Soi Cheng Law

Citrullinated peptide dendritic cell immunotherapy in HLA risk genotype-positive rheumatoid arthritis patients.

Citrullinated peptide-exposed DCs induced immune regulatory effects in HLA risk genotype–positive RA patients. Immunotherapy out of joint Autoantibodies to anti–citrullinated peptides (ACPA) are found in most patients with rheumatoid arthritis (RA), especially those with HLA-DRB1 risk alleles. Benham et al. report a first-in-human phase 1 trial of a single injection of autologous dendritic cells modified with an NF-κB inhibitor that have been exposed to four citrullinated peptide antigens. They find that HLA risk genotype–positive RA patients had reduced numbers of effector T cells and decreased production of proinflammatory cytokines compared with untreated RA patient controls. The therapy was safe and did not induce disease flares. These data support larger studies of antigen-specific immunotherapy for RA. In animals, immunomodulatory dendritic cells (DCs) exposed to autoantigen can suppress experimental arthritis in an antigen-specific manner. In rheumatoid arthritis (RA), disease-specific anti–citrullinated peptide autoantibodies (ACPA or anti-CCP) are found in the serum of about 70% of RA patients and are strongly associated with HLA-DRB1 risk alleles. This study aimed to explore the safety and biological and clinical effects of autologous DCs modified with a nuclear factor κB (NF-κB) inhibitor exposed to four citrullinated peptide antigens, designated “Rheumavax,” in a single-center, open-labeled, first-in-human phase 1 trial. Rheumavax was administered once intradermally at two progressive dose levels to 18 human leukocyte antigen (HLA) risk genotype–positive RA patients with citrullinated peptide–specific autoimmunity. Sixteen RA patients served as controls. Rheumavax was well tolerated: adverse events were grade 1 (of 4) severity. At 1 month after treatment, we observed a reduction in effector T cells and an increased ratio of regulatory to effector T cells; a reduction in serum interleukin-15 (IL-15), IL-29, CX3CL1, and CXCL11; and reduced T cell IL-6 responses to vimentin447–455–Cit450 relative to controls. Rheumavax did not induce disease flares in patients recruited with minimal disease activity, and DAS28 decreased within 1 month in Rheumavax-treated patients with active disease. This exploratory study demonstrates safety and biological activity of a single intradermal injection of autologous modified DCs exposed to citrullinated peptides, and provides rationale for further studies to assess clinical efficacy and antigen-specific effects of autoantigen immunomodulatory therapy in RA.

T-cell autoreactivity to citrullinated autoantigenic peptides in rheumatoid arthritis patients carrying HLA-DRB1 shared epitope alleles

IntroductionAnti-citrullinated peptide antibodies are found in rheumatoid arthritis (RA) patients with HLA-DRβ chains encoding the shared epitope (SE) sequence. Citrullination increases self-antigen immunogenicity, through increased binding affinity to SE-containing HLA-DR molecules. To characterise T-cell autoreactivity towards citrullinated self-epitopes, we profiled responses of SE+ healthy controls and RA patients to citrullinated and unmodified epitopes of four autoantigens.MethodsWe compared T-cell proliferative and cytokine responses to citrullinated and native type II collagen 1,237 to 1,249, vimentin 66 to 78, aggrecan 84 to 103 and fibrinogen 79 to 91 in six SE+ healthy controls and in 21 RA patients with varying disease duration. Cytokine-producing cells were stained after incubation with peptide in the presence of Brefeldin-A.ResultsAlthough proliferative responses were low, IL-6, IL-17 and TNF were secreted by CD4+ T cells of SE+ RA patients and healthy controls, as well as IFNγ and IL-10 secreted by RA patients, in response to citrullinated peptides. Of the epitopes tested, citrullinated aggrecan was most immunogenic. Patients with early RA were more likely to produce IL-6 in response to no epitope or to citrullinated aggrecan, while patients with longstanding RA were more likely to produce IL-6 to more than one epitope. Cytokine-producing CD4+ T cells included the CD45RO+ and CD45RO- and the CD28+ and CD28- subsets in RA patients.ConclusionProinflammatory cytokines were produced by CD4+ T cells in SE+ individuals in response to citrullinated self-epitopes, of which citrullinated aggrecan was most immunogenic. Our data suggest that the T-cell response to citrullinated self-epitopes matures and diversifies with development of RA.

Allergen-encoding bone marrow transfer inactivates allergic T cell responses, alleviating airway inflammation

Memory Th2 cell responses underlie the development and perpetuation of allergic diseases. Because these states result from immune dysregulation, established Th2 cell responses represent a significant challenge for conventional immunotherapies. New approaches that overcome the detrimental effects of immune dysregulation are required. We tested whether memory Th2 cell responses were silenced using a therapeutic approach where allergen expression in DCs is transferred to sensitized recipients using BM cells as a vector for therapeutic gene transfer. Development of allergen-specific Th2 responses and allergen-induced airway inflammation was blocked by expression of allergen in DCs. Adoptive transfer studies showed that Th2 responses were inactivated by a combination of deletion and induction of T cell unresponsiveness. Transfer of BM encoding allergen expression targeted to DCs terminated, in an allergen-specific manner, Th2 responses in sensitized recipients. Importantly, when preexisting airway inflammation was present, there was effective silencing of Th2 cell responses, airway inflammation was alleviated, and airway hyperreactivity was reversed. The effectiveness of DC-targeted allergen expression to terminate established Th2 responses in sensitized animals indicates that exploiting cell-intrinsic T cell tolerance pathways could lead to development of highly effective immunotherapies.

Molecular basis for increased susceptibility of Indigenous North Americans to seropositive rheumatoid arthritis

Objective The pathogenetic mechanisms by which HLA-DRB1 alleles are associated with anticitrullinated peptide antibody (ACPA)-positive rheumatoid arthritis (RA) are incompletely understood. RA high-risk HLA-DRB1 alleles are known to share a common motif, the ‘shared susceptibility epitope (SE)’. Here, the electropositive P4 pocket of HLA-DRB1 accommodates self-peptide residues containing citrulline but not arginine. HLA-DRB1 His/Phe13β stratifies with ACPA-positive RA, while His13βSer polymorphisms stratify with ACPA-negative RA and RA protection. Indigenous North American (INA) populations have high risk of early-onset ACPA-positive RA, whereby HLA-DRB1*04:04 and HLA-DRB1*14:02 are implicated as risk factors for RA in INA. However, HLA-DRB1*14:02 has a His13βSer polymorphism. Therefore, we aimed to verify this association and determine its molecular mechanism. Methods HLA genotype was compared in 344 INA patients with RA and 352 controls. Structures of HLA-DRB1*1402-class II loaded with vimentin-64Arg59-71, vimentin-64Cit59-71 and fibrinogen β−74Cit69-81 were solved using X-ray crystallography. Vimentin-64Cit59-71-specific and vimentin59-71-specific CD4+ T cells were characterised by flow cytometry using peptide-histocompatibility leukocyte antigen (pHLA) tetramers. After sorting of antigen-specific T cells, TCRα and β-chains were analysed using multiplex, nested PCR and sequencing. Results ACPA+ RA in INA was independently associated with HLA-DRB1*14:02. Consequent to the His13βSer polymorphism and altered P4 pocket of HLA-DRB1*14:02, both citrulline and arginine were accommodated in opposite orientations. Oligoclonal autoreactive CD4+ effector T cells reactive with both citrulline and arginine forms of vimentin59-71 were observed in patients with HLA-DRB1*14:02+ RA and at-risk ACPA- first-degree relatives. HLA-DRB1*14:02-vimentin59-71-specific and HLA-DRB1*14:02-vimentin-64Cit59-71-specific CD4+ memory T cells were phenotypically distinct populations. Conclusion HLA-DRB1*14:02 broadens the capacity for citrullinated and native self-peptide presentation and T cell expansion, increasing risk of ACPA+ RA.

Molecular basis for the increased susceptibility of Indigenous North American tribes to seropositive rheumatoid arthritis

CD4+Foxp3+ regulatory T cells (Tregs) are the main regulators of peripheral tolerance and prevent the development of fatal autoimmune disease in humans and mice. Furthermore, Tregs have also been implicated in suppressing anti-tumour immune responses and are often enriched at nsites of primary and metastatic tumours. While studies have shown the effect of Treg ablation on the control of primary tumours, few studies have examined their contribution to metastasis progression. nIn this thesis I hypothesised that the depletion of Tregs could promote control over metastasis. To address this, a highly metastatic murine mammary carcinoma cell line 4T1 was injected into transgenic mice expressing the diphtheria toxin receptor in Foxp3+ cells. Foxp3+ cells were depleted by administration of diphtheria toxin and the impact of this on growth of primary tumours and metastases was assessed and measured in vitro clonogenic assays. Results of these experiments indicated that Tregdepletion nled to control of primary tumour growth and in some mice to control of metastases. Control of metastases was linked to control of primary tumour growth. nIn order to measure metastasis in vivo, a PET/CT imaging technique was optimized. Primary tumours and large metastatic nodules were successfully imaged in mice using F18 FDG as a radiotracer. However, the studies described herein revealed that micrometastases in mouse lungs nwere too small to be reliably identified using PET data parameters. CT imaging did however enable detection of increases in tissue density within the lungs, which was suggestive of micrometastases. Data obtained in this way also indicated that Treg-depletion promotes control of metastasis in some mice. nCollectively, the findings described in this thesis indicate that Tregdepletion can contribute to control of metastatic disease and should therefore represent an important component of novel immunotherapies.s of ICI 2016 International Congress of Immunology 21-26 August 2016 Melbourne, Australia European Journal of Immunology Volume 46, Suppl. 1, August 2016 This abstract book can be searched using the PDF search function to look, for example, for the Abstract number or author name. To cite an Abstract, please use the following format: Abstract title. Authors. Conference: ICI 2016. Location Melbourne, Australia. Date Aug 2126, 2016. Eur. J. Immunol. 2016. 46, S1, page number(s). Meeting Abstract number [thetitle. Authors. Conference: ICI 2016. Location Melbourne, Australia. Date Aug 2126, 2016. Eur. J. Immunol. 2016. 46, S1, page number(s). Meeting Abstract number [the Abstract number can be found above the title]number can be found above the title]Changes in microbiome, mucosal immunity and intestinal integrity have been associated with the onset of Type 1 Diabetes (T1D) in children. Toll-like Receptors (TLR) have been associated all three factors. The role of TLR and their effects on microbiome in autoimmunity were studied by crossing TLR1,2,4,6,9 and MyD88 targeted deficiency mutations to the type 1 diabetes (T1D)-prone NOD mouse strain. While NOD.Tlr9-/- and NOD.Tlr6-/- mice were unaffected, T1D in NOD.Tlr4-/- and NOD.Tlr1-/- mice was exacerbated and that in NOD.Myd88-/- and NOD.Tlr2-/- mice ameliorated. Physical parameters of the intestines were compared; ileal weight was reduced in NOD.Tlr1-/-mice. Similarly, by histology, these mice had reduced villus length and width. The intestinal microbiomes of NOD wild-type (WT), NOD.Tlr1-/-, NOD.Tlr2-/- and NOD.Tlr4-/- mice were compared by high throughput sequencing of 16S ribosomal DNA (rDNA), in two cohorts, 18 months apart. Analysis of caecal 16S sequences clearly resolved the mouse lines and there were significant differences in beta diversity between the strains, with individual bacterial species contributing greatly to the differences in the microbiota of individual TLR-deficient strains. To test the relationship between microbiome and T1D, all strains were re-derived onto the parental NOD/Lt line and the incidence of T1D re-assessed within two generations. All rederived lines expressed an incidence of disease similar to that of the parental line. TLR deficiencies are associated with changes in microbiome; changes of microbiome are associated with T1D; the effects of TLR deficiencies on T1D appear to be mediated by their effects on gut flora.Intestinal TCRb+CD4-CD8b-CD8a+ (CD8aa) IELs alleviate T cell induced colitis and have been suggested to play a role in virus infection and cancer. Their thymic development has been elucidated to some extent, as IEL precursors (IELp) are known to be CD4-CD8-CD5+TCRb+, but is not yet fully understood. Within the thymus, mature IELp were identified based on their expression of CD122 and MHC class I. Two major phenotypic subsets exist within this mature thymic IELp population: a PD1+Tbet- population that preferentially expresses a4b7, and a PD1-Tbet+ population with preferential CD103 expression. These two populations were also distinct in their Valpha repertoire. The PD1+a4b7+ population contains clones that are strongly self-reactive as judged by Nur77GFP and their dramatic increase in Bim deficient mice, while the PD1-Tbet+ population did not show these characteristics. Both gave rise to CD8aa IELs upon adoptive transfer into RAG-/- recipients. However intrathymic labeling revealed that PD1+a4b7+ IELp were the major thymic emigrating population, and emigration was S1P1-dependent. In contrast, PD1-Tbet+ IELp expressed CXCR3, were retained, and accumulated in the thymus with age. Preliminary immunofluorescence data furthermore indicate differential thymic cortico-medullary localization of the IELp subtypes. These experiments more precisely define the behavior of IEL precursors.Multiple Sclerosis (MS), the most common disabling neurological disease affecting young adults in developed countries, is a complex genetic disease associated with both environmental and genetic risk factors. In most cases, the risk factors individual associations with MS are so weak that any meaningful understanding of the disease will require the identification of molecular pathways that contribute to MS liability. We therefore hypothesisedthat the complex genetic phenotype is driven by a co-ordinated expression of transcriptional regulatory networks. To test this, we generated a weighted gene co-expression network based on 712 pooled Affymetrix Human Gene 1.0 ST array analyses of magnetic bead sorted B cells, CD4 and CD8 T cells, NK cells and monocytes, from 67 untreated relapsing/remitting MS patients and 102 Healthy Controls (HC). Sixteen relatively independent gene modules were identified. For each leukocyte population, the strength of differential expression between patients and HC was assessed, by ranking genes by Mann Whitney U test and ANOVA, and each transcript was tested across the network to identify modules of interest. A group of transcripts we named the “Black” module was most significantly associated with MS in monocytes & was strongly down-regulated in patients. Twelve highly differentially expressed genes with high centrality were identified and the top annotation clusters comprised the immune processes: Natural killer cell mediated cytotoxicity & Antigen processing and presentation. We propose that manipulating the module as a whole may provide a new perspective on the aetiology of complex genetic diseases and offer novel therapies for MS.

Oligoclonally expanded CD4+T cells recognising citrulinated vimentin in peripheral blood of rheumatoid arthritis patients

CD4+Foxp3+ regulatory T cells (Tregs) are the main regulators of peripheral tolerance and prevent the development of fatal autoimmune disease in humans and mice. Furthermore, Tregs have also been implicated in suppressing anti-tumour immune responses and are often enriched at nsites of primary and metastatic tumours. While studies have shown the effect of Treg ablation on the control of primary tumours, few studies have examined their contribution to metastasis progression. nIn this thesis I hypothesised that the depletion of Tregs could promote control over metastasis. To address this, a highly metastatic murine mammary carcinoma cell line 4T1 was injected into transgenic mice expressing the diphtheria toxin receptor in Foxp3+ cells. Foxp3+ cells were depleted by administration of diphtheria toxin and the impact of this on growth of primary tumours and metastases was assessed and measured in vitro clonogenic assays. Results of these experiments indicated that Tregdepletion nled to control of primary tumour growth and in some mice to control of metastases. Control of metastases was linked to control of primary tumour growth. nIn order to measure metastasis in vivo, a PET/CT imaging technique was optimized. Primary tumours and large metastatic nodules were successfully imaged in mice using F18 FDG as a radiotracer. However, the studies described herein revealed that micrometastases in mouse lungs nwere too small to be reliably identified using PET data parameters. CT imaging did however enable detection of increases in tissue density within the lungs, which was suggestive of micrometastases. Data obtained in this way also indicated that Treg-depletion promotes control of metastasis in some mice. nCollectively, the findings described in this thesis indicate that Tregdepletion can contribute to control of metastatic disease and should therefore represent an important component of novel immunotherapies.s of ICI 2016 International Congress of Immunology 21-26 August 2016 Melbourne, Australia European Journal of Immunology Volume 46, Suppl. 1, August 2016 This abstract book can be searched using the PDF search function to look, for example, for the Abstract number or author name. To cite an Abstract, please use the following format: Abstract title. Authors. Conference: ICI 2016. Location Melbourne, Australia. Date Aug 2126, 2016. Eur. J. Immunol. 2016. 46, S1, page number(s). Meeting Abstract number [thetitle. Authors. Conference: ICI 2016. Location Melbourne, Australia. Date Aug 2126, 2016. Eur. J. Immunol. 2016. 46, S1, page number(s). Meeting Abstract number [the Abstract number can be found above the title]number can be found above the title]Changes in microbiome, mucosal immunity and intestinal integrity have been associated with the onset of Type 1 Diabetes (T1D) in children. Toll-like Receptors (TLR) have been associated all three factors. The role of TLR and their effects on microbiome in autoimmunity were studied by crossing TLR1,2,4,6,9 and MyD88 targeted deficiency mutations to the type 1 diabetes (T1D)-prone NOD mouse strain. While NOD.Tlr9-/- and NOD.Tlr6-/- mice were unaffected, T1D in NOD.Tlr4-/- and NOD.Tlr1-/- mice was exacerbated and that in NOD.Myd88-/- and NOD.Tlr2-/- mice ameliorated. Physical parameters of the intestines were compared; ileal weight was reduced in NOD.Tlr1-/-mice. Similarly, by histology, these mice had reduced villus length and width. The intestinal microbiomes of NOD wild-type (WT), NOD.Tlr1-/-, NOD.Tlr2-/- and NOD.Tlr4-/- mice were compared by high throughput sequencing of 16S ribosomal DNA (rDNA), in two cohorts, 18 months apart. Analysis of caecal 16S sequences clearly resolved the mouse lines and there were significant differences in beta diversity between the strains, with individual bacterial species contributing greatly to the differences in the microbiota of individual TLR-deficient strains. To test the relationship between microbiome and T1D, all strains were re-derived onto the parental NOD/Lt line and the incidence of T1D re-assessed within two generations. All rederived lines expressed an incidence of disease similar to that of the parental line. TLR deficiencies are associated with changes in microbiome; changes of microbiome are associated with T1D; the effects of TLR deficiencies on T1D appear to be mediated by their effects on gut flora.Intestinal TCRb+CD4-CD8b-CD8a+ (CD8aa) IELs alleviate T cell induced colitis and have been suggested to play a role in virus infection and cancer. Their thymic development has been elucidated to some extent, as IEL precursors (IELp) are known to be CD4-CD8-CD5+TCRb+, but is not yet fully understood. Within the thymus, mature IELp were identified based on their expression of CD122 and MHC class I. Two major phenotypic subsets exist within this mature thymic IELp population: a PD1+Tbet- population that preferentially expresses a4b7, and a PD1-Tbet+ population with preferential CD103 expression. These two populations were also distinct in their Valpha repertoire. The PD1+a4b7+ population contains clones that are strongly self-reactive as judged by Nur77GFP and their dramatic increase in Bim deficient mice, while the PD1-Tbet+ population did not show these characteristics. Both gave rise to CD8aa IELs upon adoptive transfer into RAG-/- recipients. However intrathymic labeling revealed that PD1+a4b7+ IELp were the major thymic emigrating population, and emigration was S1P1-dependent. In contrast, PD1-Tbet+ IELp expressed CXCR3, were retained, and accumulated in the thymus with age. Preliminary immunofluorescence data furthermore indicate differential thymic cortico-medullary localization of the IELp subtypes. These experiments more precisely define the behavior of IEL precursors.Multiple Sclerosis (MS), the most common disabling neurological disease affecting young adults in developed countries, is a complex genetic disease associated with both environmental and genetic risk factors. In most cases, the risk factors individual associations with MS are so weak that any meaningful understanding of the disease will require the identification of molecular pathways that contribute to MS liability. We therefore hypothesisedthat the complex genetic phenotype is driven by a co-ordinated expression of transcriptional regulatory networks. To test this, we generated a weighted gene co-expression network based on 712 pooled Affymetrix Human Gene 1.0 ST array analyses of magnetic bead sorted B cells, CD4 and CD8 T cells, NK cells and monocytes, from 67 untreated relapsing/remitting MS patients and 102 Healthy Controls (HC). Sixteen relatively independent gene modules were identified. For each leukocyte population, the strength of differential expression between patients and HC was assessed, by ranking genes by Mann Whitney U test and ANOVA, and each transcript was tested across the network to identify modules of interest. A group of transcripts we named the “Black” module was most significantly associated with MS in monocytes & was strongly down-regulated in patients. Twelve highly differentially expressed genes with high centrality were identified and the top annotation clusters comprised the immune processes: Natural killer cell mediated cytotoxicity & Antigen processing and presentation. We propose that manipulating the module as a whole may provide a new perspective on the aetiology of complex genetic diseases and offer novel therapies for MS.

Profiling the TCR repertoire in the Rheumatoid Arthritis (RA) Autoantigen-Specific Cd4+T-Cells At the Single-Cell Level

Robinson P1, Leo P2, Pointon J3, Harris J4, Cremin K4, Bradbury L4, Stebbings S5, Harrison A6, Duncan E4, Wordsworth P3, Brown M4 1Centre for Neurogenetics and Statistical Genomics, Queensland Brain Institute, University of Queensland 2University of Queensland Diamantina Insititute, University of Queensland, Brisbane, Australia 3National Institute for Health Research (NIHR) Oxford Musculoskeletal Biomedical Research Unit, Nuffield Orthopaedic Centre, Headington, Oxford, UK 4University of Queensland Diamantina Institute, Translational Research Institute, Princess Alexandra Hospital, Brisbane, Queensland, Australia 5University of Otago, Dunedin, New Zealand 6University of Otago, Wellington, New Zealand

Multiple Mechanisms of Tolerance Characterize the Immune Response to Autologous Modified Dendritic Cells Exposed to Citrullinated Peptides in Patients with Rheumatoid Arthritis.

This free journal suppl. entitled: Special Issue: 2014 ACR/ARHP Annual Meeting Abstract Supplement

A molecular basis for citrullination dependent rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic and debilitating autoimmune disease, characterized by inflammation of synovial tissue, joint pannus and bone erosion. The human leukocyte antigen (HLA) locus plays a vital role in immunity, encoding highly polymorphic molecules that present peptides to T cell lymphocytes. RA has a strong association with a region of the HLA-DRB1 locus known as the ‘shared epitope’ (SE) and the presence of autoantibodies specific for citrullinated proteins. The SE maps to a highly polymorphic Nterminal region of the HLA-DRβ chain around amino acids 70-74. This region encodes a positively charged residue at position 71 that is thought to dictate the amino acid that is accommodated in the P4 pocket of the antigen-binding groove. Citrullination, the conversion of positively charged arginine to polar citrulline, is a physiological process catalyzed by peptidyl arginine deiminase. Previous studies have shown that citrullination of self-antigens can significantly increase the affinity of epitopes for SE alleles. Here we provide a molecular basis for how citrullinated vimentin and aggrecan epitopes can be presented by the SE alleles, HLA-DRB1*0401 and HLADRB1*0404. Citrulline was accommodated in the electropositive P4 pocket of HLA-DRB1*0401/04, whilst arginine was not. In addition, the RA resistant HLA-DRB1*0402 allomorph was capable of binding both arginine and citrulline in its electronegative P4 pocket. Peptide elution studies revealed that arginine was presented by HLA-DRB1*0402 but not by HLA-DRB1*0401/04. Moreover, citrullinated vimentin showed a greater sensitivity to proteolysis by cathepsin L, when compared to unmodified vimentin, indicating that citrullination can impact the repertoire of self-antigens presented. Using HLA Class II tetramers, we identified citrullinated vimentin and aggrecan specific CD4+ T cells from both HLA-DRB1*0401+ RA patients and healthy controls. In RA patients, the number of autoreactive T cells correlated with disease activity and were deficient in regulatory T cells compared to healthy controls. Together these findings provide significant insight into the role citrullination plays in the pathogenesis of RA[1].

Outcome of a phase I trial of rheumavax in patients with rheumatoid arthritis

Aim: The aim of this study was to identify miRNA that target infl ammatory pathways during arthritis. Specifi cally we are interested in production of the key infl ammatory cytokine IL-1β, which is generated by a complex of proteins known as the infl ammasome. Methods: Synovial fl uid monocytes were isolated from patients with rheumatoid or psoriatic arthritis and analysis of miRNA expression was performed. NLRP3, a key component of the infl ammasome, was identifi ed as a potential target of miR-223 and this was validated by several approaches. Results: We have identifi ed the fi rst miRNA that targets an infl ammasome complex. This is miR-223, which has a single, highly conserved binding site in the NLRP3 3′UTR. miR-223 expression decreases as monocytes differentiate into macrophages, and NLRP3 protein increases during this time. However overexpression of miR-223 prevents accumulation of endogenous NLRP3 protein levels, as for monocytic Thp-1 cells differentiated into macrophages with PMA. NLRP3 function was also impacted by miR-223, with decreased IL-1β production after stimulation with nigericin or uric acid crystals, but not poly dAdT (AIM2) or salmonella (NLRC4). Consistent with this, mice lacking miR-223 are reported to have spontaneous infl ammatory disease associated with increased NLRP3 protein expression. miR-223 is known to be decreased in type 2 diabetes, Crohn’s disease, and now we show a specifi c decrease in synovial monocytes from rheumatoid and psoriatic arthritis patients. All of these diseases are associated with increased IL-1β and the effect of miR-223 on NLRP3 could be a mechanism to account for this. Conclusions: In summary we have identifi ed an endogenous miRNA that limits NLRP3 infl ammatory capacity during myeloid differentiation, and is decreased in synovial fl uid monocytes from patients with rheumatoid or psoriatic arthritis.