IL-17-producing alveolar macrophages mediate allergic lung inflammation related to asthma

RORγt inverse agonist TF-S14 inhibits Th17 cytokines and prolongs skin allograft survival in sensitized mice

Chronic antibody mediated rejection (AMR) is the major cause of solid organ graft rejection. Th17 contributes to AMR through the secretion of IL17A, IL21 and IL22. These cytokines promote neutrophilic infiltration, B cell proliferation and donor specific antibodies (DSAs) production. In the current study we investigated the role of Th17 in transplant sensitization. Additionally, we investigated the therapeutic potential of novel inverse agonists of the retinoic acid receptor-related orphan receptor gamma t (RORγt) in the treatment of skin allograft rejection in sensitized mice. Our results show that RORγt inverse agonists reduce cytokine production in human Th17 cells in vitro. In mice, we demonstrate that the RORγt inverse agonist TF-S14 reduces Th17 signature cytokines in vitro and in vivo and leads to blocking neutrophilic infiltration to skin allografts, inhibition of the B-cell differentiation, and the reduction of de novo IgG3 DSAs production. Finally, we show that TF-S14 prolongs the survival of a total mismatch grafts in sensitized mice. In conclusion, RORγt inverse agonists offer a therapeutic intervention through a novel mechanism to treat rejection in highly sensitized patients.

Echinochrome exhibits anti-asthmatic activity through the suppression of airway inflammation, oxidative stress, and histopathological alterations in ovalbumin-induced asthma in BALB/c mice

Asthma is a chronic pulmonary disease with marked infiltrating inflammatory cells and reduced respiratory performance. Echinochrome (Ech) is a dark-red pigment isolated from the sea urchin spines, shells, and ova. It has antioxidant, antimicrobial, and anti-inflammatory properties, but whether it can be used in asthma treatment has yet to be investigated. In this research, we aimed to study the inhibitory actions of Ech on allergic asthma symptoms in mice. Mice were divided into 4 groups (n = 8 for each): control, ovalbumin-challenged, and Ech-treated (0.1 and 1 mg/kg). At the end of the experiment, nasal scratching, lung oxidative stress, airway inflammation, and remodeling were assessed. In ovalbumin-challenged BALB/C mice, treatment with Ech significantly decreased nasal scratching, lung oxidative stress, inflammatory cell infiltration, mucus hyperproduction and hyperplasia of goblet cells, IgE levels, and inflammatory cytokines. It also inhibited NF-κB phosphorylation. This is the first study to investigate the immunomodulatory effect of Ech against allergic asthma in mice. According to our findings, we imply that Ech may be utilized as a treatment for allergic asthma.

Distinct trajectories distinguish antigen-specific T cells in peanut-allergic individuals undergoing oral immunotherapy

BACKGROUND

Despite similar clinical symptoms, peanut-allergic (PA) individuals may respond quite differently to the same therapeutic interventions.

OBJECTIVE

This study aimed to determine whether inherent qualities of cell response at baseline could influence response to peanut oral immunotherapy (PnOIT).

METHODS

We first performed ex vivo T-cell profiling on peanut-reactive CD154+CD137+ T (pTeff) cells from 90 challenge-confirmed PA individuals. We developed a gating strategy for unbiased assessment of the phenotypic distribution of rare pTeff cells across different memory CD4+ T-cell subsets to define patient immunotype. In longitudinal samples of 29 PA participants enrolled onto the IMPACT trial of PnOIT, we determined whether patient immunotype at baseline could influence response to PnOIT.

RESULTS

Our data emphasize the heterogeneity of pTeff cell responses in PA participants with 2 mutually exclusive phenotypic entities (CCR6-CRTH2+ and CCR6+CRTH2-). Our findings lead us to propose that peanut allergy can be classified broadly into at least 2 discrete subtypes, termed immunotypes, with distinct immunologic and clinical characteristics that are based on the proportion of TH2A pTeff cells. PnOIT induced elimination of TH2A pTeff cells in the context of the IMPACT clinical trial. Only 1 PA patient with a low level of TH2A pTeff cells at baseline experienced long-lasting benefit of remission after PnOIT discontinuation.

CONCLUSION

Dividing PA patients according to their individual peanut-specific T-cell profile may facilitate patient stratification in clinical settings by identifying which immunotypes might respond best to different therapies.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

The role of IL-17 in acute kidney injury

Acute kidney injury (AKI) is a common clinical kidney disease with a high mortality rate. AKI is caused by a variety of factors, including sepsis, ischemia, and nephrotoxic drugs, and can progress to chronic kidney disease and end-stage renal disease. Numerous studies have suggested that cytokines can be used as therapeutic targets for AKI. IL-17 is a pro-inflammatory cytokine that not only participates in the host defense and the development of autoimmune diseases but also is linked to AKI due to a variety of factors. This review will give an overview of the structure, signaling pathways, and biological functions of IL-17, as well as its role in AKI, to show that IL-17 is a potential target for the prevention and treatment of AKI.

Inhibition of non-receptor tyrosine kinase LCK partially mitigates mixed granulocytic airway inflammation in a murine model of asthma

Asthma affects millions of people worldwide and is one of the most common inflammatory airway diseases. Asthma phenotypes are quite complex and categorized as eosinophilic, mixed granulocytic (presence of both eosinophils and neutrophils in the airways) and neutrophilic. Mixed granulocytic asthma requires large doses of inhaled corticosteroids, which are often insufficient in controlling airway inflammation. Therefore, there is a medical need to test newer therapies to control granulocytic inflammation. Lymphocyte specific protein tyrosine kinase (LCK) signaling has gained momentum in recent years as a molecular target in inflammatory diseases such as asthma. LCK is expressed in lymphocytes and is required for inflammatory intracellular signaling in response to antigenic stimulation. Therefore, efficacy of LCK inhibitor, A770041 was tested in cockroach (CE)-induced corticosteroid insensitive murine model of asthma. The effect of LCK inhibitor was investigated on granulocytic airway inflammation, mucus production, p-LCK and downstream signaling molecules such as p-PLCγ, GATA3, p-STAT3 in CD4+ T cells. Moreover, its effects were also studied on Th2/Th17 related cytokines and oxidative stress parameters (iNOS/nitrotyrosine) in neutrophils/macrophages. Our study shows that CE-induced p-LCK levels are concomitant with increased neutrophilic/eosinophilic inflammation and mucus hypersecretion which are significantly mitigated by A770041 treatment. A770041 also caused marked attenuation of CE-induced pulmonary levels of IL-17A levels but not completely. However, A770041 in combination with dexamethasone caused complete downregulation of mixed granulocytic airway inflammation as well as Th2/Th17 related immune responses. These results suggest that combination of LCK inhibition along with corticosteroids may be pursued as an alternative strategy to completely treat mixed granulocytic asthma.

Tuberous Sclerosis Complex 1 Deficiency in Macrophages Promotes Unclassical Inflammatory Response to Lipopolysaccharide In Vitro and Dextran Sodium Sulfate-Induced Colitis in Mice

Human tuberous sclerosis (TSC) is mainly caused by genetic mutations of tuberous TSC1or TSC2. Recent studies found that TSC1 deficiency promoted classical M1 macrophage polarization. However, whether TSC1 regulates other inflammatory cytokine expression in lipopolysaccharidem (LPS)-stimulated macrophages is unknown. Herein, we studied the cytokine expression profile of wild-type (WT) and TSC1-deleted macrophages after LPS stimulation in vitro and the pathogenesis of dextran sodium sulfate (DSS)-induced colitis in mice with myeloid-specific TSC1 deletion (TSC1cKO mice). We found that TSC1-deficient macrophages exhibited the enhanced secretion of interleukin-17A (IL-17A), IL-17F, and interferon-gamma (IFN-γ) in response to LPS stimulation in vitro. This is in contrast to LPS-stimulated WT macrophages, which usually do not. Importantly, TSC1cKO mice exhibited exacerbated DSS-induced acute colitis with severer symptoms. MTOR deletion or rapamycin treatment significantly reversed the enhanced expressions of IL-17A, IL-17F, and IFN-γ in LPS-stimulated TSC1-deficient macrophages in vitro and rescued the enhanced DSS-induced colitis in TSC1cKO mice, indicating that TSC1 deficiency increased these cytokine productions in an mTOR-dependent manner. RNA-sequencing and molecular studies indicated that TSC1 deficiency enhanced the aerobic glycolysis process and the activities of mTOR-STAT3-RORγT pathway in LPS-stimulated macrophages. Inhibition of aerobic glycolysis, STAT3, or RORγT reversed IL-17 and IFN-γ expression in LPS-treated TSC1-deficient macrophages. Thus, TSC1 is essential for macrophages to shut down IL-17A, IL-17F, and IFN-γ expression during LPS stimulation by suppressing the aerobic glycolysis process and mTOR-STAT3, RORγT, and T-bet pathways. The present study uncovered the key role of TSC1 in shutting down IL-17A, IL-17F, and IFN-γ expressions in LPS-treated macrophages.

Role of Macrophages in Air Pollution Exposure Related Asthma

Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction, bronchial hyper-responsiveness, and airway inflammation. The chronic inflammation of the airway is mediated by many cell types, cytokines, chemokines, and inflammatory mediators. Research suggests that exposure to air pollution has a negative impact on asthma outcomes in adult and pediatric populations. Air pollution is one of the greatest environmental risks to health, and it impacts the lungs' innate and adaptive defense systems. A major pollutant in the air is particulate matter (PM), a complex component composed of elemental carbon and heavy metals. According to the WHO, 99% of people live in air pollution where air quality levels are lower than the WHO air quality guidelines. This suggests that the effect of air pollution exposure on asthma is a crucial health issue worldwide. Macrophages are essential in recognizing and processing any inhaled foreign material, such as PM. Alveolar macrophages are one of the predominant cell types that process and remove inhaled PM by secreting proinflammatory mediators from the lung. This review focuses on macrophages and their role in orchestrating the inflammatory responses induced by exposure to air pollutants in asthma.

Nontypeable Haemophilus influenzae infection of pulmonary macrophages drives neutrophilic inflammation in severe asthma

BACKGROUND

Nontypeable Haemophilus influenzae (NTHi) is a respiratory tract pathobiont that chronically colonizes the airways of asthma patients and is associated with severe, neutrophilic disease phenotypes. The mechanism of NTHi airway persistence is not well understood, but accumulating evidence suggests NTHi can persist within host airway immune cells such as macrophages. We hypothesized that NTHi infection of pulmonary macrophages drives neutrophilic inflammation in severe asthma.

METHODS

Bronchoalveolar lavage (BAL) samples from 25 severe asthma patients were assessed by fluorescence in situ hybridisation to quantify NTHi presence. Weighted gene correlation network analysis (WGCNA) was performed on RNASeq data from NTHi-infected monocyte-derived macrophages to identify transcriptomic networks associated with NTHi infection.

RESULTS

NTHi was detected in 56% of BAL samples (NTHi+) and was associated with longer asthma duration (34 vs 22.5 years, p = .0436) and higher sputum neutrophil proportion (67% vs 25%, p = .0462). WGCNA identified a transcriptomic network of immune-related macrophage genes significantly associated with NTHi infection, including upregulation of T17 inflammatory mediators and neutrophil chemoattractants IL1B, IL8, IL23 and CCL20 (all p < .05). Macrophage network genes SGPP2 (p = .0221), IL1B (p = .0014) and GBP1 (p = .0477) were more highly expressed in NTHi+ BAL and moderately correlated with asthma duration (IL1B; rho = 0.41, p = .041) and lower prebronchodilator FEV1/FVC% (GBP1; rho = -0.43, p = .046 and IL1B; rho = -0.42, p = .055).

CONCLUSIONS

NTHi persistence with pulmonary macrophages may contribute to chronic airway inflammation and T17 responses in severe asthma, which can lead to decreased lung function and reduced steroid responsiveness. Identifying therapeutic strategies to reduce the burden of NTHi in asthma could improve patient outcomes.

MiR-365-3p is a negative regulator in IL-17-mediated asthmatic inflammation

Background

Interleukin-17, the major proinflammatory cytokine secreted by Th17 cells, makes essential contribution to pathogenesis of severe asthma, while the detailed mechanisms, especially the involvement of microRNAs which are also important participants in asthma progression, remains largely unclear.

Methods

In this study, we established a house dust mite (HDM) extract-induced murine asthmatic models and the miRNA expression in the lung tissues of mice were profiled by miRNA microarray assay. The effect of miR-365-3p on IL-17-mediated inflammation was examined by qRT-PCR and immunoblotting analysis. The involvement of ARRB2 as target gene of miR-365-3p was verified by overexpression or RNA interference.

Results

HDM extract-induced asthmatic inflammation was proved to be IL17-mediated and miR-365-3p was screened out to be the only miRNA exclusively responsive to IL-17. miR-365-3p, whose expression was significantly downregulated upon IL-17 stimulation, was demonstrated to exert remarkable anti-inflammatory effect to decrease IL-17-provoked inflammatory cytokines (KC/IL-8 and IL-6) in both airway epithelial cells and macrophages of murine and human origins, verifying its universal antagonizing activity against IL-17-initiated inflammation across the two species. ARRB2 was characterized as the key target of miR-365-3p to negate IL-17-induced inflammatory cytokines.

Conclusion

Taken together, our data supported the notion that miR-365-3p, which was diminished by IL-17 in murine and human asthmatic pathogenesis, functioned as an essential negative mediator in IL-17-stimuated inflammatory response by targeting ARRB2, which would shed new light to the understanding and therapeutics thereof of asthmatic inflammation.

Fungal-mediated lung allergic airway disease: The critical role of macrophages and dendritic cells

Fungi are abundant in the environment, causing our lungs to be constantly exposed to a diverse range of species. While the majority of these are cleared effectively in healthy individuals, constant exposure to spores (especially Aspergillus spp.) can lead to the development of allergic inflammation that underpins and worsen diseases such as asthma. Despite this, the precise mechanisms that underpin the development of fungal allergic disease are poorly understood. Innate immune cells, such as macrophages (MΦs) and dendritic cells (DCs), have been shown to be critical for mediating allergic inflammation to a range of different allergens. This review will focus on the crucial role of MΦ and DCs in mediating antifungal immunity, evaluating how these immune cells mediate allergic inflammation within the context of the lung environment. Ultimately, we aim to highlight important future research questions that will lead to novel therapeutic strategies for fungal allergic diseases.

HDAC6-specific inhibitor alleviates hashimoto's thyroiditis through inhibition of Th17 cell differentiation

OBJECTIVE

Hashimoto's thyroiditis (HT) is one of the commonest autoimmune disorders. This study was performed to investigate the potential effect of histone deacetylase 6-specific inhibitor (HDAC6i) on Th17 cell differentiation in animal model and the underlying mechanism.

METHODS

Experimental autoimmune thyroiditis (EAT) mouse model was established by subcutaneously immunization of porcine thyroglobulin (pTg) and adjuvant, and the HDACi Tubastatin A (TSA) or HDAC6i (ACY-1215) was intraperitoneally injected into mice in the following. The histological examination and immune analysis in EAT mice were carried out. Next, the CD4+ T cells were isolated from peripheral blood mononuclear cells (PBMCs) of EAT mice followed by Th17 cell differentiation assay. The associated factor levels, and the protein interaction between HDAC6 and PKM2 were examined. Subsequently, the effect of STAT3 activation on Th17 cell differentiation was explored.

RESULTS

ACY-1215 or TSA treatment reduced lymphocytic infiltration and alleviated thyroid tissue injury in EAT mice. Correspondingly, either ACY-1215 or TSA treatment reduced the levels of anti-thyroglobulin (Tg), anti-thyroid peroxidase (TPO), IL-17A, and IFN-γ in the serum, decreased Th17 cell differentiation, but enhanced TGF-β level and promoted Treg cell differentiation. In vitro, after induction of Th17 cell differentiation from CD4+ T cells, HDAC6 activity and Th17 cell differentiation were significantly decreased when treated with ACY-1215 or TSA. HDAC6 could interact with PKM2, and HDAC6 overexpression promoted the phosphorylation of STAT3 and PKM2 nuclear translocation. Furthermore, the STAT3 activator treatment reversed the effects of ACY-1215 or TSA treatment.

CONCLUSION

HDAC6i suppresses Th17 cell differentiation and attenuates HT via PKM2/STAT3 axis.

Allergic airway inflammation induces upregulation of the expression of IL-23R by macrophages and not in CD3 + T cells and CD11c+F4/80- dendritic cells of the lung

Interleukin 23 and the interleukin 23 receptor (IL-23-IL23R) are described as the major enhancing factors for Interleukin 17 (IL-17) in allergic airway inflammation. IL-17 is considered to induce neutrophilic inflammation in the lung, which is often observed in severe, steroid-resistant asthma-phenotypes. For that reason, understanding of IL-23 and IL-17 axis is very important for future therapy strategies, targeting neutrophil pathway of bronchial asthma.

This study aimed to investigate the distribution and expression of IL-23R under physiological and inflammatory conditions. Therefore, a house dust mite (HDM) model of allergic airway inflammation was performed by treating mice with HDM intranasally. Immunofluorescence staining with panel of antibodies was performed in lung tissues to examine the macrophage, dendritic cell, and T cell subpopulations. The allergic airway inflammation was quantified by histopathological analysis, ELISA measurements, and airway function.

HDM-treated mice exhibited a significant allergic airway inflammation including higher amounts of NE⁺ cells in lung parenchyma. We found only a small amount of IL-23R positives, out of total CD3⁺T cells, and no upregulation in HDM-treated animals. In contrast, the populations of F4/80⁺ macrophages and CD11c⁺F4/80⁻ dendritic cells (DCs) with IL-23R expression were found to be higher. But HDM treatment leads to a significant increase of IL-23R⁺ macrophages, only. IL-23R was expressed by every examined macrophage subpopulation, whereas only Mϕ1 and hybrids between Mϕ1 and Mϕ2 phenotype and not Mϕ2 were found to upregulate IL-23R. Co-localization of IL-23R and IL-17 was only observed in F4/80⁺ macrophages, suggesting F4/80⁺ macrophages express IL-23R along with IL-17 in lung tissue.

The study revealed that macrophages involving the IL-23 and IL-17 pathway may provide a potential interesting therapeutic target in neutrophilic bronchial asthma.

Contribution of Interleukin-17A to Retinal Degenerative Diseases

Retinal degenerative diseases are a leading cause of vision loss and blindness throughout the world, characterized by chronic and progressive loss of neurons and/or myelin. One of the common features of retinal degenerative diseases and central neurodegenerative diseases is chronic neuroinflammation. Interleukin-17A (IL-17A) is the cytokine most closely related to disease in its family. Accumulating evidence suggests that IL-17A plays a key role in human retinal degenerative diseases, including age-related macular degeneration, diabetic retinopathy and glaucoma. This review aims to provide an overview of the role of IL-17A participating in the pathogenesis of retinal degenerative diseases, which may open new avenues for potential therapeutic interventions.

Interleukin-17 contributes to Ross River virus-induced arthritis and myositis

Arthritogenic alphaviruses are mosquito-borne viruses that are a major cause of infectious arthropathies worldwide, and recent outbreaks of chikungunya virus and Ross River virus (RRV) infections highlight the need for robust intervention strategies. Alphaviral arthritis can persist for months after the initial acute disease, and is mediated by cellular immune responses. A common strategy to limit inflammation and pathology is to dampen the overwhelming inflammatory responses by modulating proinflammatory cytokine pathways. Here, we investigate the contribution of interleukin-17 (IL-17), a cytokine involved in arthropathies such as rheumatoid arthritis, in the development RRV-induced arthritis and myositis. IL-17 was quantified in serum from RRV-infected patients, and mice were infected with RRV and joints and muscle tissues collected to analyse cellular infiltrates, tissue mRNA, cytokine expression, and joint and muscle histopathology. IL-17 expression was increased in musculoskeletal tissues and serum of RRV-infected mice and humans, respectively. IL-17–producing T cells and neutrophils contributed to the cellular infiltrate in the joint and muscle tissue during acute RRV disease in mice. Blockade of IL-17A/F using a monoclonal antibody (mAb) reduced disease severity in RRV-infected mice and led to decreased proinflammatory proteins, cellular infiltration in synovial tissues and cartilage damage, without affecting viral titers in inflamed tissues. IL-17A/F blockade triggered a shift in transcriptional profile of both leukocyte infiltrates and musculoskeletal stromal cells by downregulating proinflammatory genes. This study highlights a previously uncharacterized role for an effector cytokine in alphaviral pathology and points towards potential therapeutic benefit in targeting IL-17 to treat patients presenting with RRV-induced arthropathy.

Some viruses transmitted by mosquitoes cause painful and debilitating arthritis, which manifests both as an acute form shortly following infection, and a chronic form long after the initial symptoms have subsided. These viruses, termed arboviruses, are difficult to control and there are currently no specific treatments to alleviate the pain and loss of mobility. Arthritis caused by arboviruses shares similarities with a non-infectious, autoimmune form of arthritis called rheumatoid arthritis (RA). In RA, an immune molecule termed interleukin-17, or IL-17, has been shown to drive arthritis and treatments that target or block IL-17 are being developed to treat RA. Here, we asked whether arthritis caused by an arbovirus, Ross River virus (RRV), was also associated with elevated IL-17 in humans and mice. Disease severity in mice was associated with high IL-17 expression in the feet and muscle, and blocking IL-17 using an anti-IL-17 monoclonal antibody ameliorated disease in mice infected with RRV. Our study provides new information on a molecule that is implicated in arthritic inflammation, and could be targeted to treat disease caused by arthritogenic arboviruses.

Tendon Immune Regeneration: Insights on the Synergetic Role of Stem and Immune Cells during Tendon Regeneration

Tendon disorders represent a very common pathology in today’s population, and tendinopathies that account 30% of tendon-related injuries, affect yearly millions of people which in turn cause huge socioeconomic and health repercussions worldwide. Inflammation plays a prominent role in the development of tendon pathologies, and advances in understanding the underlying mechanisms during the inflammatory state have provided additional insights into its potential role in tendon disorders. Different cell compartments, in combination with secreted immune modulators, have shown to control and modulate the inflammatory response during tendinopathies. Stromal compartment represented by tenocytes has shown to display an important role in orchestrating the inflammatory response during tendon injuries due to the interplay they exhibit with the immune-sensing and infiltrating compartments, which belong to resident and recruited immune cells. The use of stem cells or their derived secretomes within the regenerative medicine field might represent synergic new therapeutical approaches that can be used to tune the reaction of immune cells within the damaged tissues. To this end, promising opportunities are headed to the stimulation of macrophages polarization towards anti-inflammatory phenotype together with the recruitment of stem cells, that possess immunomodulatory properties, able to infiltrate within the damaged tissues and improve tendinopathies resolution. Indeed, the comprehension of the interactions between tenocytes or stem cells with the immune cells might considerably modulate the immune reaction solving hence the inflammatory response and preventing fibrotic tissue formation. The purpose of this review is to compare the roles of distinct cell compartments during tendon homeostasis and injury. Furthermore, the role of immune cells in this field, as well as their interactions with stem cells and tenocytes during tendon regeneration, will be discussed to gain insights into new ways for dealing with tendinopathies.

MicroRNA-mediated calcineurin signaling activation induces CCL2, CCL3, CCL5, IL8, and chemotactic activities in 4,4'-methylene diphenyl diisocyanate exposed macrophages

Occupational exposure to 4,4'-methylene diphenyl diisocyanate (MDI), the most widely used monomeric diisocyanate, is one of the leading causes of occupational asthma (OA). Previously, we identified microRNA (miR)-206-3p/miR-381-3p-mediated PPP3CA/calcineurin signalling regulated iNOS transcription in macrophages and bronchoalveolar lavage cells (BALCs) after acute MDI exposure; however, whether PPP3CA/calcineurin signalling participates in regulation of other asthma-associated mediators secreted by macrophages/BALCs after MDI exposure is unknown.Several asthma-associated, macrophage-secreted mediator mRNAs from MDI exposed murine BALCs and MDI-glutathione (GSH) conjugate treated differentiated THP-1 macrophages were analysed using RT-qPCR.Endogenous IL1B, TNF, CCL2, CCL3, CCL5, and TGFB1 were upregulated in MDI or MDI-GSH conjugate exposed BALCs and macrophages, respectively. Calcineurin inhibitor tacrolimus (FK506) attenuated the MDI-GSH conjugate-mediated induction of CCL2, CCL3, CCL5, and CXCL8/IL8 but not others. Transfection of either miR-inhibitor-206-3p or miR-inhibitor-381-3p in macrophages induced chemokine CCL2, CCL3, CCL5, and CXCL8 transcription, whereas FK506 attenuated the miR-inhibitor-206-3p or miR-inhibitor-381-3p-mediated effects. Finally, MDI-GSH conjugate treated macrophages showed increased chemotactic ability to various immune cells, which may be attenuated by FK506.In conclusion, these results indicate that MDI exposure to macrophages/BALCs may recruit immune cells into the airway via induction of chemokines by miR-206-3p and miR-381-3p-mediated calcineurin signalling activation.

Unexpected connections of the IL-23/IL-17 and IL-4/IL-13 cytokine axes in inflammatory arthritis and enthesitis

The IL-23/IL-17 cytokine axis is related to spondyloarthropathy (SpA) pattern diseases that target the skin, eye, gut and joints. These share overlapping target tissues with Th2 type or allergic diseases, including the skin, eye and gut but SpA diseases exhibit distinct microanatomical topography, molecular characteristics, and clinical features including uveitis, psoriasis, apical pulmonary involvement, lower gastrointestinal involvement with colitis, and related arthritides including psoriatic arthritis and ankylosing spondylitis. Inflammatory arthritis is conspicuously absent from the Th2 diseases which are characterised IL-4/IL-13 dependent pathway activation including allergic rhino-conjunctivitis, atopic eczema, allergic asthma and food allergies. This traditional understanding of non-overlap of musculoskeletal territory between that atopic diseases and the IL-17 -mediated SpA diseases is undergoing a critical reappraisal with the recent demonstration of IL-4/IL-13 blockade, may be associated with the development of SpA pattern arthritis, psoriasiform skin disease and occasional anterior uveitis. Given the known plasticity within Th paradigm pathways, these findings suggest dynamic Th2 cytokine and Th17 cytokine counter regulation in vivo in humans. Unexpected, this is the case in peripheral enthesis and when the IL-4/13 immunological brake on IL-23/17 cytokines is removed, a SpA phenotype may emerge. We discuss hitherto unexpected observations in SpA, showing counter regulation between the Th17 and Th2 pathways at sites including the entheses that collectively indicate that the emergent reverse translational therapeutic data is more than coincidental and offers new insights into the "Th paradigms" in atopy and SpA.

Leukocytes in Critical Patients With Asthma Exacerbation

Background Asthma exacerbations, defined as acute or subacute progressive worsening of airway spasm, are a significant cause of disease morbidity. Risk factors for exacerbation include sex, age, race, socioeconomic status, baseline lung function, smoking history, and exposure to respiratory viruses. It is believed that white cells play an essential role in the pathogenesis of such attacks; however, the current understanding of the relationship between cell lines during an asthma attack is minimal. Methods This report represents a retrospective study for patients admitted to ICU for asthma exacerbations. The Medical Information Mart for Intensive Care iii (MIMIC iii) version 1.4 database was used to identify patients admitted for asthma exacerbations. The demographics, laboratory data gathered in addition, to clinical variables and outcomes were determined. Results The length of stay increased with the increase in WBC (p = 0.001). Intubated patients had an increased white blood cell (WBC) count when compared with non-intubated patients (p-value 0.009). In addition, patients with normal basophil counts on presentation were less likely to need intubation than those presenting with low basophils (p-value 0.015, adjusted odds ratio = 0.074, CI [0.009-0.620]) and those presenting with basophilia (p-value 0.001, adjusted odds ratio = 0.025, CI [0.003-0.225]). Furthermore, prolonged intubation (for three days or more) was positively correlated with eosinophil counts. On the other hand, there was no statistically significant association between the length of ICU and the patient's age, smoking status, or gender (p-values 0.611; 0.761; and 0.201, respectively). Conclusion Asthma exacerbation is a disease of heterogeneous pathophysiology. The leukocyte count is associated with the length of stay and the need for mechanical ventilation.

Toxicological Evaluations in Macrophages and Mice Acutely and Chronically Exposed to Halloysite Clay Nanotubes Functionalized with Polystyrene

Halloysite clay nanotubes (HNTs) have been proposed as highly biocompatible for several biomedical applications. Various polymers have been used to functionalize HNTs, but scarce information exists about polystyrene for this purpose. This work evaluated polystyrene-functionalized HNTs (FHNTs) by comparing its effects with non-FHNTs and innocuous talc powder on in vitro and in vivo models. Monocyte-derived human or murine macrophages and the RAW 264.7 cell line were treated with 0.01, 0.1, 1, and 100 μg mL^-1 FHNTs, HNTs, or talc to evaluate the cytotoxic and cytokine response. Our results show that nanoclays did not cause cytotoxic damage to macrophages. Only the 100 μg mL^-1 concentration induced slight proinflammatory cytokine production at short exposure, followed by an anti-inflammatory response that increases over time. CD1 mice treated with a single dose of 1, 2.5, or 5 mg Kg^-1 of FHNTs or HNTs by oral and inhalation routes caused aluminum accumulation in the kidneys and lungs, without bodily signs of distress or histopathological changes in any treated mice, evaluated at 48 h and 30 days post-treatment. Nanoclay administration simultaneously by four different parenteral routes (20 mg Kg^-1) or the combination of administration routes (parenteral + oral or parenteral + inhalation; 25 mg Kg^-1) showed accumulation on the injection site and slight surrounding inflammation 30 days post-treatment. CD1 mice chronically exposed to HNTs or FHNTs in the bedding material (ca 1 mg) throughout the parental generation and two successive inbred generations for 8 months did not cause any inflammatory process or damage to the abdominal organs and the reproductive system of the mice of any of the generations, did not affect the number of newborn mice and their survival, and did not induce congenital malformations in the offspring. FHNTs showed a slightly less effect than HNTs in all experiments, suggesting that functionalization makes them less cytotoxic. Doses of up to 25 mg Kg^-1 by different administration routes and permanent exposure to 1 mg of HNTs or FHNTs for 8 months seem safe for CD1 mice. Our in vivo and in vitro results indicate that nanoclays are highly biocompatible, supporting their possible safe use for future biomedical and general-purpose applications.

Inflammation in Asthma Pathogenesis: Role of T cells, Macrophages, Epithelial Cells and Type 2 Inflammation

Asthma is a chronic disease with abnormal inflammatory and immunological responses. The disease initiated by antigens in subjects with genetic susceptibility. However, environmental factors play a role in the initiation and exacerbation of asthma attack. Asthma is T helper 2 (Th2)-cell-mediated disease. Recent studies indicated that asthma is not a single disease entity, but it is with multiple phenotypes and endotypes. The pathophysiological changes in asthma included a series of subsequent continuous vicious circle of cellular activation contributed to induction of chemokines and cytokines that potentiate inflammation. The heterogeneity of asthma influenced the treatment response. The asthma pathogenesis driven by varied set of cells such as eosinophils, basophils, neutrophils, mast cells, macrophages, epithelial cells and T cells. In this review the role of T cells, macrophage, and epithelial cells are discussed.

Dual RNASeq Reveals NTHi-Macrophage Transcriptomic Changes During Intracellular Persistence

Nontypeable Haemophilus influenzae (NTHi) is a pathobiont which chronically colonises the airway of individuals with chronic respiratory disease and is associated with poor clinical outcomes. It is unclear how NTHi persists in the airway, however accumulating evidence suggests that NTHi can invade and persist within macrophages. To better understand the mechanisms of NTHi persistence within macrophages, we developed an in vitro model of NTHi intracellular persistence using human monocyte-derived macrophages (MDM). Dual RNA Sequencing was used to assess MDM and NTHi transcriptomic regulation occurring simultaneously during NTHi persistence. Analysis of the macrophage response to NTHi identified temporally regulated transcriptomic profiles, with a specific 'core' profile displaying conserved expression of genes across time points. Gene list enrichment analysis identified enrichment of immune responses in the core gene set, with KEGG pathway analysis revealing specific enrichment of intracellular immune response pathways. NTHi persistence was facilitated by modulation of bacterial metabolic, stress response and ribosome pathways. Levels of NTHi genes bioC, mepM and dps were differentially expressed by intracellular NTHi compared to planktonic NTHi, indicating that the transcriptomic adaption was distinct between the two different NTHi lifestyles. Overall, this study provides crucial insights into the transcriptomic adaptations facilitating NTHi persistence within macrophages. Targeting these reported pathways with novel therapeutics to reduce NTHi burden in the airway could be an effective treatment strategy given the current antimicrobial resistance crisis and lack of NTHi vaccines.

IL-23/IL-17A/TRPV1 axis produces mechanical pain via macrophage-sensory neuron crosstalk in female mice

Although sex dimorphism is increasingly recognized as an important factor in pain, female-specific pain signaling is not well studied. Here we report that administration of IL-23 produces mechanical pain (mechanical allodynia) in female but not male mice, and chemotherapy-induced mechanical pain is selectively impaired in female mice lacking Il23 or Il23r. IL-23-induced pain is promoted by estrogen but suppressed by androgen, suggesting an involvement of sex hormones. IL-23 requires C-fiber nociceptors and TRPV1 to produce pain but does not directly activate nociceptor neurons. Notably, IL-23 requires IL-17A release from macrophages to evoke mechanical pain in females. Low-dose IL-17A directly activates nociceptors and induces mechanical pain only in females. Finally, deletion of estrogen receptor subunit α (ERα) in TRPV1⁺ nociceptors abolishes IL-23- and IL-17-induced pain in females. These findings demonstrate that the IL-23/IL-17A/TRPV1 axis regulates female-specific mechanical pain via neuro-immune interactions. Our study also reveals sex dimorphism at both immune and neuronal levels.

Arf6 exacerbates allergic asthma through cell-to-cell transmission of ASC inflammasomes

Asthma is a chronic inflammatory disease of the airways associated with excess production of Th2 cytokines and lung eosinophil accumulation. This inflammatory response persists in spite of steroid administration that blocks autocrine/paracrine loops of inflammatory cytokines, and the detailed mechanisms underlying asthma exacerbation remain unclear. Here, we show that asthma exacerbation is triggered by airway macrophages through a prion-like cell-to-cell transmission of extracellular particulates, including ASC protein, that assemble inflammasomes and mediate IL-1β production. OVA-induced allergic asthma and associated IL-1β production were alleviated in mice with small GTPase Arf6-deficient macrophages. The extracellular ASC specks were slightly engulfed by Arf6^–/– macrophages, and the IL-1β production was reduced in Arf6^–/– macrophages compared with that in WT macrophages. Furthermore, pharmacological inhibition of the Arf6 guanine nucleotide exchange factor suppressed asthma-like allergic inflammation in OVA-challenged WT mice. Collectively, the Arf6-dependent intercellular transmission of extracellular ASC specks contributes to the amplification of allergic inflammation and subsequent asthma exacerbation.

Cellular and molecular mechanisms of allergic asthma

Asthma is a chronic disease of the airways, which affects more than 350 million people worldwide. It is the most common chronic disease in children, affecting at least 30 million children and young adults in Europe. Asthma is a complex, partially heritable disease with a marked heterogeneity. Its development is influenced both by genetic and environmental factors. The most common, as well as the most well characterized subtype of asthma is allergic eosinophilic asthma, which is characterized by a type 2 airway inflammation. The prevalence of asthma has substantially increased in industrialized countries during the last 60 years. The mechanisms underpinning this phenomenon are incompletely understood, however increased exposure to various environmental pollutants probably plays a role. Disease inception is thought to be enabled by a disadvantageous shift in the balance between protective and harmful lifestyle and environmental factors, including exposure to protective commensal microbes versus infection with pathogens, collectively leading to airway epithelial cell damage and disrupted barrier integrity. Epithelial cell-derived cytokines are one of the main drivers of the type 2 immune response against innocuous allergens, ultimately leading to infiltration of lung tissue with type 2 T helper (T_H2) cells, type 2 innate lymphoid cells (ILC2s), M2 macrophages and eosinophils. This review outlines the mechanisms responsible for the orchestration of type 2 inflammation and summarizes the novel findings, including but not limited to dysregulated epithelial barrier integrity, alarmin release and innate lymphoid cell stimulation.

Thyme oil alleviates Ova-induced bronchial asthma through modulating Th2 cytokines, IgE, TSLP and ROS

Bronchial asthma (BA) is a heterogeneous allergic respiratory disease with diverse inflammatory symptoms, pathology, and responses to treatment. Thyme is a natural product which is consisted of multiple phenolic compounds of therapeutic significance for treatment of cough and bronchitis. This study evaluated the efficacy of thyme oil against ovalbumin (OVA)-induced BA in an experimental rabbit model. Forty male rabbits were divided into four equal groups [control group (G1), OVA (G2), thyme oil (G3), and OVA plus thyme oil (G4)]. Animals were treated for 30 days, and clinical, histopathological (HP), histochemical (HC), immunohistochemical (IHC), morphometric, biochemical and flow cytometry methods were performed, followed by statistical analysis. All used methods revealed normal structure of the lung tissues in rabbits of G1 and G3. In contrast, the clinical examination of G2 rabbits revealed an obvious increase in the respiratory rate, sneezing and wheezing, whereas the HP, HC and IHC techniques exhibited substantial inflammatory changes in the peribronchio-vascular lung tissues with thinning, degeneration, apoptosis (using the TUNEL assay), necrosis, and shedding of the airway epithelium. Furthermore, the morphometric results confirmed significant increases in the numbers of inflammatory cells, goblet cells, eosinophils and apoptotic cells from (12, 0, 2, 2 cells) to (34,10, 16, 18 cells) respectively, as well as the area percentage of collagen fiber deposition and immunoexpression of eotaxin-1/10 high power fields. Additionally, the biochemical results revealed significant increases in the serum levels of TSLP, IL-4, IL-5, IL-9, IL-13, IgE and eotaxin-1 cytokines from (140, 40, 15, 38, 120, 100, 48) pg./ml to (360, 270, 130, 85, 365, 398, 110) pg./ml respectively, while analysis of ROS by flow cytometry revealed remarkable oxidative stress effects in G2 rabbits. On the other hand, treatment of rabbits with thyme oil in G4 substantially alleviated all OVA-induced alterations. Overall, our findings indicate for the first time that thyme oil can ameliorate OVA-induced BA via its immunomodulatory, anti-inflammatory, antiapoptotic, and antioxidant effects on the lung tissues of rabbits.

Scavenger Receptor BI Attenuates IL-17A-Dependent Neutrophilic Inflammation in Asthma

Asthma is a common respiratory disease currently affecting more than 300 million worldwide and is characterized by airway inflammation, hyperreactivity, and remodeling. It is a heterogeneous disease consisting of corticosteroid-sensitive T-helper cell type 2-driven eosinophilic and corticosteroid-resistant, T-helper cell type 17-driven neutrophilic phenotypes. One pathway recently described to regulate asthma pathogenesis is cholesterol trafficking. Scavenger receptors, in particular SR-BI (scavenger receptor class B type I), are known to direct cellular cholesterol uptake and efflux. We recently defined SR-BI functions in pulmonary host defense; however, the function of SR-BI in asthma pathogenesis is unknown. To elucidate the role of SR-BI in allergic asthma, SR-BI-sufficient (SR-BI+/+) and SR-BI-deficient (SR-BI-/-) mice were sensitized (Days 0 and 7) and then challenged (Days 14, 15, and 16) with a house dust mite (HDM) preparation administered through oropharyngeal aspiration. Airway inflammation and cytokine production were quantified on Day 17. When compared with SR-BI+/+ mice, the HDM-challenged SR-BI-/- mice had increased neutrophils and pulmonary IL-17A production in BAL fluid. This augmented IL-17A production in SR-BI-/- mice originated from a non-T-cell source that included neutrophils and alveolar macrophages. Given that SR-BI regulates adrenal steroid hormone production, we tested whether the changes in SR-BI-/- mice were glucocorticoid dependent. Indeed, SR-BI-/- mice were adrenally insufficient during the HDM challenge, and corticosterone replacement decreased pulmonary neutrophilia and IL-17A production in SR-BI-/- mice. Taken together, these data indicate that SR-BI dampens pulmonary neutrophilic inflammation and IL-17A production in allergic asthma at least in part by maintaining adrenal function.

Acute 4,4'-Methylene Diphenyl Diisocyanate Exposure-Mediated Downregulation of miR-206-3p and miR-381-3p Activates Inducible Nitric Oxide Synthase Transcription by Targeting Calcineurin/NFAT Signaling in Macrophages

Exposure to 4,4'-methylene diphenyl diisocyanate (MDI) in the occupational setting may lead to development of occupational asthma (OA), and the underlying molecular mechanisms of MDI-induced disease pathogenesis remain an active area of research. Using a nose-only mouse inhalation model, we find that circulating microRNA (miR)-206-3p and miR-381-3p are downregulated after MDI exposure; however, cellular miR-206-3p and miR-381-3p responses after MDI aerosol exposure and their pathophysiological roles in MDI-OA are unknown. We hypothesize that miR-206-3p and miR-381-3p-regulated mechanisms cause increased expression of the inducible nitric oxide synthase (iNOS) after MDI aerosol exposure. We examined cellular miR-206-3p and miR-381-3p, calcineurins, nuclear factors of activated T cells (NFATs), and iNOS levels from both nose-only exposed murine bronchoalveolar lavage cells (BALCs) and differentiated THP-1 macrophages treated with MDI-glutathione (GSH) conjugates. Both in vivo murine MDI aerosol exposure and in vitro MDI-GSH exposures in THP-1 macrophages result in downregulation of endogenous miR-206-3p and miR-381-3p and upregulation of PPP3CA and iNOS expression. Transfection of THP-1 macrophages with miR-inhibitor-206-3p and miR-inhibitor-381-3p resulted in the upregulation of PPP3CA and iNOS. Using RNA-induced silencing complex immunoprecipitation and translational reporter assays, we verified that PPP3CA, but not iNOS, is directly targeted by both miR-206-3p and miR-381-3p. Downregulation of miR-206-3p and miR-381-3p following by MDI exposure induces calcineurin/NFAT signaling-mediated iNOS transcription in macrophages and BALCs.

Requirement of Gαi1 and Gαi3 in interleukin-4-induced signaling, macrophage M2 polarization and allergic asthma response

IL-4 induces Akt activation in macrophages, required for full M2 (alternative) polarization. We examined the roles of Gαi1 and Gαi3 in M2 polarization using multiple genetic methods.

Methods and Results: In MEFs and primary murine BMDMs, Gαi1/3 shRNA, knockout or dominant negative mutations attenuated IL-4-induced IL4Rα endocytosis, Gab1 recruitment as well as Akt activation, leaving STAT6 signaling unaffected. Following IL-4 stimulation, Gαi1/3 proteins associated with the intracellular domain of IL-4Rα and the APPL1 adaptor, to mediate IL-4Rα endosomal traffic and Gab1-Akt activation in BMDMs. In contrast, gene silencing of Gαi1/3 with shRNA or knockout resulted in BMDMs that were refractory to IL-4-induced M2 polarization. Conversely, Gαi1/3-overexpressed BMDMs displayed preferred M2 response with IL-4 stimulation. In primary human macrophages IL-4-induced Akt activation and Th2 genes expression were inhibited with Gαi1/3 silencing, but augmented with Gαi1/3 overexpression. In Gαi1/3 double knockout (DKO) mice, M2 polarization, by injection of IL-4 complex or chitin, was potently inhibited. Moreover, in a murine model of asthma, ovalbumin-induced airway inflammation and hyperresponsiveness were largely impaired in Gαi1/3 DKO mice.

Conclusion: These findings highlight novel and essential roles for Gαi1/3 in regulating IL-4-induced signaling, macrophage M2 polarization and allergic asthma response.

IRAK-M knockout promotes allergic airway inflammation, but not airway hyperresponsiveness, in house dust mite-induced experimental asthma model

Background

IL-1 receptor associated-kinase (IRAK)-M, expressed by airway epithelium and macrophages, was shown to regulate acute and chronic airway inflammation exhibiting a biphasic response in an OVA-based animal model. House dust mite (HDM) is a common real-life aeroallergen highly relevant to asthma pathogenesis. The role of IRAK-M in HDM-induced asthma remains unknown. This study was aimed to investigate the effect of IRAK-M on allergic airway inflammation induced by HDM using IRAK-M knockout (KO) mice and the potential underlying mechanisms.

Methods

IRAK-M KO and wild-type (WT) mice were sensitized and challenged with HDM. The differences in airway inflammation were evaluated 24 hours after the last challenge between the two genotypes of mice using a number of cellular and molecular biological techniques. In vitro mechanistic investigation was also involved.

Results

Lung expression of IRAK-M was significantly upregulated by HDM in the WT mice. Compared with the WT controls, HDM-treated IRAK-M KO mice showed exacerbated infiltration of inflammatory cells, particularly Th2 cells, in the airways and mucus overproduction, higher epithelial mediators IL-25, IL-33 and TSLP and Th2 cytokines in bronchoalveolar lavage (BAL) fluid. Lung IRAK-M KO macrophages expressed higher percentage of costimulatory molecules OX40L and CD 80 and exhibited enhanced antigen uptake. However, IRAK-M KO didn’t impact the airway hyperreactivity (AHR) indirectly induced by HDM.

Conclusions

The findings indicate that IRAK-M protects allergic airway inflammation, not AHR, by modifying activation and antigen uptake of lung macrophages following HDM stimulation. Optimal regulation of IRAK-M might indicate an intriguing therapeutic avenue for allergic airway inflammation.

Exploring IL-17 in spondyloarthritis for development of novel treatments and biomarkers

Spondyloarthritis (SpA) is an umbrella term describing a family of chronic inflammatory rheumatic diseases. These diseases are characterised by inflammation of the axial skeleton, peripheral joints, and entheseal insertion sites throughout the body which can lead to structural joint damage including formation of axial syndesmophytes and peripheral osteophytes. Genetic evidence, preclinical and clinical studies indicate a clear role of interleukin (IL)- 23 and IL-17 as mediators in SpA pathogenesis. Targeting the IL-23/-17 pathways seems an efficient strategy for treatment of SpA patients, and despite the remaining challenges the pathway holds great promise for further advances and improved therapeutic opportunities. Much research is focusing on serological markers and imaging strategies to correctly diagnose patients in the early stages of SpA. Biomarkers may facilitate personalised medicine tailored to each patient's specific disease to optimise treatment efficacy and to monitor therapeutic response. This narrative review focuses on the IL-17 pathway in SpA-related diseases with emphasis on its role in pathogenesis, current approved IL-17 inhibitors, and the need for biomarkers reflecting core disease pathways for early diagnosis and measurement of disease activity, prognosis, and response to therapy.

The Role of T Cells and Macrophages in Asthma Pathogenesis: A New Perspective on Mutual Crosstalk

Asthma is associated with innate and adaptive immunity mediated by immune cells. T cell or macrophage dysfunction plays a particularly significant role in asthma pathogenesis. Furthermore, crosstalk between them continuously transmits proinflammatory or anti-inflammatory signals, causing the immune cell activation or repression in the immune response. Consequently, the imbalanced immune microenvironment is the major cause of the exacerbation of asthma. Here, we discuss the role of T cells, macrophages, and their interactions in asthma pathogenesis.

Targeting interleukin-17 in chronic inflammatory disease: A clinical perspective

Although many chronic inflammatory diseases share the feature of elevated IL-17 production, therapeutic targeting of IL-17 has vastly different clinical outcomes. Here the authors summarize the recent progress in understanding the protective and pathogenic role of the IL-23/IL-17 axis in preclinical models and human inflammatory diseases.

Chronic inflammatory diseases like psoriasis, Crohn’s disease (CD), multiple sclerosis (MS), rheumatoid arthritis (RA), and others are increasingly recognized as disease entities, where dysregulated cytokines contribute substantially to tissue-specific inflammation. A dysregulation in the IL-23/IL-17 axis can lead to inflammation of barrier tissues, whereas its role in internal organ inflammation remains less clear. Here we discuss the most recent developments in targeting IL-17 for the treatment of chronic inflammation in preclinical models and in patients afflicted with chronic inflammatory diseases.

The Role of Th17 Cells and IL-17 in Th2 Immune Responses of Allergic Conjunctivitis

Allergic conjunctivitis (AC) is a common allergic disease that is often associated with the onset of rhinitis or asthma. The incidence of AC has increased significantly in recent years possibly due to air pollution and climate warming. AC seriously affects patients' quality of life and work efficiency. Th (T-helper) 2 immune responses and type I hypersensitivity reactions are generally considered the basis of occurrence of AC. It has been found that new subpopulations of T-helper cells, Th17 cells that produce interleukin-17 (IL-17), play an important role in the Th2-mediated pathogenesis of conjunctivitis. Studies have shown that Th17 cells are involved in a variety of immune inflammation, including psoriasis, rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, and asthma. However, the role of Th17 and IL-17 in AC is unclear. This paper will focus on how T-helper 17 cells and interleukin-17 are activated in the Th2 immune response of allergic conjunctivitis and how they promote the Th2 immune response of AC.

PPARγ Deficiency in Carbon Nanotube-elicited Granulomatous Inflammation Promotes a Th17 Response to a Microbial Antigen

BACKGROUND

The pathological consequences of interaction between environmental carbon pollutants and microbial antigens have not been fully explored. We developed a murine model of multi-wall carbon nanotube (MWCNT)-elicited granulomatous disease which bears a striking resemblance to sarcoidosis, a human granulomatous disease. Because of reports describing lymphocyte reactivity to mycobacterial antigens in sarcoidosis patients, we hypothesized that addition of mycobacterial antigen (ESAT-6) to MWCNT might elicit activation in T cells.

METHODS

Macrophage-specific peroxisome-proliferator-activated receptor gamma (PPARγ) knock out (KO) mice were studied along with wild-type mice because our previous report indicated PPARγ deficiency in sarcoidosis alveolar macrophages. MWCNT+ESAT-6 were instilled into mice. Controls received vehicle (surfactant-PBS) or ESAT-6 and were evaluated 60 days post-instillation. As noted in our recent publication, lung tissues from PPARγ KO mice instilled with MWCNT+ESAT-6 yielded more intensive pathophysiology, with elevated fibrosis.

RESULTS

Inspection of mediastinal lymph nodes (MLN) revealed no granulomas but deposition of MWCNT. MLN cell counts were higher in PPARγ KO than in wild-type instilled with MWCNT+ESAT-6. Moreover, the CD4:CD8 T cell ratio, a major clinical metric for human disease, was increased in PPARγ KO mice. Bronchoalveolar lavage (BAL) cells from PPARγ KO mice instilled with MWCNT+ESAT-6 displayed increased Th17 cell markers (RORγt, IL-17A, CCR6) which associate with elevated fibrosis.

CONCLUSION

These findings suggest that PPARγ deficiency in macrophages may promote ESAT-6-associated T cell activation in the lung, and that the MWCNT+ESAT-6 model may offer new insights into pathways of lymphocyte-mediated sarcoidosis histopathology.

Arginine metabolic control of airway inflammation

Inducible nitric oxide synthase (iNOS) and arginase-2 (ARG2) share a common substrate, arginine. Higher expression of iNOS and exhaled NO are linked to airway inflammation in patients. iNOS deletion in animal models suggests that eosinophilic inflammation is regulated by arginine metabolism. Moreover, ARG2 is a regulator of Th2 response, as shown by the development of severe eosinophilic inflammation in ARG2-/- mice. However, potential synergistic roles of iNOS and ARG2 in asthma have not been explored. Here, we hypothesized that arginine metabolic fate via iNOS and ARG2 may govern airway inflammation. In an asthma cohort, ARG2 variant genotypes were associated with arginase activity. ARG2 variants with lower arginase activity, combined with levels of exhaled NO, identified a severe asthma phenotype. Airway inflammation was present in WT, ARG2-/-, iNOS-/-, and ARG2-/-/iNOS-/- mice but was greatest in ARG2-/-. Eosinophilic and neutrophilic infiltration in the ARG2-/- mice was abrogated in ARG2-/-/iNOS-/- animals. Similarly, angiogenic airway remodeling was greatest in ARG2-/- mice. Cytokines driving inflammation and remodeling were highest in lungs of asthmatic ARG2-/- mice and lowest in the iNOS-/-. ARG2 metabolism of arginine suppresses inflammation, while iNOS metabolism promotes airway inflammation, supporting a central role for arginine metabolic control of inflammation.

Lung Tissue Damage Associated with Allergic Asthma in BALB/c Mice Could Be Controlled with a Single Injection of Mesenchymal Stem Cells from Human Bone Marrow up to 14 d After Transplantation

Mesenchymal stem cell (MSC) research has demonstrated the potential of these cells to modulate lung inflammatory processes and tissue repair; however, the underlying mechanisms and treatment durability remain unknown. Here, we investigated the therapeutic potential of human bone marrow-derived MSCs in the inflammatory process and pulmonary remodeling of asthmatic BALB/c mice up to 14 d after transplantation. Our study used ovalbumin to induce allergic asthma in male BALB/c mice. MSCs were injected intratracheally in the asthma groups. Bronchoalveolar lavage fluid (BALF) was collected, and cytology was performed to measure the total protein, hydrogen peroxide (H2O2), and proinflammatory (IL-5, IL-13, and IL-17A) and anti-inflammatory (IL-10) interleukin (IL) levels. The lungs were removed for the histopathological evaluation. On day zero, the eosinophil and lymphochte percentages, total protein concentrations, and IL-13 and IL-17A levels in the BALF were significantly increased in the asthma group, proving the efficacy of the experimental model of allergic asthma. On day 7, the MSC-treated group exhibited significant reductions in the eosinophil, lymphocyte, total protein, H2O2, IL-5, IL-13, and IL-17A levels in the BALF, while the IL-10 levels were significantly increased. On day 14, the total cell numbers and lymphocyte, total protein, IL-13, and IL-17A levels in the BALF in the MSC-treated group were significantly decreased. A significant decrease in airway remodeling was observed on days 7 and 14 in almost all bronchioles, which showed reduced inflammatory infiltration, collagen deposition, muscle and epithelial thickening, and mucus production. These results demonstrate that treatment with a single injection of MSCs reduces the pathophysiological events occurring in an experimental model of allergic asthma by controlling the inflammatory process up to 14 d after transplantation.

Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Induces Interleukin-17 Production via Activation of the IRAK1-PI3K-p38MAPK-C/EBPβ/CREB Pathways

Porcine reproductive and respiratory syndrome virus (PRRSV) is widely prevalent in pigs, resulting in significant economic losses worldwide. A compelling impact of PRRSV infection is severe pneumonia. In the present study, we found that interleukin-17 (IL-17) was upregulated by PRRSV infection. Subsequently, we demonstrated that PI3K and p38MAPK signaling pathways were essential for PRRSV-induced IL-17 production as addition of phosphatidylinositol 3-kinase (PI3K) and p38MAPK inhibitors dramatically reduced IL-17 production. Furthermore, we show here that deleting the C/EBPβ and CREB binding motif in porcine IL-17 promoter abrogated its activation and that knockdown of C/EBPβ and CREB remarkably impaired PRRSV-induced IL-17 production, suggesting that IL-17 expression was dependent on C/EBPβ and CREB. More specifically, we demonstrate that PRRSV nonstructural protein 11 (nsp11) induced IL-17 production, which was also dependent on PI3K-p38MAPK-C/EBPβ/CREB pathways. We then show that Ser74 and Phe76 amino acids were essential for nsp11 to induce IL-17 production and viral rescue. In addition, IRAK1 was required for nsp11 to activate PI3K and enhance IL-17 expression by interacting with each other. Importantly, we demonstrate that PI3K inhibitor significantly suppressed IL-17 production and lung inflammation caused by HP-PRRSV in vivo, implicating that higher IL-17 level induced by HP-PRRSV might be associated with severe lung inflammation. These findings provide new insights onto the molecular mechanisms of the PRRSV-induced IL-17 production and help us further understand the pathogenesis of PRRSV infection.IMPORTANCE Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) associated with severe pneumonia has been one of the most important viral pathogens in pigs. IL-17 is a proinflammatory cytokine that might be associated with the strong inflammation caused by PRRSV. Therefore, we sought to determine whether PRRSV infection affects IL-17 expression, and if so, determine this might partially explain the underlying mechanisms for the strong inflammation in HP-PRRSV-infected pigs, especially in lungs. Here, we show that PRRSV significantly induced IL-17 expression, and we subsequently dissected the molecular mechanisms about how PRRSV regulated IL-17 production. Furthermore, we show that Ser74 and Phe76 in nsp11 were indispensable for IL-17 production and viral replication. Importantly, we demonstrated that PI3K inhibitor impaired IL-17 production and alleviated lung inflammation caused by HP-PRRSV infection. Our findings will help us for a better understanding of PRRSV pathogenesis.

Role of IL-17 in asthma pathogenesis and its implications for the clinic

Introduction: Asthma is a respiratory disorder typically characterized by T-helper type 2 (Th2) inflammation that is mediated by cytokines, including IL-4, IL-5, and IL-13. Pathophysiologically, airway inflammation involving prominent eosinophilia, elevated IgE synthesis, airway hyperresponsiveness, mucus hypersecretion, and airway remodeling manifest clinically in patients as wheezing, breathlessness, chest tightness and episodic coughing. However, the Th2 paradigm falls short in interpreting the full spectrum of asthma severity. Areas covered: Severe asthmatics represent a distinct phenotype with their mixed pattern of neutrophilic-eosinophilic infiltration and glucocorticoid insensitivity making them refractory to currently available therapies. Th17 cells and their signature cytokine, IL-17, have been implicated in the development of severe asthma. Here, we review the contribution of IL-17 in the pathological features of asthma, gathered from both human and animal studies published in Pubmed during the past 10 years, and briefly discuss the clinical implications of targeting IL-17 imbalance in asthmatic patients. Expert opinion: With advancement in our understanding of the role of IL-17 in asthma pathology, it is clear that IL-17 is a targetable pathway which may lead to improvement in clinical symptoms of asthma. However, further elucidation of the complex interactions unfurled by IL-17 is essential in the empirical development of effective therapeutic options for refractory asthmatics.

Therapeutic suppression of pulmonary neutrophilia and allergic airway hyperresponsiveness by a RORγt inverse agonist

Airway neutrophilia occurs in approximately 50% of patients with asthma and is associated with particularly severe disease. Unfortunately, this form of asthma is usually refractory to corticosteroid treatment, and there is an unmet need for new therapies. Pulmonary neutrophilic inflammation is associated with Th17 cells, whose differentiation is controlled by the nuclear receptor, RORγt. Here, we tested whether VTP-938, a selective inverse agonist of this receptor, can reduce disease parameters in animal models of neutrophilic asthma. When administered prior to allergic sensitization through the airway, the RORγt inverse agonist blunted allergen-specific Th17 cell development in lung-draining lymph nodes and attenuated allergen-induced production of IL-17. VTP-938 also reduced pulmonary production of IL-17 and airway neutrophilia when given during the allergen challenge of the model. Finally, in an environmentally relevant model of allergic responses to house dust extracts, VTP-938 suppressed production of IL-17 and neutrophilic inflammation, and also markedly diminished airway hyperresponsiveness. Together, these findings suggest that orally available inverse agonists of RORγt might provide an effective therapy to treat glucocorticoid-resistant neutrophilic asthma.

Mast cell degranulation impairs pneumococcus clearance in mice via IL-6 dependent and TNF-α independent mechanisms

Background

Mast cells participate in immune responses by releasing potent immune system modifiers via degranulation. Due to currently reported controversial roles of mast cells in Streptococcus pneumoniae infections, this study aimed to determine the role and mechanism of mast cells in clearing S. pneumoniae in mice.

Methods

In vivo mouse model of mast cell degranulation established by administration of C48/80 was evaluated for the influences of mast cell degranulation on bacterial colonization and inflammation. In vitro model was established to observe the influences of mast cell degranulation on phagocytic and bactericidal functions of neutrophils and macrophages. IL-6 null and TNF-α null mice on the C57BL/6 background were used to investigate the effects of inflammatory factors released by mast cell degranulation on bacterial clearance.

Results

Mast cell degranulation increased IL-6 and TNF-α levels and immune cell numbers in nasal lavage fluid, and inhibited the bactericidal function of macrophages and neutrophils in vitro. It decreased the number of neutrophils and macrophages recruited to respiratory tract after S. pneumoniae challenge and inhibited the clearance of S. pneumoniae in mice. After pretreatment with C48/80, S. pneumoniae loads were significantly lower in IL-6 null mice than in wild type mice, while no differences were observed between TNF-α null and wild type mice.

Conclusions

Mast cell degranulation can cause inflammation and impair immune cell recruitment to respiratory tract after S. pneumoniae challenge. Products of mast cell degranulation including IL-6 decreased the bactericidal function of neutrophils and macrophages. Through these mechanisms, mast cell degranulation inhibited clearance of S. pneumoniae in mice.

Upregulated IGF‑1 in the lungs of asthmatic mice originates from alveolar macrophages

Asthma is characterized by inflammation and remodeling of the airways. Insulin‑like growth factor-1 (IGF‑1) serves an important role in the repair of lung tissue injury and airway remodeling by elevating collagen and elastin content, increasing the thickness of smooth muscle and promoting the proliferation of lung epithelial and interstitial cells, as well as fibroblasts; however, the content of IGF‑1 and its cellular origin in the lungs of patients with asthma remain unknown. In the present study, a mouse model of asthma was constructed. Following isolation of alveolar macrophages (AMs), the content of IGF‑1 in lung tissue and bronchoalveolar lavage fluid (BALF) was detected by ELISA. The proliferation and phagocytosis of alveolar epithelial cells (AECs) stimulated by IGF‑1 were detected by Cell Counting Kit‑8 method and flow cytometry, respectively. In the present study, IGF‑1 was upregulated in the lung tissues of asthmatic mice, and the content of IGF‑1 in BALF was also elevated. Depletion of AMs by treating mice with 2‑chloroadenosine via nose dripping reversed the increase of IGF‑1 by 80% in lung tissues and by ~100% in BALF of asthmatic mice, suggesting that elevated IGF‑1 in asthmatic mice predominantly originated from AMs. As IGF‑1 promotes the proliferation and phagocytosis of AECs, AM‑derived IGF‑1 may serve an important role in the regulation of airway inflammation and remodeling in asthmatic mice.

IL-23-induced macrophage polarization and its pathological roles in mice with imiquimod-induced psoriasis

Macrophages acquire distinct phenotypes during tissue stress and inflammatory responses. Macrophages are roughly categorized into two different subsets named inflammatory M1 and anti-inflammatory M2 macrophages. We herein identified a unique pathogenic macrophage subpopulation driven by IL-23 with a distinct gene expression profile including defined types of cytokines. The freshly isolated resting mouse peritoneal macrophages were stimulated with different cytokines in vitro, the expression of cytokines and chemokines were detected by microarray, real-time PCR, ELISA and multiple colors flow cytometry. Adoptive transfer of macrophages and imiquimod-induced psoriasis mice were used. In contrast to M1- and M2-polarized macrophages, IL-23-treated macrophages produce large amounts of IL-17A, IL-22 and IFN-γ. Biochemical and molecular studies showed that IL-23 induces IL-17A expression in macrophages through the signal transducer and activator of transcription 3 (STAT3)-retinoid related orphan receptor-γ T (RORγT) pathway. T-bet mediates the IFN-γ production in IL-23-treated macrophages. Importantly, IL-23-treated macrophages significantly promote the dermatitis pathogenesis in a psoriasis-like mouse model. IL-23-treated resting macrophages express a distinctive gene expression prolife compared with M1 and M2 macrophages. The identification of IL-23-induced macrophage polarization may help us to understand the contribution of macrophage subpopulation in Th17-cytokines-related pathogenesis.

Effect of the anti-IL-17 antibody on allergic inflammation in an obesity-related asthma model

BACKGROUND/AIMS

The co-occurrence of obesity aggravates asthma symptoms. Diet-induced obesity increases helper T cell (TH) 17 cell differentiation in adipose tissue and the spleen. The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pravastatin can potentially be used to treat asthma in obese patients by inhibiting interleukin 17 (IL-17) expression. This study investigated the combined effects of pravastatin and anti-IL-17 antibody treatment on allergic inflammation in a mouse model of obesity-related asthma.

METHODS

High-fat diet (HFD)-induced obesity was induced in C57BL/6 mice with or without ovalbumin (OVA) sensitization and challenge. Mice were administered the anti-IL-17 antibody, pravastatin, or both, and pathophysiological and immunological responses were analyzed.

RESULTS

HFD exacerbated allergic airway inflammation in the bronchoalveolar lavage fluid of HFD-OVA mice as compared to OVA mice. Blockading of the IL-17 in the HFD-OVA mice decreased airway hyper-responsiveness (AHR) and airway inflammation compared to the HFD-OVA mice. Moreover, the administration of the anti-IL-17 antibody decreased the leptin/adiponectin ratio in the HFD-OVA but not the OVA mice. Co-administration of pravastatin and anti-IL-17 inhibited airway inflammation and AHR, decreased goblet cell numbers, and increased adipokine levels in obese asthmatic mice.

CONCLUSION

These results suggest that the IL-17-leptin/adiponectin axis plays a key role in airway inflammation in obesity-related asthma. Our findings suggest a potential new treatment for IL-17 as a target that may benefit obesity-related asthma patients who respond poorly to typical asthma medications.

Aspergillus fumigatus conidia stimulate lung epithelial cells (TC-1 JHU-1) to produce IL-12, IFNγ, IL-13 and IL-17 cytokines: Modulatory effect of propolis extract

Aspergillus fumigatus conidia are the most prevalent indoors fungal allergens. The interaction between Aspergillus antigens and lung epithelial cells (LECs) result in innate immune functions. The association between Aspergillus conidia and allergic reactions, like allergic bronchopulmonary aspergillosis (ABPA) and asthma have been repeatedly reported. Since conventional therapies for allergy and asthma are limited, finding new promising treatments are inevitable. This study was designed to evaluate the effect of A. fumigatus conidia on IL-12, IFNγ, IL-13 and IL-17 release from mouse LECs and to investigate the effect of propolis on cytokines modulation. Cells were divided to two groups, one was exposed to 3×10⁴ conidia of Aspergillus fumigatus and another group was treated by propolis (25μg/mL) as well as exposed to A. fumigatus conidia. Cytokines IL-13, IL-12, IFNγ and IL-17 were measured at times 0, 6 and 12hours after exposure using ELISA assay. The results indicated that A. fumigatus could increase the release of the cytokines with IL-13 and IL-17 being the most affected ones whilst treatment with propolis decreased the effects of A. fumigatus on IL-13 and IL-17 production. The results showed that propolis has down regulatory effects on Th2 cytokine, IL-13, and IL-17 production, whereas it caused a significant induction of IL-12, as an important Th1 cytokines by LECs. With respect to the obtained results, propolis extract might be contributed to decrease Th2 responses in allergic asthma phenomenon. However more investigations must be done in future to fully understand its efficacy.

Complement C3 Produced by Macrophages Promotes Renal Fibrosis via IL-17A Secretion

Complement synthesis in cells of origin is strongly linked to the pathogenesis and progression of renal disease. Multiple studies have examined local C3 synthesis in renal disease and elucidated the contribution of local cellular sources, but the contribution of infiltrating inflammatory cells remains unclear. We investigate the relationships among C3, macrophages and Th17 cells, which are involved in interstitial fibrosis. Here, we report that increased local C3 expression, mainly by monocyte/macrophages, was detected in renal biopsy specimens and was correlated with the severity of renal fibrosis (RF) and indexes of renal function. In mouse models of UUO (unilateral ureteral obstruction), we found that local C3 was constitutively expressed throughout the kidney in the interstitium, from which it was released by F4/80⁺macrophages. After the depletion of macrophages using clodronate, mice lacking macrophages exhibited reductions in C3 expression and renal tubulointerstitial fibrosis. Blocking C3 expression with a C3 and C3aR inhibitor provided similar protection against renal tubulointerstitial fibrosis. These protective effects were associated with reduced pro-inflammatory cytokines, renal recruitment of inflammatory cells, and the Th17 response. in vitro, recombinant C3a significantly enhanced T cell proliferation and IL-17A expression, which was mediated through phosphorylation of ERK, STAT3, and STAT5 and activation of NF-kB in T cells. More importantly, blockade of C3a by a C3aR inhibitor drastically suppressed IL-17A expression in C3a-stimulated T cells. We propose that local C3 secretion by macrophages leads to IL-17A-mediated inflammatory cell infiltration into the kidney, which further drives fibrogenic responses. Our findings suggest that inhibition of the C3a/C3aR pathway is a novel therapeutic approach for obstructive nephropathy.