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[Action of piroxicam on allergic inflammation].

Effects of piroxicam on allergic inflammation were investigated with allergic air pouch inflammation and antigen-induced arthritis in rats. In allergic air pouch inflammation, piroxicam exerted a dose-dependent inhibition (1-10 mg/kg, p.o.) of the exudate production, the migration of leukocytes and the release of lysosomal enzyme into the exudate; and its potency was superior to that of indomethacin and equivalent to that observed with prednisolone. In contrast with this, the suppressive effect of piroxicam on non-allergic air pouch inflammation was as weak as indomethacin. Prednisolone showed a similar effect on both types of air pouch inflammation. In antigen-induced arthritis, piroxicam showed a dose-dependent (0.3-3 mg/kg, p.o.) inhibitory effect on knee joint swelling and an improving action on the functional disorder of the inflamed joint. On this model, piroxicam was 3 to 4 times more active than both indomethacin and prednisolone. In non-allergic joint inflammation induced with croton oil in rats, however, the anti-inflammatory potency of piroxicam was almost equal to those of indomethacin and prednisolone. Piroxicam showed more potent inhibition than indomethacin on heterologous passive cutaneous anaphylaxis in rats, but showed only a slight inhibition on the increased vascular permeability caused by histamine and bradykinin. Piroxicam had no influence upon the plaque-forming cell response and the delayed hypersensitivity reaction in mice; furthermore, the hemolytic activity of complement in guinea-pig serum was scarcely affected by piroxicam in vitro. These results indicate that piroxicam possesses prominent efficiency on allergic inflammation and may function on several activities of inflammatory cells.

Air Sacs↗

Possible participation of cyclooxygenase-2 in the recurrence of allergic inflammation in rats.

In the recurrence of allergic inflammation in a rat air pouch model, pouch fluid volume, prostaglandin E2 concentration in the pouch fluid, leukocyte infiltration into the pouch fluid, and granulation tissue weight were markedly increased by the antigen challenge. To clarify the role of cyclooxygenase-2 in the recurrence of allergic inflammation, the time-course of changes in protein levels of cyclooxygenase-1 and cyclooxygenase-2 in the granulation tissue and in the infiltrated leukocytes was examined by Western blot analysis. It was shown that cyclooxygenase-1 levels in the granulation tissue and in the infiltrated leukocytes were not changed by the antigen challenge, but cyclooxygenase-2 levels were increased. Furthermore, treatment with the selective cyclooxygenase-2 inhibitor, NS-398 ([N-2(cyclohexyloxy-4-nitrophenyl]-methanesulfonamide), suppressed the recurrence of allergic inflammation as did the non-selective cyclooxygenase-1/cyclooxygenase-2 inhibitor, indomethacin. The steroidal anti-inflammatory drug, dexamethasone, inhibited the induction of cyclooxygenase-2, and suppressed the allergic inflammation. These findings strongly suggested that cyclooxygenase-2 induced by the antigen challenge plays a role in the recurrence of inflammation induced by the allergic mechanism.

Animals↗

[Allergic inflammation].

Current ideas of allergic inflammation reflected in the concept of immune inflammation are described. This concept considers immune inflammation to be an immune response mediated by a certain immunity reaction which gives the inflammation a number of qualitative and quantitative differences. The nature of the differences allows allergic (immune) inflammation to be evaluated as a biologically expedient type of defence-adaptative reaction in which the inflammatory response is optimally expressed owing to the participation of immunological mechanisms.

Eosinophils↗

Augmentation of allergic inflammation in prostanoid IP receptor deficient mice.

1 To evaluate the role of prostaglandin I(2) (PGI(2)) in allergic inflammation, allergic responses in the airway, skin and T cells were studied in mice lacking the receptor for PGI(2) (the prostanoid IP receptor) through gene disruption. 2 Three inhalations of antigen caused an increase in plasma extravasation, leukocyte accumulation and cytokine (interleukin (IL)-4 and IL-5) production in the airway of sensitized mice. These airway inflammatory responses were significantly greater in IP receptor deficient mice than in wild-type mice. 3 The vascular leakage caused by passive cutaneous anaphylaxis, substance P and 5-hydroxytryptamine was markedly increased in the skin of IP receptor deficient mice, compared with comparably treated wild-type mice. 4 The inhalation of antigen in sensitized mice resulted in increased serum antigen specific IgE, total IgE and IgG levels. The magnitude of the elevations of each immunoglobulin level in IP receptor deficient mice is notably higher than that in wild-type mice. To elucidate the mechanism of an enhancement of immunoglobulin production, the activity of T cells in sensitized and non-sensitized mice was studied by means of the production of cytokines. The antigen-induced IL-4 production by spleen cells from sensitized IP receptor deficient mice was almost three times greater than that in wild-type mice. On the contrary, the anti-CD3 antibody-induced interferon-gamma production by CD4(+) T cells from non-sensitized IP receptor deficient mice was significantly lower than that in wild-type mice. 5 The present data indicate that IP receptor deficiency reinforced an allergic airway and skin inflammation by augmentation of vascular permeability increase and the T helper 2 cell function. These findings suggest a regulatory role of PGI(2) in allergic inflammation.

Animals↗

Enhanced Th2 cell-mediated allergic inflammation in Tyk2-deficient mice.

Allergic inflammation is mediated by Th2 cell-derived cytokines, including IL-4, IL-5, and IL-13, and down-regulated by IFN-gamma and IL-12. Tyk2 is a member of the Janus family of protein tyrosine kinases and is activated by a variety of cytokines: IFN-alphabeta, IL-6, IL-10, IL-12, and IL-13. In this study, we investigated the role of Tyk2 in the regulation of Ag-induced Th cell differentiation and Ag-induced allergic inflammation in the airways using Tyk2-deficient (Tyk2(-/-)) mice. When splenocytes were stimulated with antigenic peptide, IL-12-mediated Th1 cell differentiation was decreased, but IL-4-mediated Th2 cell differentiation was increased in Tyk2(-/-) mice. In vivo, Ag-specific IgE and IgG1 production was increased, but Ag-specific IgG2a production was decreased in Tyk2(-/-) mice as compared with those in control mice. In addition, Ag-induced eosinophil and CD4(+) T cell recruitment, as well as the production of Th2 cytokines in the airways, was increased in Tyk2(-/-) mice. Adoptive transfer experiments revealed that CD4(+) T cells were responsible for the enhanced Ag-induced eosinophil recruitment in Tyk2(-/-) mice. In contrast, although the level of IL-13 was increased in the airways of Tyk2(-/-) mice after Ag inhalation, the number of goblet cells, as well as Muc5ac mRNA expression, was decreased in Tyk2(-/-) mice. Together, these results indicate that Tyk2 plays a bilateral role in the regulation of allergic inflammation in the airways: Tyk2 plays a role in the down-regulation of Th2 cell-mediated Ab production and eosinophil recruitment in the airways by regulating Th1/Th2 balance toward Th1-type, while Tyk2 is necessary for the induction of IL-13-mediated goblet cell hyperplasia in the airways.

Administration, Inhalation↗

The role of transcription factors in allergic inflammation.

The induction of allergic inflammation and the expression of allergic disorders are dependent on the coordinated regulation of numerous genes. The products of these genes determine lymphocyte phenotype, immunologic responsiveness, eosinophil and mast cell development, activation, migration and life span, adhesion molecule expression, cytokine synthesis, cell-surface receptor display, and processes governing fibrosis and tissue repair. Although the expression of gene products involved in these processes is regulated at multiple levels (eg, transcription, mRNA processing, translation, phosphorylation, and degradation), transcription represents an essential and often the most important determinant of their contribution to cellular function. Signal-dependent and cell type-specific regulation of gene expression is generally achieved by means of combinatorial interactions between sequence-specific transcription factors that recruit chromatin remodeling machinery and general transcription factors to promoter and enhancer regions of RNA polymerase II-dependent genes. As targets of signal-transduction pathways, transcription factors integrate the response of the cell to the myriad of inputs it receives. This integration can be accomplished by the effect of signaling cascades on the activation status or subcellular locus of transcription factors or by transcription factor dimerization induced by means of ligand binding. This review will identify the major families of transcription factors important in allergic mechanisms and discuss their interactions, their mechanisms of action, and their interrelated and competitive actions, as well as implications for therapy of allergic disorders.

Animals↗

Glucocorticosteroids in allergic inflammation: clinical benefits in allergic rhinitis, rhinosinusitis, and otitis media.

Allergic rhinitis, rhinosinusitis, and otitis media are among the most common health problems encountered in general practice. Although frequently trivialized, they affect the quality of life, represent a significant socioeconomic burden, and are associated with some serious complications. In addition, allergic rhinitis, rhinosinusitis, and otitis media are often considered as comorbidities. These disorders involve an inflammatory process of the respiratory mucosa of the nose, paranasal sinuses, or middle ear. Because of their well-known anti-inflammatory effects, the role of glucocorticosteroids in the management of these three disorders has been questioned, evaluated, and, in some cases, established.

Administration, Intranasal↗

Characterization of methylated bovine serum albumin-induced allergic inflammation in rats.

An air pouch type allergic inflammation in rats was induced using an insoluble cationic protein, methylated bovine serum albumin (MeBSA), as an antigen. Changes in vascular permeability, local tissue edema, histamine contents in the pouch fluid, and number of infiltrated leukocytes and chemotactic activity in the pouch fluid were analyzed during an 8-hour period after injecting the antigen solution into the air pouch of the immunized and nonimmunized rats. Vascular permeability during the first 30-min interval in the immunized rats was higher than that in the nonimmunized rats, reflecting a higher histamine level in the pouch fluid. However, both the increase in vascular permeability and histamine level in the immunized rats in this period were much lower than those induced by a soluble, noncationic antigen, azobenzenearsonate-conjugated acetyl bovine serum albumin. In the MeBSA-induced allergic inflammation model, a second peak of vascular permeability was induced at 2 h, and local tissue edema formation became apparent at 2 h, reaching a plateau at 4 h. A prominent increase in leukocyte infiltration, especially neutrophils, into the pouch fluid was induced at 4 h in accordance with an increase in chemotactic activity in the pouch fluid. These observations indicate that the acute phase of MeBSA-induced allergic inflammation is characterized by a weak anaphylactic response and a prominent neutrophil infiltration.

Animals↗

A role of peripheral leukocytes in vascular permeability and edema formation in air pouch type allergic inflammation in rats.

Using an air pouch type allergic inflammation model in rats, a role of circulating leukocytes in allergic inflammation responses was investigated by comparing normal rats with peripheral leukocytopenia rats induced by cyclophosphamide treatment. In the leukocytopenia rats, vascular permeability, edema formation, leukocyte infiltration into the pouch fluid, neutrophil chemotactic activity in the pouch fluid occurred both at the early phase (4 h) and the late phase (8 h) after the antigen challenge were decreased. However, edema formation induced by intradermal injection of arachidonate metabolites, serotonin, or platelet activating factor was not suppressed at all in the leukocytopenia rats. A possible role of peripheral leukocytes in allergic and non-allergic inflammation is discussed.

Animals↗

Activation of the prostaglandin D2 receptor DP2/CRTH2 increases allergic inflammation in mouse.

Allergic pathologies are often associated with IgE production, mast cell activation, and eosinophilia. PGD2 is the major eicosanoid, among several inflammatory mediators, released by mast cells. PGD2 binds to two membrane receptors, D prostanoid receptor (DP)1 and DP2, endowed with antagonistic properties. In humans, DP2 is preferentially expressed on type 2 lymphocytes, eosinophils, and basophils and mediates chemotaxis in vitro. Although not yet supported by in vivo studies, DP2 is thought to be important in the promotion of Th2-related inflammation. Herein, we demonstrate that mouse eosinophils express both DP1 and DP2 and that PGD2 exerts in vitro chemotactic effects on eosinophils through DP2 activation. Furthermore, 13,14-dihydro-15-keto-PGD2, a specific DP2 agonist not only increases eosinophil recruitment at inflammatory sites but also the pathology in two in vivo models of allergic inflammation: atopic dermatitis and allergic asthma. By contrast, DP1 activation tends to ameliorate the pathology in asthma. Taken together, these results support the hypothesis that DP2 might play a critical role in allergic diseases and underline the interest of DP2 antagonists in human therapy.

Animals↗

[T lymphocytes in allergic inflammation].

T lymphocytes are the crucial cells in immunopathogenesis of allergic diseases since they regulate the occurrence of allergic sensitisation, synthesis of immunoglobulin E and allergic inflammation. The importance of lymphocyte T is reflected on the fact that after activation by a specific antigen they are able to produce different cytokines responsible for activation and aggregation of specific inflammatory cells in target tissues, promoting the occurrence and maintenance of allergic inflammation. Discovery of functional dichotomy of activated lymphocytes T CD4+ capable of suppressing synthesis of immunoglobulin E (Th1) or stimulate immunoglobulin E and allergic inflammation (Th2) is an important element in elucidation of pathogenesis of allergic inflammation and inadequate synthesis of immunoglobulin E. The immunoglobulin synthesis is regulated by a complex combination of factors and signals where lymphocytes CD4+ play the central regulatory role.

Humans↗

Onset and persistence of the allergic inflammation: a molecular explanation?

Allergic respiratory inflammation in target organs does not occur in any atopic (genetically susceptible) subject, since other not fully characterized factors can influence the subsequent development of overt clinical disease. Here are presented some recent developments in experimental animal and human research that can offer a new "non-classical" interpretation about the way by which allergens are recognized and allergic inflammation persists. These aspects of the immunopathogenesis of allergic diseases can now be viewed as organ-specific pathways, acting independently from other peripheral lymphoid organs. This is a consequence of new knowledge about the function of, and molecular interactions by, intraepithelial gammadelta T cells and CD1+ dendritic cells. The allergic subject, unlike the normal one, is equipped at the mucosal surface by particular T cell and antigen-presenting cell (APC) subsets that enable them to recognize undenatured proteic and non-proteic (glycolipidic) external structures of aerodispersed particles, presented in the context of CD1 molecules. Once initiated, the mucosal allergic reaction cannot be turned off in atopic individuals because CD4+ allergen-specific T cells lack surface Fas receptor. This defect, that impairs the so-called activation-induced programmed cell death (determined by Fas/FasL interaction), is caused by the local Th2-type cytokine milieu.

Animals↗

A specific CCR3 chemokine receptor antagonist inhibits both early and late phase allergic inflammation in the conjunctiva.

Allergic inflammation manifests as one of a number of diseases, including asthma, dermatitis, food allergy, vernal keratoconjunctivitis, and systemic anaphylaxis. Together these diseases affect nearly 25% of the Western world and are a leading health-care problem. The diseases are often biphasic, with an early phase driven primarily by mast cell degranulation and a late phase characterized by leukocyte recruitment. While chemokines are well known to be critical for leukocyte recruitment, their importance in early-phase reactions is poorly defined. We show here that administration of a single oral dose of a high affinity and highly selective CCR3 antagonist ablates both the early and late phase reactions in a mouse model of allergic conjunctivitis. A direct analysis of mast cells in the conjunctiva demonstrates that antagonism of the CCR3 receptor stabilizes the mast cell in vivo, thereby leading to the impaired early phase reaction. The late phase reaction is also strongly inhibited as characterized by both reduced eosinophilia and neutrophilia. These results constitute the first direct evidence that antagonism of CCR3 has clear potential for the treatment of allergic diseases.

Administration, Oral↗

IL-13 R130Q, a common variant associated with allergy and asthma, enhances effector mechanisms essential for human allergic inflammation.

Genetic factors are known to strongly influence susceptibility to allergic inflammation. The Th2 cytokine IL-13 is a central mediator of allergy and asthma, and common single-nucleotide polymorphisms in IL13 are associated with allergic phenotypes in several ethnically diverse populations. In particular, IL13+2044GA is expected to result in the nonconservative replacement of arginine 130 (R130) with glutamine (Q). We examined the impact of IL13+2044GA on the functional properties of IL-13 by directly comparing the activity of WT IL-13 and IL-13 R130Q on primary human cells involved in the effector mechanisms of allergic inflammation. Our results show that IL-13 R130Q was significantly more active than WT IL-13 in inducing STAT6 phosphorylation and CD23 expression in monocytes and hydrocortisone-dependent IgE switching in B cells. Notably, IL-13 R130Q was neutralized less effectively than WT IL-13 by an IL-13R2 decoy. Decreased neutralization of the minor variant could contribute to its enhanced in vivo activity. Neither IL-13 variant was able to engage T cells, which suggests that increased allergic inflammation in carriers of IL13+2044A depends on enhanced IL-13-mediated Th2 effector functions rather than increased Th2 differentiation. Collectively, our data indicate that natural variation in the coding region of IL13 may be an important genetic determinant of susceptibility to allergy.

Animals↗

[Cytokines in allergic inflammation].

Cytokines play a central role in the pathogenesis of allergic diseases and allergic inflammation. Therefore, an understanding of mechanisms which regulate production and function of cytokines is very important and may result in the development of more effective methods of treatment of allergic diseases. Recent studies have demonstrated that the induction of allergic inflammation requires genetic background and environmentak factors. The most important cytokines and chemokines are IL-4, IL-5, IL-3, IL-13, GM-CSF and TNF-alpha. Many other cytokines are responsible for the growth, maturity, migration activation and apoptosis of all cells involved in allergic inflammation, among them are IL-2, IL-5, IL-6, IL-9, MIP-1 alpha, RANTES, IL-8, IL-12, IL-18, IFN-alpha i gamma, TGF-beta, sIL-4, IL-1Ra. Recently it has been proven that IL-10 and other cytokines from the IL-10 family, and TGF-beta have anti-inflammatory properties in allergy.

Cytokines↗

Basophils play a critical role in the development of IgE-mediated chronic allergic inflammation independently of T cells and mast cells.

The recruitment of basophils into the sites of allergic inflammation is often observed. However, no definitive evidence has been provided that basophils are crucially involved in the pathogenesis of chronic allergic disorders. Here, we show that basophils are responsible for the development of IgE-mediated chronic allergic inflammation independently of T cells and mast cells. A single subcutaneous injection of multivalent antigens elicited not only immediate- and late-phase ear swelling but also delayed-onset ear swelling with massive eosinophil infiltration in mice sensitized with antigen-specific IgE. Mast cells were essential for the immediate- and late-phase ear swelling but dispensable for the delayed one. T cells were also dispensable for the latter. Transfer of FcRI-expressing basophils into FcRI-deficient mice restored the development of the delayed-onset allergic inflammation. These findings indicate a novel mechanism of development of chronic allergic inflammation that is induced by basophils through the interaction of antigen, IgE, and FcRI.

Animals↗

The mechanism of histamine production in allergic inflammation.

In the air pouch-type allergic inflammation model in rats, histamine produced in the late phase plays a role in downregulation of leukocyte infiltration into the pouch fluid. In the pouch fluid, we found two kinds of histamine production-increasing factor (HPIF); HPIF-1, which induces histamine production in bone marrow cells, and HPIF-2, which enhances the activity of HPIF-1. Isoelectric point and molecular weight of HPIF-1 and HPIF-2 were estimated to be pI 4-5 and 25-40 kD, and pI 7-8 and about 100 kD, respectively. The histamine-producing ability of bone marrow cells increased after the antigen challenge, but that of peripheral leukocytes decreased markedly 8 h after the antigen challenge. Pharmacological analysis indicated that HPIF-1 induces histamine production through activation of protein kinase C and tyrosine kinase. Differentiation of bone marrow cells to histamine-producing cells by HPIF-1 was also indicated. From these observations, the histamine production in the late phase of allergic inflammation is suggested to be regulated by the production of HPIF-1, proliferation/differentiation of histamine-producing cells, and infiltration of histamine-producing cells in blood circulation into the inflammatory site.

Animals↗

Platelet-activating factor in the inflammatory exudate in the anaphylactic phase of allergic inflammation in rats.

Using a model of allergic inflammation of air pouch type in rats, the platelet-activating factor (PAF) in the pouch fluid in the anaphylactic phase was analyzed. Anaphylactic reaction was induced by injecting an antigen (azobenzene-arsonate-conjugated acetyl bovine serum albumin) solution into a subcutaneous air pouch preformed on the dorsum of immunized rats. The pouch fluid was collected 30 min after the antigenic challenge, and chloroform extract was subjected to normal phase high-performance liquid chromatography to isolate two fractions, PAF and lyso-PAF. In the pouch fluid, however, there was little activity of PAF as examined by the aggregation of guinea pig platelets. The lyso-PAF fraction obtained was acetylated to PAF chemically with pyridine and acetic anhydride. This acetylated lyso-PAF fraction induced the aggregation of guinea pig platelets, which was inhibited dose-dependently by a PAF antagonist, CV-3988. The amount of lyso-PAF in the pouch fluid of the immunized group in the anaphylactic phase was significantly higher than that of the nonimmunized group. When (3H-)PAF was incubated with the supernatant fraction of the pouch fluid it was metabolized into lyso-PAF time-dependently. The significance of the higher level of lyso-PAF in the pouch fluid in the anaphylactic phase of allergic inflammation is discussed.

Adenosine Diphosphate↗