Dr. Casola is interested in mechanisms of induction of pro-inflammatory genes during viral infections that could be targeted to develop novel approaches for modulation of both inflammatory and immune responses in vivo. RSV is the most common cause of epidemic respiratory disease in children. The inflammatory response, triggered by the infection of respiratory epithelial cells, is an essential pathogenic component of RSV disease. Interleukin 8 (IL-8) is a CXC chemokine detected in high concentrations in the nasal and bronchoalveolar lavages of RSV-infected children that could play a role in the recruitment of inflammatory cells to the lung following RSV infection. RSV replication in airway epithelial cells in vitro results in increased IL-8 gene expression and nuclear factor kappa B (NF-kB) activation. This project will pursue the hypothesis that RSV induces IL-8 gene expression partially through the activation of the mitogen-activated protein kinase (MAPK) cascade. Stimulation of MAPK extracellular regulated kinase (ERK1/2) and p38 results in activation of transcription factors that regulate IL-8 gene transcription.
Three aims are designed to test the hypothesis. First, she will investigate the activation of Raf-mitogen activated extracellular regulated kinase (MEK)-ERK pathway in RSV infection and its role in RSV-induced secretion of IL-8. The mechanism(s) of ERK1/2 activation will be determined by evaluating the kinase activity of the upstream molecule Raf and the role of each individual kinase in IL-8 gene induction, in transcription factor activation and in IL-8 protein synthesis by overexpression of dominant negative mutants or by down regulation with antisense oligonucleotides. Secondly, she will investigate the activation of the MAP kinase p38 and c-JUN-N-terminal kinase (JNK) in RSV infection and their role in RSV-induced secretion of IL-8. A similar approach as in Aim 1 will be used to establish the role of these two branches of the MAPK cascade in RSV-induced IL-8 production. Finally, she will focus on establishing the role of the MAPK cascade in a stimulus-specific mechanism of NF-kB activation by RSV infection and tumor necrosis factor (TNF) stimulation, the induction of different post-translational modifications of NF-kB and whether the recruitment of co-activators to the IL-8 promoter, and the role of MAPK cascade in these processes will be investigated. These studies may identify intracellular signaling pathways involved in the viral-induced chemokine IL-8 production that could be used to develop new therapeutic strategies useful in the treatment of acute lung inflammation and post-infectious asthma.
