Thursday, 16 October 2014

MicroRNAs and Chronic Fatigue Syndrome

"No one User wrote me! I'm worth
millions of their man-years!"
Not so long ago I posted an entry talking about microRNAs and autism (see here). As well as including some rather interesting, if preliminary findings, that particular piece of work also served to introduce yet another layer of complexity to our genome and its expression: microRNAs.

I was therefore always going to be more than a little intrigued by the results published by Ekua Brenu and colleagues [1] and their observations on circulating microRNAs (miRNAs) in a small participant group diagnosed with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME). Indeed their conclusion that "three differentially expressed circulating miRNAs in CFS/ME patients" might have potential biomarker qualities invites quite a bit of further study in this area.

The Brenu paper is open-access but a few details are worthwhile reiterating:

  • The name of the game was "high-throughput sequencing (HTS) to globally profile circulating miRNA expression" in a small participant group diagnosed with CFS/ME (n=20) compared with non-fatigue controls (n=20). "This was followed by confirmative reverse transcription-quantitative PCR (RT-qPCR) to determine differential miRNA expression in CFS/ME".
  • Actually, when it came down to it: "The six CFS/ME patients and six non-fatigued controls with the highest abundance of small RNA were used for HTS".
  • Results: 19 miRNAs were reported as being significantly 'dysregulated' in CFS/ME compared to controls. Sixteen of these were subsequently dropped from the analysis as a result of being considered "low in abundance" from a detection point of view.
  • Three miRNAs were left - hsa-miR127-3p, hsa-miR-142-5p and hsa-miR-143-3p - and were confirmed by RT-qPCR. All were up-regulated in CFS/ME cases and considered: "potential plasma biomarkers for CFS/ME diagnosis".

Obviously there is a long, long way to go before these findings translate into anything like a biomarker for CFS/ME. As per the authors' discussions, there are quite a few other conditions / biological processes which are seemingly impacted by these miRNAs; as one example: "Over-expression of miR-142-5p has been observed in most cancer-related and immunological disorders". So exclusivity to CFS/ME is unlikely to be seen. That and the fact that like quite a few conditions described these days, CFS/ME is likely not to just be one unified condition...

I note also that this is not the first time that this research group have ventured into the whole "microRNAs as prospective biomarkers" of CFS/ME as per some work a few years earlier [2]. On that particular occasions, drawing on an equally small participant group, the authors reported findings implicating other miRNAs. Specifically: "There was a significant reduction in the expression levels of miR-21, in both the NK [Natural Killer] and CD8(+)T cells in the CFS/ME sufferers". The immune system link with CFS/ME is interesting but again there's a lot more work needed in this area.

Music, music, music... D.I.Y from Heaton & Abbott.

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[1] Brenu EW. et al. High-Throughput Sequencing of Plasma MicroRNA in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. PLoS One. 2014 Sep 19;9(9):e102783.

[2] Brenu EW. et al. Cytotoxic lymphocyte microRNAs as prospective biomarkers for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. J Affect Disord. 2012 Dec 10;141(2-3):261-9.

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ResearchBlogging.org Brenu EW, Ashton KJ, Batovska J, Staines DR, & Marshall-Gradisnik SM (2014). High-Throughput Sequencing of Plasma MicroRNA in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. PloS one, 9 (9) PMID: 25238588