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Second M3 muscarinic receptor binding site contributes to bronchoprotection by tiotropium.
Br J Pharmacol 2019; 176(16):2864-2876BJ

Abstract

BACKGROUND AND PURPOSE

The bronchodilator tiotropium binds not only to its main binding site on the M3 muscarinic receptor but also to an allosteric site. Here, we have investigated the functional relevance of this allosteric binding and the potential contribution of this behaviour to interactions with long-acting β-adrenoceptor agonists, as combination therapy with anticholinergic agents and β-adrenoceptor agonists improves lung function in chronic obstructive pulmonary disease.

EXPERIMENTAL APPROACH

ACh, tiotropium, and atropine binding to M3 receptors were modelled using molecular dynamics simulations. Contractions of bovine and human tracheal smooth muscle strips were studied.

KEY RESULTS

Molecular dynamics simulation revealed extracellular vestibule binding of tiotropium, and not atropine, to M3 receptors as a secondary low affinity binding site, preventing ACh entry into the orthosteric binding pocket. This resulted in a low (allosteric binding) and high (orthosteric binding) functional affinity of tiotropium in protecting against methacholine-induced contractions of airway smooth muscle, which was not observed for atropine and glycopyrrolate. Moreover, antagonism by tiotropium was insurmountable in nature. This behaviour facilitated functional interactions of tiotropium with the β-agonist olodaterol, which synergistically enhanced bronchoprotective effects of tiotropium. This was not seen for glycopyrrolate and olodaterol or indacaterol but was mimicked by the interaction of tiotropium and forskolin, indicating no direct β-adrenoceptor-M3 receptor crosstalk in this effect.

CONCLUSIONS AND IMPLICATIONS

We propose that tiotropium has two binding sites at the M3 receptor that prevent ACh action, which, together with slow dissociation kinetics, may contribute to insurmountable antagonism and enhanced functional interactions with β-adrenoceptor agonists.

Authors+Show Affiliations

Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.Department of Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.Immunology and Respiratory Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.Department of Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31077341

Citation

Kistemaker, Loes E M., et al. "Second M3 Muscarinic Receptor Binding Site Contributes to Bronchoprotection By Tiotropium." British Journal of Pharmacology, vol. 176, no. 16, 2019, pp. 2864-2876.
Kistemaker LEM, Elzinga CRS, Tautermann CS, et al. Second M3 muscarinic receptor binding site contributes to bronchoprotection by tiotropium. Br J Pharmacol. 2019;176(16):2864-2876.
Kistemaker, L. E. M., Elzinga, C. R. S., Tautermann, C. S., Pieper, M. P., Seeliger, D., Alikhil, S., ... Gosens, R. (2019). Second M3 muscarinic receptor binding site contributes to bronchoprotection by tiotropium. British Journal of Pharmacology, 176(16), pp. 2864-2876. doi:10.1111/bph.14707.
Kistemaker LEM, et al. Second M3 Muscarinic Receptor Binding Site Contributes to Bronchoprotection By Tiotropium. Br J Pharmacol. 2019;176(16):2864-2876. PubMed PMID: 31077341.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Second M3 muscarinic receptor binding site contributes to bronchoprotection by tiotropium. AU - Kistemaker,Loes E M, AU - Elzinga,Carolina R S, AU - Tautermann,Christofer S, AU - Pieper,Michael P, AU - Seeliger,Daniel, AU - Alikhil,Suraya, AU - Schmidt,Martina, AU - Meurs,Herman, AU - Gosens,Reinoud, Y1 - 2019/07/02/ PY - 2018/04/16/received PY - 2019/04/16/revised PY - 2019/04/29/accepted PY - 2020/08/01/pmc-release PY - 2019/5/12/pubmed PY - 2019/5/12/medline PY - 2019/5/12/entrez SP - 2864 EP - 2876 JF - British journal of pharmacology JO - Br. J. Pharmacol. VL - 176 IS - 16 N2 - BACKGROUND AND PURPOSE: The bronchodilator tiotropium binds not only to its main binding site on the M3 muscarinic receptor but also to an allosteric site. Here, we have investigated the functional relevance of this allosteric binding and the potential contribution of this behaviour to interactions with long-acting β-adrenoceptor agonists, as combination therapy with anticholinergic agents and β-adrenoceptor agonists improves lung function in chronic obstructive pulmonary disease. EXPERIMENTAL APPROACH: ACh, tiotropium, and atropine binding to M3 receptors were modelled using molecular dynamics simulations. Contractions of bovine and human tracheal smooth muscle strips were studied. KEY RESULTS: Molecular dynamics simulation revealed extracellular vestibule binding of tiotropium, and not atropine, to M3 receptors as a secondary low affinity binding site, preventing ACh entry into the orthosteric binding pocket. This resulted in a low (allosteric binding) and high (orthosteric binding) functional affinity of tiotropium in protecting against methacholine-induced contractions of airway smooth muscle, which was not observed for atropine and glycopyrrolate. Moreover, antagonism by tiotropium was insurmountable in nature. This behaviour facilitated functional interactions of tiotropium with the β-agonist olodaterol, which synergistically enhanced bronchoprotective effects of tiotropium. This was not seen for glycopyrrolate and olodaterol or indacaterol but was mimicked by the interaction of tiotropium and forskolin, indicating no direct β-adrenoceptor-M3 receptor crosstalk in this effect. CONCLUSIONS AND IMPLICATIONS: We propose that tiotropium has two binding sites at the M3 receptor that prevent ACh action, which, together with slow dissociation kinetics, may contribute to insurmountable antagonism and enhanced functional interactions with β-adrenoceptor agonists. SN - 1476-5381 UR - https://www.unboundmedicine.com/medline/citation/31077341/Second_M3_muscarinic_receptor_binding_site_contributes_to_bronchoprotection_by_tiotropium L2 - https://doi.org/10.1111/bph.14707 DB - PRIME DP - Unbound Medicine ER -