On (pre)pregnancy obesity and inflammation and offspring autism risk

At the time of writing this [long read] post there has been a flurry of autism research articles making news.

The headline: 'Scientists create the first ever autistic monkeys' referring to the work published by Liu and colleagues [1] who reported on "lentivirus-based transgenic cynomolgus monkeys (Macaca fascicularis) expressing human MeCP2 in the brain exhibit autism-like behaviours and show germline transmission of the transgene" started the ball rolling. Anyone who knows a little bit about autism will realise that mutations in the MeCP2 gene generally refers to Rett syndrome. Whilst linked to the expression of certain autistic-like behaviours, Rett syndrome is but one part of the very heterogeneous spectrum called autism. I'd also suggest that other primate research had previously 'modelled' autism, or at least, certain facets of autism (see here).

Next up was the headline: 'Autism Diets: Can Nutrition Have An Impact On Autism Risk?' portraying the findings reported by Xie and colleagues [2] (open-access) who talked about inborn errors of carnitine metabolism potentially being linked to some autism. This follows some important research history in this area (see here) specifically linked to a gene called trimethyllysine hydroxylase, epsilon (TMLHE) (see here). Inborn errors of metabolism potentially linked to autism (some autism) is a woefully under-researched and under-screened area (see here).

And then we have two papers that make up the core of today's post. The first by Mengying Li and colleagues [3] continues something of an important theme in autism research circles these days on how mum's weight and risk of diabetes during pregnancy might have a bearing on offspring development [4], and specifically the risk of autism and comorbid learning disability. This time around researchers "examined the independent and combined effects of maternal prepregnancy obesity and maternal diabetes on the risk of autism spectrum disorder (ASD) in parallel with other developmental disorders (DDs)." They did this by analysing data - "a subset of the Boston Birth Cohort who completed at least 1 postnatal study visit at Boston Medical Center between 1998 and 2014" - and comparing rates of autism ("based on physician diagnoses as documented in electronic medical records") and other diagnoses "among 6 groups defined by maternal prepregnancy obesity and diabetes status." They found that yes, those mums who were obese and presented with pregestational diabetes (PGDM) had a [significantly] increased risk of offspring autism as were those with both obesity and gestational diabetes. Interestingly: "This pattern of risk was mostly accounted for by cases with co-occurring ASD and ID."

Before heading further into the potential whys and wherefores to account for the Li results, I want to bring in another paper making news. Gloria Choi and colleagues [5] report results that have created headlines such as: 'Autism caused by immune response to viral infection during pregnancy?' Accepting that again, the use of the singular term 'autism' in that media piece does little to accentuate the degree of diversity that the label includes and the various 'routes' that might bring someone to a diagnosis (see here for example), I found this to be an interesting paper.

Building on the idea that viral infection during pregnancy might be able to affect offspring risk of autism or other behavioural outcomes (see here), researchers set about looking at some of the possible mechanisms involved in this process. The work of the late Paul Patterson (see here) gets a mention in the Choi study write-up and the concept of maternal immune activation (MIA). Pregnant mice were initially artificially 'immune stimulated' and offspring were found to display the sorts of behaviours that had previously been mentioned in the science literature in this area. Researchers then took out some key elements of the cells involved in the inflammatory response to immune activation - specifically Th17 cells - and repeated the artificial immune activation procedure. Offspring mice did not appear to show the same behavioural issues as those whose mother mice possessed their Th17 cells intact. Further, when pregnant mother mice were given an antibody that blocks interleukin-17 (IL-17) (produced by Th17 cells), offspring mice also showed behavioural differences compared with those offspring whose mother mice received immune stimulation but nothing else. Ergo, the suggestion that: "therapeutic targeting of TH17 cells in susceptible pregnant mothers may reduce the likelihood of bearing children with inflammation-induced ASD-like phenotypes." The idea of an 'inflammation-induced autism phenotype' by the way is not a new one (see here).

Whilst remembering that mice are mice (and monkeys are monkeys) and so not necessarily able to model all of the complexity of human autism (and its important comorbidities), these are potentially important findings. I've covered the idea that immune function and inflammatory processes might be part and parcel of some autism previously on this blog (see here for example) as part of a larger shift in psychiatry circles (see here). Indeed, some of that research has specifically talked about IL-17 and at least some autism (see here for example) and the idea that levels might be increased compared to other groups. Insofar as the notion of blocking the effects of IL-17 (or Th17), I'm minded to suggest that we need a lot more data first before specific interventions are discussed or attempted including looking at compounds linked to the maturation of Th17 cells [6] as possible targets.

What the Li and Choi papers share in common are several variables. First is the idea that 'the nine months that made us' might indeed be an important time insofar as future behavioural outcome. Indeed the Li results also suggest that what happens prepregnancy might also exert a significant effect. Second is the notion that inflammation (or response to inflammation) in-utero might be an important concept for at least some 'types' of autism and indeed other future diagnoses (see here). If you're wondering what obesity might have to do with inflammation, well, let's just say that quite a few researchers/research groups believe there is an important link [7] and certainly some write-up on the Li paper makes that point. I say this acknowledging that Li and colleagues also noted the children with autism in their cohort were also more likely to be born preterm and with a low birth weight. Finally, is the question of whether disrupting inflammatory processes or responses particularly during critical times of prepregnancy and/or pregnancy might be something to look at with a view to altering any 'programmed' offspring autism or other risk. Appreciating that not everyone might receive this question the same way, I do think we need to have some frank discussions about this option. That Li and colleagues reported on prepregnancy obesity/diabetes as being particularly associated with autism and learning (intellectual) disability perhaps provides an important detail pertinent to the idea of improving child outcomes and quality of life (particularly if pregnancy inflammation translates into offspring inflammation and where that could lead).

Some important future research directions are indicated.

Music, and what else but Terry Wogan and The Floral Dance. Rest in peace Sir Terry and not forgetting your best quotes...

----------

[1] Liu Z. et al. Autism-like behaviours and germline transmission in transgenic monkeys overexpressing MeCP2. Nature. 2016 Jan 25.

[2] Xie Z. et al. Inborn Errors of Long-Chain Fatty Acid β-Oxidation Link Neural Stem Cell Self-Renewal to Autism. Cell Reports. 2016. Jan 28.

[3] Li M. et al.  The Association of Maternal Obesity and Diabetes With Autism and Other Developmental Disabilities. Pediatrics. 2016. Jan 29.

[4] Connolly N. et al. Maternal metabolic risk factors for autism spectrum disorder-An analysis of electronic medical records and linked birth data. Autism Res. 2016 Jan 29.

[5] Choi GB. et al. The maternal interleukin-17a pathway in mice promotes autism like phenotypes in offspring. Science. 2016. 28 Jan.

[6] Huang W. et al. DDX5 and its associated lncRNA Rmrp modulate TH17 cell effector functions. Nature. 2015 Dec 24;528(7583):517-22.

[7] Lumeng CN. & Saltiel AR. Inflammatory links between obesity and metabolic disease. J Clin Invest. 2011 Jun;121(6):2111-7.

----------

Li, M., Fallin, M., Riley, A., Landa, R., Walker, S., Silverstein, M., Caruso, D., Pearson, C., Kiang, S., Dahm, J., Hong, X., Wang, G., Wang, M., Zuckerman, B., & Wang, X. (2016). The Association of Maternal Obesity and Diabetes With Autism and Other Developmental Disabilities PEDIATRICS, 137 (2), 1-10 DOI: 10.1542/peds.2015-2206



Choi GB, Yim YS, Wong H, Kim S, Kim H, Kim SV, Hoeffer CA, Littman DR, & Huh JR (2016). The maternal interleukin-17a pathway in mice promotes autismlike phenotypes in offspring. Science (New York, N.Y.) PMID: 26822608

Paediatric autoimmune enteropathy: I did not know that

Consider this post one of my 'other musings' entries on this blog and also a slightly more descriptive post than usual.

The source paper today is by Singhi and colleagues* discussing the pretty rare condition paediatric autoimmune enteropathy (AIE), which I have to say was a bit of an eye-opener for me. Associated with protracted diarrhoea (sorry if your eating at the moment), weight loss and gut mucosa damage, the crux of the paper by Singhi et al seemed to be that the gut or gastrointestinal tract is a central organ affected by AIE - hence the enteropathy bit of the condition description - but also that "autoimmune enteropathy in children is a heterogeneous disease with protean clinical and pathologic findings". Protean by the way, means readily assuming different forms or characters (yes, I had to look it up).

I say that this is another one of my other musings post, but one of the first people to describe this condition was one Prof. John Walker-Smith** who some people might know from the still quite contentious area of gut physiology and autism*** (see a related post here). Mention of the gluten-free (GF) diet in amongst the AIE literature also piqued my attention, allowing for the fact that such dietary intervention does not seem to help in many cases of AIE**** as it does more frequently in coeliac (celiac) disease.

With my non-expert hat very firmly in place when it comes to AIE and my caveat about not giving medical or clinical advice on this blog, I was rather interested in the condition and so set about looking at some of the related literature around it to share with you. Here goes:

• AIE is a serious condition primarily reported in very young infants. I say serious because in quite a few of the experimental reports of AIE, mortality is, unfortunately, mentioned (see here for an example). 
• Whilst quite a lot of the research literature is focused on AIE in children as a function of the increased likelihood of occurring infancy, there is a body of research suggesting that adults can also present with the condition*****. In some quarters, that adult presentation has been linked to refractory sprue. 
• Boys are over-represented in AIE. 
• Gut epithelial cell antibodies - that is an immune response to the cells lining the gut - characterise this disease. In particular, anti-enterocyte antibodies are reported to be an important part of AIE as per the link with autoimmunity. That being said, anti-goblet (the mucus producing cells) and anti-Paneth (important defender cells of the gut) cell antibodies have also been reported in cases. 
• The autoimmunity link is certainly strong when it comes to AIE as per the varied comorbidity and other autoantibodies tied into presentation******. T-cells, and in particular Th-17 cells, which have been linked on more than one occasion to autoimmune conditions (see here), have been a focal point for the pathology of AIE*******. Indeed to quote the article by Ruemmele et al "Anti-enterocyte autoantibodies .... seem to be of a secondary nature and can no more be considered as directly disease causing".
• Going back to the Singhi paper, the autoimmune element to AIE has very much informed the therapeutic response to AIE and the use of various immuno-suppressing medicines. So starting with things like steroids, treatment can also include cyclosporin (see here********), tacrolimus and cyclophosphamide. Other therapeutic interventions also include anti-lymphocyte immunoglobulin and eventually in some cases, a bone marrow transplant (see here too). I did wonder, in light of the recent-ish news that alefacept - another immuno-suppressive medicine - might impact on the presentation of another autoimmune conditions, type 1 diabetes (see here), whether there may be other treatment options waiting in the wings too.

I'm gonna stop at that with this very descriptive post. AIE is a complicated condition which is both heterogeneous and potentially carrying quite a bit of other autoimmune related baggage. I do get the impression from quite a few sources that in almost 30 years since formal description, some progress has been made on discovering how AIE is expressed and indeed, in treating the condition. One might say that the advent of immuno-suppressive therapeutic options being applied to AIE, has been nothing short of remarkable in terms of long-term prognosis.

----------

* Singhi AD. et al. Pediatric autoimmune enteropathy: an entity frequently associated with immunodeficiency disorders. Mod Pathol. 2013 Sep 20. doi: 10.1038/modpathol.2013.150.

** Unsworth DJ. & Walker-Smith JA. Autoimmunity in diarrhoeal disease. J Pediatr Gastroenterol Nutr. 1985 Jun;4(3):375-80.

*** Ashwood P. et al. Intestinal lymphocyte populations in children with regressive autism: evidence for extensive mucosal immunopathology. J Clin Immunol. 2003 Nov;23(6):504-17.

**** Walker-Smith JA. Coeliac Disease and Autoimmune Enteropathy. Developments in Gastroenterology. 1991; 13: 131-136.

***** Freeman HJ. Adult autoimmune enteropathy. World J Gastroenterol. 2008. 14(8): 1156–1158.

****** Akram S. et al. Adult autoimmune enteropathy: Mayo Clinic Rochester experience. Clin Gastroenterol Hepatol. 2007 Nov;5(11):1282-90.

******* Ruemmele FM. et al. Autoimmune enteropathy: molecular concepts. Curr Opin Gastroenterol. 2004 Nov;20(6):587-91.

******** Sanderson IR. et al. Response to autoimmune enteropathy to cyclosporin A therapy. Gut. 1991 Nov;32(11):1421-5.

----------

Singhi AD, Goyal A, Davison JM, Regueiro MD, Roche RL, & Ranganathan S (2013). Pediatric autoimmune enteropathy: an entity frequently associated with immunodeficiency disorders. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc PMID: 24051695

IL-17A elevated in cases of autism

"The converging evidence strongly argues that neurodevelopmental immune insults and genetic background critically interact and result in increased risk for either autism or schizophrenia". So say Max Michel and colleagues* in their recent paper reviewing the often intricate findings in this area of investigation. Personally, I have to say that I agree with their sentiments, after having read through quite a lot of the literature on this topic over the years. I hasten to add that both the genetic and environmental effects acting on the immune system, or any other system in cases of autism, is likely to be variable and not uniform across the condition. As far as we know...

Yet more evidence for a potential role for the immune system and certain cytokines in cases of autism has emerged from two very familiar names, Laila Yousef Al-Ayadhi & Gehan Ahmed Mostafa in this paper** (full-text) looking at levels of the proinflammatory cytokine IL-17A. I say that these are familiar names because this research tag-team have been pretty prolific in recent years as per their publication entries on autism (here) and various immune-related findings. I would perhaps also plug a few previous blog posts about their work (here, here and here).

Let's start with a description. I'm sure quite a few people who follow the immune system research in relation to autism will have heard about Th1 and Th2 (type 1 and 2 helper T-cells). As per their name, helper T-cells help; more specifically they are involved in the orchestra that this is the immune response and in particular, cytokines and their expression, different types of cytokines, depending on the type of helper T-cell. Balance seems to be quite an important concept when it comes to Th1 and Th2 as per this article by Berger*** (full-text).

For quite a long time, the concepts of Th1 and Th2 predominated. That is until another kind of helper T-cell came onto the scene: Th17 - T helper 17 cells. Th17 produces the IL-17 family of cytokines which play a role in host defence and inflammation. Th17 has also been tied to quite a few 'autoimmune' conditions such as psoriasis (here) and inflammatory bowel disease (here) among others. There is of course quite a lot of biochemistry behind Th17 cells and the counterbalance, Treg(s) (including an old friend, IL-6) but I have neither the will nor expertise to go too far into all that now.

After that very brief overview, let's go through what Al-Ayadhi & Mostafa did and found:

• A sample of 45 children diagnosed with DSM-IV autism (mean age: 8.4 years) were included for study and compared with 40 age- and sex-matched 'apparently healthy' asymptomatic children. No comorbid autoimmune conditions were recorded in participants as far as the authors could tell.
• Participants with autism were also 'graded' on the severity of their autism presentation by way of the CARS; most fell into the severe category (n=28); the others (n=17) were described as having mild to moderate autism.
• Blood samples were drawn from all participants and serum levels of IL-17A determined by ELISA. Importantly, from an analytical perspective, all samples were run twice in independent experiments to confirm the results and rule out cross-reactivity (see here for a description).
• Results: as a group, the children with autism presented with significant elevations in IL-17A compared to controls. Individually, almost half of the children with autism presented with elevated IL-17A levels based on results on or above the 95th percentile of serum IL-17A noted in the control group.
• Severity of autistic symptoms seemed also to show some relationship with serum IL-17A levels in that the more severe presentation was associated with greater serum levels than those with a more moderate presentation. Age and gender did not seem to show effects.

There are a few things that can be taken from this study. IL-17 and inflammation. IL-17 and autism. Inflammation and autism. Need I say anything else? The association between Th17 and autoimmune disorders is something to bear in mind. I've talked before about autism and both features of autoimmunity seemingly present in some cases (here) or overlap with autoimmune comorbidity (here). The current results seem to suggest that there maybe something which might, at a biochemical level, relate autism and autoimmunity in at least some cases of autism; indeed quite a few cases judging by this latest paper. The question is: are IL-17A levels a core feature of autism or merely describing some hidden autoimmune comorbidity?

This is not the first time that a relationship between Th17 and autism has been suggested. Suzuki and colleagues**** (full-text) reported elevations in IL-17 and various other cytokines in their study of young adolescent boys with autism compared with control. Indeed the current authors also cited a potential role for IL-17 in other findings, specifically related to elevations in osteopontin levels previously discussed with parallel features according to things like symptom severity affecting results.

I suppose the final question should be: what can be done about elevated levels of IL-17? Reiterating my position about not giving medical advice or anything that could be construed as medical advice, the research literature contains a few options for further investigation. The therapeutic application of monoclonal antibodies against human IL-17A has already been mentioned in other areas of investigation. Leonardi and colleagues***** reported some initial success on the use of ixekizumab for a specific type of psoriasis, plaque psoriasis and improvement in clinical symptoms. Similar preliminary findings were also reported by Hueber and colleagues****** based the use of on another IL-17A human monoclonal antibody, AIN457 (secukinumab). Other compounds also seem to have the potential to affect IL-17 levels or production too. Lanzilli and colleagues******* for example, discussed the potential of resveratrol to affect IL-17 levels (at least in vitro).  Again, I reiterate the need for a lot more efficacy and safety research before these and other potential compounds go anywhere near people with autism.

There seems to be a rising tide of research coming through suggestive of links between at least some cases of autism and issues with the immune system and more precisely autoimmunity. Bearing in mind the 'correlation does not equal causation' motif, I think back to the post on Dr Kevin Becker's paper and the other work that has been done in this area and wonder whether we really should be making moves to more generalised screening for autoimmune markers and comorbidity where an autism diagnosis is given, if only to establish how deep the rabbit hole really goes?

To finish, and to coincide with the news about "detecting a particle consistent with the Higgs boson", the Galaxy song by Monty Python. Makes me feel quite insignificant really.

---------

* Michel M. et al. Immune system gene dysregulation in autism & schizophrenia. Developmental Neurobiology. June 2012.

** Al-Ayadhi LY. & Mostafa GA. Elevated serum levels of interleukin-17A in children with autism. Journal of Neuroinflammation. 2012; 9: 158.
DOI: 10.1186/1742-2094-9-158

*** Berger A. Th1 and Th2 responses: what are they? BMJ. 2000; 321: 424.1.

**** Suzuki K. et al. Plasma cytokine profiles in subjects with high-functioning autism spectrum disorders. PLoS ONE. 2011; 6: e20470.

***** Leonardi C. et al. Anti-interleukin-17 monoclonal antibody ixekizumab in chronic plaque psoriasis. NEJM. 2012; 366: 1190-1199.

****** Heuber W. et al. Effects of AIN457, a fully human antibody to interleukin-17A, on psoriasis, rheumatoid arthritis, and uveitis. Science Translational Medicine. 2010; 2: 52ra72.

******* Lanzilli G. et al. Anti-inflammatory effect of resveratrol and polydatin by in vitro IL-17 modulation. Inflammation. 2012; 35: 240-248.