Clinical Efficacy of Probiotics for Allergic Rhinitis: Results of an Exploratory Randomized Controlled Trial

Abstract

Background: Allergic Rhinitis (AR) is an atopic disease affecting the upper airways of predisposed subjects exposed to aeroallergens. This study evaluates the effects of a mix of specific probiotics (L. acidophilus PBS066, L. rhamnosus LRH020, B. breve BB077, and B. longum subsp. longum BLG240) on symptoms and fecal microbiota modulation in subjects with AR. Methods: Probiotic effects were evaluated at the beginning (T0), at four and eight weeks of treatment (T1 and T2, respectively), and after four weeks of follow-up from the end of treatment (T3) (n = 19) compared to the placebo group (n = 22). AR symptoms and quality of life were evaluated by the mini rhinitis quality of life questionnaire (MiniRQLQ) at each time point. Allergic immune response and fecal microbiota compositions were assessed at T0, T2, and T3. The study was registered on Clinical-Trial.gov (NCT05344352). Results: The probiotic group showed significant improvement in the MiniRQLQ score at T1, T2, and T3 vs. T0 (p < 0.01, p < 0.05, p < 0.01, respectively). At T2, the probiotic group showed an increase in Dorea, which can be negatively associated with allergic diseases, and Fusicatenibacter, an intestinal bacterial genus with anti-inflammatory properties (p-value FDR-corrected = 0.0074 and 0.013, respectively). Conversely, at T3 the placebo group showed an increase in Bacteroides and Ruminococcaceae unassigned, (p-value FDR-corrected = 0.033 and 0.023, respectively) which can be associated with allergies, while the probiotic group showed a significative increase in the Prevotella/Bacteroides ratio (p-value FDR-corrected = 0.023). Conclusions: This probiotic formulation improves symptoms and quality of life in subjects with AR, promoting a shift towards anti-inflammatory and anti-allergic bacterial species in the intestinal microbiota.

Keywords: allergic rhinitis; immune system; inflammation; microbiota; probiotics.

Figure 1

Study flow-chart.

Figure 2

Mini Rhinoconjunctivitis Quality of Life questionnaire (MiniRQLQ). The asterisks indicate comparison between initial (T0) and T1, T2, T3 data within the same group (Placebo group, n = 22 and Probiotic group, n = 19). * p < 0.05, ** p < 0.01.

Figure 3

(a) Plot from LDA LEfSe analysis and (b) taxa relative abundances (%). The length of the bar columns represents the LDA score. Box-and-whisker plots with data points are visualized in the six panels at the bottom of the figure and show the relative abundance of each taxon indicated in the LDA LEfSe plots in the Placebo (n = 20, lime green) and Probiotic (n = 17, blue) groups. Median, first, and third quartiles are shown in the box-and-whisker plots. Mann–Whitney U Test results of the group comparisons are shown. * p-value FDR-corrected < 0.05, ** p-value FDR-corrected < 0.01. Placebo group, n = 20 and Probiotic group, n = 17.

Figure 4

Prevotella/Bacteroides ratio in the Placebo and Probiotic groups across the three time points of the study. Mann–Whitney U Test results of the group comparisons are shown. * p-value FDR-corrected < 0.05.