Interleukin 1 ? markedly stimulates nitric oxide formation in the absence of other cytokines or lipopolysaccharide in primary cultured rat hepatocytes but not in Kupffer cells

Abstract

responses. 1 In vivo, NO has been reported to have pro-LPS stimulated NO formation in a dose-dependent manner and induced half-maximal effects at 30 pmol/L. Maxi-tective effects during the inflammation and endotoxemal stimulation was achieved at 12 to 16 hours after the mia associated with hepatic injury. 2 In contrast, NO addition of 1 nmol/L of IL-1b, and was 50-to 60-fold above has also been reported to induce hepatic mitochondrial basal levels in rat hepatocytes. The combined effect of dysfunction both in perfused liver and isolated hepatothese cytokines with LPS or IFN-g on NO formation was cytes. 3 Interleukin (IL)1b, tumor necrosis factor a also examined. Neither LPS nor IFN-g affected the IL-(TNF-a), and endotoxins have all been shown to stimu1b-induced NO formation. TNF-a, however, stimulated late NO formation in hepatocytes and in Kupffer cells IL-1b-induced NO formation, while IL-6 inhibited it, al-cultured from chronically endotoxemic rats 4 or turpenthough independently these cytokines had no effect on tine-injected rats. 5 NO is synthesized from L-arginine NO formation. None of the cytokines tested stimulated by NO synthases (NOS). These enzymes can be classi-NO formation in cultured rat Kupffer cells. In hepatocytes, the NO formation induced by IL-1b was blocked by fied into at least two distinct groups. Constitutive NOS both the NO synthase (NOS) inhibitor N G -monomethyl-L-is present in endothelium 6 and in brain. 7 Inducible arginine (L-NMMA) and by IL-1 receptor antagonist (IL-NOS (iNOS) is present in negligible quantities under 1ra). Furthermore, IL-1b markedly increased NOS activ-physiological conditions, but is highly expressed in reity, and this increase in activity was accompanied by sponse to stimuli such as endotoxins and cytokines, the expression of inducible NOS (iNOS) messenger RNA in a variety of cells including vascular smooth muscle (mRNA). This study clearly demonstrated that IL-1b cells, 8,9 macrophages, 10 and liver cells. [11][12][13] Within the markedly stimulates NO formation in hepatocytes, in the liver, however, it is not clear whether the Kupffer cells or the hepatocytes are the primary producers of NO. In order to elucidate the mechanism by which cytokines induce NO formation within the liver, a sensitive Abbreviations: IL, interleukin; TNF-a, tumor necrosis factor a; NOS, nitric oxide synthase; iNOS, inducible nitric oxide synthase; LPS, lipopolysaccharide; chemiluminescence system was employed for the mea-

Vicinal Dithiol-binding Agent, Phenylarsine Oxide, Inhibits Inducible Nitric-oxide Synthase Gene Expression at a Step of Nuclear Factor-κB DNA Binding in Hepatocytes

“…Oxide Derivative in Hepatocytes-As reported previously, an inflammatory cytokine IL-1␤ increased levels of nitrite (nitric oxide metabolite) released to the medium in primary cultures of rat hepatocytes, where concentrations for the maximal and half-maximal effects were 1 nM and 30 pM, respectively (8). Simultaneous addition of PAO, a trivalent arsenical compound, inhibited the nitritereleasestimulatedbyIL-1␤inthetime-andconcentrationdependent manner (Fig.…”

“…Induction of iNOS by lipopolysaccharide contributes to the pathogenesis of septic shock (7), leading to organ destruction, including the liver. We (8) and others (9) have reported that a single cytokine interleukin 1␤ (IL-1␤) mimicked the in vivo induction of iNOS in cultured hepatocytes. Other cytokines such as IL-6, tumor necrosis factor ␣ (TNF␣), and interferon ␥ had no effect under the same conditions (8), although a combination of these cytokines and lipopolysaccharide stimulated the nitric oxide production (10,11).…”

“…We (8) and others (9) have reported that a single cytokine interleukin 1␤ (IL-1␤) mimicked the in vivo induction of iNOS in cultured hepatocytes. Other cytokines such as IL-6, tumor necrosis factor ␣ (TNF␣), and interferon ␥ had no effect under the same conditions (8), although a combination of these cytokines and lipopolysaccharide stimulated the nitric oxide production (10,11). A high level of nitric oxide production by iNOS influences various hepatic metabolism and functions, where nitric oxide inhibits the mitochondrial Krebs cycle enzyme (12) and ATP synthesis (13).…”

Hypoxia and Heat Inhibit Inducible Nitric Oxide Synthase Gene Expression by Different Mechanisms in Rat Hepatocytes

“…Pro-inflammatory cytokine IL-1␤ induced a gene expression of iNOS and increased the production of nitric oxide in primary cultures of rat hepatocytes as reported previously. 46,47 Under hypoxic conditions with an Anaeropack system, oxygen concentrations dropped to less than 1% within 1 hour after the introduction of hypoxia. Hypoxia inhibited levels of nitrite (nitric oxide metabolite) released into the medium (Fig.…”

Synergistic regulation of inducible nitric oxide synthase gene by CCAAT/enhancer‐binding protein β and nuclear factor‐κB in hepatocytes

“…In the liver, LPS and inflammatory cytokines, such as interleukin (IL)-1 and tumour necrosis factor-␣, cause iNOS induction, and then provoke prominent NO production (Nathan 1992;Geller et al 1993). Using primary cultured cells from the rat liver, we and another group have demonstrated that the NO production is induced by IL-1␤ in hepatocytes, whereas NO is produced by LPS in Kupffer cells (Geller et al 1995;Kitade et al 1996). IL-1␤ effectively increases iNOS mRNA, and then NO production in human hepatocytes (Geller et al 1995).…”