Dexmedetomidine Restores Autophagic Flux, Modulates Associated microRNAs and the Cholinergic Anti-inflammatory Pathway upon LPS-Treatment in Rats.

Infections and perioperative stress can lead to neuroinflammation, which in turn is linked to cognitive impairments such as postoperative delirium or postoperative cognitive dysfunctions. The α2-adrenoceptor agonist dexmedetomidine (DEX) prevents cognitive impairments and has organo-protective and anti-inflammatory properties. Macroautophagy (autophagy) regulates many biological processes, but its role in DEX-mediated anti-inflammation and the underlying mechanism of DEX remains largely unclear. We were interested how a pretreatment with DEX protects against lipopolysaccharide (LPS)-induced inflammation in adult male Wistar rats. We used Western blot and activity assays to study how DEX modulated autophagy- and apoptosis-associated proteins as well as molecules of the cholinergic anti-inflammatory pathway, and qPCR to analyse the expression of autophagy and inflammation-associated microRNAs (miRNA) in the spleen, cortex and hippocampus at different time points (6 h, 24 h, 7 d). We showed that a DEX pretreatment prevents LPS-induced impairments in autophagic flux and attenuates the LPS-induced increase in the apoptosis-associated protein cleaved poly(ADP-ribose)-polymerase (PARP) in the spleen. Both, DEX and LPS altered miRNA expression and molecules of the cholinergic anti-inflammatory pathway in the spleen and brain. While only a certain set of miRNAs was up- and/or downregulated by LPS in each tissue, which was prevented or attenuated by a DEX pretreatment in the spleen and hippocampus, all miRNAs were up- and/or downregulated by DEX itself - independent of whether or not they were altered by LPS. Our results indicate that the organo-protective effect of DEX may be mediated by autophagy, possibly by acting on associated miRNAs, and the cholinergic anti-inflammatory pathway. Preventive effects of DEX on LPS-induced inflammation. DEX restores the LPS-induced impairments in autophagic flux, attenuates PARP cleavage and alters molecules of the cholinergic system in the spleen. Furthermore, DEX alters and prevents LPS-induced miRNA expression changes in the spleen and brain along with LPS.

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.

Alcohol use disorder and perioperative immune dysfunction.

The anesthesiological sequelae of long-term alcohol abuse include a three to fivefold increased risk of postoperative infection, prolonged intensive care unit stays and longer hospital stays. The cause of the higher infection rates is an altered immune response in long-term alcoholic patients. Preoperatively, the T helper cells 1 to T helper cells 2 ratio is depressed in long-term alcoholic patients and remains suppressed after surgery. The lower preoperative T helper cells 1 to T helper cells 2 ratio is predictive of later onset of infections. Postoperatively, the cytotoxic lymphocyte (Tc1/Tc2) ratio is decreased in long-term alcoholic patients and remains depressed for 5 days. The interleukin (IL)-6/IL-10 ratio and the lipopolysaccharide-stimulated interferon gamma/IL-10 ratio in whole blood cells are decreased after surgery in long-term alcoholic patients. Depressed Tc1/Tc2, IL-6/IL-10 and lipopolysaccharide-stimulated interferon gamma/IL-10 ratios in the postoperative period are predictive of subsequent postoperative infections. Perioperative interventions should aim to minimize dysregulation of the immune system.

Effects of ethanol on cytokine production after surgery in a murine model of gram-negative pneumonia.

BACKGROUND: Both alcohol abuse and surgery have been shown to impair immune function. The frequency of postoperative infectious complications is 2- to 5-fold increased in long-term alcoholic patients, leading to prolonged hospital stay. Following surgery, an increase in interleukin (IL)-6 has been shown to be associated with increased tissue injury and interleukin 1-(IL-10) is known to represent an anti-inflammatory signal. The purpose of this study was to test the hypothesis that several days of excess alcohol consumption results in more pronounced immunosuppression. We assume that alcoholic animals show increased levels of IL-10 in response to infection and increased IL-6 due to a more pronounced lung pathology. METHODS: Thirty-two female Balb/c mice were pretreated with ethanol (EtOH) at a dose of (3.8 mg/g body weight) or saline (NaCl) for 8 days. At day 8 of the experiment all mice underwent a median laparotomy. Two days postsurgery mice were either applicated 10(4) CFU Klebsiella pneumoniae or received sham-infection with saline. A total number of 4 groups (EtOH/K. pneumoniae; NaCl/K. pneumoniae; EtOH/Sham-infection, NaCl/Sham-infection) was investigated and a clinical score evaluated. Twenty-four hours later mice were killed; lung, spleen, and liver were excised for protein isolation and histological assessment. IL-6 and IL-10 levels were detected by ELISA. RESULTS: Alcohol-exposed mice exhibited a worsened clinical appearance. The histological assessment demonstrated a distinct deterioration of the pulmonary structure in alcohol-treated animals. In the lung, IL-6 and IL-10 was significantly increased in alcohol-exposed infected mice compared to saline-treated infected mice. The clinical score correlated significantly with IL-6 (r = 0.71; p < 0.01) and IL-10 levels (r = 0.64; p < 0.01) in the lung. CONCLUSIONS: Ethanol treatment in this surgical model led to a more severe pulmonary infection with K. pneumoniae which was associated with more tissue destruction and increased levels of IL-6 and IL-10 and a worsened clinical score.

Ethanol-Induced Alterations of T Cells and Cytokines after Surgery in a Murine Infection Model.

BACKGROUND: Interactions between alcohol, infection, and surgery and their effect on differentiation and functionality of T helper cells are not yet completely understood. We hypothesized that alcohol and surgery disturb differentiation of T helper cells and contribute to an impaired immune response. METHODS: Mice were treated with alcohol for two weeks. Saline treatment served as control. Clinical performance and weight were assessed. On day 14, a median laparotomy was performed and animals were challenged with Klebsiella pneumoniae intranasally. Bacterial load was determined in lungs and blood. T helper cell subpopulations and the released cytokines were assessed in lungs, spleens, and plasma. Key transcription factors of T cell differentiation were evaluated. RESULTS: Alcohol significantly impaired clinical appearance and body weight of animals with postsurgical infection (p < 0.05). Bacterial load was significantly higher after alcohol treatment (p < 0.05). T helper cell subsets and released cytokine levels were significantly altered in lung, but not in spleen. Expression of transcription factors of T helper cell lineage commitment did not translate into different counts of T helper cells. CONCLUSIONS: Alcohol and surgery lead to significant cellular and functional modulations of T helper cells during postsurgical infection. These effects may contribute to an impaired immune response after surgery.

Differential effects of ethanol on IFN-gamma- and TNF-alpha-producing splenic T lymphocytes in a murine model of gram-negative pneumonia.

The incidence of bacterial pneumonia is increased in alcoholic patients. Alcohol consumption has been shown to impair cytokine production. Tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) are critical for host defense against Klebsiella pneumoniae (K. pneumoniae). In order to examine the influence of alcohol on the immune response to infection, we investigated the frequency of TNF-alpha and IFN-gamma produced by splenic T-lymphocytes in a murine model of gram-negative pneumonia initiated after 8 days of alcohol treatment. Thirty-two Balb/c mice were pretreated with ethanol (3 mg/g body weight) or saline intraperitoneally over 8 days. On day 7 half of each group was administered K. pneumoniae. Mice were sacrificed 24 hours later to excise lungs and liver for histological assessment and spleens for cell isolation. IFN-gamma- and TNF-alpha-producing CD4(+) and CD8(+) lymphocytes were determined by FACS analysis. In mice with Klebsiella infection, the percentages of IFN-gamma-producing CD4(+) (P < 0.01) and CD8(+) (P < 0.01) were significantly decreased, the percentages of TNF-alpha-producing CD4(+) (P = 0.01) and CD8(+) (P < 0.01) T cells were significantly elevated after alcohol treatment compared with mice with saline treatment. The histological assessment showed an aggravation of K. pneumoniae-induced pneumonia in alcohol-treated mice. Alcohol differentially affects IFN-gamma and TNF-alpha production in Klebsiella-infected mice. Both effects obviously led to a weakened immune response as seen by increased histological damage. This suggests a role of T cells in the increased susceptibility of the alcoholic host to nosocomial infection due to inadequate cytokine response.