Acute alcohol intoxication and gadolinium chloride attenuate endotoxin-induced release of CC chemokines in the rat

Nanoparticle Delivery of Novel PDE4B Inhibitor for the Treatment of Alcoholic Liver Disease

The incidence of alcoholic liver disease (ALD) is increasing worldwide while no effective treatment has been approved. The progression of ALD has proven to be related to the upregulation of phosphodiesterase 4 (PDE4) expression, and PDE4 inhibitors showed potential to improve ALD. However, the application of PDE4 inhibitors is limited by the gastrointestinal side effects due to PDE4D inhibition. Therefore, we used a novel PDE4B inhibitor KVA-D88 as the therapeutic for ALD treatment. KVA-D88 inhibited inflammatory response, promoted β-oxidation, increased the level of antioxidants in the hepatocytes, and suppressed hepatic stellate cell (HSC) activation in vitro. To improve the solubility and availability in vivo, KVA-D88 was encapsulated into mPEG-b-P(CB-co-LA) nanoparticles (NPs) by solvent evaporation, with a mean particle size of 135 nm and drug loading of 4.2%. We fed the male C57BL/6 mice with a Lieber–DeCarli liquid diet containing 5% (v/v) ethanol for 6 weeks to induce ALD. Systemic administration of KVA-D88 free drug and KVA-D88-loaded NPs at 5 mg/kg significantly improved the ALD in mice. KVA-D88 significantly ameliorated alcohol-induced hepatic injury and inflammation. KVA-D88 also markedly reduced steatosis by promoting fatty acid β-oxidation. Liver fibrosis and reactive oxygen species (ROS)-caused cellular damage was observed to be alleviated by KVA-D88. KVA-D88-loaded NPs proved better efficacy than free drug in the animal study. In conclusion, the novel PDE4B inhibitor KVA-D88-loaded NPs have the potential to treat ALD in mice

Human Binge Alcohol Intake Inhibits TLR4-MyD88 and TLR4-TRIF Responses but Not the TLR3-TRIF Pathway: HspA1A and PP1 Play Selective Regulatory Roles

Binge/moderate alcohol suppresses TLR4-MyD88 proinflammatory cytokines; however, alcohol's effects on TLR-TRIF signaling, especially after in vivo exposure in humans, are unclear. We performed a comparative analysis of the TLR4-MyD88, TLR4-TRIF, and TLR3-TRIF pathways in human monocytes following binge alcohol exposure. Mechanistic regulation of TLR-TRIF signaling by binge alcohol was evaluated by analyzing IRF3 and TBK1, upstream regulator protein phosphatase 1 (PP1), and immunoregulatory stress proteins HspA1A and XBP-1 in alcohol-treated human and mouse monocytes/macrophages. Two approaches for alcohol exposure were used: in vivo exposure of primary monocytes in binge alcohol-consuming human volunteers or in vitro exposure of human monocytes/murine macrophages to physiological alcohol concentrations (25-50 mM ethanol), followed by LPS (TLR4) or polyinosinic-polycytidylic acid (TLR3) stimulation ex vivo. In vivo and in vitro binge alcohol exposure significantly inhibited the TLR4-MyD88 cytokines TNF-α and IL-6, as well as the TLR4-TRIF cytokines/chemokines IFN-β, IP-10, and RANTES, in human monocytes, but not TLR3-TRIF-induced cytokines/chemokines, as detected by quantitative PCR and ELISA. Mechanistic analyses revealed TBK-1-independent inhibition of the TLR4-TRIF effector IRF3 in alcohol-treated macrophages. Although stress protein XBP-1, which is known to regulate IRF3-mediated IFN-β induction, was not affected by alcohol, HspA1A was induced by in vivo alcohol in human monocytes. Alcohol-induced HspA1A was required for inhibition of TLR4-MyD88 signaling but not TLR4-TRIF cytokines in macrophages. In contrast, inhibition of PP1 prevented alcohol-mediated TLR4-TRIF tolerance in macrophages. Collectively, our results demonstrate that in vivo and in vitro binge alcohol exposure in humans suppresses TLR4-MyD88 and TLR4-TRIF, but not TLR3-TRIF, responses. Whereas alcohol-mediated effects on the PP1-IRF3 axis inhibit the TLR4-TRIF pathway, HspA1A selectively suppresses the TLR4-MyD88 pathway in monocytes/macrophages.

Gene expression profile analysis of rat cerebellum under acute alcohol intoxication

Acute alcohol intoxication, a common disease causing damage to the central nervous system (CNS) has been primarily studied on the aspects of alcohol addiction and chronic alcohol exposure. The understanding of gene expression change in the CNS during acute alcohol intoxication is still lacking. We established a model for acute alcohol intoxication in SD rats by oral gavage. A rat cDNA microarray was used to profile mRNA expression in the cerebella of alcohol-intoxicated rats (experimental group) and saline-treated rats (control group). A total of 251 differentially expressed genes were identified in response to acute alcohol intoxication, in which 208 of them were up-regulated and 43 were down-regulated. Gene ontology (GO) term enrichment analysis and pathway analysis revealed that the genes involved in the biological processes of immune response and endothelial integrity are among the most severely affected in response to acute alcohol intoxication. We discovered five transcription factors whose consensus binding motifs are overrepresented in the promoter region of differentially expressed genes. Additionally, we identified 20 highly connected hub genes by co-expression analysis, and validated the differential expression of these genes by real-time quantitative PCR. By determining novel biological pathways and transcription factors that have functional implication to acute alcohol intoxication, our study substantially contributes to the understanding of the molecular mechanism underlying the pathology of acute alcoholism.

Chemokines mediate ethanol-induced exacerbations of murine cockroach allergen asthma

Asthma imposes considerable patient and economic burdens, with the most severe cases causing the greatest affliction. Identifying stimuli that worsen asthma severity is an essential step to controlling both disease morbidity and the lessening economic impact. This study provides the first mechanistic investigation into how acute ethanol exposure will increase asthma severity in a murine model of mild cockroach allergen (CRA)-induced asthma. Outbred mice were sensitized to induce mild allergic asthma, with intratracheal CRA exposures on days 0 and 14. On day 21 mice were gavaged with water or 32% ethanol, and the third allergen exposure was given 30 min post-gavage. Asthmatic responses were measured at several time-points up to 42 h after the third allergen challenge. Ethanol-gavaged mice showed increased asthma severity within 90 min post-allergen challenge, with exacerbations lasting for 24 h. Ethanol caused greater airways obstruction, including an eightfold increase in epithelial cell mucin and increased mucus plugs, resulting in a 50% reduction in bronchiole patency. Ethanol gavage also induced significant increases in airways hyperreactivity. While T helper type 1 (Th1) and Th2 cytokines were not altered by ethanol gavage, pulmonary neutrophil and eosinophil recruitment were augmented. This increase was associated with increased chemokine production. Administration 2 h prior to ethanol gavage of a neutralizing antibody cocktail to keratinocyte-derived chemokine, macrophage inflammatory protein-2, eotaxin-1 and eotaxin-2 prevented ethanol-induced eosinophil recruitment and airways hyperreactivity. These data provide evidence that acute alcohol exposure immediately prior to a mild allergen-triggered asthmatic episode will exacerbate asthma severity mediated by increased production of chemokines.

CCL5-28, CCL5-403, and CCR5 genetic polymorphisms and their synergic effect with alcohol and tobacco consumptions increase susceptibility to hepatocellular carcinoma

The aim of this study was to estimate the relationship between gene polymorphisms of CCL5-28, CCL5-403, and CCR5 to the susceptibility of hepatocellular carcinoma (HCC). A total of 449 subjects, including 347 healthy controls and 102 patients with HCC, were recruited in this study and subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to investigate the impact of these two polymorphic variants on HCC. A significant association between HCC susceptibility and genetic polymorphism, CG heterozygotes of CCL5-28 (AOR=2.35; 95% CI=1.27-4.33, p=0.006), AA homozygotes of CCL5-403 (AOR=5.18; 95% CI=2.25-11.91, p=0.0001), and AA homozygotes of CCR5 (AOR=2.47; 95% CI=1.24-4.90, p=0.009), was found compared with wild genotype after adjusting for other confounders. It was detected that synergistic effect between gene-to-gene polymorphisms increased the risk to have HCC among individuals with CG or GG of CCL5-28, and GA or AA of CCL-403, and GA or AA of CCR5 (AOR=3.42; 95% CI=1.39-8.38, p=0.007) compared to individuals with wild genotypes of CCL5-28, CCL-403, and CCR5. Also, alcohol or tobacco consumption increased the risk to have HCC among subjects with CG heterozygotes of CCL5-28 (alcohol: p=0.001; tobacco: p=0.006), AA homozygotes (alcohol: p=0.0004; tobacco: p≤0.0001) or GA heterozygotes (tobacco: p=0.03) of CCL5-403, and AA homozygotes of CCR5 (alcohol: p=0.02; tobacco: p=0.02), respectively. Gene polymorphisms of CCL5-28, CCL5-403, and CCR5 play an important factor for the susceptibility of HCC, respectively. The synergic effects of these two gene polymorphisms to tobacco or alcohol consumption significantly increase the risk to develop HCC.

Effects of trauma-hemorrhage and IL-6 deficiency on splenic immune function in a murine trauma model

Splenic immune function is known to be depressed following hemorrhage. The present study investigates the effects of femoral shaft fracture, isolated or in combination with hemorrhage, on early stage cytokine production capacity of splenocytes and observes the role of IL-6 under these conditions. Male IL-6 knockout (IL-6^−/−) and wild-type mice (WT) were randomly divided into three groups: sham (S), isolated femoral fracture (Fx), and femoral fracture + volume controlled hemorrhage (TH-Fx) (n = 6 per group). Animals were sacrificed four hours after induction of hemorrhage and fracture. Cytokine release (TNF-α, IL-6, and IL-10) of isolated and LPS-stimulated splenocytes was determined by cytometric bead array. Femoral fracture with or without hemorrhage caused a suppression of in vitro cytokine production capacity of splenocytes at an early posttraumatic stage in WT and IL-6^−/−. In the absence of IL-6, the profile of splenic cytokine secretion is significantly altered, identifying this cytokine as a potential therapeutic target to modulate the posttraumatic immune response.

Productive capacity of alveolar macrophages and pulmonary organ damage after femoral fracture and hemorrhage in IL-6 knockout mice

Alveolar macrophages (AM) play an important role in the pathogenesis of posttraumatic pulmonary failure, and have been identified as major source of pulmonary cytokines. The effects of locally generated IL-6 as well as femoral fracture on the pulmonary inflammatory response and organ damage have not been fully elucidated. In the present study we evaluated the influence of femoral fracture, isolated or in combination with hemorrhage, on the immune function of AM and remote lung injury, and investigated the role of pulmonary IL-6 within this setting. 18 wild type (WT) and 18 IL-6 knockout mice (IL-6(-/-)) underwent standardized femoral fracture, isolated or in combination with volume-controlled hemorrhage, followed by fluid resuscitation and splint fixation of the fracture. Animals were sacrificed 4h after induction of fracture and hemorrhage. Animals were randomly assigned to three study groups (each consisting of six animals). Besides sham groups, experimental groups included animals with isolated femoral fracture or in combination with hemorrhagic shock. Cytokine release of AM was determined by flow cytometry. Pulmonary damage in terms of interstitial thickening and lung neutrophil infiltration was assessed by histology and immunohistology. The productive capacity of AM for pro-inflammatory cytokines was increased after isolated femoral fracture in WT and IL-6(-/-) mice. An additional hemorrhagic insult resulted in a further enhancement of pro-inflammatory cytokine release and an increased MCP-1 secretion in WT and IL-6(-/-) animals. MCP-1 and pro-inflammatory cytokine production of AM was attenuated in IL-6(-/-) mice compared to the respective WT groups. Interstitial thickening and lung neutrophil infiltration was only observed after femoral fracture combined with hemorrhagic shock with an attenuation of the pulmonary organ damage in IL-6(-/-) compared to WT animals. These results support the role of IL-6 as a therapeutic target for posttraumatic immune modulation. With an increased pro-inflammatory mediator release, already an isolated femoral fracture seems to influence the immune response of AM.

In vitro and in vivo models of acute alcohol exposure

Alcohol abuse is a global problem due to the financial burden on society and the healthcare system. While the harmful health effects of chronic alcohol abuse are well established, more recent data suggest that acute alcohol consumption also affects human wellbeing. Thus, there is a need for research models in order to fully understand the effect of acute alcohol abuse on different body systems and organs. The present manuscript summarizes the interdisciplinary advantages and disadvantages of currently available human and non-human models of acute alcohol abuse, and identifies their suitability for biomedical research.

Homocysteine induces monocyte chemoattractant protein-1 expression in hepatocytes mediated via activator protein-1 activation

Hyperhomocysteinemia is characterized by abnormally high concentrations of homocysteine (Hcy) in the plasma. It is a metabolic disorder associated with dysfunction of several organs such as atherosclerosis, altered lipid metabolism, and liver injury. In this study we investigated the effect of Hcy on transcriptional regulation of monocyte chemoattractant protein-1 (MCP-1), a potent chemokine, expression in hepatocytes. Hyperhomocysteinemia was induced in rats by a high-methionine diet for 4 weeks. MCP-1 mRNA and protein levels were significantly elevated in the liver tissue homogenate and in hepatocytes of hyperhomocysteinemic rats. The role of transcription factors in MCP-1 expression was examined by electrophoretic mobility shift assay. Activation of activator protein (AP)-1 but not nuclear factor kappaB was detected in the liver tissue of those rats. Incubation of rat hepatocytes with Hcy (50-200 microm) caused a significant increase in AP-1 activation followed by an increase in intracellular MCP-1 mRNA expression and an elevation of MCP-1 protein secreted into the culture medium. Hcy markedly increased the DNA binding activity of human recombinant AP-1 (c-Fos and c-Jun proteins). The presence of a sulfhydryl group in Hcy was essential for Hcy-induced AP-1 activation. When hepatocytes were transfected with decoy AP-1 oligodeoxynucleotide to inhibit AP-1 activation, Hcy-induced MCP-1 mRNA expression was abolished. Further analysis revealed that increased hepatic MCP-1 expression was positively correlated with the serum MCP-1 level. These results suggest that Hcy-induced MCP-1 expression in the liver is mediated via AP-1 activation, which may contribute to chronic inflammation associated with hyperhomocysteinemia.

Kupffer cells and their mediators: the culprits in producing distant organ damage after trauma-hemorrhage

Posttraumatic activation of macrophages enhances development of systemic inflammation/immunosuppression and organ dysfunction. We hypothesized that Kupffer cells are the main source of monocyte chemoattractant protein-1 (MCP-1) production after trauma-hemorrhage, that administration of 17beta-estradiol (E2) after trauma-hemorrhage modulates MCP-1 release and reduces remote organ damage, and that salutary effects of E2 are mediated via estrogen receptor (ER)-alpha. To test these hypotheses, female B57BL/J6 mice received E2 (50 microg/25 g) or vehicle after trauma-hemorrhage and female 129 Sve ER-beta-/- transgenic mice and ovariectomized wild-type mice received E2 or ER-alpha agonist propyl pyrazole triol (50 microg/25 g) after trauma-hemorrhage. Systemic MCP-1 and interleukin-6 and their release by liver, spleen, and lung macrophages were determined by flow cytometry 4 hours after trauma-hemorrhage. Prior Kupffer cell depletion with gadolinium chloride significantly decreased systemic MCP-1 and interleukin-6 after trauma-hemorrhage and was associated with decreased edema/neutrophil infiltration in lung and liver. Kupffer cells were the only macrophages showing significant MCP-1 release, which was markedly reduced by E2 or propyl pyrazole triol in wild-type and in ER-beta-/- mice. Pretreatment of mice with anti-MCP-1 antiserum prevented an increase in myeloperoxidase and edema in lung and liver. These findings suggest that Kupffer cell-derived MCP-1 plays a major role in remote organ dysfunction after trauma-hemorrhage.

Effects of 17beta-estradiol and flutamide on inflammatory response and distant organ damage following trauma-hemorrhage in metestrus females

We hypothesized that administration of androgen receptors antagonist flutamide following trauma-hemorrhage (T-H) in metestrus females will maintain immune function and reduce remote organ damage under those conditions. Female B57BL/J6 mice (metestrus state, 8-12 weeks old) underwent laparotomy and hemorrhagic shock (35.0+/-5.0 mmHg for 90 min) and then received 17beta-estradiol (E2; 50 microg/25 g), flutamide (625 microg/25 g), or E2 + flutamide. Four hours after resuscitation, plasma cytokine and chemokine (TNF-alpha, IL-6, IL-10, IFN-gamma, and MCP-1) concentrations and their release in vitro by hepatic and pulmonary tissue macrophages (M Phi) were determined by flow cytometry. Organ damage was assessed by edema formation (wet-to-dry weight ratio) and neutrophil infiltration [myeloperoxidase (MPO) activity]. Administration of E2, flutamide, or E2 + flutamide following T-H resulted in a significant decrease in systemic TNF-alpha, IL-6, and MCP-1 concentrations under those conditions. This was accompanied by significantly decreased in vitro TNF-alpha release by Kupffer cells after administration of E2, flutamide, or E2 + flutamide. The in vitro release of proinflammatory cytokines by alveolar M Phi, however, was reduced significantly only by the addition of E2 or E2 + flutamide but not by the addition of flutamide. A significant decrease in pulmonary and hepatic edema formation as well as neutrophil infiltration in the lung was observed after E2, flutamide and E2 + flutamide administration. In contrast, hepatic neutrophil infiltration was only significantly reduced following E2 and E2 + flutamide administration. Thus, although flutamide does not produce synergistic, salutary effects with E2, its administration in females following T-H also produces salutary effects on the immune and organ function, similar to E2 administration under those conditions.

Expression of macrophage inflammatory protein-1α in Kupffer cells following liver ischemia or reperfusion injury in rats

AIM: To explore the expression of macrophage inflammatory protein-1α (MIP-1α) in Kupffer cells (KCs) following liver ischemia/reperfusion injury IRI in rats.

METHODS: Forty male SD rats were divided randomly into five groups. A model of partial warm ischemia/reperfusion injury in the rat liver was established. KCs were isolated and incubated one hour, six hours, 12 h, and 24 h after the reperfusion. Tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β) in the supernatants were measured by ELISA. MIP-1α in KCs was detected by immunocytochemical and RT-PCR.

RESULTS: No or few MIP-1α protein and mRNA were expressed in the KCs of the control group. Its expression in the IRI group had a significant increase after the reperfusion (P < 0.05), which was contrary to the control group.

CONCLUSION: The active behavior of the MIP-1α gene in KCs following liver ischemia/reperfusion injury is assumed to be one of the major causes for the hepatic ischemia/reperfusion injury.

Ethanol-induced liver injury: potential roles for egr-1

Chronic ethanol-induced liver injury follows a typical progression from its earliest stage of steatosis to more advanced injury, characterized by the development of inflammation, hepatocyte necrosis/apoptosis, fibrosis and finally cirrhosis. Kupffer cells, the resident macrophage in the liver, play a critical role in the progression of liver injury. Increased exposure of Kupffer cells to lipopolysaccharide (LPS) during chronic ethanol exposure leads to the production of a number of inflammatory mediators, including tumor necrosis factor alpha (TNF-alpha). Recent evidence indicates that in addition to increased exposure to LPS, Kupffer cells also develop an enhanced sensitivity to LPS after chronic ethanol feeding. We have recently identified early growth response-1 (Egr-1), an immediate-early gene transcription factor, as an important contributor to increased LPS-stimulated TNF-alpha secretion by Kupffer cells after chronic ethanol exposure. In other models of tissue injury, such as ischemia-reperfusion in the lung, Egr-1 acts as a coordinator of the complex response to stress. Here we review the literature regarding the role of EGR-1 in regulation of a number of genes implicated in each of the stages of chronic ethanol-induced liver injury. In addition to the critical role of Egr-1 in generating maximal LPS-stimulated TNF-alpha expression, Egr-1 also controls the expression of a number of inflammatory mediators, including intercellular adhesion molecule (ICAM)-1, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-2, as well as genes contributing to fibrosis, such as transforming growth factor (TFG)-beta1, platelet-derived growth factor PDGF-A chain and fibroblast growth factor (FGF). Understanding the contribution of Egr-1 to the expression of genes involved in the development of chronic ethanol-induced liver injury may lead to the development of improved therapies designed to prevent and/or reverse alcohol-induced liver injury.

Role of Kupffer cells in lung injury in rats administered endotoxin 1

The purpose of this study was to investigate the regulation of lung macrophages (Muvarphis) by Kupffer cells (KCs) in lung injury caused by endotoxemia. Phenotypic differences in tissue Muvarphis were also investigated. Muvarphis were isolated from gadolinium chloride (GdCl(3))- or saline-treated rats 2 h after saline or lipopolysaccharide (LPS) administration. Furthermore, rats were given GdCl(3) 24 h prior to LPS administration, and survival rate was assessed for 24 h. Moreover, lung edema was assessed 9 h after LPS injection. Expression of inflammatory mediators was measured in the liver and lung. KCs were divided into three subpopulations based on size and phagocytosis. The expression of TNF-alpha and MIP-2 was greater in the small KCs and lung Muvarphis, while the expression of IL-6, IL-10, and MCP-1 was greater in the large and intermediate KCs. GdCl(3) eliminated ED2-positive large KCs and did not have any effect on the lung Muvarphis. The number of ED1-positive KCs increased significantly in both organs after LPS challenge and was reduced by GdCl(3). The population of ED2-positive KCs did not change following LPS administration. GdCl(3) completely prevented increases in lung microvascular permeability and mortality after LPS infusion. After LPS administration, expression of TNF-alpha and IL-6 increased rapidly and then decreased gradually in both organs. GdCl(3) inhibited these increases in the liver significantly and enhanced the expression of MCP-1 and IL-10 in the lung 9 h after LPS administration. Thus, the heterogeneous response of KCs to endotoxin leads to production of certain cytokines and chemokines that affect lung function.

Alcohol and HIV decrease proteasome and immunoproteasome function in macrophages: implications for impaired immune function during disease

Proteasomes (proteinase complexes, PR) and immunoproteasomes (IPR) degrade damaged proteins and affect protein processing required for antigen presentation by mononuclear phagocytes. These critical immune processes are attenuated during progressive HIV-1 infection and are affected by alcohol abuse. To investigate the mechanisms underlying these functional changes, we measured PR and CYP2E1 activities [an ethanol (EtOH) metabolizing enzyme] and reactive oxygen species (ROS) in human monocyte-derived macrophages (MDM) following HIV-1 infection and EtOH treatment. We observed progressive declines of PR activity and PR/IPR contents in HIV-1-infected MDM. PR activity and IPR expression increased after IFN-gamma stimulation but reduced after HIV-1 infection. EtOH inhibited both IFN-gamma-induced PR and IPR. Paradoxically, EtOH attenuated PR catalytic activity in infected MDM and suppressed viral replication. Elevated ROS followed EtOH exposure and paralleled decreased PR activity. The latter was restored by anti-oxidant. The data support the notion that HIV-1 infection and EtOH may work in concert to affect immune function including antigen presentation and thereby affect disease progression.

Octreotide regulates CC but not CXC LPS-induced chemokine secretion in rat Kupffer cells

Kupffer cells (KC) and lipopolysaccharide (LPS) interaction is the initial event leading to hepatic inflammation and fibrosis in many types of liver injury. We studied chemokine secretion by KC activated with LPS and the possible effect of the somatostatin analogue octreotide, in the regulation of this process. KC isolated from Sprague-Dawley rats were cultured in the presence of LPS added alone or with different concentrations of octreotide for 24 and 48 h, and chemokine production was assessed in culture supernatants by ELISA. CC chemokine mRNA expression was assessed by semiquantitative RT-PCR. Vehicle-stimulated KC produced a basal amount of CC and CXC chemokines. LPS-stimulated KC secreted significantly increased amounts of IL-8 (GRO/CINC-1) (P<0.001), MIP-2 (P<0.001), MCP-1 (P<0.001), and RANTES (P<0.01). Octreotide inhibited LPS-induced secretion of the CC chemokines MCP-1 (P<0.05) and RANTES (P<0.05), but not the CXC chemokines IL-8 (GRO/CINC-1) and MIP-2, in a concentration-dependent manner. Downregulation of basal and LPS-induced mRNA expression of the CC chemokines was also observed in the presence of octreotide. Pretreatment with phosphatidylinositol 3 (PI3)-kinase inhibitors reduced chemokine production by LPS-treated KC in both the mRNA and protein level. Furthermore, it prevented the octreotide inhibitory effect on LPS-induced chemokine secretion, indicating a possible involvement of the PI3-kinase pathway. In conclusion, these data demonstrate that chemokine secretion by KC can be differentially regulated by octreotide, and suggest that this somatostatin analogue may have immunoregulatory effects on resident liver macrophages. British Journal of Pharmacology (2004) 141, 477-487. doi:10.1038/sj.bjp.0705633

Immune response modulation in acutely ethanol-intoxicated, acutely diabetic male and female rats

We examined how acute diabetes mellitus and acute ethanol intoxication modulate factors that mediate immune responses as a basis for explaining the increased susceptibility to infection in these two conditions. Our working hypothesis is that ethanol intoxication in diabetes compromises host defense mechanisms to a greater extent than observed in each condition alone. Male and female rats were made diabetic with streptozotocin (65 mg/kg, i.p.). Forty-eight hours after administration of streptozotocin, rats either received no treatment (control group) or were treated with (1) ethanol (bolus injection of 1.75 g/kg, followed by a 3-h infusion at the rate of 300 mg/kg/h), (2) lipopolysaccharide [(LPS); 0.9 mg/kg], or (3) a combination of LPS+ethanol. At the end of 3 h, rats were killed, and the livers were digested by perfusion with collagenase-containing Hanks' balanced salt solution to isolate hepatocytes and Kupffer cells. To measure chemokine generation, hepatocytes (2.5x10(5) cells per well) and Kupffer cells (1x10(6) cells per well) were cultured for 20 h, and the supernatant was used to measure cytokine-induced neutrophil chemoattractant (CINC) and regulated on activation, normal T-cell expressed and secreted (RANTES) chemokines. Phagocytosis by Kupffer cells was measured by flow cytometry and expressed as mean channel fluorescence intensity (MCF). Induction of diabetes as well as treatment of nondiabetic rats with LPS, ethanol, or LPS+ethanol caused depression of MCF values of Kupffer cells. However, treatment of the diabetic male and female rats with LPS and LPS+ethanol increased the MCF values relative to those of Kupffer cells obtained from untreated diabetic rats, but administration of ethanol to diabetic rats did not have a similar effect. The induction of diabetes caused an increase in CINC generation by Kupffer cells obtained from male rats, but not from female rats. This diabetes-induced elevation of chemoattractant factor was decreased when diabetic animals were treated with LPS, ethanol, or LPS+ethanol, and the sex difference was obliterated. Thus, the induction of diabetes as well as treatment with LPS, ethanol, or LPS+ethanol in nondiabetic rats depressed the phagocytic capability of Kupffer cells, whereas the presence of endotoxemia (administration of the endotoxin LPS) or administration of LPS+ethanol reversed the diabetic effect, but ethanol intoxication did not. These findings seem to indicate a persistence of depression of host defense capacity in the ethanol-intoxicated diabetic condition. This is further reinforced by the depression of the diabetes-induced enhancement of chemotaxis when the diabetic rats became intoxicated.

Edaravone, a novel free radical scavenger, prevents liver injury and mortality in rats administered endotoxin

We postulated that a novel free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone; EDA), would attenuate inflammatory cytokine and chemokine expression in the liver after lipopolysaccharide (LPS) challenge through its antioxidant effect. Rats were administered EDA (0.3, 1.5, 3.0, 6.0, and 12.0 mg/kg) or the same volume of saline intravenously just after LPS (10 mg/kg) injection and then was continued intermittently every 2 h (five administrations in total). Survival was assessed for the next 24 h. In separate experiments, rats were sacrificed at 60 min, 90 min, 6 h, and 9 h after LPS injection. Serum and liver sections were collected for further analysis. Survival was improved by EDA in a dose-dependent manner up to 3 mg/kg, and maximum effects were observed at a dose of 3 mg/kg. After LPS injection, alanine aminotransferase levels increased significantly to about 1,250 IU/l in the vehicle-treated group, whereas values were blunted by about 80% by EDA. Furthermore, increases in 4-hydroxynonenal-modified proteins were also blunted in the liver by EDA. Moreover, mRNA expressions of macrophage infiltrating protein-2, monocyte chemoattractant protein (MCP)-1 and MCP-5 were attenuated by EDA. As a result, increases in the number of infiltrating inflammatory cells and mRNA expression of inflammatory cytokines such as tumor necrosis factor-alpha and interleukin-6 were significantly blunted in the liver by EDA. This reduction was accompanied by a significant reduction of their serum levels. In conclusion, EDA prevented liver injury by both inhibition of recruitments of inflammatory cells and expression of inflammatory cytokine levels in the liver.

Recent insights into the role of the innate immune system in the development of alcoholic liver disease

The innate immune system is responsible for the rapid, initial response of the organism to potentially dangerous stresses, including pathogens, tissue injury, and malignancy. Pattern-recognition receptors of the toll-like receptor (TLR) family expressed by macrophages provide a first line of defense against microbial invasion. Activation of these receptors results in a stimulus-specific expression of genes required to control the infection, including the production of inflammatory cytokines and chemokines, followed by the recruitment of neutrophils to the site of infection. The early stages in the development of alcoholic liver disease (ALD) follow a pattern characteristic of an innate immune response. Kupffer cells, the resident macrophages in the liver, are activated in response to bacterial endotoxins (lipopolysaccharide, LPS), leading to the production of inflammatory and fibrogenic cytokines, reactive oxygen species, as well as the recruitment of neutrophils to the liver. One mechanism by which chronic ethanol can turn the highly regulated innate immune response into a pathway of disease is by disrupting the signal transduction cascades mediating the innate immune response. Recent studies have identified specific modules in the TLR-4 signaling cascade that are disrupted after chronic ethanol exposure, including CD14 and the mitogen-activated protein kinase family members, ERK1/2 and p38. Enhanced activation of these TLR-4 dependent signaling pathways after chronic ethanol likely contributes to the development of alcoholic liver disease.

Acute ethanol binge followed by withdrawal regulates production of reactive oxygen species and cytokine-induced neutrophil chemoattractant and liver injury during reperfusion after hepatic ischemia

This work tests the hypothesis that withdrawal from an acute ethanol binge regulates the production of reactive oxygen species (ROS) and chemokines by Kupffer cells, and as a result compromises or protects the liver from injury. Male Sprague-Dawley rats received an intravenous ethanol bolus (1.75 g/kg), followed by an intravenous infusion of 200-300 mg/kg/h for 12 h. At 12 h, ethanol infusion was stopped and replaced by saline. At 18 h, rats were subjected to 45 min of partial hepatic ischemia, followed by 0-24 h of reperfusion (I/R). At specific time points, Kupffer cells were isolated for superoxide anion assay and CINC (cytokine-induced neutrophil chemoattractant) and MIP-2 (macrophage inflammatory protein-2) production in vitro. Alanine transferase (ALT) activity, endotoxin, CINC, and MIP-2 were measured in serum samples taken at appropriate intervals. Results show that at 3 h post reperfusion, serum ALT was significantly elevated in the ethanol-treated group + I/R, compared with the saline + I/R group. ROS production by Kupffer cells at this time was also significantly increased compared with the saline + I/R group. However, ethanol withdrawal + I/R did not significantly alter CINC and MIP-2 production at 3 h of reperfusion. After 24 h, serum ALT was lower in the ethanol + I/R group than in the saline + I/R group. Superoxide anion and MIP-2 releases by Kupffer cells were not statistically significantly different between these two groups at this time. CINC production by Kupffer cells from the ethanol-treated + I/R group was significantly lower than in the saline + I/R group. Concomitantly, CINC and nuclear factor-kappaB (NF-kappaB) mRNAs and NF-kappaB translocation and binding in Kupffer cells in this treatment group were down-regulated. Moreover, the number of polymorphonuclear neutrophils (PMNs) sequestered in the liver was significantly lower in the ethanol + I/R group than in the saline-treated group. ROS and chemokine productions in sham animals with or without ethanol were lower than in the I/R group. These data suggest that acute ethanol binge followed by withdrawal may compromise the liver to injury during the early phase, whereas in the later phase it may be protective. Furthermore, these results support the notion that Kupffer cells are involved in hepatic injury in the early phase, whereas PMNs participate more actively during the later phase of reperfusion.

Acute ethanol administration downregulates human immunodeficiency virus-1 glycoprotein 120-induced KC and RANTES production by murine Kupffer cells and splenocytes

Glycoprotein 120 from HIV-1, HIV-2 and SIV is known to stimulate secretion of chemokines by mononuclear cells. Thus, this work tests the hypothesis that acute ethanol intoxication suppresses HIV-1 gp120-induced chemokine production by murine Kupffer cells and splenocytes. Male Balb/c mice were given ethanol (1.70 g/Kg) by intragastric gavage in 0.1 ml volume of saline. Five minutes after ethanol administration, mice received an intravenous injection of HIV-1 gp120 (5 microg/Kg). After 24 hr, serum samples, splenocytes and Kupffer cells were obtained. Isolated cells were cultured in DMEM for 24 hr to determine production of chemokines and cytokines in vitro. Chemokines (MIP-2, KC, RANTES, MIP-1 alpha and MCP-1) and cytokines (IL-1 beta, TNF alpha, IL-10, gamma-IFN) were measured by ELISA. M-RNA abundance of these mediators was determined by RT-PCR. Results show that HIV-1 gp120 treatment was associated with significant elevations in serum KC and RANTES. No changes were observed with regard to other chemokines and cytokines. Oral administration of ethanol significantly suppressed HIV-1gp120-induced KC and RANTES release. KC and RANTES-mRNA expression and protein release by splenocytes and Kupffer cells were up-regulated by HIV-1 gp120. Such up-regulation was attenuated by ethanol treatment. These data show that acute ethanol administration attenuates HIV-1 gp120-induced chemokine release in vivo by isolated splenocytes and Kupffer cells. Through this mechanism, previous in vivo ethanol use may compromise the ability of HIV-1 gp120 to induce chemokine-mediated inhibition of HIV-1 entry into target cells.

Neutrophilic infiltration in alcoholic hepatitis

Leukocyte infiltration in the liver is one of the most important features of alcoholic liver disease. However, in alcoholic hepatitis, the role of polymorphonuclear neutrophils (PMNs) in liver injury still remains to be fully elucidated. Furthermore, the migration of PMNs and their presence in the liver during alcoholic hepatitis have not been fully investigated. Up-regulation of chemokine secretion and adhesion molecule expression on effector cells (i.e., PMNs) and target cells (i.e., hepatocytes) are important factors in neutrophilic infiltration of the liver. The CXC chemokines--that is, interleukin (IL)-8 (in human beings), cytokine-induced neutrophil chemoattractant (CINC) (in rats), and KC (in mice)--are proneutrophilic agents. They are up-regulated during chronic--that is, several years of--alcohol use in human beings and in up to 30 weeks in experimental models of ethanol intoxication in mice and rats. Up-regulation of these chemokines in the circulation and tissues is also associated with enhanced neutrophilic infiltration in the liver. In the rat, the up-regulation of CXC chemokine production is time dependent. For example, after 16 weeks of feeding, up-regulation of CXC chemokine is observed, whereas after 32 weeks, CC chemokines are enhanced. Concomitantly, selective migration of PMNs and mononuclear cells is observed. In another model, in which both CXC and CC chemokines were enhanced after chronic ethanol use for 12 weeks in mice, neutrophilic and mononuclear/lymphocytic infiltrations were also seen. This model correlates closely with alcoholic hepatitis in human beings, characterized by increased IL-8, RANTES (regulated upon activation, normal T cell expressed and secreted), and macrophage inflammatory protein-1 (MIP-1) and profound increases in neutrophils and lymphocytes in the liver.

Chronic ethanol intoxication enhances the production of cytokine-induced neutrophil chemoattractant and macrophage inflammatory protein-2 by hepatocytes after human immunodeficiency virus-1 glycoprotein 120 vaccination

Chemokines are implicated in the pathogenesis of alcoholic liver disease and human immunodeficiency virus-1 (HIV-1) infection. Thus, this work examined the regulation of chemokines --i.e., cytokine-induced neutrophil chemoattractant (CINC) and macrophage inflammatory protein-2 (MIP-2)--produced by hepatocytes after HIV-1 glycoprotein 120 (gp120) vaccination in Wistar rats fed with ethanol for 30 weeks. HIV-1 gp120 in complete Freund's adjuvant was given by intrainguinal route at a dose of 5 g/kg, followed by two booster shots in incomplete Freund's adjuvant at a weekly interval. Samples were taken 1 week after the last injection was given. Results show that anti-HIV-1 gp120 antibody titer was suppressed by 40% in the ethanol-fed rats, compared with findings in the parallel controls. However, serum CINC and MIP-2 levels were more elevated in the ethanol-fed rats than in the pair-fed group. The likely sources of these chemokines are the hepatocytes. After HIV-1 gp120 treatment, isolated hepatocytes obtained from the ethanol-fed group produced more CINC and MIP-2 than did those of pair-fed rats. Concomitantly, mRNA expression for these two chemokines and hepatic sequestration of neutrophils were upregulated. Ethanol feeding alone suppressed chemokine release, but it did not alter mRNA expression in isolated hepatocytes. Administration of Freund's adjuvant (without HIV-1 gp120) did not induce chemokine release in vivo and did not prime isolated hepatocytes for enhanced chemokine production in vitro. These results show that chronic ethanol intoxication affects the ability of the host to respond to HIV-1 gp120 vaccination.

Prooxidant and antioxidant functions of nitric oxide in liver toxicity

In response to tissue damage and inflammation induced by a variety of xenobiotics including acetaminophen, carbon tetrachloride, ethanol, galactosamine, and endotoxin, as well as disease states such as viral hepatitis, and postischemic and regenerative injury, the liver produces large quantities of nitric oxide. Indeed, nearly all cell types in the liver including hepatocytes, Kupffer cells, stellate cells, and endothelial cells have the capacity to generate nitric oxide. Thus, these cells, as well as infiltrating leukocytes, may indirectly augment tissue injury. In many models of liver damage, nitric oxide and its oxidation products such as peroxynitrite contribute to the injury process by directly damaging the tissue or by initiating additional immunologic reactions that result in damage. In some models, nitric oxide donors or peroxynitrite can mimic the cytotoxic actions of liver toxins. Moreover, agents that prevent the generation of nitric oxide or antioxidants that bind reactive nitrogen intermediates, or knockout mice with reduced capacity to produce nitric oxide, are protected from xenobiotic-induced tissue injury. In contrast, there have been reports that blocking nitric oxide production enhances xenobiotic-induced tissue injury. This has led to the concept that nitric oxide either inactivates proteins critical for xenobiotic-induced tissue injury or acts as an antioxidant, reducing cellular levels of cytotoxic reactive oxygen intermediates. Whether or not nitric oxide or secondary oxidants generated from nitric oxide act as mediators of tissue injury or protect against toxicity is likely to depend on the precise targets of these reactive nitrogen intermediates, as well as levels of superoxide anion present and the extent to which tissue injury is mediated by reactive oxygen intermediates. In addition, as toxicity is a complex process involving a variety of cell types and many soluble mediators, the contribution of each of these factors must be taken into account when considering the role of nitric oxide as a determinant of tissue injury.

Impact of alcohol on the ability of Kupffer cells to produce chemokines and its role in alcoholic liver disease

Chemokines are implicated in the pathogenesis of alcoholic liver disease in humans and in experimental models of alcohol intoxication. The major sources of these chemokines are Kupffer cells which represent more than 80% of tissue macrophages in the body. Kupffer cells are highly responsive to the effects of ethanol, endotoxin and human immunodeficiency virus (HIV)-1 glycoprotein120. These agents, either independently or in combination, may exacerbate the production of chemokines. Chemokines are agents that are highly chemotactic to mononuclear cells and granulocytes. The levels of these chemokines in sera and tissue are elevated in patients with alcoholic hepatitis, alcoholic cirrhosis, diseased livers, viral hepatitis, and in experimental models of chronic alcohol intoxication. Alcohol-induced influx of endotoxin from the gut into the portal circulation is suggested to play an important role in the activation of Kupffer cells which leads to enhanced chemokine release. The up-regulation of chemokines during alcohol consumption is selective. During the early phase of alcoholic liver disease, C-X-C or alpha-chemokines predominate. This is also associated with neutrophilic infiltration of the liver. In the later stage, up-regulation of C-C or beta-chemokine production and migration of mononuclear cells into the liver are observed, and this may lead to liver cirrhosis. Selective up-regulation of chemokine synthesis and release may involve differential modulation of the transcription factors required for chemokine gene expression. Increased cytokine release following alcohol consumption may also regulate chemokine secretion in Kupffer cells via paracrine and autocrine mechanisms and vice versa. In addition, infection with HIV-1 may further compromise the liver to more damage. During HIV-1 infection, a pre-existing liver disease superimposed on chronic alcohol consumption may also exacerbate HIV-1 replication and lymphocytic infiltration in the liver, because of the ability of HIV-1 gp120 to stimulate chemokine production by Kupffer cells and stimulate migration of inflammatory leucocytes in the liver.