Healing the GUT with probiotics: can probiotics help relieve allergic rhinitis?

• Main Authors: Ser, Hooi Leng *, Wong, Joshua You Jing *, Goh, Bey Hing *, Kavita, Reginald *
• Format: Article
• Published: BMJ Publishing Group 2022
• Subjects: QR Microbiology; RA Public aspects of medicine; RC Internal medicine
• Online Access: http://eprints.sunway.edu.my/2969/; https://doi.org/10.1136/gutjnl-2022-IDDF.75

Background The role of the gut microbiome has been implicated in allergic rhinitis (AR), which is the most prevalent allergic disease that can occur at any age. As microbes in the gut have important roles in supporting the metabolism of the host as well as shaping the immune system, tackling the dysbiosis in AR via probiotic supplementation appears to be a feasible intervention to reduce mucosal inflammation and prevent its recurrence. Thus, the current study aims to assess the potential of probiotics in reversing gut dysbiosis in AR, specifically via improving the resilience of the gut microbiome and potentially relieving AR symptoms. Methods Searches were performed in four databases (PubMed, MEDLINE, CENTRAL, ScienceDirect; database inception to 31st March 2022) using ’allergy rhinitis’, ‘hay fever’, ‘microbiota’, ’microbiome’ and ’probiotics’ as MeSH terms (following PRISMA guidelines). All titles and abstracts retrieved were screened based on the inclusion and exclusion criteria. Studies reporting gut microbiome data in relation to AR were included in the analysis but not those without gut microbiome data or without intervention. Results Out of the 79 articles retrieved, a total of five human studies reporting the use of probiotics in AR were selected according to the inclusion and exclusion criteria (IDDF2022-ABS-0236 Figure 1). Despite different strains used, three studies from Japan reported their potential of probiotic supplementations in suppressing gut microbiota changes during the pollen season. A recent study in 2017 highlighted that fermented milk containing LGG and L. gasseri increased microbial diversity; Firmicutes were significantly increased (P < 0.001), while Bacteroidetes were significantly decreased after probiotic administration (P < 0.001). LGG was detected in the probiotic group, but not those in the placebo group at the end of the study. Besides combatting gut dysbiosis, probiotic supplementation can reduce the severity of AR symptoms and improve quality of life, as reported by Torre and the team in Italy. Serum levels of IL-4 and IL-5 decreased after the intervention, implying a reduction in the Th2 cytokine profile. Conclusions While all studies have supported the safe use of probiotics, these evidence warrants further investigations into the efficacy of probiotics for the long-term management of AR and the exact mechanisms behind their immunomodulatory effects.