RESUMO
Whole-exome sequencing of two unrelated kindreds with systemic autoimmune disease featuring antinuclear antibodies with IgG4 elevation uncovered an identical ultrarare heterozygous TNIP1Q333P variant segregating with disease. Mice with the orthologous Q346P variant developed antinuclear autoantibodies, salivary gland inflammation, elevated IgG2c, spontaneous germinal centers and expansion of age-associated B cells, plasma cells and follicular and extrafollicular helper T cells. B cell phenotypes were cell-autonomous and rescued by ablation of Toll-like receptor 7 (TLR7) or MyD88. The variant increased interferon-ß without altering nuclear factor kappa-light-chain-enhancer of activated B cells signaling, and impaired MyD88 and IRAK1 recruitment to autophagosomes. Additionally, the Q333P variant impaired TNIP1 localization to damaged mitochondria and mitophagosome formation. Damaged mitochondria were abundant in the salivary epithelial cells of Tnip1Q346P mice. These findings suggest that TNIP1-mediated autoimmunity may be a consequence of increased TLR7 signaling due to impaired recruitment of downstream signaling molecules and damaged mitochondria to autophagosomes and may thus respond to TLR7-targeted therapeutics.
RESUMO
Accumulation of immunoglobulin and complement components within the kidneys is a hallmark of glomerulonephritis. Staining and detection of IgG, IgA, IgM, and C3 deposits can assist in diagnosing the underlying causes of nephritis and has implications for the pathological processes underpinning glomerulonephritis. Here, we describe a protocol to detect immune deposits within biological specimens such as mouse kidneys. We detail tissue isolation and processing, immunostaining, and fluorescence microscopy to characterize and quantify the extent of immunological deposits contributing to kidney injury. For complete details on the use and execution of this protocol, please refer to Jiang et al. (2021).
