Bronchial thermoplasty

Asthma is a chronic inflammatory disease that affects 300 million people worldwide. Its prevalence rangesfrom 1% to 18% of the population in different countries. The World Health Organization has estimated that 15 million disability-adjusted life years are lost annually due to asthma. Worldwide deaths from asthma are estimated at 250 000 per year. Furthermore, asthma is a major cause of absence from work in many countries, including United States .

Effects of bronchial thermoplasty and cryoablation on airway smooth muscle

Background:The effectiveness of bronchial thermoplasty(BT)has been reported in patients with severe asthma.This study compared the effects of BT and cryoballoon ablation(CBA)therapy on the airway smooth muscle(ASM).Methods:Eight healthy male beagle dogs were included in this experiment.In the preliminary experiment,one dog received BT treatment for both lower lobe bronchus,another dog received CBA treatment for 7 s on the upper and lower lobe of right bronchus,and 30 s on the left upper and lower lobe.The treatments were performed twice at an interval of 1 month.In subsequent experiments,the right lower lobe bronchus was treated with BT,and the left lower lobe bronchus was treated with CBA.The effects of treatment were observed after 1(n=3)month and 6 months(n=3).Hematoxylin-eosin staining,Masson trichrome staining,and immunohistochemical staining were used to compare the effects of BT and CBA therapy on the ASM thickness,collagen fibers synthesis,and M3 receptor expression after treatment.One-way analysis of variance with Dunnett post hoc test was used to analyze the differences among groups.Results:In the preliminary experiment,the ASM ablation effect of 30-s CBA was equivalent to that of 7-s CBA(ASM thickness:30.52±7.75μm vs.17.57±15.20μm,P=0.128),but the bronchial mucociliary epithelium did not recover,and large numbers of inflammatory cells had infiltrated the mucosal epithelium at 1-month post-CBA with 30-s freezing.Therefore,we chose 7 s as the CBA treatment time in our follow-up experiments.Compared with the control group(35.81±11.02μm),BT group and CBA group(13.41±4.40μm and 4.81±4.44μm,respectively)had significantly decreased ASM thickness after 1 month(P<0.001).Furthermore,the ASM thickness was significantly lower in the 1-month post-CBA group than in the 1-month post-BT group(P=0.015).There was no significant difference in ASM thickness between the BT and CBA groups after six months(9.92±4.42μm vs.7.41±7.20μm,P=0.540).Compared with the control group(0.161±0.013),the average optical density of the ASM M3 receptor was significantly decreased in 6-month post-BT,1-month post-CBA,and 6-month post-CBA groups(0.070±0.022,0.072±0.012,0.074±0.008,respectively;all P<0.001).There was no significant difference in the average optical density of ASM M3 receptor between the BT and CBA therapy groups after six months(P=0.613).Conclusions:CBA therapy effectively ablates the ASM,and its ablation effect is equivalent to that of BT with a shorter onset time.A neural mechanism is involved in both BT and CBA therapy.