, and less-toxic treatment options, it is imperative to understand the precise mechanisms by which the disease occurs. Objective: The effectiveness of broad immune suppression indicates that a dysfunctional immune system is likely a cause of INS. However, the kidney of INS patients does not show typical signs of inflammation with immune cells, and so, INS has remained a “mysterious disease” despite five decades passing since its initial description. Recently, our group and others showed that a group of cells in the immune system of INS patients called B cells are making antibodies that attack a particular cell type within the kidney called podocytes. In this proposal, we will identify which cells are responsible for making antibodies that attack podocytes and cause INS. Experimental plans: First, we will take B cells from children while INS is flared and analyze them by the state-of-the-art technology called ‘single-cell RNA-sequencing (scRNA-seq)’. By analyzing the genes expressed by each B cell, we will determine the precise type of B cell associated with INS. At the same time, using a technique called ‘V(D)J-sequencing’, we will obtain the gene sequence of the antibodies being produced by these B cells. The results will inform us about the type of immune response taking place in INS, which is important for the development of new B cell-targeting therapies. At this point, we still do not know if the identified antibody is targeting podocytes or not. To know this, we will take the B cells identified above into a culture system and expand them with stimuli to make them produce the antibody. We will then test if the antibody binds to the proteins expressed in podocytes. We will also study if the genes encoding this antibody is identical to the one identified by V(D)J-sequencing above. Altogether, we will know the identity of the B cell that is making the antibody that attacks podocytes. Finally, we will study if B cells that produce podocyte-attacking antibody are still present after the treatment with rituximab, the B cell-depleting drug often used in INS to maintain a longer remission. The presence of these antibody-producing cells likely predicts an eventual relapse of INS, a common event despite treatment with rituximab. Significance: If successful, the results will be transformative; we will establish INS as an autoimmune disease, identify podocyte proteins in the kidney as the target, and determine which cells are responsible for generating the antibody against podocytes. In the long-term, the results will help identify new biomarkers that allow more accurate diagnosis and prediction of relapses, and disease-causing B cells that can be targeted by personalized, novel, and safer therapies for the individuals affected with INS.