Regulatory T-cells in Periapical Lesions

CD4+CD25hiFoxp3+ regulatory T-cells (Tregs) are of crucial importance in regulating the immune response, including the control of any defense against infection. Their presence in periapical lesions has not been demonstrated, as yet. We hypothesized that Tregs infiltrate periapical lesions, where they inhibit T-cell proliferation. The aim of this study was to characterize Tregs in periapical lesions by confocal microscopy, flow cytometry, and functional assays. We showed that CD4+CD25hiFoxp3+ cells in periapical lesions expressed IL-10 and TGF-β. Their frequency was significantly higher than in peripheral blood and correlated with the levels of TGF-β and IL-10 in culture supernatants of periapical lesion mononuclear cells. Tregs inhibited the proliferation of responder T-cells in vitro, at least in part, by stimulating the production of IL-10. These findings suggest that CD4+CD25hiFoxp3+ cells in periapical lesions may play regulatory roles in controlling local immune/inflammatory processes.

Modulatory effects of garlic extracts on proliferation of T-lymphocytes in vitro stimulated with concanavalin A

Different active components from the garlic (Allium sativum) possess immunomodulatory activity both in vitro and in vivo. However, mechanisms of their actions are not sufficiently elucidated. In this study we examined the effects of garlic aqueous extract (GAE) and garlic ethanolic extract (GEE), prepared from two different garlic powder samples, on proliferation of rat thymocytes and splenocytes in culture, stimulated with concanavalin A (Con A). It has been shown that the extracts from both samples significantly modulate lymphocyte proliferation, triggered by this potent T-cell mitogen, depending on the type and dilutions of extracts and concentrations of Con A. The extracts, alone, were not mitogenic for lymphocytes. Generally, higher concentrations of the extracts showed inhibitory effects, whereas lower concentrations significantly augmented proliferation of lymphocytes. The stimulatory effect of GAE was stronger using splenocytes and suboptimal concentrations of Con A as a consequence of increased interleukin 2 (IL-2) production as well as the expression of IL-2 receptor alpha (IL-2Ralpha). The relationship between these two phenomena was demonstrated using neutralizing anti-IL-2Ralpha monoclonal antibody. The inhibitory effect of GAE correlated with a decrease in IL-2 production, but was not followed by down-regulation of IL-2Ralpha expression. The addition of IL-2 almost completely abolished inhibition of lymphocyte proliferation in the presence of higher concentrations of GAE.

Characterization of antigen-presenting cells in human apical periodontitis lesions by flow cytometry and immunocytochemistry

AIM

To analyse phenotypic characteristics of antigen-presenting cells (APC), isolated from human periapical lesions by flow cytometry and immunocytochemistry.

METHODOLOGY

Sixteen periapical lesions were digested for 15 min with 0.05% collagenase. Mononuclear cells, separated from other inflammatory cells by density centrifugation, were processed for flow cytometry and/or immunocytochemistry. Single and double immunostainings were performed using monoclonal antibodies specific for human CD45, CD3, CD19, CD14, HLA-DR, CD1a, CD83 and CD123.

RESULTS

Antigen-presenting cells (HLA-DR(+) cells) represented 32.9 +/- 17.8% of total mononuclear cells. Amongst them, B cells (HLA-DR(+) CD19(+)) were the predominant APC population, followed by activated macrophages (HLA-DR(+) CD14(+)), dendritic cells (DC) (HLA-DR(+) CD14(-) CD19(-) CD3(-)) and activated T cells (HLA-DR(+) CD3(+)). Based on the predominance of T cells (CD3(+)) or B cells and plasma cells (CD19(+) and CD19(lo), respectively) amongst mononuclear cell infiltrates, lesions were divided into T- and B-types. The percentage of DC in T-type lesions (27.1 +/- 6.8% of total HLA-DR(+) cells) was higher, compared with B-type lesions (10.3 +/- 5.2%) (P < 0.01). Within the DC population, the percentages of CD1a (Langerhans cell type) and CD123 (probably plasmacytoid DC type) did not differ significantly between the groups (P > 0.05). However, the percentage of mature DC (CD83(+)) was significantly higher in T-type periapical lesions (P < 0.05).

CONCLUSIONS

Flow cytometry and immunocytochemistry are suitable methods for phenotypic analysis of APC after their isolation from human periapical lesions. APC, that were phenotypically heterogeneous, constituted a significant component of infiltrating cells. Lesions with the predominance of T cells were characterized by a higher proportion of mature DC (HLA-DR(+)CD83(+) cells) than lesions with predominance of B cells/plasma cells.

Liver antioxidant capacity in the early phase of acute paracetamol-induced liver injury in mice

The aim of our study was to investigate the relationship between liver antioxidant capacity and hepatic injury in the early phase of acute paracetamol intoxication in mice. Male Swiss mice were divided into groups: (1) control, that received saline, (2) paracetamol-treated group (300 mg/kg intraperitoneally). Animals were sacrificed 6, 24 and 48 h after treatment. Oxidative stress parameters were determined in blood and liver samples spectrophotometrically. Liver malondialdehyde and nitrite + nitrate level were significantly increased 6 h after paracetamol administration in comparison with control group (p < 0.05). Paracetamol induced a significant reduction in total liver superoxide dismutase (SOD) and copper/zinc SOD activity at all time intervals (p < 0.01). However, manganese SOD activity was significantly increased within 6 h (p < 0.01), while its activity progressively declined 24 and 48 h after paracetamol administration in comparison with control group (p < 0.01). Content of sulfhydryl groups in the liver was increased 24 h after paracetamol administration (p < 0.05), while its level was decreased within next 24 h when compared to control animals (p < 0.01). Our data showed that liver antioxidant capacity increases in first 24 h of paracetamol-induced liver injury were in correlation with manganese SOD activity and increase in level of sulfhydryl groups.

Immunomodulatory effect of xylazine, an alpha(2) adrenergic agonist, on rat spleen cells in culture

Xylazine is an adrenergic alpha(2) agonist, which is used in veterinary medicine as a sedative and anesthetic agent. In this work we found that xylazine administered in vivo at a dose of 2.5 mg/kg enhanced spleen cell proliferation and interleukin 2 (IL-2) production in cultures stimulated with concanavalin A (Con A), whereas doses of 10 and 25 mg/kg were inhibitory. A similar stimulatory (10 microM) and inhibitory (50-500 microM) effect on splenocyte proliferation and IL-2 production was observed in vitro. Clonidine, another alpha(2) adrenergic agonist, only had a stimulatory proliferative effect on splenocytes. Yohimbine, an alpha(2) adrenergic antagonist, abrogated the stimulatory action of both clonidine and xylazine, but not the suppressive proliferative activity of xylazine in vitro. The inhibited proliferation of splenocytes to Con A correlated with increased apoptosis of T cells. The apoptosis was not blocked by yohimbine or antibodies to Fas and Fas-L. N-Nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase, enhanced proliferation of splenocytes to Con A, partly abrogated the inhibitory effect of xylazine in the proliferation assay, and, only at high concentration (1000 microM), partly suppressed apoptosis of lymphocytes. The enhancing effect of L-NAME on the Con A-induced proliferation of splenocytes correlated with decreased NO production. However, decreased NO production observed in cultures with xylazine was followed by both decreased lymphocyte proliferation and apoptosis. Cumulatively, these results suggest that the immunosuppressive properties of xylazine on splenocytes in vitro are due to increased apoptosis of lymphocytes, predominantly involve NO-independent pathways, and are probably independent of its action through alpha(2) adrenoreceptors.

Modulatory effect of 7-thia-8-oxoguanosine on proliferation of rat thymocytes in vitro stimulated with concanavalin A

7-thia-8-oxoguanosine (immunosine) is a guanosine analogue showing immunostimulatory activity on different components of the immune system, including B lymphocytes, natural killer cells and macrophages. However, little is known about its effect on T-cell functions. In this work it was demonstrated that immunosine at concentrations between 10 microM and 1 mM stimulated proliferation of rat thymocytes in vitro triggered by suboptimal concentrations of concanavalin A (Con A). The effect correlated with increased interleukin 2 (IL-2) production, upregulation of the IL-2 receptor alpha (IL-2Ralpha) expression and decreased apoptosis of thymocytes in comparison to the effect of Con A alone.

[The role of oxidative stress in alcoholic liver injury]

INTRODUCTION

Oxidative stress plays an important role in pathogenesis of alcoholic liver injury. The main source of free oxygen species is cytochrome P450-dependent monooxygenase, which can be induced by ethanol. ROLE OF CYTOCHROME P4502E1 IN ETHANOL-INDUCED OXIDATIVE STRESS: Reactive oxygen species produced by this enzyme are more important in intracellular oxidative damage compared to species derived from activated phagocytes. Free radicals lead to lipid peroxidation, enzymatic inactivation and protein oxidation. ROLE OF MITOCHONDRIA IN ALCOHOL-INDUCED OXIDATIVE STRESS. Production of mitochondrial reactive oxygen species is increased, and glutathione content is decreased in chronically ethanol-fed animals. Oxidative stress in mitochondria leads to mitochondrial DNA damage and has a dual effect on apoptosis. ROLE OF KUPFFER CELLS IN ALCOHOL-INDUCED LIVER INJURY: Chronic ethanol consumption is associated with increased release of endotoxin from gut lumen into portal circulation. Endotoxin activates Kupffer cells, which then release proinflammatory cytokines and oxidants. ROLE OF NEUTROPHILS IN ALCOHOL-INDUCED LIVER INJURY: Alcoholic liver injury leads to the accumulation of neutrophils, which release reactive oxygen species and lysosomal enzymes and contribute to hepatocyte damage and necrosis. ROLE OF NITRIC OXIDE IN ALCOHOL-INDUCED OXIDATIVE STRESS: High amounts of nitric oxide contribute to the oxidative damage, mainly by generating peroxynitrites. ROLE OF ANTIOXIDANTS IN ETHANOL-INDUCED OXIDATIVE STRESS: Chronic ethanol consumption is associated with reduced liver glutathione and alpha-tocopherol level and with reduced superoxide dismutase, catalase and glutathione peroxidase activity.

CONCLUSION

Oxidative stress in alcoholic liver disease is a consequence of increased production of oxidants and decreased antioxidant defense in the liver.

Correlation between electrocorticographic and motor phenomena in lindane-induced experimental epilepsy in rats

We report a study on the relation between open-field behavior and electroencephalographic (EEG) changes during lindane-induced seizures in 2-month-old adult male Wistar rats. For chronic EEG recordings and power spectra analysis, 3 electrodes were implanted into the skull. Three groups of animals, (i) saline-injected control (n = 6), (ii) DMSO-treated (n = 6), and (iii) lindane intraperitoneally administered: L(4) (4 mg/kg, n = 10), L(6) (6 mg/kg, n = 11), and L(8) (8 mg/kg, n = 11), were observed for 30 min for the occurrence of convulsive behavior. It was assessed by incidence of motor seizures, and seizure severity grade was determined by a descriptive rating scale (0, no response; 1, head nodding, lower jaw twitching; 2, myoclonic body jerks, bilateral forelimb clonus with full rearing; 3, progression to generalized clonic convulsions followed by tonic extension of fore and hind limbs and tail; 4, status epilepticus). EEG signal and spectral analyses were suitable to describe the dynamics of complex behavioral responses. Incidence and severity of epileptic manifestations, recorded as high voltage spike-wave complexes, polyspikes, sleep-like patterns in EEG, and power spectra changes, were greater in lindane-treated groups in a dose-dependent manner compared with control or DMSO-treated groups. Our results suggest good correlation between lindane-induced epileptiform activity and behavioral changes.

Effect of acute lindane and alcohol intoxication on serum concentration of enzymes and fatty acids in rats

This study examines possible synergistic effects of lindane and ethanol on inducing liver injury and serum fatty acid derangement in adult male Wistar rats. When administered together, ethanol and lindane-induced even more pronounced increase of alanine aminotransferase (165 +/- 10 U/L) and gamma-glutamyltranspeptidase activity (10.3 +/- 0.6 U/L) than after isolated administration of either substance. In addition, separate administration of lindane and ethanol was followed by a significant decrease of linoleic acid level in the serum (301 +/- 38 mg/L, 276 +/- 35 mg/L vs. 416 +/- 48 mg/L). However, when ethanol administration was followed by lindane injection, serum linoleic acid was at the similar level found in the control group (516 +/- 62 mg/L). Ethanol-treated rats that received lindane 30 min after ethanol administration have shown a marked increase of palmitic (421 +/- 27 mg/L) and linolic acid level (43 +/- 5 mg/L) in comparison with rats that have been treated only with ethanol (316+/-26 mg/L for palmitic and 32 +/- 2 mg/L for linolic acid) or lindane (295 +/- 26 mg/L for palmitic and 301 +/- 38 mg/L for linolic acid). Linolic acid level was significantly greater in comparison with control group (29 +/- 1 mg/L). In conclusion, this study found enough evidence to support the hypothesis that acute ethanol intoxication potentiates lindane-induced liver injury and enhances lipid derangement.

A monoclonal antibody to the rat Crry/p65 antigen, a complement regulatory membrane protein, stimulates adhesion and proliferation of thymocytes

A murine monoclonal antibody (mAb), 3F10, was produced by fusion of spleen cells obtained from mice immunized with a rat cortical thymic epithelial cell line (R-TNC.1) stimulated with interferon-gamma and P3X myeloma cells. 3F10 recognized an antigen expressed both on thymocytes and non-lymphoid cells in the thymus. Flow cytometry showed that 3F10 stained more than 98% thymocytes and 90% R-TNC.1 cells. Immunoprecipitation and Western blot studies demonstrated that 3F10 reacted with molecules of 55000 and 65000 MW from both thymocyte and R-TNC.1 cell lysates. 3F10 recognized the same antigen on Chinese hamster ovary cells transfected with rat Crry as did 5I2 mAb, confirming the specificity of 3F10 mAb for the rat homologue of mouse Crry/p65, a membrane-bound complement regulatory protein. 3F10 mAb induced homotypic aggregation of thymocytes and exhibited an additive effect on the aggregation evoked by phorbol myristate acetate. The aggregation was dependent on active cell metabolism, intact cytoskeleton, divalent cations and activation of protein phosphatases 1 and 2A (as assessed by use of okadaic acid). In contrast, H-7, HA1004 and genistein partially inhibited, whereas staurosporine potentiated the aggregation of thymocytes triggered by 3F10. 3F10 mAb also stimulated binding of thymocytes to the R-TNC.1 line. Both homotypic and heterotypic adhesive interactions are mediated by leucocyte function-associated antigen-1 (LFA-1). In addition, 3F10 stimulated proliferation of thymocytes induced by suboptimal concentrations of concanavalin A. These data suggest that rat Crry/p65 might be involved in the regulation of both cell adhesion and activation of thymocytes. This is a novel, non-complement-dependent function of Crry/p65.

[The growth hormone axis and insulin-like growth factors]

INTRODUCTION

Growth is regulated by the interaction of environmental signals with endogenous neuroendocrine responses to the genetic programs that determine the body plan. The insulin-like growth factors (IGFs) are integral components of multiple systems controlling both growth and metabolism.

THE IGF SYSTEM

The IGF system is thouht to be more complex than other endocrine systems, as genes for six IGF-binding proteins (IGFBPs) have been identified so far. The IGFs play a critical role in both cell cycle control and apoptosis, two functions involved in regulation of tumorigenesis. Insulin-like growth factor-I (IGF-I) is essential for normal growth. Confirmation of the significance of IGF-I in human physiology was obtained by the discovery of a patient with intrauterine growth retardation and postnatal growth failure associated with a mutation in the IGF-I gene.

STAGES OF EVOLUTION OF THE SOMATOMEDIN HYPOTHESIS

The original somatomedin hypothesis postulated that somatic growth was regulated by growth hormone's (GH's) stimulation of hepatic IGF-I production, with IGF-I acting in an endocrine fashion to promote growth. The dual effector theory proposed an alternative view, involving direct effects by GH on peripheral tissues not mediated by IGF-I and GH-stimulated local IGF-I production for autocrine/paracrine action. It is now clear that GH stimulates the formation of ternary IGF binding complex, which stabilizes IGF-I in the serum.

[The role of oxidative/nitrosative stress in pathogenesis of paracetamol-induced toxic hepatitis]

INTRODUCTION

Paracetamol is an effective analgesic/antipyretic drug when used at therapeutic doses. However, the overdose of paracetamol can cause severe liver injury and liver necrosis. The mechanism of paracetamol-induced liver injury is still not completely understood. Reactive metabolite formation, depletion of glutathione and alkylation of proteins are the triggers of inhibition of mitochondrial respiration, adenosine triphosphate depletion and mitochondrial oxidant stress leading to hepatocellular necrosis. ROLE OF OXIDATIVE STRESS IN PARACETAMOL-INDUCED LIVER INJURY: The importance of oxidative stress in paracetamol hepatotoxicity is controversial. Paracetamol-induced liver injury cause the formation of reactive oxygen species. The potent sources of reactive oxygen are mitochondria, neutrophils. Kupffer cells and the enzyme xatnine oxidase. Free radicals lead to lipid peroxidation, enzymatic inactivation and protein oxidation. ROLE OF MITOCHONDRIA IN PARACETAMOL-INDUCED OXIDATIVE STRESS: The production of mitochondrial reactive oxygen species is increased, and the glutathione content is decreased in paracetamol overdose. Oxidative stress in mitochondria leads to mitochondrial dysfunction with adenosine triphosphate depletion, increase mitochondrial permeability transition, deoxyribonucleic acid fragmentation which contribute to the development of hepatocellular necrosis in the liver after paracetamol overdose. ROLE OF KUPFFER CELLS IN PARACETAMOL-INDUCED LIVER INJURY: Paracetamol activates Kupffer cells, which then release numerous cytokines and signalling molecules, including nitric oxide and superoxide. Kupffer cells are important in peroxynitrite formation. On the other hand, the activated Kupffer cells release anti-inflammatory cytokines. ROLE OF NEUTROPHILS IN PARACETAMOL-INDUCED LIVER INJURY: Paracetamol-induced liver injury leads to the accumulation of neutrophils, which release lysosomal enzymes and generate superoxide anion radicals through the enzyme nicotinamide adenine dinucleotide phosphate oxidase. Hydrogen peroxide, which is influenced by the neutrophil-derived enzyme myeloperoxidase, generates hypochlorus acid as a potent oxidant. ROLE OF PEROXYNITRITE IN PARACETAMOL-INDUCED OXIDATIVE STRESS: Superoxide can react with nitric oxide to form peroxynitrite, as a potent oxidant. Nitrotyrosine is formed by the reaction of tyrosine with peroxynitrite in paracetamol hepatotoxicity.

CONCLUSION

Overdose of paracetamol may produce severe liver injury with hepatocellular necrosis. The most important mechanisms of cell injury are metabolic activation of paracetamol, glutathione depletion, alkylation of proteins, especially mitochondrial proteins, and formation of reactive oxygen/nitrogen species.

The correlation between lipid peroxidation in different brain regions and the severity of lindane-induced seizures in rats

The aim of this study was to investigate the dynamics of lipid peroxidation and the possible correlation between lipid peroxidation in different brain regions and behavioral manifestations in lindane-induced seizures in rats. Male Wistar rats were divided into the following groups: 1. control, saline-treated group; 2. dimethylsulfoxide (DMSO)-treated group; 3. lindane-treated group (8 mg/kg), intraperitoneally. Animals were sacrificed 0.5 or 4 h after treatment and the malondialdehyde level and superoxide dismutase (SOD) activity were determined in various brain regions spectrophotometrically. Behavioral changes were classified according to the descriptive scale (0--no response, 1--head nodding, lower jaw twitching; 2--myoclonic body jerks, bilateral forelimb clonus with full rearing; 3--progression to generalized clonic convulsions followed by tonic extension of fore- and hind limbs and tail; 4--status epilepticus). A significant rise in the malondialdehyde level was detected in the cerebral cortex, hippocampus, and thalamus of lindane-treated animals 0.5 and 4 h after administration (P < 0.05). SOD activity (total and mitochondrial) was significantly decreased in the hippocampus and the cortex of lindane-treated animals at both time points (P < 0.05). An initial fall in SOD activity was detected in the thalamus 4 h after lindane administration (P < 0.05). A positive correlation between seizure severity and the malondialdehyde level was found in the hippocampus at both time points (P < 0.01). These results suggest that lipid peroxidation may contribute to the neurotoxic effects of lindane in early acute lindane intoxication and that behavioral manifestations correlate with lipid peroxidation in the hippocampus of lindane-treated rats.

Immunomodulatory Activity of IL-27 in Human Periapical Lesions

IL-27, a cytokine with pro-inflammatory and anti-inflammatory properties, is a new member of the IL-6/IL-12 family, whose function in periapical lesions is unknown. We hypothesized that the production of IL-27 and its effect depend upon the type of immune/inflammatory response and clinical presentation of periapical lesions. We tested this hypothesis by studying the expression and function of IL-27 in human periapical lesions, both in situ and in culture. Immunohistochemistry demonstrated the strongest expression of IL-27 by endothelial cells and mononuclear phagocytes. Its production by periapical lesion mononuclear cells (PL-MNC), especially in symptomatic lesions, was significantly higher compared with that in peripheral blood MNC and correlated with the frequency of CD14+ and CD3+ cells. Exogenous IL-27 stimulated Th1 and down-regulated Th17 cytokine production by PL-MNC from symptomatic lesions, but down-regulated Th1 and Th2 responses in asymptomatic lesions. These findings suggest that IL-27 is an immunomodulatory cytokine in periapical lesions, with complex biological effects.

Moderate body hypothermia alleviates behavioral and EEG manifestations of audiogenic seizures in metaphit-treated rats

We investigated the effects of hypothermia on the incidence and EEG signs of audiogenic seizures in rats treated with metaphit (1-[1(3isothiocyanatophenyl)-cyclohexyl] piperidine), an experimental model of generalized reflex epilepsy. After i.p. injection with metaphit (10 mg/kg) Wistar rats were exposed to audiogenic stimulation at hourly intervals during the time course of the experiment. After intermittent use of an ice pack 8 h after the metaphit treatment, when seizure was fully developed, the body temperature was reduced to 30 +/- 0.5 degrees C in one half of the rats, and maintained at 37 +/- 0.5 degrees C in the other half. Saline-injected rats served as a control group. In the hypothermia group, the incidence of audiogenic seizures induced by metaphit was completely suppressed during the 3 consecutive testing times, while no signs of epileptiform activity were noted in EEG tracings. The termination of hypothermic treatment resulted in the recovery of seizure susceptibility, and during audiogenic stimulation, bursts of spiking activity were recorded in the EEGs of metaphit-treated rats. These findings indicate that moderate body hypothermia is an effective anticonvulsant treatment for audiogenic seizures in metaphit-treated rats.

[Inflammatory process in atherogenesis: new facts about old flame]

INTRODUCTION. Atherosclerosis is a progressive, multifactorial, diffuse, multisystemic, chronic, inflammatory disease, which is manifested by disorders of vascular, immune and metabolic system. Pathogenesis of this disease is not fully understood. Endothelial Dysfunction and Inflammatory Process. Endothelial dysfunction is recognized as the crucial step in atherogenesis. A lot of studies have confirmed the involvement of various mediators of inflammation in initial proatherogenic processes, such as the upregulation of adhesion molecules on endothelial cells, binding of low density lipoproteins to endothelium, activation of macrophages and proliferation of vascular smooth muscle cells. Fatty stain and Inflammatory Process. Fatty stain consists of foam cell accumulation. After foam cell formation, mediators of inflammation initiate a series ofintracellular events that include the induction of inflammatory cytokines. Thus, a vicious circle of inflammation, modification of lipoproteins and further inflammation can be maintained in the artery. Transitory Lesion and Inflammatory Process. In transitory lesion intensive phagocytosis of oxidized low density lipoproteins additionally activates monocytes and macrophages and consequently facilitates and exacerbates the inflammatory response. Fibrotic Plaque and Inflammatory Process. Inflammatory process, matrix-degrading metalloproteinases activity, platelets aggregation and smooth muscle cells proliferation play a central role in development of fibrotic plaque. Complex Lesion and Inflammatory Process. It has been shown that inflammation is closely related to the development of atherosclerotic plaque rupture.

CONCLUSION

The contribution of inflammatory process has become increasingly meaningful in understanding the initiation, progression and clinical manifestations ofatherosclerosis.

Immunosine (7-thia-8-oxoguanosine) acts as a cofactor for proliferation of T cells

Immunosine (7-thia-8-oxoguanosine) is a novel guanosine analogue showing immunostimulatory activity both in vivo and in vitro. This compound acts on different components of the immune system including B cells, natural killer (NK) cells and antigen-presenting cells (APC). However, its influence on functions of T cells is poorly understood. In this work we studied the effect of immunosine on proliferation of total rat splenocytes and purified T cells triggered by different mitogens and the mechanisms involved. The results demonstrate that immunosine significantly stimulates proliferation of T cells. The effect was dose-dependent and also depended on concentrations of specific stimulators. Maximal stimulation was seen using 250 microM immunosine. The stimulatory effect of immunosine on lymphocyte proliferation triggered by Concanavalin A (Con A) correlated with increased interleukin 2 (IL-2) production and upregulation of the IL-2 receptor alpha (IL-2Ralpha) expression. The dependency of T-cell proliferation on IL-2/IL-2R was confirmed using neutralizing anti-IL-2Ralpha monoclonal antibodies (mAbs). Higher concentrations of immunosine in the presence of optimal concentrations of Con A (5 microg/mL) inhibited proliferation of T cells. A similar stimulatory effect of immunosine on proliferation of purified T cells and IL-2 production was observed using an anti-T-cell receptor (TCR) mAb and a combination of anti-TCR mAb and IL-2. However, the guanosine analogue did not significantly modulate proliferation of T cells triggered by IL-2 alone. When the combination of phorbol myristate acetate (PMA) and ionomycin was used for T-cell stimulation different results were obtained. Under lower cell stimulation immunosine significantly potentiated T-cell proliferation, expression of IL-2Ralpha and IL-2 production. In the presence of suboptimal stimulation the compound stimulated T-cell proliferation and IL-2Ralpha expression, whereas under maximal stimulation an enhancing effect on IL-2 production was seen. Since direct stimulatory effect of immunosine on T-cell growth in culture was rather weak it can be postulated that the compound acts as a cofactor for T-lymphocyte proliferation.

Influence of aging on ethanol-induced oxidative stress in digestive tract of rats

Aging and ethanol induce oxidative stress due to increased prooxidant production and decreased antioxidative capacity. The aim was to investigate the influence of aging on oxidative stress in liver, stomach and pancreas in acute ethanol intoxication. Adult (3 months) and old (18 months) male Wistar rats were divided into the following groups: control (control group rats aged 3 months (C3) and control group rats aged 18 months (C18)) and ethanol-treated groups (ethanol-treated 3-month-old rats (E3) and ethanol-treated 18-month-old rats (E18)). Ethanol was administered in five doses of 2 g/kg at 12-h intervals by orogastric tube. Tissue samples were collected for the determination of oxidative stress parameters. Malondialdehyde (MDA) concentration was increased in all the experimental groups and investigated organs versus C3 group ( p < 0.01). The highest MDA level was observed in the stomach in E18 group when compared with C18 and E3 groups ( p < 0.01). Activity of total superoxide dismutase (SOD) and its isoenzymes (copper-/zinc-SOD and manganese-SOD) in E18 group was significantly decreased when compared with E3 and C18 groups ( p < 0.01). Nitrates and nitrites (NO x ) concentration was increased in stomach and pancreas for all the groups when compared with C3 group ( p < 0.01). Hepatic, gastric and pancreatic NO x level was significantly increased in E18 group when compared with E3 group ( p < 0.01). Moreover, level of NO x in liver and pancreas in E18 group was significantly increased when compared with C18 group ( p < 0.01). Aging potentiates ethanol-induced oxidative stress in liver, stomach and pancreas due to increased lipid peroxidation and nitrosative stress and decreased antioxidative tissue capacity.

[The role of oxidative stress in the pathogenesis of pulmonary emphysema]

OXIDATIVE PULMONARY DAMAGE: The pathogenesis of pulmonary emphysema is incompletely understood. Nearly 90% of all patients with chronic obstructive pulmonary diseases are smokers. Cigarette smoke is a rich source of oxidants. Oxidative stress increases oxidant generation, which cannot be neutralized with antioxidant defense mechanisms. Lipids, proteins and deoxyribonucleic acid are components of the cell that are most sensitive to oxidative damage. Oxygen radicals can modify amino acid side chains, form protein aggregates, cleave peptide bonds, and make proteins more susceptible to proteolytic degradation. It has been shown that neutrophils have a principal effector role in pulmonary tissue damage. Neutrophil elastase can damage air spaces by degrading elastin, and a variety of extracellular membrane proteins, proteoglycans, and glycoproteins. Neutrophil elastase can also stimulate inflammation by increasing interleukin-8 synthesis. Additionally, neutrophil elastase can activate or inactivate inhibitors of neutrophil collagenase, and secretory leukoprotease proteinase inhibitor. Apart from neutrophils, oxidative stress causes activation of other phagocytes and severe inflammatory response ensues. LIPID PEROXILATION AND PULMONARY EMPHYSEMA: Except protein oxidation and lipid peroxidation, oxidants may disturb signal transmission in the cells, as well as normal cell membrane function and function of organelles. Modified structure of deoxyribonucleic acid may cause mutations, which in absence of repairation enzyme activity lead to cell injury. IRON AND OXIDATIVE STRESS: Iron metabolism is also important in the development of pulmonary emphysema due to its role in production of some oxidants.

[The role of psychic factors in the pathogenesis of bronchial asthma]

Bronchial asthma is a chronic inflammatory disorder of the airways in which many cells play a role, in particular mast cells, eosinophils, neutrophils, T-lymphocytes and epithelial cells. In susceptible individuals this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness and cough, particularly at night and/or in the early morning. These symptoms are usually associated with variable and extensive limitations of airflow in the bronchi reversible spontaneously or by treatment. It has been shown that restrain of the effectors of stress response participate in the pathogenesis of bronchial asthma. Anger that is not expressed and frustrations may activate the limbic stress pathway. Thus, the released neurotransmitters followed by excitation thus causing psychogenic (mental or emotional) stress. It is also known that emotional stress may be responsible for the exacerbation of asthma. Namely, pronounced emotions cause hyperventilation and hypocapnia inducing bronchospasm. Certain psychological personality features are related to adaptive or inadequate body response to numerous life events. Thus, until the beginning of the last century, bronchial asthma was referred to as asthma nervosa, because clinicians clearly observed the psychological profile of patients with predominant fear of asphyxia and recurrent attacks of paroxysmal dyspnoea. Besides, increased sensitivity, repression of aggressive feelings and expressive empathy have been identified as the most frequent psychological characteristics of asthmatic patients. However, scientists are still far from a full understanding of bronchial asthma pathogenesis. The contribution of psychic factors has become meaningful in the understanding of the development of bronchial asthma. Having in mind that in the majority of patients asthma is a lifelong condition, there is a hope that further investigations of bronchial asthma psychogenesis will improve prevention and treatment of this disease.

Bidirectional interactions between thymocytes and thymic epithelial cell lines in vitro

In vitro interactions of thymocytes and thymocyte hybridomas with cortical (R-TNC.1) and medullary (TE-R 2.5) rat thymic epithelial-cell (TEC) lines were studied. It was found that the cortical line had better adhesion capability. It bound exclusively immature CD4+ CD8+ alpha beta TCRlo thymocytes, induced apoptosis of a subset of these cells, and stimulated proliferation of the BWRT 1 (CD4- CD8- alpha beta TCR-) hybridoma. The medullary line bound both immature and mature thymocytes, decreased their apoptosis, and induced apoptosis of the BWRT 8 (CD4+ CD8lo alpha beta TCRhi) hybridoma. Thymocyte differently modulated cytokine production by TEC lines, upregulating the secretion of IL-1 by R-TNC.1 and IL-6 by TE-R 2.5 cells. Finally, coculture of thymocytes with TEC lines resulted in different patterns of protein-tyrosine phosphorylation in thymocytes. These results show the existence of mutual bidirectional interactions between thymocytes and TEC lines in vitro, but these processes differed depending on phenotypic characteristics and origin of TEC lines used.

Comparison of signaling pathways involved in apoptosis of a thymocyte hybridoma triggered by a rat thymic medullary epithelial cell line, dexamethasone or T-cell receptor cross-linking

Using an in vitro co-culture assay we found that a rat medullary thymic epithelial cell (TEC) line (TE-R2.5) induces apoptosis of the BWRT8 thymocyte hybridoma (TH) (CD4(hi)CD8(low) alphabetaTCR(hi)). TH apoptosis induced by this TEC line was predominantly mediated by direct cell-cell contacts and was potentiated by cross-linking of the T cell receptor (TCR) by R73 monoclonal antibody (mAb). Dexamethasone (Dx) also triggered TH apoptosis but inhibited death of these cells induced by TE-R2.5 cells or immobilized R73 mAb. The TEC-induced apoptosis was independent of the LFA-1/ICAM-1 interaction but partly depended on a novel 29 kDa molecule expressed on TE-R2.5 cells. All three types of TH apoptosis were followed by the cleavage of poly-(ADP-ribose)-polymerase and were blocked by a caspase inhibitor Z-Val-Ala-Asp(OMe)-CH(2)F.PKC stimulation by phorbol myristate acetate interfered with the TH apoptosis induced by TE-R2.5 and Dx, but did not modulate the effect of R73 mAb. On the contrary, inhibition of calcineurin with cyclosporine A did not influence the apoptosis induced by TE-R2.5 and Dx, but completely prevented the R73-triggered TH cell death. The TE-R2.5-mediated BWRT8 apoptosis was suppressed by Na-orthovanadate, an inhibitor of protein tyrosine phosphatases (PTP) as well as by genistein, a protein tyrosine kinase (PTK) inhibitor, while both compounds potentiated the effect of Dx. Blocking PTP, but not PTK decreased the proapoptotic effect of R73 mAb. These results, including those using a BWRT8 subclone (BWRT8-MDP.2) which is resistant to TCR-triggered apoptosis, but sensitive to apoptosis stimulated by TE-R2.5 and Dx, indicate that TE-R2.5-induced TH apoptosis in our model is different from apoptosis in other TEC co-culture models, published so far.

[Behavioral and electroencephalographic effects of delta sleep inducing peptide and its analogue on metaphit-induced audiogenic seizures in rats]

INTRODUCTION

Delta sleep inducing peptide (DSIP) is well known natural somnogenic peptide that has many other physiological functions. DSIP analogues representing hepta- and octapeptides (also known as long) as well as tetrapeptide (termed short, used in our experiments) were synthesized with a view to evaluate the peptide specificity in sleep. The effects of DSIP and its analogue DSIP1-4 on metaphit 1-[1(3-isothiocyanatophenylciclohexyl)-piperidine] induced audiogenic seizures were evaluated in rats.

METHODS

Male Wistar albino rats were divided into 4 groups: 1. Saline; 2. Metaphit; 3. Metaphit + DSIP, and 4. Metaphit + DSIP1-4. To examine the blocking effects of DSIP and its analogue on fully developed metaphit seizures, the last two groups were injected after the 8th audiogenic testing. Animals were injected with metaphit (10 mg/kg) intraperitoneally (i.p.) and exposed to sound stimulation (100 +/- 3 dB, 60 s) at hourly intervals. The incidence and severity (running, clonus and tonus) of seizures were analyzed. For electroencephalographic (EEG) recordings, three gold-plated electrodes were used. Convulsive behavior was assessed by incidence of motor seizure and by seizure severity grade, determined by descriptive rating scale ranging from 0 to 3: 0--no response, 1--wild running only; 2--wild running followed by clonic seizures of all four limbs with body rollover; 3--wild running progressing to generalized clonic convulsions followed by tonic extension of fore- and hind legs and tail. Sound onset, seizure events, and sound offset, along with the animal's behavior (convulsive or other) were characterized with EEG changes.

RESULTS

In most animals, the administration of metaphit resulted in electroencephalographic abnormalities, elicited epileptiform activity in the form of spikes, polyspikes and spike-wave complexes. Maximum incidence and severity of metaphit convulsions occurred 8 h after the injection (9/12, 75%), then abated gradually and disappeared 30 h later. Both DSIP and DSIP1-4 significantly increased the power spectra of d waves and decreased the incidence of seizures, mean seizure grade and tonic component of metaphit-induced convulsions.

DISCUSSION

Metaphit has been shown to induce audiogenic seizures after systemic and intracerebroventricular administration and to be truly epileptic in small rodents, although about 8 h after metaphit administration, the power spectra increased and was more intense in the period of sound onset and seizure events. Taken together, DSIP makes an optimal ratio between inhibitory and excitatory amino acid neurotransmitters and may represent one of the endogenous control systems of the brain, thus exerting the protective effect against the seizures. The results obtained throughout the present study corroborate and broaden the data on prolonged antiepileptic DSIP effect.

CONCLUSION

The results of the present study strongly suggest that treatment of adult rats with DSIP and its analogue DSIP1-4 should be considered as potential natural antiepileptics.

The relationship between atherosclerosis and pulmonary emphysema

INTRODUCTION

The etiopathogenesis of atherosclerosis and subsequent pulmonary emphysema has not been fully elucidated.

EXPERIMENTAL STUDIES

Foam cells are of great importance in the development of these diseases. It is known that local cytokine secretion and modification of native lipoprotein particles, which are internalized by the vascular and alveolar macrophages via the scavenger receptors on the surfaces of these cells, lead to the formation of foam cells. Thus, the exacerbation of local inflammatory process in the vascular and lung tissue ensues due to a generation of reactive oxygen species, resulting in further lipoprotein modification and cytokine production. Accumulating evidence suggests that oxidants may facilitate the inflammatory response by impairing antiprotease function, directly attacking vascular and lung matrix proteins and by inactivating enzymes involved in elastin synthesis and vascular and lung repair.

CLINICAL STUDIES

Cigarette smoke is recognized as a rich source of oxidants. Nearly 90% of all patients with chronic obstructive pulmonary disease are smokers. The process of atherogenesis is also influenced by tobacco smoke.

CONCLUSION

The role of vascular and alveolar macrophages has become increasingly important in understanding the development of atherosclerosis and resulting pulmonary emphysema.

Dose-dependent anticonvulsive effect of ethanol on lindane-induced seizures in rats

Chronic ethanol consumption is a major risk factor for epilepsy, and seizures frequently occur during the withdrawal period. The aim of our study was to investigate effects of ethanol on lindane-induced seizures in rats. Male Wistar rats were injected i.p. with one of the following 5 treatments: (i) saline, (ii) dimethylsulfoxide, (iii) lindane (8 mg/kg) (L), (iv) ethanol in doses of 0.5 g/kg (E(0.5)), 1 g/kg (E(1)), and 2 g/kg (E(2)), and (v) groups that received ethanol 30 min before lindane (LE(0.5), LE(1), and LE(2)). Behavioral changes were described by using a descriptive scale as follows: 0, no response; 1, head nodding, lower jaw twitching; 2, myoclonic body jerks, bilateral forelimb clonus; 3, generalized tonic-clonic convulsions; 4, status epilepticus. The incidence of convulsions in the LE(2) group was significantly lower than the incidence in the L (p < 0.01) and LE(0.5) groups (p < 0.05). The median grade of convulsive behavior was significantly lower in the LE(2) (p < 0.01) and LE(1) groups (p < 0.05) compared with the L group. Latencies to the first seizure response were not significantly different among groups. ED50 of ethanol was 1.40 (1.19-1.65). Our findings suggest that ethanol decreased severity and incidence of lindane-induced seizures in a dose-dependent manner.