Saturday, 18 February 2017

Meta analysis points a finger at a virus.

Morandi E, Tanasescu R, Tarlinton RE, Constantinescu CS, Zhang W, Tench C, Gran B.The association between human endogenous retroviruses and multiple sclerosis: A systematic review and meta-analysis. PLoS One. 2017 ;12(2):e0172415.

BACKGROUND:The interaction between genetic and environmental factors is crucial to multiple sclerosis (MS) pathogenesis. Human Endogenous Retroviruses (HERVs) are endogenous viral elements of the human genome whose expression is associated with MS.
OBJECTIVE: To perform a systematic review and meta-analysis and to assess qualitative and quantitative evidence on the expression of HERV families in MS patients.
METHODS:Medline, Embase and the Cochrane Library were searched for published studies on the association of HERVs and MS. Meta-analysis was performed on the HERV-W family. Odds Ratio (OR) and 95% confidence interval (CI) were calculated for association.
RESULTS: 43 reports were extracted (25 related to HERV-W, 13 to HERV-H, 9 to HERV-K, 5 to HRES-1 and 1 to HER-15 family). The analysis showed an association between expression of all HERV families and MS. For HERV-W, adequate data was available for meta-analysis. Results from meta-analyses of HERV-W were OR = 22.66 (95%CI 6.32 to 81.20) from 4 studies investigating MSRV/HERV-W (MS-associated retrovirus) envelope mRNA in peripheral blood mononuclear cells, OR = 44.11 (95%CI 12.95 to 150.30) from 6 studies of MSRV/HERV-W polymerase mRNA in serum/plasma and OR = 6.00 (95%CI 3.35 to 10.74) from 4 studies of MSRV/HERV-W polymerase mRNA in CSF.
CONCLUSIONS:This systematic review and meta-analysis shows an association between expression of HERVs, and in particular the HERV-W family, and MS.



We all have endogenous retroviruses in our genome, it makes up about 5% of our genome. There is a suggestion that these can be reactivated to be a target in MS. This study does a meta analysis of data out there and concludes that HERV-W is associated with MS. However, how many papers are related to the fact that there is commercial development of an anti-HERV-W antibody.

The problem with meta analysis is publication bias, as there is bias towards positive data being published, and if you don't understand the biology then you can't sort out the "wheat from the chaff".

This is why meta analysis of EAE data is largely futile, there is a dearth of negative studies and there is such over-interpretation of results to make them look interesting. 

The number of studies where drug X or compound Y is reported to save nerves, cause remyelination, when the drug never gets into the CNS. So if you see that there is an immunosuppressive action, it will be neuroprotective and stop demyelination and even allow remyelination because inflammation is stopped. You claim your drug to be neuroprotective and pro-remyelination and the person doing the meta analysis buys it. 

Therefore, be careful all sorts stuff can be believed of as fact.

If we did a meta analysis on whether T or B cells are the important target in MS, I bet T cells will win hands down.

Fingolimod works by trapping white blood subsets in lymph glands...if you did a meta analysis on that, we would all agree  that this is so. Are there any decenting ideas or data...I think there is.

Therefore careful understanding of the facts, probably gives us greater insight. We need more thinkers than herders

2 comments:

  1. decenting = dissenting

    Fingolimod works by trapping white blood subsets in lymph glands...if you did a meta analysis on that, we would all agree that this is so. Are there any decenting ideas or data...I think there is.

    ReplyDelete
    Replies
    1. Best I not change it otherwise your post will look strange.

      I often re read what I have written once posted and then edit, but some words I don't know or see...dyslexia

      Delete

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