IL33: Roles in Allergic Inflammation and Therapeutic Perspectives

Emerging Roles of Platelets in Allergic Asthma

Allergic asthma is a complex chronic inflammatory disease of the airways, driven by Th2 immune responses and characterized by eosinophilic pulmonary inflammation, airway hyperresponsiveness, excessive mucus production, and airway remodeling. Overwhelming evidence from studies in animal models and allergic asthmatic patients suggests that platelets are aberrantly activated and recruited to the lungs. It has been established that platelets can interact with other immune cells and secrete various biochemical mediators to promote allergic sensitization and airway inflammatory response, and platelet deficiency may alleviate the pathological features and symptoms of allergic asthma. However, the comprehensive roles of platelets in allergic asthma have not been fully clarified, leaving attempts to treat allergic asthma with antiplatelet agents questionable. In this review, we summarize the role of platelet activation and pulmonary accumulation in allergic asthma; emphasis is placed on the different interactions between platelets with crucial immune cell types and the contribution of platelet-derived mediators in this context. Furthermore, clinical antiplatelet approaches to treat allergic asthma are discussed. This review provides a clearer understanding of the roles of platelets in the pathogenesis of allergic asthma and could be informative in the development of novel strategies for the treatment of allergic asthma.

The Interleukin-1 (IL-1) Superfamily Cytokines and Their Single Nucleotide Polymorphisms (SNPs)

Interleukins (ILs)—which are important members of cytokines—consist of a vast group of molecules, including a wide range of immune mediators that contribute to the immunological responses of many cells and tissues. ILs are immune-glycoproteins, which directly contribute to the growth, activation, adhesion, differentiation, migration, proliferation, and maturation of immune cells; and subsequently, they are involved in the pro and anti-inflammatory responses of the body, by their interaction with a wide range of receptors. Due to the importance of immune system in different organisms, the genes belonging to immune elements, such as ILs, have been studied vigorously. The results of recent investigations showed that the genes pertaining to the immune system undergo progressive evolution with a constant rate. The occurrence of any mutation or polymorphism in IL genes may result in substantial changes in their biology and function and may be associated with a wide range of diseases and disorders. Among these abnormalities, single nucleotide polymorphisms (SNPs) can represent as important disruptive factors. The present review aims at concisely summarizing the current knowledge available on the occurrence, properties, role, and biological consequences of SNPs within the IL-1 family members.

IL-33 regulates M1/M2 chemokine expression via mitochondrial redox-related mitophagy in human monocytes

Interleukin (IL)-33 is an epithelial-derived cytokine that enhances T helper (Th) 2 responses. Allergens and other agents induce IL-33 in asthma. Excessive production of reactive oxygen species (ROS) leads to airway inflammation. Mitophagy is the selective degradation of mitochondria by autophagy and often occurs in defective mitochondria, followed by ROS production. In the present study, we examined the effects of IL-33 on ROS production and mitophagy in human monocytes, and the detailed mechanisms were investigated. Human monocyte cell line THP-1 was pretreated with different concentrations of IL-33. ROS production was measured by flow cytometry. Mitochondrial involvement and the mitophagy and intercellular pathway activation were evaluated by quantitative real-time PCR, western blotting, and confocal microscopy, and cytokine/chemokine concentrations were detected by ELISA. The data showed that IL-33 alone could induce ROS expression in THP-1 cells. The expression of complex II and V mRNA was increased in the presence of IL-33. The mitophagy-related proteins PINK1, Parkin, and LC3 were regulated by IL-33 through the AMPK pathway. IL-33 significantly decreased M1-related cytokines CXCL-10 and TNF-α production and significantly increased M2-related cytokine CCL-22 production. In conclusion, IL-33 induces ROS production and subsequently influences mitophagy through AMPK activation, altering the macrophage-polarization phenotype of monocytes.

Inhibitory Effects of Euscaphic Acid in the Atopic Dermatitis Model by Reducing Skin Inflammation and Intense Pruritus

Atopic dermatitis (AD) is a complex and multifactorial skin disease characterized by skin inflammation and intense pruritus. There are many commercially available treatments such as topical corticosteroids and immunosuppressants to treat of AD, but their effectiveness is limited, and frequent use of these treatments can cause serious side effects. Therefore, the development of new therapeutic agents is necessary for the treatment of AD. Hence, an alternative agent that was derived from natural products that are effective and safe for AD treatment was investigated using experimental models. The biological activity of euscaphic acid has anti-inflammatory, anticoagulant, and antioxidant effects. Despite the various biomedical properties of euscaphic acid, its therapeutic effects on AD have not been well studied. In this study, we investigated the effects of euscaphic acid on skin inflammation and pruritus in AD mouse model. The effects of euscaphic acid were investigated in activated human epidermal keratinocytes and leukemia T lymphoblast cell lines, and Dermatophagoides farina extract and 2,4-dinitrochlorobenzene-induced AD mouse model. Euscaphic acid ameliorated AD properties, such as the expression of inflammatory cytokines and activation of transcription factors. In addition, euscaphic acid reduced critical factors for pruritus such as immunoglobulin E hyperproduction, mast cell invasion, and interleukin-33 expression. Taken together, euscaphic acid could be a potent therapeutic agent for the treatment of AD.

IL-37 regulates allergic inflammation by counterbalancing pro-inflammatory IL-1 and IL-33

BACKGROUND

Children with asthma have impaired production of interleukin (IL) 37; in mice, IL-37 reduces hallmarks of experimental allergic asthma (EAA). However, it remains unclear how IL-37 exerts its inhibitory properties in asthma. This study aimed to identify the mechanism(s) by which IL-37 controls allergic inflammation.

METHODS

IL-37 target cells were identified by single-cell RNA-seq of IL-1R5 and IL-1R8. Airway tissues were isolated by laser-capture microdissection and examined by microarray-based gene expression analysis. Mononuclear cells (MNC) and airway epithelial cells (AECs) were isolated and stimulated with allergen, IL-1β, or IL-33 together with recombinant human (rh) IL-37. Wild-type, IL-1R1- and IL-33-deficient mice with EAA were treated with rhIL-37. IL-1β, IL-33, and IL-37 levels were determined in sputum and nasal secretions from adult asthma patients without glucocorticoid therapy.

RESULTS

IL-37 target cells included AECs, T cells, and dendritic cells. In mice with EAA, rhIL-37 led to differential expression of >90 genes induced by IL-1β and IL-33. rhIL-37 reduced production of Th2 cytokines in allergen-activated MNCs from wild-type but not from IL-1R1-deficient mice and inhibited IL-33-induced Th2 cytokine release. Furthermore, rhIL-37 attenuated IL-1β- and IL-33-induced pro-inflammatory mediator expression in murine AEC cultures. In contrast to wild-type mice, hIL-37 had no effect on EAA in IL-1R1- or IL-33-deficient mice. We also observed that expression/production ratios of both IL-1β and IL-33 to IL-37 were dramatically increased in asthma patients compared to healthy controls.

CONCLUSION

IL-37 downregulates allergic airway inflammation by counterbalancing the disease-amplifying effects of IL-1β and IL-33.

Evaluating the glucagon-like peptide-1 receptor in managing asthma

PURPOSE OF REVIEW

The aim of this study was to discuss the role of glucagon-like peptide-1 (GLP-1) receptor signalling in reducing lung inflammation and potential use for GLP-1 receptor agonists (GLP-1RAs) in management of asthma.

RECENT FINDINGS

Although GLP-1RA are currently used for the treatment of type 2 diabetes (T2D) and weight loss in obesity, there is much interest in expanding the indications for use in other diseases, including inflammatory pulmonary disease. In animal models of both acute and chronic pulmonary disease, use of GLP-1RA reduces airway inflammation, obstruction and fibrosis. In particular, GLP-1 receptor (GLP-1R) signalling seems to inhibit allergen-induced type 2 inflammation, making it an attractive agent for asthma. Results are especially promising in disease processes with disturbed metabolic regulation, such as T2D or metabolic syndrome. Retrospective clinical studies demonstrate promising evidence for the use of GLP-1RAs in comorbid diabetes and asthma, although prospective human studies are limited.

SUMMARY

Here, we discuss the biology of GLP-1 and GLP-1R signalling, review the preclinical and mechanistic evidence for how GLP-1R signalling may reduce pulmonary inflammation, and summarize recent and upcoming clinical studies. Ultimately, targeting GLP-1R signalling may represent a novel approach for asthma therapy that is glucocorticoid sparing and possibly disease modifying.

Sex-Specific Differences in Resolution of Airway Inflammation in Fat-1 Transgenic Mice Following Repetitive Agricultural Dust Exposure

In agriculture industries, workers are at increased risk for developing pulmonary diseases due to inhalation of agricultural dusts, particularly when working in enclosed confinement facilities. Agricultural dusts inhalation leads to unresolved airway inflammation that precedes the development and progression of lung disease. We have previously shown beneficial effects of the omega-3 polyunsaturated fatty acid (ω-3 PUFA) DHA in protecting against the negative inflammatory effects of repetitive dust exposure in the lung. Dietary manipulation of pulmonary disease risk is an attractive and timely approach given the contribution of an increased ω-6 to ω-3 PUFA ratio to low grade inflammation and chronic disease in the Western diet. To prevent any confounding factors that comes with dietary supplementation of ω-3 PUFA (different sources, purity, dose, and duration), we employed a Fat-1 transgenic mouse model that convert ω-6 PUFA to ω-3 PUFA, leading to a tissue ω-6 to ω-3 PUFA ratio of approximately 1:1. Building on our initial findings, we hypothesized that attaining elevated tissue levels of ω-3 PUFA would attenuate agricultural dust-induced lung inflammation and its resolution. To test this hypothesis, we compared wild-type (WT) and Fat-1 transgenic mice in their response to aqueous extracts of agricultural dust (DE). We also used a soluble epoxide hydrolase inhibitor (sEH) to potentiate the effects of ω-3 PUFA, since sEH inhibitors have been shown to stabilize the anti-inflammatory P450 metabolites derived from both ω-3 and ω-6 PUFA and promote generation of specialized pro-resolving lipid mediators from ω-3 PUFA. Over a three-week period, mice were exposed to a total of 15 intranasal instillations of DE obtained from swine confinement buildings in the Midwest. We observed genotype and sex-specific differences between the WT vs. Fat-1 transgenic mice in response to repetitive dust exposure, where three-way ANOVA revealed significant main effects of treatment, genotype, and sex. Also, Fat-1 transgenic mice displayed reduced lymphoid aggregates in the lung following DE exposure as compared to WT animals exposed to DE, suggesting improved resilience to the DE-induced inflammatory effects. Overall, our data implicate a protective role of ω-3 FA in the lung following repetitive dust exposure.

Unravelling the therapeutic potential of IL-33 for atrophic AMD

Age-related macular degeneration (AMD), a degenerative disease affecting the retinal pigment epithelium (RPE) and photoreceptors in the macula, is the leading cause of central blindness in the elderly. AMD progresses to advanced stages of the disease, atrophic AMD (aAMD), or in 15% of cases "wet" or neovascular AMD (nAMD), associated with substantial vision loss. Whilst there has been advancement in therapies treating nAMD, to date, there are no licenced effective treatments for the 85% affected by aAMD, with disease managed by changes to diet, vitamin supplements, and regular monitoring. AMD has a complex pathogenesis, involving highly integrated and common age-related disease pathways, including dysregulated complement/inflammation, impaired autophagy, and oxidative stress. The intricacy of AMD pathogenesis makes therapeutic development challenging and identifying a target that combats the converging disease pathways is essential to provide a globally effective treatment. Interleukin-33 is a cytokine, classically known for the proinflammatory role it plays in allergic disease. Recent evidence across degenerative and inflammatory disease conditions reveals a diverse immune-modulatory role for IL-33, with promising therapeutic potential. Here, we will review IL-33 function in disease and discuss the future potential for this homeostatic cytokine in treating AMD.

Inhalant Mammal-Derived Lipocalin Allergens and the Innate Immunity

A major part of important mammalian respiratory allergens belongs to the lipocalin family of proteins. By this time, 19 respiratory mammalian lipocalin allergens have been registered in the WHO/IUIS Allergen Nomenclature Database. Originally, lipocalins, small extracellular proteins (molecular mass ca. 20 kDa), were characterized as transport proteins but they are currently known to exert a variety of biological functions. The three-dimensional structure of lipocalins is well-preserved, and lipocalin allergens can exhibit high amino acid identities, in several cases more than 50%. Lipocalins contain an internal ligand-binding site where they can harbor small principally hydrophobic molecules. Another characteristic feature is their capacity to bind to specific cell-surface receptors. In all, the physicochemical properties of lipocalin allergens do not offer any straightforward explanations for their allergenicity. Allergic sensitization begins at epithelial barriers where diverse insults through pattern recognition receptors awaken innate immunity. This front-line response is manifested by epithelial barrier-associated cytokines which together with other components of immunity can initiate the sensitization process. In the following, the crucial factor in allergic sensitization is interleukin (IL)-4 which is needed for stabilizing and promoting the type 2 immune response. The source for IL-4 has been searched widely. Candidates for it may be non-professional antigen-presenting cells, such as basophils or mast cells, as well as CD4+ T cells. The synthesis of IL-4 by CD4+ T cells requires T cell receptor engagement, i.e., the recognition of allergen peptides, which also provides the specificity for sensitization. Lipocalin and innate immunity-associated cell-surface receptors are implicated in facilitating the access of lipocalin allergens into the immune system. However, the significance of this for allergic sensitization is unclear, as the recognition by these receptors has been found to produce conflicting results. As to potential adjuvants associated with mammalian lipocalin allergens, the hydrophobic ligands transported by lipocalins have not been reported to enhance sensitization while it is justified to suppose that lipopolysaccharide plays a role in it. Taken together, type 2 immunity to lipocalin allergens appears to be a harmful immune response resulting from a combination of signals involving both the innate and adaptive immunities.

Overcoming drug delivery barriers and challenges in topical therapy of atopic dermatitis: A nanotechnological perspective

Atopic dermatitis (AD) is an inflammatory disorder centered around loss of epidermal barrier function, and T helper 2 (Th2) immune responses. The current understanding of disease heterogeneity and complexity, limits the rational use of existing topical, systemic therapeutic agents, but paves way for development of advanced therapeutic agents. Additionally, advanced nanocarriers that deliver therapeutics to target cells, seem to offer a promising strategy, to overcome intrinsic limitations and challenges of conventional, and traditional drug delivery systems. Ever-evolving understanding of molecular target sites and complex pathophysiology, adverse effects of current therapeutic options, inefficient disease recapitulation by existing animal models are some of the challenges that we face. Also, despite limited success in market translatibility, nanocarriers have demonstrated excellent preclinical results and have been extensively studied for AD. Detailed research on behavior of nanocarriers in different patients and tailored therapy to account for phenotypic variability of the disease are the new research avenues that we look forward to.

Biological Role, Mechanism of Action and the Importance of Interleukins in Kidney Diseases

Each year, the number of patients who are diagnosed with kidney disease too late is increasing, which leads to permanent renal failure. This growing problem affects people of every age, sex and origin, and its full etiopathogenesis is not fully understood, although the involvement of genetic susceptibility, infections, immune disorders or high blood pressure is suggested. Difficulties in making a correct and quick diagnosis are caused by the lack of research on early molecular markers, as well as educational and preventive activities among the public, which leads to the late detection of kidney diseases. An important role in the homeostasis and disease progression, including kidney diseases, is attributed to interleukins, which perform several biological functions and interact with other cells and tissues of the body. The aim of this article was to systematize the knowledge about the biological functions performed by interleukins in humans and their involvement in kidney diseases development. In our work, we took into account the role of interleukins in acute and chronic kidney disease and kidney transplantation.

Vulnerability to acid reflux of the airway epithelium in severe asthma

BACKGROUND

Severe asthma is associated with multiple co-morbidities, including gastro-oesophageal reflux disease (GORD) which can contribute to exacerbation frequency and poor quality of life. Since epithelial dysfunction is an important feature in asthma, we hypothesised that in severe asthma the bronchial epithelium is more susceptible to the effects of acid reflux.

METHODS

We developed an in vitro model of GORD using differentiated bronchial epithelial cells (BECs) from normal or severe asthmatic donors exposed to a combination of pepsin, acid pH, and bile acids using a multiple challenge protocol (MCP-PAB). We also analysed bronchial biopsies and undertook RNA-sequencing of bronchial brushings from controls and severe asthmatics without or with GORD.

RESULTS

Exposure of BECs to the MCP-PAB caused structural disruption, increased permeability, IL-33 expression, inflammatory mediator release and changes in gene expression for multiple biological processes. Cultures from severe asthmatics were significantly more affected than those from healthy donors. Analysis of bronchial biopsies confirmed increased IL-33 expression in severe asthmatics with GORD. RNA-sequencing of bronchial brushings from this group identified 15 of the top 37 dysregulated genes found in MCP-PAB treated BECs, including genes involved in oxidative stress responses.

CONCLUSIONS

By affecting epithelial permeability, GORD may increase exposure of the airway submucosa to allergens and pathogens, resulting in increased risk of inflammation and exacerbations.

CLINICAL IMPLICATION

These results suggest the need for research into alternative therapeutic management of GORD in severe asthma.

Association of IL33, IL1RL1, IL1RAP Polymorphisms and Asthma in Chinese Han Children

Background: Genome-wide association studies have identified interleukin 33 (IL33), interleukin 1 receptor-like 1 (IL1RL1), interleukin 1 receptor accessory protein (IL1RAP) as asthma susceptibility loci in Europeans. IL33, IL1RL1, and IL1RAP constitute a ligand-receptor complex.

Objective: We analyzed associations of asthma susceptibility, eosinophilic airway inflammation, and response to inhaled corticosteroid (ICS) with single nucleotide polymorphisms (SNPs) of 3 genes encoding IL33, IL1RL1, and its coreceptor IL1RAP in Chinese Han nationality children.

Methods: A total of 153 non-asthmatic children and 265 asthmatic children who visited the Xiangya Hospital between September 2015 and August 2019 were recruited for this study. Pulmonary function tests, peripheral blood eosinophil counts (PBEC), and fractional exhaled nitric oxide (FeNO) tests were performed before treatment, and 3 months after treatment. Each participant’s DNA was extracted from the peripheral blood, and a Mass ARRAY system was used to genotype the SNPs.

Results: The T allele of rs4742170 in IL33 was associated with a risk of higher FeNO at baseline, and no improvement in FeNO and airway hyperresponsiveness was found after ICS treatment. The A allele of rs10208293 and C allele of rs13424006 in IL1RL1 both were associated with lower susceptibility to asthma and lower FeNO. The TT genotype of rs1420101 and AA genotype of rs4142132 in IL1RL1 were associated with a greater probability of improvement in PBEC after ICS treatment.

Conclusion: IL33-IL1RL1-IL1RAP complex polymorphisms are associated with childhood asthma susceptibility, eosinophilic airway inflammation, and ICS response in Chinese Han children in Hunan. We speculate that IL33-IL1RL1-IL1RAP complex polymorphisms affect the development of asthma, airway inflammation, and subsequent ICS response in childhood.

Effects of cytokine signaling inhibition on inflammation-driven tissue remodeling

Fibrosis is a common condition that can affect all body tissues, driven by unresolved tissue inflammation and resulting in tissue dysfunction and organ failure that could ultimately lead to death. A myriad of factors are thought to contribute to fibrosis and, although it is relatively common, treatments focusing on reversing fibrosis are few and far between. The process of fibrosis involves a variety of cell types, including epithelial, endothelial, and mesenchymal cells, as well as immune cells, which have been shown to produce pro-fibrotic cytokines. Advances in our understanding of the molecular mechanisms of inflammation-driven tissue fibrosis and scar formation have led to the development of targeted therapeutics aiming to prevent, delay, or even reverse tissue fibrosis. In this review, we describe promising targets and agents in development, with a specific focus on cytokines that have been well-described to play a role in fibrosis: IL-1, TNF-α, IL-6, and TGF-β. An array of small molecule inhibitors, natural compounds, and biologics have been assessed in vivo, in vivo, and in the clinic, demonstrating the capacity to either directly interfere with pro-fibrotic pathways or to block intracellular enzymes that control fibrosis-related signaling pathways. Targeting pro-fibrotic cytokines, potentially via a multi-pronged approach, holds promise for the treatment of inflammation-driven fibrotic diseases in numerous organs. Despite the complexity of the interplay of cytokines in fibrotic tissues, the breadth of the currently ongoing research targeting cytokines suggests that these may hold the key to mitigating tissue fibrosis and reducing organ damage in the future.

A Closer Look at Dexamethasone and the SARS-CoV-2-Induced Cytokine Storm: In Silico Insights of the First Life-Saving COVID-19 Drug

The term cytokine storm refers to an uncontrolled overproduction of soluble inflammatory markers known as cytokines and chemokines. Autoimmune destruction of the lungs triggered by the release of these inflammatory markers often induces acute respiratory distress syndrome (ARDS). ARDS is an emergency condition with a high mortality rate in COVID-19 patients. Dexamethasone is the first repurposed corticosteroid with life-saving efficacy in patients with severe SARS-CoV-2 infection. Dexamethasone has traditionally been known to suppress the production of inflammatory markers at the transcriptional level, but its role as a direct therapeutic to neutralize cytokines, chemokines, their receptors, and functionally critical SARS-CoV-2 proteins has not yet been explored. Herein, we demonstrated that dexamethasone binds with high affinity to interlukin-1 (IL-1), IL-6, IL-8, IL-12, IL-21, INF2, TGFβ-1, INF-γ, CXCL8, some of the receptors, IL-1R, IL-21R, IFNGR, INFAR, IL-6αR-gp130, ST2 and the SARS-CoV-2 protein NSP macro X, and 3CLpro, forming stable drug–protein complexes. Our work implied that dexamethasone has the potential to directly neutralize inflammatory markers, further supporting its life-saving potential in patients with severe manifestations of COVID-19.

IL-1β Promotes Expansion of IL-33+ Lung Epithelial Stem Cells Following RSV Infection During Infancy

Respiratory syncytial virus (RSV)-induced immunopathogenesis and disease severity in neonatal mice and human infants have been related to elevated pulmonary IL-33. Thus, targeting IL-33 has been suggested as a potential therapy for respiratory viral infections. Yet, the regulatory mechanisms on IL-33 during early life remain unclear. Here, using a neonatal mouse model of RSV, we demonstrate that IL-1β positively regulates but is not required for RSV-induced expression of pulmonary IL-33 in neonatal mice early after the initial infection. Exogenous IL-1β upregulates RSV-induced IL-33 expression by promoting the proliferation of IL-33pos lung epithelial stem/progenitor cells (EpiSPC). These cells are exclusively detected in RSV-infected neonatal rather than adult mice, partially explaining the IL-1β-independent IL-33 expression in RSV-infected adult mice. Furthermore, IL-1β aggravates IL-33 mediated Th2 biased immunopathogenesis upon reinfection. Collectively, our study demonstrates that IL-1β exacerbates IL-33 mediated RSV immunopathogenesis by promoting the proliferation of IL-33pos EpiSPC in early life.

The Pathology of Type 2 Inflammation-Associated Itch in Atopic Dermatitis

Accumulated evidence on type 2 inflammation-associated itch in atopic dermatitis has recently been reported. Crosstalk between the immune and nervous systems (neuroimmune interactions) is prominent in atopic dermatitis research, particularly regarding itch and inflammation. A comprehensive understanding of bidirectional neuroimmune interactions will provide insights into the pathogenesis of itch and its treatment. There is currently no agreed cure for itch in atopic dermatitis; however, increasing numbers of novel and targeted biologic agents have potential for its management and are in the advanced stages of clinical trials. In this review, we summarize and discuss advances in our understanding of type 2 inflammation-associated itch and implications for its management and treatment in patients with atopic dermatitis.

Heme Peroxidases at Unperturbed and Inflamed Mucous Surfaces

In our organism, mucous surfaces are important boundaries against the environmental milieu with defined fluxes of metabolites through these surfaces and specific rules for defense reactions. Major mucous surfaces are formed by epithelia of the respiratory system and the digestive tract. The heme peroxidases lactoperoxidase (LPO), myeloperoxidase (MPO), and eosinophil peroxidase (EPO) contribute to immune protection at epithelial surfaces and in secretions. Whereas LPO is secreted from epithelial cells and maintains microbes in surface linings on low level, MPO and EPO are released from recruited neutrophils and eosinophils, respectively, at inflamed mucous surfaces. Activated heme peroxidases are able to oxidize (pseudo)halides to hypohalous acids and hypothiocyanite. These products are involved in the defense against pathogens, but can also contribute to cell and tissue damage under pathological conditions. This review highlights the beneficial and harmful functions of LPO, MPO, and EPO at unperturbed and inflamed mucous surfaces. Among the disorders, special attention is directed to cystic fibrosis and allergic reactions.

Biomarkers in the management of acute heart failure: state of the art and role in COVID-19 era

Acute heart failure (AHF) affects millions of people worldwide, and it is a potentially life‐threatening condition for which the cardiologist is more often brought into play. It is crucial to rapidly identify, among patients presenting with dyspnoea, those with AHF and to accurately stratify their risk, in order to define the appropriate setting of care, especially nowadays due to the coronavirus disease 2019 (COVID‐19) outbreak. Furthermore, with physical examination being limited by personal protective equipment, the use of new alternative diagnostic and prognostic tools could be of extreme importance. In this regard, usage of biomarkers, especially when combined (a multimarker approach) is beneficial for establishment of an accurate diagnosis, risk stratification and post‐discharge monitoring. This review highlights the use of both traditional biomarkers such as natriuretic peptides (NP) and troponin, and emerging biomarkers such as soluble suppression of tumourigenicity (sST2) and galectin‐3 (Gal‐3), from patients' emergency admission to discharge and follow‐up, to improve risk stratification and outcomes in terms of mortality and rehospitalization.

Biotite-Calx Based Traditional Indian Medicine Sahastraputi-Abhrak-Bhasma Prophylactically Mitigates Allergic Airway Inflammation in a Mouse Model of Asthma by Amending Cytokine Responses

Purpose

Asthma is a heterogeneous airway inflammatory disease with limited therapeutic options. Traditional medicine is extensively used for treating various ailments including asthma. Sahastraputi-Abhrak-Bhasma (SPAB) is a biotite-calx based Indian medicine.

Methods

We have tested for the anti-inflammatory and anti-asthmatic properties of SPAB, using a mouse model of ovalbumin-induced allergic asthma in-vivo and cell-based assays in-vitro. Histological analysis, qPCR and ELISA were performed to assess the pathology. SEM, EDX and XRD-analysis were performed to characterize the SPAB particles.

Results

SEM, EDX and XRD-analysis identified the presence of SPAB particle of 100 nm–~1µm diameter and contains annite-1M, aluminium silicate, kyanite, aluminium oxide, magnesium silicate, and maghemite in the samples. Ova-challenge resulted in severe inflammatory responses, airway remodelling and increased oxidative burden in lungs. Importantly, prophylactic treatment with SPAB significantly attenuated allergen induced leukocyte infiltration specifically eosinophils, lymphocytes, macrophages and neutrophils in BALF. Ova-induced mucus hypersecretion, peri-bronchial collagen deposition, inflammatory cell infiltration and bronchial epithelial thickening were significantly abrogated upon SPAB treatment. qPCR and ELISA analysis identified that allergen induced increases in IL-5, IL-13, IL-33, IFN-γ and IL-1β cytokines mRNA in whole lungs and the levels of IL-6, IL-1β and TNF-α proteins in BALF were significantly attenuated upon oral SPAB treatment. SPAB restored allergen induced decreases in anti-oxidant markers in lungs. In-vitro, SPAB attenuated the secretion of IL-6, and TNF-α from human bronchial epithelial cells and modestly inhibited NF-kB/AP-1 pathway in HEK cells.

Conclusion

Taken together, our results experimentally validated the prophylactic ameliorative potential of the Indian classical medicine Sahastraputi-Abhrak-Bhasma against asthma associated airway inflammation.

IL-33 signaling in sensory neurons promotes dry skin itch

BACKGROUND

Chronic pruritus, or itch, is common and debilitating, but the neuroimmune mechanisms that drive chronic itch are only starting to be elucidated. Recent studies demonstrate that the IL-33 receptor (IL-33R) is expressed by sensory neurons. However, whether sensory neuron-restricted activity of IL-33 is necessary for chronic itch remains poorly understood.

OBJECTIVES

We sought to determine if IL-33 signaling in sensory neurons is critical for the development of chronic itch in 2 divergent pruritic disease models.

METHODS

Plasma levels of IL-33 were assessed in patients with atopic dermatitis (AD) and chronic pruritus of unknown origin (CPUO). Mice were generated to conditionally delete IL-33R from sensory neurons. The contribution of neuronal IL-33R signaling to chronic itch development was tested in mouse models that recapitulate key pathologic features of AD and CPUO, respectively.

RESULTS

IL-33 was elevated in both AD and CPUO as well as their respective mouse models. While neuron-restricted IL-33R signaling was dispensable for itch in AD-like disease, it was required for the development of dry skin itch in a mouse model that mirrors key aspects of CPUO pathology.

CONCLUSIONS

These data highlight how IL-33 may be a predominant mediator of itch in certain contexts, depending on the tissue microenvironment. Further, this study provides insight into future therapeutic strategies targeting the IL-33 pathway for chronic itch.

Role of IL-33 receptor (ST2) deletion in diaphragm contractile and mitochondrial function in the Sugen5416/hypoxia model of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vasculature that leads to right ventricular failure. Skeletal muscle maladaptations limit physical activity and may contribute to disease progression. The role of alarmin/inflammatory signaling in PAH respiratory muscle dysfunction is unknown. We hypothesized that diaphragm mitochondrial and contractile functions are impaired in SU5416/hypoxia-induced pulmonary hypertension due to increased systemic IL-33 signaling. We induced pulmonary hypertension in adult C57Bl/6 J (WT) and ST2 (IL1RL1) gene ablated mice by SU5416/hypoxia (SuHx). We measured diaphragm fiber mitochondrial respiration, inflammatory markers, and contractile function ex vivo. SuHx reduced coupled and uncoupled permeabilized myofiber respiration by ∼40 %. During coupled respiration with complex I substrates, ST2^-/- attenuated SuHx inhibition of mitochondrial respiration (genotype × treatment interaction F[1,67] = 3.3, p = 0.07, η² = 0.04). Flux control ratio and coupling efficiency were not affected by SuHx or genotype. A higher substrate control ratio for succinate was observed in SuHx fibers and attenuated in ST2^-/- fibers (F[1,67] = 5.3, p < 0.05, η² = 0.07). Diaphragm TNFα, but not IL-33 or NFkB, was increased in SuHx vs. DMSO in both genotypes (F[1,43] = 4.7, p < 0.05, η² = 0.1). Diaphragm force-frequency relationships were right-shifted in SuHx vs. WT (F[3,440] = 8.4, p < 0.05, η² = 0.0025). There was no effect of ST2^-/- on the force-frequency relationship. Force decay during a fatigue protocol at 100 Hz, but not at 40 Hz, was attenuated by SuHx vs. DMSO in both genotypes (F[1,41] = 5.6, p < 0.05, η² = 0.11). SuHx mice exhibit a modest compensation in diaphragm contractility and mitochondrial dysfunction during coupled respiration; the latter partially regulated through ST2 signaling.

The role of IL-17, IL-23 and IL-31, IL-33 in allergic skin diseases

PURPOSE OF REVIEW

Allergic skin diseases such as urticaria, atopic dermatitis and allergic contact dermatitis are among the most common skin diseases with severe socioeconomic consequences. The pathogenesis of allergic skin diseases is complex. This review provides an overview of cytocines IL-17, IL-23, IL-31 and IL-33.

RECENT FINDINGS

Current research results show a variety of immunological processes in the pathogenesis of the allergic skin diseases, including the role of cytokines. In addition to the Th1 and Th2 immune response, the immune response via Th17 is becoming increasingly important in allergic skin diseases but also the cytokines IL-23, IL-31 and IL-33 have been discussed in the literature recently. Different cytokines promote in a kind of orchestra the different symptoms seen in the different allergic skin diseases, including pruritus, dermatitis, mast cell mediator release and inflammation.

SUMMARY

We are still in the early stages of understanding pathophysiology of allergic skin diseases and the role of various cytokines in the immune system. With the development of targeted antibodies against the proinflammatory cytokines, the variety of normal therapeutic options can be expected to evolve.

P2X Receptor-Dependent Modulation of Mast Cell and Glial Cell Activities in Neuroinflammation

Localisation of mast cells (MCs) at the abluminal side of blood vessels in the brain favours their interaction with glial cells, neurons, and endothelial cells, resulting in the activation of these cells and the release of pro-inflammatory mediators. In turn, stimulation of glial cells, such as microglia, astrocytes, and oligodendrocytes may result in the modulation of MC activities. MCs, microglia, astrocytes, and oligodendrocytes all express P2X receptors (P2XRs) family members that are selectively engaged by ATP. As increased concentrations of extracellular adenosine 5′-triphosphate (ATP) are present in the brain in neuropathological conditions, P2XR activation in MCs and glial cells contributes to the control of their communication and amplification of the inflammatory response. In this review we discuss P2XR-mediated MC activation, its bi-directional effect on microglia, astrocytes and oligodendrocytes and role in neuroinflammation.

Pediococcus Pentosaceus from the Sweet Potato Fermented Ger-Minated Brown Rice Can Inhibit Type I Hypersensitivity in RBL-2H3 Cell and BALB/c Mice Models

In this study, the effect of GBR fermented with the Pediococcus pentosaceus SP024 strain on IgE/Ag mediated passive cutaneous anaphylaxis (PCA) was investigated. Protocatechuic acid and trans-ferulic acid levels in GBR-SP024 increased more than those in unfermented GBR, respec-tively. The inhibitory activity of GBR-SP024 on β-hexosaminidase release and the level of proin-flammatory cytokine mRNA expression (tumor necrosis factor-α (TNF-α) and interleukin 4 (IL-4)) was observed in IgE/Ag-stimulated RBL-2H3 cells. Western blot analysis showed that GBR-SP024 significantly inhibited the phosphorylation of the linker for activation of T cell (LAT) and nuclear factor-κB (NF-κB) in IgE/Ag-stimulated RBL-2H3 cells. Further, we investigated the anti-allergic effect of GBR-SP024 using PCA murine model. The number of infiltrated immune cells and degranulated mast cells in GBR-SP024 treated dermis was lower than that in the GBR-treated mice. In addition, mRNA expression of 5-lipoxygenase (5-LOX) in the dermis of ear tissue declined in the GBR-SP024–treated group, compared to that in the GBR group. GBR-SP024 was also more effective than GBR at reducing the levels of IL-33 protein expression in IgE/Ag-stimulated BALB/c mice. Our study suggests the potential usage of GBR-SP024 as a dietary supplement or an adjuvant for treating IgE-dependent-allergic diseases.

Monoclonal Antibodies Targeting Alarmins: A New Perspective for Biological Therapies of Severe Asthma

Alarmins are innate cytokines, including thymic stromal lymphopoietin (TSLP), interleukin-33 (IL-33), and interleukin-25 (IL-25), which are mainly produced by airway epithelium and exert a prominent role in asthma pathobiology. In particular, several environmental factors such as allergens, cigarette smoking, airborne pollutants, and infectious agents trigger the release of alarmins, which in turn act as upstream activators of pro-inflammatory pathways underlying type 2 (T2-high) asthma. Indeed, alarmins directly activate group 2 innate lymphoid cells (ILC2), eosinophils, basophils, and mast cells and also stimulate dendritic cells to drive the commitment of naïve T helper (Th) cells towards the Th2 immunophenotype. Therefore, TSLP, IL-33, and IL-25 represent suitable targets for add-on therapies of severe asthma. Within this context, the fully human anti-TSLP monoclonal antibody tezepelumab has been evaluated in very promising randomized clinical trials. Tezepelumab and other anti-alarmins are thus likely to become, in the near future, valuable therapeutic options for the biological treatment of uncontrolled severe asthma.

IL-33 activates mTORC1 and modulates glycolytic metabolism in CD8+ T cells

Interleukin (IL)-33, a member in the IL-1 family, plays a central role in innate and adaptive immunity; however, how IL-33 mediates cytotoxic T-cell regulation and the downstream signals remain elusive. In this study, we found increased mouse IL-33 expression in CD8⁺ T cells following cell activation via anti-CD3/CD28 stimulation in vitro or lymphocytic choriomeningitis virus (LCMV) infection in vivo. Our cell adoptive transfer experiment demonstrated that extracellular, but not nuclear, IL-33 contributed to the activation and proliferation of CD8⁺ , but not CD4⁺ T effector cells in LCMV infection. Importantly, IL-33 induced mTORC1 activation in CD8⁺ T cells as evidenced by increased phosphorylated S6 ribosomal protein (p-S6) levels both in vitro and in vivo. Meanwhile, this IL-33-induced CD8⁺ T-cell activation was suppressed by mTORC1 inhibitors. Furthermore, IL-33 elevated glucose uptake and lactate production in CD8⁺ T cells in both dose- and time-dependent manners. The results of glycolytic rate assay demonstrated the increased glycolytic capacity of IL-33-treated CD8⁺ T cells compared with that of control cells. Our mechanistic study further revealed the capacity of IL-33 in promoting the expression of glucose transporter 1 (Glut1) and glycolytic enzymes via mTORC1, leading to accelerated aerobic glucose metabolism Warburg effect and increased effector T-cell activation. Together, our data provide new insights into IL-33-mediated regulation of CD8⁺ T cells, which might be beneficial for therapeutic strategies of inflammatory and infectious diseases in the future.

Differences and similarities between the upper and lower airway: focusing on innate immunity

The nose is the first respiratory barrier to external pathogens, allergens, pollutants, or cigarette smoke, and vigorous immune responses are triggered when external pathogens come in contact with the nasal epithelium. The mucosal epithelial cells of the nose are essential to the innate immune response against external pathogens and transmit signals that modulate the adaptive immune response. The upper and lower airways share many physiological and immunological features, but there are also numerous differences. It is crucial to understand these differences and their contribution to pathophysiology in order to optimize treatments for inflammatory diseases of the respiratory tract. This review summarizes important differences in the embryological development, histological features, microbiota, immune responses, and cellular subtypes of mucosal epithelial cells of the nose and lungs.

Viability Status-Dependent Effect of Bifidobacterium longum ssp. longum CCM 7952 on Prevention of Allergic Inflammation in Mouse Model

The classical definition of probiotics states that bacteria must be alive to be beneficial for human organism. However, recent reports show that inactivated bacteria or their effector molecules can also possess such properties. In this study, we investigated the physical and immunomodulatory properties of four Bifidobacterium strains in the heat-treated (HT) and untreated (UN) forms. We showed that temperature treatment of bacteria changes their size and charge, which affects their interaction with epithelial and immune cells. Based on the in vitro assays, we observed that all tested strains reduced the level of OVA-induced IL-4, IL-5, and IL-13 in the spleen culture of OVA-sensitized mice. We selected Bifidobacterium longum ssp. longum CCM 7952 (Bl 7952) for further analysis. In vivo experiments confirmed that untreated Bl 7952 exhibited allergy-reducing properties when administered intranasally to OVA-sensitized mice, which manifested in significant suppression of airway inflammation. Untreated Bl 7952 decreased local and systemic levels of Th2 related cytokines, OVA-specific IgE antibodies and simultaneously inhibited airway eosinophilia. In contrast, heat-treated Bl 7952 was only able to reduce IL-4 levels in the lungs and eosinophils in bronchoalveolar lavage, but increased neutrophil and macrophage numbers. We demonstrated that the viability status of Bl 7952 is a prerequisite for the beneficial effects of bacteria, and that heat treatment reduces but does not completely abolish these properties. Further research on bacterial effector molecules to elucidate the beneficial effects of probiotics in the prevention of allergic diseases is warranted.

Particulate matter exposure is highly correlated to pediatric asthma exacerbation

Asthma is a heterogeneous disease in which environmental factors play an important role, and the effect of particulate matter (PM) on the occurrence and severity of asthma is drawing more attention. This study aims to identify the correlation between PM and pediatric asthma exacerbation and explore the potential mechanisms. The asthma visits data (N = 16,779,739) in a university-based tertiary children’s hospital from January 2013 to December 2017 were collected, and the relationship between asthma visits and local PM concentration was analyzed. For further study, we established a house dust mite (HDM)-induced allergic airway inflammation model with PM intervention. We detected a correlation between PM concentration and pediatric asthma visits, especially in children under 6 years old. The in vivo data showed that PM aggravated HDM-induced airway inflammation, and IL-33 neutralizing antibody exerted a protective role. Our study suggests that PM is a risk factor in promoting pediatric asthma exacerbation, in which IL-33 might be a promising target.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

Skewed inflammation is associated with aberrant interleukin-37 signaling pathway in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a severe global burden on physical, physiological, and mental health. The role of IL-37, a fundamental inhibitor of immunity, in AD was herein explored.

METHOD

Serum levels of IL-37 and T helper (Th) 2-related inflammatory mediators were quantified in subjects with or without AD. The expression of IL-37 receptors was determined by flow cytometry. Proteomics was employed to explore the serum protein profile and novel biomarkers. In vitro cell model, 3D-keratinocytes mimicking skin model, and the serum of subjects with or without AD were investigated to verify the proteomic results.

RESULTS

AD patients were found to present with higher levels of total and specific IgE as well as Th2 inflammatory mediators compared with healthy controls (HC). IL-37 level and its receptor IL18Rɑ expression in AD patients were significantly decreased, together with increased population of eosinophils, indicating that the signaling of IL37/IL18Rɑ was dampened. In addition, proteomic analysis revealed a significantly differential protein profile of AD patients compared with HC. IL-37 showed the strongest negative correlation with involucrin, a keratinizing epithelia protein. IL-37 was verified to suppress induced involucrin expression in in vitro skin cell models. AD patients show a significantly higher serum concentration of involucrin compared with HC. Together, our results demonstrated that IL-37 plays a regulatory role in AD. Its deficiency may lead to the aberrant involucrin expression in AD.

CONCLUSIONS

The dysregulation of serum protein and skin disruption in AD is related to the insufficiency of IL-37 and its attenuated anti-inflammatory signaling.

Review of the potential of mesenchymal stem cells for the treatment of infectious diseases

The therapeutic value of mesenchymal stem cells (MSCs) for the treatment of infectious diseases and the repair of disease-induced tissue damage has been explored extensively. MSCs inhibit inflammation, reduce pathogen load and tissue damage encountered during infectious diseases through the secretion of antimicrobial factors for pathogen clearance and they phagocytose certain bacteria themselves. MSCs dampen tissue damage during infection by downregulating the levels of pro-inflammatory cytokines, and inhibiting the excessive recruitment of neutrophils and proliferation of T cells at the site of injury. MSCs aid in the regeneration of damaged tissue by differentiating into the damaged cell types or by releasing paracrine factors that direct tissue regeneration, differentiation, and wound healing. In this review, we discuss in detail the various mechanisms by which MSCs help combat pathogens, tissue damage associated with infectious diseases, and challenges in utilizing MSCs for therapy.

Lycopene Modulates Placental Health and Fetal Development Under High-Fat Diet During Pregnancy of Rats

Lycopene plays an important role in improving immunity, promoting antioxidant capacity, and regulating fat metabolism. The placenta, an important organ for nutrients exchange between mother and child during pregnancy, directly affects fetal development. This study aims to characterize effects of lycopene on placental health and fetal development under a high-fat diet, and utilize RNA sequencing (RNA-seq) to investigate and integrate the differences of molecular pathways and biological processes in placenta. For placental health, high-fat diet during pregnancy increases placental oxidative stress, inflammation, and fat deposition. However, lycopene reduces the negative effects of high-fat diet on placenta to some extent, and further promotes fetal development. Under high-fat diet, lycopene reduces the levels of Interleukin 17 (IL-17), Interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) in placenta (p < 0.05) through the IL-17 pathway. Furthermore, lycopene supplementation in high-fat diet increases Glutaredoxin (Glrx) gene and protein expression in the placenta (p < 0.05), increases Glutathione peroxidase (GSH-Px) and Total antioxidant capacity (T-AOC) levels (p < 0.05), decreases reactive oxygen species (ROS) (p < 0.01) and Hydrogen peroxide (H₂ O₂ ) levels (p < 0.05) in placenta. In addition, lycopene supplementation in high fat diet increases the expression of Lep gene and protein in placenta and increases the level of leptin (p < 0.05). In terms of fetal development, the average fetal weight and fetal litter weight are increased by lycopene compared to high-diet treatment.

Current Insights into Immunology and Novel Therapeutics of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory disease among non-fatal skin diseases, affecting up to one fifth of the population in developed countries. AD is characterized by recurrent pruritic and localized eczema with seasonal fluctuations. AD initializes the phenomenon of atopic march, during which infant AD patients are predisposed to progressive secondary allergies such as allergic rhinitis, asthma, and food allergies. The pathophysiology of AD is complex; onset of the disease is caused by several factors, including strong genetic predisposition, disrupted epidermal barrier, and immune dysregulation. AD was initially characterized by defects in the innate immune system and a vigorous skewed adaptive Th2 response to environmental agents; there are compelling evidences that the disorder involves multiple immune pathways. Symptomatic palliative treatment is the only strategy to manage the disease and restore skin integrity. Researchers are trying to more precisely define the contribution of different AD genotypes and elucidate the role of various immune axes. In this review, we have summarized the current knowledge about the roles of innate and adaptive immune responsive cells in AD. In addition, current and novel treatment strategies for the management of AD are comprehensively described, including some ongoing clinical trials and promising therapeutic agents. This information will provide an asset towards identifying personalized targets for better therapeutic outcomes.

Immune evasion in HPV- head and neck precancer-cancer transition is driven by an aneuploid switch involving chromosome 9p loss

An aneuploid-immune paradox encompasses somatic copy-number alterations (SCNAs), unleashing a cytotoxic response in experimental precancer systems, while conversely being associated with immune suppression and cytotoxic-cell depletion in human tumors, especially head and neck cancer (HNSC). We present evidence from patient samples and cell lines that alterations in chromosome dosage contribute to an immune hot-to-cold switch during human papillomavirus-negative (HPV-) head and neck tumorigenesis. Overall SCNA (aneuploidy) level was associated with increased CD3+ and CD8+ T cell microenvironments in precancer (mostly CD3+, linked to trisomy and aneuploidy), but with T cell-deficient tumors. Early lesions with 9p21.3 loss were associated with depletion of cytotoxic T cell infiltration in TP53 mutant tumors; and with aneuploidy were associated with increased NK-cell infiltration. The strongest driver of cytotoxic T cell and Immune Score depletion in oral cancer was 9p-arm level loss, promoting profound decreases of pivotal IFN-γ-related chemokines (e.g., CXCL9) and pathway genes. Chromosome 9p21.3 deletion contributed mainly to cell-intrinsic senescence suppression, but deletion of the entire arm was necessary to diminish levels of cytokine, JAK-STAT, and Hallmark NF-κB pathways. Finally, 9p arm-level loss and JAK2-PD-L1 codeletion (at 9p24) were predictive markers of poor survival in recurrent HPV- HNSC after anti-PD-1 therapy; likely amplified by independent aneuploidy-induced immune-cold microenvironments observed here. We hypothesize that 9p21.3 arm-loss expansion and epistatic interactions allow oral precancer cells to acquire properties to overcome a proimmunogenic aneuploid checkpoint, transform and invade. These findings enable distinct HNSC interception and precision-therapeutic approaches, concepts that may apply to other CN-driven neoplastic, immune or aneuploid diseases, and immunotherapies.

Expression of Nutrient Transporters on NK Cells During Murine Cytomegalovirus Infection Is MyD88-Dependent

Natural killer (NK) cells are the predominant innate lymphocytes that provide early defense against infections. In the inflammatory milieu, NK cells modify their metabolism to support high energy demands required for their proliferation, activation, and functional plasticity. This metabolic reprogramming is usually accompanied by the upregulation of nutrient transporter expression on the cell surface, leading to increased nutrient uptake required for intense proliferation. The interleukin-1 family members of inflammatory cytokines are critical in activating NK cells during infection; however, their underlying mechanism in NK cell metabolism is not fully elucidated. Previously, we have shown that IL-18 upregulates the expression of solute carrier transmembrane proteins and thereby induces a robust metabolic boost in NK cells. Unexpectedly, we found that IL-18 signaling is dispensable during viral infection in vivo, while the upregulation of nutrient transporters is primarily MyD88-dependent. NK cells from Myd88-/- mice displayed significantly reduced surface expression of nutrient receptors and mTOR activity during MCMV infection. We also identified that IL-33, another cytokine employing MyD88 signaling, induces the expression of nutrient transporters but requires a pre-exposure to IL-12. Moreover, signaling through the NK cell activating receptor, Ly49H, can also promote the expression of nutrient transporters. Collectively, our findings revealed multiple pathways that can induce the expression of nutrient transporters on NK cells while highlighting the imperative role of MyD88 in NK cell metabolism during infection.

The Predictive Role of Biomarkers and Genetics in Childhood Asthma Exacerbations

Asthma exacerbations are associated with significant childhood morbidity and mortality. Recurrent asthma attacks contribute to progressive loss of lung function and can sometimes be fatal or near-fatal, even in mild asthma. Exacerbation prevention becomes a primary target in the management of all asthmatic patients. Our work reviews current advances on exacerbation predictive factors, focusing on the role of non-invasive biomarkers and genetics in order to identify subjects at higher risk of asthma attacks. Easy-to-perform tests are necessary in children; therefore, interest has increased on samples like exhaled breath condensate, urine and saliva. The variability of biomarker levels suggests the use of seriate measurements and composite markers. Genetic predisposition to childhood asthma onset has been largely investigated. Recent studies highlighted the influence of single nucleotide polymorphisms even on exacerbation susceptibility, through involvement of both intrinsic mechanisms and gene-environment interaction. The role of molecular and genetic aspects in exacerbation prediction supports an individual-shaped approach, in which follow-up planning and therapy optimization take into account not only the severity degree, but also the risk of recurrent exacerbations. Further efforts should be made to improve and validate the application of biomarkers and genomics in clinical settings.

Mast Cells in the Skin: Defenders of Integrity or Offenders in Inflammation?

Mast cells (MCs) are best-known as key effector cells of immediate-type allergic reactions that may even culminate in life-threatening anaphylactic shock syndromes. However, strategically positioned at the host–environment interfaces and equipped with a plethora of receptors, MCs also play an important role in the first-line defense against pathogens. Their main characteristic, the huge amount of preformed proinflammatory mediators embedded in secretory granules, allows for a rapid response and initiation of further immune effector cell recruitment. The same mechanism, however, may account for detrimental overshooting responses. MCs are not only detrimental in MC-driven diseases but also responsible for disease exacerbation in other inflammatory disorders. Focusing on the skin as the largest immune organ, we herein review both beneficial and detrimental functions of skin MCs, from skin barrier integrity via host defense mechanisms to MC-driven inflammatory skin disorders. Moreover, we emphasize the importance of IgE-independent pathways of MC activation and their role in sustained chronic skin inflammation and disease exacerbation.

Virtual discovery of a hetero-cyclic compound from the Universal Natural Product Database (UNPD36) as a potential inhibitor of interleukin-33: molecular docking and dynamic simulations

Interleukin (IL)-33 is a cytokine implicated in several inflammatory and autoimmune diseases. Upon binding to its receptor ST2, IL-33 activates allergic inflammatory responses. To block this protein-protein interaction with a potential anti-allergic agent, we screened Universal Natural Product Database (UNPD) using a combined approach of molecular docking and dynamic simulations. Six hundred compounds with high gastrointestinal absorption properties from the UNPD were retrieved and subjected to molecular docking using Autodock Vina, out of which four hetero-cyclic compounds (UNPD36, UNPD2045, UNPD8905, UNPD122514) were found to have binding energy score of < -7.0 Kcal/mol. Further analysis from 100 ns MD simulation of the best hit (UNPD36) revealed that IL-33_UNPD36 complex reached average stability at RMSD of 2.7 Å, and residues involved in the interaction showed lower fluctuations compared to the residues at the β4-β5 and β11-β12 loop region. Further molecular docking using Autodock 4.2 was carried out to determine the binding orientation of UNPD36. Using GROMACS, additional 50 ns MD simulations and MM-PBSA calculation were performed on this complex. Finally, chemoinformatic studies revealed that the UNPD36 had drug-like and pharmacokinetic profiles as well as potentials for oral and topical applications, in addition to good safety profile. Thus, it was concluded that a hetero-cyclic compound with chromone moiety (UNPD36) had a good and stable binding mode to serve as potential inhibitor of IL-33 and/or may provide a scaffold for further optimization toward the design of more potent inhibitors for application in the treatment of respiratory allergies.Communicated by Ramaswamy H. Sarma.

The basic immunology of asthma

In many asthmatics, chronic airway inflammation is driven by IL-4-, IL-5-, and IL-13-producing Th2 cells or ILC2s. Type 2 cytokines promote hallmark features of the disease such as eosinophilia, mucus hypersecretion, bronchial hyperresponsiveness (BHR), IgE production, and susceptibility to exacerbations. However, only half the asthmatics have this "type 2-high" signature, and "type 2-low" asthma is more associated with obesity, presence of neutrophils, and unresponsiveness to corticosteroids, the mainstay asthma therapy. Here, we review the underlying immunological basis of various asthma endotypes by discussing results obtained from animal studies as well as results generated in clinical studies targeting specific immune pathways.

Nuclear IL-33/SMAD signaling axis promotes cancer development in chronic inflammation

Interleukin (IL)-33 cytokine plays a critical role in allergic diseases and cancer. IL-33 also has a nuclear localization signal. However, the nuclear function of IL-33 and its impact on cancer is unknown. Here, we demonstrate that nuclear IL-33-mediated activation of SMAD signaling pathway in epithelial cells is essential for cancer development in chronic inflammation. Using RNA and ChIP sequencing, we found that nuclear IL-33 repressed the expression of an inhibitory SMAD, Smad6, by interacting with its transcription factor, RUNX2. IL-33 was highly expressed in the skin and pancreatic epithelial cells in chronic inflammation, leading to a markedly repressed Smad6 expression as well as dramatically upregulated p-SMAD2/3 and p-SMAD1/5 in the epithelial cells. Blocking TGF-β/SMAD signaling attenuated the IL-33-induced cell proliferation in vitro and inhibited IL-33-dependent epidermal hyperplasia and skin cancer development in vivo. IL-33 and SMAD signaling were upregulated in human skin cancer, pancreatitis, and pancreatitis-associated pancreatic cancer. Collectively, our findings reveal that nuclear IL-33/SMAD signaling is a cell-autonomous tumor-promoting axis in chronic inflammation, which can be targeted by small-molecule inhibitors for cancer treatment and prevention.

Ruxolitinib Cream Has Dual Efficacy on Pruritus and Inflammation in Experimental Dermatitis

The goal of this study was to elucidate the anti-pruritic and anti-inflammatory efficacy of ruxolitinib cream in experimentally-induced dermatitis. Atopic dermatitis (AD), the most common chronic relapsing inflammatory skin disease, significantly impairs patients' quality of life, with pruritus being a common complaint. The sensation of itch results from the interplay between epidermal barrier dysfunction, upregulated immune signaling and the activation of the central nervous system. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a central role in pro-inflammatory cytokine signaling in AD. Ruxolitinib cream is a potent and selective JAK1/2 inhibitor currently undergoing clinical evaluation in adults with mild-to-moderate AD (NCT03745638, NCT03920852 and NCT03745651). The efficacy of ruxolitinib cream was tested in murine models of acute and chronic dermatitis and was also characterized in an ex vivo human skin dermatitis model. Ruxolitinib cream was highly effective at ameliorating disease symptoms in multiple murine dermatitis models through downregulation of T helper (Th)2-driven inflammation, resulting in reduced skin thickening and decreased itch. Pathway analysis of mouse ear tissue and human skin explants underscored the role for ruxolitinib in ameliorating inflammation and reducing itch via modulation of the JAK-STAT pathway. Together, the data offer a strong rationale for the use of ruxolitinib cream as a potent therapeutic agent for the clinical management of atopic dermatitis.