Injury Induced Paracrine Effects on the Podocyte’s Transcriptome

Although injury in glomerular disease might only damage a subset of podocytes in any given glomerulus, the response of the healthy neighboring podocytes to the injured podocytes oftentimes determines the course of the disease. To investigate this relationship, we designed a dual chamber open microfluidic co-culture device to specifically examine paracrine signaling to healthy podocytes from podocytes targeted injured by either Adriamycin, Puromycin Aminonucleoside or a cytopathic anti-podocyte antibody. Global transcriptomic analysis measured by RNA-sequencing revealed shared and unique pathways between the three forms of targeted injury, with temporal differences in the transcriptomic responses to each form of injury. Paracrine-induced injury to neighboring podocytes was similar to the targeted primary injured podocytes and was specific for each podocyte injury model. Ligand-receptor analysis of ligands secreted by the insult targeted podocytes and receptors expressed by the responsive, paracrine injured counterparts identified 23 candidate mediator pairs. These findings critically define a new concept for future studies to understand the pathways involved in secondary cellular injury fields in animal models and ultimately human studies. Primary, human podocytes were seeded into a two-chamber microfluidic device. The podocytes in the outer chamber were injured using either (i) a cytopathic anti-podocyte antibody (IgG), (ii) puromycin aminonucleoside (PAN), or (iii) Adriamycin/doxorubicin (ADR). The podocytes in the inner chamber remained naïve (uninjured). After 24-hours post-injury, the two chambers were connected by flooding with shared media. Autocrine and paracrine effects of the injury models were assessed with mRNA sequencing at 24- and 96-hours post-injury.