Zinc chelators inhibit eotaxin, RANTES, and MCP-1 production in stimulated human airway epithelium and fibroblasts

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Antioxidant Intake and Biomarkers of Asthma in Relation to Smoking Status-A Review

Asthma is considered a chronic inflammatory disorder associated with airway hyperresponsiveness (AHR). Increased oxidative stress (OS) is a clinical feature of asthma, which promotes the inflammatory responses in bronchial/airway epithelial cells. Smokers and nonsmokers with asthma have been shown to have increases in several OS and inflammatory biomarkers. However, studies suggest significant differences in OS and inflammation biomarkers between smokers and nonsmokers. A few studies suggest associations between antioxidant intake from diet/supplements and asthma in patients with different smoking status. Evidence is lacking on the protective role of antioxidant vitamin and/or mineral consumption against asthma by smoking status with respect to inflammation and OS biomarkers. Therefore, the aim of this review is to highlight current knowledge regarding the relations between antioxidant intake, asthma, and its associated biomarkers, according to smoking status. This paper can be used to guide future research directions towards the health consequences of antioxidant intake in smoking and nonsmoking asthmatics.

Biased agonism at histamine H1 receptor: Desensitization, internalization and MAPK activation triggered by antihistamines

Histamine H₁ receptor ligands used clinically as antiallergics rank among the most widely prescribed and over-the-counter drugs in the world. They exert the therapeutic actions by blocking the effects of histamine, due to null or negative efficacy towards Gα_q-phospholipase C (PLC)-inositol triphosphates (IP₃)-Ca²⁺ and nuclear factor-kappa B cascades. However, there is no information regarding their ability to modulate other receptor responses. The aim of the present study was to investigate whether histamine H₁ receptor ligands could display positive efficacy concerning receptor desensitization, internalization, signaling through Gα_q independent pathways or even transcriptional regulation of proinflammatory genes. While diphenhydramine, triprolidine and chlorpheniramine activate ERK1/2 (extracellular signal-regulated kinase 1/2) pathway in A549 cells, pre-treatment with chlorpheniramine or triprolidine completely desensitize histamine H₁ receptor mediated Ca²⁺ response, and both diphenhydramine and triprolidine lead to receptor internalization. Unlike histamine, histamine H₁ receptor desensitization and internalization induced by antihistamines prove to be independent of G protein-coupled receptor kinase 2 (GRK2) phosphorylation. Also, unlike the reference agonist, the recovery of the number of cell-surface histamine H₁ receptors is a consequence of de novo synthesis. On the other hand, all of the ligands lack efficacy regarding cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) mRNA regulation. However, a prolonged exposure with each of the antihistamines impaires the increase in COX-2 and IL-8 mRNA levels induced by histamine, even after ligand removal. Altogether, these findings demonstrate the biased nature of histamine H₁ receptor ligands contributing to a more accurate classification, and providing evidence for a more rational and safe use of them.

Role of Zinc Signaling in the Regulation of Mast Cell-, Basophil-, and T Cell-Mediated Allergic Responses

Zinc is essential for maintaining normal structure and physiological function of cells. Its deficiency causes growth retardation, immunodeficiency, and neuronal degeneration. Zinc homeostasis is tightly regulated by zinc transporters and metallothioneins that control zinc concentration and its distribution in individual cells and contributes to zinc signaling. The intracellular zinc signaling regulates immune reactions. Although many molecules involved in these processes have zinc-binding motifs, the molecular mechanisms and the role of zinc in immune responses have not been elucidated. We and others have demonstrated that zinc signaling plays diverse and specific roles in vivo and in vitro in studies using knockout mice lacking zinc transporter function and metallothionein function. In this review, we discuss the impact of zinc signaling focusing particularly on mast cell-, basophil-, and T cell-mediated inflammatory and allergic responses. We also describe zinc signaling dysregulation as a leading health problem in inflammatory disease and allergy.

Association of CD14 -159 (-260C/T) polymorphism and asthma risk: an updated genetic meta-analysis study

BACKGROUND

It has been reported that the cluster of differentiation 14 (CD14) gene -159C/T variant may be associated with asthma risk. However, some studies yielded conflicting results. Therefore, a comprehensive meta-analysis was designed to assess the precise association.

METHODS

A systematic search in PubMed, Embase (Ovid), China National Knowledge Internet (CNKI), and Wan fang databases was conducted up to August 15, 2015. Odds ratio (OR) and 95% confidence interval (CI) were used to pool the effect size. We used I to assess heterogeneity, and a funnel plot and Egger test to assess publication bias.

RESULTS

In total, 34 studies involving 15,641 subjects were included in this meta-analysis. There was a statistically significant association between CD14 -159C/T polymorphism and asthma risk observed in dominant model (TT+TC vs CC: OR = 0.86, 95% CI = 0.77-0.97, P = 0.012) and codominant model (TC vs CC: OR = 0.88, 95% CI = 0.78-0.99, P = 0.035) in adults. However, there may be no significant association between CD14 159C/T and atopic and nonatopic asthma risk.

CONCLUSION

In summary, the overall results suggested that the CD14 -159C/T variant may decrease the risk of asthma susceptibility in adults. However, no significant association between CD14 159C/T and atopic and nonatopic asthma susceptibility was identified. More studies with larger sample size are needed to validate the findings from this study.

Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus

Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N′,N′-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin.

Effects of histamine H1 receptor signaling on glucocorticoid receptor activity. Role of canonical and non-canonical pathways

Histamine H1 receptor (H1R) antagonists and glucocorticoid receptor (GR) agonists are used to treat inflammatory conditions such as allergic rhinitis, atopic dermatitis and asthma. Consistent with the high morbidity levels of such inflammatory conditions, these receptors are the targets of a vast number of approved drugs, and in many situations their ligands are co-administered. However, this drug association has no clear rationale and has arisen from clinical practice. We hypothesized that H1R signaling could affect GR-mediated activity, impacting on its transcriptional outcome. Indeed, our results show a dual regulation of GR activity by the H1R: a potentiation mediated by G-protein βγ subunits and a parallel inhibitory effect mediated by Gαq-PLC pathway. Activation of the H1R by its full agonists resulted in a composite potentiating effect. Intriguingly, inactivation of the Gαq-PLC pathway by H1R inverse agonists resulted also in a potentiation of GR activity. Moreover, histamine and clinically relevant antihistamines synergized with the GR agonist dexamethasone to induce gene transactivation and transrepression in a gene-specific manner. Our work provides a delineation of molecular mechanisms underlying the widespread clinical association of antihistamines and GR agonists, which may contribute to future dosage optimization and reduction of well-described side effects associated with glucocorticoid administration.

Association between RANTES gene polymorphisms and asthma: a meta-analysis

BACKGROUND

A few recent studies have suggested that regulated on activation, normal T cell expressed and secreted (RANTES) polymorphisms (-403 G/A, -28C/G) are associated with asthma. However, there still existed studies which did not confirm these correlations.

OBJECTIVE

The objective of this study was to evaluate the relationship of RANTES and asthma using a meta-analysis.

METHODS

Pubmed, Embase, and Cochrane library databases were systemically searched. Data were extracted by two independent reviewers and pooled odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Eighteen studies were enrolled, including a total of 2558 cases and 2630 controls of -403 G/A, as well as 3311 cases and 4031 controls of -28C/G in this meta-analysis. The overall ORs and 95% CIs of -403 G/A were 1.19, 1.06-1.33 (P<0.001) and 1.25, 1.03-1.51 (P = 0.933) in dominant and recessive models, respectively. The overall ORs and 95% CIs of -28G were 1.23, 1.09-1.39 (P = 0.221) and 1.76, 1.32-2.34 (P = 0.356) in dominant and recessive models, respectively. No publication bias among studies was showed.

CONCLUSIONS

This meta-analysis showed that RANTES -403 G/A polymorphism was a risk factor for asthma, while -28C/G polymorphism were not associated with asthma.

Comparative physicochemical and biological characterization of NIST Interim Reference Material PM2.5 and SRM 1648 in human A549 and mouse RAW264.7 cells

The epidemiological association between exposure to fine particulate matter (PM2.5) and adverse health effects is well-known. Here we report the size distribution, metals content, endotoxin content, and biological activity of National Institute of Standards and Technology (NIST) Interim Reference Material (RM) PM2.5. Biological activity was measured in vitro by effects on cell viability and the release of four inflammatory immune mediators, from human A549 alveolar epithelial cells or murine RAW264.7 monocytes. A dose range covering three orders of magnitude (1-1000μg/mL) was tested, and biological activity was compared to an existing Standard Reference Material (SRM) for urban PM (NIST SRM 1648). Robust release of IL-8 and MCP-1 from A549 cells was observed in response to IRM PM2.5 exposures. Significant TNF-α, but not IL-6, secretion from RAW264.7 cells was observed in response to both IRM PM2.5 and SRM 1648 particle types. Cytokine or chemokine release at high doses often occurred in the presence of cytotoxicity, likely as a result of externalization of preformed mediator. Our results are consistent with a local cytotoxic and pro-inflammatory mechanism of response to exposure to inhaled ambient PM2.5 and reinforce the continued relevance of in vitro assays for mechanistic research in PM toxicology. Our study furthers the goal of developing reference samples of environmentally relevant particulate matter of various sizes that can be used for hypothesis testing by multiple investigators.

Zinc suppressed the airway inflammation in asthmatic rats: effects of zinc on generation of eotaxin, MCP-1, IL-8, IL-4, and IFN-γ

Airway epithelium is rich in labile zinc (Zn), which may have an important protective role in the airway epithelium. The aim of this study is to investigate the effects of Zn on the airway inflammation and the generation of eotaxin, monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), interleukin-4 (IL-4), and interferon-γ (IFN-γ) in rat models of ovalbumin (OVA)-induced allergic airway inflammation. For this purpose, animal model of asthma was established by OVA challenge and zinc-deficient and zinc-supplemented diets were given. Thirty-two Sprague-Dawley rats were divided into four groups: zinc-deficient diet with OVA treatment group, zinc-supplemented diet with OVA treatment group, zinc-normal diet with OVA treatment group, and zinc-normal diet with saline treatment group. Twenty-four hours after asthma was induced, lung histomorphological changes, cells in bronchoalveolar lavage fluid (BALF), contents of eotaxin, MCP-1, and IL-8 in BALF, and the expression of IFN-γ and IL-4 mRNAs were observed. Compared with the group of zinc-normal diet with OVA challenge rats, the group of zinc-deficient rats had higher numbers of eosinophils, neutrophils, and monocytes in BALF, as well as higher contents of eotaxin and MCP-1 in BALF and lower expression of lung IFN-γ mRNA. Conversely, Zn supplementation would decrease the numbers of eosinophils, neutrophils, and monocytes in BALF; suppress eotaxin and MCP-1 protein secretion; and increase lung IFN-γ mRNA expression. No significant difference was observed in IL-8 and IL-4 among OVA-challenged rats with different zinc diets. These studies suggested that Zn may be an important anti-inflammatory mediator of airway inflammation.

Severe dermatitis with loss of epidermal Langerhans cells in human and mouse zinc deficiency

Zinc deficiency can be an inherited disorder, in which case it is known as acrodermatitis enteropathica (AE), or an acquired disorder caused by low dietary intake of zinc. Even though zinc deficiency diminishes cellular and humoral immunity, patients develop immunostimulating skin inflammation. Here, we have demonstrated that despite diminished allergic contact dermatitis in mice fed a zinc-deficient (ZD) diet, irritant contact dermatitis (ICD) in these mice was more severe and prolonged than that in controls. Further, histological examination of ICD lesions in ZD mice revealed subcorneal vacuolization and epidermal pallor, histological features of AE. Consistent with the fact that ATP release from chemically injured keratinocytes serves as a causative mediator of ICD, we found that the severe ICD response in ZD mice was attenuated by local injection of soluble nucleoside triphosphate diphosphohydrolase. In addition, skin tissue from ZD mice with ICD showed increased levels of ATP, as did cultured wild-type keratinocytes treated with chemical irritants and the zinc-chelating reagent TPEN. Interestingly, numbers of epidermal Langerhans cells (LCs), which play a protective role against ATP-mediated inflammatory signals, were decreased in ZD mice as well as samples from ZD patients. These findings suggest that upon exposure to irritants, aberrant ATP release from keratinocytes and impaired LC-dependent hydrolysis of nucleotides may be important in the pathogenesis of AE.

Chemical sensitization and allergotoxicology

Chemical sensitization remains an important environmental and occupational health issue. A wide range of substances have been shown to possess the ability to induce skin sensitization or respiratory sensitization. As a consequence, there is a need to have appropriate methods to identify sensitizing agents. Although a considerable investment has been made in exploring opportunities to develop methods for hazard identification and characterization, there are, as yet, no validated nonanimal methods available. A state of the art of the different in vitro approaches to identify contact and respiratory capacity of chemicals is covered in this chapter.

A zinc chelator TPEN attenuates airway hyperresponsiveness and airway inflammation in mice in vivo

BACKGROUND

Zinc is an essential element required for the cell metabolism, including gene transcription, signal transduction, immunity, and apoptosis. The pathophysiological role of zinc in asthma, however, is not entirely clear. Mast cells have been implicated in atopic asthma, and zinc deprivation has been reported to reduce mast cell activation. Here, we investigate the effects of a zinc chelator, N,N,N',N'-tetrakis (2-pyridyl-methyl) ethylenediamine (TPEN), on asthmatic responses in mouse models of ovalbumin (OVA)-induced airway hyperresponsiveness and allergic airway inflammation.

METHODS

Mice were sensitized with OVA with or without the adjuvant aluminum hydroxide (alum) and subjected to OVA exposure with or without treatment of TPEN. Cell profiles and cytokine levels in bronchoalveolar lavage (BAL) fluids, airway responsiveness to inhaled acetylcholine, and goblet cell hyperplasia after allergen exposure were assessed.

RESULTS

In mice sensitized to OVA without alum, TPEN significantly suppressed airway hyperresponsiveness and eosinophilia in BAL fluids. TPEN also attenuated the upregulation of TNFα, IL-13 and IL-4 in BAL fluids and goblet cell hyperplasia after OVA exposure. By contrast, in mice sensitized to OVA with alum, TPEN suppressed eosinophilia in BAL fluids but not airway hyperresponsiveness and goblet cell hyperplasia.

CONCLUSIONS

In pulmonary allergic inflammation induced in mice immunized with antigen without alum, zinc chelator inhibits airway inflammation and hyperresponsiveness. These findings suggest that zinc may be a therapeutic target of allergic asthma.

Zinc homeostasis and signaling in health and diseases: Zinc signaling

The essential trace element zinc (Zn) is widely required in cellular functions, and abnormal Zn homeostasis causes a variety of health problems that include growth retardation, immunodeficiency, hypogonadism, and neuronal and sensory dysfunctions. Zn homeostasis is regulated through Zn transporters, permeable channels, and metallothioneins. Recent studies highlight Zn's dynamic activity and its role as a signaling mediator. Zn acts as an intracellular signaling molecule, capable of communicating between cells, converting extracellular stimuli to intracellular signals, and controlling intracellular events. We have proposed that intracellular Zn signaling falls into two classes, early and late Zn signaling. This review addresses recent findings regarding Zn signaling and its role in physiological processes and pathogenesis.

The crucial role of GATA-1 in CCR3 gene transcription: modulated balance by multiple GATA elements in the CCR3 regulatory region

GATA-1, a zinc finger-containing transcription factor, regulates not only the differentiation of eosinophils but also the expression of many eosinophil-specific genes. In the current study, we dissected CCR3 gene expression at the molecular level using several cell types that express varying levels of GATA-1 and CCR3. Chromatin immunoprecipitation analysis revealed that GATA-1 preferentially bound to sequences in both exon 1 and its proximal intron 1. A reporter plasmid assay showed that constructs harboring exon 1 and/or intron 1 sequences retained transactivation activity, which was essentially proportional to cellular levels of endogenous GATA-1. Introduction of a dominant-negative GATA-1 or small interfering RNA of GATA-1 resulted in a decrease in transcription activity of the CCR3 reporter. Both point mutation and EMSA analyses demonstrated that although GATA-1 bound to virtually all seven putative GATA elements present in exon 1-intron 1, the first GATA site in exon 1 exhibited the highest binding affinity for GATA-1 and was solely responsible for GATA-1-mediated transactivation. The fourth and fifth GATA sites in exon 1, which were postulated previously to be a canonical double-GATA site for GATA-1-mediated transcription of eosinophil-specific genes, appeared to play an inhibitory role in transactivation, albeit with a high affinity for GATA-1. Furthermore, mutation of the seventh GATA site (present in intron 1) increased transcription, suggesting an inhibitory role. These data suggest that GATA-1 controls CCR3 transcription by interacting dynamically with the multiple GATA sites in the regulatory region of the CCR3 gene.

RANTES gene polymorphisms and asthma risk: A meta-analysis

BACKGROUND AND AIMS

RANTES is a chemokine that assists the recruitment of inflammatory cells including eosinophils. Previous studies revealed that polymorphisms of RANTES were implicated in susceptibility to asthma, but a large number of studies reported apparently conflicting results. We performed a meta-analysis to investigate the association of these polymorphisms and asthma risk.

METHODS

Literature-based meta-analysis was supplemented by tabular data from investigation of all relevant studies regarding all polymorphisms of RANTES available before November 30, 2009, with investigation on potential sources of heterogeneity.

RESULTS

Ten case/control studies were included in the meta-analysis, involving a total of 1706 cases and 1685 controls. In a combined analysis, no significant associations with asthma risk were found on these two polymorphisms (-403G/A and -28C/G) without any publication bias. For the -403G/A polymorphism, in subgroup analysis by ethnicity, no significant associations were found in Asians, Europeans or African-Americans; in subgroup analysis by age, no significant associations were found in adults or children. In subgroup analysis by atopic status, the -403G/A polymorphism was significantly associated with asthma risk in atopic asthma (dominant model [OR = 1.38, 95% CI = 1.09-1.76, p = 0.009; P(het) = 0.10]; A vs. G model [OR = 1.25, 95% CI = 1.04-1.51, p = 0.02; P(het) = 0.11] and AG vs. GG model [OR = 1.37, 95% CI = 1.06-1.77, p = 0.02; P(het) = 0.14]).

CONCLUSIONS

This meta-analysis suggested that RANTES gene -403G/A polymorphism would be a risk factor among atopic asthma patients. To further evaluate gene-to-gene and gene-to-environment interactions on RANTES polymorphisms and asthma risk, more studies with thousands of patients are required.

Tumor necrosis factor-alpha in severe corticosteroid-refractory asthma

Tumor necrosis factor (TNF)-alpha is a proinflammatory cytokine. Blocking TNF-alpha has been demonstrated to be effective in various diseases, including both rheumatoid and psoriatic arthritis. There is evidence to show that levels of TNF-alpha are elevated in patients with severe asthma. TNF-alpha is involved in the initiation and perpetuation of the inflammatory process, epithelial damage and remodeling, and mucin hypersecretion. Furthermore, TNF-alpha polymorphism has also been reported in the asthmatic population. Based on the necessity for alternative treatments for asthmatics with severe disease and those who are particularly resistant to conventional asthma therapy, it has been shown that molecules targeted at blocking the effects of TNF-alpha probably constitute a considerable advance in the management of these difficult patients. This review focuses on the evidence of TNF-alpha axis upregulation in severe corticosteroid-refractory asthma, as well as the role of TNF-alpha inhibition and the adverse effects of treatment.

TNF-alpha inhibitors in asthma and COPD: we must not throw the baby out with the bath water

Tumor necrosis factor (TNF)-alpha, a pleiotropic cytokine that exerts a variety of effects, such as growth promotion, growth inhibition, angiogenesis, cytotoxicity, inflammation, and immunomodulation, has been implicated in several inflammatory conditions. It plays a significant role in many inflammatory diseases of lungs. Given that there is significant literature supporting the pathobiologic role of TNF-alpha in asthma, mainly in severe refractory asthma, and COPD, TNF-alpha inhibitors (infliximab, golimumab and etanercept) are now regarded as the potential new medications in asthma and COPD management. The studies reported in literature indicate that TNF-alpha inhibitors are effective in a relatively small subgroup of patients with severe asthma, possibly defined by an increased TNF axis, but they seem to be ineffective in COPD, although an observational study demonstrated that TNF-alpha inhibitors were associated with a reduction in the rate of COPD hospitalisation among patients with COPD receiving these agents to treat their rheumatoid arthritis. These findings require a smart approach because there is still good reason to target TNF-alpha, perhaps in a more carefully selected patient group. TNF-alpha treatment should, therefore, not be thrown out, or abandoned. Indeed, since severe asthma and COPD are heterogeneous diseases that have characteristics that occur with different phenotypes that remained poorly characterized and little known about the underlying pathobiology contributing to them, it is likely that definition of these phenotypes and choice of the right outcome measure will allow us to understand which kind of patients can benefit from TNF-alpha inhibitors.

The effects of anti-asthma drugs on the phagocytic clearance of apoptotic eosinophils by A549 cells

BACKGROUND

Phagocytic clearance of apoptotic eosinophils plays an important role in the successful resolution of asthmatic inflammation. To our knowledge, there is limited information available on the effects of anti-asthma drugs on the ingestion of apoptotic eosinophils by bronchial epithelial cells.

AIMS

To evaluate the effects of dexamethasone, aminophylline and terbutaline on the ingestion of apoptotic eosinophils by A549 cells.

METHODS

Eosinophils were purified by CD15 and CD16-dependent immunomagnetic selection from peripheral blood of five normal donors. The capacity of phagocytosis of apoptotic eosinophils by A549 cells were assessed under the microscope. IL-6 and IL-8 released from A549 cells to the culture supernatants were measured by RIA.

RESULTS

Dexamethasone enhanced the phagocytic capacity of A549 cells and inhibited the production of IL-6 and IL-8 from A549 cells stimulated by LPS. Interestingly, aminophylline and terbutaline could not only down-regulate the ingestion of apoptotic eosinophils by A549 cells in a time- and dose-dependent manner, but also decrease IL-6 and IL-8 secretion by A549 cells induced by LPS.

CONCLUSIONS

The present study showed that all of the investigated anti-asthmatic drugs including dexamethasone, aminophylline and terbutaline play an anti-inflammatory effect by decreasing the release of IL-6 and IL-8 induced by LPS. On the other hand, they may have a different effect on the phagocytosis of apoptotic eosinophils by A549 cells, i.e., dexamethasone promotes the uptake of apoptotic eosinophils while aminophylline and terbutaline inhibit the ingestion of apoptotic eosinophils. These results revealed a novel aspect of dexamethasone, aminophylline and terbutaline in the treatment of asthma.

Cell types involved in allergic asthma and their use in in vitro models to assess respiratory sensitization

This review first describes the mechanism and cell types involved in allergic asthma, which is a complex clinical disease characterized by airway obstruction, airway inflammation and airway hyperresponsiveness to a variety of stimuli. The development of allergic asthma exists of three phases, namely the induction phase, the early-phase asthmatic reaction (EAR) and the late-phase asthmatic reaction (LAR). In the induction phase, antigen-presenting cells play a major role. Most important cells in the EAR are mast cells, and during the LAR, various cell types, such as eosinophils, neutrophils, T cells, macrophages, dendritic cells (DCs), and cells that endow structure are involved. In occupational asthma, this immunological mechanism is involved in 90% of the cases. The second part of this review gives an overview of in vitro models to assess the hazardous potential of high- and low-molecular weight chemicals on the respiratory system. In order to develop a good in vitro model for respiratory allergy, the choice of appropriate cell types is important. Epithelial cells, macrophages and DCs are currently the most used models in this field of research.

Effect of zinc supplementation on plasma IL-6 and MCP-1 production and NK cell function in healthy elderly: interactive influence of +647 MT1a and -174 IL-6 polymorphic alleles

Pro-inflammatory cytokine response and NK activity are controlled by the availability of zinc ion, whose intra-cellular transport is regulated by metallothioneins. In order to closely examine the importance of circulating zinc in the modulation of immune response during ageing, in the balance of Th2/Th1 equilibrium and finally in the reversibility of systemic low grade inflammation, we evaluated the changes occurring in plasma IL-6 and MCP-1 concentrations and NK lytic activity in a healthy low grade inflamed elderly population, following zinc-aspartate supplementation. In addition, we aimed to highlight the potential interaction among circulating zinc increments, changes in immunological parameters and +647 MT1a and -174 IL-6 polymorphic alleles. Thirty-nine healthy individuals (60-83 years) from the ZINCAGE cohort (previously typed for +647 MT1a and -174 IL-6 polymorphisms) were supplied with zinc-aspartate. Blood samples collected before and after supplementation underwent basal laboratory determinations (circulating zinc, albumin and C-reactive protein) and immunological studies (plasma IL-6 and MCP-1 and NK lytic activity). Zinc supplementation in subjects with low or borderline-normal circulating zinc increased the concentration of this ion and modulated plasmatic IL-6 and MCP-1 as well as NK lytic activity. An interactive effect of polymorphic alleles of MT1a and IL-6 genes on zinc, IL-6, MCP-1 and NK activity was evidenced following supplementation, indicating the genetic background as one of the determinants for identifying groups of subjects that can take advantage of therapeutic intervention.

Suppression of cytokine response by GATA inhibitor K-7174 via unfolded protein response

K-7174, a GATA-specific inhibitor, is a putative anti-inflammatory agent that attenuates effects of inflammatory cytokines in certain cell types. However, molecular mechanisms involved have not been elucidated. We found that, in glomerular podocytes, induction of monocyte chemoattractant protein 1 (MCP-1) and inducible nitric oxide synthase (iNOS) by TNF-alpha was abrogated by K-7174. It was correlated with unexpected induction of unfolded protein response (UPR) evidenced by: (1) induction of endogenous indicators 78 kDa glucose-regulated protein and CCAAT/enhancer-binding protein-homologous protein, and (2) suppression of an exogenous indicator, endoplasmic reticulum stress-repressive alkaline phosphatase. In podocytes, induction of UPR by either tunicamycin, thapsigargin, A23187 or AB5 subtilase cytotoxin completely reproduced the suppressive effect of K-7174. Furthermore, K-7174-elicited UPR abrogated induction of MCP-1 and iNOS not only by TNF-alpha but also by medium conditioned by activated macrophages. These results suggested a novel, UPR-dependent mechanism underlying the anti-inflammatory potential of K-7174.

Transcriptome profiling of the small intestinal epithelium in germfree versus conventional piglets

BACKGROUND

To gain insight into host-microbe interactions in a piglet model, a functional genomics approach was used to address the working hypothesis that transcriptionally regulated genes associated with promoting epithelial barrier function are activated as a defensive response to the intestinal microbiota. Cesarean-derived germfree (GF) newborn piglets were colonized with adult swine feces, and villus and crypt epithelial cell transcriptomes from colonized and GF neonatal piglets were compared using laser-capture microdissection and high-density porcine oligonucleotide microarray technology.

RESULTS

Consistent with our hypothesis, resident microbiota induced the expression of genes contributing to intestinal epithelial cell turnover, mucus biosynthesis, and priming of the immune system. Furthermore, differential expression of genes associated with antigen presentation (pan SLA class I, B2M, TAP1 and TAPBP) demonstrated that microbiota induced immune responses using a distinct regulatory mechanism common for these genes. Specifically, gene network analysis revealed that microbial colonization activated both type I (IFNAR) and type II (IFNGR) interferon receptor mediated signaling cascades leading to enhanced expression of signal transducer and activator of transcription 1 (STAT1), STAT2 and IFN regulatory factor 7 (IRF7) transcription factors and the induction of IFN-inducible genes as a reflection of intestinal epithelial inflammation. In addition, activated RNA expression of NF-kappa-B inhibitor alpha (NFkappaBIA; a.k.a I-kappa-B-alpha, IKBalpha) and toll interacting protein (TOLLIP), both inhibitors of inflammation, along with downregulated expression of the immunoregulatory transcription factor GATA binding protein-1 (GATA1) is consistent with the maintenance of intestinal homeostasis.

CONCLUSION

This study supports the concept that the intestinal epithelium has evolved to maintain a physiological state of inflammation with respect to continuous microbial exposure, which serves to sustain a tight intestinal barrier while preventing overt inflammatory responses that would compromise barrier function.

A new model of cystic fibrosis pathology: Lack of transport of glutathione and its thiocyanate conjugates

Many of the symptoms of cystic fibrosis are not explained by the current disease mechanisms. Therefore, the authors conducted an extensive literature review and present a new model of cystic fibrosis pathology, which is the culmination of this research. Understanding that the cystic fibrosis transmembrane conductance regulator (CFTR) is responsible for glutathione (GSH) transport, the authors hypothesize that mutations of the CFTR, which create abnormal GSH transport, will lead to aberrations of GSH levels in both the intracellular as well as the extracellular milieu. These alterations in normal cellular GSH levels affect the redox state of the cell, thereby affecting the intracellular stress protein, metallothionein. The authors describe how this disruption of the redox state caused by excess cellular GSH, will naturally prevent the delivery of zinc as a cofactor for various enzymatic processes, and how these disruptions in normal redox may cause alterations in both humoral and cell-mediated immunity. Moreover, the symptom of thick sticky mucus in these patients might be explained through the understanding that oversulfation of mucus is a direct result of elevated cellular GSH and cysteine. The issues of hyperinflammation, altered pH and the imbalance of fatty acids that are typical in cystic fibrosis are addressed-all of which may also be linked to disruptions in GSH homeostasis. Additionally, this new model of cystic fibrosis pathology, clarifies the relationship between the CFTR and the multi-drug resistance proteins, and the lack of cell-mediated immunity by predicting that the substrate of these proteins is a glutathione adduct of thiocyanate. Finally, a new therapeutic strategy by using isothiocyanates to rectify the GSH imbalance and restore the immune system is suggested for the treatment of cystic fibrosis patients.

DMPS reverts morphologic and mitochondrial damage in OK cells exposed to toxic concentrations of HgCl2

Mercuric chloride (HgCl(2)) is a highly toxic compound, which can cause nephrotoxic damage. In the present study effects of HgCl(2) on mitochondria integrity and energy metabolism, as well as antidotal effects of 2,3-dimercaptopropane-1-sulfonate (DMPS) were investigated in the opossum kidney derived cell line (OK). OK cell monolayers were incubated during 0, 1, 3, 6, and 9 h in serum-free culture medium containing 15 microM HgCl(2), either in the absence or in the presence of 60 microM DMPS in a 1:4 ratio. Intracellular ATP content, MTT reduction, and HSP70/HSP90 induction were studied; confocal, transmission electron microscopy, and light microscopy studies were also performed. For confocal analysis, a mitochondrial selective probe (MitoTracker Red CMXH2Ros) was used. Antioxidant activity of DMPS was also studied by the scavenging of the free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) technique. A decrease of ATP content, an impaired ability to reduce tetrazolium, and dramatic changes on cellular and mitochondrial morphology, and energetic levels were found after either 6 or 9 h of HgCl(2) exposure. Increased expression of HSP90 and HSP70 were also seen. When OK cells were co-incubated with HgCl(2) and DMPS, cellular morphology, viability, intracellular ATP, and mitochondrial membrane potential were partially restored; a protective effect on mitochondrial morphology was also seen. DMPS also showed potent antioxidant activity in vitro. Mitochondrial protection could be the cellular mechanism mediated by DMPS in OK cells exposed to a toxic concentration of HgCl(2).

Suppressive activity of epinastine hydrochloride on TARC production from human peripheral blood CD4+ T cells in-vitro

Thymus- and activation-regulated chemokine (TARC) is an important molecule in the development and maintenance of allergic diseases. However, there is little information about the influence of anti-allergic agents on TARC production. The aim of this study is to examine the influence of epinastine hydrochloride, an H1-receptor antagonist, on TARC production from human peripheral blood CD4+ T cells using an in-vitro cell culture technique. CD4+ T cells prepared from healthy subjects were cultured in wells coated with a combination of OKT3 and anti-CD28 monoclonal antibody in the presence or absence of epinastine HCl for 24 h. The cells were also stimulated with interleukin (IL)-4 in a similar manner. Levels of TARC and IL-4 in culture supernatants were examined by ELISA. The addition of epinastine HCl exerted a dose-dependent suppressive effect on the production of both TARC and IL-4 from CD4+ T cells under co-stimulatory molecule stimulation. The minimum concentration of the agent showing a significant suppressive effect on TARC and IL-4 production was 5.0 microM and 2.5 microM, respectively. Epinastine HCl also suppressed the ability of cells to produce TARC in response to IL-4 stimulation, when the agent was added to cell cultures at more than 2.5 microM. It was concluded that this inhibitory action of epinastine HCl may be partially responsible for epinastine's attenuating effect on allergic diseases.

Inhibition of protein tyrosine phosphatase activity mediates epidermal growth factor receptor signaling in human airway epithelial cells exposed to Zn2+

Epidemiological studies have implicated zinc (Zn2+) in the toxicity of ambient particulate matter (PM) inhalation. We previously showed that exposure to metal-laden PM inhibits protein tyrosine phosphatase (PTP) activity in human primary bronchial epithelial cells (HAEC) and leads to Src-dependent activation of EGFR signaling in B82 and A431 cells. In order to elucidate the mechanism of Zn2+-induced EGFR activation in HAEC, we treated HAEC with 500 microM ZnSO4 for 5-20 min and measured the state of activation of EGFR, c-Src and PTPs. Western blots revealed that exposure to Zn2+ results in increased phosphorylation at both trans- and autophosphorylation sites in the EGFR. Zn2+-mediated EGFR phosphorylation did not require ligand binding and was ablated by the EGFR kinase inhibitor PD153035, but not by the Src kinase inhibitor PP2. Src activity was inhibited by Zn2+ treatment of HAEC, consistent with Src-independent EGFR transactivation in HAEC exposed to Zn2+. The rate of exogenous EGFR dephosphorylation in lysates of HAEC exposed to Zn2+ or V4+ was significantly diminished. Moreover, exposure of HAEC to Zn2+ also resulted in a significant impairment of dephosphorylation of endogenous EGFR. These data show that Zn2+-induced activation of EGFR in HAEC involves a loss of PTP activities whose function is to dephosphorylate EGFR in opposition to baseline EGFR kinase activity. These findings also suggest that there are marked cell-type-specific differences in the mechanism of EGFR activation induced by Zn2+ exposure.

Preferential migration of effector CD8+ T cells into the interstitium of the normal lung

The respiratory tract is a primary site of infection and exposure to environmental antigens and an important site of memory T cell localization. We analyzed the migration and retention of naive and activated CD8+ T cells within the noninflamed lungs and quantitated the partitioning of adoptively transferred T cells between the pulmonary vascular and interstitial compartments. Activated but not naive T cells were retained within the lungs for a prolonged period. Effector CD8+ T cells preferentially egressed from the pulmonary vascular compartment into the noninflamed pulmonary interstitium. T cell retention within the lung vasculature was leukocyte function antigen-1 dependent, while the egress of effector T cells from the vascular to the interstitium functions through a pertussis toxin-sensitive (PTX-sensitive) mechanism driven in part by constitutive CC chemokine ligand 5 expression in the lungs. These results document a novel mechanism of adhesion receptor- and pulmonary chemokine-dependent regulation of the migration of activated CD8+ T cells into an important nonlymphoid peripheral site (i.e., the normal/noninflamed lung).

Cytokine-stimulated human lung alveolar epithelial cells release eotaxin-2 (CCL24) and eotaxin-3 (CCL26)

Asthma is a complex inflammatory disease characterized by a prolonged underlying airway inflammation resulting from cytokine-orchestrated signaling between many types of cells, including airway epithelial cells. Trafficking, recruitment, and activation of cells in airway disease are, in part, modulated by the newly discovered CC subfamily of chemokines, eotaxin (CCL11), eotaxin-2 (CCL24) and eotaxin-3 (CCL26), which transduce signals by acting as agonists for the CCR3 receptor. The specific cytokine stimuli that modulate CCL24 and CCL26 release in airway epithelial cells remain poorly defined. Thus, human 549 alveolar type II epithelium-like cells were stimulated singly and with combinations of 1-100 ng/ml tumor necrosis-factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-4, cytokines known to be elevated in the airways of asthmatics. Release of CCL11, CCL24, and CCL26 was quantified by ELISA, and CCR3 receptors monitored by immunocytochemistry and FACS analysis. Results suggest that epithelial cells release CCL11 during the first 24 h of stimulation, in contrast to a significant increase in CCL24 and CCL26 release after 24-48 h of stimulation. Differential release of the eotaxins in response to cytokine combinations was noted. The alveolar type II epithelial cells were found to possess constitutive CCR3 receptors, which increased after proinflammatory cytokine stimulation. The airway epithelium CCR3 receptor/eotaxin ligand signal transduction system may be an important target for development of novel mechanism-based adjunctive therapies designed to interrupt the underlying chronic inflammation in allergic and inflammatory disorders.

Effect of tumor necrosis factor antagonism on allergen-mediated asthmatic airway inflammation

OBJECTIVE

To assess whether tumor necrosis factor (TNF) antagonism can attenuate eosinophilic airway inflammation in patients with mild-to-moderate allergic asthma.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

National Institutes of Health (NIH) Clinical Center.

PATIENTS

Twenty-six patients with mild-to-moderate allergic asthma, receiving only inhaled beta-2-agonists, who demonstrated both an early and late phase response to inhalational allergen challenge.

INTERVENTION

Injection of a soluble TNF receptor (TNFR:Fc, etanercept, Enbrel) or placebo, 25mg subcutaneously, twice weekly for 2 weeks, followed by a bronchoscopic segmental allergen challenge.

MEASUREMENTS

The primary outcome measure was whether TNFR:Fc can access the lung and inhibit TNF bioactivity. Secondary outcome measures included pulmonary eosinophilia, Th2-type cytokines, and airway hyperresponsiveness.

RESULTS

Anti-TNF therapy was associated with transient hemiplegia in one patient, which resulted in suspension of the study. Data from the 21 participants who completed the study were analyzed. Following treatment, patients receiving anti-TNF therapy had significantly increased TNFR2 levels in epithelial lining fluid (ELF) (P<0.001), consistent with delivery of TNFR:Fc to the lung. TNF antagonism did not attenuate pulmonary eosinophilia and was associated with an increase in ELF IL-4 levels (P=0.033) at 24h following segmental allergen challenge. TNF antagonism was not associated with a change in airway hyperresponsiveness to methacholine.

CONCLUSIONS

TNF antagonism may not be effective for preventing allergen-mediated eosinophilic airway inflammation in mild-to-moderate asthmatics. Transient hemiplegia, which may mimic an evolving stroke, may be a potential toxicity of anti-TNF therapy.

Zinc metabolism in airway epithelium and airway inflammation: basic mechanisms and clinical targets. A review

In addition to basic housekeeping roles in metalloenzymes and transcription factors, dietary zinc (Zn) is an important immunoregulatory agent, growth cofactor, and cytoprotectant with anti-oxidant, anti-apoptotic, and anti-inflammatory roles. These properties of Zn are of particular importance in maintaining homeostasis of epithelial tissues which are at the front line of defense. This review is about the role of Zn in airway epithelium (AE). The first part focuses on the cellular biology of Zn, and what is known about its distribution and function in AE. The second part of the review considers evidence for altered Zn metabolism in asthma and other chronic diseases of airway inflammation. Important issues arise from a potential therapeutic perspective as to the optimal ways to monitor circulating and epithelial Zn levels in patients and the most effective means of supplementing these levels.