The pathogenesis of autoimmune diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) is driven by genetic predisposition and environmental triggers that lead to ...dysregulated immune responses. These include the generation of pathogenic autoantibodies and aberrant production of inflammatory cytokines. Current therapies for RA and other autoimmune diseases reduce inflammation by targeting inflammatory mediators, most of which are innate response cytokines, resulting in generalized immunosuppression. Overall, this strategy has been very successful, but not all patients respond, responses can diminish over time and numerous side effects can occur. Therapies that target the germinal center (GC) reaction and/or antibody-secreting plasma cells (PC) potentially provide a novel approach. TANK-binding kinase 1 (TBK1) is an IKK-related serine/threonine kinase best characterized for its involvement in innate antiviral responses through the induction of type I interferons. TBK1 is also gaining attention for its roles in humoral immune responses. In this review, we discuss the role of TBK1 in immunological pathways involved in the development and maintenance of antibody responses, with particular emphasis on its potential relevance in the pathogenesis of humoral autoimmunity. First, we review the role of TBK1 in the induction of type I IFNs. Second, we highlight how TBK1 mediates inducible T cell co-stimulator signaling to the GC T follicular B helper population. Third, we discuss emerging evidence on the contribution of TBK1 to autophagic pathways and the potential implications for immune cell function. Finally, we discuss the therapeutic potential of TBK1 inhibition in autoimmunity.
Stimulator of Interferon Genes (STING) is a critical component of host innate immune defense but can contribute to chronic autoimmune or autoinflammatory disease. Once activated, the cyclic guanosine ...monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS)-STING pathway induces both type I interferon (IFN) expression and nuclear factor-κB (NF-κB)-mediated cytokine production. Currently, these two signaling arms are thought to be mediated by a single upstream kinase, TANK-binding kinase 1 (TBK1). Here, using genetic and pharmacological approaches, we show that TBK1 alone is dispensable for STING-induced NF-κB responses in human and mouse immune cells, as well as in vivo. We further demonstrate that TBK1 acts redundantly with IκB kinase ε (IKKε) to drive NF-κB upon STING activation. Interestingly, we show that activation of IFN regulatory factor 3 (IRF3) is highly dependent on TBK1 kinase activity, whereas NF-κB is significantly less sensitive to TBK1/IKKε kinase inhibition. Our work redefines signaling events downstream of cGAS-STING. Our findings further suggest that cGAS-STING will need to be targeted directly to effectively ameliorate the inflammation underpinning disorders associated with STING hyperactivity.
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•TBK1 is dispensable for NF-κB activation downstream of STING in vitro and in vivo•TBK1 and IKKε act redundantly to elicit STING-induced NF-κB activation•STING-NF-κB is less sensitive to TBK1/IKKε kinase inhibition than type I IFN•TAK1 and IKK complexes are required for STING-mediated NF-κB responses
Activation of NF-κB via STING is considered to be exclusively dependent on TBK1. Balka et al. now show that, although TBK1 and its kinase activity are critical for IRF3 activation and type I IFNs, it is dispensable for NF-κB. Instead, TBK1 and IKKε act redundantly to mediate STING-induced NF-κB responses.
Abstract
Detection of microbial components such as lipopolysaccharide (LPS) by Toll-like receptor 4 (TLR4) on macrophages induces a robust pro-inflammatory response that is dependent on metabolic ...reprogramming. These innate metabolic changes have been compared to aerobic glycolysis in tumour cells. However, the mechanisms by which TLR4 activation leads to mitochondrial and glycolytic reprogramming are unknown. Here we show that TLR4 activation induces a signalling cascade recruiting TRAF6 and TBK-1, while TBK-1 phosphorylates STAT3 on S727. Using a genetically engineered mouse model incapable of undergoing STAT3 Ser727 phosphorylation, we show ex vivo and in vivo that STAT3 Ser727 phosphorylation is critical for LPS-induced glycolytic reprogramming, production of the central immune response metabolite succinate and inflammatory cytokine production in a model of LPS-induced inflammation. Our study identifies non-canonical STAT3 activation as the crucial signalling intermediary for TLR4-induced glycolysis, macrophage metabolic reprogramming and inflammation.
Muscle cell death in polymyositis is induced by CD8
cytotoxic T lymphocytes. We hypothesized that the injured muscle fibers release pro-inflammatory molecules, which would further accelerate CD8
...cytotoxic T lymphocytes-induced muscle injury, and inhibition of the cell death of muscle fibers could be a novel therapeutic strategy to suppress both muscle injury and inflammation in polymyositis. Here, we show that the pattern of cell death of muscle fibers in polymyositis is FAS ligand-dependent necroptosis, while that of satellite cells and myoblasts is perforin 1/granzyme B-dependent apoptosis, using human muscle biopsy specimens of polymyositis patients and models of polymyositis in vitro and in vivo. Inhibition of necroptosis suppresses not only CD8
cytotoxic T lymphocytes-induced cell death of myotubes but also the release of inflammatory molecules including HMGB1. Treatment with a necroptosis inhibitor or anti-HMGB1 antibodies ameliorates myositis-induced muscle weakness as well as muscle cell death and inflammation in the muscles. Thus, targeting necroptosis in muscle cells is a promising strategy for treating polymyositis providing an alternative to current therapies directed at leukocytes.
Despite increasing recognition of the importance of GM-CSF in autoimmune disease, it remains unclear how GM-CSF is regulated at sites of tissue inflammation. Using GM-CSF fate reporter mice, we show ...that synovial NK cells produce GM-CSF in autoantibody-mediated inflammatory arthritis. Synovial NK cells promote a neutrophilic inflammatory cell infiltrate, and persistent arthritis, via GM-CSF production, as deletion of NK cells, or specific ablation of GM-CSF production in NK cells, abrogated disease. Synovial NK cell production of GM-CSF is IL-18-dependent. Furthermore, we show that cytokine-inducible SH2-containing protein (CIS) is crucial in limiting GM-CSF signaling not only during inflammatory arthritis but also in experimental allergic encephalomyelitis (EAE), a murine model of multiple sclerosis. Thus, a cellular cascade of synovial macrophages, NK cells, and neutrophils mediates persistent joint inflammation via production of IL-18 and GM-CSF. Endogenous CIS provides a key brake on signaling through the GM-CSF receptor. These findings shed new light on GM-CSF biology in sterile tissue inflammation and identify several potential therapeutic targets.
Introduction: Studies have found that AML pts treated at high pt volume, academic or NCI-designated cancer centers have improved outcomes compared to pts treated at smaller community hospitals. But ...little is known about the treatment patterns and outcomes as related to a combined academic and community based health system. Therefore, in a real-world cohort that included both academic and community hospitals that collaborate with one another, we evaluated pt characteristics, frequency of genomic testing, frequency of chemotherapy treatment (Tx) or any targeted therapy as a function of age, and outcomes in ND AML pts.
Methods: This was a retrospective observational study of patients treated within a comprehensive health system in the Midwest US that includes both metropolitan and rural populations. Pts ≥18 years (yrs) with ND AML between 1 Jan 2011 and 31 Dec 2018 were identified using ICD-9 / ICD-10 codes for AML within the Health System or from one of two local cancer registries, with a follow-up period that ended with the pt's death, 2 years after initial diagnosis or 31 Dec 2018, whichever came first. Date of diagnosis served as the index date. Kaplan-Meier estimates were used to visualize overall survival.
Results: A total of 629 pts with ND AML were identified in the 3 data sources and included in the cohort for analysis (Figure 1). At the index date, majority (55%) of the pts were older (61 yrs or more), male (55%) and White (89%) (Table 1). Majority of the identified pts (76%) died before the end of the study; higher proportion of older pts died vs younger pts (≥75 yrs: 89%; 61 - 74 yrs: 85% vs. ≤60 yrs: 62%). Most common comorbidities were renal disease (30%), cardiovascular diseases (24%), and diabetes (18%).
Of the 500 pts with available cytogenetics data, majority had ELN-defined intermediate risk (49%), then adverse (25%) and favorable (6%); no pt ≥75 yrs had favorable risk profile. Only 82 pts (13%) had evidence of a sequencing genomic report; 78% of the pts had at least 1 mutation and 56% had 2 - 5 mutations (Table 2). By age, pts ≥75 yrs had the highest proportion of multiple (≥3) mutations (46%); most common overall were ASXL1, NPM1, and FLT3. By age, mutations with the highest frequencies were: ≥75 yrs - ASXL1, RUNX1 and TET2; 61 - 74 yrs - ASXL1, NPM1 and TP53; and ≤60 yrs - NPM1, FLT3 and DNMT3A. As expected, pts with TP53 mutations had a lower overall probability of survival vs pts with wild type TP53 or NPM1 mutations (Figure 2).
Overall, 69% of pts had records for either standard induction chemotherapy (IC) or other chemotherapy (OC; includes targeted therapy) during the study period; 31% did not have records for chemotherapy (Table 3). Of the 54% of pts with IC, majority (63%) were ≤60 yrs. A higher proportion of pts ≥75 yrs (23%) received OC, which includes hypomethylating agents (HMAs), but 66% of pts ≥75 yrs did not have records for receiving any chemotherapy. Overall probability of survival for pts who received Tx (IC + OC) was higher than for pts who did not receive any Tx (Figure 3). Pts ≥75 years received proportionally more HMAs vs other age groups (Table 3). Anthracyclines and cytarabine records were similar within each age group, suggesting they were given together. In pts with genomic data, 84% received chemotherapy (IC 68%; OC 16%) while 16% did not (Table 4); proportion of pts ≤60 yrs who received IC (91%) was much higher in those with a genomic report than for the entire cohort (75%), and fewer older pts ≥75 yrs with a genomic report did not receive any chemotherapy (31%) vs 66% for the entire cohort.
Conclusions: Results of this retrospective study showed 55% of the ND AML pts were >60 yrs, younger pts (≤60 yrs) are more likely to receive IC and 66% of those ≥75 yrs did not receive any chemotherapy or alternative treatment. Additionally, only 13% of pts had evidence of a genomic report although it has been used for prognostication for at least the last decade. With newer Tx options including targeted therapies, access to genomic analysis and Tx needs to increase across all environments (rural and metropolitan) given the impact that such treatments can have on patient outcome.
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Byrd: Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria; Newave: Membership on an entity's Board of Directors or advisory committees. Mims: Leukemia and Lymphoma Society's Beat AML clinical study: Consultancy, Research Funding; Aptevo: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Glycomemetics: Research Funding; Kartos Pharmaceuticals: Research Funding; Xencor: Research Funding; Genentech: Consultancy; Abbvie: Consultancy; BMS: Consultancy; Kura Oncology: Consultancy; Syndax Pharmaceuticals: Consultancy; BMS: Consultancy; Jazz Pharmaceuticals: Consultancy; Aptevo: Research Funding. Borate: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rampal: Membership on an entity's Board of Directors or advisory committees; Galecto, Inc.: Consultancy; Promedior: Consultancy.
Data from preclinical and clinical studies have demonstrated that granulocyte macrophage colony-stimulating factor (GM-CSF) can function as a key proinflammatory cytokine. However, therapies that ...directly target GM-CSF function could lead to undesirable side effects, creating a need to delineate downstream pathways and mediators. In this work, we provide evidence that GM-CSF drives CCL17 production by acting through an IFN regulatory factor 4-dependent (IRF4-dependent) pathway in human monocytes, murine macrophages, and mice in vivo. In murine models of arthritis and pain, IRF4 regulated the formation of CCL17, which mediated the proinflammatory and algesic actions of GM-CSF. Mechanistically, GM-CSF upregulated IRF4 expression by enhancing JMJD3 demethylase activity. We also determined that CCL17 has chemokine-independent functions in inflammatory arthritis and pain. These findings indicate that GM-CSF can mediate inflammation and pain by regulating IRF4-induced CCL17 production, providing insights into a pathway with potential therapeutic avenues for the treatment of inflammatory diseases and their associated pain.
M-CSF (or CSF-1) and GM-CSF can regulate the development and function of the mononuclear phagocyte system (MPS). To address some of the outstanding and sometimes conflicting issues surrounding this ...biology, we undertook a comparative analysis of the effects of neutralizing mAbs to these CSFs on murine MPS populations in the steady-state and during acute inflammatory reactions. CSF-1 neutralization, but not of GM-CSF, in normal mice rapidly reduced the numbers of more mature Ly6C(-) monocytes in blood and bone marrow, without any effect on proliferating precursors, and also the numbers of the resident peritoneal macrophages, observations consistent with CSF-1 signaling being essential only at a relatively late state in steady-state MPS development; in contrast, GM-CSF neutralization had no effect on the numbers of these particular populations. In Ag-induced peritonitis (AIP), thioglycolate-induced peritonitis, and LPS-induced lung inflammation, CSF-1 neutralization lowered inflammatory macrophage number; in the AIP model, this reduced number was not due to suppressed proliferation. More detailed studies with the convenient AIP model indicated that CSF-1 neutralization led to a relatively uniform reduction in all inflammatory cell populations; GM-CSF neutralization, in contrast, was more selective, resulting in the preferential loss among the MPS populations of a cycling, monocyte-derived inflammatory dendritic cell population. Some mechanistic options for the specific CSF-dependent biologies enumerated are discussed.
Objective
The production of class‐switched high‐affinity autoantibodies derived from organized germinal centers (GCs) is a hallmark of many autoimmune inflammatory diseases, including rheumatoid ...arthritis (RA). TANK‐binding kinase 1 (TBK‐1) is a serine/threonine kinase involved in the maturation of GC follicular helper T (Tfh) cells downstream of inducible costimulator signaling. We undertook this study to assess the therapeutic potential of TBK‐1 inhibition using the small‐molecule inhibitor WEHI‐112 in antibody‐dependent models of inflammatory arthritis.
Methods
Using the models of collagen‐induced arthritis (CIA), antigen‐induced arthritis (AIA), and K/BxN serum‐transfer–induced arthritis (STIA), we determined the effectiveness of WEHI‐112 at inhibiting clinical and histologic features of arthritis in C57BL/6 and DBA/1 mice. We used immunohistochemistry to characterize GC populations during CIA development, and we used enzyme‐linked immunosorbent assays to determine levels of Ig autoantibodies in WEHI‐112–treated mice compared to vehicle‐treated mice.
Results
WEHI‐112, a tool compound that is semiselective for TBK‐1 but that also has activity against IKKε and JAK2, abolished TBK‐1–dependent activation of interferon (IFN) regulatory factor 3 and inhibited type I IFN responses in vitro. In vivo, treatment with WEHI‐112 selectively abrogated clinical and histologic features of established, antibody‐dependent CIA, but had minimal effects on an antibody‐independent model of AIA or on K/BxN STIA. In keeping with these findings, WEHI‐112 reduced arthritogenic type II collagen–specific IgG1 and IgG2b antibody production. Furthermore, WEHI‐112 altered the GC Tfh cell phenotype and GC B cell function in CIA.
Conclusion
We report that TBK‐1 inhibition using WEHI‐112 abrogated antibody‐dependent CIA. As WEHI‐112 failed to inhibit non–antibody‐driven joint inflammation, we conclude that the major effect of this compound was most likely the targeting of TBK‐1–mediated mechanisms in the GC reaction. This approach may have therapeutic potential in RA and in other GC‐associated autoantibody‐driven inflammatory diseases.
Natural killer (NK) cells are a specialised population of innate lymphoid cells (ILCs) that help control local immune responses. Through natural cytotoxicity, production of cytokines and chemokines, ...and migratory capacity, NK cells play a vital immunoregulatory role in the initiation and chronicity of inflammatory and autoimmune responses. Our understanding of their functional differences and contributions in disease settings is evolving owing to new genetic and functional murine proof‐of‐concept studies. Here, we summarise current understanding of NK cells in several classic autoimmune disorders, particularly in rheumatoid arthritis (RA), multiple sclerosis (MS), systemic lupus erythematosus (SLE) and type 1 diabetes mellitus (T1DM), but also less understood diseases such as idiopathic inflammatory myopathies (IIMs). A better understanding of how NK cells contribute to these autoimmune disorders may pave the way for NK cell‐targeted therapeutics.
In this review, we summarise current understanding of NK cells in several classic autoimmune disorders, particularly in rheumatoid arthritis (RA), multiple sclerosis (MS), systemic lupus erythematosus (SLE) and type 1 diabetes mellitus (T1DM), but also less understood diseases such as idiopathic inflammatory myopathies. We also discuss how a better understanding of the contribution of NK cells to these autoimmune disorders may pave the way for NK cell‐targeted therapeutics.
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