Immunoglobulin A nephropathy: current progress and future directions

Immunoglobulin A (IgA) nephropathy is the most prevalent form of primary glomerulonephritis that often leads to end-stage kidney failure, thereby representing a major health challenge worldwide. Tremendous effort has been dedicated to the diagnosis, monitoring, and treatment of the disease, and the past several years have witnessed exciting advances that have enriched our understanding of the biology, etiology, and pathology of IgA nephropathy. The disease is characterized by predominant deposition of IgA immune complexes that progressively causes activation of mesangial cells, glomerular inflammation, and ultimately renal injury. Multiple recent independent high-throughput studies in cohorts have identified key susceptibility alleles, such as the major histocompatibility complex loci that are significantly associated with the risk of disease occurrence. Notably, a fraction of these risk loci encode proteins that participate in immune defense against mucosal pathogens, particularly intestinal nematodes, indicating a linkage between IgA-mediated antihelminth immunity and the pathogenesis of IgA nephropathy. The emerging "omics" technology also allows for systemic analysis of urinary and serum samples as a noninvasive procedure for diagnosis and prognosis, as demonstrated by several studies implicating the proteomic signature and microRNA profile as promising diagnostic and prognostic parameters. In the clinic, the current treatment protocol relies on suppression of the renin-angiotensin system to control blood pressure and proteinuria. This review scrutinizes and summarizes recent relevant findings that aim to translate researchers' benchside knowledge of disease initiation and development into patients' bedside diagnosis and therapy.