Ruth A. Coleman

Chronic ethanol consumption by mice results in activated splenic T cells

Previous studies have shown that T cells from human alcoholics overexpress activation or memory markers such as human leukocyte antigen‐DR, CD45RO, CD57, and CD11b and may have reduced levels of CD62L. In those studies, we demonstrated that the increased CD57+ T cell population rapidly produces interferon‐γ (IFN‐γ) and tumor necrosis factor α, independent of a second signal requirement, consistent with an increased effector T cell population. In contrast to the length of alcohol abuse by human alcoholics, most work with mice has involved 2‐week ethanol exposures or less, which result in decreased IFN‐γ responses. In the present work, we have evaluated C57Bl/6 or BALB/c mice, which were administered 20% w/v ethanol in water for 3–13 weeks. In these mice, rapid cytoplasmic IFN‐γ expression by T cells after stimulation through the T cell receptor was significantly increased versus normals. Studies of surface‐activation markers showed that T cells from chronically ethanol‐fed mice had reduced CD62L expression and an increased percentage of CD44hi T cells. The CD44hi subset was largely second signal‐independent for secreted IFN‐γ and interleukin (IL)‐4 production at early times after stimulation. The enriched T cells of chronic ethanol mice secreted more IFN‐γ and IL‐4 than controls and equivalent IL‐2 at early times after stimulation (6–24 h). The overall results support the concept that in humans and mice, chronic alcohol exposure of sufficient duration results in T cell activation or sensitization in vivo and an increased percentage of the effector/memory subset.

Chronic Alcohol Consumption Increases the Severity of Murine Influenza Virus Infections

Respiratory infections with both seasonal as well as potential pandemic Influenza viruses represent a significant burden on human health. Furthermore, viruses such as Influenza are increasingly recognized as important etiologic agents in community acquired pneumonia. Within the U.S. alone, ∼12.9 million people are heavy drinkers and chronic abuse of alcohol is known to increase the risk and severity of community acquired pneumonia. Given the lack of knowledge regarding Influenza disease in this population, we determined the effects of chronic alcohol consumption on Influenza virus infection. Herein, we report that mice exposed to chronic ethanol have sharp increases in morbidity, mortality, and pulmonary virus titers relative to controls. These increases in influenza severity correspond with inhibited pulmonary influenza-specific CD8 T cell responses. Further, chronic ethanol consumption results in an enhanced pulmonary lesion severity, similar to that recently described for pandemic influenzas. Together, our results suggest that chronic alcohol consumption may increase the risk for severe influenza virus infections by altering the pulmonary inflammatory environment and CD8 T cell response.

Fetal exposure to ethanol has long-term effects on the severity of influenza virus infections.

Alcohol use by pregnant women is a significant public health issue despite well-described risks to the fetus including physical and intellectual growth retardation and malformations. Although clinical studies are limited, they suggest that in utero alcohol exposure also results in significant immune deficiencies in naive neonates. However, little is known about fetal alcohol exposure (FAE) effects on adult infections. Therefore, to determine the long-term effects of FAE on disease susceptibility and the adult immune system, we infected FAE adult mice with influenza virus. In this study, we demonstrate that mice exposed to ethanol during gestation and nursing exhibit enhanced disease severity as well as increased and sustained pulmonary viral titers following influenza virus infection. Secondary exposure to alcohol as an adult further exacerbates these effects. Moreover, we demonstrate that FAE mice have impaired adaptive immune responses, including decreased numbers of virus-specific pulmonary CD8 T cells, a decreased size and frequency of pulmonary B cell foci, and reduced production of influenza-specific Ab following influenza infection. Together, our results suggest that FAE induces significant and long-term defects in immunity and susceptibility to influenza virus infection and that FAE individuals could be at increased risk for severe and fatal respiratory infections.

TH1 cytokine response of CD57+ T-cell subsets in healthy controls and patients with alcoholic liver disease

Patients with chronic inflammatory diseases, including Crohns disease and rheumatoid arthritis, as well as those with certain viral infections, and patients who are transplant recipients or who have certain hematologic malignancies have been observed to have CD57+ T cell expansion in both CD4+ and CD8+ subsets. We have reported previously that alcoholic patients also have CD57+ T cell expansion. Because many alcoholics become seriously deficient in cell-mediated immunity, it is of interest to determine whether the expanded CD57+ subsets can respond to stimulation with normal T helper cell subtype 1 (TH1) cytokine production. We report evaluation of the CD57 T-cell subsets of patients with alcoholic liver disease (ALD) with the use of cytoplasmic staining after stimulation through the T-cell receptor (TCR). The CD57+ subsets of the T cells of both healthy individuals and patients with ALD express significantly higher amounts of cytoplasmic tumor necrosis factor-alpha (TNF-) and interferon-gamma (IFN-) after 6 h of stimulation than do the CD57- subsets. This increased production can persist up to 46 h of continuous stimulation. Under these assay conditions, very little cytoplasmic interleukin (IL)-4 is observed in the T cells of either healthy control subjects or patients with ALD. Measurement of cytokine secretion by sort-purified CD57 T-cell subsets with the use of enzyme-linked immunosorbent assay (ELISA) shows that the CD57+ T-cell subset produces 18- to 30-fold more TNF- and IFN-, respectively, than does the CD57- subset in the first 12 h of stimulation. This response requires only stimulation through the TCR for the CD57+ subset, whereas significant secretion by the CD57- subset requires added IL-2 or anti-CD28 antibody. These results are consistent with the concept of the CD57+ T-cell subset as a differentiated effector cell and demonstrate that patients with ALD who are not drinking at the time of evaluation have normal or increased immediate TH1 T-cell responses.

Chronic ethanol induces inhibition of antigen-specific CD8+ but not CD4+ immunodominant T cell responses following Listeria monocytogenes inoculation.

Chronic ethanol consumption results in immunodeficiency. Previous work with chronic ethanol‐fed mice has shown reduced splenic weight and cellularity, including reduced numbers of CD8+ T cells. However, antigen‐specific CD8+ and CD4+ T cell responses in chronic ethanol‐fed mice have been studied relatively little. We have used an attenuated Listeria monocytogenes strain DPL 1942 (LM ΔactA) to inoculate mice and subsequently used CD4+ and CD8+ immunodominant peptides of LM to measure the CD4+ and CD8+ T cell responses after chronic ethanol exposure. We found no major differences between control and ethanol‐fed mice in the kinetics and persistence of antigen‐specific CD4+ T cells in response to an immunodominant LM peptide, as measured by intracellular IFN‐γ staining. In contrast to CD4+ responses, three methods of in vitro antigen presentation indicated that the primary response of CD8+ T cells to several different epitopes was reduced significantly in mice chronically fed ethanol. Antigen‐specific CD8+ T cells were also reduced in chronic ethanol‐fed mice during the contraction phase of the primary response, and memory cells evaluated at 29 and 60 days after inoculation were reduced significantly. BrdU proliferation assays showed that in vivo proliferation of CD8+ T cells was reduced in ethanol‐fed mice, and IL‐2‐dependent in vitro proliferation of naive CD8+ T cells was also reduced. In conclusion, these results suggest that antigen‐specific CD4+ T cell responses to LM are affected little by chronic ethanol consumption; however, antigen‐specific CD8+ T cell responses are reduced significantly, as are in vivo and in vitro proliferation. The reduction of antigen‐specific CD8+ T cells may contribute strongly to the immunodeficiency caused by ethanol abuse.

Chronic Ethanol Consumption Decreases Murine Langerhans Cell Numbers and Delays Migration of Langerhans Cells as Well as Dermal Dendritic Cells

BACKGROUND Chronic alcoholics experience increased incidence and severity of infections, the mechanism of which is incompletely understood. Dendritic cells (DC) migrate from peripheral locations to lymph nodes (LN) to initiate adaptive immunity against infection. Little is known about how chronic alcohol exposure affects skin DC numbers or migration. METHODS Mice received 20% EtOH in the drinking water for up to 35 weeks. Baseline Langerhans cell (LC) and dermal DC (dDC) numbers were enumerated by immunofluorescence (IF). LC repopulation after inflammation was determined following congenic bone marrow (BM) transplant and ultraviolet (UV) irradiation. Net LC loss from epidermis was determined by IF following TNF-alpha or CpG stimulation. LC and dDC migration into LN was assessed by flow cytometry following epicutaneous FITC administration. RESULTS Chronic EtOH consumption caused a baseline reduction in LC but not dDC numbers. The deficit was not corrected following transplantation with non-EtOH-exposed BM and UV irradiation, supporting the hypothesis that the defect is intrinsic to the skin environment rather than LC precursors. Net loss of LC from epidermis following inflammation was greatly reduced in EtOH-fed mice versus controls. Ethanol consumption for at least 4 weeks led to delayed LC migration into LN, and consumption for at least 8 weeks led to delayed dDC migration into LN following epicutaneous FITC application. CONCLUSIONS Chronic EtOH consumption causes decreased density of epidermal LC, which likely results in decreased epidermal immunosurveillance. It also results in altered migratory responsiveness and delayed LC and dDC migration into LN, which likely delays activation of adaptive immunity. Decreased LC density at baseline appears to be the result of an alteration in the skin environment rather than an intrinsic LC defect. These findings provide novel mechanisms to at least partially explain why chronic alcoholics are more susceptible to infections, especially those following skin penetration.

Erythromycin, lincosamides, peptidyl-tRNA dissociation, and ribosome editing

Inaccurate protein synthesis produces unstable β-galactosidase, whose activity is rapidly lost at high temperature. Erythromycin, lincomycin, clindamycin, and celesticetin were shown to counteract the error-inducing effects of streptomycin on β-galactosidase synthesized in the antibiotic-hypersensitive Escherichia coli strain DB-11 Met−. Newly synthesized β-galactosidase was more easily inactivated by high temperatures when synthesized by bacteria partially starved for arginine, threonine, or methionine. Simultaneous treatment with erythromycin or linocomycin yielded β-galactosidase that was inactivated by high temperatures less easily than during starvation alone, an effect attributed to stimulation of ribosome editing. When synthesized in the presence of canavanine, β-galactosidase was inactivated by high temperature more easily but this effect could not be reversed by erythromycin. The first arginine in β-galactosidase occurs at residue 13, so the effect of erythromycin during arginine starvation is probably to stimulate dissociation of erroneous peptidyl-tRNAs of at least that length. Correction of errors induced by methionine starvation is probably due to stimulation of dissociation of erroneous peptidyl-tRNAs bearing peptides at least 92 residues in length. All the effects of erythromycin or the tested lincosamides on protein synthesis are probably the result of stimulating the dissociation from ribosomes of peptidyl-tRNAs that are erroneous or short.

Lincosamide antibiotics stimulate dissociation of peptidyl-tRNA from ribosomes.

At nonpermissive temperatures the peptidyl-tRNA hydrolase of pth(Ts) bacterial mutants is inactivated, and cells accumulate peptidyl-tRNA and die. Doses of erythromycin, lincomycin, or clindamycin that inhibited the growth of antibiotic-hypersensitive DB-11 pth+ cells accelerated the killing of DB-11 pth(Ts) cells at nonpermissive temperatures. Erythromycin and lincomycin also stimulated the accumulation of peptidyl-tRNA. Lincomycin and clindamycin stimulated peptidyl-tRNA dissociation from ribosomes.

A Dynamic Flux in Natural Killer Cell Subsets as a Function of the Duration of Alcohol Ingestion

BACKGROUND Chronic ethanol (EtOH) consumption is associated with a wide variety of immune abnormalities including changes in T cells, B cells, dendritic cells, and natural killer (NK) cells. However, there is conflicting information as to the direction of such immune changes. The hypothesis that was tested in this report is that, for NK cells, the changes can vary as a function of the duration of alcohol ingestion. METHODS Using the Meadows-Cook murine model of chronic alcohol ingestion, the changes in NK cell function and subset distribution were examined as a function of the duration of alcohol ingestion. RESULTS Acute alcohol ingestion resulted in decreased number and cytotoxic function of NK cells with no effect on intracellular interferon gamma expression. These abnormalities normalized after 12 to 14 days of alcohol ingestion and there was an increase of NK cell number and cytotoxicity after 8 weeks of continued EtOH ingestion. Ten weeks of continued alcohol consumption results in a significant decrease in the Ly49H+ CD11b+ CD27- splenic NK cell subset; this difference continued to be significant at 30 weeks. CONCLUSIONS This report may explain some of the conflicting data in the literature that examined NK cell activity in alcoholic patients. It is apparent that various abnormalities can be seen in NK cell activity and subset distribution with the flux being a function of the duration of alcohol ingestion. The demonstration of a decrease in the Ly49H+ subset (which is known to be involved in resisting murine cytomegalovirus infection) may explain the reported increase in susceptibility to some viral infections in chronic alcohol abuse. Another novel finding is that changes of some subsets of NK cells are not evident until at least 10 weeks of continued EtOH consumption.

A Practical Method of Chronic Ethanol Administration in Mice

Mice provide a useful model for the study of immune deficiency caused by chronic alcohol abuse. Their suitability is related to several factors, including in particular the extensive knowledge base in the immunology of mice already existing in the literature. Specific modeling of the immunodeficiency of the chronic human alcoholic requires that ethanol must be administered to the model for a significant portion of its life span. In mice, it has proven to be necessary to administer ethanol daily for up to 32 wk or longer to observe all the immune abnormalities that occur in middle-aged alcoholic humans. Such time spans are problematic with many of the common protocols for ethanol administration. It has been shown by others and confirmed by our group that the most practical way of accomplishing such long protocols is by administering ethanol in water as the only choice of water. Details of management of the chronic ethanol mouse colony are described here that are necessary for the success of such studies, including methods for initiating ethanol administration, maintenance of barrier protection, monitoring weight gain, strain differences and fetal alcohol exposure.