TRPC3 overexpression and intervention in airway smooth muscle of ovalbumin-induced hyperresponsiveness and remodeling

Mechanisms of allergy and adult asthma

PURPOSE OF REVIEW

Allergic asthma reflects the interplay between inflammatory mediators and immune, airway epithelial, and other cells. This review summarizes key insights in these areas over the past year.

RECENT FINDINGS

Key findings over the past year demonstrate that epithelial cells mediate tight junction breakdown to facilitate the development of asthma-like disease in mice. Innate lymph lymphoid cells (ILC), while previously shown to promote allergic airway disease, have now been shown to inhibit the development of severe allergic disease in mice. Fibrinogen cleavage products (previously shown to mediate allergic airway disease and macrophage fungistatic immunity by signaling through Toll-like receptor 4) have now been shown to first bind to the integrin Mac-1 (CD11c/CD18). Therapeutically, recent discoveries include the development of the antiasthma drug PM-43I that inhibits the allergy-related transcription factors STAT5 and STAT6 in mice, and confirmatory evidence of the efficacy of the antifungal agent voriconazole in human asthma.

SUMMARY

Studies over the past year provide critical new insight into the mechanisms by which epithelial cells, ILC, and coagulation factors contribute to the expression of asthma-like disease and further support the development antiasthma drugs that block STAT factors and inhibit fungal growth in the airways.

Folium Sennae and emodin reverse airway smooth muscle contraction

The objective of this project was to find a bronchodilatory compound from herbs and clarify the mechanism. We found that the ethanol extract of Folium Sennae (EEFS) can relax airway smooth muscle (ASM). EEFS inhibited ASM contraction, induced by acetylcholine, in mouse tracheal rings and lung slices. High-performance liquid chromatography assay showed that EEFS contained emodin. Emodin had a similar reversal action. Acetylcholine-evoked contraction was also partially reduced by nifedipine (a selective inhibitor of L-type voltage-dependent Ca²⁺ channels, LVDCCs), YM-58483 (a selective inhibitor of store-operated Ca²⁺ entry, SOCE), as well as Y-27632 (an inhibitor of Rho-associated protein kinase). In addition, LVDCC- and SOCE-mediated currents and cytosolic Ca²⁺ elevations were inhibited by emodin. Emodin reversed acetylcholine-caused increases in phosphorylation of myosin phosphatase target subunit 1. Furthermore, emodin, in vivo, inhibited acetylcholine-induced respiratory system resistance in mice. These results indicate that EEFS-induced relaxation results from emodin inhibiting LVDCC, SOCE, and Ca²⁺ sensitization. These findings suggest that Folium Sennae and emodin may be new sources of bronchodilators.

Roles of airway smooth muscle dysfunction in chronic obstructive pulmonary disease

The airway smooth muscle (ASM) plays an indispensable role in airway structure and function. Dysfunction in ASM plays a central role in the pathogenesis of chronic obstructive pulmonary disease (COPD) and contributes to alterations of contractility, inflammatory response, immunoreaction, phenotype, quantity, and size of airways. ASM makes a key contribution in COPD by various mechanisms including altered contractility and relaxation induce by [Ca²⁺]_i, cell proliferation and hypertrophy, production and modulation of extracellular cytokines, and release of pro-and-anti-inflammatory mediators. Multiple dysfunctions of ASM contribute to modulating airway responses to stimuli, remodeling, and fibrosis, as well as influence the compliance of lungs. The present review highlights regulatory roles of multiple factors in the development of ASM dysfunction in COPD, aims to understand the regulatory mechanism by which ASM dysfunctions are initiated, and explores the clinical significance of ASM on alterations of airway structure and function in COPD and development of novel therapeutic strategies for COPD.