Inhaled Inactivated Mycobacterium Phlei in Moderate Asthma

In This Article

Abstract and Introduction

Abstract

BCG and other mycobacterial infections suppress airway hyper-responsiveness and inflammation in asthma models; however, its efficacy in human populations remains controversial. We use inactivated Mycobacterium phlei by way of atomizing inhalation to investigate whether it would protect against asthma in adult patients. Patients with newly diagnosed, uncontrolled, moderate persistent bronchial asthma were randomly divided into two groups. The patients in group A were treated with a solution of inhaled inactivated-M. phlei. Group B were treated with salmeterol xinafoate and fluticasone propionate powder. The Spirometry and Bronchial Provocation Test and Asthma Control Test were carried out; the peak expiratory flow and forced expiratory volume in 1 s-PD20 of the patients in the two groups increased significantly. However, overall, there was no significant difference between the two groups. Asthma Control Test scores of the patients in the two groups were significantly increased. We concluded that inhaled inactivated M. phlei, to a certain extent, improves asthma symptoms, reduces the need for rescue medication and reduces acute exacerbation of asthma. It plays the same role as inhaled Seretide treatment in reducing airway hyper-responsiveness.

Introduction

The prevalence of bronchial asthma has increasingly risen around the world, especially in many developed countries. In China, the pediatric asthma prevalence rate is drastically increasing due to the aggravation of environmental pollution, as has happened in other countries.^[1] This so-called 'hygiene hypothesis' states that reduced exposure to microbial components leads to an imbalance of the immune system with a predisposition to the development of allergic disorders.^[2] More specifically, the epidemiological study by Shirakawa indicated an inverse association among Japanese school children between exposure to mycobacteria and the subsequent development of atopy and asthma.^[3] Exposure to the Mycobacterium bovis BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.^[4] Inhaled corticosteroids (ICS) and long-acting β2-adrenoceptor agonists are the mainstay of asthma therapy. Most patients achieve good asthma control by complying with this standard therapy. However, these therapies do not change the underlying immunological mechanisms and fail to afford a significant proportion of patients with good control of their symptoms or prevent severe exacerbations.^[5] Many investigators have shown that BCG and other mycobacterial infections suppress airway hyper-responsiveness (AHR) and eosinophilic inflammation in animal models of asthma,^[6,7] but its efficacy in human populations remains controversial. In this article, we use inactivated Mycobacterium phlei by way of atomizing inhalation via mucosa to investigate whether it would protect against allergic asthma in adult patients.

Table 1. Characteristics of patients at study enrolment.
Variable	Group A	Group B
Number	14	14
Sex (male:female)	8:6	7:7
Age (years)	33.16 ± 13.23	31.56 ± 11.75
FEV1 (l)	2.31 ± 0.78	2.51 ± 0.65
Peak expiratory flow (l/s)	5.63 ± 2.19	5.83 ± 2.17
ACT	13.71 ± 1.07	14.07 ± 1.15

ACT: Asthma control test; FEV1: Forced expiratory volume in 1 s.

Table 2. Negative conversion rate (%) after treatment in the two groups.
Group	Day 6			Day 30			Day 90
Group	Positive	Negative	Negative conversion rate (%)	Positive	Negative	Negative conversion rate (%)	Positive	Negative	Negative conversion rate (%)
A	3	11	78.5	2	12	85.7	3	11	78.5
B	2	12	85.7	1	13	92.9	0	14	100

Table 3. ACT scores, FEV1, FEV1%, PEF, PEF% and FEF1-PD20 in the two groups.
Tests	Group A (n = 14)				Group B (n = 14)
Tests	Day 0	Day 6	Day 30	Day 90	Day 0	Day 6	Day 30	Day 90
ACT	13.71 ± 1.07	–	20.57 ± 2.28^†	20.64 ± 4.01^†	14.07 ± 1.15	–	22.36 ± 1.87^†	24.43 ± 0.76^§†
FEV1 (l)	2.31 ± 0.78	2.37 ± 0.77	2.39 ± 0.80	2.39 ± 0.87	2.51 ± 0.65	2.81 ± 0.66	2.86 ± 0.62	2.91 ± 0.58^‡
FEV1, predicted (%)	77.89 ± 14.40	79.13 ± 13.46	80.00 ± 14.69	81.31 ± 17.04	79.12 ± 15.16	87.44 ± 9.44^‡	91.66 ± 7.63^†¶	93.67 ± 5.79^†¶
PEF (l/s)	5.63 ± 2.19	7.03 ± 1.65^‡	7.58 ± 1.35^†	7.29 ± 1.79^‡	5.83 ± 2.17	7.05 ± 2.35^‡	7.18 ± 1.56^‡	7.59 ± 1.86^‡
PEF, predicted (%)	68.66 ± 14.17	82.89 ± 21.24	86.00 ± 22.21^‡	90.36 ± 23.41^†	73.82 ± 18.19	91.40 ± 17.60^†	96.79 ± 14.28^†	99.89 ± 10.95^†
FEV1-PD20 (mg)	0.41 ± 0.23	2.23 ± 0.43^‡	2.25 ± 0.64^†	2.20 ± 0.89^‡	0.38 ± 0.29	2.30 ± 0.55^†	2.38 ± 0.40^†	2.40 ± 0.10^†

Data expressed as mean ± standard deviation.
^† p < 0.01; ^‡ p < 0.05 as compared with pretreatment in each group; §p < 0.01; ¶p < 0.05, group A versus group B.
ACT: Asthma Control Test; FEV1: Forced expiratory volume in 1 s; PD20: Provocative dose of MCh causing a 20% fall; PEF: Peak expiratory flow.

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