Ocimum gratissimum Linn. and rosmarinic acid, attenuate eosinophilic airway inflammation in an experimental model of respiratory allergy to Blomia tropicalis.

Allergic asthma has emerged as an important public health problem of urban populations in developed countries. Very often herbal medicine is used to treat this widespread disease, due to the lack of efficacy and the important side effects related to the classical drugs in use. Along this line, Ocimum gratissimum (Og) is a plant widely used in Brazilian folk medicine to treat inflammatory disorders, such as asthma. In the present study we evaluated the immunomodulatory effects of Og and rosmarinic acid (RA, a polyphenolic compound) in a murine model of respiratory allergy induced by the Blomia tropicalis (Bt) mite. The respiratory allergy was induced in A/J mice by administration of Bt extract and the treatment was done using 25, 50 or 100mg/kg of an Og methanolic extract or using 2, 20 or 200mg/kg of RA. We then evaluated the changes induced by these drugs on immunological parameters related to the allergic process, which are up-regulated in this allergic model. The treatment of animals with 100mg/Kg Og and 200mg/Kg RA led to a significant reduction in the numbers of leukocytes/eosinophils in bronchoalveolar lavage (BAL); eosinophil peroxidase activity in BAL; presence of mucus in respiratory tract, histopathological changes in the lung, and IL-4 in BAL. These results suggest that the methanolic extract of Og and the polyphenol RA have therapeutic potential in this murine model of respiratory allergy to a clinically relevant human sensitizer allergen.

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

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

Biochemical, functional, and pharmacological characterization of AT-56, an orally active and selective inhibitor of lipocalin-type prostaglandin D synthase.

We report here that 4-dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)-butyl]-piperidine (AT-56) is an orally active and selective inhibitor of lipocalin-type prostaglandin (PG) D synthase (L-PGDS). AT-56 inhibited human and mouse L-PGDSs in a concentration (3-250 microm)-dependent manner but did not affect the activities of hematopoietic PGD synthase (H-PGDS), cyclooxygenase-1 and -2, and microsomal PGE synthase-1. AT-56 inhibited the L-PGDS activity in a competitive manner against the substrate PGH(2) (K(m) = 14 microm) with a K(i) value of 75 microm but did not inhibit the binding of 13-cis-retinoic acid, a nonsubstrate lipophilic ligand, to L-PGDS. NMR titration analysis revealed that AT-56 occupied the catalytic pocket, but not the retinoid-binding pocket, of L-PGDS. AT-56 inhibited the production of PGD(2) by L-PGDS-expressing human TE-671 cells after stimulation with Ca(2+) ionophore (5 microm A23187) with an IC(50) value of about 3 microm without affecting their production of PGE(2) and PGF(2alpha) but had no effect on the PGD(2) production by H-PGDS-expressing human megakaryocytes. Orally administered AT-56 (<30 mg/kg body weight) decreased the PGD(2) production to 40% in the brain of H-PGDS-deficient mice after a stab wound injury in a dose-dependent manner without affecting the production of PGE(2) and PGF(2alpha) and also suppressed the accumulation of eosinophils and monocytes in the bronco-alveolar lavage fluid from the antigen-induced lung inflammation model of human L-PGDS-transgenic mice.

Real-time assessment of inflammation and treatment response in a mouse model of allergic airway inflammation.

Eosinophils are multifunctional leukocytes that degrade and remodel tissue extracellular matrix through production of proteolytic enzymes, release of proinflammatory factors to initiate and propagate inflammatory responses, and direct activation of mucus secretion and smooth muscle cell constriction. Thus, eosinophils are central effector cells during allergic airway inflammation and an important clinical therapeutic target. Here we describe the use of an injectable MMP-targeted optical sensor that specifically and quantitatively resolves eosinophil activity in the lungs of mice with experimental allergic airway inflammation. Through the use of real-time molecular imaging methods, we report the visualization of eosinophil responses in vivo and at different scales. Eosinophil responses were seen at single-cell resolution in conducting airways using near-infrared fluorescence fiberoptic bronchoscopy, in lung parenchyma using intravital microscopy, and in the whole body using fluorescence-mediated molecular tomography. Using these real-time imaging methods, we confirmed the immunosuppressive effects of the glucocorticoid drug dexamethasone in the mouse model of allergic airway inflammation and identified a viridin-derived prodrug that potently inhibited the accumulation and enzyme activity of eosinophils in the lungs. The combination of sensitive enzyme-targeted sensors with noninvasive molecular imaging approaches permitted evaluation of airway inflammation severity and was used as a model to rapidly screen for new drug effects. Both fluorescence-mediated tomography and fiberoptic bronchoscopy techniques have the potential to be translated into the clinic.

Establishment of an allergic rhinitis model in mice for the evaluation of nasal symptoms.

The purpose of our study was to establish a new model of allergic rhinitis in mice, eliciting symptoms such as sneezing, infiltration of eosinophils into the nasal mucosa, and antigen-specific IgE production. One of the major human T-cell epitopes in Cry j 1, an allergen of Japanese cedar pollen, is also a major murine T-cell epitope in B10.S mice. Thus we tried to establish an allergic rhinitis model in B10.S mice with Cry j 1 as the antigen. We sensitized B10.S mice subcutaneously with Cry j 1/alum three times at intervals of 1 week. Five weeks after the final sensitization, we challenged the mice by instilling Cry j 1 intranasally from the day after intranasal histamine pretreatment. Soon after, we counted the number of sneezes. We then evaluated the infiltration of eosinophils into the nasal tissues and also measured the serum levels of antigen-specific IgE antibody. In addition, we confirmed the effects of ketotifen fumarate and dexamethasone hydrochloride on these animals. In Cry j 1-sensitized B10.S mice, sneezes, eosinophil peroxidase (EPO) activity in nasal tissues, and Cry j 1-specific IgE clearly increased after intranasal histamine pretreatment and 5 days of continuous intranasal Cry j 1 challenge. Both ketotifen and dexamethasone inhibited the increase in sneezing, and dexamethasone also inhibited EPO activity and Cry j 1-specific IgE. Thus we succeeded in establishing a new model of allergic rhinitis in Cry j 1-sensitized B10.S mice, which exhibited sneezing, eosinophil infiltration into the nasal mucosa, and Cry j 1-specific IgE production.

Oxidant-mediated mitochondrial injury in eosinophil apoptosis: enhancement by glucocorticoids and inhibition by granulocyte-macrophage colony-stimulating factor.

The mainstay of asthma therapy, glucocorticosteroids (GCs) have among their therapeutic effects the inhibition of inflammatory cytokine production and induction of eosinophil apoptosis. In the absence of prosurvival cytokines (e.g., GM-CSF), eosinophils appear to be short-lived, undergoing apoptosis over 96 h in vitro. In a dose-dependent manner, GC further enhances apoptosis, while prosurvival cytokines inhibit apoptosis and antagonize the effect of GC. The mechanisms of eosinophil apoptosis, its enhancement by GC, and antagonism of GC by GM-CSF are not well-understood. As demonstrated in this study, baseline apoptosis of eosinophils resulted from oxidant-mediated mitochondrial injury that was significantly enhanced by GC. Mitochondrial injury was detected by early and progressive loss of mitochondrial membrane potential and the antioxidant protein, Mn superoxide dismutase (SOD). Also observed was the activation/translocation of the proapoptotic protein, Bax, to mitochondria. Underscoring the role of oxidants was the inhibition of mitochondrial changes and apoptosis with culture in hypoxia, or pretreatment with a flavoprotein inhibitor or a SOD mimic. GCs demonstrated early (40 min) and late (16 h) activation of proapoptotic c-Jun NH2-terminal kinase (JNK) and decreased the antiapoptotic protein X-linked inhibitor of apoptosis, a recently demonstrated inhibitor of JNK activation. Similarly, inhibition of JNK prevented GC-enhanced mitochondrial injury and apoptosis. Importantly, GM-CSF prevented GC-induced loss of X-linked inhibitor of apoptosis protein, late activation of JNK, and mitochondrial injury even in the face of unchanged oxidant production, loss of MnSOD, and early JNK activation. These data demonstrate that oxidant-induced mitochondrial injury is pivotal in eosinophil apoptosis, and is enhanced by GC-induced prolonged JNK activation that is in turn inhibited by GM-CSF.

Neutrophil and eosinophil granule proteins as markers of response to local prednisolone treatment in distal ulcerative colitis and proctitis.

OBJECTIVE: The pathophysiological role of neutrophil and eosinophil granulocytes in relation to steroid enema treatment was studied in patients with distal ulcerative colitis and proctitis. METHODS: The rectal release of the neutrophil (myeloperoxidase, MPO), and eosinophil (eosinophilic cationic protein, ECP and eosinophil peroxidase, EPO) granule constituents were measured in 11 patients using intraluminal segmental perfusion of the rectum. The released amounts of MPO, ECP, and EPO in the perfusion fluids were determined by radioimmunoassays before and during prednisolone enema treatment and related to clinical, endoscopical, and histopathological data in addition to treatment outcome. RESULTS: Clinical activity and particularly endoscopic activity correlated well with intraluminal MPO concentrations both before and during treatment. At the end of the study, eight of 11 patients fulfilled predefined response criteria; all responding patients had significant decrease of MPO concentrations (p < 0.01). This decline of MPO concentration was seen after 7 days of treatment (p < 0.05) in the response group and often occurred before clinical improvement. There was a nonsignificant trend toward a decrease in the concentrations of ECP and EPO at the end of treatment in responders.

Activation of human leukocytes reduces surface P-selectin glycoprotein ligand-1 (PSGL-1, CD162) and adhesion to P-selectin in vitro.

P-selectin glycoprotein ligand-1 (PSGL-1), the primary ligand for P-selectin, is constitutively expressed on the surface of circulating leukocytes. The objective of this study was to examine the effect of leukocyte activation on PSGL-1 expression and PSGL-1-mediated leukocyte adhesion to P-selectin. PSGL-1 expression was examined via indirect immunofluorescence and flow cytometry before and after leukocyte stimulation with platelet activating factor (PAF) and PMA. Human neutrophils, monocytes, and eosinophils were all demonstrated to have significant surface expression of PSGL-1 at baseline, which decreased within minutes of exposure to PAF or PMA. PSGL-1 was detected in the supernatants of PAF-activated neutrophils by immunoprecipitation. Along with the expression data, this suggests removal of PSGL-1 from the cell surface. Soluble PSGL-1 was also detected in human bronchoalveolar lavage fluids. Down-regulation of PSGL-1 was inhibited by EDTA. However, inhibitors of L-selectin shedding and other sheddase inhibitors did not affect PSGL-1 release, suggesting that PSGL-1 may be shed by an as yet unidentified sheddase or removed by some other mechanism. Functionally, PSGL-1 down-regulation was associated with decreased neutrophil adhesion to immobilized P-selectin under both static and flow conditions, with the most profound effects seen under flow conditions. Together, these data indicate that PSGL-1 can be removed from the surface of activated leukocytes, and that this decrease in PSGL-1 expression has profound effects on leukocyte binding to P-selectin, especially under conditions of flow.

Purification, characterization, and cDNA sequencing of cytosolic phospholipase A(2) from equine neutrophils.

It has been demonstrated that equine neutrophils, but not eosinophils, require exogenous arachidonic acid for calcium ionophore A23187-induced leukotriene synthesis. Because cytosolic phospholipase A(2) (cPLA(2)) plays an essential role in leukotriene formation in leukocytes, we investigated the presence of a functional cPLA(2) in equine neutrophils. To determine whether cPLA(2) from neutrophils was catalytically active, we purified the enzyme >6,500 fold with 3% recovery from equine neutrophils. The full-length cDNA sequence encoded a 749-amino acid protein. The deduced amino acid sequence demonstrated 95% identity with human and mouse cPLA(2), as well as 83 and 73% identity with chicken and zebra fish cPLA(2) protein, respectively. The equine cPLA(2) possessed some properties that distinguished the equine enzyme from the human enzyme. First, the enzyme activity of the equine cPLA(2) was differently influenced by cations as compared with the human cPLA(2). Second, the equine neutrophil cPLA(2) migrated as an approximately 105-kDa protein, in comparison with human cPLA(2) which migrated as a 110-kDa protein. A difference between equine neutrophils and eosinophils in the degree of phosphorylation of the cPLA(2) protein was observed. Thus, the cPLA(2) protein from eosinophils was constitutively phosphorylated, while the cPLA(2) protein from neutrophils was unphosphorylated. In summary, these results demonstrate that equine neutrophils indeed express an active cPLA(2) protein but that there is a difference in the degree of phosphorylation of the cPLA(2) protein between equine neutrophils and eosinophils. This difference might explain the difference between the two cell types in the capacity to produce leukotrienes from endogenous substrate.

Studies of differential gene expression in clinically derived eosinophil populations.

BACKGROUND: Influx of eosinophils into the post-capillary bronchial epithelium and the subsequent release of inflammatory mediators is characteristic of the late phase of asthmatic attacks. The genes that serve to predispose the peripheral blood eosinophils of asthmatics to undergo this process are poorly defined. The aim of this report is to describe the differential gene expression of both the known pro-inflammatory genes 5-lipoxygenase and 5-lipoxygenase-activating protein (FLAP) and novel cDNA sequences in eosinophils derived from clinical samples. METHODS: Novel cDNA sequences representing genes upregulated in peripheral blood eosinophils of asthmatic as compared with nonasthmatic patients were identified by differential display polymerase chain reaction (DDPCR). The differential expression of these sequences, in addition to known pro-inflammatory genes, were then studied by reverse dot blotting of amplified RNA generated from the eosinophils of nonasthmatic donors, asthmatic donors, asthmatic donors taking steroids, interleukin (IL) -3, IL-5, granulocyte-macrophage colony stimulating factor- (GM-CSF) treated eosinophils from asthmatic donors and the eosinophilic cell line AML14. RESULTS: Four unique DDPCR-generated 3'UTR DNA fragments were identified that showed differing patterns of expression between the eosinophil populations of interest. Expression of each of the novel clones was increased in the peripheral blood eosinophils of asthmatics and downregulated in those donors taking steroids. Expression of 5-lipoxygenase was not found to vary between the different eosinophil populations, whereas FLAP was induced by treatment with the cytokine cocktail in both primary eosinophils and the eosinophilic cell line AML14. CONCLUSION: The differential regulation of the novel cDNA sequences and FLAP in the range of eosinophil populations studied suggest that they may provide clinically relevant therapeutic targets. Moreover, the procedures used in these studies may provide a general approach to the study of differential gene expression in small numbers of cells such as those obtained from clinical samples.

7-Oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridines as novel inhibitors of human eosinophil phosphodiesterase.

High-throughput file screening against inhibition of human lung PDE4 led to the discovery of 3-ethyl-1-(4-fluorophenyl)-6-phenyl-7-oxo-4, 5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine (11) as a novel PDE4 inhibitor. Subsequent SAR development, using an eosinophil PDE assay, led to analogues up to 50-fold more potent than 11 with IC50 values of 0.03-1.6 microM. One such compound, CP-220,629 (22) (IC50 = 0.44 microM), was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 2.0 mg/kg, po) and demonstrated a significant reduction in eosinophil (55%), neutrophil (65%), and IL-1beta (82%) responses to antigen challenge in atopic monkeys (10 mg/kg, po).

A role for Th2 T-memory cells in early airway obstruction.

The role of T-cell memory in late-phase allergic lung inflammation is not well defined. To evaluate the role of systemic T-cell memory in allergic late-phase lung inflammation, BALB/c mice were injected intraperitoneally with ovalbumin (OVA) or ragweed (RW) allergens (Test I and Test II groups) or saline (control groups C I and C IV) and then challenged intratracheally with the allergen. Late-phase allergic lung inflammation was defined by: (i) recruitment of eosinophils to airways, (ii) IL-5 mRNA upregulation in BAL fluid cells, and (iii) detection of a Th2 cell cytokine profile in BAL fluids. The number of eosinophils recruited in allergic mice following intratracheal challenge with allergen was at least 300-fold higher P < or = 0.01) in mice with allergen-specific T-memory cells in BAL fluid (Test I and Test II) than in control mice without allergen-specific T-memory cells (C I and C IV). Further, the number of eosinophils recruited in Test I and II correlated with the magnitude of in vitro T-cell memory responses (r = 0.93, P < or = 0.04). Moreover, IL-5 mRNA upregulation in BAL cells and Th2 cytokine production in BAL fluids were observed only in Test I and Test II, and not in any of the control groups. Further, results from pulmonary function tests performed on the same allergic animals indicated that only animals from Test I and Test II groups had impaired lung function after allergen challenge. Taken together, these data strongly suggest that allergen-specific Th2-type T-cell memory is required for the development of allergic asthma. That is, without T-cell memory responses, no eosinophil recruitment and release of EPO (which is known to induce bronchoconstriction) occurred in the airways, and no Th2 cytokine profile was detected in the BAL fluid. Furthermore, if the Th2 cytokine profile was absent, then pulmonary functions remained normal.

Demonstration and partial purification of lactoperoxidase from human colostrum.

A peroxidase with stability, chromatographic and immunoreactive properties similar to that of bovine lactoperoxidase has been partly purified from human colostrum. Hydrophobic interaction chromatography on Phenyl-Sepharose C1-4B gave a 10-fold purification with an apparent recovery of about 45%. The enzyme was quantitatively and specifically adsorbed to beads of anti-lactoperoxidase (bovine)-Protein A-Sepharose. No adsorption of the enzyme was observed on immunoadsorbent columns prepared with high-titre polyclonal antibodies raised against human myeloperoxidase and human eosinophile peroxidase.