Nanoplastics Penetrate Human Bronchial Smooth Muscle and Small Airway Epithelial Cells and Affect Mitochondrial Metabolism.

Micro- and nanoplastic particles, including common forms like polyethylene and polystyrene, have been identified as relevant pollutants, potentially causing health problems in living organisms. The mechanisms at the cellular level largely remain to be elucidated. This study aims to visualize nanoplastics in bronchial smooth muscle (BSMC) and small airway epithelial cells (SAEC), and to assess the impact on mitochondrial metabolism. Healthy and asthmatic human BSMC and SAEC in vitro cultures were stimulated with polystyrene nanoplastics (PS-NPs) of 25 or 50 nm size, for 1 or 24 h. Live cell, label-free imaging by holotomography microscopy and mitochondrial respiration and glycolysis assessment were performed. Furthermore, 25 and 50 nm NPs were shown to penetrate SAEC, along with healthy and diseased BSMC, and they impaired bioenergetics and induce mitochondrial dysfunction compared to cells not treated with NPs, including changes in oxygen consumption rate and extracellular acidification rate. NPs pose a serious threat to human health by penetrating airway tissues and cells, and affecting both oxidative and glycolytic metabolism.

Green tea extract suppresses airway inflammation via oxidative stress-driven MAPKs/MMP-9 signaling in asthmatic mice and human airway epithelial cells.

Introduction: The anti-inflammatory effect of green tea extract (GTE) has been confirmed in asthmatic mice, however, the pharmacological mechanism is not fully elucidated. Methods: To investigate the therapeutic efficacy of GTE in asthma and identify specific pathways, murine model of allergic asthma was established by ovalbumin (OVA) sensitization and the challenge for 4 weeks, with oral treatment using GTE and dexamethasone (DEX). Inflammatory cell counts, cytokines, OVA-specific IgE, airway hyperreactivity, and antioxidant markers in the lung were evaluated. Also, pulmonary histopathological analysis and western blotting were performed. In vitro, we established the model by stimulating the human airway epithelial cell line NCI-H292 using lipopolysaccharide, and treating with GTE and mitogen-activated protein kinases (MAPKs) inhibitors. Results: The GTE100 and GTE400 groups showed a decrease in airway hyperresponsiveness and the number of inflammatory cells in the bronchoalveolar lavage fluid (BALF) compared to the OVA group. GTE treatment also reduced interleukin (IL)-13, IL-5, and IL-4 levels in the BALF, and OVA-specific immunoglobulin E levels in the serum compared to those in the OVA group. GTE treatment decreased OVA-induced mucus secretion and airway inflammation. In addition, GTE suppressed the oxidative stress, and phosphorylation of MAPKs, which generally occurs after exposure to OVA. GTE administration also reduced matrix metalloproteinase-9 activity and protein levels. Conclusion: GTE effectively inhibited asthmatic respiratory inflammation and mucus hyperproduction induced by OVA inhalation. These results suggest that GTE has the potential to be used for the treatment of asthma.

Iron controls the development of airway hyperreactivity by regulating ILC2 metabolism and effector function.

Group 2 innate lymphoid cells (ILC2s) rapidly induce a type 2 inflammation in the lungs in response to allergens. Here, we focused on the role of iron, a critical nutritional trace element, on ILC2 function and asthma pathogenesis. We found that transferrin receptor 1 (TfR1) is rapidly up-regulated and functional during ILC2 activation in the lungs, and blocking transferrin uptake reduces ILC2 expansion and activation. Iron deprivation reprogrammed ILC2 metabolism, inducing a HIF-1α-driven up-regulation of glycolysis and inhibition of oxidative mitochondrial activity. Consequently, we observed that in vivo iron chelation or induction of hypoferremia reduced the development of airway hyperreactivity in experimental models of ILC2-driven allergic asthma. Human circulating ILC2s rapidly induced TfR1 during activation, whereas inhibition of iron uptake or iron deprivation reduced effector functions. Last, we found a negative relationship between circulating ILC2 TfR1 expression and airway function in cohorts of patients with asthma. Collectively, our studies define cellular iron as a critical regulator of ILC2 function.

Dimethyl fumarate alleviates allergic asthma by strengthening the Nrf2 signaling pathway in regulatory T cells.

Allergic asthma is a widely prevalent inflammatory condition affecting people across the globe. T cells and their secretory cytokines are central to the pathogenesis of allergic asthma. Here, we have evaluated the anti-inflammatory impact of dimethyl fumarate (DMF) in allergic asthma with more focus on determining its effect on T cell responses in allergic asthma. By utilizing the ovalbumin (OVA)-induced allergic asthma model, we observed that DMF administration reduced the allergic asthma symptoms and IgE levels in the OVA-induced mice model. Histopathological analysis showed that DMF treatment in an OVA-induced animal model eased the inflammation in the nasal and bronchial tissues, with a particular decrease in the infiltration of immune cells. Additionally, RT-qPCR analysis exhibited that treatment of DMF in an OVA-induced model reduced the expression of inflammatory cytokine (IL4, IL13, and IL17) while augmenting anti-inflammatory IL10 and Foxp3 (forkhead box protein 3). Mechanistically, we found that DMF increased the expression of Foxp3 by exacerbating the expression of nuclear factor E2-related factor 2 (Nrf2), and the in-vitro activation of Foxp3+ Tregs leads to an escalated expression of Nrf2. Notably, CD4-specific Nrf2 deletion intensified the allergic asthma symptoms and reduced the in-vitro iTreg differentiation. Meanwhile, DMF failed to exert protective effects on OVA-induced allergic asthma in CD4-specific Nrf2 knock-out mice. Overall, our study illustrates that DMF enhances Nrf2 signaling in T cells to assist the differentiation of Tregs, which could improve the anti-inflammatory immune response in allergic asthma.

Interleukin-13 Treatment of Living Lung Tissue Model Alters the Metabolome and Proteome-A Nano-DESI MS Metabolomics and Shotgun Proteomics Study.

Asthma is a chronic respiratory disease with one of the largest numbers of cases in the world; thus, constant investigation and technical development are needed to unravel the underlying biochemical mechanisms. In this study, we aimed to develop a nano-DESI MS method for the in vivo characterization of the cellular metabolome. Using air-liquid interface (ALI) cell layers, we studied the role of Interleukin-13 (IL-13) on differentiated lung epithelial cells acting as a lung tissue model. We demonstrate the feasibility of nano-DESI MS for the in vivo monitoring of basal-apical molecular transport, and the subsequent endogenous metabolic response, for the first time. Conserving the integrity of the ALI lung-cell layer enabled us to perform temporally resolved metabolomic characterization followed by "bottom-up" proteomics on the same population of cells. Metabolic remodeling was observed upon histamine and corticosteroid treatment of the IL-13-exposed lung cell monolayers, in correlation with alterations in the proteomic profile. This proof of principle study demonstrates the utility of in vivo nano-DESI MS for characterizing ALI tissue layers, and the new markers identified in our study provide a good starting point for future, larger-scale studies.

A common polymorphism in the Intelectin-1 gene influences mucus plugging in severe asthma.

By incompletely understood mechanisms, type 2 (T2) inflammation present in the airways of severe asthmatics drives the formation of pathologic mucus which leads to airway mucus plugging. Here we investigate the molecular role and clinical significance of intelectin-1 (ITLN-1) in the development of pathologic airway mucus in asthma. Through analyses of human airway epithelial cells we find that ITLN1 gene expression is highly induced by interleukin-13 (IL-13) in a subset of metaplastic MUC5AC+ mucus secretory cells, and that ITLN-1 protein is a secreted component of IL-13-induced mucus. Additionally, we find ITLN-1 protein binds the C-terminus of the MUC5AC mucin and that its deletion in airway epithelial cells partially reverses IL-13-induced mucostasis. Through analysis of nasal airway epithelial brushings, we find that ITLN1 is highly expressed in T2-high asthmatics, when compared to T2-low children. Furthermore, we demonstrate that both ITLN-1 gene expression and protein levels are significantly reduced by a common genetic variant that is associated with protection from the formation of mucus plugs in T2-high asthma. This work identifies an important biomarker and targetable pathways for the treatment of mucus obstruction in asthma.

KLF5-mediated pyroptosis of airway epithelial cells leads to airway inflammation in asthmatic mice through the miR-182-5p/TLR4 axis.

Asthma is viewed as an airway disease and an inflammatory condition. This study aims to reveal the role of Kruppel-like factor 5 (KLF5)-mediated pyroptosis of airway epithelial cells in airway inflammation in asthma. The asthmatic mouse model was established. The mice were infected with the lentivirus containing sh-KLF5, antagomiR-182-5p, and pc-Toll-like receptor 4 (TLR4). Airway hyperresponsiveness was measured, and the cells in bronchoalveolar lavage fluid (BALF) were sorted and counted. The expression levels of interleukin (IL)-4/IL-13/IL-6/IL-18/IL-1ß/NOD-like receptor family pyrin domain containing 3 (NLRP3)/N-gasdermin D (GSDMD-N)/cleaved caspase-1 were detected. The pathological changes in lung tissue were observed. The enrichment of KLF5 in the miR-182-5p promoter region was measured. The binding relationship among KLF5, miR-182-5p, and TLR4 were analyzed. KLF5 was highly expressed in asthmatic mice. Silencing KLF5 improved airway resistance and lung dynamic compliance, reduced the cells in BALF and the expression of IL-4/IL-13/IL-6/NLRP3/GSDMD-N/cleaved caspase-1/IL-18/IL-1ß, and alleviated the pathological changes. Mechanistically, KLF5 bonded to the miR-182-5p promoter to inhibit miR-182-5p expression, and miR-182-5p inhibited TLR4. Silencing miR-182-5p or TLR4 overexpression reversed the improvement of silencing KLF5 on airway inflammation and pyroptosis in asthmatic mice. In conclusion, KLF5 inhibited miR-182-5p to promote TLR4 expression, thus aggravating pyroptosis and airway inflammation in asthmatic mice.

Stigmasterol alleviates airway inflammation in OVA-induced asthmatic mice via inhibiting the TGF-ß1/Smad2 and IL-17A signaling pathways.

Stigmasterol is a common dietary phytosterol with high nutritional value and physiological activity. In this study, we evaluated the effects of stigmasterol on inflammatory cytokines and the TGF-ß1/Smad2 and IL-17A signaling pathway in an ovalbumin (OVA)-induced asthma mouse model. Stigmasterol treatment improved airway remodeling. In addition, it significantly attenuated the symptoms of asthma attacks, reduced the number of macrophages, lymphocytes, neutrophils, and eosinophils in BALF and inflammatory cytokines, including IL-1ß, IL-5, IL-6, and IL-13. It further decreased the level of IL-17A in BALF, serum and spleen. Spleen single-cell suspension analysis via flow cytometry showed that IL-17A level was consistent with the results obtained in BALF, serum and spleen. Stigmasterol decreased the protein expression levels of TGF-ß, p-Smad2 and IL-17A in the spleen, by increasing the protein expression level of IL-10. After 24 h of co-culture of TGF-ß, IL-6 and stigmasterol, the level of IL-17 in CD4+ T cell supernatant was lower relative to levels in the group without stigmasterol. Meanwhile, stigmasterol treatment attenuated the expression level of TGF- ß, p-Smad2 and IL-17A proteins in CD4+ T cells and enhanced the expression levels of IL-10 protein. These data suggested that stigmasterol inhibited the TGF-ß1/Smad2 and IL-17A signaling pathway to achieve anti-asthmatic effects in the OVA-induced asthma mouse model. Collectively, the results of this study are that stigmasterol has achieved preliminary efficacy in the non-clinical laboratory, further studies are needed to consider the clinical application of stigmasterol.

TFEB regulates dendritic cell antigen presentation to modulate immune balance in asthma.

OBJECTIVE: Asthma stands as one of the most prevalent chronic respiratory conditions in children, with its pathogenesis tied to the actived antigen presentation by dendritic cells (DCs) and the imbalance within T cell subgroups. This study seeks to investigate the role of the transcription factor EB (TFEB) in modulating the antigen presentation process of DCs and its impact on the differentiation of T cell subgroups. METHODS: Bone marrow dendritic cells (BMDCs) were activated using house dust mites (HDM) and underwent RNA sequencing (RNA-seq) to pinpoint differentially expressed genes. TFEB mRNA expression levels were assessed in the peripheral blood mononuclear cells (PBMCs) of both healthy children and those diagnosed with asthma. In an asthma mouse model induced by HDM, the TFEB expression in lung tissue DCs was evaluated. Further experiments involved LV-shTFEB BMDCs co-cultured with T cells to explore the influence of TFEB on DCs' antigen presentation, T cell subset differentiation, and cytokine production. RESULTS: Transcriptomic sequencing identified TFEB as a significantly differentially expressed gene associated with immune system pathways and antigen presentation. Notably, TFEB expression showed a significant increase in the PBMCs of children diagnosed with asthma compared to healthy counterparts. Moreover, TFEB exhibited heightened expression in lung tissue DCs of HDM-induced asthmatic mice and HDM-stimulated BMDCs. Silencing TFEB resulted in the downregulation of MHC II, CD80, CD86, and CD40 on DCs. This action reinstated the equilibrium among Th1/Th2 and Th17/Treg cell subgroups, suppressed the expression of pro-inflammatory cytokines like IL-4, IL-5, IL-13, and IL-17, while augmenting the expression of the anti-inflammatory cytokine IL-10. CONCLUSION: TFEB might have a vital role in asthma's development by impacting the antigen presentation of DCs, regulating T cell subgroup differentiation, and influencing cytokine secretion. Its involvement could be pivotal in rebalancing the immune system in asthma. These research findings could potentially unveil novel therapeutic avenues for treating asthma.

In vivo determination of the anti-inflammatory and antioxidant effects of the aqueous extract of Syzygium aromaticum (clove) in an asthmatic rat model.

Asthma is a chronic inflammatory disease of the airways strongly associated with interleukin-4 (IL-4), a cytokine that mediates and regulates various immune responses, including allergic reactions. This study aimed to evaluate the anti-inflammatory and antioxidant effects of an Aqueous Extract of Clove (AEC) Syzygium aromaticum on the lungs and erythrocytes of an experimental asthma model in Wistar rats. For this purpose, four groups of male rats were examined: control, sensitized with ovalbumin (OVA), treated with AEC, and treated with a combination of OVA/AEC. After treatment, the antioxidant effect was determined by measuring the malondialdehyde (MDA), glutathione peroxidase (GPx), glutathione (GSH), and catalase (CAT) levels. The anti-inflammatory effect was determined by measuring IL-4 levels by performing enzyme-linked immunosorbent assay (ELISA) using serum, lung, and bronchoalveolar lavage fluid (BALF) samples. A significant reduction (p ≤ 0.05) in the MDA levels and a significant increase (p ≤ 0.05) in the levels of GPx and CAT were observed in the lungs of rats treated with cloves. However, no statistically significant variation was observed in GSH levels. In erythrocytes, no statistically significant differences were observed between the experimental batches. Regarding the anti-inflammatory effect, the administration of S. aromaticum extract to sensitized rats resulted in a recovery in the levels of total proteins and IL-4 and a decrease in the three compartments studied (lungs, serum, and bronchoalveolar liquid). These results were confirmed by microscopic examination of lung histological sections. Overall, these findings confirmed that the AEC has anti-inflammatory and antioxidant effects.

PI3Kγδ inhibition suppresses key disease features in a rat model of asthma.

BACKGROUND: Two isoforms of Phosphoinositide 3-kinase (PI3K), p110γ and p110δ, are predominantly expressed in leukocytes and represent attractive therapeutic targets for the treatment of allergic asthma. The study aim was to assess the impact of administration of an inhaled PI3Kγδ inhibitor (AZD8154) in a rat model of asthma. METHODS: Firstly, we checked that the tool compound, AZD8154, inhibited rat PI3K γ & δ kinases using rat cell-based assays. Subsequently, a time-course study was conducted in a rat model of asthma to assess PI3K activity in the lung and how it is temporally associated with other key transcription pathways and asthma like features of the model. Finally, the impact on lung dosed AZD8154 on target engagement, pathway specificity, airway inflammation and lung function changes was assessed. RESULTS: Data showed that AZD8154 could inhibit rat PI3K γ & δ isoforms and, in a rat model of allergic asthma the PI3K pathway was activated in the lung. Intratracheal administration of AZD8154 caused a dose related suppression PI3K pathway activation (reduction in pAkt) and unlike after budesonide treatment, STAT and NF-κB pathways were not affected by AZD8154. The suppression of the PI3K pathway led to a marked inhibition of airway inflammation and reduction in changes in lung function. CONCLUSION: These data show that a dual PI3Kγδ inhibitor suppress key features of disease in a rat model of asthma to a similar degree as budesonide and indicate that dual PI3Kγδ inhibition may be an effective treatment for people suffering from allergic asthma.

Studying of anti-inflammatory and antioxidant effects of tectorigenin in ovalbumin-induced asthma mice models.

BACKGROUND: Allergic asthma is an important respiratory system problem characterized by airway inflammation, breathlessness, and bronchoconstriction. Allergic asthma and its outcomes are triggered by type 2 allergic immune responses. Tectorigenin is a methoxy-isoflavone with anti-inflammatory effects. In this study, we investigated the effects of tectorigenin on the pathophysiology of allergic asthma in an animal model. METHODS: Asthmatic mice were treated with tectorigenin. Then airway hyperresponsiveness (AHR), eosinophil percentage, levels of interleukin (IL)-33, IL-25, IL-13, IL-5, IL-4, total and ovalbumin (OVA)-specific immunoglobulin (Ig)E, and lung histopathology were evaluated. RESULT: Tectorigenin significantly (P 〈 0.05) reduced eosinophil infiltration (41 ± 7%) in the broncho-alveolar lavage fluid (BALF), serum IL-5 level (41 ± 5, pg/mL), and bronchial and vascular inflammation (scores of 1.3 ± 0.2 and 1.1 ± 0.3, respectively) but had no significant effects on AHR, serum levels of IL-33, -25, -13, and -4 (403 ± 24, 56 ± 7, 154 ± 11, and 89 ± 6 pg/mL, respectively), total and OVA-specific IgE (2684 ± 265 and 264 ± 19 ng/mL, respectively), goblet cell hyperplasia, and mucus production. CONCLUSION: Tectorigenin could control inflammation and the secretion of inflammatory mediators of asthma, so it can be regarded as a potential antiasthma treatment with the ability to control eosinophilia-related problems.

Inflammation and Organic Cation Transporters Novel (OCTNs).

Inflammation is a physiological condition characterized by a complex interplay between different cells handled by metabolites and specific inflammatory-related molecules. In some pathological situations, inflammation persists underlying and worsening the pathological state. Over the years, two membrane transporters namely OCTN1 (SLC22A4) and OCTN2 (SLC22A5) have been shown to play specific roles in inflammation. These transporters form the OCTN subfamily within the larger SLC22 family. The link between these proteins and inflammation has been proposed based on their link to some chronic inflammatory diseases such as asthma, Crohn's disease (CD), and rheumatoid arthritis (RA). Moreover, the two transporters show the ability to mediate the transport of several compounds including carnitine, carnitine derivatives, acetylcholine, ergothioneine, and gut microbiota by-products, which have been specifically associated with inflammation for their anti- or proinflammatory action. Therefore, the absorption and distribution of these molecules rely on the presence of OCTN1 and OCTN2, whose expression is modulated by inflammatory cytokines and transcription factors typically activated by inflammation. In the present review, we wish to provide a state of the art on OCTN1 and OCTN2 transport function and regulation in relationships with inflammation and inflammatory diseases focusing on the metabolic signature collected in different body districts and gene polymorphisms related to inflammatory diseases.

Multifactorial Causes and Consequences of TLSP Production, Function, and Release in the Asthmatic Airway.

Disruption of the airway epithelium triggers a defensive immune response that begins with the production and release of alarmin cytokines. These epithelial-derived alarmin cytokines, including thymic stromal lymphopoietin (TSLP), are produced in response to aeroallergens, viruses, and toxic inhalants. An alarmin response disproportionate to the inhaled trigger can exacerbate airway diseases such as asthma. Allergens inhaled into previously sensitized airways are known to drive a T2 inflammatory response through the polarization of T cells by dendritic cells mediated by TSLP. Harmful compounds found within air pollution, microbes, and viruses are also triggers causing airway epithelial cell release of TSLP in asthmatic airways. The release of TSLP leads to the development of inflammation which, when unchecked, can result in asthma exacerbations. Genetic and inheritable factors can contribute to the variable expression of TSLP and the risk and severity of asthma. This paper will review the various triggers and consequences of TSLP release in asthmatic airways.

Anti-inflammatory effect of Trichospira verticillata via suppression of the NLRP3 inflammasome in neutrophilic asthma.

Trichospira verticillata is an annual herb that belongs to the family Asteraceae. Trichospira verticillata extract (TVE) elicits anti-plasmodial activity; however, there has been no detailed report about its anti-inflammatory effects and molecular mechanisms. In addition, herbal plants exhibit anti-inflammatory effects by suppressing the NLRP3 inflammasome. Therefore, the primary goal of this study was to examine the effects of TVE on NLRP3 inflammasome activation by measuring interleukin-1ß (IL-1ß) secretion. We treated lipopolysaccharides (LPS)-primed J774A.1 and THP-1 cells with TVE, which attenuated NLRP3 inflammasome activation. Notably, TVE did not affect nuclear factor-kappa B (NF-κB) signalling or intracellular reactive oxygen species (ROS) production and potassium efflux, suggesting that it inactivates the NLRP3 inflammasome via other mechanisms. Moreover, TVE suppressed the formation of apoptosis-associated speck-like protein (ASC) speck and oligomerization. Immunoprecipitation data revealed that TVE reduced the binding of NLRP3 to NIMA-related kinase 7 (NEK7), resulting in reduced ASC oligomerization and speck formation. Moreover, TVE alleviated neutrophilic asthma (NA) symptoms in mice. This study demonstrates that TVE modulates the binding of NLPR3 to NEK7, thereby reporting novel insights into the mechanism by which TVE inhibits NLRP3 inflammasome. These findings suggest TVE as a potential therapeutic of NLRP3 inflammasome-mediated diseases, particularly NA.

Effect of overweight/obesity on relationship between fractional exhaled nitric oxide and airway hyperresponsiveness in Chinese elderly patients with asthma.

Purpose: This retrospective study investigates the influence of overweight and obesity status on pulmonary function, airway inflammatory markers, and airway responsiveness in elderly asthma patients. Methods: Patients with asthma older than 65 years old who completed a bronchial provocation test (BPT) or bronchial dilation test (BDT) and a fractional exhaled nitric oxide (FeNO) test between December 2015 and June 2020 were identified retrospectively for this study. All of the patients were categorized into overweight/obesity and non-obesity groups based on their BMI. Pulmonary function test (PFT) and FeNO measurements were accomplished according to the 2014 recommendations of the Chinese National Guidelines of Pulmonary Function Test and American Thoracic Society/European Respiratory Society recommendations, respectively. Results: A total of 136 patients with an average age of 71.2 ± 5.40 years were identified. The average BMI was 23.8 ± 3.63, while the value of FeNO was 42.3 ± 38.4 parts per billion (ppb). In contrast to the non-obesity group, which had a value of 48.8 ± 43.1 ppb for FeNO, the overweight/obesity group had a significant lower value of 35.4 ± 31.4 ppb. There was no significant difference in the proportion of individuals with high airway hyperresponsiveness between the overweight/obesity and non-obesity groups (96 patients in total). Multiple linear regression analysis established an inverse correlation between FeNO and Provocation concentration causing a 20% fall in FEV1(PC20) but excluded significant relationships with age and BMI. The model's R is 0.289, and its p value is 0.045. Conclusion: The elderly Chinese Han asthmatics with overweight/obesity had lower FeNO levels than those with non-obese according to our findings. In addition, the FeNO level was inversely correlated between FeNO levels and PC20 in elderly asthmatics.

Ferroptosis contributes to airway epithelial E-cadherin disruption in a mixed granulocytic asthma mouse model.

Aberrant expression of airway epithelial E-cadherin is a key feature of asthma, yet the underlying mechanisms are largely unknown. Ferroptosis is a novel form of regulated cell death involved in asthma pathogenesis. This study was aimed to evaluate the role of ferroptosis and to investigate whether ferroptosis mediates E-cadherin disruption in mixed granulocyte asthma (MGA). Two murine models of MGA were established using toluene diisocyanate (TDI) or ovalbumin with Complete Freund's Adjuvant (OVA/CFA). Specific antagonists of ferroptosis, including Liproxstatin-1 (Lip-1) and Ferrostatin-1 (Fer-1) were given to the mice. The allergen-exposed mice displayed markedly shrunk mitochondria in the airway epithelia, with decreased volume and denser staining accompanied by down-regulated GPX4 as well as up-regulated FTH1 and malondialdehyde, which are markers of ferroptosis. Decreased pulmonary expression of E-cadherin was also observed, with profound loss of membrane E-cadherin in the airway epithelia, as well as increased secretion of sE-cadherin. Treatment with Lip-1 not only showed potent protective effects against the allergen-induced airway hyperresponsiveness and inflammatory responses, but also rescued airway epithelial E-cadherin expression and inhibited the release of sE-cadherin. Taken together, our data demonstrated that ferroptosis mediates airway epithelial E-cadherin dysfunction in MGA.

Free fatty acid receptor 4 (FFA4) activation attenuates obese asthma by suppressing adiposity and resolving metaflammation.

Obese asthma is recognized to have different asthma phenotypes. N-3 polyunsaturated fatty acids (PUFAs) have shown beneficial effects in obesity and metabolic syndrome. Free fatty acid receptor 4 (FFA4, also known as GPR120) is a receptor for n-3 PUFAs. In the present study, we investigated whether FFA4 activation ameliorates high-fat diet (HFD)-induced obese asthma. We investigated whether FFA4 activation ameliorates obese asthma using an FFA4 agonist, compound A (CpdA), in combination with FFA4 wild-type (WT) and knock-out (KO) mice. Administration of an FFA4 agonist, compound A (CpdA, 30 mg/kg), suppressed HFD-induced weight gain, adiposity, and airway hypersensitivity (AHR), and increased immune cell infiltration in an FFA4-dependent manner. Histological analysis revealed that CpdA treatment suppressed HFD-induced mucus hypersecretion, inflammation, and fibrosis in an FFA4-dependent manner. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) showed an HFD-induced increase in the mRNA levels of pro-inflammatory cytokines in the lungs and gonadal white adipose tissue, whereas CpdA inhibited this increase in an FFA4-dependent manner. In the fluorescence-activated cell sorting (FACS) analysis, HFD induced an increase in the lung innate lymphoid cells (ILC) ILC1, ILC2, and ILC3; however, CpdA reversed this increase. In addition, HFD induced an increase in the pro-inflammatory M1 macrophage population and a decrease in the anti-inflammatory M2 macrophage population in the lungs, whereas CpdA treatment reversed these changes. The present study suggests that FFA4 activation may have therapeutic potential in obese asthma.

Stimulatory effect of methylglyoxal on capsaicin-sensitive lung vagal afferents in rats: role of TRPA1.

Methylglyoxal (MG), a reactive metabolic byproduct of glycolysis, is a causative of painful diabetic neuropathy. Patients with diabetes are associated with more frequent severe asthma exacerbation. Stimulation of capsaicin-sensitive lung vagal (CSLV) afferents may contribute to the pathogenesis of hyperreactive airway diseases such as asthma. However, the possibility of the stimulatory effect of MG on CSLV afferents and the underlying mechanisms remain unknown. Our results showed that intravenous injection of MG (25 mg/kg, MG25) in anesthetized, spontaneously breathing rats elicited pulmonary chemoreflexes characterized by apnea, bradycardia, and hypotension. The MG-induced apneic response was reproducible and dose dependent. MG25 no longer evoked these reflex responses after perineural capsaicin treatment of both cervical vagi to block C-fibers' conduction, suggesting that the reflexes were mediated through the stimulation of CSLV afferents. Pretreatment with HC030031 [an antagonist of transient receptor potential ankyrin subtype 1 protein (TRPA1)] or AP18 (another TRPA1 antagonist), but not their vehicle, markedly attenuated the apneic response induced by MG25. Consistently, electrophysiological results showed that pretreatment with HC030031 largely attenuated the intense discharge in CSLV afferents induced by injection of MG25 in open-chest and artificially ventilated rats. In isolated CSLV neurons, the perfusion of MG evoked an abrupt and pronounced increase in calcium transients in a concentration-dependent manner. This stimulatory effect on CSLV neurons was also abolished by HC030031 treatment but not by its vehicle. In conclusion, these results suggest that MG exerts a stimulatory effect on CSLV afferents, inducing pulmonary chemoreflexes, and such stimulation is mediated through the TRPA1 activation.NEW & NOTEWORTHY Methylglyoxal (MG) is implicated in the development of painful diabetic neuropathy. A retrospective cohort study revealed an increased incidence of asthma exacerbations in patients with diabetes. This study demonstrated that elevated circulating MG levels stimulate capsaicin-sensitive lung vagal afferents via activation of TRPA1, which in turn triggers respiratory reflexes. These findings provide new information for understanding the pathogenic mechanism of diabetes-associated hyperreactive airway diseases and potential therapy.