"Autoimmune epilepsy is an underrecognized condition..."

"Among adult patients with epilepsy of unknown etiology, a significant minority had detectable serum Abs [autoantibodies] suggesting an autoimmune etiology."

So said the findings reported by Divyanshu Dubey and colleagues [1] continuing a research theme previously discussed on this blog (see here) on how epilepsy / seizure-type disorder(s) for some might have more to do with immune function than many people might think.

OK, a brief bit of background: epilepsy is a blanket term covering a wide variety of different presentations that affect the brain and specifically, 'the electrics' of the brain. Seizures are the most common symptom. Treatment typically comes in the form of anti-epileptic medicines (although other options are being considered for some). It's been known for a while that outside of the 'brain' focus of epilepsy, other biological systems might also play a role in the development/maintenance of the condition(s); specifically the immune system and quite often in cases where traditional anti-epileptic medicines don't seem to be able to control seizures effectively. The details are still a little sketchy but studies like the one from Dubey et al are trying to put some scientific flesh on to the bones of what facets of the immune system are potentially involved, specifically under 'autoimmune' conditions where the body fails to recognise 'self' as self and mounts an immune response against the body's own tissue(s).

Dubey and colleagues looked at a group of participants "presenting to neurology services with new-onset epilepsy or established epilepsy of unknown etiology" and tested donated serum samples "for Abs reported to be associated with autoimmune epilepsy (NMDAR-Ab, VGKCc-Ab, leucine-rich glioma-inactivated protein 1 [LGI1] Ab, GAD65-Ab, γ-aminobutyric acid type B receptor [GABAB] Ab, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor [AMPAR] Ab, antineuronal nuclear antibody type 1 [ANNA-1 or anti-Hu] Ab, Purkinje cell cytoplasmic antibody type 2 [PCA-2] Ab, amphiphysin Ab, collapsin-response mediator protein 5 [CRMP-5] Ab, and thyroperoxidase [TPO] Ab)." Quite a lot of those autoantibodies probably sound like gibberish to the lay reader but some of them have been discussed in other contexts on this blog (see here and see here for examples).

Results: some (15) of the 127 participants initially enrolled in the study were "subsequently excluded after identification of an alternative diagnosis." This in itself is interesting, as diagnoses such as "hypoxic or anoxic injury following cardiac arrest" and "ischemic stroke" are mentioned, illustrating how several different roads can lead to epilepsy and/or the presentation of seizures.

Then: "Serum Abs suggesting a potential autoimmune etiology were detected in 39 (34.8%) cases." Over a third of the cohort showed serological evidence of autoantibodies and some presented with more than one type of autoantibody as being present. Breaking down those serologically positive participants, we are told that: "19 patients (48.7%) had new-onset epilepsy and 20 patients (51.3%) had established epilepsy." The authors did also subsequently limit their findings to those cases excluding TPO-Ab and low-titer GAD65-Ab (autoantibodies where a specific role to epilepsy is unclear or not specific) but even then reported that: "23 patients (20.5%) with unexplained epilepsy had positive serologic findings strongly suggestive of an autoimmune cause of epilepsy." There is also a final part to the Dubey paper which also merits mention: "Among the 23 patients who were seropositive, 15 (65.2%) received some sort of immunotherapy. Better seizure outcome was associated with use of immunomodulatory therapy... especially with use of intravenous methylprednisolone... or plasmapheresis."

Alongside other (independent) studies in this area, the peer-reviewed evidence does seem to growing to suggest that within the wide (and heterogeneous) 'spectrum' that is epilepsy, at least some of that epilepsy might have an important immune component to it. To quote again from Dubey: "The data presented here suggest that autoimmune encephalitis may explain at least 20% of adult-onset epilepsies of unknown etiology." Aside from the importance of screening for said autoantibodies when certain cases of epilepsy appear at clinic, there are a few other potentially important points that could be raised about such data. Autism is area that I would be interested to see some further investigations carried out on with the Dubey findings in mind. Epilepsy is an important comorbidity 'over-represented' when it comes to autism (see here) and given the suggestions down the years that immune function (specifically autoimmunity) might be a facet of 'some' autism (see here for example) it's not beyond the realms of possibility that comorbid epilepsy might be a further facet of any autoimmune processes. Birds of an autoimmune feather tend to stick together and all that (see here). Add in the findings specifically talking about 'anti-NMDA-receptor encephalitis "mimicking an autistic regression"' (see here) and how methlyprednisolone might not be an uncommon medicine for some types of (autoimmune-related autistic presentation) and the hypotheses to be tested are laid out in front of you. By saying that, I don't want to take anything away from the more typical forms of epilepsy that can present (either alone or alongside autism) but rather point to the expanding knowledge base suggesting that immune functions may extend much further than just protecting the host from infection et al...

To close, slightly related to some of the content included in this post, the trailer for the film Brain on Fire (from the book of the same name) is out and looking like required viewing.

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[1] Dubey D. et al. Neurological Autoantibody Prevalence in Epilepsy of Unknown Etiology. JAMA Neurol. 2017 Feb 6.

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Dubey D, Alqallaf A, Hays R, Freeman M, Chen K, Ding K, Agostini M, & Vernino S (2017). Neurological Autoantibody Prevalence in Epilepsy of Unknown Etiology. JAMA neurology PMID: 28166327

Blood glutamate levels in autism meta-analysed

"The meta-analysis provided evidence for higher blood glutamate levels in ASD [autism spectrum disorder]."

That was the research bottom-line reported by Zhen Zheng and colleagues [1] (open-access available here) who surveyed the current peer-reviewed science literature in this area and found something to see based on: "Twelve studies involving 880 participants and 446 incident cases."

Drawing on the idea that glutamate is a rather important amino acid that plays a role in various biological processes including that related to the manufacture of GABA (see here), Zheng et al observed higher circulating blood levels of the stuff; a sort-of proxy for what might also be going on with regards to brain levels of glutamate. That "excess glutamate has been shown to be a potent neurotoxin that leads to neuronal cell death and plays a role in the pathophysiology of some neuropsychiatric disorders" is an important point to make as to the potential implications from the Zheng meta-analysis.

Zheng et al do mention how important glutamate is for the purposes of GABA production and in particular, how issues with glutamate decarboxylase (GAD) - a key enzyme that converts glutamate into GABA - described in some cases of autism [2] might account for the elevated levels of glutamate yet the generally lower levels of GABA seen in autism (see here). I'd be inclined to agree that this is perhaps one of the more important implications for glutamate in autism; particularly when added to the whole 'glutamate linked to epilepsy' bit knowing how close a relationship autism and epilepsy seem to share (see here).

Where next with this research area I hear you ask? Well, I'd like to know a little more not just about glutamate but also another linked amino acid called glutamine. It has already been talked about in the autism research literature a while back (see here) but a lot more follow-up work is required on these two important compounds and what their differing ratio might mean. I'd also like to see more work done on the idea that "the mood stabilizer valproic acid, which exerts neuroprotective effects against glutamate-induced excitotoxicity, is effective in ASD [autism spectrum disorder] with seizures." Yes, I know that valproic acid a.k.a valproate is a bit of a double-edged sword when it comes to autism and other offspring developmental issues under certain circumstances (see here) but much like another research story in autism (see here) timing of exposure seems to be a key issue and one wonders whether other unrelated compounds might also exert a similar neuroprotective effect.

As to the idea that "blood glutamate levels may serve as a potential biomarker in the diagnosis of ASD" made by Zheng and colleagues, we'll wait and see...

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[1] Zheng Z. et al. Blood Glutamate Levels in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis. PLoS One. 2016 Jul 8;11(7):e0158688.

[2] Yip J. et al. Decreased GAD65 mRNA levels in select subpopulations of neurons in the cerebellar dentate nuclei in autism: an in situ hybridization study. Autism Res. 2009 Feb;2(1):50-9.

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Zheng Z, Zhu T, Qu Y, & Mu D (2016). Blood Glutamate Levels in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis. PloS one, 11 (7) PMID: 27390857

Autoantibodies not implicated in cases of autism?

Contrary results are a common feature of the autism peer-reviewed research landscape. No sooner does one group publish the next 'big thing' when it comes to the singular term 'autism' than seemingly opposite results follow suit.

So it is with the paper under discussion today by Simran Kalra and colleagues [1] (open-access) who concluded that: "The idea that autoantibodies represent an underlying cause or are biomarkers for autism pathophysiology is not supported by this report."

Autoantibodies by the way, are part of the process whereby the body's immune system fails to recognise self as 'self' and mounts a response against the body's own tissue. It's a topic that has been discussed quite extensively with the autism spectrum in mind (see here for example) as part of a wider scientific debate about a role for immune function in at least some autism (see here).

The Kalra paper is open-access but a few details might be useful:

• "Serological analysis was performed on typically developing children (n = 55), developmentally delayed children without autism (n = 24) and children diagnosed with autism (n = 104)." I believe this cohort of children were part of a larger study titled: 'Clinical and Immunological Investigations of Subtypes of Autism'.
• Based on an interesting analytical method - Luciferase Immunoprecipitation Systems (LIPS) - used as an alternative to the more traditional ELISA methods, researchers initially set about looking for the presence of "autoantibodies against GAD65." GAD65 by the way, is part and parcel of the mechanism for synthesising GABA (see a previous post on this topic). They then extended the study focus to look for antibodies "against several other autoimmune-associated autoantigens, candidate neurological autoantigens, and viral proteins."
• Results: well, when comparing study samples against samples from three people with diagnosed type 1 diabetes where GAD65 autoantibodies were to be expected to be present (and indeed were): "testing of serum from the typically developed children..., developmentally delayed children... and children with ASD... demonstrated no seropositive autoantibodies to GAD65." 
• Likewise when comparing autism samples with samples from "three positive control samples from subjects with systemic lupus erythematosus" for Ro52 - one of the anti-Ro antibodies found in cases of SLE - there was again nothing of note to see. Collectively the authors conclude that: "These findings rule out the possibility that GAD65 and Ro52 autoantibodies are biomarkers in ASD [autism spectrum disorder]."
• Among the other results reported is an interesting remark when it comes to a retrovirus called XMRV. For those in chronic fatigue syndrome / myalgic encephalomyelitis circles, XMRV will probably be remembered for all the wrong reasons (see here) albeit with not all questions completely answered (see here). Kalra et al found nothing in terms of seropositivity when it came to autism and XMRV (and another target, mouse mammary tumor virus (MMTV)). They do however caution that "additional studies are needed to determine if other infectious agents, or the body's response to such infections agents, might play a role" in some autism.

These results are interesting. As per my opening comment on contrary results being part and parcel of autism research, the lack of GAD65 antibodies detailed is in direct contrast to previous findings such as those produced by Rout and colleagues [2] for example. Whilst there may be various reasons for the difference in findings including a role for the analytical method used, I was drawn to one comment made by Rout et al suggesting that there may be a subgroup of children with autism and/or ADHD (attention-deficit hyperactivity disorder) where further characterisation may be needed. That also reduced levels of GAD65 mRNA levels have been reported [3] in relation to autism (with appropriate caveats regarding tissue used for study) does not mean that GAD65 is off the research menu just yet.

The lack of XMRV antibody findings reported by Kalra et al in relation to their autism group is not necessarily new news. Previous studies such as the one from Satterfield and colleagues [4] basically said as much.

There are of course quite a few other types of autoantibodies and/or antibodies to infective agents that perhaps require more study using the technique utilised by Kalra and colleagues with autism in mind. The various contributions in this research area from the Saudi-Egyptian research tag-team that crop up on this blog every now and again (see here and see here) might be a next port of call. Anti-brain antibodies detailed by other teams might also receive the same treatment (see here). Who knows, researchers might also consider putting a little more flesh on the bones of all that folate receptor autoantibody research that is crying out for independent replication (see here) or even antimitochondrial antibodies (see here). Quite a few areas to consider.

As for the infection side of things and realising the important contribution that at least one of the authors on the Kalra paper has made to another area of research (Swedo and PANDAS/PANS) I can think of quite a few research studies to be done. My growing interest in enterovirus and autism (see here) or even enterovirus and ADHD (see here) is again requiring some further investigation. Perhaps a little more 'out there' are the ways and means that the methods detailed by Kalra might also be transferable to more ancient retroviruses such as the HERVs that have been discussed before on this blog (see here) with autism and various other conditions in mind (see here).

Music: John Newman - Come And Get It.

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[1] Kalra S. et al. No evidence of antibodies against GAD65 and other specific antigens in children with autism. BBA Clinical. 2015. August 8.

[2] Rout UK. et al. Presence of GAD65 autoantibodies in the serum of children with autism or ADHD. Eur Child Adolesc Psychiatry. 2012 Mar;21(3):141-7.

[3] Yip J. et al. Decreased GAD65 mRNA levels in select subpopulations of neurons in the cerebellar dentate nuclei in autism: an in situ hybridization study. Autism Res. 2009 Feb;2(1):50-9.

[4] Satterfield BC. et al. PCR and serology find no association between xenotropic murine leukemia virus-related virus (XMRV) and autism. Mol Autism. 2010 Oct 14;1(1):14.

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Kalra, S., Burbelo, P., Bayat, A., Ching, K., Thurm, A., Iadarola, M., & Swedo, S. (2015). No evidence of antibodies against GAD65 and other specific antigens in children with autism BBA Clinical DOI: 10.1016/j.bbacli.2015.08.001