Involvement of galectin-9 in guinea pig allergic airway inflammation

Background: There is little information about the involvement of galectin-9 (Gal-9) in allergic inflammation. Thus, we investigated the role of Gal-9 in asthma model guinea pigs. Methods: Airway resistance (R_aw) was measured using a double-flow plethysmograph system. Gal-9 expression in the lung was assessed by Western blot and immunohistochemistry. Eosinophil chemotactic activity was evaluated in a chamber containing a polyvinylpyrolidone-free membrane. Cell apoptosis was analyzed on a flowcytometry with propidium iodide. Results: In cloning guinea pig Gal-9 we identified three isoforms that differ only in the length of their linker peptides, just as with human Gal-9. Guinea pig Gal-9 was found to be a chemoattractant for eosinophils and to promote induction of apoptosis in sensitized but not non-sensitized T lymphocytes. In allergic airway hypersensitivity model, a low level of Gal-9 expression was observed in the nonsensitized/nonchallenged group, but upregulation was detected at 7 h after challenge and sustained up to 24 h. Such upregulation correlated with elevation of eosinophil peroxidase activity but not with increased R _aw. Conclusions: The present results provide evidence that Gal-9 is not involved in airway hypersensitivity, but is partly involved in prolonged eosinophil accumulation in the lung.