Hypoxia-inducible factor-1α inhibition modulates airway hyperresponsiveness and nitric oxide levels in a BALB/c mouse model of asthma

Blocking the HIF-1α/glycolysis axis inhibits allergic airway inflammation by reducing ILC2 metabolism and function

BACKGROUND

The role of lung group 2 innate lymphoid cell (ILC2) activation in allergic asthma is increasingly established. However, the regulatory mechanisms underlying hypoxia-inducible factor-1α (HIF-1α)-mediated glycolysis in ILC2-mediated allergic airway inflammation remain unclear.

OBJECTIVE

To investigate the role of the HIF-1α/glycolysis axis in ILC2-mediated allergic airway inflammation.

METHODS

Glycolysis and HIF-1α inhibitors were used to identify their effect on the function and glucose metabolism of mouse and human ILC2s in vivo and vitro. Blocking glycolysis and HIF-1α in mice under interleukin-33 (IL-33) stimulation were performed to test ILC2 responses. Conditional HIF-1α-deficient mice were used to confirm the specific role of HIF-1α in ILC2-driven airway inflammation models. Transcriptomic, metabolic, and chromatin immunoprecipitation analyses were performed to elucidate the underlying mechanism.

RESULTS

HIF-1α is involved in ILC2 metabolism and is crucial in allergic airway inflammation. Single-cell sequencing data analysis and qPCR confirmation revealed a significant upregulation of glycolysis-related genes, particularly HIF-1α, in murine lung ILC2s after IL-33 intranasal administration or injection. Treatment with the glycolysis inhibitor 2-deoxy-D-glucose (2-DG) and the HIF-1α inhibitor 2-methoxyestradiol (2-ME) abrogated inflammation by suppressing ILC2s function. Conditional HIF-1α-deficient mice showed reduced ILC2 response and airway inflammation induced upon IL-33 or house dust mite (HDM) stimulation. Transcriptome and metabolic analyses revealed significantly impaired glycolysis in lung ILC2s in conditional HIF-1α knockout mice compared to that in their littermate controls. Chromatin immunoprecipitation results confirmed the transcriptional downregulation of glycolysis-related genes in HIF-1α-knockout and 2-DG-treated mice. Furthermore, impaired HIF-1α/glycolysis axis activation is correlated with downregulated ILC2 in patients with asthma.

CONCLUSION

The HIF-1α/glycolysis axis is critical for controlling ILC2 responses in allergic airway inflammation and has potential immunotherapeutic value in asthma.

Hypoxia-inducible-factors differentially contribute to clinical disease and the control of viral replication during RSV infection

Hypoxia-inducible-factors (HIF) are transcription factors that regulate cellular adaptation to hypoxic conditions, enabling cells to survive in low-oxygen environments. Viruses have evolved to stabilize this pathway to promote successful viral infection, therefore modulation of HIFs could represent a novel antiviral strategy. In previous in vitro studies, we found that respiratory syncytial virus (RSV), a leading cause of respiratory illness, stabilizes HIFs under normoxic conditions, with inhibition of HIF-1α resulting in reduced viral replication. Despite several HIF modulating compounds being tested/approved for use in other non-infectious models, little is known about their efficacy against respiratory viruses using relevant animal models. This study aimed to characterize the disease modulating properties and antiviral potential of anti-HIF-1α (PX478) and anti-HIF-2α (PT2385) in RSV-infected BALB/c mice. We found that inhibition of HIF-1α worsen clinical disease parameters, while simultaneously improving airway function. Additionally, anti-HIF-1α results in significantly reduced viral titer at early and peak time points of RSV replication, followed by a loss in viral clearance when given every day, but not every-other-day. In contrast, inhibition of HIF-2α was associated with improved clinical parameters, with no changes in airway function, and amelioration of interstitial pneumonia. Furthermore, anti-HIF-2α reduced early and peak lung viral replication, with no impairment of viral clearance. Analysis of lung cells found significant modification in the T cell compartment that correlated with changes in lung pathology and viral titers in response to each HIF inhibitor administration. These data underscore the complex role of HIFs in RSV infection and highlight the need for careful therapeutic consideration.

Cbx4 governs HIF-1α to involve in Th9 cell differentiation promoting asthma by its SUMO E3 ligase activity

The potential role of polycomb chromobox 4 (Cbx4), as a small ubiquitin-like ligase (SUMO) E3 ligase, in the development and exacerbation of asthma remains unclear. Hypoxia inducible factor-1 (HIF-1) is a key transcription factor in the cellular response to hypoxia and contributes to the pathogenesis and progression of a range of diseases, including asthma. Here, we aimed to investigate the interaction of Cbx4 with Hypoxia inducible factor-1α (HIF-1α) and the potent mechanism of action in asthma progression. In present study, in vitro and ex vivo results demonstrated that Cbx4 interacts with HIF-1α protein through its SUMO E3 ligase activity and enhances the sumoylation, which increases HIF-1 transactivation through Cbx4 and promotes the differentiation of Th9 cells, then in turn promotes the process of asthma. Treatment of inhibitors targeting SUMO E3 ligase activity of Cbx4 or HIF-1α can effectively reduce HIF-1α activation and differentiation of Th9 cells, which further attenuates the asthma in mouse model. Current results collectively demonstrated Cbx4 can govern HIF-1α to involve in Th9 cell differentiation promoting asthma by its SUMO E3 ligase activity, providing a new direction for clinical treatment of asthma.

Cellular senescence in asthma: from pathogenesis to therapeutic challenges

Asthma is a heterogeneous chronic respiratory disease that impacts nearly 10% of the population worldwide. While cellular senescence is a normal physiological process, the accumulation of senescent cells is considered a trigger that transforms physiology into the pathophysiology of a tissue/organ. Recent advances have suggested the significance of cellular senescence in asthma. With this review, we focus on the literature regarding the physiology and pathophysiology of cellular senescence and cellular stress responses that link the triggers of asthma to cellular senescence, including telomere shortening, DNA damage, oncogene activation, oxidative-related senescence, and senescence-associated secretory phenotype (SASP). The association of cellular senescence to asthma phenotypes, airway inflammation and remodeling, was also reviewed. Importantly, several approaches targeting cellular senescence, such as senolytics and senomorphics, have emerged as promising strategies for asthma treatment. Therefore, cellular senescence might represent a mechanism in asthma, and the senescence-related molecules and pathways could be targeted for therapeutic benefit.

Molecular mechanism of Ferula asafoetida for the treatment of asthma: Network pharmacology and molecular docking approach

Asthma is a significant health-care burden that has great impact on the quality of life of patients and their families. The limited amount of previously reported data and complicated pathophysiology of asthma make it a difficult to treat and significant economic burden on public healthcare systems. Ferula asafoetida is an herbaceous, monoecious, perennial plant of the Umbelliferae family. In Asia, F. asafoetida is used to treat a range of diseases and disorders, including asthma. Several in vitro studies demonstrated the therapeutic efficacy of F. asafoetida against asthma. Nevertheless, the precise molecular mechanism is yet to be discovered. In the framework of current study, network pharmacology approach was used to identify the bioactive compounds of F. asafoetida in order to better understand its molecular mechanism for the treatment of asthma. In present work, we explored a compound-target-pathway network and discovered that assafoetidin, cynaroside, farnesiferol-B, farnesiferol-C, galbanic-acid, and luteolin significantly influenced the development of asthma by targeting MAPK3, AKT1 and TNF genes. Later, docking analysis revealed that active constituents of F. asafoetida bind stably with three target proteins and function as asthma repressor by regulating the expression of MAPK3, AKT1 and TNF genes. Thus, integration of network pharmacology with molecular docking revealed that F. asafoetida prevent asthma by modulating asthma-related signaling pathways. This study lays the basis for establishing the efficacy of multi-component, multi-target compound formulae, as well as investigating new therapeutic targets for asthma.

The Combination of Bioinformatics Analysis and Untargeted Metabolomics Reveals Potential Biomarkers and Key Metabolic Pathways in Asthma

Asthma is a complex chronic airway inflammatory disease that seriously impacts patients' quality of life. As a novel approach to exploring the pathogenesis of diseases, metabolomics provides the potential to identify biomarkers of asthma host susceptibility and elucidate biological pathways. The aim of this study was to screen potential biomarkers and biological pathways so as to provide possible pharmacological therapeutic targets for asthma. In the present study, we merged the differentially expressed genes (DEGs) of asthma in the GEO database with the metabolic genes obtained by Genecard for bioinformatics analysis and successfully screened out the metabolism-related hub genes (HIF1A, OCRL, NNMT, and PER1). Then, untargeted metabolic techniques were utilized to reveal HDM-induced metabolite alterations in 16HBE cells. A total of 45 significant differential metabolites and 5 differential metabolic pathways between the control group and HDM group were identified based on the OPLS-DA model. Finally, three key metabolic pathways, including glycerophospholipid metabolism, galactose metabolism, and alanine, aspartate, and glutamate metabolism, were screened through the integrated analysis of bioinformatics data and untargeted metabolomics data. Taken together, these findings provide valuable insights into the pathophysiology and targeted therapy of asthma and lay a foundation for further research.

The role of hypoxia in the pathophysiology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal cavity characterized by excessive nasal mucus secretion and nasal congestion. The development of CRS is related to pathological mechanisms induced by hypoxia. Under hypoxic conditions, the stable expression of both Hypoxia inducible factor-1 (HIF-1) α and HIF-2α are involved in the immune response and inflammatory pathways of CRS. The imbalance in the composition of nasal microbiota may affect the hypoxic state of CRS and perpetuate existing inflammation. Hypoxia affects the differentiation of nasal epithelial cells such as ciliated cells and goblet cells, induces fibroblast proliferation, and leads to epithelial-mesenchymal transition (EMT) and tissue remodeling. Hypoxia also affects the proliferation and differentiation of macrophages, eosinophils, basophils, and mast cells in sinonasal mucosa, and thus influences the inflammatory state of CRS by regulating T cells and B cells. Given the multifactorial nature in which HIF is linked to CRS, this study aims to elucidate the effect of hypoxia on the pathogenic mechanisms of CRS.

Effects of Hypoxia on Respiratory Diseases: Perspective View of Epithelial Ion Transport

The balance of gas exchange and lung ventilation is essential for the maintenance of body homeostasis. There are many ion channels and transporters in respiratory epithelial cells, including epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator, and some transporters. These ion channels/transporters maintain the capacity of liquid layer on the surface of respiratory epithelial cells, and provide an immune barrier for the respiratory system to clear off foreign pathogens. However, in some harmful external environment and/or pathological conditions, the respiratory epithelium is prone to hypoxia, which would destroy the ion transport function of the epithelium and unbalance the homeostasis of internal environment, triggering a series of pathological reactions. Many respiratory diseases associated with hypoxia manifest an increased expression of hypoxia-inducible factor-1, which mediates the integrity of the epithelial barrier and affects epithelial ion transport function. It is important to study the relationship between hypoxia and ion transport function, whereas the mechanism of hypoxia-induced ion transport dysfunction in respiratory diseases is not clear. This review focuses on the relationship of hypoxia and respiratory diseases, as well as dysfunction of ion transport and tight junctions in respiratory epithelial cells under hypoxia.

Explore the Effect of Asthma Regulating HIF-1 Pathway on Sperm Quality Based on Rat Model

This study is to verify the effect of asthma on sperm quality and explore its potential underlying mechanism. We randomly categorized the Sprague-Dawley (SD) rats into control (Group C) and asthma model (Group M) groups. Rats in the asthma model group were induced allergic asthma by intraperitoneal injection of ovalbumin solution. We evaluated the sperm motility and sperm concentration. The expression of the Interleukin-6 (IL6), phosphorylation-signal transducer and activator of transcription 3 (p-Stat3), and hypoxia-inducible factor-1α (HIF-1α) proteins and mRNAs in the testicular tissue was detected by western blotting and RT-qPCR. Compared with group C, sperm concentration and sperm motility in group M rats were significantly decreased (P < 0.05). Meanwhile, compared with group C, the expression levels of IL6, Stat3, and HIF-1α proteins and mRNAs in group M rats were significantly increased (P < 0.05). Asthma can regulate the HIF-1 signaling pathway, promoting the expression of IL6, Stat3, and HIF-1α protein and mRNAs, so as to promote sperm apoptosis and ultimately causing male infertility.

Anti-Inflammatory Activity of Monosubstituted Xestoquinone Analogues from the Marine Sponge Neopetrosia compacta

Chronic inflammation is recognized as a contributor to multiple chronic diseases, such as cancer, cardiovascular, and autoimmune disorders. Here, a natural products-initiated discovery of anti-inflammatory agents from marine sponges was undertaken. From the screening of 231 crude extracts, a total of 30 extracts showed anti-inflammatory activity with no direct cytotoxic effects at 50 μg/mL on RAW 264.7 (ATCC®TIB-71™) murine macrophage cells stimulated with 1 μg/mL lipopolysaccharide (LPS). Bioactivity-guided purification of the anti-inflammatory extract from the sponge Neopetrosia compacta led to the isolation of xestoquinone (1), adociaquinone B (2), adociaquinone A (3), 14-hydroxymethylxestoquinone (4), 15-hydroxymethylxestoquinone (5), and an inseparable 2:1 mixture of 14-methoxyxestoquinone and 15-methoxyxestoquinone (6). Compounds 1–6 caused a concentration-dependent reduction of nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells, with 4–6 having low micromolar IC50 and acceptable selectivity index. Gene expression analysis using qRT-PCR showed that 1, 5, and 6 downregulated Il1b and Nos2 expression by 2.1- to 14.8-fold relative to the solvent control at 10 μM. Xestoquinone (1) and monosubstituted analogues (4–6), but not the disubstituted adociaquinones (2 and 3), caused Nrf2 activation in a luciferase reporter MCF7 stable cells. Compounds 5 and 6 caused a modest increase in Nqo1 gene expression at 10 μM. The anti-inflammatory activity of xestoquinone (1) and monosubstituted analogues (4–6) may, in part, be mediated by Nrf2 activation, leading to attenuation of inflammatory mediators such as IL-1β and NOS2.

Synthetic strategy and structure-activity relationship (SAR) studies of 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1, Lificiguat): a review

Since 1994, YC-1 (Lificiguat, 3-(5′-hydroxymethyl-2′-furyl)-1-benzylindazole) has been synthesized, and many targets for special bioactivities have been explored, such as stimulation of platelet-soluble guanylate cyclase, indirect elevation of platelet cGMP levels, and inhibition of hypoxia-inducible factor-1 (HIF-1) and NF-κB. Recently, Riociguat®, the first soluble guanylate cyclase (sGC) stimulator drug used to treat pulmonary hypertension and pulmonary arterial hypertension, was derived from the YC-1 structure. In this review, we aim to highlight the synthesis and structure–activity relationships in the development of YC-1 analogs and their possible indications.

Since 1994, YC-1 (Lificiguat) has been synthesized, and many targets for special bioactivities have been explored, such as stimulation of platelet-soluble guanylate cyclase, indirect elevation of platelet cGMP levels, and inhibition of HIF-1 and NF-κB.

Adenosine at the Interphase of Hypoxia and Inflammation in Lung Injury

Hypoxia and inflammation often coincide in pathogenic conditions such as acute respiratory distress syndrome (ARDS) and chronic lung diseases, which are significant contributors to morbidity and mortality for the general population. For example, the recent global outbreak of Coronavirus disease 2019 (COVID-19) has placed viral infection-induced ARDS under the spotlight. Moreover, chronic lung disease ranks the third leading cause of death in the United States. Hypoxia signaling plays a diverse role in both acute and chronic lung inflammation, which could partially be explained by the divergent function of downstream target pathways such as adenosine signaling. Particularly, hypoxia signaling activates adenosine signaling to inhibit the inflammatory response in ARDS, while in chronic lung diseases, it promotes inflammation and tissue injury. In this review, we discuss the role of adenosine at the interphase of hypoxia and inflammation in ARDS and chronic lung diseases, as well as the current strategy for therapeutic targeting of the adenosine signaling pathway.

Association between asthma and risk of benign prostatic hyperplasia: a retrospective population-based study

OBJECTIVE

The association between asthma and benign prostatic hyperplasia (BPH) has rarely been explored. We investigated whether male asthmatic patients had an increased risk of BPH by conducting this retrospective nationwide population-based study.

METHODS

We utilized data derived from the National Health Insurance Research Database (NHIRD) in Taiwan. A total of 9778 male patients aged >40 years who were newly diagnosed with asthma between 2000 and 2006 were included in the asthma group. Male enrollees without asthma were selected as the non-asthma group from the same database. Both the groups were followed up until the end of 2013. We performed Cox proportional hazard regression analysis to estimate the risk of BPH and transurethral resection of the prostate (TURP) in the male patients with asthma compared with that in those without asthma.

RESULTS

The risk of BPH and TURP in the asthma group was 1.40-fold (95% confidence interval [CI] = 1.30-1.42) and 1.30-fold (95% CI= 1.31-1.50) higher than that in the non-asthma group, respectively, after adjusting for comorbidities, relevant medications and number of annual outpatient visits.

CONCLUSIONS

The male patients with asthma were found to have a higher risk of BPH than did those without asthma.

HIF-1α-Mediated, NADPH Oxidase-Derived ROS Contributes to Laryngeal Airway Hyperreactivity Induced by Intermittent Hypoxia in Rats

Obstructive sleep apnea, similar to intermittent hypoxia (IH) during sleep, is associated with laryngeal airway hyperreactivity (LAH). IH-induced laryngeal oxidative stress may contribute to LAH, but the underlying mechanism remains unknown. Conscious rats were subjected to repetitive 75 s cycles of IH for 7 or 14 consecutive days. Reflex apneic responses to laryngeal provocations with chemical stimulants were measured to reflect laryngeal reflex reactivity. Compared with control rats, rats exposed to IH for 14 days, but not for 7 days, displayed enhanced apneic response to laryngeal chemical stimulants. The apneic response to chemical stimulants, but not to mechanical stimulation, was totally abolished by perineural capsaicin treatment of superior laryngeal nerves (SLNs) or by the sectioning of the SLNs, suggesting that the reflex was mediated through capsaicin-sensitive SLNs. Daily intraperitoneal administration of N-acetyl-L-cysteine [NAC, a reactive oxygen species (ROS) scavenger], apocynin (an inhibitor of NADPH oxidase) or YC-1 (an inhibitor of HIF-1α), but not their vehicles, largely attenuated this augmented apneic response in 14 days IH rats. Laryngeal lipid peroxidation (an index of oxidative stress) was elevated in 7 days IH rats and 14 days IH rats, and was abolished by any of these three pharmacologic interventions. The protein expression of HIF-1α (an index of HIF-1 activation) and p47^phox subunit in the membrane fraction (an index of NADPH oxidase activation) in the laryngeal tissues increased in 14 days IH rats; the former was reduced by NAC, whereas the latter was inhibited by YC-1. These results suggest that 14 days of IH exposure may sensitize capsaicin-sensitive SLNs and result in exaggerated apneic reflex response to laryngeal chemical stimulants. This phenomenon depends on the action of HIF-1α-mediated, NADPH oxidase-derived ROS.

If it's not one thing, HIF's another: immunoregulation by hypoxia inducible factors in disease

Hypoxia‐inducible factors (HIFs) have emerged in recent years as critical regulators of immunity. Localised, low oxygen tension is a hallmark of inflamed and infected tissues. Subsequent myeloid cell HIF stabilisation plays key roles in the innate immune response, alongside emerging oxygen‐independent roles. Manipulation of regulatory proteins of the HIF transcription factor family can profoundly influence inflammatory profiles, innate immune cell function and pathogen clearance and, as such, has been proposed as a therapeutic strategy against inflammatory diseases. The direction and mode of HIF manipulation as a therapy are dictated by the inflammatory properties of the disease in question, with innate immune cell HIF reduction being, in general, advantageous during chronic inflammatory conditions, while upregulation of HIF is beneficial during infections. The therapeutic potential of targeting myeloid HIFs, both genetically and pharmacologically, has been recently illuminated in vitro and in vivo, with an emerging range of inhibitory and activating strategies becoming available. This review focuses on cutting edge findings that uncover the roles of myeloid cell HIF signalling on immunoregulation in the contexts of inflammation and infection and explores future directions of potential therapeutic strategies.

Bioenergetic Differences in the Airway Epithelium of Lean Versus Obese Asthmatics Are Driven by Nitric Oxide and Reflected in Circulating Platelets

Aims: Asthma, characterized by airway obstruction and hyper-responsiveness, is more severe and less responsive to treatment in obese subjects. While alterations in mitochondrial function and redox signaling have been implicated in asthma pathogenesis, it is unclear whether these mechanisms differ in lean versus obese asthmatics. In addition, we previously demonstrated that circulating platelets from asthmatic individuals have altered bioenergetics; however, it is unknown whether platelet mitochondrial changes reflect those observed in airway epithelial cells. Herein we hypothesized that lean and obese asthmatics show differential bioenergetics and redox signaling in airway cells and that these alterations could be measured in platelets from the same individual. Results: Using freshly isolated bronchial airway epithelial cells and platelets from lean and obese asthmatics and healthy individuals, we show that both cell types from obese asthmatics have significantly increased glycolysis, basal and maximal respiration, and oxidative stress compared with lean asthmatics and healthy controls. This increased respiration was associated with enhanced arginine metabolism by arginase, which has previously been shown to drive respiration. Inducible nitric oxide synthase (iNOS) was also upregulated in cells from all asthmatics. However, due to nitric oxide synthase uncoupling in obese asthmatics, overall nitric oxide (NO) bioavailability was decreased, preventing NO-dependent inhibition in obese asthmatic cells that was observed in lean asthmatics. Innovation and Conclusion: These data demonstrate bioenergetic differences between lean and obese asthmatics that are, in part, due to differences in NO signaling. They also suggest that the platelet may serve as a useful surrogate to understand redox, oxidative stress and bioenergetic changes in the asthmatic airway.

Consistent Biomarkers and Related Pathogenesis Underlying Asthma Revealed by Systems Biology Approach

Asthma is a common chronic airway disease worldwide. Due to its clinical and genetic heterogeneity, the cellular and molecular processes in asthma are highly complex and relatively unknown. To discover novel biomarkers and the molecular mechanisms underlying asthma, several studies have been conducted by focusing on gene expression patterns in epithelium through microarray analysis. However, few robust specific biomarkers were identified and some inconsistent results were observed. Therefore, it is imperative to conduct a robust analysis to solve these problems. Herein, an integrated gene expression analysis of ten independent, publicly available microarray data of bronchial epithelial cells from 348 asthmatic patients and 208 healthy controls was performed. As a result, 78 up- and 75 down-regulated genes were identified in bronchial epithelium of asthmatics. Comprehensive functional enrichment and pathway analysis revealed that response to chemical stimulus, extracellular region, pathways in cancer, and arachidonic acid metabolism were the four most significantly enriched terms. In the protein-protein interaction network, three main communities associated with cytoskeleton, response to lipid, and regulation of response to stimulus were established, and the most highly ranked 6 hub genes (up-regulated CD44, KRT6A, CEACAM5, SERPINB2, and down-regulated LTF and MUC5B) were identified and should be considered as new biomarkers. Pathway cross-talk analysis highlights that signaling pathways mediated by IL-4/13 and transcription factor HIF-1α and FOXA1 play crucial roles in the pathogenesis of asthma. Interestingly, three chemicals, polyphenol catechin, antibiotic lomefloxacin, and natural alkaloid boldine, were predicted and may be potential drugs for asthma treatment. Taken together, our findings shed new light on the common molecular pathogenesis mechanisms of asthma and provide theoretical support for further clinical therapeutic studies.

Genome-wide analysis revealed sex-specific gene expression in asthmatics

Global gene-expression analysis has shown remarkable difference between males and females in response to exposure to many diseases. Nevertheless, gene expression studies in asthmatics have so far focused on sex-combined analysis, ignoring inherent variabilities between the sexes, which potentially drive disparities in asthma prevalence. The objectives of this study were to identify (1) sex-specific differentially expressed genes (DEGs), (2) genes that show sex-interaction effects and (3) sex-specific pathways and networks enriched in asthma risk. We analyzed 711 males and 689 females and more than 2.8 million transcripts covering 20 000 genes leveraged from five different tissues and cell types (i.e. epithelial, blood, induced sputum, T cells and lymphoblastoids). Using tissue-specific meta-analysis, we identified 439 male- and 297 female-specific DEGs in all cell types, with 32 genes in common. By linking DEGs to the genome-wide association study (GWAS) catalog and the lung and blood eQTL annotation data from GTEx, we identified four male-specific genes (FBXL7, ITPR3 and RAD51B from epithelial tissue and ALOX15 from blood) and one female-specific gene (HLA-DQA1 from epithelial tissue) that are disregulated during asthma. The hypoxia-inducible factor 1 signaling pathway was enriched only in males, and IL-17 and chemokine signaling pathways were enriched in females. The cytokine-cytokine signaling pathway was enriched in both sexes. The presence of sex-specific genes and pathways demonstrates that sex-combined analysis does not identify genes preferentially expressed in each sex in response to diseases. Linking DEG and molecular eQTLs to GWAS catalog represents an important avenue for identifying biologically and clinically relevant genes.

Inhibition of HIF-1α Reduced Blood Brain Barrier Damage by Regulating MMP-2 and VEGF During Acute Cerebral Ischemia

Increase of blood brain barrier (BBB) permeability after acute ischemia stroke is a predictor to intracerebral hemorrhage transformation (HT) for tissue plasminogen activator (tPA) thrombolysis and post-endovascular treatment. Previous studies showed that 2-h ischemia induced damage of BBB integrity and matrix metalloproteinase-2 (MMP-2) made major contribution to this disruption. A recent study showed that blocking β2-adrenergic receptor (β2-AR) alleviated ischemia-induced BBB injury by reducing hypoxia-inducible factor-1 alpha (HIF-1α) level. In this study, we sought to investigate the interaction of HIF-1α with MMP-2 and vascular endothelial growth factor (VEGF) in BBB injury after acute ischemia stroke. Rat suture middle cerebral artery occlusion (MCAO) model was used to mimic ischemia condition. Our results showed that ischemia produced BBB damage and MMP-2/9 upregulation was colocalized with Rhodamine-dextran leakage. Pretreatment with YC-1, a HIF-1α inhibitor, alleviated 2-h ischemia-induced BBB injury significantly accompanied by decrease of MMP-2 upregulation. In addition, YC-1 also prevented VEGF-induced BBB damage. Of note, VEGF was shown to be colocalized with neurons but not astrocytes. Taken together, BBB damage was reduced by inhibition of interaction of HIF-1α with MMP-2 and VEGF during acute cerebral ischemia. These findings provide mechanisms underlying BBB damage after acute ischemia stroke and may help reduce thrombolysis- and post-endovascular treatment-related cerebral hemorrhage.

Hypoxia disrupts aryl hydrocarbon receptor signaling and the Th17 response in allergic rhinitis patients

BACKGROUND

Hypoxic conditions area key feature of allergic rhinitis (AR), however, the role of hypoxia in AR remains to be fully understood. The aim of this study was to survey the effect of hypoxia on the Th17 response in AR patients by investigating the action of hypoxia-influenced signaling pathways on Th17 differentiation.

METHODS

23 AR patients and 15 healthy controls were recruited for this study. Under normoxia and hypoxic conditions, the expression of HIF-1α, AhR, CYP1A1 and CYP1B1 and the presence of Th17 cells in CD4⁺T cells were measured. Furthermore, the amount of ARNT combined with either HIF-1α or AhR was determined after the exposure of 2-(1H-Indol-3-ylcarbonyl)-4-thiazolecarboxylic acid methyl easter (ITE) with normoxia and hypoxia.

RESULTS

HIF-1α and AhR expression were higher in CD4⁺T cells from AR patients than in those from healthy controls. In a hypoxic environment, the expression of HIF-1α was elevated in CD4⁺T cells of both AR patients and healthy controls. Meanwhile, the suppressive effects of a non-toxic AhR ligand (ITE) on the Th17 response and its positive effects on IL-10 production were suppressed in the cells of AR patients and healthy controls under hypoxia. These effects were arisen from HIF-1α out-competing AhR for ARNT binding which limited the activity of the AhR pathway.

CONCLUSIONS

The present results suggest that hypoxia is capable of promoting the Th17 response by reducing AhR activity via HIF-1α activity. Thus hypoxia may be intimately involved in the pathogenesis of AR.

Outstanding animal studies in allergy I. From asthma to food allergy and anaphylaxis

PURPOSE OF REVIEW

Animal models published within the past 18 months on asthma, food allergy and anaphylaxis, all conditions of rising public health concern, were reviewed.

RECENT FINDINGS

While domestic animals spontaneously develop asthma, food allergy and anaphylaxis, in animal models, divergent sensitization and challenge routes, dosages, intervals and antigens are used to induce asthmatic, food allergic or anaphylactic phenotypes. This must be considered in the interpretation of results. Instead of model antigens, gradually relevant allergens such as house dust mite in asthma, and food allergens like peanut, apple and peach in food allergy research were used. Novel engineered mouse models such as a mouse with a T-cell receptor for house dust mite allergen Der p 1, or with transgenic human hFcγR genes, facilitated the investigation of single molecules of interest. Whole-body plethysmography has become a state-of-the-art in-vivo readout in asthma research. In food allergy and anaphylaxis research, novel techniques were developed allowing real-time monitoring of in-vivo effects following allergen challenge. Networks to share tissues were established as an effort to reduce animal experiments in allergy which cannot be replaced by in-vitro measures.

SUMMARY

Natural and artificial animal models were used to explore the pathophysiology of asthma, food allergy and anaphylaxis and to improve prophylactic and therapeutic measures. Especially the novel mouse models mimicking molecular aspects of the complex immune network in asthma, food allergy and anaphylaxis will facilitate proof-of-concept studies under controlled conditions.