Spring is in the air… flowers are in bloom and my annual tradition of the flat deep clean has begun. The air is adrift with pollen and dust, and you may have noticed that the TV Benedryl ads have upped their frequency. Allergy has become a common part of our day-to-day living. Only this weekend I had to warn my nut-allergic flat mate that I had eaten peanut butter on toast (meaning take care in the kitchen and have your epipen to hand!).
It is estimated that each year the number of allergy sufferers in the UK increases by 5%. It has also been estimated that by 2015 50% of Europeans will suffer from an allergy! Interesting however studies have shown that allergy (and autoimmune conditions, such as MS and Rheumatoid arthritis), are much less common in the under-developed world. This has been attributed to the lower level of cleanliness- an idea also commonly referred to as the Hygiene hypothesis.
The Hygiene hypothesis: due to the cleanliness habits of modern Western living (with increased usage of anti-bacterials and antibiotics), we are progressively reducing our exposure to disease-causing pathogens. Conversely, within developing countries the average immune system is under constant pressure with often on-going parasitic, viral and bacterial co-infections requiring a very tight immune regulation. The now reduced work-load applied to the average Westerners immune systems means it is much less efficiently controlled and resultantly initiates an inflammatory reaction in response to normally non-pathogenic molecules such as food/dust (in the case of allergy) and self-molecules (in the case of MS and RA).
In support of the hypothesis… longitudinal studies in the third world have demonstrated an increase in immunological disorders as a country grows to be more affluent and, it is presumed, cleaner! MS patient who are infected with parasitic have been shown to suffer less disease relapses than parasite-free patients. Also worth watching is the incredible Embarrassing Bodies video diary of Dr. James Logan, who after infecting himself with hookworm enjoyed a pizza for the first time having suffered with life-long bread intolerance!
However no biologic support for the hypothesis has ever been directly demonstrated. Until now! Researchers at Brigham and Women’s Hospital recently published a study comparing mice living in a germ-free environment with mice living in a normal environment with microbes. The germ-free mice were found to have exaggerated inflammatory reactions caused by the hyperactivity of a unique class of immune cells. It was also found that exposing the germ-free mice to microbes during their first weeks of life, but not when exposed later in life, led to a normalized immune system and long lasting prevention of inflammatory disease. Richard Blumberg, co-author of the study published in Science online explains how
“these studies show the critical importance of proper immune conditioning by microbes during the earliest periods of life”
It is exciting to think that science is now on road to discovering the microbial factors that may be important in determining protection from allergic and autoimmune diseases later in life.
For more information see: http://www.sciencemag.org/content/336/6080/489
Author – Andrea McConnell, Account Manager