Allergic rhinitis, the most common manifestation of respiratory allergy, frequently progresses to allergic asthma. It is associated with dysbiosis in the gastrointestinal and ENT microbiota.
A common hereditary disease
Allergic rhinitis is a very common disease, and the number of cases continues to climb worldwide. Around 500 million people are affected1. It starts with exposure to an allergen and can be intermittent or persistent, depending on the nature of that allergen (pollen, dust mites, pet dander, etc.). Symptoms include itching, anosmia, rhinorrhea, nasal obstruction, and sneezing. The hereditary component of respiratory allergy is well documented; if both parents are allergic, in 7 out of 10 cases the individual will also be allergic2.
Allergic rhinitis and allergic asthma
Around 20% of people with allergic rhinitis have asthma and 80% of asthmatics have rhinitis3. Clinical and epidemiological studies have established a connection between microbiota, allergic rhinitis, and asthma.
Among the characteristics these diseases have in common, there is low diversity in the intestinal microbiota during the first weeks of life4,5. Lactobacilli in particular are less present in allergic individuals, and they are known as bacteria that limit the proliferation of pathogens in the bowel and promote immunoregulation by stimulating regulatory T cells responses. Conversely, a greater diversity of bacteria is found in the ENT microbiota6, which can contribute to chronic inflammation and symptoms observed in these patients.
Probiotics under investigation
Currently, treatment for allergic rhinitis is based on removal of the allergen and preventive or curative antihistamine treatment. Topical corticosteroids can help with exacerbation episodes. Research is also being directed at modulating the microbiota to reduce allergic risk, using probiotics like Lactobacillus plantarum and Lactobacillus paracasei7,8.
1. Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines: 2010 Revision. The Journal of Allergy and Clinical Immunology, septembre 2010, vol. 126(3): 466-476 http://www.jacionline.org/article/S0091-6749(10)01057-2/pdf
2. Dávila I, Mullol J, Ferrer M, Bartra J, del Cuvillo A, Montoro J, Jáuregui I, Sastre J, Valero A. Genetic aspects of allergic rhinitis. J Investig Allergol. Clin Immunol. 2009;19 Suppl 1:25-31. Review. PubMed PMID: 19476051.
3. Mullol J. et al. Allergic Rhinitis and its Impact on Asthma Update (ARIA 2008) : the perspective from Spain. J Investig Allergol Clin Immunol 2008 ;18 :327-334 https://www.ncbi.nlm.nih.gov/pubmed/18973095
4. Bisgaard H et al. Reduced diversity of the intestinal microbiota during infancy is associated with increased risk of allergic disease at school age. J Allergy Clin Immunol 2011 ; 128 : 646-52. https://www.ncbi.nlm.nih.gov/pubmed/21782228
5. L.C.F.L. Melli et al. Intestinal microbiota and allergic diseases: A systematic review. Allergol Immunopathol (Madr). 2016;44(2):177-188 https://www.ncbi.nlm.nih.gov/pubmed/25985709
6. Choi CH, Watanabe S et al. Seasonal allergic rhinitis affects sinonasal microbiota. Am Journal of Allergy, 2014 Jul;28(4):281-6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101129
7. Peng GC et al. The efficacy and safety of heat-killed Lactobacillus paracasei for treatment of perennial allergic rhinitis induced by house-dust mite. Pediatr Allergy Immunol. 2005;16:433–8 https://www.ncbi.nlm.nih.gov/pubmed/16101937
8. Yang G. et al. Treatment of Allergic Rhinitis with Probiotics: An Alternative Approach. North American Journal of Medical Sciences, 5(8), 465–468. http://doi.org/10.4103/1947-2714.117299