Tuesday, 20 December 2011

Diagnosis by gut bacteria?

Please don't take the title of this post too literally. Sciences is only just beginning to unravel the first strands of the complicated universe that is our gut microbiota but two recent papers certainly do make for some interesting reading.

The first paper by Iebba and colleagues* provides quite a nice summary of where we stand (research-wise) with regards to different bacterial species seemingly predominating in different childhood conditions. The second paper by Jeffery and colleagues** details the intriguing possibility that irritable bowel syndrome (IBS), or some phenotypes of IBS based on the presence of functional bowel disturbances, might be classifiable by the predominating types of gut bacteria.

The Iebba paper was of double (triple) interest to me because it mentioned autism, coeliac disease (CD) and inflammatory bowel disease (IBD) in the same sentence. In particular, the prevalence of Bacteroidetes alongside a parallel decrease of Firmicutes was a commonality between these three conditions; the first time I've seen a research group looking (bacterially) at these conditions together. I have to point out that autism is an extremely heterogeneous condition with quite a lot of scope for comorbidity; hence I am careful with any generalisations.

By contrast the Jeffery paper, although based on quite a small participant group, suggested quite a few things including that cluster analysis might be able to 'pick out' those cases of IBS associated with diarrhoea compared with those where constipation or alternating bowel habits were more common. Interestingly, their analysis also reported the opposite trend in terms of an increase of Firmicutes-associated taxa and a depletion of Bacteroidetes-related taxa in some of their participant cases. This alongside other related findings which perhaps indicate that the so-called 'leaky gut' (gut hyperpermeability) might also show some differences in terms of site when sub-categorising IBS on the basis of predominant functional bowel patterns.

Aside from factors such as different ages, different populations, different genders, et al, all of this makes me wonder about things like the immune system differences between conditions like IBD and CD compared with IBS. Indeed a few open questions: do the gut bacteria findings in autism perhaps reflect similar immune features to CD and IBD or is it all merely a coincidence? Is IBS an immune-mediated condition the same way as CD or IBD are or are other forces at work?

Without getting too Arthur C. Clarke, there are lots of potential possibilities to these collected works based on our individual and collected patterns of gut microbiota. Unlike fingerprints or retinal scans, gut bacteria is perhaps slightly more dynamic as a function of diet, environment, etc. and so is probably not going to be biometrically encoded onto your passport any time soon. Having said that, if the subtle differences between our gut bacteria might also be reflective of our condition or disease, this could potentially offer some quite startling insights into the way medicine diagnoses and also manages a wide variety of conditions.

Finally, this is probably my last post on this blog until the New Year. I would like to wish readers Merry Christmas and a Happy New Year. I raise a glass of water to your good digestive health over the holiday period!

* Iebba V. et al. Gut microbiota and pediatric disease. Digestive Diseases. December 2011.

** Jeffery IB. et al. An irritable bowel syndrome subtype defined by species-specific alterations in faecal microbiota. Gut. December 2011.

Thursday, 15 December 2011

The leaky gut and chronic fatigue syndrome

I've mentioned the TV programme called the Food Hospital before on this blog in a post not so long ago about Crohn's disease and the LOFFLEX diet. Having watched the episodes so far as well as the various social networking chatter about the series, my conclusion is that it is rather a brave programme to broadcast in terms of 'treating' various medical conditions simply with adjustments to diet. I will perhaps lay my stall out to you in that I am swayed by some of the arguments that food, certain foods, do place certain people at a health disadvantage outside of known food-related conditions such as coeliac (celiac) disease and PKU. The emerging data, albeit preliminary, on some cases of autism and ADHD seems to be pointing in that direction for example.

The latest programme aired on Tuesday 13 December (2011) again presented some interesting 'cases' and the potential link to food. One particular cases was that of a woman diagnosed with Chronic Fatigue Syndrome (CFS). I don't want to get too bogged down with a description of CFS (and CFS/ME) because it is quite complicated. Without blowing my own trumpet, I was involved in a paper on trying to describe CFS a while back which suggested that quite a few symptoms might be variably expressed including physical, somatic features alongside other more cognitive issues. The bottom line is that CFS/ME is a real and very often complicated condition.

The Food Hospital suggested a few things in terms of diet which might be useful for the particular lady with CFS in question. Outside of chocolate being suggested (and not doing particularly well in this case) I thought I also heard the suggestion that a glutamine-rich diet might also be something to try. My attention was grabbed by this suggestion for a very good reason: glutamine (also called L-glutamine) has some interesting effects on the gastrointestinal (GI) tract and in particular, intestinal permeability.

Maybe I should back up a little here. Glutamine is an amino acid, a building block of protein. For quite a few years, glutamine has been finding some favour in relation to improving the structural integrity of the intestinal barrier in both humans and animals and potentially relieving the so-called 'leaky gut'. Leaky gut is a bit of a misnomer because everyone has leaky gut to some degree; the better description would perhaps be gut hyperpermeability or excessive leakiness.

With regards to CFS/ME, as with other conditions, leaky gut has been reported in the research literature and commented on elsewhere. One name seems to crop up quite a lot in this area of investigation, Dr Michael Maes and not just with regards to CFS/ME. It seems leaky gut might have the potential to do all manner of things. So putting leaky gut, CFS/ME and glutamine together might make some sense? Aside from the paper from Maes, I have been unable to find any other published trials of glutamine for CFS/ME which is a shame really, given that a double-blind, placebo-controlled trial of a solitary supplement like glutamine should be a pretty straight-forward experiment to do (he says with a straight face). Any budding researchers out there with a few hundred thousand pounds to spare could do a lot worse than put such an experiment to their boss and local ethics committee.

I would finally add that as per the tenets of this and my other blogs, I don't give out medical advice and am not suggesting for one minute that glutamine is a cure-all for CFS/ME. I do however reiterate that for a condition like CFS/ME where more questions are being asked than answered, every experimental and research avenue should be explored.

Friday, 2 December 2011

Probiotics, probiotics, probiotics

Do you ever have one of those days where a certain word seems to keep cropping up again and again no matter where you turn? Well, today is one of those days for me, and today's word is probiotics. Like a good dose of influenza (if there is such a thing as a good dose), I just can't seem to shake that word today.

So here are the papers with that word:

Delzenne and colleagues* (open-access) report on an interesting relationship between gut bacteria and obesity with a specific focus on studies looking to 'alter' the gut microbiota via pre- and probiotics and the various reported outcomes based on anthropometric and biochemical parameters linked to obesity. I talked about something similar a few months back on a sister blog.

Min Tan and colleagues** (open-access) report on the quite positive effects to patients recovering from traumatic brain injury in intensive care following administration of probiotics. Based on a relatively small patient group, patients (n=52) were randomised into either a nutrition + probiotics group or a nutrition alone group. Feeds were administered via a nasogastric tube initially which then progressed to the 'by mouth' route when patients were well enough. Various serum cytokines and related immune markers were analysed over the course of the study which lasted for 21 days.

Unfortunately some of the patients did not make it following their group allocation as sadly might be expected following a serious brain trauma. Other patients developed complications following their accident which did not seem to differ in quantity statistically between the groups aside from the number of pathogens potentially related to infections: fewer pathogens in the probiotic group. The probiotic group (the probiotic including Bifidobacterium longum, Lactobacillus bulgaricus, and Streptococcus thermophilus) did however show an altered immune profile to the control group in terms of indications of the Th1-Th2 slant to the immune system. Although perhaps a little simplistic, Th1 represents the fighting infection side of the immune system and Th2 is the production of antibodies side of things. The probiotic group showed an immune profile more representative of the Th1 response, speculated to be important for their speedier recovery and their less frequent use of antibiotics.

Although the results were not totally astounding in this study, there is an important clinical lesson from this trial in that patients spent statistically less time in intensive care and relied on fewer antibiotics during their recovery as a result of probiotic administration. For patients and physicians alike, this has got to be a good thing.

Finally, ScienceDaily carries an interesting statement from the Annual Scientific Meeting of the American College of Gastroenterology (ACG) regarding probiotics and the potential anti-inflammatory properties of certain types of probiotic. I like to sound of the collected press conference for the studies listed in this release: "Good, bad and ugly bugs: Mother Nature as a treatment for better health in the GI tract". As per the release there are a few headlines including:

  • A meta-analysis of studies looking at the use of probiotics used to reduce cases of antibiotic-associated diarrhoea (diarrhea) concluded that yep, probiotics, and particularly that most lovable to yeasts Saccharomyces boulardii, do a pretty good job at curbing your risk of this quite unpleasant condition.
  • The use of Bifidobacterium infantis 35624 for those suffering from recurrent abdominal bloating and discomfort did not fare too well in a new randomised-controlled trial. B.infantis 35624 had previously shown some interesting positive results for those with irritable bowel syndrome (IBS).
  • Having said that, it was not all bad news for B.infantis 35624 as per another trial which suggested that the probiotic might have some pretty good anti-inflammatory properties when it comes to those dastardly pro-inflammatory cytokines. Indeed that most common of inflammatory markers, C-reactive protein seemed also to be reduced in cases of psoriasis, ulcerative colitis and even in chronic fatigue patients following probiotic administration.

What then can we assume from these collected studies. Well, at least in the short-term under various controlled conditions, probiotics, various probiotics, might just be able to influence our health and ill-health particularly in certain conditions/states. As per my previous post, our collected gut bacteria is a complicated organism which talks to our immune system in ways we are only starting to understand. Like every married couple, sometime the talk is positive and healthy; other times the talk is slightly less healthy... (not in front of the kids!).

Whether in the longer-term, supplementing with probiotics offers any added benefit, I don't know. Speculation (and it is only that) would perhaps suggest that the way probiotics are delivered (those all important enteric coatings), how our immune system recognise bacteria as 'self' or 'not-self' and good old homeostasis (the body's drive to keep harmony) are all factors potentially affecting the ability to make a more permanent shift in our not-so-good bacterial species to those preferred choices. Indeed this last point on what is good and bad gut bacteria perhaps needs a little more research in terms of the effects of individual species, etc on health and wellbeing.

* Delzeene NM. et al. Targeting gut microbiota in obesity: effects of prebiotics and probiotics. Nature Revs. November 2011.

** Min Tan. et al. Effects of probiotics on serum levels of Th1/Th2-cytokine and clinical outcomes in severe traumatic brain-injured patients: a prospective randomized pilot study. Critical Care. December 2011.

Tuesday, 29 November 2011

Innate immunity and the gut microbial ecosystem

A quick-ish post following the publication of a real fact-finding paper by Larsson and colleagues* (full-text). The aim of the paper was to map out how innate immunity intersects with microbial composition along the length of the gastrointestinal tract in a mouse model.

If you are slightly adverse to mouse research I'm afraid that you won't like this study much, which basically looked at bacterial composition in twelve segments of the mouse gut corresponding to the small intestine, cecum and large intestine correlated with several hundred/thousand genes regulated by the gut microbiota.

I won't lie to you in that this is quite a complicated study to follow. My Mr Men take on it suggested a few important findings were presented:

  • In the small intestine, several thousand genes were regulated by bacterial microbiota. By comparison, fewer genes were regulated in the colon than other areas thought to be due to some shielding in that part of the gut from bacterial exposure.
  • Depending on whether the authors looked at wild or germ-free mice, there were some interesting differences in different parts of the gut for genes related to lipid and fatty acid metabolism and nutrient absorption and metabolism. Genes governing cholesterol biosynthesis seemed to be top of the pile when it comes to being affected by microbiota as a function of whether or not there was a loss of innate immune signalling (Myd88-deficient). 
  • When it came to gut barrier function along various stretches, gut bacteria had some ability to alter the expression of some important genes according to comparisons between germ-free and wide mice. 
  • Myd88-deficient mice showed alterations in the types of bacteria present, some signs of disordered antimicrobial resistance as well as being potentially more susceptible to viral infections such as norovirus.

I can't possibly do justice to the amount of data presented in this paper. Extrapolating from the mouse model to humans, this data suggests that we have an extremely important symbiotic relationship going on in our deepest, darkest recesses. A relationship between self and bacteria; where genes and environment seem to play key roles in how we metabolise our food, how we regulate our ability to take on bacteria and viruses, and ultimately how our health in other organs might just want to make reference to the gut also.

* Larsson E. et al. Analysis of gut microbial regulation of host gene expression along the length of the gut and regulation of gut microbial ecology through MyD88. Gut. November 2011

Friday, 25 November 2011

Gut bacteria and the immune system

Quite an interesting article by Lamousé-Smith and colleagues* has appeared on the potential gut bacterial requirements of the immune system. The paper is open-access so readers are invited to read it at their leisure.

The basic conclusion reached from this research is that the ability of a mouse (and by proxy a human being) to mount an immune response to a specific pathogen (bacterial or viral) might be to some degree affected by the presence/absence of certain gut bacteria.

In the case of this paper, researchers undertook investigations based on two different scenarios: (a) a mouse model where antibiotics were used to disrupt the normal gastrointestinal (GI) flora and (b) a germ-free mouse model who were subsequently colonised. Under such models, mice were injected with a suspension of ovalbumin (the main protein in egg white) and an immunity stimulator, Freund's complete adjuvant. The authors then looked at the mice ability to mount an immune response to the egg white protein (ova).

They noted a few interesting observations:

  • Administration of antibiotics lead to some interesting changes in the gut microbiota. I should perhaps mention that pregnant mice were given antibiotics in their feed so the changes were noted in both mother and baby mice when born. The specific combination of antibiotics given to pregnant dams - ampicillin, streptomycin and clindamycin -  seemed to particularly deplete Firmicutes and Bacteroidetes bacterial species leaving Enterobacteriaceae to dominate. I don't like the idea of labelling bacterial species as good guys or bad guys because that is a little generalised and unfair. Having said that the Enterobacteriaceae includes things like Salmonella, E.coli, Klebsiella and few more 'pathogenic' species among their lot; if they were people, these would be the ones not to hang around with. 
  • Those offspring mice born to mothers on antibiotics seemed to show similar changes to gut flora. Additionally, antibody titer levels to ovalbumin were lower in this group when compared to a non-antibiotic exposed group when immunised at 7 days. These findings were not replicated when injected at 14 days.
  • Looking at the second mouse model where gut flora was absent, the authors reported consistently lower titer levels across age and when injections were given. This finding was kinda confirmed when germ-free mice (those with no bacterial flora) were colonised via bacteria derived from normal gut flora mice (I guess a sort of bacterial transplant!) thereafter more appropriate antibody titer levels were noted .

Appreciating that these experiments were carried out on mice and quite a small group of mice, there are some interesting things to take from this research. Already on this blog discussions have ranged from gut bacteria and a possible link to coeliac disease to the potential usefulness of bacterial transplantation for certain bowel conditions. Within these pretty diverse areas, a common theme is a potential role for the immune system in terms of clinical outcomes. What this research adds quite nicely, is that our ability to fight infection, develop immunity might be quite a bit more complex than previously thought. Our gut bacteria potentially being a mediator of immunity.

Thinking back to some findings in that other field of interest to me, autism, I do wonder about the implications of this research. On a sister blog, I recently discussed a paper looking at carbohydrate metabolism and dysbiosis in cases of autism. One of the findings from that small-ish study was that levels of Bacteroidetes were in shorter supply. Coincidence or perhaps tied into some interesting data on antibiotic use? Given the various studies suggestive of problems with immunity at least in some people with autism, I wonder if we should be looking at the gut bacteria/immune system relationship a little more closely?

Of course it easy for me to sit here and speculate, compare and contrast. Precisely how our bodies make and utilise immunity is still a source of much research and investigation.

* Lamousé-Smith ES. et al. The intestinal flora is required to support antibody responses to systemic immunization in infant and germ free mice. PLoS ONE. NOvember 2011

Gut bacteria, pesticides and obesity

Although my interest in this blog centres on all things gut-related, within this huge area of research I am particularly interested in how our genetic makeup interacts with our environment and vice-versa. I suppose gastrointestinal (GI) conditions are ideally suited to this complex 'nature-nutrure' relationship as evidenced by conditions like coeliac (celiac) disease, the archetypal gene-environment condition.

An interesting paper has appeared by Hae-Sook Lee and colleagues* suggestive of an interesting 'threesome' between a species of methane gas producing microbe, organochlorine pesticides and obesity. The paper is open-access. A summary of the details:

  • Fecal and blood samples from 83 Korean women were analysed alongside anthropometric (body mass index) measurements.
  • Fecal levels of Methanobacteriales were quantified via qPCR and serum / fecal levels of various organochlorine pesticides (OCPs) were assayed via GC-MS among a selection of participants with detected or non-detected levels of Methanobacteriales.
  • The results: Methanobacteriales were present in about a third of patient stool samples (27/83). Higher Methanobacteriales levels were present in women with a waist circumference above 83cm than below and showed some connection with elevated BMI also. Higher fecal levels of Methanobacteriales were also associated with higher serum levels of the OCPs.

We do need to take a step back from these findings before making too many associations. The sample population is quite small and the numbers of people included for analysis of OCPs for example is even smaller. Bear in mind that just looking at three primary variables is not necessarily grounds for a relationship.

I am however struck by the 'suggestion' that gut bacterial content and obesity might either increase the risk of greater take-up of compounds such as OCPs or that gut bacteria might interact with our chemical environment to potentially predispose to conditions such as obesity. This latter hypothesis: OCP levels determining Methanobacteriales levels which in turn leads to increases in anthropometric measures is the author's preferred interpretation.

The authors discuss the properties of OCPs as being central to the finding i.e. lipophilic (fat or oil loving) and also note that Methanobacteriales are quite often used to biodegrade hydrocarbons such as petroleum. I have to say I have never really thought about industrial waste management being applied to the human model but perhaps should not be so surprised given the current interest in things like industrial biodigestion.

What this study does more than anything is to reaffirm the complexity of conditions such as obesity as well as providing some new targets, environmental and biochemical, which we should perhaps be exploring with a little more assiduity.

* Hae-Sook Lee et al. Associations among organochlorine pesticides, Methanobacteriales, and obesity in Korean women. PLoS ONE. November 2011.

Tuesday, 15 November 2011

Crohn's disease and the LOFFLEX diet

A short post this one following a very interesting series airing here in the UK called the Food Hospital. 'Let food be your medicine' was the mantra of a certain Greek gentleman called Hippocrates (or perhaps according to Bill and Ted, 'Hippo-crates') and that is exactly what this series is suggesting.

In the programmes so far we have seen conditions ranging from migraine to obesity discussed. Tonight's programme featured a particularly brave young woman called Laura who presented with quite a serious case of Crohn's disease. For those who want more information about Crohn's see here. The long and short of it is inflammation, discomfort and quite a few 'peripheral' symptoms; no recognised cure and a life of medication and possibly surgery. Certainly one of the more serious gastrointestinal (GI) conditions.

Anyhow true to the name, the Food Hospital investigated whether it was possible the manage some of the symptoms of Crohn's disease through dietary changes. The plan in question is highlighted here and included a 3-step dietary intervention beginning with a cessation of food intake and reliance instead on a liquid feed containing all the necessary nutrients, followed a few weeks later by the implementation of the LOFFLEX (LOw Fibre, Fat Limited EXclusion) diet finally followed by dietary challenge/rechallenge in the hope of identifying problem foods related to symptoms.

It was interesting to see that some success was reported whilst on the regime in terms of symptom reduction following a flare-up. This is not proof of anything but certainly an interesting case study (n=1). Looking at the scientific literature for the LOFFLEX diet, things seem to be a little bit sparse at the moment. I found this trial from Addenbrookes Hospital which was the first place to look at the diet (I think). I also noted an interesting name on the authorship list, Prof. John Hunter, who is quite an expert on all things gastroenterology and particularly a role for gut bacteria in various bowel conditions.

I await more research on this very interesting regime and its potential applications to other conditions.

Tuesday, 25 October 2011

Bacterial transplantation: undesirable but effective

We have a term common to certain parts of the UK: 'where there's muck, there's brass'. The more usual interpretation of this phrase is that where there is a dirty job to be done, so there is money to be made. In the case of this post on probably the most undesirable therapy ever, bacterial transplantation, money might be replaced with health.

The paper in question is this review by Ethan Gough and colleagues* (available full-text not anymore). I'm not going to go through the whole paper because it is was free to view to everyone. The bottom line is that following the identification of various literature on other-person derived stool infusions, 27 reports fulfilled author criteria for review, of which over 90% of patients reported on showed 'resolution' of their problems of Clostridia difficile infection or pseudomembranous colitis following a bacterial transplant. Perhaps more importantly, the reported rate of side-effects including the ultimate side-effect of death, whilst present, could not be directly attributed to the transplant but rather the disease transplant was attempting to treat.

I note the authors also discuss the likelihood that bacterial transplantation might also be useful for other bowel-related conditions including inflammatory bowel disease and irritable bowel syndrome (although I offer no endorsement for anything on this blog).

Despite the subject matter, I have to say that I am interested in the combined results of bacterial therapy. There are lots of questions to answer about the hows and whys of this method and importantly, what are we transplanting aside from bacteria, the gut virome for example? Assuming that gut bacteria or pathogens affecting gut health are non-responsive to more traditional anti-microbial forms of treatment, and looking at the success rates included in this review, I wonder also how many GI-related conditions might benefit from such an intervention. Extending GI disease to cover other conditions as a comorbidity also, such as autism and the bacterial work being done there or even Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME), does this mean we should be looking at this measure a little more closely rather than just squinting our eyes in disgust?

* Gough E. et al. Systematic review of intestinal microbiota transplantation (fecal bacteriotherapy) for recurrent Clostridium difficile infection. Clin Infect Dis. August 2011.

Friday, 21 October 2011

Cytokines and gut motility

A relatively short post this one.

I think most people would understand why gastrointestinal motility is important to our health and wellbeing. Too fast or too slow a transit time is likely to lead to some pretty uncomfortable symptoms and indeed could signal the presence of one of a number of complications.

A recently published review paper on motility in gastrointestinal disorders by Akiho and colleagues* (full-text here) caught my eye. I was interested in this paper because it reviews the association between gastrointestinal motility and the expression of cytokines as a function of which way the immune system might be skewed.

I should perhaps back-up slightly here and provide some commentary on the way the immune system can be poised (according to our current knowledge) and in particular the concepts of Th1 and Th2. A good overview of the T helper cells is here. In brief, it's all to do with different kinds of immunity and how our immune system attempts to strike a balance between cell-mediated immunity (Th1) and humoral immunity (Th2) depending on what particular pathogen the immune system is up against.

The Akiho review paper lists a number of the most common GI disorders currently in the medical dictionary and details what particular types of response and cytokines are tied into the disease state. So for coeliac (celiac) disease and Crohn's disease there is a predominantly Th1 skewed cytokine profile either associated with disease onset or perpetuation. In ulcerative colitis, it is more of a Th2-like response in terms of cytokines associated with the condition. The authors do make mention also about Th17-mediated inflammation (possibly linked to autoimmunity) but this is still very much an emerging area of investigation.

The authors then proceed to review the evidence that Th1-related cytokines seem to show more of an affinity with hypocontractality of inflamed intestinal smooth muscle (slowing down) and Th-2 show a more hypercontractility (speeding up).  This is perhaps too simplistic a view to take, one linked to one but not the other, given the number of cytokines tied into various GI states and the complexity of the whole thing. But their analysis of the current evidence base is an interesting one.

What work like this serves to show is that the our immune system is a fantastic piece of engineering constantly trying to strike a balance between fighting off pathogens and infections and invaders, whilst at the same time keeping the host (us) in working order, trying not to destroy us also. The presentation of GI conditions, many GI conditions, seem to reflect the inner workings (and malfunctions) of the immune system and when establishing how the immune system manifests itself in individual conditions, offers some tantilising insights into potential therapies.

* Akiho H. et al. Cytokine-induced alterations of gastrointestinal motility in gastrointestinal disorders. World J Gastrointest Pathophysiol. October 2011

Saturday, 15 October 2011

The emergency exits are here and here

The title of this post has very little to do with steward / stewardess instructions delivered just before take-off, despite my recently watching the very funny Walliams/Lucas series 'Come Fly With Me'. Rather, with a straight face, I refer to your route into the world and whether Mother Nature required a helping hand in bringing you from the comfort of your watery cocoon into the real world. Could your route of entry alter your risk of developing certain things in later life... say coeliac (celiac) disease?

I am going to keep this post brief because this is a question that I have tackled before on a sister blog post: caesarean section and coeliac disease? The crux of that entry was the emerging suggestion that people born via caesarean section (c-section) were at greater risk of coeliac disease than those who were pushed through the bacteria-filled birth canal.

Further evidence has now emerged concerning a possible relationship in this paper by Marild and colleagues*. The details summarised:

  • A case-control study where recorded pregnancy information was collected via a central database between 1973 and 2008.
  • Biopsy-verified coeliac disease (CD) was determined for 11,749 participants compared with 53,887 age- and gender-matched non-CD general population controls.
  • There was a positive significant association between elective c-section delivery and later CD diagnosis (p=0.005) but none for emergency c-sections.
  • Small for dates babies were over 20% more likely to develop CD also.
  • No other pregnancy variables showed an association with CD.

I quote from the author's final sentence of their abstract: ".. consistent with the hypothesis that the bacterial flora of the newborn plays a role in the development of celiac disease".

I must point out that whilst bacterial colonisation of the infant gut may be a variable in determining your risk of CD, it is most probably not the only important variable. I don't want anyone reading this entry and taking it to their healthcare provider as 'proof' of anything; it is not. Likewise I am not trying to overturn any 'too posh to push' arguments.

What however can be inferred from this paper is that there may consequences to every action; some consequence might be positive (such as getting a breech presenting infant out of mum and avoiding any very serious complications), some of them might be not-so positive. The trick is to see where this research leads and, just a suggestion, whether an early bacterial 'transplant' from mum to baby one day becomes the norm for those babies who don't end up traversing the birth canal. Just a suggestion.

* Marild K. et al. Pregnancy outcome and risk of celiac disease in offspring: a nationwide case-control study. Gastroenterology. October 2011.

Tuesday, 11 October 2011

I, claudin

There is no way that I can blog about the gastrointestinal (GI) tract without making mention of that wonderful barrier separating gut contents from the other recesses of our body. Without being too dramatic, I could probably say that I owe my livelihood to the gut barrier; as a consequence of much of my research career heading towards some involvement for the gut barrier at least in some cases of autism spectrum conditions.

A recent paper brought all the years of reading on this subject back to me with the suggestion of a link between intestinal inflammation and claudin-1. The paper by Poritz and colleagues* describes how key tight junction proteins like occludin and zonula occludens-1 (ZO-1) are decreased in inflammatory bowel diseases and how treatment of intestinal epithelial cells with the inflammatory cytokine TNF-alpha (sorry about the lack of Greek characters) seems to increase permeability (leaky gut). With all due respect to the authors, these findings are nothing new.

What was slightly more interesting from Poritz however were the findings in relation to the ratio of claudin-1 and occludin (C:O) as a consequence of cell treatment with TNF-a and what this ratio looked like in real life when comparing different intestinal diseases like Crohn's disease (CD) and ulcerative colitis (UC). Answer: decreased occludin and increased claudin-1 in diseased UC vs. non-diseased UC and normal colons and nothing spectacularly different in different disease-states of CD or controls.

Even to an interested amateur like me, this data indicate some things potentially very important: (a) ratios between multiples rather than independent statistics might yield more diagnostic information, and (b) there may be some underlying differences in the way that tight junctions might be affected in UC vs. CD.

I will come back to the leaky gut and various other things related to it at some point in the future no doubt. But for now if you really, really want some extra credits bedtime reading, here is an article that I always found invaluable on the subject (long yawn, adjust reading glasses and reach for that glass of scotch on the bedside table).

* Poritz LS. et al. Increase in the tight junction protein claudin-1 in intestinal inflammation. Dig Dis Sci. October 2011.

Tuesday, 4 October 2011

Gluten, bacteria and mouthwash

Peptides. Those short-ish chains of amino acids, are interesting characters. Therapeutically, certain peptides have the propensity to do great things as exemplified by compounds such as the glucagon-like peptides and speculation on a therapeutic role in conditions like diabetes and intestinal disease.

In terms of 'disease' and ill-health, other peptides have a slightly less desirable side; something which I have been interested in for a few years speculatively in relation to conditions such as autism and schizophrenia. Peptides, such as those immunogenic epitopes derived from gluten, in relation to coeliac (celiac) disease (CD) also perhaps show a less speculative negative side in terms of effect.

What can be done about these immune-stimulating gluten peptides? Well, you could try and break them down via enzymes such as endopeptidases. There are also lots of products on the market which claim to do similar things (bearing in mind that I offer no endorsement). A recent paper by Zamakchari and colleagues* also offers another potential solution: certain enzymes produced by bacteria with the propensity to degrade gluten.

Before you go scouring the Internet for some commercial bacterial supplement, know that the authors suggested that we might already have such bacteria in our 'oral cavity' (mouth in plain speak); in our saliva and dental plaque.

The paper summary:

  • Human dental plaque and saliva were collected from willing volunteers and the various oral micro-organisms cultured. Those bacteria with gliadin-degrading activity were identified by 16S rDNA analysis, a sort of molecular fingerprinting service.
  • Various bacterial strains were added to synthetic immunogenic peptide sequences from gliadin and the subsequent effects separated and characterised by a combination of reversed-phase HPLC and mass spectrometric detection (MS/MS).
  • The results: 27 aerobic and 30 anaerobic bacterial strains capable of metabolising gluten were found. All the final anaerobic strains cultured (n=10 fastest growing) were of the Bifidobacterium genus. The final aerobic strains (n=5 fastest growing) included bacteria of the Rothia genus.
  • Several tri-peptide combinations appearing in the greatest frequency within the larger gluten peptides were broken down by individual bacterial strains. Rothia mucilaginosa and Rothia aeria seemed to come out top in terms of their hydrolysing abilities in terms of amounts and time taken. This effect was also noted when the larger immunogenic epitopes were exposed to the Rothia strains. 

There are a few important points to be taken from this research. First is the suggestion that digestion starts in the mouth and that all important motherly advice 'chew your food properly'. Masticating (or chewing to us mere mortals) is an important first step in presenting the food we eat to the rest of our hard-working gastrointestinal (GI) tract. Second is the suggestion that dental plaque (alongside saliva) might actually serve some purpose rather than just being something associated with poor oral hygiene and bad breath. I am not for one minute suggesting that we should all stop our regular tooth cleaning routine; but perhaps just step back and think about when you clean your teeth and what products you might use in your dental hygiene routine. Finally (finally!) I am already a big fan of the idea that our relationship with bacteria, some strains of bacteria, is an important one. A primary implication from this work is that 'addition' of bacteria to food or whilst eating certain foods (bearing in mind the effect of pH on these bacteria) might actually serve as another tool in the arsenal against conditions like coeliac disease, and even gluten sensitivity when it comes to degrading those very difficult gluten peptides. Please note that I am not recommending anything from this point given the slightly more negative press from these strains; just speculating.

* Zamakhchari M. et al. Identification of Rothia bacteria as gluten-degrading natural colonizers of the upper gastro-intestinal tract. PLoS ONE. September 2011.

Friday, 30 September 2011

Parasitic infection, coeliac disease and inflammation

My day-to-day job does not normally include giving lectures and presentations but today was an exception. I was asked to give a short talk on autism, and specifically some of the more 'somatic' research aspects to the condition. One of the issues that cropped up during that talk was some discussion on how we might think that we are in charge of our behaviour, but more often than not external environmental forces might also influence us. By environment, I mean the physical environment we can see and interact with but also the more hidden aspects. Words like Toxoplasma gondii and schizophrenia were used as examples, but also some speculative suggestions about how other 'parasitic' infections might affect our health and wellbeing.

Such discussion brings me neatly to a recent paper by Henry McSorley and colleagues from Australia published in PLoS ONE. The crux of the paper (which is open-access) is that purposeful infection with hookworm might have some interesting positive effects on various aspects of inflammation in relation to coeliac (celiac) disease (CD).

I must admit that I have covered parasitic infection in a previous post on autism (here); the conclusion being that our modern-day obsession with hygiene leads to the eradication of certain parasitic species which have evolved alongside us, and with it, a suggested increase in things like inflammation and conditions manifesting inflammation.

It does appear that similar findings were reported by McSorley and colleagues, where:

  • A 2-stage clinical trial was undertaken. Trial 1: 20 participants in total with CD and on a gluten-free diet; 10 were randomly infected with the larvae of the hookworm (Necator americanus) administered via the skin, the controls were given topically administered chilli pepper. At 20 weeks post-infection (with a top-up at 5 weeks), a gluten-challenge was given. Trial 2: a follow-up control participants, infecting 7 of them with hookworm, top-up infection and gluten challenge.
  • Levels of duodenal interferon-gamma (IF-y) (sorry about the lack of Greek gamma symbols) and the cytokine IL-17A were significantly decreased in the hookworm infected group from Trial 1 post gluten challenge. This and other results led the authors to assume that helminth therapy might skew the immune response in CD towards a Th2 phenotype; in effect, a more anti-inflammatory response (see this article for a better description of Th1 and Th2).

I must point out that I am in no way advocating such parasite therapy for anyone. I am also under no illusion that these results suggest a simple relationship between parasite and inflammation because they do not. I am however drawn (again!) to the notion that such parasites might carry some important evolutionary function for human health and as such, our recent leanings towards cleanliness (next to Godliness apparently) and sterility might just be to the detriment of our health.

* McSorley HJ. et al. Suppression of inflammatory immune responses in celiac disease by experimental hookworm infection. PLoS ONE. September 2011.

Thursday, 22 September 2011

Psychiatric comorbidity and coeliac disease

A short post this one following the recent publication of a paper by Danielle Arigo and colleagues* on the psychiatric comorbidity potentially accompanying a diagnosis of coeliac (celiac) disease (CD) in women. There is nothing particularly earth-shattering about the fact that people with coeliac disease or gluten sensitivity might be at greater risk of other comorbidities, particularly those based outside of the gastrointestinal (GI) tract. If you don't believe me, check out the work of Drs Mario Hadjivassiliou and David Sanders for example and even the suggestion that parts of conditions such as autism and schizophrenia might manifest as a result of dietary gluten.

The Arigo study suggested that despite high compliance with a gluten-free diet, women diagnosed with coeliac disease (N=177) were still reporting symptoms for conditions like depression (37%) and 'disordered eating' (22%) (disordered eating I assume meaning a recognised eating disorder). Whilst the authors suggest that additional psychosocial care might be required for women with CD, I think that this study provides a small snapshot into a more a complex pattern of conditions which perhaps requires further exploration.

Depression for example has cropped up in other studies of CD. This paper suggested pretty much the same thing in gluten-free compliant children with CD and prominent 'internalising' symptoms particularly in females. So perhaps age is not the deciding factor here.

As for eating disorders and CD, you might expect that the adoption of a gluten-free diet might make a person more likely to concentrate on the food they eat, but would it necessarily promote an eating disorder? I find this a little hard to swallow but as yet can offer no other evidence-based explanation aside from the fact that this is again not the first time that an association has been made (see here). If I was to be ultra-speculative (careful!) I might go back to the autism connection, and the suggestion that there may be some overlap in the 'cognitive phenotype' between autism and eating disorders; could this possibly overlap with those 'best responder' cases to dietary intervention in autism spectrum conditions?

* Arigo D. et al. Psychiatric comorbidities in women with celiac disease. Chronic Illness. September 2011.

Wednesday, 14 September 2011

Coeliac disease in Type 1 diabetes

When I think of coeliac (celiac) disease and the various names attached to research on this exquisite sensitivity to gluten, I think of a few names with a good publishing track record in this area. First name out of the hat is Mario Hadjivassiliou. Second is David Sanders. Without turning this post into some idol worship, when I see new papers appearing from one or other of these guys, my interest is piqued.

So when this paper from Leeds and colleagues* appeared bearing both names on the author group, I was interested. When I saw that the paper was also looking at another autoimmune condition, type-1 diabetes alongside coeliac disease (CD), I was even more interested.

The main facts from the Leeds case-control study are:

  • The prevalence of CD in their cohort of people with type-1 diabetes was 3.3%. Although there is still some debate about prevalence of CD in the general population, it is generally accepted to be currently around 1%. Interestingly, 3.3% is exactly the prevalence of CD in cases of autism described in this paper from a few years back. What a coincidence. 
  • At diagnosis of CD, type-1 diabetes seemed to be associated with a higher prevalence of retinopathy, nephropathy and peripheral neuropathy. Some of these conditions have been noted in 'gluten sensitivity' alone.
  • Glycemic control was also worse in the diabetes-CD group, accompanied by lower HDL (good guy) and total cholesterol.
  • A gluten-free diet is generally well tolerated by individuals with CD and comorbid type-1 diabetes. 

I am excited by this research. Excited because as well as linking two autoimmune conditions, the genetics of which are starting to receive some attention, it extends into some other areas already discussed on this blog that may affect quality of life and importantly, longevity.

* Leeds JS. et al. High prevalence of microvascular complications in adults with type 1 diabetes and newly diagnosed celiac disease. Diabetes Care. September 2011.

Thursday, 1 September 2011

The gut virome

Our gastrointestinal tract is alive. Teaming with all sort of weird and wonderful compounds and organisms, it truly is a world within a world. Metabolites from food, various neurotransmitters, digestive juices and enzymes; all swimming merrily around doing things which we have only started to understand, not just in the gut but also connected to lots of other systems in the body.

Our gastrointestinal bacteria constitutes a large portion of this 'biochemical soup' and has started to receive quite a lot more research inquiry recently as a result. What is perhaps only now starting to be realised is that our gut also house a lot more than just bacteria, it is also home to quite a few viruses also.

Think viruses and people automatically assume infection and bad things like bird flu. Even today, alerts are cropping up suggesting that bird flu might be making a comeback and this time with even more lethal strains. Viruses do not have a great reputation despite the fact that perhaps not all are the devil incarnate as exemplified by this recent advance in a potential anti-cancer virus.

A recent paper by Minot and colleagues* published in Genome Research suggests that our gut might house quite a few viruses and that what we eat has the potential to affect both the bacterial and viral signature in our gut.

The paper which has been summarised here suggests the gut virome, similar to the gut bacterial microbiome is both unique to a person and dynamic; in this case, changing the fibre and fat content of a persons diet resulted in changes to the gut virome.

I await more investigation on this topic. Investigation into how our gut virome interacts with our health and disease and how potentially other environmental factors might affect our viral world within a world.

* Minot S. The human gut virome: inter-individual variation and dynamic response to diet. Genome Research. August 2011.

Wednesday, 31 August 2011

Food and irritable bowel syndrome

Irritable bowel syndrome (IBS) has always seemed like a bit of an odd term to me. Odd because whilst it is used to describe various symptoms related to the bowel, 'irritable' to me implies angry and annoyed. Assuming that a similar meaning is denoted for IBS, various notions perhaps acquire new meaning. If for example, we assume that the gut is the second brain, and our first brain (the one in our head!) is the part of us that becomes irritable, angry or annoyed in response to whatever, then one can see some sense in its use when applied to the gut.

I digress. There is quite a lot of speculation as to what causes IBS and what are the most effective ways of reducing or managing symptoms. Outside of psychological factors such as stress, diet and food have been consistently related to some cases of IBS and the suggestion that sensitivity or intolerance might be tied into symptoms. I wrote a post about this not so long ago following the publication of quite an important piece of research where non-celiac gluten intolerance seemed to be linked to some cases of IBS. Removing gluten, or rather reintroducing gluten after having previously been excluded from the diet, seemed to be linked to the appearance of various IBS symptoms over placebo.

A recent article adds to the dietary connection. The paper by Carroccio and colleagues* suggested that a quarter of their participant group were found to have a food hypersensitivity to cow's milk protein and/or gluten wheat protein. Furthermore levels of tryptase, an enzyme normally released as part of an allergic-immune response, and fecal eosinophil cationic protein (ECP), related to inflammation, were higher in those participants with IBS and food hypersensitivity. This indicating some possibility of identifying those cases of IBS with a potential dietary effect involved.

Whilst complicated, dare I say spectral, conditions such as IBS are never going to be caused by one factor and one factor alone, there is some reliable evidence emerging implicating a dietary effect as being involved. Much like lifestyle and stress-reduction treatments and pharmacotherapy, such a dietary effect if linked, provides another possible intervention route to potentially alleviating symptoms, at least for a proportion of those affected.

* Carroccio A. et al. Fecal assays detect hypersensitivity to cows milk protein and gluten in adults with irritable bowel syndrome. Clinical Gastroenterology & Hepatology. August 2011.

Wednesday, 24 August 2011

Metabolic syndrome and gluten

I am pretty used to hearing about and using the word 'metabolic' in my day-to-day work. In this context, metabolic refers to a few things: a metabolic pathway, describing some chemical reactions leading to an end compound or other endpoint process; or an in-born error of metabolism, describing some genetic 'malfunction' predominantly with enzymes or enzymatic reactions.

A new term has started to creep into my dictionary over the past few months or so, metabolic syndrome. Whilst sounding like it should have something to do with the other uses I described, metabolic syndrome actually describes a set of risk factors which might predispose a person to subsequent problems of coronary artery disease, stroke and type-2 diabetes. The main risks taken from the various descriptions tend to include:

Why might metabolic syndrome be important to this blog? Well, because of this paper by Garcia-Manzanares and colleagues* published in the World Journal of Gastrointestinal Pathophysiology which reported on a case study of a woman presenting with the features of metabolic syndrome alongside coeliac (celiac) disease, and what happened when a gluten-free (GF) diet was installed.

I am sure that readers can guess what I am going to say. The woman, who was overweight, presented with high cholesterol and triglycerides, alongside iron deficiency was eventually found to present with comorbid metabolic syndrome and coeliac disease. Installation of a GF diet seemed to solve the iron problems (as one would expect it would in coeliac disease) but also seemed to positively affect dyslipidemia and measured glucose levels. In short, some of her metabolic disease risk factors seemed to be reduced.

It would of course be easy to say that all the effects were from the GF diet (and indeed I might try and further that view) but stepping back there are quite a few potential confounders which might also have played a hand in the results. So things like the fact that entering onto a GF diet probably quite fundamentally changed her diet anyway; out goes the wheat and other gluten-containing grains yes, but in comes perhaps more protein, more vegetables and fruits, more dairy products? What about any additional supplementation for all those vitamins and minerals that might be lost from the diet? I dare say that she was also told to do a little more exercise to help reduce her weight burden also. Lots of confounders which could potentially affect her metabolic disease risk factors.

Having said all that, there has for quite a while, been some discussions about how a GF diet might potentially be linked to lots of different things outside of just managing coeliac disease and other gluten sensitivities. I am not going to go down the autism or schizophrenia route too much, but there are some suggestions of potential effects in these areas and for related conditions particularly the health effects of components of our modern diet such as carbohydrates and what happens when you reduce the carbs. Another quite interesting thought (as least to me!) is whether or not the link between gluten removal and subsequent altered gut permeability in coeliac disease might also tie into some of the effects noted. So does a better gut barrier function promote better lipid and glucose measures?

I am going to stop there as I fast approach the limits of my competence in an area which is screaming out for further investigation. I state my disclaimer that I am not providing any medical or dietary advice from the research discussed in this post - that's the job of your healthcare professional, and I strongly suggest you consult them before making any changes to diet or anything else.

* Garcia-Manzanares A. et al. Resolution of metabolic syndrome after following a gluten-free diet in an adult woman diagnosed with celiac disease. World Journal of Gastrointestinal Pathophysiology. June 2011.

Thursday, 18 August 2011

Milk, gut bacteria and coeliac disease

Coeliac disease (CD), that exquisite sensitivity to dietary gluten, has long been the focus of quite a bit of research. That's not to say that in all those years we don't know a little bit about CD; some of its genetics, its diagnostic markers, its treatment, but there are still lots of things we don't know about CD as well as the various non-coeliac forms of gluten sensitivity which seem to be emerging.

When it comes to early markers or risk factors for CD, there are quite a few already in the research literature. I covered some of them on one of the sister blogs (here and here). Indeed the last link including this paper on your choice of entry into the world and subsequent gut bacteria, provides a good example of what might affect your start-up gut bacteria and potentially your subsequent risk of things like CD on the back of my previous post.

Enter a new potential player into the world of CD risk; surprisingly enough from your earliest form of nourishment post-partum, milk. The research by Sanchez and colleagues* postulated a connection between the genetic risk of CD and the type of bacteria from the Bacteroides species identified in fecal samples from infants with a parent with CD. An overview of the results can be found here.

The results from this study point towards two important points:

  • Genetic risk of CD as measured by the HLA-DQ genotype might influence the composition of the gut bacteria.
  • The type of early feeding practices (breast vs. bottle) might also influence gut bacterial composition at different times of infancy.

Whilst there are some interesting links made in this and other studies in this area, as always we need to be cautious in jumping to conclusions. Several authors have speculated that the type of early feeding pattern might alter the risk of developing CD. The evidence is however far from conclusive; indeed whilst there may be some effect in delaying the onset of CD, delay does not mean the condition will not develop. Indeed we will have to wait for studies like this one to formally reports before we can draw any firmer conclusions.

Still what studies like this offer is an insight into the complicated world of genetics and environment in conditions like CD and how our gut bacteria might well be king-maker (or at least a prince/princess) when it comes to conferring risk and protection against lots of conditions.

* Sanchez E. et al. Influence of environment and genetic factors linked to celiac disease risk on infant gut colonization by Bacteroides species. Applied & Environmental Microbiology. August 2011.

Tuesday, 16 August 2011

Can a gluten-free diet affect gut bacteria?

For those who have stumbled across this blog on the wide open plains of the Internet, I have a bit of interest in all things gluten-free. It is a professional interest and has been for quite a few years, as various colleagues and I have been looking at whether a gluten-free (GF) diet might show some effect on behaviour, and in particular behaviours commonly associated with autism spectrum conditions. We don't have a definitive answer by the way, but do suspect more than a passing association between diet and some cases of autism.

For those of you who perhaps already know of my interest and are thinking 'change the record mate', this post (this blog) is not going to rehash material from its sister blog, Questioning Answers, at least not on this occasion, but rather take a slightly different perspective. This post is tied into this study by Nistal and colleagues* on what happens to gut bacteria populations in coeliac disease when a GF diet is/is not in place. One of their findings was that gut bacterial populations differed (in adults) according to whether or not a GF diet was being applied.

This is not the first time that coeliac disease has been looked at in terms of the GF diet and gut bacterial populations. Indeed the effects of the GF diet seem also to be present outside of coeliac disease, depending on where you look for your bacterial colonies in the gut.

To me this is an interesting finding. Interesting because it suggests that our diet, much like various medications, can affect the trillions or so of gut bacteria that colonise us. Indeed comparative studies looking at diets in different parts of the world outside of coeliac disease have shown pretty much the same thing: what you eat affects your gut bacterial populations. The knock-on effects of this... to be discussed in subsequent posts.

* Nistal E et al. Differences of small intestinal bacterial populations in adults and children with/without celiac disease: effect of age, gluten diet and disease. Inflammatory Bowel Diseases. August 2011.


As per the headlines, this is a blog about your gut, your gastrointestinal (GI) tract, your intestines. This blog is a place to discuss various strands of research about the gut related to all sorts of different aspects and conditions ranging from how the gut works to gut bacteria to gut barrier function to conditions associated with the gut.

Where and what is your gut (as if I have to ask)? Well just in case you don't know, here is a link to a bit of a description.

Please keep all comments on blog posts cordial and polite and no swearing or vulgarity please. I hereby declare that no medical advice will be given or intended from this blog. If you think you have a problem with your gut (or any other body part), go to your doctor, don't rely on blogs!