Targeting of Rac1 prevents bronchoconstriction and airway hyperresponsiveness - 20/12/17
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Abstract |
Background |
The molecular mechanisms responsible for airway smooth muscle cells' (aSMCs) contraction and proliferation in airway hyperresponsiveness (AHR) associated with asthma are still largely unknown. The small GTPases of the Rho family (RhoA, Rac1, and Cdc42) play a central role in SMC functions including migration, proliferation, and contraction.
Objective |
The objective of this study was to identify the role of Rac1 in aSMC contraction and to investigate its involvement in AHR associated with allergic asthma.
Methods |
To define the role of Rac1 in aSMC, ex and in vitro analyses of bronchial reactivity were performed on bronchi from smooth muscle (SM)-specific Rac1 knockout mice and human individuals. In addition, this murine model was exposed to allergens (ovalbumin or house dust mite extract) to decipher in vivo the implication of Rac1 in AHR.
Results |
The specific SMC deletion or pharmacological inhibition of Rac1 in mice prevented the bronchoconstrictor response to methacholine. In human bronchi, a similar role of Rac1 was observed during bronchoconstriction. We further demonstrated that Rac1 activation is responsible for bronchoconstrictor-induced increase in intracellular Ca2+ concentration and contraction both in murine and in human bronchial aSMCs, through its association with phospholipase C β2 and the stimulation of inositol 1,4,5-trisphosphate production. In vivo, Rac1 deletion in SMCs or pharmacological Rac1 inhibition by nebulization of NSC23766 prevented AHR in murine models of allergic asthma. Moreover, nebulization of NSC23766 decreased eosinophil and neutrophil populations in bronchoalveolar lavages from mice with asthma.
Conclusions |
Our data reveal an unexpected and essential role of Rac1 in the regulation of intracellular Ca2+ and contraction of aSMCs, and the development of AHR. Rac1 thus appears as an attractive therapeutic target in asthma, with a combined beneficial action on both bronchoconstriction and pulmonary inflammation.
Le texte complet de cet article est disponible en PDF.Graphical abstract |
Key words : Rac1, airway smooth muscle, asthma, airway hyperresponsiveness, calcium, PLC, pulmonary inflammation
Abbreviations used : AHR, aSMC, CCh, Der f, IP3, OVA, Pak1, SMC, SMC-Rac1-KO
Plan
This work was supported by grants from the Agence National de la Recherche (project no. ANR-09-JCJC-0115-01), the Institut de Recherche en Santé Respiratoire des Pays de la Loire (G-Rar project), the Société d’Accélération du Transfert de Technologie (project no. STRAS-2117), the Fondation pour la Recherche Médicale (project no. PMJ20151034369), and the Institut National de la Santé et de la Recherche Médicale (INSERM). G.A-G. was supported by a grant from Ministère de la Recherche et de l'Enseignement Supérieur. |
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Disclosure of potential conflict of interest: G. André-Grégoire, F. Dilasser, G. Loirand, and V. Sauzeau have received grants from Agence National de la Recherche (project no. ANR-09-JCJC-0115-01), Institut de Recherche en Santé Respiratoire des Pays de la Loire (G-Rar project), Société d'Accélération du Transfert de Technologie (project no. STRAS-2117), the Fondation pour la Recherche Médicale (project no. PMJ20151034369), and the Institut National de la Santé et de la Recherche Médicale (INSERM). A. Magnan has board memberships with Novartis and Astra Zeneca; has consultant arrangements with Novartis, Astra Zeneca, and Teva; and has received payment for lectures from Novartis and Astra Zeneca. The rest of the authors declare that they have no relevant conflicts of interest. |
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