Friday, 24 July 2015

Autism, asthma and IL-17

"IL-17 was increased in ASD [autism spectrum disorder] children with co-morbid asthma compared to controls with the same condition."

That was the conclusion reached by Marjannie Eloi Akintunde and colleagues [1] including some notable names on the authorship list from the University of California, Davis. IL-17 (Interleukin 17) by the way, refers to a group of cytokines - chemical messengers of the immune system - linked to various processes centred on inflammation. Jin & Dong [2] provide quite a good overview of the complexities of IL-17 with respect to immune function and inflammation.

Asthma crops up yet again on this blog. Based on the idea that overlapping diagnoses of autism and asthma might be more frequent than one would perhaps anticipate (see here and see here), researchers looked at the production of various cytokines including IL-17 in biological samples provided by a group of young children with ASD compared to asymptomatic controls "following ex vivo mitogen stimulation." They reported that levels of IL-17 were elevated in samples from the group with ASD compared to controls and for those with ASD and comorbid asthma, levels of IL-17 were elevated compared with those diagnosed with ASD minus asthma.

This is not the first time that IL-17 has cropped up on the autism research radar as per the findings reported by Al-Ayadhi & Mostafa [3] also covered on this blog (see here). Other, more case report data has also hinted that IL-17 as part of a "proinflammatory, autoimmune-polarized cytokine profile" [4] might also show some connection with [some] autism. Even some of the co-authors on the Akintunde paper have previously reported on IL-17 in relation to autism [5] albeit not necessarily central to the cytokine 'profile' of autism.

It is important to note that whilst there were group differences noted between autism and controls, the idea that IL-17 might distinguish autism + asthma from autism alone is not an entirely unexpected finding. Elevated levels of IL-17 have been reported in cases of asthma [6] and in some quarters, has been touted as a possible 'therapeutic target' specifically in those cases of steroid-insensitive asthma [7]. Questions do however remain about the hows and whys of the association between autism and asthma and importantly, whether there may be overlapping aetiological factors leading to both conditions developing alongside the idea that other comorbidity might be also implicated (see here).

Music: MGMT - Time To Pretend.

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[1] Akintunde ME. et al. Increased production of IL-17 in children with autism spectrum disorders and co-morbid asthma. Journal of Neuroimmunology. 2015. July 11.

[2] Jin W. & Dong C. IL-17 cytokines in immunity and inflammation. Emerging Microbes & Infections. 2013; 2: e60.

[3] Al-Ayadhi LY. & Mostafa GA. Elevated serum levels of interleukin-17A in children with autism. J Neuroinflammation. 2012 Jul 2;9:158.

[4] Magid-Bernstein J. et al. Case report: cytokine and CD4+ T-cell profiles of monozygotic twins with autism and divergent comorbidities and drug treatment. J Child Neurol. 2015 Mar;30(3):386-90.

[5] Onore C. et al. Decreased cellular IL-23 but not IL-17 production in children with autism spectrum disorders. J Neuroimmunol. 2009 Nov 30;216(1-2):126-9.

[6] Chesné J. et al. IL-17 in severe asthma. Where do we stand? Am J Respir Crit Care Med. 2014 Nov 15;190(10):1094-101.

[7] Morishima Y. et al. Th17-associated cytokines as a therapeutic target for steroid-insensitive asthma. Clin Dev Immunol. 2013;2013:609395.

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ResearchBlogging.org Akintunde, M., Rose, M., Krakowiak, P., Heuer, L., Ashwood, P., Hansen, R., Hertz-Picciotto, I., & Van de Water, J. (2015). Increased production of IL-17 in children with autism spectrum disorders and co-morbid asthma Journal of Neuroimmunology DOI: 10.1016/j.jneuroim.2015.07.003