Respiratory syncytial virus-induced airway hyperresponsiveness is independent of IL-13 compared with that induced by allergen.
BACKGROUND
IL-13 is a central mediator of allergen-induced airway hyperresponsiveness (AHR), but its role in respiratory syncytial virus (RSV)-induced AHR is not defined. The combination of allergen exposure and RSV infection is known to increase AHR and lung inflammation, but whether IL-13 regulates this increase is similarly not known.


OBJECTIVE
Our objective was to determine the role of RSV infection and IL-13 on airway responsiveness and lung inflammation on sensitized and challenged mice.


METHODS
Using a murine model of RSV infection and allergen exposure, we examined the role of IL-13 in the development of AHR and lung inflammation in IL-13 knockout mice, as well as using a potent IL-13 inhibitor (IL-13i). Mice were sensitized and challenged to allergen, and 6 days after the last challenge, they were infected with RSV. IL-13 was inhibited using an IL-13 receptor alpha(2)-human IgG fusion protein. AHR to inhaled methacholine was measured 6 days after infection, as was bronchoalveolar lavage fluid and lung inflammatory and cytokine responses.


RESULTS
RSV-induced AHR was unaffected by the IL-13i, despite prevention of goblet cell hyperplasia. Similar results were seen in IL-13-deficient mice. In sensitized and challenged mice, RSV infection significantly increased AHR, and after IL-13i treatment, AHR was significantly reduced, but to the levels seen in RSV-infected mice alone.


CONCLUSIONS
These results indicate that despite some similarities, the mechanisms leading to AHR induced by RSV are different from those that follow allergen sensitization and challenge. Because IL-13 inhibition is effective in preventing the increases in AHR and mucus production in sensitized and challenged mice infected with RSV, IL-13i could play an important role in preventing the consequences of viral infection in patients with allergic asthma.
Park
Jung Won
JW
Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA.
Taube
Christian
C
Yang
Eun Seok
ES
Joetham
Anthony
A
Balhorn
Annette
A
Takeda
Katsuyuki
K
Miyahara
Nobuaki
N
Dakhama
Azzeddine
A
Donaldson
Debra D
DD
Gelfand
Erwin W
EW
D000485:Allergens / Q000276:immunology*; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000209:etiology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D018793:Interleukin-13 / Q000096:biosynthesis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology* / Q000821:virology; D018113:Respiratory Syncytial Virus, Human / Q000472:pathogenicity*
D000485:Allergens; D016207:Cytokines; D018793:Interleukin-13; D010047:Ovalbumin