Defining diagnostic trajectories in patients with podocytopathies

Characterization of immortalized human podocytes infected with lentivirus as an in vitro model of viral infection-associated podocytopathy

A large number of studies have shown the association of kidney disease with viral infections in the body. Viral infections cause kidney injury in two manners, the systemic inflammation (cytokine storm) and the direct infection of kidney cells. Concerning direct viral infection of podocytes, the mechanism underlying virus-induced podocyte injury remains largely unknown and requires effective experimental models to facilitate its study. Here, we performed molecular characterization of immortalized human podocyte cell line (HPC) infected with lentivirus by RNA-seq. Bioinformatics analysis revealed a strong innate immune response in the cells, including interferon production and signaling. Meanwhile, activations of ferroptosis pathway and TNF-alpha signaling were also found, consistent with an impaired viability of the cells. Lentiviral infection also upregulated expression of APOL1 as observed in patients with HIV associated nephropathy (HIVAN) and diabetic nephropathy (DN). Interestingly, when the lentiviral infected cells were treated with Adriamycin (ADR), the ADR-associated signaling pathways were not interfered and remained activated as that in the cells treated with ADR only, suggesting that the virus and ADR have distinct mechanisms in damaging podocytes. Thus, the lentivirus-infected HPC cells represent a useful in vitro model of viral infection-associated podocytopathy.

Cytoskeleton Rearrangement in Podocytopathies: An Update

Podocyte injury can disrupt the glomerular filtration barrier (GFB), leading to podocytopathies that emphasize podocytes as the glomerulus's key organizer. The coordinated cytoskeleton is essential for supporting the elegant structure and complete functions of podocytes. Therefore, cytoskeleton rearrangement is closely related to the pathogenesis of podocytopathies. In podocytopathies, the rearrangement of the cytoskeleton refers to significant alterations in a string of slit diaphragm (SD) and focal adhesion proteins such as the signaling node nephrin, calcium influx via transient receptor potential channel 6 (TRPC6), and regulation of the Rho family, eventually leading to the disorganization of the original cytoskeletal architecture. Thus, it is imperative to focus on these proteins and signaling pathways to probe the cytoskeleton rearrangement in podocytopathies. In this review, we describe podocytopathies and the podocyte cytoskeleton, then discuss the molecular mechanisms involved in cytoskeleton rearrangement in podocytopathies and summarize the effects of currently existing drugs on regulating the podocyte cytoskeleton.

Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis

The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.