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목적 : The spontaneous signal transducer and activator of transcription (STAT)6 phosphorylation and the following specific gene expression of the host cells are major strategy for the survival of the intracellular Toxoplasma gondii against the parasiticidal events through the STAT1 phosphorylation by the provoked interferon-gamma in the infection. We examined to find out the effect of several tyrosine kinase inhibitors (TKIs) on the growth inhibition of intracellular T. gondii and the relationship with STAT1 and 6 phosphorylation in the retinal pigment epithelial cell line, ARPE-19.
방법 : We counted the number of T. gondii per parasitophorous vacuolar membrane (PVM) after the treatment with several TKIs within the RPE host cells at 12-hr interval for 72 hrs. In addition, the inhibition of phosphorylation of STAT6 after treatment was checked in the western blot and immunofluorescence assay.
결과 : Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, 5 uM) inhibits the growth of T. gondii of 98.0%, which is comparable to pyrimethamine (5 uM) of 96.9%, and followed by Erlotinib (ErbB1/EGFR inhibitor, 20 uM) of 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, 10 uM) of 21.3% in the counting number of T. gondii per PVM within the host cells. In early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibits the spontaneous phosphorylation of STAT6 in the western blot and immunofluorescence assay, but still the STAT1 phosphorylation is not affected by interferon-gamma stimulation. On the while, Jak1/Jak3, the upper hierarchical kinase of the cytokine signaling, are strongly phosphorylated at 2 hr and then disappear entirely after 4 hr.
결론 : Some TKIs, especially EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of direct phosphorylation of STAT6 by T. gondii itself.
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