A Role for Interleukin-10 in Alcohol-Induced Liver Sensitization to Bacterial Lipopolysaccharide (original) (raw)
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Journal of Psychiatry, 2015
Alcohol exposure is related to increased susceptibility to infections. We investigated the effect of acute exposure to alcohol on pro-and anti-inflammatory cytokine production in an ex-vivo model of whole blood stimulation with lipopolysacharide (LPS). Ten ml of whole blood were taken from 24 healthy volunteers (all men) aged 36.5 ± 1.4 years. Each sample was transferred into two tubes, without and with EDTA as anticoagulant, under sterile conditions. We had 14 groups: the control group in which whole blood was incubated without any other intervention, the LPS group in which whole blood was stimulated with LPS alone, and 12 alcohol groups with (6 groups) and without LPS stimulation (6 groups) using six different doses of alcohol (5‚ 12.5‚ 25‚ 50‚ 100 and 200mM). LPS (500pg) was added after pretreatment with alcohol for 10 minutes. Blood samples were diluted 1:10 in RPMI 1640 culture medium (100μl whole blood added in 900μl RPMI 1640), and then alcohol solution and LPS were added according to the study protocol for incubation period of 4 hours at 37°C. Cell culture supernatants were isolated with centrifugation at 1,800rpm, for 5 min at room temperature and stored at-70°C until measurements. Cytokine levels were determined in culture supernatant with the ELISA method. Alcohol had no effect on cytokine production when incubated with whole blood alone. TNF-α IL-6 and IL-10 significantly increased after LPS stimulation. Alcohol had no effect on IL-6 production after LPS challenge but significantly decreased TNF-α and IL-10 production in the presence of LPS challenge at 25mM to 200mM in a dose dependent manner. Conclusively TNF-α and IL-10 were significantly decreased after alcohol exposure in a dose depended manner in a model of whole blood stimulation with LPS exvivo expressing both suppression of pro-and anti-inflammatory response.
The Effect of Inflammatory Cytokines in Alcoholic Liver Disease
Mediators of Inflammation, 2013
Alcohol is the most common cause of liver disease in the world. Chronic alcohol consumption leads to hepatocellular injury and liver inflammation. Inflammatory cytokines, such as TNF-and IFN-, induce liver injury in the rat model of alcoholic liver disease (ALD). Hepatoprotective cytokines, such as IL-6, and anti-inflammatory cytokines, such as IL-10, are also associated with ALD. IL-6 improves ALD via activation of the signal transducer and activator of transcription 3 (STAT3) and the subsequent induction of a variety of hepatoprotective genes in hepatocytes. IL-10 inhibits alcoholic liver inflammation via activation of STAT3 in Kupffer cells and the subsequent inhibition of liver inflammation. Alcohol consumption promotes liver inflammation by increasing translocation of gut-derived endotoxins to the portal circulation and activating Kupffer cells through the LPS/Toll-like receptor (TLR) 4 pathways. Oxidative stress and microflora products are also associated with ALD. Interactions between pro-and anti-inflammatory cytokines and other cytokines and chemokines are likely to play important roles in the development of ALD. The present study aims to conduct a systemic review of ALD from the aspect of inflammation.
Alcoholism: Clinical and Experimental Research, 2001
Background: Endotoxin has been proposed to play a primary role in ALD, by initiating an inflammatory cascade within the liver. Although the source of these cytokines has been presumed to be circulating monocytes or tissue macrophages, ethanol-induced, nonhepatic sources of soluble mediators recently have been identified. One potential, but not clearly defined, extrahepatic source of cytokines in ALD is the intestine. In the current study, we hypothesized that alcohol would alter cytokine expression within the small intestine of mice exposed to ethanol and that LPS would alter levels of cytokine expression even more dramatically. Methods: Mice were fed a modified Lieber-DeCarli liquid ethanol or control diet for up to 14 days prior to injecting either saline or LPS. Plasma alanine aminotransferase (ALT) and cytokine levels, histology, and RT-PCR of pro-and anti-inflammatory cytokine gene expression were determined from distal ileum and liver samples. Translocation of intestinal bacterial flora also was assessed. Results: Ethanol exposure upregulated basal gene expression of IL-1, TNF-␣, IL-6, and iNOS in the distal ileum, but similar effects of ethanol on the liver were not observed. In contrast, LPS challenge of ethanol-exposed mice increased intestinal gene expression of some cytokines, but decreased expression of others. These effects were not associated with bacterial translocation. Also, ethanol alone induced a modest increase in both ICAM-1 and TLR4 mRNA expression in the intestine, but expression of both molecules was inhibited in mice that received both ethanol and LPS. Finally, whereas basal levels of hepatic IL-11 mRNA were not elevated by exposure to ethanol, intestinal IL-11 mRNA levels were increased more than100-fold. Conclusions: These studies are the first to show that ethanol affects cytokine gene expression in the ileum and identifies the ileum as a potential target for ethanol effects. In addition, our results suggest that IL-11 expression may be enhanced in the intestine to help repair or protect this organ from alcohol-induced damage. Collectively, these studies suggest that both pro-and anti-inflammatory soluble mediators in the intestine maintain and exacerbate the local hepatic response to ethanol.
Alcoholic Liver Disease: Role of Cytokines
Biomolecules, 2015
The present review spans a broad spectrum of topics dealing with alcoholic liver disease (ALD), including clinical and translational research. It focuses on the role of the immune system and the signaling pathways of cytokines in the pathogenesis of ALD. An additional factor that contributes to the pathogenesis of ALD is lipopolysaccharide (LPS), which plays a central role in the induction of steatosis, inflammation, and fibrosis in the liver. LPS derived from the intestinal microbiota enters the portal circulation, and is recognized by macrophages (Kupffer cells) and hepatocytes. In individuals with ALD, excessive levels of LPS in the liver affect immune, parenchymal, and non-immune cells, which in turn release various inflammatory cytokines and recruit neutrophils and other inflammatory cells. In this review, we elucidate the mechanisms by which alcohol contributes to the activation of Kupffer cells and the inflammatory cascade. The role of the stellate cells in fibrogenesis is also discussed.
A Voluntary Oral Ethanol-Feeding Rat Model Associated With Necroinflammatory Liver Injury
Alcoholism: Clinical and Experimental Research, 2008
The intragastric (IG) ethanol infusion model results in fatty liver, necrosis, inflammation and fibrosis. This model was utilized to study the pathogenesis of alcoholic liver disease (ALD). Disadvantages of the IG model include maintenance of the animals and equipment expense. To develop a voluntary feeding model for ALD, we took advantage of two important observations in the IG model: (i) female rats demonstrate greater severity of alcohol-induced liver injury than males and (ii) rats fed fish oil as a source of fatty acids develop more severe alcoholic liver injury than rats fed other fatty acids with ethanol. Female Wistar rats (205 to 220 g) were fed for 8 weeks a diet containing 8% ethanol, fish oil (30% of calories), protein, and dextrose. Pair-fed controls (FD) received dextrose in amounts isocaloric to ethanol. The following measurements were made: liver pathology [fatty liver (0 to 4), necrosis, inflammation and fibrosis by Sirius Red], endotoxin and alanine aminotransferase (ALT) in plasma, urine ethanol, lipid peroxidation, nuclear factor kappa-B (NF-kappaB) and mRNA levels for tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). Protein levels for iNOS and nitrotyrosine were evaluated by immunohistochemistry and Western Blot analysis. Liver proteasome and cytochrome P450 2E1 activity and protein levels of asialoglycoprotein receptor (ASGPR) were also evaluated. In addition, mRNA levels of fibrogenic markers were assessed. All animals lost weight for the initial 2 to 3 weeks but then gained weight until killing at 8 weeks. There was, however, a significant difference (p < 0.05) in weight between the ethanol-fed (Etoh) and (FD) groups at the end of the experiment. The mean urine ethanol levels ranged between 190 and 240 mg/dl. The severity of pathological changes was greater (p < 0.01) in Etoh vs. FD: fatty liver, 3.0 +/- 1.2 vs. 1.2 +/- 0.4; necrosis (foci/mm(2)), 3.9 +/- 2.3 vs. 0.4 +/- 0.3; inflammation (cells/mm(2)), 19.0 +/- 6.3 vs. 1.8 +/- 0.6. Centrilobular collagen deposition (% area), assessed by Sirius Red staining, was greater in Etoh vs. FD. Levels of endotoxin, ALT, CYP2E1 and lipid peroxidation markers were also higher (p < 0.01) in Etoh vs. FD. Levels of NF-kappaB and mRNA of pro-inflammatory mediators (TNF-alpha, COX-2, iNOS) and procollagen-I were increased (p < 0.05) in ethanol-fed rats. Immunohistochemical analysis showed more intense staining for both iNOS and nitrotyrosine in the centrilobular areas in the Etoh vs. FD groups. The greater area of positive staining for iNOS and nitrotyrosine in Etoh vs. FD was confirmed by Western Blot analysis. An increase in the expression of mRNA for profibrogenic genes (p < 0.05) was seen in ethanol-fed rats. A voluntary feeding regimen consisting of fish oil and ethanol in female rats is technically less demanding yet produces pathological and biochemical changes similar to those observed with the IG model. Pathological changes include fatty liver, necrosis and inflammation. Increased NF-kappaB and mRNA and protein levels of the pro-inflammatory mediators TNF-alpha, COX-2 and iNOS, coincided with the presence of necroinflammatory changes. The voluntary feeding regimen is proposed as an alternative to the IG model in the study of alcoholic liver injury.
Signalling pathways in alcohol-induced liver inflammation
Journal of Hepatology, 2009
The pathogenesis of alcoholic liver injury involves interactions of several intracellular signalling pathways in different cell types of the liver. Alcohol-induced sensitization of liver macrophages to portal endotoxin / lipopolysaccharide (LPS) is considered a hallmark of alcoholic liver disease (ALD). Intracellular mechanisms associated with LPS-induced signalling play a crucial role in the initiation and progression of alcoholic liver injury, and are being extensively explored. LPS recognition by Toll-like receptor 4 (TLR4) on macrophages and other cell types in the liver, activation of downstream signalling pathways culminating in activation of transcription factors such as NFjB, AP-1 leads to increased inflammatory cytokine production in ALD. In addition, LPS-induced MAPK such as ERK and p38 also contribute to liver injury. The importance of alcohol-induced reactive oxygen species and interactions with TLR pathways in macrophages leading to inflammation is becoming increasingly evident. Collectively, these signalling pathways induce pro-and anti-inflammatory cytokines that play an important role in ALD. In this review we describe the key signalling intermediates leading to alcohol-induced inflammation in alcoholic liver disease. Ó
BMC Immunology, 2009
Background: Previous reports indicate that ethanol, in a binge drinking model in mice, inhibits the production of pro-inflammatory cytokines in vivo. However, the inhibition of signaling through TLR4 has not been investigated in this experimental model in vivo. Considering evidence that signaling can be very different in vitro and in vivo, the present study was conducted to determine if effects of ethanol on TLR4 signaling reported for cells in culture or cells removed from ethanol treated mice and stimulated in culture also occur when ethanol treatment and TLR4 activation occur in vivo. Results: Phosphorylated p38, ERK, and c-Jun (nuclear) were quantified with kits or by western blot using samples taken 15, 30, and 60 min after stimulation of peritoneal macrophages with lipopolysaccharide in vivo. Effects of ethanol were assessed by administering ethanol by gavage at 6 g/kg 30 min before administration of lipopolysaccharide (LPS). Cytokine concentrations in the samples of peritoneal lavage fluid and in serum were determined at 1, 2, and 6 hr after lipopolysaccharide administration. All of these data were used to measure the area under the concentration vs time curve, which provided an indication of the overall effects of ethanol in this system. Ethanol suppressed production of most pro-inflammatory cytokines to a similar degree as it inhibited key TLR4 signaling events. However, NF-B (p65) translocation to the nucleus was not inhibited by ethanol. To determine if NF-B composed of other subunits was inhibited, transgenic mice with a luciferase reporter were used. This revealed a reproducible inhibition of NF-B activity, which is consistent with the observed inhibition of cytokines whose expression is known to be NF-B dependent. Conclusion: Overall, the effects of ethanol on signalling in vivo were similar to those reported for in vitro exposure to ethanol and/or lipopolysaccharide. However, inhibition of the activation of NF-B was not detected as translocation of p65 to the nucleus but was detected using transgenic reporter mice. The observation that ethanol given 24 hr before dosing with LPS modulated production of some cytokines indicates a persistent effect which does not require continued presence of ethanol.
Alcoholism: Clinical and Experimental Research, 2002
Background: Whereas the role of proinflammatory cytokines in the pathogenesis of alcoholic liver disease has been at the forefront of investigation, a possible role for anti-inflammatory cytokines in this disease has received little attention. This study investigated (1) the hepatic protective effect of an anti-inflammatory cytokine, epidermal growth factor (EGF), against deleterious effects of alcohol and sensitization to bacterial lipopolysaccharide (LPS), and (2) the possible mechanisms that underlie such protection.
Cytokines and the Molecular Mechanisms of Alcoholic Liver Disease
Alcoholism: Clinical and Experimental Research, 1999
This manuscript was given as a plenary lecture at the annual meeting of the Research Society on Alcoholism in July of 1999. It describes the general mechanisms by which tumor necrosis factor (TNF) alpha, an injury-related cytokine, promotes liver regeneration and then details how TNF-initiated hepatotrophic signals are inhibited by chronic ethanol consumption. There is evidence that chronic ethanol exposure impairs the TNF-dependent activation of stress-activated protein kinases and some of their targets, including the growth-stimulatory DNA binding protein, c-Jun. Ethanol exposure also prevents TNF from activating the redox-sensitive transcription factor, NF kappa B, in regenerating hepatocytes. These effects are followed by decreased hepatocyte proliferation, as well as by impaired induction of TNFregulated survival factors, such as Bcl-XL, in the liver. Thus, chronic ethanol consumption may damage the liver by inhibiting the hepatotrophic and hepatoprotective actions of TNFa and other growth-regulatory cytokines.