Cytokine Storm and Avian Influenza
In class, Dr. Cohen referenced the cytokine storm in association with Multiple Sclerosis on Tuesday [1]. Interestingly enough, cytokine storm is associated with many conditions.
The term “Cytokine Storm” has been used more or less romantically with regard to the hot topics of Emergency Preparedness in a Post 9/11 world. A particular scientist, Dr. Michael Osterholm (http://www.cidrap.umn.edu/),[1, 2] has been one of the loudest voices (many consider him quite controversial – Look at this clip from the Oprah Show - http://www2.oprah.com/tows/pastshows/200601/tows_past_20060124.jhtml) in putting the possible “natural” biological threats like Avian Influenza (H5N1) in the popular media.
Specifically, the threat from bird flu is considered different from the seasonal flu from public health standpoint, in part, because young, healthy individuals might be most at risk. The reason for this – the “Cytokine storm”. It is believed that healthy, young individuals could over respond immunologically. Typically, in the public health community, the oldest and youngest individuals are the target of influenza vaccine programs because they are considered most at risk for death from the seasonal influenza outbreaks. This release of literally hundreds of pro-inflammatory cytokines simultaneous could result in sepsis, or septic shock syndrome, and put younger individuals at most risk. (SSS) (http://www.cytokinestorm.com/). In addition, there is some evidence that inhibition of this response would not protect an individual from the lethality of the infection [3], that the H5N1 infection might have a dual mechanism for causing death.
There is some historical precedent and justification for this - the Spanish Flu of 1918. This world wide Pandemic from the Type A H5N1 Influenza strain resulted in an estimate in upwards of 50 million deaths worldwide. Younger individuals ( e.g. military men, college students, etc.) seemed to be disproportionately affected.
References
1. Link H. The cytokine storm in multiple sclerosis. Mult Scler 1998;4:12-5.
2. Osterholm MT. Preparing for the next pandemic. N Engl J Med 2005;352:1839-42.
3. Salomon R, Hoffmann E, Webster RG. Inhibition of the cytokine response does not protect against lethal H5N1 influenza infection. Proc Natl Acad Sci U S A 2007;104:12479-81.
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4 comments:
The Spanish Flu of 1918 was not H5N1, it was H1N1. Still severe, just as crappy.
http://en.wikipedia.org/wiki/Spanish_flu
This is interesting. From my understanding, one problem about treating Avian Influenza is that vaccines are developed in chicken eggs, however, Avian Influenza destroys the egg before a vaccine can be fully developed. Also, this would not be the first case where the host cytokines contributed to death. Hantavirus cause hantavirus cardiopulmonary syndrome (HCPS) which the host response of cytokines contribute to the illness (~30% leathal).
Schountz T. et al. Regulatory T cell-like responses in deer mice persistently infected with Sin Nombre virus. PNAS 2007 Sep 17; [Epub ahead of print]
My apologies for the inaccuracy - the neurimidase was of the same type, not the hemaglutinin.
I would like to see some sort of study that looked at the effect of antibiotics in drinking water on our imminent avian flu pandemic. While the main concern with having high levels of antibiotics in water is that they kill off the weak bacteria and leave resistant strains in their wake. Is it possible that we are inadvertently treating the birds that get the flu? Well not likely at the detected levels currently in our laves and rivers. I think it is more likely that we are babying the immune systems of young birds drinking the water. Now as to whether or not this increases the ability of the flu to spread or causes the flu to kill the birds so fast that they never come into contact with a human is up to speculation.
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