Of Mice and Men Again: New Genomic Study Helps Explain why Mouse Models of Acute Inflammation do not Work in Men

25 02 2013

ResearchBlogging.org

This post is update after a discussion at Twitter with @animalevidence who pointed me at a great blog post at Speaking of Research ([19], a repost of [20], highlighting the shortcomings of the current study using just one single inbred strain of mice (C57Bl6)  [2013-02-26]. Main changes are in blue

A recent paper published in PNAS [1] caused quite a stir both inside and outside the scientific community. The study challenges the validity of using mouse models to test what works as a treatment in humans. At least this is what many online news sources seem to conclude: “drug testing may be a waste of time”[2], “we are not mice” [3, 4], or a bit more to the point: mouse models of inflammation are worthless [5, 6, 7].

But basically the current study looks only at one specific area, the area of inflammatory responses that occur in critically ill patients after severe trauma and burns (SIRS, Systemic Inflammatory Response Syndrome). In these patients a storm of events may eventually lead to organ failure and death. It is similar to what may occur after sepsis (but here the cause is a systemic infection).

Furthermore the study only uses one single approach: it compares the gene response patterns in serious human injuries (burns, trauma) and a human model partially mimicking these inflammatory diseases (human healthy volunteers receiving  a low dose endotoxin) with the corresponding three animal models (burns, trauma, endotoxin).

And, as highlighted by Bill Barrington of “Understand Nutrition” [8], the researchers have only tested the gene profiles in one single strain of mice: C57Bl6 (B6 for short). If B6 was the only model used in practice this would be less of a problem. But according to Mark Wanner of the Jackson Laboratory [19, 20]:

 It is now well known that some inbred mouse strains, such as the C57BL/6J (B6 for short) strain used, are resistant to septic shock. Other strains, such as BALB and A/J, are much more susceptible, however. So use of a single strain will not provide representative results.

The results in itself are very clear. The figures show at a glance that there is no correlation whatsoever between the human and B6 mouse expression data.

Seok and 36 other researchers from across the USA  looked at approximately 5500 human genes and their mouse analogs. In humans, burns and traumatic injuries (and to a certain extent the human endotoxin model) triggered the activation of a vast number of genes, that were not triggered in the present C57Bl6 mouse models. In addition the genomic response is longer lasting in human injuries. Furthermore, the top 5 most activated and most suppressed pathways in human burns and trauma had no correlates in mice. Finally, analysis of existing data in the Gene Expression (GEO) Database showed that the lack of correlation between mouse and human studies was also true for other acute inflammatory responses, like sepsis and acute infection.

This is a high quality study with interesting results. However, the results are not as groundbreaking as some media suggest.

As discussed by the authors [1], mice are known to be far more resilient to inflammatory challenge than humans*: a million fold higher dose of endotoxin than the dose causing shock in humans is lethal to mice.* This, and the fact that “none of the 150  candidate agents that progressed to human trials has proved successful in critically ill patients” already indicates that the current approach fails.

[This is not entirely correct the endotoxin/LPS dose in mice is 1000–10,000 times the dose required to induce severe disease with shock in humans [20] and mice that are resilient to endotoxin may still be susceptible to infection. It may well be that the endotoxin response is not a good model for the late effects of  sepsis]

The disappointing trial results have forced many researchers to question not only the usefulness of the current mouse models for acute inflammation [9,10; refs from 11], but also to rethink the key aspects of the human response itself and the way these clinical trials are performed [12, 13, 14]. For instance, emphasis has always been on the exuberant inflammatory reaction, but the subsequent immunosuppression may also be a major contributor to the disease. There is also substantial heterogeneity among patients [13-14] that may explain why some patients have a good prognosis and others haven’t. And some of the initially positive results in human trials have not been reproduced in later studies either (benefit of intense glucose control and corticosteroid treatment) [12]. Thus is it fair to blame only the mouse studies?

dick mouse

dick mouse (Photo credit: Wikipedia)

The coverage by some media is grist to the mill of people who think animal studies are worthless anyway. But one cannot extrapolate these findings to other diseases. Furthermore, as referred to above, the researchers have only tested the gene profiles in one single strain of mice: C57Bl6, meaning that “The findings of Seok et al. are solely applicable to the B6 strain of mice in the three models of inflammation they tested. They unduly generalize these findings to mouse models of inflammation in general. [8]“

It is true that animal studies, including rodent studies, have their limitations. But what are the alternatives? In vitro studies are often even more artificial, and direct clinical testing of new compounds in humans is not ethical.

Obviously, the final proof of effectiveness and safety of new treatments can only be established in human trials. No one will question that.

A lot can be said about why animal studies often fail to directly translate to the clinic [15]. Clinical disparities between the animal models and the clinical trials testing the treatment (like in sepsis) are one reason. Other important reasons may be methodological flaws in animal studies (i.e. no randomization, wrong statistics) and publication bias: non-publication of “negative” results appears to be prevalent in laboratory animal research.[15-16]. Despite their shortcomings, animal studies and in vitro studies offer a way to examine certain aspects of a process, disease or treatment.

In summary, this study confirms that the existing (C57Bl6) mouse model doesn’t resemble the human situation in the systemic response following acute traumatic injury or sepsis: the genomic response is entirely different, in magnitude, duration and types of changes in expression.

The findings are not new: the shortcomings of the mouse model(s) were long known. It remains enigmatic why the researchers chose only one inbred strain of mice, and of all mice only the B6-strain, which is less sensitive to endotoxin, and only develop acute kidney injury (part of organ failure) at old age (young mice were used) [21]. In this paper from 2009 (!) various reasons are given why the animal models didn’t properly mimic the human disease and how this can be improved. The authors stress that:

the genetically heterogeneous human population should be more accurately represented by outbred mice, reducing the bias found in inbred strains that might contain or lack recessive disease susceptibility loci, depending on selective pressures.” 

Both Bill Barrington [8] and Mark Wanner [18,19] propose the use of “diversity outbred cross or collaborative cross mice that  provide additional diversity.” Indeed, “replicating genetic heterogeneity and critical clinical risk factors such as advanced age and comorbid conditions (..) led to improved models of sepsis and sepsis-induced AKI (acute kidney injury). 

The authors of the PNAS paper suggest that genomic analysis can aid further in revealing which genes play a role in the perturbed immune response in acute inflammation, but it remains to be seen whether this will ultimately lead to effective treatments of sepsis and other forms of acute inflammation.

It also remains to be seen whether comprehensive genomic characterization will be useful in other disease models. The authors suggest for instance,  that genetic profiling may serve as a guide to develop animal models. A shotgun analyses of gene expression of thousands of genes was useful in the present situation, because “the severe inflammatory stress produced a genomic storm affecting all major cellular functions and pathways in humans which led to sufficient perturbations to allow comparisons between the genes in the human conditions and their analogs in the murine models”. But rough analysis of overall expression profiles may give little insight in the usefulness of other animal models, where genetic responses are more subtle.

And predicting what will happen is far less easy that to confirm what is already known….

NOTE: as said the coverage in news and blogs is again quite biased. The conclusion of a generally good Dutch science  news site (the headline and lead suggested that animal models of immune diseases are crap [6]) was adapted after a critical discussion at Twitter (see here and here), and a link was added to this blog post). I wished this occurred more often….
In my opinion the most balanced summaries can be found at the science-based blogs: ScienceBased Medicine [11] and NIH’s Director’s Blog [17], whereas “Understand Nutrition” [8] has an original point of view, which is further elaborated by Mark Wanner at Speaking of Research [19] and Genetics and your health Blog [20]

References

  1. Seok, J., Warren, H., Cuenca, A., Mindrinos, M., Baker, H., Xu, W., Richards, D., McDonald-Smith, G., Gao, H., Hennessy, L., Finnerty, C., Lopez, C., Honari, S., Moore, E., Minei, J., Cuschieri, J., Bankey, P., Johnson, J., Sperry, J., Nathens, A., Billiar, T., West, M., Jeschke, M., Klein, M., Gamelli, R., Gibran, N., Brownstein, B., Miller-Graziano, C., Calvano, S., Mason, P., Cobb, J., Rahme, L., Lowry, S., Maier, R., Moldawer, L., Herndon, D., Davis, R., Xiao, W., Tompkins, R., , ., Abouhamze, A., Balis, U., Camp, D., De, A., Harbrecht, B., Hayden, D., Kaushal, A., O’Keefe, G., Kotz, K., Qian, W., Schoenfeld, D., Shapiro, M., Silver, G., Smith, R., Storey, J., Tibshirani, R., Toner, M., Wilhelmy, J., Wispelwey, B., & Wong, W. (2013). Genomic responses in mouse models poorly mimic human inflammatory diseases Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1222878110
  2. Drug Testing In Mice May Be a Waste of Time, Researchers Warn 2013-02-12 (science.slashdot.org)
  3. Susan M Love We are not mice 2013-02-14 (Huffingtonpost.com)
  4. Elbert Chu  This Is Why It’s A Mistake To Cure Mice Instead Of Humans 2012-12-20(richarddawkins.net)
  5. Derek Low. Mouse Models of Inflammation Are Basically Worthless. Now We Know. 2013-02-12 (pipeline.corante.com)
  6. Elmar Veerman. Waardeloos onderzoek. Proeven met muizen zeggen vrijwel niets over ontstekingen bij mensen. 2013-02-12 (wetenschap24.nl)
  7. Gina Kolata. Mice Fall Short as Test Subjects for Humans’ Deadly Ills. 2013-02-12 (nytimes.com)

  8. Bill Barrington. Are Mice Reliable Models for Human Disease Studies? 2013-02-14 (understandnutrition.com)
  9. Raven, K. (2012). Rodent models of sepsis found shockingly lacking Nature Medicine, 18 (7), 998-998 DOI: 10.1038/nm0712-998a
  10. Nemzek JA, Hugunin KM, & Opp MR (2008). Modeling sepsis in the laboratory: merging sound science with animal well-being. Comparative medicine, 58 (2), 120-8 PMID: 18524169
  11. Steven Novella. Mouse Model of Sepsis Challenged 2013-02-13 (http://www.sciencebasedmedicine.org/index.php/mouse-model-of-sepsis-challenged/)
  12. Wiersinga WJ (2011). Current insights in sepsis: from pathogenesis to new treatment targets. Current opinion in critical care, 17 (5), 480-6 PMID: 21900767
  13. Khamsi R (2012). Execution of sepsis trials needs an overhaul, experts say. Nature medicine, 18 (7), 998-9 PMID: 22772540
  14. Hotchkiss RS, Coopersmith CM, McDunn JE, & Ferguson TA (2009). The sepsis seesaw: tilting toward immunosuppression. Nature medicine, 15 (5), 496-7 PMID: 19424209
  15. van der Worp, H., Howells, D., Sena, E., Porritt, M., Rewell, S., O’Collins, V., & Macleod, M. (2010). Can Animal Models of Disease Reliably Inform Human Studies? PLoS Medicine, 7 (3) DOI: 10.1371/journal.pmed.1000245
  16. ter Riet, G., Korevaar, D., Leenaars, M., Sterk, P., Van Noorden, C., Bouter, L., Lutter, R., Elferink, R., & Hooft, L. (2012). Publication Bias in Laboratory Animal Research: A Survey on Magnitude, Drivers, Consequences and Potential Solutions PLoS ONE, 7 (9) DOI: 10.1371/journal.pone.0043404
  17. Dr. Francis Collins. Of Mice, Men and Medicine 2013-02-19 (directorsblog.nih.gov)
  18. Tom/ Mark Wanner Why mice may succeed in research when a single mouse falls short (2013-02-15) (speakingofresearch.com) [repost, with introduction]
  19. Mark Wanner Why mice may succeed in research when a single mouse falls short (2013-02-13/) (http://community.jax.org) %5Boriginal post]
  20. Warren, H. (2009). Editorial: Mouse models to study sepsis syndrome in humans Journal of Leukocyte Biology, 86 (2), 199-201 DOI: 10.1189/jlb.0309210
  21. Doi, K., Leelahavanichkul, A., Yuen, P., & Star, R. (2009). Animal models of sepsis and sepsis-induced kidney injury Journal of Clinical Investigation, 119 (10), 2868-2878 DOI: 10.1172/JCI39421




Kaleidoscope 2009 wk 47

19 11 2009

3621322354_4bc3bb115e

Kaleidoscope is a new series, with a “kaleidoscope” of facts, findings, views and news gathered over the last 1-2 weeks.

Most items originate from Twitter, my Google Reader (RSS) and sometimes real articles (yeah!).

I read a lot, I bookmark a lot, but only some of those things end op in a post. Since tweets have a half-life of less than a week, I thought it would be nice to safeguard some of the tweets in a post. For me to keep, for you to read.

I don’t have the time and the discipline to post daily about health news and social media as Ves Dimov does. It looks more like the compilation at blogs of dr Shock’s (see example),  dr Bates shout-outs, Health Highlights of Highlight HEALTH and Rachel Walden’s Womens health News Round-ups, but less on one subject and less structured. It will just be a mix of old and new, Social Media and science, just a kaleidoscope. Or a potpourri  if you like.

I don’t know if this kaleidoscope will live a long live. I already wrote 2 3 4 5 6 editions, but didn’t have the time to finish them. Well, we will see, just enjoy this one.

Ooh and the beautiful kaleidoscope is made by RevBean and is called: Eyeballs divide like cells. Looks very much like the eyeball-bubblewrap of a previous post but that is thus coincidence. Here is the link (Flickr, CC)

3621322354_4bc3bb115e

Medical Grand Rounds

Louise Norris at Colorado Health Insurance Insider is this week’s host of Grand Rounds.(see here). There are many interesting posts again. As a mother of two teens I especially liked the insight Nancy Brown of Teen Health 411 brings us into what teens want when it comes to their relationships with their parents and the “would you rather…?” story that Amy Tenderich of Diabetes Mine shares with us. The punch line is great. Her 9 year old melts my heart.

At InsureBlog’s Hank Stern brings us an article about a British hospital that will no longer admit expectant mothers with a BMI of more than 34, because the hospital’s labor and delivery unit is not equipped to handle complicated births. Hank concludes: “Fear not, though, portly preggies have to travel but 20 miles to the next closest facility. Assuming, of course, that they can make it that far when contractions are minutes apart.”

Dr Charles of the The Examining Room wrote an in depth article about a cheerleader who was supposedly stricken with dystonia following a seasonal flu vaccine in August. Dr Charles not only highlights why (specialists) think it is not dystonia, but gives also background information about the efficacy of vaccins.

Recent editions of the Grand Rounds were at CREGRL, flight nurse (link), NonClinicalJobs (link) and Codeblog, tales of a nurse (link). You can always find previous and upcoming hosts at the Grand Rounds Archive at Blogborygmi.

3621322354_4bc3bb115e Breast cancer screening

The update of the 2002 USPSTF recommendation statement on screening for breast cancer in the general population, published in the November issue of The Annals of Internal Medicine has led to heated discussions in the mainstream media (i.e. New York Times and MedPage Today). Based on current evidence, partly based on 2 other articles in the same journal (comparison screening schedules and an systematic review) the guidelines advise scaling back of the screening. The USPSTF recommends:

  • against routine screening mammography in women aged 40 to 49 years
  • against routine screening mammography of women 75 years or older.
  • biennial (instead of annual) screening mammography for women between the ages of 50 and 74 years.
  • against teaching breast self-examination (BSE).
  • against either digital mammography or magnetic resonance imaging (MRI) instead of film mammography as screening modalities.

The two articles published in Ann Intern Med add to the evidence that the propagation of breast cancer self exam doesn’t save lives (see Cochrane review discussed in a previous post) and that the benefits of routine mammography in the young (<50) or old (>75) do not outweigh the harm (also covered by a  Cochrane review before). Indeed, as put forward by Gary Schwitzer at Schwitzer health news blog this is NOT a new debate. He refers to Slate who republishes a five-year old piece of Amanda Schaffer that does a good job of explaining the potential harms of screening. However it is difficult for women (and some doctors) to understand that “When it comes to cancer screening, more isn’t always better.” Indeed -as Kevin Pho at Kevin MD states, the question is whether “patients will accept the new, evidence-based, breast cancer screening guidelines”.

In the Netherlands it is already practice to start biannual routine mammography at the age of 50. The official breast cancer screening site of the RIVM even states that the US is now going to follow the Dutch guidelines ;) (one of assessed guidelines in one the Ann Intern Med papers is Dutch). But people still find the  long established guidelines difficult to accept: coincidentally I saw tweets today asking to sign a petition to advance the age of screening ‘because breast cancer is more and more frequently observed at young age…(??)’ Young, well educated, women are very willing to sign…

No time to read the full articles, but interested to know more, then listen to the podcast of this Ann Intern Med edition:


3621322354_4bc3bb115e

Systematic Reviews, pharma sponsored trials and other publishing news

Cochrane reviews are regarded as scientifically rigorous, yet a review’s time to publication can be affected by factors such as the statistical significance of the findings. A study published in Open Medicine examined the factors associated with the time to publication of Cochrane reviews. A change in authors and updated reviews were predictive factors, but the favorability of the results was not.

Roy Poses of the Health Care Renewal Blog starts this blogpost as follows: “Woe to those of us who have been advocates for evidence-based medicine”. He mainly refers to a study published in the NEJM, that identified selective outcome reporting for trials of off-label use of gabapentin: for 8 of the 12 published trials, there was a disagreement between the definition of the primary outcome in the protocol and that in the published report. This seriously threatens the validity of evidence for the effectiveness of off-label interventions. Roy was surprised that the article didn’t generate much media attention. The reason may be that we have been overwhelmed by manipulation of data, ghostwriting and by the fact that pharma-sponsored trials rarely produce results that are unfavorable to the companies’ product (see previous posts about Ghostwriting (Merck/Elsevier, Conflict of Interest in Cancer Studies and David Tovey about Cochrane Reviews). At least two authors of the NEJM review (Bero and Dickersin) have repeatedly this to be the case [e.g. see here for an overview, and papers of Lisa Bero]. It is some relief that at least 3 of the 4 NEJM authors are also members of the Cochrane Collaboration. Indirectly better control of reporting, i.e. by clinical trials registries, can improve the reliability of pharma sponsored trials and thus systematic reviews summarizing them. As a matter of fact Cochrane authors always have to check these registries.

At Highlight Health Walter Jessen writes about Medical Journal Conflict of Interest Disclosure and Other Issues, which also discusses how money can taint objectivity in scientific publishing. Half of the post discusses the book The Trouble with Medical Journals, written in 2007 by Richard Smith, the former editor of the BMJ.
By the way, Walter just hosted MedLibs Round with the theme “Finding Credible Health Information Online”.

Good news in the Netherlands: right after international Open Access week and the launching of the Dutch Open Access website (www.openaccess.nl), the Netherlands Organization for Scientific Research (NWO) has announced that it is in favor of Open Access. (via PLOS-facebook).

The open access nature of PLOS itself gets out of hand: they even peer-review T-shirts (according to Bora Zivkovic of a Blog around the Clock, see here)

3621322354_4bc3bb115e

Other Health & Science News:

Medline Plus summarizes an article in the Journal of Nutrition, that states that Selenium supplements, may pose a heart risk.

Even Folic Acid and vitamin B12, when taken in large doses, have been reported to Increase Cancer Risk (WebMD)

Luckily WebMD also reports that dark chocolate seems to help against stress, that is it reduced stress hormones in the blood. However @evidencematters and @NHSChoices cast doubt on that“Chocolate cuts stress, says newspaper. Does the study really say that? And who paid for the study?…”

Scientists made the unexpected discovery (published in Molecular Cell) that BRAF, which is linked to around 70 per cent of melanomas and seven per cent of all cancers, is in fact controlled by a gene from the same RAF family called CRAF – which has also been linked to the disease. For the first time it is shown “how two genes from the same ‘family’ can interact with each other to stop cancer in its tracks” (Source: Info Cancer Research UK)

For the first time, scientists have successfully used exome sequencing to quickly discover a previously unknown gene responsible for Miller syndrome, a rare disorder. The finding demonstrates the usefulness of exome sequencing in studying rare genetic disorders. The exome is enriched for coding (thus functional) DNA, it is only 1% of the total DNA, but contains 85% of the mutations (Published in , source: PhysOrg.com)

3621322354_4bc3bb115e

Web 2.0
For information regarding the FDA hearings on internet and social media see #FDASM: http://www.fdasm.com.

Read Write Web summarizes the new numbers released by analytics firm Postrank that indicate that reader engagement with blogs has changed dramatically over the last three years, primarily because of the rise of online social networks.

Twitter has began to relaunch the new retweet feature, although not without controversy. What do you think about the newest feature?

The Next Web gives an overview of which Twitter application is hot and which is not.

And Finally: Top 100 tools for learning, compiled by Jane Hart from the contributions of 278 learning professionals worldwide. You can see the lists here (HT: http://blogs.netedu.info/?p=1005)

The web 2.0 part is relatively short, but it is time to conclude this edition. Till next time!

  • MEDLIB’s ROUND 1.6 (laikaspoetnik.wordpress.com)
  • Tool Talk: quick links re Facebook, GReader and GWave (socialfish.org)
  • Reblog this post [with Zemanta]




    Gene Genie #44

    24 03 2009

    genegenie_logoThe latest issue of Gene Genie (nr 44) is now up at Mary Meets Dolly. Please enjoy reading the posts here

    Gene genie is the “blog carnival of genes and genetic conditions“, initiated and maintained by Bertalan Mesko of Scienceroll.

    You can subcribe to Gene Genie by email or RSS feed and as you may know there is also an aggregated feed of credible, rotating health and medicine blog carnivals available (which contains the Grand Round (due today) and the Medlib’s Round as well).

    Please mail Bertalan if you want to contribute to the next carnival as a writer or a host (berci.mesko at gmail.com).









    Follow

    Get every new post delivered to your Inbox.

    Join 607 other followers