Acute alcohol activates STAT3, AP-1, and Sp-1 transcription factors via the family of Src kinases to promote IL-10 production in human monocytes

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

Alleviating Effect of Lacticaseibacillus rhamnosus 1.0320 Combined with Dihydromyricetin on Acute Alcohol Exposure-Induced Hepatic Impairment: Based on Short-Chain Fatty Acids and Adenosine 5'-Monophosphate-Activated Protein Kinase-Mediated Lipid Metabolism Signaling Pathway

Excessive drinking has been listed by the World Health Organization as the fifth major risk factor; especially the liver, as the core organ of alcohol metabolism, is prone to organic lesions. Probiotics have received attention due to their bioactivity for liver protection. The beneficial effects of probiotics on hosts are related to their physiological functions. Therefore, based on the concept of second-generation synbiotes, this study explored the protective effects of four dietary polyphenols on the stress tolerance, hydrophobicity, adhesion, and digestive characteristics of L. rhamnosus 1.0320. L. rhamnosus 1.0320 had the best synergistic effect with dihydromyricetin (DMY). Therefore, this combination was selected as a synbiotic supplement to explore the protective effect on acute alcohol exposure-induced hepatic impairment. The results showed that L. rhamnosus 1.0320 combined with DMY restored the intestinal barrier by upregulating short-chain fatty acid levels and activated the adenosine 5'-monophosphate-activated protein kinase-mediated lipid metabolism pathway to inhibit oxidative stress, inflammation, and lipid accumulation in the liver. Furthermore, 10⁹ CFU/mouse/d L. rhamnosus 1.0320 and 50 mg/kg/d DMY by gavage were identified as the optimal doses for protection against acute alcohol expose-induced hepatic impairment. This study provides new insights into alleviating acute alcoholic hepatic impairment by targeting intestinal metabolites through the gut-liver axis.

Tim-3 downregulation by Toxoplasma gondii infection contributes to decidual dendritic cell dysfunction

Background

Women in early pregnancy infected by Toxoplasma gondii may have severe adverse pregnancy outcomes, such as spontaneous abortion and fetal malformation. The inhibitory molecule T cell immunoglobulin and mucin domain 3 (Tim-3) is highly expressed on decidual dendritic cells (dDCs) and plays an important role in maintaining immune tolerance. However, whether T. gondii infection can cause dDC dysfunction by influencing the expression of Tim-3 and further participate in adverse pregnancy outcomes is still unclear.

Methods

An abnormal pregnancy model in Tim-3-deficient mice and primary human dDCs treated with Tim-3 neutralizing antibodies were used to examine the effect of Tim-3 expression on dDC dysfunction after T. gondii infection.

Results

Following T. gondii infection, the expression of Tim-3 on dDCs was downregulated, those of the pro-inflammatory functional molecules CD80, CD86, MHC-II, tumor necrosis factor-α (TNF-α), and interleukin-12 (IL-12) were increased, while those of the tolerant molecules indoleamine 2,3-dioxygenase (IDO) and interleukin-10 (IL-10) were significantly reduced. Tim-3 downregulation by T. gondii infection was closely associated with an increase in proinflammatory molecules and a decrease in tolerant molecules, which further resulted in dDC dysfunction. Moreover, the changes in Tim-3 induced by T. gondii infection further reduced the secretion of the cytokine IL-10 via the SRC-signal transducer and activator of transcription 3 (STAT3) pathway, which ultimately contributed to abnormal pregnancy outcomes.

Conclusions

Toxoplasma gondii infection can significantly downregulate the expression of Tim-3 and cause the aberrant expression of functional molecules in dDCs. This leads to dDC dysfunction, which can ultimately contribute to abnormal pregnancy outcomes. Further, the expression of the anti-inflammatory molecule IL-10 was significantly decreased by Tim-3 downregulation, which was mediated by the SRC-STAT3 signaling pathway in dDCs after T. gondii infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05506-1.

Antioxidative and Anti-Inflammatory Effects of Lactobacillus plantarum ZS62 on Alcohol-Induced Subacute Hepatic Damage

Lactobacillus plantarum ZS62 is a newly isolated strain from naturally fermented yogurt that might offer some beneficial effects in the setting of alcohol-induced subacute liver injury. The liver-protective effect of L. plantarum ZS62 was investigated by gavage feeding of mice with this Lactobacillus strain (1 × 10⁹ CFU/kg _BW) before alcohol administration daily for 7 days. We then compared hepatic morphology, liver function indexes, liver lipid levels, inflammation, oxidative stress levels, and mRNA expression of oxidative metabolism- and inflammation-related genes in mice that had been pretreated with Lactobacillus plantarum versus control mice that had not been pretreated. Our results showed that L. plantarum ZS62 attenuated alcohol-induced weight loss; prevented morphological changes in hepatocytes; reduced markers of liver damage including aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), hyaluronidase (HAase), precollagen III (PC III), and inflammatory cytokines; and enhanced the antioxidative status. L. plantarum ZS62 also significantly downregulated inflammation-related genes and upregulated lipid- and oxidative-metabolism genes. Thus, Lactobacillus plantarum pretreatment appears to confer hepatic protection by reducing inflammation and enhancing antioxidative capacity. The protective effect of L. plantarum ZS62 was even better than that of a commonly used commercial lactic acid bacteria (Lactobacillus delbrueckii subsp. Bulgaricus). The L. plantarum ZS62 might be a potentially beneficial prophylactic treatment for people who frequently drink alcoholic beverages.

Transcriptional, Epigenetic, and Functional Reprogramming of Monocytes From Non-Human Primates Following Chronic Alcohol Drinking

Chronic heavy drinking (CHD) of alcohol is a known risk factor for increased susceptibility to bacterial and viral infection as well as impaired wound healing. Evidence suggests that these defects are mediated by a dysregulated inflammatory response originating from myeloid cells, notably monocytes and macrophages, but the mechanisms remain poorly understood. Our ability to study CHD is impacted by the complexities of human drinking patterns and behavior as well as comorbidities and confounding risk factors for patients with alcohol use disorders. To overcome these challenges, we utilized a translational rhesus macaque model of voluntary ethanol self-administration that closely recapitulates human drinking patterns and chronicity. In this study, we examined the effects of CHD on blood monocytes in control and CHD female macaques after 12 months of daily ethanol consumption. While monocytes from CHD female macaques generated a hyper-inflammatory response to ex vivo LPS stimulation, their response to E. coli was dampened. In depth scRNA-Seq analysis of purified monocytes revealed significant shifts in classical monocyte subsets with accumulation of cells expressing markers of hypoxia (HIF1A) and inflammation (NFkB signaling pathway) in CHD macaques. The increased presence of monocyte subsets skewed towards inflammatory phenotypes was complemented by epigenetic analysis, which revealed higher accessibility of promoter regions that regulate genes involved in cytokine signaling pathways. Collectively, data presented in this manuscript demonstrate that CHD shifts classical monocyte subset composition and primes the monocytes towards a more hyper-inflammatory response to LPS, but compromised pathogen response.

Alcohol alters IL-6 Signal Transduction in the CNS of Transgenic Mice with Increased Astrocyte Expression of IL-6

Neuroimmune factors, including the cytokine interleukin-6 (IL-6), are important chemical regulators of central nervous system (CNS) function under both physiological and pathological conditions. Elevated expression of IL-6 occurs in the CNS in a variety of disorders associated with altered CNS function, including excessive alcohol use. Alcohol-induced production of IL-6 has been reported for several CNS regions including the cerebellum. Cerebellar actions of alcohol occur through a variety of mechanisms, but alcohol-induced changes in signal transduction, transcription, and translation are known to play important roles. IL-6 is an activator of signal transduction that regulates gene expression. Thus, alcohol-induced IL-6 production could contribute to cerebellar effects of alcohol by altering gene expression, especially under conditions of chronic alcohol abuse, where IL-6 levels could be habitually elevated. To gain an understanding of the effects of alcohol on IL-6 signal transduction, we studied activation/expression of IL-6 signal transduction partners STAT3 (Signal Transducer and Activator of Transcription), CCAAT-enhancer binding protein (C/EBP) beta, and p42/p44 mitogen-activated protein kinase (MAPK) at the protein level. Cerebella of transgenic mice that express elevated levels of astrocyte produced IL-6 in the CNS were studied. Results show that the both IL-6 and chronic intermittent alcohol exposure/withdrawal affect IL-6 signal transduction partners and that the actions of IL-6 and alcohol interact to alter activation/expression of IL-6 signal transduction partners. The alcohol/IL-6 interactions may contribute to cerebellar actions of alcohol, whereas the effects of IL-6 alone may have relevance to cerebellar changes occurring in CNS disorders associated with elevated levels of IL-6.

The Binary Classification of Protein Kinases

In an earlier publication a binary model for chronic diseases classification has been proposed. According to the model, chronic diseases were classified as “high Treg” or “low Treg” diseases, depending on whether the immune response is anti- or pro-inflammatory and assuming that regulatory T cells are major determinants of the response. It turned out that most cancers are “high Treg” diseases, while autoimmune diseases are “low Treg”. This paper proposes a molecular cause for this binary response. The mechanism proposed depends on the effect of protein kinases on the immune system. Thus, protein kinases are classified as anti- or pro-inflammatory kinases depending on whether they drive “high Treg” or “low Treg” diseases. Observations reported in the earlier publication can be described in terms of anti-inflammatory kinase (AIK) or pro-inflammatory kinase (PIK) activity. Analysis of literature data reveals that the two classes of kinases display distinctive properties relating to their interactions with pathogens and environmental factors. Pathogens that promote Treg activity (“high Treg” pathogens) activate AIKs, while pathogens that suppress Treg activity (“low Treg” pathogens) activate PIKs. Diseases driven by AIKs are associated with “high Treg” pathogens while those diseases driven by PIKs are associated with “low Treg” pathogens. By promoting the activity of AIKs, alcohol consumption increases the risk of “high Treg” cancers but decreases the risk of some “low Treg” autoimmune diseases. JAK1 gain-of-function mutations are observed at high frequencies in autoimmune diseases while JAK1 loss-of-function mutations are observed at high frequencies in cancers with high tumor-infiltrating Tregs. It should also be noted that the corresponding two classes of protein kinase inhibitors are mutually exclusive in terms of their approved therapeutic indications. There is no protein kinase inhibitor that is approved for the treatment of both autoimmune diseases and “high Treg” cancers. Although there are exceptions to the conclusions presented above, these conclusions are supported by the great bulk of published data. It therefore seems that the binary division of protein kinases is a useful tool for elucidating (at the molecular level) many distinctive properties of cancers and autoimmune diseases.

Anti-inflammatory Effects of Alcohol Are Associated with JNK-STAT3 Downregulation in an In Vitro Inflammation Model in HepG2 Cells

Background

In several preclinical and in vitro models of acute inflammation, alcohol (ethanol, EtOH) has been described as an immunomodulatory agent. Similarly, in different pathologies, clinical observations have confirmed either pro- or anti-inflammatory effects of EtOH. The liver plays an important role in immunity and alcohol metabolism; therefore, we analysed dose- and time-dependent effects of EtOH on the inflammatory response of human liver cells in an in vitro model of acute inflammation.

Methods

HepG2 cells were stimulated with IL-1β and subsequently exposed to EtOH in a low or high dose (85 mM, LoD or 170 mM, HiD) for 1 h (acute exposure) or 72 h (prolonged exposure). IL-6 and TNF-α release was determined by ELISA. Cell viability, adhesion of isolated neutrophils to HepG2 monolayers, their ICAM-1 expression, and the activation of stress-induced protein kinase/c-Jun N-terminal kinase (SAPK/JNK) or signal transducer and activator of transcription 3 (STAT3) were analysed.

Results

In this experimental design, EtOH did not markedly change the cell viability. Acute and prolonged exposure to EtOH significantly reduced dose-independent IL-1β-induced IL-6 and TNF-α release, as well as adhesion capacity to pretreated HepG2 cells. Acute exposure to EtOH significantly decreased the percentage of ICAM-1-expressing cells. IL-1β stimulation notably increased the activation of SAPK/JNK. However, low-dose EtOH exposure reduced this activation considerably, in contradiction to high-dose EtOH exposure. Acute exposure to LoD EtOH significantly diminished the IL-1β-induced STAT3 activation, whereas an acute exposure of cells to either HiD EtOH or in a prolonged setting showed no effects on STAT3 activation.

Conclusion

EtOH exerts anti-inflammatory potential in this in vitro model of hepatic inflammation. These effects are associated with the reduced activation of JNK/STAT3 by EtOH, particularly in the condition of acute exposure to low-dose EtOH.

Opening a Window on Attention: Adjuvant Therapies for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), most commonly known as Crohn's disease (CD) and ulcerative disease (UC), is a chronic and relapsing intestinal disease which cannot be cured completely. The prevalence of IBD in Europe and in North America has increased over the past 20 years. As most IBD patients are young at onset, their quality of life (QOL) can be influenced to varying degrees. Thus, current treatment goals are typically focused on preventing complications, including maintaining clinical remission and improving the QOL. Adjuvant therapies have been widely concerned as an effective treatment in alleviating IBD symptoms, including dietary intervention, traditional Chinese medicine, smoking, alcohol, and physical activities. This review focuses on different ancillary therapies for IBD treatments, in particular the mechanism of reducing inflammation based on the actual data from research studies. Moreover, comparing the latest data, this review also presented potential future prospect for adjuvant therapies.

Mesenchymal stem cells alleviate liver injury induced by chronic-binge ethanol feeding in mice via release of TSG6 and suppression of STAT3 activation

Background

Mesenchymal stem cells (MSCs) are a population of pluripotent cells that might be used for treatment of liver disease. However, the efficacy of MSCs for mice with alcoholic hepatitis (AH) and its underlying mechanism remains unclear.

Methods

MSCs were isolated from the bone marrow (BM) of 4–6-week-old male C57BL/6 N mice. AH was induced in female mice by chronic-binge ethanol feeding for 10 days. The mice were given intraperitoneal injections of MSCs with or without transfection or AG490, recombinant mouse tumor necrosis factor (TNF)-α-stimulated gene/protein 6 (rmTSG-6), or saline at day 10. Blood samples and hepatic tissues were collected at day 11. Various assays such as biochemistry, histology, and flow cytometry were performed.

Results

MSCs reduced AH in mice, decreasing liver/body weight ratio, liver injury, blood and hepatic lipids, malondialdehyde, interleukin (IL)-6, and TNF-ɑ, but increasing glutathione, IL-10, and TSG-6, compared to control mice. Few MSCs engrafted into the inflamed liver. Knockdown of TSG-6 in MSCs significantly attenuated their effects, and injection of rmTSG-6 achieved similar effects to MSCs. The signal transducer and activator of transcription 3 (STAT3) was activated in mice with AH, and MSCs and rmTSG-6 inhibited the STAT3 activation. Injection of MSCs plus AG490 obtained more alleviation of liver injury than MSCs alone.

Conclusions

BM-MSCs injected into mice with AH do not engraft the liver, but they secrete TSG-6 to reduce liver injury and to inhibit STAT3 activation.

Ethanol and Cytokines in the Central Nervous System

The innate immune system plays a critical role in the ethanol-induced neuroimmune response in the brain. Ethanol initiates the innate immune response via activation of the innate immune receptors Toll-like receptors (TLRs, e.g., TLR4, TLR3, TLR7) and NOD-like receptors (inflammasome NLRs) leading to a release of a plethora of chemokines and cytokines and development of the innate immune response. Cytokines and chemokines can have pro- or anti-inflammatory properties through which they regulate the immune response. In this chapter, we will focus on key cytokines (e.g., IL-1, IL-6, TNF-α) and chemokines (e.g., MCP-1/CCL2) that mediate the ethanol-induced neuroimmune responses. In this regard, we will use IL-1β, as an example cytokine, to discuss the neuromodulatory properties of cytokines on cellular properties and synaptic transmission. We will discuss their involvement through a set of evidence: (1) changes in gene and protein expression following ethanol exposure, (2) association of gene polymorphisms (humans) and alterations in gene expression (animal models) with increased alcohol intake, and (3) modulation of alcohol-related behaviors by transgenic or pharmacological manipulations of chemokine and cytokine systems. Over the last years, our understanding of the molecular mechanisms mediating cytokine- and chemokine-dependent regulation of immune responses has advanced tremendously, and we review evidence pointing to cytokines and chemokines serving as neuromodulators and regulators of neurotransmission.

Chronic heavy drinking drives distinct transcriptional and epigenetic changes in splenic macrophages

Background

Chronic heavy alcohol drinking (CHD) leads to significant organ damage, increased susceptibility to infections, and delayed wound healing. These adverse outcomes are believed to be mediated by alterations in the function of myeloid cells; however, the mechanisms underlying these changes are poorly understood.

Methods

We determined the impact of CHD on the phenotype of splenic macrophages using flow cytometry. Changes in functional responses to LPS were measured using luminex and RNA-Seq. Finally, alterations in chromatin accessibility were uncovered using ATAC-Seq.

Findings

A history of CHD led to increased frequency of splenic macrophages that exhibited a heightened activation state at resting. Additionally, splenic macrophages from CHD animals generated a larger inflammatory response to LPS, both at protein and gene expression levels. Finally, CHD resulted in increased levels of H3K4me3, a histone mark of active promoters, as well as chromatin accessibility at promoters and intergenic regions that regulate inflammatory responses.

Interpretation

These findings suggest that a history of CHD alters the immune fitness of tissue-resident macrophages via epigenetic mechanisms.

Fund

National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH) - R24AA019431, U01 AA13641, U01 AA13510, R21AA021947, and R21AA025839.

Aryl Hydrocarbon Receptor Promotes IL-10 Expression in Inflammatory Macrophages Through Src-STAT3 Signaling Pathway

The aryl hydrocarbon receptor (AhR) is an important immune regulator with a role in inflammatory response. However, the role of AhR in IL-10 production by inflammatory macrophages is currently unknown. In this study, we investigated LPS-induced IL-10 expression in macrophages from AhR-KO mice and AhR-overexpressing RAW264.7 cells. AhR was highly expressed after LPS stimulation through NF-κB pathway. Loss of AhR resulted in reduced IL-10 expression in LPS-induced macrophages. Moreover, the IL-10 expression was elevated in LPS-induced AhR-overexpressing RAW264.7 cells. Maximal IL-10 expression was dependent on an AhR non-genomic pathway closely related to Src and STAT3. Furthermore, AhR-associated Src activity was responsible for tyrosine phosphorylation of STAT3 and IL-10 expression by inflammatory macrophages. Adoptive transfer of AhR-expressing macrophages protected mice against LPS-induced peritonitis associated with high IL-10 production. In conclusion, we identified the AhR-Src-STAT3-IL-10 signaling pathway as a critical pathway in the immune regulation of inflammatory macrophages, It suggests that AhR may be a potential therapeutic target in immune response.

Differential regulation of the TLR4 signalling pathway in post-mortem prefrontal cortex and cerebellum in chronic schizophrenia: Relationship with SP transcription factors

Alterations in innate immunity may underlie the pathophysiology of schizophrenia (SZ). Toll-like receptor-4 (TLR4) is a master element of innate immunity. The specificity proteins (SPs), transcription factors recently implicated in SZ, are putative regulatory agents of this. This work was aimed at describing alterations in the TLR4 signalling pathway in postmortem brain prefrontal cortex (PFC) and cerebellum (CB) of 16 chronic SZ patients and 14 controls. The possible association of TLR4 pathway with SP1 and SP4 and SZ negative symptomatology is explored. In PFC, TLR4/myeloid differentiation factor 88 (MyD88)/inhibitory subunit of nuclear factor kappa B alpha (IκBα) protein levels were lower in SZ patients, while nuclear transcription factor-κB (NFκB) activity, cyclooxygenase-2 (COX-2) expression and the lipid peroxidation index malondialdehyde (MDA) appeared increased. The pattern of changes in CB is opposite, except for COX-2 expression that remained augmented and MDA levels unaltered. Network interaction analysis showed that TLR4/MyD88/IκBα/NFκB/COX-2 pathway was coupled in PFC and uncoupled in CB. SP4 co-expressed with TLR4 and NFκB in PFC and both SP1 and SP4 co-expressed with NFκB in CB. In PFC, correlation analysis found an inverse relationship between NFκB and negative symptoms. In summary, we found brain region-specific alterations in the TLR4 signalling pathway in chronic SZ, in which SP transcription factors could participate at different levels. Further studies are required to elucidate the regulatory mechanisms of innate immunity in SZ and its relationship with symptoms.

The complex roles of STAT3 and STAT5 in maintaining redox balance: Lessons from STAT-mediated xCT expression in cancer cells

STAT3 and STAT5 mediate diverse cellular processes, transcriptionally regulating gene expression and interacting with cytoplasmic proteins. Their canonical activity is stimulated by cytokines/growth factors through JAK-STAT signaling. As targets of oncogenes with intrinsic tyrosine kinase activity, STAT3 and STAT5 become constitutively active in hematologic neoplasms and solid tumors, promoting cell proliferation and survival and modulating redox homeostasis. This review summarizes reactive oxygen species (ROS)-regulated STAT activation and how STATs influence ROS production. ROS-induced effects on post-translational modifications are presented, and STAT3/5-mediated regulation of xCT, a redox-sensitive target up-regulated in numerous cancers, is discussed with regard to transcriptional cross-talk.

CCM111, the water extract of Antrodia cinnamomea, regulates immune-related activity through STAT3 and NF-κB pathways

Antrodia cinnamomea (AC) exhibits many bioactivities, including anti-inflammatory, anti-cancer, and hepatoprotection activities. Many researchers have studied the functions of the components or fractions of AC, but the functions of the original extractions of AC have not been studied. In addition, the detailed relationship between AC and immune-related signaling pathways is unclear. In this study, we screened the effects of CCM111, which is the extract of AC, on seven immune-related signaling pathways and further investigated whether CCM111 can influence inflammation. Interestingly, our results showed that CCM111 significantly inhibited the IL-6-stimulated STAT3 pathway and the LPS-stimulated NF-κB pathway in macrophages. CCM111 also decreased the phosphorylation of STAT3, Tyk2 and the nuclear translocation of p65. Moreover, CCM111 and F4, a fraction of CCM111, down-regulated nitric oxide (NO) production, the protein levels of iNOS and COX-2, and inflammatory cytokines in macrophage cells. Therefore, our study suggested that CCM111 has the potential to be developed as an effective anti-inflammatory agent.

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.

Role of cytokines and chemokines in alcohol-induced tumor promotion

Excessive chronic alcohol consumption has become a worldwide health problem. The oncogenic effect of chronic alcohol consumption is one of the leading concerns. The mechanisms of alcohol-induced tumorigenesis and tumor progression are largely unknown, although many factors have been implicated in the process. This review discusses the recent progress in this research area with concentration on alcohol-induced dysregulation of cytokines and chemokines. Based on the available evidence, we propose that alcohol promotes tumor progression by the dysregulation of the cytokine/chemokine system. In addition, we discuss specific transcription factors and signaling pathways that are involved in the action of these cytokines/chemokines and the oncogenic effect of alcohol. This review provides novel insight into the mechanisms of alcohol-induced tumor promotion.

GITRL modulates the activities of p38 MAPK and STAT3 to promote Th17 cell differentiation in autoimmune arthritis

The glucocorticoid-induced TNFR family-related protein (GITR) and its ligand play a critical role in the pathogenesis of autoimmune arthritis by enhancing the Th17 cell response, but their molecular mechanisms remain largely unclear. This study aims to define the role of p38 mitogen-activated protein kinases (MAPK) and signal transducer and activator of transcription 3 (STAT3) signaling in GITRL-induced Th17 cells in autoimmune arthritis. We found that the p38 phosphorylation was enhanced by GITRL in activated CD4⁺T cells, and the p38 inhibitor restrained the GITRL-induced Th17 cell expansion in a dose-dependent manner. Moreover, there was decreased STAT3 activity on Tyr705 and Ser727 with the p38 inhibitor in vitro. Notably, the p38 inhibitor could prevent GITRL-treated arthritis progression and markedly decrease the Th17 cell percentages. The phosphorylation of the Tyr705 site was significantly lower in the GITRL-treated CIA mice administrated with the p38 inhibitor. A significantly higher phosphorylation of p38 was detected in RA patients and had a positive relationship with the serum level of anti-cyclic citrullinated peptide (anti-CCP) antibody. Our findings have indicated that GITRL could promote Th17 cell differentiation by p38 MAPK and STAT3 signaling in autoimmune arthritis.

Bendamustine increases interleukin-10 secretion from B cells via p38 MAP kinase activation

We investigated the effects of bendamustine on B cell functions and explored potential clinical applications of the drugs to autoimmune diseases. Proliferation of Ramos cells, a human B cell line, was significantly inhibited by 25-100μM of bendamustine in a dose-dependent manner. Concordantly, IgM secretion from Ramos cells was significantly inhibited at these concentrations by up to 70%. Interestingly, however, the production and secretion of interleukin-10 (IL-10) were dramatically (at least >10-fold) increased by bendamustine at growth inhibitory concentrations. Exploration of the molecular mechanism of IL-10 production revealed that bendamustine enhanced the phosphorylation of p38 MAP kinase. Further, Sp1 was identified as a downstream transcription factor, and the inhibition of p38 MAP kinase and Sp1 with their inhibitors led to the abrogation of bendamustine-induced IL-10 production and the DNA binding of Sp1. Importantly, when PBMC from healthy donors were cultured with bendamustine at the concentration of 30μM, under the stimulation with an anti-IgM antibody, an anti-CD40 antibody, recombinant human IL-21 (rhIL-21) and recombinant human soluble BAFF (rhsBAFF), IL-10 production by B cells (CD20+CD4-CD8-CD14-) among peripheral blood mononuclear cell (PBMC) was significantly enhanced by adding bendamustine. These results collectively suggest that the p38 MAP kinase-Sp1 pathway plays a crucial role in bendamustine-induced IL-10 production by B cells. Our findings suggest a novel therapeutic possibility for autoimmune diseases through the upregulation of IL-10 which has an anti-inflammatory effects.

Role of interleukin-10 (IL-10) in regulation of GABAergic transmission and acute response to ethanol

Mounting evidence indicates that ethanol (EtOH) exposure activates neuroimmune signaling. Alterations in pro-inflammatory cytokines after acute and chronic EtOH exposure have been heavily investigated. In contrast, little is known about the regulation of neurotransmission and/or modulation by anti-inflammatory cytokines in the brain after an acute EtOH exposure. Recent evidence suggests that interleukin-10 (IL-10), an anti-inflammatory cytokine, is upregulated during withdrawal from chronic EtOH exposure. In the present study, we show that IL-10 is increased early (1 h) after a single intoxicating dose of EtOH (5 g/kg, intragastric) in Sprague Dawley rats. We also show that IL-10 rapidly regulates GABAergic transmission in dentate gyrus neurons. In brain slice recordings, IL-10 application dose-dependently decreases miniature inhibitory postsynaptic current (mIPSC) area and frequency, and decreases the magnitude of the picrotoxin sensitive tonic current (Itonic), indicating both pre- and postsynaptic mechanisms. A PI3K inhibitor LY294002 (but not the negative control LY303511) ablated the inhibitory effects of IL-10 on mIPSC area and Itonic, but not on mIPSC frequency, indicating the involvement of PI3K in postsynaptic effects of IL-10 on GABAergic transmission. Lastly, we also identify a novel neurobehavioral regulation of EtOH sensitivity by IL-10, whereby IL-10 attenuates acute EtOH-induced hypnosis. These results suggest that EtOH causes an early release of IL-10 in the brain, which may contribute to neuronal hyperexcitability as well as disturbed sleep seen after binge exposure to EtOH. These results also identify IL-10 signaling as a potential therapeutic target in alcohol-use disorders and other CNS disorders where GABAergic transmission is altered.

ΔPK oncolytic activity includes modulation of the tumour cell milieu

Oncolytic virotherapy is a unique cancer therapeutic that encompasses tumour cell lysis through both virus replication and programmed cell death (PCD) pathways. Nonetheless, clinical efficacy is relatively modest, likely related to the immunosuppressive tumour milieu. Our studies use the herpes simplex virus type 2 (HSV-2)-based oncolytic virus ΔPK that has documented anti-tumour activity associated with virus replication, PCD and cancer stem cell lysis. They are designed to examine whether ΔPK-mediated oncolysis includes the ability to reverse the immunosuppressive tumour microenvironment by altering the balance of cytokines directly secreted by the melanoma cells and to define its mechanism. Here, we show that melanoma cells secreted the immunosuppressive cytokine IL-10, and that secretion was inhibited by ΔPK through virus replication and c-Jun N-terminal kinase/c-Jun activation. ΔPK-induced IL-10 inhibition upregulated surface expression of MHC class I chain-related protein A, the ligand for the activating NKG2D receptor expressed on NK- and cytotoxic T-cells. Concomitantly, ΔPK also upregulated the secretion of inflammatory cytokines TNF-α, granulocyte macrophage colony-stimulating factor and IL-1β through autophagy-mediated activation of Toll-like receptor 2 pathways and pyroptosis, and it inhibited the expression of the negative immune checkpoint regulator cytotoxic T-lymphocyte antigen 4. Pharmacologic inhibition of these processes significantly reduces the oncolytic activity of ΔPK.

Micro-RNA-155 deficiency prevents alcohol-induced serum endotoxin increase and small bowel inflammation in mice

BACKGROUND

Chronic alcohol impairs gut barrier function and induces inflammatory cytokines. The effects of acute alcohol binge on the gut are partially understood. Micro-RNA-155 (miR-155), a modulator of cytokine and T-cell immune response in the gut, stabilizes tumor necrosis factor-α (TNFα) mRNA. Here, we investigated the role of the inflammation modulator miR-155 as well as the effects of acute binge and chronic alcohol feeding in the small bowel (SB) in mice.

METHODS

For the acute alcohol binge, wild-type (WT) mice received 5 g/kg 50% alcohol/d or equal amount of water oral gavage for 3 days. WT and miR-155-deficient (miR-155-knockout [KO]) mice received ethanol containing Lieber-DeCarli or isocaloric control diet for 5 weeks. MiR-155, antimicrobial peptide, regenerating islet-derived 3-beta (Reg3b), inflammation markers, Src homology 2-containing inositol phosphatase-1 (SHIP1), TNFα, and nuclear factor-κB (NF-κB) were measured in proximal intestinal tissue. Endotoxin was measured in the serum.

RESULTS

Acute alcohol binge enhanced, whereas chronic alcohol feeding decreased, Reg3b mRNA and protein levels in the SB. Both acute binge and chronic alcohol feeding increased serum endotoxin levels, intestinal NF-κB activation and TNFα mRNA levels. However, TNFα protein and miR-155 were increased only after chronic alcohol feeding in the SB. Furthermore, miR-155-KO mice were protected from chronic alcohol-induced increase in serum endotoxin, intestinal TNFα, and NF-κB activation. Also, alcohol-fed miR-155-KO mice had no decrease of Reg3b and SHIP1 levels.

CONCLUSIONS

These results demonstrate that both acute binge and chronic ethanol administration result in increased serum-endotoxin levels. Our study identifies a novel role for miR-155 in chronic alcohol-induced intestinal inflammation and barrier dysfunction.

Interleukin-6 mediated upregulation of CYP1B1 and CYP2E1 in colorectal cancer involves DNA methylation, miR27b and STAT3

Background:

The pro-inflammatory cytokine interleukin-6 (IL6) promotes colorectal cancer (CRC) development. It is also known to regulate cytochrome P450 (CYP450) enzymes, which are involved in CRC tumour initiation and promotion via activation of chemical carcinogens. Here, IL6 regulation of CYP450 expression was investigated in CRC.

Methods:

The effect of IL6 on CYP 1A1, 1B1 and 2E1 expression was determined in vitro using CRC cell lines HCT116 and SW480, and CYP450 expression was determined by immunohistochemistry in CRC tissues previously shown to have increased levels of IL6.

Results:

In mechanistic studies, IL6 treatment significantly induced CYP1B1 and CYP2E1, but not CYP1A1, gene expression in HCT116 and SW480 cells. CYP2E1 expression regulation occurred via a transcriptional mechanism involving STAT3. For CYP1B1 regulation, IL6 downregulated the CYP1B1-targeting microRNA miR27b through a mechanism involving DNA methylation. In clinical samples, the expression of CYP1B1 and CYP2E1, but not CYP1A1, was significantly increased in malignant tissue overexpressing IL6 compared with matched adjacent normal tissue.

Conclusions:

Colonic inflammation with the presence of IL6 associated with neoplastic tissue can alter metabolic competency of epithelial cells by manipulating CYP2E1 and CYP1B1 expression through transcriptional and epigenetic mechanisms. This can lead to increased activation of dietary carcinogens and DNA damage, thus promoting colorectal carcinogenesis.

Moderate alcohol induces stress proteins HSF1 and hsp70 and inhibits proinflammatory cytokines resulting in endotoxin tolerance

Binge or moderate alcohol exposure impairs host defense and increases susceptibility to infection because of compromised innate immune responses. However, there is a lack of consensus on the molecular mechanism by which alcohol mediates this immunosuppression. In this study, we show that cellular stress proteins HSF1 and hsp70 play a mechanistic role in alcohol-mediated inhibition of the TLR4/MyD88 pathway. Alcohol exposure induced transcription factor HSF1 mRNA expression and DNA binding activity in primary human monocytes and murine macrophages. Furthermore, HSF1 target gene hsp70 mRNA and protein are upregulated by alcohol in monocytes. In vitro pre-exposure to moderate alcohol reduced subsequent LPS-induced NF-κB promoter activity and downstream TNF-α, IL-6 and IL-1β production in monocytes and macrophages, exhibiting endotoxin tolerance. Mechanistic analysis demonstrates that alcohol-induced HSF1 binds to the TNF-α promoter in macrophages at early time points, exerting transrepression and decreased TNF-α expression. Furthermore, association of hsp70 with NF-κB subunit p50 in alcohol-treated macrophages correlates with reduced NF-κB activation at later time points. Hsp70 overexpression in macrophages was sufficient to block LPS-induced NF-κB promoter activity, suggesting alcohol-mediated immunosuppression by hsp70. The direct crosstalk of hsp70 and HSF1 was further confirmed by the loss of alcohol-mediated endotoxin tolerance in hsp70- and HSF1-silenced macrophages. Our data suggest that alcohol-mediated activation of HSF1 and induction of hsp70 inhibit TLR4-MyD88 signaling and are required for alcohol-induced endotoxin tolerance. Using stress proteins as direct drug targets would be clinically relevant in alcohol abuse treatment and may serve to provide a better understanding of alcohol-mediated immunosuppression.

Acute alcohol intoxication impairs methicillin-resistant Staphylococcus aureus clearance in the lung by impeding epithelial production of Reg3γ

The incidence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in previously healthy individuals has increased in the past 5 years. Such infections are associated with bronchiectasis and high mortality rates, making them a significant public health concern. The mechanisms of host defense against this pathogen are not well characterized. However, patients diagnosed with MRSA, as opposed to methicillin-susceptible S. aureus (MSSA), are more likely to have abused alcohol in the past, and these patients are more likely to die from sepsis. In the United States, USA300 is the predominant strain that causes necrotizing pneumonia. To investigate whether acute ethanol exacerbates MRSA pneumonia, mice were intraperitoneally (i.p.) administered 2 or 4 g/kg of ethanol 30 min prior to oropharyngeal inoculation of 2 × 10(7) CFU of USA300. An increased pulmonary bacterial burden was observed in alcohol-intoxicated mice at 16 and 24 h and was associated with decreased levels of interleukin 6 (IL-6). IL-6 activates signal transducer and activator of transcription 3 (STAT3) as part of an acute-phase response of infection. Reg3γ is an antimicrobial C-type lectin that is induced by STAT3 signaling in response to Gram-positive bacteria. Previously, in situ hybridization studies showed that Reg3g is highly expressed in lung epithelium. In the present study, we found that acute ethanol exacerbated USA300 in a murine model of USA300 pneumonia. This was associated with reduced IL-6 expression in vivo as well as inhibition of IL-6 induction of STAT3 signaling and Reg3g expression in mouse lung epithelial (MLE12) cells in vitro. Furthermore, recombinant Reg3γ administration 4 h after MRSA infection in alcohol-intoxicated mice rescued USA300 clearance in vivo. Therefore, acute alcohol intoxication leads to decreased MRSA clearance in part by inhibiting IL-6/STAT3 induction of the antimicrobial protein Reg3γ in the pulmonary epithelium.

Ethanol induces cell cycle arrest and triggers apoptosis via Sp1-dependent p75NTR expression in human neuroblastoma cells

Ethanol exposure has deleterious effects on the central nervous system. Although several mechanisms for ethanol-induced damage have been suggested, the precise mechanism underlying ethanol-induced neuronal cell death remains unclear. Recent studies indicate that the p75 neurotrophin receptor (p75NTR) has a critical role in the regulation of neuronal survival. This study was designed to examine the role of p75NTR in ethanol-induced apoptotic signaling in neuroblastoma cells. Ethanol caused highly increased level of p75NTR expression. The use of small interfering RNA to inhibit p75NTR expression markedly attenuated ethanol-induced cell cycle arrest and apoptosis. DNA binding activity of Sp1 was increased by ethanol, whereas inhibition of Sp1 activity by mithramycin, a Sp1 inhibitor, or short hairpin RNA suppressed ethanol-induced p75NTR expression. In addition, inhibitors of casein kinase 2 (CK2) and extracellular signal-regulated kinase (ERK) augmented ethanol-induced p75NTR expression. Our results also demonstrate that inhibition of ERK and CK2 caused a further increase in the activation of the p75NTR proximal promoter induced by ethanol. This increased activation was partially suppressed by the deletion of the Sp1 binding sites. These results suggest that Sp1-mediated p75NTR expression is regulated at least in part by ERK and CK2 pathways. The present study also showed that treatment with ethanol resulted in significant increases in the expression of p21, but not the levels of p53 and p53 target genes such as Bax, Puma, and Bcl-2. Furthermore, the inhibition of p75NTR expression or Sp1 activity suppressed ethanol-induced p21 expression, cell cycle arrest, and apoptosis. These data suggest that ethanol increases p75NTR expression, and CK2 and ERK signaling inversely regulate Sp1-mediated p75NTR expression in ethanol-treated neuroblastoma cells. Thus, our study provides more insight into the mechanisms underlying ethanol actions.

Microarray characterization of gene expression changes in blood during acute ethanol exposure

Background

As part of the civil aviation safety program to define the adverse effects of ethanol on flying performance, we performed a DNA microarray analysis of human whole blood samples from a five-time point study of subjects administered ethanol orally, followed by breathalyzer analysis, to monitor blood alcohol concentration (BAC) to discover significant gene expression changes in response to the ethanol exposure.

Methods

Subjects were administered either orange juice or orange juice with ethanol. Blood samples were taken based on BAC and total RNA was isolated from PaxGene™ blood tubes. The amplified cDNA was used in microarray and quantitative real-time polymerase chain reaction (RT-qPCR) analyses to evaluate differential gene expression. Microarray data was analyzed in a pipeline fashion to summarize and normalize and the results evaluated for relative expression across time points with multiple methods. Candidate genes showing distinctive expression patterns in response to ethanol were clustered by pattern and further analyzed for related function, pathway membership and common transcription factor binding within and across clusters. RT-qPCR was used with representative genes to confirm relative transcript levels across time to those detected in microarrays.

Results

Microarray analysis of samples representing 0%, 0.04%, 0.08%, return to 0.04%, and 0.02% wt/vol BAC showed that changes in gene expression could be detected across the time course. The expression changes were verified by qRT-PCR.

The candidate genes of interest (GOI) identified from the microarray analysis and clustered by expression pattern across the five BAC points showed seven coordinately expressed groups. Analysis showed function-based networks, shared transcription factor binding sites and signaling pathways for members of the clusters. These include hematological functions, innate immunity and inflammation functions, metabolic functions expected of ethanol metabolism, and pancreatic and hepatic function. Five of the seven clusters showed links to the p38 MAPK pathway.

Conclusions

The results of this study provide a first look at changing gene expression patterns in human blood during an acute rise in blood ethanol concentration and its depletion because of metabolism and excretion, and demonstrate that it is possible to detect changes in gene expression using total RNA isolated from whole blood. The analysis approach for this study serves as a workflow to investigate the biology linked to expression changes across a time course and from these changes, to identify target genes that could serve as biomarkers linked to pilot performance.

A novel transcription mechanism activated by ethanol: induction of Slc7a11 gene expression via inhibition of the DNA-binding activity of transcriptional repressor octamer-binding transcription factor 1 (OCT-1)

Solute carrier family 7, member 11 (Slc7a11) is a plasma membrane cystine/glutamate exchanger that provides intracellular cystine to produce glutathione, a major cellular antioxidant. Oxidative and endoplasmic reticulum stresses up-regulate Slc7a11 expression by activation of nuclear factor erythroid 2-related factor 2 and transcription factor 4. This study examined the effect of ethanol on Slc7a11 expression and the underlying mechanism involved. Treatment of mouse hepatic stellate cells with ethanol significantly increased Slc7a11 mRNA and protein levels. Deletion of a 20-bp DNA sequence between -2044 to -2024 upstream of the transcription start site significantly increased basal activity and completely abolished the ethanol-induced activity of the Slc7a11 promoter. This deletion did not affect Slc7a11 promoter activity induced by oxidative or endoplasmic reticulum stress. DNA sequence analysis revealed a binding motif for octamer-binding transcription factor 1 (OCT-1) in the deleted fragment. Mutation of this OCT-1 binding motif resulted in a similar effect as the deletion experiment, i.e. it increased the basal promoter activity and abolished the response to ethanol. Ethanol exposure significantly inhibited OCT-1 binding to the Slc7a11 promoter region, although it did not alter OCT-1 mRNA and protein levels. OCT-1 reportedly functions as either a transcriptional enhancer or repressor, depending on the target genes. Results from this study suggest that OCT-1 functions as a repressor on the Slc7a11 promoter and that ethanol inhibits OCT-1 binding to the Slc7a11 promoter, thereby increasing Slc7a11 expression. Taken together, inhibition of the DNA binding activity of transcriptional repressor OCT-1 is a mechanism by which ethanol up-regulates Slc711 expression.

Induction of Bcl-3 by acute binge alcohol results in toll-like receptor 4/LPS tolerance

Acute alcohol binge results in immunosuppression and impaired production of proinflammatory cytokines, including TNF-α. TNF-α production is induced by LPS, a TLR4 ligand, and is tightly regulated at various levels of the signaling cascade, including the NF-κB transcription factor. Here, we hypothesized that acute alcohol induces TLR4/LPS tolerance via Bcl-3, a nuclear protein and member of the NF-κB family. We found that acute alcohol pretreatment resulted in the same attenuating effect as LPS pretreatment on TLR4-induced TNF-α production in human monocytes and murine RAW 264.7 macrophages. Acute alcohol-induced Bcl-3 expression and IP studies revealed increased association of Bcl-3 with NF-κB p50 homodimers in alcohol-treated macrophages and in mice. ChIP assays revealed increased occupancy of Bcl-3 and p50 at the promoter region of TNF-α in alcohol-pretreated cells. To confirm that the Bcl-3-p50 complex regulates transcription/production of TNF-α during acute alcohol exposure, we inhibited Bcl-3 expression using a targeted siRNA. Bcl-3 knockdown prevented the alcohol-induced inhibition of TNF-α mRNA and protein production. In a mouse model of binge alcohol, an increase in Bcl-3 and a concomitant decrease in TNF-α but no change in IL-10 production were found in mice that received alcohol followed by LPS challenge. In summary, our novel data suggest that acute alcohol treatment in vitro and in vivo induces molecular signatures of TLR4/LPS tolerance through the induction of Bcl-3, a negative regulator of TNF-α transcription via its association with NF-κB p50/p50 dimers.

Intermittent hypoxia conditioning protects mitochondrial cytochrome c oxidase of rat cerebellum from ethanol withdrawal stress

Intermittent hypoxia (IH) conditioning minimizes neurocognitive impairment and stabilizes brain mitochondrial integrity during ethanol withdrawal (EW) in rats, but the mitoprotective mechanism is unclear. We investigated whether IH conditioning protects a key mitochondrial enzyme, cytochrome c oxidase (COX), from EW stress by inhibiting mitochondrially directed apoptotic pathways involving cytochrome c, Bax, or phosphor-P38 (pP38). Male rats completed two cycles of a 4-wk ethanol diet (6.5%) and 3 wk of EW. An IH program consisting of 5-10 bouts of 5-8 min of mild hypoxia (9.5-10% inspired O(2)) and 4 min of reoxygenation for 20 consecutive days began 3 days before the first EW period. For some animals, vitamin E replaced IH conditioning to test the contributions of antioxidant mechanisms to IH's mitoprotection. During the second EW, cerebellar-related motor function was evaluated by measuring latency of fall from a rotating rod (Rotarod test). After the second EW, COX activity in cerebellar mitochondria was measured by spectrophotometry, and COX, cytochrome c, Bax, and pP38 content were analyzed by immunoblot. Mitochondrial protein oxidation was detected by measuring carbonyl contents and by immunochemistry. Earlier IH conditioning prevented motor impairment, COX inactivation, depletion of COX subunit 4, protein carbonylation, and P38 phosphorylation during EW. IH did not prevent cytochrome c depletion during EW, and Bax content was unaffected by EW ± IH. Vitamin E treatment recapitulated IH protection of COX, and P38 inhibition attenuated protein oxidation during EW. Thus IH protects COX and improves cerebellar function during EW by limiting P38-dependent oxidative damage.

Oxidative stress, endogenous antioxidants, alcohol, and hepatitis C: pathogenic interactions and therapeutic considerations

Hepatitis C virus (HCV) is a blood-borne pathogen that was identified as an etiologic agent of non-A, non-B hepatitis in 1989. HCV is estimated to have infected at least 170 million people worldwide. The majority of patients infected with HCV do not clear the virus and become chronically infected, and chronic HCV infection increases the risk for hepatic steatosis, cirrhosis, and hepatocellular carcinoma. HCV induces oxidative/nitrosative stress from multiple sources, including inducible nitric oxide synthase, the mitochondrial electron transport chain, hepatocyte NAD(P)H oxidases, and inflammation, while decreasing glutathione. The cumulative oxidative burden is likely to promote both hepatic and extrahepatic conditions precipitated by HCV through a combination of local and more distal effects of reactive species, and clinical, animal, and in vitro studies strongly point to a role of oxidative/nitrosative stress in HCV-induced pathogenesis. Oxidative stress and hepatopathogenesis induced by HCV are exacerbated by even low doses of alcohol. Alcohol and reactive species may have other effects on hepatitis C patients such as modulation of the host immune system, viral replication, and positive selection of HCV sequence variants that contribute to antiviral resistance. This review summarizes the current understanding of redox interactions of HCV, outlining key experimental findings, directions for future research, and potential applications to therapy.

The Toll-like receptor 1/2 agonists Pam(3) CSK(4) and human β-defensin-3 differentially induce interleukin-10 and nuclear factor-κB signalling patterns in human monocytes

Human β-defensin 3 (hBD-3) activates antigen-presenting cells through Toll-like receptors (TLRs) 1/2. Several TLR1/2 agonists have been identified but little is known about how they might differentially affect cellular activation. We compared the effects of hBD-3 with those of another TLR1/2 agonist, Pam(3) CSK(4) , in human monocytes. Monocytes incubated with hBD-3 or Pam(3) CSK(4) produced interleukin-6 (IL-6), IL-8 and IL-1β, but only Pam(3) CSK(4) induced IL-10. The IL-10 induction by Pam(3) CSK(4) caused down-modulation of the co-stimulatory molecule, CD86, whereas CD86 expression was increased in monocytes exposed to hBD-3. Assessment of signalling pathways linked to IL-10 induction indicated that mitogen-activated protein kinases were activated similarly by hBD-3 or Pam(3) CSK(4) , whereas the non-canonical nuclear factor-κB pathway was only induced by Pam(3) CSK(4) . Our data suggest that the lack of non-canonical nuclear factor-κB signalling by hBD-3 could contribute to the failure of this TLR agonist to induce production of the anti-inflammatory cytokine, IL-10, in human monocytes.

Inhibition of TLR8- and TLR4-induced Type I IFN induction by alcohol is different from its effects on inflammatory cytokine production in monocytes

BACKGROUND

Prolonged alcohol consumption is a significant co-factor in the progression of chronic viral infections including hepatitis C and HIV, which are both single-stranded RNA viruses. Toll like receptor 8 (TLR8), a pattern recognition receptor expressed in monocytes, senses viral single stranded RNA as a danger signal and leads to the induction of Type I interferon (IFN) as well as the pro-inflammatory cytokine, tumor necrosis factor alpha (TNF alpha). Lipopolysaccharide (LPS), a Toll like receptor 4 (TLR4) ligand, was shown to affect inflammatory cell activation after alcohol consumption and in HIV and HCV infections. Here we hypothesized that alcohol exposure modulates TLR8- and TLR4-ligand-induced monocyte activation and affects both type I IFN and inflammatory cytokine induction.

RESULTS

The TLR8 ligand, CL075, as well as the TLR4 ligand, LPS, resulted in a significant induction of TNF alpha both at the mRNA and protein levels in human monocytes. We found that both acute and prolonged alcohol treatment resulted in inhibition of type I IFN induction by either TLR8 or TLR4 ligands in human monocytes at the protein and mRNA levels. In contrast to Type I IFN production, the effects of acute and prolonged alcohol were different on inflammatory cytokine activation after TLR8 or TLR4 ligand stimulation. Acute alcohol inhibited TLR8- or TLR4-induced TNF alpha protein and mRNA induction while it augmented IL-10 production in monocytes. In contrast, prolonged alcohol treatment augmented TNF alpha without affecting IL-10 production significantly in response to either TLR8 or TLR4 ligand stimulation.

CONCLUSIONS

These novel results suggest first, that alcohol has a profound inhibitory effect on Type I IFN induction regardless of intracellular (TLR8) or cell surface-derived (TLR4) danger signals. Second, both acute and prolonged alcohol exposure can inhibit antiviral Type I IFN pathway activation. Third, the opposite effects of acute (inhibitory) and prolonged alcohol (augmentation) treatment on pro-inflammatory cytokine activation extend to TLR8-induced signals beyond the previously shown TLR4/LPS pathway.

Chronic non-bacterial osteomyelitis is associated with impaired Sp1 signaling, reduced IL10 promoter phosphorylation, and reduced myeloid IL-10 expression

Chronic non-bacterial osteomyelitis (CNO) is an auto-inflammatory disorder that affects the skeletal system. Interleukin (IL-)10 is an immune-modulatory cytokine that controls inflammation, and limits inflammatory cytokine responses. Dysregulation of IL-10 expression has been shown to result in autoimmune and infectious diseases. We investigated IL-10 expression by monocytic cells from CNO patients and controls. In response to stimulation with LPS, IL-10 expression from CNO monocytes was reduced (p<0.001). This was independent of IL10 promoter polymorphisms. Thus, we investigated Sp1 recruitment to the IL10 promoter and saw markedly reduced binding in CNO monocytes. This was accompanied with reduced phosphorylation of histone H3 serine 10 (H3S10), an activating epigenetic mark. Impaired recruitment of Sp1 to the IL10 promoter, and reduced H3S10 phosphorylation, may be a reflection of deficient MAPK signaling in CNO monocytes in response to LPS stimulation. Thus, we have discovered a mechanism that may be central in the pathophysiology of CNO.

Hck is a key regulator of gene expression in alternatively activated human monocytes

IL-13 is a Th2 cytokine that promotes alternative activation (M2 polarization) in primary human monocytes. Our studies have characterized the functional IL-13 receptor complex and the downstream signaling events in response to IL-13 stimulation in alternatively activated monocytes/macrophages. In this report, we present evidence that IL-13 induces the activation of a Src family tyrosine kinase, which is required for IL-13 induction of M2 gene expression, including 15-lipoxygenase (15-LO). Our data show that Src kinase activity regulates IL-13-induced p38 MAPK tyrosine phosphorylation via the upstream kinases MKK3 or MKK6. Our findings also reveal that the IL-13 receptor-associated tyrosine kinase Jak2 is required for the activation of both Src kinase as well as p38 MAPK. Further, we found that Src tyrosine kinase-mediated activation of p38 MAPK is required for Stat1 and Stat3 serine 727 phosphorylation in alternatively activated monocytes/macrophages. Additional studies identify Hck as the specific Src family member, stimulated by IL-13 and involved in regulating both p38 MAPK activation and p38 MAPK-mediated 15-LO expression. Finally we show that the Hck regulates the expression of other alternative state (M2)-specific genes (Mannose receptor, MAO-A, and CD36) and therefore conclude that Hck acts as a key regulator controlling gene expression in alternatively activated monocytes/macrophages.

Pathogenesis of alcohol-induced liver disease: classical concepts and recent advances

Alcoholic liver disease (ALD) is a primary consequence of heavy and prolonged drinking. ALD contributes to the bulk of liver disease burden worldwide. Progression of ALD is a multifactorial and multistep process that includes many genetic and environmental risk factors. The molecular pathogenesis of ALD involves alcohol metabolism and secondary mechanisms such as oxidative stress, endotoxin, cytokines and immune regulators. The histopathological manifestation of ALD occurs as an outcome of complex but controlled interactions between hepatic cell types. Hepatic stellate cells (HSCs) are the key drivers of fibrogenesis, but transformation of hepatocytes to myofibroblastoids also implicate parenchymal cells as playing an active role in hepatic fibrogenesis. Recent discoveries indicate that lipogenesis during the early stages of ALD is a risk for advancement to cirrhosis. Other recently identified novel molecules and physiological/cell signaling pathways include fibrinolysis, osteopontin, transforming growth factor-β-SMAD and hedgehog signaling, and involvement of novel cytokines in hepatic fibrogenesis. The observation that ALD and non-alcoholic steatohepatitis share common pathways and genetic polymorphisms suggests operation of parallel pathogenic mechanisms. Future research involving genomics, epigenomics, deep sequencing and non-coding regulatory elements holds promise to identify novel diagnostic and therapeutic targets for ALD. There is also a need for adequate animal models to study pathogenic mechanisms at the molecular level and targeted therapy.

Ethanol inhibits antigen presentation by dendritic cells

Previous studies suggest that altered virus-specific T-cell responses observed during chronic ethanol exposure may be due to abnormal functioning of dendritic cells (DCs). Here we explored the effects of ethanol on exogenous antigen presentation by DCs. BALB/c, C57BL/6, and CBA/caj mice were fed ethanol or an isocaloric control diet for 8 weeks. The splenic DC population was expanded using an Flt3L expression plasmid via tail vein injection. DCs were purified and assessed for antigen presentation and processing and for peptide-major histocompatibility complex class I and II (MHCI and MHCII) formation on the cell surface. Interleukin-2 (IL-2) was measured as an indicator of antigen-specific T-cell activation by DCs in coculture. Antigen processing and peptide-MHCII complexes were evaluated by flow cytometry. We observed that ethanol not only suppressed allogeneic peptide presentation to T cells by DCs but also altered presentation of exogenous ovalbumin (OVA) peptide 323-339 to an OVA-specific DO11 T-cell line as well as to OVA-sensitized primary T cells. Smaller amounts of peptide-MHCII complexes were found on the DCs isolated from the spleens of ethanol-fed mice. In contrast to MHCII presentation, cross-presentation of exogenous OVA peptide via MHCI by DCs remained intact. More importantly, ethanol-exposed DCs had reduced B7-DC and enhanced ICOS-L (inhibitory) costimulatory molecule expression. Ethanol inhibits exogenous and allogeneic antigen presentation and affects the formation of peptide-MHCII complexes, as well as altering costimulatory molecule expression on the cell surface. Therefore, DC presentation of peptides in a favorable costimulatory protein environment is required to subsequently activate T cells and appears to be a critical target for the immunosuppressive effects of ethanol.

Pathogenesis of alcoholic hepatitis: Role of inflammatory signaling and oxidative stress

Inflammatory signaling and oxidative stress are two major components in the pathogenesis of alcoholic hepatitis. Alcohol consumption results in translocation of gut bacteria into the portal system along with lipopolysaccharides that interact with toll-like receptors and results in the production of inflammatory and immunogenic mediators such as tumor necrosis factor-alpha (TNF-α) and interferons. Chronic consumption of alcohol causes priming of this process in which there is enhanced production of cytokines, interferon, interleukins, and TNF-α. Oxidative stress, genetic predisposition, and the unfolded protein response are other contributory mechanisms. Novel therapies aimed at these pathways may prevent, decrease, or delay the complications of alcoholic hepatitis.

Exogenous IL-10 down-regulates STAT3 expression in pancreatic and hepatic tissue of rats with acute necrotizing pancreatitis

AIM: To investigate the effect of treatment with exogenous interleukin-10 (IL-10) on the expression of signal transducer and activator of transcription3 (STAT3) in pancreatic and hepatic tissue of rats with acute necrotizing pancreatitis (ANP).

METHODS: Ninety-two male Sprague-Dawley rats were divided randomly into three groups: control group (n = 24), ANP group (n = 36), and IL-10 group (n = 32). ANP was induced in rats by intraperitoneal injection (ip) of L-arginine. The IL-10 group was treated with 10 000 units of recombinant human IL-10 (rhIL-10) by ip at 2, 5, and 8 h after the last L-arginine injection. Rats were killed at 4, 12, 24, and 36 h after the last L-arginine injection. Pancreatic and hepatic histopathological changes were scored, and the expression of STAT3 was detected by immunohistochemical (IHC) staining.

RESULTS: Pancreatic and hepatic histopathological scores at all time points were significantly higher in the ANP group and IL-10 group than in the control group (all P < 0.01 or 0.05). Compared to the ANP group, pancreatic histopathological scores at 12, 24, and 36 h and hepatic histopathological score at 24 h were significantly lower in the IL-10 group (all P < 0.05 or 0.01). The expression levels of STAT3 in pancreatic and hepatic tissue at all time points were significantly lower in the ANP group and IL-10 group than in the control group (all P < 0.01). The expression levels of STAT3 in pancreatic (12 h: 174.61 ± 6.25 vs 146.10 ± 10.51; 24 h: 178.55 ± 10.36 vs 150.63 ± 9.11; 36 h: 193.37 ± 21.54 vs 155.55 ± 11.70, all P < 0.01 or 0.05) and hepatic tissue (24 h: 89.88 ± 18.89 vs 38.85 ± 10.27; 36 h: 48.79 ± 15.38 vs 23.51 ± 5.67, all P < 0.01) were significantly higher in the IL-10 group than in the ANP group.

CONCLUSION: STAT3 may be involved in the early inflammatory response to ANP. Exogenous IL-10 could improve pancreatic and hepatic tissue injury in ANP rats possibly by down-regulating STAT3 expression.

Alcohol suppresses the granulopoietic response to pulmonary Streptococcus pneumoniae infection with enhancement of STAT3 signaling

Enhanced granulopoietic activity is crucial for host defense against bacterial pneumonia. Alcohol impairs this response. The underlying mechanisms remain obscure. G-CSF produced by infected lung tissue plays a key role in stimulating bone marrow granulopoiesis. This study investigated the effects of alcohol on G-CSF signaling in the regulation of marrow myeloid progenitor cell proliferation in mice with Streptococcus pneumoniae pneumonia. Chronic alcohol consumption plus acute alcohol intoxication suppressed the increase in blood granulocyte counts following intrapulmonary challenge with S. pneumoniae. This suppression was associated with a significant decrease in bone marrow granulopoietic progenitor cell proliferation. Alcohol treatment significantly enhanced STAT3 phosphorylation in bone marrow cells of animals challenged with S. pneumoniae. In vitro experiments showed that G-CSF-induced activation of STAT3-p27(Kip1) pathway in murine myeloid progenitor cell line 32D-G-CSFR cells was markedly enhanced by alcohol exposure. Alcohol dose dependently inhibited G-CSF-stimulated 32D-G-CSFR cell proliferation. This impairment of myeloid progenitor cell proliferation was not attenuated by inhibition of alcohol metabolism through either the alcohol dehydrogenase pathway or the cytochrome P450 system. These data suggest that alcohol enhances G-CSF-associated STAT3-p27(Kip1) signaling, which impairs granulopoietic progenitor cell proliferation by inducing cell cycling arrest and facilitating their terminal differentiation during the granulopoietic response to pulmonary infection.

Molecular mechanisms of alcoholic liver disease: innate immunity and cytokines

Alcohol consumption is a predominant etiological factor in the pathogenesis of chronic liver diseases worldwide, causing fatty liver, alcoholic hepatitis, fibrosis/cirrhosis, and hepatocellular carcinoma. In the past few decades, significant progress has been made in our understanding of the molecular mechanisms underlying alcoholic liver injury. Activation of innate immunity components such as Kupffer cells, LPS/TLR4, and complements in response to alcohol exposure plays a key role in the development and progression of alcoholic liver disease (ALD). LPS activation of Kupffer cells also produces IL-6 and IL-10 that may play a protective role in ameliorating ALD. IL-6 activates signal transducer and activator of transcription 3 (STAT3) in hepatocytes and sinusoidal endothelial cells, while IL-10 activates STAT3 in Kupffer cells/macrophages, subsequently protecting against ALD. In addition, alcohol consumption also inhibits some components of innate immunity such as natural killer (NK) cells, a type of cells that play key roles in anti-viral, anti-tumor, and anti-fibrotic defenses in the liver. Ethanol inhibition of NK cells likely contributes significantly to the pathogenesis of ALD. Understanding the roles of innate immunity and cytokines in alcoholic liver injury may provide insight into novel therapeutic targets in the treatment of alcoholic liver disease.

RNA-binding protein AUF1 regulates lipopolysaccharide-induced IL10 expression by activating IkappaB kinase complex in monocytes

Exposure of monocytes and macrophages to endotoxin/lipopolysaccharide (LPS) from Gram-negative bacteria activates the NF-κB signaling pathway. At early times, this leads to their production of proinflammatory cytokines, but subsequently, they produce anti-inflammatory interleukin-10 (IL-10) to quell the immune response. LPS-mediated induction of IL10 gene expression requires the p40 isoform of the RNA-binding protein AUF1. As LPS exerts modest effects upon IL10 mRNA stability, we hypothesized that AUF1 controls the expression of signaling proteins. Indeed, knockdown of AUF1 impairs LPS-mediated p38 mitogen-activated protein kinase (MAPK) and NF-κB signaling, and the expression of an RNA interference-refractory p40(AUF1) cDNA restores both signaling pathways. To define the molecular mechanisms by which p40(AUF1) controls IL10 expression, we focused on the NF-κB pathway in search of AUF1-regulated targets. Here, we show that p40(AUF1) serves to maintain proper levels of the kinase TAK1 (transforming growth factor-β-activated kinase), which phosphorylates the IKKβ subunit within the IκB kinase complex to activate NF-κB-regulated genes. However, p40(AUF1) does not control the TAK1 mRNA levels but instead promotes the translation of the mRNA. Thus, p40(AUF1) regulates a critical node within the NF-κB signaling pathway to permit IL10 induction for the anti-inflammatory arm of an innate immune response.

The inhibition of JNK and p38 MAPKs downregulates IL-10 and differentially affects c-Jun gene expression in human monocytes

Interleukin-10 is the most important anti-inflammatory cytokine that controls the progress of the immune response. The molecular mechanisms driving the IL10 gene regulation are not well understood. To gain insight into this process we studied the IL-10 expression on mRNA and protein levels, together with c-Jun, FOXP3 and RelA transcription factors gene expression in human monocytes. We investigated also, the involvement of JNK and p38 transduction pathways in IL-10, c-Jun, FOXP3 and RelA gene expression. The quantity determination of IL-10 was performed by ELISA. qRT-PCR was performed for the detection of mRNA transcripts. The pharmacological inhibitors SP600125 and SB202190 were used to explore JNK and p38 MAPKs involvement in IL10, c-Jun, FOXP3 and RelA gene expression. The measurement of IL-10 mRNA synthesis, triggered by lipopolysaccharide (LPS) or C3 binding glycoprotein (C3bgp) showed that stimulation with both inducers led to similar high level of IL-10 mRNA synthesis, whereas C3bgp was the stronger inducer of IL-10 production than LPS. JNK and p38 inhibition significantly decreased IL-10 expression in stimulated cells. C3bgp and LPS induced comparatively low expression of FOXP3, RelA and c-Jun mRNA in monocytes. The inhibition of p38 MAPK in stimulated monocytes resulted in significant enhancement of c-Jun mRNA synthesis suggesting the functional relation between p38 MAPK and c-Jun gene expression. We concluded that the IL10 gene transcription did not associate with enhancement of c-Jun, RelA and FOXP3 gene expression and strictly depended on the JNK and p38 MAPKs activation in stimulated human monocytes.

Alcohol withdrawal and brain injuries: beyond classical mechanisms

Unmanaged sudden withdrawal from the excessive consumption of alcohol (ethanol) adversely alters neuronal integrity in vulnerable brain regions such as the cerebellum, hippocampus, or cortex. In addition to well known hyperexcitatory neurotransmissions, ethanol withdrawal (EW) provokes the intense generation of reactive oxygen species (ROS) and the activation of stress-responding protein kinases, which are the focus of this review article. EW also inflicts mitochondrial membranes/membrane potential, perturbs redox balance, and suppresses mitochondrial enzymes, all of which impair a fundamental function of mitochondria. Moreover, EW acts as an age-provoking stressor. The vulnerable age to EW stress is not necessarily the oldest age and varies depending upon the target molecule of EW. A major female sex steroid, 17β-estradiol (E2), interferes with the EW-induced alteration of oxidative signaling pathways and thereby protects neurons, mitochondria, and behaviors. The current review attempts to provide integrated information at the levels of oxidative signaling mechanisms by which EW provokes brain injuries and E2 protects against it.

Pattern of alcohol consumption and its effect on gastrointestinal symptoms in inflammatory bowel disease

Alcohol consumption is a potential trigger for flare in inflammatory bowel disease (IBD) flare because of alcohol's pro-oxidant effects and its deleterious effects on gut barrier function. The association with alcohol consumption and IBD flare is unclear. To test this hypothesis, we evaluated the pattern of alcohol consumption and its self-reported effect on gastrointestinal (GI) symptoms in patients with IBD. We recruited 129 consecutive patients: 52 patients with Crohn's disease, 38 patients with ulcerative colitis, and 39 patients with irritable bowel syndrome (IBS). All the participants completed a validated questionnaire on disease activity (the Crohn's disease activity index or ulcerative colitis clinical activity index, respectively) validated questionnaires to quantify alcohol consumption by National Institute of Alcohol Abuse and Alcoholism criteria, and two structured questionnaires we designed to access patients' perception of the effect of alcohol on their GI symptoms and on overall GI symptom severity. The pattern of current, light, moderate, and heavy alcohol consumption in inactive IBD was similar to the general U.S. population. Specifically, of the 90 inactive IBD patients, 56 (62%) were current drinkers, compared with 61% in the general U.S. population. Of current drinkers, 75% of IBD (N=42) and 43% of IBS (N=9) reported a worsening of GI symptoms with alcohol consumption (P=.01); however, overall GI symptom severity did not differ when compared with quantity of alcohol consumed. Patients with inactive IBD drink alcohol in quantities similar to the general population. Current drinkers with inactive IBD are more likely to report worsening of GI symptoms with alcohol than current drinkers with IBS.

Alcohol-induced interactive phosphorylation of Src and toll-like receptor regulates the secretion of inflammatory mediators by human astrocytes

Secretion of pro-inflammatory molecules by astrocytes after alcohol treatment was shown to be associated with neuroinflammation. We hypothesized that activation of cytosolic phospholipase A2 (cPLA2) and cyclooxygenase (COX-2) by ethanol in astrocytes enhanced the secretion of inflammatory agents via the interactive tyrosine phosphorylation of toll-like receptor 4 (TLR4) and Src kinase. To test this hypothesis, we treated primary human astrocytes with 20 mM ethanol for 48 h at 37°C. Ethanol exposure elevated cytochrome P450-2E1 activity, reactive oxygen species levels, and secretion of prostaglandin E2 (PGE2) in these cells. Secretion of PGE2 was associated with induction of cPLA2 activity and protein content as well as COX-2 protein level in a Src phosphorylation-dependent manner that occurred by enhanced transcription. Immunoprecipitation and Western blot analyses indicated that the interactive tyrosine phosphorylation of TLR4-Src complex at the cell membrane triggered the activation of cPLA2 and COX-2 in the cytoplasm through a Src signaling intermediate. Inhibition of ethanol metabolism, blockage of Src activity, or inactivation of TLR4 prevented the activation of cPLA2 and COX-2 as well as diminished PGE2 production, suggesting that interactive phosphorylation of TLR4-Src regulated the pro-inflammatory response in astrocytes. Experiments with small interfering RNA knockdown of TLR4 in human astrocytes confirmed that silencing expression also abolished the interactive phosphorylation of both TLR4 and Src in the presence of ethanol.

Ethanol withdrawal acts as an age-specific stressor to activate cerebellar p38 kinase

We investigated whether protein kinase p38 plays a role in the brain-aging changes associated with repeated ethanol withdrawal (EW). Ovariectomized young, middle-age and older rats, with or without 17β-estradiol (E2) implantation, received a 90-day ethanol with repeated withdrawal. They were tested for active pP38 expression in cerebellar Purkinje neurons and whole-cerebellar lysates using immunohistochemistry and enzyme-linked immunosorbent assay, respectively. They were also tested for the Rotarod task to determine the behavioral manifestation of cerebellar neuronal stress and for reactive oxygen species (ROS) and mitochondrial protein carbonyls to determine oxidative mechanisms. Middle-age EW rats showed higher levels of pP38-positive Purkinje neurons/cerebellar lysates, which coincided with increased mitochondrial protein oxidation than other diet/age groups. Exacerbated motor deficit due to age-EW combination also began at the middle-age. In comparison, ROS contents peaked in older EW rats. E2 treatment mitigated each of the EW effects to a different extent. Collectively, pP38 may mediate the brain-aging changes associated with pro-oxidant EW at vulnerable ages and in vulnerable neurons in a manner protected by estrogen.