The role of oxygen in thymocyte apoptosis

Signals generated by T cell receptor (TCR) cross-linking (or phorbol 12-myristate-13-acetate + Ca²⁺ ionophore), glucocorticoids or ionizing radiation all stimulate apoptotic cell death in thymocytes by signals that are initially distinct from each other. However, when these stimuli were administered to thymocyte cultures that were maintained under an atmosphere containing less than 20 ppm oxygen as opposed to one that contained 18.5 % molecular oxygen, cell death was inhibited or abrogated, suggesting that the induction of death by all three different stimuli depend on the presence of molecular oxygen. Studies of the effects of the cysteine analog N-acetyl cysteine (NAC) with normal thymocytes demonstrated that this antioxidant inhibited the induction of death by each of the different stimuli in a manner that paralleled anaerobiosis. Furthermore, studies with thymocytes demonstrated that the induction of nur77, a gene shown to be involved in thymocyte apoptosis signaled through the TCR or its surrogates, is not inhibited by NAC or dependent upon molecular oxygen. The possible implications for negative selection of NAC-mediated inhibition of TCR-signaled thymocyte cell death was examined in thymic organ culture. Treatment of these cultures with NAC provided significant protection against staphylococcal enterotoxin B-mediated deletion of Vβ8-expressing thymocytes.     

Oxidative stress and apoptosis in HIV infection: a role for plant-derived metabolites with synergistic antioxidant activity

The cascade of events resulting from ‘oxidative stress’ is markedly similar to that which can initiate apoptosis, a possible mechanism of immune-cell loss in patients with HIV infection and AIDS. Since primary and secondary metabolites found in plants can act as synergistic antioxidants, and can prevent oxidation-induced cell death, Howard Greenspan and Okezie Aruoma ask whether of not these compounds can be useful in inhibiting viral activation and the death of immune cells in HIV/AIDS.     

Neutrophil-mediated cytotoxicity triggered by immune complexes: the role of reactive oxygen metabolites.

Normal human neutrophils triggered by precipitating immune complexes (IC), soluble IC (sIC) or heat-aggregated IgG (HAIgG) displayed low levels of cytotoxicity towards nonsensitized target cells. Catalase, but not heated catalase, completely impaired this nonspecific cytotoxicity (NSC), suggesting a key role for hydrogen peroxide (H2O2) in the lysis of target cells. Superoxide dismutase (SOD) and certain HO. and 1O2 scavengers were unable to exert significant effects. Three haem-enzyme inhibitors, sodium azide, sodium cyanide and 3-amino-1,2,4-triazole did not decrease neutrophil NSC, but markedly enhanced it. This data suggest that the mechanism involved was not dependent upon myeloperoxidase (MPO). The analysis of neutrophil-mediated ADCC indicates that oxygen-dependent but MPO-independent mechanisms appeared to be operative in this system. It was also found that the microfilament disrupting agents, cytochalasin B (CB) and dihydrocytochalasin B (dhCB), as well as the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), significantly enhanced NSC. In contrast, these compounds partially inhibited ADCC. This cytotoxic system provides a suitable model to study events that may occur during the course of immune complex diseases and also permits the evaluation of alternative lytic mechanisms triggered through neutrophil Fc gamma receptors.     

几种反应性氧代谢物逆转剂免疫佐剂作用的比较

目的 分析比较硫普罗宁(TIP)、还原型谷胱甘肽(GSH)、二氢氯组胺(DHT)3种反应性氧代谢物(ROM)逆转剂抗白血病细胞免疫治疗中的增效作用.方法 在K562细胞、NK细胞的混合培养系中分别加入单核细胞和白细胞介素-2,然后分别加入TIP、GSH、DHT,观察ROM水平及K562细胞抑制率(KIR)的变化.结果 加入E/MO=10/2、10/5、10/10三种浓度的MO,ROM水平分别为(389.79±43.83)U/L,(456.74±42.77)U/L,(601.42±21.92)U/L,KIR分别为82.36%,81.36%,48.09%:加入TIP、GSH或DHT后,当E/MO=10/2时,ROM水平从(389.79±43.83)U/L,分别减至(-1.20±60.70)U/L、(-3.58±9.49)U/L和(50.21 4-22.4)U/L(P＜0.05),随着TIP、GSH或DHT浓度的增加ROM水平逐渐减少,KIR从82.53%分别升至96.09%、96.39%和94.64%(P＜0.05).结论 TIP、GSH逆转ROM的效应强于DHT,提高NK细胞对K562的抑制率,其效应强度与DHT相似,但毒副作用轻微,两者均可能成为更理想的抗白血病的免疫佐剂.     

Anti-inflammatory and antipyretic effects of boldine

Boldine, and antioxidant alkaloid isolated fromPeumus boldus, exhibits a dose-dependent anti-inflammatory activity in the carrageenan-induced guinea pig paw edema test with an oral ED₅₀ of 34 mg/kg. Boldine also reduces bacterial pyrogen-induced hyperthermia in rabbits to an extent which varied between 51% and 98% at a dose of 60 mg/kg p.o.In vitro studies carried out in rat aortal rings revealed that boldine is an effective inhibitor of prostaglandin biosynthesis, promoting 53% inhibition at 75 M. The latterin vitro effect may be mechanistically linked to the anti-inflammatory and antipyretic effects of boldine exertedin vivo.     

Polyamine oxidase-mediated intraerythrocytic killing of Plasmodium falciparum: evidence against the role of reactive oxygen metabolites.

The polyamines spermine and spermidine, in the presence of polyamine oxidase, were shown to be cytotoxic in vitro to various isolates of Plasmodium falciparum. Neither polyamines nor polyamine oxidase alone was cytotoxic. This cytotoxicity was manifested by the degeneration of the parasites into crisis forms and by the inhibition of methionine incorporation by the parasites. Only 2 to 2.5 h of exposure to the reaction mixture (polyamine oxidase, 100 micrograms/ml; spermine, 1 mM) resulted in parasite death. It was shown that ammonia, hydrogen peroxide, and associated reactive oxygen intermediates produced during the oxidation of polyamines were not the cause of the parasite death observed in this system. This suggested that aldehydes or further breakdown products of these, e.g., acrolein (or both), need to be considered as the effector substances of the polyamine oxidase-mediated killing of P. falciparum.     

Paracoccidioides brasiliensis killing by IFN-gamma, TNF-alpha and GM-CSF activated human neutrophils: role for oxygen metabolites.

Paracoccidioidomycosis, a deep mycosis endemic in Latin America, is a chronic granulomatous disease caused by the fungus Paracoccidioides brasiliensis. Phagocytic cells play a critical role against the fungus and several papers show the effects of activator and suppressive cytokines on macrophage and monocyte functions. However, the studies focusing on polymorphonuclear neutrophils (PMNs) antifungal functions are scarcer. Thus, the objective of the present paper was to assess the capacity of human PMNs to kill virulent P. brasiliensis strain in vitro, before and after priming with different cytokines. Moreover, the involvement of oxygen metabolites in this activity was evaluated. Nonactivated cells failed to exhibit antifungal activity. However, when these cells were IFN-gamma, TNF-alpha or GM-CSF activated, a significative fungicidal activity was detected. This process was significantly inhibited when P. brasiliensis challenge occurred in presence of catalase (CAT - a scavenger of H2O2) and superoxide dismutase (SOD - a scavenger of superoxide anion). From these results it is concluded that cytokines activation is required for P. brasiliensis killing by human PMNs, and that H2O2 and superoxide anion participate as effectors molecules in this process.     

Anti-inflammatory and anti-allergic effects of kefir in a mouse asthma model

Kefir is a microbial symbiont mixture that produces jelly-like grains. As a widely used neutraceutical, however, the therapeutic applicability of kefir is not certain. In order to investigate the pharmacological effects of kefir, we used a mouse asthma model, in which airway inflammation and airway remodeling was produced by ovalbumin sensitization and challenge. BALB/c mice sensitized and challenged to ovalbumin, were treated with kefir (50mg/kg administered by intra-gastric mode) 1h before the ovalbumin challenge. Kefir significantly suppressed ovalbumin-induced airway hyper-responsiveness (AHR) to inhaled methacholine. Intra-gastric administration of kefir significantly inhibited the increase in the total inflammatory cell count induced by ovalbumin, and the eosinophil count in bronchoalveolar lavage fluid (BALF). Type 2 helper T cell (Th2) cytokines, such as interleukin-4 and interleukin-13, and total immunoglobulin E (Ig E) levels, were also reduced to normal levels in bronchoalveolar lavage fluid. Histological studies demonstrate that kefir substantially inhibited ovalbumin-induced eosinophilia in lung tissue and mucus hyper-secretion by goblet cells in the airway. Kefir displayed anti-inflammatory and anti-allergic effects in a mouse asthma model and may possess new therapeutic potential for the treatment of allergic bronchial asthma.     

Anti-inflammatory activity of topical nimesulide gel in various experimental models

1|Objective and Design The anti-inflammatory activity of topically applied nimesulide gel was compared in different experimental models with that of diclofenac and piroxicam gels. 2|Material Wistar albino rats of either sex were used. 3|Treatment In acute models, 50 mg of nimesulide or diclofenac were applied to right hind paws 1 h (carrageenan) or immediately before (formalin) irritant injection (sub-plantar). In adjuvant arthritis, 50 mg of nimesulide, diclofenac or piroxicam were applied daily to injected paws for 14 days. 4|Methods Paw volume was measured by plethysmograph. Statistical significance was tested with Student's t-test. 5|Results In the carrageenan paw odema, topical nimesulide gel exhibited similar anti-inflammatory activity to diclofenac gel, and was more effective than diclofenac gel in formalin-paw odema. In both acute (18h) and chronic (14d) phases of adjuvant arthritis, nimesulide gel was more effective than diclofenac or piroxicam gels. 6|Conclusion Topical nimesulide gel possesses higher anti-inflammatory activity than that of diclofenac or piroxicam gels.     

Comparison of possible carcinogenic estradiol metabolites: effects on proliferation, apoptosis and metastasis of human breast cancer cells

OBJECTIVES: Certain estradiol metabolites may play a pivotal role in breast carcinogenesis. Of special interest are the metabolites 2-hydroxyestradiol (2-OHE2), which can react anti-carcinogenically, and 4-hydroxyestradiol (4-OHE1) and 16a-hydroxyestrone (16-OHE1), which may have procarcinogenic potential. In the present study, we have compared for the first time the effect of these metabolites and their parent substance 17beta-estradiol (E2) on proliferation, apoptosis, apoptosis markers and markers of metastatic property of human breast cancer cells. METHODS: MCF-7 cells (human estrogen-receptor positive metastatic breast cancer cell line) were incubated with the estrogens at concentrations of 0.1-100 nM. Cell proliferation rate was measured by the ATP-assay. Apoptosis was measured by cell death assay and the apoptosis markers cytochrome C, Bcl-2, Fasl and p53 were determined in cell lysates by ELISAs. The markers of metastatic property of the cell line, VEGF and MCP-1 were measured in the cell supernatant by ELISAs. RESULTS: The estrogens E2, 4-OHE2 and 16-OHE1 display a proliferative effect on MCF-7 cells which is accompanied by a down-regulation of apoptosis. Various markers of apoptosis such as Bcl-2, cytochrome C and p53 appear to be involved. No significant effect was found for the metabolite 2-OHE2. VEGF and MCP-1 were up-regulated by E2 and 16-OHE1, whereas 2-OHE2 and 4-OHE2 did not show any effect. CONCLUSIONS: The most potent estrogen regarding proliferation, apoptosis and metastasis of breast cancer cells seems to be estradiol. However, the estradiol metabolites 4-OHE2 and 16-OHE1 elicit similar properties on cell proliferation, apoptosis and metastasis as compared to estradiol but only at higher concentrations. In contrast 2-OHE2 did not show any significant effect on these parameters. Thus, intracellular estradiol metabolism may determine an individual's risk for breast carcinogenesis.     

Trophoblast-mediated spiral artery remodelling: a role for apoptosis

In the first 20 weeks of pregnancy a number of important changes take place in the maternal uterine vasculature. Vascular endothelial and smooth muscle cells are lost from the spiral arteries and are replaced by fetal trophoblast cells. The resulting increase in blood flow to the intervillous space ensures that the fetus receives the nutrients and respiratory gases required for growth. Failure of the vessels to remodel sufficiently is a common feature of pregnancy pathologies such as early pregnancy loss, intrauterine growth restriction and pre-eclampsia. Although there is evidence to suggest that some vascular changes occur prior to trophoblast invasion, it is clear that in the absence of trophoblast invasion the remodelling of the spiral arteries is reduced. The cellular and molecular mechanisms by which trophoblasts influence vessel structure have been little studied. Trophoblasts synthesize and release a plethora of cytokines and growth factors including members of the tumour necrosis factor family such as tumour necrosis factor α, Fas-ligand and tumour necrosis factor-related apoptosis-inducing ligand. Recent studies suggest that these factors may be important in regulating the remodelling process by inducing both endothelial cell and vascular smooth muscle cell apoptosis.     

Anti-inflammatory effects of LY221068 and LY269415

Guanine nucleotides have, besides an activating effect on exocytosis and respiratory burst in permeabilized neutrophils, a modulating effect on some functions in intact neutrophils. We investigated the effect of guanine nucleotides on fMet-Leu-Phe-induced migration of rabbit neutrophils using the Boyden chamber technique. GTP gave a moderate inhibition of fMet-Leu-Phe-induced neutrophil migration. The GTP analogue GTP[S] had a stronger inhibitory effect than GTP. Other nucleotides, such as GDP, GMP, and guanosine were less effective inhibitors than GTP and GTP[S]. Maximal inhibition was achieved at nucleotide concentration of about 40 M; higher concentration gave only little additional inhibition. The inhibitory effect persisted when the nucleotide was removed after pretreatment of the neutrophil with that nucleotide. Guanine nucleotide induced inhibition was not due to an interference with the fMet-Leu-Phe receptor as casein-induced migration was equally inhibited. We recently found that ATP inhibited neutrophil chemotaxis. The results obtained with guanine nucleotides resembles the inhibitory effects of ATP and its analogues. It is conceivable that guanine nucleotide-induced inhibition of neutrophil migration is mediated by an interaction of these nucleotides with purinergic receptors.     

Anti-inflammatory and PG inhibitory effects of phenacetin and acetaminophen

Although acetaminophen and phenacetin do not inhibit PG synthesis when added directly to isolated rat platelets and when given orally, both drugs inhibit carrageenan-induced hindpaw edema — a widely used inflammatory assay method. It does not appear that the anti-inflammatory effects of these non-steroidal drugs (unlike other well-known non-steroidal drugs) can be explained on the basis of PG-synthetase inhibition.     

Anti-inflammatory effects of nedocromil sodium: inhibition of alveolar macrophage function

The IgE-dependent activation of mononuclear phagocytic cells through their capacity to express low affinity IgE receptors (Fc epsilon RII) has been proposed as a mechanism for the development of airways inflammation in allergic asthma. This Fc epsilon RII expression leads to the IgE-dependent production of the potent pro-inflammatory cytokines IL-1 beta and TNF-alpha. Expression by monocytes of Fc epsilon RII is regulated by several cytokines including interleukin-4, gamma- and alpha-interferons, and granulocyte-macrophage and macrophage colony stimulating factors. An anti-inflammatory effect of nedocromil on monocytes has been proposed as a possible mechanism for its anti-asthma activity. We therefore investigated the capacity of nedocromil to modulate mononuclear phagocyte Fc epsilon RII expression and cytokine production. We used an anti-Fc epsilon RII antibody and flow cytometric analysis to assess the capacity of nedocromil to modulate cytokine-induced Fc epsilon RII expression in normals and asthmatics. Monocytes, THP-1 monocyte leukaemia cells, and alveolar macrophages were exposed to varying concentrations of these cytokines for 48 hr at 37 degrees C with or without the additional presence of nedocromil (1-10 microM) and the per cent of monocytes expressing Fc epsilon RII was determined. No changes in Fc epsilon RII expression were observed. Subsequently, we investigated the capacity of nedocromil to affect the capacity of IgE plus anti-IgE complexes, allergen, and LPS (16 hr/37 degrees C) to stimulate IL-1 beta and IL-6 production. No changes were observed when nedocromil was applied concomitant with the stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anti-inflammatory effects of isoacteoside from Abeliophyllum distichum

Abstract

Isoacteoside, a dihydroxypheynylethyl glycoside, is a major bioactive component of Abeliophyllum distichum (White Forsythia) which is a deciduous shrub native to the south and central areas of Korea. The present study is designed to evaluate the anti-inflammatory activities and underlying mechanisms of isoacteoside in human mast cell line, HMC-1 cells. We isolated isoacteoside from A. distichum. The anti-inflammatory effect of isoacteoside was investigated in HMC-1 cells by studying the following markers: phorbol 12-myristate 13-acetate and calcium ionophore A23187 (PMACI)-induced interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor alpha (TNF-α) secretion and mRNA expression by ELISA and RT-PCR, respectively. In addition, mechanism related to anti-inflammatory was investigated by Western blotting. Isoacteoside significantly suppressed the production and mRNA expression of proinflammatory cytokines including IL-1β, IL-6, IL-8 and TNF-α in PMACI-stimulated HMC-1 cells without cytotoxicity. It was found that anti-inflammatory effects of isoacteoside are mediated by action on caspase-1, mitogen-activated protein kinases (c-Jun N-terminal kinase, p38, extracellular signal-regulated protein kinase) and nuclear factor-kappa B pathways. Taken together, the present findings provide new insights that isoacteoside may be a promising anti-inflammatory agent for inflammatory disorders.