NEW YORK (Reuters Health) Jul 11 - A single paramyxoviral infection in
mice results in airway hyperreactivity and goblet cell hyperplasia
that persists for a year after the virus has been cleared, according
to the report in the July 15th issue of The Journal of Clinical
Investigation.
"While the allergic response may increase during an asthma attack,
our research suggests that the antiviral response also increases,"
coauthor Dr. Michael J. Holtzman said in a press statement. "We think
that a virus in infancy or childhood creates a hit-and-run effect,
where a brief infection causes permanent changes in the body's
antiviral system."
To test their theory, Dr. Holtzman and colleagues from Washington
University School of Medicine, St. Louis, performed experiments in
same strain wild-type and intercellular adhesion molecule-1
(ICAM-1)-null mice exposed to a paramyxoviral infection.
Despite similar infection rates in both strains of mice, as
expected, during the acute phase of infection the ICAM-1-null mice
were protected from airway inflammation and hyperreactivity.
However, the chronic response to the infection persisted in both
wild-type and ICAM-1 deficient mice, the researchers found. By 11
weeks after infection, both strains of mice reached the same levels of
airway hyperreactivity and goblet cell hyperplasia, the investigators
note.
This response was not associated with a deficiency in
interferon-gamma, and the chronic response was partially mitigated by
glucocorticoid treatment, they add. Dr. Holtzman's team also found
that in uninfected mice, allergen challenge produced expression of the
asthma phenotype only in the short-term.
Dr. Holtzman said that "our findings raise the possibility that
asthma not only resembles a persistent antiviral response but may
actually be caused by one. These results in mice provide a further
basis for determining exactly how similar events may develop in
children and adults with asthma."
J Clin Invest 2002;110:165-175.
