Mediation of local homeostasis and inflammation by leukotrienes and other mast cell-dependent compounds

Beyond CCR7: dendritic cell migration in type 2 inflammation

Conventional dendritic cells (cDCs) are crucial antigen-presenting cells that initiate and regulate T cell responses, thereby shaping immunity against pathogens, innocuous antigens, tumors, and self-antigens. The migration of cDCs from peripheral tissues to draining lymph nodes (dLNs) is essential for their function in immune surveillance. This migration allows cDCs to convey the conditions of peripheral tissues to antigen-specific T cells in the dLNs, facilitating effective immune responses. Migration is primarily mediated by chemokine receptor CCR7, which is upregulated in response to homeostatic and inflammatory cues, guiding cDCs to dLNs. However, during type 2 immune responses, such as those triggered by parasites or allergens, a paradox arises-cDCs exhibit robust migration to dLNs despite low CCR7 expression. This review discusses how type 2 inflammation relies on additional signaling pathways, including those induced by membrane-derived bioactive lipid mediators like eicosanoids, sphingolipids, and oxysterols, which cooperate with CCR7 to enhance cDC migration and T helper 2 (Th2) differentiation. We explore the potential regulatory mechanisms of cDC migration in type 2 immunity, offering insights into the differential control of cDC trafficking in diverse immune contexts and its impact on immune responses.

Bacillus thuringiensis Cry1A Insecticidal Toxins and Their Digests Do Not Stimulate Histamine Release from Cultured Rat Mast Cells

Public acceptance of genetically modified crops engineered with Bacillus thuringiensis (Bt) insecticidal protein genes (BT-GMCs), which confer resistance to various lepidopteran insect pests, is generally lacking. As a major concern over BT-GMCs is the allergenicity of insecticidal proteins, alleviating safety concerns should help increase public acceptance. In this study, three lepidopteran-specific Bt toxins, Cry1Aa, Cy1Ab, and Cry1Ac, were treated with simulated digestive fluids under various conditions. Western blotting using antiserum raised against individual segments (α-helices of domain I and β-sheets of domains II and III) of Cry1Aa showed that digestion produces a variety of polypeptides. In particular, the transmembrane α4-α5 of domain I, which may retain the ability to form pores, was the most resistant to digestion. Intact Cry1A toxins and these digests were then applied to RBL-2H3 cultured rat mast cells to determine whether the toxins directly induce histamine release. However, fluorescence microscopy revealed no specific binding of Cry1A toxins to RBL-2H3 cultured rat mast cells. In addition, neither the OPA method nor HPLC analysis detected significant histamine release from mast cells treated with Cry1A toxins and these digests. Our results provide important data supporting the safety of Cry1A toxins and potentially BT-GMCs.

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

8-iso-prostaglandin E2 induces nasal obstruction via thromboxane receptor in murine model of allergic rhinitis

Thromboxane receptor (TP) mediates nasal obstruction, a typical symptom of allergic rhinitis. Since it has been reported that several types of eicosanoids, such as non-enzymatic oxidation product of arachidonic acid isoprostane, act as a TP ligand, there is a possibility that some other eicosanoids contribute to the TP-mediated nasal obstruction. The aim of this study is to investigate the mechanisms of TP-mediated nasal obstruction. Intranasal challenges of ovalbumin (OVA) induced nasal obstruction in mice. Pharmacological blockade of TP receptor but not thromboxane A₂ synthase inhibited OVA-induced nasal obstruction. Simultaneous analysis of eicosanoids in nasal lavage fluid and the responses in trans-endothelial resistance suggested that 8-iso-prostaglandin E₂ (PGE₂ ) can be a candidate for TP ligand. Intranasal challenge of 8-iso-PGE₂ induced vascular hyperpermeability and nasal obstruction in TP receptor-dependent manner. Wholemount immunostaining of nasal septum mucosa revealed that 8-iso-PGE₂ increased plasma leakage accompanied by distention of venous sinusoids. This study shows that 8-iso-PGE₂ is a contributor in TP-mediated nasal obstruction in mice.

The roles of lipid mediators in type I hypersensitivity

Type I hypersensitivity is an immediate immune reaction that involves IgE-mediated activation of mast cells. Activated mast cells release chemical mediators, such as histamine and lipid mediators, which cause allergic reactions. Recent developments in detection devices have revealed that mast cells simultaneously release a wide variety of lipid mediators. Mounting evidence has revealed that mast cell-derived mediators exert both pro- and anti-inflammatory functions and positively and negatively regulate the development of allergic inflammation. This review presents the roles of major lipid mediators released from mast cells. Author believes this review will be helpful for a better understanding of the pathogenesis of allergic diseases and provide a new strategy for the diagnosis and treatment of allergic reactions.

Potassium bromate (KBrO3) modulates oxidative stress and inflammatory biomarkers in sodium hydroxide (NaOH) - induced Crohn's colitis in Wistar rats

Potassium bromate (KBrO₃) present in consumed ozonised water was recently documented to exacerbate experimental gastric ulcer. Information, however, is vague as regards its effects in the colon where water reabsorption occurs. In this study, we observed the possible effects of KBrO₃ on oxidative stress and inflammatory biomarkers in sodium hydroxide (NaOH) - induced Crohn's colitis (CC). Wistar rats (180-200 g) were divided into six groups (n = 10): (i) control; (ii) untreated CC (induced by 1.4% NaOH; intra-rectal administration); and (iii-vi) CC treated with vitamin E, KBrO₃, vitamin E+KBrO₃, and sulphazalazine, respectively, for 7 days. Body weight and stool score were monitored daily. By day 3 and 7, excised colon was evaluated for ulcer scores and biochemical and histological analysis. Blood samples collected on days 3 and 7 were assayed for haematological indices using standard methods. Data were subjected to analysis of variance (ANOVA) and p ≤ 0.05 considered significant. Platelet/lymphocyte ratio, colonic ulcer score, malondialdehyde, and mast cells were significantly decreased while colonic sulfhydryl, and Ca²⁺- and Na⁺/K⁺-ATPase activities were increased following KBrO₃ treatment compared with untreated CC. These findings suggest that KBrO₃ may mitigate against NaOH-induced CC via inhibiting mast cell population and oxidative and inflammatory content but stimulating colonic sulfhydryl and Ca²⁺- and Na⁺/K⁺-ATPase activities.

Targeting lipid mediators in cancer biology

Bioactive lipids are essential components of human cells and tissues. As discussed in this review, the cancer lipidome is diverse and malleable, with the ability to promote or inhibit cancer pathogenesis. Targeting lipids within the tumor and surrounding microenvironment may be a novel therapeutic approach for treating cancer patients. Additionally, the emergence of a novel super-family of lipid mediators termed specialized pro-resolving mediators (SPMs) has revealed a new role for bioactive lipid mediators in the resolution of inflammation in cancer biology. The role of SPMs in cancer holds great promise in our understanding of cancer pathogenesis and can ultimately be used in future cancer diagnostics and therapy.

Structures of the Human PGD2 Receptor CRTH2 Reveal Novel Mechanisms for Ligand Recognition

The signaling of prostaglandin D₂ (PGD₂) through G-protein-coupled receptor (GPCR) CRTH2 is a major pathway in type 2 inflammation. Compelling evidence suggests the therapeutic benefits of blocking CRTH2 signaling in many inflammatory disorders. Currently, a number of CRTH2 antagonists are under clinical investigation, and one compound, fevipiprant, has advanced to phase 3 clinical trials for asthma. Here, we present the crystal structures of human CRTH2 with two antagonists, fevipiprant and CAY10471. The structures, together with docking and ligand-binding data, reveal a semi-occluded pocket covered by a well-structured amino terminus and different binding modes of chemically diverse CRTH2 antagonists. Structural analysis suggests a ligand entry port and a binding process that is facilitated by opposite charge attraction for PGD₂, which differs significantly from the binding pose and binding environment of lysophospholipids and endocannabinoids, revealing a new mechanism for lipid recognition by GPCRs.

Comparison of innate immunity mediators in peritoneal fluid and spleen between young and aged rats

BACKGROUND

Aging of the innate immune system can result in a wide array of decreasing biological function.

AIM

We investigated differences between young and old mice in the expression of the pattern-recognition receptors (PRRs).

METHODS

mRNA levels for PRRs were quantified and compared in peritoneal fluid and spleens from old (36 months old) and young (1 month old) Wistar white rats (n = 8/group) using real-time reverse transcription-polymerase chain reaction.

RESULTS

In old rats, TLR-5 and -7 were decreased in peritoneal fluid, whereas TLR 4/6/9 and Syk were increased in the spleen (p < 0.05). In young rats, TLR 2/4, dectin-1, and Trem-1 were increased in peritoneal fluid and decreased in the spleen (p < 0.05), but TLR 1/3/7/9/10 and Syk were vice versa (p < 0.05).

DISCUSSION

Several parameters related to innate immunity may change with aging.

CONCLUSION

Different expressions of mRNA for several PRRs are suggesting changes in innate immune responses in association with aging.

The Prognostic Significance of Mast Cell Count in Soft Tissue Sarcomas

Mast cells (MC) are known to play an important role in IgE-dependent allergic reaction, host defense against parasite infestation, local hemostasis, inflammation, and angiogenesis. The significance of MC in tumor surveillance has been studied with conflicting results. The presence of MC in tumor has been described as evidence of a host immunologic antitumor response, and a high count of tumor-associated MC has been considered as a favorable prognostic factor in sarcomas. In other studies, MC have been shown to have an adverse role in neoplastic proliferation. In this study, tumor-associated MC were histologically quantitated in 75 soft tissue sarcomas. We found that soft tissue sarcomas with a higher MC count (n=or>six) were associated with significant better survival and relatively low incidence of metastasis in contrast to those with a lower count (n<six). There was no correlation between MC count and the histologic type, grade, or size of the sarcomas. Although the role of mast cells in tumor surveillance is still under investigation, quantitive assessment of tumorassociated MC on routine histologic sections could be used as an additional prognostic factor in soft tissue sarcomas.

Sphingosine-1-phosphate and other lipid mediators generated by mast cells as critical players in allergy and mast cell function

Sphingosine-1-phosphate (S1P), platelet activating factor (PAF) and eicosanoids are bioactive lipid mediators abundantly produced by antigen-stimulated mast cells that exert their function mostly through specific cell surface receptors. Although it has long been recognized that some of these bioactive lipids are potent regulators of allergic diseases, their exact contributions to disease pathology have been obscured by the complexity of their mode of action and the regulation of their metabolism. Indeed, the effects of such lipids are usually mediated by multiple receptor subtypes that may differ in their signaling mechanisms and functions. In addition, their actions may be elicited by cell surface receptor-independent mechanisms. Furthermore, these lipids may be converted into metabolites that exhibit different functionalities, adding another layer of complexity to their overall biological responses. In some instances, a second wave of lipid mediator synthesis by both mast cell and non-mast cell sources may occur late during inflammation, bringing about additional roles in the altered environment. New evidence also suggests that bioactive lipids in the local environment can fine-tune mast cell maturation and phenotype, and thus their responsiveness. A better understanding of the subtleties of the spatiotemporal regulation of these lipid mediators, their receptors and functions may aid in the pursuit of pharmacological applications for allergy treatments.

Single- and multiple-dose tolerability and pharmacokinetics of the CRTH2 antagonist setipiprant in healthy male subjects

Chemoattractant receptor-homologous molecule expressed on T helper (Th) 2 cells (CRTH2) is a G-protein-coupled receptor for prostaglandin D2 (PGD2), a key mediator in inflammatory disorders such as asthma and allergic rhinitis. In this study, we investigated the single- and multiple-dose tolerability and pharmacokinetics (PKs) of setipiprant, an orally active, potent, and selective CRTH2 antagonist. This randomized, double-blind, placebo-controlled study was performed in two parts in healthy male subjects. In study Part A, single oral doses of up to 2000 mg setipiprant or placebo were given to sequential groups of eight subjects each. Additionally, the impact of food on the PKs was investigated in one-dose group. In study Part B, two groups of subjects received 500 or 1000 mg setipiprant or placebo b.i.d. during 5.5 days. At regular intervals, tolerability variables and plasma and urine levels of setipiprant were determined. Setipiprant was well tolerated after single- and multiple-dose administration. Headache was the most frequently reported adverse event. No treatment effect on tolerability variables was observed. After single- and multiple-dose administration, setipiprant was rapidly absorbed and followed a biphasic elimination pattern with an elimination half-life between 10 and 18 h. Steady-state conditions were reached after 2-3 days and setipiprant did not accumulate. Exposure to setipiprant was lower in the presence of food. Urinary excretion of unchanged setipiprant did not exceed 7% of the administered dose. In this entry-into-human study, setipiprant showed good tolerability and a favorable PK profile, thus warranting its development in the treatment of inflammatory disorders.

Leukotriene biosynthesis inhibitors

This review describes the design and current development of leukotriene biosynthesis inhibitors as potential antiinflammatory agents. Knowledge of the enzymatic mechanism of 5-lipoxygenase led to specific inhibitors of this enzyme which catalyzes a key step in the leukotriene pathway. Competitive inhibitors include iron chelators, redox agents and alternate substrates. Further, the potential of product inhibitors and mechanism based inactivators of 5-lipoxygenase is discussed.

IgE, mast cells, and eosinophils in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific immune and inflammatory mechanisms. Atopy is among the major features of the diagnosis criteria for AD but is not an essential feature. Thus, patients diagnosed with AD can be atopic or non-atopic. This review focuses on the role of IgE, mast cells, and eosinophils in the pathogenesis of AD. The known functions of IgE in allergic inflammation suggest that IgE and IgE-mediated mast cell and eosinophil activation contribute to AD, but direct evidence supporting this is scarce. The level of IgE (thus the degree of allergic sensitization) is associated with severity of AD and contributed by abnormality of skin barrier, a key feature of AD. The function of IgE in development of AD is supported by the beneficial effect of anti-IgE therapy in a number of clinical studies. The role of mast cells in AD is suggested by the increase in the mast cell number and mast cell activation in AD lesions and the association between mast cell activation and AD. It is further suggested by their role in mouse models of AD as well as by the effect of therapeutic agents for AD that can affect mast cells. The role of eosinophils in AD is suggested by the presence of eosinophilia in AD patients and eosinophil infiltrates in AD lesions. It is further supported by information that links AD to cytokines and chemokines associated with production, recruitment, and activation of eosinophils.

Preliminary Analysis of the Anti-Inflammatory Activity of Essential Oils of Zingiber zerumbet

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely used for the treatment of inflammation. However, despite their effectiveness, most NSAIDs cause various side effects that negatively affect the management of inflammation and, in part, pain. Thus, there is a need to search for new anti-inflammatory agents with few, or no, side effects. Natural products of plant, animal, or microorganism origin have been good sources of new bioactive compounds. The present study was carried out to evaluate the acute and chronic anti-inflammatory activities of the essential oil of the rhizomes of Zingiber zerumbet (Zingiberaceae) using the carrageenan-induced paw edema and cotton pellet-induced granuloma tests, respectively. The effect of the essential oil on inflammatory- and noninflammatory-mediated pain was also assessed using the formalin test. Essential oil of Z. zerumbet, at doses of 30, 100, and 300 mg/kg, was administered intraperitoneally to rats. The substance exhibited significant anti-inflammatory activity both in acute and chronic animal models. The essential oil also inhibited inflammatory- and noninflammatory-mediated pain when assessed using the formalin test. In conclusion, the essential oil of Z. zerumbet possessed anti-inflammatory activity, in addition to its antinociceptive activity, which may explain its traditional uses to treat inflammatory-related ailments.

CRTH2 mediates the activation of human Th2 cells in response to PGD(2) released from IgE/anti-IgE treated nasal polyp tissue

BACKGROUND

Mast cells release mediators upon stimulation that contribute to the pathogenesis of chronic airway disease, including the recruitment and activation of Th2 lymphocytes. The objective was to determine the involvement of prostaglandin D(2) (PGD(2)) and its receptors in the chemotaxis of Th2 cells, using nasal polyp tissue.

METHODS

Tissue explants from ten patients with nasal polyposis were incubated with RPMI alone or RPMI containing IgE/anti-IgE for 30 min. Some samples were treated with diclofenac to inhibit the production of PGD(2). Supernatants were assayed for PGD(2) content and for their ability to promote human Th2 cell chemotaxis in the presence and absence of a CRTH2 antagonist. Transcript levels of D protanoid receptor type 1 (DP(1)), chemoattractant receptor-homologous receptor expressed on Th2 cells (CRTH2) and PGD(2) synthase were analysed by real time PCR.

RESULTS

Increased release of PGD(2) by nasal polyp tissue treated with IgE/anti-IgE was significantly inhibited by preincubation of the tissue with diclofenac. Transcript levels of PGD(2) synthase, DP(1) and CRTH2 receptors increased after stimulation with IgE/anti-IgE. Supernatants from IgE/anti-IgE-stimulated nasal polyp tissue caused significantly increased chemotaxis of Th2 cells. The levels of PGD(2) produced and the degree of Th2 cell chemotaxis were highly correlated. Diclofenac inhibited the production of Th2 cell chemotactic activity, and the chemotactic effect of the supernatant on Th2 cells was inhibited by the CRTH2 antagonist ramatroban.

CONCLUSION

These data suggest that in immunologically activated nasal polyp tissue, PGD(2) produced by mast cells promotes the migration of Th2 cells through a CRTH2 dependent mechanism.

Prostanoids and inflammation: a new concept arising from receptor knockout mice

Prostanoids including various types of prostaglandins and thromboxanes are arachidonate metabolites produced and released in response to a variety of physiological and pathological stimuli and function to maintain the body homeostasis. Since cyclooxygenase, the enzyme initiating their biosynthesis, is inhibited by aspirin-like antipyretic, anti-inflammatory, and analgesic drugs, contribution of prostanoids to acute inflammation such as fever generation, pain sensitization, and inflammatory swelling has been recognized very early. On the other hand, since aspirin-like drugs generally show little effects on allergy and immunity, it has been believed that prostanoids play little roles in these processes. Prostanoids act on a family of G-protein-coupled receptors designated PGD receptor, PGE receptor subtypes EP1-EP4, PGF receptor, PGI receptor, and TX receptor to elicit their actions. Studies using mice deficient in each of these receptors have revealed that prostanoids indeed function in the above aspirin-sensitive processes. However, these studies have also revealed that prostanoids exert both pro-inflammatory and anti-inflammatory actions not only by acting as mediators of acute inflammation but also by regulating gene expression in mesenchymal and epithelial cells at inflammatory site. Such dual actions of prostanoids are frequently seen in immune and allergic reactions, where different type of prostanoids and their receptors often exert opposite actions in a single process. Thus, a new concept on the role of prostanoids in inflammation has arisen from studies using the receptor knockout mice.

Association of CRTH2 gene polymorphisms with the required dose of antihistamines in patients with chronic urticaria

INTRODUCTION

Chronic urticaria (CU), defined as the recurring incidence of wheals with or without angioedema for more than 6 weeks, is a common disorder associated with mast cell activation, degranulation, and histamine release. Considering the association between the CRTH2 gene and mast cells, we investigated the association of this gene polymorphism with the CU phenotype and antihistamine drug requirement in patients with CU.

MATERIALS & METHODS

Two groups consisting of 384 patients with CU and 231 patients as normal controls (NCs) were enrolled from the Department of Allergy and Rheumatology, Ajou University Hospital, Suwon, Korea. Two polymorphisms of the CRTH2 gene, -466T>C and -129C>A were genotyped using primer extension methods.

RESULTS

No significant differences were detected in the genotype and allele frequencies of the two CRTH2 polymorphisms between the CU and NC groups, and no significant associations were observed with clinical parameters, such as atopy status, serum total IgE, prevalence of autoantibodies and duration of CU. However, CU patients with homozygous TT genotypes had significantly higher dose requirements of antihistamines to control the CU symptoms (164.56 +/- 115.62 vs 137.38 +/- 90.15 loratadine equivalents, mg/week) than those with the CT and CC genotypes (p = 0.025). The luciferase activity was significantly enhanced in the construct containing CRTH2 466C compared with the -466T-containing construct (p < 0.001). Co-transfection experiments with GATA-3 (300 ng) and the -466T and -466C CRTH2 alleles revealed that the CRTH2 -466T allele produced a greater increase in induction of luciferase activity than the -466C allele (p < 0.001).

CONCLUSION

The CRTH2 -466T>C gene polymorphism may not affect on the phenotype of CU, but contributes to the required dose of antihistamines in patients with CU.

Granule formation in NGF-cultured mast cells is associated with expressions of pyruvate kinase type M2 and annexin I proteins

BACKGROUND

Nerve growth factor (NGF) is a potent mediator, which regulates characteristics of mast cells, but its biological function is not well characterized. This study aimed to screen proteins associated with the maturation of human mast cells-1 (HMC-1) or mouse bone marrow-derived mast cells (BMMCs) cultured with NGF, and to examine the functions of proteins involved.

METHODS

NGF (10 ng/ml) was added to cell culture medium every other day for 10 days for HMC-1 or twice a week for 5 weeks for BMMCs. Granule formation was determined by electron microscopy or May-Grunwald-Giemsa staining, TNF-alpha by ELISA, expressions of various proteins by two-dimensional gel electrophoresis (2-DE), siRNA transfection by Lipofectamine 2000, and the expressions of pyruvate kinase and annexin I by immunoblotting.

RESULTS

After NGF treatment, granule formation and total amounts of granular mediator, TNF-alpha increased in both mast cells. This TNF-alpha was released by calcium ionophore or by antigen/antibody reaction. Expressions of pyruvate kinase and annexin I obtained by 2-DE were confirmed by immunoblotting and siRNA-transfected HMC-1 cells. Expressions of proteins, granule formation and TNF-alpha content were blocked by both the TrkA inhibitor, K252a, and the ERK inhibitor, PD98059, but not by the PI3 kinase inhibitors, LY294002 and wortmannin.

CONCLUSION

These data suggest that pyruvate kinase and annexin I expressed by NGF contribute to granule formation containing TNF-alpha as well as other mediators in mast cells, which play a major role in allergic diseases via a TrkA/ERK pathway.

An improved LC-MS/MS method for the quantification of prostaglandins E(2) and D(2) production in biological fluids

We report an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay that accurately measures prostaglandins D(2) (PGD(2)) and E(2) (PGE(2)) in cell culture supernatants and other biological fluids. The limit of detection for each prostaglandin was 20 pg/ml (0.20 pg, 0.55 fmol on-column), and the interday and intraday coefficients of variation were less than 5%. Both d(4)-PGE(2) and d(4)-PGD(2) were used as surrogate standards to control for differential loss and degradation of the analytes. Stability studies indicated that sample preparation time should be less than 8h to measure PGD(2) accurately, whereas preparation time did not affect PGE(2) measurement due to its greater stability in biological samples. As an application of the method, PGD(2) and PGE(2) were measured in culture supernatants from A549 cells and RAW 264.7 cells. The human lung alveolar cell line A549 was found to produce PGE(2) but no PGD(2), whereas the murine macrophage cell line RAW 264.7 produced PGD(2) and only trace amounts of PGE(2). This direct comparison showed that COX-2 gene expression can lead to differential production of PGD(2) and PGE(2) by epithelial cells and macrophages. Because PGE(2) is antiasthmatic and PGD(2) is proasthmatic, we speculate that the balance of production of these eicosanoids by epithelial cells and macrophages in the lung contributes to the pathogenesis of chronic obstructive pulmonary disease (COPD), bronchiectasis, asthma, and lung cancer.

Anti-IgE antibodies for the treatment of IgE-mediated allergic diseases

The pharmacological purposes of the anti-IgE therapy are to neutralize IgE and to inhibit its production to attenuate type I hypersensitivity reactions. The therapy is based on humanized IgG1 antibodies that bind to free IgE and to membrane-bound IgE on B cells, but not to IgE bound by the high-affinity IgE.Fc receptors on basophils and mast cells or by the low-affinity IgE.Fc receptors on B cells. After nearly 20 years since inception, therapeutic anti-IgE antibodies (anti-IgE) have been studied in about 30 Phase II and III clinical trials in many allergy indications, and a lead antibody, omalizumab, has been approved for treating patients (12 years and older) with moderate-to-severe allergic asthma. Anti-IgE has confirmed the roles of IgE in the pathogenesis of asthma and helped define the concept "allergic asthma" in clinical practice. It has been shown to be safe and efficacious in treating pediatric allergic asthma and treating allergic rhinitis and is being investigated for treating peanut allergy, atopic dermatitis, latex allergy, and others. It has potential for use to combine with specific and rush immunotherapy for increased safety and efficacy. Anti-IgE thus appears to provide a prophylactic and therapeutic option for moderate to severe cases of many allergic diseases and conditions in which IgE plays a significant role. This chapter reviews the evolution of the anti-IgE concept and the clinical studies of anti-IgE on various disease indications, and presents a comprehensive analysis on the multiple intricate immunoregulatory pharmacological effects of anti-IgE. Finally, it reviews other approaches that target IgE or IgE-expressing B cells.

Clara cell 16-kd protein downregulates T(H)2 differentiation of human naive neonatal T cells

BACKGROUND

Levels of the Clara cell 16-kd protein (CC16) are lower in plasma and bronchoalveolar lavage fluid from adults with asthma relative to those seen in healthy control subjects, and CC16 inhibits the T(H)2 cytokine production from murine T cells.

OBJECTIVE

We sought to determine the plasma levels of CC16 in infants and to investigate whether CC16 might inhibit the T(H)2 cytokine production from neonatal T cells.

METHODS

Cord blood and blood samples at 4, 18, and 36 months of age were taken from 64 children prospectively, and CC16 levels were analyzed in plasma. Cord monocyte-derived dendritic cells (DCs) were pulsed with birch allergen extract alone or together with CC16 or prostaglandin D(2) receptor inhibitors, after which autologous naive CD4(+) T cells were added to the DCs. The production of IL-5, IL-13, and IFN-gamma was measured by means of ELISA and flow cytometry.

RESULTS

The plasma levels of CC16 in children peaked at 4 months. CC16 did not directly affect the cytokine production from human T(H)2 cells. However, CC16 inhibited birch pollen extract-stimulated T(H)2 differentiation of naive T cells through the DC. Inhibition of the prostaglandin D(2) receptors did not consistently result in suppressed T(H)2 differentiation.

CONCLUSION

The production of CC16 seems to peak early in life, and CC16 has an inhibitory effect on T(H)2 cell differentiation from human infants by affecting DCs.

CLINICAL IMPLICATIONS

CC16 is an immunoregulatory protein, and its inhibitory effect on T(H)2 cell differentiation might be of importance in the pathogenesis of allergy in infants.

The role of allergic rhinitis in the development of otitis media with effusion: effect on eustachian tube function

PURPOSE

The pathogenesis of otitis media with effusion (OME) is considered multifactorial, with viral upper respiratory tract infection and eustachian tube dysfunction. Allergy may be related to the pathogenesis of OME or to another etiological factor. We investigated the role of allergic rhinitis (AR) in children with OME and evaluated eustachian tube function in patients with AR.

MATERIALS AND METHODS

We prospectively analyzed the prevalence of AR, serum eosinophil count, and serum total IgE concentrations in 123 children with OME and in 141 controls. IgE concentration in middle ear effusion was compared in children with OME with and without AR, and eustachian tube function after a nasal provocation test was compared between patients with AR and controls.

RESULTS

The prevalence of AR in children with OME (28.4%) and control subjects (24.1%) did not differ significantly. These 2 groups also showed no differences in total eosinophil count and serum and middle ear effusion IgE concentration. Abnormalities in eustachian tube function were the same in patients with AR and controls.

CONCLUSIONS

Allergic rhinitis may not be related to the development of OME in children.

Identification and evaluation of antioxidant, analgesic/anti-inflammatory activity of the most active ninhydrin–phenol adducts synthesized

Treatment of phenols with ninhydrin in acidic medium afforded 2-hydroxy-2-(ortho-hydroxy-phenyl/naphthyl)-1,3-dioxoindanes, which being unstable were isolated in their hemiketal forms. These synthesized compounds were subjected to TLC screening for radical scavenging and in vitro lipoxgenase and cycloxygenase enzyme inhibition assays. The best compound was identified and studied in detail for steady-state and time-resolved free radical kinetics, viz., DPPH, ABTS(-), *OH and rate constants for these reactions were evaluated. The best compound was also subjected to in vivo anti-inflammatory and analgesic activities in which the compound showed good promise for further structural optimization.

Mast cells are required for normal healing of skin wounds in mice

Mast cells (MCs) have recently been reported to play a pivotal role in the elicitation of inflammatory reactions that are beneficial to the host, e.g., during innate immune responses to bacteria. To explore whether MCs also contribute to wound repair, we studied experimentally induced skin wounds in MC-deficient Kit(W)/Kit(W-v) mice, normal Kit+/+ mice, and MC-reconstituted Kit(W)/Kit(W-v) mice. Wound closure was significantly impaired in the absence of MCs during the first 6 days of wound healing and histomorphometric analyses of MC degranulation at the wound edges revealed distance-dependent MC activation, i.e., MC degranulation was most prominent directly adjacent to the wound. In addition, Kit(W)/Kit(W-v) mice showed impaired extravasation and recruitment of neutrophils to the wounded areas. Notably, wound closure, extravasation, and neutrophil recruitment were found to be normal in MC-reconstituted Kit(W)/Kit(W-v) mice. Therefore, we examined whether MCs promote wound healing by releasing histamine or TNF-alpha. Interestingly, wound closure was reduced in mice treated with an H1-receptor antagonist but not after treatment with an H2-receptor antagonist or in the absence of TNF-alpha. Taken together, our findings indicate that MC activation and histamine release are required for normal cutaneous wound healing.

The Anti-inflammatory and Anti-nociceptive Effects of Ethyl Acetate Fraction of Cynanchi Paniculati Radix

The anti-inflammatory and anti-nociceptive effects and sedative activities of the ethyl acetate fraction of Cynanchum paniculatum (EACP) were evaluated in mice and rats by acetic acid-induced vascular permeability, arachidonic acid-induced paw edema, cotton pellet-induced granuloma formation, formalin-induced licking time, acetic acid-induced writhing response, and pentobarbital-induced sleeping time. EACP at a dose of 40 mg/kg significantly exhibited anti-inflammatory activities on acetic acid-induced vascular permeability, arachidonic acid-induced paw edema, and the late phase of formalin-induced licking time. Moreover, it showed anti-nociceptive effects on acetic acid-induced writhing responses and significant sedative effects on pentobarbital-induced sleeping time. The results demonstrated that the anti-nociceptive effects are apparently related to the sedative effects of EACP. These results support the use of Cynanchum paniculatum in relieving inflammatory pain.

Prostaglandin D2 Induces Chemotaxis in Eosinophils Via Its Receptor CRTH2 and Eosinophils May Cause Severe Ocular Inflammation in Patients With Allergic Conjunctivitis

PURPOSE

Eosinophils are known to have important roles in the pathogenesis of allergic conjunctivitis. Prostaglandin (PG) D2, which has been implicated as a factor in allergic diseases, is known to have chemotactic activity for eosinophils. Its receptor, chemoattractant receptor homologous molecule expressed on TH2 (CRTH2), serves as a receptor for PGD2 and has been reported to mediate PGD2-dependent migration of eosinophils. In the present study, both eosinophil toxic activity for corneal epithelial cells and chemotaxis induced by PGD2 in normal volunteers were investigated. Expression of CRTH2 in normal subjects was also measured.

METHODS

Primary cultured corneal epithelial cells and eosinophils in serum from normal volunteers were used and a human corneal epithelial cell line was established. Studies were performed with/without amniotic membrane. CRTH2 expression on eosinophils was assessed by flow cytometry. Chemotaxis experiments were performed using a modified Boyden chamber technique.

RESULTS

Corneal epithelial cells cultured with eosinophils showed higher floating epithelial cells and epithelial defect than those cultured in the absence of eosinophils. Flow cytometry analysis revealed that eosinophils expressed CRTH2. PGD2 induced chemotaxis of eosinophils.

CONCLUSIONS

Corneal epithelial damage might be caused by eosinophils, which are recruited by PGD2 secretion via CRTH2 expressed on eosinophils.

New approaches in immunotherapy: allergen vaccination with immunostimulatory DNA

Despite its success, conventional immunotherapy is saddled with a number of encumbrances. An allergenic vaccine that could reduce allergenicity, maintain immunogenicity, and be given in a few doses would have important therapeutic implications, as millions of patients with poorly controlled allergic rhinitis and asthma would be candidates for such a form of immunomodulation. This article addresses a specific adjuvant approach to immunotherapy in which highly active immunostimulatory phosphorothioate oligodeoxyribonucleotide moieties are linked to the principal allergenic moiety of a relevant aeroallergen.

Cyclooxygenase isozymes: the biology of prostaglandin synthesis and inhibition

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most highly utilized classes of pharmaceutical agents in medicine. All NSAIDs act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective drugs. These pharmaceutical agents have quickly become established as important therapeutic medications with potentially fewer side effects than traditional NSAIDs. Additionally, characterization of the two COX isozymes is allowing the discrimination of the roles each play in physiological processes such as homeostatic maintenance of the gastrointestinal tract, renal function, blood clotting, embryonic implantation, parturition, pain, and fever. Of particular importance has been the investigation of COX-1 and -2 isozymic functions in cancer, dysregulation of inflammation, and Alzheimer's disease. More recently, additional heterogeneity in COX-related proteins has been described, with the finding of variants of COX-1 and COX-2 enzymes. These variants may function in tissue-specific physiological and pathophysiological processes and may represent important new targets for drug therapy.

The significance of vasoactive intestinal peptide in immunomodulation

First identified by Said and Mutt some 30 years ago, the vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator peptide. Subsequently, its biochemistry was elucidated, and within the 1st decade, their signature features as a neuropeptide became consolidated. It did not take long for these insights to permeate the field of immunology, out of which surprising new attributes for VIP were found in the last years. VIP is rapidly transforming into something more than a mere hormone. In evolving scientifically from a hormone to a novel agent for modifying immune function and possibly a cytokine-like molecule, VIP research has engaged many physiologists, molecular biologists, biochemists, endocrinologists, and pharmacologists and it is a paradigm to explore mutual interactions between neural and neuroendocrine links in health and disease. The aim of this review is firstly to update our knowledge of the cellular and molecular events relevant to VIP function on the immune system and secondly to gather together recent data that support its role as a type 2 cytokine. Recognition of the central functions VIP plays in cellular processes is focusing our attention on this "very important peptide" as exciting new candidates for therapeutic intervention and drug development.

Anti-inflammatory activity of methanolic extracts from Ventilago harmandiana Pierre

Methanolic extracts from the heart wood, stem bark, and stem wood of Ventilago harmandiana Pierre (Family Rhamnaceae) were assessed for anti-inflammatory effects using both acute and chronic inflammatory models. Analgesic and antipyretic activities of the extracts were also evaluated. It was found that all extracts possessed strong inhibitory effects on the acute phase of inflammation as seen in ethyl phenylpropiolate (EPP)- and arachidonic acid (AA)-induced ear edema as well as in carrageenin-induced paw edema in rats. The extracts elicited only weak inhibitory activity on cotton pellet-induced granuloma formation, a subchronic inflammatory model. In the analgesic test, all extracts exerted pronounced inhibitory activity in acetic acid-induced writhing response but showed only weak effects in the tail-flick test. The extracts also showed excellent antipyretic activity on yeast-induced hyperthermia in rats.

Chemoattractant receptor-homologous molecule expressed on Th2 cells activation in vivo increases blood leukocyte counts and its blockade abrogates 13,14-dihydro-15-keto-prostaglandin D2-induced eosinophilia in rats

We cloned, expressed, and characterized in vitro and in vivo the gene encoding the rat ortholog of chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2), a G protein-coupled receptor for prostaglandin D2 (PGD2). Quantitative reverse transcription-polymerase chain reaction analysis demonstrated highest CRTH2 expression in the lung, brain, ovary, and spleen. Pharmacologically, rat CRTH2 stably transfected in mouse preB lymphoma L1.2 cells behaved very similar compared with the mouse and human orthologs, showing a binding affinity for PGD2 of 11 nM, a functional calcium mobilization when exposed to agonist, and similar sensitivity to agonists and antagonists. In vivo, selective activation of CRTH2 by 13,14-dihydro-15-keto (DK)-PGD2 injection into rats led to a dose- and time-dependent increase of the number of leukocytes in the peripheral blood. Specifically, eosinophils, lymphocytes, and neutrophils were recruited with maximum effects seen 60 min after the injection of 300 microg of DK-PGD2 per rat. Pretreatment of the animals with the CRTH2/thromboxane A2 receptor antagonist, ramatroban, completely abrogated DK-PGD2-induced eosinophilia, suggesting that CRTH2 might have a physiological and/or pathophysiological role in controlling leukocyte migration.

Prostaglandin D2 affects the maturation of human monocyte-derived dendritic cells: consequence on the polarization of naive Th cells

Among the factors produced at inflammatory sites and those capable of modulating dendritic cell (DC) functions, PGD(2) may be important in the outcome of immune responses. The biological roles for PGD(2) are in part effected through two plasma membrane G protein-coupled receptors: the D prostanoid (DP) receptor and the chemoattractant receptor-homologous molecule expressed on Th2 lymphocytes (CRTH2). In this report, we studied the effects of PGD(2) and of its major physiological metabolite, 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), on the functions of human monocyte-derived DC. First, we show that PGD(2) exerts in vitro chemotactic effects on monocytes via CRTH2 activation while it inhibits the chemokine-driven migration of monocyte-derived DC through DP. We also report that PGD(2) and 15d-PGJ(2) alter the LPS- and allergen-induced DC maturation and enhance the CD80/CD86 ratio on mature DC in a DP- and CRTH2-independent manner. Moreover, PGD(2) and 15d-PGJ(2) strongly reduce the secretion of the Th1 promoting cytokine IL-12 and affect the synthesis of chemokines involved in Th1 cell chemotaxis, particularly CXCL10. Inhibition of cytokine/chemokine secretion implicates at least in part DP, but not CRTH2. The effects exerted by PGD(2) are associated with the phosphorylation of CREB, but do not parallel with the deactivation of the NF-kappa B and mitogen-activated protein kinase pathways. In contrast, 15d-PGJ(2) seems to target other cellular proteins. Finally, in a model of Th CD45RA(+) differentiation induced by allergen- and superantigen-pulsed DC, PGD(2) impacts on the orientation of the immune response by favoring a Th2 response.

Down-regulation of vasoactive intestinal polypeptide receptor expression in atopic dermatitis

BACKGROUND

Receptors for vasoactive intestinal polypeptide (VIP) have recently been suggested to play a key role in immunomodulation with genetically modified mice. However, it is not known whether changes in receptor gene regulation are involved in the pathogenesis of human immune disorders.

OBJECTIVE

We studied the expression of VPAC(2) in acute lesions of the human immune disease atopic dermatitis.

METHODS

By using nonradioactive in situ hybridization, quantitative immunohistochemistry, RT-PCR, and gene array studies, the expression status of VPAC(2) was assessed in atopic dermatitis and control tissues and in the human mast cell line HMC-1.

RESULTS

In situ hybridization and immunohistochemistry demonstrated VPAC(2) mRNA and protein expression in human mast cells surrounded by VIP positive nerve fibers. Gene array experiments and RT-PCR studies showed high levels of VPAC(2) mRNA expression in mast cells that were increased compared to other receptors such as VPAC(1) or VIP in the human mast cell line HMC-1. Stimulation of HMC-1 cells led to a downregulation of VPAC(2). Similarly, quantitative immunohistochemistry for VPAC(2) in acute atopic dermatitis lesions showed a significantly decreased VPAC(2) immunoreactivity in mast cells.

CONCLUSION

The downregulation of VPAC(2) in human mast cells in acute lesions of atopic dermatitis suggests a role of this G-protein;coupled receptor in the pathophysiology of the disease.

Function of prostanoid receptors: studies on knockout mice

Prostanoids consisting of the prostaglandins (PGs) and the thromboxanes (TXs) are the cyclooxygenase metabolites of arachidonic acid. They exert a range of actions mediated by their respective receptors expressed in the target cells. The receptors include the DP, EP, FP, IP and TP receptors for PGD, PGE, PGF, PGI and TXA, respectively. Furthermore, EP is subdivided into four subtypes, EP1, EP2, EP3 and EP4, which are encoded by different genes and differ in their responses to various agonists and antagonists. Recent developments in the molecular biology of the prostanoid receptors have enabled the investigation of physiological roles of each receptor by disruption of the respective gene. At this point, all the eight types and subtypes of the prostanoid receptors have been individually knocked out in mice, and various phenotypes have been reported for each strain. Here, we review the findings obtained in these studies. The results from these knockout mice studies may be useful in the development of novel therapeutics that can selectively manipulate actions mediated by each receptor.

Nutrient partitioning between reproductive and immune functions in animals

The physiological processes that underlie the reproductive cycle impose considerable metabolisable protein (MP) demands on a female, especially during the periparturient period. When MP supply falls short of MP demand (i.e. MP becomes scarce), certain, if not all, bodily functions are expected to be penalised. It has been proposed that partitioning of scarce MP is prioritised to reproductive rather than to immune functions. In other words, at times of MP scarcity, the penalty on expression of immunity would be expected to be greater than that on reproduction. This hypothesis forms a nutritional basis for the occurrence of periparturient breakdown of immunity to parasites (BIP), which can be observed in many host-parasite systems. In the present review we explore this nutritional basis, using periparturient sheep infected with the abomasal nematode Teladorsagia circumcincta as an example, and attempt to quantify its occurrence. Evidence supporting the nutritional basis of periparturient BIP is reviewed, covering experiments in which nutrient supply (from both exogenous and endogenous sources) and/or nutrient demand were manipulated. Quantitatively, MP requirements for expression of immunity to T. circumcincta were estimated to be about 1 g/kg metabolic body weight (body weight 0.75) per d, approximately 5% of the maximum MP requirements of periparturient sheep. The major component of this requirement was assumed to be for replenishing irreversible plasma protein losses into the gastrointestinal tract. Although confirmation of this estimate is required, such estimates may be used to improve the known MP requirements of periparturient animals, enabling the extent and the consequences of periparturient BIP to be minimised.

Efficacy of leukotriene receptor antagonist in chronic urticaria. A double-blind, placebo-controlled comparison of treatment with montelukast and cetirizine in patients with chronic urticaria with intolerance to food additive and/or acetylsalicylic acid

BACKGROUND

The cause and pathogenesis of chronic urticaria are still poorly understood. IgE-independent reactions, are common in adult patients with chronic urticaria, who have daily spontaneous occurrence of weals. H(1)-receptor antagonists (antihistamines) are the major class of therapeutic agents used in the management of urticaria and angioedema. Nevertheless, chronic urticaria is often difficult to treat and may not be controlled by antihistamines alone. It has been postulated that mediators other than histamine, such as kinins, prostaglandin and leukotrienes, may be responsible for some of the symptoms in urticaria which are not controlled by antihistamines. In this study, which was randomized double-blind, placebo-controlled, we compare the clinical efficacy and safety of montelukast (MT) 10 mg given once a day and cetirizine (CET) 10 mg given once a day with placebo (PLA), in the treatment of patients with chronic urticaria who have positive challenge to acetylsalicylic acid (ASA) and/or food additives.

PATIENTS AND METHODS

A group of 51 patients, ranging in age from 15 to 71 years, with chronic urticaria and positive challenge to food additives and/or ASA, participated in this study for a period of 4 weeks, starting from a 3-day run-in. The assessment of the efficacy was based on scores of daily urticaria symptoms.

RESULTS

MT significantly increased the percentage of symptom-free days for hive and itch. Analysis of frequency distribution of urticaria scores for each symptom gave similar results (MT vs. CET and MT vs. PLA, P < 0.001). The interference with sleep due to their skin condition was also lower in the group treated with MT (P < 0.001). In addition, the median number of days without the rescue medication was significantly higher in the MT group (24 days) than both the CET and the PLA groups (18 days, P < 0.001, and 20 days, P < 0.001, respectively). Finally, a low incidence of adverse events was observed in this study.

CONCLUSION

The results of this comparative study demonstrate that montelukast orally administered once a day is very effective for the treatment of cutaneous symptoms in patients with chronic urticaria due to food additives and/or ASA.

Clinical and histological evaluation of an analogue of palmitoylethanolamide, PLR 120 (comicronized Palmidrol INN) in cats with eosinophilic granuloma and eosinophilic plaque: a pilot study

Fifteen cats with eosinophilic granuloma or eosinophilic plaque were given PLR 120 at the dosage of 10 mg kg-1 twice daily for one month. PLR-120 down-modulates mast cell degranulation via a receptor-mediated mechanism. No other drugs were permitted and cats were kept free of parasites throughout the study. A clinical evaluation and skin biopsies were performed before and after the treatment. Clinical improvement was assessed at 15 and 30 days. Mast cell numbers were counted and their granular content was assessed by densitometric analysis on toluidine blue-stained sections before and after the treatment. Ten of 15 (67%) cats showed clinical improvement of signs and lesions. There was no significant difference between mast cell numbers in skin biopsies taken before and after the trial, whereas the number of granules was significantly increased (P < 0.009). This pilot study suggests that PLR-120 might be a useful drug for the treatment of eosinophilic granuloma and eosinophilic plaque.

New bis-catechols 5-lipoxygenase inhibitors

Three polyhydroxy-2-phenylnaphthalenes (1-3) and the oxy analogue of tetrahydroxypavinan (4) were prepared and evaluated for their antioxidant properties (inhibition of diphenylpycrylhydrazyl radical (DPPH), reduction of iron (III) ion) and inhibition of 5-lipoxygenase (5-LO) activity. Their three-dimensional structures were established on the basis of spectroscopic data and semiempirical calculations. Compounds 1 and 2 were found as potent 5-LO inhibitors as nordihydroguaiaretic acid (NDGA), whereas 4 is 2.5 times less potent than NDGA. The reliability of the 3-D structures with the 5-LO inhibition properties is discussed. Their antioxidant properties show that tested compounds are expected to act as redox inhibitors.

Correlation between cytosolic calcium concentration and degranulation in RBL-2H3 cells in the presence of various concentrations of antigen-specific IgEs

We studied the dependence of beta-hexosaminidase release from RBL-2H3 cells on the antigen-specific IgE concentrations. The cells were sensitized with DNP-specific IgE (0.5-5000 ng/ml) or OVA-specific IgE (5-50 ng/ml) and stimulated with DNP(35)-HSA (10(-2)-100 ng/ml) or OVA (10(-1) ng/ml-10 microg/ml). It was found that the beta-hexosaminidase release increased in a dose-dependent manner with the concentration of the IgEs and antigens added to the mast-cell suspension. We also studied the correlation between the intracellular calcium concentration ([Ca(2+)]i) and degranulation in RBL-2H3 cells. The percentage of beta-hexosaminidase release from the cells was well correlated with [Ca(2+)](i) increase, and the correlation coefficient was 0.88 for DNP-specific IgE and 0.99 for OVA-specific IgE. The minimum [Ca(2+)](i) required to induce the beta-hexosaminidase release was 100 nM for DNP-specific IgE, and 70 nM for OVA-specific IgE. Therefore, the [Ca(2+)](i) monitoring system is a sensitive marker of degranulation from RBL-2H3 cells and can be used to measure even low amounts of antigen-specific IgE.