Posted by Katie Alexander
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| Green Fluorescent Protein (GFP) labeled bacteria |
As a member of the Elson lab at UAB, I examine the
relationships between a certain cell type, regulatory T cells (Tregs), and the
microbiota. Tregs are major players in immune tolerance and homeostasis, the
policemen of the immune response. They are essential in anti-inflammatory mechanisms.
Recently, researchers have shown that certain species of bacteria effectively
induce Tregs and anti-inflammatory responses (1). Conversely, other types of
bacteria encourage pro-inflammatory cells to thrive and can damage the immune
system. During IBD, the microbiota becomes unbalanced, and the bacterial species
associated with inflammation tip the scales in their favor, ousting the beneficial
bacteria. This is also what happens when a person is infected with the
bacterium Clostridium difficile (C.diff).
Additionally, bacteria can interact with components of our
food directly. A recent report by Suez et al. (2) outlined the relationship
between non-caloric artificial sweeteners (NAS) and the microbiota. NAS are
ubiquitous in the Western diet, with saccharin and aspartame being some of the
most commonly used. Interestingly, our bodies do not recognize NAS and
therefore cannot absorb or use them as energy sources. For that reason,
numerous health officials have considered these sweeteners harmless, or in the
case of a person with diabetes, beneficial. Suez and colleagues demonstrated that NAS
interact closely with intestinal bacteria, causing shifts in the balance of
good and bad bacteria. In fact, mice subjected to a diet supplemented with NAS
were susceptible to increased glucose intolerance. This finding was
recapitulated in a small-scale human study. It is obvious that microbes affect
countless aspects of human health, and therefore further research into
understanding how to maintain a healthy population of microbes will contribute profoundly to overall human wellbeing.
References:
Atarashi K. et al. Induction of colonic regulatory T cells
by indigenous Clostridium species. Science. 2011. Jan 21:331(6015):337-41.
Suez J. et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014 Oct 9:514 (7521):181-6.
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