Abstract :
[en] Matrix metalloproteinases (MMPs) recently appeared as key regulators of inflammation,
allowing recruitment and clearance of inflammatory cells and modifying the biological activity
of many peptidic mediators by cleavage. MMP-19 is a newly described MMP and preferentially
cleaves matrix proteins such as collagens and tenascin-C. The role of MMP-19 in asthma has not
been described to date. The purpose of the present study was to assess MMP-19 expression in a
murine asthma model and to address biological effects of MMP-19 deficiency in mice. Allergenexposed
wild-type (WT) mice displayed an increased expression of MMP-19 mRNA and an
increased number of MMP-19-positive cells in the lungs detected by immunohistochemistry.
After allergen challenge of MMP-19 knockout (MMP-19-/-) mice, an exacerbated eosinophilic
inflammation was detected in bronchoalveolar lavage fluid and bronchial tissue along with an
increased airway responsiveness to methacholine. A shift towards increased Th2-driven
inflammation in MMP-19-/- mice was demonstrated by 1) increased numbers of cells expressing
the IL-33 receptor T1/ST2 in lung parenchyma, 2) increased IgG1 levels in serum and 3) higher
levels of IL-13 and CCL11 in lung extracts. Tenascin-C was found accumulated in peribronchial
areas of MMP-19-/- after allergen challenges as assessed by Western blot and
immunohistochemistry analysis. We conclude that MMP-19 is a new mediator in asthma,
preventing tenascin-C accumulation and directly or indirectly controlling Th2-driven airway
eosinophilia and airway hyperreactivity. Our data suggest that MMP-19 might act on Th2
inflammation homeostasis through preventing tenascin protein accumulation.
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