Richard W. Chapman

New IL-17 Family Members Promote Th1 or Th2 Responses in the Lung: In Vivo Function of the Novel Cytokine IL-25

We have biologically characterized two new members of the IL-17 cytokine family: IL-17F and IL-25. In contrast to conventional in vitro screening approaches, we have characterized the activity of these new molecules by direct in vivo analysis and have compared their function to that of other IL-17 family members. Intranasal administration of adenovirus expressing IL-17, IL-17C, or IL-17F resulted in bronchoalveolar lavage neutrophilia and inflammatory gene expression in the lung. In contrast, intranasal administration of IL-25-expressing adenovirus or IL-25 protein resulted in the production of IL-4, IL-5, IL-13, and eotaxin mRNA in the lung and marked eosinophilia in the bronchoalveolar lavage and lung tissue. Mice given intranasal IL-25 also developed epithelial cell hyperplasia, increased mucus secretion, and airway hyperreactivity. IL-25 gene expression was detected following Aspergillus and Nippostrongylus infection in the lung and gut, respectively. IL-25-induced eosinophilia required IL-5 and IL-13, but not IL-4 or T cells. Following IL-25 administration, the IL-5+ staining cells were CD45R/B220+, Thy-1+/−, but were NK1.1-, Ly-6G(GR-1)-, CD4-, CD3-, and c-kit-negative. γ-common knockout mice did not develop eosinophilia in response to IL-25, nor were IL-5+ cells detected. These findings suggest the existence of a previously unrecognized cell population that may initiate Th2-like responses by responding to IL-25 in vivo. Further, these data demonstrate the heterogeneity of function within the IL-17 cytokine family and suggest that IL-25 may be an important mediator of allergic disease via production of IL-4, IL-5, IL-13, and eotaxin.

Characterization of a murine model of allergic pulmonary inflammation.

Pulmonary inflammation with eosinophil (EOs) infiltration is a prominent feature of allergic respiratory diseases such as asthma. In order to study the cellular response during the disease development, an animal model of IgE-mediated pulmonary inflammation with characteristic eosinophilia is needed. We developed a method for inducing severe pulmonary eosinophilia in the mouse and also studied the numbers of EOs in blood and bone marrow and the response to corticosteroid treatment. Animals were sensitized with alum-precipitated ovalbumin (OVA) and challenged with aerosolized OVA 12 days later when serum IgE levels were significantly elevated. Four to eight hours after challenge there were moderate increases in the number of EOs in the bone marrow and peripheral blood, but only a few EOs were observed in the lung tissue and in bronchoalveolar lavage (BAL) fluid. Twenty-four hours after challenge, there was a marked reduction of EOs in bone marrow, while the number of EOs peaked in the perivascular and peribronchial regions of the lung. Forty-eight hours after challenge, the highest number of EOs was found in the BAL fluid, making up > 80% of all cells in that compartment. The high levels of EOs in the lung tissue and BAL fluid lasted for 2-3 days and was followed by a more moderate but persistent eosinophilia for another 10 days. Nonsensitized animals showed no significant changes in the number of EOs in BAL fluid, lungs, blood or bone marrow. Histopathological evaluation also revealed epithelial damage, excessive mucus in the lumen and edema in the submucosa of the airways.(ABSTRACT TRUNCATED AT 250 WORDS)

CXCR2 antagonists for the treatment of pulmonary disease.

Chemokines have long been implicated in the initiation and amplification of inflammatory responses by virtue of their role in leukocyte chemotaxis. The expression of one of the receptors for these chemokines, CXCR2, on a variety of cell types and tissues suggests that these receptors may have a broad functional role under both constitutive conditions and in the pathophysiology of a number of acute and chronic diseases. With the development of several pharmacological, immunological and genetic tools to study CXCR2 function, an important role for this CXC chemokine receptor subtype has been identified in chronic obstructive pulmonary disease (COPD), asthma and fibrotic pulmonary disorders. Interference with CXCR2 receptor function has demonstrated different effects in the lungs including inhibition of pulmonary damage induced by neutrophils (PMNs), antigen or irritant-induced goblet cell hyperplasia and angiogenesis/collagen deposition caused by lung injury. Many of these features are common to inflammatory and fibrotic disorders of the lung. Clinical trials evaluating small molecule CXCR2 antagonists in COPD, asthma and cystic fibrosis are currently underway. These studies hold considerable promise for identifying novel and efficacious treatments of pulmonary disorders.

Th2 cytokines and asthma. The role of interleukin-5 in allergic eosinophilic disease.

Interleukin-5 is produced by a number of cell types, and is responsible for the maturation and release of eosinophils in the bone marrow. In humans, interleukin-5 is a very selective cytokine as a result of the restricted expression of the interleukin-5 receptor on eosinophils and basophils. Eosinophils are a prominent feature in the pulmonary inflammation that is associated with allergic airway diseases, suggesting that inhibition of interleukin-5 is a viable treatment. The present review addresses the data that relate interleukin-5 to pulmonary inflammation and function in animal models, and the use of neutralizing anti-interleukin-5 monoclonal antibodies for the treatment of asthma in humans.

A novel, orally active CXCR1/2 receptor antagonist, sch527123, inhibits neutrophil recruitment, mucus production, and goblet cell hyperplasia in animal models of pulmonary inflammation

Sch527123 [2-hydroxy-N,N-dimethyl-3-[[2-[[1(R)-(5-methyl-2-furanyl)propyl]amino]-3,4-dioxo-1-cyclobuten-1-yl]amino]ben-zamide] is a potent, selective antagonist of the human CXCR1 and CXCR2 receptors (Gonsiorek et al., 2007). Here we describe its pharmacologic properties at rodent CXCR2 and at the CXCR1 and CXCR2 receptors in the cynomolgus monkey, as well as its in vivo activity in models demonstrating prominent pulmonary neutrophilia, goblet cell hyperplasia, and mucus production. Sch527123 bound with high affinity to the CXCR2 receptors of mouse (Kd = 0.20 nM), rat (Kd = 0.20 nM), and cynomolgus monkey (Kd = 0.08 nM) and was a potent antagonist of CXCR2-mediated chemotaxis (IC50 ∼3–6 nM). In contrast, Sch527123 bound to cynomolgus CXCR1 with lesser affinity (Kd = 41 nM) and weakly inhibited cynomolgus CXCR1-mediated chemotaxis (IC50 ∼1000 nM). Oral treatment with Sch527123 blocked pulmonary neutrophilia (ED50 = 1.2 mg/kg) and goblet cell hyperplasia (32–38% inhibition at 1–3 mg/kg) in mice following the intranasal lipopolysaccharide (LPS) administration. In rats, Sch527123 suppressed the pulmonary neutrophilia (ED50 = 1.8 mg/kg) and increase in bronchoalveolar lavage (BAL) mucin content (ED50 =<0.1 mg/kg) induced by intratracheal (i.t.) LPS. Sch527123 also suppressed the pulmonary neutrophilia (ED50 = 1.3 mg/kg), goblet cell hyperplasia (ED50 = 0.7 mg/kg), and increase in BAL mucin content (ED50 = <1 mg/kg) in rats after i.t. administration of vanadium pentoxide. In cynomolgus monkeys, Sch527123 reduced the pulmonary neutrophilia induced by repeat bronchoscopy and lavage (ED50 = 0.3 mg/kg). Therefore, Sch527123 may offer benefit for the treatment of inflammatory lung disorders in which pulmonary neutrophilia and mucus hypersecretion are important components of the underlying disease pathology.

Biology of interleukin-5 and its relevance to allergic disease

While bronchoconstriction associated with an acute attack is the most prominent feature of asthma, chronic inflammation is the underlying cause (1, 2, 3). Therefore, considerable attention has been focused on the role of chronic pulmonary inflammation in the pathophysiology of asthma, especially as it relates to ongoing airway hyperreactivity. Pulmonary inflammation is characterized by edema, decreased mucociliary clearance, epithelial damage, increased neuronal responsiveness, and bronchoalveolar eosinophilia (2). There are small numbers of eosinophils in the lung tissue of normal subjects, but they accumulate noticeably in the lungs of patients with asthma (2). Eosinophils are produced in the bone marrow from myeloid precursors in response to cytokine activation, and are released from the bone marrow by an appropriate stimulus. Once in the circulation, they rapidly accumulate in tissue, both in the human and in animal models ( 1, 4). Activated eosinophils synthesize and release lipid mediators that can cause edema, bronchoconstriction, and chemotaxis (1). They also secrete enzymes and proteins that can lyse epithelial tissue and are found in the lungs of patients with asthma ( 5 ) . Furthermore, the role of the eosinophil as a protective agent against parasitic infection is somewhat limited (6). Therefore, the eosinophil is an ideal target for selectively inhibiting the tissue damage that accompanies pulmonary inflammation during asthma, without inducing the immunosuppressive consequences that would arise from inhibiting the actions of other inflammatory cells. relevance to

Peripheral and central sites of action of GABA-B agonists to inhibit the cough reflex in the cat and guinea pig.

1 The GABA‐B receptor agonists baclofen and 3‐aminopropylphosphinic acid (3‐APPi) have antitussive activity in the cat and guinea pig. The purpose of this study was to investigate the sites of action of these GABA‐B receptor agonists to inhibit the cough reflex. 2 Single intracerebroventricular (i.e.v.) cannulas were placed in the lateral ventricles of anaesthetized guinea pigs. Approximately 1 week later, the animals were exposed to aerosols of capsaicin (0.3 μm) to elicit coughing. Coughs were detected with a microphone and counted. 3 Cough was produced in anaesthetized cats by mechanical stimulation of the intrathoracic trachea and was recorded from electromyograms of respiratory muscle activity. Cannulas were placed for intravenous (i.v.) or, in separate groups of animals, intravertebral arterial (i.a.) administration of baclofen, 3‐APPi, the centrally active antitussive drug codeine or the peripherally active antitussive drug BW443c. Dose‐response relationships for i.v. and i.a. administration of each drug were generated to determine a ratio of i.v. ED50 to i.a. ED50, known as the effective dose ratio (EDR). The EDR will be 20 or greater for a centrally acting drug. 4 In the guinea pig, baclofen (3 mg kg−1, s.c.) and 3‐APPi (10 mg kg−1, s.c.) inhibited capsaicin‐induced cough by 50% and 35% respectively. The antitussive activity of baclofen was completely blocked by i.e.v. administration of the GABA‐B receptor antagonist CGP 35348 (10 μg). Conversely, the antitussive effect of 3‐APPi was unaffected by i.e.v. CGP 35348. However, systemic administration of CGP 35348 (30 mg kg−1, s.c.) completely blocked the antitussive activity of 3‐APPi (10 mg kg−1, s.c). In separate experiments baclofen alone (1 μg, i.c.v.) inhibited capsaicin‐induced cough by 78%. 3‐APPi (10 and 100 μg, i.c.v.) had no effect on capsaicin‐induced cough in the guinea pig. 5 In the cat, potencies (ED50) of the standards and GABA‐B agonists by the i.v. route were: codeine (0.34 mg kg−1), BW443C (0.17 mg kg−1), baclofen (0.63 mg kg−1) and 3‐APPi (2.3 mg kg−1). Potencies of these drugs by the i.a. route were: codeine, 0.013 mg kg−1; BW443C, 0.06 mg kg−1; baclofen, 0.016 mg kg−1; and 3‐APPi, 0.87 mg kg−1. The EDRs for each drug were: codeine, 26; BW443C, 3; baclofen, 39; and 3‐APPi, 3. 6 We conclude that in both the cat and guinea pig baclofen inhibits cough by a central site of action, while 3‐APPi inhibits cough by a peripheral site of action.

GABAB receptors in the lung

gamma-Aminobutyric acid (GABA), an important inhibitory neurotransmitter in the mammalian CNS, is also found in peripheral tissues, including the lung. Recent pharmacological studies using selective ligands for GABAA and GABAB receptors demonstrate that of these two, the GABAB receptor is the important receptor subtype controlling lung functions. GABAB agonists inhibit a variety of responses in the airways, including neuronally induced cholinergic- and tachykinin-mediated smooth muscle contraction, microvascular leakage, anaphylactic bronchospasm and cough. Because these conditions are seen in certain respiratory diseases, such as asthma, a selective GABAB agonist may have therapeutic potential for the treatment of this respiratory disorder.

Antiallergic activity of loratadine, a non-sedating antihistamine.

Loratadine is a new non‐sedating antihistamine. The present studies compared loratadine and terfenadine, another non‐sedating antihistamine, for their ability to inhibit the bronchial response to histamine and other autacoids which have been implicated as contributing to the symptoms of an allergic reaction. In addition, the two antihistamines were evaluated in models of immunologically mediated allergic reactions. Loratadine is a more potent inhibitor of histamine‐induced bronchospasm in guinea pigs than is terfenadine. Both antihistamines exhibit marked antiserotonin activity at doses 10 times their antihistamine ED50 values. In contrast, loratadine and terfenadine produce little or no inhibition of the bronchial responses to methacholine, leukotriene C4 or platelet‐activating factor. An allergic bronchospasm in guinea pigs is inhibited by loratadine (ED50= 0.40 mg/kg, p.o.) and terfenadine (ED50= 1.7 mg/kg, p.o.). The bronchospasm associated with allergic anaphylaxis in rats is significantly inhibited by 10 mg/kg, p.o. loratadine and 30 mg/kg, p.o. terfenadine. Loratadine exhibits antiallergy activity in vitro. At micromolar concentrations, loratadine inhibits the release of histamine from Con A and A23187‐stimulated rat peritoneal mast cells and the release of histamine and leukotrine C4 from a Con A‐stimulated cloned murine mast cell line

Inhibition of sympathetic hypertensive responses in the guinea-pig by prejunctional histamine H3-receptors

1 The effect of (R)‐α‐methylhistamine, a selective H3‐histamine receptor agonist, was examined on the neurogenic hypertension and tachycardia that is induced by stimulation of areas in the medulla oblongata of guinea‐pigs. Electrical medullary stimulation (32 Hz, 3–5 s trains, 0.5–1.0 ms square pulse, 25–400 μA) produced intensity‐dependent increases in blood pressure and a more variable tachycardia. 2 (R)‐α‐methylhistamine inhibited the hypertension and tachycardia due to submaximal CNS stimulation. The inhibition of hypertension by (R)‐α‐methylhistamine was dose‐dependent (10–300 μg kg−1, i.v.) and was not seen at high intensities of stimulation. 3 (R)‐α‐methylhistamine (300 μg kg−1, i.v.) did not attenuate the pressor response to adrenaline (1 and 3 μg kg−1, i.v.), indicating that the effect of (R)‐α‐methylhistamine was not mediated by a postjunctional action on smooth muscle. 4 The inhibition of CNS‐induced hypertension by (R)‐α‐methylhistamine (300 μg kg−1, i.v.) was blocked by the H3 antagonists, thioperamide (ID50 = 0.39 mg kg−1, i.v.), impromidine (ID50 = 0.22 mg kg−1, i.v.) and burimamide (ID50 = 6 mg kg−1, i.v.). The rank order potency of these antagonists is consistent with activity at the H3B receptor subtype. Chlorpheniramine (30 μg kg−1, i.v.) and cimetidine (3 mg kg−1, i.v.) did not antagonize the inhibition of CNS‐hypertension by (R)‐α‐methylhistamine. 5 These results suggest that (R)‐α‐methylhistamine inhibits sympathetic hypertensive responses in guinea‐pigs by activation of prejunctional H3‐receptors, possibly located on postganglionic nerve terminals. Furthermore, on the basis of the rank order potency to different H3‐antagonists, it appears that the H3B‐receptor subtype is involved with H3‐receptor responses on vascular sympathetic nerves.