Soltalk December 2017 | Page 44

Doctor’s notes
Dr Rik Heymans is a general practitioner in Nerja and writes on developments in the world of medicine
The world we are living in is less clean than we would like it to
be. In fact, we are living literally surrounded by a sea of
microbes, some of which seemingly just wait for an
opportunity to invade, decompose and digest our organism.
However, this does not happen as evolution has developed a
dual strategy. First, our body is sealed by largely impermeable
surfaces (skin and mucous membranes) that prevent most
outside microorganisms from entering. Second, those few bugs
that may have made it into our tissues are spotted, pursued
and neutralized from inside by our immune system and
defenses. Our intestinal microbiota are profoundly shaped by our
dietary habits. It is, therefore, not too far-fetched to predict
that autoimmune diseases could be prevented or treated by
special feeding programs. In fact, attempts to link MS to
dietary habits and to treat the disease with alimentary
regimens have been manifold, and they date back way into the
past century. An early study of rural Norway, for example,
found that a population feeding mostly on milk products had
an increased risk of disease, as compared with their fish-eating
neighbours. Dietary interventions reported remarkable results,
although rigidly designed studies are still awaited.
Immunology has been termed the science of self/nonself
discrimination. Indeed, the immune system’s cardinal mission
is to distinguish the body’s own components (self) from any
foreign structure (non-self) intruded into the body. Self-
structures must be tolerated, whereas non-self material, which
includes infectious agents, must be eliminated. This seemingly
clear-cut confrontation is blurred by a third, most powerful
player in the field: the universe of our microbiota, the
commensal microbes colonizing our body’s outer surfaces, as
well as the linings of our caves, most importantly the gut. To
appreciate their power, it is worthwhile to remember that we
carry in our bowels ~100 trillion bacteria, densely packed
within the intestinal lumen. Finally, as a radical way to manipulate a potentially pathogenic
gut flora, faecal transplantation has been used to mitigate
severe inflammatory bowel disease caused not by autoimmune
attacks but by pathogenic bacteria. Infusion of faecal bacteria
sampled from healthy donors significantly reduced pathogenic
Clostridium difficile organisms, introduced a stable
commensal flora, and ameliorated diarrhoea in the majority of
treated patients. And studies are gradually starting to look at
these treatments, in order to control and perhaps even cure
more and more diseases and conditions triggered by a
deficient auto-immune response.
© Dr RIK HEYMANS
c/ Angustias 24, Nerja.
Tel: [phone]
Naturally, the gut microbiota are our welcome partners, vitally
involved in helping us digest our diet. But quite unexpectedly,
it now turns out that, way beyond this, these microbes
profoundly influence the body’s functions on a general level.
Microbial interactions with the immune system are
indispensable in helping develop and maintain the system’s
full functionality. However, there is a downside to this
partnership: in particular circumstances things may go wrong,
and our commensals can trigger autoimmune responses.
Importantly, gut microbiota are highly dynamic. Their species
composition changes over time, and some bacteria are more
volatile than others. Inoculation of the germfree neonate
happens directly during birth, with vaginal (and possibly breast
milk) germs being the microbial pioneers. Healthy microbiota
are protective, curbing invasions of potentially pathogenic
bacteria; they also provide colonization resistance, by
outcompeting pathogenic organisms for nutrients or
stimulating host responses.
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