Current concepts in chronic inflammatory diseases: Interactions between microbes, cellular metabolism, and inflammation

You are more than just one human being.  That may sound like an inspirational quote, but it’s actually a scientific fact: there are literally millions of bacteria living on, in, and around you that play crucial roles in the ways that your body and your mind work.  And now, thanks to newer technology, we have the ability to see how these ‘old friends’ – bacteria have likely been around since the emergence of humans – interact with our own cells to change how our immune system works.
In this month’s issue of the Journal of Allergy and Clinical Immunology, Garn and colleagues provide an overview of how these microbes influence our metabolism and can lead to inflammation, based on the insights from the International von-Behring-Röntgen-Symposium (J Allergy Clin Immunol 2016; 138(1): 47-56).  While our knowledge of the microbiome keeps on growing, the fact is that there remains so much to be researched.  For example, how does our modern age of hygiene, where we have eliminated so many of the old infectious agents with which we have co-evolved, impact chronic inflammation?  How do resident microbes interact with food to cause inflammation, or resolve it?  What role does biodiversity (which plummets while on antibiotics) play in maintaining the balance between promotion and resolution of inflammation?  And how do these microbes educate our immune systems during infancy and childhood?  Unfortunately, these questions remain mostly unanswered but there are some promising leads.  For example, a study involving 560 babies of families from Baltimore, New York City, and St. Louis demonstrated that exposure to allergens in the first few months of life may be associated with a reduced risk of recurrent wheeze, while exposure to microbes may reduce both the risk of atopy and atopy plus wheeze.

Extracellular RNA, DNA, and proteins that may come from microbes have been shown to mediate inflammation.  These molecules alter the cytokines released by our own cells, and can lead to upregulation of inflammatory responses.  While research is extremely preliminary, the influence of the microbiome on allergic, autoimmune, gastrointestinal, and neuropsychiatric disease is becoming more and more appreciated, possibly opening doors to new management strategies.  So embrace your inner germs and realize that you’re more than just one, sole human being.

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