In vitro effects of ethanol on polymorphonuclear leukocyte membrane receptor expression and mobility

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.

Effects of ethanol on cytokine generation and NFκB activity in human lung epithelial cell

Alcohol abuse is associated with enhanced risk for pulmonary infections, but the mechanisms remain obscure. We assessed whether ethanol reduced generation of cytokines from a human lung epithelial cell line (A549) in vitro and if effects on the NFkappaB transcription factor were involved. Exposure of A549 to ethanol (0.1-1%) dose-dependently inhibited (by 15-49%) the release of G-CSF and IL-8, but not of M-CSF, triggered by IL1beta or TNFalpha. Ethanol also inhibited by 49% the IL-1beta stimulated translocation of the p65 subunit of NFkappaB from the cytoplasm into the nucleus. Using a kappaB binding and luciferase coupled construct, transfected into A549 cells, we found that 1% ethanol specifically reduced IL-1beta and TNFalpha induced luciferase activity with 34 and 40%, respectively. Thus, in vitro exposure of lung epithelial cells to ethanol reduced the generation of cytokines, as well as translocation and gene activation by NFkappaB.

Lindane stimulates neutrophils by selectively activating phospholipase C and phosphoinositide-kinase activity

The organochlorine insecticide lindane is a known activator of neutrophil responses. In this work we delineated the biochemical pathways by which lindane stimulates neutrophil oxidant production. Plasma membrane GTPase activity was not stimulated by lindane, ruling out a role for lindane-induced activation of G-proteins or G-protein coupled receptors, whereas inhibition of phospholipase C inhibited lindane-induced oxidant production. Together these data pointed to phospholipase C as the direct target of lindane activation. Type I phosphoinositide 3-kinase was not significantly activated by lindane and an inhibitor of phosphoinositide 3-kinases inhibited oxidant production by only 40%. Thus, Type I phosphoinositide 3-kinase played a minor role, if any, in lindane-induced oxidant production. Lindane stimulated an increase in phosphatidylinositol phosphate suggesting a Type II or III phosphotidylinositol 3-kinase or phosphatidylinositol 4-kinase activity was also stimulated.

Effects of ethanol on NF-kappaB activation, production of myeloid growth factors, and adhesive events in human endothelial cells

Because neutropenia may aggravate infections in alcoholics, effects of ethanol on the generation of myeloid growth factors by human umbilical vein endothelial cells (HUVECs) and on interactions with neutrophils were examined in vitro. Exposure of HUVECs to ethanol (0.01%-1%) dose-dependently inhibited (by 12%-27%) the release of stem cell factor, granulocyte-macrophage and granulocyte colony-stimulating factors (CSFs), or interleukin (IL)-8, but not of macrophage CSF triggered by lipopolysaccharide (LPS) or IL-1. Ethanol also inhibited the LPS-induced increase in HUVECs to bind neutrophils by 28% (without affecting the expression of intracellular adhesion molecule-1 and E-selectin) and inhibited the translocation of the p65 subunit of NF-kappaB from the cytoplasm to the nucleus by 46%. Thus, exposure of HUVECs to ethanol inhibited the generation of cytokines important for myeloid cell development and reduced the adhesiveness of HUVECs for neutrophils: effects that are possibly linked to the reduced activation of NF-kappaB.

Ethanol increases superoxide anion production stimulated with 4beta-phorbol 12-myristate 13-acetate in human polymorphonuclear leukocytes. Involvement of protein kinase C

Stimulation of human polymorphonuclear leukocytes (PMNs) with PMA initiates a cascade of events leading to the production and release of superoxide anion (O-2), a major component in anti-bacterial defense. Generation of O-2 by PMA-stimulated PMNs occurs through the translocation and activation of protein kinase C (PKC). In this study, using freshly isolated PMNs, we examined the effect of ethanol on this response to PMA. Our results show that the basal production of O-2 was not affected by ethanol. In contrast, the response induced by PMA was potentiated by ethanol. This potentiation was observed even at high doses of PMA (200 nM) which alone had stimulated the O-2 response maximally. This enhanced response was not due to an increase of PMA uptake by PMNs. The maximal effect was obtained when the cells were preincubated with 80 mM of ethanol before PMA stimulation. Measurement of PKC activity in the cytosolic and membrane fractions showed that pretreatment of PMNs with ethanol increased twofold the PMA-stimulated PKC activity in the membrane fraction. Furthermore, Western blot analysis verified that this increase in PKC activity in the membrane fraction was linked to an increase in the translocation of PKC-alpha and -beta isoforms to the membrane. These results suggest that ethanol potentiates PMA-induced O-2 production through increasing PKC translocation and activity in PMNs.

Cellular responses to FMLP challenging: a mini-review

FMLP (N-formyl-methionyl-leucyl-phenylalanine) and other N-formylpeptides are powerful "activators" of polymorphonuclear and mononuclear phagocytes, but they are also active on other cell types. Present knowledge about formylpeptide receptors and the relevant tools for their imaging and the study of their dynamics are briefly discussed. The main responses elicited by FMLP in granulocytes are cell polarisation, the generation of reactive oxygen species, the production of arachidonic acid metabolites, and the release of lysosomal enzymes. The transduction cascades involved and the agents able to modulate these responses are reviewed. Homologous desensitization and heterologous desensitization of the FMLP-receptor following ligation of other chemokine receptors are also outlined. Finally, the receptor expression and the pharmacological and toxic actions of FMLP upon other tissues and organs, and its actions on the developing embryo, are illustrated.

Isotonic ethanol inhibits the generation of superoxide anion in neutrophils by inducing cell expansion

The effects of ethanol on the production of oxygen-derived free radicals by neutrophils are controversial. Osmolarity-mediated alteration of cell volume appears to be an important mechanism for regulating neutrophil activity. We investigated in neutrophils from healthy volunteers the effect of isotonic/hypertonic ethanol on both chemiluminescence amplified by a Cypridina luciferin analog in response to N-formyl-Met-Lue-Phe and cell volume measured with a Coulter counter. Both isotonic and hypertonic ethanol significantly decreased chemiluminescence in a dose-dependent manner. Isotonic ethanol produced a greater magnitude of inhibition than hypertonic ethanol (P<0.01). Another permeable molecule, urea, and hypotonic solution had the same effects on chemiluminescence. Isotonic and hypertonic ethanol caused a prompt cell expansion and shrinking, respectively. On the other hand, isotonic sucrose, an impermeable molecule, was ineffective in both chemiluminescence and cell volume changes. These data suggest that isotonic ethanol inhibits the superoxide anion production by inducing cell expansion probably due to increased intracellular osmotic pressure caused by rapid ethanol permeation through the plasmalemma. This impaired neutrophil function may, in some part, contribute to the susceptibility to infection in alcoholics.