Antioxidant enzymes suppress nitric oxide production through the inhibition of NF-kappa B activation: role of H(2)O(2) and nitric oxide in inducible nitric oxide synthase expression in macrophages

The Effects of Dietary Pterostilbene on the Immune Response, Antioxidant Function, and Jejunal Structure of Broilers

This experiment was carried out to investigate the effect of pterostilbene (PTE) supplementation in feed on Arbor Acres broilers in terms of serum biochemical parameters, immune and inflammatory responses, antioxidant status, and intestinal morphological structure. For a duration of 42 days, a total of 480 1-day-old Arbor Acres broilers were randomly divided into four groups. Each group was assigned to receive either the basal diet or the basal diet supplemented with 200, 400, or 600 mg/kg of PTE. Each treatment consisted of eight replicates, with 15 chicks per replicate. In comparison with the control group, three PTE treatments significantly increased the lymphocyte transformation rate in the spleen of broilers. The automated biochemical analysis, enzyme-linked immunosorbent assay, and RT-qPCR analysis kits found that 400 mg/kg of PTE significantly increased the serum levels of complement C3, IL-4, and iNOS; reduced the serum levels of IL-6, TNF-α, and mRNA levels of the genes IL-6, IL-8, TNF-α, NLRP3, and IFN-γ; significantly improved the activities of antioxidant enzymes including CAT, GSH-Px, and T-SOD in the jejunum; and significantly reduced the MDA contents in the serum and jejunum of broilers. Nikon microscope observations and ImagePro Plus 6.0 measure results found that 400 mg/kg of PTE supplementation significantly reduced the relative length and weight of the jejunum and improved the jejunal villi structure, resulting in increased intestinal villi, deepened crypt, and an enhanced ratio of villi height to crypt depth (VH/CD). RT-qPCR and Western blot found that dietary PTE also resulted in increased mRNA levels of the genes Claudin-2, Occludin, ZO-1, and Sirt1, and decreased NF-κB protein levels in the jejunum. The results of this study demonstrated that dietary PTE improved the immune function and intestinal health of broilers by reducing inflammation and increasing the antioxidant capacity of the animals.

Photobiomodulation effects on synovial morphology, iNOS gene, and protein expression in a model of acute inflammation

PURPOSE

To evaluate morphological aspects and inducible nitric oxide synthase (iNOS) gene and protein expression in a model of acute inflammation.

METHODS

Thirty-six female Wistar rats were assigned into three groups: control (saline, n = 12), sham (arthritis, n = 12), and PBM (arthritis and photobiomodulation, n = 12). Arthritis induction was performed with 200 μg of intra-articular Zymosan in sham and PBM animals. PBM was performed 24 h after induction with a laser device (λ = 808 nm, 25 mW of nominal power, fluence of 20 J/cm2, beam area of 0.02 mm2, time of 33 s, total energy of 0.825 J) with punctual and single dose application. Morphological analysis of joint structure (HE) and immunohistochemistry (anti-iNOS antibody) were performed on knee samples, and synovial tissue was submitted to RNA extraction, cDNA synthesis and gene expression analysis by quantitative polymerase chain reaction. Statistical analyses were performed with p < 0.05.

RESULTS

It was observed an increase in the thickness of the synovial lining epithelium and inflammatory infiltrate in sham compared to PBM. Gene expression analysis showed higher iNOS expression in PBM, and iNOS protein expression decreased in PBM compared to sham.

CONCLUSIONS

Photobiomodulation decreased inflammation in PBM animals, upregulated iNOS gene expression, however down egulated protein expression compared to sham.

Pyrrolidine dithiocarbamate in combination with L-N-monomethyl arginine alleviates Staphylococcus aureus infection via regulation of CXCL8/CXCR1 axis in peritoneal macrophages in vitro

The CXCL8/CXCR1 axis in conjoint with the free radicals and anti-oxidants dictates the severity of inflammation caused by the bacteria, Staphylococcus aureus. S.aureus mediated inflammatory processes is regulated by NF-κB and its product, iNOS. The objective of this study was to examine the effects of inhibition of NF-κB and iNOS on CXCL8/CXCR1, alteration in M1/M2 polarization of macrophages and associated inflammatory responses during S.aureus infection in vitro. For this, the murine peritoneal macrophages were pretreated with NF-κB inhibitor, Pyrrolidine dithiocarbamate (PDTC) and iNOS inhibitor, L-N-monomethyl arginine (LNMMA), either alone or in combination, followed by time-dependent S.aureus infection. The chemotactic migrations of macrophages were determined by the agarose spot assay. The iNOS, NF-κB and CXCR1 protein expressions were evaluated. The ROS level (superoxide, H2O2, NO) and antioxidant activities (SOD, CAT, GSH, arginase) were measured. The intra-macrophage phagoctyic activity had been analyzed by confocal microscopy. S.aureus activated macrophages showed increased iNOS expression that symbolizes M1 characterization of macrophages. The results suggest that the combination treatment of LNMMA + PDTC was effective in diminution of CXCL8 production and CXCR1 expression through downregulation of NF-κB and iNOS signaling pathway. Consequently, there was decrement in macrophage migration, reduced ROS generation, elevated antioxidant enzyme activity as well as bacterial phagocytosis at 90 min post bacterial infection. The increased arginase activity further proves the switch from pro-inflammatory M1 to anti-inflammatory M2 polarization of macrophages. Concludingly, the combination of PDTC + LNMMA could resolve S.aureus mediated inflammation through mitigation of CXCL8/CXCR1 pathway switching from M1 to M2 polarization.

Prevention of aspirin-mediated secondary toxicity by combined treatment of carotenoids in macrophages

Upon understanding the boosting role of carotenoids on the endogenous anti-inflammatory system, it is vital to explore their role in reducing the use of high doses of non-steroidal anti-inflammatory drug (NSAIDs), and their mediated secondary toxicity during the treatment of chronic diseases. The current study investigates the carotenoids potential on inhibition of secondary complications induced by NSAIDs, aspirin (ASA) against lipopolysaccharide (LPS) stimulated inflammation. Initially, this study evaluated a minimal cytotoxic dose of ASA and carotenoids (β-carotene, BC/lutein, LUT/astaxanthin, AST/fucoxanthin FUCO) in Raw 264.7, U937, and peripheral blood mononuclear cells (PBMCs). In all three cells, carotenoids + ASA treatment reduced the LDH release, NO, and PGE2 efficiently than an equivalent dose of carotenoid or ASA treated alone. Based on cytotoxicity and sensitivity results, RAW 264.7 cells were selected for further cell-based assay. Among carotenoids, FUCO + ASA exhibited an efficient reduction of LDH release, NO, and PGE2 than the other carotenoids (BC + ASA, LUT + ASA, and AST + ASA) treatment. FUCO + ASA combination decreased LPS/ASA induced oxidative stress, pro-inflammatory mediators (iNOS, COX-2, and NF-κB), and cytokines (IL-6, TNF-α, and IL-1β) efficiently. Further, apoptosis was inhibited by 69.2% in FUCO + ASA, and 46.7% in ASA than LPS treated cells. A drastic decrease in intracellular ROS generation with the increase in GSH was observed in FUCO + ASA compared to LPS/ASA groups. The results documented on the low dose of ASA with a relative physiological concentration of FUCO suggested greater importance for alleviating secondary complications and optimize prolonged chronic disease treatments with NSAID's associated side effects.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03632-w.

Effects of Melatonin and Silymarin on Reactive Oxygen Species, Nitric Oxide Production, and Sperm Viability and Motility during Sperm Freezing in Pigs

Sperm during the freezing and thawing process is damaged by oxidative stress. Thus, its antioxidant scavenger is essential for sperm survival and death in frozen-thawed semen. We used melatonin and silymarin in experiments after the dose-dependent experiment. Our study aimed to identify the effect of melatonin and silymarin on the motility and viability of sperm, reactive oxygen species (ROS), and nitric oxide (NO) production in frozen-thawed boar semen. Melatonin and silymarin were treated alone and cotreated in the fresh boar semen. Boar semen was collected using the gloved-hand method from ten crossbred pigs, and samples were used in the experiments. We evaluated sperm viability using SYBR-14 and PI kit, and ROS and NO production were detected by DCF-DA and DAF-2, respectively. The sperm motility was not significantly different between non-treatment and treatment. ROS and NO production in frozen-thawed sperm were decreased by melatonin and silymarin. Moreover, silymarin significantly reduced NO production more than melatonin. Melatonin and silymarin enhanced the viability of sperm. We suggest that melatonin and silymarin are essential antioxidants in semen cryopreservation for protecting sperm damage and maintaining sperm viability. Melatonin and silymarin may be useful antioxidants in freezing boar sperm.

Investigations of adsorption behavior and anti-inflammatory activity of glycine functionalized Al12N12 and Al12ON11 fullerene-like cages

The adsorption behavior of the amino acid, glycine (Gly), via the carboxyl, hydroxyl, and amino groups onto the surfaces of Al₁₂N₁₂ and Al₁₆N₁₆ fullerene-like cages were computationally evaluated by the combination of density functional theory (DFT) and molecular docking studies. It was found that Gly can chemically bond with the Al₁₂N₁₂ and Al₁₆N₁₆ fullerene-like cages as its amino group being more favorable to interact with the aluminum atoms of the adsorbents compared to carboxyl and hydroxyl groups. Oxygen and carbon doping were reported to reduce steric hindrance for Glycine interaction at Al site of Al₁₂ON₁₁/Gly and Al₁₂CN₁₁/Gly complexes. Interaction was further enhanced by oxygen doping due to its greater electron withdrawing effect. Herein, the Al₁₂ON₁₁/Gly complex where two carbonyl groups of Gly are bonded to the aluminum atoms of the Al₁₂N₁₂ fullerene-like cage is the most stable interaction configuration showing ∆_adsH and ∆_adsG values of -81.74 kcal/mol and -66.21 kcal/mol, respectively. Computational studies also revealed the frequency shifts that occurred due to the interaction process. Molecular docking analysis revealed that the Al₁₂N₁₂/Gly (-11.7 kcal/mol) and the Al₁₂ON₁₁/Gly (-9.2 kcal/mol) complexes have a good binding affinity with protein tumor necrosis factor alpha (TNF-α). TNF-α was implicated as a key cytokine in various diseases, and it has been a validated therapeutic target for the treatment of rheumatoid arthritis. These results suggest that the Al₁₂N₁₂/Gly complex in comparison with the Al₁₆N₁₆/Gly, Al₁₂ON₁₁/Gly, and the Al₁₂CN₁₁/Gly complexes could be efficient inhibitors of TNF-α.

Baicalin improves the survival in endotoxic mice and inhibits the inflammatory responses in LPS-treated RAW 264.7 macrophages

Introduction:

Sepsis is a severe disease with a high morbidity and mortality. Baicalin, an active compound of Chinese medicine, Scutellaria baicalensis Georgi (Huang Qui), exhibits several beneficial effects. In this study, we examined whether administration of baicalin increases the survival in mice with endotoxemia and investigated its anti-inflammatory mechanisms in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

Methods:

The production of NOx, PGE2, and pro-inflammatory cytokines, the mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the nuclear translocation of NF-κB in LPS-stimulated macrophages or endotoxic mice were determined. The model of severe endotoxic mice was established by injection of LPS (60 mg/kg, i.p.).

Results:

Baicalin significantly inhibited the production of NO, PGE2, and pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6 in LPS-stimulated macrophages. Baicalin treatment also markedly suppressed LPS-induced iNOS and COX-2 expression at the transcriptional and translational levels, and the nuclear translocation of NF-κB in macrophages. Similarly, the serum concentrations of NOx, PGE2, and pro-inflammatory cytokines, and the lung myeloperoxidase activity were greatly reduced in baicalin-treated endotoxic mice. Notably, after LPS injection, the 3-day survival rate of mice treated with pre- or post-administration of baicalin (50 mg/kg, i.p.) remarkably increased to 100% and 90%, respectively compared with LPS-injected alone mice with a survival rate of 0%.

Conclusion:

Baicalin has a potent anti-inflammatory activity in LPS-stimulated macrophages and endotoxic mice. Moreover, treatment with baicalin dramatically increased the survival in the severe septic mice, suggesting that baicalin may be a potential agent for sepsis therapy.

Phyto-therapeutic potential of stem bark of the wonder tree, Prosopis cineraria (L.) Druce in LPS-induced mouse model: An Anti-Inflammatory Study

Background

Therapeutic potential of Prosopis cineraria has been extensively explored by many eminent researchers against various serious diseases but its activity against Lipopolysaccharide (endotoxin) is obscure. Therefore, present experimental investigation was conducted to unravel and analyze the anti-inflammatory potential of hydro-ethanol extract of Prosopis cineraria against LPS-induced inflammation in Swiss albino male mice.

Methods

Swiss Albino male mice were intoxicated (intra-peritoneal) with LPS (2 mg/kg body weight) and further treated with low and high dose (i.e. 100 mg/kg body weight and 300 mg/kg body weight respectively) of hydro-ethanol extract of stem-bark of Prosopis cineraria. The levels of cytokines (TNF-α, Prostaglandins E2, IL-6, NF-κBp65, IFN-γ and IL-10) were determined in liver homogenate. Nitric oxide generated due to LPS-induced toxicity was estimated by using Griess reagent.

Results

The results demonstrated that the plant extract suppressed the over-expression and altered levels of cytokines due to LPS intoxication and restored the levels of TNF-α, NF-κB, NO, IL-6, IFN- γ, Prostaglandin E2 and IL-10.

Conclusion

The present research work unravelled the alleviating potential of Prosopis cineraria against LPS-induced inflammation by modulating the expression of cytokines.

Antioxidant and Intracellular Reactive Oxygen Species/Reactive Nitrogen Species Scavenging Activities of Three Porcupine Bezoars from Hystrix brachyura

BACKGROUND

Porcupine dates are phytobezoar stones that are used in Traditional Chinese Medicine (TCM) treatments against cancer, postsurgical recovery, dengue fever, etc. The medicinal values have not been scientifically investigated due to the availability and high pricing of the dates.

OBJECTIVES

This paper represents the first report on the phytochemical content, in vitro antioxidant and intracellular reactive oxygen species (ROS)/reactive nitrogen species (RNS) scavenging properties of the extracts of three porcupine dates: grassy date (GD), black date (BD), and powdery date (PD).

MATERIALS AND METHODS

Dried samples were extracted with methanol and lyophilized. Samples were screened for phytochemical constituents, in vitro antioxidant assays based on total phenolic content (TPC), free radical scavenging, and ferric reducing power (FRP) as well as intracellular ROS and RNS scavenging properties.

RESULTS

Phytochemical screening and total tannins assay revealed that tannins, cardiac glycosides, and terpenoids were found in all porcupine dates with tannins forming the major portion of the TPC. In comparison to GD, BD and PD were found to contain significantly high TPC, radical scavenging activity, and FRP. At 200 μg/ml, BD and PD remarkably scavenged 2, 2-azobis (2-amidinopropane) dihydrochloride-induced ROS in RAW264.7 cells and significantly reduced nitric oxide in lipopolysaccharide-stimulated cells.

CONCLUSION

Overall, BD and PD exhibited promising in vitro antioxidant as well as intracellular ROS/RNS scavenging properties.

SUMMARY

Tannins, cardiac glycoside, and terpenoids were found in all three types of porcupine dates with tannins being the major compoundsAntioxidant contents and properties of three dates were in the order black date (BD) > powdery date (PD) > grassy dateBD and PD extracts showed significant intracellular reactive oxygen species and reactive nitrogen species scavenging properties. Abbreviations Used: TCM: Traditional Chinese Medicine, BD: Black date, GD: Grassy date, PD: Powdery date, TPC: Total phenolic content, FRS: Free radical scavenging, FRP: Ferric reducing power, NO: Nitric oxide, ROS: Reactive oxygen species, RNS: Reactive nitrogen species, GAE: Gallic acid equivalent, AAE: Ascorbic acid equivalent, PVPP: Polyvinylpolypyrrolidone, DCFH-DA: Dichloro-dihydro-fluorescein diacetate, AAPH: 2, 2-azobis (2-amidinopropane) dihydrochloride, LPS: Lipopolysaccharide.

Doxorubicin-induced nitrosative stress is mitigated by vitamin C via the modulation of nitric oxide synthases

An increase in oxidative stress is suggested to be the main cause in Doxorubicin (Dox)–induced cardiotoxicity. However, there is now evidence that activation of inducible nitric oxide synthase (iNOS) and nitrosative stress are also involved. The role of vitamin C (Vit C) in the regulation of nitric oxide synthase (NOS) and reduction of nitrosative stress in Dox-induced cardiotoxicity is unknown. The present study investigated the effects of Vit C in the mitigation of Dox-induced changes in the levels of nitric oxide (NO), NOS activity, protein expression of NOS isoforms, and nitrosative stress as well as cytokines TNF-α and IL-10 in isolated cardiomyocytes. Cardiomyocytes isolated from adult Sprague-Dawley rats were segregated into four groups: 1) control, 2) Vit C (25 µM), 3) Dox (10 µM), and 4) Vit C + Dox. Dox caused a significant increase in the generation of superoxide radical (O2·−), peroxynitrite, and NO, and these effects of Dox were blunted by Vit C. Dox increased the expression of iNOS and altered protein expression as well as activation of endothelial NOS (eNOS). These changes were prevented by Vit C. Dox induced an increase in the ratio of monomeric/dimeric eNOS, promoting the production of O2·−, which was prevented by Vit C by increasing the stability of the dimeric form of eNOS. Vit C protected against the Dox-induced increase in TNFα as well as a reduction in IL-10. These results suggest that Vit C provides cardioprotection by reducing oxidative/nitrosative stress and inflammation via a modulation of Dox-induced increase in the NO levels and NOS activity.

The Glyoxalase System and Methylglyoxal-Derived Carbonyl Stress in Sepsis: Glycotoxic Aspects of Sepsis Pathophysiology

Sepsis remains one of the leading causes of death in intensive care units. Although sepsis is caused by a viral, fungal or bacterial infection, it is the dysregulated generalized host response that ultimately leads to severe dysfunction of multiple organs and death. The concomitant profound metabolic changes are characterized by hyperglycemia, insulin resistance, and profound transformations of the intracellular energy supply in both peripheral and immune cells. A further hallmark of the early phases of sepsis is a massive formation of reactive oxygen (ROS; e.g., superoxide) as well as nitrogen (RNS; e.g., nitric oxide) species. Reactive carbonyl species (RCS) form a third crucial group of highly reactive metabolites, which until today have been not the focus of interest in sepsis. However, we previously showed in a prospective observational clinical trial that patients suffering from septic shock are characterized by significant methylglyoxal (MG)-derived carbonyl stress, with the glyoxalase system being downregulated in peripheral blood mononuclear cells. In this review, we give a detailed insight into the current state of research regarding the metabolic changes that entail an increased MG-production in septicemia. Thus, we point out the special role of the glyoxalase system in the context of sepsis.

Modulatory effects of caffeine on oxidative stress and anxiety-like behavior in ovariectomized rats

Menopause is accompanied by enhanced oxidative stress and behavioral changes, effects attenuated by antioxidants. The aim of this study was to evaluate the effects of caffeine on behavior and oxidative stress in an experimental model of menopause. Female rats were divided into the following groups: sham-operated (CON), sham-operated and caffeine-treated (CAF), ovariectomized (OVX), ovariectomized and caffeine-treated (OVX+CAF). Caffeine (6 mg/kg) and vehicle were administered for 21 days (subchronic) and 42 days (chronic), using 2 experimental subsets. Behavioral tests and oxidative stress parameters in the blood, whole brain, and hippocampus were assessed. The subchronic administration of caffeine decreased the lipid peroxidation and improved the antioxidant defense in the blood and brain. The GSH/GGSG ratio in the brain was improved by chronic administration, with reduced activities of antioxidant enzymes and enhanced nitric oxide and malondialdehyde levels. In particular, the lipid peroxidation in the hippocampus decreased in both experiments. The rats became hyperactive after 21 days of treatment, but no effect was observed after chronic administration. In both experimental subsets, caffeine had anxiolytic effects as tested in elevated plus maze. The administration of low doses of caffeine, for a short period of time, may be a new therapeutic approach to modulating the oxidative stress and anxiety in menopause.

Evaluation of iNOS Expression in Esophageal Cancer Patients

BACKGROUND

Esophageal cancer is a public health concern around the world; this cancer is the sixth leading cause of death of cancer in the world with about 386,000 deaths per year. Its risk factors include environmental factors such as tobacco smoke, gastroesophageal reflux and genetic changes. iNOS is stated by the effect of various inflammatory factors and is thus called inducible NOS. Investigating iNOS expression is a powerful tool for understanding effective molecular parameters at tissue and cellular responses to external factors. In this research work, iNOS expression in patients with esophageal cancer was studied in Iran.

MATERIALS AND METHODS

15 formalin-fixed and paraffin-embedded (FFPE) esophageal cancer tissue samples and 15 normal FFPE samples were collected from various medical centers (Zabol, Zahedan, Kashan) to measure iNOS expression by real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR). All PCR reactions were conducted by three replicates for iNOS and internal control (β-actin) by 2^-ΔΔCT (Livak) method. Differences were measured in target gene expression in patients and control group using the t test. All statistical analyses were done using the SPSS software.

RESULTS

The results showed that there was no significant difference between iNOS expression in the case and control groups (p > 0.05); however, there was an increase in iNOS expression in the case group. On the other hand, there was a significant difference between iNOS expression in males and females in the two groups of healthy subjects and patients, and it was higher in women than in men.

CONCLUSION

Further studies need to be conducted with larger sample sizes and in other populations to validate these findings.

Influence of A Continuous Very Low Dose of Gamma-Rays on Cell Proliferation, Apoptosis and Oxidative Stress

We have previously shown a delay of death by lymphoma in SJL/J mice irradiated with continuous very low doses of ionizing radiation. In order to understand the mechanisms involved in this phenomenon, we have irradiated in vitro the Raw264.7 monocytic and the YAC-1 lymphoma cell lines at very low-dose rate of 4cGy.month(-1). We have observed a transient increase in production of both free radicals and nitric oxide with a transient adaptive response during at least two weeks after the beginning of the irradiation. The slight decrease of Ki67 proliferation index observed during the second and third weeks of YAC-1 cells culture under irradiation was not significant but consistent with the shift of the proliferation assay curves of YAC-1cells at these same durations of culture. These in vitro results were in good agreement with the slightly decrease under irradiation of Ki67 proliferative index evaluated on lymphomatous lymph nodes of SJL/J mice. A significant decrease of YAC-1 cells apoptotic rate under radiation appeared after 4 weeks of culture. Therefore very small doses of gamma-irradiation are able to modify the cellular response. The main observations did not last with increasing time under irradiation, suggesting a transient adaptation of cells or organisms to this level of irradiation.

Apigenin modulates the expression levels of pro-inflammatory mediators to reduce the human insulin amyloid-induced oxidant damages in SK-N-MC cells

Amyloid depositions of proteins play crucial roles in a wide variety of degenerative disorders called amyloidosis. Although the exact mechanisms involved in amyloid-mediated cytotoxicity remain unknown, increased formation of reactive oxygen species (ROS) and nitrogen species and overproduction of pro-inflammatory cytokines are believed to play key roles in the process. In that regard, we investigated the effect of apigenin, a common dietary flavonoid with high antioxidant and anti-inflammatory properties on potential factors involved in cytotoxicity of human insulin amyloids. Pretreatment of SK-N-MC neuroblastoma cells with apigenin increased cell viability and reduced the apoptosis induced by insulin fibrils. In addition, apigenin attenuated insulin fibril-induced ROS production and lipid peroxidation. Our result also demonstrated that pretreatment of the fibril-affected cells with apigenin caused an increase in catalase activity and the intracellular glutathione content along with reduction in nitric oxide production and nuclear factor κB, tumor necrosis factor α, and interleukin 6 gene expression based on real-time polymerase chain reaction evaluation. In accordance with these results, apigenin could be a promising candidate in the design of natural-based drugs for treatment or prevention of amyloid-related disorders.

Aging is not a disease: distinguishing age-related macular degeneration from aging

Age-related macular degeneration (AMD) is a disease of the outer retina, characterized most significantly by atrophy of photoreceptors and retinal pigment epithelium accompanied with or without choroidal neovascularization. Development of AMD has been recognized as contingent on environmental and genetic risk factors, the strongest being advanced age. In this review, we highlight pathogenic changes that destabilize ocular homeostasis and promote AMD development. With normal aging, photoreceptors are steadily lost, Bruch's membrane thickens, the choroid thins, and hard drusen may form in the periphery. In AMD, many of these changes are exacerbated in addition to the development of disease-specific factors such as soft macular drusen. Para-inflammation, which can be thought of as an intermediate between basal and robust levels of inflammation, develops within the retina in an attempt to maintain ocular homeostasis, reflected by increased expression of the anti-inflammatory cytokine IL-10 coupled with shifts in macrophage plasticity from the pro-inflammatory M1 to the anti-inflammatory M2 polarization. In AMD, imbalances in the M1 and M2 populations together with activation of retinal microglia are observed and potentially contribute to tissue degeneration. Nonetheless, the retina persists in a state of chronic inflammation and increased expression of certain cytokines and inflammasomes is observed. Since not everyone develops AMD, the vital question to ask is how the body establishes a balance between normal age-related changes and the pathological phenotypes in AMD.

Astrocytes inhibit nitric oxide-dependent Ca(2+) dynamics in activated microglia: involvement of ATP released via pannexin 1 channels

Under inflammatory conditions, microglia exhibit increased levels of free intracellular Ca(2+) and produce high amounts of nitric oxide (NO). However, whether NO, Ca(2+) dynamics, and gliotransmitter release are reciprocally modulated is not fully understood. More importantly, the effect of astrocytes in the potentiation or suppression of such signaling is unknown. Our aim was to address if astrocytes could regulate NO-dependent Ca(2+) dynamics and ATP release in LPS-stimulated microglia. Griess assays and Fura-2AM time-lapse fluorescence images of microglia revealed that LPS produced an increased basal [Ca(2+) ]i that depended on the sequential activation of iNOS, COXs, and EP1 receptor. TGFβ1 released by astrocytes inhibited the abovementioned responses and also abolished LPS-induced ATP release by microglia. Luciferin/luciferase assays and dye uptake experiments showed that release of ATP from LPS-stimulated microglia occurred via pannexin 1 (Panx1) channels, but not connexin 43 hemichannels. Moreover, in LPS-stimulated microglia, exogenous ATP triggered activation of purinergic P2Y1 receptors resulting in Ca(2+) release from intracellular stores. Interestingly, TGFβ1 released by astrocytes inhibited ATP-induced Ca(2+) response in LPS-stimulated microglia to that observed in control microglia. Finally, COX/EP1 receptor signaling and activation of P2 receptors via ATP released through Panx1 channels were critical for the increased NO production in LPS-stimulated microglia. Thus, Ca(2+) dynamics depended on the inflammatory profile of microglia and could be modulated by astrocytes. The understanding of mechanisms underlying glial cell regulatory crosstalk could contribute to the development of new treatments to reduce inflammatory cytotoxicity in several brain pathologies.

Reactive metabolites and AGE-RAGE-mediated inflammation in patients following liver transplantation

Recent investigations have indicated that reactive metabolites and AGE-RAGE-mediated inflammation might play an important role in the pathogenesis of ischemia-reperfusion injury in liver transplantation. In this observational clinical study, 150 patients were enrolled following liver transplantation from deceased donors. The occurrence of short-term complications within 10 days of transplantation was documented. Blood samples were collected prior to transplantation, immediately after transplantation, and at consecutive time points, for a total of seven days after transplantation. Plasma levels of methylglyoxal were determined using HPLC, whereas plasma levels of L-arginine, asymmetric dimethylarginine, advanced glycation endproducts-carboxylmethyllysine, soluble receptor for advanced glycation endproducts, and total antioxidant capacity were measured by ELISA. Patients following liver transplantation were shown to suffer from increased RAGE-associated inflammation with an AGE load mainly dependent upon reactive carbonyl species-derived AGEs. In contrast, carboxylmethyllysine-derived AGEs were of a minor importance. As assessed by the ratio of L-arginine/asymmetric dimethylarginine, the bioavailability of nitric oxide was shown to be reduced in hepatic IRI, especially in those patients suffering from perfusion disorders following liver transplantation. For the early identification of patients at high risk of perfusion disorders, the implementation of asymmetric dimethylarginine measurements in routine diagnostics following liver transplantation from deceased donors should be taken into consideration.

Hemoglobin-induced nitric oxide synthase overexpression and nitric oxide production contribute to blood-brain barrier disruption in the rat

Hemoglobin (Hb) released from extravasated erythrocytes may have a critical role in the process of blood-brain barrier (BBB) disruption and subsequent edema formation after intracerebral hemorrhage (ICH). Excessive nitric oxide (NO) production synthesized by nitric oxide synthase (NOS) has been well documented to contribute to BBB disruption. However, considerably less attention has been focused on the role of NO in Hb-induced BBB disruption. This study was designed to examine the hypothesis that Hb-induced NOS overexpression and excessive NO production may contribute to the changes of tight junction (TJ) proteins and subsequent BBB dysfunction. Hemoglobin was infused with stereotactic guidance into the right caudate nucleus of male Sprague Dawley rats. Then, we investigated the effect of Hb on the BBB permeability, changes of TJ proteins (claudin-5, occludin, zonula occludens-1 (ZO-1), and junctional adhesion molecule-1 (JAM-1)), iron deposition, expression of inducible NOS (iNOS) and endothelial NOS (eNOS), as well as NO production. Hb injection caused a significant increase in BBB permeability. Significant reduction of claudin-5, ZO-1, and JAM-1 was observed after Hb injection as evidenced by PCR and immunofluorescence. After a decrease at early stage, occludin showed a fivefold increase in mRNA level at 7 days. Significant iron deposition was detectable from 48 h to 7 days in a time-dependent manner. The iNOS and eNOS levels dramatically increased after Hb injection concomitantly with large quantities of NO released. Furthermore, enhanced iNOS or eNOS immunoreactivity was co-localized with diffused or diminished claudin-5 staining. We concluded that overexpressed NOS and excessive NO production induced by Hb may contribute to BBB disruption, which may provide an important potential therapeutic target in the treatment of ICH.

Plant polyphenols attenuate hepatic injury after hemorrhage/resuscitation by inhibition of apoptosis, oxidative stress, and inflammation via NF-kappaB in rats

PURPOSE

Oxidative stress and inflammation contribute to hepatic injury after hemorrhage/resuscitation (H/R). Natural plant polyphenols, i.e., green tea extract (GTE) possess high anti-oxidant and anti-inflammatory activities in various models of acute inflammation. However, possible protective effects and feasible mechanisms by which plant polyphenols modulate pro-inflammatory, apoptotic, and oxidant signaling after H/R in the liver remain unknown. Therefore, we investigated the effects of GTE and its impact on the activation of NF-kappaB in the pathogenesis of hepatic injury induced by H/R.

METHODS

Twenty-four female LEWIS rats (180-250 g) were fed a standard chow (ctrl) or a diet containing 0.1% polyphenolic extracts (GTE) from Camellia sinensis starting 5 days before H/R. Rats were hemorrhaged to a mean arterial pressure of 30 ± 2 mmHg for 60 min and resuscitated (H/R and GTE H/R groups). Control groups (sham, ctrl, and GTE) underwent surgical procedures without H/R. Two hours after resuscitation, tissues were harvested.

RESULTS

Plasma alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) increased 3.5-fold and fourfold, respectively, in vehicle-treated rats as compared to GTE-fed rats. Histopathological analysis revealed significantly decreased hepatic necrosis and apoptosis in GTE-fed rats after H/R. Real-time PCR showed that GTE diminished gene expression of pro-apoptotic caspase-8 and Bax, while anti-apoptotic Bcl-2 was increased after H/R. Hepatic oxidative (4-hydroxynonenal) and nitrosative (3-nitrotyrosine) stress as well as systemic IL-6 level and hepatic IL-6 mRNA were markedly reduced in GTE-fed rats compared with controls after H/R. Plant polyphenols also decreased the activation of both JNK and NFκB.

CONCLUSIONS

Taken together, GTE application blunts hepatic damage, apoptotic, oxidative, and pro-inflammatory changes after H/R. These results underline the important roles of JNK and NF-kappaB in inflammatory processes after H/R and the beneficial impact of plant polyphenols in preventing their activation.

Asymmetric dimethylarginine potentiates lung inflammation in a mouse model of allergic asthma

Nitric oxide (NO), formed by nitric oxide synthase (NOS), is an important mediator of lung inflammation in allergic asthma. Asymmetric dimethylarginine (ADMA), a competitive endogenous inhibitor of NOS, is metabolized by the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Elevated ADMA has been shown to affect lung function in mice, and by inhibiting NOS it alters NO and reactive oxygen species production in mouse lung epithelial cells. However, the effects of altered ADMA levels during lung inflammation have not been explored. A model of allergen-induced airway inflammation was utilized in combination with the modulation of endogenous circulating ADMA levels in mice. Airway inflammation was assessed by quantifying inflammatory cell infiltrates in lung lavage and by histology. Lung DDAH expression was assessed by quantitative PCR and immunohistochemistry. Nitrite levels were determined in lung lavage fluid as a measure of NO production. iNOS expression was determined by immunohistochemistry, immunofluorescence, Western blot, and quantitative PCR. NF-κB binding activity was assessed by a transcription factor binding assay. Allergen-induced lung inflammation was potentiated in mice with elevated circulating ADMA and was reduced in mice overexpressing DDAH. Elevated ADMA reduced nitrite levels in lung lavage fluid in both allergen-challenged and control animals. ADMA increased iNOS expression in airway epithelial cells in vivo following allergen challenge and in vitro in stimulated mouse lung epithelial cells. ADMA also increased NF-κB binding activity in airway epithelial cells in vitro. These data support that ADMA may play a role in inflammatory airway diseases such as asthma through modulation of iNOS expression in lung epithelial cells.

Liquid perfluorochemical inhibits inducible nitric oxide synthase expression and nitric oxide formation in lipopolysaccharide-treated RAW 264.7 macrophages

Partial liquid ventilation with various types of perfluorocarbon (PFC) has been shown to be beneficial in treating acute lung injury, a clinical outcome that may involve the anti-inflammatory activity of PFC. FC-77 is a type of PFC with relatively higher vapor pressure and evaporative loss than other PFCs during partial liquid ventilation. Overproduction of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been proposed to play a crucial role in the pathogenesis of inflammatory diseases. However, whether the iNOS/NO pathway is affected by FC-77 is unknown. Thus, the aim of this study was to investigate whether FC-77 inhibits iNOS expression and NO production in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. We found that treatment with FC-77 significantly attenuated LPS-induced iNOS expression/activity and production of NO and reactive oxygen species (ROS). FC-77 also attenuated LPS-induced pro-inflammatory cytokine formation, but enhanced interleukin-10 production. Furthermore, the LPS-induced degradation of cytosolic IkappaB-alpha and activation of nuclear transcription factor-kappaB (NF-kappaB) were also inhibited by FC-77. In conclusion, the present study is the first to demonstrate that FC-77 decreases LPS-induced NO production in macrophages, which may be associated with the suppression of pro-inflammatory cytokines, and ROS production, as well as NF-kappaB activation. These results also provide a novel explanation for its anti-inflammatory activity.

The effect of intracellular antioxidant delivery (catalase) on hydrogen peroxide and proinflammatory cytokine synthesis: a new therapeutic horizon

Reactive oxygen species synthesized by endothelial cells may be responsible for cell damage and altered physiologic function. After endotoxin stimulation, free radicals including H(2)O(2) are produced. We have developed a method of intracellular drug delivery using albumin microcapsules. Catalase would be an excellent compound to alter H(2)O(2) production. However, the large molecular size of catalase limits cellular penetration. Endothelial cells have been previously shown to readily phagocytoze albumin microcapsules.

METHODS

Catalase was added to an albumin solution to form a 10% solution of catalase. Microspheres from 2 to 7 microm in size were formed using a Bucchi spray dryer. Human endothelial cells were incubated with varying concentrations of microencapsulated catalase. The cells were then exposed to Escherichia coli endotoxin to determine if increased intracellular penetration of catalase would inhibit H(2)O(2), nitrate, and cytokine synthesis.

RESULTS

There was a 7.2-fold increase in endothelial intracellular catalase after 48 h incubation. H(2)O(2) was inhibited by 72%, nitrate 96%, TNF 90%, IL1 21%, IL6 42%.

CONCLUSIONS

These results demonstrate that inhibition of H(2)O(2) as a result of increased intracellular delivery of catalase inhibits proinflammatory cytokine synthesis after endotoxin exposure.

Supressive effect of maslinic acid from pomace olive oil on oxidative stress and cytokine production in stimulated murine macrophages

The pentacyclic triterpene maslinic acid (MA) is a natural compound present in the non glyceride fraction of pomace olive oil, also called orujo olive oil. This compound has previously demonstrated antioxidant properties against lipid peroxidation in vitro, but its effects on reactive oxygen and nitrogen-derived species and pro-inflammatory cytokines generated by a cell system have not yet been investigated. In this study, we have tested the effect of MA upon oxidative stress and cytokine production using peritoneal murine macrophages. MA significantly inhibited the enhanced production of nitric oxide (NO) induced by lypopolysaccharide (LPS) when it was measured by the nitrite production with an inhibitory concentration 50% value (IC(50)) of 25.4 microM. This inhibiting effect seems to be consequence of an action at the level of the LPS-induction of the inducible nitric oxide synthethase (iNOS) gene enzyme expression rather than to a direct inhibitory action on enzyme activity. The secretion of the inflammatory cytokines interleukine-6 and TNF-a from LPS-stimulated murine macrophages was also significantly reduced (p < 0.05 and 0.01) by 50 and 100 microM of MA. In addition, reactive oxygen species were measured after stimulation with phorbol-12-myristate-13-acetate (PMA). Thus, pre-treatment with MA reduced the generation of hydrogen peroxide from stimulated macrophages in a dose-dependent manner (IC(50): 43.6 microM) as assayed by the oxidation of the peroxidase enzyme. However, no inhibitory effect on superoxide release, measured by the reduction of ferricytochrome c, was observed after the pretreatment with MA in the culture medium. These results suggest a potential biopharmaceutical use of this hydroxy-pentacyclic triterpene derivative, present in orujo olive oil, on preventing oxidative stress and pro-inflammatory cytokine generation.

Nitric oxide production and monoamine oxidase activity in cancer patients during interferon-alpha therapy

Both increased and decreased nitric oxide (NO) synthesis have been reported in patients treated with interferon-α (IFN-α). Animal studies showed that IFN-α administration results in increased levels of biogenic amines, subsequent activation of monoamine oxidases (MAOs), and finally in a change in NO production due to the H₂O₂ generated by MAOs. We examined the potential relationship between NO production in plasma and MAO-B activity in platelets of 43 cancer patients during 8 weeks of treatment with IFN-α. NO synthesis was quantitated by measuring both the ratio of citrulline and arginine (CIT/ARG-ratio) and total nitrite/nitrate (NOx) levels. Compared to baseline, MAO activity and NOx increased, while the CIT/ARG-ratio decreased. No associations were found between NOx, MAO and CIT/ARG-ratio. Only few associations were observed between changes in the biochemical parameters and changes in psychopathology induced by IFN-α, of which the association between changes in CIT and lassitude was the most consistent. The results suggest that peripheral NO production and MAO activity are unrelated to each other, and that peripheral changes in these biochemical parameters induced by IFN-α are unlikely to contribute to definite psychiatric disturbance.

The non-provitamin A carotenoid, lutein, inhibits NF-kappaB-dependent gene expression through redox-based regulation of the phosphatidylinositol 3-kinase/PTEN/Akt and NF-kappaB-inducing kinase pathways: role of H(2)O(2) in NF-kappaB activation

Reactive oxygen species (ROS) have been implicated in the regulation of NF-kappaB activation, which plays an important role in inflammation and cell survival. However, the molecular mechanisms of ROS in NF-kappaB activation remain poorly defined. We found that the non-provitamin A carotenoid, lutein, decreased intracellular H(2)O(2) accumulation by scavenging superoxide and H(2)O(2) and the NF-kappaB-regulated inflammatory genes, iNOS, TNF-alpha, IL-1beta, and cyclooxygenase-2, in lipopolysaccharide (LPS)-stimulated macrophages. Lutein inhibited LPS-induced NF-kappaB activation, which highly correlated with its inhibitory effect on LPS-induced IkappaB kinase (IKK) activation, IkappaB degradation, nuclear translocation of NF-kappaB, and binding of NF-kappaB to the kappaB motif of the iNOS promoter. This compound inhibited LPS- and H(2)O(2)-induced increases in phosphatidylinositol 3-kinase (PI3K) activity, PTEN inactivation, NF-kappaB-inducing kinase (NIK), and Akt phosphorylation, which are all upstream of IKK activation, but did not affect the interaction between Toll-like receptor 4 and MyD88 and the activation of mitogen-activated protein kinases. The NADPH oxidase inhibitor apocynin and gp91(phox) deletion reduced the LPS-induced NF-kappaB signaling pathway as lutein did. Moreover, lutein treatment and gp91(phox) deletion decreased the expressional levels of the inflammatory genes in vivo and protected mice from LPS-induced lethality. Our data suggest that H(2)O(2) modulates IKK-dependent NF-kappaB activation by promoting the redox-sensitive activation of the PI3K/PTEN/Akt and NIK/IKK pathways. These findings further provide new insights into the pathophysiological role of intracellular H(2)O(2) in the NF-kappaB signal pathway and inflammatory process.

Nitric oxide plays a key role in the platelet-activating factor-induced enhancement of resistance against systemic candidiasis

Platelet-activating factor (PAF) has been demonstrated to augment resistance against Candida albicans infection. In this study, the role of nitric oxide (NO) in PAF-induced resistance in the kidneys was investigated. Pretreatment of the C. albicans-infected mice with PAF resulted in strong expression of messenger RNA (mRNA) and the protein synthesis of inducible nitric oxide synthase (iNOS). These PAF effects were inhibited to a significant degree by pretreatment with the nuclear factor-kappaB inhibitor, pyrrolidinedithiocarbamate. Pretreatment with PAF protected the mice from death caused by C. albicans infection and reduced the growth of fungus in the kidneys. The protective activity of PAF was abrogated by pretreatment with the iNOS inhibitor, aminoguanidine, and in the iNOS(-/-) mice. The PAF markedly increased the infiltration of neutrophils, but not macrophages, and also enhanced the mRNA expression levels of the CXC chemokine, keratinocyte-derived chemokine, in C. albicans-infected kidneys. These effects of PAF were attenuated in the aminoguanidine-treated mice and the iNOS(-/-) mice. These data show that NO plays an important role in PAF-induced protection against C. albicans.

Preventive effect of 20(S)-ginsenoside Rg3 against lipopolysaccharide-induced hepatic and renal injury in rats

The preventive effect of 20(S)-ginsenoside Rg(3) (20(S)-Rg(3)) on lipopolysaccharide (LPS)-induced oxidative tissue injury in rats was investigated in this study. The elevated serum nitrite/nitrate, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase and creatinine levels in LPS-treated control rats were significantly decreased following 15 consecutive days of 20(S)-Rg(3) administration. In addition, thiobarbituric acid-reactive substance levels in the serum, liver and kidney were dose-dependently lower in 20(S)-Rg(3)-treated groups than in the LPS-treated control group. The nuclear factor-kappaB (NF-kappaB), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) protein expressions in the liver and kidney were significantly increased by LPS treatment. However, the 20(S)-Rg(3) administrations significantly decreased these protein expressions except for HO-1 in the liver. On the other hand, in the kidney, oral administration of 20(S)-Rg(3) showed a tendency to reduce NF-kappaB and iNOS protein expressions and also significantly reduced the elevated COX-2 and HO-1 protein expressions at a dose of 10 mg/kg body weight/day. All these results suggest the preventive effect of 20(S)-Rg(3) against LPS-induced acute oxidative damage in the liver and kidney and the preventive effect of 20(S)-Rg(3) administration against LPS toxicity was thought to be more predominant in the liver than kidney.

Baicalin inhibits macrophage activation by lipopolysaccharide and protects mice from endotoxin shock

Baicalin (BA) exhibits anti-inflammatory effect in vivo and in vitro and is used to treat inflammatory diseases. Here, we report that BA inhibits the activation of macrophage and protects mice from macrophage-mediated endotoxin shock. The experiments in vitro showed BA suppressed the increased generation of nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS) induced by LPS or Interferon-gamma (IFN-gamma) without directly affecting iNOS activity in RAW264.7 cells and peritoneal macrophages. Similarly, BA inhibited the production of reactive oxidative species (ROS), whereas augmented the level of intracellular superoxide dismutase (SOD). Moreover, BA inhibited the production of inflammatory mediators including tumor necrosis factor (TNF)-alpha, endothelin (ET)-1 and thromboxane A2 (TXA2) induced by lipopolysaccharide (LPS) in RAW264.7 cells. In animal model, BA protected mice from endotoxin shock induced by d-galactosamine (D-GalN)/LPS possibly through inhibiting the production of cytokine and NO. Collectively, BA inhibited the production of inflammatory mediators by macrophage and may be a potential target for treatment of macrophage-mediated diseases.

Phellinus linteus inhibits inflammatory mediators by suppressing redox-based NF-kappaB and MAPKs activation in lipopolysaccharide-induced RAW 264.7 macrophage

The mushroom Phellinus linteus has been known to exhibit potent biological activity. In contrast to the immuno-potentiating properties of Phellinus linteus, the anti-inflammatory properties of Phellinus linteus have rarely been investigated. Recently, ethanol extract and n-BuOH fractions from Phellinus linteus were deemed most effective in anti-inflammatory activity in RAW 264.7 macrophages. The regulatory mechanisms of Phellinus linteus butanol fractions (PLBF) on the pharmacological and biochemical actions of macrophages involved in inflammation have not been clearly defined yet. In the present study, we tested the role of PLBF on anti-inflammation patterns in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. To investigate the mechanism by which PLBF inhibits NO and PGE2 production as well as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, we examined the activation of IkappaB and MAPKs in LPS-activated macrophages. PLBF clearly inhibited nuclear translocation of NF-kappaB p65 subunits, which correlated with PLBF's inhibitory effects on IkappaBalpha phosphorylation and degradation. PLBF also suppressed the activation of mitogen-activated protein (MAP) kinases including p38 and stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK). Furthermore, macrophages stimulated with LPS generated ROS via activation of membrane-bound NADPH oxidase, and ROS played an important role in the activation of nuclear factor-kappaB (NF-kappaB) and MAPKs. We demonstrated that PLBF directly blocked intracellular accumulation of reactive oxygen species in RAW 264.7 cells stimulated with LPS much as the NADPH oxidase inhibitors, diphenylene iodonium, and antioxidant pyrrolidine dithiocarbamate did. The suppression of NADPH oxidase also inhibited NO production and iNOS protein expression. Cumulatively, these results suggest that PLBF inhibits the production of NO and PGE2 through the down-regulation of iNOS and COX-2 gene expression via ROS-based NF-kappaB and MAPKs activation. Thus, PLBF may provide a potential therapeutic approach for inflammation-associated disorders.

Effect of sun ginseng methanol extract on lipopolysaccharide-induced liver injury in rats

Sun ginseng (SG) is heat-processed Panax ginseng C.A. Meyer steamed at 120 degrees C, which has ginsenoside-Rg(3), -Rk(1), and -Rg(5) as its main ginsenoside components. The effect of SG on lipopolysaccharide (LPS)-induced liver injury in rats was investigated in this study. Intravenous injection of LPS induced excessive nitric oxide (*NO) generation in serum and increased the hepatic mitochondrial thiobarbituric acid-reactive substance (TBA-RS) level. However, the elevated TBA-RS level was significantly lowered by 15 consecutive days of SG administrations. In addition, up-regulated hepatic inducible nitric oxide synthase and heme oxygenase 1 levels in LPS-treated control rats were significantly lowered and increased, respectively, by 100 mg/kg body weight/day of SG administration. These antioxidant effects were thought to be partially related to the deactivation of nuclear factor-kappaB by SG administration.

Redox factor-1 mediates NF-kappaB nuclear translocation for LPS-induced iNOS expression in murine macrophage cell line RAW 264.7

Redox-sensitive transcriptional regulator redox factor-1 (Ref-1) is induced by oxidative stress and protects cells against it. However, the function of Ref-1 in regulating nitric oxide (NO) synthesis in macrophages has not been defined. We investigated the role of Ref-1 related to the regulation of NO synthesis in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. LPS stimulates the up-regulation and nuclear translocation of Ref-1 in macrophages. Importantly, Ref-1-deficient macrophages using a small interfering RNA did not stimulate inducible NO synthase (iNOS) expression as well as nuclear factor-kappaB nuclear translocation by stimulation with LPS. When the cells were pretreated with diphenyleneiodonium or p47(phox) small interfering RNA for inhibition of NADPH oxidase activity, LPS did not stimulate the nuclear translocation of Ref-1. We next asked whether reactive oxygen species are sufficient for the nuclear translocation of Ref-1 in macrophages. The direct use of H2O2 stimulated the translocation to the nucleus of nuclear factor-kappaB, but not Ref-1 and antioxidant N-acetyl cysteine did not inhibit the LPS-stimulated nuclear translocation of Ref-1. These data suggest that Ref-1 nuclear translocation in LPS-stimulated macrophages requires the activation of other signalling molecules aside from reactive oxygen species followed by the activation of NADPH oxidase.

Peripheral blood leukocyte NO production and oxidative stress in multiple sclerosis

BACKGROUND

The reason for increased peripheral blood leukocyte (PBL) nitric oxide (NO) production in patients with multiple sclerosis (MS) is unknown.

OBJECTIVE

To investigate whether PBL NO production is related to measures of oxidative stress.

METHODS

PBL nitrite, diene conjugates (DC, a measure of undergone oxidative stress), antiradical activity (ARA) and antioxidant acitvity (AOA) were measured in 35 healthy control persons and 80 patients with MS. We investigated the correlation of these measures with a partial correlation analysis, with age as the control variable.

RESULTS

There was a significant correlation in both MS patients and healthy control persons between PBL nitrite levels and PBL DC, ARA and AOA. The correlations were stronger in healthy control persons. An analysis by disease subtype showed that the correlations were present in patients with relapsing-remitting and secondary progressive MS, but absent in primary progressive MS.

CONCLUSIONS

PBL nitrite levels and measures of oxidative stress are closely related in MS-patients as well as in healthy control persons. Increased serum NO levels in MS may be the result of a physiologic reaction to overall oxidative stress. The differences in the strength of correlation between different disease subtypes may reflect differences in leukocyte biology.

Anti-inflammatory activity of c-phycocyanin in lipopolysaccharide-stimulated RAW 264.7 macrophages

C-phycocyanin (C-PC), found in blue green algae, is often used as a dietary nutritional supplement. C-PC has been found to have an anti-inflammatory activity and exert beneficial effect in various diseases. However, little is known about its mechanism of action. Overproduction of nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) plays an important role in the pathogenesis of inflammation. The aim of this study was to determine whether C-PC inhibits production of nitrite, an index of NO, and iNOS expression in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Our results indicated that C-PC significantly inhibited the LPS-induced nitrite production and iNOS protein expression accompanied by an attenuation of tumor necrosis factor-alpha (TNF-alpha) formation but had no effect on interleukin-10 production in macrophages. Furthermore, C-PC also suppressed the activation of nuclear factor-kappaB (NF-kappaB) through preventing degradation of cytosolic IkappaB-alpha in LPS-stimulated RAW 264.7 macrophages. Thus, the inhibitory activity of C-PC on LPS-induced NO release and iNOS expression is probably associated with suppressing TNF-alpha formation and nuclear NF-kappaB activation, which may provide an additional explanation for its anti-inflammatory activity and therapeutic effect.

Age modulates the nitric oxide system response in the ischemic cerebellum

To determine whether age influences the nitric oxide system response to ischemia in the cerebellum, we have analyzed the levels of nitrogen oxides (NOx) and the expression of the different nitric oxide synthase isoforms (NOS) in mature adult (4-5 months old) and aged rats (24-27 months old) subjected to a transient global ischemia/reperfusion (I/R) model. We also analyzed the nitrated proteins and the glial fibrillary acidic protein (GFAP) expression. NOx concentration in adult rats, which more than doubled the values found in the aged rats, decreased after the ischemia and reperfusion. However, in the aged animals, these NOx levels did not significantly change after I/R. Constitutive isoforms were first down-regulated in the ischemic period, in both adult and aged animals. However, after 6 h of reperfusion, these isoforms were up-regulated, but only in aged rats. After I/R, iNOS was up-regulated in adults but down-regulated in the aged rats. Hence, after an episode of transient global ischemia and reperfusion, the aged cerebellum maintains a balanced NO production, silencing the iNOS isoform and inducing a weak expression of nNOS and eNOS; this allows NO physiological functions while avoiding possible undesirable effects such as the nitrative damage or astrocyte activation.

Mediation of aldose reductase in lipopolysaccharide-induced inflammatory signals in mouse peritoneal macrophages

Aldose reductase (AR; AKR1B1) a member of aldo-keto reductase super family, that we had shown earlier mediates cytotoxic signals induced by high glucose, cytokines and growth factors, also mediates the inflammatory signals induced by Gram-negative bacterial endotoxin, lipopolysaccharide (LPS). Inhibition of AR by three distinct AR inhibitors sorbinil, tolrestat or zopolrestat suppressed the LPS-induced production of inflammatory cytokines such as TNF-alpha, IL-6, IL-1beta, IFN-gamma, and chemokine MCP-1 in murine peritoneal macrophages. Inhibition of AR also prevented the production of nitric oxide, and prostaglandin E2 and expression of iNOS and Cox-2 proteins. The LPS-induced DNA binding activity of NF-kappaB and AP1 were significantly inhibited by AR inhibitors, and this effect was mediated through the inhibition of phosphorylation of IkappaB-alpha, IKK alpha/beta and PKC. These results suggest the therapeutic use of AR inhibitors as anti-inflammatory drugs.

Hormonal and spatial regulation of nitric oxide synthases (NOS) (neuronal NOS, inducible NOS, and endothelial NOS) in the oviducts

Nitric oxide (NO) is a free radical produced by the action of NO synthases (NOS) and is known to be involved in the regulation of many reproductive events that occur in the oviducts. The oviducts are highly specialized organs that play crucial roles in reproduction by providing an optimal environment for the final maturation of gametes, fertilization, and early embryo development. In this study, we analyzed the expression, hormonal regulation, and cellular distribution of neuronal, inducible, and endothelial NOS in different bovine oviduct segments to better understand the roles played by these enzymes in oviductal functions in vivo. Quantitative RT-PCR analysis revealed that NOS isoforms are hormonally regulated and differentially expressed along the oviduct throughout the estrous cycle. All NOS were highly expressed around the time of estrus, and immunohistochemistry studies determined that neuronal NOS, inducible NOS (iNOS), and endothelial NOS are differentially distributed in cells along the oviduct. Interestingly, our results showed that estradiol selectively up-regulates iNOS expression in the oviduct during the periovulatory period corresponding to the window of ovulation, oocyte transport, and fertilization. The resulting NO production by this high-output NOS may be of crucial importance for reproductive events that occur in the oviduct. This study provided the first demonstration that NO production is hormonally regulated in the mammalian oviducts in vivo. Our results suggest that neuronal NOS, iNOS, and endothelial NOS contribute to oviductal functions in a timely and site-specific manner.

4-O-methylgallic acid down-regulates endothelial adhesion molecule expression by inhibiting NF-kappaB-DNA-binding activity

We here investigated the functional effect of 4-O-methylgallic acid (4-OMGA), a major metabolite of gallic acid abundant in red wine, on vascular inflammation and its action mechanism. 4-OMGA inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor-alpha (TNF-alpha), resulting in the suppression of leukocyte adhesion to HUVECs. In addition, 4-OMGA inhibited the promoter activities of ICAM-1 and VCAM-1 and the activity of nuclear factor-kappaB (NF-kappaB) without affecting cytosolic IkappaB kinase (IKK) activation, inhibitor of kappaB (IkappaB) phosphorylation and degradation, and nuclear translocation of NF-kappaB. This compound did not alter nitric oxide (NO) generation, but inhibited reactive oxygen species (ROS) production in TNF-alpha-stimulated HUVECs, suggesting that NO and ROS are not involved in 4-OMGA-mediated inhibition of NF-kappaB activity. Moreover, 4-OMGA directly blocked the binding activity of NF-kappaB to its consensus DNA oligonucleotide, when pre-incubated with the nuclear extract from TNF-alpha-stimulated HUVECs, but not with the oligonucleotide alone. This inhibition was completely abolished by the addition of dithiothreitol. 4-OMGA exhibits an anti-inflammatory property by interfering with the formation of the NF-kappaB-DNA complex in the nuclei through direct and redox-sensitive interactions and may play an important role in the prevention of inflammatory responses such as the atherosclerotic process.

Canova, a Brazilian medical formulation, alters oxidative metabolism of mice macrophages

Macrophages play a significant role in the host defence mechanism. When activated they can produce reactive oxygen species (ROS) as well as related reactive nitrogen species (RNS). ROS are produced via NAD(P)H oxidase which catalyzes superoxide (O2-) formation. It is subsequently converted to hydrogen peroxide (H2O2) by either spontaneous or enzyme-mediated dismutation. Nitric oxide synthase (NOS) catalyzes nitric oxide (NO) formation. Canova (CA) is a Brazilian medication produced with homeopathic techniques, composed of Aconitum, Thuya, Bryonia, Arsenicum, Lachesis in distilled water containing less than 1% ethanol. Previous studies demonstrated that CA is neither toxic nor mutagenic and activates macrophages decreasing the tumor necrosis factor-alpha (TNFalpha) production. In this assay we showed that macrophages triggered with Canova increased NAD(P)H oxidase activity as well as that of iNOS, consequently producing ROS and NO respectively. Cytochrome oxidase and peroxisomes activities were inhibited by NO. As NO and O2- are being produced at the same time, formation of peroxynitrite (ONOO-) may be occurring. A potential explanation is provided on how treatment with Canova may enhance immune functions which could be particularly important in the cytotoxic actions of macrophages. CA can be considered as a new adjuvant therapeutic approach to known therapies.

Catalase protects cardiomyocytes via its inhibition of nitric oxide synthesis

Nitric oxide (NO) has been reported to play an important role as an effector molecule in cytokine signal transduction in cardiomyocytes. A treatment of neonatal rat ventricular cardiomyocytes with interleukin-1 beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) induces apoptosis via an NO-dependent pathway. However, cardiomyocytes were more resistant to NO-dependent cell death in the presence of catalase, while producing inducible nitric oxide synthase. This paper reports that catalase stimulates the NF-kappaB-binding affinity. However, the NO synthase activity is abolished by the addition of catalase, suggesting that H(2)O(2) is involved in NO synthesis in a posttranslation state. The catalase-induced inhibition of NO was partially but significantly reversed by H(4)B, an important cofactor of NO synthesis. Treatment of myocytes with IL-1beta, TNF-alpha, and IFN-gamma induced a significant increase in the formation of peroxynitrite, and a pretreatment with catalase was found to quench the production of peroxynitrite. This paper shows that the catalase activity was significantly down-regulated by H(4)B in a concentration-dependent manner. The treatment of H(4)B induced reactive oxygen species (ROS) release in cardiac cell system. These results suggest that catalase interferes with NO and peroxynitrite production as well as with the related apoptosis of cardiomyocytes. This study also shows that the catalase-induced inhibition of NO release may be reversed by H(4)B by the release of ROS.

Inhibition of lipopolysaccharide-induced expression of inducible nitric oxide synthase by phenolic (3E)-4-(2-hydroxyphenyl)but-3-en-2-one in RAW 264.7 macrophages

The large amount of nitric oxide (NO) produced by inducible NO synthase (iNOS) contributes to cellular injury in inflammatory disease. In the present study, a novel synthetic compound (3E)-4-(2-hydroxyphenyl)but-3-en-2-one (HPB) was found to inhibit lipopolysaccharide (LPS)-induced NO generation, but not through the inhibition of iNOS activity, in RAW 264.7 macrophages. Administration of HPB into mice also inhibited the LPS-induced increase in serum nitrite/nitrate levels. To evaluate the underlying mechanisms of HPB inhibition of NO generation, the expression of the iNOS gene in RAW 264.7 macrophages was examined. HPB abolished the LPS-induced expression of iNOS protein, iNOS mRNA and iNOS promoter activity in a similar concentration-dependent manner. LPS-induced nuclear factor-kappaB (NF-kappaB) DNA binding and NF-kappaB-dependent reporter gene activity were both significantly inhibited by HPB. This effect was mediated through the inhibition of inhibitory factor-kappaBalpha (IkappaBalpha) phosphorylation and degradation, and of p65 nuclear translocation. HPB had no effect on the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinases (MAPK), and c-Jun NH(2)-terminal kinase (JNK). However, HPB suppressed the LPS-induced intracellular reactive oxygen species (ROS) production. These results indicate that HPB down-regulates iNOS gene expression probably through the inhibition of LPS-induced intracellular ROS production, which has been implicated in the activation of NF-kappaB.

The activity of inducible nitric oxide synthase in rejected skin xenografts is selectively inhibited by a factor produced by grafted cells

BACKGROUND

Production of nitric oxide (NO) by graft infiltrating macrophages has been suggested as an important effector mechanism of allograft rejection. Expression of the gene for the inducible NO synthase (iNOS) and the production of NO in rejected graft has been demonstrated in various models of allotransplantation. However, whether NO plays a role in rejection of skin xenografts has not been documented.

METHODS

Explants of rejected skin allografts or xenografts (rat to mouse) were cultivated in vitro and the production of NO, interleukin (IL)-2, IL-4, IL-10 and interferon-gamma (IFN-gamma) by graft infiltrating cells was determined by the Griess reaction or ELISA. Effects of supernatants from cultures of xenograft explants on the expression of gene for iNOS, accumulation of iNOS protein and NO production were determined by RT-PCR or Western blots. Molecular mass of the factor with the suppressive activity was characterized by filtration on chromatography Sephacryl S-200 Superfine column. In addition, the effects of 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), a selective iNOS inhibitor, on survival of skin xenografts were tested.

RESULTS

While explants of rejected mouse skin allografts produced substantial amounts of NO, undetectable or only very low levels of NO were found in supernatants from cultured rat skin xenografts. Cocultivation of bacterial lipopolysaccharide (LPS)-stimulated mouse macrophages which produce high quantities of NO, with pieces of rejected xenografts, but not of syngeneic grafts, allografts or normal rat skin, completely inhibited production of NO. Production of IL-6 and IL-10 by LPS-stimulated macrophages was not inhibited under the same conditions. The inhibition of NO production was mediated by a factor which was produced by rejected rat xenograft and which was eluted from chromatography Sephacryl S-200 Superfine column in a fraction representing a molecular mass of 67 kDa. The factor did not inhibit the expression of the gene for iNOS, reduce the level of iNOS protein in stimulated macrophages, or function as a scavenger of NO. Rather, the factor inhibited the function of iNOS. The finding that NO does not play an important role during rejection of skin xenografts is supported by the observation that treatment of graft recipients with AMT, a specific iNOS inhibitor, did not enhance xenograft survival, while the same treatment resulted in prolongation of survival of skin allografts.

CONCLUSION

The results thus demonstrate that a 67-kDa molecule produced by rejected rat skin xenografts selectively inhibits iNOS activity in graft infiltrating macrophages. We suggest that NO does not play a significant role in rejection of skin xenografts as it does in the case of allograft rejection.

Macrophages overexpressing tartrate-resistant acid phosphatase show altered profile of free radical production and enhanced capacity of bacterial killing

Activated macrophages and osteoclasts express high amounts of tartrate-resistant acid phosphatase (TRACP, acp5). TRACP has a binuclear iron center with a redox-active iron that has been shown to catalyze the formation of reactive oxygen species (ROS) by Fenton's reaction. Previous studies suggest that ROS generated by TRACP may participate in degradation of endocytosed bone matrix products in resorbing osteoclasts and degradation of foreign compounds during antigen presentation in activated macrophages. Here we have compared free radical production in macrophages of TRACP overexpressing (TRACP+) and wild-type (WT) mice. TRACP overexpression increased both ROS levels and superoxide production. Nitric oxide production was increased in activated macrophages of WT mice, but not in TRACP+ mice. Macrophages from TRACP+ mice showed increased capacity of bacterial killing. Recombinant TRACP enzyme was capable of bacterial killing in the presence of hydrogen peroxide. These results suggest that TRACP has an important biological function in immune defense system.