Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease

Immunoglobulin A (IgA) nephropathy is the most common type of primary glomerulonephritis worldwide. Several studies indicated that 6-43% of IgA nephropathy patients would develop end-stage kidney disease (ESKD) over a period of 10 years. The clinical risk factors for progression are hypertension, protienuria, impaired renal function and histologic lesions at presentation. There is no well accepted optimal therapy for patients with IgA. Current established therapies include full RAS inhibition and optimal blood pressure control for patients with proteinuria and/or hypertension.

Hydroxychloroquine has been used for many years to treat malaria. It is also used to treat systemic lupus erythematosus, rheumatic disorders like rheumatoid arthritis and Sjögren's Syndrome. Recently, several studies found that Hydroxychloroquine could reduce the risk of ESRD in patients with lupus nephrits. The mechanism of the treatment wasn't well known so far. Some investigators found that Hydroxychloroquine increases lysosomal pH in antigen presenting cells. In inflammatory conditions, it blocks toll-like receptors on plasmacytoid dendritic cells (PDCs). Toll-like receptor 9 (TLR 9), which recognizes DNA-containing immune complexes, leads to the production of interferon and causes the dendritic cells to mature and present antigen to T cells. Hydroxychloroquine, by decreasing TLR signaling, reduces the activation of dendritic cells and the inflammatory process.

The pathogenesis of IgA nephropathy included the deposition of immune complex containing IgA in mesangium and causing local immune activation and injury to kidney. Therefore, Hydroxychloroquine might have the potential effect of anti-inflammation in patients with IgA nephropathy, reduced the proteinuria and had the renal protect effect.

Our study will recruite IgA nephropathy patients with proteinuria range from 0.75 to 3.5g/d even after three-month treatment by sufficient ACEi/ARB. The patients were treated with Hydroxychloroquine 300-400mg/d according to eGFR. The proteinuria will recorded every two months and total four months. Then, the drug will be stopped for two months for observation of change of proteinuria.