title: Interleukin-1-mediated H2O2 production by hepatic sinusoidal endothelium in response to B16 melanoma cell adhesion.
abstract: We have examined H2O2 production by in vitro enriched hepatic sinusoidal endothelium (HSE) during interleukin-1 beta (IL-1 beta) stimulation and B16 melanoma cell adhesion. Production of H2O2 was quantified by flow cytometry and multiwell plate-scanning fluorimetry of intracellular 2', 7'-dichlorofluorescein (DCFH) oxidation in HSE. Under IL-1 beta treatment there was a 6-fold increase in endothelial cells producing H2O2 (67%) and a 4-fold augmentation in the Kupffer cell population (86%). The average H2O2 content per cell size unit significantly (P < 0.01) increased in endothelial cells (2.6-fold) and Kupffer cells (1.7-fold). In contrast to the homogeneity of Kupffer cells, H2O2 production intensity was largely heterogeneous in IL-1 beta-activated HSE. Enhancement of H2O2 production by IL-beta-treated HSE started at the 4th h and peaked 2-3 h later. The addition of increasing concentration of IL-1 beta to HSE for 4 h caused the progressive activation of H2O2 production by treated cells. The addition of 80 M excess of IL-1 receptor antagonist (IL-1 Ra) 10 min before IL-1 beta treatment abrogated IL-1 beta-mediated enhancement of H2O2. From the 2nd h of B16 melanoma adhesion to HSE there was significantly (P < 0.05) enhancement of H2O2 content in HSE. This activation increased 2.25-fold by the 3rd h of coculture and had reduced again by the 5th h. IL-1 Ra (80 ng/ml) given to HSE 10 min before melanoma cells abrogated the HSE response to melanoma cells. The addition of 1% paraformaldehyde (PFA)-fixed B16 melanoma cells to HSE did not affect H2O2 production response, indicating that HSE-activating agents were on the melanoma cell surface. Preincubation of B16 melanoma cells in the presence of 5 micrograms/ml anti-mouse IL-1 beta neutralizing antibody reduced the melanoma cell-induced HSE production of H2O2 by 80%. On the contrary, B16 melanoma cell-conditioned medium did not vary HSE production of H2O2 compared to control HSE. Western blot analysis of cytosolic and membrane sediments from B16 melanoma cells confirmed the presence of IL-1 beta (17.4 kDa) in both cell compartments. Thus, HSE responded to melanoma cell contact with a rapid production of H2O2. HSE activation was IL-1-dependent. This cytokine was directly provided to HSE by the cell surface of adhered melanoma cells.
authors.affiliation: Department of Cellular Biology and Morphological Sciences, University of the Basque Country School of Medicine and Dentistry, Leioa, Vizcaya, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Anasagasti
authors.forename: A
authors.initials: A
authors.lastname: Alvarez
authors.forename: C
authors.initials: C
authors.lastname: Avivi
authors.forename: F
authors.initials: F
authors.lastname: Vidal-Vanaclocha
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005452:Fluoresceins; D005470:Fluorometry; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000473:pathology*; D051379:Mice; D008858:Microscopy, Phase-Contrast; D013997:Time Factors
chemical_list: D005452:Fluoresceins; D007375:Interleukin-1; C029569:diacetyldichlorofluorescein; D006861:Hydrogen Peroxide