Role of interleukin-4 and interleukin-13 in synthesis of IgE and expression of CD23 by human B cells

OK-432 Administration Inhibits Murine Allergic Rhinitis at the Induction Phase, through the Macrophage Activation with TLR2 Signaling Pathway

OK-432, a preparation of a low-virulence strain (Su) of Streptococcus pyogenes (Group A) killed by a penicillin and lyophilized, is a stiff inducer of Th1 cytokines, and exerts anti-cancer effects in tumor-bearing mice. OK-432 has been reported to consist of many bacterial components, such as peptidoglycan, M-protein, etc. However, it is yet to be ascertained which bacterial component induces T helper 1 (Th1) responses. For the last decade, Toll-like receptor (TLR) family proteins are well elucidated to play a role in recognizing bacterial components and inducing interleukin (IL)-12 from macrophages. Above all, peptidoglycan seems to be the agonist of TLR2 rather than the obverse. In our present study, the role of TLR2 for the recognition of OK-432 by macrophages and the effects of OK-432 are examined on murine allergic rhinitis model. Interestingly, results show IL-12 production by macrophages derived from TLR2 knock-out (ko) mice was significantly decreased, in comparison with that of macrophages derived from wild-type mice. Moreover, in TLR2 ko mice, no regulatory effect of OK-432 was observed on an allergic rhinitis model. These data indicate that TLR2 signaling is involved in regulating OK-432-induced anti-T helper 2 (Th2) immunity, and may offer a new prophylactic and therapeutic approach using OK-432 to downregulate allergic disorders, such as allergic rhinitis.

Baicalein, wogonin, and Scutellaria baicalensis ethanol extract alleviate ovalbumin-induced allergic airway inflammation and mast cell-mediated anaphylactic shock by regulation of Th1/Th2 imbalance and histamine release

Asthma is characterized by chronic inflammation, goblet cell hyperplasia, the aberrant production of the Th2 cytokines, and eosinophil infiltration into the lungs. In this study, we examined the effects of baicalein, wogonin, and Scutellaria baicalensis ethanol extract on ovalbumin (OVA)-induced asthma by evaluating Th1/Th2 cytokine levels, histopathologic analysis, and compound 48/80-induced systemic anaphylaxis and mast cell activation, focusing on the histamine release from rat peritoneal mast cells. Baicalein, wogonin, and S. baicalensis ethanol extract also decreased the number of inflammatory cells especially eosinophils and downregulated peribronchial and perivascular inflammation in the lungs of mice challenged by OVA. Baicalein, wogonin, and S. baicalensis ethanol extract significantly reduced the levels of tumor necrosis factor α, interleukin (IL)-1β, IL-4, IL-5 and the production of OVA-specific IgE and IgG1, and upregulated the level of interferon-γ and OVA-specific IgG2a. In addition, oral administration of baicalein, wogonin, and S. baicalensis ethanol extract inhibited compound 48/80-induced systemic anaphylaxis and plasma histamine release in mice. Moreover, baicalein, wogonin, and S. baicalensis ethanol extract suppressed compound 48/80-induced mast cell degranulation and histamine release from rat peritoneal mast cells. Conclusively, baicalein and wogonin as major flavonoids of S. baicalensis may have therapeutic potential for allergic asthma through modulation of Th1/Th2 cytokine imbalance and histamine release from mast cells.

Recombinant human deoxyribonuclease therapy improves airway resistance and reduces DNA extracellular traps in a murine acute asthma model

PURPOSE

Asthma is a highly prevalent chronic inflammatory lung disease characterized by airway hyperresponsiveness to allergens, airway edema, and increased mucus secretion. Such mucus can be liquefied by recombinant human deoxyribonuclease (rhDNase), in which efficacy of rhDNase has been well documented in patients with cystic fibrosis, but little studied in asthma. In the present study, we investigated whether rhDNase intranasal administration improved inflammation and pulmonary function in an experimental model of asthma.

METHODS

Mice were sensitized by two subcutaneous injections of ovalbumin (OVA), on days 0 and 7, followed by three intranasal challenges with OVA on days 14, 15, and 16. A control group, replacing OVA by DPBS, was included. On days 15 and 16, after 2 hours of OVA challenge, mice received 1 mg/mL of intranasal rhDNase.

RESULTS

We showed that rhDNase decreased significantly the airway resistance and reduced EETs formation and globet cells hyperplasia.

CONCLUSIONS

Our results suggest that extracellular DNA in mucus play a role in lower airways obstruction in OVA asthma protocol and that the treatment with rhDNase improved lung function and DNA extracellular traps, with no direct cellular anti-inflammatory effects.

Definition of a pool of epitopes that recapitulates the T cell reactivity against major house dust mite allergens

BACKGROUND

Allergens from house dust mites (HDM) are a common cause of asthma. Der p and Der f from Dermatophagoides sp. are strong immunogens in humans. Allergen extracts are used to study T helper (Th2) cell responses to HDM, which are implicated in the development and regulation of allergic disease.

OBJECTIVE

To define an epitope mixture that recapitulates, and might substitute for, HDM extract in terms of detecting and characterizing Th2 cell responses.

METHODS

Peripheral blood mononuclear cells (PBMC) from 52 HDM allergic and 10 non-allergic individuals were stimulated with HDM extracts and assayed with a set of 178 peptides spanning mite allergens group Der p 1, 2, 23 and Der f group 1 and 2 allergens. A pool of the most dominant T cell epitopes identified in the present study and from published literature was assembled and tested for ex vivo T cell responses. Correlation with HDM-specific IgE titres was examined.

RESULTS

Patterns of T cell reactivity to Der p and Der f - derived peptides revealed a large number of epitopes. Clear patterns of immunodominance were apparent, with HDM allergen group 1 and 2 dominant over group 23. Furthermore, within a given antigen, 6-11 epitopes accounted for the vast majority of responses. Based on these results and published data, a comprehensive dust mite pool (DMP) of epitopes was designed and found to allow detection of ex vivo T cell responses. DMP ex vivo reactivity correlated with HDM-specific IgE titres and was similar to that detected with commonly used HDM extracts. Ex vivo DMP stimulation was associated with a predominant Th2 response in allergic donors, and minor reactivity of T cells producing IFNγ, IL17 and IL10.

CONCLUSIONS & CLINICAL RELEVANCE

A detailed map of Der p and Der f antigens defined a pool of epitopes that can be used to detect ex vivo HDM responses.

IL-4 enhances expression and function of surface IgM in CLL cells

Kinase inhibitors targeting the B-cell receptor (BCR) are now prominent in the treatment of chronic lymphocytic leukemia (CLL). We have focused here on interleukin 4 (IL-4), a cytokine that protects normal and malignant B cells from apoptosis and increases surface immunoglobulin M (sIgM) expression on murine splenic B cells. First, we have demonstrated that IL-4 treatment increased sIgM expression in vitro on peripheral blood B cells obtained from healthy individuals. In CLL, IL-4 target genes are overexpressed in cells purified from the lymph nodes of patients compared with cells derived from matched blood and bone marrow samples. As for normal B cells, IL-4 increased sIgM expression on CLL cells in vitro, especially in samples expressing unmutated V-genes. IL-4-induced sIgM expression was associated with increased receptor signalling activity, measured by anti-IgM-induced calcium mobilization, and with increased expression of CD79B messenger RNA and protein, and the "mature" glycoform of sIgM. Importantly, the ability of the BCR-associated kinase inhibitors idelalisib and ibrutinib, approved for treatment of CLL and other B-cell malignancies, to inhibit anti-IgM-induced signalling was reduced following IL-4 pretreatment in samples from the majority of patients. In contrast to stimulatory effects on sIgM, IL-4 decreased CXCR4 and CXCR5 expression; therefore, CLL cells, particularly within the progressive unmutated V-gene subset, may harness the ability of IL-4 to promote BCR signalling and B-cell retention within lymph nodes. Effects of IL-4 were mediated via JAK3/STAT6 and we propose a potential role for JAK inhibitors in combination with BCR kinase inhibitors for the treatment of CLL.

Soshiho-tang water extract inhibits ovalbumin-induced airway inflammation via the regulation of heme oxygenase-1

Background

Soshiho-tang, known as Xio-hai-Hu-Tang in Chinese and Sho-Saiko-to in Japanese, has been widely used as a therapeutic agent. Its pharmacological effects include anti-inflammatory, antioxidant, antihepatic fibrosis, antitumor and immunomodulating activities. However, little is known regarding its effects on allergic asthma. Therefore, the aim of the present study was to investigate whether the Soshiho-tang water extract (SSTW) has antiasthmatic effects on airway inflammation in an ovalbumin (OVA)-induced mouse model.

Methods

BALB/c mice were used as a model of asthma after induction by sensitization and challenge with OVA. We measured change in eosinophils, other inflammatory cells, and T helper 2 (Th2)-type cytokines, such as interleukin (IL)-4, IL-5, IL-13, IL-17, IL-33, and chemokine (eotaxin) in bronchoalveolar lavage fluid (BALF), presence of total and OVA-specific immunoglobulin (Ig)E in plasma, and expression of mucus production and heme oxygenase (HO)-1 protein in lung tissue.

Results

Our results show that SSTW had a suppressive effect on eosinophil influx into BALF and decreased the levels of Th2-type cytokines. Moreover, SSTW exhibited a marked decrease in mucus hypersecretion, total and OVA-specific IgE levels, and significantly induced HO-1 protein expression.

Conclusions

These results suggest that SSTW may be used as a valuable therapeutic agent for treating various inflammatory diseases including allergic asthma.

Immuno-evasive tactics by schistosomes identify an effective allergy preventative

Many chronic inflammatory diseases can be improved by helminth infection, but the mechanisms are poorly understood. Allergy and helminthiasis are both associated with Th2-like immune responses; thus, defining how infection with parasites leads to reduced allergy has been particularly challenging. We sought to better understand this conundrum by evaluating host-parasite interactions involved in Th2 immunity in human schistosomiasis. Immune cells were cultured with schistosomes and the effect on CD23, an IgE receptor associated with resistance in schistosomiasis, was evaluated. Cells treated with schistosomes demonstrated reduced surface CD23 levels with a parallel accumulation of soluble (s) CD23 suggesting this IgE receptor is proteolytically cleaved by the parasite. Consistent with this hypothesis, a schistosome-generated (SG)-sCD23 fragment of 15 kDa was identified. SG-sCD23 inhibited IgE from binding to CD23 and FcεRI, but lacked the ability to bind CD21. These results suggested that schistosomes target IgE-mediated immunity in immuno-evasive tactics. Based on its characteristics, we predicted that SG-sCD23 would function as an efficacious allergy preventative. Treatment of human FcεRI-transgenic mice with recombinant (r) SG-sCD23 reduced the ability of human IgE to induce an acute allergic response in vivo. In addition, an optimized form of rSG-sCD23 with an introduced point mutation at Asp258 (D258E)to stabilize IgE binding had increased efficacy compared to native rSG-sCD23. Schistosome infection may thus inhibit allergic-like protective immune responses by increasing soluble IgE decoy receptors. Allergy treatments based on this naturally occurring phenomenon may be highly effective and have fewer side effects with long-term use.

Sulforaphane inhibits the Th2 immune response in ovalbumin-induced asthma

Sulforaphane (1-isothiocyanato-4-(methylsulfinyl)-butane), belonging to a family of natural compounds that are abundant in broccoli, has received significant therapeutic interest in recent years. However, the molecular basis of its effects remains to be elucidated. In this study, we attempt to determine whether sulforaphane regulates the inflammatory response in an ovalbumin (OVA)-induced murine asthma model. Mice were sensitized with OVA, treated with sulforaphane, and then challenged with OVA. Sulforaphane administration significantly alleviated the OVA-induced airway hyperresponsiveness to inhaled methacholine. Additionally, sulforaphane suppressed the increase in the levels of SOCS-3 and GATA-3 and IL-4 expression in the OVA-challenged mice. Collectively, our results demonstrate that sulforaphane regulates Th2 immune responses. This sutdy provides novel insights into the regulatory role of sulforaphane in allergen-induced Th2 inflammation and airway responses, which indicates its therapeutic potential for asthma and other allergic diseases.

Polyopes affinis alleviates airway inflammation in a murine model of allergic asthma

Marine algae have been utilized in food as well as medicine products for a variety of purposes. The purpose of this study was to determine whether an ethanol extract of Polyopes affinis (P.affinis) can inhibit the pathogenesis of T helper 2 (Th2)-mediated allergen-induced airway inflammation in a murine model of asthma. Mice that were sensitized and challenged with ovalbumin (OVA) evidenced typical asthmatic reactions such as the following: an increase in the number of eosinophils in the bronchoalveolar lavage (BAL) fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways as well as the narrowing of the airway luminal; the development of airway hyperresponsiveness (AHR); the presence of pulmonary Th2 cytokines; and the presence of allergenspecific immunoglobulin E (IgE) in the serum. The successive intraperitoneal administration of P. affinis ethanolic extracts before the last airway OVA-challenge resulted in a significant inhibition of all asthmatic reactions. These data suggest that P. affinis ethanolic extracts possess therapeutic potential for the treatment of pulmonary allergic disorders such as allergic asthma.

Skullcapflavone II inhibits ovalbumin-induced airway inflammation in a mouse model of asthma

Skullcapflavone II is a flavonoid derived from Scutellaria baicalensis, a widely used herbal medicine in anti-inflammatory and anticancer therapy in Korea. Skullcapflavone II antagonized the bradykinin receptor more potently than any of the other flavonoids derived from this plant. Here, we were investigated its therapeutic effects in a mouse model of ovalbumin (OVA)-induced allergic asthma. Administration of skullcapflavone II significantly reduced airway hyperresponsiveness (AHR), airway eosinophilia, Th2 cytokine production, and increased transforming growth factor-β1 (TGF-β1) levels in bronchoalveolarlavage (BAL) fluids and lungs from OVA-sensitized and -challenged mice. Skullcapflavone II administration also significantly suppressed subepithelial collagen deposition and goblet cell hyperplasia, elevated Smad7 expression and suppressed pSmad2/3 levels. Collectively, these findings indicate that skullcapflavone II, a potential bradykinin antagonist, reduced the major pathophysiological features of allergic asthma, at least in part by acting on TGF-β1/Smad signaling pathways. Thus, skullcapflavone II may have therapeutic potential for the treatment of allergic asthma.

Oxytetracycline attenuates allergic airway inflammation in mice via inhibition of the NF-κB pathway

Oxytetracycline has been used in the treatment of acute and chronic bronchial inflammation and infectious asthma. However, its potential use for non-infectious asthma has not yet been studied. The objective of this study was to investigate the anti-inflammatory properties of oxytetracycline using a mouse asthma model. Female BALB/c mice, sensitized and challenged with ovalbumin. Naive CD4+ T cells from spleen were stimulated for 72 h with anti-CD3 (5 μg/ml) plus anti-CD28 (2.5 μg/ml) and differentiated into Th2 cells. IL-4, IL-5, IL-9, IL-13, and ovalbumin (OVA)-specific IgE production were measured by ELISA in BALF and cell supernatants. Histopathological evaluation was used to study the alterations in lung tissue. The mRNA levels of CCL5, CCL11, CCR1, and CCR3 were detected by real-time PCR. In addition, the protein levels of p-Akt, Akt, nuclear factor kappa B (NF-κB), IκBα and p-IκBα in lung tissue and cells were measured by western blot or immunofluorescence analysis. Oxytetracycline treatment caused a marked reduction in IL-4, IL-5, IL-13, immune cells, and the level of ovalbumin-specific IgE. Real-time PCR studies demonstrated that oxytetracycline can significantly reduce CCL5, CCL11 and their specific receptor CCR1 and CCR3. Histological studies demonstrated that oxytetracycline substantially inhibited ovalbumin-induced inflammatory cell infiltration in lung tissue and goblet cell hyperplasia in airway. Oxytetracycline inhibited the NF-κB activation via phosphorylation and degradation of IκBα both in vivo and in vitro. Furthermore, the increased phosphorylated Akt but not Akt protein levels in lung tissues after OVA inhalation were significantly reduced by the oral administration of oxytetracycline. These findings demonstrate an anti-inflammatory effect of oxytetracycline that might be mediated via reduction of inflammatory mediators and activation of transcription factors.

Florfenicol inhibits allergic airway inflammation in mice by p38 MAPK-mediated phosphorylation of GATA 3

Florfenicol has been shown to possess anti-inflammatory activity. However, its possible use for asthma has not yet been studied. First we investigated the anti-inflammatory properties of florfenicol using mice asthma model. BALB/c mice were immunized and challenged by ovalbumin. Treatment with florfenicol caused a marked reduction in inflammatory cells and three Th2 type cytokines in the bronchoalveolar lavage fluids of mice. The levels of ovalbumin-specific IgE and airway hyperresponsiveness were significantly altered after treatment with florfenicol. Histological studies using H&E and AB-PAS staining demonstrate that florfenicol substantially inhibited ovalbumin-induced inflammatory cells infiltration in lung tissue and goblet cell hyperplasia in the airway. These results were similar to those obtained with dexamethasone treatment. We then investigated which signal transduction mechanisms could be implicated in florfenicol activity. Our results suggested that the protective effect of florfenicol was mediated by the inhibition of the p38 MAPK-mediated phosphorylation of GATA 3.

Anti-asthmatic effects of Angelica dahurica against ovalbumin-induced airway inflammation via upregulation of heme oxygenase-1

Asthma is a chronic immune inflammatory disease characterized by variable airflow obstruction. The present study was undertaken to assess the effects of an Angelica dahurica Bentham et Hooker ethanolic extract (AD) on airway inflammation in an ovalbumin (OVA)-induced airway inflammation model. Mice that received AD displayed significantly lower airway eosinophilia, cytokine levels, including interleukin (IL)-4, IL-5, and tumor necrosis factor (TNF)-alpha levels, mucus production and immunoglobulin (Ig)E, compared with OVA-induced mice. In our experiments, AD treatment reduced airway inflammation and suppressed oxidative stress in the OVA-induced asthma model, partly via induction of heme oxygenase (HO)-1. The effects of AD on OVA-induced HO-1 induction were partially reversed by the HO-1 inhibitor, tin protoporphyrin (SnPP). Our results clearly indicate that AD is a suppressor of airway allergic inflammation, and may thus be effectively used as an anti-inflammatory drug in the treatment of asthma.

Anti-asthmatic effect of schizandrin on OVA-induced airway inflammation in a murine asthma model

Asthma comprises a triad of reversible airway obstruction, bronchial smooth muscle cell hyperreactivity to bronchoconstrictors, and chronic bronchial inflammation. Clinical and experimental findings have established eosinophilia as a sign of allergic disorders. In the present investigation, we evaluated the anti-asthmatic effects of schizandrin and its underlying mechanisms in an in vivo murine asthmatic model. To accomplish this, female BALB/c mice were sensitized and challenged with ovalbumin (OVA), and examined for the following typical asthmatic reactions: increased numbers of eosinophils and other inflammatory cells in bronchoalveolar lavage fluid (BALF); production of Th1 cytokines (such as tumor necrosis factor (TNF)-α in BALF); production of Th2 cytokines (such as interleukin IL-4 and IL-5) in BALF; presence of total and OVA-specific immunoglobulins (Ig)E in serum; presence of oxidative stress; hyperplasia of goblet cells in the lung; and marked influx of inflammatory cells into the lung. Our results collectively show that schizandrin exerts profound inhibitory effects on accumulation of eosinophils into the airways and reduces the levels of IL-4, IL-5, IFN-γ, and TNF-α in BALF. Additionally, schizandrin suppresses the production of reactive oxygen species (ROS) in a dose-dependent manner, and inhibits goblet cell hyperplasia and inflammatory cell infiltration in lung tissue. Thus, schizandrin has anti-asthmatic effects, which seem to be partially mediated by reduction of oxidative stress and airway inflammation, in a murine allergic asthma model. These results indicate that schizandrin may be an effective novel therapeutic agent for the treatment of allergic asthma.

Apigenin protects ovalbumin-induced asthma through the regulation of GATA-3 gene

Apigenin, a dietary plant-flavonoid has shown anti-inflammatory and anticancer properties, however the molecular basis of this effect remains to be elucidated. Thus we elucidated to anti-allergic effect of apigenin in ovalbumin (OVA)-induced asthma model mice. The OVA-induced mice showed allergic airway reactions. It included an increase in the number of eosinophils in bronchoalveolar lavage (BAL) fluid, an increase in inflammatory cell infiltration into the lung around blood vessels and airways, airway luminal narrowing, and the development of airway hyper-responsiveness (AHR). The administration of apigenin before the last airway OVA challenge resulted in a significant inhibition of all asthmatic reactions. Accordingly, this study may provide evidence that apigenin plays a critical role in the amelioration of the pathogenetic process of asthma in mice. These findings provide new insight into the immunopharmacological role of apigenin in terms of its effects in a murine model of asthma.

Effects of Enterococcus sp. isolated from deep seawater on inhibition of allergic responses in mice

The objective of the present study was to assess the effects of Enterococcus sp. strain TN-3 isolated from deep seawater on inhibition of eosinophil accumulation, IgE production and active cutaneous anaphylaxis (ACA). We investigated the effects of viable and non-viable TN-3 on allergen-induced peritoneal eosinophil accumulation in mice. Viable (5.4 x 1010 colony-forming units per 60 mg) or non-viable TN-3 (60 mg) was orally administered to BALB/c mice that had been sensitised with the cedar pollen (Cryptomeria japonica) allergen. Oral administration of non-viable TN-3 was effective in suppressing eosinophil accumulation while viable TN-3 was ineffective. We also examined the dose-response relationship for non-viable TN-3 in regard to eosinophil accumulation, IgE production and ACA in allergen-primed mice. Non-viable TN-3 was orally administered at doses of 15 mg (low dose), 30 mg (medium dose) and 60 mg (high dose) to BALB/c mice that had been sensitised with cedar pollen allergen. The anti-allergic effects expressed as inhibition of eosinophil accumulation, IgE production and ACA were found at the low and high doses, but not at the medium dose. These results suggest that non-viable TN-3 exhibited anti-allergic effects at doses of 15 and 60 mg.

Anti-asthmatic effect of marine red alga (Laurencia undulata) polyphenolic extracts in a murine model of asthma

The aim of the present work is focused on protective effects of an edible red alga, Laurencia undulata ethanolic (EtOH) extracts (LU) containing a large amount of polyphenols against OVA-induced murine allergic airway reactions using in vivo histological and cytokine assay. Mice sensitized and challenged with ovalbumin (OVA) showed typical asthmatic reactions as follows: an increase in the number of eosinophil in bronchoalveolar lavage fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways, and airway luminal narrowing; the development of airway hyperresponsiveness; the detection of TNF-alpha and Th2 cytokines, such as IL-4 and IL-5 in the bronchoalveolar lavage (BAL) fluid; and detection of allergen-specific IgE in the serum. The successive intraperitoneal administration of LU before the last airway OVA-challenge resulted in a significant inhibition of all asthmatic reactions. These results suggest that L. undulata polyphenolic extracts possess therapeutic potential for combating bronchial asthma associated with allergic diseases.

Effects of Ecklonia cava ethanolic extracts on airway hyperresponsiveness and inflammation in a murine asthma model: role of suppressor of cytokine signaling

Ecklonia cava (EC) is a brown alga that evidences radical scavenging activity, bactericidal activity, tyrosinase inhibitory activity, and protease inhibitory activity. However, its anti-allergic effects remain poorly understood. In the current study, we attempted to determine whether pretreatment with EC induces a significant inhibition of asthmatic reactions in a mouse asthma model. Mice sensitized and challenged with ovalbumin (OVA) evidenced typical asthmatic reactions, as follows: an increase in the number of eosinophils in bronchoalveolar lavage fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways, and airway luminal narrowing; the development of airway hyperresponsiveness; the detection of tumor necrosis factor-alpha (TNF-alpha) and Th2 cytokines, including IL-4 and IL-5 in the bronchoalveolar lavage (BAL) fluid; and the detection of allergen-specific immunoglobulin E (IgE) in the serum. However, the administration of EC extract prior to the final airway OVA challenge resulted in a significant inhibition of all asthmatic reactions. We also demonstrated that EC extracts treatment resulted in significant reductions on matrix metalloproteinase-9 (MMP-9) and Suppressor of cytokine signaling-3 (SOCS-3) expression and a reduction in the increased eosinophil peroxidase (EPO) activity. The treatment of animals with EC extracts resulted in a significant reduction in the concentrations of the Th2 cytokine (IL-4 and IL-5) in the airways, without any concomitant increase in the concentration of Th1 cytokines. These findings indicate that EC extracts may prove useful as an adjuvant therapy for allergic airway reactions via the inhibition of the Th2 response. Accordingly, this study may provide evidence that EC extract performs a critical function in the amelioration of the pathogenetic process of asthma in mice.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

An Analysis of the Effectiveness of Heat-Killed Lactic Acid Bacteria in Alleviating Allergic Diseases

Allergic diseases are reported to be caused by a skew in the balance between T helper type 1 and 2 cells. Because some lactic acid bacteria have been shown to stimulate IL-12 (p70) production, which in turn shifts the balance between the T helper type 1 and 2 cell response from the latter to the former, they have the potential to either prevent or ameliorate disease conditions or both. They have therefore been extensively studied in the recent past for their probiotic activities. Nevertheless, much less information is available concerning the microbial factors that determine the strain-dependent ability to affect the production of cytokines. The objectives of our study were first to select potentially probiotic lactobacilli that strongly stimulate cytokine production in vitro, and then to determine whether the selected Lactobacillus strains could suppress antigen-specific IgE production in vivo by using allergic model animals. Finally, our investigation was extended to analyze which bacterial components were responsible for the observed biological activity. Twenty strains of heat-killed lactobacilli isolated from humans were screened for their stimulatory activity for the production of IL-12 (p70) by murine splenocytes in vitro. The results showed that some strains of Lactobacillus plantarum and Lactobacillus gasseri had a higher stimulatory activity for IL-12 (p70) production than the other lactobacilli tested; however, this effect was strain dependent rather than species dependent. Oral administration of the heat-killed strains that showed higher stimulatory activity for IL-12 (p70) production tended to reduce the serum antigen-specific IgE levels in ovalbumin-sensitized BALB/c mice compared with the controls. Among the lactobacilli tested, L. gasseri OLL2809 showed the highest activity in reducing the level of antigen-specific IgE. Furthermore, the stimulatory activity for IL-12 (p70) production was found to be reduced after treating the lactobacilli with N-acetyl-muramidase and to be positively correlated with the amount of peptidoglycan in the cells. The present data suggest that L. gasseri OLL2809 is a good candidate for potential probiotics in terms of either the prevention or amelioration of allergic diseases or both. In addition, the strain-dependent stimulatory activity for IL-12 (p70) production was found to be due, at least in part, to the amount of peptidoglycan present in the cells.

Transcytosis of IgE-antigen complexes by CD23a in human intestinal epithelial cells and its role in food allergy

BACKGROUND & AIMS

Secreted immunoglobulins play an integral role in host defense at mucosal surfaces, and recent evidence shows that IgG can participate in antigen sampling from the intestinal lumen. We examined whether IgE also could facilitate transepithelial antigen sampling.

METHODS

Stool samples from food-allergic patients undergoing oral food challenge were analyzed for CD23 and food-specific IgE. CD23 isoform expression on primary human intestinal epithelial cells (IEC) was analyzed by polymerase chain reaction. The role of CD23 isoforms in transcytosis of antigen and IgE-antigen complexes was assessed using polarized human T84 cells retrovirally transfected with CD23a or CD23b.

RESULTS

CD23 was expressed constitutively on IECs, and food-allergic patients had increased levels of soluble CD23 and food-specific IgE in the stool after challenge. CD23a, but not CD23b, was expressed by primary human IECs. We show in transcytosis assays that CD23a, but not CD23b, acts as a bidirectional transporter of IgE. In addition, specific IgE facilitated the uptake of antigen from the apical surface of an epithelial monolayer by diverting antigen from delivery to lysosomes. Finally, delivery of antigen-IgE complexes across the epithelial barrier could induce the degranulation of rat basophil leukemia cells transfected with the human high-affinity IgE receptor.

CONCLUSIONS

These studies show that CD23a is expressed normally on human IECs, and in the presence of IgE can function as an antigen-sampling mechanism capable of activating subepithelial mast cells. IgE may serve as a secretory immunoglobulin that in concert with CD23 participates in food-induced pathophysiology of the gastrointestinal tract.

Substituted 2-phenyl-benzimidazole derivatives: novel compounds that suppress key markers of allergy

The pharmacotherapy of allergy and asthma has traditionally focused on the effecter molecules of the allergic cascade, while neglecting targets that play an early role in their development. Reasoning that IgE is central to the expansion of atopic diseases, we identified and extended a novel family of 2-(substituted phenyl)-benzimidazole inhibitors of IgE response. Pharmacological activity depends on an intact phenylbenzimidazole-bis-amide backbone, and is optimized by the presence of lipophilic terminal groups composed of either bis cycloalkyl or combinations of aliphatic and halogen-substituted aromatic groups. These compounds also inhibit IL-4 and IL-5 responses in T cells and CD23 expression on B cells, with potencies that parallel their inhibition of IgE. The broad profile of these compounds thus underscores their potential for treating the multifarious pathology of asthma.

Leishmania promastigote membrane antigen-based enzyme-linked immunosorbent assay and immunoblotting for differential diagnosis of Indian post-kala-azar dermal leishmaniasis

Diagnosis of post-kala-azar dermal leishmaniasis (PKDL), caused by Leishmania donovani, is difficult, as the dermal lesions are of several types and resemble those caused by other skin diseases, especially leprosy. Since the disease generally appears very late after the clinical cure of kala-azar in India, it is also difficult to correlate PKDL with a previous exposure to L. donovani. Very few attempts have been made so far to diagnose PKDL serologically, and the diagnostic methods vary in their sensitivities and specificities. Diagnosis of PKDL through sophisticated PCR methods, although highly sensitive, has limited practical use. We have developed a serodiagnostic method using an enzyme-linked immunosorbent assay to detect specific immunoglobulin (Ig) isotypes and IgG subclass antibodies in the sera of Indian PKDL patients. Our assay, which uses L. donovani promastigote membrane antigens, was 100% sensitive for the detection of IgG and 96.7% specific for the detection of IgG and IgG1. Optical density values for individual patients, however, demonstrated wide variations. Western blot analysis based on IgG reactivity could differentiate patients with PKDL from control subjects, which included patients with leprosy, patients from areas where kala-azar is endemic, and healthy subjects, by the detection of polypeptides of 67, 72, and 120 kDa. The recognition patterns of the majority of serum samples from patients with PKDL were also distinct from those of the serum samples from patients with visceral leishmaniasis (VL), at least for a 31-kDa polypeptide. To further differentiate patients with PKDL from those with active and cured VL, we analyzed the specific titers of the Ig isotypes and IgG subclasses. High levels of IgG, IgG1, IgG2, and IgG3 antibodies significantly differentiated patients with PKDL from patients cured of VL. The absence of antileishmanial IgE and IgG4 in patients with PKDL differentiated these patients from those with active VL. These results imply intrinsic differences in the antibodies generated in the sera from patients with PKDL and VL.

Expression of membrane-bound CD23 in nasal mucosal B cells from patients with perennial allergic rhinitis

BACKGROUND

CD23 is the low-affinity receptor for IgE on B cells and is thought to play an important role in regulation of IgE production.

OBJECTIVE

To measure the expression of membrane-bound CD23 in nasal B cells and examine its correlation with CD4 subtypes or serum IgE levels in patients with perennial allergic rhinitis.

METHOD

We used flow cytometric analysis with double, direct immunofluorescence staining of the mucosal-infiltrating lymphocytes to examine the expression of CD23 in nasal mucosal B cells of patients with perennial allergic rhinitis. The expression of CD23 in nasal B cells of patients with nonatopic rhinosinusitis served as a control.

RESULT

The ratio of CD23+ B cells to total B cells in patients with perennial allergic rhinitis was significantly higher than in nonatopic controls, whereas that of B cells to total lymphocytes was unchanged. The ratio of CCR4+ CD4 cells to total CD4 cells in allergic patients was significantly higher than in nonatopic controls, whereas the ratio of CXCR3+ CD4 cells to total CD4 cells was unchanged. There was no significant correlation between the percentages of CD23+ B cells and CCR4+ CD4 cells. In addition, the percentage of CD23+ B cells did not correlate with the total IgE level or with the specific IgE level.

CONCLUSIONS

Our results indicate that nasal mucosal CD23-bearing B cells, as well as T(H)2 cells, increase in patients with perennial allergic rhinitis. However, the expression of CD23 did not directly correlate with the number of T(H)2 cells in the nasal mucosa.

Long-term exacerbation by interleukin 13 of IgE-mediated eosinophilia in rats

Recent work shows that at least two cycles of antigen challenge applied in a 7-day interval are required to yield tissue eosinophil accumulation in IgE-passively sensitized rats. Since interleukin (IL)-13 is widely regarded as a key mediator in eosinophilic responses associated with mast cells and IgE, we investigated whether this cytokine could replace the first cycle of sensitization and challenge in its proeosinophilic role. We found that IL-13 (25 and 50 ng/cavity) injected into the rat pleural space led to eotaxin generation and a dose-dependent accumulation of eosinophils following IgE-passive sensitization and challenge 7 days later. IL-13 failed to cause eosinophil chemotaxis in vitro but induced eosinophil accumulation into the pleural cavity of naïve rats, which peaked 1 day and faded 72 h post-challenge. No changes were found 1 week after intrapleural injection of IL-13, except an approximately 40-50% increase in the number of adhered and non-adhered pleural mast cells. As recovered from the pleural effluent 1 week after IL-13, mast cells expressed the same amount of IgE bound on their surface as compared to controls. However, they generated 3-fold more LTC(4) following IgE-sensitization and challenge in vitro, keeping intact the amount of histamine released. Finally, pretreatment with zileuton (50 microg/cavity) 1 h before allergen challenge prevented eosinophil accumulation in those animals injected with IL-13 1 week before. In conclusion, our findings show that IL-13 causes a long-term exacerbation of the IgE-mediated eosinophilic response in a mechanism associated with heightened cysteinyl-leukotriene (cys-LT) production by resident mast cells.

Elevated expression of CD23 on peripheral blood B lymphocytes from patients with bullous pemphigoid: correlation with increased serum IgE

BACKGROUND

Increased serum IgE levels are occasionally found in patients with severe bullous pemphigoid (BP). CD23, a low affinity Fc receptor for IgE, is mainly expressed on mature B lymphocytes. Studies have suggested that serum levels of soluble CD23 (sCD23) correlate with serum IgE levels and disease severity in BP.

OBJECTIVE

The purpose of our study is to examine whether the expression of CD23 is elevated in BP and whether this expression correlates with serum IgE levels and disease severity.

METHODS

We measured CD23 expression on B cells from patients with active BP, pemphigus vulgaris, pemphigus foliaceus, and atopic dermatitis (AD), as well as healthy control subjects, using a flow cytometer. Serum levels of IgE and sCD23 were also measured.

RESULTS

The expression of CD23 was significantly higher in BP patients compared with healthy control subjects (P < 0.05), whereas the levels were normal in the other bullous diseases. CD23 expression tended to be higher in severe BP compared with moderate BP, and the levels in severe BP were comparable to the levels in AD. Furthermore, CD23 expression correlated positively with serum IgE levels (P < 0.002), and the IgE levels were significantly higher in severe BP than in moderate BP (P < 0.01 ). CD23 expression in BP did not correlate with sCD23 levels.

CONCLUSIONS

These results suggest that the up-regulated surface CD23 on B cells may be involved in IgE synthesis and inflammatory events in BP.

Inhibition of murine allergic airway disease by Bordetella pertussis

Whole-cell pertussis vaccines have been shown to selectively induce T helper 1 (Th1)-type responses in human and animals. In this study, we investigated whether whole-cell B. pertussis could inhibit allergic airway reactions in a murine model of asthma induced by ovalbumin (OVA). Systemic administration of whole-cell B. pertussis strongly inhibited allergic airway reactions such as eosinophil recruitment into the airway, lung inflammation, and airway hyperresponsiveness to methacholine. The inhibitory effect of whole-cell B. pertussis was mediated by chromosomal DNA and pretreatment of DNA with CpG methylase or DNase I resulted in a loss of the inhibitory effect. Treatment of animals with B. pertussis DNA significantly decreased the Th2 cytokine (interleukins IL-4 and IL-5) concentrations in the airways without increasing Th1 cytokines. These results suggest that B. pertussis DNA containing unmethylated CpG appears to be responsible for the inhibitory effect of whole cell B. pertussis on the allergic airway reactions through inhibition of the Th2 response.

TCR usage and cytokine expression in peripheral blood and BAL T cells

T cells are thought to play an important regulatory role in atopic asthma. We hypothesized that human blood and BAL T cell subsets bearing various TCR-Vbeta genes might show selective differences in their cytokine profile. Peripheral blood (PB) and bronchoalveolar lavage (BAL) T cells from seven atopic asthmatic and six non-atopic non-asthmatic subjects were stimulated with PMA and ionomycin in the presence of monensin and analysed for TCR-Vbeta expression and production of cytokines at the single cell level. The percentage of IFN-gamma- and IL-2-producing BAL T cells was elevated compared with PB T cells from both the asthmatic subjects and the non-atopic, non-asthmatic controls. A small percentage of PB and BAL T cells produced IL-4 and IL-5, in asthmatic and normal subjects. In peripheral blood, the percentage of T cells expressing each cytokine was similar in the various TCR-Vbeta subsets and in total CD3+ T cells in all normal and six of seven asthmatic subjects. However, there was a substantial degree of heterogeneity in the cytokine profile of BAL TCR-Vbeta subsets compared with the total CD3+ T cells. This was more obvious in the asthmatic subjects with a reduction in the percentage of IFN-gamma- and IL-2-expressing T cells (five of seven asthmatic subjects) and an increase in the percentage of IL-4- and IL-5-expressing T cells (two of seven asthmatic subjects). These data confirm previous findings of an elevated proportion of IFN-gamma- and IL-2-producing BAL T cells while only a small proportion of PB and BAL T cells produce IL-4 and IL-5. Moreover, subsets of BAL T cells, defined by their TCR-Vbeta usage, may differ in their cytokine profile compared with the total CD3+ T cells, implying that T cells expressing different Vbeta elements may play different roles in regulating the airway inflammation in asthma.

The identification, characterization, and distribution of guinea pig CCR4 and epitope mapping of a blocking antibody

Th2 lymphocytes play a central role in the control and maintenance of allergic inflammation. The chemokine receptor CCR4 is preferentially expressed on the surface of Th2 lymphocytes polarised in vitro. However, CCR4 is found on the surface of a significant proportion of circulating memory T lymphocytes, some of which are capable of producing the Th1-associated cytokine interferon gamma. To investigate the function of CCR4 on guinea pig (gp) T lymphocytes, we identified the open-reading frame of gpCCR4, which encodes a 361-amino acid protein with 88 and 81% amino acid identity to human and murine CCR4 sequences, respectively. Cells transfected with gpCCR4 migrated toward the human and murine orthologues of the CCR4 ligands, macrophage-derived chemokine and thymus and activation-regulated chemokine. Surface expression of CCR4, using an anti-human CCR4 monoclonal antibody, 10E4, was detected on approximately 12% of guinea pig peripheral blood T helper cells, and CCR4(+) guinea pig thymocytes were detected in low numbers. However, CCR4(+) T helper cells constituted approximately 9% of the T lymphocyte population within the normal guinea pig lung and 52% of the guinea pig bronchoalveolar lavage fluid, which is consistent with a role for CCR4 in T lymphocyte development and trafficking through normal tissues. Subsequent analysis of chimeric chemokine receptors indicated that 10E4, a functional inhibitor of gpCCR4 responses, recognized the amino terminus of CCR4.

Gene expression profiling of B cell chronic lymphocytic leukemia reveals a homogeneous phenotype related to memory B cells

B cell-derived chronic lymphocytic leukemia (B-CLL) represents a common malignancy whose cell derivation and pathogenesis are unknown. Recent studies have shown that >50% of CLLs display hypermutated immunoglobulin variable region (IgV) sequences and a more favorable prognosis, suggesting that they may represent a distinct subset of CLLs which have transited through germinal centers (GCs), the physiologic site of IgV hypermutation. To further investigate the phenotype of CLLs, their cellular derivation and their relationship to normal B cells, we have analyzed their gene expression profiles using oligonucleotide-based DNA chip microarrays representative of approximately 12,000 genes. The results show that CLLs display a common and characteristic gene expression profile that is largely independent of their IgV genotype. Nevertheless, a restricted number of genes (<30) have been identified whose differential expression can distinguish IgV mutated versus unmutated cases and identify them in independent panels of cases. Comparison of CLL profiles with those of purified normal B cell subpopulations indicates that the common CLL profile is more related to memory B cells than to those derived from naive B cells, CD5(+) B cells, and GC centroblasts and centrocytes. Finally, this analysis has identified a subset of genes specifically expressed by CLL cells of potential pathogenetic and clinical relevance.

Serum levels of interleukins (IL)-4, IL-5, IL-13, and interferon-gamma in acute asthma

T-cell activation and alteration of cytokine levels are involved in the pathogenesis of bronchial asthma. However, the profile of circulating T-lymphocyte subsets and related cytokines during acute asthmatic attacks is still unclear. We hypothesized that serum levels of interleukin (IL)-4, IL-5, and IL-13 would be increased, whereas IFN-y would be decreased in acute asthma. The subjects enrolled in this study included 58 acute asthmatics, 22 asymptomatic asthmatics, and 10 healthy controls. Serum levels of IL-4, IL-5, IL-13, and IFN-gamma were measured using a sandwich enzyme-linked immunosorbent assay. We correlated serum levels of IL-4, IL-5, IL-13, and IFN-gamma with initial forced expiratory volume in 1 sec (FEV1). Compared with control subjects, acute asthmatics had significantly increased levels of circulating IL-4 (p < 0.001), IL-5 (p < 0.001), and IL-13 (p < 0.001), although the differences were of borderline significance in serum IFN-gamma (p = 0.069). There were also significant differences in the circulating levels of IL-4, IL-5, and IL-13 between acute asthmatics and asymptomatic asthmatics. There was no significant association between initial FEV1 and serum levels of IL-4 or IL-13, however, among acute asthmatics, a lower initial FEV1 was associated with higher IL-5 and/or lower IFN-gamma levels. Our results suggest that serum levels of IL-4, IL-5, and IL-13 may be elevated in acute asthma, and that higher levels of IL-5 and/or lower levels of IFN-gamma are associated with severe airway obstruction.

Isolated airways from current smokers are hyper-responsive to histamine

Epidemiological studies suggest that bronchial hyper-responsiveness (BHR) and elevated levels of serum IgE are more frequently found in current smokers than in ex-smokers. Since elevated serum IgE is associated with BHR under both in vivo and in vitro conditions, we aimed to assess whether smoking affects BHR independently from IgE. Lung resection material was obtained from 27 current smokers and 11 non-smokers with low serum IgE (< 100 U/mL). Peripheral airways were cut into rings and incubated overnight in the presence (passively sensitized) or absence (non-sensitized) of serum containing IgE levels above 250 U/mL. Isometric contractile responses to histamine were assessed in the organ bath. Compared with non-smokers, isolated airways from smokers showed significantly increased responses to histamine (P < 0.05, ANOVA). Passive sensitization enhanced responses in both groups by about the same amount (P < 0.05, both). In patients with low serum IgE current smoking is associated with increased bronchial responsiveness to histamine in vitro, which can be further enhanced by passive sensitization. These findings suggest that both smoking and serum IgE contribute to non-specific airway hyper-responsiveness.

Specific immunoglobulin E responses in ZAP-70-deficient patients are mediated by Syk-dependent T-cell receptor signalling

ZAP-70 deficiency is a rare primary immunodeficiency characterized by the absence of peripheral CD8+ T cells and defects in T-cell receptor (TCR) signalling. T cells in ZAP-70-deficient patients are assumed to have no helper functions for B-cell immunoglobulin synthesis, whereas the patients rarely have antigen-specific antibodies. We experienced a ZAP-70-deficient patient, who had immunoglobulin E (IgE) antibodies specific to food allergens, and we investigated the mechanisms of switching to IgE in the patient. Peripheral blood mononuclear cells from the patient did not proliferate upon stimulation with the antigens but produced distinct levels of interleukin-4 (IL-4). Cell sorting analysis indicated that the cells that produced IL-4 in response to the antigens were enriched in CD4+ T cells. Purified CD4+ T cells from the patient produced IL-4 and expressed CD40L upon stimulation with anti-CD3. Moreover, CD4+ T cells pretreated with anti-CD3 induced mature epsilon transcript on naive B cells. Since the results indicated that there remained sufficient T-cell receptor (TCR)-signalling in the patient's T cells to exert antigen-specific IgE switching on B cells, we next investigated the expression of the ZAP-70-homologous kinase Syk. Syk was present in high levels in patient's CD4+ T cells and was tyrosine-phosphorylated after TCR stimulation. Inhibition of Syk by piceatannol resulted in decreased production of IL-4 and expression of CD40L on patient's CD4+ T cells. Moreover, Syk was expressed on all human T-cell leukaemia virus (HTLV-1)-transformed T-cell lines derived from peripheral blood of the patient, whereas it was low or undetectable in control lines. It was therefore concluded that specific IgE responses in the patient were most likely to be mediated by Syk-dependent TCR-signalling.

Anti-allergy properties of fermented foods: an important immunoregulatory mechanism of lactic acid bacteria?

Clinical reports have suggested that dietary consumption of fermented foods, such as yogurt, can alleviate some of the symptoms of atopy and might also reduce the development of allergies, possibly via a mechanism of immune regulation. Controlled studies have indicated that consumption of fermented milk cultures containing lactic acid bacteria (LAB) can enhance production of Type I and Type II interferons at the systemic level. In animal models, LAB have been shown to promote interferon expression, and to reduce allergen-stimulated production of IL-4 and IL-5 in some cases. Recent results have shown that LAB are potent inducers of pro-interferon monokines (IL-12 and IL-18), and that cytokine secretion is stimulated by the interaction of Gram-positive cell wall components with surface receptors of mononuclear phagocytes, via NF-kappa B and STAT signalling pathways. However, it is clear that the extent and quality of LAB-induced immunoregulation is strain-dependent. This review discusses the clinical and laboratory evidence for anti-allergy properties of fermented foods, and proposes a model for the mechanism by which some well-defined strains of immunoregulatory LAB might down-regulate a Th2 allergic phenotype.

Environmental factors favoring the allergen-specific Th2 response in allergic subjects

Allergen-reactive type 2 helper T cells (Th2) play a triggering role in the activation and/or recruitment of IgE antibody-producing B cells, mast cells, and eosinophils, i.e., the cellular triad involved in the allergic inflammation. Interleukin (IL)-4 production at the time of antigen presentation to the Th cell is critical for the development of Th2 cells. Other cytokines, such as IL-1 and IL-10, and hormones, such as calcitriol and progesterone, also play a positive role. In contrast, cytokines such as interferon (IFN)-alpha, IFN-gamma, IL-12, and transforming growth factor (TGF)-beta, and relaxin play a negative regulatory role on the development of Th2 cells. However, the mechanisms underlying the preferential activation by environmental allergens of Th2 cells in atopic individuals still remain obscure. Some gene products selectively expressed in Th2 cells or selectively controlling the expression of IL-4 have recently been described. Moreover, cytokines and other gene products that dampen the production of IL-4, as well as the development and/or the function of Th2 cells, have been identified. These findings allow us to suggest that the upregulation of genes controlling IL-4 expression and/or abnormalities of regulatory mechanisms of Th2 development and/or function may be responsible for Th2 responses against common environmental allergens in atopic subjects.

Leukotriene inhibitors and non-steroidal therapies in the treatment of asthma

Asthma is the most common chronic disease of childhood whose morbidity and mortality continues to rise [1]. Drugs used in the treatment of asthma must be targeted at reversing three principle pathophysiologic features: bronchoconstriction, mucus plugging/hypersecretion and inflammation. In the past two decades, the contribution of airway inflammation to the development and progression of asthma symptoms and airway pathology has become a critical focus. Chronic airway inflammation can lead to the progressive decline and irreversible loss of lung function and airway remodelling [2]. In recent years, therapies aimed at diminishing airway inflammation have been at the forefront of asthma management. Steroids have been extensively studied and used as primary anti-inflammatory agents in the management of the asthmatic patient with persistent symptoms of varying severity. Within the last decade, however, several additional non-steroidal classes of drugs have begun to emerge as anti-inflammatory agents for the treatment of asthma. This article will focus on these non-steroidal drugs which have been developed and investigated within the last 5 years. Particular emphasis will be placed on leukotriene receptor antagonists, but anti-IgE and anti-IL-4 therapies, as well as phosphodiesterase inhibitors will also be discussed. Of these new therapies, only two leukotriene receptor antagonists, montelukast (Singulairtrade mark, Merck) and zafirlukast (Accolatetrade mark, AstraZeneca) and the 5-lipoxygenase inhibitor, zileuton (Zyflotrade mark, Abbott Laboratories), have been recommended, approved and are currently available for use in the treatment of paediatric patients with asthma in the United States.

T regulatory cells 1 inhibit a Th2-specific response in vivo

We recently described a new population of CD4(+) regulatory T cells (Tr1) that inhibits proliferative responses of bystander T cells and prevents colitis induction in vivo through the secretion of IL-10. IL-10, which had been primarily described as a Th2-specific cytokine inhibiting Th1 responses, has displayed in several models a more general immune suppression on both types of effector T cell responses. Using an immediate hypersensitivity model in which BALB/c mice immunized with OVA (alum) normally generate Th2-dominated responses, we examined the ability of OVA-specific Tr1 T cell clones to inhibit OVA-specific cytokines and Ab responses. In contrast to Th2 or Th1 T cell clones, transfer of Tr1 T cell clones coincident with OVA immunization inhibited Ag-specific serum IgE responses, whereas IgG1 and IgG2a synthesis were not affected. This specific inhibition was mediated in part through IL-10 secretion as anti-IL-10 receptor Abs treatment reverted the inhibitory effect of Tr1 T cell clones. Although specifically targeted to IgE responses, Tr1 clones' inhibitory effects were more profound as they affected Ag-specific Th2 cell priming both in term of proliferative responses and cytokine secretion. These results suggest that regulatory T cells may play a fundamental role in maintaining the balance of the immune system to prevent allergic disorders.

Immune mechanisms of smooth muscle hyperreactivity in asthma

Asthma is characterized by bronchial hyperresponsiveness to a variety of bronchospasmogenic stimuli. To study the pathophysiologic mechanisms underlying the increased sensitivity and degree of maximal airway narrowing, various in vivo and in vitro models have been developed with methods of active and passive sensitization. These studies indicated a major role for alterations in the smooth muscle itself rather than neural dysfunction or airway inflammation as the underlying cause for the development of bronchial hyperresponsiveness. During the last years smooth muscle cells were found to exhibit not only the "classical" contractile phenotype but also a proliferative-synthetic phenotype, which is capable of producing proinflammatory cytokines, chemotaxins, and growth factors. Allergic sensitization can alter both contractile and secretory functions, thereby indicating that the smooth muscle cell could contribute directly to the persistence of airway inflammation in asthma. A better understanding of the changes within the smooth muscle cells and of the mechanisms that lead to their induction could contribute to the development of novel therapeutic approaches for the treatment of asthma.

Serum immunoglobulin E levels predict human airway reactivity in vitro

BACKGROUND

Airway hyperresponsiveness to non-specific stimuli is one characteristic feature of airway diseases such as bronchial asthma and chronic bronchitis. Until now, studies aiming to demonstrate a relationship between in vivo conditions associated with airway hyperreactivity and in vitro airway responsiveness have been inconclusive.

OBJECTIVE

Since serum immunoglobulin (Ig) E is believed to be one determinant of airway reactivity in vivo, we studied whether in vitro airway reactivity in lung resection material from patients with elevated levels of serum IgE was increased as compared with patients with undetectable IgE. By this approach, we aimed to elucidate the role of circulating IgE for bronchial smooth muscle reactivity in vitro.

METHODS

Bronchial rings from nine patients with total serum IgE levels above 200 U/mL and 10 patients with total serum IgE levels below 10 U/mL were passively sensitized, i.e. incubated overnight with buffer or sensitizing serum containing high levels of total IgE (> 250 U/mL). Afterwards, contractile responses to histamine were assessed in the organ bath.

RESULTS

Histamine responsiveness was significantly increased in airways obtained from patients with IgE levels above 200 U/mL as compared with airways from patients with IgE levels below 10 U/mL (P < 0.05). Passive sensitization of bronchi from patients with low IgE significantly increased histamine responsiveness, as compared with non-sensitized controls from the same patients (P < 0.05). In contrast, passive sensitization of airways from patients with elevated IgE did not further increase responsiveness. There was no difference in histamine reactivity between non-passively sensitized and passively sensitized tissue preparations from patients with IgE above 200 U/mL and passively sensitized tissues from patients with IgE below 10 U/mL.

CONCLUSION

Our findings reveal that elevated levels of serum IgE predict airway hyperresponsiveness to histamine in vitro. At the same time, they indicate that the in vitro model of passive sensitization, in addition to its ability to induce allergen responses, also mimics conditions of non-specific airway hyperreactivity, which are relevant under in vivo conditions.

Cytokine profiles of BAL T cells and T-cell clones obtained from human asthmatic airways after local allergen challenge

BACKGROUND

This study assessed the heterogeneity of cytokine expression in asthma before and after local allergen challenge.

METHODS

BAL T cells were obtained 10 min or 24 h after local endobronchial allergen challenge in atopic asthmatic subjects. T cells were cloned by direct limiting dilution. mRNA expression was assessed by RT-PCR, and cytokine protein production by ELISA.

RESULTS

Unstimulated baseline BAL T cells expressed mRNA for IFN-gamma, IL-13, and TNF-alpha. A minority of samples expressed IL-4 and IL-5, but no IL-3 mRNA was detected. PHA stimulation increased expression of IL-3, IL-4, and IL-5 mRNA in 4/6 samples. IL-13 and GM-CSF mRNA were found in BAL cells after allergen challenge, but expression of IFN-gamma was reduced. Both IL-4 and IL-3 were strongly upregulated after PHA stimulation, while the expression of TNF-alpha and IFN-gamma was reduced, compared to equivalent baseline samples. Seventeen panels of BAL T-cell clones were derived (average cloning efficiency 1/40 T cells). Seven panels survived to 8 weeks for analysis. Clones derived 4 h after saline challenge showed strong mRNA signals for IL-13, IL-4, and IFN-gamma, whereas clones derived 24 h after allergen challenge expressed IL-13, GM-CSF, IL-3, IL-4, and often IL-5 (i.e., closer to the Th2 profile). There was considerable heterogeneity in the patterns of cytokine mRNA and protein production by different clones.

CONCLUSIONS

T cells from asthmatic airways produce IL-13, IFN-gamma, and TNF-alpha, but after allergen challenge, type 2 cytokines are upregulated. mRNA and protein analysis provide complementary information on airways T-cell cytokine profiles.

Asthma: an inflammatory mediator soup

Reversible or partially reversible airway obstruction, inflammation, and bronchial hyperresponsiveness to various stimuli are the defining characteristics of asthma. Airway obstruction in asthma is a complex event that is due to bronchospasm, inflammation, and mucus formation. Inflammation has assumed a more central role in the pathogenesis of the disease, as it contributes not only to airflow obstruction, but also to bronchial hyperresponsiveness. The inciting trigger, or inhaled allergen, in asthma induces the activation of mast cells and macrophages with the subsequent release of several proinflammatory mediators, including leukotrienes, chemotactic factors, and cytokines. Antigen processed by macrophages is presented to undifferentiated T helper cells, inducing differentiation to the Th2 phenotype, with the subsequent release of IL-4 and IL-5, causing IgE synthesis and eosinophil infiltration, respectively. Macrophage-derived cytokines, such as IL-1, TNF-alpha, and IFN-gamma, activate endothelial cells, upregulating the expression of adhesion molecules such as ICAM-1 and VCAM-1, which permit egression of leukocytes from the vasculature to the airway mucosa. Several inflammatory cells, such as eosinophils, mast cells, and macrophages, not only cause airway damage, but also synthesize cytokines that perpetuate the inflammatory process. This complex interplay of inflammatory cells and mediators causes the classic histopathophysiologic features in the airways of both symptomatic and asymptomatic individuals with asthma, emphasizing the importance of early recognition and antiinflammatory treatment.

BLyS: member of the tumor necrosis factor family and B lymphocyte stimulator

The tumor necrosis factor (TNF) superfamily of cytokines includes both soluble and membrane-bound proteins that regulate immune responses. A member of the human TNF family, BLyS (B lymphocyte stimulator), was identified that induced B cell proliferation and immunoglobulin secretion. BLyS expression on human monocytes could be up-regulated by interferon-gamma. Soluble BLyS functioned as a potent B cell growth factor in costimulation assays. Administration of soluble recombinant BLyS to mice disrupted splenic B and T cell zones and resulted in elevated serum immunoglobulin concentrations. The B cell tropism of BLyS is consistent with its receptor expression on B-lineage cells. The biological profile of BLyS suggests it is involved in monocyte-driven B cell activation.