Effect of montelukast on bacterial sinusitis in allergic mice.
BACKGROUND
In mice, allergic rhinitis augments the infectious and inflammatory response to Streptococcus pneumoniae-induced sinusitis.


OBJECTIVE
To investigate the effects of cysteinyl leukotriene antagonism on the severity of bacterial infection.


METHODS
We performed 3 parallel, placebo-controlled experiments. In the first, mice were ovalbumin sensitized and ovalbumin challenged to show the effects of montelukast on the allergic inflammation; in the second, we evaluated the effect of montelukast on S. pneumoniae infection; in the third, we used mice that were both allergic and infected. Montelukast was given starting 2 days after sensitization until the day before euthanasia. One day after drug treatment began, the mice were inoculated intranasally with S. pneumoniae in the infected groups. Nasal hypersensitivity was measured with histamine challenges before the first sensitization and on the day before euthanasia. On the fifth day after infection, mice were euthanized, nasal lavage was performed, bacteria were cultured, and inflammatory cells in the sinuses were quantified.


RESULTS
Mice that were infected only tended toward having increased bacterial counts from nasal lavage in the montelukast-treated group. The mice that were allergic and infected experienced significantly higher bacterial counts (P < .05). All 3 montelukast treatment groups had significantly decreased eosinophil counts as well as T-lymphocyte counts.


CONCLUSIONS
Montelukast reduces the manifestations of allergic rhinitis in mice. Surprisingly, montelukast led to an increase in bacterial growth in infected mice. This suggests an effect of the cysteinyl leukotrienes on the innate response to bacterial infection.
Khoury
Paneez
P
Department of Surgery, Section of Otolaryngology-Head and Neck Surgery, The University of Chicago, Illinois 60637, USA.
Baroody
Fuad M
FM
Klemens
James J
JJ
Thompson
Kenneth
K
Naclerio
Robert M
RM
D000085:Acetates / Q000627:therapeutic use*; D000818:Animals; D003521:Cyclopropanes; D005260:Female; D005434:Flow Cytometry; D006967:Hypersensitivity / Q000150:complications* / Q000188:drug therapy*; D020024:Leukotriene Antagonists / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D017817:Nasal Lavage Fluid / Q000166:cytology / Q000382:microbiology; D010047:Ovalbumin / Q000276:immunology; D011008:Pneumococcal Infections / Q000150:complications / Q000188:drug therapy / Q000276:immunology; D011804:Quinolines / Q000627:therapeutic use*; D012852:Sinusitis / Q000150:complications* / Q000188:drug therapy*; D013296:Streptococcus pneumoniae / Q000187:drug effects; D013440:Sulfides
D000085:Acetates; D003521:Cyclopropanes; D020024:Leukotriene Antagonists; D011804:Quinolines; D013440:Sulfides; D010047:Ovalbumin; C093875:montelukast