Allergy response v. the microbiome
Allergic diseases are becoming more widespread and increasing in prevalence, with many studies now showing that the typical progression of allergy responses begins early in life, although there’s no doubt that there are other factors at play.
There’s also no doubt that the gut microbiota play a leading role in shaping early immune responses - science is now showing that there are allergy-protective bacteria in the microbiome! That said, I'm sure it'll come as no surprise that it’sall about environmental and lifestyle factors which impact the formation of a diverse microbiota, both skin and GI tract, with the usual suspects being a poor-quality diet, early-life antibiotics/overuse of antibiotics, dust/mould, and outdoor air-pollution, i.e. crop spraying.
Sadly, intestinal dysbiosis in youngstock is now common, inhibiting the natural production in the gut of important SCFAs (short chain fatty acids) such as butyrate, acetate, and propionate. These SCFAs are not only anti-inflammatory, but they also act as an energy source for specific gut microbes known as ‘colonocytes’ which shape the beneficial gut microbiota diversity. They’re also key drivers of T-cell proliferation and activity, T-cells being part of the immune system that focus on specific antigens, playing a critical part in immunity to foreign substances.
As for dust and mould, surprisingly the data is showing that endotoxin levels in the air aren't that different between farming and urban environments, but endotoxins in dust are much higher around farms.
This all collectively emphasises the microbiome’s influence on systemic aspects of the immune response - supporting a healthy microbiome is key for strengthening immune responses and increasing toxicant elimination. Examples include focusing on:
1. Doruel D, Bingöl G, Altantaa DU, Seydaoalu G, Erkan A, Yalmaz M. The trend of change of allergic diseases over the years: three repeated surveys from 1994 to 2014. Int Arch Allergy Immunol.2017;173(3):178-182. doi:1159/000477726
2. Brozek G, Lawson J, Szumilas D, Zejda J. Increasing prevalence of asthma, respiratory symptoms, and allergic diseases: four repeated surveys from 1993-2014. Respir Med.2015;109(8):982-990. doi:1016/j.rmed.2015.05.010
3. Renz H, Skevaki C. Early life microbial exposures and allergy risks: opportunities for prevention. Nat Rev Immunol. Published online September 11, 2020. doi:1038/s41577-020-00420-y
4. Kemter AM, Nagler CR. Influences on allergic mechanisms through gut, lung, and skin microbiome exposures. J Clin Invest. 2019;129(4):1483-1492. doi:1172/JCI124610
5. Hill DA, Spergel JM. The atopic march: critical evidence and clinical relevance. Ann Allergy Asthma Immunol. 2018;120(2):131-137. doi:1016/j.anai.2017.10.037
6. Yamamoto-Hanada K, Yang L, Narita M, Saito H, Ohya Y. Influence of antibiotic use in early childhood on asthma and allergic diseases at age 5. Ann Allergy Asthma Immunol. 2017;119(1):54-58. doi:1016/j.anai.2017.05.013
7. Tischer C, Weikl F, Probst AJ, Standl M, Heinrich J, Pritsch K. Urban dust microbiome: impact on later atopy and wheezing. Environ Health Perspect. 2016;124(12):1919-1923. doi:1289/ehp158
8. Stein MM, Hrusch CL, Gozdz J, et al. Innate immunity and asthma risk in Amish and Hutterite farm children. N Engl J Med. 2016;375(5):411-421. doi:1056/NEJMoa1508749
9. Herr M, Just J, Nikasinovic L, et al. Risk factors and characteristics of respiratory and allergic phenotypes in early childhood. J Allergy Clin Immunol. 2012;130(2):389-396.e4. doi:1016/j.jaci.2012.05.054
10. Peden DB. Effect of pollution on allergy/immunology. J Allergy Clin Immunol. 2018;141(3):P878-879. doi:1016/j.jaci.2018.01.017
11. Schiavoni G, D’Amato G, Afferni C. The dangerous liaison between pollens and pollution in respiratory allergy. Ann Allergy Asthma Immunol. 2017;118(3):269-275. doi:1016/j.anai.2016.12.019
12. Shan Y, Wu W, Fan W, Haahtela T, Zhang G. House dust microbiome and human health risks. Int Microbiol. 2019;22(3):297-304. doi:1007/s10123-019-00057-5
13. Liew WPP, Mohd-Redzwan S. Mycotoxin: its impact on gut health and microbiota. Front Cell Infect Microbiol. 2018;8:60. doi:3389/fcimb.2018.00060
14. Moelling K, Broecker F. Air microbiome and pollution: composition and potential effects on human health, including SARS coronavirus infection. J Environ Public Health. 2020;2020:1646943. doi:1155/2020/1646943
15. Arrieta MC, Stiemsma LT, Dimitriu PA, et al. Early infancy microbial and metabolic alterations affect risk of childhood asthma. Sci Transl Med. 2015;7(307):307ra152. doi:1126/scitranslmed.aab2271
16. Lynch SV. Gut microbiota and allergic disease. New insights. Ann Am Thorac Soc. 2016;13(Suppl 1):S51-S54. doi:1513/AnnalsATS.201507-451MG
17. McKenzie C, Tan J, Macia L, Mackay CR. The nutrition-gut microbiome-physiology axis and allergic diseases. Immunol Rev. 2017;278(1):27-295. doi:1111/imr.12556
18. Barnig C, Reboux G, Roussel S, et al. Indoor dust and air concentrations of endotoxin in urban and rural environments. Lett Appl Microbiol. 2013;56(3):161-167. doi:1111/lam.12024
19. Lai PS, Sheehan WJ, Gaffin JM, et al. School endotoxin exposure and asthma morbidity in inner-city children. Chest. 2015;148(5):1251-1258. doi:1378/chest.15-0098
20. Gehring U, Bischof W, Fahlbusch B, Wichmann HE, Heinrich J. House dust endotoxin and allergic sensitization in children. Am J Respir Crit Care Med.2002;166(7):939-944. doi:1164/rccm.200203-256OC
21. Gehring U, Strikwold M, Schram-Bijkerk D, et al. Asthma and allergic symptoms in relation to house dust endotoxin: phase two of the International Study on Asthma and Allergies in Childhood (ISAAC II). Clin Exp Allergy. 2008;38(12):1911-1920. doi:1111/j.1365-2222.2008.03087.x