Role of histamine in the pathophysiology of asthma: immunomodulatory and anti-inflammatory activities of H1-receptor antagonists

Testosterone Enhances KV Currents and Airway Smooth Muscle Relaxation Induced by ATP and UTP through P2Y4 Receptors and Adenylyl Cyclase Pathway

Numerous studies suggest the involvement of adenosine-5'-triphosphate (ATP) and similar nucleotides in the pathophysiology of asthma. Androgens, such as testosterone (TES), are proposed to alleviate asthma symptoms in young men. ATP and uridine-5'-triphosphate (UTP) relax the airway smooth muscle (ASM) via purinergic P2Y2 and P2Y4 receptors and K+ channel opening. We previously demonstrated that TES increased the expression of voltage-dependent K+ (KV) channels in ASM. This study investigates how TES may potentiate ASM relaxation induced by ATP and UTP. Tracheal tissues treated with or without TES (control group) from young male guinea pigs were used. In organ baths, tracheas exposed to TES (40 nM for 48 h) showed enhanced ATP- and UTP-evoked relaxation. Tetraethylammonium, a K+ channel blocker, annulled this effect. Patch-clamp experiments in tracheal myocytes showed that TES also increased ATP- and UTP-induced K+ currents, and this effect was abolished with flutamide (an androgen receptor antagonist). KV channels were involved in this phenomenon, which was demonstrated by inhibition with 4-aminopyridine. RB2 (an antagonist of almost all P2Y receptors except for P2Y2), as well as N-ethylmaleimide and SQ 22,536 (inhibitors of G proteins and adenylyl cyclase, respectively), attenuated the enhancement of the K+ currents induced by TES. Immunofluorescence and immunohistochemistry studies revealed that TES did not modify the expression of P2Y4 receptors or COX-1 and COX-2, while we have demonstrated that this androgen augmented the expression of KV1.2 and KV1.5 channels in ASM. Thus, TES leads to the upregulation of P2Y4 signaling and KV channels in guinea pig ASM, enhancing ATP and UTP relaxation responses, which likely limits the severity of bronchospasm in young males.

Immunologic Basis of Type 2 Biologics for Severe Asthma

Asthma is a chronic airway inflammatory disease characterized by reversible airway obstruction and airway hyperreactivity to various environmental stimuli, leading to recurrent cough, dyspnea, and wheezing episodes. Regarding inflammatory mechanisms, type 2/eosinophilic inflammation along with activated mast cells is the major one; however, diverse mechanisms, including structural cells-derived and non-type 2/neutrophilic inflammations are involved, presenting heterogenous phenotypes. Although most asthmatic patients could be properly controlled by the guided treatment, patients with severe asthma (SA; classified as a treatment-refractory group) suffer from uncontrolled symptoms with frequent asthma exacerbations even on regular anti-inflammatory medications, raising needs for additional controllers, including biologics that target specific molecules found in asthmatic airway, and achieving the precision medicine for asthma. This review summarizes the immunologic basis of airway inflammatory mechanisms and current biologics for SA in order to address unmet needs for future targets.

Astragaloside IV suppresses histamine-induced inflammatory factors and mucin 5 subtype AC overproduction in nasal epithelial cells via regulation of inflammation-related genes

Allergic rhinitis (AR) is a symptomatic allergic disease that leads to severe inflammation. Astragaloside IV (AS-IV) is a primary active component of Astragalus membranaceus and exerts immune-regulation and anti-inflammatory effects. However, the pharmacological effect of AS-IV in the nasal epithelial cells (NECs) has not been reported. The present study aimed to assess the effect of AS-IV on inflammatory cytokines and mucin 5 subtype AC (MUC5AC) overproduction in histamine (His)-stimulated NECs and its underlying mechanism. NECs were stimulated with or without His for 24 h in the absence or presence of AS-IV. The levels of inflammatory cytokines including IL-6, IL-8, MCP-1, IL-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), eotaxin, and MUC5AC were assayed. Our findings indicated that AS-IV inhibited His-evoked release and expression of inflammatory cytokines and MUC5AC in NECs. RNA-seq analyses indicated the significant changes in expression levels involved in inflammation genes upon treatment of His-induced NECs with AS-IV. Our findings indicated that AS-IV inhibited His-evoked inflammatory cytokines secretion and MUC5AC overproduction in NECs, which were partly mediated by regulation of inflammation-related genes. Therefore, our findings provided a scientific basis for the development of AS-IV as an effective agent for clinical therapeutic strategy in the treatment of AR.

Organic Cation Transporters in the Lung-Current and Emerging (Patho)Physiological and Pharmacological Concepts

Organic cation transporters (OCT) 1, 2 and 3 and novel organic cation transporters (OCTN) 1 and 2 of the solute carrier 22 (SLC22) family are involved in the cellular transport of endogenous compounds such as neurotransmitters, l-carnitine and ergothioneine. OCT/Ns have also been implicated in the transport of xenobiotics across various biological barriers, for example biguanides and histamine receptor antagonists. In addition, several drugs used in the treatment of respiratory disorders are cations at physiological pH and potential substrates of OCT/Ns. OCT/Ns may also be associated with the development of chronic lung diseases such as allergic asthma and chronic obstructive pulmonary disease (COPD) and, thus, are possible new drug targets. As part of the Special Issue "Physiology, Biochemistry and Pharmacology of Transporters for Organic Cations", this review provides an overview of recent findings on the (patho)physiological and pharmacological functions of organic cation transporters in the lung.

The effect of pulmonary surfactant on the airway smooth muscle after lipopolysaccharide exposure and its mechanisms

Pulmonary surfactant has a relaxing effect on the airway smooth muscle (ASM), which suggests its role in the pathogenesis of respiratory diseases associated with hyperreactivity of the ASM, such as asthma and chronic obstructive pulmonary disease (COPD). The ASM tone may be directly or indirectly modified by bacterial wall component lipopolysaccharide (LPS). This study elucidated the effect of LPS on the ASM reactivity and the role of surfactant in this interaction. The experiments were performed using ASM of adult guinea pigs by in vitro method of tissue organ bath (ASM unexposed-healthy or exposed to LPS under in vitro conditions) and ASM of animals intraperitoneally injected with LPS at a dose 1 mg/kg of b.w. once a day during 4-day period. Variable response of LPS was controlled by cyclooxygenase inhibitor indomethacin and relaxing effect of exogenous surfactant was studied using leukotriene and histamine receptor antagonists. The exogenous surfactant has relaxing effect on the ASM, but does not reverse LPS-induced smooth muscle contraction. The results further indicate participation of prostanoids and potential involvement of leukotriene and histamine H1 receptors in the airway smooth muscle contraction during LPS exposure.

Esculetin inhibits histamine-induced expression of inflammatory cytokines and mucin in nasal epithelial cells

Allergic rhinitis (AR) is a type of respiratory disease closely associated with chronic inflammation. Esculetin is a natural coumarin derivative and has been reported to possess anti-allergic and anti-inflammatory effects. However, the roles of esculetin in AR have not been studied. In this study, we aimed to examine the effect of esculetin on AR using an in vitro model. The human nasal epithelial cells (HNEpC) were stimulated by histamine for 24 hours with or without the pretreatment of esculetin. The mRNA levels and production of inflammatory cytokines including IL-6 and IL-8, as well as mucin 5AC (MUC5AC) were measured using qRT-PCR and ELISA, respectively. The results showed that esculetin suppressed histamine-induced expression and secretion of IL-6, IL-8, and MUC5AC in HNEpCs. Furthermore, we examined the effect of esculetin on NF-κB pathway by detecting the expression levels of NF-κB p65, p-p65 and IκBα using western blot analysis. Esculetin treatment suppressed the histamine-induced p-p65 expression and p-IκBα degradation. Inhibiting NF-κB pathway suppressed histamine-induced production of IL-6, IL-8, and MUC5AC in HNEpCs. These findings suggested that esculetin suppressed histamine-induced production of inflammatory cytokines and mucin in HNEpCs, which were partly mediated by the inhibition of NF-κB pathway.

Magnesium in man: implications for health and disease

Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.

The extract of Zataria multiflora affect tracheal responsiveness, serum levels of NO, nitrite, PLA2, TP and histamine in sensitized Guinea pigs

ETHNOPHARMACOLOGICAL RELEVANCE

Different therapeutic effects for Zataria multiflora have been described in Iranian traditional medicine. In addition anti-inflammatory and anti-oxidant effects of this plant were previously described. The effect of the extract of Zataria multiflora on tracheal responsiveness (TR) and inflammatory mediators of sensitized guinea pigs was examined.

MATERIALS AND METHODS

Five groups of sensitized guinea pigs to ovalbumin (OA) were given drinking water alone, drinking water containing three concentrations of the extract and dexamethasone. TR to methacholine and OA, serum levels of NO, nitrite, PLA2, TP and histamine were measured (n=6, for each groups).

RESULTS

TR to methacholine and OA, serum levels of NO, nitrite, PLA2, TP and histamine were increased in sensitized animals compared to control group (p<0.05 to p<0.001). Treatment of sensitized animals with dexamethasone and most concentration of the extract lead to significantly decrease in all measured parameters compared to sensitized group (p<0.05 to p<0.001) except TP and histamine levels in treated group with dexamethasone.

CONCLUSION

These results showed a preventive effect of the extract of Zataria multiflora on tracheal responsiveness, serum level of NO, nitrite, total protein, PLA2 and histamine in sensitized guinea pigs which was equal or even more potent than dexamethasone at used concentrations.

Bile acid increases expression of the histamine-producing enzyme, histidine decarboxylase, in gastric cells

AIM: To investigate the effect of bile acid on the expression of histidine decarboxylase (HDC), which is a major enzyme involved in histamine production, and gene expression of gastric transcription factors upon cooperative activation.

METHODS: HDC expression was examined by immunohistochemistry, reverse transcriptase polymerase chain reaction, and promoter assay in human gastric precancerous tissues, normal stomach tissue, and gastric cancer cell lines. The relationship between gastric precancerous state and HDC expression induced by bile acid was determined. The association between the expression of HDC and various specific transcription factors in gastric cells was also evaluated. MKN45 and AGS human gastric carcinoma cell lines were transfected with farnesoid X receptor (FXR), small heterodimer partner (SHP), and caudal-type homeodomain transcription factor (CDX)1 expression plasmids. The effects of various transcription factors on HDC expression were monitored by luciferase-reporter promoter assay.

RESULTS: Histamine production and secretion in the stomach play critical roles in gastric acid secretion and in the pathogenesis of gastric diseases. Here, we show that bile acid increased the expression of HDC, which is a rate-limiting enzyme of the histamine production pathway. FXR was found to be a primary regulatory transcription factor for bile acid-induced HDC expression. In addition, the transcription factors CDX1 and SHP synergistically enhanced bile acid-induced elevation of HDC gene expression. We confirmed similar expression patterns for HDC, CDX1, and SHP in patient tissues.

CONCLUSION: HDC production in the stomach is associated with bile acid exposure and its related transcriptional regulation network of FXR, SHP, and CDX1.

Induction of regulator of G-protein signaling 2 expression by long-acting β2-adrenoceptor agonists and glucocorticoids in human airway epithelial cells

In asthma and chronic obstructive pulmonary disease (COPD) multiple mediators act on Gαq-linked G-protein-coupled receptors (GPCRs) to cause bronchoconstriction. However, acting on the airway epithelium, such mediators may also elicit inflammatory responses. In human bronchial epithelial BEAS-2B cells (bronchial epithelium + adenovirus 12-SV40 hybrid), regulator of G-protein signaling (RGS) 2 mRNA and protein were synergistically induced in response to combinations of long-acting β2-adrenoceptor agonist (LABA) (salmeterol, formoterol) plus glucocorticoid (dexamethasone, fluticasone propionate, budesonide). Equivalent responses occurred in primary human bronchial epithelial cells. Concentrations of glucocorticoid plus LABA required to induce RGS2 expression in BEAS-2B cells were consistent with the levels achieved therapeutically in the lungs. As RGS2 is a GTPase-activating protein that switches off Gαq, intracellular free calcium ([Ca(2+)]i) flux was used as a surrogate of responses induced by histamine, methacholine, and the thromboxane receptor agonist U46619 [(Z)-7-[(1S,4R,5R,6S)-5-[(E,3S)-3-hydroxyoct-1-enyl]-3-oxabicyclo[2.2.1]heptan-6-yl]hept-5-enoic acid]. This was significantly attenuated by salmeterol plus dexamethasone pretreatment, or RGS2 overexpression, and the protective effect of salmeterol plus dexamethasone was abolished by RGS2 RNA silencing. Although methacholine and U46619 induced interleukin-8 (IL-8) release and this was inhibited by RGS2 overexpression, the repression of U46619-induced IL-8 release by salmeterol plus dexamethasone was unaffected by RGS2 knockdown. Given a role for Gαq-mediated pathways in inducing IL-8 release, we propose that RGS2 acts redundantly with other effector processes to repress IL-8 expression. Thus, RGS2 expression is a novel effector mechanism in the airway epithelium that is induced by glucocorticoid/LABA combinations. This could contribute to the efficacy of glucocorticoid/LABA combinations in asthma and COPD.

The effect of the extract of Crocus sativus and its constituent safranal, on lung pathology and lung inflammation of ovalbumin sensitized guinea-pigs

Different pharmacological effects of Crocus sativus have been demonstrated on guinea pig tracheal chains in previous studies. In the present study, the prophylactic effect of the extract of C. sativus and its constituent, safranal on lung pathology and total and differential white blood cells (WBC) of sensitized guinea pigs was examined. Guinea pigs were sensitized with injection and inhalation of ovalbumin (OA). One group of sensitized guinea pigs were given drinking water alone (group S) and three groups were given drinking water containing three concentrations of safranal (S+SA1, S+SA2 and S+SA3 groups), three groups, drinking water containing three concentrations of extract (S+CS1, S+CS2 and S+CS3 groups) and one group drinking water containing one concentration of dexamethasone (S+D group) (n=6, for all groups). The lung pathology was evaluated in control, non treated and treated sensitized groups. Total and differential WBC counts of lung lavage were also examined. All pathological indices in group S showed significant increased compared to control group (p<0.05 for lung congestion and p<0.001 for other groups). Total WBC number (p<0.001), eosinophyl percentage (p<0.001) in lung lavage and serum histamine levels (p<0.01) were also increased in sensitized animals compared to those of controls. Treatment of S animals with dexamethasone, all concentrations of the extract and safranal significantly improved lung pathological changes, most types of WBC and serum histamine levels compared to group S (p<0.05-0.001). Treatment of S group with first concentration of safranal also decreased total WBC. Treatment with safranal was more effective in improvement of most pathological changes, total and differential WBC count as well as serum histamine level (p<0.05-0.001). These results showed a preventive effect of the extract of C. sativus and its constituent safranal on lung inflammation of sensitized guinea pigs. The results also showed that the effect of the plant is perhaps due to its constituent safranal.

Investigation of in vitro and in vivo anti-asthmatic properties of Siphonochilus aethiopicus

AIM OF THE STUDY

Asthma is a chronic inflammatory disease of the lungs, characterized by increased sensitivity to bronchoconstriction associated with infiltration of immune cells, mucus hypersecretion and structural remodelling of the airways. In South Africa, the indigenous plant Siphonochilus aethiopicus, is used by traditional health practitioners to treat colds, wheezing of the chest, coughs, influenza, sinus problems and mild asthma. In this study we aimed to investigate the potential anti-inflammatory and anti-allergic properties of S. aethiopicus in vitro and its efficacy in a mouse model of allergic asthma.

MATERIALS AND METHODS

The dried and powdered S. aethiopicus plant material was extracted separately with organic solvents (diethyl ether, ethanol) and water. Dried extracts as well as a purified furanoterpenoid compound present in the extracts were screened in vitro in a glucocorticoid and histamine H(1) receptor binding assay and a phosphodiesterase IV enzyme inhibition assay. Extracts were also evaluated for efficacy against ovalbumin (OVA)-induced allergic airway disease in mice.

RESULTS

Biological assaying of extracts of the plant and the isolated furanoterpenoid showed significant in vitro inhibition of glucocorticoid and histamine H(1) receptor binding and phosphodiesterase IV activity, supporting a possible anti-inflammatory, anti-allergic and bronchodilatory effect. Administration of S. aethiopicus extracts to OVA-sensitized and challenged mice significantly reduced lung inflammation and the percentage of eosinophils in bronchoalveolar lavage fluid but did not influence airway hyperreactivity.

CONCLUSION

This study provides evidence that S. aethiopicus has anti-inflammatory and anti-allergic properties in vitro and in vivo. These findings may support anecdotal accounts of its effectiveness against asthma, sinusitis, colds and flu.

Increased muscarinic receptor activity of airway smooth muscle isolated from a mouse model of allergic asthma

The mechanisms leading to airway hyper-responsiveness (AHR) in asthma are still not fully understood. AHR could be produced by hypersensitivity of the airway smooth muscle or hyperreactivity of the airways. This study was conducted to ascertain whether AHR in a murine model of asthma is produced by changes at the level of the airway smooth muscle. Airway smooth muscle responses were characterised in vitro in isolated trachea spirals from naive mice and from an acute ovalbumin (OVA) challenge model of allergic asthma. AHR was investigated in vivo in conscious, freely moving mice. Inflammatory cell influx into the lungs and antibody responses to the antigen were also measured. In vitro study of tracheal airway smooth muscle from naïve mice demonstrated concentration-related contractions to methacholine and 5-HT, but no responses to histamine or adenosine or its stable analogue, 5'-N-ethyl-carboxamidoadenosine. The contractions to 5-HT were inhibited by ketanserin and alosetron indicating involvement of 5-HT(2A) and 5-HT(3) receptors, respectively. In an acute model of allergic asthma, OVA-treated mice were shown to be atopic by inflammatory cell influx to the lungs after OVA challenge, increases in total IgE and OVA-specific IgG levels and contractions to OVA in isolated trachea. In the asthmatic model, AHR to methacholine was demonstrated in conscious, freely moving mice in vivo and in isolated trachea in vitro 24 and 72h after OVA challenge. No AHR in vitro was seen for 5-HT, histamine or adenosine. These results suggest that, in our mouse model of asthma, changes occur at the level of the muscarinic receptor transduction pathway of coupling to airway smooth muscle contraction. These changes are maintained when tissues are removed from the inflammatory environment and for at least 3 days.

Fexofenadine: biochemical, pharmacokinetic and pharmacodynamic properties and its unique role in allergic disorders

BACKGROUND

Fexofenadine is one of several second-generation H(1)-antihistamines approved for the treatment of various allergic disorders; however, it shows numerous unique properties that make it an optimal choice for many patients.

OBJECTIVE

To review the pharmacology, efficacy and safety of fexofenadine and the attributes differentiating it from other H(1)-antihistamines.

METHODS

We performed a literature search in PubMed/MEDLINE (1966 - March 2009) using the keywords fexofenadine, antihistamine, allergic rhinitis and chronic urticaria. We also reviewed data provided by the manufacturer in addition to reports from various governmental agencies.

RESULTS/CONCLUSIONS

Fexofenadine is devoid of sedative and anticholinergic effects and may offer equivalent or greater efficacy in treating allergic disorders compared with other currently available second-generation H(1)-antihistamines. In addition, fexofenadine may offer cost savings over other selected H(1)-antihistamines owing to its recent availability in generic form in the US.

Glucocorticoids inhibit degranulation of mast cells in allergic asthma via nongenomic mechanism

BACKGROUND

Glucocorticoids (GCs) are the most potent anti-inflammatory agents available for allergic diseases including asthma, which are routinely believed to need several hours to take effect through regulating gene expression. Our previous report had shown that GCs could inhibit allergic asthma within 10 min, which the classical mechanism could not explain.

OBJECTIVE

To confirm the existence and verify the sites of GCs' rapid action, we investigated nongenomic effects of GCs on degranulation of mast cells in allergic asthma.

METHODS

The GCs' rapid action on airway mast cells deregulations was evaluated in the allergic asthma model of guinea pigs by the computer-assisted morphometry. Using whole-cell patch clamp and fluorometric assay, we examined GCs' nongenomic effect on IgE-mediated exocytosis and histamine release of rat basophilic leukaemia-2H3 mast cells. Employing the flash photolysis technique, we studied the role of Ca(2+) signal in the GCs' nongenomic effect.

RESULTS

Inhaled GCs significantly inhibited airway mast cells degranulation in the allergic asthma model of guinea pigs within 10 min. In vitro, GCs could rapidly inhibit IgE-mediated exocytosis and histamine release of mast cells, and neither GC nuclear receptor antagonist nor protein synthesis inhibitor could block the rapid action. We further demonstrated that GCs' nongenomic effect was not through direct action on secretory machinery, but was mediated by a reduction in the [Ca(2+)](i) elevation.

CONCLUSIONS

The study suggested for the first time that nongenomic pathway was involved in GCs' rapid inhibition on allergic asthma, and raised the possibility of new therapeutic strategies for allergic diseases including asthma.

Tip60 functions as a potential corepressor of KLF4 in regulation of HDC promoter activity

KLF4 is a transcription factor that is highly expressed in the gastrointestinal tract. Previously we have demonstrated that KLF4 represses HDC promoter activity in a gastric cell line through both an upstream Sp1 binding GC box and downstream gastrin responsive elements. However, the mechanism by which KLF4 inhibits HDC promoter is not well defined. In the current study, by using yeast two-hybrid screening, Tip60 was identified as a KLF4 interacting protein. Further coimmunoprecipitation and functional reporter assays support the interaction between these two proteins. In addition, Tip60 and HDAC7, previously shown to interact with each other and repress transcription, inhibited HDC promoter activity in a dose-dependent fashion. Consistently, knock down of Tip60 or HDAC7 gene expression by specific shRNA increased endogenous HDC mRNA level. Co-immunoprecipitation assays showed that HDAC7 was pulled down by KLF4 and Tip60, suggesting that these three proteins form a repressive complex. Further chromatin immuno-precipitation indicated that all three proteins associated with HDC promoter. Two-hour gastrin treatment, known to activate HDC gene expression, significantly decreased the association of KLF4, Tip60 and HDAC7 with HDC promoter, suggesting that gastrin activates HDC gene expression at least partly by decreasing the formation of KLF4/Tip60/HDAC7 repressive complexes at the HDC promoter.

Inhibition of IgE-mediated phosphorylation of FcεRIγ protein by antiallergic drugs in rat basophilic leukemia (RBL-2H3) cells: A novel action of antiallergic drugs

We examined the effect of antiallergic drugs, azelastine and epinastine, on the expression of FcepsilonRIalpha, beta, and gamma chains and phosphorylation of the gamma chains in rat basophilic leukemia (RBL-2H3) cells. The cells were cultured for 24 h with IgE treatment in the presence of azelastine or epinastine at the concentration of 10(-5) M. The FcepsilonRIalpha mRNA expression was determined by northern blot analysis. The protein level of FcepsilonRI expressed on the plasma membrane was examined following IgE treatment by immunoprecipitation with anti-IgE light chain, followed by western blot analysis with anti-gamma chain of FcR. Azelastine and epinastine had no effect on the FcepsilonRIalpha, beta and gamma mRNA levels. Although the amount of gamma chain assembled into IgE-bound FcepsilonRI was not changed by treatment with azelastine nor epinastine, phosphorylation levels of gamma chains of IgE-bound FcepsilonRI were inhibited by azelastine. The inhibitory effect of azelastine on the IgE-mediated expression of FcepsilonRIgamma protein is not due to their inhibition of mRNA and protein expression, but due to abrogating phosphorylation of the gamma chains, which is important for initiation of FcepsilonRI signaling cascade elicited by IgE interaction.

Yin yang 1 (YY1) represses histidine decarboxylase gene expression with SREBP-1a in part through an upstream Sp1 site

Histidine decarboxylase (HDC) is the enzyme that converts histidine to histamine, a bioamine that plays an important role in many physiological aspects including allergic responses, inflammation, neurotransmission, and gastric acid secretion. In previous studies, we demonstrated that Kruppel-like factor 4 represses HDC promoter activity in a gastric cell line through both an upstream Sp1-binding GC box (GGGCGG sequence) and downstream gastrin-responsive elements. In the current study, Yin Yang 1 (YY1), a pleiotropic transcriptional factor, was also shown in cotransfection assays to repress HDC promoter activity through the upstream GC box. DNA affinity purification assay demonstrated that YY1 was pulled down specifically by the upstream GC box. In addition, sterol-responsive element-binding protein 1a (SREBP-1a), a transcriptional factor that binds YY1, represses the HDC promoter. Interestingly, deletion analysis and cotransfection assays indicated that mutation of the upstream GC box or truncation of downstream gastrin-responsive elements in the HDC promoter disrupted the inhibitory effect of YY1 and SREBP-1a in an identical fashion. Furthermore, quantitative real-time PCR analysis indicated that gastrin treatment downregulated SREBP-1a gene expression and reduced the DNA binding activity of SREBP in EMSAs. Taken together, these results suggest that YY1 and SREBP-1a form a complex to inhibit HDC gene expression through both the upstream GC box and downstream gastrin-responsive elements and gastrin-induced activation of HDC gene expression is mediated at least partly through downregulation of transcriptional repressors such as SREBPs.

Desloratadine reduces systemic allergic inflammation following nasal provocation in allergic rhinitis and asthma patients

BACKGROUND

Preclinical studies have demonstrated that some second-generation antihistamines have anti-inflammatory effects. It is not known whether these effects are also demonstrable in vivo. In this study we investigated the effect of treatment with desloratadine (DL) on systemic inflammation and on nasal and bronchial mucosal inflammation after nasal allergen provocation (NP) in subjects with grass-pollen-allergic rhinitis and asthma.

METHODS

Twenty-six subjects with grass-pollen-allergic rhinitis and asthma were randomly allocated to 8 days of treatment with DL (n = 13) or placebo (n = 13) outside the grass pollen season. On day 7 they underwent nasal provocation with grass pollen allergen. Nasal and bronchial biopsies were taken for immunohistochemical evaluation, and blood samples were analysed. Rhinitis and asthma symptoms, peak nasal inspiratory flow and peak expiratory flow, were also measured at specified times.

RESULTS

The number of circulating eosinophils decreased during DL treatment, and there was a reduced increase in circulating eosinophils after NP in these subjects. There was also a significant reduction in early bronchial clinical response. There was no significant lessening in the severity of the nasal symptoms. Nasal and bronchial mucosal inflammation parameters did not alter under DL treatment.

CONCLUSION

These data suggest that treatment with DL reduces systemic eosinophilia and prevents the increase in circulating eosinophils after NP. DL also significantly reduces the early bronchial clinical response to NP. However, airway mucosal inflammation is not altered by 1 week of treatment.

Desloratadine partially inhibits the augmented bacterial responses in the sinuses of allergic and infected mice

BACKGROUND

Allergic rhinitis (AR) is considered a major predisposing factor for the development of acute bacterial rhinosinusitis. How AR augments a bacterial infection is unknown.

OBJECTIVE

Our purpose in this study was to test whether an H1 receptor antagonist, desloratadine, could reduce the augmented effect of an ongoing allergic reaction on acute bacterial rhinosinusitis.

METHODS

Three groups of infected and ovalbumin (OVA)-sensitized mice were studied: (1) infected and allergic mice treated with desloratadine, (2) infected and allergic mice treated with placebo, and (3) infected mice. A fourth group of uninfected, non-sensitized mice served as a control for the cellular changes. BALB/c mice were sensitized by two intraperitoneal injections of OVA given 8 days apart. One day after the second injection, the mice were nasally exposed daily to 6% OVA (the groups treated with desloratadine or placebo) or phosphate-buffered saline (PBS) (the infection-only group) for 5 days. After the second OVA exposure, the mice were intranasally inoculated with Streptococcus pneumoniae. Desloratadine or placebo was given daily throughout the OVA exposure period. Nasal allergic symptoms were observed by counting of nasal rubbing and sneezing for 10 min after OVA or PBS nasal challenge. On day 5 post-infection, nasal lavage culture was done, and the inflammatory cells in the sinuses were evaluated by flow cytometry.

RESULTS

Mice that were made allergic, infected, and treated with placebo showed more organisms and phagocytes than did only infect mice. They also manifested allergic nasal symptoms and eosinophil influx into the sinuses. Desloratadine treatment during allergen exposure reduced allergic symptoms and reduced sinonasal infection (P<0.05). There tended to be less myeloid cell and neutrophil influx (P=0.09 both), but not eosinophil influx (P=0.85) compared with that in the placebo-treated group.

CONCLUSION

Desloratadine treatment during nasal challenge inhibited allergic symptoms and reduced sinonasal infection, suggesting that histamine via an H1 receptor plays a role in the augmented infection in mice with an ongoing allergic reaction.

Anti-inflammatory properties of desloratadine

BACKGROUND

Allergic rhinitis (AR) is associated with robust infiltration of immune cells and mediators that may contribute to clinical manifestations of the disease.

OBJECTIVE

To review the complex immune effector mechanisms involved in the allergic response and discuss their effects on the pathophysiological and clinical manifestations of AR. Desloratadine, a novel antihistamine, was used as a probe with the goal of attaining a better understanding of the inflammatory processes underlying the allergic response.

METHODS

Data were obtained from abstracts and peer-reviewed journals. The pathophysiology of the allergic response has been extensively studied. This paper presents only data from studies that used desloratadine at physiologically relevant concentrations.

RESULTS

Key mediators involved in the allergic response and in pathophysiological and clinical manifestations of the immune response were reviewed. Desloratadine was used as a probe to further elucidate the mechanisms involved during an allergic response.

CONCLUSIONS

Some have proposed a link between the pathophysiology of AR and the clinical manifestation of symptoms. Desloratadine, a new-generation antihistamine, has demonstrated anti-inflammatory effects in vitro; indeed, desloratadine is capable of intervening at various points in the immune cascade. Although in vitro results do not necessarily correlate with clinical efficacy, the anti-inflammatory properties of desloratadine may contribute to its efficacy in patients with AR, allergy-induced asthma, and other related allergic conditions. Antihistamines that modulate in the immune system at various stages may optimize treatment of allergic disease.

Kruppel-like factor 4 (KLF4) represses histidine decarboxylase gene expression through an upstream Sp1 site and downstream gastrin responsive elements

Histidine decarboxylase (HDC) is the enzyme that catalyzes the conversion of histidine to histamine, a bioamine that plays an important role in allergic responses, inflammation, neurotransmission, and gastric acid secretion. Previously, we demonstrated that gastrin activates HDC promoter activity in a gastric cancer (AGS-E) cell line through three overlapping downstream promoter elements. In the current study, we used the yeast one-hybrid strategy to identify nuclear factors that bind to these three elements. Among eight positives from the one-hybrid screen, we identified Kruppel-like factor 4 (KLF4) (previously known as gut-enriched Kruppel-like factor (GKLF)) as one factor that binds to the gastrin responsive elements in the HDC promoter. Electrophoretic mobility shift assays confirmed that KLF4 is able to bind all three gastrin responsive elements. In addition, transient cotransfection experiments showed that overexpression of KLF4 dose dependently and specifically inhibited HDC promoter activity. Regulation of HDC transcription by KLF4 was confirmed by changes in the endogenous HDC messenger RNA by KLF4 small interfering RNA and KLF4 overexpression. We further showed that KLF4 inhibits HDC promoter activity by competing with Sp1 at the upstream GC box and also independently by binding the three downstream gastrin responsive elements. Taken together, these results indicate that KLF4 can act to repress HDC gene expression by Sp1-dependent and -independent mechanisms.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

Influence of Histamine in a Liver Injury Model Induced by Propionibacterium acnes and Lipopolysaccharide

In normal mice, plasma histamine levels were 29.4+/-10.1 pmol/ml. When 0.1 microg of lipopolysaccharide (LPS) was intravenously injected into Propionibacterium acnes (P. acnes)-primed ICR mice, histamine levels increased remarkably to 61.2+/-15.9 pmol/ml (p<0.001). An increase was also observed in liver tissues. Oral administration of histidine at 200 mg/kg once daily for 5 d before intravenous LPS injection increased the plasma alanine aminotransferase (ALT) activity to 2936.5+/-356.3 IU/l, a significant change compared with the controls (2244.8+/-425.5 IU/l, p<0.05). The 24 h survival rate after LPS injection was 72.7% in the mice treated with 50 mg/kg of ranitidine, in contrast with 50% in the control group although the treatment did not significantly decrease the plasma ALT activity. On the other hand, 50 mg/kg of pyrilamine significantly reduced plasma ALT activity (p<0.001). The results suggested that histamine levels are related to hepatic damage in the P. acnes plus LPS induction of liver injury.