Late-phase Inflammatory Response Research Articles

Guideline on the investigation and management of acute transfusion reactions.

Guideline on the investigation and management of acute transfusion reactions.

Agarose/crystalline nanocellulose (CNC) composites promote bone marrow-derived mast cell integrity, degranulation and receptor expression but inhibit production of de novo synthesized mediators.

Introduction: Mast cells are highly granulated tissue-resident leukocytes that require a three-dimensional matrix to differentiate and mediate immune responses. However, almost all cultured mast cells rely on two-dimensional suspension or adherent cell culture systems, which do not adequately reflect the complex structure that these cells require for optimal function. Methods: Crystalline nanocellulose (CNC), consisting of rod-like crystals 4-15nm in diameter and 0.2-1µm in length, were dispersed in an agarose matrix (12.5% w/v), and bone marrow derived mouse mast cells (BMMC) were cultured on the agarose/CNC composite. BMMC were activated with the calcium ionophore A23187 or immunoglobulin E (IgE) and antigen (Ag) to crosslink high affinity IgE receptors (FcεRI). Results: BMMC cultured on a CNC/agarose matrix remained viable and metabolically active as measured by reduction of sodium 3'-[1-[(phenylamino)-carbony]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT), and the cells maintained their membrane integrity as analyzed by measuring the release of lactate dehydrogenase (LDH) and propidium iodide exclusion by flow cytometry. Culture on CNC/agarose matrix had no effect on BMMC degranulation in response to IgE/Ag or A23187. However, culture of BMMC on a CNC/agarose matrix inhibited A23187-and IgE/Ag-activated production of tumor necrosis factor (TNF) and other mediators such as IL-1β, IL-4, IL-6, IL-13, MCP-1/CCL2, MMP-9 and RANTES by as much as 95%. RNAseq analysis indicated that BMMC expressed a unique and balanced transcriptome when cultured on CNC/agarose. Discussion: These data demonstrate that culture of BMMCs on a CNC/agarose matrix promotes cell integrity, maintains expression of surface biomarkers such as FcεRI and KIT and preserves the ability of BMMC to release pre-stored mediators in response to IgE/Ag and A23187. However, culture of BMMC on CNC/agarose matrix inhibits BMMC production of de novo synthesized mediators, suggesting that CNC may be altering specific phenotypic characteristics of these cells that are associated with late phase inflammatory responses.

Antigen- and Epitope-Delivering Nanoparticles Targeting Liver Induce Comparable Immunotolerance in Allergic Airway Disease and Anaphylaxis as Nanoparticle-Delivering Pharmaceuticals

The targeting of natural tolerogenic liver sinusoidal endothelial cells (LSEC) by nanoparticles (NPs), decorated with a stabilin receptor ligand, is capable of generating regulatory T-cells (Tregs), which can suppress antigen-specific immune responses, including to ovalbumin (OVA), a possible food allergen. In this regard, we have previously demonstrated that OVA-encapsulating poly(lactic-co-glycolic acid) (PLGA) nanoparticles eliminate allergic airway inflammation in OVA-sensitized mice, prophylactically and therapeutically. A competing approach is a nanocarrier platform that incorporates pharmaceutical agents interfering in mTOR (rapamycin) or NF-κB (curcumin) pathways, with the ability to induce a tolerogenic state in nontargeted antigen-presenting cells system-wide. First, we compared OVA-encapsulating, LSEC-targeting tolerogenic nanoparticles (TNPs) with nontargeted NPs incorporating curcumin and rapamycin (Rapa) in a murine eosinophilic airway inflammation model, which is Treg-sensitive. This demonstrated roughly similar tolerogenic effects on allergic airway inflammation by stabilin-targeting NPOVA versus nontargeted NPs delivering OVA plus Rapa. Reduction in eosinophilic inflammation and TH2-mediated immune responses in the lung was accompanied by increased Foxp3+ Treg recruitment and TGF-β production in both platforms. As OVA incorporates IgE-binding as well as non-IgE-binding epitopes, the next experiment explored the possibility of obtaining immune tolerance by non-anaphylactic T-cell epitopes. This was accomplished by incorporating OVA323-339 and OVA257-264 epitopes in liver-targeting NPs to assess the prophylactic and therapeutic impact on allergic inflammation in transgenic OT-II mice. Importantly, we demonstrated that the major histocompatibility complex (MHC)-II binding (former) but not the MHC-I binding (latter) epitope interfered in allergic airway inflammation, improving TNPOVA efficacy. The epitope-specific effect was transduced by TGF-β-producing Tregs. In the final phase of experimentation, we used an OVA-induced anaphylaxis model to demonstrate that targeted delivery of OVA and its MHC-II epitope could significantly suppress the anaphylaxis symptom score, mast cell release, and the late-phase inflammatory response. In summary, these results demonstrate comparable efficacy of LSEC-targeting versus pharmaceutical PLGA nanoparticles, as well as the ability of T-cell epitopes to achieve response outcomes similar to those of the intact allergens.

Rupatadine Does Not Affect Atherosclerosis Development In Apoe-Ko Mice

Background and Aims: Rupatadine is an N-alkyl pyridine derivative with anti-inflammatory properties through the inhibition of a range of mediators involved in the early-to late-phase inflammatory response. Rupatadine mainly acts through the histamine H1 receptor, exerting potent anti-inflammatory effects at concentrations in the nanomolar range. In addition, this anti-inflammatory activity is strengthened by its antagonist activity towards PAF. For its strong anti-inflammatory properties, rupatadine may display a positive effect against atherosclerosis development.

Vesicular trafficking and signaling for cytokine and chemokine secretion in mast cells.

Upon activation mast cells (MCs) secrete numerous inflammatory compounds stored in their cytoplasmic secretory granules by a process called anaphylactic degranulation, which is responsible for type I hypersensitivity responses. Prestored mediators include histamine and MC proteases but also some cytokines and growth factors making them available within minutes for a maximal biological effect. Degranulation is followed by the de novo synthesis of lipid mediators such as prostaglandins and leukotrienes as well as a vast array of cytokines, chemokines, and growth factors, which are responsible for late phase inflammatory responses. While lipid mediators diffuse freely out of the cell through lipid bilayers, both anaphylactic degranulation and secretion of cytokines, chemokines, and growth factors depends on highly regulated vesicular trafficking steps that occur along the secretory pathway starting with the translocation of proteins to the endoplasmic reticulum. Vesicular trafficking in MCs also intersects with endocytic routes, notably to form specialized cytoplasmic granules called secretory lysosomes. Some of the mediators like histamine reach granules via specific vesicular monoamine transporters directly from the cytoplasm. In this review, we try to summarize the available data on granule biogenesis and signaling events that coordinate the complex steps that lead to the release of the inflammatory mediators from the various vesicular carriers in MCs.

Late-phase inflammatory response as a feature of in-stent restenosis after drug-eluting stent implantation

The aim of this study was to compare pathological features among in-stent restenosis lesions after drug-eluting stent (DES) placement, those after bare metal stent (BMS) placement, and de-novo atherosclerotic lesions. Restenosis after stenting is an over-reaction of the wound-healing response after vascular injury, which is characterized by a sequence of inflammation, granulation, extracellular matrix remodeling, and smooth muscle cell proliferation and migration. Recent advances in DES technology could considerably succeed in inhibiting this sequence of events. Thus, we hypothesized that the mechanism of in-stent restenosis after DES stenting might be different from that after BMS stenting as well as atherosclerosis. Tissues obtained by directional atherectomy (DES: seven specimens, BMS: 17 specimens, and de-novo: 15 specimens) were immunostained for T lymphocytes (CD45), macrophages (CD68), smooth muscle cells (α-smooth muscle actin), endothelial cells (von Willebrand factor), and activated platelets (P-selectin). The accumulation of T lymphocytes tended to increase and that of macrophages increased significantly in the DES lesions compared with BMS lesions. No significant differences were observed for the other parameters evaluated. Pathological features of restenotic tissues after DES implantation showed a stronger inflammatory response compared with those after BMS implantation. Thus, the mechanism of restenosis after DES implantation may be different from that observed after BMS implantation.

The late-phase inflammatory response after drug-eluting stent implantation

Recent advances in drug-eluting stent (DES) technology have succeeded in preventing restenosis. In addition to inhibiting smooth muscle cell proliferation, DES greatly inhibits the local inflammatory response in the acute phase after implantation, leading to prevention of restenosis. However, a unique issue in DES implantation is an impairment of reendothelialization, which may result in abnormal wound healing. Consequently, a late-phase inflammatory relapse could appear in the long term after DES implantation. In this study, we measured serum levels of inflammatory markers, including interleukin (IL)-6, IL-8, tumor necrosis factor-α, monocyte chemoattractant protein-1, matrix metalloproteinase-9, and myeloperoxidase, as well as high-sensitivity C-reactive protein at follow-up coronary angiography (mean 9 months) in 54 patients who received DES stenting who did not experience restenosis, and compared them with 51 patients receiving bare-metal stents (BMS) without restenosis. The level of IL-6 was over the measurement threshold (≥2.22 pg/ml) in 12 patients (21 %) in the DES group, but in only 2 patients (4 %) in the BMS group (P = 0.003). IL-8 was significantly higher in the DES group than in the BMS group (4.51 ± 2.40 vs 3.84 ± 1.34 pg/ml, P = 0.015). The levels of other biomarkers were similar between the two groups. DES showed an increase in inflammatory cytokines in the late phase after implantation in comparison with patients who received BMS, suggesting late-stage inflammation. Therefore, the wound-healing response after DES implantation might be different from that after BMS.

Treg cells may regulate interlukin-17 production by modulating TH1 responses in 1,3-β-glucan-induced lung inflammation in mice

1,3-β-glucan is considered a fungal biomarker and exposure to this agent can induce lung inflammation. Complement activation plays an important role in early immune responses to β-glucan. Previous studies showed that T-regulatory cells (Tregs) regulated 1,3-β-glucan-induced lung inflammation by modulating the maintenance of immune homeostasis in the lung. Both interleukin (IL)-17 and TH17 cells play pivotal roles in inflammation associated with lung disease and share reciprocal developmental pathways with Tregs. However, the effect of Tregs on IL-17 and TH17 responses in 1,3-β-glucan-induced lung inflammation remains unclear. In this study, mice were exposed to 1,3-β-glucan by intratracheal instillation. To investigate the effects of Tregs on IL-17 and TH17 cells in the induced lung inflammation, a Treg-depleted mice model was generated by administration of anti-CD25 mAb. The results indicated that Treg-depleted mice showed more severe pathological inflammatory changes in lung tissues. Tregs depletion reduced IL-17 expression in these tissues, and increased those of TH1 cytokines. The expression of IL-17 increased at the early phase of the inflammation response. There were no significant effects of the Tregs on expression of RORγt and IL-6 or the amount of CD4+IL-17+ cells in the lungs. When taken together, the late phase of the 1,3-β-glucan-induced inflammatory response in the mice was primarily mediated by TH1 cytokines rather than IL-17. In contrast, the early phase of the inflammatory response might be mediated in part by IL-17 along with activated complement. Tregs might be required for IL-17 expression during the late phase inflammatory response in mice. The increased IL-17 mRNA observed during the 1,3-β-glucan induced inflammatory response were attributed to cells other than TH17 cells.

Allergic Airways Responses Are Associated With A Late-phase Systemic Inflammatory Response In An Environmental Allergen Challenge Model

FEBRUARY 2012 AB6 Abstracts S A T U R D A Y 21 Cord Blood Cellular Proliferative Response as a Predictive Factor For Atopic Dermatitis At 6 Months of Age H. Kim, J. Seo, H. Kim, J. Kwon, B. Kim, J. Shim, W. Kim, D. Song, S. Lee, S. Lee, G. Jang, K. Kim, K. Ahn, Y. Shin, J. Yu, M. Kang, K. Lee, S. Hong; Inje University Sanggye Paik Hospital, Seoul, REPUBLIC OF KOREA, University of Ulsan College of Medicine, Seoul, REPUBLIC OF KOREA, Seoul National University Bundang Hospital, Seongnam, REPUBLIC OF KOREA, Inje University Haeundae Paik Hospital, Pusan, REPUBLIC OF KOREA, Sungkyunkwan University School of Medicine, Seoul, REPUBLIC OF KOREA, Inje University Seoul Paik Hospital, Seoul, REPUBLIC OF KOREA, College of Medicine, Korea University, Seoul, REPUBLIC OF KOREA, Hallym University College of Medicine, Seoul, REPUBLIC OF KOREA, Ajou University School of Medicine, Suwon, REPUBLIC OF KOREA, National Health Insurance Corporation Ilsan Hospital, Ilsan, REPUBLIC OF KOREA, Yonsei University, Seoul, REPUBLIC OF KOREA, CHA University School of Medicine, Seoul, REPUBLIC OF KOREA. RATIONALE: When a person exposed to allergens earlier as fetal period, the risk to develop allergic diseases increase. Therefore immunologic status of fetus may be associated with the development of allergic disease. We evaluated the factors that could have an effect on the development of atopic dermatitis (AD) at 6 months with cord blood mononuclear cells (CBMCs). METHODS: We constructed Cohort for Childhood Origin of Asthma and Allergic Diseases (COCOA) in general population from 2007 and diagnosed AD by allergy specialists in 371 infants. Cord blood was collected from them and measured cell count and total IgE. When CBMCs were extracted, ovalbumin (OVA) 100 ug/mL and phytohaemagglutinin (PHA) 10 ug/mL were stimulated and cellular proliferative response (CPR) and cytokine levels (IL-13 and IFN-g) were measured. RESULTS: The risk to develop AD at 6 months is increased in boys (OR 3.04, 95% CI 1.64-5.65) and when maternal education level was high (OR 1.97, 95% CI 1.07-3.61). Parental history of AD increased the risk of AD diagnosis (OR 2.39, 95% CI 1.18-4.81). With PHA stimulation, CPR was increased in AD-diagnosed group compared to infants without AD (P50.013), but with OVA stimulation, there was no difference between the two groups (P50.180). In addition, there was no significant difference in IFN-g/IL-13 ratio to PHA stimulation. CONCLUSIONS: The independent risk factors for the development of AD at 6 months were male, high maternal education level, and parental history of AD. Increased CPR with PHA stimulation may predict the development of AD at 6 months.

Controlled Allergen Exposure in the Environmental Exposure Chamber (EEC) Results in a Late Phase Inflammatory Response Evidenced by Increased Eosinophils in the Upper Airway of Allergic Patients

Controlled Allergen Exposure in the Environmental Exposure Chamber (EEC) Results in a Late Phase Inflammatory Response Evidenced by Increased Eosinophils in the Upper Airway of Allergic Patients

Attenuated Lung Fibrosis in Interleukin 6 Knock-out Mice after C-ion Irradiation to Lung

There is a great deal of evidence that a cyclic cascade of inflammatory cytokines, together with the activation of macrophages, is initiated very early after irradiation to develop lung fibrosis in a late phase. To understand the persistent effects of cytokines, the cytokine gene of knock out or transgenic mouse is one of the useful tools. In this study, we evaluated a role of a key molecule, interleukin-6 (IL-6), in the late-phase inflammatory response and subsequent fibrotic changes after irradiation using wild-type (WT) and IL-6 knock out (IL-6 KO) mice. The mice underwent thoracic irradiation with 10 Gy of C-ion beam or sham-irradiation and were examined by histology. Immunoreactivity for IL-6 was induced at the site of bronchiolar epithelium, in pneumocytes and in monocytes by C-ion irradiation. At 24 weeks after irradiation, the infiltration of macrophages, detected by positive immunohistological staining with Mac3 antibody, was observed in alveolar spaces both in WT and IL-6 KO mice. The thickening of bronchiolar and alveolar walls exhibited in WT mice, but not KO mice, and fibrotic changes detected by Masson-Trichrome staining, were observed only in the lungs of WT mice, while it was attenuated in IL-6 KO mice. These results indicated that IL-6 might not be essential for activating macrophages in the late phase, but plays an important role for fibrotic changes of the alveolar wall after irradiation.

IL-33 Is Produced by Mast Cells and Regulates IgE-Dependent Inflammation

BackgroundIL-33 is a recently characterized IL-1 family cytokine and found to be expressed in inflammatory diseases, including severe asthma and inflammatory bowl disease. Recombinant IL-33 has been shown to enhance Th2-associated immune responses and potently increase mast cell proliferation and cytokine production. While IL-33 is constitutively expressed in endothelial and epithelial cells, where it may function as a transcriptional regulator, cellular sources of IL-33 and its role in inflammation remain unclear.Methodology/Principal FindingsHere, we identify mast cells as IL-33 producing cells. IgE/antigen activation of bone marrow-derived mast cells or a murine mast cell line (MC/9) significantly enhanced IL-33. Conversely, recombinant IL-33 directly activated mast cells to produce several cytokines including IL-4, IL-5 and IL-6 but not IL-33. We show that expression of IL-33 in response to IgE-activation required calcium and that ionomycin was sufficient to induce IL-33. In vivo, peritoneal mast cells expressed IL-33 and IL-33 levels were significantly lower within the skin of mast cell deficient mice, compared to littermate controls. Local activation of mast cells promotes edema, followed by the recruitment of inflammatory cells. We demonstrate using passive cutaneous anaphylaxis, a mast cell-dependent model, that deficiency in ST2 or antibody blockage of ST2 or IL-33 ablated the late phase inflammatory response but that the immediate phase response was unaffected. IL-33 levels in the skin were significantly elevated only during the late phase.Conclusions/SignificanceOur findings demonstrate that mast cells produce IL-33 after IgE-mediated activation and that the IL-33/ST2 pathway is critical for the progression of IgE-dependent inflammation.

Regulatory Function of CpG-Activated B Cells in Late-Phase Experimental Allergic Conjunctivitis

To determine how CpG, an immunostimulatory sequence, affects experimental allergic conjunctivitis and to determine the mechanisms of its action. Experimental allergic conjunctivitis was induced in mice to investigate the suppressive mechanism of CpG treatment. Cytokine profiling, fluorescence-activated cell sorting analyses, and adoptive transfer were used to analyze suppressive mechanisms after CpG treatment. Administration of the CpG oligonucleotide induced significant splenomegaly. Adoptive transfer of the splenocytes isolated from CpG-treated mice was able to confer resistance to allergen-induced inflammatory responses in recipient mice. CpG treatment led to a transient upregulation of IL-1ra, IL-18, IL-1alpha, and IL-12 in the spleen, draining lymph nodes, and conjunctiva. In contrast, IL-10 showed a marked and sustained induction in the inductive and effector tissues. Splenomegaly after CpG exposure was reduced in IL-10-deficient mice, indicating that IL-10 is required for immune remodeling of the spleen. Analyses of allergen-sensitized mice deficient in IL-10 exacerbated the late-phase inflammatory responses. Fluorescence-activated cell sorting analysis of the CpG-induced splenocyte subsets showed that the predominant source of IL-10 was B220(+) CD19(+) CD23(+)IgM(+)CD40(+)class II(high) follicular B cells. Adoptive transfer of IL-10-deficient B cells exacerbated eosinophilia. Transfer of an expanded population of cells after CpG treatment, including IL-10-secreting follicular B cells, protected against eosinophilia. CpG treatment provided B cell-mediated regulation of immune responses and B cell differentiation in CpG-induced immune remodeling with the use of IL-10.

Interferon‐γ limits Th1 lymphocyte adhesion to inflamed endothelium: A nitric oxide regulatory feedback mechanism

CD4(+) T helper (Th1 and Th2) cell localization to a site of inflammation is important for the development, maintenance and regulation of an immune response. The factors that regulate Th1 and Th2 cell recruitment into tissue are not fully understood. The aim of the present study was to examine the effect of different cytokine microenvironments on the recruitment of Th1 and Th2 lymphocytes into tissue. Fluorescently labelled Th1 or Th2 lymphocyte-endothelial interactions were observed via intravital microscopy of the cytokine-treated cremaster muscle. Our results show that TNF-alpha alone is sufficient to maximally recruit Th1 cells. Surprisingly, treatment with TNF-alpha + IFN-gamma significantly decreased Th1 adhesion and emigration in comparison to TNF-alpha treatment alone. The decreased adhesion of Th1 cells in response to TNF-alpha + IFN-gamma reflected a decreased ability to bind to ICAM-1 and was iNOS-dependent. This phenomenon was not observed with Th2 cells. These results suggest that IFN-gamma may play a key immunomodulatory role in the recruitment of different T lymphocyte subsets. Indeed, blockade of IFN-gamma or iNOS function during the Th1-mediated contact hypersensitivity response resulted in an acceleration and exacerbation of the late-phase inflammatory response.

Rupatadine in allergic rhinitis and chronic urticaria

Histamine is the primary mediator involved the pathophysiology of allergic rhinitis and chronic urticaria, and this explains the prominent role that histamine H(1)-receptor antagonists have in the treatment of these disorders. However, histamine is clearly not the only mediator involved in the inflammatory cascade. There is an emerging view that drugs which can inhibit a broader range of inflammatory processes may prove to be more effective in providing symptomatic relief in both allergic rhinitis and chronic urticaria. This is an important consideration of the Allergic Rhinitis and its Impact on Asthma (ARIA) initiative which provides a scientific basis for defining what are the desirable properties of an 'ideal' antihistamine. In this review of rupatadine, a newer dual inhibitor of histamine H(1)- and PAF-receptors, we evaluate the evidence for a mechanism of action which includes anti-inflammatory effects in addition to a powerful inhibition of H(1)- and PAF-receptors. We assess this in relation to the clinical efficacy (particularly the speed of onset of action) and safety of rupatadine, and importantly its longer term utility in everyday life. In clinical trials, rupatadine has been shown to be an effective and well-tolerated treatment for allergic rhinitis and chronic idiopathic urticaria (CIU). It has a fast onset of action, producing rapid symptomatic relief, and it also has an extended duration of clinical activity which allows once-daily administration. In comparative clinical trials rupatadine was shown to be at least as effective as drugs such as loratadine, cetirizine, desloratadine and ebastine in reducing allergic symptoms in adult/adolescent patients with seasonal, perennial or persistent allergic rhinitis. Importantly, rupatadine demonstrated no adverse cardiovascular effects in preclinical or extensive clinical testing, nor negative significant effects on cognition or psychomotor performance (including a practical driving study). It improved the overall well-being of patients with allergic rhinitis or CIU based on findings from quality of life questionnaires and patient global rating scores in clinical trials. Thus, rupatadine is a recently introduced dual inhibitor of histamine H(1)- and PAF-receptors, which has been shown to be an effective and generally well-tolerated treatment for allergic rhinitis and chronic urticaria. It possesses a broader profile of anti-inflammatory properties inhibiting both inflammatory cells and a range of mediators involved in the early- and late-phase inflammatory response, but the clinical relevance of these effects remain to be clarified.

Impact of CD40 Ligand, B Cells, and Mast Cells in Peanut-Induced Anaphylactic Responses

The effector immune mechanisms underlying peanut-induced anaphylaxis remain to be fully elucidated. We investigated the relative contribution of Igs, mast cells (MCs), and FcepsilonRI in the elicitation of anaphylaxis in a murine model. Assessment of peanut hypersensitivity reactions was performed clinically and biologically. Our data show that wild-type (WT; C57BL/6 strain) mice consistently developed severe anaphylaxis (median clinical score: 3.5/5), an approximately 8 degrees C drop in core body temperature, and significantly increased plasma levels of histamine and leukotrienes. CD40 ligand- and B cell-deficient mice presented evidence of allergic sensitization as demonstrated by production of Th2-associated cytokines by splenocytes and a late-phase inflammatory response that were both indistinguishable to those detected in WT mice. However, CD40 ligand- and B cell-deficient mice did not exhibit any evidence of anaphylaxis. Our data also show that MC-deficient (Kit(W)/Kit(W-v)) mice did not suffer, unlike their littermate controls, anaphylactic reactions despite the fact that serum levels of peanut-specific Igs were similarly elevated. Finally, FcepsilonRI-deficient mice experienced anaphylactic responses although to a significantly lesser degree than those observed in WT mice. Thus, these data demonstrate that the presence of peanut-specific Abs along with functional MCs comprise a necessary and sufficient condition for the elicitation of peanut-induced anaphylaxis. That the absence of FcepsilonRI prevented the development of anaphylaxis only partially insinuates the contribution of an IgE-independent pathway, and suggests that strategies to impair MC degranulation may be necessary to improve the efficacy of anti-IgE therapy.

Orally Administrated Lactobacillus gasseri TMC0356 and Lactobacillus GG Alleviated Nasal Blockage of Guinea Pig with Allergic Rhinitis

Lactobacillus GG (LGG) and L. gasseri TMC0356 (TMC0356) were investigated for their ability to alleviate nasal blockage associated with allergic rhinitis using a guinea pig model. The increases in sRaw at 10 min and 5 hr after the exposure of the nasal mucosa to OVA were significantly alleviated in the guinea pigs orally administrated with LGG and TMC0356 compared with those of the control (P<0.05 and P<0.01). The total numbers of leukocytes, particularly eosinophils and neutrophils from the nasal cavity lavage fluid, and the OVA-specific IgE concentration in the serum were also decreased in the guinea pigs orally administrated with LGG and TMC0356, although the decreases were not statistically significant. These results suggest that LGG and TMC0356 can alleviate antigen-induced nasal blockage in earlyphase and late-phase inflammatory responses associated with allergic rhinitis.

Allergen-IgE Complexes Trigger CD23-Dependent CCL20 Release From Human Intestinal Epithelial Cells

In food allergic individuals, exposure to food allergens by the oral route can trigger immediate (within minutes) local hypersensitivity reactions in the intestine followed by a late-phase inflammatory response. Previous work has shown that CD23 is constitutively expressed by human intestinal epithelial cells and mediates the uptake of allergen-IgE complexes. We hypothesized that allergen-IgE complexes could also signal via CD23 to trigger an inflammatory cascade in the local environment. Caco-2 monolayers were stimulated with human IgE-antigen (Ag) complexes. IL-8 and CCL20 mRNA and protein were determined by RT-PCR and ELISA, respectively. Signaling pathways were assessed by immunoblotting. Endogenous CD23 expression was knocked down by stable transfection with CD23 shRNA retroviral plasmid. Migration assays were performed using human monocyte-derived dendritic cells. Stimulation of Caco-2 cells with IgE-Ag complexes triggered upregulation of IL-8 and CCL20 at the mRNA and protein level. Allergen complexes induced phosphorylation of ERK and JNK, but not p38 MAP kinase or NK-kappaB, and resulted in AP-1 activation. Cross-linking of CD23 replicated the findings with IgE-Ag complexes, and silencing of CD23 expression abrogated the response to allergen-IgE complexes. Supernatant from IgE-Ag-stimulated epithelial cells induced migration of dendritic cells in a CCL20-dependent manner. Finally, immunostaining of duodenal biopsies demonstrated that CCL20 was constitutively expressed by epithelial cells in vivo. Signaling via epithelial CD23 may participate in the late-phase inflammatory response by the release of chemokines capable of recruiting antigen presenting cells and effector cells of allergic inflammation.

Effect of tecastemizole on pulmonary and cutaneous allergic inflammatory responses

Tecastemizole, a major metabolite of astemizole, is a potent and selective H1 receptor antagonist. Evidence suggests that this and certain other H1 receptor antagonists may possess anti-inflammatory effects that are, in some cases, independent of H1 receptor antagonism. Objective The aim of this study was to investigate the anti-inflammatory effects of tectastemizole in models of allergic inflammation. Effects of tecastemizole were assessed in a murine model of allergic lung inflammation, in passive cutaneous anaphylaxis (PCA) responses in guinea-pig skin and in in vitro assays measuring endothelial adhesion molecule expression and leucocyte-endothelial adhesion. Tecastemizole inhibited antigen-induced eosinophil recruitment to the lungs of allergic mice in a dose-dependent manner. Furthermore, combination of a sub-effective dose of tecastemizole, combined with a sub-effective dose of dexamethasone inhibited eosinophil accumulation in this model. Plasma extravasation in PCA reactions was inhibited by tecastemizole, although by a mechanism that would appear to be H1 receptor-dependent. Cytokine-induced endothelial intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression, as well as mononuclear cell adhesion to human umbilical vein endothelial cells was inhibited by tecastemazole in a manner independent of H1 receptor antagonism. These data suggest that tecastemizole may have H1 receptor-independent effects in inhibiting late-phase inflammatory responses, while acute responses appear to be inhibited in a H1 receptor-dependent manner. Furthermore, our data suggest an important potential steroid-sparing role for such drugs in the treatment of allergic inflammatory conditions.

An orally bioavailable small molecule antagonist of CRTH2, ramatroban (BAY u3405), inhibits prostaglandin D2-induced eosinophil migration in vitro.

Ramatroban (Baynas, BAY u3405), a thromboxane A(2) (TxA(2)) antagonist marketed for allergic rhinitis, has been shown to partially attenuate prostaglandin (PG)D(2)-induced bronchial hyperresponsiveness in humans, as well as reduce antigen-induced early- and late-phase inflammatory responses in mice, guinea pigs, and rats. PGD(2) is known to induce eosinophilia following intranasal administration, and to induce eosinophil activation in vitro. In addition to the TxA(2) receptor, PGD(2) is known as a ligand for the PGD(2) receptor, and the newly identified G-protein-coupled chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). To fully characterize PGD(2)-mediated inflammatory responses relevant to eosinophil activation, further analysis of the mechanism of action of ramatroban has now been performed. PGD(2)-stimulated human eosinophil migration was shown to be mediated exclusively through activation of CRTH2, and surprisingly, these effects were completely inhibited by ramatroban. This is also the first report detailing an orally bioavailable small molecule CRTH2 antagonist. Our findings suggest that clinical efficacy of ramatroban may be in part mediated through its action on this Th2-, eosinophil-, and basophil-specific chemoattractant receptor.