Friday, 4 May 2012

When poo tells a story (and I'm not talking about Winnie)

If you sprinkle while you tinkle,
be a sweetie and wipe the seatie.
Bear with me on this post but probably best if you're not eating when reading this.

When was the last time you watched a film and saw any of the protagonists pop into the toilet for a 'number two'? Seriously now. Did James Bond ever stop to think about the yummy Brussels sprout curry he ate last night washed down with a vodka martini or two? Come to think about it, does anyone know where the toilets were on the Millenium Falcon, to the sound of Han Solo telling everyone to 'give it about 10 minutes' to air? (May the 4th be with you by the way).

I know it is a bit gross to think about poo, stools, kaka, whatever you want to call it. But move past the sight, smell and visualising of people, well-known people, sat on the 'throne' and think a little about how our poo might actually be able to tell quite a bit about us. While that thought remains, have a look at this paper by Wang and colleagues* (full-text) on the analysis of fecal bacteria from children with autism.

I am discussing this paper for several reasons: the growing interest in gut bacteria and autism, the potential link with gut barrier dysfunction - the so-called 'leaky gut' - and the Australian research group who conducted this study who are fast becoming part of the Premier League of autism research to match the MIND Institute and the very impressive Saudi researchers.

The details of the Wang study:

  • Similar to their study on short chain fatty acids and ammonia, the participant group comprised 23 children with an autism spectrum condition, 22 siblings and 9 asymptomatic controls.
  • A number of fecal - poo - specimens were collected from each participant over 48 hours, bagged, tagged and shipped out for PCR analysis of various types of target bacteria.
  • Results: well, there were quite a few interesting results such as a lower relative abundance of Bifidobacterium spp. in samples from children with autism compared to controls. A similar finding was also reported for Akkermansia muciniphila, a bacterium that I have never come across before but as the authors note, is a mucin degrading bacterium and seemingly quite abundant in samples from other groups.
  • The lower concentrations of A. muciniphila were potentially indicative of a thinner gastrointestinal mucus barrier and onwards to impaired gut permeability aka the leaky gut.

A. muciniphila is a mucolytic bacterium - mucolytic similar to an old friend NAC - and evidence drawn from inflammatory bowel diseases such as ulcerative colitis suggests that lower substrate levels as a function of an already thinner mucosa may lead to lower bacterial numbers to be present. One could therefore see where the authors were coming from when they detail such findings as potentially being ".. indirect evidence of impaired gut permeability in ASD children and their first-degree relatives". I should also point out that this is not the first time such sentiments been expressed as per the excellent gut permeability study from Laura de Magistris and colleagues a few years back.

The findings whilst unique so far in autism research do seem to mirror, to some degree, other areas of research such as this paper on weight gain during pregnancy. I'm not exactly sure how and why women who gain excessive weight during pregnancy and children with autism might be biologically and microbiologically similar, unless one assumes that there might be a link from mum's bacteria to child's bacteria (see this full-text paper by a very interestingly named person called Fåk and colleagues**) and dare I mention that other recent study which received so much attention. That and the possibility of ethnic differences as a function of factors such as breastfeeding (or not) complicate matters somewhat. I'm not really qualified enough to go any further into these areas.

If one however does assume that gut bacteria is involved in some cases of autism in whatever way, shape or form, all those 'wacky suggestions' about things like probiotics and bacterial transplantations might turn out to be not so daft after all (even the stool transplant science is gaining research ground!). No medical advice intended.

To finish and to erase all those harrowing mental images of toilets and poo, something altogether different from Sparks and Good morning. Indeed, good morning if you are reading this in the morning.

* Wang L. et al. Low relative abundances of the mucolytic bacterium Akkermansia muciniphila and Bifidobacterium spp. in feces of children with autism. Applied & Environmental Microbiology. 2011; 77: 6718-6721
DOI: 10.1128/AEM.05212-11

** Fåk F et al. Microbial manipulation of the rat dam changes bacterial colonization and alters properties of the gut in her offspring. American Journal of Physiology: Gastrointestinal & Liver Physiology. 2008; 294: G148-G154.
DOI: 10.​1152/​ajpgi.​00023.​2007