Project description:UNC93B1 is critical for trafficking and function of nucleic acid-sensing Toll-like receptors (TLRs) TLR3, TLR7, TLR8, and TLR9, which are essential for antiviral immunity. Overactive TLR7 signaling induced by recognition of self-nucleic acids has been implicated in systemic lupus erythematosus (SLE). Here, we report UNC93B1 variants (E92G and R336L) in four patients with early-onset SLE. Patient cells or mouse macrophages carrying the UNC93B1 variants produced high amounts of TNF-α and IL-6 and upon stimulation with TLR7/TLR8 agonist, but not with TLR3 or TLR9 agonists. E92G causes UNC93B1 protein instability and reduced interaction with TLR7, leading to selective TLR7 hyperactivation with constitutive type I IFN signaling. Thus, UNC93B1 regulates TLR subtype-specific mechanisms of ligand recognition. Our findings establish a pivotal role for UNC93B1 in TLR7-dependent autoimmunity and highlight the therapeutic potential of targeting TLR7 in SLE.
Project description:Systemic autoimmune diseases such as lupus and scleroderma are characterized by the loss of tolerance to nuclear antigens, but the mechanisms by which specific autoantibodies are selected are unclear. Here we report that B cells containing the Y-linked autoimmune accelerator (Yaa) locus are intrinsically biased towards nucleolar antigens due to a duplication of TLR genes in the pseudoautosomal region that makes them more responsive to TLR7 ligands and augments the Btk-dependent signaling pathway. These findings provide genetic evidence that naturally occurring differences in expression of TLR7 have a dramatic impact on antigen selection in autoimmunity. Follicular B cells were isolated from spleen of C57BL/6 male and C57BL/6.Yaa male. Four mice from each group using in this analysis were 2 months old. Dye swab labeled RNA had been done in one mice from each group.
Project description:Systemic autoimmune diseases such as lupus and scleroderma are characterized by the loss of tolerance to nuclear antigens, but the mechanisms by which specific autoantibodies are selected are unclear. Here we report that B cells containing the Y-linked autoimmune accelerator (Yaa) locus are intrinsically biased towards nucleolar antigens due to a duplication of TLR genes in the pseudoautosomal region that makes them more responsive to TLR7 ligands and augments the Btk-dependent signaling pathway. These findings provide genetic evidence that naturally occurring differences in expression of TLR7 have a dramatic impact on antigen selection in autoimmunity. Keywords: genetic modification, Yaa locus
Project description:While circumstantial evidence supports enhanced TLR7 signaling as a mechanism of human systemic autoimmune disease, we have lacked the proof afforded by lupus-causing TLR7 gene variants. Here we undertook a whole exome sequencing (WES) approach to identify novel TLR7 variants in human lupus patients. We establish the importance of TLR7 for human SLE pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.
Project description:NOD mice spontaneously develop lacrimal gland inflammation. NOD mice that lack TLR7 or that lack IFNAR1 are protected from developing lacrimal gland inflammation. RNA sequencing studies were performed to compare gene expression profiles in lacrimal glands from wild-type (WT) vs Tlr7 knockout or Ifnar1 knockout nonobese diabetic (NOD) mice to determine disease-relevant gene and pathway profiles upregulated in WT lacrimal glands in either a TLR7- or IFNAR1-dependent manner.
Project description:Endosomal Toll-like receptors (TLRs) play an important role in the etiology of systemic autoimmune diseases such as SLE, where DNA- and RNA-associated autoantigens activate autoreactive B cells through TLR9- and TLR7-dependent pathways, respectively. Nevertheless, TLR9-deficient autoimmune prone mice develop more severe clinical disease, while TLR7-deficient and TLR7/9-double deficient autoimmune-prone mice develop less severe disease. To determine whether the regulatory activity of TLR9 is B cell intrinsic, we have now directly compared the functional properties of autoantigen activated WT, TLR9-deficient and TLR7-deficient B cells, in an experimental system where proliferation depends on BCR/TLR co-engagement. In vitro, TLR9-deficient cells are less dependent on survival factors for a sustained proliferative response than either WT or TLR7-deficient cells. The TLR9-deficient cells also preferentially differentiate toward the plasma cell lineage, as indicated by expression of CD138, sustained expression of IRF4, and other molecular markers of plasma cells. In vivo, autoantigen-activated TLR9-deficient cells give rise to greater numbers of autoantibody producing cells. Our results identify distinct roles for TLR7 and TLR9 in the differentiation of autoreactive B cells that explain the capacity of TLR9 to limit, and TLR7 to promote, the clinical features of SLE. AM14 WT, Tlr7-/-, Tlr9-/- and Tlr7/9-/- B cells were stimulated with PL2-3 for 0, 6, 24, and 42 hours, for a total of 16 samples.