IL-9: a novel pro-podocyte survival cytokine in FSGS

Progressive focal segmental glomerulosclerosis, characterized by podocyte loss, is often refractory to treatment and leads to progressive proteinuric chronic kidney disease. Interleukin-9 (IL-9) is reported to play important roles in innate and adaptive immunity in extrarenal inflammatory diseases. By using an IL-9 knockout mouse model, Xiong et al. demonstrate IL-9 as a novel pro-podocyte survival cytokine in the adriamycin nephropathy model of focal segmental glomerulosclerosis. Sequential in vitro and in vivo data corroborate a direct protective role, rather than an immunologic role, for IL-9 on podocyte survival. This commentary highlights these novel data and discusses the necessary steps for developing IL-9 as a potential novel therapeutic for focal segmental glomerulosclerosis.