Apoptosis and necrosis induced by ultraviolet radiation in the presence of autologous plasma

This paper deals with the effect of ultraviolet (UV) light (240–390 nm) at doses of 151–3020 J/m²* on the character of the death of donors’ blood lymphocytic cells (with the use of markers of apoptotic and necrotic cell death) and on the level of the CD95 receptor—a marker of apoptotic predisposition. UV irradiation has been shown to increase the expression of CD95 receptors, which is due mainly to synthesis de novo. It is revealed that over the course of the 24-h incubation of photomodified lymphocytes (at irradiation doses of 151 and 755 J/m²) without autologous blood plasma, cell death occurs by receptor-mediated apoptosis. Action of high irradiation doses (1510 and 3020 J/m²) leads to the massive necrotic death of immunocytes. The use of autologous blood plasma during the incubation of photomodified lymphocytes allows a reduction in the amount of both apoptotic and necrotic cells.     

Peculiarities of metabolism of UV-irradiated lymphocytes

The influence of UV-light (240-390 nm) at a dose of 151 and 755 J/m2 on the functional properties of lymphocyte metabolism key enzymes from donors' human blood: lactate dehydrogenase (LDH), cytochrome c oxidase, succinate dehydrogenase (SDH), Ca2(+)-ATPase of plasma membranes has been investigated. It has been revealed that photoinactivation of enzymes immediately after UV-irradiation which leads to the decrease of the ATP content in lymphocytes is replaced by the increased activity of the enzymes under investigation during daily incubation of lymphocytes. As a result, the level of ATP in photo-modified lymphocytes does not differ from that in native cells before incubation. This indicates the normalization of biochemical processes in lymphocytes influenced by UV-light applied in autotransfusion of UV-irradiated blood.     

Mechanisms of impairment of DNA repair in human cells. Interferons stimulated DNA repair in xeroderma pigmentosum cells

DNA repair synthesis and strand break DNA repair induced by 4-nitroquinoline-1-oxide and UV-irradiation in Xeroderma pigmentosum lymphocytes and fibroblasts pretreated by leucocyte interferons were studied. Stimulation of DNA repair synthesis in interferon-pretreated Xeroderma pigmentosum cells, defective in incision, was detected. No such effect was noted for strand break DNA repair. Hence, antimutagenic activity of interferons in human cells is connected with their modificating effect on DNA repair.     

Inhibition of phosphatidylethanolamine and phosphatidylinositol synthesis, alteration of the G0 and G1 cell cycle phases and spontaneous apoptosis in lymphocytes from patients under immunosuppressive treatment

Lymphocytes from patients treated with immunosuppressive agents were cultured for 48 hours either with or without concanavalin A. Phospholipid synthesis was then studied using 32p pulse-incorporation (5-hours pulses). Phosphatidylethanolamine synthesis was strongly decreased under immunosuppressive treatment: 1.5-fold in resting lymphocytes and 3- to 4-fold in concanavalin A-stimulated lymphocytes. Phosphatidylinositol synthesis also decreased about 2-fold in stimulated lymphocytes. These results indicate a loss of sensitivity of immunodeficient lymphocytes to the mitogen and an alteration of the G0 and the late G1 cell cycle phases. In parallel, but after a 72-hours incubation, lymphocytes were analysed by flow-cytofluorimetry with propidium iodide. Under concanavalin A-triggered stimulation, the entry into the S phase was much lower in immunodeficient lymphocytes as compared to standard. The characteristics of the G0-G1 population of lymphocytes were also modified. More importantly, after incubation in the culture medium in the absence of mitogen, we observed, among the immunodeficient lymphocytes, a high level of apoptotic cells, about 20 to 30%. This susceptibility to spontaneous apoptosis seems inherent to the status of immunodeficiency itself, whatever its origin. It may be related to the inhibition of phosphatidylethanolamine synthesis in the G0 phase.     

Activation by inflammatory stimuli increases neutrophil binding of human immunodeficiency virus type 1 and subsequent infection of lymphocytes

Resting neutrophils bind human immunodeficiency virus type 1 (HIV-1) and efficiently transfer infection to lymphocytes. The present study shows that a brief activation by inflammatory stimuli increases the neutrophil binding levels of both R5 and X4 isolates of HIV-1 at least twofold. The binding occurs independently of CD4, gp120, and incubation temperature and is observed with HIV-1 propagated either in lymphocytes or in HEK293 cells. Significantly, HIV-1 bound to the activated neutrophils accelerates the infection of activated lymphocytes compared to free HIV-1 or to HIV-1 bound to resting neutrophils. It is proposed that these events may contribute to the increased risk of HIV-1 transmission at sites of mucosal infection.     

Ways of realizing apoptosis of human lymphocytes induced by UV-light and reactive oxygen species

Changes of DNA structural condition, the level of membrane Fas-receptor expression, caspase-3 functional activity, concentrations of Ca2+, p53 and cytochrome c proteins of human lymphocytes in dynamics of apoptosis development induced by UV-light (240-390 nm) at doses 151, 1510, 3020 J/m2 and reactive oxygen species (superoxide anion-radical, hydroxyl radicals, hydrogen peroxide, singlet oxygen) have been studied. UV-light and reactive oxygen species have been established to induce fragmentation of lymphocyte DNA after 20 h incubation of the modified cells. It has been shown, that the increase in the expression level of membrane death Fas-receptors is observed during 1-5 h after exposure oflymphocytes to UV-light and ROS compared with intact cells. Also revealed is augmentation of lymphocyte caspase-3 functional activity 4 h after generation of singlet oxygen, hydroxyl radical and hydrogen peroxide addition, as well as 8 and 24 and 6 and 8 h after UV-irradiation of the cells at doses 151 and 1510 J/m2, correspondingly. Using DNA-comet method made it possible to tape that DNA damages (single-strand breaks) appear 15-20 min after lymphocyte UV-irradiation at doses 1510 and 3020 J/m and addition of hydrogen peroxide in concentration 10(-6) mol/l (C1 type comet) and reach their maximum 6 h after modification of the cells (C2 and C3 type comets). It has been observed, that 6 h after exposure oflymphocytes to hydrogen peroxide and UV-light at doses 1510 and 3020 J/m2, the p53 level of investigated cells raises. It has also been shown that the higher level of calcium in lymphocyte cytosol in conditions of UV-light exposure (1510 J/m2) and exogenous generation of reactive oxygen species is caused by Ca2+ exit from intracellular depots as a result of activating the components of the phosphoinositide mechanism for transferring information into a cell. Ideas about correlation between alterations of the calcium level and initiation of programmed cellular destruction of human lymphocytes after exposure to UV-irradiation and ROS is proposed. The authors come to the conclusion about the leading role of receptor-mediated (Fas-dependent) caspase- and p53-dependent ways of realizing apoptosis oflymphocytes induced by UV-light at doses 151 and 1510 J/m2 and active oxygen metabolites. The pattern of the possible intracellular events leading to apoptotic destruction of lymphocytes after their UV-irradiation is offered.     

Induction of CD69 activation molecule on human neutrophils by GM-CSF,IFN-gamma,and IFN-alpha

The CD69 glycoprotein is an early activation antigen of T and B lymphocytes but it expression is induced in vitro on cells of most hematopoietic lineages, including neutrophils after stimulation with PMA or fMLP. In this study, we investigated whether CD69 expression on human neutrophils could be modulated by inflammatory or anti-inflammatory cytokines (IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, G-CSF, GM-CSF, TNF-alpha, TGF-beta, IFN-alpha, IFN-gamma). Resting neutrophils from healthy subjects did not express CD69 on the cell surface; moreover, a preformed intracellular pool of CD69 was not evident in these cells. CD69 was barely detectable on these cells after overnight incubation in medium while overnight incubation with GM-CSF, IFN-gamma or IFN-alpha significantly induced CD69 expression on neutrophils with GM-CSF appearing to be the most potent inducer. This induction was dependent on a new protein synthesis as it was significantly inhibited by cycloheximide (about 50% inhibition). CD69 cross-linking on GM-CSF-primed neutrophils sinergized with LPS and increased TNF-alpha production and secretion suggesting a role for CD69-positive neutrophils in the pathogenesis and maintenance of different inflammatory diseases.     

Generation of active forms of oxygen by human peripheral blood neutrophils and lymphocytes during adhesion to glass

Oxygen activation by neutrophils and human blood lymphocytes at adhesion to glass have been studied by luminol--dependent chemiluminescence. It has been established that the cell interaction with glass leads to the formation of O2-., O2', .OH and H2O2. Chemiluminescence kinetics and the excited--oxygen forms ratio at adhesion were different for neutrophils and lymphocytes. The desorption of cells resulted in a decrease of the chemiluminescent response to neutrophils and lymphocytes when they again adhered to glass and in practically complete inhibition of chemiluminescence induced by adding concanavalin A. It has been determined that at adhesion of neutrophils and lymphocytes to glass different mechanisms of oxygen activation take place.     

Altered cellular response to UV irradiation in a patient affected by premature ageing

Summary An abnormal response to UV-irradiation was found in a patient affected by precocious senescence. A decreased level of unscheduled DNA synthesis (UDS) was present in 60% of G_o lymphocytes and in fibroblasts after the fifth culture passage. Hypersensitivity of lymphocytes to UV-light was indicated also by a decreased rate of DNA synthesis after mitogen stimulation. The results of this study indicate that the defect which determines the premature ageing influences the capacity to repair UV-induced DNA damage.     

Synergistic stimulatory effect of glucocorticoid, EGF and insulin on the synthesis of ribosomal RNA and phosphorylation of nucleolin in primary cultured rat hepatocytes.

Effects of dexamethasone, EGF and insulin on the synthesis of rRNA and phosphorylation of nucleolin in primary cultures of adult rat hepatocytes were studied. Hepatocytes were incubated for 8 h with EGF (20 ng/ml) plus insulin (0.1 microM) and/or for 20 h with dexamethasone (1 microM) before the end of incubation. The incorporation of [3H]uridine into acid-insoluble materials and the nuclear activity of RNA polymerase I were stimulated approx. 2-fold with EGF plus insulin and these were further enhanced 2-3-times by dexamethasone, although dexamethasone alone exerted no stimulation. When hepatocytes were incubated with [32P]orthophosphate, similar enhancement by these hormones was also observed in the phosphorylation of a nucleolar protein, nucleolin, which was detected by immunoprecipitation with anti-nucleolin antibodies. The amount of nucleolin was slightly increased by EGF plus insulin in the presence of dexamethasone, but scarcely changed by treatment with EGF plus insulin or dexamethasone alone. Cycloheximide inhibited RNA synthesis to a greater or lesser degree in the case of all hepatocytes which were cultured with or without these hormonal treatments. These results indicate that the in vivo effect of glucocorticoid on rRNA synthesis and nucleolin phosphorylation in liver is primarily a direct action on parenchymal cells and requires other growth factors such as EGF and insulin.     

Further characterization of SOS system induction in recBC mutants of Escherichia coli

Expression of several SOS functions such as induction of lambda prophage, inhibition of cell division and induction of both umuC and recA genes after UV-irradiation, nalidixic acid or mitomycin C addition was studied in an RecBC- mutant. UV-irradiation and mitomycin C induced all SOS functions studied in the RecBC- cells but at a lower level and delayed with respect to the wild-type strain. On the contrary, nalidixic acid was unable to trigger any of these SOS functions. In the RecBC- mutant, adenine only had a stimulating effect on the amplification of RecA protein synthesis following UV-irradiation. Nevertheless, in the wild-type strain the stimulating effect occurred in all SOS functions studied following UV-irradiation as well as in the amplification of RecA protein synthesis by nalidixic acid but not in the other SOS functions triggered by this compound. Furthermore, adenine produced a decrease in the mitomycin C-mediated induction of all SOS functions studied in both RecBC- and wild-type strains.     

Characteristics of RNA and protein synthesis in the polymorphonuclear neutrophilic granulocytes of wounds

RNA and protein synthesis was comparatively studied in blood and wound neutrophils by electron microscopic autoradiography. It has been shown that the penetration of neutrophils into the wound was associated with a significant rise in RNA and a decrease in protein synthesis.     

Suppression of DNA synthesis in lymphocytes by UV-irradiated plasma

The autologous plasma, isolated upon UV-irradiation of the whole blood, has an inhibitory effect on mitogen-induced, blastogenesis of human lymphocytes. Its addition to the culture medium results in a statistically significant suppression of DNA synthesis in lymphocytes in the presence of phytohemagglutinin and concanavalin A. No such effect was observed with the use of pokeweed mitogen. Our studies show that this phenomenon is associated with photoconversion of the plasma components.     

Synergistic stimulatory effect of glucocorticoid,EGF and insulin on the synthesis of ribosomal RNA and phosphorylation of nucleolin in primary cultured rat hepatocytes

Effects of dexamethasone, EGF and insulin on the synthesis of rRNA and phosphorylation of nucleolin in primary cultures of adult rat hepatocytes were studied. Hepatocytes were incubated for 8 h with EGF (20 ng/ml) plus insulin (0.1 μM) and/or for 20 h with dexamethasone (1 μM) before the end of incubation. The incorporation of [³H]uridine into acid-insoluble materials and the nuclear activity of RNA polymerase I were stimulated approx. 2-fold with EGF plus insulin and these were further enhanced 2–3-times by dexamethasone, although dexamethasone alone exerted no stimulation. When hepatocytes were incubated with [³²P]orthophosphate, similar enhancement by these hormones was also observed in the phosphorylation of a nucleolar protein, nucleolin, which was detected by immunoprecipitation with anti-nucleolin antibodies. The amount of nucleolin was slightly increased by EGF plus insulin in the presence of dexamethasone, but scarcely changed by treatment with EGF plus insulin or dexamethasone alone. Cycloheximide inhibited RNA synthesis to a greater or lesser degree in the case of all hepatocytes which were cultured with or without these hormonal treatments. These results indicate that the in vivo effect of glucocorticoid on rRNA synthesis and nucleolin phosphorylation in liver is primarily a direct action on parenchymal cells and requires other growth factors such as EGF and insulin.     

Effect of lipid peroxide photooxidation on activity of lymphocyte-bound peroxidase

The UV-light influence (240-390 nm) in the doses range of 75.5 divided by 2265 J/m2 has been studied on structurally functional state of lymphocytes by the method of determination of the TBA-active products, spectrophotometric method and enzyme-linked immunosorbent assay. It has been shown that UV-irradiation dose increase led to the intensification of lipids peroxide photooxidation processes on lymphocytes, accompanied by the increase of their natural peroxidase activity and ability to sorb exogenic peroxidase. The association of peroxidase with the native and UV-irradiated lymphocytes results in the decrease of its catalytic activity.     

Endotoxins of enteric pathogens modulate the functions of human neutrophils and lymphocytes

The locomotor responses of human peripheral blood neutrophils and lymphocytes were measured by the change from spherical to polarized shapes in the presence of endotoxins (lipopolysaccharide, LPS) of enteric pathogens: S. dysenteriae type 1, V. cholerae Inaba 569B, S. typhimurium, and K. pneumoniae. We reported earlier that these endotoxins are chemotactic factors for the neutrophils since they stimulated cell polarization within a few minutes of incubation. Endotoxins had an inhibitory effect upon neutrophil phagocytosis of opsonized yeast and the cells engulfed fewer yeasts. Interestingly, endotoxins increased neutrophil adhesion to clean glass surfaces, but stimulated the cells to exhibit increased random locomotion (chemokinesis) through cellulose nitrate filters and show an enhanced ability to reduce nitroblue tetrazolium (NBT) dye. Unlike neutrophils, lymphocytes direct from blood do not show polarized morphology towards chemotactic factors but the cells acquire locomotor capacity during 24-72 h culture with mitogens such as phytohemagglutinin (PHA), phorbol myristate acetate or concanavalin A. Stimulation of blood lymphocytes with endotoxins did not induce cell polarization in short-term but long-term culture resulted in an increase in the proportion of polarized cells that acquired locomotor morphologies. The majority of these cells were identified as esterase negative B-lymphocytes that migrated through filters. Despite the optimum time of incubation for each of these cell types being different, we found that lymphocytes respond to much lower concentrations of endotoxins than the neutrophils. These findings suggest that endotoxins of enteric pathogens modulate the functions of human blood neutrophils and lymphocytes.     

Semi-conservative synthesis of DNA in UV-sensitive mutant cells of Chinese hamster after UV-irradiation

A study was made of the rate of semi-conservative DNA synthesis in asynchronous UV-resistant (clone V79) and UV-sensitive clones (VII and XII) of Chinese hamster cells after UV-irradiation. In all 3 clones studied, UV-irradiation (5-30 J/m2) induced a decrease in the rate of DNA synthesis during the subsequent 1-2 h. In the resistant clone (V79) recovery of DNA synthesis rate started after the first 2 h post-irradiation (5 J/m2) and by the 3rd hour reached its maximum value, which constituted 70% of that observed in control, non-irradiated cells. The UV-sensitive mutant clones VII and XII showed no recovery in the rate of DNA synthesis during 6-7 h post-irradiation. The results obtained show that the survival of cells is correlated with the ability of DNA synthesis to recover after UV-irradiation in 3 clones studied. The observed recovery of UV-inhibited DNA synthesis in mutant clones may be due to certain defects in DNA repair.