The role of histone deacetylases in asthma and allergic diseases

Protective effect of valproic acid on ischemia-reperfusion induced spinal cord injury in a rat model

PURPOSE

This study aims to determine the anti-inflammatory, antioxidant, and anti-apoptotic effects of valproic acid (VPA) on rat spinal cord tissue in ischemia-reperfusion (IR) injury model created by abdominal aorta occlusion.

MATERIALS AND METHODS

Sprague Dawley rat (male sex) weighing 190-260 g divided into four experimental groups: control only underwent laparotomy, sham group, pre-IR injury (200 mg/kg dose), and post-IR injury (300 mg/kg) VPA. We measured serum levels of TNF-α, IL-6, IL-1β, IL-18, Total Oxidant Status (TOS) and Total Antioxidant Status (TAS), and serum Oxidative Stress Index (OSI) ratio, and tissue expression of Bax and Bcl2, Caspase3, and Bax/Bcl2 ratio.

RESULTS

Serum IL-18 was higher in the sham than the control group(P = 0.001), and there were declines in the pre-IR treatment (P = 0.002) and the post-IR treatment when compared to sham (P = 0.001). Despite these reductions, IL-18 expression levels in both the pre- and post-IR treatment groups were higher than in the control group (P = 0.001 & P = 0.003). The favorable effects of pre-IR VPA administration on immunohistochemical biomarkers were superior to post-IR VPA administration.

CONCLUSIONS

Comparative analyses between prophylactic VPA administration and post-IR interventions revealed congruence in their anti-inflammatory and anti-apoptotic ramifications. VPA can reduce spinal cord IR injury in an aortic occlusion model of rats.

The role of HDAC3 in inflammation: mechanisms and therapeutic implications

Histone deacetylases (HDACs) are critical regulators of inflammatory gene expression, and the efficacy of pan-HDAC inhibitors has been implicated in various disease conditions. However, it remains largely unclear how HDACs precisely regulate inflammation. To this end, evaluating the isoform-specific function of HDACs is critical, and the isoform-specific targeting could also circumvent the off-target effects of pan-HDAC inhibitors. This review provides an overview of the roles of HDAC3, a class I HDAC isoform, in modulating inflammatory responses and discusses the molecular mechanisms by which HDAC3 regulates inflammation associated with brain pathology, arthritis, cardiovascular diseases, lung pathology, allergic conditions, and kidney disorders. The articles also identify knowledge gaps in the field for future studies. Despite some conflicting reports, the selective inhibition of HDAC3 has been demonstrated to play a beneficial role in various inflammatory pathologies. Exploring the potential of HDAC3 inhibition to improve disease prognosis is a promising avenue requiring further investigation.

Peripheral neutrophils and oxidative stress-associated molecules for predicting the severity of asthma: a cross-sectional study based on multidimensional assessment

Objectives

This study aims to explore the relationship between the severity of asthma and neutrophils and related oxidative stress-associated molecules in peripheral blood and induced sputum.

Methods

A total of 67 subjects were included in this study, namely, 25 patients with severe asthma and 42 patients with non-severe asthma. Clinical data, induced sputum and peripheral blood were collected. Lung function and molecules related to oxidative stress in induced sputum and peripheral blood of asthma patients were detected. The relationship between neutrophils and asthma severity was analyzed. HDAC2 mRNA and protein expression levels and HDAC2 activity were also analyzed. Multivariate logistic regression was performed to select statistically significant variables.

Results

The absolute value of neutrophils and percentage of neutrophils were higher in the severe asthma patients. These two values were used to predict the severity of asthma by ROC analysis, with the best cutoff values being 4.55 × 109/L (sensitivity 83.3%, specificity 64.0%) and 55.15% (sensitivity 54.8%, specificity 88.0%). The ROS concentration of neutrophils in the induced sputum samples and the 8-iso-PGF2α concentration in the peripheral blood samples were higher in the severe asthma group (P = 0.012; P = 0.044), whereas there was reduced HDAC2 protein activity in PBMCs (P < 0.001). A logistic equation and a nomogram were created to give a precise prediction of disease severity.

Conclusion

Oxidative stress is increased in severe asthma patients. Peripheral blood neutrophils and 8-iso-PGF2α can be used as biomarkers to predict the severity of asthma. A prediction model was created for evaluating asthma severity.

A functional genomics pipeline to identify high-value asthma and allergy CpGs in the human methylome

BACKGROUND

DNA methylation of cytosines at cytosine-phosphate-guanine (CpG) dinucleotides (CpGs) is a widespread epigenetic mark, but genome-wide variation has been relatively unexplored due to the limited representation of variable CpGs on commercial high-throughput arrays.

OBJECTIVES

To explore this hidden portion of the epigenome, this study combined whole-genome bisulfite sequencing with in silico evidence of gene regulatory regions to design a custom array of high-value CpGs. This study focused on airway epithelial cells from children with and without allergic asthma because these cells mediate the effects of inhaled microbes, pollution, and allergens on asthma and allergic disease risk.

METHODS

This study identified differentially methylated regions from whole-genome bisulfite sequencing in nasal epithelial cell DNA from a total of 39 children with and without allergic asthma of both European and African ancestries. This study selected CpGs from differentially methylated regions, previous allergy or asthma epigenome-wide association studies (EWAS), or genome-wide association study loci, and overlapped them with functional annotations for inclusion on a custom Asthma&Allergy array. This study used both the custom and EPIC arrays to perform EWAS of allergic sensitization (AS) in nasal epithelial cell DNA from children in the URECA (Urban Environment and Childhood Asthma) birth cohort and using the custom array in the INSPIRE [Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure] birth cohort. Each CpG on the arrays was assigned to its nearest gene and its promotor capture Hi-C interacting gene and performed expression quantitative trait methylation (eQTM) studies for both sets of genes.

RESULTS

Custom array CpGs were enriched for intermediate methylation levels compared to EPIC CpGs. Intermediate methylation CpGs were further enriched among those associated with AS and for eQTMs on both arrays.

CONCLUSIONS

This study revealed signature features of high-value CpGs and evidence for epigenetic regulation of genes at AS EWAS loci that are robust to race/ethnicity, ascertainment, age, and geography.

Precision Medicine in Asthma Therapy

Asthma is a complex, heterogeneous disease that necessitates a proper patient evaluation to decide the correct treatment and optimize disease control. The recent introduction of new target therapies for the most severe form of the disease has heralded a new era of treatment options, intending to treat and control specific molecular pathways in asthma pathophysiology. Precision medicine, using omics sciences, investigates biological and molecular mechanisms to find novel biomarkers that can be used to guide treatment selection and predict response. The identification of reliable biomarkers indicative of the pathological mechanisms in asthma is essential to unravel new potential treatment targets. In this chapter, we provide a general description of the currently available -omics techniques, focusing on their implications in asthma therapy.

Histone deacetylase activity is a novel target for epithelial barrier defects in patients with eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Studies have independently indicated that eosinophils and histone deacetylases (HDACs) may compromise the integrity of the epithelial barrier in nasal polyps; however, the underlying mechanisms are not clear. In this study, we aimed to investigate the role of eosinophilia and HDACs in regulation of tight junctions (TJs) and nasal epithelial barrier integrity in chronic rhinosinusitis with nasal polyps (CRSwNP) patients.

METHODS

Expression of mRNAs and proteins of TJs and HDACs of biopsy specimens and air-liquid interface (ALI) human nasal epithelial cell cultures (HNECs) from eosinophilic and noneosinophilic CRSwNP patients and healthy controls was assessed. The ALI HNECs were also assessed for changes in transepithelial electrical resistance (TER) and paracellular flux of fluorescein isothiocyanate (FITC)-labelled dextran. Meanwhile, the assessments for the effect of HDAC inhibitor in eosinophilic nasal polyps were also conducted.

RESULTS

Decreased TER and increased paracellular flux of FITC-labelled dextran in the ALI cultures were found in both eosinophilic and noneosinophilic CRSwNP, along with irregular, patchy and reduced expression of claudin-1, 4, 7, occludin, zonula occludens (ZO)-1 and ZO-2 and increased expression of HDAC1, 9 and SIRT7 for both ALI culture cells and biopsy specimens, especially for the eosinophilic CRSwNP group. Treatment of eosinophilic CRSwNP ALI-HNECs with an HDAC inhibitor improved the TJs expression and epithelial barrier integrity.

CONCLUSIONS

Our data suggest that eosinophilia and HDACs influence epithelial barrier function in CRSwNP patients by regulating TJ protein expression. Targeting HDACs with specific inhibitors may be a potential treatment option for patients with eosinophilic CRSwNP.

Shukri N, Wong KK, Mohd Ashari NS. Zonula occludens-1 expression is reduced in nasal epithelial cells of allergic rhinitis patients

Allergic rhinitis (AR) is a common allergic disease characterized by disruption of nasal epithelial barrier. In this study, we investigated the mRNA expression of zonula occludens-1 (ZO-1), ZO-2 and ZO-3 and histone deacetylase 1 (HDAC1) and HDAC2 in AR patients compared to healthy controls. RNA samples were extracted from nasal epithelial cells of house dust mites (HDMs)-sensitized AR patients and healthy controls (n = 28 in each group). The RNAs were reverse transcribed into cDNAs for measurement of ZO-1, ZO-2, ZO-3, HDAC1 and HDAC2 expression levels by quantitative PCR. The mRNA expression of ZO-1 was significantly decreased in AR patients compared to healthy controls (p = 0.010). No significant difference was observed in the expression levels of ZO-2, ZO-3, HDAC1 and HDAC2 in AR patients compared to healthy controls. We found significant associations of higher HDAC2 levels in AR patients with lower frequency of changing bedsheet (p = 0.043) and with AR patients sensitized to Dermatophagoides farinae (p = 0.041). Higher expression of ZO-2 was observed in AR patients who had pets (p = 0.007). In conclusion, our data indicated that ZO-1 expression was lower in AR patients contributing to decreased integrity of nasal epithelial barrier integrity, and HDAC2 may be involved in the pathogenesis of the disease.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

Intranasal curcumin and sodium butyrate modulates airway inflammation and fibrosis via HDAC inhibition in allergic asthma

Asthma being an inflammatory disease of the airways lead to structural alterations in lungs which often results in the severity of the disease. Curcumin, diferuloylmethane, is well known for its medicinal properties but its anti-inflammatory potential via Histone deacetylase inhibition (HDACi) has not been revealed yet. Therefore, we have explored here, anti-inflammatory and anti-fibrotic potential of intranasal curcumin via HDAC inhibition and compared its potential with Sodium butyrate (SoB), a known histone deacetylase inhibitor of Class I and II series. Anti-inflammatory potential of SoB, has been investigated in cancer but not been studied in asthma before.

MATERIALS AND METHODS

In present study, ovalbumin (OVA) was used to sensitize Balb/c mice and later exposed to (1%) OVA aerosol. Curcumin (5 mg/kg) and Sodium butyrate (50 mg/kg) was administered through intranasal route an hour before OVA aerosol challenge. Efficacies of SoB and Curcumin as HDAC inhibitors were evaluated in terms of different inflammatory parameters like, total inflammatory cell count, reactive oxygen species (ROS), histamine release, nitric oxide and serum IgE levels. Inflammatory cell recruitment was analyzed by H&E staining and structural alterations were revealed by Masson's Trichrome staining of lung sections.

RESULTS

Enhanced Matrix Metalloproteinase-2 and 9 (MMP-2 and MMP-9) activities were observed in bronchoalveolar lavage fluid (BALF) of asthmatic mice by gelatin zymography which was inhibited in both treatment groups. Protein expressions of MMP-9, HDAC 1, H3acK9 and NF-kB p65 were modulated in intranasal curcumin and SoB pretreatment groups.

CONCLUSION

This is the first report where intranasal curcumin inhibited asthma severity via affecting HDAC 1 (H3acK9) leading to NF-kB suppression in mouse model of allergic asthma.

Valproic Acid Ameliorates Locomotor Function in the Rat Model of Contusion via Alteration of Mst1, Bcl-2, and Nrf2 Gene Expression

Background:

In animal models of inflammatory diseases, Mst1 facilitates the programmed cell death as a novel pro-apoptotic kinase. This research aimed to determine the expression level of Mst1 gene in a rat model of SCI treated with VPA.

Methods:

Severe rat model contusion was used for evaluation of the neuroprotective effect of valproic acid. The BBB test, was performed to determine locomotor functions. H&E staining and TUNEL assay were performed to detect cavity formation and apoptosis, respectively. The mRNA levels of the genes Mst1, Nrf2, and Bcl-2 were evaluated, using quantitative RT-PCR.

Results:

The results revealed that Mst1 gene expression and TUNEL-positive cells in the VPA-treated group were significantly reduced as compared to the untreated group (p ≤ 0.05).

Conclusion:

Our findings indicate that VPA has therapeutic potential and can be a candidate for the treatment of neurodegenerative disorders and traumatic injury as a promising drug.

Epithelial barriers in allergy and asthma

The respiratory epithelium provides a physical, functional, and immunologic barrier to protect the host from the potential harming effects of inhaled environmental particles and to guarantee maintenance of a healthy state of the host. When compromised, activation of immune/inflammatory responses against exogenous allergens, microbial substances, and pollutants might occur, rendering individuals prone to develop chronic inflammation as seen in allergic rhinitis, chronic rhinosinusitis, and asthma. The airway epithelium in asthma and upper airway diseases is dysfunctional due to disturbed tight junction formation. By putting the epithelial barrier to the forefront of the pathophysiology of airway inflammation, different approaches to diagnose and target epithelial barrier defects are currently being developed. Using single-cell transcriptomics, novel epithelial cell types are being unraveled that might play a role in chronicity of respiratory diseases. We here review and discuss the current understandings of epithelial barrier defects in type 2-driven chronic inflammation of the upper and lower airways, the estimated contribution of these novel identified epithelial cells to disease, and the current clinical challenges in relation to diagnosis and treatment of allergic rhinitis, chronic rhinosinusitis, and asthma.

Zonula occludens and nasal epithelial barrier integrity in allergic rhinitis

Allergic rhinitis (AR) is a common disease affecting 400 million of the population worldwide. Nasal epithelial cells form a barrier against the invasion of environmental pathogens. These nasal epithelial cells are connected together by tight junction (TJ) proteins including zonula occludens-1 (ZO-1), ZO-2 and ZO-3. Impairment of ZO proteins are observed in AR patients whereby dysfunction of ZOs allows allergens to pass the nasal passage into the subepithelium causing AR development. In this review, we discuss ZO proteins and their impairment leading to AR, regulation of their expression by Th1 cytokines (i.e., IL-2, TNF-α and IFN-γ), Th2 cytokines (i.e., IL-4 and IL-13) and histone deacetylases (i.e., HDAC1 and HDAC2). These findings are pivotal for future development of targeted therapies by restoring ZO protein expression and improving nasal epithelial barrier integrity in AR patients.

Pharmacogenomic Response of Inhaled Corticosteroids for the Treatment of Asthma: Considerations for Therapy

There is a large interindividual variability in response to ICSs in asthma. About 70% of the variance in ICS response is likely due at least partially to genetically determined characteristics of target genes. In this article, we examine the effects on the ICS response of gene variations in the corticosteroid pathway, and in the pharmacokinetics of corticosteroids, and also those outside the corticosteroid pathway, which have the potential to influence corticosteroid activity. Although the available evidence indicates that responses to ICSs in asthma are influenced by different genetic variants, there are still deep uncertainties as to whether a real association between these genetic variants and corticosteroid response could also possibly exist because there are difficulties in reproducing pharmacogenetic findings. This explains at least partly the insufficient use of pharmacogenomic data when treating asthmatic patients, which creates a real limitation to the proper use of ICSs in an era of precision medicine that links the right patient to the right treatment. Knowing and dealing with the genetic factors that influence the therapeutic ICS response is a fundamental condition for prescribing the right dose of ICS to the right patient at the right time.

Valproate improves middle cerebral artery occlusion-induced ischemic cerebral disorders in mice and oxygen-glucose deprivation-induced injuries in microglia by modulating RMRP/PI3K/Akt axis

Valproate (VPA) is capable of attenuating ischemic stroke (IS)-related disorders in brain tissues. Long non-coding RNAs (lncRNAs) are involved in the progression of IS. In the current study, the role of lncRNA RMRP in the protective effects of VPA against IS was explored. Mice were subjected to middle cerebral artery occlusion (MCAO) model to induce IS injures and then were administrated with VPA. The effects of VPA on infarction area and apoptosis in brain tissues, and the RMRP-regulated PI3K/Akt signaling activity were detected. Thereafter, oxygen-glucose deprivation (OGD) BV-2 cells were used as the in vitro model to further explore the mechanism underlying VPA function. The administration of VPA reduced infarction area and suppressed apoptosis in brain tissues of MCAO mice. VPA also inhibited RMRP expression and activated PI3K/Akt signaling. In OGD BV-2 cells, the treatment of VPA increased viability and attenuated apoptosis, which was associated with the inhibition of RMRP and the activation of PI3K/Akt pathway. Moreover, the induced expression of RMRP blocked the anti-OGD function of VPA, indicating the key role of RMRP inhibition in the effects of VPA on nerve system. Collectively, VPA attenuated MCAO/OGD-induced disorders in mice and microglia. The effects were dependent on the inhibition of RMRP, which subsequently induced the activation of PI3K/Akt signaling.

Recent findings in the genetics and epigenetics of asthma and allergy

In asthma and allergy genetics, a trend towards a few main topics developed over the last 2 years. First, a number of studies have been published recently which focus on overlapping and/or very specific phenotypes: within the allergy spectrum but also reaching beyond, looking for common genetic traits shared between different diseases or disease entities. Secondly, an urgently needed focus has been put on asthma and allergy genetics in populations genetically different from European ancestry. This acknowledges that the majority of new asthma patients today are not white and asthma is a truly worldwide disease. In epigenetics, recent years have seen several large-scale epigenome-wide association studies (EWAS) being published and a further focus was on the interaction between the environment and epigenetic signatures. And finally, the major trends in current asthma and allergy genetics and epigenetics comes from the field of pharmacogenetics, where it is necessary to understand the susceptibility for and mechanisms of current asthma and allergy therapies while at the same time, we need to have scientific answers to the recent availability of novel drugs that hold the promise for a more individualized therapy.

Role of Erythromycin-Regulated Histone Deacetylase-2 in Benign Tracheal Stenosis

Objective

This study aims to explore the role of erythromycin-regulated histone deacetylase-2 in benign tracheal stenosis.

Methods

The rabbit model of tracheal stenosis was established. The rabbits were randomly divided into 8 groups. Histone deacetylase-2 (HDAC2) expression was detected by immunofluorescence. The expression of type I collagen and type III collagen was detected by immunohistochemical method. The expression of TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-

Results

In Erythromycin (ERY) group, ERY + Budesonide group, ERY + Vorinostat group and ERY + Budesonide + Vorinostat group, the degree of bronchial stenosis was alleviated, and the mucosal epithelium was still slightly proliferated. The effect of ERY combined with other drugs was more obvious. The HDAC2 protein expression increased significantly in ERY group, ERY + Budesonide group and ERY + Budesonide + Vorinostat group and decreased significantly in Vorinostat group, the expression of collagen I and III decreased significantly in ERY group, ERY + Budesonide group and ERY + Budesonide + Vorinostat group (P < 0.05). The TGF-β1, VEGF and IL-8 in serum and alveolar lavage fluid was detected by ELISA. The expression of HDAC2, TGF-P < 0.05). The TGF-

Conclusions

Erythromycin inhibited inflammation and excessive proliferation of granulation tissue after tracheobronchial mucosal injury by up-regulating the expression of HDAC2, it promoted wound healing and alleviated tracheobronchial stenosis. When combined with budesonide, penicillin and other glucocorticoids and antibiotics, it had a good synergistic effect. However, vorinostat could attenuate erythromycin's effect by down-regulating the expression of HDAC2. It may have good clinical application prospects in the treatment of tracheal stenosis.

Comorbidity of asthma and hypertension may be mediated by shared genetic dysregulation and drug side effects

Asthma and hypertension are complex diseases coinciding more frequently than expected by chance. Unraveling the mechanisms of comorbidity of asthma and hypertension is necessary for choosing the most appropriate treatment plan for patients with this comorbidity. Since both diseases have a strong genetic component in this article we aimed to find and study genes simultaneously associated with asthma and hypertension. We identified 330 shared genes and found that they form six modules on the interaction network. A strong overlap between genes associated with asthma and hypertension was found on the level of eQTL regulated genes and between targets of drugs relevant for asthma and hypertension. This suggests that the phenomenon of comorbidity of asthma and hypertension may be explained by altered genetic regulation or result from drug side effects. In this work we also demonstrate that not only drug indications but also contraindications provide an important source of molecular evidence helpful to uncover disease mechanisms. These findings give a clue to the possible mechanisms of comorbidity and highlight the direction for future research.

A translational perspective on epigenetics in allergic diseases

The analysis of epigenetic modifications in allergic diseases has recently attracted substantial interest because epigenetic modifications can mediate the effects of the environment on the development of or protection from allergic diseases. Furthermore, recent research has provided evidence for an altered epigenomic landscape in disease-relevant cell populations. Although still in the early phase, epigenetic modifications, particularly DNA methylation and microRNAs, might have potential for assisting in the stratification of patients for treatment and complement or replace in the future biochemical or clinical tests. The first epigenetic biomarkers correlating with the successful outcome of immunotherapy have been reported, and with personalized treatment options being rolled out, epigenetic modifications might well play a role in monitoring or even predicting the response to tailored therapy. However, further studies in larger cohorts with well-defined phenotypes in specific cell populations need to be performed before their implementation. Furthermore, the epigenome provides an interesting target for therapeutic intervention, with microRNA mimics, inhibitors, and antisense oligonucleotides being evaluated in clinical trials in patients with other diseases. Selection or engineering of populations of extracellular vesicles and epigenetic editing represent novel tools for modulation of the cellular phenotype and responses, although further technological improvements are required. Moreover, interactions between the host epigenome and the microbiome are increasingly recognized, and interventions of the microbiome could contribute to modulation of the epigenome with a potential effect on the overall goal of prevention of allergic diseases.

FcεRI-HDAC3-MCP1 Signaling Axis Promotes Passive Anaphylaxis Mediated by Cellular Interactions

Anaphylaxis is an acute and life-threatening systemic reaction. Food, drug, aero-allergen and insect sting are known to induce anaphylaxis. Mast cells and basophils are known to mediate Immunoglobulin E (IgE)-dependent anaphylaxis, while macrophages, neutrophils and basophils mediate non IgE-dependent anaphylaxis. Histone deacetylases (HDACs) play various roles in biological processes by deacetylating histones and non-histones proteins. HDAC inhibitors can increase the acetylation of target proteins and affect various inflammatory diseases such as cancers and allergic diseases. HDAC3, a class I HDAC, is known to act as epigenetic and transcriptional regulators. It has been shown that HDAC3 can interact with the high-affinity Immunoglobulin E receptor (FcεRI), to mediate passive anaphylaxis and cellular interactions during passive anaphylaxis. Effects of HDAC3 on anaphylaxis, cellular interactions involving mast cells and macrophages during anaphylaxis, and any tumorigenic potential of cancer cells enhanced by mast cells will be discussed in this review. Roles of microRNAs that form negative feedback loops with hallmarks of anaphylaxis such as HDAC3 in anaphylaxis and cellular interactions will also be discussed. The roles of MCP1 regulated by HDAC3 in cellular interactions during anaphylaxis are discussed. Roles of exosomes in cellular interactions mediated by HDAC3 during anaphylaxis are also discussed. Thus, review might provide clues for development of drugs targeting passive anaphylaxis.

p300 mediates the histone acetylation of ORMDL3 to affect airway inflammation and remodeling in asthma

BACKGROUND

Bronchial asthma is affected by both environmental and genetic factors. The orosomucoid 1-like protein 3 (ORMDL3) gene is related to childhood asthma and is involved in airway inflammation and airway remodeling. The ORMDL3 promoter contains binding sites for the histone acetylase p300. Gene expression can be affected by epigenetic modifications. This study aimed to investigate whether the p300-mediated histone acetylation (HAT) of ORMDL3 gene affects airway inflammation and remodeling in asthma.

METHODS

16HBE14o- cells were transfected with various concentrations of a wild-type p300 plasmid or p300HAT-deletion plasmids. A dual luciferase reporter assay was used to examine the effect of p300-mediated HAT on the ORMDL3 promoter. Thirty BALB/c mice were randomly divided into a control group, an ovalbumin (OVA)-induced asthma group and an asthma + C646 (a selective inhibitor of p300) group. Noninvasive lung function tests were conducted to examine airway hyperreactivity (AHR) in the different groups. HE and Masson's trichrome staining was performed to examine airway remodeling and inflammation. Immunohistochemistry, western blotting and real-time PCR were used to analyze ORMDL3 expression in lung tissues. ELISA and western blotting were used to evaluate the HAT status in lung tissue. The ChIP assay was used to determine the relationship of the ORMDL3 promoter to p300 or acetylated histone H3 (aceH3).

RESULTS

p300 activated transcription from the ORMDL3 promoter, resulting in an increase in endogenous ORMDL3 mRNA levels. ORMDL3 promoter activity was reduced when the HAT activity of p300 was lost. ORMDL3 expression was elevated, and HAT activity was high in the lung tissues of asthmatic mice. p300 and aceH3 bound to the promoter region of ORMDL3. In the asthma group, the amounts of p300 and aceH3 recruited to the ORMDL3 promoter were increased. C646 inhibited p300 expression and reduced HAT activity and aceH3 levels in asthmatic mice, thereby reducing ORMDL3 expression and relieving AHR and airway remodeling.

CONCLUSION

p300-mediated HAT modulates the expression of the asthma susceptibility gene ORMDL3, thereby improving the process of airway inflammation and remodeling in asthma.

Harnessing the HDAC-histone deacetylase enzymes, inhibitors and how these can be utilised in tissue engineering

There are large knowledge gaps regarding how to control stem cells growth and differentiation. The limitations of currently available technologies, such as growth factors and/or gene therapies has led to the search of alternatives. We explore here how a cell's epigenome influences determination of cell type, and potential applications in tissue engineering. A prevalent epigenetic modification is the acetylation of DNA core histone proteins. Acetylation levels heavily influence gene transcription. Histone deacetylase (HDAC) enzymes can remove these acetyl groups, leading to the formation of a condensed and more transcriptionally silenced chromatin. Histone deacetylase inhibitors (HDACis) can inhibit these enzymes, resulting in the increased acetylation of histones, thereby affecting gene expression. There is strong evidence to suggest that HDACis can be utilised in stem cell therapies and tissue engineering, potentially providing novel tools to control stem cell fate. This review introduces the structure/function of HDAC enzymes and their links to different tissue types (specifically bone, cardiac, neural tissues), including the history, current status and future perspectives of using HDACis for stem cell research and tissue engineering, with particular attention paid to how different HDAC isoforms may be integral to this field.

Blocking histone deacetylase activity as a novel target for epithelial barrier defects in patients with allergic rhinitis

BACKGROUND

A defective epithelial barrier is found in patients with allergic rhinitis (AR) and asthma; however, the underlying mechanisms remain poorly understood. Histone deacetylase (HDAC) activity has been identified as a crucial driver of allergic inflammation and tight junction dysfunction.

OBJECTIVE

We investigated whether HDAC activity has been altered in patients with AR and in a mouse model of house dust mite (HDM)-induced allergic asthma and whether it contributed to epithelial barrier dysfunction.

METHODS

Primary nasal epithelial cells of control subjects and patients with AR were cultured at the air-liquid interface to study transepithelial electrical resistance and paracellular flux of fluorescein isothiocyanate-dextran (4 kDa) together with mRNA expression and immunofluorescence staining of tight junctions. Air-liquid interface cultures were stimulated with different concentrations of JNJ-26481585, a broad-spectrum HDAC inhibitor. In vivo the effect of JNJ-26481585 on mucosal permeability and tight junction function was evaluated in a mouse model of HDM-induced allergic airway inflammation.

RESULTS

General HDAC activity was greater in nasal epithelial cells of patients with AR and correlated inversely with epithelial integrity. Treatment of nasal epithelial cells with JNJ-26481585 restored epithelial integrity by promoting tight junction expression and protein reorganization. HDM-sensitized mice were treated with JNJ-26481585 to demonstrate the in vivo role of HDACs. Treated mice did not have allergic airway inflammation and had no bronchial hyperreactivity. Moreover, JNJ-26481585 treatment restored nasal mucosal function by promoting tight junction expression.

CONCLUSION

Our findings identify increased HDAC activity as a potential tissue-injury mechanism responsible for dysregulated epithelial cell repair, leading to defective epithelial barriers in AR. Blocking HDAC activity is a promising novel target for therapeutic intervention in patients with airway diseases.

Valproic acid attenuates global cerebral ischemia/reperfusion injury in gerbils via anti-pyroptosis pathways

Ischemic stroke is the third most common cause of death and the leading cause of disability worldwide in adults. The antiepileptic drug valproic acid (VPA) was reported to protect cerebral ischemia/reperfusion injury. However, the action mechanism of VPA in cerebral ischemia/reperfusion injury has not been fully understood. We explored the action mechanism of VPA in vivo and in vitro. Gerbils were subjected to transient global cerebral ischemic-reperfusion injury, and hippocampal neuron injury was treated with oxygen-glucose deprivation in vitro. Morris water maze test was performed to evaluate the cognitive dysfunction. Histopathological examinations and western blot were performed to evaluate the pyroptosis of neurons. The results showed that VPA attenuated the cognitive dysfunction, pyroptosis of the gerbils suffer from ischemic-reperfusion injury and decreased hippocampal neurons pyroptosis induced by oxygen-glucose deprivation in vitro. In addition, western blot and real-time PCR analysis revealed that VPA modulated the protein expression of apoptosis repressor with caspase recruitment domain (ARC), caspase-1 and IL-1β/IL-18. Our results suggested that VPA alleviated ischemic/reperfusion injury-mediated neuronal impairment by anti-pyroptotic effects.

Diet, Obesity, and Asthma

Obesity has reached epidemic proportions in many developed countries as Western dietary patterns have been widely adopted. These diets are characterized by excess energy intake as well as regular consumption of processed or "fast" foods and limited consumption of fruit, vegetables, and whole grains. The result is a high intake of saturated fat, refined carbohydrates, and sodium; and a low intake of fiber, vitamins, and other phytochemicals. This type of poor-quality diet has been associated with increased risk of chronic inflammatory diseases, including asthma. Of particular note, high intake of saturated fat stimulates proinflammatory pathways via activation of pattern recognition receptors, endoplasmic reticulum stress, and fatty acid-binding protein activity. Conversely, with a low intake of soluble fiber, beneficial antiinflammatory mechanisms, such as free fatty acid receptor activation and histone deacetylase inhibition, are suppressed. Similarly, with a low intake of antioxidants such as vitamin C, vitamin E, and carotenoids, nuclear factor κ-light-chain-enhancer of activated B cells activity is enhanced, creating a proinflammatory environment. There is evidence derived from human and experimental models of asthma suggesting that these mechanisms contribute to the development of airway inflammation, loss of asthma control, and/or worse lung function. Obese individuals have increased asthma morbidity and reduced quality of life, so strategies for better management of these patients are urgently needed. Evidence suggests that, in addition to reducing the quantity of food consumed, interventions should also target the quality of food consumed to improve both asthma management and the overall health and well being of these patients.

Butyrate protects against disruption of the blood-milk barrier and moderates inflammatory responses in a model of mastitis induced by lipopolysaccharide

BACKGROUND AND PURPOSE

Short-chain fatty acids are fermentation end products produced by gut bacteria, which have been shown to ameliorate inflammatory bowel diseases and allergic asthma. However, the mechanism involved remains largely unknown. Here, we investigate the protective effects and mechanisms of sodium butyrate (SB) on LPS-induced mastitis model.

EXPERIMENTAL APPROACH

Effects of increasing doses of SB on blood-milk barrier function and inflammation are studied in BALB/c mice with LPS-induced mastitis. The underlying mechanisms of anti-inflammatory effects of SB were further investigated in LPS-stimulated mouse mammary epithelial cells (mMECs).

KEY RESULTS

The results show that SB decreased LPS-induced disruption in mammary tissues, infiltration of inflammatory cells and the levels of TNF-α, IL-6 and IL-1β. SB up-regulated the tight junction proteins occludin and claudin-3 and reduced blood-milk barrier permeability in LPS-induced mastitis. Studies in vitro revealed that SB inhibited LPS-induced inflammatory response by inhibition of the NF-κB signalling pathway and histone deacetylases in LPS-stimulated mMECs.

CONCLUSIONS AND IMPLICATIONS

In our model, SB protected against LPS-induced mastitis by preserving blood-milk barrier function and depressing pro-inflammatory responses, suggesting the potential use of SB as a prophylactic agent to protect blood-milk barrier function in mastitis.

Oxidative stress destabilizes protein arginine methyltransferase 4 via glycogen synthase kinase 3β to impede lung epithelial cell migration

Oxidative stress impacts normal cellular function leading to the pathogenesis of various diseases including pulmonary illnesses. Protein arginine methyltransferase 4 (PRMT4) is critical for normal lung alveolar epithelial cell development; however, the regulation of PRMT4 within such pulmonary diseases has yet to be elucidated. Using biochemical approaches, we uncovered that peroxide (H₂O₂) treatment decreases PRMT4 protein stability in murine lung epithelial (MLE12) cells to impede cell migration. Protein kinase glycogen synthase kinase 3β (GSK-3β) interacts with PRMT4 and catalyzes PRMT4 T132 phosphorylation that protects PRMT4 from ubiquitin proteasomal degradation. H₂O₂ downregulates GSK-3β to reduce PRMT4 at protein level. PRMT4 promotes cell migration and H₂O₂ degrades PRMT4 to inhibit lung epithelial cell migration. These observations demonstrate that oxidative stress destabilizes PRMT4 via GSK-3β signaling to impede lung epithelial cell migration that may hinder the lung repair and regeneration process.

Histone deacetylases (HDAC) in physiological and pathological bone remodelling

Histone deacetylases (HDACs)² play important roles in the epigenetic regulation of gene expression in cells and are emerging therapeutic targets for treating a wide range of diseases. HDAC inhibitors (HDACi)³ that act on multiple HDAC enzymes have been used clinically to treat a number of solid and hematological malignancies. HDACi are also currently being studied for their efficacy in non-malignant diseases, including pathologic bone loss, but this has necessitated a better understanding of the roles of individual HDAC enzymes, particularly the eleven zinc-containing isozymes. Selective isozyme-specific inhibitors currently being developed against class I HDACs (1, 2, 3 and 8) and class II HDACs (4, 5, 6, 7, 9 and 10) will be valuable tools for elucidating the roles played by individual HDACs in different physiological and pathological settings. Isozyme-specific HDACi promise to have greater efficacy and reduced side effects, as required for treating chronic disease over extended periods of time. This article reviews the current understanding of roles for individual HDAC isozymes and effects of HDACi on bone cells, (osteoblasts, osteoclasts and osteocytes), in relation to bone remodelling in conditions characterised by pathological bone loss, including periodontitis, rheumatoid arthritis and myeloma bone disease.

Effects of genetic factors to inhaled corticosteroid response in children with asthma: a literature review

Numerous studies have examined the association between pharmacogenetic effects and the response to inhaled corticosteroids (ICS) in patients with asthma. In fact, several single nucleotide polymorphisms of a number of candidate genes have been identified that might influence the clinical response to ICS in children with asthma. Their direct or indirect effects depend on their role in the inflammatory process in asthma or the anti-inflammatory action of corticosteroids, respectively. Among the genes identified, variants in T-box 21 (TBX21) and Fc fragment of IgE receptor II (FCER2) contribute indirectly to the variability in the response to ICS by altering the inflammatory mechanisms in asthma, while other genes such as corticotropin releasing hormone receptor 1 (CRHR1), nuclear receptor subfamily 3 group C member 1 (NR3C1), stress induced phosphoprotein 1 (STIP1), dual specificity phosphatase 1 (DUSP1), glucocorticoid induced 1 (GLCCI1), histone deacetylase 1 (HDAC), ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3), and vascular endothelial growth factors (VEGF) directly affect this variability through the anti-inflammatory mechanisms of ICS. The results to date indicate various potential genetic factors associated with the response to ICS, which could be utilized to predict the individual therapeutic response of children with asthma to ICS. Clinical trials are underway and their results are greatly anticipated. Further pharmacogenetic studies are needed to fully understand the effects of genetic variation on the response to ICS in children with asthma.

Epigenetic dysfunctional diseases and therapy for infection and inflammation

Even though the discovery of the term 'epigenetics' was in the 1940s, it has recently become one of the most promising and expanding fields to unravel the gene expression pattern in several diseases. The most well studied example is cancer, but other diseases like metabolic disorders, autism, or inflammation-associated diseases such as lung injury, autoimmune disease, asthma, and type-2 diabetes display aberrant gene expression and epigenetic regulation during their occurrence. The change in the epigenetic pattern of a gene may also alter gene function because of a change in the DNA status. Constant environmental pressure, lifestyle, as well as food habits are the other important parameters responsible for transgenerational inheritance of epigenetic traits. Discovery of epigenetic modifiers targeting DNA methylation and histone deacetylation enzymes could be an alternative source to treat or manipulate the pathogenesis of diseases. Particularly, the combination of epigenetic drugs such as 5-aza-2-deoxycytidine (Aza) and trichostatin A (TSA) are well studied to reduce inflammation in an acute lung injury model. It is important to understand the epigenetic machinery and the function of its components in specific diseases to develop targeted epigenetic therapy. Moreover, it is equally critical to know the specific inhibitors other than the widely used pan inhibitors in clinical trials and explore their roles in regulating specific genes in a more defined way during infection.

Modulation of inflammation and disease tolerance by DNA damage response pathways

The accurate replication and repair of DNA is central to organismal survival. This process is challenged by the many factors that can change genetic information such as replication errors and direct damage to the DNA molecule by chemical and physical agents. DNA damage can also result from microorganism invasion as an integral step of their life cycle or as collateral damage from host defense mechanisms against pathogens. Here we review the complex crosstalk of DNA damage response and immune response pathways that might be evolutionarily connected and argue that DNA damage response pathways can be explored therapeutically to induce disease tolerance through the activation of tissue damage control processes. Such approach may constitute the missing pillar in the treatment of critical illnesses caused by multiple organ failure, such as sepsis and septic shock.

Trichostatin A Inhibits Epithelial Mesenchymal Transition Induced by TGF-β1 in Airway Epithelium

Background and Objectives

Tissue remodeling is believed to cause recalcitrant chronic rhinosinusitis (CRS). Epithelial-mesenchymal transition (EMT) is a novel clinical therapeutic target in many chronic airway diseases related with tissue remodeling. The aim of this study was to investigate the effect of trichostatin A (TSA) on transforming growth factor (TGF)-β1-induced EMT in airway epithelium and nasal tissue.

Materials and Methods

A549 cells, primary nasal epithelial cells (PNECs), or inferior nasal turbinate organ culture were exposed to TSA prior to stimulation with TGF-β1. Expression levels of E-cadherin, vimentin, fibronectin, α-smooth muscle actin (SMA), histone deacetylase 2 (HDAC2), and HDAC4 were determined by western blotting and/or immunofluorescent staining. Hyperacetylation of histone H2 and H4 by TSA was measured by western blotting. After siHDAC transfection, the effects of HDAC2 and HDAC4 silencing on expression of E-cadherin, vimentin, fibronectin, α-SMA, HDAC2, and HDAC4 in TGF-β1-induced A549 were determined by RT-PCR and/or western blotting. We assessed the change in migration capacity of A549 cells by using cell migration assay and transwell invasion assay.

Results

TGF-β1 altered mRNA and protein expression levels of EMT markers including E-cadherin, vimentin, fibronectin, α-SMA, slug, and snail in A549 cells. Inhibition and silencing of HDAC2 and HDAC4 by TSA and siRNA enhanced TGF-β1-induced EMT in A549 cells. TSA blocked the effect of TGF-β1 on the migratory ability of A549 cells. In experiments using PNECs and inferior turbinate organ cultures, TSA suppressed expression of EMT markers induced by TGF-β1.

Conclusions

We showed that EMT is induced by TGF-β1 in airway epithelial cells and nasal tissue via activation of HDAC2 and HDAC4, and that inhibition of HDAC2 and HDAC4 by TSA reduces TGF-β1-induced EMT. This observation indicates that histone deacetylase inhibitors such as TSA could be potential candidates for treatment of recalcitrant CRS related with tissue remodeling.

The world of protein acetylation

Acetylation is one of the major post-translational protein modifications in the cell, with manifold effects on the protein level as well as on the metabolome level. The acetyl group, donated by the metabolite acetyl-coenzyme A, can be co- or post-translationally attached to either the α-amino group of the N-terminus of proteins or to the ε-amino group of lysine residues. These reactions are catalyzed by various N-terminal and lysine acetyltransferases. In case of lysine acetylation, the reaction is enzymatically reversible via tightly regulated and metabolism-dependent mechanisms. The interplay between acetylation and deacetylation is crucial for many important cellular processes. In recent years, our understanding of protein acetylation has increased significantly by global proteomics analyses and in depth functional studies. This review gives a general overview of protein acetylation and the respective acetyltransferases, and focuses on the regulation of metabolic processes and physiological consequences that come along with protein acetylation.

H3K9 acetylation change patterns in rats after exposure to traffic-related air pollution

Traffic-related air pollution (TRAP) has been acknowledged as a potential risk factor for numerous respiratory disorders including lung cancer; however, the exact mechanisms involved are still unclear. Here we investigated the effects of TRAP exposure on the H3K9 acetylation in rats. The exposure was performed in both spring and autumn with identical study procedures. In each season, 48 healthy Wistar rats were exposed to different levels of TRAP for 4 h, 7 d, 14 d, and 28 d, respectively. H3K9 acetylation levels in both the peripheral blood mononuclear cells (PBMCs) and lung tissues were quantified. Multiple linear regression was applied to assess the influence of air pollutants on H3K9 acetylation levels. The levels of PM2.5, PM10, and NO2 in the tunnel and crossroad groups were significantly higher than in the control group. The H3K9 acetylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, no significant association between the TRAP and H3K9 acetylation was found in 4h exposure window. However, in the 7 d exposure window, PM2.5 and PM10 exposures were associated with changes in H3K9 acetylation ranging from 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) per 1 μg/m(3) increase in the pollutant concentration. In addition, prolonged exposure of the rats in the tunnel showed that both PM2.5 and PM10 concentrations were positively associated with H3k9 acetylation in both PBMCs and lung tissues. The findings showed that 7-d and prolonged TRAP exposure could effectively increase the H3K9 acetylation level in both PBMCs and lung tissues of rats.

Therapeutic Effect of Histone Deacetylase Inhibitor, Sodium Butyrate, on Allergic Rhinitis In Vivo

Despite the well-documented therapeutic effects of histone deacetylase inhibitor (HDACi) on various diseases, including arthritis and asthma, the therapeutic effect of HDACi on allergic rhinitis remains unmentioned in the literature. This study investigated the therapeutic effect of sodium butyrate (SoB), a form of HDACi, on mice with allergic rhinitis. The results showed that the expression levels of histone deacetylase 1 (HDAC1), histone deacetylase 3 (HDAC3), and thymic stromal lymphopoietin (TSLP) were significantly upregulated in mice with allergic rhinitis, whereas H3 acetylation at lysine 9 (H3AcK9) was decreased. The intranasal application of SoB inhibited the expression levels of TSLP levels and upregulated the expression of H3AcK9 in a mouse model of allergic rhinitis. Furthermore, SoB treatment significantly decreased the increased levels of ovalbumin-specific IgE and improved clinical symptoms and nasal mucosa epithelial morphology in the mouse model of allergic rhinitis. In addition, we further demonstrated that SoB treatment significantly increased the serum levels of IL-2 and IFN-γ and decreased the serum levels of IL-4 and IL-10, correcting the Th1/Th2 imbalance in the mouse model of allergic rhinitis. Taken together, our study suggests that SoB has the potential to treat allergic rhinitis.

Identification of therapeutic targets for childhood severe asthmatics with DNA microarray

BACKGROUND

In this study, we aimed to discover potential gene targets for treating childhood asthmatics.

METHODS

With the microarray data downloaded from Gene Expression Omnibus (GEO) database, we explored the common differentially expressed genes (DEGs) in children with severe asthma and mild asthma (SA vs. MA) or healthy controls (SA vs. HC). Then we performed hierarchical clustering, function and pathway enrichment analysis for the common DEGs.

RESULTS

A total of 81 genes were identified to be differentially expressed in SA vs. MA and SA vs. HC group. Hierarchical clustering of the 81 DEGs could crudely separate the SA, MA and healthy individuals. The overrepresented GO terms of the common DEGs were related with lipid biosynthetic process (21.74%), pigment biosynthetic process (13.04%) and nucleoside monophosphate metabolic process (13.04%). Only one pathway was significantly enriched, which was the antigen processing and presentation pathway involved with CD4 and RFX gene.

CONCLUSIONS

The antigen processing and presentation pathway and lipid biosynthetic process may play roles in the pathogenesis of severe asthma. CD4 and RFX provide a therapeutic possibility for childhood asthma.

Antiallergic Effects of Trichostatin A in a Murine Model of Allergic Rhinitis

Objectives

Trichostatin A (TSA), an inhibitor of histone deacetylase, has been shown to play an important role in attenuating asthmatic inflammation. However, the effect of TSA in allergic rhinitis is not known. The aims of this study were to investigate the effect of TSA on allergic nasal inflammation and on the induction of regulatory T cells in a murine model of allergic rhinitis.

Methods

BALB/c mice were sensitized intraperitoneally with ovalbumin (OVA) and then challenged intranasally with OVA. TSA (1 mg/kg) was given to the treatment group, and multiple parameters of allergic responses were evaluated to determine the effects of TSA on allergic rhinitis. Allergic nasal symptom scores, including frequency of rubbing and sneezing, were checked. Eosinophil infiltrations were stained with Chromotrope 2R, and the expression levels of OVA-specific IgE, T-helper 1 (Th1) cytokine (interferon-gamma [IFN-γ]), Th2 cytokines (interleukin [IL] 4 and IL-5) and Treg (Foxp3, IL-10, and transforming growth factor-beta [TGF-β]) were measured by quantitative reverse transcription-polymerase chain reaction or enzyme-linked immunosorbent assay.

Results

TSA reduced the scores of allergic nasal symptoms and the amount of eosinophil infiltration into the nasal mucosa. TSA suppressed OVA-specific IgE levels and reduced expression of the IL-4 and IL-5. However, the expression of IFN-γ was unchanged in the treatment group. The levels of Foxp3, IL-10, and TGF-β were increased in pretreatment with TSA as compared to control group.

Conclusion

This study shows that TSA induced antiallergic effects by decreasing eosinophilic infiltration and Th2 cytokines in a murine model of allergic rhinitis via regulation of Tregs. Thus, TSA may be considered a potentially therapeutic agent in treating allergic rhinitis.

The Hyaluronic Acid-HDAC3-miRNA Network in Allergic Inflammation

We previously reported the anti-allergic effect of high molecular weight form of hyaluronic acid (HMW-HA). In doing so, HA targets CD44 and inhibits FcεRI signaling and cross-talk between epidermal growth factor receptor (EGFR) and FcεRI. We previously reported the role of histone deacetylases (HDACs) in allergic inflammation and allergic inflammation-promoted enhanced tumorigenic potential. We reported regulatory role of HA in the expression of HDAC3. In this review, we will discuss molecular mechanisms associated with anti-allergic effect of HA in relation with HDACs. The role of microRNAs (miRNAs) in allergic inflammation has been reported. We will also discuss the role of miRNAs in allergic inflammation in relation with HA-mediated anti-allergic effects.

Short-chain fatty acids induce both effector and regulatory T cells by suppression of histone deacetylases and regulation of the mTOR-S6K pathway

Microbial metabolites, such as short-chain fatty acids (SCFAs), are highly produced in the intestine and potentially regulate the immune system. We studied the function of SCFAs in the regulation of T-cell differentiation into effector and regulatory T cells. We report that SCFAs can directly promote T-cell differentiation into T cells producing interleukin-17 (IL-17), interferon-γ, and/or IL-10 depending on cytokine milieu. This effect of SCFAs on T cells is independent of GPR41 or GPR43, but dependent on direct histone deacetylase (HDAC) inhibitor activity. Inhibition of HDACs in T cells by SCFAs increased the acetylation of p70 S6 kinase and phosphorylation rS6, regulating the mTOR pathway required for generation of Th17 (T helper type 17), Th1, and IL-10(+) T cells. Acetate (C2) administration enhanced the induction of Th1 and Th17 cells during Citrobacter rodentium infection, but decreased anti-CD3-induced inflammation in an IL-10-dependent manner. Our results indicate that SCFAs promote T-cell differentiation into both effector and regulatory T cells to promote either immunity or immune tolerance depending on immunological milieu.

Bronchial epithelial cells induce alternatively activated dendritic cells dependent on glucocorticoid receptor signaling

Airway epithelial cells mount a tolerogenic microenvironment that reduces the proinflammatory potential of respiratory dendritic cells (DCs). We recently demonstrated that tracheal epithelial cells continuously secrete soluble mediators that affect the reactivity of local innate immune cells. Using transcriptional profiling, we now observed that conditioning of DCs by tracheal epithelial cells regulated 98 genes under homeostatic conditions. Among the most upregulated genes were Ms4a8a and Ym1, marker genes of alternatively activated myeloid cells. Ex vivo analysis of respiratory DCs from nonchallenged mice confirmed a phenotype of alternative activation. Bioinformatic analysis showed an overrepresentation of hormone-nuclear receptors within the regulated genes, among which was the glucocorticoid receptor. In line with a role for glucocorticoids, pharmacological blockade as well as genetic manipulation of the glucocorticoid receptor within DCs inhibited Ms4a8a and Ym1 expression as well as MHC class II and CD86 regulation upon epithelial cell conditioning. Within epithelial cell-conditioned medium, low amounts of glucocorticoids were present. Further analysis showed that airway epithelial cells did not produce glucocorticoids de novo, yet were able to reactivate inactive dehydrocorticosterone enzymatically. The results show that airway epithelial cells regulate local immune responses, and this modulation involves local production of glucocorticoids and induction of an alternative activation phenotype in DCs.

Valproic acid enhances the effect of bone marrow-derived mononuclear cells in a rat ischemic stroke model

Bone marrow derived mononuclear cell (MNC) transplantation is a potential therapy for ischemic stroke. Here, we hypothesized that valproic acid (VPA) would modulate transplantation effects of MNCs in a rat ischemic stroke model. Male Sprague-Dawley rats were subjected to transient 90min middle cerebral artery occlusion. Infarct volume, neurological outcome, and immunohistological assessments were performed 7 days after ischemia. MNCs injected 6 or 24h but not 48 or 72h after ischemia significantly reduced infarct volume and improved neurological deficits. We then tested whether the therapeutic window of MNC transplantation could be expanded through combination therapy with VPA. MNC transplantation at 48h combined with VPA injection three times at 47, 53, and 72h after ischemia significantly ameliorated infarct volume and neurological deficits compared to a vehicle group. Combination therapy reduced the number of myeloperoxidase-positive cells, ionized calcium binding adapter molecule 1-positive cells, tumor necrosis factor-α-positive cells, and von Willebrand factor-positive cells in the ischemic boundary zone. The number of engrafted MNCs that were fluorescently labeled with PKH 26, on day 7, was significantly higher after combination therapy than after that MNC transplantation alone. Our results demonstrated that combination therapy with VPA enhanced the anti-inflammatory and vasculo-protective effects against endothelial damage following ischemia, and increased the survival of transplanted cells, leading to expansion of the therapeutic time window for MNC transplantation. Together, these findings suggest that VPA may be an appropriate partner for cell-based treatment of ischemic stroke.

Modulation of cytokine production by drugs with antiepileptic or mood stabilizer properties in anti-CD3- and anti-Cd40-stimulated blood in vitro

Increased cytokine production possibly due to oxidative stress has repeatedly been shown to play a pivotal role in the pathophysiology of epilepsy and bipolar disorder. Recent in vitro and animal studies of valproic acid (VPA) report antioxidative and anti-inflammatory properties, and suppression of interleukin (IL)-6 and tumor necrosis factor (TNF)-α. We tested the effect of drugs with antiepileptic or mood stabilizer properties, namely, primidone (PRM), carbamazepine (CBZ), levetiracetam (LEV), lamotrigine (LTG), VPA, oxcarbazepine (OXC), topiramate (TPM), phenobarbital (PB), and lithium on the production of the following cytokines in vitro: interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-17, IL-22, and TNF-α. We performed a whole blood assay with stimulated blood of 14 healthy female subjects. Anti-human CD3 monoclonal antibody OKT3, combined with 5C3 antibody against CD40, was used as stimulant. We found a significant reduction of IL-1 and IL-2 levels with all tested drugs other than lithium in the CD3/5C3-stimulated blood; VPA led to a decrease in IL-1β, IL-2, IL-4, IL-6, IL-17, and TNF-α production, which substantiates and adds knowledge to current hypotheses on VPA's anti-inflammatory properties.

Histone deacetylase-3 mediates positive feedback relationship between anaphylaxis and tumor metastasis

Allergic inflammation has been known to enhance the metastatic potential of tumor cells. The role of histone deacetylase-3 (HDAC3) in allergic skin inflammation was reported. We investigated HDAC3 involvement in the allergic inflammation-promotion of metastatic potential of tumor cells. Passive systemic anaphylaxis (PSA) induced HDAC3 expression and FcεRI signaling in BALB/c mice. PSA enhanced the tumorigenic and metastatic potential of mouse melanoma cells in HDAC3- and monocyte chemoattractant protein 1-(MCP1)-dependent manner. The PSA-mediated enhancement of metastatic potential involved the induction of HDAC3, MCP1, and CD11b (a macrophage marker) expression in the lung tumor tissues. We examined an interaction between anaphylaxis and tumor growth and metastasis at the molecular level. Conditioned medium from antigen-stimulated bone marrow-derived mouse mast cell cultures induced the expression of HDAC3, MCP1, and CCR2, a receptor for MCP1, in B16F1 mouse melanoma cells and enhanced migration and invasion potential of B16F1 cells. The conditioned medium from B16F10 cultures induced the activation of FcεRI signaling in lung mast cells in an HDAC3-dependent manner. FcεRI signaling was observed in lung tumors derived from B16F10 cells. Target scan analysis predicted HDAC3 to be as a target of miR-384, and miR-384 and HDAC3 were found to form a feedback regulatory loop. miR-384, which is decreased by PSA, negatively regulated HDAC3 expression, allergic inflammation, and the positive feedback regulatory loop between anaphylaxis and tumor metastasis. We show the miR-384/HDAC3 feedback loop to be a novel regulator of the positive feedback relationship between anaphylaxis and tumor metastasis.

A polymorphism in the histone deacetylase 1 gene is associated with the response to corticosteroids in asthmatics

BACKGROUND/AIMS

Recent investigations suggest that histone deacetylase 1 (HDAC1) and HDAC2 may be target molecules to predict therapeutic responses to corticosteroids. We evaluated the effects of variation in HDAC1 and HDAC2 on the response to corticosteroids in asthmatics.

METHODS

Two single nucleotide polymorphisms (SNPs) were selected after resequencing HDAC1 and HDAC2. For the first analysis, we evaluated the association between those SNPs and asthma severity in 477 asthmatics. For the second analysis, we evaluated the effects of these SNPs on lung function improvements in response to corticosteroid treatment in 35 independent adult asthmatics and 70 childhood asthmatics.

RESULTS

We found that one SNP in HDAC1 (rs1741981) was significantly related to asthma severity in a recessive model (corrected p = 0.036). Adult asthmatics who were homozygous for the minor allele of rs1741981 showed significantly lower % forced expiratory volume in 1 second (%FEV1) increases in response to systemic corticosteroids treatment compared with the heterozygotes or those homozygous for the major allele (12.7% ± 7.2% vs. 37.4% ± 33.7%, p = 0.018). Similarly, childhood asthmatics who were homozygous for the minor allele of rs1741981 showed significantly lower %FEV1 increases in response to inhaled corticosteroid treatment compared with the heterozygotes or those homozygous for the major allele (14.1% ± 5.9% vs. 19.4% ± 8.9%, p = 0.035).

CONCLUSIONS

The present study demonstrated that rs1741981 in HDAC1 was significantly associated with the response to corticosteroid treatment in asthmatics.

Functional KCa3.1 channels regulate steroid insensitivity in bronchial smooth muscle cells

Identifying the factors responsible for relative glucocorticosteroid (GC) resistance present in patients with severe asthma and finding tools to reverse it are of paramount importance. In asthma we see in vivo evidence of GC-resistant pathways in airway smooth muscle (ASM) bundles that can be modeled in vitro by exposing cultured ASM cells to TNF-α/IFN-γ. This action drives GC insensitivity via protein phosphatase 5-dependent impairment of GC receptor phosphorylation. In this study, we investigated whether KCa3.1 ion channels modulate the activity of GC-resistant pathways using our ASM model of GC insensitivity. Immunohistochemical staining of endobronchial biopsies revealed that KCa3.1 channels are localized to the plasma membrane and nucleus of ASM in both healthy controls and asthmatic patients, irrespective of disease severity. Western blot assays and immunofluorescence staining confirmed the nuclear localization of KCa3.1 channels in ASM cells. The functional importance of KCa3.1 channels in the regulation of GC-resistant chemokines induced by TNF-α/IFN-γ was assessed using complementary inhibitory strategies, including KCa3.1 blockers (TRAM-34 and ICA-17043) or KCa3.1-specific small hairpin RNA delivered by adenoviruses. KCa3.1 channel blockade led to a significant reduction of fluticasone-resistant CX3CL1, CCL5, and CCL11 gene and protein expression. KCa3.1 channel blockade also restored fluticasone-induced GC receptor-α phosphorylation at Ser(211) and transactivation properties via the suppression of cytokine-induced protein phosphatase 5 expression. The effect of KCa3.1 blockade was evident in ASM cells from both healthy controls and asthmatic subjects. In summary, KCa3.1 channels contribute to the regulation of GC-resistant inflammatory pathways in ASM cells: blocking KCa3.1 channels may enhance corticosteroid activity in severe asthma.

Regulation and function of epithelial secreted phospholipase A2 group X in asthma

RATIONALE

Indirect airway hyperresponsiveness (AHR) is a fundamental feature of asthma that is manifest as exercise-induced bronchoconstriction (EIB). Secreted phospholipase A2 group X (sPLA2-X) plays a key role in regulating eicosanoid formation and the development of inflammation and AHR in murine models.

OBJECTIVES

We sought to examine sPLA2-X in the airway epithelium and airway wall of patients with asthma, the relationship to AHR in humans, and the regulation and function of sPLA2-X within the epithelium.

METHODS

We precisely phenotyped 34 patients with asthma (19 with and 15 without EIB) and 10 normal control subjects to examine in vivo differences in epithelial gene expression, quantitative morphometry of endobronchial biopsies, and levels of secreted protein. The regulation of sPLA2-X gene (PLA2G10) expression was examined in primary airway epithelial cell cultures. The function of epithelial sPLA2-X in eicosanoid formation was examined using PLA2 inhibitors and murine tracheal epithelial cells with Pla2g10 deletion.

MEASUREMENTS AND MAIN RESULTS

We found that sPLA2-X protein is increased in the airways of patients with asthma and that epithelial-derived sPLA2-X may be increased in association with indirect AHR. The expression of sPLA2-X increases during in vitro epithelial differentiation; is regulated by inflammatory signals including tumor necrosis factor, IL-13, and IL-17; and is both secreted from the epithelium and directly participates in the release of arachidonic acid by epithelial cells.

CONCLUSIONS

These data reveal a relationship between epithelial-derived sPLA2-X and indirect AHR in asthma and that sPLA2-X serves as an epithelial regulator of inflammatory eicosanoid formation. Therapies targeting epithelial sPLA2-X may be useful in asthma.

Role of comorbid conditions in asthma hospitalizations in the south of France

BACKGROUND

Reasons for asthma hospitalizations are dynamic and complex. Comorbid conditions are important contributors to most chronic diseases today. We aim to characterize and describe risk factors associated with hospitalizations due to asthma in the Languedoc-Roussillon region (France) in 2009.

METHODS

Programme de Médicalisation des Systèmes d'Information (PMSI) data records from 2009 were sorted using selected International Classification of Diseases (ICD10) codes eliciting three groups of asthma hospitalizations according to acute severity. All available data including demographics, comorbid conditions, past hospitalizations either related or unrelated to asthma, seasonality and distance to medical facilities were used to compare the subjects within the three groups.

RESULTS

One thousand two hundred and eighty-nine hospitalizations due to asthma exacerbation were found, concerning 1122 patients. We observed significant differences within the groups, using univariate analysis, concerning duration of hospitalizations (mean ± SD, 4.9 ± 5.9 days vs 6.4 ± 6.8 vs 15.8 ± 16.8, P < 0.001), deaths (percentage, 0.03% vs 1.50% vs 9.20%, P < 0.001) and numbers of comorbid conditions (0.80 ± 0.95 vs 0.75 ± 0.97 vs 1.74 ± 1.36, P < 0.001). Recurrent admissions for asthma during the period 2006-2008 were significantly more frequent in the more severe group (1.93 ± 3.91 vs 2.56 ± 4.47 vs 2.81 ± 3.97, P = 0.006). In the multivariate model, age and number of comorbid conditions were independently associated with severe hospitalizations and deaths.

CONCLUSIONS

Asthma hospitalizations can be appropriately assessed using PMSI coding databases. In this study, age and the presence of comorbid conditions are the major risk factors for asthma hospitalizations and deaths.

Valproic acid attenuates ischemia-reperfusion injury in the rat brain through inhibition of oxidative stress and inflammation

Valproic acid (VPA), widely used in clinical contexts for the treatment of seizures and bipolar mood disorder, has neuroprotective properties in cellular and animal models. However, the precise mechanisms underlying its neuroprotection against stroke remain unknown. In the present study, we explored the effect of VPA on experimental ischemic stroke. Male Sprague-Dawley rats were subjected to middle cerebral artery occlusion for 90 min, followed by reperfusion. The animals received a single injection of VPA (300 mg/kg) immediately, 90, or 270 min after the induction of ischemia. Vehicle-treated animals underwent the same procedure with physiological saline. Infarct volume and neurological symptoms were evaluated 24 h after reperfusion. Immunohistochemical staining for myeloperoxidase (MPO), microglia (Iba1), 4-hydroxy-2-nonenal (4-HNE), or 8-hydroxy-deoxyguanosine (8-OHdG) was performed. Ischemic boundary zone cell death was determined by TUNEL staining. VPA injected immediately or 90 min after ischemia induction significantly reduced infarct volume and improved neurological deficit compared with vehicle (P<0.05). VPA was ineffective when given 270 min after ischemia induction. VPA significantly reduced TUNEL-positive cells, MPO-positive cells, Iba1-positive cells, 4-HNE-positive cells, and 8-OHdG-positive cells compared with vehicle in the ischemic boundary zone (P<0.05). The therapeutic time window for single injection of VPA is between 0 and 90 min in this model. Our results demonstrate that single injection of VPA may have anti-inflammatory as well as antioxidative effects, leading to reduced cell death in ischemia-reperfusion injury.