Project description:Murine CD3+ T-cells were immunomagnetically purified from the spleens of C57BL/6J mice and were pretreated in vitro for three days in the presence of R848 (5 μg/ml). Gene expression profile of wild type (WT) C57BL/6J TLR7-primed T-cells, was compared to unmanipulated B6 TLR7 null CD3+ Τ-cells. We used Qiagen Toll-like Receptor RT2 Profiler PCR Array kit to quantitate gene expression profiling of the TLR signaling pathway.
Project description:Murine CD3+ T-cells were immunomagnetically purified from the spleens of C57BL/6J mice and were pretreated in vitro for three days in the presence of R848 (5 μg/ml). Unmanipulated T-cells served as negative control. We used Qiagen Toll-like Receptor RT2 Profiler PCR Array kit to quantitate gene expression profiling of the TLR signaling pathway.
Project description:The debilitating autoimmune disease Systemic Lupus Erythematosus (SLE) is closely associated with Toll-like receptor (TLR) 7 and type I interferon (IFN) activity in humans and in murine SLE-like disease. Two central manifestations of SLE affect the myeloid lineage of the immune system, myeloid expansion and anemia. Yet, whether these symptoms are linked and the role of TLR7 and/or type I IFN in these processes is unclear. Here we show that TLR7 signaling promotes cell-autonomous, phosphoinositide 3-kinase (PI3K)- and mammalian target of rapamycin (mTOR)-dependent macrophage development from the common myeloid progenitor (CMP). Strikingly, this TLR7-driven macrophage development requires and is enhanced by type I IFN. Genome-wide transcriptional profiling and functional studies demonstrated that TLR7 promoted the expression of Spic, the master regulator of splenic red pulp macrophages (RPM) and preferential development of hemophagocytic RPM-like cells from CMP in vitro. We found increased incidence of RPM-like cells in vivo in a mouse model of SLE caused by TLR7 overexpression, which correlated with decreased red blood cell (RBC) count and anemia. These findings demonstrate a mechanism by which TLR7 signaling promotes anemia that is of clinical significance in SLE, other rheumatological diseases and chronic viral infections. This work also identifies a previously unknown molecular pathway by which TLR signaling and type I IFN synergize to promote myeloid development from hematopoietic progenitors. CMP were sorted from the bone marrow of wild-type C57BL/6 mice, cultured with SCF+R848 or SCFr+MCSF, and CD11b+F4/80+ macrophages sorted after 5 days, n=3 per 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. 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:PCR Array Profiling - R848 does not induce TLR-signaling related genes in TLR7-/- mice. Aim: To corroborate TLR7-dependency of R848 in mice "Triggering TLR7 in mice induces immune activation and lymphoid system disruption, resembling HIV-mediated pathology", Baenziger et al. Blood 2008
Project description:In the activated B-cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), the most frequent gain-of-function mutations target MyD88, a signaling adapter for Tolllike receptors (TLRs). The most prevalent oncogenic mutant, MyD88 L265P, occurs in 29% of cases and is the most active in engaging the NF-kappaB pathway. Here we show that MyD88 mutants do not function autonomously, but rather require TLR7, TLR9, and to a lesser extent, TLR4 to promote the survival of ABC DLBCL cells. Unlike wild type MyD88, MyD88 mutants associate constitutively with TLR7 and TLR9 in ABC DLBCL cells. Like ligand-induced TLR7/9 signaling in normal immune cells, the survival of ABC DLBCL cell lines depends upon translocation of TLR7 and TLR9 to acidic endolysosomes, where proteolytic processing of their ligand binding ectodomains is required for their oncogenic signaling. ABC DLBCL viability also depends upon CD14, a co-receptor for TLR7 and TLR9 that promotes engagement of nucleic acid ligands by these receptors. Point mutations in the TLR7 or TLR9 ectodomains that abrogate ligand binding and/or signaling were incapable of sustaining ABC DLBCL survival. An inhibitory oligonucleotide that suppresses TLR9 responses in normal B cells blocked NF-kappaB signaling and survival of ABC DLBCL lines. Together, these data suggest that an endogenous TLR ligand may play a pathogenic role in ABC DLBCL and provide a rationale for targeting TLR signaling to improve therapy of this aggressive lymphoma. Gene expression was analyzed using Agilent human 2-color 4X44K oligo gene expression arrays. Cell line, TMD8 ABC-DLBCL, was infected with control (shControl, Cy3), shLTR7 (Cy5) or shLTR9 (Cy5) and changes in gene expression were monitored on day 1 and day 2 after induction of the shRNA with doxycycline, co-hybridizing control and experimental samples (Cy3+Cy5), for a total of 4 arrays.
Project description:T cells from many patients with systemic lupus erythematosus are hypoproliferative in response to TCR ligation. This defect is mediated, at least in part, through down regulation of the TCR zeta chain. Investigation of this phenomenon in lupus-prone mice revealed that the hypoproliferative T cell phenotype apparent in BXSB males is mediated in part by the Yaa locus. The BXSB model of lupus is a recombinant inbred strain that was originally derived from a cross between a male SB/LE mouse and a female C57BL/6 mouse. BXSB is unique among lupus-prone mouse strains, in that males carry an autoimmune accelerating factor on the Y chromosome, termed Yaa, which accelerates disease onset in male BXSB mice so that fatal glomerulonephritis occurs around 6 months of age. It was recently reported that the Yaa locus is a translocation of a short stretch of genes including that encoding Toll-like receptor 7 (Tlr-7) from the X to the Y chromosome, leading to a two-fold over expression of a subset of these genes, including Tlr-7, and hypersensitivity of Yaa+ cells to TLR-7 agonists. To more fully understand the functional significance of the Yaa gene and how it plays a part in the modulation of CD4+ T cell responses, we performed microarray analysis using Affymetrix 430 2.0 arrays on spleens from B6 male B6.Yaa male samples. The analysis revealed an enhanced signature of innate immunity, including increased expression not only of Tlr7 and Tlr8, in line with reports that the Yaa locus leads to a duplication of the murine Tlr7 and Tlr8 genes , but also of Tlr2, Tlr5, Cd14, Lbp, C2, C3 and genes for several heat-shock proteins. T cells from B6.Yaa mice also displayed decreased TCR? expression. Interestingly, cell surface levels of the inhibitory molecule B7-H1 were increased on B6.Yaa B cells and monocytes/macrophages. In line with increased TLR-7 expression reported in B6.Yaa mice, the TLR-7 agonist imiquimod increased B7-H1 expression on normal B cells. Restoration of proliferation in co-cultures of B6 T cells and B6.Yaa APC with B7-H1 blocking Ab demonstrated a mechanistic contribution of B7-H1 up-regulation to Yaa-mediated APC-dependent T cell hypoproliferation. In addition, T cell hypoproliferation was induced in normal B6 T cells in vitro by the application of imiquimod. However, this defect was not mediated by B7-H1 or secreted factors but was independent of APC and mediated through direct imiquimod stimulation of T cells themselves. We postulate that excessive TLR-7 stimulation in Yaa+ mice mediates T cell hypoproliferation in part through up-regulation of B7-H1 and possibly also through direct T cell-mediated effects. Keywords: differential gene expression, RNA, spleen, C57Bl/6J, B6.SB-Yaa/J, male, wild type, Yaa Control mice: four C57Bl/6J male spleens Experimental mice: three B6.SB-Yaa/J male spleens and one pool of two B6.Yaa male spleens for the third Yaa sample (GSM236622) All mice were obtained from the Jackson Laboratories between March and December 2005. Spleen cell suspensions were prepared by teasing spleen tissue through 70 micron nylon screens and lysing red cells with ammonium chloride. All mice were 8 weeks of age at the time of the experiment. RNA was separately extracted, labeled, and hybridized from each animal.
Project description:Macrophages generate mitochondrial reactive oxygen and electrophilic species (mtROS, mtRES) as antimicrobials during Toll-like receptor (TLR)-dependent inflammatory responses. Whether mitochondrial stress caused by these molecules impacts macrophage function is unknown. Here, we demonstrate that both pharmacologically- and lipopolysaccharide (LPS)-driven mitochondrial stress in macrophages triggers a stress response called mitohormesis. LPS-driven mitohormetic stress adaptations occur as macrophages transition from an LPS-responsive to LPS-tolerant state where stimulus-induced proinflammatory gene transcription is impaired, suggesting tolerance is a product of mitohormesis. Indeed, like LPS, hydroxyestrogen-triggered mitohormesis suppresses mitochondrial oxidative metabolism and acetyl-CoA production needed for histone acetylation and proinflammatory gene transcription, and is sufficient to enforce an LPS-tolerant state. Thus, mtROS and mtRES are TLR-dependent signaling molecules that trigger mitohormesis as a negative feedback mechanism to restrain inflammation via tolerance. Moreover, bypassing TLR signaling and pharmacologically triggering mitohormesis represents a novel anti-inflammatory strategy that co-opts this stress response to impair epigenetic support of proinflammatory gene transcription by mitochondria.