Reversal of allergen-induced airway remodeling by CysLT1 receptor blockade

William R Henderson Jr, Gertrude K S Chiang, Ying-Tzang Tien, Emil Y Chi, William R Henderson Jr, Gertrude K S Chiang, Ying-Tzang Tien, Emil Y Chi

Abstract

Rationale: Airway inflammation in asthma is accompanied by structural changes, including goblet cell metaplasia, smooth muscle cell layer thickening, and subepithelial fibrosis. This allergen-induced airway remodeling can be replicated in a mouse asthma model.

Objectives: The study goal was to determine whether established airway remodeling in a mouse asthma model is reversible by administration of the cysteinyl leukotriene (CysLT)1 receptor antagonist montelukast, the corticosteroid dexamethasone, or the combination montelukast + dexamethasone.

Methods: BALB/c mice, sensitized by intraperitoneal ovalbumin (OVA) as allergen, received intranasal OVA periodically Days 14-73 and montelukast or dexamethasone or placebo from Days 73-163.

Measurements and main results: Allergen-induced trafficking of eosinophils into the bronchoalveolar lavage fluid and lung interstitium and airway goblet cell metaplasia, smooth muscle cell layer thickening, and subepithelial fibrosis present on Day 73 persisted at Day 163, 3 mo after the last allergen challenge. Airway hyperreactivity to methacholine observed on Day 73 in OVA-treated mice was absent on Day 163. In OVA-treated mice, airway eosinophil infiltration and goblet cell metaplasia were reduced by either montelukast or dexamethasone alone. Montelukast, but not dexamethasone, reversed the established increase in airway smooth muscle mass and subepithelial collagen deposition. By immunocytochemistry, CysLT1 receptor expression was significantly increased in airway smooth muscle cells in allergen-treated mice compared with saline-treated controls and was reduced by montelukast, but not dexamethasone, administration.

Conclusions: These data indicate that established airway smooth muscle cell layer thickening and subepithelial fibrosis, key allergen-induced airway structural changes not modulated by corticosteroids, are reversible by CysLT1 receptor blockade therapy.

Figures

Figure 1.
Figure 1.
Study design. BAL = bronchoalveolar lavage; OVA = ovalbumin.
Figure 2.
Figure 2.
Allergen-induced airway inflammation and remodeling. Lung tissue was obtained on Day 73 from saline control animals (A, C) and OVA-sensitized/challenged mice (B, D) and stained with hematoxylin and eosin (A, B) or Masson's trichrome stain (C, D). AW = airway; BV = blood vessel. Bars = 100 μm.
Figure 2.
Figure 2.
Allergen-induced airway inflammation and remodeling. Lung tissue was obtained on Day 73 from saline control animals (A, C) and OVA-sensitized/challenged mice (B, D) and stained with hematoxylin and eosin (A, B) or Masson's trichrome stain (C, D). AW = airway; BV = blood vessel. Bars = 100 μm.
Figure 3.
Figure 3.
Effect of CysLT1 receptor blockade and corticosteroid treatment on airway inflammatory cell infiltration in OVA-treated mice. Lung tissue (A, B) and BAL fluid (C) were obtained on Day 73 from saline-treated mice (saline; n = 4) and OVA-sensitized/challenged mice (OVA; n = 4) and Day 163 from saline-treated mice (saline/saline; n = 7) and OVA-treated mice in the absence (OVA/saline; n = 6) or presence of treatment from Days 73–163 with 1 mg/kg of montelukast (OVA/MK; n = 8), 1 mg/kg of dexamethasone (OVA/DEX; n = 8), or 1 mg/kg of montelukast + 1 mg/kg of dexamethasone (OVA/MK + DEX; n = 4). The total inflammatory cell infiltrate (0–4+ scale; A) and number of eosinophils per unit area (2,200 μm2; B) in the lung interstitium, and number of eosinophils (× 104) per ml of BAL fluid (C) were determined by morphometry; p values are shown where significant (p < 0.05).
Figure 4.
Figure 4.
Effect of CysLT1 receptor blockade and corticosteroid treatment on allergen-induced airway goblet cell metaplasia. Lung tissue was obtained on Day 163 from saline controls (A) and OVA-treated mice in the absence (B) or presence of MK (C), dexamethasone (D), or MK + dexamethasone (E) and stained with Alcian blue with nuclear fast red counterstaining. AW = airway. Bars = 100 μm.
Figure 4.
Figure 4.
Effect of CysLT1 receptor blockade and corticosteroid treatment on allergen-induced airway goblet cell metaplasia. Lung tissue was obtained on Day 163 from saline controls (A) and OVA-treated mice in the absence (B) or presence of MK (C), dexamethasone (D), or MK + dexamethasone (E) and stained with Alcian blue with nuclear fast red counterstaining. AW = airway. Bars = 100 μm.
Figure 4.
Figure 4.
Effect of CysLT1 receptor blockade and corticosteroid treatment on allergen-induced airway goblet cell metaplasia. Lung tissue was obtained on Day 163 from saline controls (A) and OVA-treated mice in the absence (B) or presence of MK (C), dexamethasone (D), or MK + dexamethasone (E) and stained with Alcian blue with nuclear fast red counterstaining. AW = airway. Bars = 100 μm.
Figure 5.
Figure 5.
Reduction in allergen-induced airway goblet cell metaplasia by CysLT1 receptor blockade and corticosteroid treatment. Lung tissue was obtained on Day 73 from saline-treated mice (saline; n = 4) and OVA-treated mice (n = 4) and on Day 163 from saline-treated mice (saline/saline; n = 7) and OVA-treated mice in the absence (OVA/saline; n = 6) or presence of MK (OVA/MK; n = 8), dexamethasone (OVA/DEX; n = 8), or MK + dexamethasone (OVA/MK + DEX; n = 4). The percentage of airway cells positive for mucus glycoproteins was determined by morphometry; p values are shown where significant (p < 0.05).
Figure 6.
Figure 6.
Effect of CysLT1 receptor blockade and corticosteroid treatment on allergen-induced increased airway smooth muscle mass and collagen deposition. Lung tissue was obtained on Day 163 from saline controls (A) and OVA-sensitized/challenged mice in the absence (B) or presence of MK (C), dexamethasone (D), or MK + dexamethasone (E), and stained with Masson's trichrome stain. Arrowheads indicate collagen deposition, arrows airway mucus. AW = airway; EP = epithelial cell. Bars = 50 μm.
Figure 6.
Figure 6.
Effect of CysLT1 receptor blockade and corticosteroid treatment on allergen-induced increased airway smooth muscle mass and collagen deposition. Lung tissue was obtained on Day 163 from saline controls (A) and OVA-sensitized/challenged mice in the absence (B) or presence of MK (C), dexamethasone (D), or MK + dexamethasone (E), and stained with Masson's trichrome stain. Arrowheads indicate collagen deposition, arrows airway mucus. AW = airway; EP = epithelial cell. Bars = 50 μm.
Figure 7.
Figure 7.
Reduction in allergen-induced increased airway smooth muscle mass and subepithelial collagen deposition by CysLT1 receptor blockade but not by corticosteroid treatment. Lung tissue was obtained on Day 73 from saline-treated mice (saline; n = 4) and OVA-treated mice (OVA; n = 4) and Day 163 from saline-treated mice (saline/saline; n = 7) and OVA-treated mice in the absence (OVA/saline; n = 6) or presence of MK (OVA/MK; n = 8), dexamethasone (OVA/DEX; n = 6), or MK + dexamethasone (OVA/MK + DEX; n = 4), and thickness of the airway smooth muscle cell layer in μm (A) and collagen deposition/fibrosis (0–4+ scale; B determined; p values are shown where significant (p < 0.05).
Figure 8.
Figure 8.
Effect of CysLT1 receptor blockade on CysLT1 receptor expression in OVA-treated mice. Lung tissue obtained on Day 163 from saline-treated mice (A) and OVA-treated mice in the absence (C, E, F) or presence of MK (B) or dexamethasone (D) underwent immunocytochemistry for CysLT1 receptor expression using goat anti-CysLT1 receptor antibody (A–D) or for controls, incubation with either phosphate-buffered saline (E) or nonimmunized goat IgG (F) instead of incubation with goat anti-CysLT1 receptor primary antibody. Arrowheads indicate smooth muscle cell layer, arrows indicate inflammatory cells. Bars = 100 μm.
Figure 8.
Figure 8.
Effect of CysLT1 receptor blockade on CysLT1 receptor expression in OVA-treated mice. Lung tissue obtained on Day 163 from saline-treated mice (A) and OVA-treated mice in the absence (C, E, F) or presence of MK (B) or dexamethasone (D) underwent immunocytochemistry for CysLT1 receptor expression using goat anti-CysLT1 receptor antibody (A–D) or for controls, incubation with either phosphate-buffered saline (E) or nonimmunized goat IgG (F) instead of incubation with goat anti-CysLT1 receptor primary antibody. Arrowheads indicate smooth muscle cell layer, arrows indicate inflammatory cells. Bars = 100 μm.
Figure 9.
Figure 9.
Effect of CysLT1 receptor blockade and corticosteroid treatment on pulmonary mechanics to aerosolized methacholine in OVA-treated mice. The degree of bronchoconstriction (expressed as Penh [% of air]) to aerosolized methacholine (0, 5, and 20 mg/ml) was determined on Day 73 in saline-treated mice (saline; n = 4) and OVA-treated mice (OVA; n = 4; *p < 0.05, OVA vs. saline) (A) and Day 163 in saline-treated mice (saline/saline; n = 7) and OVA-treated mice in the absence (OVA/saline; n = 8) or presence of MK (OVA/MK; n = 8), dexamethasone (OVA/DEX; n = 8), or montelukast + dexamethasone (OVA/MK + DEX; n = 4; B).

Source: PubMed

Sponsorer og samarbejdspartnere

Medicinske tilstande

Narkotikainterventioner

3
Abonner