Ethanol augments RANTES/CCL5 expression in rat liver sinusoidal endothelial cells and human endothelial cells via activation of NF-kappa B, HIF-1 alpha, and AP-1

GET73 modulates lipopolysaccharide- and ethanol-induced increase in cytokine/chemokine levels in primary cultures of microglia of rat cerebral cortex

BACKGROUND

- Alcohol-induced pro-inflammatory activation might influence cellular and synaptic pathology, thus contributing to the behavioral phenotypes associated with alcohol use disorders. In the present study, the possible anti-inflammatory properties of N-[(4-trifluoromethyl)-benzyl]4-methoxybutyramide (GET73), a promising therapeutic agent for alcohol use disorder treatment, were evaluated in primary cultures of rat cortical microglia.

METHODS

- Primary cultures of cerebral cortex microglial cells were treated with 100 ng/ml lipopolysaccharide (LPS; 8 h, 37 °C) or 75 mM ethanol (EtOH; 4 days, 37 °C) alone or in the presence of GET73 (1-30 µM). At the end of the incubation period, multiparametric quantification of cytokines/chemokines was performed by using the xMAP technology and Luminex platform. Furthermore, cultured microglial cell viability following the treatment with EtOH and GET73, alone or in combination, has been measured by a colorimetric assay (i.e. MTT assay).

RESULTS

- GET73 (10 and 30 µM) partially or fully prevented the LPS-induced increase of IL-6, IL-1β, RANTES/CCL5 protein and MCP-1/CCL2 levels. On the contrary, GET73 failed to attenuate the TNF-α level increase induced by LPS. Furthermore, GET73 treatment (10-30 µM) significantly attenuated or prevented the EtOH-induced increase of TNF-α, IL-6, IL-1β and MCP-1/CCL2 levels. Finally, at all the concentrations tested (1-30 µM), the GET73 treatment did not alter the EtOH-induced reduction of microglial cell viability.

CONCLUSIONS

- The current results provide the first in vitro evidence of GET73 protective properties against EtOH-induced neuroinflammation. These data add more information on the complex and multifactorial profile of action of the compound, further supporting the significance of developing GET73 as a therapeutic tool for the treatment of individuals with alcohol use disorders.

AIF1 + CSF1R + MSCs, induced by TNF-α, act to generate an inflammatory microenvironment and promote hepatocarcinogenesis

BACKGROUND AND AIMS

Increasing evidence suggests that mesenchymal stem cells (MSCs) home to injured local tissues and the tumor microenvironment in the liver. Chronic inflammation is regarded as the major trait of primary liver cancer. However, the characteristics of endogenous MSCs in the inflammatory environment and their role in the occurrence of liver cancer remain obscure.

APPROACH AND RESULTS

Using single-cell RNA sequencing, we identified a distinct inflammation-associated subset of MSCs, namely AIF1 + CSF1R + MSCs, which existed in the microenvironment before the occurrence of liver cancer. Furthermore, we found that this MSC subgroup is likely to be induced by TNF-α stimulation through the TNFR1/SIRT1 (sirtuin 1) pathway. In a rat primary liver cancer model, we showed that MSCs with high SIRT1 expression (Ad-Sirt1-MSCs) promoted macrophage recruitment and synergistically facilitated liver cancer occurrence by secreting C-C motif chemokine ligand (CCL) 5. Interestingly, depletion of macrophages or knockdown of CCL5 expression in Ad-Sirt1-MSCs attenuated the promotive effect of Ad-Sirt1-MSCs on liver inflammation and hepatocarcinogenesis (HCG). Finally, we demonstrated that SIRT1 up-regulated CCL5 expression through activation of the AKT/HIF1α signaling axis in MSCs.

CONCLUSIONS

Together, our results show that MSCs, which are mobilized to the injured site, can be educated by macrophages. In turn, the educated MSCs are involved in generating a chronic inflammatory microenvironment and promoting HCG.

Investigation of therapeutic effects of rhubarb decoction retention enema on minimal hepatic encephalopathy in rats based on 16S rDNA gene sequencing and bile acid metabolomics

Minimal hepatic encephalopathy (MHE) is an early stage of hepatic encephalopathy (HE), with high incidence and a high rate of clinically missed diagnosis. Early diagnosis of MHE and effective clinical intervention are of great importance. Rhubarb decoction (RD)-induced retention enema can effectively improve the cognitive function of patients with MHE, whereas disturbances in the enterohepatic circulation of bile acid (BAs) can induce MHE. However, the molecular mechanisms underlying the therapeutic effects of RD have not been examined from the perspective of intestinal microbiota and bile metabolomics. In this study, we investigated the effects of RD-induced retention enema on intestinal microbiota and bile metabolites in rats with CCl₄- and TAA-induced MHE. RD-induced retention enema significantly improved liver function, reduced blood ammonia levels, alleviated cerebral oedema and restored cognitive function in rats with MHE. In addition, it increased the abundance of intestinal microbes; partially reversed the disorder in the composition of intestinal microbiota, including the Bifidobacterium and Bacteroides genera; and regulated BA metabolism, such as taurine combined with increased BA synthesis. In conclusion, this study highlights the potential importance of BA enterohepatic circulation for RD to improve cognitive function in MHE rats, providing a new perspective on the mechanism of this herb. The findings of this study will facilitate experimental research on RD and help to develop RD-based strategies for clinical application.

Signal Transduction and Gene Regulation in the Endothelium

Extracellular signals act on G-protein-coupled receptors (GPCRs) to regulate homeostasis and adapt to stress. This involves rapid intracellular post-translational responses and long-lasting gene-expression changes that ultimately determine cellular phenotype and fate changes. The lipid mediator sphingosine 1-phosphate (S1P) and its receptors (S1PRs) are examples of well-studied GPCR signaling axis essential for vascular development, homeostasis, and diseases. The biochemical cascades involved in rapid S1P signaling are well understood. However, gene-expression regulation by S1PRs are less understood. In this review, we focus our attention to how S1PRs regulate nuclear chromatin changes and gene transcription to modulate vascular and lymphatic endothelial phenotypic changes during embryonic development and adult homeostasis. Because S1PR-targeted drugs approved for use in the treatment of autoimmune diseases cause substantial vascular-related adverse events, these findings are critical not only for general understanding of stimulus-evoked gene regulation in the vascular endothelium, but also for therapeutic development of drugs for autoimmune and perhaps vascular diseases.

Dietary camellia seed oil attenuates liver injury in mice chronically exposed to alcohol

Dietary fat composition is closely associated with the pathological development of alcoholic liver disease (ALD). Fat enriched with saturated fatty acids protects whereas with polyunsaturated fatty acids aggravates alcohol-induced liver injury. However, limited study has addressed how monounsaturated fatty acids (MUFAs) determines the pathological process of ALD. Our study was conducted to evaluate the effect of MUFAs-enriched-camellia seed oil (CSO) on alcohol-induced liver injury. The ALD model was established by feeding C57BL/6 mice with Lieber-DeCarli diet, and with either CSO or polyunsaturated fatty acids (PUFAs)-enriched-corn oil (CO) as fat source. After 4-week-intervention, CSO-feed rescued alcohol-induced liver injury compared to CO-feed, evidenced by measurements of plasma ALT activity, H&E stain, and hepatic cleaved-Caspase-3 expression. Besides, CSO-feed alleviated alcohol-induced oxidative stress, associated with NRF2 and Hif-1α expressions improvement. The reduction of F4/80 immunostaining and the decreased expressions of hepatic TNF-α and IL-6 suggested CSO-feed improved alcohol-induced inflammation. The mechanistic analysis showed that the inhibition of ASK1 and MAPKs might contribute to CSO-protected liver injury. Notably, we observed CSO-feed relieved the gut microbiota disturbance with the decreased Firmicutes and Turicibater, and the increased Bacteroidota, Alloprevotella, and Bacteroides, and reduced circulatory endotoxin level and lipolysis of adipose tissue, which are the known pathogenic factors in alcohol-induced liver injury. Unexpectedly, CSO induced more hepatic steatosis than CO-feed. In conclusion, CSO attenuated chronic alcohol consumption-induced liver injury but enhanced hepatic steatosis. CSO could be a potential dietary choice for alcoholic individuals with liver injury.

Immune-regulating strategy against rheumatoid arthritis by inducing tolerogenic dendritic cells with modified zinc peroxide nanoparticles

In hypoxic dendritic cells (DCs), a low level of Zn²⁺ can induce the activation of immunogenic DCs (igDCs), thereby triggering an active T-cell response to propel the immune progression of rheumatoid arthritis (RA). This finding indicates the crucial roles of zinc and oxygen homeostasis in DCs during the pathogenesis of RA. However, very few studies have focused on the modulation of zinc and oxygen homeostasis in DCs during RA treatment. Proposed herein is a DC-targeting immune-regulating strategy to induce igDCs into tolerogenic DCs (tDCs) and inhibit subsequent T-cell activation, referred to as ZnO₂/Catalase@liposome-Mannose nanoparticles (ZnCM NPs). ZnCM NPs displayed targeted intracellular delivery of Zn²⁺ and O₂ towards igDCs in a pH-responsive manner. After inactivating OTUB1 deubiquitination, the ZnCM NPs promoted CCL5 degradation via NF-κB signalling, thereby inducing the igDC-tDC transition to further inhibit CD4⁺ T-cell homeostasis. In collagen-induced arthritis (CIA) mice, this nanoimmunoplatform showed significant accumulation in the spleen, where immature DCs (imDCs) differentiated into igDCs. Splenic tDCs were induced to alleviate ankle swelling, improve walking posture and safely inhibit ankle/spleen inflammation. Our work pioneers the combination of DC-targeting nanoplatforms with RA treatments and highlights the significance of zinc and oxygen homeostasis for the immunoregulation of RA by inducing tDCs with modified ZnO₂ NPs, which provides novel insight into ion homeostasis regulation for the treatment of immune diseases with a larger variety of distinct metal or nonmetal ions.

The DC-targeting immune-regulating nanostrategy was firstly employed to treat RA.

The complex immune regulating effects was realized through a portable, convenient and green nanomaterial.

Highlighting the significance of zinc and oxygen homeostasis for the immunoregulation of RA by inducing tDCs with modified ZnO₂ NPs.

Expanding the notion of ion homeostasis regulation with a larger variety of distinct metal or nonmetal ions.

Alcohol induces mitochondrial derangements in alveolar macrophages by upregulating NADPH oxidase 4

Excessive alcohol users have increased risk of developing respiratory infections in part due to oxidative stress-induced alveolar macrophage (AM) phagocytic dysfunction. Chronic ethanol exposure increases cellular oxidative stress in AMs via upregulation of NADPH oxidase (Nox) 4, and treatment with the peroxisome proliferator-activated receptor gamma (PPARγ) ligand, rosiglitazone, decreases ethanol-induced Nox4. However, the mechanism by which ethanol induces Nox4 expression and the PPARγ ligand reverses this defect has not been elucidated. Since microRNA (miR)-92a has been predicted to target Nox4 for destabilization, we hypothesized that ethanol exposure decreases miR-92a expression and leads to Nox4 upregulation. Previous studies have implicated mitochondrial-derived oxidative stress in AM dysfunction. We further hypothesized that ethanol increases mitochondrial-derived AM oxidative stress and dysfunction via miR-92a, and that treatment with the PPARγ ligand, pioglitazone, could reverse these derangements. To test these hypotheses, a mouse AM cell line, MH-S cells, was exposed to ethanol in vitro, and primary AMs were isolated from a mouse model of chronic ethanol consumption to measure Nox4, mitochondrial target mRNA (qRT-PCR) and protein levels (confocal microscopy), mitochondria-derived reactive oxygen species (confocal immunofluorescence), mitochondrial fission (electron microscopy), and mitochondrial bioenergetics (extracellular flux analyzer). Ethanol exposure increased Nox4, enhanced mitochondria-derived oxidative stress, augmented mitochondrial fission, and impaired mitochondrial bioenergetics. Transfection with a miR-92a mimic in vitro or pioglitazone treatment in vivo diminished Nox4 levels, resulting in improvements in these ethanol-mediated derangements. These findings demonstrate that pioglitazone may provide a novel therapeutic approach to mitigate ethanol-induced AM mitochondrial derangements.

Animal models for liver disease - A practical approach for translational research

Animal models are crucial for improving our understanding of human pathogenesis, enabling researchers to identify therapeutic targets and test novel drugs. In the current review, we provide a comprehensive summary of the most widely used experimental models of chronic liver disease, starting from early stages of fatty liver disease (non-alcoholic and alcoholic) to steatohepatitis, advanced cirrhosis and end-stage primary liver cancer. We focus on aspects such as reproducibility and practicality, discussing the advantages and weaknesses of available models for researchers who are planning to perform animal studies in the near future. Additionally, we summarise current and prospective models based on human tissue bioengineering.

Young adult binge drinkers have immunophenotypical disarrangements in peripheral natural killer cells

Alcohol consumption is an issue of worldwide relevance and a problem of national scale in Mexico. The consumption pattern of large amounts of alcohol on the weekends is rapidly increasing in young adults between 18 and 29 years. Despite various studies that have focused on the noxious effect of alcohol in immunity, the changes in the immunoprofiles of peripheral blood cells have not been completely described. Natural killer cells (NKCs) are lymphoid-origin cells of the immune system that are responsible for defense against tumors, among other functions. In homeostatic conditions, they are found to be in a state of "dynamic balance" between activation and inhibition stimuli, which, if broken, may lead to immunosuppression or activation of cytotoxic mechanisms. In this study, we evaluated the immunoprofile of peripheral NKCs of 54 young adults, 29 of whom were binge drinkers and 25 of whom were low risk (LR), as classified by validated tools. Drinking habits were assessed. Blood samples were collected to perform hematic biometry and liver enzyme tests. Peripheral NKCs were identified by FACS, and stained for CCR2, CCR4, CCR5, CXCR4, CD69, CD127, CD137, TLR4, and Granzyme B. The data were analyzed using the t test and Mann-Whitney's U test for contrasts, and the effect size was obtained in order to evaluate the impact of each immunoprofile. The binge group showed increased expression of CCR5 and PD-1 in NKCs, respective to the LR group, and decreased expression of TLR4, along with fewer CCR4⁺ cells. Moreover, the increase found in CCR5 and PD-1 expression was correlated with the number of drinks in the last drinking session. Our findings show that young binge drinkers have different immunoprofiles that could suggest an early status of immunosuppression and trafficking of NKCs to the liver, which could be related to the onset of early liver damage, early in a subject's lifespan.

Protein kinase Ds promote tumor angiogenesis through mast cell recruitment and expression of angiogenic factors in prostate cancer microenvironment

Background

Mast cells are being increasingly recognized as critical components in the tumor microenvironment. Protein Kinase D (PKD) is essential for the progression of prostate cancer, but its role in prostate cancer microenvironment remains poorly understood.

Methods

The expression of PKD, mast cells and microvessel density were examined by IHC. The clinical significance was determined by statistical analyses. The biological function of PKD and the underlying mechanisms were investigated using in vitro and in vivo models.

Results

PKD2/3 contributed to MCs recruitment and tumor angiogenesis in the prostate cancer microenvironment. Clinical data showed that increased activation of PKD at Ser744/748 in prostate cancer was correlated with mast cell infiltration and microvascular density. PKD2/3 silencing of prostate cancer cells markedly decreased MCs migration and tube formation of HUVEC cells. Moreover, PKD2/3 depletion not only reduced SCF, CCL5 and CCL11 expression in prostate cancer cells but also inhibited angiogenic factors in MCs. Conversely, exogenous SCF, CCL5 and CCL11 reversed the effect on MCs migration inhibited by PKD2/3 silencing. Mechanistically, PKD2/3 interacted with Erk1/2 and activated Erk1/2 or NF-κB signaling pathway, leading to AP-1 or NF-κB binding to the promoter of scf, ccl5 and ccl11. Finally, PKD-specific inhibitor significantly reduced tumor volume and tumor growth in mice bearing RM-1 prostate cancer cells, which was attributed to attenuation of mast cell recruitment and tumor angiogenesis.

Conclusions

These results demonstrate a novel PKDs function that contributes to tumor angiogenesis and progression through mast cells recruitment in prostate cancer microenvironment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1118-y) contains supplementary material, which is available to authorized users.

Role of Alcohol Oxidative Metabolism in Its Cardiovascular and Autonomic Effects

Several review articles have been published on the neurobehavioral actions of acetaldehyde and other ethanol metabolites as well as in major alcohol-related disorders such as cancer and liver and lung disease. However, very few reviews dealt with the role of alcohol metabolism in the adverse cardiac and autonomic effects of alcohol and their potential underlying mechanisms, particularly in vulnerable populations. In this chapter, following a brief overview of the dose-related favorable and adverse cardiovascular effects of alcohol, we discuss the role of ethanol metabolism in its adverse effects in the brainstem and heart. Notably, current knowledge dismisses a major role for acetaldehyde in the adverse autonomic and cardiac effects of alcohol because of its low tissue level in vivo. Contrary to these findings in men and male rodents, women and hypertensive individuals are more sensitive to the adverse cardiac effects of similar amounts of alcohol. To understand this discrepancy, we discuss the autonomic and cardiac effects of alcohol and its metabolite acetaldehyde in a model of hypertension, the spontaneously hypertensive rat (SHR) and female rats. We present evidence that enhanced catalase activity, which contributes to cardioprotection in hypertension (compensatory) and in the presence of estrogen (inherent), becomes detrimental due to catalase catalysis of alcohol metabolism to acetaldehyde. Noteworthy, studies in SHRs and in estrogen deprived or replete normotensive rats implicate acetaldehyde in triggering oxidative stress in autonomic nuclei and the heart via (i) the Akt/extracellular signal-regulated kinases (ERK)/nitric oxide synthase (NOS) cascade and (ii) estrogen receptor-alpha (ERα) mediation of the higher catalase activity, which generates higher ethanol-derived acetaldehyde in female heart. The latter is supported by the ability of ERα blockade or catalase inhibition to attenuate alcohol-evoked myocardial oxidative stress and dysfunction. More mechanistic studies are needed to further understand the mechanisms of this public health problem.

Role of HIF-1α in Alcohol-Mediated Multiple Organ Dysfunction

Excess alcohol consumption is a global crisis contributing to over 3 million alcohol-related deaths per year worldwide and economic costs exceeding $200 billion dollars, which include productivity losses, healthcare, and other effects (e.g., property damages). Both clinical and experimental models have shown that excessive alcohol consumption results in multiple organ injury. Although alcohol metabolism occurs primarily in the liver, alcohol exposure can lead to pathophysiological conditions in multiple organs and tissues, including the brain, lungs, adipose, liver, and intestines. Understanding the mechanisms by which alcohol-mediated organ dysfunction occurs could help to identify new therapeutic approaches to mitigate the detrimental effects of alcohol misuse. Hypoxia-inducible factor (HIF)-1 is a transcription factor comprised of HIF-1α and HIF-1β subunits that play a critical role in alcohol-mediated organ dysfunction. This review provides a comprehensive analysis of recent studies examining the relationship between HIF-1α and alcohol consumption as it relates to multiple organ injury and potential therapies to mitigate alcohol’s effects.

Abnormal expression of TFIIIB subunits and RNA Pol III genes is associated with hepatocellular carcinoma

The levels of the products of RNA polymerase III-dependent genes (Pol III genes), including tRNAs and 5S rRNA, are elevated in transformed and tumor cells, which potentiate tumorigenesis. TFIIB-related factor 1 (Brf1) is a key transcription factor and specifically regulates the transcription of Pol III genes. In vivo and in vitro studies have demonstrated that a decrease in Brf1 reduces Pol III gene transcription and is sufficient for inhibiting cell transformation and tumor formation. Emerging evidence indicates that dysregulation of Brf1 and Pol III genes is linked to the development of hepatocellular carcinoma (HCC) in humans and animals. We have reported that Brf1 is overexpressed in human liver cancer patients and that those with high Brf1 levels have shorter survivals. This review summarizes the effects of dysregulation of these genes on HCC and their regulation by signaling pathways and epigenetics. These novel data should help us determine the molecular mechanisms of HCC from a different perspective and guide the development of therapeutic approaches for HCC patients.

Signaling pathways related to role of hepatic sinusoidal endothelial cells in liver fibrosis

Liver fibrosis is the pathological preprocess of liver cirrhosis or liver cancer progressing from chronic liver disease. Hepatic sinusoidal endothelial cells (HSECs) are involved in the formation and development of liver fibrosis through multiple signaling pathways. In this paper, we summarize and elaborate these signaling pathways including Rho-GTPase, CXCR7-Id1/FGFR1-CXCR4, VEGFR-2/p38 mitogen-activated protein kinases (MAPK), MAPK, and TLRs. Based on these signaling pathways, we put forward new ideas for the prevention and treatment of liver fibrosis.

Alcohol and inflammatory responses: Highlights of the 2015 Alcohol and Immunology Research Interest Group (AIRIG) meeting

On September 27, 2015 the 20th annual Alcohol and Immunology Research Interest Group (AIRIG) meeting was held as a satellite symposium at the annual meeting of the Society for Leukocyte Biology in Raleigh, NC. The 2015 meeting focused broadly on adverse effects of alcohol and alcohol-use disorders in multiple organ systems. Divided into two plenary sessions, AIRIG opened with the topic of pulmonary inflammation as a result of alcohol consumption, which was followed by alcohol's effect on multiple organs, including the brain and liver. With presentations showing the diverse range of underlying pathology and mechanisms associated with multiple organs as a result of alcohol consumption, AIRIG emphasized the importance of continued alcohol research, as its detrimental consequences are not limited to one or even two organs, but rather extend to the entire host as a whole.

Peroxisome Proliferator-Activated Receptor γ Regulates Chronic Alcohol-Induced Alveolar Macrophage Dysfunction

Peroxisome proliferator-activated receptor (PPAR) γ is critical for alveolar macrophage (AM) function. Chronic alcohol abuse causes AM phagocytic dysfunction and susceptibility to respiratory infections by stimulating nicotinamide adenine dinucleotide oxidases (Nox), transforming growth factor-β1, and oxidative stress in the AM. Because PPARγ inhibits Nox expression, we hypothesized that alcohol reduces PPARγ, stimulating AM dysfunction. AMs were examined from: (1) patients with alcoholism or control patients; (2) a mouse model of chronic ethanol consumption; (3) PPARγ knockout mice; or (4) MH-S cells exposed to ethanol in vitro. Alcohol reduced AM PPARγ levels and increased Nox1, -2, and -4, transforming growth factor-β1, oxidative stress, and phagocytic dysfunction. Genetic loss of PPARγ recapitulated, whereas stimulating PPARγ activity attenuated alcohol-mediated alterations in gene expression and phagocytic function, supporting the importance of PPARγ in alcohol-induced AM derangements. Similarly, PPARγ activation in vivo reduced alcohol-mediated impairments in lung bacterial clearance. Alcohol increased levels of microRNA-130a/-301a, which bind to the PPARγ 3' untranslated region to reduce PPARγ expression. MicroRNA-130a/-301a inhibition attenuated alcohol-mediated PPARγ reductions and derangements in AM gene expression and function. Alcohol-induced Toll-like receptor 4 endocytosis was reversed by PPARγ activation. These findings demonstrate that targeting PPARγ provides a novel therapeutic approach for mitigating alcohol-induced AM derangements and susceptibility to lung infection.

Role of Transcription Factors in Steatohepatitis and Hypertension after Ethanol: The Epicenter of Metabolism

Chronic alcohol consumption induces multi-organ damage, including alcoholic liver disease (ALD), pancreatitis and hypertension. Ethanol and ethanol metabolic products play a significant role in the manifestation of its toxicity. Ethanol metabolizes to acetaldehyde and produces reduced nicotinamide adenine dinucleotide (NADH) by cytosolic alcohol dehydrogenase. Ethanol metabolism mediated by cytochrome-P450 2E1 causes oxidative stress due to increased production of reactive oxygen species (ROS). Acetaldehyde, increased redox cellular state and ROS activate transcription factors, which in turn activate genes for lipid biosynthesis and offer protection of hepatocytes from alcohol toxicity. Sterol regulatory element binding proteins (SREBPs) and peroxisome proliferator activated-receptors (PPARs) are two key lipogenic transcription factors implicated in the development of fatty liver in alcoholic and non-alcoholic steatohepatitis. SREBP-1 is activated in the livers of chronic ethanol abusers. An increase in ROS activates nuclear factor erythroid-2-related factor-2 (Nrf2) and hypoxia inducible factor (HIF) to provide protection to hepatocytes from ethanol toxicity. Under ethanol exposure, due to increased gut permeability, there is release of gram-negative bacteria-derived lipopolysaccharide (LPS) from intestine causing activation of immune response. In addition, the metabolic product, acetaldehyde, modifies the proteins in hepatocyte, which become antigens inviting auto-immune response. LPS activates macrophages, especially the liver resident macrophages, Kupffer cells. These Kupffer cells and circulating macrophages secrete various cytokines. The level of tumor necrosis factor-α (TNFα), interleukin-1beta (IL-1β), IL-6, IL-8 and IL-12 have been found elevated among chronic alcoholics. In addition to elevation of these cytokines, the peripheral iron (Fe(2+)) is also mobilized. An increased level of hepatic iron has been observed among alcoholics. Increased ROS, IL-1β, acetaldehyde, and increased hepatic iron, all activate nuclear factor-kappa B (NF-κB) transcription factor. Resolution of increased reactive oxygen species requires increased expression of genes responsible for dismutation of increased ROS which is partially achieved by IL-6 mediated activation of signal transducers and activators of transcription 3 (STAT3). In addition to these transcription factors, activator protein-1 may also be activated in hepatocytes due to its association with resolution of increased ROS. These transcription factors are central to alcohol-mediated hepatotoxicity.

A new HIF-1α/RANTES-driven pathway to hepatocellular carcinoma mediated by germline haploinsufficiency of SART1/HAF in mice

The hypoxia-inducible factor (HIF), HIF-1, is a central regulator of the response to low oxygen or inflammatory stress and plays an essential role in survival and function of immune cells. However, the mechanisms regulating nonhypoxic induction of HIF-1 remain unclear. Here, we assess the impact of germline heterozygosity of a novel, oxygen-independent ubiquitin ligase for HIF-1α: hypoxia-associated factor (HAF; encoded by SART1). SART1(-/-) mice were embryonic lethal, whereas male SART1(+/-) mice spontaneously recapitulated key features of nonalcoholic steatohepatitis (NASH)-driven hepatocellular carcinoma (HCC), including steatosis, fibrosis, and inflammatory cytokine production. Male, but not female, SART1(+/-) mice showed significant up-regulation of HIF-1α in circulating and liver-infiltrating immune cells, but not in hepatocytes, before development of malignancy. Additionally, Kupffer cells derived from male, but not female, SART1(+/-) mice produced increased levels of the HIF-1-dependent chemokine, regulated on activation, normal T-cell expressed and secreted (RANTES), compared to wild type. This was associated with increased liver-neutrophilic infiltration, whereas infiltration of lymphocytes and macrophages were not significantly different. Neutralization of circulating RANTES decreased liver neutrophilic infiltration and attenuated HCC tumor initiation/growth in SART1(+/-) mice.

CONCLUSION

This work establishes a new tumor-suppressor role for HAF in immune cell function by preventing inappropriate HIF-1 activation in male mice and identifies RANTES as a novel therapeutic target for NASH and NASH-driven HCC.

Short Term Hypoxia Synergizes with Interleukin 15 Priming in Driving Glycolytic Gene Transcription and Supports Human Natural Killer Cell Activities

Natural killer (NK) cells induce apoptosis in infected and transformed cells and are important producers of immunoregulatory cytokines. Therefore, they operate under low oxygen conditions (hypoxia) in inflammatory and tumor environments. In vitro studies of NK cells are, however, commonly performed in ambient air (normoxia). We used global gene expression profiling to evaluate changes in transcriptional pathways in primary human NK cells following short term culture under hypoxia compared with normoxia and in response to interleukin 15 (IL-15) priming using a 2 × 2 factorial design. The largest contrasts observed were priming dependences for associations between hypoxia and the hypoxia-inducible factor (Hif) 1 signaling and glycolysis pathways. RT-PCR confirmed positive synergistic hypoxia/IL-15 interactions for genes of key regulatory and metabolic enzymes. IL-15 primes NK cells for effector functions, which were recently demonstrated to depend on glycolytic switching. We did not, however, observe important increases in glycolytic flux through hypoxia and priming alone. Chemical Hif-1α inhibition suggested equal importance of this transcription factor for glycolysis and energy production under normoxia and hypoxia. Hypoxia promoted secretion of CC chemokines Ccl3/4/5 and macrophage migration inhibitory factor. Unexpectedly, hypoxia also stimulated migration of NK cells through the extracellular matrix and shifted amounts of susceptible leukemia target cells toward late apoptosis in a cell killing assay. We conclude that short term hypoxia supports these activities by positively interacting with NK cell priming at the level of glycolytic gene transcription. Hypoxic conditioning of NK cells may thus benefit their use in cell-based immunotherapy of cancer.

Migration of bone marrow progenitor cells in the adult brain of rats and rabbits

Neurogenesis takes place in the adult mammalian brain in three areas: Subgranular zone of the dentate gyrus (DG); subventricular zone of the lateral ventricle; olfactory bulb. Different molecular markers can be used to characterize the cells involved in adult neurogenesis. It has been recently suggested that a population of bone marrow (BM) progenitor cells may migrate to the brain and differentiate into neuronal lineage. To explore this hypothesis, we injected recombinant SV40-derived vectors into the BM and followed the potential migration of the transduced cells. Long-term BM-directed gene transfer using recombinant SV40-derived vectors leads to expression of the genes delivered to the BM firstly in circulating cells, then after several months in mature neurons and microglial cells, and thus without central nervous system (CNS) lesion. Most of transgene-expressing cells expressed NeuN, a marker of mature neurons. Thus, BM-derived cells may function as progenitors of CNS cells in adult animals. The mechanism by which the cells from the BM come to be neurons remains to be determined. Although the observed gradual increase in transgene-expressing neurons over 16 mo suggests that the pathway involved differentiation of BM-resident cells into neurons, cell fusion as the principal route cannot be totally ruled out. Additional studies using similar viral vectors showed that BM-derived progenitor cells migrating in the CNS express markers of neuronal precursors or immature neurons. Transgene-positive cells were found in the subgranular zone of the DG of the hippocampus 16 mo after intramarrow injection of the vector. In addition to cells expressing markers of mature neurons, transgene-positive cells were also positive for nestin and doublecortin, molecules expressed by developing neuronal cells. These cells were actively proliferating, as shown by short term BrdU incorporation studies. Inducing seizures by using kainic acid increased the number of BM progenitor cells transduced by SV40 vectors migrating to the hippocampus, and these cells were seen at earlier time points in the DG. We show that the cell membrane chemokine receptor, CCR5, and its ligands, enhance CNS inflammation and seizure activity in a model of neuronal excitotoxicity. SV40-based gene delivery of RNAi targeting CCR5 to the BM results in downregulating CCR5 in circulating cells, suggesting that CCR5 plays an important role in regulating traffic of BM-derived cells into the CNS, both in the basal state and in response to injury. Furthermore, reduction in CCR5 expression in circulating cells provides profound neuroprotection from excitotoxic neuronal injury, reduces neuroinflammation, and increases neuronal regeneration following this type of insult. These results suggest that BM-derived, transgene-expressing, cells can migrate to the brain and that they become neurons, at least in part, by differentiating into neuron precursors and subsequently developing into mature neurons.

Ethanol-induced hepatic autophagy: Friend or foe?

Excessive alcohol intake may induce hepatic apoptosis, steatosis, fibrosis, cirrhosis and even cancer. Ethanol-induced activation of general or selective autophagy as mitophagy or lipophagy in hepatocytes is generally considered a prosurvival mechanism. On the other side of the coin, upregulation of autophagy in non-hepatocytes as stellate cells may stimulate fibrogenesis and subsequently induce detrimental effects on the liver. The autophagic response of other non-hepatocytes as macrophages and endothelial cells is unknown yet and needs to be investigated as these cells play important roles in ethanol-induced hepatic steatosis and damage. Selective pharmacological stimulation of autophagy in hepatocytes may be of therapeutic importance in alcoholic liver disease.

Breast cancer cells condition lymphatic endothelial cells within pre-metastatic niches to promote metastasis

Breast cancer metastasis involves lymphatic dissemination in addition to hematogenous spreading. Although stromal lymphatic vessels (LVs) serve as initial metastatic routes, roles of organ-residing LVs are under-investigated. Here we show that lymphatic endothelial cells (LECs), a component of LVs within pre-metastatic niches, are conditioned by triple-negative breast cancer (TNBC) cells to accelerate metastasis. LECs within the lungs and lymph nodes, conditioned by tumor-secreted factors express CCL5 that is not expressed either in normal LECs or cancer cells, and direct tumor dissemination into these tissues. Moreover, tumor-conditioned LECs promote angiogenesis in these organs, allowing tumor extravasation and colonization. Mechanistically, tumor cell-secreted IL6 causes Stat3 phosphorylation in LECs. This pStat3 induces HIF-1α and VEGF, and a pStat3-pc-Jun-pATF-2 ternary complex induces CCL5 expression in LECs. This study demonstrates anti-metastatic activities of multiple repurposed drugs, blocking a self-reinforcing paracrine loop between breast cancer cells and LECs.

Inhibitory effect of tanshinone IIA on rat hepatic stellate cells

Background

Anti-inflammation via inhibition of NF-κB pathways in hepatic stellate cells (HSCs) is one therapeutic approach to hepatic fibrosis. Tanshinone IIA (C₁₉H₁₈O₃, Tan IIA) is a lipophilic diterpene isolated from Salvia miltiorrhiza Bunge, with reported anti-inflammatory activity. We tested whether Tan IIA could inhibit HSC activation.

Materials and Methods

The cell line of rat hepatic stellate cells (HSC-T6) was stimulated with lipopolysaccharide (LPS) (100 ng/ml). Cytotoxicity was assessed by MTT assay. HSC-T6 cells were pretreated with Tan IIA (1, 3 and 10 µM), then induced by LPS (100 ng/ml). NF-κB activity was evaluated by the luciferase reporter gene assay. Western blotting analysis was performed to measure NF-κB-p65, and phosphorylations of MAPKs (ERK, JNK, p38). Cell chemotaxis was assessed by both wound-healing assay and trans-well invasion assay. Quantitative real-time PCR was used to detect gene expression in HSC-T6 cells.

Results

All concentrations of drugs showed no cytotoxicity against HSC-T6 cells. LPS stimulated NF-κB luciferase activities, nuclear translocation of NF-κB-p65, and phosphorylations of ERK, JNK and p38, all of which were suppressed by Tan IIA. In addition, Tan IIA significantly inhibited LPS-induced HSCs chemotaxis, in both wound-healing and trans-well invasion assays. Moreover, Tan IIA attenuated LPS-induced mRNA expressions of CCL2, CCL3, CCL5, IL-1β, TNF-α, IL-6, ICAM-1, iNOS, and α-SMA in HSC-T6 cells.

Conclusion

Our results demonstrated that Tan IIA decreased LPS-induced HSC activation.

Tirapazamine sensitizes hepatocellular carcinoma cells to topoisomerase I inhibitors via cooperative modulation of hypoxia-inducible factor-1α

Topoisomerase I inhibitors are a class of anticancer drugs with a broad spectrum of clinical activity. However, they have limited efficacy in hepatocellular cancer. Here, we present in vitro and in vivo evidence that the extremely high level of hypoxia-inducible factor-1α (HIF-1α) in hepatocellular carcinoma is intimately correlated with resistance to topoisomerase I inhibitors. In a previous study conducted by our group, we found that tirapazamine could downregulate HIF-1α expression by decreasing HIF-1α protein synthesis. Therefore, we hypothesized that combining tirapazamine with topoisomerase I inhibitors may overcome the chemoresistance. In this study, we investigated that in combination with tirapazamine, topoisomerase I inhibitors exhibited synergistic cytotoxicity and induced significant apoptosis in several hepatocellular carcinoma cell lines. The enhanced apoptosis induced by tirapazamine plus SN-38 (the active metabolite of irinotecan) was accompanied by increased mitochondrial depolarization and caspase pathway activation. The combination treatment dramatically inhibited the accumulation of HIF-1α protein, decreased the HIF-1α transcriptional activation, and impaired the phosphorylation of proteins involved in the homologous recombination repair pathway, ultimately resulting in the synergism of these two drugs. Moreover, the increased anticancer efficacy of tirapazamine combined with irinotecan was further validated in a human liver cancer Bel-7402 xenograft mouse model. Taken together, our data show for the first time that HIF-1α is strongly correlated with resistance to topoisomerase I inhibitors in hepatocellular carcinoma. These results suggest that HIF-1α is a promising target and provide a rationale for clinical trials investigating the efficacy of the combination of topoisomerase I inhibitors and tirapazamine in hepatocellular cancers.

Role of rostral ventrolateral medullary ERK/JNK/p38 MAPK signaling in the pressor effects of ethanol and its oxidative product acetaldehyde

BACKGROUND

We tested the hypothesis that alterations of the phosphorylation/dephosphorylation profile of mitogen-activated protein kinases (MAPKs) in the rostral ventrolateral medulla (RVLM) underlie the pressor response elicited by ethanol (EtOH) microinjection into the RVLM of spontaneously hypertensive rats (SHRs). The studies were extended to determine whether acetaldehyde (ACA), the primary oxidative product of EtOH, replicates the molecular effects of EtOH within the RVLM and the consequent pressor response.

METHODS

Effects of EtOH or ACA on blood pressure (BP) were evaluated in the absence or presence of selective JNK (SP600125), ERK (PD98059), p38 (SB203580), or ser/thr phosphatases (okadaic acid [OKA]) inhibitor.

RESULTS

Intra-RVLM EtOH (10 μg/rat) or ACA (2 μg/rat) caused a similar ERK2-dependent pressor response because EtOH or ACA-evoked increases in BP and in RVLM p-ERK2 level were abolished after pharmacologic inhibition of ERK phosphorylation. SP600125 abrogated the pressor action of EtOH, but not ACA, thus implicating JNK in EtOH action on BP. Despite EtOH enhancement of p38 phosphorylation, pharmacological studies argued against a causal role for this kinase in EtOH-evoked pressor response. RVLM phosphatase catalytic activity was not influenced by EtOH or ACA. Interestingly, pharmacologic phosphatase inhibition (OKA), which increased RVLM p-ERK2 and BP, abrogated the pressor effect of subsequently administered EtOH or ACA.

CONCLUSIONS

Enhancement of RVLM ERK2 phosphorylation constitutes a major molecular mechanism for the pressor response elicited by intra-RVLM EtOH or its metabolite, ACA, in conscious SHRs. Further, RVLM kinases dephosphorylation does not contribute to intra-RVLM EtOH- or ACA-evoked pressor response.

Pulmonary cytokine composition differs in the setting of alcohol use disorders and cigarette smoking

Alcohol use disorders (AUDs), including alcohol abuse and dependence, and cigarette smoking are widely acknowledged and common risk factors for pneumococcal pneumonia. Reasons for these associations are likely complex but may involve an imbalance in pro- and anti-inflammatory cytokines within the lung. Delineating the specific effects of alcohol, smoking, and their combination on pulmonary cytokines may help unravel mechanisms that predispose these individuals to pneumococcal pneumonia. We hypothesized that the combination of AUD and cigarette smoking would be associated with increased bronchoalveolar lavage (BAL) proinflammatory cytokines and diminished anti-inflammatory cytokines, compared with either AUDs or cigarette smoking alone. Acellular BAL fluid was obtained from 20 subjects with AUDs, who were identified using a validated questionnaire, and 19 control subjects, matched on the basis of age, sex, and smoking history. Half were current cigarette smokers; baseline pulmonary function tests and chest radiographs were normal. A positive relationship between regulated and normal T cell expressed and secreted (RANTES) with increasing severity of alcohol dependence was observed, independent of cigarette smoking (P = 0.0001). Cigarette smoking duration was associated with higher IL-1β (P = 0.0009) but lower VEGF (P = 0.0007); cigarette smoking intensity was characterized by higher IL-1β and lower VEGF and diminished IL-12 (P = 0.0004). No synergistic effects of AUDs and cigarette smoking were observed. Collectively, our work suggests that AUDs and cigarette smoking each contribute to a proinflammatory pulmonary milieu in human subjects through independent effects on BAL RANTES and IL-1β. Furthermore, cigarette smoking additionally influences BAL IL-12 and VEGF that may be relevant to the pulmonary immune response.

An in vitro model of human acute ethanol exposure that incorporates CXCR3- and CXCR4-dependent recruitment of immune cells

Alcoholic liver disease (ALD) is one of the commonest causes of cirrhosis and liver failure in the developed world. Hepatic inflammation is the critical stage in progression of both ALD and non-ALD, but it remains difficult to study the underlying mechanisms in a human system, and current animal models do not fully recapitulate human liver disease. We developed a human tissue-based system to study lymphocyte recruitment in response to ethanol challenge. Precision-cut liver slices (PCLS) from human livers were incubated in culture, and hepatic function was determined by albumin production, 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide assay, glucose uptake responses, and morphometric assessment. Responses of tissue and lymphocytes to ethanol exposure were determined by PCR, flow cytometry, histology, and lymphocyte infiltration assays. Human PCLS demonstrated appropriate upregulation of CYP2E1, ADH1α, and ADH3 in response to ethanol treatment. Ethanol also induced expression of endothelial VCAM-1 and ICAM-1, production of sICAM-1 and CXCL8, and the chemokine receptors CXCR3 and CXCR4 on CD4 and CD8 lymphocytes. CXCR3- and CXCR4-dependent migration of lymphocytes into the tissue increased significantly in response to treatment with ethanol. We have demonstrated that ethanol increases chemokine receptor expression and lymphocyte recruitment into human liver tissue, suggesting that it may operate directly to promote hepatitis in ALD. The physiological and pathophysiological responses of the PCLS to ethanol in vitro highlight the potential of this assay for dissecting the molecular mechanisms underlying human liver inflammation and as a screening tool for novel therapeutics.

Toll-like receptors in liver disease

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Recent studies demonstrated that Toll-like receptors, the sensors of microbial and endogenous danger signals, are expressed and activated in innate immune cells as well as in parenchymal cells in the liver and thereby contribute to ALD and NASH. In this review, we emphasize the importance of gut-derived endotoxin and its recognition by TLR4 in the liver. The significance of TLR-induced intracellular signaling pathways and cytokine production as well as the contribution of individual cell types to the inflammation is evaluated. The contribution of TLR signaling to the induction of liver fibrosis and to the progression of liver pathology mediated by viral pathogens is reviewed in the context of ALD and NASH.

ATF4 is directly recruited by TLR4 signaling and positively regulates TLR4-trigged cytokine production in human monocytes

Toll-like receptors (TLRs) are sentinels of the host defense system, which recognize a large number of microbial pathogens. The host defense system may be inefficient or inflammatory diseases may develop if microbial recognition by TLRs and subsequent TLR-triggered cytokine production are deregulated. Activating transcription factor 4 (ATF4), a member of the ATF/CREB transcription factor family, is an important factor that participates in several pathophysiological processes. In this report, we found that ATF4 is also involved in the TLR-mediated innate immune response, which participates in TLR4 signal transduction and mediates the secretion of a variety of cytokines. We observed that ATF4 is activated and translocates to the nucleus following lipopolysaccharide (LPS) stimulation via the TLR4-MyD88-dependent pathway. Additionally, a cytokine array assay showed that some key inflammatory cytokines, such as IL-6, IL-8 and RANTES, are positively regulated by ATF4. We also demonstrate that c-Jun directly binds to ATF4, thereby promoting the secretion of inflammatory cytokines. Taken together, these results indicate that ATF4 acts as a positive regulator in TLR4-triggered cytokine production.

Hypoxia and HIF-1 increase S100A8 and S100A9 expression in prostate cancer

S100A8 and S100A9, two heterodimer-forming members of the cytosolic S100 Ca(2+) signaling protein family, are overexpressed in various cancer types, including prostate cancer. They act as proinflammatory danger signals when secreted to the extracellular space and are thought to play an important role during tumorigenesis, affecting inflammatory processes, proliferation, invasion and metastasis of tumor cells. Despite this fact, little is known about tumor environmental factors influencing S100A8/A9 expression. The aim of this study was to test the effect of hypoxia and its master transcriptional regulator hypoxia-inducible factor 1 (HIF-1) on S100A8/A9 expression. Hypoxia treatment resulted in induction of S100A8/A9 protein and mRNA expression in prostate epithelial BPH-1 cells, the latter was also confirmed in the prostate cancer cell lines PC-3 and DU-145. Furthermore, overexpression of HIF-1α caused increase in S100A8/A9 protein and mRNA expression as well as secretion. Functional hypoxia response elements mediating promoter activation on HIF-1α overexpression were identified within the S100A8 and S100A9 promoters using promoter luciferase reporter constructs. Binding of HIF-1α to S100A8 and S100A9 promoters was confirmed by chromatin immunoprecipitation. Immunohistochemical analysis of a prostate cancer tissue array showed clear correlation of S100A8 and S100A9 with HIF-1α expression. Multivariate proportional hazard analysis revealed association of high S100A9 level with time to prostate cancer recurrence. In conclusion, we identified hypoxia and HIF-1 as novel regulators of S100A8/A9 expression in prostate cancer. S100A9 might be useful as prognostic marker for prostate cancer recurrence after radical prostatectomy.

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.

15th International Symposium on Cells of the Hepatic Sinusoid, 2010

This is a meeting report of the presentations given at the 15th International Symposium on Cells of the Hepatic Sinusoid, held in 2010. The areas covered include the contributions of the various liver cell populations to liver disease, molecular and cellular targets involved in steatohepatitis, hepatic fibrosis and cancer and regenerative medicine. In addition to a review of the science presented at the meeting, this report provides references to recent literature on the topics covered at the meeting.

TLRs, Alcohol, HCV, and Tumorigenesis

Chronic liver damage caused by viral infection, alcohol, or obesity can result in increased risk for hepatocellular carcinoma (HCC). Ample epidemiological evidence suggests that there is a strong synergism between hepatitis C virus (HCV) and alcoholic liver diseases (ALD). The Toll-like receptor (TLR) signaling pathway is upregulated in chronic liver diseases. Alcoholism is associated with endotoxemia that stimulates expression of proinflammatory cytokine expression and inflammation in the liver and fat tissues. Recent studies of HCC have centered on cancer-initiating stem cell (CSC), including detection of CSC in cancer, identification of CSC markers, and isolation of CSC from human HCC cell lines. Synergism between alcohol and HCV may lead to liver tumorigenesis through TLR signaling.

Alcohol induces RNA polymerase III-dependent transcription through c-Jun by co-regulating TATA-binding protein (TBP) and Brf1 expression

Chronic alcohol consumption is associated with steatohepatitis and cirrhosis, enhancing the risk for hepatocellular carcinoma. RNA polymerase (pol) III transcribes a variety of small, untranslated RNAs, including tRNAs and 5S rRNAs, which determine the biosynthetic capacity of cells. Increased RNA pol III-dependent transcription, observed in transformed cells and human tumors, is required for oncogenic transformation. Given that alcohol consumption increases risk for liver cancer, we examined whether alcohol regulates this class of genes. Ethanol induces RNA pol III-dependent transcription in both HepG2 cells and primary mouse hepatocytes in a manner that requires ethanol metabolism and the activation of JNK1. This regulatory event is mediated, at least in part, through the ability of ethanol to induce expression of the TFIIIB components, Brf1, and the TATA-binding protein (TBP). Induction of TBP, Brf1, and RNA pol III-dependent gene expression is driven by enhanced c-Jun expression. Ethanol promotes a marked increase in the direct recruitment of c-Jun to TBP, Brf1, and tRNA gene promoters. Chronic alcohol administration in mice leads to enhanced expression of TBP, Brf1, tRNA, and 5S rRNA gene transcription in the liver. These alcohol-dependent increases are more pronounced in transgenic animals that express the HCV NS5A protein that display increased incidence of liver tumors. Together, these results identify a new class of genes that are regulated by alcohol through the co-regulation of TFIIIB components and define a central role for c-Jun in this process.

Progress in developing rat models of hepatic encephalopathy

Hepatic encephalopathy is a serious complication of acute and chronic liver diseases and has a high mortality rate. The pathogenesis of hepatic encephalopathy remains unclear, and there is no means of prevention or effective cure for the disease. Therefore, there is an urgent need for the basic and clinical research of hepatic encephalopathy to elucidate its pathogenesis. The development of animal models is important for elucidating the pathogenesis of hepatic encephalopathy and providing new avenues for diagnosis and therapy of the disease. Among a variety of animal models, rat model is applied most widely for similarity to humans, repeatability, reliability, applicability, controllability, simplicity and economy. In this paper, we briefly review various rat models of hepatic encephalopathy that have different origins.

Role of CCR5 and its ligands in the control of vascular inflammation and leukocyte recruitment required for acute excitotoxic seizure induction and neural damage

Chemokines may play a role in leukocyte migration across the blood-brain barrier (BBB) during neuroinflammation and other neuropathological processes, such as epilepsy. We investigated the role of the chemokine receptor CCR5 in seizures. We used a rat model based on intraperitoneal kainic acid (KA) administration. Four months before KA injection, adult rats were given femoral intramarrow inoculations of SV (RNAiR5-RevM10.AU1), which carries an interfering RNA (RNAi) against CCR5, plus a marker epitope (AU1), or its monofunctional RNAi-carrying homologue, SV(RNAiR5). This treatment lowered expression of CCR5 in circulating cells. In control rats, seizures induced elevated expression of CCR5 ligands MIP-1α and RANTES in the microvasculature, increased BBB leakage and CCR5(+) cells, as well as neuronal loss, inflammation, and gliosis in the hippocampi. Animals given either the bifunctional or the monofunctional vector were largely protected from KA-induced seizures, neuroinflammation, BBB damage, and neuron loss. Brain CCR5 mRNA was reduced. Rats receiving RNAiR5-bearing vectors showed far greater repair responses: increased neuronal proliferation, and decreased production of MIP-1α and RANTES. Controls received unrelated SV(BUGT) vectors. Decrease in CCR5 in circulating cells strongly protected from excitotoxin-induced seizures, BBB leakage, CNS injury, and inflammation, and facilitated neurogenic repair.

Ethanol-induced HO-1 and NQO1 are differentially regulated by HIF-1alpha and Nrf2 to attenuate inflammatory cytokine expression

Oxidative stress plays an important role in alcohol-induced inflammation and liver injury. Relatively less is known about how Kupffer cells respond to oxidative stress-induced expression of heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase (NQO1) to blunt inflammation and liver injury. We showed that Kupffer cells from ethanol-fed rats and ethanol-treated rat Kupffer cells and THP-1 cells displayed increased mRNA expression of HO-1, NQO1, and hypoxia-inducible factor-1α (HIF-1α). Our studies showed that silencing with HIF-1α and JNK-1 siRNAs attenuated ethanol-mediated mRNA expression of HO-1, but not NQO1, whereas Nrf2 siRNA attenuated the mRNA expression of both HO-1 and NQO1. Additionally, JunD but not JunB formed an activator protein-1 (AP-1) oligomeric complex to augment HO-1 promoter activity. Ethanol-induced HO-1 transcription involved antioxidant response elements, hypoxia-response elements, and an AP-1 binding motif in its promoter, as demonstrated by mutation analysis of the promoter, EMSA, and ChIP. Furthermore, livers of ethanol-fed c-Jun(fl/fl) mice showed reduced levels of mRNA for HO-1 but not of NQO1 compared with ethanol-fed control rats, supporting the role of c-Jun or the AP-1 transcriptional complex in ethanol-induced HO-1 expression. Additionally, attenuation of HO-1 levels in ethanol-fed c-Jun(fl/fl) mice led to increased proinflammatory cytokine expression in the liver. These results for the first time show that ethanol regulates HO-1 and NQO1 transcription by different signaling pathways. Additionally, up-regulation of HO-1 protects the liver from excessive formation of inflammatory cytokines. These studies provide novel therapeutic targets to ameliorate alcohol induced inflammation and liver injury.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Toll-like receptors in the pathogenesis of alcoholic liver disease

In the multifactorial pathophysiology of alcoholic liver disease (ALD), inflammatory cascade activation plays a central role. Recent studies demonstrated that Toll-like Receptors, the sensors of microbial and endogenous danger signals, are expressed and activated in innate immune cells as well as in parenchymal cells in the liver and thereby contribute to ALD. In this paper, we discuss the importance of gut-derived endotoxin and its recognition by TLR4. The significance of TLR-induced intracellular signaling pathways and cytokine production as well as the contribution of reactive oxygen radicals is evaluated. The contribution of TLR signaling to induction of liver fibrosis and hepatocellular cancer is reviewed in the context of alcohol-induced liver disease.

Intralesional delivery of dendritic cells engineered to express T-bet promotes protective type 1 immunity and the normalization of the tumor microenvironment

T-bet (Tbx21), a T-box transcription factor, has been previously identified as a master regulator of type 1 T cell polarization. We have also recently shown that the genetic engineering of human dendritic cells (DCs) to express human T-bet cDNA yields type 1-polarizing APCs in vitro (1). In the present study, murine CD11c(+) DCs were transduced with a recombinant adenovirus encoding full-length murine T-bets (DC.mTbets) and analyzed for their immunomodulatory functions in vitro and in vivo. Within the range of markers analyzed, DC.mTbets exhibited a control DC phenotype and were indistinguishable from control DCs in their ability to promote allogenic T cell proliferation in MLR in vitro. However, DC.mTbets were superior to control DCs in promoting Th1 and Tc1 responses in vitro via a mechanism requiring DC-T cell interaction or the close proximity of these two cell types and that can only partially be explained by the action of DC-elaborated IL-12p70. When injected into day 7 s.c. CMS4 sarcoma lesions growing in syngenic BALB/c mice, DC.mTbets dramatically slowed tumor progression (versus control DCs) and extended overall survival via a mechanism dependent on both CD4(+) and CD8(+) T cells and, to a lesser extent, asialoGM1(+) NK cells. DC.mTbet-based therapy also promoted superior tumor-specific Tc1 responses in the spleens and tumor-draining lymph nodes of treated animals, and within the tumor microenvironment it inhibited the accumulation of CD11b(+)Gr1(+) myeloid-derived suppressor cells and normalized CD31(+) vascular structures. These findings support the potential translational utility of DC.Tbets as a therapeutic modality in the cancer setting.

In hepatic fibrosis, liver sinusoidal endothelial cells acquire enhanced immunogenicity

The normal liver is characterized by immunologic tolerance. Primary mediators of hepatic immune tolerance are liver sinusoidal endothelial cells (LSECs). LSECs block adaptive immunogenic responses to Ag and induce the generation of T regulatory cells. Hepatic fibrosis is characterized by both intense intrahepatic inflammation and altered hepatic immunity. We postulated that, in liver fibrosis, a reversal of LSEC function from tolerogenic to proinflammatory and immunogenic may contribute to both the heightened inflammatory milieu and altered intrahepatic immunity. We found that, after fibrotic liver injury from hepatotoxins, LSECs become highly proinflammatory and secrete an array of cytokines and chemokines. In addition, LSECs gain enhanced capacity to capture Ag and induce T cell proliferation. Similarly, unlike LSECs in normal livers, in fibrosis, LSECs do not veto dendritic cell priming of T cells. Furthermore, whereas in normal livers, LSECs are active in the generation of T regulatory cells, in hepatic fibrosis LSECs induce an immunogenic T cell phenotype capable of enhancing endogenous CTLs and generating potent de novo CTL responses. Moreover, depletion of LSECs from fibrotic liver cultures mitigates the proinflammatory milieu characteristic of hepatic fibrosis. Our findings offer a critical understanding of the role of LSECs in modulating intrahepatic immunity and inflammation in fibro-inflammatory liver disease.