Saturday 27 July 2013

Coeliac Disease - a training post

You're probably wondering why, with all the reams of autism research being produced every day, that I'm dedicating a post to describing coeliac (celiac) disease on this blog? Well, the answer is simple; I've talked about coeliac disease (CD) quite a bit in relation to autism (here) and schizophrenia (here) and other conditions (here) but I'm mindful that not everyone actually knows what it is or what we think we currently know about it.
Gluten @ Wikipedia  

So in future occasions when I talk about CD in relation to some wonderful new study, I've got this training post as mine and yours go-to reference for the condition.

If you want the long and complicated story of CD, there are plenty of peer-reviewed papers which I could suggest you read such as this one from Kagnoff* (open-access) or this one from Meresse and colleagues** (open-access). There are lots of other papers on the topic too but if you want the Mr Men version, read on.

Gluten protein and peptides
CD is a condition governed by genes and environment in pretty equal measure. I suppose it all starts with foods containing the protein gluten. Actually gluten is a bit of a catch-all word because it combines two types of protein: gliadin and glutenin. Gluten is a protein which consists of long chains of amino acids. When ingested, various enzymes go to work on chopping up the protein into those nutritious rich amino acids that our bodies so rely on. But digestion does not just see the gluten protein immediately exploded into its constituent amino acids but rather breaking the protein down chunk by chuck to form small chains of amino acids called peptides along with way.

If you're a follower of autism research and in particular the whole gluten- and casein-free dietary intervention thing, you'll probably have heard about peptides as per the opioid-excess theory*** (open-access) put forward as one explanation for why diet might 'work' for some on the autism spectrum. It's still a little bit contentious but that's perhaps a topic for another day.

Anyhow, gluten is not an easy protein to digest as per the presence of certain amino acids such as glutamine and proline in that protein chain, the chemistry of which don't like being degraded easily. So what you potentially get are quite a few peptides swimming around our gastrointestinal (GI) tract which are not completely degraded into their simplest building block form, the amino acids.

Gut access
These gluten, sorry gliadin, peptides however don't just stay in the gut; some of them are also able to gain access to a part of the gut barrier called the lamina propria. Once there, something rather interesting seems to happen in cases of CD. The peptides come across something called tissue transglutaminase (tTG) something else which has cropped up on this blog with autism in mind (see here). The clue is in the name about tTG (also called TG2) and what it can do: -ase means it's an enzyme and the glutaminase bit means that it does things to the amino acid glutamine. The specific duty it does is a process called deamidation which basically involves the conversion of glutamine to glutamic acid (otherwise known as glutamate). Without getting too much into the chemistry of this process, the newly deamidated gliadin peptide is now 'super-charged' (neutral into negatively charged amino acids) in terms of its attraction (binding affinity) to molecules of the almighty MHC - major histocompatability complex or HLA in humans (see here).

DQ2 and DQ8
OK, so a quick recap. Gluten protein digested into gluten peptides. Said peptides meet and greet tTG and funny things start to happen to them.

Next in the process chain of CD is how these newly enhanced peptides from an immunogenicity point of view are met by the cells of the MHC and the sparks that fly as a result. Just in case you didn't click on my link talking about the MHC, it's all about how things are presented to the immune system and in particular, the tricky task of making sure that 'self' is not confused with 'other' by the immune system.

The genetics of CD represent the important part of this next stage of proceedings as per the HLA-DQ2 and DQ8 heterodimers; in effect the genes of CD. It's all about inheritance patterns as to whether or not a person will have two or one or no copies of these genes as a consequence of genetic zygosity.

HLA DQ2 or DQ8 molecules are part of the antigen presenting cells (APCs). Those newly enhanced gluten peptides fit nicely into the 'pocket' of the DQ2 and/or DQ8 molecules and once there activate T cells or more specifically a Th1 CD4+ response**** (open-access) focused on gliadin. This eventually leads to the release of cytokines such as IFN-γ (see here also) and TNF which then go on to damage the gut mucosa as a function of their important role in the process of inflammation.

This is quite a simplistic overview of the main processes involved in CD. As per the discussions on the Kagnoff and Meresse papers, there are still quite a few unknowns about the whole process of CD. There's also the relatively newer work coming into the science of CD such as a role for zonulin (see this post) and its 'gatekeeper' role in relation to the gut barrier and things like the wheat amylase trypsin inhibitors (thanks Jad).

The gluten-free diet
As you'll probably already know, management of CD is primarily via the use of a gluten-free diet. The theory being that if there is still no starting material (gluten) to form those peptides, even though the genetics may be there, there is nothing or only little material for tTG or the DQ2/DQ8 molecules to go to work on.

That being said, you'll probably also see a few other potential areas where other interventions might also be developed***** (open-access). So how about helping to degrade those gluten peptides? What about stopping those peptides from meeting tTG? Blocking DQ8 and DQ2 molecules? Or even reducing the release or blocking the effects of those cytokines? And the good things is that research is underway in some of these areas.

Testing for coeliac disease
Just before you go it might also be worthwhile mentioning about how one goes about testing for CD in light of some confusion in this area over the years. It's worth pointing out that an accurate diagnosis of CD relies on more than one test (see here) covering serology, gut biopsy and on occasion, genetic testing. One of the more recent professional consensus statements on testing can be seen here****** (open-access).

And finally.... please don't take my word for it, do some research yourself.


* Kagnoff MF. Celiac disease: pathogenesis of a model immunogenetic disease. J Clin Invest. 2007 Jan;117(1):41-9.

** Meresse B. et al. Celiac disease: from oral tolerance to intestinal inflammation, autoimmunity and lymphomagenesis. Mucosal Immunol. 2009 Jan;2(1):8-23. doi: 10.1038/mi.2008.75.

*** Whiteley P. et al. How Could a Gluten- and Casein-Free Diet Ameliorate Symptoms Associated with Autism Spectrum Conditions? Autism Insights 2010:2 39-53.

**** Nilsen EM. et al. Gluten induces an intestinal cytokine response strongly dominated by interferon gamma in patients with celiac disease. Gastroenterology 1999; 115: 551-563.

***** Bakshi A. et al. Emerging Therapeutic Options for Celiac Disease: Potential Alternatives to a Gluten-Free Diet. Gastroenterol Hepatol (N Y). 2012 Sep;8(9):582-588.

****** Husby S. et al. European Society for Pediatric Gastroenterology, Hepatology, and Nutrition Guidelines for the Diagnosis of Coeliac Disease. JPGN. 2012; 54: 136-160.

---------- Meresse B, Ripoche J, Heyman M, & Cerf-Bensussan N (2009). Celiac disease: from oral tolerance to intestinal inflammation, autoimmunity and lymphomagenesis. Mucosal immunology, 2 (1), 8-23 PMID: 19079330

Monday 22 July 2013

Epilepsy in autism revisited

I've said it before and I'll say it again, a diagnosis of autism or autism spectrum disorder is seemingly protective of nothing when it comes to comorbidity. Indeed, in these days of common ground and overlap (think ESSENCE) one of the more positive changes in thinking about autism is the move away from viewing the condition as some sort of homogenous, stand-alone diagnosis ripe for over-arching generalised theories. It's not.

Stealing a kiss @ Wikipedia  
Of that growing list of comorbidity which can and does sometimes follow autism, one condition or set of conditions in particular, has the ability to severely impact on the health and wellbeing of a person, in some unfortunate cases leading to the most severe outcomes: epilepsy.

I've covered the topic of epilepsy and seizure disorders previously on this blog (see here). The main conclusion from that post was that epilepsy represents one of the more common comorbidities which can present alongside autism and that there is no positive side to being diagnosed with epilepsy in terms of how it can affect quality of life and how it is, in some cases, linked to early mortality.

With these facts in mind, I was therefore interested to read the paper by Emma Viscidi and colleagues* (open-access) which looked at a number of issues around the autism-epilepsy link in terms of the prevalence of epilepsy and some of the factors which might influence the start and presentation of epilepsy in cases of autism.

The paper is open-access so there's no real need for me to get the fine-toothed comb out on it. I will however summarise some key points:

  • Based on participant data from four separate initiatives - AGRE, Simons Simplex collection, Autism Consortium, NSCH 2007 - authors collated data on nearly 6000 mainly young people diagnosed with an autism spectrum condition.
  • There were some differences among the various datasets in terms of how the diagnostic coding of autism was arrived at which needs to be kept in mind with this paper, but on the whole most diagnoses were confirmed by gold-standard assessment tools.
  • In terms of the presence of epilepsy, these were "based on parent report in all of the samples" without independent, professional verification of the diagnosis.
  • Several other facets of presentation were [variably] collected / ascertained from the available datasets including things like cognitive ability, history of developmental regression (see here) and the severity of autism presentation (at least at the time of initial presentation to the various initiatives).
  • Results: well, bearing in mind some variability between the datasets and various demographic slants such as participants being predominantly male and white, the frequency of reported epilepsy occurring in cases of autism ranged from 2.9% - 6.7% and the prevalence (based on the NSCH 2007 data) was 12.5%.
  • When stratifying the data across age groups (6 and below, 7-9, 10-12, 13 and above years) it appeared that older chronological age was associated with an increased frequency of reports of epilepsy; from the NSCH data, upwards of 25% of 13 year olds and older with autism were reported to present with epilepsy.
  • Similarly other recorded factors also seemed to be linked to the appearance of epilepsy including: the presence of developmental regression, those with poorer language skills, lower cognitive ability, etc.
  • The authors conclude that "epilepsy is a common co-morbid condition in individuals with ASD" and that "low IQ is the best clinical predictor of epilepsy in children with ASD".

As I've mentioned, there are some pretty big holes in this research; not least the lack of independent verification when it comes to the presence of epilepsy or not. Actually, I'm going to rephrase that last sentence to say that this is not a 'hole' in the research but rather something that needs to be investigated further in light of my previous posts talking about parents actually being quite good at spotting clinical signs (see here) and other comorbidity (see here) when it comes to autism. A shocker I know.

That aside, there are several potentially important lessons which can be learned from this data, not least when it comes to 'predicting' who with autism, might eventually go on to develop epilepsy and hence where screening and clinical management for this particular comorbidity perhaps needs to be focused in these times of limited resources and austerity. The accompanying paper by Jedrzejczyk-Goral and colleagues** looking at what types of epilepsy might be more commonly associated with autism is also helpful.

The related issue of intellectual disability (ID) in cases of autism seemingly being a magnet for epilepsy is also worthy of greater follow-up. One wonders for example, whether this finding might overlap with the other data looking at things like genetics in relation to autism and how ID seems to shoulder the larger burden when it comes to CNV load for example (see here). Indeed, whether some of these CNVs or other point mutations (SNPs et al) might actually be more relevant to the onset of epilepsy than the presence of autism itself? And then what about that inborn error of the branched-chain amino acids work discussed not so long ago on this blog (see here) where epilepsy and autism was presented?

Finally(!) my thoughts also wander back to the recent chatter about ketogenic diets and autism (see here and here). I'm not for one minute giving anything like medical advice on this issue - don't mess with epilepsy or indeed, antiepileptics it seems (more to follow on this). I'm merely suggesting that when potentially knowing which children/young adults with autism are more likely to develop epilepsy, and given the increasing interest in managing certain types of epilepsy through the ketogenic approach, whether further controlled research might wish to have a closer look at whether there are important links (or not) between these areas.

To close, Radio 2 listeners here in the UK might recognise a version of this song... enjoy yourself (it's later than you think).


* Viscidi EW. et al. Clinical Characteristics of Children with Autism Spectrum Disorder and Co-Occurring Epilepsy. PLoS ONE 2013;  8(7): e67797. doi:10.1371/journal.pone.0067797

** Jedrzejczyk-Goral B. et al. 1925 – The frequency of different types of seizures in children suffered from autism and epilepsy. European Psychiatry. 2013; 28: supplement (Abstracts of the 21th European Congress of Psychiatry).

---------- Viscidi EW (2013). Clinical Characteristics of Children with Autism Spectrum Disorder and Co-Occurring Epilepsy PLoS ONE DOI: 10.1371/journal.pone.0067797

Friday 19 July 2013

Autism, gut problems and oxidative stress

I'm still a rank amateur when it comes to talking about many aspects of autism research. Mitochondrial dysfunction remains a particularly curious area of research to me as I might have mention previously, but other areas are equally as baffling.
Storm in a teacup @ Wikipedia 

Take for example oxidative stress and the various research done on this topic in connection to autism. Yes, I've touched upon some aspects of this wide, very wide, area of investigation in previous posts (see here and here) but still it's hard going for me and I don't mind admitting it.

I therefore approach the paper by Phillip Gorrindo and colleagues* (open-access) with some degree of trepidation, and their suggestion that the presence of gastrointestinal (GI) issues appearing alongside cases of autism might very well be implicated in the whole oxidative stress area.

Some of you might remember the name Phillip Gorrindo and the excellent study** he was involved with suggesting that when mums and dads of children with autism talk about GI or bowel problems presenting in their children, professionals may do well to listen to them rather than fobbing them off as merely being 'non-experts'. By saying this I'm implying that parents are partners when it comes to identifying such issues as they are in other areas.

In this latest paper - which again has some media attention attached to it - we are told of three reasons why the authors chose to look at autism, GI issues and oxidative stress based on (i) the gut and brain possessing a "likely shared susceptibility to insults", (ii) that old mitochondrial ticket (see here again), and (iii) the links already made between autism and oxidative stress. The inclusion of the GI bit stems, I assume, from the previous focus of the author's work and quite a large volume of other research looking at GI issues and oxidative stress (see here for example) outside of autism.

  • Four groups of participants were included for study: ASD+GI issues (n=27), ASD alone (n=29), GI issues with no ASD (n=21) and an "unaffected" group (n=10). GI issues by the way, were defined as functional GI issues (constipation, reflux, IBS, abdominal pain).
  • Blood samples were provided by participants and plasma levels of F2-Isoprostanes were analysed blind via GC-MS (although not seemingly based on accurate mass). 
  • In addition, levels of plasma triglycerides were also measured explained due to the effects of blood lipids on F2-IsoPs.
  • Results: well, in all clinical groups, including the GI issues only group, mean levels of F2-IsoPs were above that seen in the unaffected control group.
  • Group levels of F2-IsoPs were significantly greater in the ASD+GI group compared with the ASD alone group (p=0.007), although the ASD+GI group and GI issues with no ASD group were not significantly different from one and another.
  • Plasma triglyceride measurements also suggested that compared to the unaffected control group, the other groups all presented with elevations.
  • As well as looking at just the biochemistry side of things, the authors also noted that when it came to looking at "social impairment", the ASD+GI group seemed to fare considerably worse than the other groups.
  • The authors conclude that: "individuals with co-occurring ASD and GID [gastrointestinal dysfunction] may exhibit clinical phenotypes that are sufficiently distinct from children with ASD".

There's little more for me to add to this entry that has not already been said. Yes, the participant numbers were on the small side and so one has to be careful not to make too many sweeping generalisations. That being said though this is not the first time that such biochemical findings have been noted in cases of autism**. Quite by coincidence, I also stumbled across this recent paper by Ghezzo and colleagues*** (open-access) and this paper by Signorini and colleagues**** (open-access) both of which mention the isoprostanes (the Signorini paper with Rett syndrome in mind too). Isoprostanes with autism or autistic behaviours in mind seem to be rising in importance and with it their link to oxidative stress (see here).

I personally would have liked to have seen other markers linked to oxidative stress and its defences also measured and reported in this study. That very big elephant in the room that is glutathione is perhaps an important marker for future work in this area. I happened also to stumble across this article by Sido and colleagues***** (open-access) which talked about glutathione and inflammatory bowel disease (IBD) which might very possibly be relevant to those cases of autism where functional GI issues are part and parcel of something altogether more complicated (see here). Indeed the focus in the Sido article on cysteine brings us back to another important, if slightly under-rated, autism research avenue: sulphate (or sulfate if you wish).

To close, some music from Sonic Youth: 100% and some background on Joe.


* Gorrindo P. et al. Enrichment of Elevated Plasma F2t-Isoprostane Levels in Individuals with Autism Who Are Stratified by Presence of Gastrointestinal Dysfunction. PLoS ONE 8(7):2013;  e68444. doi:10.1371/journal.pone.0068444

** Ming X. et al. Increased excretion of a lipid peroxidation biomarker in autism. Prostaglandins Leukot Essent Fatty Acids. 2005 Nov;73(5):379-84.

*** Ghezzo A. et al. Oxidative Stress and Erythrocyte Membrane Alterations in Children with Autism: Correlation with Clinical Features. PLoS One. 2013 Jun 19;8(6):e66418.

**** Signorini C. et al. Isoprostanes and 4-Hydroxy-2-nonenal: Markers or Mediators of Disease? Focus on Rett Syndrome as a Model of Autism Spectrum Disorder. Oxid Med Cell Longev. 2013;2013:343824.

**** Sido B. et al. Impairment of intestinal glutathione synthesis in patients with inflammatory bowel disease. Gut. 1998 Apr;42(4):485-92.

---------- Gorrindo P (2013). Enrichment of Elevated Plasma F2t-Isoprostane Levels in Individuals with Autism Who Are Stratified by Presence of Gastrointestinal Dysfunction PLoS ONE DOI: 10.1371/journal.pone.0068444

Tuesday 16 July 2013

The gut microbiota and ME/CFS

Continuing a common theme of gut bacteria on this blog, most recently with autism in mind, my attention today turns to a paper by Frémont and colleagues* looking at the gut microbiota in cases of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS).

Cross my palm @ Wikipedia 
This is not the first time that those trillions of bacterial masters of ours have cropped up on this blog with CFS/ME in mind as per my recent post on yuck factor 10 and the fecal microbiota transplant (FMT) with CFS/ME in mind (see here).

Frémont et al utilised the most commonly used tool of the bacteriologists trade, high-throughput 16S rRNA gene sequencing (see here for an overview** and here for some issues with the method), to classify bacteria derived from a lovely sample medium - stool samples - provided by 43 participants diagnosed with ME/CFS compared with 36 asymptomatic controls.

They reported a few interesting things.
  • Because samples were provided by both Belgian and Norwegian participants (both ME/CFS and control groups), the authors reported differences in the type of bacteria between the different country samples. I'm guessing that quite a lot of this variation has to do with environmental factors such as food preferences and the like as per what other studies have shown. We also know for example that what you eat can have a fairly important effect on what bacteria you have in your gut (see here).
  • "Norwegians showed higher percentages of specific Firmicutes populations" when looked at as a whole in comparison to the Belgian samples.
  • When comparing Norwegian CFS/ME participants with their fellow asymptomatic country-people "patients presented increased proportions of Lactonifactor and Alistipes, as well as a decrease in several Firmicutes populations". Readers who clicked on the link for more information about Alistipes might recognise the name carried by a particular species, A. finegoldii named in honour of one Sydney Finegold, a regular on the autism-gut bacteria research scene
  • "In Belgian subjects the patient/control separation was less pronounced, however some abnormalities observed in Norwegian patients were also found in Belgian patients". Not too much more to add there aside from the suggestion that searching for diagnosis-wide biomarkers for a heterogeneous condition like CFS/ME perhaps suffers from the same methodological ills as has been talked about with the autisms in mind (see here). That and the whole brain CFS/ME vs gut CFS/ME subgroup discussions that I've had on this blog. 

Appreciating that this was a relatively small scale study in terms of participant numbers, I'm intrigued by this study and its results. Heterogeneity in presentation and all the myriad of other factors which can and do affect gut bacteria are important interfering factors in any kind of research in this area. Indeed if one compares the gut microbiome with some of the other -omes such as the genome or epigenome, one starts to appreciate the similar issues involved in building up a picture of the underlying pathology behind a condition like CFS/ME in terms of no one gene or epigenetic factor probably working in isolation covering all cases. So it is probably true for the gut microbiome too.

That being said, unlike genes and to a lesser extent the epigenome, where differences are identified in the various phylum/class/order/family/genus/species of bacteria present potentially even in just subgroups of the condition, one would assume that some corrective intervention could be put in place which might, just might, affect the presentation of symptoms. Indeed the authors speculate on "treatments based on gut microbiota modulation (antibiotics, pre and probiotics supplementation)" which brings me to the paper by Groeger and colleagues**** and back to the original paper by Borody and colleagues***** and indeed outside of CFS/ME, that interesting case study on antibiotics and autism which I discussed recently (see here) [no medical advice is given or intended].

To close, Muscial Youth and a blast from the 80s past.


* Frémont M. et al. High-throughput 16S rRNA gene sequencing reveals alterations of intestinal microbiota in myalgic encephalomyelitis/chronic fatigue syndrome patients. Anaerobe. 2013 Jun 19. pii: S1075-9964(13)00092-9. doi: 10.1016/j.anaerobe.2013.06.002.

** Trichopoulou A. et al. Disparities in food habits across Europe. Proceedings of the Nutrition Society. 2002; 61, 553–558.

*** Větrovský T. & Baldrian P. The Variability of the 16S rRNA Gene in Bacterial Genomes and Its Consequences for Bacterial Community Analyses. PLoS ONE. 2013; 8(2): e57923. doi:10.1371/journal.pone.0057923

**** Groeger D. et al. Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut. Gut Microbes. 2013 Jun 21;4(4).

***** Borody TJ. et al. The GI microbiome and its role in Chronic Fatigue Syndrome: A summary of bacteriotherapy. Journal of the Australasian College of Nutritional and Environmental Medicine. 2012; 31: 3-8.

---------- Frémont M, Coomans D, Massart S, & De Meirleir K (2013). High-throughput 16S rRNA gene sequencing reveals alterations of intestinal microbiota in myalgic encephalomyelitis/chronic fatigue syndrome patients. Anaerobe PMID: 23791918

Saturday 13 July 2013

Fructose and lactose intolerance are common and frequently overlap in FGID

The title of this post is a quote taken from the paper by Clive Wilder-Smith and colleagues* (open-access) who reported that issues with the metabolism of the short chain carbohydrates (sugars) fructose found in fruits and lactose found in milk and dairy products may very well be common in functional gastrointestinal disorder (FGID).
Soup again! @ Wikipedia 

I was interested in this paper on two levels.

First is a passing interest in all things FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) and some potential relationship to cases of FGIDs specifically with irritable bowel syndrome (IBS) in mind**. Indeed, I've passed mention about this on a previous post on a sister blog (see here).

Second is, as those who read this blog regularly (thank you!) might know, my interest in all things comorbidity with the autisms in mind. Specifically that growing body of evidence (peer-reviewed of course) suggesting that gastrointestinal (GI) issues might be present in a fair few cases of autism (see here). That and the links suggested between such GI issues and reports of various dietary links (see here).

Certainly on that last point, I'm entertaining the possibility that where clinician-defined FGID (constipation, diarrhoea, even IBS) is found in cases of autism  one might be so inclined to enquire whether there may be issues with fructose and lactose also comorbid.

Just in case you're thinking that I'm getting a little ahead of myself with such speculation, I should point out that: (a) autism is seemingly protective of nothing when it comes to comorbidity and (b) certainly on the issue of lactose, and in particular lactose intolerance, there is more than one study suggesting issues to be present in cases (see here) and perhaps even issues more generally with carbohydrate metabolism as per the 'game-changer' work of Brent Williams and colleagues (see here) and subsequent others (see here). At the very least there is a study there waiting to happen. Fructose by the way, has also been mentioned with autism in mind albeit rather speculatively (see here).

Just before I go there were a few other pertinent points to take from the Wilder-Smith study. "Dietary modification based on fructose and lactose intolerance testing was clearly beneficial". In other words, when it came to the presentation of FGIDs, for those who were shown to be "sugar" intolerant, there was quite a bit of relief reported. Interesting too that the authors talk about an "elevated prevalence of non-GI functional syndromes" to accompany FGID - with fatigue being the most commonly reported in their cohort. One could interpret this in several ways including taking some inspiration from the name of the author's research group  - the Brain-Gut Research Group - and perhaps even some overlap into other conditions too (see here).

I could also go on about gut bacteria and gut hyperpermeability also mentioned in the paper, but to save me getting too obsessed with these areas, I'll stop right there apart from reiterating that no medical or clinical advice was offered or intended in this blog post.

Music to close: I've linked to this record before but it is a classic so worth again a link... Buddy Holly by Weezer (including The Fonz dancing - what a mover!).


* Wilder-Smith CH. et al. Fructose and lactose intolerance and malabsorption testing: the relationship with symptoms in functional gastrointestinal disorders. Aliment Pharmacol Ther. 2013 Jun;37(11):1074-83. doi: 10.1111/apt.12306.

** Shepherd SJ. et al. Short-Chain Carbohydrates and Functional Gastrointestinal Disorders. Am J Gastroenterology. 2013; 108: 707-717.

---------- Wilder-Smith CH, Materna A, Wermelinger C, & Schuler J (2013). Fructose and lactose intolerance and malabsorption testing: the relationship with symptoms in functional gastrointestinal disorders. Alimentary pharmacology & therapeutics, 37 (11), 1074-83 PMID: 23574302

Wednesday 10 July 2013

Maternal autoantibody-related (MAR) autism?

Yes you heard me right: maternal autoantibody-related autism or 'MAR autism' for short.

The term comes from some of the latest investigations published by researchers at the MIND Institute continuing an important strand of their various studies looking at the autism spectrum disorders (ASDs).
Rhesus, me? @ JM Garg / Wikipedia 

The papers in question are this one from Melissa Bauman and colleagues* (open-access) and this one from Dan Braunschweig and colleagues** (open-access) suggesting that maternal autoantibodies reactive to offspring foetal tissue might very well be an important part of quite a few cases of autism (see here for some background). An article in The Scientist covers the recent papers well so if you don't want my take, just click here and many thanks for dropping by.

You're still here. OK, thanks.

Those who actively follow this region of the autism research landscape will no doubt have already heard of similar results in transplanting purified IgG brain reactive antibodies (IgG-ASD) from mums of children with autism into pregnant mice and watching what happens to the mice offspring (see here) in terms of things like behaviour. In the Bauman study, mice were replaced with rhesus monkeys (cute picture alert) as per another occasion*** and again the development and behaviour of offspring and mother monkeys (n=8) were observed and recorded. This time around however analysis was following the application of a specific IgG mix (37 and 73kDa foetal brain autoantibodies) compared to control monkeys who received an IgG control mix from mums with no children diagnosed with autism.

Some very interesting things were observed in both mother and infants' behaviour over the 2 year period of investigation covering the main developmental periods (weaning, post-weaning, juveniles). Mums treated with IgG-ASD antibodies showed a heightened protectiveness towards their similarly exposed offspring potentially indicative of them picking up cues about their offsprings' unusual behaviour. Offspring were also more frequently taken to approaching other monkeys that were unfamiliar to them, which the authors again translated as being evidence for either not understanding the social etiquette of who and who not to approach or failing to recognise danger. Just before you sigh and click away, yes it was another study of inferring animal behaviour and superimposing it on a complex condition like autism (see here).

Allowing also for the small number of monkey participants, offspring were also tracked using neuroimaging to see whether there were any changes to brain structure or neuropathology. The authors reported that males in the IgG-ASD antibodies group seemed to show "a higher rate of brain growth" when compared to study controls added to an external control set (n=7). This alongside various other observations of the brain (see here). The net conclusion: "These outcomes are supportive of our hypothesis that the antibodies are pathogenic for one form of autism". But do bear in mind that again this was all about interpreting animal behaviour and the absolute number of 'animal participants' was small.

The second paper by Braunschweig and colleagues extended the interest in MAR by actually looking to identify the specific - exclusive - antigen(s) which were the target of the IgG antibodies. Based on an analysis of blood samples from some 250 mothers of children with autism and just shy of 150 control group mothers (with no offspring autism), researchers were able to isolate several combinations of antigens which were more reactive to the blood of mums of autistic children compared with controls. On a personal level it was nice to see mention of words like proteomics and MALDI-ToF mass spectrometry in amongst the methods.

The identified antigens were: "lactate dehydrogenase A and B, cypin (guanine deaminase), stress-induced phosphoprotein 1, collapsing response mediator proteins 1 and 2, and Y-box binding protein". They found that 23% of samples from mums with a child with autism presented with reactivity to certain combinations of these antigens compared with only 1% of control mothers. Ergo statements like "MAR autism cases could represent as much as 23 percent of all autism cases" and the subsequent chatter on developing a biomarker screen for MAR autism (of which this is the first step). Oh, and that certain antigens seemed also to correlate with specific core featues associated with autism such as stereotypic behaviours is also noteworthy.

I can't readily comment too much on the antigens linked to MAR autism. Lactate dehydrogenase (LDH) which it seems was one of the more important antigens, is for example involved in energy metabolism (see here). The authors seem to focus on its links to responding to viral infections (influenza?) or toxic exposures. I'd be interested to hear more about this as time goes by.

These are intriguing findings, of that there is no doubt and judging by some of the feedback I'm reading about the studies, this could be another important step forward in autism research (think folic acid, valproate and the elephant in the room that is glutathione). It's heartening to see that a certain Prof. Paul Patterson and his team who have also championed a role for the maternal immune system in relation to at least some offspring autism (see here) are also really interested in these findings and the potential implications of them. Indeed on the basis of the latest Patterson lab findings which I assume are going through peer-review as we speak(?), one might also start asking some wider questions about the hows and whys of maternal immune activation in relation to autism.

And finally, just in case you'd forgotten, autoantibodies outside of the maternal variety have previously been talked about with autism in mind as per the insightful work from Dr Frye (see here) who gave a great presentation at the US IACC very recently (see here).

2013 it seems is shaping up to be quite a year for autism research.

To close, Peter and Kate with some inspiring words.


* Bauman MD. et al. Maternal antibodies from mothers of children with autism alter brain growth and social behavior development in the rhesus monkey. Translational Psychiatry. 2013. 3: e278; doi:10.1038/tp.2013.47

** Braunschweig D. et al. Autism-specific maternal autoantibodies recognize critical proteins in developing brain. Translational Psychiatry. 2013 3: e277; doi:10.1038/tp.2013.50

*** Martin LA. et al. Stereotypies and hyperactivity in rhesus monkeys exposed to IgG from mothers of children with autism. Brain Behav Immun. 2008 Aug;22(6):806-16. doi: 10.1016/j.bbi.2007.12.007.

---------- M D Bauman (2013). Maternal antibodies from mothers of children with autism alter brain growth and social behavior development in the rhesus monkey Translational Psychiatry DOI: 10.1038/tp.2013.47 D Braunschweig (2013). Autism-specific maternal autoantibodies recognize critical proteins in developing brain Translational Psychiatry DOI: 10.1038/tp.2013.47

Tuesday 9 July 2013

BH4 for autism?

I've talked about tetrahydrobiopterin (sapropterin or BH4) a few times on this blog with reference to autism (see here and here) and also some interesting suggestions about it being a potential intervention for the archetypal 'diet can affect behaviour' condition, PKU (see here).
The Nubian Giraffe @ Wikipedia 

A quick recap: BH4 is a hold-my-hand cofactor involved in some pretty important biochemical reactions; notably quite a few utilising those interesting aromatic amino acids (see here) and their neurotransmitter relations. Deficiency of BH4 has a few consequences as one might imagine; one of the important ones being a build up of the amino acid phenylalanine, which as seen in PKU and perhaps other conditions, is not necessarily a great position to be in.

Going back to the autism connection, the paper by Cheryl Klaiman and colleagues* caught my eye, as they reported on the results of a gold-standard double-blind, placebo-controlled trial of BH4 in young children (3-7 years old) diagnosed with an autism spectrum disorder (ASD). Actually, you can see a little bit more about their trial from their entry in the database (see here) with the requirement for the study authors to update their study details!! (as of July 2013).

Anyhow, in their fairly small participant group they looked at children taking BH4 - 20mg/Kg body weight per day - compared with those taking a placebo for 16 weeks and examined various autism and related behaviours. They reported no statistically significant difference on their primary outcome measure (the CGI-I and CGI-S) but..... there were a number of significant improvements noted on some of the secondary measures used including behaviours related to social awareness, hyperactivity and aspects of language. Importantly too, reported side-effects from BH4 were minimal and on a par with those reported by the placebo group. They conclude: "These results indicate that BH4 offers promise in reducing symptoms of ASD".

These are interesting results both insofar as what is reported and the speculations about what BH4 might be doing. Unfortunately, this study did not report on any specific biochemical measures so it's slightly difficult to add anything further even though just some simple measures of things like blood phenylalanine levels** or even nitric oxide (NO) metabolites*** would, I dare say, have been quite revealing.

I'm not going quibble however about this paper because it adds to the already interesting evidence base on BH4 for at least some cases of autism. That and the quite impressive record on few and far between side-effects of BH4 makes for another interesting potential therapeutic agent (and its targets) should anyone wish to take up the research gauntlet further.


* Klaiman C. et al. Tetrahydrobiopterin as a treatment for autism spectrum disorders: a double-blind, placebo-controlled trial. J Child Adolesc Psychopharmacol. 2013 Jun;23(5):320-8. doi: 10.1089/cap.2012.0127.

** Burton BK. et al. Sapropterin therapy increases stability of blood phenylalanine levels in patients with BH4-responsive phenylketonuria (PKU). Mol Genet Metab. 2010 Oct-Nov;101(2-3):110-4. doi: 10.1016/j.ymgme.2010.06.015.

*** Frye RE. et al. Metabolic effects of sapropterin treatment in autism spectrum disorder: a preliminary study. Transl Psychiatry. 2013 Mar 5;3:e237. doi: 10.1038/tp.2013.14.

---------- Klaiman C, Huffman L, Masaki L, & Elliott GR (2013). Tetrahydrobiopterin as a treatment for autism spectrum disorders: a double-blind, placebo-controlled trial. Journal of child and adolescent psychopharmacology, 23 (5), 320-8 PMID: 23782126

Sunday 7 July 2013

Gut bacterial diversity and autism

Let's face it, those who regularly read this blog probably knew that I was always going to be interested in the paper published by Dae-Wook Kang and colleagues* (open-access) discussing the gut microbiome and autism.
Holding it in @ Wikipedia  

For quite a while now I've been going on (and on and on) about how those trillions of wee beasties which call us home might be doing so much more than just helping to digest our food and producing the odd vitamin or two.

Indeed it's come to the point that questions have started to be asked about whether gut bacteria might not just shape or influence behaviour (see here) but indeed whether our very psychological development might be linked to what goes on in the deepest, darkest recesses of our bowels: psychobacteriomics anyone?

Appreciating that such work still needs to go some before we proclaim that social development for example, is linked to gut bacteria (it was a study of mice** after all) and put quite a few psychologist-theorists out of business, there is nevertheless a growing tide of research highlighting how important the symbiotic relationship between bacteria and human might be. Just call me Dax.

The Kang paper has, as one might expect, already received some media attention (see here). Indeed, the authorship list also includes a favourite autism researcher of mine - Prof. Jim Adams - who aside from publishing that pretty good gold-standard RCT of vitamin supplementation for autism a while back (see here), has himself already dabbled in the science of gut bacteria and autism as per other articles*** (open-access).

  • In the latest study, the name of the game was stool analysis; said stools provided by 20 children diagnosed with an autism spectrum disorder (ASD) and 20 age- and sex-matched aysmptomatic control kids. DNA was extracted from the stools (what a lovely job that must have been!) and analysed to discern what bacteria and families of bacteria were present across the two groups. If you really want more information about 16S rDNA sequencing method used in the Kang study, I've got another post scheduled soon on more gut microbiomics in chronic fatigue syndrome (CFS) which gives a little more information on the science.
  • The results: well, after some fancy analysis based on the various groupings of bacteria and the "microbial richness and diversity" present between the groups, one of the main conclusions was that the control asymptomatic group "harbored more diverse gut microbiota than the autistic group did". 
  • When they looked at the presence of gastrointestinal (GI) issues related to cases of autism there was some hint of an effect too on gut bacterial diversity but it appeared that the severity of autism was a more important factor to potentially account for the microbial differences detected.
  • The authors note findings of: "significantly lower abundances of the genera Prevotella, Coprococcus, and unclassified Veillonellaceae in autistic samples". Not being an expert on the various types of bacteria which colonise our gut, I can't necessarily suggest anything more than what the authors noted about the link between some of these bacterial families and things like the digestion of carbohydrate-rich foods. Interesting though that the name Brent Williams appears in the paper text and his 'carbs and dysbiosis' work in autism (see here). 
  • The authors conclude that the reduced microbial diversity and specific differences across the groups should be further investigated taking into account issues like dietary effects (see here) and the 'cross-talk' between bacteria and other biological functions.

OK you can perhaps appreciate that this was a relatively small study based on the participant numbers included. That and the fact that unlike the hunt for autism-related genes and genetic mutations (yep, lots of them potentially) when we talk about the gut microbiome, we are 'generally' (see here) talking about a dynamic system influenced by all manner of environmental effects not just the food we eat (see here). Kinda more like the methylome me thinks. That gut bacteria might also only be one part of the 'triad' of issues (pathogenic gut bacteria, gut hyperpermeability / leaky gut, immune response) which seem to be discussed with autism and the gut in mind is also worthwhile remembering.

But on the positive side of things, the Kang paper represents a lot of hard work and is yet another brick in the autism research wall suggesting that we should be looking more 'whole-body' when it comes to cases and phenotypes. Of particular note is the suggestion that behavioural symptom severity might trump GI symptom presentation as being 'correlated' to gut microbiome diversity. The authors do qualify this assertion by suggesting that "autism-related GI disorders may be linked to a unique shift in microbial balance", part of which they detected in their study. Whether or not this statement ties into those Stephen Walker 'distinctive features' bowel findings reported recently (see here) is perhaps further source for speculation and investigation.

To close Franz Ferdinand and Take Me Out.


* Kang D-W. et al. Reduced Incidence of Prevotella and Other Fermenters in Intestinal Microflora of Autistic Children. PLoS ONE 8(7): 2013; e68322. doi:10.1371/journal.pone.0068322

** Desbonnet L. et al. Microbiota is essential for social development in the mouse. Molecular Psychiatry. 2013. doi: 10.1038/mp.2013.65

*** Adams JB. et al. Gastrointestinal flora and gastrointestinal status in children with autism -- comparisons to typical children and correlation with autism severity. BMC Gastroenterology 2011, 11:22 doi:10.1186/1471-230X-11-22

---------- Kang D-W (2013). Reduced Incidence of Prevotella and Other Fermenters in Intestinal Microflora of Autistic Children PLoS ONE DOI: 10.1371/journal.pone.0068322

Thursday 4 July 2013

sPECAM pie and school-aged autism

I've talked about adhesion molecules with autism in mind before on this blog (see here). In that entry it was some interesting data out of the MIND Institute which caught my attention; specifically the selectins and their sticky siblings being 'generally' suggested to be lower in case of autism than control samples. Without repeating my previous post, it's all about the binding of leukocytes to the walls of blood vessels to begin their rolling journey towards the site of an injury and then inflammation, yadda, yadda...
Rolling stone & moss @ Wikipedia  

Anyhow, a new addition joins the voices suggesting issues with adhesion in cases of autism in the form of the paper by Yosuke Kameno and colleagues* (open-access paper available here).

The Kameno paper fills a bit of a gap in the literature in this area by looking at levels of platelet-endothelial adhesion molecule-1 (PECAM-1), platelet selectin (P-selectin), endothelial selectin (E-selectin), intracellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in serum samples from school-aged children (5-17 years old) diagnosed with autism compared with asymptomatic controls. The reasoning being that very young infants and young adults have been examined with these adhesion molecules in mind but not the intervening age group.

The results: well probably unsurprisingly, levels of at least some of the adhesion molecules were lower in cases of autism compared with the control group. So: "The serum levels of sPECAM-1 in subjects with high-functioning ASD were significantly lower than those of controls (U = 91.0, P<0.0001) (Table 1). Subjects with high-functioning ASD also had significantly decreased levels of sVCAM-1 compared with those in controls (U= 168.0, P = 0.0042)". The U by the way refers to the statistical test used (Mann-Whitney U test) to analyse results. That and the fact that attempts to correlate the biological findings with things like scores on the Autism Diagnostic Interview-Revised (ADI-R) didn't reveal any significant correlations.

There are also a few hidden gems in this paper not readily discussed too much. So for example: "To exclude inflammatory disease, serum C-reactive protein (CRP) levels were determined". CRP is another interesting compound which I've talked about before with regards to inflammation and autism or risk of autism (see here and here). Kameno didn't seem to find anything specific in their autism cohort aside from: "The CRP measurement of one subject with ASD was 2.30 mg/dl (this individual did not have subjective symptoms or a history of inflammatory disease)".

They also looked at a number of cytokines in their participant group and concluded: "We determined that plasma concentrations of IL-1β, IL-1RA, IL-5, IL-8, IL-12(p70), IL-13, IL-17 and GRO-α were 
significantly higher in subjects with ASD compared with the corresponding values of the matched controls, after correcting for multiple comparisons". I'm particularly interested in their observations on IL-17 given some previous work in this area (see here) and its [proposed] link to various autoimmune conditions.

So Kameno and colleagues have filled the age group gap in the work looking at adhesion molecules with autism in mind. Given the increasing strength of the evidence coming out of this area of autism research, one could make a good argument for quite a bit more detailed investigation?

To finish, there are potentially lots of rolling linked songs I could offer. But instead I'll go for burning....


* Kameno Y. et al. Serum levels of soluble platelet endothelial cell adhesion molecule-1 and vascular cell adhesion molecule-1 are decreased in subjects with autism spectrum disorder. Mol Autism. 2013 Jun 17;4(1):19.

---------- Kameno Y, Iwata K, Matsuzaki H, Miyachi T, Tsuchiya KJ, Matsumoto K, Iwata Y, Suzuki K, Nakamura K, Maekawa M, Tsujii M, Sugiyama T, & Mori N (2013). Serum levels of soluble platelet endothelial cell adhesion molecule-1 and vascular cell adhesion molecule-1 are decreased in subjects with autism spectrum disorder. Molecular autism, 4 (1) PMID: 23773279

Monday 1 July 2013

The big H and schizophrenia

Frankly I am more than a little interested in all-things homocysteine when it comes to behaviour and psychiatry. Perhaps more readily finding discussion and argument with regards to more physical health complaints as per the literature on homocysteine and cardiovascular disease risk*, the 'big H' ties into quite a lot of other interesting areas such as folic acid and the link with another important amino acid, methionine and all that methylation mumbo-jumbo.
Islands in the CpG stream @ Wikipedia 

With autism in mind, the various investigations looking at homocysteine have been pretty much all one direction: elevated levels detected in various biological fluids** (open-access). I hate to make generalisations about the autisms, but homocysteine does appear to be something in need of more detailed consideration as per another potential elephant in the room.

Today however my interest turns to a paper by Makoto Kinoshita and colleagues*** (open-access version here) who report that their cohort of participants with schizophrenia (n=42) not only presented with significantly elevated levels of plasma total homocysteine but also that this homocysteine load might also affect DNA methylation.

OK, a recap. Homocysteine and methionine take part in a merry dance together which crosses one-carbon metabolism (folic acid) and should eventually result in methionine being converted to SAM which then donates a methyl group for the process of DNA methylation. I've kinda covered this process on a previous post with autism in mind complete with hand drawn diagram by yours truly.

Kinoshita et al used some nifty technology (quantitative high-resolution DNA methylation array) to look at the methylation status of CpG islands (see here) located across whole gene regions based on the analysis of peripheral leukocytes. They concluded that alongside those elevations in homocysteine "plasma total homocysteine might affect DNA methylation across whole gene regions" and when talking about genes which have been linked to schizophrenia, one might be minded to look at methylation outside of more structural changes to the genome.

Outside of what I've already discussed about the big 'H' and methylation, there is another potentially important implication from all this talk about epigenetics and schizophrenia: intervention. I'm taken back for example to some interesting work about folic acid and SNPs in schizophrenia which was discussed on this blog (see here). The question being whether any intervention strategy designed to bring the homocysteine-methionine relationship back into planetary alignment would impact on gene methylation and then on presented symptoms? (Bearing in mind my caveat about not giving medical advice on this blog).

To finish, I can't talk about (CpG) islands without linking to an interpretation of a famous song about islands.... (what's occurring?)


* Wald DS. et al. Homocysteine and cardiovascular disease: evidence on causality from a meta-analysis. BMJ. 2002 Nov 23;325(7374):1202.

** Kałużna-Czaplińska J. et al. A focus on homocysteine in autism. Acta Biochim Pol. 2013 Jun 6.

*** Kinoshita M. et al. Plasma total homocysteine is associated with DNA methylation in patients with schizophrenia. Epigenetics. 2013 Apr 26;8(6).

---------- Kinoshita M, Numata S, Tajima A, Shimodera S, Imoto I, & Ohmori T (2013). Plasma total homocysteine is associated with DNA methylation in patients with schizophrenia. Epigenetics : official journal of the DNA Methylation Society, 8 (6) PMID: 23774737