Recently, researchers at University of Iowa Health Care discovered a link between chronic heavy alcohol use and influenza virus infection in mice. David Meyerholz, DVM, PhD, an assistant professor, Department of Pathology, and co-author of the study, talks about the study and how it may relate to us.
How was the study involving alcohol use and the immune system set up?
We used an established alcohol model to study the immune system. Mice were acclimated to drinking water that was progressively supplemented with alcohol to reach a final concentration of approximately 20 percent. After four weeks, the mice were then challenged with influenza virus, and we observed them through the course of infection with special interest in days 4 and 5, as this is near the time point where the immune system of a healthy individual starts to control the virus.
What was considered “heavy alcohol use”?
In order to get a comparable model in humans, chronic alcohol abuse will typically produce changes in the immune system and enhance susceptibility of the disease. But this typically takes decades of abuse to occur. In the mouse model, we can get similar changes in the immune system over a shorter time span of only weeks and months. And in this model of heavy alcohol exposure, the equivalent for humans is about seven beers or seven glasses of wine per day for the average-sized individual.
What was the result of the study?
What we found was that the chronic alcohol exposure led to more severe influenza disease. Essentially the alcohol exposed mice were sicker. And this was associated with more widespread and severe lung disease caused in part by the uncontrolled replication of the influenza virus. These results suggest that chronic and heavy alcohol ingestion inhibits the immune system from effectively controlling the virus and thus results in more severe disease.
Carrying those results into the human population – what would it suggest?
The apparent indication would be that alcoholics are more susceptible to influenza disease, and this is one of many reasons why alcohol abuse can be harmful, but further work is really needed to carry the results of this study to humans all the way. But it does open the door for some important questions that may need addressed, such as what is the best approach for prophylaxis or treatment of people in this high risk group during influenza season or during influenza outbreaks.
Why concentrate on influenza specifically?
Currently there’s a gap in our understanding on the affects of influenza infection in individuals with chronic alcohol abuse. In addition, influenza is a seasonal virus that Iowans, as well as people around the world, are annually exposed, and thus it’s a very relevant disease. And lastly, influenza’s a very timely topic, given all the recent public attention and concern over the potential of a future avian influenza, also known as H5N1, pandemic.
Would the study suggest a heavy alcohol user may also be susceptible to illnesses other than influenza?
Yes it does, and this work is really consistent with what scientists already know about the immune system in people who abuse alcohol is that it’s a weakened immune system, and they are more susceptible to various diseases. And this includes lung infections such as pneumonia and tuberculosis, and tuberculosis susceptibility has been known for almost a full century in alcoholics.
Will there be follow up studies on the immune system?
Our research group is focused and committed to understanding the effects of chronic and heavy ethanol ingestion on the immune system and we want to further define this deficiency that’s causing enhanced influenza infection. Our long-term goals are to define these mechanisms and hopefully devise novel therapies to mitigate these risk factors for influenza and other diseases. |
