Dilinoleoylphosphatidylcholine decreases LPS-induced TNF-alpha generation in Kupffer cells of ethanol-fed rats: respective roles of MAPKs and NF-kappaB

Polyene phosphatidylcholine promotes tibial fracture healing in rats by stimulating angiogenesis dominated by the VEGFA/VEGFR2 signaling pathway

One of the factors that predispose to fractures is liver damage. Interestingly, fractures are sometimes accompanied by abnormal liver function. Polyene phosphatidylcholine (PPC) is an important liver repair drug. We wondered if PPC had a role in promoting fracture healing. A rat model of tibial fracture was developed using the modified Einhorn model method. X-rays were used to detect the progression of fracture healing. Progress of ossification and angiogenesis at the fracture site were analyzed by Safranin O/fast green staining and CD31 immunohistochemistry. To investigate whether PPC has a direct angiogenesis effect, HUVECs were used. We performed MTT, wound healing, Transwell migration, and tube formation assays. Finally, RT-qPCR and Western blot analysis were used to study the underlying mechanism. The results showed that PPC significantly shortened the apparent recovery time of mobility in rats. PPC treatment significantly promoted the formation of cartilage callus, endochondral ossification, and angiogenesis at the fracture site. In vitro, PPC promoted the proliferative viability of HUVECs, their ability to heal wounds, and their ability to penetrate membranes in the Transwell apparatus and increased the tube formation of cells. The transcription of VEGFA, VEGFR2, PLCγ, RAS, ERK1/2 and MEK1/2 was significantly up regulated by PPC. Further, the protein level results demonstrated a significant increase in the expression of VEGFA, VEGFR2, MEK1/2, and ERK1/2 proteins. In conclusion, our findings suggest that PPC promotes angiogenesis by activating the VEGFA/VEGFR2 and downstream signaling pathway, thereby accelerating fracture healing.

Soybean polyenylphosphatidylcholine (PPC) is beneficial in liver and extrahepatic tissue injury: An update in experimental research

Polyenylphosphatidylcholine (PPC) is a purified polyunsaturated phosphatidylcholine extract of soybeans. This article updates PPC's beneficial effects on various forms of liver cell injury and other tissues in experimental research. PPC downregulates hepatocyte CYP2E1 expression and associated hepatotoxicity, as well as attenuates oxidative stress, apoptosis, lipoprotein oxidation and steatosis in alcoholic and nonalcoholic liver injury. PPC inhibits pro-inflammatory cytokine production, while stimulating anti-inflammatory cytokine secretion in ethanol or lipopolysaccharide-stimulated Kupffer cells/macrophages. It promotes M2-type macrophage polarization and metabolic reprogramming of glucose and lipid metabolism. PPC mitigates steatosis in NAFLD through inhibiting polarization of pro-inflammatory M1-type Kupffer cells, alleviating metabolic inflammation, remodeling hepatic lipid metabolism, correcting imbalances between lipogenesis and lipolysis and enhancing lipoprotein secretion from hepatocytes. PPC is antifibrotic by preventing progression of alcoholic hepatic fibrosis in baboons and also prevents CCl4-induced fibrosis in rats. PPC supplementation replenishes the phosphatidylcholine content of damaged cell membranes, resulting in increased membrane fluidity and functioning. Phosphatidylcholine repletion prevents increased membrane curvature of the endoplasmic reticulum and Golgi and decreases sterol regulatory element binding protein-1-mediated lipogenesis, reducing steatosis. PPC remodels gut microbiota and affects hepatic lipid metabolism via the gut-hepatic-axis and also alleviates brain inflammatory responses and cognitive impairment via the gut-brain-axis. Additionally, PPC protects extrahepatic tissues from injury caused by various toxic compounds by reducing oxidative stress, inflammation, and membrane damage. It also stimulates liver regeneration, enhances sensitivity of cancer cells to radiotherapy/chemotherapy, and inhibits experimental hepatocarcinogenesis. PPC's beneficial effects justify it as a supportive treatment of liver disease.

Integrative lipidomic features identify plasma lipid signatures in chronic urticaria

Chronic urticaria (CU) is a chronic inflammatory skin disease mainly mediated by mast cells. Lipids exert essential functions in biological processes; however, the role of lipids in CU remains unclear. Nontargeted lipidomics was performed to investigate the differential lipid profiles between CU patients and healthy control (HC) subjects. Functional validation studies were performed in vitro and in vivo including β-hexosaminidase release examination from mast cells and passive cutaneous anaphylaxis (PCA) mouse model. We detected dramatically altered glycerophospholipids in CU patients compared with HCs. Phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) were increased, while phosphatidylcholine (PC) was reduced in CU patients. The reduction in PC was related to a high weekly urticaria activity score (UAS7), while PS was positively associated with the dermatology life quality index (DLQI). We also identified the differential lipid profiles between chronic spontaneous urticaria (CSU), symptomatic dermographism (SD), and CSU coexist with SD. CU patients were classified into two subtypes (subtype 1 and subtype 2) based on consensus clustering of lipid profiling. Compared with patients in subtype 2, patients in subtype 1 had elevated levels of PC (18:0e/18:2) and PE (38:2), and lower urticaria control test (UCT) scores indicated worse clinical efficiency of secondary generation H1 antihistamines treatment. Importantly, we found that supplementation with PC could attenuate IgE-induced immune responses in mast cells. In general, We described the landscape of plasma lipid alterations in CU patients and provided novel insights into the role of PC in mast cells.

Therapeutic potential of garlic chive-derived vesicle-like nanoparticles in NLRP3 inflammasome-mediated inflammatory diseases

Aberrant activation of the nucleotide-binding domain and leucine-rich repeat related (NLR) family, pyrin domain containing 3 (NLRP3) inflammasome drives the development of many complex inflammatory diseases, such as obesity, Alzheimer's disease, and atherosclerosis. However, no medications specifically targeting the NLRP3 inflammasome have become clinically available. Therefore, we aim to identify new inhibitors of the NLRP3 inflammasome in this study. Methods: Vesicle-like nanoparticles (VLNs) were extracted from garlic chives and other Allium vegetables and their effects on the NLRP3 inflammasome were evaluated in primary macrophages. After garlic chive-derived VLNs (GC-VLNs) were found to exhibit potent anti-NLRP3 inflammasome activity in cell culture, such function was further assessed in a murine acute liver injury disease model, as well as in diet-induced obesity. Finally, GC-VLNs were subjected to omics analysis to identify the active components with anti-NLRP3 inflammasome function. Results: GC-VLNs are membrane-enclosed nanoparticles containing lipids, proteins, and RNAs. They dose-dependently inhibit pathways downstream of NLRP3 inflammasome activation, including caspase-1 autocleavage, cytokine release, and pyroptotic cell death in primary macrophages. The inhibitory effects of GC-VLNs on the NLRP3 inflammasome are specific, considering their marginal impact on activation of other inflammasomes. Local administration of GC-VLNs in mice alleviates NLRP3 inflammasome-mediated inflammation in chemical-induced acute liver injury. When administered orally or intravenously, GC-VLNs accumulate in specific tissues and suppress activation of the NLRP3 inflammasome and chronic inflammation in diet-induced obese mice. The phospholipid 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC) in GC-VLNs has been identified to inhibit NLRP3 inflammasome activation. Conclusions: Identification of GC-VLNs and their active component DLPC as potent inflammasome inhibitors provides new therapeutic candidates in the treatment of NLRP3 inflammasome-driven diseases.

Therapeutic targets, novel drugs, and delivery systems for diabetes associated NAFLD and liver fibrosis

Type 2 diabetes mellitus (T2DM) associated non-alcoholic fatty liver disease (NAFLD) is the fourth-leading cause of death. Hyperglycemia induces various complications, including nephropathy, cirrhosis and eventually hepatocellular carcinoma (HCC). There are several etiological factors leading to liver disease development, which involve insulin resistance and oxidative stress. Free fatty acid (FFA) accumulation in the liver exerts oxidative and endoplasmic reticulum (ER) stresses. Hepatocyte injury induces release of inflammatory cytokines from Kupffer cells (KCs), which are responsible for activating hepatic stellate cells (HSCs). In this review, we will discuss various molecular targets for treating chronic liver diseases, including homeostasis of FFA, lipid metabolism, and decrease in hepatocyte apoptosis, role of growth factors, and regulation of epithelial-to-mesenchymal transition (EMT) and HSC activation. This review will also critically assess different strategies to enhance drug delivery to different cell types. Targeting nanocarriers to specific liver cell types have the potential to increase efficacy and suppress off-target effects.

Targeted treatment of alcoholic liver disease based on inflammatory signalling pathways

Targeted therapy is an emerging treatment strategy for alcoholic liver disease (ALD). Inflammation plays an important role in the occurrence and development of ALD, and is a key choice for its targeted treatment, and anti-inflammatory treatment has been considered beneficial for liver disease. Surprisingly, immune checkpoint inhibitors have become important therapeutic agents for hepatocellular carcinoma (HCC). Moreover, studies have shown that the combination of inflammatory molecule inhibitors and immune checkpoint inhibitors can exert better effects than either alone in mouse models of HCC. This review discusses the mechanism of hepatic ethanol metabolism and the conditions under which inflammation occurs. In addition, we focus on the potential molecular targets in inflammatory signalling pathways and summarize the potential targeted inhibitors and immune checkpoint inhibitors, providing a theoretical basis for the targeted treatment of ALD and the development of new combination therapy strategies for HCC.

cis-4-[18F]fluoro-L-proline Molecular Imaging Experimental Liver Fibrosis

Introduction: Early-stage liver fibrosis is potentially reversible, but difficult to diagnose. Clinical management would be enhanced by the development of a non-invasive imaging technique able to identify hepatic injury early, before end-stage fibrosis ensues. The analog of the amino acid proline, cis-4-[¹⁸F]fluoro-L-proline ([¹⁸F]fluoro-proline), which targets collagenogenesis in hepatic stellate cells (HSC), was used to detect fibrosis.

Methods: Acute steatohepatitis was induced in experimental animals by liquid ethanol diet for 8 weeks, intra-gastric binge feedings every 10th day along with lipopolysaccharide (LPS) injection. The control animals received control diet for 8 weeks and an equivalent volume of saline on the same schedule as the acute steatohepatitis model. First, in vitro cellular experiments were carried out to assess [³H]proline uptake by HSC, hepatocytes and Kupffer cells derived from rats with acute steatohepatitis (n = 14) and controls (n = 14). Next, ex vivo liver experiments were done to investigate unlabeled proline-mediated collagen synthesis and its associated proline transporter expression in acute steatohepatitis (n = 5) and controls (n = 5). Last, in vivo dynamic and static [¹⁸F]fluoro-proline micro-PET/CT imaging was performed in animal models of acute steatohepatitis (n = 7) and control (n = 7) mice.

Results: [³H]proline uptake was 5-fold higher in the HSCs of steatohepatitis rats than controls after incubation of up to 60 min. There was an excellent correlation between [³H]proline uptake and liver collagen expression (r-value > 0.90, p < 0.05). Subsequent liver tissue studies demonstrated 2–3-fold higher proline transporter expression in acute steatohepatitis animals than in controls, and proline-related collagen synthesis was blocked by this transporter inhibitor. In vivo micro-PET/CT studies with [¹⁸F]fluoro-proline showed 2–3-fold higher uptake in the livers of acute steatohepatitis mice than in controls. There was an excellent correlation between [¹⁸F]fluoro-proline uptake and liver collagen expression in the livers of acute steatohepatitis mice (r-value = 0.97, p < 0.001).

Conclusion: [¹⁸F]fluoro-proline localizes in the liver and correlates with collagenogenesis in acute steatohepatitis with a signal intensity that is sufficiently high to allow imaging with micro-PET/CT. Thus, [¹⁸F]fluoro-proline could serve as a PET imaging biomarker for detecting early-stage liver fibrosis.

Decreased Taurine and Creatine in the Thalamus May Relate to Behavioral Impairments in Ethanol-Fed Mice: A Pilot Study of Proton Magnetic Resonance Spectroscopy

Minimal hepatic encephalopathy (MHE) is highly prevalent, observed in up to 80% of patients with liver dysfunction. Minimal hepatic encephalopathy is defined as hepatic encephalopathy with cognitive deficits and no grossly evident neurologic abnormalities. Clinical management may be delayed due to the lack of in vivo quantitative methods needed to reveal changes in brain neurobiochemical biomarkers. To gain insight into the development of alcoholic liver disease–induced neurological dysfunction (NDF), a mouse model of late-stage alcoholic liver fibrosis (LALF) was used to investigate changes in neurochemical levels in the thalamus and hippocampus that relate to behavioral changes. Proton magnetic resonance spectroscopy of the brain and behavioral testing were performed to determine neurochemical alterations and their relationships to behavioral changes in LALF. Glutamine levels were higher in both the thalamus and hippocampus of alcohol-treated mice than in controls. Thalamic levels of taurine and creatine were significantly diminished and strongly correlated with alcohol-induced behavioral changes. Chronic long-term alcohol consumption gives rise to advanced liver fibrosis, neurochemical changes in the nuclei, and behavioral changes which may be linked to NDF. Magnetic resonance spectroscopy represents a sensitive and noninvasive measurement of pathological alterations in the brain, which may provide insight into the pathogenesis underlying the development of MHE.

Anti-inflammatory properties of ursodeoxycholyl lysophosphatidylethanolamide in endotoxin-mediated inflammatory liver injury

AIM

Endotoxin-mediated liver inflammation is a key component of many acute and chronic liver diseases contributing to liver damage, fibrosis and eventually organ failure. Here, we investigated ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), a synthetic bile acid-phospholipid conjugate regarding its anti-inflammatory and anti-fibrogenic properties.

METHODS

Anti-inflammatory properties of UDCA-LPE were evaluated in a mouse model of D-galactosamine/lipopolysaccharide (GalN/LPS)-induced acute liver injury, LPS treated RAW264.7 macrophages and murine primary Kupffer cells. Furthermore, anti-inflammatory and anti-fibrotic effects of UDCA-LPE were studied on primary hepatic stellate cells (HSC) incubated with supernatant from LPS±UDCA-LPE treated RAW264.7 cells.

RESULTS

UDCA-LPE ameliorated LPS-induced increase of IL-6, TNF-α, TGF-β, NOX-2 in the GalN/LPS model by up to 80.2% for IL-6. Similarly, UDCA-LPE markedly decreased the expression of inflammatory cytokines IL-6, TNF-α and TGF-β as well as the chemokines MCP1 and RANTES in LPS-stimulated RAW 264.7 cells. Anti-inflammatory effects were also observed in primary murine Kupffer cells. Mechanistic evaluation revealed a reversion of LPS-activated pro-inflammatory TLR4 pathway by UDCA-LPE. Moreover, UDCA-LPE inhibited iNOS and NOX-2 expression while activating eNOS via phosphorylation of AKT and pERK1/2 in RAW264.7 cells. HSC treated with conditioned medium from LPS±UDCA-LPE RAW264.7 cells showed lower fibrogenic activation due to less SMAD2/3 phosphorylation, reduced expression of profibrogenic CTGF and reduced pro-inflammatory chemokine expression.

CONCLUSION

In the setting of endotoxin-mediated liver inflammation, UDCA-LPE exerts profound anti-inflammatory and anti-fibrotic effect implying a promising potential for the drug candidate as an experimental approach for the treatment of acute and chronic liver diseases.

Ursodeoxycholyl Lysophosphatidylethanolamide Protects Against CD95/FAS-Induced Fulminant Hepatitis

Increased activation of CD95/Fas by Fas ligand in viral hepatitis and autoimmunity is involved in pathogenesis of fulminant hepatitis and liver failure. We designed a bile-acid phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE with LPE containing oleate at the sn-1) as a hepatoprotectant that was shown to protect against fulminant hepatitis induced by endotoxin. We herein further assessed the ability of UDCA-LPE to prevent death receptor CD95/Fas-induced fulminant hepatitis. C57BL/6 mice were intravenously administered with CD95/Fas agonistic monoclonal antibody (Jo-2) with or without 1 h pretreatment with 50 mg/kg UDCA-LPE. Jo-2 administration caused massive hepatocyte damage as seen by histology, and this was associated with a significant decrease in hepatic phosphatidylcholine (PC), lysoPC, and lysophosphatidylethanolamine levels. By histology, UDCA-LPE pretreatment improved hepatocyte damage and restored the loss of these phospholipids in part by a mechanism involving an inhibition of cytosolic phospholipaseA2 expression. Accordingly, Jo-2 treatment increased hepatic expression of cleaved caspase 8, caspase 3, and poly (ADP-Ribose) polymerase-1, and on the other hand decreased that of anti-apoptotic cellular FLICE-inhibitory protein. UDCA-LPE pretreatment was able to reverse all these changes. Moreover, UDCA-LPE attenuated inflammatory response by lowering the levels of Jo-2-induced proinflammatory cytokines TNF-α, IL-6, and IL-1β in liver and serum. UDCA-LPE was also able to decrease the levels of stimulated Th1/Th17 cytokines in Jo-2-primed isolated splenocytes. Taken together, UDCA-LPE exhibited potent anti-inflammatory effects against CD95/Fas-induced fulminant hepatitis.

Alcohol Modulation of the Postburn Hepatic Response

The widespread and rapidly increasing trend of binge drinking is accompanied by a concomitant rise in the prevalence of trauma patients under the influence of alcohol at the time of their injury. Epidemiological evidence suggests up to half of all adult burn patients are intoxicated at the time of admission, and the presence of alcohol is an independent risk factor for death in the early stages post burn. As the major site of alcohol metabolism and toxicity, the liver is a critical determinant of postburn outcome, and experimental evidence implies an injury threshold exists beyond which burn-induced hepatic derangement is observed. Alcohol may lower this threshold for postburn hepatic damage through a variety of mechanisms including modulation of extrahepatic events, alteration of the gut-liver axis, and changes in signaling pathways. The direct and indirect effects of alcohol may prime the liver for the second-hit of many overlapping physiologic responses to burn injury. In an effort to gain a deeper understanding of how alcohol potentiates postburn hepatic damage, the authors summarize possible mechanisms by which alcohol modulates the postburn hepatic response.

Root bark of Ulmus davidiana var. japonica restrains acute alcohol-induced hepatic steatosis onset in mice by inhibiting ROS accumulation

Alcohol-induced hepatic steatosis and inflammation are key drivers of alcohol-induced liver injury, mainly caused by oxidative stress. The roots bark of Ulmus davidiana var. japonica is well known for its substantial antioxidative and antitumorigenic potency. In this study, we examined whether this plant can ameliorate alcohol-induced liver injuries characterized by hepatic steatosis and inflammation through its antioxidative activity. C57BL/6J mice were treated with the root bark extract of Ulmus davidiana var. japonica (RUE; 100 mg of extract/kg bodyweight; oral gavage) and alcohol (1 g/kg of bodyweight; oral gavage) for 5 days. Markers of acute alcohol-induced hepatic steatosis were determined and putative molecular mechanisms responsible for the protection of RUE were investigated. RUE noticeably protected against alcohol-induced hepatic steatosis and inflammation. Reactive oxygen species (ROS), over-produced by alcohol, negatively orchestrated various signaling pathways involved in the lipid metabolism and inflammation. These pathways were restored through the ROS scavenging activity of RUE in the liver. In particular, the expression of lipogenic genes (e.g., SREBP-1, ACC, and FAS) and inflammatory cytokines (e.g., IL-1β, and NF-κB p65) significantly decreased with RUE treatment. Conversely, the expression of fatty acid oxidation-related genes (e.g., SIRT1, AMPKα, and PGC1α) were increased in mice treated with RUE. Thus, the results indicate that RUE counteracts and thus attenuates alcoholic hepatic steatosis onset in mice, possibly by suppressing ROS-mediated steatosis and inflammation.

Targeting inflammation for the treatment of alcoholic liver disease

Alcoholic liver disease (ALD) is a leading cause of chronic liver disease with a wide spectrum of manifestations including simple steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Liver injury in ALD is caused by chronic inflammation, which has been actively investigated as a therapeutic target for the treatment of ALD for over the last four decades. In this review, we summarize a wide variety of inflammatory mediators that have been shown to contribute to the pathogenesis of ALD, and discuss the therapeutic potential of these mediators for the treatment of ALD.

Alcohol, aging, and innate immunity

The global population is aging: in 2010, 8% of the population was older than 65 y, and that is expected to double to 16% by 2050. With advanced age comes a heightened prevalence of chronic diseases. Moreover, elderly humans fair worse after acute diseases, namely infection, leading to higher rates of infection-mediated mortality. Advanced age alters many aspects of both the innate and adaptive immune systems, leading to impaired responses to primary infection and poor development of immunologic memory. An often overlooked, yet increasingly common, behavior in older individuals is alcohol consumption. In fact, it has been estimated that >40% of older adults consume alcohol, and evidence reveals that >10% of this group is drinking more than the recommended limit by the National Institute on Alcohol Abuse and Alcoholism. Alcohol consumption, at any level, alters host immune responses, including changes in the number, phenotype, and function of innate and adaptive immune cells. Thus, understanding the effect of alcohol ingestion on the immune system of older individuals, who are already less capable of combating infection, merits further study. However, there is currently almost nothing known about how drinking alters innate immunity in older subjects, despite innate immune cells being critical for host defense, resolution of inflammation, and maintenance of immune homeostasis. Here, we review the effects of aging and alcohol consumption on innate immune cells independently and highlight the few studies that have examined the effects of alcohol ingestion in aged individuals.

LPS promote the odontoblastic differentiation of human dental pulp stem cells via MAPK signaling pathway

Human dental pulp stem cells (hDPSCs) show significant potential for exploitation in novel regeneration strategies, although lack of understanding of their responses to bacterial challenge constrains their application. The present study aimed to investigate whether lipopolysaccharide (LPS), the major pathogenic factor of Gram-negative bacteria, regulates the differentiation of hDPSCs and which intracellular signaling pathways may be involved. LPS treatment significantly promoted the differentiation of hDPSCs demonstrable by increased mineralized nodule formation and mRNA expression of several odontoblastic markers in a dose-dependent manner. While inhibition of TLR4, p38, and ERK signaling markedly antagonized LPS-mediated differentiation of hDPSCs. The inhibition of JNK and NF-κB signaling had no detectable effect on LPS activation of hDPSCs. LPS stimulation resulted in phosphorylation of NF-κB p65, IκB-α, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) in DPSCs in a time-dependent manner, which was markedly suppressed by their specific inhibitors, respectively. Data demonstrated that LPS promoted odontoblastic differentiation of hDPSCs via TLR4, ERK, and P38 MAPK signaling pathways, but not NF-κB signaling.

Protective effect of phosphatidylcholine on restoration of ethanol-injured hepatocytes related with caveolin-1

The absorption of phospholipid may improve the fluidity of membrane and enzyme activities. Phospholipids also play a role in promoting Caveolae formation and membrane synthesis. Caveolin-1 has a significant effect on signaling pathways involved in regulating cell proliferation and stress responsiveness. Thus, we can speculate that Caveolin-1 could affect the sense of environmental stress. We use Chang liver cell line to investigate the ability of Caveolin-1 to modulate the cellular response to ethanol injury. Caveolin-1 downregulate cells (Cav-1(-/-)) were established by stable transfecting with psiRNA-CAV1 plasmids, which were more sensitive to toxic effects of ethanol than the untransfected parental cells (WT). Releasing of ALT and electric conductivity were changed significantly in Cav-1(-/-) cells compared with WT. Caveolin-1 gene silencing could obviously down-regulate the activities of protein kinase C-α (PKC-α) and phospho-p42/44 MAP kinase, indicating cell proliferation and self-repairing abilities were inhibited. However, the levels of Caveolin-1 and PKC-α were increased by phosphatidylcholine administration. The results indicated that the inhibition of lipid peroxidation by phosphatidylcholine could lead to the prevention of membrane disruption, which closely correlated with the level of Caveolin-1. Since the protective effects of phosphatidylcholine against ethanol-induced lipid peroxidation might be regulated by phospholipid-PKC-α signaling pathway, related with Caveolin-1, the potential effects of phosphatidylcholine on membranes need to be verified.

Role of oxidative stress in the pathogenesis of alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease, which represents a major cause of morbidity and mortality worldwide. The pathological process of alcohol-induced liver disease is characterized by a broad spectrum of morphological changes ranging from steatosis with minimal injury to more advanced liver damage, including steato-hepatitis and fibrosis/cirrhosis. Experimental and clinical studies increasingly show that the oxidative damage induced by ethanol contribute in many ways to the pathogenesis of alcohol hepatotoxicity. This article describes the contribution of oxidative mechanisms to liver damage by alcohol.

Cytochrome P4502E1 inhibitor, chlormethiazole, decreases lipopolysaccharide-induced inflammation in rat Kupffer cells with ethanol treatment

AIM

To investigate the role of Cytochrome P4502E1 in sensitizing Kupffer cells to lipopolysaccharide (LPS)-mediated inflammation after ethanol induction.

METHODS

Sprague-Dawley rats were fed a liquid ethanol diet, control diet or ethanol diet supplemented with CYP2E1 inhibitor, chlormethiazole (CMZ), for 4 weeks. Hepatic CYP2E1 protein, nuclear factor-kappa B (NF-κB) p65 protein and tumor necrosis factor (TNF)-α mRNA were measured. In vitro, isolated Kupffer cells from control rats were exposed to ethanol with different CMZ concentration; CYP2E1 expression and reactive oxygen species (ROS) generation were compared. The identified CMZ concentration was further utilized to evaluate the role of CYP2E1 on the sensitization of ethanol-induced Kupffer cell to LPS. The effect of LPS alone was tested in controlled Kupffer cells without ethanol. TNF-α, nuclear NF-κB p65 and cytoplasm IκB-α were monitored for all groups.

RESULTS

Ethanol feeding increased hepatic CYP2E1 level, nuclear accumulation of NF-κB p65 and TNF-α expression in rats. These changes were inhibited by CMZ supplementation. In cultured Kupffer cells, increased CYP2E1 content and ROS production by in vitro ethanol induction were dose-dependently inhibited by CMZ. Compared with LPS alone, the ethanol induction group produced significantly more TNF-α, nuclear NF-κB p65 and less cytoplasm IκB-α under LPS stimuli. CMZ abolished the effects of ethanol on LPS-stimulated NF-κB translocation and TNF-α generation in Kupffer cells.

CONCLUSION

In cultured Kupffer cell, using CMZ as inhibitor, ethanol-induced CYP2E1 overexpression was proved to contribute to the sensitization of Kupffer cells to LPS stimuli, with amplification of ROS production and activation of NF-κB, resulting in increased TNF-α production.

Dietary phosphatidylinositol protects C57BL/6 mice from concanavalin A-induced liver injury by modulating immune cell functions

SCOPE

Several recent studies have demonstrated that phospholipids (PLs) supplementation can modulate the function of cultured-immune cells. Furthermore, dietary PLs have been shown to ameliorate inflammatory processes and immune responses in arthritic and diabetic murine models, respectively. Thus, the aim of this study was to examine the immune-modulating activities of dietary soybean PLs in mice, with particular emphasis on the immune cell functions.

METHODS AND RESULTS

Mice were fed semisynthetic diets for 6 weeks, which contained either 7% soybean oil or 5% soybean oil plus 2% of either PL: phosphatidylcholine (PC), phosphatidylinositol (PI), or phosphatidylserine (PS). Production of concanavalin A (Con A)-induced proinflammatory cytokines was significantly decreased in the splenocytes isolated from mice fed PI compared to other lipids. Supplementation of the diet with PI, but not with the other lipids, significantly suppressed the proinflammatory cytokine serum levels and the development of Con A-induced liver damages.

CONCLUSION

These observations suggest that dietary PI influenced immune functions, resulting in the prevention of pathogenesis and development of the liver injury in mice.

Arachidonic acid stimulates TNFα production in Kupffer cells via a reactive oxygen species-pERK1/2-Egr1-dependent mechanism

Kupffer cells are a key source of mediators of alcohol-induced liver damage such as reactive oxygen species, chemokines, growth factors, and eicosanoids. Since diets rich in polyunsaturated fatty acids are a requirement for the development of alcoholic liver disease, we hypothesized that polyunsaturated fatty acids could synergize with ethanol to promote Kupffer cell activation and TNFα production, hence, contributing to liver injury. Primary Kupffer cells from control and from ethanol-fed rats incubated with arachidonic acid showed similar proliferation rates than nontreated cells; however, arachidonic acid induced phenotypic changes, lipid peroxidation, hydroperoxides, and superoxide radical generation. Similar effects occurred in human Kupffer cells. These events were greater in Kupffer cells from ethanol-fed rats, and antioxidants and inhibitors of arachidonic acid metabolism prevented them. Arachidonic acid treatment increased NADPH oxidase activity. Inhibitors of NADPH oxidase and of arachidonic acid metabolism partially prevented the increase in oxidant stress. Upon arachidonic acid stimulation, there was a rapid and sustained increase in TNFα, which was greater in Kupffer cells from ethanol-fed rats than in Kupffer cells from control rats. Arachidonic acid induced ERK1/2 phosphorylation and nuclear translocation of early growth response-1 (Egr1), and ethanol synergized with arachidonic acid to promote this effect. PD98059, a mitogen extracellular kinase 1/2 inhibitor, and curcumin, an Egr1 inhibitor, blocked the arachidonic acid-mediated upregulation of TNFα in Kupffer cells. This study unveils the mechanism whereby arachidonic acid and ethanol increase TNFα production in Kupffer cells, thus contributing to alcoholic liver disease.

Effects of early administration of a novel anticholinergic drug on acute respiratory distress syndrome induced by sepsis

Background

Acute respiratory distress syndrome (ARDS) is the inflammatory disorder of the lung most commonly caused by sepsis. It was hypothesized that treating the lung with penehyclidine hydrochloride (PHC), a new type of hyoscyamus drug, early in the development of sepsis could diminish the lung dysfunction.

Material/Methods

Sprague-Dawley rats were divided into 4 groups: 1) a control group; 2) a sham-operated group; 3) a cecal ligation and puncture (CLP) group; 4) a PHC-treated group. One hour after CLP surgery, rats were either untreated or treated with PHC via intraperitoneal injection. Lung wet/dry weight ratio, bronchoalveolar lavage fluid (BALF), serum tumor necrosis factor (TNF-α), interleukin 6 (IL-6), interleukin 10 (IL-10), total nitrite/nitrate (NOx), superoxide dismutase (SOD), malondialdehyde (MDA) in lung tissues, and pulmonary functions were examined 24 hour after surgery. Another 60 rats were randomly assigned to 4 equal groups to observe survival status 96 hours after surgery.

Results

Treatment of PHC markedly decreased TNF-α, IL-6, NOx, SOD, MDA content, protein concentration in BALF, and lung wet/dry weight ratio and enhanced SOD activity (p<0.05), which are indicative of PHC-induced suppression in the pathogenesis of ARDS caused by sepsis. In comparison to group CLP/saline, plasma IL-10 level markedly increased in group CLP/PHC. In PHC-treated groups, the administered PHC had a significant protective effect on the lung dysfunction induced by sepsis.

Conclusions

We conclude that administration of PHC at the time of a systemic insult can protect the lung from the damaging effects of sepsis.

Activity of essential phospholipids (EPL) from soybean in liver diseases

Essential phospholipids (EPL) contain a highly purified extract of polyenylphosphatidylcholine (PPC) molecules from soybean. The main active ingredient is 1,2-dilinoleoylphosphatidylcholine (DLPC), which differentiates it from other phospholipids, lecithins, or extracts from other sources. Although EPLis widely used in liver diseases of various origins, its mode of action and pharmacological and clinical evidence of its efficacy have not yet been concisely reviewed. This paper critically summarizes experimental and clinical results. With regard to in-vitro and animal tests, EPL influenced membrane-dependent cellular functions and showed anti-oxidant, anti-inflammatory, anti-fibrotic, apoptosis-modulating, regenerative, membrane-repairing and -protective, cell-signaling and receptor-influencing, as well as lipid-regulating effects in intoxication models with chemicals or drugs. Clinical studies, primarily from European and Asian countries, have shown improvement in subjective symptoms; clinical, biochemical and imaging findings; and histology in liver indications such as fatty liver of different origin, drug hepatotoxicity, and adjuvant in chronic viral hepatitis and hepatic coma. The available studies characterize EPL as evidence-based medicine, although further long-term controlled clinical trials are required to precisely determine its benefit for alleviating symptoms, improving well-being, inducing histological changes and slowing the progression of liver disease. EPL-related relevant side effects were not observed.

Acetate, the key modulator of inflammatory responses in acute alcoholic hepatitis

Acute alcoholic hepatitis is characterized by disproportionate macrophage inflammatory cytokine responses to bacterial lipopolysaccharide. Lack of knowledge of the underlying mechanism has limited progress toward effective therapy. We postulated a novel mechanism by which ethanol increases histone acetylation, increasing proinflammatory gene transcription and cytokine synthesis. Cytokine responses to lipopolysaccharide in a human macrophage cell line cultured in 86 mM ethanol, 1 mM acetate, and normal media were measured by multiplex immunoassay. Changes in histone acetylation were determined by immunofluorescence microscopy and chromatin immunoprecipitation on presentation. The effect of ethanol and acetate on acetyl-coenzyme A (acetyl-coA) synthetases, which convert acetate to acetyl-coA, the substrate for histone acetylation, was determined by quantitative reverse-transcription polymerase chain reaction and immunoblotting. Knockdown of acetyl-coA synthetases by short hairpin RNA (shRNA) was used to determine their role in ethanol's enhancement of the inflammatory cytokine response. Ethanol-exposed macrophages developed enhanced interleukin 6 (IL6), IL8, and tumor necrosis factor alpha responses to lipopolysaccharide with time-dependent increases in histone acetylation that could be prevented by inhibition of ethanol metabolism. Chromatin immunoprecipitation confirmed increased histone acetylation at promoter regions of specific cytokine genes. The effect of ethanol was reproduced by incubation with acetate, the principal hepatic metabolite of ethanol, and both ethanol and acetate reduced histone deacetylase activity and up-regulated acetyl-coA synthetases. Knockdown of the acetyl-coA synthetases abrogated the effect of ethanol on cytokine production.

CONCLUSION

Synthesis of metabolically available acetyl-coA from acetate is critical to the increased acetylation of proinflammatory gene histones and consequent enhancement of the inflammatory response in ethanol-exposed macrophages. This mechanism is a potential therapeutic target in acute alcoholic hepatitis.

Dilinoleoylphosphatidylcholine induces the expression of the anti-inflammatory heme oxygenase-1 in RAW264.7 macrophages

1,2-Dilinoleoyl-sn-glycero-3-phosphocholine (DLPC), the main and active component of soybean lecithin, has been reported to exert anti-inflammatory effects, but the underlying mechanisms remain to be established. It was found that DLPC could induce the expression of the anti-inflammatory heme oxygenase-1 (HO-1) through the activation of nuclear erythroid 2-related factor 2 (Nrf2) in RAW264.7 macrophages. Pretreatment with DLPC suppressed the expression of inducible nitric oxide (NO) synthase (iNOS), one of proinflammatory enzymes, and reduced NO production in lipopolysaccharide (LPS)-stimulated macrophages. Similarly, DLPC also diminished the production of tumor necrosis factor-alpha (TNF-alpha), one of proinflammatory cytokines. Interestingly, the inhibitory effects of DLPC on LPS-induced iNOS expression and TNF-alpha production were reversed by tin protoporphyrin, a HO-1 inhibitor. Thus, HO-1 expression via Nrf2 activation may be one of the possible mechanisms explaining the anti-inflammatory effects of DLPC.

Anti-inflammatory pathways and alcoholic liver disease: Role of an adiponectin/interleukin-10/heme oxygenase-1 pathway

The development of alcoholic liver disease (ALD) is a complex process involving both the parenchymal and non-parenchymal cells in the liver. Enhanced inflammation in the liver during ethanol exposure is an important contributor to injury. Kupffer cells, the resident macrophages in liver, are particularly critical to the onset of ethanol-induced liver injury. Chronic ethanol exposure sensitizes Kupffer cells to activation by lipopolysaccharide via Toll-like receptor 4. This sensitization enhances production of inflammatory mediators, such as tumor necrosis factor-α and reactive oxygen species, that contribute to hepatocyte dysfunction, necrosis, apoptosis, and fibrosis. Impaired resolution of the inflammatory process probably also contributes to ALD. The resolution of inflammation is an active, highly coordinated response that can potentially be manipulated via therapeutic interventions to treat chronic inflammatory diseases. Recent studies have identified an adiponectin/interleukin-10/heme oxygenase-1 (HO-1) pathway that is profoundly effective in dampening the enhanced activation of innate immune responses in primary cultures of Kupffer cells, as well as in an in vivo mouse model of chronic ethanol feeding. Importantly, induction of HO-1 also reduces ethanol-induced hepatocellular apoptosis in this in vivo model. Based on these data, we hypothesize that the development of therapeutic agents to regulate HO-1 and its downstream targets could be useful in enhancing the resolution of inflammation during ALD and preventing progression of early stages of liver injury.

New insights into alcoholic pancreatitis and pancreatic cancer

Pancreatitis and pancreatic cancer represent two major diseases of the exocrine pancreas. Pancreatitis exhibits both acute and chronic manifestations. The commonest causes of acute pancreatitis are gallstones and alcohol abuse; the latter is also the predominant cause of chronic pancreatitis. Recent evidence indicates that endotoxinemia, which occurs in alcoholics due to increased gut permeability, may trigger overt necroinflammation of the pancreas in alcoholics and one that may also play a critical role in progression to chronic pancreatitis (acinar atrophy and fibrosis) via activation of pancreatic stellate cells (PSCs). Chronic pancreatitis is a major risk factor for the development of pancreatic cancer, which is the fourth leading cause of cancer-related deaths in humans. Increasing attention has been paid in recent years to the role of the stroma in pancreatic cancer progression. It is now well established that PSCs play a key role in the production of cancer stroma and that they interact closely with cancer cells to create a tumor facilitatory environment that stimulates local tumor growth and distant metastasis. This review summarizes recent advances in our understanding of the pathogenesis of alcoholic pancreatitis and pancreatic cancer, with particular reference to the central role played by PSCs in both diseases. An improved knowledge of PSC biology has the potential to provide an insight into pathways that may be therapeutically targeted to inhibit PSC activation, thereby inhibiting the development of fibrosis in chronic pancreatitis and interrupting stellate cell-cancer cell interactions so as to retard cancer progression.

Phospholipids block nuclear factor-kappa B and tau phosphorylation and inhibit amyloid-beta secretion in human neuroblastoma cells

Inflammation and oxidative stress have been shown to play a critical role in the pathophysiology that leads to neurodegeneration. Omega-6 phospholipids, e.g. dilinoleoylphosphatidylcholine (DLPC), have been shown to have anti-inflammatory properties and therefore experiments were undertaken to determine whether DLPC can prevent inflammatory neurodegenerative events in the model neuronal cell line, SH-SY5Y. Tumor necrosis factor (TNF-alpha) and H(2)O(2) activate mitogen-activated protein kinase (MAPK) in SH-SY5Y cells within 5 min and this activation is completely blocked by DLPC (12 microM). DLPC blocks IkappaBalpha phosphorylation in the SH-SY5Y cells and prevents the phosphorylation and activation of nuclear factor-kappa B (NF-kappaB). The phospholipid inhibits induction of MAPK and NF-kappaB in similar fashion to the MEK1/2-inhibitor, U0126 (10 microM). DLPC completely abolishes TNF-alpha, H(2)O(2) and lipopolysaccaride (LPS)-induced neuronal tau phosphorylation. Cellular amyloid precursor protein levels are reduced by DLPC and LPS-induced amyloid-beta expression and secretion in SH-SY5Y cells are completely blocked by DLPC. Taken together, these data suggest that DLPC can act through MAPK to block neuronal inflammatory cascades and prevent potential pathological consequences in the neuronal metabolism of amyloid and tau proteins.

Peroxisome proliferator-activated receptor and retinoic x receptor in alcoholic liver disease

A growing number of new studies demonstrate that nuclear receptors are involved in the development of alcoholic liver disease (ALD). Ethanol metabolism and RXR/PPAR functions are tightly interconnected in the liver. Several ethanol metabolizing enzymes are potently regulated by RXR and PPARα after alcohol consumption. The increased ethanol metabolism, in turn, leads to alteration of the redox balance of the cells and impairment of RXR/PPAR functions by direct and indirect effects of acetaldehyde, resulting in deranged lipid metabolism, oxidative stress, and release of proinflammatory cytokines. The use of animal models played a crucial role in understanding the molecular mechanisms of ALD. In this paper we summarize the reciprocal interactions between ethanol metabolism and RXR/PPAR functions. In conclusion, RXR and PPAR play a central role in the onset and perpetuation of the mechanisms underling all steps of the clinical progression in ALD.

Soy phosphatidylcholine inhibited TLR4-mediated MCP-1 expression in vascular cells

Inflammatory signaling via Toll-like receptor 4 (TLR4) has been shown to facilitate atherogenesis. Recent lines of evidence show that saturated fatty acids (SFAs) induce the inflammatory response via the TLR4 pathway in macrophages and adipocytes. The aims of this study are to confirm the role of SFAs in TLR4-mediated inflammatory signaling in vascular cells and to propose soy phosphatidylcholine (SPC) as an effective inhibitor against TLR4-mediated agonists. SFAs such as palmitate and stearate increased the expression and secretion of MCP-1 in human umbilical vein endothelial cells (HUVECs) and rat vascular smooth muscle cells (VSMCs). SFAs up-regulated the activity of MCP-1 promoter through the activation of NF-kappaB. Knockdown of TLR4 using siRNA diminished the SFA-induced MCP-1 expression in HUVECs and rat VSMCs, while PKC or ceramide signal inhibitor did not inhibit the expression. Furthermore, we found that SPC effectively inhibited the MCP-1 expression induced by palmitate or LPS in a dose-dependent manner. However, SPC did not inhibit the mRNA expression of MCP-1 induced by cytokines such as TNF-alpha and IL-1beta, or by agonists binding to TLRs other than TLR4. In addition, SPC did not affect the activity of LPS assessed by clotting activity of the Limulus amoebocyte lysate. These results clearly show that SPC specifically inhibits the inflammatory responses induced by the TLR4-dependent signal. In conclusion, we have demonstrated a role of SFAs for inflammatory response via TLR4-NF-kappaB signaling in vascular cells. Moreover, we propose that SPC can be useful as a selective inhibitor to suppress the TLR4-mediated inflammatory signaling.

Signalling pathways in alcohol-induced liver inflammation

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 NFkappaB, 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.

Role of SIRT1 in regulation of LPS- or two ethanol metabolites-induced TNF-alpha production in cultured macrophage cell lines

Dysregulation of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of alcoholic liver injury. Sirtuin 1 (SIRT1) is an NAD(+)-dependent class III protein deacetylase that is known to be involved in regulating production of proinflammatory cytokines including TNF-alpha. In the present study, we examined the role of SIRT1 signaling in TNF-alpha generation stimulated by either lipopolysaccharide (LPS), acetaldehyde (AcH), or acetate (two major metabolites of ethanol) in two cultured macrophage cell lines. In both rat Kupffer cell line 1 (RKC1) and murine RAW 264.7 macrophages, treatment with either LPS, AcH, or acetate caused significant decreases in SIRT1 transcription, translation, and activation, which essentially demonstrated an inverse relationship with TNF-alpha levels. LPS, AcH, and acetate each provoked the release of TNF-alpha from RKC1 cells, whereas coincubation with resveratrol (a potent SIRT1 agonist) inhibited this effect. Conversely, addition of sirtinol (a known SIRT1 inhibitor) or knocking down SIRT1 by the small silencing SIRT1 plasmid (SIRT1shRNA) augmented TNF-alpha release, suggesting that impairment of SIRT1 may contribute to TNF-alpha secretion. Further mechanistic studies revealed that inhibition of SIRT1 by LPS, AcH, or acetate was associated with a marked increase in the acetylation of the RelA/p65 subunit of nuclear transcription factor (NF-kappaB) and promotion of NF-kappaB transcriptional activity. Taken together, our findings suggest that SIRT1-NF-kappaB signaling is involved in regulating LPS- and metabolites-of-ethanol-mediated TNF-alpha production in rat Kupffer cells and in murine macrophages. Our study provides new insights into understanding the molecular mechanisms underlying the development of alcoholic steatohepatitis.

Protective effects of N-acetylcysteine and beta-glucan pretreatment on oxidative stress in cecal ligation and puncture model of sepsis

This study was designed to compare the effect of pretreatment with N-acetylcysteine (NAC) and beta -glucan (beta GLU) on inflammatory response in a rat model of sepsis. The study was performed in the animal laboratory of the Kahramanmaras Sutcu Imam University, School of Medicine. Forty rats were randomized into four groups (control, sham, NAC, and beta GLU). Control and Sham groups received saline or NAC (200 mg/kg, po) in the NAC group and beta GLU (50 mg/kg, po) in the betaGLU group via intragastric gavage once a day for 10 days and 30 min prior to surgery. Sepsis was induced by cecal ligation and puncture (CLP) in rats. In the NAC, beta GLU, and control groups, a laparotomy was performed with the CLP procedure. In the sham group, laparotomy was performed and cecum was manipulated but not ligated or perforated. TNF-alpha and IL-6 levels were significantly elevated in the control group and decreased in the NAC and beta GLU groups. IL-10 levels were significantly increased in the beta GLU group (p < .05). Superoxide dismutase and catalase levels in the liver tissue were significantly increased in the NAC and beta GLU groups, whereas superoxide dismutase levels were higher in the beta GLU pretreatment group than the NAC pretreatment group (p < 0.05). Malondialdehyde levels in the liver tissue were significantly elevated in the control group and decreased in the NAC and beta GLU groups (p < .05). Prophylactic administration of NAC or beta GLU similarly ameliorated sepsis syndrome by reduction of the proinflammatory cytokines and increase of the anti-inflammatory cytokine levels and accession of cellular antioxidants, which protect cells from oxidative stress, thereby recruiting inflammatory cells into tissue.

Phosphatidylcholine reverses ethanol-induced increase in transepithelial endotoxin permeability and abolishes transepithelial leukocyte activation

BACKGROUND

Chronic alcohol abuse increases both intestinal bacterial overgrowth and intestinal permeability to macromolecules. Intestinal permeability of endotoxin, a component of the outer cell membrane of Gram-negative bacteria, plays a crucial role in the development of alcohol-induced liver disease (ALD). As impaired bile flow leads to endotoxemia and the bile component phosphatidylcholine (PC) is therapeutically active in ALD, we tested the hypothesis that conjugated primary bile salts (CPBS) and PC inhibit ethanol-enhanced transepithelial permeability of endotoxin and the subsequent transepithelial activation of human leukocytes.

METHODS

For this purpose, we used a model in which intestinal epithelial cells (Caco-2) were basolaterally cocultivated with mononuclear leukocytes. Cells were challenged apically with endotoxin from Escherichia coli K12 and were incubated with or without the addition of CPBS (1.5 mM), PC (0.38 mM), pooled human bile (2%) in combination with ethanol (0 to 66 mM).

RESULTS

Ethanol decreased integrity of intestinal epithelial cell monolayer and enhanced transepithelial permeability of endotoxin. Both the transepithelial permeability of endotoxin and the transepithelial stimulation of leukocytes were nearly completely abolished after the apical supplementation of PC with CPBS, but not by CPBS alone. Ethanol up to 66 mM was not able to reverse this effect.

CONCLUSIONS

A considerable part of the therapeutic and preventive effect of PC supplementation in ALD might result from a reduction of ethanol-enhanced permeability of endotoxin through the intestinal barrier.

Inhibitory effect of olive oil on fibrosis induced by carbon tetrachloride in rat liver

BACKGROUND & AIMS

In this study, the inhibitory effect of olive oil on liver fibrosis induced by carbon tetrachloride (CCl(4)) has been investigated in rats.

METHODS

Rats were divided randomly into four groups: control, CCl(4), and two olive oil groups. Except for rats in the control group, all rats were orally administered CCl(4) twice a week for 8 weeks. Rats in the olive oil groups were treated daily with olive oil (2 or 10 ml/kg) through gastrogavage for the entire experimental period.

RESULTS

RT-PCR analysis showed that CCl(4) increased the hepatic mRNA expressions of lipopolysaccharide binding protein, CD14, Toll-like receptor-4, NADPH oxidase, nuclear factor-kappa beta, collagen (alpha1) (I), collagen (alpha1) (III), and transforming growth factor beta1. The expression of these mRNAs could be decreased by olive oil treatment. In addition, Western blot analysis also supported these results. CCl(4)-induced liver damage, as characterized by the increase in hepatic malondialdehyde and hydroxyproline levels. Olive oil treatment decreased the hepatic malondialdehyde and hydroxyproline levels. Histological evaluations showed that olive oil could attenuate the liver fibrosis, necrosis, and expression of smooth muscle alpha-actin that are induced by CCl(4).

CONCLUSION

It is speculated that the phenolic compounds in olive oil significantly reduced CCl(4)-induced hepatic fibrosis in rats.

Alcohol and lipid metabolism

Many new mechanisms for alcoholic steatosis have been suggested by work reported in the last five years. These include alterations of transcriptional controls of lipid metabolism, better understanding of the effects of abnormal methionine metabolism on the endoplasmic reticulum stress response, unraveling of the basis for sensitization of the Kupffer cell to lipopolysaccharide, a better understanding of the role of cytokines and adipokines in alcoholic liver disease, and implication of the innate immune and complement systems in responses to alcohol. Much of this work has been facilitated by work with knockout mice. Undoubtedly, there are interrelationships among these various pathogenic mechanisms that ultimately will provide a more cohesive picture of how heavy alcohol use deranges hepatic lipid metabolism.

Exposure-dependent effects of ethanol on the innate immune system

Extensive evidence indicates that ethanol (alcohol) has immunomodulatory properties. Many of its effects on innate immune response are dose dependent, with acute or moderate use associated with attenuated inflammatory responses, and heavy ethanol consumption linked with augmentation of inflammation. Ethanol may modify innate immunity via functional alterations of the cells of the innate immune system. Mounting evidence indicates that ethanol can diversely affect antigen recognition and intracellular signaling events, which include activation of mitogen activated protein kinases, and NFkappaB, mediated by Toll-like receptors, leading to altered inflammatory responses. The mechanism(s) underlying these changes may involve dose-dependent effects of ethanol on the fluidity of cell membrane, resulting in interference with the timely assembly or disassembly of lipid rafts. Ethanol could also modify cell activation by specific interactions with cell membrane molecules.

Regulation of macrophage activation in alcoholic liver disease

Chronic ethanol feeding sensitizes Kupffer cells to activation by lipopolysaccharide (LPS), leading to increased production of tumor necrosis factor alpha (TNFalpha). The regulation of TNFalpha synthesis is controlled by both transcriptional and post-transcriptional mechanisms via the integration of complex signal transduction pathways activated in response to LPS exposure. Recent data has shown that increased LPS-stimulated phosphorylation of extracellular signal-regulated kinase pathway 1/2 (ERK1/2) is one of the important molecular targets of chronic ethanol in Kupffer cells. This increased activation of ERK1/2 after chronic ethanol is associated with increased expression of Egr-1, a transcription factor required for enhanced LPS-stimulated TNFalpha mRNA expression after chronic ethanol exposure. egr-1 null mice are protected from the development of fatty liver injury in response to chronic ethanol feeding, identifying an essential role for Egr-1 in the development of chronic ethanol-induced liver injury. Here we review recent studies aimed at understanding the mechanisms by which chronic ethanol enhances the LPS-->ERK1/2-->Egr-1-->TNFalpha pathway in Kupffer cells. These studies identify a critical role for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species in the activation of ERK1/2 and subsequent production of TNFalpha in Kupffer cells after chronic ethanol feeding.

Attenuation of ureteral obstruction-induced renal injury by polyenylphosphatidylcholine

BACKGROUND

The cytoprotective, antioxidant and antifibrotic effects of polyenylphosphatidylcholine (lecithin, PPC) have been demonstrated both experimentally and clinically. The present study investigated whether PPC treatment has any beneficial effect on renal injury in unilateral partial ureteral obstruction (UUO) in rats.

METHODS

Forty Wistar-Albino rats were split into three groups (sham-operated controls, untreated and treated rats). Rats of the untreated and treated groups (n = 15) underwent UUO with two-thirds of the left ureter embedded in the psoas muscle. In group 3, PPC was given orally at a dose of 100 mg/day for 30 days. At the end of the 30th day of the experimental period, obstructed kidneys and blood samples were harvested. To investigate the therapeutic efficacy of PPC treatment in UUO kidneys, oxidant and antioxidant enzyme levels, lipid peroxidation, proinflammatory cytokines (interleukin-1, interleukin-6, tumor necrosis factor alpha), transforming growth factor beta-1 (TGFbeta-1), alpha smooth muscle actin (alpha-SMA) and nuclear factor kappa beta (NF-kappabeta) expression, leukocyte infiltration (ED1, ED2, CD4 and CD8 immunohistochemistry), and tubulointerstitial damage in the obstructed kidneys were studied.

RESULTS

Oxidative stress, neutrophil infiltration, release of cytotoxic mediators, TGFbeta-1 levels, tubulointerstitial damage, alpha-SMA and NF-KB expressions in kidney tissue were significantly increased in the UUO rats. PPC treatment attenuated oxidative stress, leukocyte infiltration, cytotoxic mediator, and TGFbeta-1 levels and also decreased expressions of alpha-SMA and NF-kappabeta. It was associated with decreased tubulointerstitial damage, compared with UUO alone.

CONCLUSIONS

These results indicate that PPC treatment protects against UUO-induced renal injury in rats possibly through its antioxidant, anti-inflammatory and antifibrotic actions.

Effects of a new bioactive lipid-based drug carrier on cultured hepatic stellate cells and liver fibrosis in bile duct-ligated rats

In the fibrotic liver, hepatic stellate cells (HSC) produce large amounts of collagen and secrete variety of mediators that promote development of fibrosis in this organ. Therefore, these cells are considered an attractive target for antifibrotic therapies. We incorporated the bioactive lipid dilinoleoylphosphatidylcholine (DLPC) into the membrane of liposomes, and then we evaluated its effect on hepatic stellate cell activation and liver fibrosis. To target DLPC-liposomes to HSC, human serum albumin modified with mannose 6-phosphate (M6P-HSA) was coupled to the surface of these liposomes. In vitro, the effects of the carrier were determined in primary cultures of HSC, Kupffer cells, and liver endothelial cells using real-time reverse transcription-polymerase chain reaction. In vivo DLPC-liposomes were tested in bile duct-ligated rats. Targeted M6P-HSA-DLPC-liposomes and DLPC-liposomes significantly reduced gene expression levels for collagen 1alpha1, alpha-smooth muscle actin (alpha-SMA), and transforming growth factor-beta (TGF-beta) in cultured HSC. In fibrotic livers, DLPC-liposomes decreased gene expression for TGF-beta and collagen 1alpha1 as well as alpha-SMA and collagen protein expression. In contrast, M6P-HSA-DLPC-liposomes enhanced expression of profibrotic and proinflammatory genes in vivo. In cultured Kupffer and endothelial cells M6P-HSA liposomes influenced the expression of proinflammatory genes. Both types of liposomes increased hepatocyte glycogen content in fibrotic livers, indicating improved functionality of the hepatocytes. We conclude that DLPC-containing liposomes attenuate activation of cultured HSC. In fibrotic livers, M6P-HSA-mediated activation of Kupffer and endothelial cells probably counteracts this beneficial effect of DLPC-liposomes. Therefore, these bioactive drug carriers modulate the activity of all liver cells during liver fibrosis.

NADPH oxidase is not an essential mediator of oxidative stress or liver injury in murine MCD diet-induced steatohepatitis

BACKGROUND/AIMS

Hepatic oxidative stress is a key feature of metabolic forms of steatohepatitis, but the sources of pro-oxidants are unclear. The NADPH oxidase complex is critical for ROS generation in inflammatory cells; loss of any one component (e.g., gp91phox) renders NADPH oxidase inactive. We tested whether activated inflammatory cells contribute to oxidant stress in steatohepatitis.

METHODS

gp91phox-/- and wildtype (wt) mice were fed a methionine and choline-deficient (MCD) diet. Serum ALT, hepatic triglycerides, histopathology, lipid peroxidation, activation of NF-kappaB, expression of NF-kappaB-regulated genes and macrophage chemokines were measured.

RESULTS

After 10 days of MCD dietary feeding, gp91phox-/- and wt mice displayed equivalent hepatocellular injury. After 8 weeks, there were fewer activated macrophages in livers of gp91phox-/- mice than controls, despite similar mRNA levels for MCP and MIP chemokines, but fibrosis was similar. NF-kappaB activation and increased expression of ICAM-1, TNF-alpha and COX-2 mRNA were evident in both genotypes, but in gp91phox-/- mice, expression of these genes was confined to hepatocytes.

CONCLUSIONS

A functional NADPH oxidase complex does not contribute importantly to oxidative stress in this model and therefore is not obligatory for induction or perpetuation of dietary steatohepatitis.

Regulation of Kupffer cell activity during chronic ethanol exposure: role of adiponectin

There is a growing appreciation that adipose tissue is a multifunctional organ. In addition to its central role in lipid storage, adipose tissue secretes a diverse group of proteins, called adipokines, involved in lipid metabolism, insulin sensitivity, angiogenesis etc. Adipocytes also secrete various inflammatory and anti-inflammatory mediators. Adiponectin, an adipokine with potent anti-inflammatory properties, is thought to play an important role in the regulation of inflammation. The development of alcoholic liver disease is thought to involve increased pro-inflammatory activity, mediated in part by the activation of Kupffer cells. Chronic ethanol feeding sensitizes Kupffer cells to activation by lipopolysaccharide (LPS), leading to increased production of reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-alpha). Recent studies have demonstrated a hepato-protective effect of adiponectin in the progression of alcoholic liver disease. Herein are summarized recent data demonstrating that adiponectin treatment can normalize LPS-stimulated ROS production and TNF-alpha expression in Kupffer cells after chronic ethanol feeding. These studies suggest that the hepato-protective activity of adiponectin is due, at least in part, to a direct anti-inflammatory effect of adiponectin on Kupffer cells.

Polyenylphosphatidylcholine pretreatment ameliorates ischemic acute renal injury in rats

AIM

Polyenylphosphatidycholine has been demonstrated to have antioxidant, cytoprotective and anti-inflammatory effects. Whether polyenylphosphatidycholine pretreatment affects ischemia/reperfusion-induced renal damage in vivo is not known and was investigated here in rats.

METHODS

Forty female Sprague-Dawley rats were divided into three groups. Group 1 (n = 10) was given saline (control, sham operated). Group 2 (n = 15) were given saline, and Group 3 (n = 15) were given polyenylphosphatidycholine (100 mg/day for 10 days prior to experiment). Groups 2 and 3 were subjected to bilateral renal ischemia (60 min) followed by reperfusion (6 h). After the reperfusion period, the rats were sacrificed and kidney tissue superoxide dismutase, glutathione, total nitrite and nitrate, malondialdehyde and myeloperoxidase levels, plasma aspartate aminotransferase, blood urea nitrogen and creatinine concentrations, and nuclear factor kappa beta expression were determined.

RESULTS

Serum levels of aspartate aminotransferase, blood urea nitrogen and creatinine were significantly decreased (P < 0.05) in the treatment group compared to those in the ischemic group. There were significant differences between treatment and ischemic groups regarding the tissue superoxide dismutase, glutathione, total nitrite and nitrate, malondialdehyde, and myeloperoxidase levels (P < 0.05). In addition, polyenylphosphatidycholine pretreatment reduced nuclear factor kappa beta expression in ischemic kidney tissue. Kidneys obtained from rats pretreated with polyenylphosphatidycholine demonstrated marked reduction of the histological features of renal injury compared to kidneys obtained from Group 2 rats, including a little vacuolization, pyknosis and necrosis.

CONCLUSIONS

Polyenylphosphatidycholine pretreatment provided significant protection against ischemia/reperfusion injury to the kidney. This treatment could be therapeutic in kidney transplantation and other conditions associated with ischemia/reperfusion injury to the kidney.

Differential liver sensitization to toll-like receptor pathways in mice with alcoholic fatty liver

Gut-derived, endotoxin-mediated hepatocellular damage has been postulated to play a crucial role in the pathogenesis of alcohol-induced liver injury in rodents. Endotoxins induce production of tumor necrosis factor alpha (TNF-alpha) by Kupffer cells via Toll-like receptor (TLR) 4 and contribute to liver injury. This study addressed the contribution of other TLRs and ligands to alcoholic fatty liver. C57Bl6/J mice were fed a modified Lieber-DeCarli diet. Serum aminotransferase measurements, histological analysis, and quantification of liver TNF-alpha and TLR1-9 messenger RNA (mRNA) were performed. The effect of TLR ligands on liver injury was assessed in vivo. Neomycin and metronidazole or diphenyleneiodonium sulfate (DPI) were administered to evaluate the role of gut bacteria and NADPH oxidase activity, respectively, in hepatic TLR expression. Enteral ethanol (EtOH) exposure induced steatosis and increased liver weight, aminotransferase levels, and expression of TLR1, 2, 4, 6, 7, 8, and 9 liver mRNA. Injection of lipoteichoic acid, peptidoglycan (PGN), lipopolysaccharide (LPS), loxoribine, and oligonudeotide containing CpG (ISS-ODN) increased TNF-alpha mRNA expression more in the livers of EtOH-fed mice than in control mice. PGN, LPS, flagellin, and ISS-ODN induced liver inflammatory infiltrate in EtOH-fed mice but not control mice. Addition of antibiotics reduced the severity of alcoholic fatty liver without affecting TLR expression, whereas daily DPI injections reduced the EtOH-mediated upregulation of TLR2, 4, 6, and 9 mRNA. In conclusion, EtOH-fed mice exhibited an oxidative stress dependent on upregulation of multiple TLRs in the liver and are sensitive to liver inflammation induced by multiple bacterial products recognized by TLRs.

Adiponectin normalizes LPS-stimulated TNF-alpha production by rat Kupffer cells after chronic ethanol feeding

Chronic ethanol feeding sensitizes Kupffer cells to activation by lipopolysaccharide (LPS), leading to increased production of tumor necrosis factor-alpha (TNF-alpha). Adiponectin treatment protects mice from ethanol-induced liver injury. Because adiponectin has anti-inflammatory effects on macrophages, we hypothesized that adiponectin would normalize chronic ethanol-induced sensitization of Kupffer cells to LPS-mediated signals. Serum adiponectin concentrations were decreased by 45% in rats fed an ethanol-containing diet for 4 wk compared with pair-fed rats. Adiponectin dose dependently inhibited LPS-stimulated accumulation of TNF-alpha mRNA and peptide in Kupffer cells from both pair- and ethanol-fed rats. Kupffer cells from ethanol-fed rats were more sensitive to both globular (gAcrp) and full-length adiponectin (flAcrp) than Kupffer cells from pair-fed controls with suppression at 10 ng/ml adiponectin after chronic ethanol feeding. Kupffer cells expressed both adiponectin receptors 1 and 2; chronic ethanol feeding did not change the expression of adiponectin receptor mRNA or protein. gAcrp suppressed LPS-stimulated ERK1/2 and p38 phosphorylation as well as IkappaB degradation at 100-1,000 ng/ml in Kupffer cells from both pair- and ethanol-fed rats. However, only LPS-stimulated ERK1/2 phosphorylation was sensitive to 10 ng/ml gAcrp. gAcrp also normalized LPS-stimulated DNA binding activity of early growth response-1 with greater sensitivity in Kupffer cells from rats fed chronic ethanol. In conclusion, these results demonstrate that Kupffer cells from ethanol-fed rats are more sensitive to the anti-inflammatory effects of both gAcrp and flAcrp. Suppression of LPS-stimulated ERK1/2 signaling by low concentrations of gAcrp was associated with normalization of TNF-alpha production by Kupffer cells after chronic ethanol exposure.

Chronic ethanol feeding increases activation of NADPH oxidase by lipopolysaccharide in rat Kupffer cells: role of increased reactive oxygen in LPS-stimulated ERK1/2 activation and TNF-alpha production

Reactive oxygen species (ROS) contribute to the development of chronic ethanol-induced liver injury. Although ROS modulate the activity of many signal transduction pathways, the molecular targets of ROS during ethanol exposure are not well understood. Here, we investigated whether specific ROS-sensitive signal transduction pathways contribute to increased tumor necrosis factor alpha (TNF-alpha) production by Kupffer cells after chronic ethanol feeding to rats. Lipopolysaccharide (LPS) rapidly increased ROS production, measured by dihydrorhodamine fluorescence, in Kupffer cells from ethanol- and pair-fed rats, and ROS production was 2.5-fold greater in ethanol-fed compared with pair-fed. Pretreatment with diphenyleneiodonium (DPI), which inhibits reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, normalized ROS production in Kupffer cells from ethanol-fed rats. LPS rapidly increased Rac1-guanosinetriphosphatase (GTPase) activity and p67(phox) translocation to the plasma membrane in Kupffer cells from pair-fed rats. After ethanol feeding, Rac1-GTPase activity was already increased over pair-fed at baseline and remained elevated over pair-fed after LPS stimulation. Further, LPS-stimulated p67(phox) translocation to the plasma membrane was enhanced after chronic ethanol feeding. LPS-stimulated extracellular signal-regulated kinase (ERK)1/2 and p38 phosphorylation, two signaling pathways regulated by ROS, were increased twofold in Kupffer cells from ethanol-fed rats compared with pair-fed controls. However, only LPS-stimulated ERK1/2 phosphorylation was inhibited by DPI, which also reduced LPS-stimulated TNF-alpha production in Kupffer cells from pair- and ethanol-fed rats. These results demonstrate that chronic ethanol feeding increases LPS-stimulated NADPH oxidase-dependent production of ROS in Kupffer cells. Further, ERK1/2 is an important target of NADPH oxidase-derived ROS in Kupffer cells, contributing to enhanced LPS-stimulated TNF-alpha production by Kupffer cells after chronic ethanol feeding.

Globular adiponectin decreases leptin-induced tumor necrosis factor-alpha expression by murine macrophages: involvement of cAMP-PKA and MAPK pathways

Several lines of evidence have supported a link between obesity and inflammation. The present study investigated the capacity of leptin and globular adiponectin to affect tumor necrosis factor alpha (TNF-alpha) production in murine peritoneal macrophages. Leptin stimulated TNF-alpha production at mRNA as well as protein levels in a dose- and time-dependent manner. Intracellular cAMP concentration was increased and protein kinase A (PKA) was activated with the treatment of leptin, subsequently downstream MAPK signal proteins, ERK1/2 and p38, were phosphorylated. Specific inhibitors for the signal proteins, Rp cAMPS, H89, PD98059, and U0126, or SB203580, suppressed the signaling pathway and TNF-alpha expression. Although gAd partially increased cAMP concentration and PKA activity, it directly reduced leptin-induced ERK1/2 and p38 MAPK phosphorylation thus inhibiting TNF-alpha production. In conclusion, leptin promotes inflammation by stimulating TNF-alpha production, which is mediated by cAMP-PKA-ERK1/2 and p38 MAPK pathways. gAd inhibited leptin-induced TNF-alpha production through suppressing phosphorylation of ERK1/2 and p38 pathways.

NF-kappaB activation, rather than TNF, mediates hepatic inflammation in a murine dietary model of steatohepatitis

BACKGROUND & AIMS

We explored the roles of nuclear factor-kappaB (NF-kappaB) and tumor necrosis factor (TNF) alpha (TNF-alpha) as mediators of inflammation in a nutritional model of steatohepatitis.

METHODS

Wild-type (wt), TNF null -/-, and TNF receptor (R)-1-/- mice were fed a methionine- and choline-deficient (MCD) diet for up to 5 weeks. Liver injury (serum alanine aminotransferase [ALT]), hepatic inflammation, triglycerides, and lipid peroxide levels were determined. Hepatic NF-kappaB activation and expression of TNF and intercellular adhesion molecule-1 (ICAM-1) were assayed.

RESULTS

Irrespective of genotype, MCD diet-fed mice developed hepatic lipid peroxidation and serum ALT elevation; at day 10, livers from wt, TNF-/-, and TNFR-1-/- mice showed equivalent steatohepatitis. NF-kappaB/DNA binding was enhanced in hepatic nuclear fractions from MCD diet-fed wt mice compared with dietary controls; there were corresponding increases of ICAM-1 and TNF messenger RNA (mRNA). Likewise, NF-kappaB activation and ICAM-1 expression were enhanced by MCD dietary feeding in TNF-/- and TNFR-1-/- mice compared with respective controls. To establish whether NF-kappaB is a primary mediator of inflammation in experimental steatohepatitis, we over-expressed a mutant, nondegradable IkappaB (mIkappaB), delivered by adenovirus in vivo. As expected, hepatic mIkappaB expression reduced NF-kappaB/DNA binding induced by MCD dietary feeding, with resultant abrogation of ICAM-1 and TNF synthesis. Such blockade of NF-kappaB transcriptional activation substantially protected against development of steatohepatitis, with significant reductions in liver injury and hepatic inflammation.

CONCLUSIONS

In the MCD dietary model of steatohepatitis, NF-kappaB is activated early and is an important proinflammatory mediator of lesion development, but steatohepatitis occurs independently of TNF synthesis and TNFR-1 activation.