In this study, we investigated the roles of CD4 T cell cytokines IL-17 and IL-17F in GM-CSF production from lung microvascular endothelial cells (LMVECs). While a wide range of doses of IL-17 or IL-17F alone did not induce GM-CSF release from LMVECs, IL-17 had an enhancing effect on macrophage-derived IL-1β- and TNF-α-induced GM-CSF mRNA expression and production, whereas IL-17F had an enhancing effect on IL-1β-induced GM-CSF production, but a marked inhibitory effect on TNF-α-induced secretion. GM-CSF production was further enhanced with the combination of three cytokines IL-1β, TNF-α and IL-17 or IL-17F. Additionally, when Th1 or Th2 cytokine was combined with IL-1β or TNF-α, both Th1 and Th2 cytokines had a modest stimulatory effect on TNF-α-induced GM-CSF production, whereas IL-4 and IFN-γ profoundly attenuated IL-1β-induced secretion. Moreover, the regulation by IL-17 plus Th1 or Th2 cytokine of GM-CSF production from LMVECs treated with IL-1β or TNF-α was dependent on the concentration of IL-17. Our findings indicate that IL-17 and IL-17F play a differential regulatory role in GM-CSF production by LMVECs stimulated with IL-1β and/or TNF-α, which is sensitive to Th1 and Th2 cytokine modulation.
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