Probiotic supplements may improve asthma control, lung function
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Key takeaways:
- Bifidobacterium infantis 35624 can decrease levels of dysfunctional T regulatory cells.
- There were no significant differences in Asthma Control Test scores between the probiotic and placebo groups.
- 93.3% of the probiotic group and 35.7% of the placebo group achieved well-controlled asthma after 4 weeks of treatment.
Probiotic supplements such as Bifidobacterium infantis 35624 could improve asthma control and lung function while reducing the need to use rescue inhalers, according to a letter published in Annals of Allergy, Asthma & Immunology.
These improvements may be due to the decrease in dysfunctional T regulatory (Treg) cells that comes with probiotic treatment, Sasipa Sangkanjanavanich, MD, doctorate student and research assistant, faculty of medicine, Ramathibodi Hospital, Mahidol University, Ratchathewi, Thailand, and colleagues wrote.
The randomized, double-blind trial was conducted between January 2019 and January 2020 at Phramongkutklao Hospital in Bangkok. Patients took capsules with 1 x 109 colony-forming unit live Bifidobacterium infantis 35624 or a placebo twice a day for 4 weeks, with 60 patients completing the study.
The researchers found no significant differences in Asthma Control Test (ACT) scores, pulmonary function test, VAS or rescue inhaler use between the groups at 4 weeks or 8 weeks. Also, there were no differences in percentage change in ACT scores between the groups, the researchers said.
After 4 weeks, 14 of the 15 members (93.3%) of the probiotic group and five of the 14 members (35.7%) of the placebo group achieved well-controlled asthma, defined as an ACT score of 20 or higher (P = .001). At 8 weeks, 100% of the probiotic group and 57.1% of the placebo group had well-controlled asthma (P = .006).
The probiotic group had minimally better scores for FEV1 than the placebo group, but the researchers did not think this difference was significantly different.
However, the probiotic group had significant increases in forced vital capacity (median difference, 11.16%; 95% CI, –20% to –0.22%) and lower frequency of rescue inhaler use (1 puff vs. 11 puffs; 95% CI, 1-12) compared with the placebo group.
Two patients in the placebo group and none of the patients in the probiotic group experienced severe asthma exacerbations. Also, the researchers did not observe any significant differences in peripheral blood eosinophil counts or plasma periostin levels.
At 4 weeks, patients in the treatment group with uncontrolled asthma had significantly lower CRTH2+ Treg cell numbers (0.095% vs. 0.066%; 95% CI, –0.06 to –0.01).
The treatment group also had a substantially lower relative change in median CRTH2+ Treg cell number (median difference, 57.8%; 95% CI, 1.8% to 78.3%) compared with the placebo group. Plus, CRTH2+ Treg cell frequency correlated with ACT scores (Pearson correlation coefficient = –0.21).
According to the researchers, these decreases in dysfunctional Treg cells likely are due to improvements mediated by Bifidobacterium infantis, which could improve asthma control and lung function while reducing the need for rescue inhalers, although more extensive clinical trials with longer durations would be needed to confirm these findings.
Perspective
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The methodology of this study was robust, as it was a randomized controlled trial with placebo. There also was follow-up after discontinuation. But the treatment period was relatively short, as many other studies extended the treatment duration up to 4 to 6 months.
Also, this study emphasized the need to stratify patients. In other words, it is important to phenotype patients. In this case, it was important to select the uncontrolled subset. Namely, uncontrolled asthmatics responded very well to the probiotic concerning asthma control, with 14 of the 15 patients in the probiotic group and five of the 14 patients in the placebo group achieving asthma control after the course. More interestingly, the effect was full in all subjects after discontinuation, which means that the beneficial effects persisted over time.
However, lung function was not modified in clinically relevant manner. This outcome could be expected, as it is difficult for a probiotic to improve lung function in a very short time.
The reduced need for symptomatic medications such as bronchodilators is consistent with control improvement. After all, one criterion for evaluating control is precisely the use of relievers.
In addition, this study provided biological information because the probiotic reduced a subpopulation of Treg cells (CRTH2+). Moreover, the T-cell count correlated with ACT. This subset is involved in the expansion of type inflammation, which is a characteristic of asthmatic patients.
Therefore, this study underscored the importance of phenotyping patients (selecting uncontrolled asthmatics), as its 4-week course improved asthma control, probably because treatment affects the immune response, dampening the type 2 inflammation.
Although the study’s limitations included the lack of sample size and mediator measurement, it confirmed other research that demonstrated the beneficial effects provided by probiotics as add-on treatment.
Doctors may integrate probiotics into their own care, which would be an intriguing option. Of course, probiotics cannot substitute standard therapy. But they could improve the immune response and dampen inflammation. So, asthma progress may improve as reported by this study.
Unfortunately, guidelines do not include probiotics as a possible therapeutical option. Further studies should be conducted with fully rigorous methodology and assessing mediators.
Reference:
Ciprandi G, et al. Ann Allergy Asthma Immunol. 2022;doi:10.1016/j.anai.2022.04.026.
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Sangkanjanavanich S, et al. Ann Allergy Asthma Immunol. 2022;doi:10.1016/j.anai.2022.08.1000.
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