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  • Title: Interferon alpha2b increases paracellular permeability of renal proximal tubular LLC-PK1 cells via a mitogen activated protein kinase signaling pathway.
    Author: Lechner J, Pfaller W.
    Journal: Ren Fail; 2001; 23(3-4):573-88. PubMed ID: 11499571.
    Abstract:
    The therapeutic administration of Interferon alpha2b (IFNalpha) is often accompanied by impaired renal function, i.e. reduced glomerular filtration rate and sometimes a so-called "capillary leak syndrome". To clarify the mechanism behind the renal dysfunction, confluent monolayers of LLC-PK1 cells were used as a model system to analyze the effects of IFNalpha on renal tubular epithelium. Examination of epithelial barrier function via measurement of transepithelial resistance (TER) revealed a dose dependent increase in paracellular permeability by IFNalpha treatment. The effect was reversible upon removal of IFNalpha at doses up to 5 x 10(3) U/mL. Apical or basolateral application of IFNalpha yielded the same decrease in TER. Tyrphostin A25, an inhibitor of phosphotyrosine kinases, ameliorated the IFNalpha induced decrease of TER. In order to unravel intracellular signal transduction pathways that may mediate IFNalpha induced changes of epithelial barrier function, we inhibited IFNalpha signaling through a mitogen activated protein kinase pathway by the Mek1 inhibitor PD98059. The inhibitor could be shown to prevent IFNalpha induced decrease of transepithelial resistance. Inhibitors of the p38 mitogen activated protein kinase pathway did not affect IFNalpha mediated changes of epithelial barrier function, indicating a highly specific role for the Mek/Erk pathway. Activation of mitogen activated protein kinase pathways by epidermal growth factor or anisomycin could not, per se, imitate the effect of IFNalpha on the paracellular permeability of LLC-PK1 monolayers. These findings provide evidence that IFNalpha can affect barrier function in renal epithelial cells via activation of the Mek/Erk pathway.
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