Use of probiotic supplementation in patients with asthma has been associated with improved pulmonary function and quality-of-life parameters, according to study findings published in the journal Allergy, Asthma & Clinical Immunology.
The investigators sought to explore how probiotic supplementation of patients with asthma affected their clinical asthma symptoms, the expression pattern of selective microRNAs (miRNAs), and plasma levels of interleukin-4 (IL-4) and interferon gamma (IFN–γ).
The researchers conducted an 8-week, randomized, double-blind, parallel, placebo-controlled study of 40 patients with asthma who were randomly assigned to receive I capsule per day of either the probiotic intervention or placebo for 8 weeks. The mean (SD) participant age was 38.62 (10.49) years. All patients had a history of mild to moderate asthma for at least 1 year. Study inclusion criteria, which were based on the Global Initiative for Asthma (GINA) guidelines, were a history of at least 2 episodes of wheezing within the past 6 months and/or a bronchodilator test that confirmed a positive response with a 12% increase in forced expiratory volume in 1 second (FEV1).
The primary outcomes following treatment included Asthma Control Test (ACT) scores, FEV1, forced vital capacity (FVC), and FEV1/FVC ratio. Secondary outcomes were changes in Asthma Quality of Life Questionnaire (AQLQ) scores; gene expression of
miR-21, miR-155, miR-146a, miR-126, miR-16, and miR-133b in plasma; and IL-4 and IFN–γ plasma levels during the 2-month intervention.
Of the 40 participants, 5 were excluded from the study following enrollment — 3 in the probiotic arm and 2 in the placebo arm. A total of 17 participants (9 female, 8 male) remained in the probiotic group and 18 patients (5 female, 13 male) in the placebo group.
Results of the study showed that after receiving probiotic supplementation, patients in the probiotic arm had significant improvements in ACT and AQLQ scores compared with their baseline scores (P <.001 and P <.0001, respectively). Further, a significant negative correlation was observed between miR-16 expression and FEV1/FVC ratio prior to the intervention (P =.02). Also, miR-21 expression was correlated with miR-133 expression (P =.002) before the intervention, and miR-155 was associated with miR-126 expression following the intervention (P =.01).
In patients with asthma, the expression of miR-16, miR-146a, and IL-4 levels was reduced significantly, and miR-133b expression was increased, following probiotic supplementation.
Several limitations of the present study warrant mention. First, the analysis was conducted during the COVID-19 pandemic, thus rendering it more difficult to select uninfected participants. Because the study population was small, further studies with larger populations are needed. Additionally, stool samples were not collected to check the differences in bacterial counts and species between the probiotic and placebo arms.
As the study authors concluded, “In our study, 8-week treatment with probiotic supplementation led to reduced Th2 cells-associated IL-4 and improved Forced Expiratory Volume and Forced Vital Capacity. It appears probiotics can be used in addition to common asthma treatments.” The researchers further noted that more research is needed to determine whether long-term probiotic supplementation is beneficial for patients with asthma.
Sadrifar S, Abbasi-Dokht T, Forouzandeh S, et al. Immunomodulatory effects of probiotic supplementation in patients with asthma: a randomized, double-blind, placebo-controlled trial. Allergy Asthma Clin Immunol. 2023;19(1):1. doi:10.1186/s13223-022-00753-4