Interleukin-33 in health and disease. Nat Rev Immunol. 2016;16:676-689. [PMID: 27640624 DOI: 10.1038/nri.2016.95]

Steroid-resistant human inflammatory ILC2s are marked by CD45RO and elevated in type 2 respiratory diseases

Group 2 innate lymphoid cells (ILC2s) orchestrate protective type 2 immunity and have been implicated in various immune disorders. In the mouse, circulatory inflammatory ILC2s (iILC2s) were identified as a major source of type 2 cytokines. The human equivalent of the iILC2 subset remains unknown. Here, we identify a human inflammatory ILC2 population that resides in inflamed mucosal tissue and is specifically marked by surface CD45RO expression. CD45RO⁺ ILC2s are derived from resting CD45RA⁺ ILC2s upon activation by epithelial alarmins such as IL-33 and TSLP, which is tightly linked to STAT5 activation and up-regulation of the IRF4/BATF transcription factors. Transcriptome analysis reveals marked similarities between human CD45RO⁺ ILC2s and mouse iILC2s. Frequencies of CD45RO⁺ inflammatory ILC2 are increased in inflamed mucosal tissue and in the circulation of patients with chronic rhinosinusitis or asthma, correlating with disease severity and resistance to corticosteroid therapy. CD45RA-to-CD45RO ILC2 conversion is suppressed by corticosteroids via induction of differentiation toward an immunomodulatory ILC2 phenotype characterized by low type 2 cytokine and high amphiregulin expression. Once converted, however, CD45RO⁺ ILC2s are resistant to corticosteroids, which is associated with metabolic reprogramming resulting in the activation of detoxification pathways. Our combined data identify CD45RO⁺ inflammatory ILC2s as a human analog of mouse iILC2s linked to severe type 2 inflammatory disease and therapy resistance.

Pathophysiologic role of Interleukin-33/ST2 in Sjögren's syndrome

Interleukin-33 (IL-33) is a member of the IL-1 family and has dual functions as a nuclear factor as well as a cytokine. The pivotal role of IL-33 as an active player contributing to aberrant local and systemic damage has been highlighted in several inflammatory and autoimmune diseases. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by dry eyes and mouth syndrome due to local dysfunctions of exocrine glands, but also accompanied with systemic manifestations. The pathophysiology of pSS has been advocated as a conjecture of activated B and T cells as well as the production of inflammatory cytokines and autoantibodies, driving epithelial tissue damage and disease progression. In pSS, IL-33 is released in the extracellular space from damaged salivary cells upon pro-inflammatory stimuli and/or dysfunction of epithelial barrier. Counter-regulatory mechanisms are initiated to limit the pro-inflammatory actions of IL-33 as portrayed by an increase in the decoy receptor for IL-33, the soluble form of ST2 (sST2). In pSS and associated diseases, the levels of IL-33 are significantly elevated in the serum or tears of patients. Mechanistically, IL-33 acts in synergy with IL-12 and IL-23 on NK and NKT cells to boost the production of IFN-γ contributing to inflammation. TNF-α, IL-1β and IFN-γ in turn further increase the activation of IL-33/ST2 pathway, thereby constituting a vicious inflammatory loop leading to disease exacerbation. IL-33/ST2 axis is involved in Sjögren's syndrome and opens new perspectives as therapeutic target of one of the culprits in the inflammatory perpetuation.

Germline variants in exonic regions have limited impact on immune checkpoint blockade clinical outcomes in advanced melanoma

Immune checkpoint inhibition (ICI) treatments improve outcomes for metastatic melanoma; however, up to 60% of treated patients do not respond to ICI and/or develop immune-related adverse events (irAEs). Currently, robust and reliable biomarker to predict response and/or occurrence of irAEs to ICI are missing. Herein, we wanted to explore whether germline variants (SNPs) could predict the clinical outcomes of melanoma patients treated with ICIs. We performed a whole exome sequencing using gDNA isolated from blood, from a discovery cohort of 57 patients with metastatic melanoma. The top associations were then tested in a validation cohort of 57 patients. Our work suggests that individual germline genetic variants have no or weak impact on the response to ICIs. Only, variants in IL1RL1 have a significant impact in treatment response. The role of IL1RL1 in the immune response against melanoma and as a theranostic marker warrants further investigations.

IL-33 Changes Our "Gut Feelings" about Serotonin

Many studies highlight direct interactions between immune cells and enteric neurons, but whether immune signals can indirectly modulate enteric function through neurotransmitter regulation is poorly understood. In this issue of Immunity, Chen et al. reveal how IL-33 induces intestinal serotonin to promote gut motility.

IL-33 and Superantigenic Activation of Human Lung Mast Cells Induce the Release of Angiogenic and Lymphangiogenic Factors

Human lung mast cells (HLMCs) express the high-affinity receptor FcεRI for IgE and are strategically located in different compartments of human lung, where they play a role in several inflammatory disorders and cancer. Immunoglobulin superantigens (e.g., protein A of Staphylococcus aureus and protein L of Peptostreptococcus magnus) bind to the variable regions of either the heavy (V_H3) or light chain (κ) of IgE. IL-33 is a cytokine expressed by epithelial cells that exerts pleiotropic functions in the lung. The present study investigated whether immunoglobulin superantigens protein A and protein L and IL-33 caused the release of inflammatory (histamine), angiogenic (VEGF-A) and lymphangiogenic (VEGF-C) factors from HLMCs. The results show that protein A and protein L induced the rapid (30 min) release of preformed histamine from HLMCs. By contrast, IL-33 did not induce the release of histamine from lung mast cells. Prolonged incubation (12 h) of HLMCs with superantigens and IL-33 induced the release of VEGF-A and VEGF-C. Preincubation with IL-33 potentiated the superantigenic release of histamine, angiogenic and lymphangiogenic factors from HLMCs. Our results suggest that IL-33 might enhance the inflammatory, angiogenic and lymphangiogenic activities of lung mast cells in pulmonary disorders.

Inflammatory Mediators and Pain in Endometriosis: A Systematic Review

BACKGROUND

pain is one of the main symptoms of endometriosis and it has a deleterious effect on a patients' personal and social life. To date, the clinical management of pain includes prolonged medication use and, in some cases, surgery, both of which are disruptive events for patients. Hence, there is an urgency for the development of a sufficient non-invasive medical treatment. Inflammation is one of the causative factors of pain in endometriosis. It is well established that inflammatory mediators promote angiogenesis and interact with the sensory neurons inducing the pain signal; the threshold of pain varies and it depends on the state and location of the disease. The inhibition of inflammatory mediators' synthesis might offer a novel and effective treatment of the pain that is caused by inflammation in endometriosis.

OBJECTIVES

patients with endometriosis experience chronic pelvic pain, which is moderate to severe in terms of intensity. The objective of this systematic review is to highlight the inflammatory mediators that contribute to the induction of pain in endometriosis and present their biological mechanism of action. In addition, the authors aim to identify new targets for the development of novel treatments for chronic pelvic pain in patients with endometriosis.

DATA SOURCES

three databases (PubMed, Scopus, and Europe PMC) were searched in order to retrieve articles with the keywords 'inflammation, pain, and endometriosis' between the review period of 1 January 2016 to 31 December 2020. This review has been registered with PROSPERO (registry number: CRD42020171018). Eligibility Criteria: only original articles that presented the regulation of inflammatory mediators and related biological molecules in endometriosis and their contribution in the stimulation of pain signal were included.

DATA EXTRACTION

two authors independently extracted data from articles, using predefined criteria.

RESULTS

the database search yielded 1871 articles, which were narrowed down to 56 relevant articles of interest according to the eligibility criteria.

CONCLUSIONS

inflammatory factors that promote angiogenesis and neuroangiogenesis are promising targets for the treatment of inflammatory pain in endometriosis. Specifically, CXC chemokine family, chemokine fractalkine, and PGE2 have an active role in the induction of pain. Additionally, IL-1β appears to be the primary interleukin (IL), which stimulates the majority of the inflammatory factors that contribute to neuroangiogenesis along with IL-6. Finally, the role of Ninj1 and BDNF proteins needs further investigation.

IL-33/Vitamin D Crosstalk in Psoriasis-Associated Osteoporosis

Patients with psoriasis (Pso) and, in particular, psoriatic arthritis (PsoA) have an increased risk of developing osteoporosis (OP). It has been shown that OP is among the more common pathologies associated with Pso, mainly due to the well-known osteopenizing conditions coexisting in these patients. Pso and OP share common risk factors, such as vitamin D deficiency and chronic inflammation. Interestingly, the interleukin (IL)-33/ST2 axis, together with vitamin D, is closely related to both Pso and OP. Vitamin D and the IL-33/ST2 signaling pathways are closely involved in bone remodeling, as well as in skin barrier pathophysiology. The production of anti-osteoclastogenic cytokines, e.g., IL-4 and IL-10, is promoted by IL-33 and vitamin D, which are stimulators of both regulatory and Th2 cells. IL-33, together with other Th2 cytokines, shifts osteoclast precursor differentiation towards macrophage and dendritic cells and inhibits receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis by regulating the expression of anti-osteoclastic genes. However, while the vitamin D protective functions in OP and Pso have been definitively ascertained, the overall effect of IL-33 on bone and skin homeostasis, because of its pleiotropic action, is still controversial. Emerging evidence suggests a functional link between vitamin D and the IL-33/ST2 axis, which acts through hormonal influences and immune-mediated effects, as well as cellular and metabolic functions. Based on the actions of vitamin D and IL-33 in Pso and OP, here, we hypothesize the role of their crosstalk in the pathogenesis of both these pathologies.

Asthma and Obesity: Two Diseases on the Rise and Bridged by Inflammation

Asthma and obesity are two epidemics affecting the developed world. The relationship between obesity and both asthma and severe asthma appears to be weight-dependent, causal, partly genetic, and probably bidirectional. There are two distinct phenotypes: 1. Allergic asthma in children with obesity, which worsens a pre-existing asthma, and 2. An often non allergic, late-onset asthma developing as a consequence of obesity. In obesity, infiltration of adipose tissue by macrophages M1, together with an increased expression of multiple mediators that amplify and propagate inflammation, is considered as the culprit of obesity-related inflammation. Adipose tissue is an important source of adipokines, such as pro-inflammatory leptin, produced in excess in obesity, and adiponectin with anti-inflammatory effects with reduced synthesis. The inflammatory process also involves the synthesis of pro-inflammatory cytokines such as IL-1β, IL-6, TNFα, and TGFβ, which also contribute to asthma pathogenesis. In contrast, asthma pro-inflammatory cytokines such as IL-4, IL-5, IL-13, and IL-33 contribute to maintain the lean state. The resulting regulatory effects of the immunomodulatory pathways underlying both diseases have been hypothesized to be one of the mechanisms by which obesity increases asthma risk and severity. Reduction of weight by diet, exercise, or bariatric surgery reduces inflammatory activity and improves asthma and lung function.

Requirement of brain interleukin33 for aquaporin4 expression in astrocytes and glymphatic drainage of abnormal tau

Defective aquaporin4 (AQP4)-mediated glymphatic drainage has been linked to tauopathy and amyloid plaque in Alzheimer's disease. We now show that brain interleukin33 (IL33) is required for regulation of AQP4 expression in astrocytes, especially those at neuron-facing membrane domain (n-AQP4). First, IL33-deficient (Il33^-/-) mice showed a loss of n-AQP4 after middle age, which coincided with a rapid accumulation of abnormal tau in neurons and a reduction in drainage of abnormal tau to peripheral tissues. Second, injection of recombinant IL33 induced robust expression of AQP4 at perivascular endfoot (p-AQP4) of astrocytes, but not n-AQP4, in Il33^-/- brains. Although the increased p-AQP4 greatly accelerated drainage of intracerebroventricularly injected peptides, it did not substantially accelerate drainage of abnormal tau. These results suggest that p-AQP4 drives overall convective flow toward perivenous space, i.e., glymphatics, whereas n-AQP4 may generate an aqueous flow away from neurons to remove neuronal wastes, e.g., abnormal tau. We have previously shown the role of brain IL33 in DNA repair and autophagy in neurons with oxidative stress. Now, we show that IL33 deficiency also impairs glymphatic drainage. Defects in those mechanisms together may lead to chronic neurodegeneration and tauopathy at old age in IL33-deficient mice.

Regulation of neuroimmune processes by damage- and resolution-associated molecular patterns

Sterile inflammatory processes are essential for the maintenance of central nervous system homeostasis, but they also contribute to various neurological disorders, including neurotrauma, stroke, and demyelinating or neurodegenerative diseases. Immune mechanisms in the central nervous system and periphery are regulated by a diverse group of endogenous proteins, which can be broadly divided into the pro-inflammatory damage-associated molecular patterns (DAMPs) and anti-inflammatory resolution-associated molecular patterns (RAMPs), even though there is notable overlap between the DAMP- and RAMP-like activities for some of these molecules. Both groups of molecular patterns were initially described in peripheral immune processes and pathologies; however, it is now evident that at least some, if not all, of these immunomodulators also regulate neuroimmune processes and contribute to neuroinflammation in diverse central nervous system disorders. The review of recent literature demonstrates that studies on DAMPs and RAMPs of the central nervous system still lag behind the much broader research effort focused on their peripheral counterparts. Nevertheless, this review also reveals that over the last five years, significant advances have been made in our understanding of the neuroimmune functions of several well-established DAMPs, including high-mobility group box 1 protein and interleukin 33. Novel neuroimmune functions have been demonstrated for other DAMPs that previously were considered almost exclusively as peripheral immune regulators; they include mitochondrial transcription factor A and cytochrome C. RAMPs of the central nervous system are an emerging area of neuroimmunology with very high translational potential since some of these molecules have already been used in preclinical and clinical studies as candidate therapeutic agents for inflammatory conditions, such as multiple sclerosis and rheumatoid arthritis. The therapeutic potential of DAMP antagonists and neutralizing antibodies in central nervous system neuroinflammatory diseases is also supported by several of the identified studies. It can be concluded that further studies of DAMPs and RAMPs of the central nervous system will continue to be an important and productive field of neuroimmunology.

Estrogen receptor-α signaling increases allergen-induced IL-33 release and airway inflammation

BACKGROUND

Group 2 innate lymphoid cells (ILC2) are stimulated by IL-33 to increase IL-5 and IL-13 production and airway inflammation. While sex hormones regulate airway inflammation, it remained unclear whether estrogen signaling through estrogen receptor-α (ER-α, Esr1) or ER-β (Esr2) increased ILC2-mediated airway inflammation. We hypothesize that estrogen signaling increases allergen-induced IL-33 release, ILC2 cytokine production, and airway inflammation.

METHODS

Female Esr1^-/- , Esr2^-/- , wild-type (WT), and IL33^fl/fl eGFP mice were challenged with Alternaria extract (Alt Ext) or vehicle for 4 days. In select experiments, mice were administered tamoxifen or vehicle pellets for 21 days prior to challenge. Lung ILC2, IL-5 and IL-13 production, and BAL inflammatory cells were measured on day 5 of Alt Ext challenge model. Bone marrow from WT and Esr1^-/- female mice was transferred (1:1 ratio) into WT female recipients for 6 weeks followed by Alt Ext challenge. hBE33 cells and normal human bronchial epithelial cells (NHBE) were pretreated with 17β-estradiol (E2), propyl-pyrazole-triol (PPT, ER-α agonist), or diarylpropionitrile (DPN, ER-β agonist) before allergen challenge to determine IL-33 gene expression and release, extracellular ATP release, DUOX-1 production, and necrosis.

RESULTS

Alt Ext challenged Esr1^-/- , but not Esr2^-/- , mice had decreased IL-5 and IL-13 production, BAL eosinophils, and IL-33 release compared to WT mice. Tamoxifen decreased IL-5 and IL-13 production and BAL eosinophils. IL-33eGFP + epithelial cells were decreased in Alt Ext challenged Esr1^-/- mice compared to WT mice. 17β-E2 or PPT, but not DPN, increased IL-33 gene expression, release, and DUOX-1 production in hBE33 or NHBE cells.

CONCLUSION

Estrogen receptor -α signaling increased IL-33 release and ILC2-mediated airway inflammation.

Interleukin-31, a Potent Pruritus-Inducing Cytokine and Its Role in Inflammatory Disease and in the Tumor Microenvironment

Substantial new information has emerged supporting the fundamental role of the cytokine interleukin-31 (IL-31) in the genesis of chronic pruritus in a broad array of clinical conditions. These include inflammatory conditions, such as atopic dermatitis and chronic urticaria, to autoimmune conditions such as dermatomyositis and bullous pemphigoid, to the lymphoproliferative disorders of Hodgkin's disease and cutaneous T-cell lymphoma. IL-31 is produced in greatest quantity by T-helper type 2 (Th2) cells and upon release, interacts with a cascade of other cytokines and chemokines to lead to pruritus and to a proinflammatory environment, particularly within the skin. Antibodies which neutralize IL-31 or which block the IL-31 receptor may reduce or eliminate pruritus and may diminish the manifestations of chronic cutaneous conditions associated with elevated IL-31. The role of IL-31 in these various conditions will be reviewed.

IL-33 ameliorates liver injury and inflammation in Poly I:C and Concanavalin-A induced acute hepatitis

The IL-33/ST2 axis is known to be involved in liver pathologies and IL-33 is over-expressed in mouse hepatitis models. We aimed to investigate the proposed protective effect of IL-33 in murine fulminant hepatitis induced by a Toll like receptor 3 (TLR3) viral mimetic, Poly I:C or by Concanavalin-A (ConA). The Balb/C mice were administered intravenously with ConA (15 mg/kg) or Poly I:C (30 μg/mouse) to induce acute hepatitis along with vehicle control. The recombinant mouse IL-33 (rIL-33) was injected (0.2 μg/mouse) to mice 2 h prior to ConA or Poly I:C injection to check its hepato-protective effects. The gross lesions, level of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), histopathology (H&E staining) and levels of IFNγ and TNFα were measured by ELISA. The gross pathological liver injury induced by Poly I:C or ConA was reduced by rIL-33 administration in mice. The levels of AST and ALT were significantly (P ≤ 0.05) higher in mice challenged with Poly I:C or ConA in comparison to control mice. The rIL-33 pre-treated mice in both Poly I:C and ConA challenge groups showed significantly (P ≤ 0.05) lower levels of AST and ALT, and decreased liver injury (parenchymal and per-vascular necrotic areas) in histological liver sections. The soluble levels of TNFα and IFNγ were significantly (P ≤ 0.05) raised in Poly I:C or ConA challenged mice than control mice. The levels of TNFα and IFNγ were significantly reduced (P ≤ 0.05) in rIL-33 pre-treated mice. In conclusion, the exogenous IL-33 administration mitigated liver injury and inflammation (decreased levels of IFNγ and TNFα) in Poly I:C and ConA-induced acute hepatitis in mice.

Mechanical Ventilation with Moderate Tidal Volume Exacerbates Extrapulmonary Sepsis-Induced Lung Injury via IL33-WISP1 Signaling Pathway

ABSTRACT

IL-33 and WNT1-inducible secreted protein (WISP1) play central roles in acute lung injury (ALI) induced by mechanical ventilation with moderate tidal volume (MTV) in the setting of sepsis. Here, we sought to determine the inter-relationship between IL-33 and WISP1 and the associated signaling pathways in this process.We used a two-hit model of cecal ligation puncture (CLP) followed by MTV ventilation (4 h 10 mL/kg) in wild-type, IL-33-/- or ST2-/- mice or wild-type mice treated with intratracheal antibodies to WISP1. Macrophages (Raw 264.7 and alveolar macrophages from wild-type or ST2-/- mice) were used to identify specific signaling components.CLP + MTV resulted in ALI that was partially sensitive to genetic ablation of IL-33 or ST2 or antibody neutralization of WISP1. Genetic ablation of IL-33 or ST2 significantly prevented ALI after CLP + MTV and reduced levels of WISP1 in the circulation and bronchoalveolar lung fluid. rIL-33 increased WISP1 in alveolar macrophages in an ST2, PI3K/AKT, and ERK dependent manner. This WISP1 upregulation and WNT β-catenin activation were sensitive to inhibition of the β-catenin/TCF/CBP/P300 nuclear pathway.We show that IL-33 drives WISP1 upregulation and ALI during MTV in CLP sepsis. The identification of this relationship and the associated signaling pathways reveals a number of possible therapeutic targets to prevent ALI in ventilated sepsis patients.

IL-33 facilitates rapid expulsion of the parasitic nematode Strongyloides ratti from the intestine via ILC2- and IL-9-driven mast cell activation

Parasitic helminths are sensed by the immune system via tissue-derived alarmins that promote the initiation of the appropriate type 2 immune responses. Here we establish the nuclear alarmin cytokine IL-33 as a non-redundant trigger of specifically IL-9-driven and mast cell-mediated immunity to the intestinal parasite Strongyloides ratti. Blockade of endogenous IL-33 using a helminth-derived IL-33 inhibitor elevated intestinal parasite burdens in the context of reduced mast cell activation while stabilization of endogenous IL-33 or application of recombinant IL-33 reciprocally reduced intestinal parasite burdens and increased mast cell activation. Using gene-deficient mice, we show that application of IL-33 triggered rapid mast cell-mediated expulsion of parasites directly in the intestine, independent of the adaptive immune system, basophils, eosinophils or Gr-1+ cells but dependent on functional IL-9 receptor and innate lymphoid cells (ILC). Thereby we connect the described axis of IL-33-mediated ILC2 expansion to the rapid initiation of IL-9-mediated and mast cell-driven intestinal anti-helminth immunity.

Astrocyte-secreted IL-33 mediates homeostatic synaptic plasticity in the adult hippocampus

Synaptic plasticity in the hippocampus is important for learning and memory formation. In particular, homeostatic synaptic plasticity enables neurons to restore their activity levels in response to chronic neuronal activity changes. While astrocytes modulate synaptic functions via the secretion of factors, the underlying molecular mechanisms remain unclear. Here, we show that suppression of hippocampal neuronal activity increases cytokine IL-33 release from astrocytes in the CA1 region. Activation of IL-33 and its neuronal ST2 receptor complex promotes functional excitatory synapse formation. Moreover, IL-33/ST2 signaling is important for the neuronal activity blockade-induced increase of CA1 excitatory synapses in vivo and spatial memory formation. This study suggests that astrocyte-secreted IL-33 acts as a negative feedback control signal to regulate hippocampal homeostatic synaptic plasticity.

Hippocampal synaptic plasticity is important for learning and memory formation. Homeostatic synaptic plasticity is a specific form of synaptic plasticity that is induced upon prolonged changes in neuronal activity to maintain network homeostasis. While astrocytes are important regulators of synaptic transmission and plasticity, it is largely unclear how they interact with neurons to regulate synaptic plasticity at the circuit level. Here, we show that neuronal activity blockade selectively increases the expression and secretion of IL-33 (interleukin-33) by astrocytes in the hippocampal cornu ammonis 1 (CA1) subregion. This IL-33 stimulates an increase in excitatory synapses and neurotransmission through the activation of neuronal IL-33 receptor complex and synaptic recruitment of the scaffold protein PSD-95. We found that acute administration of tetrodotoxin in hippocampal slices or inhibition of hippocampal CA1 excitatory neurons by optogenetic manipulation increases IL-33 expression in CA1 astrocytes. Furthermore, IL-33 administration in vivo promotes the formation of functional excitatory synapses in hippocampal CA1 neurons, whereas conditional knockout of IL-33 in CA1 astrocytes decreases the number of excitatory synapses therein. Importantly, blockade of IL-33 and its receptor signaling in vivo by intracerebroventricular administration of its decoy receptor inhibits homeostatic synaptic plasticity in CA1 pyramidal neurons and impairs spatial memory formation in mice. These results collectively reveal an important role of astrocytic IL-33 in mediating the negative-feedback signaling mechanism in homeostatic synaptic plasticity, providing insights into how astrocytes maintain hippocampal network homeostasis.

The structure of SeviL, a GM1b/asialo-GM1 binding R-type lectin from the mussel Mytilisepta virgata

SeviL is a recently isolated lectin found to bind to the linear saccharides of the ganglioside GM1b (Neu5Ac\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\alpha$$\end{document}α(2-3)Gal\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-3)GalNAc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-4)Gal\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-4)Glc) and its precursor, asialo-GM1 (Gal\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-3)GalNAc\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-4)Gal\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β(1-4)Glc). The crystal structures of recombinant SeviL have been determined in the presence and absence of ligand. The protein belongs to the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}β-trefoil family, but shows only weak sequence similarity to known structures. SeviL forms a dimer in solution, with one binding site per subunit, close to the subunit interface. Molecular details of glycan recognition by SeviL in solution were analysed by ligand- and protein-based NMR techniques as well as ligand binding assays. SeviL shows no interaction with GM1 due to steric hindrance with the sialic acid branch that is absent from GM1b. This unusual specificity makes SeviL of great interest for the detection and control of certain cancer cells, and cells of the immune system, that display asialo-GM1.

Pathology of IgG4-related sclerosing mastitis

Immunoglobulin G4-related sclerosing mastitis (IgG4-RM) is a recently recognised member of the IgG4-related disease (IgG4-RD) family, a multisystem fibroinflammatory condition that can affect any organ system. IgG4-RM is rare and predominantly occurs in middle-aged women. It may present with painless palpable mass and/or lymphadenopathy thereby mimicking breast cancer. Although there is an abundance of literature describing the clinicopathological characteristics of IgG4-RD in a variety of organs, data on IgG4-RM are limited due to its rarity. This review describes the manifestation of the disease in the breast based on reported cases, emphasising the clinicopathological features, pathophysiology, differential diagnosis, treatment and prognosis.

Mechanisms Underlying the Skin-Gut Cross Talk in the Development of IgE-Mediated Food Allergy

Immune-globulin E (IgE)-mediated food allergy is characterized by a variety of clinical entities within the gastrointestinal tract, skin and lungs, and systemically as anaphylaxis. The default response to food antigens, which is antigen specific immune tolerance, requires exposure to the antigen and is already initiated during pregnancy. After birth, tolerance is mostly acquired in the gut after oral ingestion of dietary proteins, whilst exposure to these same proteins via the skin, especially when it is inflamed and has a disrupted barrier, can lead to allergic sensitization. The crosstalk between the skin and the gut, which is involved in the induction of food allergy, is still incompletely understood. In this review, we will focus on mechanisms underlying allergic sensitization (to food antigens) via the skin, leading to gastrointestinal inflammation, and the development of IgE-mediated food allergy. Better understanding of these processes will eventually help to develop new preventive and therapeutic strategies in children.

NKT cells promote both type 1 and type 2 inflammatory responses in a mouse model of liver fibrosis

Sterile liver inflammation and fibrosis are associated with many liver disorders of different etiologies. Both type 1 and type 2 inflammatory responses have been reported to contribute to liver pathology. However, the mechanisms controlling the balance between these responses are largely unknown. Natural killer T (NKT) cells can be activated to rapidly secrete cytokines and chemokines associated with both type 1 and type 2 inflammatory responses. As these proteins have been reported to accumulate in different types of sterile liver inflammation, we hypothesized that these cells may play a role in this pathological process. We have found that a transgenic NKT (tgNKT) cell population produced in the immunodeficient 2,4αβNOD.Rag2^−/− mice, but not in 2,4αβNOD.Rag2^+/− control mice, promoted a type 1 inflammatory response with engagement of the NOD-, LRR- and pyrin domain-containing protein-3 (NLRP3) inflammasome. The induction of the type 1 inflammatory response was followed by an altered cytokine profile of the tgNKT cell population with a biased production of anti-inflammatory/profibrotic cytokines and development of liver fibrosis. These findings illustrate how the plasticity of NKT cells modulates the inflammatory response, suggesting a key role for the NKT cell population in the control of sterile liver inflammation.

Signaling Pathways Implicated in Carbon Nanotube-Induced Lung Inflammation

Inflammation is a tissue response to a variety of harmful stimuli, such as pathogens, irritants, and injuries, and can eliminate insults and limit tissue damage. However, dysregulated inflammation is recognized as a cause of many human diseases, exemplified by organ fibrosis and cancer. In this regard, inflammation-promoted fibrosis is commonly observed in human lung diseases, such as idiopathic pulmonary fibrosis and pneumoconiosis. Carbon nanotubes (CNTs) are a type of nanomaterials with unique properties and various industrial and commercial applications. On the other hand, certain forms of CNTs are potent inducers of inflammation and fibrosis in animal lungs. Notably, acute inflammation is a remarkable phenotype elicited by CNTs in the lung during the early acute phase post-exposure; whereas a type 2 immune response is evidently activated and dominates during the late acute and chronic phases, leading to type 2 inflammation and lung fibrosis. Numerous studies demonstrate that these immune responses involve distinct immune cells, various pathologic factors, and specific functions and play crucial roles in the initiation and progression of inflammation and fibrosis in the lung exposed to CNTs. Thus, the mechanistic understanding of the immune responses activated by CNTs has drawn great attention in recent years. This article reviews the major findings on the cell signaling pathways that are activated in immune cells and exert functions in promoting immune responses in CNT-exposed lungs, which would provide new insights into the understanding of CNT-induced lung inflammation and inflammation-driven fibrosis, the application of CNT-induced lung inflammation and fibrosis as a new disease model, and the potential of targeting immune cells as a therapeutic strategy for relevant human lung diseases.

"NETs and EETs, a Whole Web of Mess"

Neutrophils and eosinophils are granulocytes that have very distinct functions. Neutrophils are first responders to external threats, and they use different mechanisms to control pathogens. Phagocytosis, reactive oxygen species, and neutrophil extracellular traps (NETs) are some of the mechanisms that neutrophils utilize to fight pathogens. Although there is some controversy as to whether NETs are in fact beneficial or detrimental to the host, it mainly depends on the biological context. NETs can contribute to disease pathogenesis in certain types of diseases, while they are also undeniably critical components of the innate immune response. On the contrary, the role of eosinophils during host immune responses remains to be better elucidated. Eosinophils play an important role during helminthic infections and allergic responses. Eosinophils can function as effector cells in viral respiratory infections, gut bacterial infections, and as modulators of immune responses by driving the balance between Th1 and Th2 responses. In particular, eosinophils have biological activities that appear to be quite similar to those of neutrophils. Both possess bactericidal activity, can activate proinflammatory responses, can modulate adaptive immune responses, can form extracellular traps, and can be beneficial or detrimental to the host according to the underlying pathology. In this review we compare these two cell types with a focus on highlighting their numerous similarities related to extracellular traps.

The first-in-human study of CNTO 7160, an anti-interleukin-33 receptor monoclonal antibody, in healthy subjects and patients with asthma or atopic dermatitis

AIMS

To assess safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and immunogenicity of CNTO 7160, an anti-interleukin-33 receptor (IL-33R) monoclonal antibody, in healthy subjects and patients with asthma or atopic dermatitis (AD).

METHODS

In Part 1 of this Phase I, randomized, double-blind, placebo-controlled study, healthy subjects (n = 68) received single ascending intravenous (IV) CNTO 7160 dose (0.001 to 10 mg/kg) or placebo. In Part 2, patients with mild asthma (n = 24) or mild AD (n = 15) received 3 biweekly IV CNTO 7160 doses (3 or 10 mg/kg) or placebo.

RESULTS

CNTO 7160 was generally well tolerated, with 1 serious adverse event of severe cellulitis reported (AD, CNTO 7160, 3 mg/kg). CNTO 7160 exhibited nonlinear PK (0.01-10 mg/kg). Mean clearance decreased with increasing dose (2.43 to 18.03 mL/d/kg). CNTO 7160 PK was similar between healthy subjects and patients with asthma or AD (3 or 10 mg/kg). Free sIL-33R suppression was rapid and dose dependent. Ex vivo inhibition of p38 phosphorylation of basophils was dose-dependent (1-10 mg/kg) and sustained inhibition (≥75%) was observed at higher doses (3 or 10 mg/kg). PK/PD modelling and simulation suggests that 1 mg/kg IV every 2 weeks provides adequate systemic drug exposure for sustained inhibition of p38 phosphorylation of basophils. Despite confirmation of target engagement, no apparent CNTO 7160 clinical activity was observed in patients (asthma or AD).

CONCLUSION

This first-in-human study provides PK, PD and safety data, supporting further clinical investigation of CNTO 7160 in patients with asthma and AD.

Anti-Tumorigenic Activities of IL-33: A Mechanistic Insight

Interleukin-33 (IL-33) is an epithelial-derived cytokine that can be released upon tissue damage, stress, or infection, acting as an alarmin for the immune system. IL-33 has long been studied in the context of Th2-related immunopathologies, such as allergic diseases and parasitic infections. However, its capacity to stimulate also Th1-type of immune responses is now well established. IL-33 binds to its specific receptor ST2 expressed by most immune cell populations, modulating a variety of responses. In cancer immunity, IL-33 can display both pro-tumoral and anti-tumoral functions, depending on the specific microenvironment. Recent findings indicate that IL-33 can effectively stimulate immune effector cells (NK and CD8⁺ T cells), eosinophils, basophils and type 2 innate lymphoid cells (ILC2) promoting direct and indirect anti-tumoral activities. In this review, we summarize the most recent advances on anti-tumor immune mechanisms operated by IL-33, including the modulation of immune checkpoint molecules, with the aim to understand its potential as a therapeutic target in cancer.

Myeloid-Derived IL-33 Limits the Severity of Dextran Sulfate Sodium-Induced Colitis

IL-33 is an IL-1 family cytokine that signals through its cognate receptor, ST2, to regulate inflammation. Whether IL-33 serves a pathogenic or protective role during inflammatory bowel disease is controversial. Herein, two different strains of cell-specific conditionally deficient mice were used to compare the role of myeloid- versus intestinal epithelial cell-derived IL-33 during dextran sodium sulfate-induced colitis. Data show that loss of CD11c-restricted IL-33 exacerbated tissue pathology, coinciding with increased tissue Il6 levels and loss of intestinal forkhead box p3⁺ regulatory T cells. Surprisingly, the lack of intestinal epithelial cell-derived IL-33 had no impact on disease severity or tissue recovery. Thus, we show that myeloid-derived IL-33 functionally restrains colitic disease, whereas intestinal epithelial cell-derived IL-33 is dispensable.

Interleukin-33 Promotes Serotonin Release from Enterochromaffin Cells for Intestinal Homeostasis

The gastrointestinal tract is known as the largest endocrine organ that encounters and integrates various immune stimulations and neuronal responses due to constant environmental challenges. Enterochromaffin (EC) cells, which function as chemosensors on the gut epithelium, are known to translate environmental cues into serotonin (5-HT) production, contributing to intestinal physiology. However, how immune signals participate in gut sensation and neuroendocrine response remains unclear. Interleukin-33 (IL-33) acts as an alarmin cytokine by alerting the system of potential environmental stresses. We here demonstrate that IL-33 induced instantaneous peristaltic movement and facilitated Trichuris muris expulsion. We found that IL-33 could be sensed by EC cells, inducing release of 5-HT. IL-33-mediated 5-HT release activated enteric neurons, subsequently promoting gut motility. Mechanistically, IL-33 triggered calcium influx via a non-canonical signaling pathway specifically in EC cells to induce 5-HT secretion. Our data establish an immune-neuroendocrine axis in calibrating rapid 5-HT release for intestinal homeostasis.

Cellular context of IL-33 expression dictates impact on anti-helminth immunity

Interleukin-33 (IL-33) is a pleiotropic cytokine that can promote type 2 inflammation but also drives immunoregulation through Foxp3⁺T_reg expansion. How IL-33 is exported from cells to serve this dual role in immunosuppression and inflammation remains unclear. Here, we demonstrate that the biological consequences of IL-33 activity are dictated by its cellular source. Whereas IL-33 derived from epithelial cells stimulates group 2 innate lymphoid cell (ILC2)-driven type 2 immunity and parasite clearance, we report that IL-33 derived from myeloid antigen-presenting cells (APCs) suppresses host-protective inflammatory responses. Conditional deletion of IL-33 in CD11c-expressing cells resulted in lowered numbers of intestinal Foxp3⁺T_reg cells that express the transcription factor GATA3 and the IL-33 receptor ST2, causing elevated IL-5 and IL-13 production and accelerated anti-helminth immunity. We demonstrate that cell-intrinsic IL-33 promoted mouse dendritic cells (DCs) to express the pore-forming protein perforin-2, which may function as a conduit on the plasma membrane facilitating IL-33 export. Lack of perforin-2 in DCs blocked the proliferative expansion of the ST2⁺Foxp3⁺T_reg subset. We propose that perforin-2 can provide a plasma membrane conduit in DCs that promotes the export of IL-33, contributing to mucosal immunoregulation under steady-state and infectious conditions.

Acute and subacute oral toxicity of deoxynivalenol exposure in a Dermatophagoides farinae induced murine asthma model

Previously, researchers have demonstrated that mycotoxin deoxynivalenol significantly enhances immunocyte activation. However, the interaction between deoxynivalenol exposure and immune disorders remains unclear. In this study, we aimed to investigate whether acute and subacute oral exposure to deoxynivalenol exacerbates the development of respiratory allergy using a mite allergen (Dermatophagoides farina, Derf)-induced mouse model of asthma. The direct relationship between deoxynivalenol exposure and asthma development was examined following acute oral deoxynivalenol administration (0, 0.1, or 0.3 mg/kg body weight), immediately before the final mite allergen challenge. Simultaneously, the influence of subacute oral exposure via low dose deoxynivalenol contaminated wheat (0.33 ppm) was evaluated using the same settings. To detect the pro-inflammatory effects of deoxynivalenol exposure, we examined the total and Derf-specific serum IgE levels, histology, number of immunocytes, and cytokine and chemokine secretion. Acute oral deoxynivalenol significantly enhanced the inflammatory responses, including cellular infiltration into bronchoalveolar lavage fluid, infiltration of immunocytes and cytokine production in local lymph nodes, and cytokine levels in lung tissues. Corresponding pro-inflammatory responses were observed in a mouse group exposed to subacute oral deoxynivalenol. In vivo results were validated by in vitro experiments using the human bronchial epithelial (BEAS-2B) and human eosinophilic leukemia (EOL-1) cell lines. Following exposure to deoxynivalenol, the secretion of interleukin (IL)-1β, IL-6, IL-8, and/or tumor necrosis factor (TNF)-α in BEAS-2B cells, as well as EoL-1 cells, increased significantly. Our findings indicate that deoxynivalenol exposure is significantly involved in the pro-inflammatory response observed in respiratory allergy.

Early Treatment of Interleukin-33 can Attenuate Lupus Development in Young NZB/W F1 Mice

Interleukin-33 (IL-33), a member of the IL-1 cytokine family, has been recently associated with the development of autoimmune diseases, including systemic lupus erythematosus (SLE). IL-33 is an alarmin and a pleiotropic cytokine that affects various types of immune cells via binding to its receptor, ST2. In this study, we determine the impact of intraperitoneal IL-33 treatments in young lupus, NZB/W F1 mice. Mice were treated from the age of 6 to 11 weeks. We then assessed the proteinuria level, renal damage, survival rate, and anti-dsDNA antibodies. The induction of regulatory B (Breg) cells, changes in the level of autoantibodies, and gene expression were also examined. In comparison to the control group, young NZB/W F1 mice administered with IL-33 had a better survival rate as well as reduced proteinuria level and lupus nephritis. IL-33 treatments significantly increased the level of IgM anti-dsDNA antibodies, IL-10 expressing Breg cells, and alternatively-induced M2 macrophage gene signatures. These results imply that IL-33 exhibits a regulatory role during lupus onset via the expansion of protective IgM anti-dsDNA as well as regulatory cells such as Breg cells and M2 macrophages.

Immune and Metabolic Interactions of Human Erythrocytes: A Molecular Perspective

Apart from their main function as oxygen carriers in vertebrates, erythrocytes are also involved in immune regulation. By circulating throughout the body, the erythrocytes are exposed and interact with tissues that are damaged as a result of a disease. In this study, we summarize the literature regarding the contribution of erythrocytes to immune regulation and metabolism. Under the circumstances of a disease state, the erythrocytes may lose their antioxidant capacity and release Damage Associated Molecular Patterns, resulting in the regulation of innate and adaptive immunity. In addition, the erythrocytes scavenge and affect the levels of chemokines, circulating cell-free mtDNA, and C3b attached immune complexes. Furthermore, through surface molecules, erythrocytes control the function of T lymphocytes, macrophages, and dendritic cells. Through an array of enzymes, red blood cells contribute to the pool of blood's bioactive lipids. Finally, the erythrocytes contribute to reverse cholesterol transport through various mechanisms. Our study is highlighting overlooked molecular interactions between erythrocytes and immunity and metabolism, which could lead to the discovery of potent therapeutic targets for immunometabolic diseases.

A review of T helper 17 cell-related cytokines in serum and saliva in periodontitis

Periodontitis is a chronic inflammatory disease with a complex underlying immunopathology. Cytokines, as molecular mediators of inflammation, play a role in all stages of disease progression. T helper 17 (Th17) cells are thought to play a role in periodontitis. Th17 cell development and maintenance requires a pro-inflammatory cytokine milieu, with many of the cytokines implicated in the pathogenesis of periodontitis. Serum and saliva are easily accessible biofluids which can represent the systemic and local environment to promote the development of Th17 cells. Here we review human clinical studies that investigate IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, sCD40L and TNF-α in serum and saliva in periodontitis. We highlight their putative role in the pathogenesis of periodontitis and place them within a wider context of animal and other clinical studies.

RGS4 promotes allergen- and aspirin-associated airway hyperresponsiveness by inhibiting PGE2 biosynthesis

BACKGROUND

Allergens elicit host production of mediators acting on G-protein-coupled receptors to regulate airway tone. Among these is prostaglandin E2 (PGE2), which, in addition to its role as a bronchodilator, has anti-inflammatory actions. Some patients with asthma develop bronchospasm after the ingestion of aspirin and other nonsteroidal anti-inflammatory drugs, a disorder termed aspirin-exacerbated respiratory disease. This condition may result in part from abnormal dependence on the bronchoprotective actions of PGE2.

OBJECTIVE

We sought to understand the functions of regulator of G protein signaling 4 (RGS4), a cytoplasmic protein expressed in airway smooth muscle and bronchial epithelium that regulates the activity of G-protein-coupled receptors, in asthma.

METHODS

We examined RGS4 expression in human lung biopsies by immunohistochemistry. We assessed airways hyperresponsiveness (AHR) and lung inflammation in germline and airway smooth muscle-specific Rgs4-/- mice and in mice treated with an RGS4 antagonist after challenge with Aspergillus fumigatus. We examined the role of RGS4 in nonsteroidal anti-inflammatory drug-associated bronchoconstriction by challenging aspirin-exacerbated respiratory disease-like (ptges1-/-) mice with aspirin.

RESULTS

RGS4 expression in respiratory epithelium is increased in subjects with severe asthma. Allergen-induced AHR was unexpectedly diminished in Rgs4-/- mice, a finding associated with increased airway PGE2 levels. RGS4 modulated allergen-induced PGE2 secretion in human bronchial epithelial cells and prostanoid-dependent bronchodilation. The RGS4 antagonist CCG203769 attenuated AHR induced by allergen or aspirin challenge of wild-type or ptges1-/- mice, respectively, in association with increased airway PGE2 levels.

CONCLUSIONS

RGS4 may contribute to the development of AHR by reducing airway PGE2 biosynthesis in allergen- and aspirin-induced asthma.

Tumor-Infiltrating Regulatory T-cell Accumulation in the Tumor Microenvironment Is Mediated by IL33/ST2 Signaling

Regulatory T cells (Treg) are enriched in the tumor microenvironment (TME) and suppress antitumor immunity; however, the molecular mechanism underlying the accumulation of Tregs in the TME is poorly understood. In various tumor models, tumor-infiltrating Tregs were highly enriched in the TME and had significantly higher expression of immune checkpoint molecules. To characterize tumor-infiltrating Tregs, we performed bulk RNA sequencing (RNA-seq) and found that proliferation-related genes, immune suppression-related genes, and cytokine/chemokine receptor genes were upregulated in tumor-infiltrating Tregs compared with tumor-infiltrating CD4+Foxp3- conventional T cells or splenic Tregs from the same tumor-bearing mice. Single-cell RNA-seq and T-cell receptor sequencing also revealed active proliferation of tumor infiltrating Tregs by clonal expansion. One of these genes, ST2, an IL33 receptor, was identified as a potential factor driving Treg accumulation in the TME. Indeed, IL33-directed ST2 signaling induced the preferential proliferation of tumor-infiltrating Tregs and enhanced tumor progression, whereas genetic deletion of ST2 in Tregs limited their TME accumulation and delayed tumor growth. These data demonstrated the IL33/ST2 axis in Tregs as one of the critical pathways for the preferential accumulation of Tregs in the TME and suggests that the IL33/ST2 axis may be a potential therapeutic target for cancer immunotherapy.

Respiratory syncytial virus upregulates IL-33 expression in mouse model of virus-induced inflammation exacerbation in OVA-sensitized mice and in asthmatic subjects

BACKGROUND

Bronchial asthma (BA) is a chronic disease of the airways. The great majority of BA exacerbations are associated with respiratory viral infections. Recent findings point out a possible role of proinflammatory cytokine interleukin-33 (IL-33) in the development of atopic diseases. Although, little is known about the role of IL-33 in virus-induced BA exacerbations.

METHODS

We used mouse models of RSV (respiratory syncytial virus)-induced inflammation exacerbation in OVA-sensitized mice and RSV infection alone in adult animals to characterize expression of il33 in the mouse lungs. Moreover, we studied the influence of il33 knockdown with intranasally administrated siRNA on the development of RSV-induced inflammation exacerbation. In addition, we evaluated the expression of IL33 in the ex vivo stimulated PBMCs from allergic asthma patients and healthy subjects with and without confirmed acute respiratory viral infection.

RESULTS

Using mouse models, we found that infection with RSV drives enhanced il33 mRNA expression in the mouse lung. Treatment with anti-il33 siRNA diminishes airway inflammation in the lungs (we found a decrease in the number of inflammatory cells in the lungs and in the severity of histopathological alterations) of mice with RSV-induced inflammation exacerbation, but do not influence viral load. Elevated level of the IL33 mRNA was detected in ex vivo stimulated blood lymphocytes of allergic asthmatics infected with respiratory viruses. RSV and rhinovirus were the most detected viruses in volunteers with symptoms of respiratory infection.

CONCLUSION

The present study provides additional evidence of the crucial role of the IL-33 in pathogenesis of RSV infection and virus-induced allergic bronchial asthma exacerbations.

IL-33/ST2 induces neutrophil-dependent reactive oxygen species production and mediates gout pain

Objective: Gout, induced by monosodium urate (MSU) crystal deposition in joint tissues, provokes severe pain and impacts life quality of patients. However, the mechanisms underlying gout pain are still incompletely understood.

Methods: We established a mouse gout model by intra-articularly injection of MSU crystals into the ankle joint of wild type and genetic knockout mice. RNA-Sequencing, in vivo molecular imaging, Ca²⁺ imaging, reactive oxygen species (ROS) generation, neutrophil influx and nocifensive behavioral assays, etc. were used.

Results: We found interleukin-33 (IL-33) was among the top up-regulated cytokines in the inflamed ankle. Neutralizing or genetic deletion of IL-33 or its receptor ST2 (suppression of tumorigenicity) significantly ameliorated pain hypersensitivities and inflammation. Mechanistically, IL-33 was largely released from infiltrated macrophages in inflamed ankle upon MSU stimulation. IL-33 promoted neutrophil influx and triggered neutrophil-dependent ROS production via ST2 during gout, which in turn, activated transient receptor potential ankyrin 1 (TRPA1) channel in dorsal root ganglion (DRG) neurons and produced nociception. Further, TRPA1 channel activity was significantly enhanced in DRG neurons that innervate the inflamed ankle via ST2 dependent mechanism, which results in exaggerated nociceptive response to endogenous ROS products during gout.

Conclusions: We demonstrated a previous unidentified role of IL-33/ST2 in mediating pain hypersensitivity and inflammation in a mouse gout model through promoting neutrophil-dependent ROS production and TRPA1 channel activation. Targeting IL-33/ST2 may represent a novel therapeutic approach to ameliorate gout pain and inflammation.

Blockade of IL-33 signalling attenuates osteoarthritis

Objectives

Osteoarthritis (OA) is the most common form of arthritis characterised by cartilage degradation, synovitis and pain. Disease modifying treatments for OA are not available. The critical unmet need is to find therapeutic targets to reduce both disease progression and pain. The cytokine IL‐33 and its receptor ST2 have been shown to play a role in immune and inflammatory diseases, but their role in osteoarthritis is unknown.

Methods

Non‐OA and OA human chondrocytes samples were examined for IL‐33 and ST2 expression. Novel inducible cartilage specific knockout mice (IL‐33^{Acan CreERT2}) and inducible fibroblast‐like synoviocyte knockout mice (IL‐33^{Col1a2 CreERT2}) were generated and subjected to an experimental OA model. In addition, wild‐type mice were intra‐articularly administered with either IL‐33‐ or ST2‐neutralising antibodies during experimental OA studies.

Results

IL‐33 and its receptor ST2 have increased expression in OA patients and a murine disease model. Administering recombinant IL‐33 increased OA and pain in vivo. Synovial fibroblast‐specific deletion of IL‐33 decreased synovitis but did not impact disease outcomes, whilst cartilage‐specific deletion of IL‐33 improved disease outcomes in vivo. Blocking IL‐33 signalling also reduced the release of cartilage‐degrading enzymes in human and mouse chondrocytes. Most importantly, we show the use of monoclonal antibodies against IL‐33 and ST2 attenuates both OA and pain in vivo.

Conclusion

Overall, our data reveal blockade of IL‐33 signalling as a viable therapeutic target for OA.

Soluble suppression of tumorigenicity-2 predicts pneumonia in patients with inhalation injury: Results of a pilot study

INTRODUCTION

Several mechanisms play a role in the development of pneumonia after inhalation injury. Our aim was to analyze whether higher concentrations of inflammatory markers or of biomarkers of epithelial injury are associated with a higher incidence of pneumonia in patients with inhalation injury.

MATERIAL AND METHODS

Secondary analysis of a single-center prospective observational cohort pilot study, performed over a two-year period (2015-2017) at the Burns Unit of the Plastic and Reconstructive Surgery Department of Vall d'Hebron University Hospital. All patients aged 18 with suspected inhalation injury undergoing admission to the Burns Unit were included. Plasma biomarkers of the lung epithelium (RAGE and SP-D), inflammation markers (IL6, IL8), and IL33, as well as soluble suppression of tumorigenicity-2 (sST2) levels, were measured within the first 24 h of admission.

RESULTS

Twenty-four patients with inhalation injury were included. Eight (33.3%) developed pneumonia after a median of 7 (4-8) days of hospital stay. Patients with pneumonia presented higher plasma concentrations of sST2 (2853 [2356-3351] ng/mL vs 1352 [865-1839] ng/mL; p < 0.001), IL33 (1.95 [1.31-2.59] pg/mL vs 1.26 [1.07-1.45] pg/mL; p = 0.002) and IL8 (325.7 [221.6-430.0] pg/mL vs 174.1 [95.2-253.0] pg/mL; p = 0.017) on day 1 of inclusion. Plasma sST2 concentration in the first 24 h demonstrated excellent diagnostic accuracy for predicting the occurrence of pneumonia in patients with smoke inhalation (AUROC 0.929 [95%CI 0.818-1.000]). A cutoff point of ≥2825 ng/mL for sST2 had a sensitivity of 75% and a specificity of 100%. The risk ratio of pneumonia in patients with sST2 ≥ 2825 ng/mL was 7.14 ([95% CI 1.56-32.61]; p = 0.016).

CONCLUSIONS

Plasma sST2 in the first 24 h of admission predicts the occurrence of pneumonia in patients with inhalation injury.

Pathogen-Associated Molecules from Gut Translocation Enhance Severity of Cecal Ligation and Puncture Sepsis in Iron-Overload β-Thalassemia Mice

Introduction

Systemic inflammation induced by gut translocation of lipopolysaccharide (LPS), a major component of Gram-negative bacteria, in thalassemia with iron-overload worsens sepsis. However, the impact of (1→3)-β-D-glucan (BG), a major fungal molecule, in iron-overload thalassemia is still unclear. Hence, the influence of BG was explored in 1) iron-overload mice with sepsis induced by cecal ligation and puncture (CLP) surgery; and 2) in bone marrow-derived macrophages (BMMs).

Methods

The heterozygous β-globin-deficient mice, Hbb^th3/+ mice, were used as representative thalassemia (TH) mice. Iron overload was generated by 6 months of oral iron administration before CLP surgery- induced sepsis in TH mice and wild-type (WT) mice. Additionally, BMMs from both mouse strains were used to explore the impact of BG.

Results

Without sepsis, iron-overload TH mice demonstrated more severe intestinal mucosal injury (gut leakage) with higher LPS and BG in serum, from gut translocation, when compared with WT mice. With CLP in iron-overload mice, sepsis severity in TH mice was more severe than WT as determined by survival analysis, organ injury (kidney and liver), bacteremia, endotoxemia, gut leakage (FITC-dextran) and serum BG. Activation by LPS plus BG (LPS+BG) in BMMs and in peripheral blood-derived neutrophils (both WT and TH cells) demonstrated more prominent cytokine production when compared with LPS activation alone. In parallel, LPS+BG also prominently induced genes expression of M1 macrophage polarization (iNOS, TNF-α and IL-1β) in both WT and TH cells in comparison with LPS activation alone. In addition, LPS+BG activated macrophage cytokine production was enhanced by a high dose of ferric ion (800 mM), more predominantly in TH macrophages compared with WT cells. Moreover, LPS+BG induced higher glycolysis activity with similar respiratory capacity in RAW264.7 (a macrophage cell line) compared with LPS activation alone. These data support an additive pro-inflammatory effect of BG upon LPS.

Conclusion

The enhanced-severity of sepsis in iron-overload TH mice was due to 1) increased LPS and BG in serum from iron-induced gut-mucosal injury; and 2) the pro-inflammatory amplification by ferric ion on LPS+BG activation.

Fibroblast-Derived IL33 Facilitates Breast Cancer Metastasis by Modifying the Immune Microenvironment and Driving Type 2 Immunity

Lungs are one of the main sites of breast cancer metastasis. The metastatic microenvironment is essential to facilitate growth of disseminated tumor cells. Cancer-associated fibroblasts (CAF) are prominent players in the microenvironment of breast cancer. However, their role in the formation of a permissive metastatic niche is unresolved. Here we show that IL33 is upregulated in metastases-associated fibroblasts in mouse models of spontaneous breast cancer metastasis and in patients with breast cancer with lung metastasis. Upregulation of IL33 instigated type 2 inflammation in the metastatic microenvironment and mediated recruitment of eosinophils, neutrophils, and inflammatory monocytes to lung metastases. Importantly, targeting of IL33 in vivo resulted in inhibition of lung metastasis and significant attenuation of immune cell recruitment and type 2 immunity. These findings demonstrate a key function of IL33 in facilitating lung metastatic relapse by modulating the immune microenvironment. Our study shows a novel interaction axis between CAF and immune cells and reveals the central role of CAF in establishing a hospitable inflammatory niche in lung metastasis. SIGNIFICANCE: This study elucidates a novel role for fibroblast-derived IL33 in facilitating breast cancer lung metastasis by modifying the immune microenvironment at the metastatic niche toward type 2 inflammation.

Glioma-derived IL-33 orchestrates an inflammatory brain tumor microenvironment that accelerates glioma progression

Despite a deeper molecular understanding, human glioblastoma remains one of the most treatment refractory and fatal cancers. It is known that the presence of macrophages and microglia impact glioblastoma tumorigenesis and prevent durable response. Herein we identify the dual function cytokine IL-33 as an orchestrator of the glioblastoma microenvironment that contributes to tumorigenesis. We find that IL-33 expression in a large subset of human glioma specimens and murine models correlates with increased tumor-associated macrophages/monocytes/microglia. In addition, nuclear and secreted functions of IL-33 regulate chemokines that collectively recruit and activate circulating and resident innate immune cells creating a pro-tumorigenic environment. Conversely, loss of nuclear IL-33 cripples recruitment, dramatically suppresses glioma growth, and increases survival. Our data supports the paradigm that recruitment and activation of immune cells, when instructed appropriately, offer a therapeutic strategy that switches the focus from the cancer cell alone to one that includes the normal host environment.

Astrocytes promote a protective immune response to brain Toxoplasma gondii infection via IL-33-ST2 signaling

It is of great interest to understand how invading pathogens are sensed within the brain, a tissue with unique challenges to mounting an immune response. The eukaryotic parasite Toxoplasma gondii colonizes the brain of its hosts, and initiates robust immune cell recruitment, but little is known about pattern recognition of T. gondii within brain tissue. The host damage signal IL-33 is one protein that has been implicated in control of chronic T. gondii infection, but, like many other pattern recognition pathways, IL-33 can signal peripherally, and the specific impact of IL-33 signaling within the brain is unclear. Here, we show that IL-33 is expressed by oligodendrocytes and astrocytes during T. gondii infection, is released locally into the cerebrospinal fluid of T. gondii-infected animals, and is required for control of infection. IL-33 signaling promotes chemokine expression within brain tissue and is required for the recruitment and/or maintenance of blood-derived anti-parasitic immune cells, including proliferating, IFN-γ-expressing T cells and iNOS-expressing monocytes. Importantly, we find that the beneficial effects of IL-33 during chronic infection are not a result of signaling on infiltrating immune cells, but rather on radio-resistant responders, and specifically, astrocytes. Mice with IL-33 receptor-deficient astrocytes fail to mount an adequate adaptive immune response in the CNS to control parasite burden-demonstrating, genetically, that astrocytes can directly respond to IL-33 in vivo. Together, these results indicate a brain-specific mechanism by which IL-33 is released locally, and sensed locally, to engage the peripheral immune system in controlling a pathogen.

Graft IL-33 regulates infiltrating macrophages to protect against chronic rejection

Alarmins, sequestered self-molecules containing damage-associated molecular patterns, are released during tissue injury to drive innate immune cell proinflammatory responses. Whether endogenous negative regulators controlling early immune responses are also released at the site of injury is poorly understood. Herein, we establish that the stromal cell-derived alarmin interleukin 33 (IL-33) is a local factor that directly restricts the proinflammatory capacity of graft-infiltrating macrophages early after transplantation. By assessing heart transplant recipient samples and using a mouse heart transplant model, we establish that IL-33 is upregulated in allografts to limit chronic rejection. Mouse cardiac transplants lacking IL-33 displayed dramatically accelerated vascular occlusion and subsequent fibrosis, which was not due to altered systemic immune responses. Instead, a lack of graft IL-33 caused local augmentation of proinflammatory iNOS+ macrophages that accelerated graft loss. IL-33 facilitated a metabolic program in macrophages associated with reparative and regulatory functions, and local delivery of IL-33 prevented the chronic rejection of IL-33-deficient cardiac transplants. Therefore, IL-33 represents what we believe is a novel regulatory alarmin in transplantation that limits chronic rejection by restraining the local activation of proinflammatory macrophages. The local delivery of IL-33 in extracellular matrix-based materials may be a promising biologic for chronic rejection prophylaxis.

A new dawn for eosinophils in the tumour microenvironment

Eosinophils are evolutionarily conserved, pleotropic cells that display key effector functions in allergic diseases, such as asthma. Nonetheless, eosinophils infiltrate multiple tumours and are equipped to regulate tumour progression either directly by interacting with tumour cells or indirectly by shaping the tumour microenvironment (TME). Eosinophils can readily respond to diverse stimuli and are capable of synthesizing and secreting a large range of molecules, including unique granule proteins that can potentially kill tumour cells. Alternatively, they can secrete pro-angiogenic and matrix-remodelling soluble mediators that could promote tumour growth. Herein, we aim to comprehensively outline basic eosinophil biology that is directly related to their activity in the TME. We discuss the mechanisms of eosinophil homing to the TME and examine their diverse pro-tumorigenic and antitumorigenic functions. Finally, we present emerging data regarding eosinophils as predictive biomarkers and effector cells in immunotherapy, especially in response to immune checkpoint blockade therapy, and highlight outstanding questions for future basic and clinical cancer research.

Interleukin-33 activates regulatory T cells to suppress innate γδ T cell responses in the lung

Foxp3⁺ regulatory T (T_reg) cells expressing the interleukin (IL)-33 receptor ST2 mediate tissue repair in response to IL-33. Whether T_reg cells also respond to the alarmin IL-33 to regulate specific aspects of the immune response is not known. Here we describe an unexpected function of ST2⁺ T_reg cells in suppressing the innate immune response in the lung to environmental allergens without altering the adaptive immune response. Following allergen exposure, ST2⁺ T_reg cells were activated by IL-33 to suppress IL-17-producing γδ T cells. ST2 signaling in T_reg cells induced Ebi3, a component of the heterodimeric cytokine IL-35 that was required for T_reg cell-mediated suppression of γδ T cells. This response resulted in fewer eosinophil-attracting chemokines and reduced eosinophil recruitment into the lung, which was beneficial to the host in reducing allergen-induced inflammation. Thus, we define a fundamental role for ST2⁺ T_reg cells in the lung as a negative regulator of the early innate γδ T cell response to mucosal injury.

High level of interleukin-33 in cancer cells and cancer-associated fibroblasts correlates with good prognosis and suppressed migration in cholangiocarcinoma

Interleukin 33 (IL-33) promotes cholangiocarcinoma (CCA) genesis in a mouse model, however, its function in human CCA has not been clearly understood. This study was aimed to investigate IL-33 level in CCA tissues and its clinicopathological correlations. The results revealed that IL-33 was found in both cancer cells and stromal cancer-associated fibroblast (CAFs) staining patterns which were divided into high (CH) and low level (CL) in cancer cells; and presence (FP) and absence (FA) in CAFs. Kaplan-Meier analysis showed that patients in the CL group were significantly correlated with a short 2-year survival time (P = 0.027). The CL/FP group had a shorter survival time compared to the other groups with statistical significance for 2-year (P = 0.030) and 5-year (P = 0.023) survivals. In contrast, CH/FP patients had significantly greater 2-year (P = 0.003) and 5-year (P = 0.003) survivals. Univariate and multivariate analysis confirmed that CL/FP was a significantly independent risk factor whereas CH/FP was a significant protective factor in CCA patients. High IL-33 expressing CCA cells had low migration, but they showed increased migration when IL-33 expression was knocked down. The low level of recombinant human IL-33 (rhIL-33) (0.002 - 2 ng/ml) could promote CCA cell migration, in contrast to the suppressive effect at a high dose (20 - 200 ng/ml). In conclusion, the combination of high IL-33 level in cancer cells and CAFs is a potentially good prognosis marker in CCA patients. The in vitro migration suppressive effect of IL-33 may be the potential mechanism supporting its role as a good prognostic marker in CCA patients. The obtained results strengthen IL-33 as a promising predictor and therapeutic target for CCA.

IL-33-ST2 axis regulates myeloid cell differentiation and activation enabling effective club cell regeneration

Evidence points to an indispensable function of macrophages in tissue regeneration, yet the underlying molecular mechanisms remain elusive. Here we demonstrate a protective function for the IL-33-ST2 axis in bronchial epithelial repair, and implicate ST2 in myeloid cell differentiation. ST2 deficiency in mice leads to reduced lung myeloid cell infiltration, abnormal alternatively activated macrophage (AAM) function, and impaired epithelial repair post naphthalene-induced injury. Reconstitution of wild type (WT) AAMs to ST2-deficient mice completely restores bronchial re-epithelialization. Central to this mechanism is the direct effect of IL-33-ST2 signaling on monocyte/macrophage differentiation, self-renewal and repairing ability, as evidenced by the downregulation of key pathways regulating myeloid cell cycle, maturation and regenerative function of the epithelial niche in ST2^−/− mice. Thus, the IL-33-ST2 axis controls epithelial niche regeneration by activating a large multi-cellular circuit, including monocyte differentiation into competent repairing AAMs, as well as group-2 innate lymphoid cell (ILC2)-mediated AAM activation.

Signaling of IL-33 via its receptor, ST2, has been implicated in macrophage function in tissue repair. Here the authors show, using genetic mouse models and single-cell transcriptomic data, that the IL-33/ST2 axis regulates both ILC2-derived IL-13 and macrophage differentiation/reparative function required for club cell regeneration.