Project description:Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IL-1R-associated kinase (IRAK)-4, myeloid differentiation factor 88 (MyD88) and UNC-93B. Indeed, all TLRs except TLR3 require IRAK-4 and MyD88 to signal and UNC-93B-deficient cells are unresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients did not display autoreactive antibodies in their serum nor developed autoimmune diseases, suggesting that IRAK-4, MyD88 and UNC-93B pathway blockade may thwart autoimmunity in humans.
Project description:Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IL-1R-associated kinase (IRAK)-4, myeloid differentiation factor 88 (MyD88) and UNC-93B. Indeed, all TLRs except TLR3 require IRAK-4 and MyD88 to signal and UNC-93B-deficient cells are unresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients did not display autoreactive antibodies in their serum nor developed autoimmune diseases, suggesting that IRAK-4, MyD88 and UNC-93B pathway blockade may thwart autoimmunity in humans. Experiment Overall Design: RNA was extracted from 105-3.105 batch sorted new emigrant and mature naïve B cells isolated from donors using the Absolutely RNA microprep kit (Stratagene). 100-200 ng of RNA was obtained per sample, and the quality of the purified RNA was assessed by the Bioanalyzer from Agilent. Using the Ovation biotin system kit from Nugen, 30-50ng of RNA was amplified and labeled to produce cDNA. Labeled cDNA was hybridized on chips containing the whole human genome (Human Genome U133 2.0 from Affymetrix). Raw data from new emigrant (1 healthy donor) and mature naive (4 healthy donors) B cells were analyzed in order to determine the expression of some molecules involved in the TLR pathway in these B cell population in humans.
Project description:IRAK-4 is an essential component of the signal transduction complex downstream of the IL-1- and Toll-like receptors. Though regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function is still controversial. In order to investigate the role of IRAK-4 kinase function in vivo, ‘knock-in’ mice were generated by replacing the wild type IRAK-4 gene with a mutant gene encoding kinase deficient IRAK-4 protein (IRAK-4 KD). Analysis of bone marrow macrophages obtained from WT and IRAK-4 KD mice with a number of experimental techniques demonstrated that the IRAK-4 KD cells greatly lack responsiveness to stimulation with the Toll-like receptor 4 (TLR4) agonist LPS. One of the techniques used, microarray analysis, identified IRAK-4 kinase-dependent LPS response genes and revealed that the induction of LPS-responsive mRNAs was largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in TLR4-mediated induction of inflammatory responses. Keywords: genetic modification, strain comparison, cell stimulation, time course, anti-bacterial response, innate immune response, inflammatory response
Project description:IRAK-4 is an essential component of the signal transduction complex downstream of the IL-1- and Toll-like receptors. Though regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function is still controversial. In order to investigate the role of IRAK-4 kinase function in vivo, ‘knock-in’ mice were generated by replacing the wild type IRAK-4 gene with a mutant gene encoding kinase deficient IRAK-4 protein (IRAK-4 KD). Analysis of embryonic fibroblasts and macrophages obtained from IRAK-4 KD mice with a number of experimental techniques demonstrated that they greatly lack responsiveness to stimulation with IL-1b or a Toll-like receptor 7 (TLR7) agonist. One of the techniques used, microarray analysis, identified IRAK-4 kinase-dependent IL-1b response genes in mouse embryonic fibroblasts and revealed that the induction of IL-1b-responsive mRNAs was largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in IL-1R/TLR7-mediated induction of inflammatory responses. Keywords: genetic modification, strain comparison, cell stimulation, time course, inflammatory response
Project description:IRAK-4 is an essential component of the signal transduction complex downstream of the IL-1- and Toll-like receptors. Though regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function is still controversial. In order to investigate the role of IRAK-4 kinase function in vivo, âknock-inâ mice were generated by replacing the wild type IRAK-4 gene with a mutant gene encoding kinase deficient IRAK-4 protein (IRAK-4 KD). Analysis of bone marrow macrophages obtained from WT and IRAK-4 KD mice with a number of experimental techniques demonstrated that the IRAK-4 KD cells greatly lack responsiveness to stimulation with the Toll-like receptor 4 (TLR4) agonist LPS. One of the techniques used, microarray analysis, identified IRAK-4 kinase-dependent LPS response genes and revealed that the induction of LPS-responsive mRNAs was largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in TLR4-mediated induction of inflammatory responses. Experiment Overall Design: The response of mouse bone marrow macrophages from WT and IRAK4 kinase dead animals to stimulation with LPS at two time points was determined. There were 12 samples in total, 6 from WT and 6 from IRAK4 kinase dead cells; for each strain there were 3 conditions: growth for 4 hours without stimulation (the strain-specific control), growth for 1 hour with stimulation, and growth for 4 hours with stimulation; for each condition there were two biological replicates.
Project description:Children with autosomal recessive deficiency suffer from life-threatening, often recurrent viral or bacterial infections. We have profiled transcriptional responses of fibroblast cell lines derived from patients deficient for key regulators of immune responses such as MYD88, IRAK4, UNC93B, STAT1 or NEMO. This systems immunology approach revealed distinct patterns or responsiveness to stimuli activating the Toll-like/IL1 Receptor pathway in either an MYD88-dependent (IL1B) or independent (poly(I:C)) fashion, or activating the TNF pathway. The prototypic signatures in cell lines derived from patients were as follows: NEMO-deficient cells were unresponsive to all three stimuli, UNC-93B-deficient cells did not respond to poly(I:C), and STAT1-deficient cells responded only weakly to poly(I:C) after eight hours (not shown). MyD88- and IRAK-4-deficient cells had indistinguishable phenotypes, both being unresponsive to IL-1B at both time points. The signatures obtained in response to TNF and poly(I:C) (via TLR3) in these cells were similar to that of control fibroblasts.
Project description:IRAK-4 is an essential component of the signal transduction complex downstream of the IL-1- and Toll-like receptors. Though regarded as the first kinase in the signaling cascade, the role of IRAK-4 kinase activity versus its scaffold function is still controversial. In order to investigate the role of IRAK-4 kinase function in vivo, knock-in mice were generated by replacing the wild type IRAK-4 gene with a mutant gene encoding kinase deficient IRAK-4 protein (IRAK-4 KD). Analysis of embryonic fibroblasts and macrophages obtained from IRAK-4 KD mice with a number of experimental techniques demonstrated that they greatly lack responsiveness to stimulation with IL-1b or a Toll-like receptor 7 (TLR7) agonist. One of the techniques used, microarray analysis, identified IRAK-4 kinase-dependent IL-1b response genes in mouse embryonic fibroblasts and revealed that the induction of IL-1b-responsive mRNAs was largely ablated in IRAK-4 KD cells. In summary, our results suggest that IRAK-4 kinase activity plays a critical role in IL-1R/TLR7-mediated induction of inflammatory responses. Experiment Overall Design: The response of mouse embryonic fibroblasts from WT and IRAK4 kinase dead animals to stimulation with IL-1b at two time points was determined. There were 12 samples in total, 6 from WT and 6 from IRAK4 kinase dead cells; for each strain there were 3 conditions: growth for 4 hours without stimulation (the strain-specific control), growth for 1 hour with stimulation, and growth for 4 hours with stimulation; for each condition there were two biological replicates.
Project description:We describe here a male infant with a 100 kb de novo Xq28 deletion encompassing parts of the TMEM187 and MECP2 protein-coding genes and the IRAK1 protein-coding gene, as well as the MIR3202-1, MIR3202-2, and MIR718 RNA-coding genes. We analyzed the impact of human IRAK-1 deficiency on a genome-wide gene expression in human fibroblasts in response to TLR2/6, TLR4 agonists as well as to IL-1β and TNF-α, using primary fibroblasts from healthy controls and IRAK-4-, MyD88- and MECP2-deficient patients for comparison.
Project description:Nitric oxide (NO) produced by macrophages (MØs) is toxic to both host tissues and invading pathogens and its regulation is therefore essential to suppress host cytotoxicity. MØ arginase 1 (Arg1) inhibits NO production by competing with NO synthases for arginine, the common substrate of NO synthases and arginases. Two signal transduction pathways control Arg1 expression in MØs. First, a MyD88-dependent pathway induces Arg1 in intracellular infections, while a second Stat6-dependent pathway is required for Arg1 expression in alternativelyactivated MØs. We found that mycobacteria-infected MØs produce soluble factors that induce Arg1 in an autocrine-paracrine manner via Stat3. We identify these factors as IL-6, IL-10 and GCSF. We further establish that Arg1 expression is controlled by the MyD88-dependent production of IL-6, IL-10 and G-CSF rather than cell intrinsic MyD88 signaling to Arg1. Our data reveal the MyD88-dependent pathway of Arg1induction following BCG infection requires Stat3 activation and may result in the development of an immunosuppressive niche in granulomas due to the induced Arg1 production in surrounding uninfected MØs We used microarrays to perform genome wide expression analysis in mycobacteria-infected macrophages from C57Bl/6 WT and MyD88-knockout mice.