A dynamic flux in natural killer cell subsets as a function of the duration of alcohol ingestion

Natural killer cells immunosenescence and the impact of lifestyle management

Natural killer cells (NKs) are lymphocytes of the innate immune system that quickly respond to viruses, infections, and tumors during their short cell life cycle. However, it was recently found that NKs undergo quantitative, distributional, structural, and functional phenotypic changes during aging that suppress immune responses, which is known as immunosenescence. The aging host environment, cytokine regulation, cytomegalovirus status, and hypothalamic‒pituitary‒adrenal axis have significant effects on NK function. Different lifestyle management interventions modulate the number and cytotoxic activity of NKs, which are essential for rebuilding the immune barrier against pathogens in elderly individuals. Based on recent studies, we review the phenotypic changes of and potential threats of NKs during aging and explore the underlying mechanisms. By summarizing the effects of lifestyle management on NKs and their application prospects, we aim to provide evidence for enhancing immune system function against immune diseases in elderly individuals.

Restricted immunological and cellular pathways are shared by murine models of chronic alcohol consumption

Murine models of chronic alcohol consumption are frequently used to investigate alcoholic liver injury and define new therapeutic targets. Lieber-DeCarli diet (LD) and Meadows-Cook diet (MC) are the most accepted models of chronic alcohol consumption. It is unclear how similar these models are at the cellular, immunologic, and transcriptome levels. We investigated the common and specific pathways of LD and MC models. Livers from LD and MC mice were subjected to histologic changes, hepatic leukocyte population, hepatic transcripts level related to leukocyte recruitment, and hepatic RNA-seq analysis. Cross-species comparison was performed using the alcoholic liver disease (ALD) transcriptomic public dataset. Despite LD mice have increased liver injury and steatosis by alcohol exposure, the number of CD45⁺ cells were reduced. Opposite, MC mice have an increased number of monocytes/liver by alcohol. The pattern of chemokine gradient, adhesion molecules, and cytokine transcripts is highly specific for each model, not shared with advanced human alcoholic liver disease. Moreover, hepatic RNA-seq revealed a limited and restricted number of shared genes differentially changed by alcohol exposure in these 2 models. Thus, mechanisms involved in alcohol tissue injury are model-dependent at multiple levels and raise the consideration of significant pathophysiological diversity of human alcoholic liver injury.

Health effects of a forest environment on natural killer cells in humans: an observational pilot study

Health effect assessments based on natural killer (NK) cells are an important emerging area of human health. We recruited 90 forest staff members in Xitou, Taiwan and 110 urban staff members in Taipei to investigate the health effects of forest environment exposure on NK cells (CD3⁻/CD56⁺) and activating NK cells (CD3⁻/CD56⁺/CD69⁺) in humans. We also invited 11 middle-aged volunteers in a pilot study to participate in a five-day/four-night forest trip to Xitou forest to investigate the health effects of a forest trip on NK cells and activating NK cells. Results showed that NK cells were higher in the forest group (19.5 ± 9.1%) than in the urban group (16.4 ± 8.4%). In particular, the percentage of NK cells was significantly higher in the forest group than in the urban group among the subgroups of male, a higher body mass index (≥ 25 kg/m²), without hypertension, lower high-sensitivity C-reactive protein, hyperglycemia, without smoking habit, and with tea drinking habit. After the five-day trip in Xitou forest, the percentage of activating NK cells of the invited participants from Taipei increased significantly after the trip to Xitou forest (0.83 ± 0.39% vs. 1.72 ± 0.1%). The percentage of activating NK cells was 1.13 ± 0.43%, which was higher than the baseline value of 0.77 ± 0.38% before the forest trip among the seven subjects who participated in the follow-up study four days after returning to Taipei. This study suggests that exposure to forest environments might enhance the immune response of NK cells and activating NK cells in humans.

Hepatic Immune System: Adaptations to Alcohol

Both the innate and adaptive immune systems are critical for the maintenance of healthy liver function. Immune activity maintains the tolerogenic capacity of the liver, modulates hepatocellular response to various stresses, and orchestrates appropriate cellular repair and turnover. However, in response to heavy, chronic alcohol exposure, the finely tuned balance of pro- and anti-inflammatory functions in the liver is disrupted, leading to a state of chronic inflammation in the liver. Over time, this non-resolving inflammatory response contributes to the progression of alcoholic liver disease (ALD). Here we review the contributions of the cellular components of the immune system to the progression of ALD, as well as the pathophysiological roles for soluble and circulating mediators of immunity, including cytokines, chemokines, complement, and extracellular vesicles, in ALD. Finally, we compare the role of the innate immune response in health and disease in the liver to our growing understanding of the role of neuroimmunity in the development and maintenance of a healthy central nervous system, as well as the progression of neuroinflammation.

Spinal AMPA Receptor GluA1 Ser831 Phosphorylation Controls Chronic Alcohol Consumption-Produced Prolongation of Postsurgical Pain

Previous studies have shown that excessive alcohol drinking is associated with chronic pain development; however, the molecular mechanism underlying this association is poorly understood. In this study, we investigated the effect of chronic alcohol consumption on plantar incision-induced postsurgical pain. We observed that 4-week ethanol drinking significantly prolonged plantar incision-induced mechanical pain, but not thermal pain. The chronic alcohol consumption enhanced plantar incision-produced α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluA1 phosphorylation at the Ser831 site in the spinal cord. The targeted mutation of the GluA1 phosphorylation site in GluA1 S831A mutant mice significantly inhibited the incisional pain prolongation produced by chronic alcohol consumption. Moreover, chronic alcohol consumption combined with plantar incision markedly increased AMPA receptor-mediated miniature excitatory postsynaptic currents in the spinal dorsal horn neurons, and this effect was diminished significantly in the GluA1 S831A mutant mice. Our results suggest that chronic alcohol consumption may promote the development of persistent postsurgical pain by enhancing AMPA receptor GluA1 Ser831 phosphorylation. We identified chronic alcohol consumption as a risk factor for pain chronification after surgery.

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.

Ethanol-dependent expression of the NKG2D ligands MICA/B in human cell lines and leukocytes

Alcohol consumption affects the human immune system, causing a variety of disorders. However, the mechanisms of development of these changes are not fully understood. We hypothesized that ethanol may influence the expression of MICA and MICB, stress-induced molecules capable of regulating the activity of cytotoxic lymphocytes through the interaction with receptor NKG2D, which substantially affects the functionality of cellular immunity. We analyzed the effects of ethanol on MICA/B expression in tumor cell lines and human leukocytes. In the cell line models, ethanol caused different changes in the surface expression of MICA/B; in particular, it induced the translocation of intracellular proteins MICA/B to the cell surface and shedding of MICA (in soluble and microparticle-associated forms) from the plasma membrane. The observed results are not linked with cell death in cultures, taking place only under higher doses of ethanol. Ethanol at physiologically relevant concentrations (and higher) stimulated expression of MICA/B genes in different cell types. The effect of ethanol was more pronounced in hepatocyte line HepG2 compared with hematopoietic cell lines K562, Jurkat, and THP-1. Among the tested leukocytes, the most sensitive to ethanol action were T cells activated ex vivo with IL-2, in which the increase of MICA/B mRNA expression was registered with the smallest dose of ethanol (0.125%). In human monocytes, ethanol may lead to elevations in surface MICA/B levels. Presumably, changes in MICA/B expression caused by ethanol can affect the functions of NKG2D-positive cytotoxic lymphocytes, modulating immune reactions at excessive alcohol consumption.

Chronic alcohol consumption inhibits peripheral NK cell development and maturation by decreasing the availability of IL-15

NK cells are innate immune cells and have important roles in antiviral and antitumor immunity. Based on the transcriptional regulation, organ distribution, and cell function, NK cells have recently been further divided into cytotoxic conventional NK cells (cNK) and noncytotoxic helper-like group 1 innate lymphoid cells (ILC1s). It is well known that chronic alcohol consumption decreases peripheral NK cell number and cytolytic activity; however, the underlying mechanism remains to be elucidated. How chronic alcohol consumption affects ILC1s is, to our knowledge, completely unexplored. Herein, we used a well-established mouse model of chronic alcohol consumption to study the effects of alcohol on transcription factor expression, maturation, and cytokine production of cNK cells and ILC1s in various organs. We found that alcohol consumption significantly decreased Eomes-expressing cNK cells in all the examined organs, except BM, but did not significantly affect ILC1s. Alcohol consumption compromised cNK cell development and maturation. Exogenous IL-15/IL-15Rα treatment caused full recovery of Eomes-expressing cNK cell number and maturation. Taken together, our data indicated that chronic alcohol consumption decreases cNK cell number and cytolytic activity by arresting cNK cell development at the CD27⁺CD11b⁺ stage. This developmental arrest of NK cells results from a lack of IL-15 availability in the microenvironment. IL-15/IL-15Rα treatment can recover alcohol consumption-induced developmental defect in NK cells.

Trillin Reduces Liver Chronic Inflammation and Fibrosis in Carbon Tetrachloride (CCl4) Induced Liver Injury in Mice

Trillin is an active ingredient isolated from Dioscorea nipponica Makino. This study investigated the anti-inflammatory and anti-fibrosis effects of trillin on CCl4-induced hepatotoxicity in C57BL/6 mice. Chronic inflammation and fibrosis were induced by intraperitoneal administration of CCl4 0.5 μL/g of body weight twice a week for 6 weeks. Trillin (50 mg/kg, 100 mg/kg) was administered by gavage for 12 days before finishing the CCl4 induction. Aspartate amino-transferase (AST) and glutamic-pyruvic transaminase (ALT) in serum were determined by AST and ALT kits. Superoxidase dismutase (SOD) activity and malondialdehyde (MDA) levels in serum were assayed by SOD and MDA kits. Meanwhile, the levels of inflammatory mediators including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in serum were detected by enzyme-linked immunosorbent assay (ELISA) method. Pathological changes were observed by hematoxylin-eosin (HE) staining. The proteins of the NF-κB pathway and the TGF-β/Smad pathway were measured by western blot. The trillin-treated group exhibited reduced AST, ALT, MDA, IL-6, TNF-α, and IL-1β, and increased SOD. Histological analyses of the trillin-treated group exhibited reduced inflammatory process and prevented liver fibrosis. Western blot analyses of the trillin-treated group showed reduced NF-κB pathway and TGF-β/Smad pathway.

SIGNIFICANCE

Based on the results of the present study, trillin can be used as a potential anti-inflammatory drug for chronic hepatic inflammation.

Is excessive acetaminophen intake associated with transaminitis in adult patients with dengue fever?

BACKGROUND

Dengue, an endemic infection causing severe flu-like symptoms and fever, is often treated with high-dose acetaminophen that can exceed recommended daily dosages. This leads to hepatotoxicity, although the underlying mechanism is poorly understood. We hypothesised that excessive acetaminophen causes hepatic toxicity in dengue patients.

AIMS

To investigate a correlation between elevated serum transaminases and excessive acetaminophen intake, and other aggravating factors of liver injury in dengue cases.

METHODS

This prospective observational study obtained blood samples from 150 participants with acute febrile illness for dengue serological tests, blood counts, and the detection of serum transaminases and acetaminophen levels. Other factors were determined by questionnaire.

RESULTS

Of 150 participants enrolled, 77 had dengue fever. Abnormally high serum aspartate transaminase and alanine transaminase levels were present in 97.0% and 75.3% of dengue cases respectively. Multivariate analysis of cases with increased serum transaminases more than threefold normal upper limits indicated that male gender (odds ratio (OR) = 3.62, 95% confidence interval (CI) 1.38-9.42) and consuming >8 g acetaminophen orally (OR = 4.62, 95% CI 1.37-13.18) correlated with transaminitis. No correlation was found for other factors such as age, fever day at presentation, body mass index, alcohol intake or dengue severity classification (all P > 0.05). Chronic alcohol consumption was higher in non-dengue (2.6%) versus dengue cases (27.8%) (P < 0.01).

CONCLUSIONS

Most dengue patients had mild-to-moderate transaminitis. Male gender and acetaminophen >8 g were associated with increased serum transaminases. Thus, 1000 mg acetaminophen every 8 h or <3000 mg/day is recommended for dengue cases. Chronic alcohol consumption might be protective against dengue infection.

Impact of dietary components on NK and Treg cell function for cancer prevention

An important characteristic of cancer is that the disease can overcome the surveillance of the immune system. A possible explanation for this resistance arises from the ability of tumor cells to block the tumoricidal activity of host immune cells such as natural killer (NK) cells by inducing the localized accumulation of regulatory T (Treg) cells. Evidence exists that components in commonly consumed foods including vitamins A, D, and E, water-soluble constituents of mushrooms, polyphenolics in fruits and vegetables, and n-3 fatty acids in fish oil can modulate NK cell activities, Treg cell properties, and the interactions between those two cell types. Thus, it is extremely important for cancer prevention to understand the involvement of dietary components with the early stage dynamics of interactions among these immune cells. This review addresses the potential significance of diet in supporting the function of NK cells, Treg cells, and the balance between those two cell types, which ultimately results in decreased cancer risk.

Alcohol Use As a Risk Factor in Infections and Healing: A Clinician's Perspective

Physicians have recognized for more than a century that alcohol use is associated with infections and that alcoholics are especially at risk for pneumonia. Clear evidence now indicates that alcohol has a systemic effect on every organ. This review first presents a clinical case to describe a patient with immunity issues complicated by alcohol use-a setting familiar to many clinicians. This is followed by a description of the molecular mechanisms that explain the secondary immune deficiency produced by alcohol in the host, focusing mostly on the gut and lower respiratory mucosal immunity. The goal of this review is to increase awareness of the new mechanisms being investigated to understand how alcohol affects the human immune system and the development of new strategies to attenuate adverse outcomes in the affected population.

Diethylcarbamazine reduces chronic inflammation and fibrosis in carbon tetrachloride- (CCl₄-) induced liver injury in mice

This study investigated the anti-inflammatory effects of DEC on the CCl₄-induced hepatotoxicity in C57BL/6 mice. Chronic inflammation was induced by i.p. administration of CCl₄ 0.5 μL/g of body weight through two injections a week for 6 weeks. DEC (50 mg/kg) was administered by gavage for 12 days before finishing the CCl₄ induction. Histological analyses of the DEC-treated group exhibited reduced inflammatory process and prevented liver necrosis and fibrosis. Immunohistochemical and immunofluorescence analyses of the DEC-treated group showed reduced COX-2, IL1β, MDA, TGF-β, and αSMA immunopositivity, besides exhibiting decreased IL1β, COX-2, NFκB, IFNγ, and TGFβ expressions in the western blot analysis. The DEC group enhanced significantly the IL-10 expression. The reduction of hepatic injury in the DEC-treated group was confirmed by the COX-2 and iNOS mRNA expression levels. Based on the results of the present study, DEC can be used as a potential anti-inflammatory drug for chronic hepatic inflammation.

Role of NK cell subsets in organ-specific murine melanoma metastasis

Tumor metastasis plays a major role in the morbidity and mortality of cancer patients. Among solid tumors that undergo metastasis, there is often a predilection to metastasize to a particular organ with, for example, prostate cancer preferentially metastasizing to bones and colon cancer preferentially metastasizing to the liver. Although many factors are thought to be important in establishing permissiveness for metastasis, the reasons for organ-specific predilection of each tumor are not understood. Using a B16 murine melanoma model, we tested the hypothesis that organ-specific NK cell subsets play a critical role in organ-specific metastasis of this tumor. Melanoma cells, given intravenously, readily colonized the lungs but not the liver. NK cell depletion (either iatrogenically or by using genetically targeted mice) resulted in substantial hepatic metastasis. Analysis of NK cell subsets, defined by the differential expression of a combination of CD27 and CD11b, indicated a significant difference in the distribution of NK cell subsets in the lung and liver with the mature subset being dominant in the lung and the immature subset being dominant in the liver. Several experimental approaches, including adoptive transfer, clearly indicated that the immature hepatic NK cell subset, CD27+ CD11b–, was protective against liver metastasis; this subset mediated its protection by a perforin-dependent cytotoxic mechanism. In contrast, the more mature NK cell subsets were more efficient at reducing pulmonary tumor load. These data indicate that organ-specific immune responses may play a pivotal role in determining the permissiveness of a given organ for the establishment of a metastatic niche.

Chronic alcohol ingestion increases mortality and organ injury in a murine model of septic peritonitis

Background

Patients admitted to the intensive care unit with alcohol use disorders have increased morbidity and mortality. The purpose of this study was to determine how chronic alcohol ingestion alters the host response to sepsis in mice.

Methods

Mice were randomized to receive either alcohol or water for 12 weeks and then subjected to cecal ligation and puncture. Mice were sacrificed 24 hours post-operatively or followed seven days for survival.

Results

Septic alcohol-fed mice had a significantly higher mortality than septic water-fed mice (74% vs. 41%, p = 0.01). This was associated with worsened gut integrity in alcohol-fed mice with elevated intestinal epithelial apoptosis, decreased crypt proliferation and shortened villus length. Further, alcohol-fed mice had higher intestinal permeability with decreased ZO-1 and occludin protein expression in the intestinal tight junction. The frequency of splenic and bone marrow CD4+ T cells was similar between groups; however, splenic CD4+ T cells in septic alcohol-fed mice had a marked increase in both TNF and IFN-γ production following ex vivo stimulation. Neither the frequency nor function of CD8+ T cells differed between alcohol-fed and water-fed septic mice. NK cells were decreased in both the spleen and bone marrow of alcohol-fed septic mice. Pulmonary myeloperoxidase levels and BAL levels of G-CSF and TFG-β were higher in alcohol-fed mice. Pancreatic metabolomics demonstrated increased acetate, adenosine, xanthine, acetoacetate, 3-hydroxybutyrate and betaine in alcohol-fed mice and decreased cytidine, uracil, fumarate, creatine phosphate, creatine, and choline. Serum and peritoneal cytokines were generally similar between alcohol-fed and water-fed mice, and there were no differences in bacteremia, lung wet to dry weight, or pulmonary, liver or splenic histology.

Conclusions

When subjected to the same septic insult, mice with chronic alcohol ingestion have increased mortality. Alterations in intestinal integrity, the host immune response, and pancreatic metabolomics may help explain this differential response.