Role of activated CD8+ T cells in the initiation and continuation of hepatic damage

Over-expression of CD8+ T-cell activation is associated with decreased CD4+ cells in patients seeking treatment of Alcohol Use Disorder

INTRODUCTION

Harmful alcohol consumption may have an impact on the adaptive immune system through an imbalance in T cell subpopulations and changes in cell activation. We aimed to analyze profiles of CD4 and CD8T cell activation in patients with alcohol use disorder (AUD).

METHODS

We used a cross-sectional study with patients seeking treatment of the disorder. Blood samples for immunophenotyping were obtained at admission. Profiles of T cell activation were defined: (I) CD38⁺/HLA-DR⁺, (II) CD38⁺/HLA-DR^-, (III) CD38^-/HLA-DR⁺, (IV) CD38^-/HLA-DR^- and compared with healthy controls. We calculated a CD8⁺ T cell activation indicator (AI) that was defined as the quotient of non-activated cells (CD38^-/HLA-DR^-) and activated cells (CD38⁺/HLA-DR⁺).

RESULTS

60 patients were eligible (83%M); median age was 49 years [IQR: 44-54] and alcohol consumption was 145g/day [IQR: 90-205]. Mean±SD of CD38⁺/HLA-DR^- was 50.3±50.6 cells/μL in patients and 33.5±24.5 cells/μL in controls (p=0.03), for the CD38^-/HLA-DR⁺ it was 61±62.2 cells/μL in patients and 21.2±17.3 cells/μL in controls (p<0.001) and for the CD38⁺/HLA-DR⁺ it was 20.2±15.6 cells/μL in patients and 10.8±10.3 cells/μL in controls (p<0.001). In patients, an inverse correlation was observed between absolute number and percentage of CD4⁺ T cells, and the percentage of CD38⁺/HLA-DR⁺CD8⁺ T cells (r=0.37, p=0.003; r=0.2, p=0.086, respectively).

CONCLUSIONS

Patients with AUD have an increased expression of immune activation with respect to healthy individuals. This excess of activated CD8⁺ T cells correlates with the absolute CD4⁺ T cells.

Alterations in Activation, Cytotoxic Capacity and Trafficking Profile of Peripheral CD8 T Cells in Young Adult Binge Drinkers

Background

Excess of alcohol consumption is a public health problem and has documented effects on the immune system of humans and animals. Animal and in vitro studies suggest that alcohol abuse changes CD8 T cell (CD8) characteristics, however it remains unknown if the CD8 profile of binge drinkers is different in terms of activation, trafficking and cytotoxic capacity.

Aim

To analyze the peripheral CD8 cytotoxic capacity, activation and trafficking phenotypic profile of Mexican young adults with regard to alcohol consumption pattern.

Methods

55 Mexican young adults were stratified as Light (20), Intermediate (18) or Binge drinkers (17) according to their reported alcohol consumption pattern. Blood samples were obtained and hematic biometry and liver enzyme analysis were performed. Peripheral CD8 profile was established by expression of Granzyme B (GB), CD137, CD127, CD69, TLR4, PD1, CCR2, CCR4, CCR5 and CXCR4 by FACS. Data was analyzed by ANOVA, posthoc DMS and Tamhane, and principal component analysis (PCA) with varimax rotation, p<0.05.

Results

The Binge drinking group showed increased γGT together with increased expression of CD69 and reduced expression of TLR4, PD1, CCR2 and CXCR4 in peripheral CD8 cells. Other parameters were also specific to Binge drinkers. PCA established 3 factors associated with alcohol consumption: “Early Activation” represented by CD69 and TLR4 expression in the CD8 population; “Effector Activation” by CD69 expression in CD8 CD127⁺CD137⁺ and CD8 CD25⁺ CD137⁺; and Trafficking by CXCR4 expression on total CD8 and CD8 GB⁺CXCR4⁺, and CCR2 expression on total CD8. Binge drinking pattern showed low expression of Early Activation and Trafficking factors while Light drinking pattern exhibited high expression of Effector Activation factor.

Conclusions

Alcohol consumption affects the immune phenotype of CD8 cells since binge drinking pattern was found to be associated with high CD69 and low TLR4, CXCR4 and CCR2 expression, which suggest recent activation, decreased sensitivity to LPS and lower migration capacity in response to chemokines SDF-1 and MCP-1. These results indicate that a binge-drinking pattern of alcohol consumption may induce an altered immune profile that could be related with liver damage and the increased susceptibility to infection reported to this behavior.

Decreased peripheral blood CD4+/CD25+ regulatory T cells in patients with alcoholic hepatitis

BACKGROUND

Development of alcoholic hepatitis (AH) may be favored by the activation of the innate immune response. Recently, decreased numbers of circulating regulatory T cells (Tregs) have been reported in diseases associated with an immune activation status, but no studies have focused so far, in investigating the distribution of Tregs in chronic alcoholism and its potential association with liver disease. Here, we analyzed for the first time the frequency of peripheral blood (PB) Tregs and Treg subsets in AH and its relationship with the production of inflammatory cytokines by PB monocytes and dendritic cells (DCs).

METHODS

PB samples from 25 male patients with AH were studied; in parallel, 15 male chronic alcoholic patients without liver disease (AWLD) and 17 male healthy donors were also studied, as controls. The distribution of CD4⁺CD25hiCD127-/lo Tregs and their maturation subsets (naïve, central memory, and peripheral memory Tregs) was analyzed by flow cytometry. Spontaneous and in vitro-stimulated production of inflammatory cytokines by PB monocytes and DCs was analyzed by flow cytometry at the cytoplasmic level.

RESULTS

Patients with AH showed decreased (p < 0.05) numbers of PB CD4⁺CD25hiCD127-/lo Tregs at the expense of all maturation-associated subsets, while AWLD and healthy subjects showed a similar (p > 0.05) distribution of PB CD4⁺CD25hiCD127-/lo Tregs. Interestingly, significantly increased amounts of spontaneously produced inflammatory cytokines were found among circulating monocyte-derived DCs and monocytes from AH (and AWLD) patients in comparison with healthy donors. Conversely, the ability of these cell subsets to produce cytokines after in vitro stimulation was lower (p < 0.05) in AH versus the 2 control groups.

CONCLUSIONS

PB CD4⁺CD25hiCD127-/lo Tregs are significantly decreased in patients with AH when compared to both healthy and AWLD; this may contribute to explain the more pronounced activation of the innate immune response observed in AH, as reflected by an increased secretion of inflammatory cytokines by PB DCs and monocytes, and could facilitate the development of liver disease.

Peripheral blood dendritic cells in alcoholic and autoimmune liver disorders

Little is known about effects of alcohol consumption on dendritic cell (DC) function and resultant immune response. However, quantitative and qualitative disturbances of DCs are speculated to be involved in alcohol-related as well as in other liver pathology. The present study aimed to evaluate changes in circulating DC subsets in alcoholic liver disease (N = 43), autoimmune hepatitis (N = 26) and primary biliary cirrhosis (N = 20). DCs isolated from the peripheral blood of recruited participants were stained with monoclonal antibodies against blood dendritic cell antigens (BDCAs) and estimated using the flow cytometry. Myeloid DCs were defined as BDCA-1(+)/CD19(-) cells, and lymphoid DCs as BDCA-2(+)/CD123(+) cells. Total numbers of circulating DCs in subjects with some liver diseases were markedly lower than in the healthy participants (p = 0.03). There was a significantly lower percentage of circulating BDCA-2(+)/CD123(+) (p = 0.02), and a tendency for the percentage of circulating BDCA-1(+)/CD19(-) cells to decrease in patients with liver diseases compared to the controls (p = 0.09). These results may suggest that decreased numbers of DCs may be responsible for reduced adaptive immune responses and increased susceptibility to infections and cancer development observed in patients exposed to alcohol. Moreover, numerical abnormalities of DCs may contribute to the breakdown of self-tolerance, a feature of autoimmune diseases.

Chronic alcohol consumption is associated with an increased cytotoxic profile of circulating lymphocytes that may be related with the development of liver injury

BACKGROUND

Apoptosis has recently emerged as a key component of acute and chronic liver diseases and it could be related to alcoholic liver disease. In the present study, we attempted to analyze the cytotoxic profile of circulating lymphocytes in chronic alcoholic patients grouped according to ethanol intake status and presence of liver disease.

METHODS

We investigate the phenotypic and functional behavior of different compartments of peripheral blood (PB) cytotoxic T and natural killer (NK) cells in chronic alcoholic patients without liver disease and active ethanol intake (AWLD group; n = 22), and in subjects with alcohol liver cirrhosis (ALC group; n = 22).

RESULTS

AWLD patients showed an expansion of both CD4+/CD8+ cytotoxic T cells and NK/T cells, in association with an enhanced cytolytic activity against K562 cells and a higher ability to induce in vitro expression of the pro-apoptotic protein APO2.7 in HepG2 cells. Conversely, ethanol intake in ALC patients was associated with decreased NK cell numbers, a reduced cytotoxic activity against K562 cells without significant changes in the expression of APO2.7, and a pro-fibrotic profile of cytokine secretion.

CONCLUSIONS

Overall, our results suggest that alcoholic patients display different phenotypical and functional changes in circulating PB cytotoxic lymphocytes according to the presence of alcoholic liver disease, which could be related to the development and progress of liver injury.

A recent perspective on alcohol, immunity, and host defense

BACKGROUND

Multiple line of clinical and experimental evidence demonstrates that both acute, moderate, and chronic, excessive alcohol use result in various abnormalities in the functions of the immune system.

METHODS

Medline and PubMed databases were used to identify published reports with particular interest in the period of 2000-2008 in the subject of alcohol use, infection, inflammation, innate, and adaptive immunity.

RESULTS

This review article summarizes recent findings relevant to acute or chronic alcohol use-induced immunomodulation and its consequences on host defense against microbial pathogens and tissue injury. Studies with in vivo and in vitro alcohol administration are both discussed. The effects of alcohol on lung infections, trauma and burn injury, liver, pancreas, and cardiovascular diseases are evaluated with respect to the role of immune cells. Specific changes in innate immune response and abnormalities in adaptive immunity caused by alcohol intake are detailed.

CONCLUSION

Altered inflammatory cell and adaptive immune responses after alcohol consumption result in increased incidence and poor outcome of infections and other organ-specific immune-mediated effects.

A new genetic variant involved in genetic susceptibility to alcoholic liver cirrhosis: -330T>G polymorphism of the interleukin-2 gene

OBJECTIVE

Genetic factors may determine susceptibility to develop alcoholic liver cirrhosis, although it remains uncertain why only a minority of alcoholics suffers from this disease. A decrease in serum levels of interleukin-2 (IL-2) is usually found in alcoholic cirrhotics. In this study we examined the relationship between the -330T>G IL-2 gene (IL2) polymorphism and alcoholic liver cirrhosis.

METHODS

Genotyping of the aforementioned polymorphism was done by polymerase chain reaction and digestion with restriction enzymes in 257 male alcoholics (161 without liver disease and 96 with alcoholic liver cirrhosis) and 101 healthy controls. A logistic regression analysis was performed to adjust for potential confounders and to analyze the model of inheritance.

RESULTS

We found an association between the -330T>G IL2 polymorphism and alcoholic liver cirrhosis: the frequency of the allele T carriers (genotype TT and GT) was significantly higher in alcoholics with cirrhosis (96.9%) than in those without liver disease (89.4%, P=0.043).

CONCLUSION

We report for the first time that the possession of the -330T allele of the IL2 is associated with a higher risk of developing alcoholic liver cirrhosis and this fact may favor the progression of alcoholic liver disease.

Production of inflammatory cytokines by peripheral blood monocytes in chronic alcoholism: relationship with ethanol intake and liver disease

BACKGROUND

Controversial results have been reported about the effects of alcoholism on the functionality of monocytes. In the present study we analyze the effects of chronic alcoholism on the intracellular production of inflammatory cytokines by peripheral blood (PB) monocytes.

METHODS

Spontaneous and in vitro-stimulated production of interleukin (IL) 1alpha (TNFalpha) by PB monocytes was analyzed at the single level by flow cytometry in chronic alcoholics without liver disease and active ethanol (EtOH) intake (AWLD group), as well as in patients with alcohol liver cirrhosis (ALC group), who were either actively drinking (ALCET group) or with alcohol withdrawal (ALCAW group).

RESULTS

A significantly increased spontaneous production of IL1beta, IL6, IL12, and TNFalpha was observed on PB monocytes among AWLD individuals. Conversely, circulating monocytes form ALCET patients showed an abnormally low spontaneous and stimulated production of inflammatory cytokines. No significant changes were observed in ALCAW group as regards production of IL1beta, IL6, IL12, and TNFalpha.

CONCLUSION

Our results show an altered pattern of production of inflammatory cytokines in PB monocytes from chronic alcoholic patients, the exact abnormalities observed depending on both the status of EtOH intake and the existence of alcoholic liver disease.

Chronic alcohol consumption is associated with changes in the distribution, immunophenotype, and the inflammatory cytokine secretion profile of circulating dendritic cells

BACKGROUND

Alcoholism is frequently associated with altered immune responses, limited information being available on its effects on dendritic cells (DC). In the present study we analyze the effects of chronic alcoholism on circulating DC.

METHODS

For the first time we studied the numerical distribution of DC in peripheral blood (PB), their immunophenotype, and their ex vivo pattern of spontaneous cytokine secretion, in chronic alcoholic patients without liver disease (AWLD group; n=17) and active ethanol (EtOH) intake, as well as in subjects with alcohol liver cirrhosis (ALC group; n=21).

RESULTS

A significantly decreased HLADR expression and an increased reactivity for CD123 was observed on PB DC from AWLD patients; additionally, increased secretion of interleukin (IL) 1beta, IL6, IL12, and tumor necrosis factor-alpha (TNFalpha) by DC was also noted in this group. Conversely, patients with ALC and at least 1 year of alcohol withdrawal (ALCAW group) showed a decreased number of total circulating DC, whereas ALC patients with active EtOH intake (ALCET group) had an abnormally low production of IL1beta and TNFalpha by PB DC.

CONCLUSION

Chronic alcoholism in the absence of liver disease is associated with an increased secretion of inflammatory cytokines by PB DC, whereas ALCAW and ALCET patients show decreased numbers of circulating DC and reduced secretion of these cytokines, respectively.

Addictive drugs and their relationship with infectious diseases

The use of drugs of abuse, both recreationally and medicinally, may be related to serious public health concerns. There is a relationship between addictive drugs of abuse such as alcohol and nicotine in cigarette smoke, as well as illegal drugs such as opiates, cocaine and marijuana, and increased susceptibility to infections. The nature and mechanisms of immunomodulation induced by such drugs of abuse are described in this review. The effects of opiates and marijuana, using animal models as well as in vitro studies with immune cells from experimental animals and humans, have shown that immunomodulation induced by these drugs is mainly receptor-mediated, either directly by interaction with specific receptors on immune cells or indirectly by reaction with similar receptors on cells of the nervous system. Similar studies also show that cocaine and nicotine have marked immunomodulatory effects, which are mainly receptor-mediated. Both cocaine, an illegal drug, and nicotine, a widely used legal addictive component of cigarettes, are markedly immunomodulatory and increase susceptibility to infection. The nature and mechanism of immunomodulation induced by alcohol, the most widely used addictive substance of abuse, are similar but immunomodulatory effects, although not receptor-mediated. The many research studies on the effects of these drugs on immunity and increased susceptibility to infectious diseases, including AIDS, are providing a better understanding of the complex interactions between immunity, infections and substance abuse.

Immunological aetiology of major psychiatric disorders: evidence and therapeutic implications

Historically, immunological research in psychiatry was based on empirical findings and early epidemiological studies indicating a possible relationship between psychiatric symptoms and acute infectious diseases. However, aetiopathological explanations for psychiatric disorders are no longer closely related to acute infection. Nevertheless, immune hypotheses have been discussed in schizophrenia, affective disorders and infantile autism in the last decades. Although the variability between the results of the epidemiological studies conducted to date is strikingly high, there is still some evidence that the immune system might play a role in the aetiopathogenesis of these three psychiatric diseases, at least in subgroups of patients. In anxiety disorders immunological research is still very much in its infancy, and the few and inconsistent data of immune changes in these patients are believed to reflect the influence of short- or long-term stress exposure. Nevertheless, there are also some hints raising the possibility that autoimmune mechanisms could interrupt neurotransmission, which would be of significance in certain patients with anxiety and panic disorders. Drug and alcohol (ethanol) dependence are not believed to be primarily influenced by an immunological aetiology. On the other hand, immune reactions due to different drugs of abuse and alcohol may directly or indirectly influence the course of concomitant somatic diseases. In different organic brain disorders the underlying somatic disease is defined as a primary immune or autoimmune disorder, for instance HIV infection or systemic lupus erythematosus (SLE). For other neurodegenerative disorders, such as Alzheimer's disease, immunoaetiopathological mechanisms are supported by experimental and clinical studies. Treatment strategies based on immune mechanisms have been investigated in patients with schizophrenia and affective disorders. Furthermore, some antipsychotics and most antidepressants are known to have direct or indirect effects on the immune system. Different immunotherapies have been used in autism, including transfer factor, pentoxifylline, intravenous immunoglobulins and corticosteroids. Immunosuppressive and/or immunomodulating agents are well established methods for treating the neuropsychiatric sequelae of immune or autoimmune disorders, for example AIDS and SLE. Therapeutic approaches in Alzheimer's disease also apply immunological methods such as strategies of active/passive immunisation and NSAIDs. Considering the comprehensive interactive network between mind and body, future research should focus on approaches linking targets of the different involved systems.

[Immune system and alcoholic liver disease]

It is well established that alcoholism is associated with imbalanced immune responses. To date, most relevant finding reported is the existence of an immunodepressed state which leads to a higher risk of suffering from severe infections in alcoholic patients. However, recent studies have shown that ethanol intake is followed by changes involving the synthesis and serum levels of specific cytokines as well as the activation of several different subsets of cytotoxic lymphocytes, that could be involved in the development of alcoholic liver disease. Accordingly, tumor necrosis factor-alpha plays a key role in the development of alcoholic liver damage through the induction of both apoptosis and necrosis of hepatocytes. This cytokine, together with interleukin (IL) 1, IL6 and several chemokines, facilitate the development of inflammation of the liver. Additionally, both transforming growth factor-beta and platelet-derived growth factor, act over stellate cells favouring hepatic fibrogenesis. The advances in the knowledge of the immunological mechanisms involved in alcoholic liver disease may lead to the discovery of new potential therapeutic targets, which may modify disease outcome in the near future.

Alcohol and the liver

PURPOSE OF REVIEW

To highlight salient recent discoveries and results of clinical trials in alcoholic liver disease (ALD). The burden of care for ALD patients is hefty and the prevalence of alcohol abuse may be increasing in both the developed and the underdeveloped world.

RECENT FINDINGS

Molecular mechanisms of alcoholism are being identified but not of the predisposition to alcoholic liver injury, except perhaps for polymorphism of a cytotoxic T-cell antigen. The Mayo End-stage Liver Disease (MELD) score performs well in assessing the prognosis of ALD; serological biomarkers for predicting ALD outcome are of uncertain value. Concomitant liver disease (e.g., obesity, hepatitis C, and iron overload) aggravates the severity of ALD; conversely, alcohol abuse may be a cryptic co-factor in some cases of non-alcoholic fatty liver. For alcoholic hepatitis, nutritional support is the mainstay of treatment; steroids are considered by some (but not all) as safe and effective therapy, whereas manipulations of tumor necrosis factor-alpha activity have been disappointing, or of unproven benefit at best. In liver transplantation for ALD, methods are being devised to monitor recidivism and to ameliorate its risk and that of co-morbid psychiatric conditions.

SUMMARY

Much of the pathogenesis of ALD has been identified and headway has been made in predicting its prognosis. However, much remains to be done to elucidate the molecular genetics of the risk of developing ALD and in formulating safe, effective therapies for alcoholic hepatitis.

Microbial infections, immunomodulation, and drugs of abuse

The use of recreational drugs of abuse has generated serious health concerns. There is a long-recognized relationship between addictive drugs and increased levels of infections. Studies of the mechanisms of actions of these drugs became more urgent with the advent of AIDS and its correlation with abused substances. The nature and mechanisms of immunomodulation by marijuana, opiates, cocaine, nicotine, and alcohol are described in this review. Recent studies of the effects of opiates or marijuana on the immune system have demonstrated that they are receptor mediated, occurring both directly via specific receptors on immune cells and indirectly through similar receptors on cells of the nervous system. Findings are also discussed that demonstrate that cocaine and nicotine have similar immunomodulatory effects, which are also apparently receptor mediated. Finally, the nature and mechanisms of immunomodulation by alcohol are described. Although no specific alcohol receptors have been identified, it is widely recognized that alcohol enhances susceptibility to opportunistic microbes. The review covers recent studies of the effects of these drugs on immunity and on increased susceptibility to infectious diseases, including AIDS.