Airway epithelial cells are known to produce a granulocyte/macrophage colony-stimulating factor (GM-CSF), which induces eosinophilic inflammation in bronchial asthma. Interleukin-4 (IL-4), IL-10, and IL-13 produced by Th2 cells are involved in the pathogenesis of bronchial asthma. To assess their contributions to airway inflammation, we examined their effects on GM-CSF production by bronchial epithelial cells. Human bronchial epithelial cells were obtained under bronchoscopy from 21 patients with various respiratory diseases and incubated with or without IL-4, IL-10, or IL-13. Then the GM-CSF concentrations in the cell-free supernatants were measured by enzyme-linked immunosorbent assay. Results showed that IL-4 and IL-13 stimulated GM-CSF production by the epithelial cells dose-dependently, whereas IL-10 did not. The eosinophil survival-stimulating activity in the culture supernatants was closely correlated with GM-CSF concentration and was neutralized by anti-GM-CSF antibody. Thus, IL-4 and IL-13 may contribute to airway inflammation by upregulating GM-CSF production by bronchial epithelial cells.
SUMMARYThe induction of immunoregulatory cytokines IL-1 , IL-6, IL-12, tumour necrosis factor-alpha (TNF-) and interferon-gamma (IFN-) was studied with neonatal (cord blood) monocyte-derived macrophages (MDM) after in vitro infection with respiratory syncytial virus (RSV). The expression of mRNAs for these cytokines in RSV-infected MDM was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). The activities of these cytokines were assayed by ELISA. Significant increase of expression of mRNA for IL-6, IL-12, TNF-and IFN-occurred within 2 h after infection and decreased within 6 h after infection. At 20 h after infection the MDM produced and secreted moderate levels of IL-6 and TNF-; however, no IL-12 and IFN-activities were detected. Moderate IL-1 mRNA was expressed before RSV infection, and its expression increased at 2 h after infection. However, no detectable IL-1 was secreted in culture fluids. These observations suggest that RSVinfected neonatal macrophages produce and secrete IL-6 and TNF-quickly during the eclipse phase of RSV infection and therefore may play a prominent role in the initiation of the immune response to RSV.
The production of IL-6 and TNF-alpha and the expression of their mRNA were studied with neonatal (cord blood) and adult blood monocyte-derived macrophages (MDM) after in vitro infection with respiratory syncytial virus (RSV). Cord blood MDM exhibited production of high levels of IL-6 within 24 hr after infection. Little or no IL-6 production was detected after 24-48 hr and after in vitro stimulation with inactivated (nonreplicating) virus. Adult blood MDM also produced high levels of IL-6 within 24 hr of RSV infection. Unlike cord blood MDM, adult MDM demonstrated significant activity of IL-6 after 24 hr of infection with live RSV and after exposure to the inactivated virus. The pattern of TNF-alpha production by cord and adult blood MDM after live RSV infection resembled closely the pattern of IL-6 production. Both cell types produced TNF-alpha in the first 24 hr after infection. However, little or no production was observed after 24 hr of infection and after exposure to the inactivated virus. The profile of mRNA expression was similar to the production of IL-6 or TNF-alpha. mRNA expression occurred over a shorter period in cord blood MDM. These observations suggest that inflammatory and immunoregulatory cytokines, such as IL-6 and TNF-alpha, are produced by neonatal as well as previously primed adult macrophages. However, neonatal cells may be less efficient in inducing IL-6 production.
The production of IL-6 and TNF-alpha and the expression of their mRNA were studied with neonatal (cord blood) and adult blood monocyte-derived macrophages (MDM) after in vitro infection with respiratory syncytial virus (RSV). Cord blood MDM exhibited production of high levels of IL-6 within 24 hr after infection. Little or no IL-6 production was detected after 24-48 hr and after in vitro stimulation with inactivated (nonreplicating) virus. Adult blood MDM also produced high levels of IL-6 within 24 hr of RSV infection. Unlike cord blood MDM, adult MDM demonstrated significant activity of IL-6 after 24 hr of infection with live RSV and after exposure to the inactivated virus. The pattern of TNF-alpha production by cord and adult blood MDM after live RSV infection resembled closely the pattern of IL-6 production. Both cell types produced TNF-alpha in the first 24 hr after infection. However, little or no production was observed after 24 hr of infection and after exposure to the inactivated virus. The profile of mRNA expression was similar to the production of IL-6 or TNF-alpha. mRNA expression occurred over a shorter period in cord blood MDM. These observations suggest that inflammatory and immunoregulatory cytokines, such as IL-6 and TNF-alpha, are produced by neonatal as well as previously primed adult macrophages. However, neonatal cells may be less efficient in inducing IL-6 production.
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