TLR4 and IgA glomerulonephritis: Furthermore, bilirubin participates in immune response at several levels including modulation of regulatory T cells and T helper type 17 (Th17) cells, inhibition of the Toll-like receptor 4/nuclear factor kappaB signaling pathway, down-regulation of NLRP3 inflammasome 8, 24-26, which has been proved to be very important for IgA nephropathy in a previous study by our team 27.