Research of sphingosine kinase modification in acute lung injury

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The metabolism of sphingosine kinase (SPHK)/sphingosine 1-phosphate (SIP) system in lung diseases has been reported recently. In this project, we focused on the role of SPHK in lung epithelial cells and fibroblasts in injured lungs.1. We investigated the mechanism of myofibroblast differentiation in lung fibroblasts of acute lung injury. Bleomycin treatment increased SPHK expression and fibrotic changes in injured lungs. Our study reported that TGF-beta treatment increased SPHK1 activation in lung fibroblasts. S1P produced by SPHK1 induced the transactivation of S1P receptors and recruitment of activated RhoA. This data was accepted in Am J Respir Cell Mol Biol in 2007.2. Using mouse asthmatic model, we examined whether the effect of SPHK inhibitors attenuates airway inflammation. The inhalation of SPHK inhibitors by nebulizing maneuver showed significant decrease of airway hyperresponsiveness and eosinophilic inflammation induced by ovalbumin treatment, whereas intravenous delivery showed limited effects. Our data indicated that intratracheal treatment of SPHK inhibitor may be one of therapeutic approach for lung inflammation. This data was accepted in Am J Physiol Lung Cell Mol Physiol in 2008.3. In this animal model, we found that SPHK activity was increased in bronchial epithelial areas in asthmatic lungs. Then we examined the function of SPHK in goblet cell formation around epithelial walls. In vitro studies using airway liquid interface demonstrated that SPHK was activated and played a pivotal role in cell changes by IL-13 treatment. This data will be exhibited in American Thoracic Society in 2008. Thus, our studies clarified that SPHK works for morphological cell changes in lung inflammation.