Image: Lactococcus lactis, basonym Streptococcus lactis/Minyoung Choi An oft-repeated (and oft-misinterpreted) fact is that there are ten times more bacterial cells found in the human body than there are actual human cells. While this doesnt really make us mostly bacteria in the factoid sense pushed by cherry pickers like Michael Pollan, it does mean that our own health is impacted in powerful and poorly understood ways by the happenings of these colonies of non-virulent microorganisms. Collectively, these colonies are considered by some researchers to be a sort of forgotten organ or virtual organ, with gut flora doing some of the heavy lifting of (at least) the bodys immune and digestive systems, while demonstrating metabolic activity roughly equal to a proper organ-organ. Its tempting to look at bacteria as a kind of binary realm, with good and the bad sorts that have good and bad impacts on health, when its really not that easy. Our own personal bacterial flora might help keep harmful bacteria at bay through competitive pressure, but the goodness of these tiny helpers is less a function of benevolence than geography—set them loose elsewhere in the body, beyond the inner-outside of the digestive tract, and very bad things will happen. A different set of bad things awaits a host with just a bit too much or too little friendly bacteria, ranging from cancer to inflammatory bowel diseases. While its possible to live without gut flora, such an existence portends a wide variety of troubles. One fascinating aspect of this would-be dualism is how the bacteria that we provisionally know as friendly and harmful interact with each other. We know well enough that our gut flora help us out with immunity and keeping virulent bacterial invaders at bay, but its hardly because of some secret intraspecies armistice. A study out this week in the journal PLOS ONE examines the response of gut flora (in mice) to colitis-causing bacterial infection elsewhere in the body, finding that our own personal colonies of helper bacteria get sick themselves in a very real sense. Its an observation that paves the way for not just better understandings of bacterial interrelationships, but also early warning tools for diseases. Its estimated that there are up to a thousand different species of bacteria calling the human body home, and its likely that some large portion of these species will remain unidentified for a long time to come. And because the specific make-ups of those thousand or so species vary human to human, it becomes rather difficult to make observations on the dynamics of individual species; mostly, researchers are able observe overall bacterial communities, rather than bacterial houses or neighborhoods. This creates something of an information black box for gut flora. The current study employed a recent algorithm known as the Microbial Counts Trajectories Infinite Mixture Model Engine to get a higher-resolution view of bacterial dynamics than previously possible, with the result being population changes observed in a small handful of species, with at least one species fading away during a virulent infection, and with a pair of others showing population spikes once the infection cleared. Critically, the species that declined, a member of the recently-identified genus Mucispirillum, began its tumble before the onset of infection-related symptoms, a presickness sickness. One intriguing feature of the changes is that they didnt always occur in the presence of the actual infection: sickness at a distance, a reflection of the effects of systemic host responses elicited in response to the colitis, in the papers words. The study suggests the possibility of using the bacterial group containing Mucispirillum, which partially comprises the muscous lining of the intenstines, as a tool providing, a marker for health of the surface mucus layer in distal colon, with potential application to other models of inflammatory colitis. So, rather than a colitis patient showing up in agony during a flare-up, it should be possible to detect a flare ahead of time, possibly heading it off and eliminating a lot of misery and damage—damage that can take weeks to heal and in some cases never heals at all, leading to very bad things, including the surgical removal of portions of the colon. From a clinical perspective, these new microbial signatures we identified could help clinicians detect early stages of inflammation or subtle persistent disease in patients with gastrointestinal disorders, such as inflammatory bowel disease, noted Lynn Bry, the studys senior author, in a statement. Moreover, several time-dependent microbial signatures we identified may be leveraged to conduct further research of other infectious and inflammatory conditions.
Posted on: Sat, 12 Jul 2014 22:33:24 +0000
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