RESUMO
Based on in house screening lead compound 1 for the NAR project, SAR studies have been focused on the modification of the C2 ethers of the pyrimidinedione core structure. In this effort, an unpredictable SAR trend was overcome in the alkyl ether and arylalkyl ether series to identify compound 24 with improved in vitro activity compared to nicotinic acid. More consistent and predictable SAR was achieved in the propargyl ether series. Lead compound 41 was identified with good in vitro and in vivo activity in rat, and much improved rat PK profile.
Assuntos
Éteres/farmacologia , Lactonas/farmacologia , Pirimidinas/farmacologia , Receptores Nicotínicos/metabolismo , Éteres/síntese química , Éteres/química , Humanos , Lactonas/síntese química , Lactonas/química , Estrutura Molecular , Pirimidinas/síntese química , Pirimidinas/química , Relação Estrutura-AtividadeRESUMO
The neuromodulatory action of the tachykinin NK(3)-receptor agonist [MePhe(7)]-neurokinin B ([MePhe(7)]-NKB) was evaluated on vagal stimulation-induced bronchoconstriction in nonsensitized nonchallenged and ovalbumin (OVA)-sensitized and -challenged guinea pig using the isolated perfused lung preparation. Lungs were placed inside a warmed (37°C) glass chamber and suspended from a force displacement transducer (Grass FT-03) with both vagi connected to a stimulating electrode. Isolated lungs were stimulated at a constant voltage (20 V) and pulse duration (5 ms) with electrical stimulation frequencies ranging from 1 to 128 Hz. The authors demonstrated that vagal stimulation produced frequency-dependent bronchoconstriction and [MePhe(7)]-NKB, at a dose (0.1 µM) that does not produce bronchoconstriction by itself, potentiated the vagally induced bronchoconstriction at all frequencies in nonsensitized nonchallenged animals and to a greater extent in OVA-sensitized and -challenged guinea pigs; the potentiations were totally inhibited by the tachykinin NK(3)-receptor antagonist SR 142801 (1 µM). In a second set of experiments, [MePhe(7)]-NKB produced bronchoconstriction in a dose-dependent (1 to 300 µg/mL) manner with similar potencies and maximum responses in nonsensitized nonchallenged (EC(50) = 8.6 ± 1.1 µM; E(Max) = 61.1 ± 3.5 mm Hg) and OVA-sensitized and -challenged (EC(50) = 8.5 ± 1.3 µM; E(Max) = 63.5 ± 3.7 mm Hg) animals. In conclusion, these results demonstrated that [MePhe(7)]-NKB potentiated vagal stimulation-induced bronchoconstriction via the tachykinin NK(3)-receptors and OVA sensitization caused development of airway hyperresponsiveness in these potentiations. However, OVA sensitization had no effect on airway responsiveness of vagal stimulation-and [MePhe(7)]-NKB-induced bronchoconstrictions.
Assuntos
Pulmão/efeitos dos fármacos , Neurocinina B/análogos & derivados , Neurotransmissores/farmacologia , Ovalbumina/farmacologia , Receptores da Neurocinina-3/agonistas , Receptores da Neurocinina-3/metabolismo , Animais , Broncoconstrição/efeitos dos fármacos , Broncoconstrição/fisiologia , Eletrodos , Cobaias , Pulmão/metabolismo , Pulmão/fisiologia , Masculino , Neurocinina A/metabolismo , Neurocinina B/metabolismo , Neurocinina B/farmacologia , Piperidinas/farmacologia , Receptores da Neurocinina-2/metabolismo , Receptores de Taquicininas/metabolismo , Nervo Vago/efeitos dos fármacos , Nervo Vago/metabolismo , Estimulação do Nervo Vago/métodosRESUMO
For decades, the focus of therapy to mitigate cardiovascular risk has been to lower low density lipoprotein cholesterol (LDL-C), so called "bad cholesterol". Widespread use of statins has resulted in a large body of clinical experience, which indicates that lower LDL-C levels do indeed correlate with decreased risk of cardiovascular and coronary artery diseases (CVD and CAD). Given these findings, recommended targets for LDL-C levels are continually being revised lower. Interestingly, however, even at low LDL-C levels there remains a substantial residual risk of CVD and CAD, particularly in patients with additional contributing factors. Recent post-hoc analyses of several large lipid modulation trials specifically assessing high density lipoprotein cholesterol (HDL-C) have revealed that increased HDL-C levels confer additional benefit against risk of CVD and CAD, even when LDL-C levels are already low. Human clinical outcomes trials that specifically target increasing HDL-C have not yet been conducted. However, the strong epidemiological inverse correlation between HDL-C and CVD risk remains. Discovery efforts aimed at increasing circulating levels of HDL-C have increased dramatically in recent years. This review will cover recent efforts and agents being developed such as cholesterol ester transfer protein inhibitors and nicotinic acid receptor agonists among other potential strategies.
Assuntos
Doenças Cardiovasculares/tratamento farmacológico , HDL-Colesterol/metabolismo , Anticolesterolemiantes/uso terapêutico , Proteínas de Transferência de Ésteres de Colesterol/antagonistas & inibidores , HDL-Colesterol/sangue , HDL-Colesterol/efeitos dos fármacos , LDL-Colesterol/sangue , LDL-Colesterol/metabolismo , Doença da Artéria Coronariana/tratamento farmacológico , Doença da Artéria Coronariana/etiologia , Doença da Artéria Coronariana/prevenção & controle , Humanos , Hipolipemiantes/uso terapêutico , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Acoplados a Proteínas G/agonistas , Fatores de RiscoRESUMO
The very high occurrence of cardiovascular events presents a major public health issue, because treatment remains suboptimal. Lowering LDL cholesterol (LDL-C) with statins or ezetimibe in combination with a statin reduces major adverse cardiovascular events. The cardiovascular risk reduction in relation to the absolute LDL-C reduction is linear for most interventions without evidence of attenuation or increase in risk at low LDL-C levels. Opportunities for innovation in dyslipidaemia treatment should address the substantial risk of lipid-associated cardiovascular events among patients optimally treated per guidelines but who cannot achieve LDL-C goals and who could benefit from additional LDL-C-lowering therapy or experience side effects of statins. Fresh approaches are needed to identify promising drug targets early and develop them efficiently. The Cardiovascular Round Table of the European Society of Cardiology (ESC) convened a workshop to discuss new lipid-lowering strategies for cardiovascular risk reduction. Opportunities to improve treatment approaches and the efficient study of new therapies were explored. Circulating biomarkers may not be fully reliable proxy indicators of the relationship between treatment effect and clinical outcome. Mendelian randomization studies may better inform development strategies and refine treatment targets before Phase 3. Trials should match the drug to appropriate lipid and patient profile, and guidelines may move towards a precision-based approach to individual patient management. Stakeholder collaboration is needed to ensure continued innovation and better international coordination of both regulatory aspects and guidelines. It should be noted that risk may also be addressed through increased attention to other risk factors such as smoking, hypertension, overweight, and inactivity.
Assuntos
Cardiologia/normas , Doenças Cardiovasculares , Desenvolvimento de Medicamentos/normas , Hipolipemiantes/uso terapêutico , Lipídeos/sangue , Guias de Prática Clínica como Assunto , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Saúde Global , Humanos , Incidência , Fatores de RiscoRESUMO
Current asthma therapy is directed at the relief of chronic inflammation or improving lung function through bronchodilation. These approaches treat the overt symptoms of asthma but do not approach underlying causes of the disease. Such therapies have limited efficacy and for a number of patients the disease remains poorly controlled. The short-term future of asthma therapy will probably focus on the treatment of multiple symptoms to provide improved lung function. Long-term approaches to asthma will have to focus on modulation of the mechanisms that are the underlying causes of the various asthmatic pathophysiologies. These targets include a number of TH2-type T-cell-generated cytokines and chemokines, G-protein-coupled receptors, TH2-related transcription factors, neurotrophins and adhesion molecules. Additional new targets and understanding of asthma may also arise from genetic analysis.
Assuntos
Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Animais , Antiasmáticos/imunologia , Antiasmáticos/farmacologia , Asma/genética , Asma/imunologia , Citocinas/farmacologia , Sistemas de Liberação de Medicamentos , Avaliação de Medicamentos , Humanos , Imunidade Celular , Células Th2RESUMO
We have characterized desloratadine (5H-benzo[5,6]cyclohepta[1,2-b]pyridine, 8-chloro-6,11-dihydro-11-(4-piperidinylidene), CAS 100643-71-8) as a potent antagonist of the human histamine H(1) receptor. [3H]Desloratadine bound to membranes expressing the recombinant human histamine H(1) receptor in Chinese hamster ovary cells (CHO-H(1)) in a specific and saturable manner with a K(d) of 1.1+/-0.2 nM, a B(max) of 7.9+/-2.0 pmol/mg protein, and an association rate constant of 0.011 nM(-1) x min(-1). The K(d) calculated from the kinetic measurements was 1.5 nM. Dissociation of [3H]desloratadine from the human histamine H(1) receptor was slow, with only 37% of the binding reversed at 6 h in the presence of 5 microM unlabeled desloratadine. Seventeen histamine H(1)-receptor antagonists were evaluated in competition-binding studies. Desloratadine had a K(i) of 0.9+/-0.1 nM in these competition studies. In CHO-H(1) cells, histamine stimulation resulted in a concentration-dependent increase in [Ca(2+)](i) with an EC(50) of 170+/-30 nM. After a 90-min preincubation with desloratadine, the histamine-stimulated increase in [Ca(2+)](i) was shifted to the right, with a depression of the maximal response at higher concentrations of antagonist. The apparent K(b) value was 0.2+/-0.14 nM with a slope of 1.6+/-0.1. The slow dissociation from the receptor and noncompetitive antagonism suggests that desloratadine may be a pseudoirreversible antagonist of the human histamine H(1) receptor. The mechanism of desloratadine antagonism of the human histamine H(1) receptor may help to explain the high potency and 24-h duration of action observed in clinical studies.
Assuntos
Antagonistas dos Receptores Histamínicos H1/farmacologia , Loratadina/análogos & derivados , Loratadina/farmacologia , Receptores Histamínicos H1/efeitos dos fármacos , Animais , Ligação Competitiva/efeitos dos fármacos , Células CHO , Cálcio/metabolismo , Clonagem Molecular , Cricetinae , Primers do DNA/farmacologia , Feminino , Antagonistas dos Receptores Histamínicos H1/metabolismo , Humanos , Cinética , Loratadina/metabolismo , Oligonucleotídeos Antissenso/farmacologia , Pirilamina/metabolismo , Receptores Histamínicos H1/metabolismoRESUMO
Experiments were performed to characterize the pharmacology of SCH 206272 [(R,R)-1'[5-[(3,5-dichlorobenzoyl)methylamino]-3-(3,4-dichlorophenyl)-4(Z)-(methoxyimino)pentyl]-N-methyl-2-oxo-[1,4'bipiperidine]-3-acetamide] as a potent and selective antagonist of tachykinin (NK) NK(1), NK(2), and NK(3) receptors. SCH 206272 inhibited binding at human tachykinin NK(1), NK(2), and NK(3) receptors (K(i) = 1.3, 0.4, and 0.3 nM, respectively) and antagonized [Ca(2+)](i) mobilization in Chinese hamster ovary (CHO) cells expressing the cloned human tachykinin NK(1), NK(2), or NK(3) receptors. SCH 206272 inhibited relaxation of the human pulmonary artery (pK(b) = 7.7 +/- 0.3) induced by the tachykinin NK(1) receptor agonist, [Met-O-Me] substance P and contraction of the human bronchus (pK(b = 8.2 +/- 0.3) induced by the tachykinin NK(2) receptor agonist, neurokinin A. In isolated guinea pig tissues, SCH 206272 inhibited substance P-induced enhancement of electrical field stimulated contractions of the vas deferens, (pK(b = 7.6 +/- 0.2), NKA-induced contraction of the bronchus (pK(b) = 7.7 +/- 0.2), and senktide-induced contraction of the ileum. In vivo, oral SCH 206272 (0.1-10 mg/kg, p.o.) inhibited substance P-induced airway microvascular leakage and neurokinin A-induced bronchospasm in the guinea pig. In a canine in vivo model, SCH 206272 (0.1-3 mg/kg, p.o.) inhibited NK(1) and NK(2) activities induced by exogenous substance P and neurokinin A. Furthermore, in guinea pig models involving endogenously released tachykinins, SCH 206272 inhibited hyperventilation-induced bronchospasm, capsaicin-induced cough, and airway microvascular leakage induced by nebulized hypertonic saline. These data demonstrate that SCH 206272 is a potent, orally active tachykinin NK(1), NK(2), and NK(3) receptor antagonist. This compound may have beneficial effects in diseases thought to be mediated by tachykinins, such as cough, asthma, and chronic obstructive pulmonary disease.
Assuntos
Acetamidas/farmacologia , Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/farmacologia , Receptores da Neurocinina-2/antagonistas & inibidores , Receptores da Neurocinina-3/antagonistas & inibidores , Administração Oral , Animais , Broncoconstrição/efeitos dos fármacos , Broncoconstrição/fisiologia , Células CHO , Permeabilidade Capilar , Capsaicina/farmacologia , Tosse/induzido quimicamente , Tosse/tratamento farmacológico , Cricetinae , Cães , Relação Dose-Resposta a Droga , Cobaias , Humanos , Íleo/efeitos dos fármacos , Íleo/fisiologia , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Artéria Pulmonar/efeitos dos fármacos , Artéria Pulmonar/fisiologia , Ensaio Radioligante , Receptores da Neurocinina-1/metabolismo , Receptores da Neurocinina-2/metabolismo , Receptores da Neurocinina-3/metabolismo , Ducto Deferente/efeitos dos fármacos , Ducto Deferente/fisiologiaRESUMO
The Transient Receptor Potential cation channel V1 (TRPV1) is expressed in peripheral nociceptive neurons and is subject to polymodal activation via various agents including capsaicin, noxious heat, low extracellular pH, and direct phosphorylation by protein kinase C (PKC). We have cloned and heterologously expressed mouse TRPV1 (mTRPV1) and characterized its function utilizing FLIPR-based calcium imaging to measure functional responses to various small molecule agonists, low pH and direct phosphorylation via PKC. The various TRPV1 agonists activated mTRPV1 with a rank order of agonist potency of (resiniferatoxin (RTX) = arvanil > capsaicin = olvanil > OLDA > PPAHV) (EC50 values of 0.15+/-0.04 nM, 0.27+/-0.07 nM, 9.1+/-1.2 nM, 3.7+/-0.3 nM, 258+/-105 nM, and 667+/-151 nM, respectively). Additionally, mTRPV1 was activated by either low pH or with addition of the PKC activator phorbol 12-myristate 13-acetate (PMA). The TRPV1 antagonists iodinated-resiniferatoxin (I-RTX) or BCTC were both able to block capsaicin, pH and PKC-induced responses of mTRPV1 (IC50 (I-RTX) = 0.35+/-0.12 nM, 1.9+/-0.7 nM, and 0.80+/-0.68 nM, IC50 (BCTC) = 1.3+/-0.36 nM, 0.59+/-0.16 nM, and 0.37+/-0.15 nM, respectively). However, the antagonist capsazepine was only able to inhibit a capsaicin-evoked response of mTRPV1 with an IC50 of 1426+/-316 nM. Comparable results were achieved with rat TRPV1, while capsazepine blocked all modes of human TRPV1 activation. Thus, the mTRPV1 cation channel has a molecular pharmacological profile more akin to rat TRPV1 than either human or guinea pig TRPV1 and the molecular pharmacology suggests that capsazepine may be an ineffective TRPV1 antagonist for in vivo models of inflammatory pain in the mouse.
Assuntos
Canais Iônicos/genética , Receptores de Droga/fisiologia , Sequência de Aminoácidos , Animais , Cálcio/metabolismo , Capsaicina/agonistas , Capsaicina/farmacologia , Linhagem Celular , Clonagem Molecular , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Diterpenos/farmacologia , Ativação Enzimática/efeitos dos fármacos , Cobaias , Humanos , Concentração de Íons de Hidrogênio , Concentração Inibidora 50 , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Canais Iônicos/fisiologia , Camundongos , Ésteres de Forbol/farmacologia , Fosforilação/efeitos dos fármacos , RNA Mensageiro/biossíntese , Coelhos , Ratos , Receptores de Droga/agonistas , Receptores de Droga/antagonistas & inibidores , Receptores de Droga/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Canais de Cátion TRPV , Transfecção/métodosRESUMO
Mast cells are the central mediating cells of allergic reactions. Binding of allergen specific IgE to high affinity IgE receptor (Fcepsilon RI) and subsequent binding of allergen by the IgE causes receptor cross-linking and activation. In a study examining the differential gene expression in human cord blood-derived mast cells (CBMCs) mediated by activation of Fcepsilon RI both with IgE and IgE followed by cross-linking with alpha-IgE, the chemokine I-309 was found to be upregulated. I-309 is the ligand for the CCR8 receptor and is responsible for chemoattraction of TH2 type T-cells. Interestingly, I-309 RNA and protein levels were elevated not only in response to IgE/alpha-IgE activation but also by IgE alone. In addition, the I-309 levels were augmented by growth of the CBMCs in the presence of the proinflammatory cytokine IL-4. GM-CSF and MIP-1alpha secretion was also induced by IgE. These results suggest that IgE, through the production and release of cytokines such as I-309, GM-CSF and MIP-1alpha could promote an inflammatory reaction in the absence of antigen stimulation of mast cells.
Assuntos
Quimiocinas CC/metabolismo , Sangue Fetal/citologia , Imunoglobulina E/farmacologia , Mastócitos/fisiologia , Quimiocina CCL1 , Quimiocinas/metabolismo , Reagentes de Ligações Cruzadas , Citocinas/metabolismo , Primers do DNA , Expressão Gênica , Histamina/metabolismo , Liberação de Histamina/efeitos dos fármacos , Humanos , Interleucina-4/biossíntese , Interleucina-4/genética , Análise de Sequência com Séries de Oligonucleotídeos , Receptores CCR8 , Receptores de Quimiocinas/metabolismo , Receptores de IgE/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Structure-guided optimization of a series of C-5 alkyl substituents led to the discovery of a potent nicotinic acid receptor agonist SCH 900271 (33) with an EC50 of 2 nM in the hu-GPR109a assay. Compound 33 demonstrated good oral bioavailability in all species. Compound 33 exhibited dose-dependent inhibition of plasma free fatty acid (FFA) with 50% FFA reduction at 1.0 mg/kg in fasted male beagle dogs. Compound 33 had no overt signs of flushing at doses up to 10 mg/kg with an improved therapeutic window to flushing as compared to nicotinic acid. Compound 33 was evaluated in human clinical trials.
RESUMO
BACKGROUND: Obesity and inflammation are highly integrated processes in the pathogenesis of insulin resistance, diabetes, dyslipidemia, and non-alcoholic fatty liver disease. Molecular mechanisms underlying inflammatory events during high fat diet-induced obesity are poorly defined in mouse models of obesity. This work investigated gene activation signals integral to the temporal development of obesity. METHODS: Gene expression analysis in multiple organs from obese mice was done with Taqman Low Density Array (TLDA) using a panel of 92 genes representing cell markers, cytokines, chemokines, metabolic, and activation genes. Mice were monitored for systemic changes characteristic of the disease, including hyperinsulinemia, body weight, and liver enzymes. Liver steatosis and fibrosis as well as cellular infiltrates in liver and adipose tissues were analyzed by histology and immunohistochemistry. RESULTS: Obese C57BL/6 mice were fed with high fat and cholesterol diet (HFC) for 6, 16 and 26 weeks. Here we report that the mRNA levels of macrophage and inflammation associated genes were strongly upregulated at different time points in adipose tissues (6-16 weeks) and liver (16-26 weeks), after the start of HFC feeding. CD11b+ and CD11c+ macrophages highly infiltrated HFC liver at 16 and 26 weeks. We found clear evidence that signals for IL-1ß, IL1RN, TNF-α and TGFß-1 are present in both adipose and liver tissues and that these are linked to the development of inflammation and insulin resistance in the HFC-fed mice. CONCLUSIONS: Macrophage infiltration accompanied by severe inflammation and metabolic changes occurred in both adipose and liver tissues with a temporal shift in these signals depending upon the duration of HFC feeding. The evidences of gene expression profile, elevated serum alanine aminotransferase, and histological data support a progression towards nonalcoholic fatty liver disease and steatohepatitis in these HFC-fed mice within the time frame of 26 weeks.
RESUMO
Nicotinic acid has been used clinically for decades to control serum lipoproteins. Nicotinic acid lowers very low-density lipoprotein (VLDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, and lipoprotein-a (LPa), and it is also effective in raising high-density lipoprotein (HDL)-cholesterol. However, nicotinic acid has several side effects in clinical use. The most notable is intense cutaneous vasodilation "flushing" on the upper body and face. We discovered a pyranopyrimidinedione series to be nicotinic acid receptor agonists. A potent nicotinic acid receptor agonist from this series {5-(3-cyclopropylpropyl)-2-(difluoromethyl)-3H-pyrano[2,3-d]pyrimidine-4,7-dione}with reduced flushing side effect in dogs was identified.
RESUMO
In this study, we present the identification and characterization of hamster and guinea pig nicotinic acid receptors. The hamster receptor shares approximately 80-90% identity with the nucleotide and amino acid sequences of human, mouse, and rat receptors. The guinea pig receptor shares 76-80% identity with the nucleotide and amino acid sequences of these other species. [(3)H]nicotinic acid binding affinity at guinea pig and hamster receptors is similar to that in human (dissociation constant = 121 nM for guinea pig, 72 nM for hamster, and 74 nM for human), as are potencies of nicotinic acid analogs in competition binding studies. Inhibition of forskolin-stimulated cAMP production by nicotinic acid and related analogs is also similar to the activity in the human receptor. Analysis of mRNA tissue distribution for the hamster and guinea pig nicotinic acid receptors shows expression across a number of tissues, with higher expression in adipose, lung, skeletal muscle, spleen, testis, and ovary.
Assuntos
Receptores Nicotínicos/isolamento & purificação , Receptores Nicotínicos/metabolismo , Sequência de Aminoácidos , Animais , Células CHO , Clonagem Molecular , Cricetinae , Cricetulus , Cobaias , Humanos , Dados de Sequência Molecular , Niacina/metabolismo , Alinhamento de SequênciaRESUMO
The P2X7 channel is a member of the P2X family of ligand-gated ion channels which respond to ATP as the endogenous agonist. Studies suggest that P2X7 has a potentially pivotal role in inflammatory responses largely stemming from its role in mediating the release of IL-1beta in response to ATP. We report the identification of seven variants of human P2X7 which result from alternative splicing. Two of these variants (one lacking the first transmembrane domain, the second lacking the entire cytoplasmic tail) were compared to the full-length channel. Real-time PCR analysis demonstrated that both variants were expressed in various tissues and that the cytoplasmic tail deleted variant is highly expressed. Deletion of the first transmembrane domain resulted in a non-functional channel. Deletion of the cytoplasmic tail did not affect ion movement but severely affected the ability to form a large pore and to induce activation of caspases.
Assuntos
Trifosfato de Adenosina/metabolismo , Receptores Purinérgicos P2/química , Receptores Purinérgicos P2/metabolismo , Processamento Alternativo/genética , Sequência de Aminoácidos , Substituição de Aminoácidos , DNA Recombinante/genética , Variação Genética/genética , Humanos , Canais Iônicos/análise , Canais Iônicos/química , Canais Iônicos/genética , Canais Iônicos/metabolismo , Dados de Sequência Molecular , Especificidade de Órgãos , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Receptores Purinérgicos P2/análise , Receptores Purinérgicos P2/genética , Receptores Purinérgicos P2X7 , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , Distribuição TecidualRESUMO
BACKGROUND: The role of IL-5-induced eosinophilia in airway hyperresponsiveness has been questioned. In addition, eosinophil-independent IL-5-induced airway hyperresponsiveness has been demonstrated in animals. OBJECTIVE: In this study, IL-5 was investigated for direct effects on human bronchial responsiveness. METHODS: Human muscle preparations were isolated from organ donor and surgical tissue. Bronchus, jejunum, and saphenous vein were incubated for 24 hours in vitro with recombinant human (rh) IL-5. Contractility to acetylcholine (bronchus, jejunum) and phenylephrine (saphenous vein) was then investigated. RT-PCR was used to evaluate IL-5 receptor alpha (IL-5R(alpha)) expression in various tissues and to assess bronchus and saphenous vein eosinophils through use of CCR3 expression. RESULTS: rhIL-5 primed bronchus for an exaggerated contraction to acetylcholine. The acetylcholine concentration that produced 50% of the control maximum response was reduced 17- to 20-fold in bronchus treated with 1 and 10 nmol/L rhIL-5. The lower concentration of 0.1 nmol/L rhIL-5 had no effect. The rhIL-5 effect on bronchial contractility was attenuated by antibodies to IL-5 (TRFK-5; 100 nmol/L) and human IL-5R(alpha) (100 nmol/L). rhIL-5 (10 nmol/L) did not enhance contractility of saphenous vein or jejunum. When RT-PCR was used, IL-5R(alpha) expression was strong in bronchus muscle, weak in trachealis, saphenous vein, and atrial muscle, and undetectable in jejunum, urinary bladder, and pulmonary and renal artery muscle. Comparable weak expression of CCR3 was identified in bronchus and saphenous vein. CONCLUSION: The findings are consistent with an airway tissue-selective expression of the IL-5 receptor that mediates IL-5-induced airway hyperresponsiveness independent of eosinophils. In asthma, in which IL-5 expression is elevated, IL-5 might directly induce bronchial hyperresponsiveness.