Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA081

Poster Communications

Effects of pharmacological Gq protein inhibition on airway remodeling in chronic asthma

J. M. Dietrich1, A. Simon1, M. Matthey1, G. König2, B. K. Fleischmann1, D. Wenzel1

1. Physiology 1, University of Bonn, Bonn, Germany. 2. Pharmaceutical Biology, University of Bonn, Bonn, Germany.

G proteins are important modulators of (patho)physiological functions in many organs. In the lung, the Gq subtype is of particular relevance, as it is a key mediator of smooth muscle tone regulation in airways and also involved in chronic lung diseases such as allergic asthma. This disease is characterized by airway hyperresponsiveness, inflammation and remodeling comprising collagen deposition, goblet cell hyperplasia as well as smooth muscle thickening. Even though the severity of asthma appears to be linked to airway remodeling, currently available drugs cannot efficiently reduce this process. We therefore wondered, whether the pharmacological pan-Gq protein inhibitor FR900359 (FR) could modulate airway remodeling. The effect of FR was investigated in a mouse model of chronic ovalbumin (OVA)-induced asthma: Balb/c mice were sensitized with i.p. injections of 20 µg OVA and 2 mg Alum on days 0 and 14.Then, mice were challenged with 1% OVA three days a week until day 37. FR or vehicle was applied one hour before every OVA challenge via intratracheal application (5 Vol% isoflurane, p.i.). For functional analysis mice were injected i.p. with fentanyl (50 µg/kg), medetomedine (0.5 mg/kg), midazolam (5 mg/kg), vecuronium (0.1 mg/kg) and carprofen (5 mg/kg s.c.) and airway resistance was determined with a FlexiVent system. For the in vitro assessment of FR effects on airway smooth muscle a cell growth assay using human bronchial smooth muscle cells (hBSMCs) was used. In our chronic asthma model airway hyperresponsiveness could be observed, when airway resistance was compared to healthy mice upon methacholine (MCh) challenge. We also found that local pulmonary application of FR strongly reduced the MCh-induced increase of airway resistance in OVA mice (mean±S.E.M.: 4.2±0.5 cmH2Os/mL at 50 mg/ml MCh, n=5) compared to vehicle treated controls (10.8±1.9 cmH2Os/mL, n=7, two-way-ANOVA, p<0.01). Also collagen deposition around the airways was found to be enhanced in OVA mice as determined by Sirius Red staining of lung sections. Gq Inhibition by FR led to a decreased amount of collagen (2.8±0.2 collagen µm2/µm bm, n=10), when compared to vehicle controls (3.6±0.2 collagen µm2/µm bm, n=8, p<0.05). Moreover, FR also reduced goblet cell hyperplasia (0.07±0.01 PAS+ cells/µm bm, n=5) compared to vehicle treatment (0.13±0.02 PAS+ cells/µm bm, n=5, one-way-ANOVA, p<0.05), as determined by periodic acid Schiff staining (PAS). Furthermore, hBSMCs were stimulated with PDGF (20 ng/mL) and thrombin (1 U/mL) for 3 days in vitro and co-application of FR reduced growth of hBSMC compared to vehicle controls (Vehicle: 1.4±0.07 vs FR: 1.1±0.06 relative cell number, n=4, one-way-ANOVA, p<0.05). These findings identify the pharmacological Gq inhibitor FR as a potentially promising candidate for reducing both, airway hyperresponsiveness and airway remodeling in chronic asthma.

Where applicable, experiments conform with Society ethical requirements