We Are Not Alone
If you are looking for a trendy term to impress your friends or co-workers, try microbiome. The microbiome refers to the fascinating world of microorganisms (bacteria, viruses and fungi) that not only fill every nook and cranny of the planet we live on but also every nook and cranny of our own bodies.
By some estimates, we have as many microbes living in our bodies as we do our own cells. (Wouldn’t that be a cool fact to throw out at a dinner party?) For the most part, those microbes living in and on our bodies share a symbiotic relationship with us, meaning they help us and we help them. Supposedly, my dog and I share a symbiotic relationship: I provide him food and shelter and he, well… he hangs around the house looking cute and chewing up my shoes and socks. (Come to think of it, this may be more indicative of a parasitic relationship.)
Not only do the microorganisms in our body help us digest our food, produce vitamins and help fight off infection, they play an important role in regulating our immune system. From infancy on, these single-celled animals communicate with our immune system and explain the ways of the world to it. It is believed that this early-life education is essential for our immune system to grow up and act appropriately: attacking bad guys – like the measles virus – and not reacting with good things like breakfast or the dander from the sock eating dog.
Of course, the process of this early-life microbial education can involve infection. And yet, these are usually not life threatening infections, and the end result is a strong, wise and well behaved immune system.
We No Longer Live in the Garden
Getting back to the question of what went wrong to cause us to have allergies, one of the theories is the hygiene hypothesis which proposes that our immune system is adapted to an environment that – at least for people living in Ahwatukee and most of the westernized world- no longer exists. At one time in our history, our environment was much more complex and diverse from a microbial point of view with exposure to farm animals and other elements of a farming environment as well as large families with lots of runny-nosed siblings to play with. The hygiene hypothesis was proposed in 1989 when researchers noticed that children who grew up on farms or who came from large families with lots of siblings had fewer allergies.
The explanation? Progress and myriad changes associated with modern life such as a decrease in natural birth deliveries, antibiotic use, lack of breast-feeding, pasteurization, Lysol in every kitchen and bathroom, and antimicrobial everything (hand wipes, mouth wash, soaps, detergents) – not to mention a noticeable lack of cows, chickens, and pigs in the yard -reduce an infant’s exposure to the wise microbe masters that once kept or immune system from going down the path of the dark side.
Just as children who grow up in an overly protective, sterile, and restrictive parental environment may have difficulty coping with challenges later in life, our pampered undirected immune system may react inappropriately.
The unintended consequence of our quest to control everything has been the emergence of allergy and other chronic inflammatory diseases. Who knew?
Now that we are beginning to understand why we develop allergies, the big question is how to fix it. Allergy immunotherapy or desensitization is essentially a way of re-educating the immune system to behave more appropriately towards our environment. It is not a quick fix, but the end result can be life-long immunity to things we are allergic to. New forms of immunotherapy are in the works that combine conventional immunotherapy with elements of the microbiome to mimic the type of early-life training that has been lost (along with paradise).
Brian Millhollon, MD