Effect of bronchial thermoplasty on structural changes and inflammatory mediators in the airways of subjects with severe asthma.

BACKGROUND: Bronchial thermoplasty (BT) is a novel technique used in the treatment of subjects with severe refractory asthma. Radiofrequency is provided to airway walls during bronchoscopy in order to reduce airway remodeling. Several clinical studies have reported an improvement in subjects' symptoms following BT. However, how BT affects the airway architectures and inflammatory mediators in the airways has not been yet fully elucidated. METHODS: Fourteen subjects with severe asthma were recruited in this study according to the criteria of ATS severe asthma definition. The study subjects undertook bronchial biopsy during the bronchoscopy procedure at baseline and 6 weeks after the initial BT treatment. The obtained samples were stained with antibodies for α-smooth muscle actin (α-SMA); protein gene product (PGP) 9.5, a specific nerve marker; von Willebrand factor (vWF), a marker for blood vessels; interleukin-17A (IL-17A) and transforming growth factor-ß1 (TGF-ß1). RESULTS: The expression of α-SMA and PGP9.5 were significantly reduced post-BT. There was no significant difference in the number of blood vessels between baseline and post-BT. In addition, BT did not affect the production of IL-17A and TGF-ß1 in the airways. The changes in the expression of α-SMA and PGP9.5 had no significant correlation with the improvement of pulmonary function. CONCLUSION: and Clinical Relevance: This study suggests that BT reduces airway smooth muscle mass and the airway innervation without affecting vasculature and the production of inflammatory mediators in the airways of subjects with severe asthma.

Expression of airway remodeling proteins in mast cell activated by TGF-ß released in OVA-induced allergic responses and their inhibition by low-dose irradiation or 8-oxo-dG.

Allergic asthma is characterized by chronic airway remodeling, which is associated with the expression of extracellular matrix proteins (ECM) by TGF-ß. However, to date there are no reports demonstrating that structural proteins are directly expressed in mast cells. This study aimed to investigate whether ECM proteins are expressed in mast cells activated with antigen/antibody reaction, and whether the resolution effects of irradiation or 8-oxo-dG may contribute to allergic asthma prevention. Bone marrow-derived mast cells (BMMCs) were activated with DNP-HSA/anti-DNP IgE antibody (act-BMMCs). C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) to induce allergic asthma. Mice were treated orally with 8-oxo-dG or exposed to whole body irradiation (using (137)Cs gamma ray at a dose of 0.5 Gy) for three consecutive days 24 h after OVA challenge. Expression of extracellular matrix (ECM) proteins, TGF-ß signaling molecules and NF-κB/AP-1 was determined in the BMMCs, bronchoalveolar lavage (BAL) cells or lung tissues using Western blot, polymerase chain reaction (PCR) and electrophoretic mobility shift assay (EMSA), respectively. Act-BMMCs increased expression of ECM proteins, TGF-ß/TGF-ß receptor I, TGF-ß signaling molecules and cytokines; and increased both NF-κB and AP-1 activity. In addition, the population of mast cells; expression of mast cell markers, TGF-ß signaling molecules, ECM proteins/amounts; OVA-specific serum IgE level; numbers of goblet cells; airway hyperresponsiveness; cytokines/chemokines were increased in BAL cells and lung tissues of OVA-challenged mice. All of the above end points were reduced by irradiation or 8-oxo-dG in vitro and in vivo, respectively. The data suggest that mast cells induce expression of ECM proteins through TGF-ß produced in inflammatory cells of OVA mice and that post treatment of irradiation or 8-oxo-dG after OVA-challenge may reduce airway remodeling through down-regulating mast cell re-activation by TGF-ß/Smad signals.

Low-level laser therapy inhibits bronchoconstriction, Th2 inflammation and airway remodeling in allergic asthma.

Low-level laser therapy (LLLT) controls bronchial hyperresponsiveness (BHR) associated with increased RhoA expression as well as pro-inflammatory mediators associated with NF-kB in acute lung inflammation. Herein, we explore if LLLT can reduce both BHR and Th2 cytokines in allergic asthma. Mice were studied for bronchial reactivity and lung inflammation after antigen challenge. BHR was measured through dose-response curves to acetylcholine. Some animals were pretreated with a RhoA inhibitor before the antigen. LLLT (660 nm, 30 mW and 5.4 J) was applied on the skin over the right upper bronchus and two irradiation protocols were used. Reduction of BHR post LLLT coincided with lower RhoA expression in bronchial muscle as well as reduction in eosinophils and eotaxin. LLLT also diminished ICAM expression and Th2 cytokines as well as signal transducer and activator of transduction 6 (STAT6) levels in lungs from challenged mice. Our results demonstrated that LLLT reduced BHR via RhoA and lessened allergic lung inflammation via STAT6.