Protective Roles for RGS2 in a Mouse Model of House Dust Mite-Induced Airway Inflammation

PLoS One. 2017 Jan 20;12(1):e0170269. doi: 10.1371/journal.pone.0170269. eCollection 2017.

Abstract

The GTPase-accelerating protein, regulator of G-protein signalling 2 (RGS2) reduces signalling from G-protein-coupled receptors (GPCRs) that signal via Gαq. In humans, RGS2 expression is up-regulated by inhaled corticosteroids (ICSs) and long-acting β2-adrenoceptor agonists (LABAs) such that synergy is produced in combination. This may contribute to the superior clinical efficacy of ICS/LABA therapy in asthma relative to ICS alone. In a murine model of house dust mite (HDM)-induced airways inflammation, three weeks of intranasal HDM (25 μg, 3×/week) reduced lung function and induced granulocytic airways inflammation. Compared to wild type animals, Rgs2-/- mice showed airways hyperresponsiveness (increased airways resistance and reduced compliance). While HDM increased pulmonary inflammation observed on hematoxylin and eosin-stained sections, there was no difference between wild type and Rgs2-/- animals. HDM-induced mucus hypersecretion was also unaffected by RGS2 deficiency. However, inflammatory cell counts in the bronchoalveolar lavage fluid of Rgs2-/- animals were significantly increased (57%) compared to wild type animals and this correlated with increased granulocyte (neutrophil and eosinophil) numbers. Likewise, cytokine and chemokine (IL4, IL17, IL5, LIF, IL6, CSF3, CXCLl, CXCL10 and CXCL11) release was increased by HDM exposure. Compared to wild type, Rgs2-/- animals showed a trend towards increased expression for many cytokines/chemokines, with CCL3, CCL11, CXCL9 and CXCL10 being significantly enhanced. As RGS2 expression was unaffected by HDM exposure, these data indicate that RGS2 exerts tonic bronchoprotection in HDM-induced airways inflammation. Modest anti-inflammatory and anti-remodelling roles for RGS2 are also suggested. If translatable to humans, therapies that maximize RGS2 expression may prove advantageous.

MeSH terms

  • Animals
  • Bronchitis / immunology
  • Bronchitis / physiopathology*
  • Bronchoalveolar Lavage Fluid
  • Disease Models, Animal*
  • Female
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pneumonia / immunology
  • Pneumonia / physiopathology*
  • Pyroglyphidae / immunology*
  • RGS Proteins / genetics
  • RGS Proteins / physiology*

Substances

  • RGS Proteins
  • Rgs2 protein, mouse

Grants and funding

This work was supported by: Canadian Institutes of Health Research (CIHR) (MOP 125918) (RN); Alberta Innovates – Health Solutions (AI-HS) Senior Scholar award (RN); Alberta Lung Association scholarship (TG) and grant in aid (RN).