Nasal administration of a probiotic assemblage in allergic rhinitis: a placebo‐controlled crossover experimental study

Background Topical probiotics have been suggested as a treatment option for allergic rhinitis, as they may skew the immune response towards a beneficial type-1 non-allergic profile. So far observations in man have exclusively involved oral intake. The aim of this study was to examine if a topical/nasal administration of a probiotic assemblage (PA) affects quality of life, symptoms, and signs of allergic rhinitis in a nasal allergen challenge (NAC) model. Methods In a placebo-controlled and crossover design, 24 patients with seasonal allergic rhinitis were subjected to topical/nasal administration with a PA of Lactobacillus rhamnosus SP1, Lactobacillus paracasei 101/37, and Lactococcus lactis L1A for three weeks. The last week of each treatment period was combined with a NAC-series. Efficacy variables were “Mini-Rhinoconjunctivitis Quality of Life Questionnaire” (Mini-RQLQ), “Total Nasal Symptom Score” (TNSS), “Peak Nasal Inspiratory Flow” (PNIF), and “Fractional Exhaled Nitric Oxide” (FeNO). In addition, to assess whether or not the PA produced any pro-inflammatory effect per se, soluble analytes were monitored in nasal lavage fluids. Finally, bacterial cultures, sampled using swabs from the middle nasal meatus, were assessed for presence of the PA by MALDI-TOF analysis. Results Administration of the PA did not produce any nasal symptoms (cf. placebo). An innate response was discerned within the PA-run (cf. baseline), but no change in nasal lavage fluid levels of cytokines/mediators were observed cf. placebo except for IL-17/IL-17A (a minor increase in the PA run). Administration of the PA did neither affect Mini-RQLQ, TNSS, PNIF, nor FeNO. No evidence of persistent colonization was observed. Conclusion Topical/nasal administration of a PA comprising Lactobacillus rhamnosus SP1, Lactobacillus paracasei 101/37, Lactococcus lactis L1A, while likely evoking a minor innate immune response yet being safe, does not affect quality of life, symptoms, or signs of allergic rhinitis.