Nitric oxide in immunity and inflammation

Endosulfan acute toxicity in Bufo bufo gills: ultrastructural changes and nitric oxide synthase localization

Endosulfan is an organochlorine pesticide used in agriculture for a wide range of crops. Endosulfan concentrations of up to 0.7 mg/L can be found in ponds and streams near sprayed agricultural fields. We investigated the short-term toxicity of endosulfan in common toad (Bufo bufo) tadpoles after 24, 48, and 96 h of exposure. Acute toxicity was evaluated at nominal concentrations ranging from 0.01 to 0.6 mg/L: concentrations that could be found after the application of pesticide. Our results show that 0.43 mg/L of endosulfan caused 50% mortality (LC(50)). The effects of a sublethal endosulfan concentration (0.2mg/L) on gill apparatus morphology were evaluated by scanning and transmission electron microscopy. Immunohistochemical methods were also applied to detect the expression pattern of the inducible isoform of nitric oxide synthase (iNOS) in the gills using the confocal laser scanner microscope. Exposure to 0.2mg/L of endosulfan caused an apparent increase in mucus production, the occurrence of secretory vesicles and lamellar bodies, a widening of intercellular spaces and additionally there was evidence of an inflammatory response in the gill apparatus. The morphological alterations occurred after 24h and were more pronounced after 48 and 96 h of exposure. Altered morphology and increased mucus secretion indicate impaired gas exchange and osmoregulation in the gills. In addition, there was an increase of iNOS expression after 24 and 48 h which may reflect hypoxia and inflammation in the gill epithelium. Our results clearly indicate that short-term exposure to a sublethal concentration of endosulfan, near the high end of the environmental range, disrupts gill morphology and function in B. bufo tadpoles.

Inflammation and lung cancer: roles of reactive oxygen/nitrogen species

The lung is a highly specialized organ that facilitates uptake of oxygen and release of carbon dioxide. Due to its unique structure providing enormous surface area to outside ambient air, it is vulnerable to numerous pathogens, pollutants, oxidants, gases, and toxicants that are inhaled continuously from air, which makes the lung susceptible to varying degrees of oxidative injury. To combat these unrelenting physical, chemical, and biological insults, the respiratory epithelium is covered with a thin layer of lining fluid containing several antioxidants and surfactants. Inhaled toxic agents stimulate the generation of reactive oxygen/nitrogen species (ROS/RNS), which in turn provoke inflammatory responses resulting in the release of proinflammatory cytokines and chemokines. These subsequently stimulate the influx of polymorphonuclear leukocytes (PMNs) and monocytes into the lung so as to combat the invading pathogens or toxic agents. In addition to the beneficial effects, persistent inhalation of the invading pathogens or toxic agents may result in overwhelming production of ROS/RNS, producing chronic inflammation and lung injury. During inflammation, enhanced ROS/RNS production may induce recurring DNA damage, inhibition of apoptosis, and activation of proto-oncogenes by initiating signal transduction pathways. Therefore, it is conceivable that chronic inflammation-induced production of ROS/RNS in the lung may predispose individuals to lung cancer. This review describes the complex relationship between lung inflammation and carcinogenesis, and highlights the role of ROS/RNS in cancer development.

Leishmania chagasi: Cytotoxic effect of infected macrophages on parenchymal liver cells

Leishmania (Leishmania) chagasi, the ethiological agent of New World visceral leishmaniasis, causes morphological and functional injury to the liver. To investigate the role of macrophage-released leishmanicidal factors in hepatocyte damage, we used a co-culture model of hepatocytes and L. chagasi promastigote-infected peritoneal macrophages obtained from C57BL/6 or BALB/c mice. C57BL/6 macrophages killed intracellular parasites more efficiently than BALB/c macrophages, leading to higher number of intracellular amastigotes in the BALB/c culture during the entire course of infection. Early TNF-alpha production led to macrophages activation resulting in parasite growth control. Hepatic transaminases and lactate dehydrogenase were present at high levels in the supernatants of both co-cultures; concurrently, parasites were eliminated from infected macrophages. Nitric oxide production was higher in C57BL/6 co-cultures than in BALB/c co-cultures. Inhibitors of the oxidative burst and secreted proteinases protected hepatocytes against toxicity, and treatment with an inducible nitric oxide synthase inhibitor fully impeded the enzyme release. Our data suggest that the intracellular cytotoxic effects elicited by macrophages for parasite destruction are directly associated with hepatocyte damage, and that nitric oxide plays a pivotal role in this phenomenon.

Orazipone inhibits activation of inflammatory transcription factors nuclear factor-kappa B and signal transducer and activator of transcription 1 and decreases inducible nitric-oxide synthase expression and nitric oxide production in response to inflammatory stimuli

Orazipone [OR-1384; 3-[4-(methylsulfonyl)benzylidene]pentane-2,4-dione] is a novel sulfhydryl-modulating compound that has anti-inflammatory properties in experimental models of asthma and inflammatory bowel disease. In inflammation, inducible nitricoxide synthase (iNOS) generates NO, which modulates the immune response. Compounds that inhibit iNOS expression or iNOS activity possess anti-inflammatory effects. In the present study, we examined the effects of orazipone and its derivative OR-1958 [3-[3-chlorine-4-(methylsulfonyl)benzylidene]pentane-2,4-dione] on iNOS expression and NO production in J774 macrophages stimulated by bacterial lipopolysaccharide (LPS) and in human alveolar epithelial cells activated by proinflammatory cytokines. Protein expression and nuclear translocation of transcription factors were measured by Western blot. iNOS mRNA expression was determined by quantitative reverse transcription-polymerase chain reaction and iNOS mRNA stability by actinomycin D assay. iNOS promoter activity was studied in a cell line expressing luciferase under the control of iNOS promoter. Orazipone and its derivative OR-1958 but not its nonthiol-modulating analog inhibited iNOS expression and NO production in a concentration-dependent manner. Orazipone decreased LPS-induced iNOS mRNA expression, but the decay of iNOS mRNA was not affected. Orazipone extensively prevented LPS-induced activation of nuclear factor kappaB (NF-kappaB) and signal transducer and activator of transcription (STAT) 1, which are important transcription factors for iNOS. In agreement, human iNOS promoter activity was inhibited by orazipone. In conclusion, orazipone decreased activation of inflammatory transcription factors NF-kappaB and STAT1, and expression of iNOS in cells exposed to inflammatory stimuli. The thiolmodulating property seems to be critical in mediating the antiinflammatory effects of orazipone.

iNOS activity is critical for the clearance of Burkholderia mallei from infected RAW 264.7 murine macrophages

Burkholderia mallei is a facultative intracellular pathogen that can cause fatal disease in animals and humans. To better understand the role of phagocytic cells in the control of infections caused by this organism, studies were initiated to examine the interactions of B. mallei with RAW 264.7 murine macrophages. Utilizing modified kanamycin-protection assays, B. mallei was shown to survive and replicate in RAW 264.7 cells infected at multiplicities of infection (moi) of < or = 1. In contrast, the organism was efficiently cleared by the macrophages when infected at an moi of 10. Interestingly, studies demonstrated that the monolayers only produced high levels of TNF-alpha, IL-6, IL-10, GM-CSF, RANTES and IFN-beta when infected at an moi of 10. In addition, nitric oxide assays and inducible nitric oxide synthase (iNOS) immunoblot analyses revealed a strong correlation between iNOS activity and clearance of B. mallei from RAW 264.7 cells. Furthermore, treatment of activated macrophages with the iNOS inhibitor, aminoguanidine, inhibited clearance of B. mallei from infected monolayers. Based upon these results, it appears that moi significantly influence the outcome of interactions between B. mallei and murine macrophages and that iNOS activity is critical for the clearance of B. mallei from activated RAW 264.7 cells.

Synthesis and pharmacological activity of chalcones derived from 2,4,6-trimethoxyacetophenone in RAW 264.7 cells stimulated by LPS: quantitative structure-activity relationships

Inhibition of nitric oxide (NO) production by altering the expression of induced enzymes involved is potentially an important strategy for obtaining antiinflammatory agents. In the search for hits to obtain lead compounds for new drugs of this class, 14 synthetic chalcones derived from 2,4,6-trimethoxyacetophenone were evaluated in terms of their inhibitory action, in vitro, in relation to NO production in murine macrophages of the line RAW 264.7 induced by bacterial lipopolysaccharides (LPS). All the compounds were obtained by aldolic condensation between the acetophenone and corresponding aldehydes, under basic conditions. The mean IC(50) values, calculated through dose versus inhibitory effect curves, in four independent experiments, varied between 1.34 and 27.60microM, and were compared with the positive control, compound 1400W (IC(50)=3.78microM), a highly selective inhibitor of iNOS (induced nitric oxide synthase). Eight chalcones gave mean IC(50) values less than or equal to those obtained for 1400W, which suggests that these molecules may act as inhibitors of inflammatory process. The QSAR study reveals that electron-withdrawing groups in the B-ring seem to increase the inhibition of nitrite production, mainly when in position 2. A substitution in the ortho position of the A-ring seems to be necessary for the activity.

Short-term effects of particulate matter: an inflammatory mechanism?

"Would you tell me please, which way I ought to go from here," asked Alice. "That depends a good deal on where you want to go to," said the cat. (Lewis Carroll, Alice's Adventures in Wonderland) A large number of epidemiological studies show positive correlations between increasing levels of particulate matter (PM) in urban air and short-term morbidity and mortality for diverse acute cardiopulmonary diseases. Brought about by PM increments, inflammation is thought to exacerbate preexisting inflammatory diseases. Experimental evidence suggests a hierarchical oxidative stress model, in which a weakened antioxidant defense, as observed in disease or induced by inhaled particles, increases the PM ability to cause lung inflammation, accounting for exacerbations that occur in asthmatics and in patients with chronic obstructive lung disease. The role of PM-induced inflammation leading to acute cardiovascular events such as arrhythmia, heart failure, and myocardial infarction is more speculative. There is neither clear-cut evidence in humans that inhaled PM could get as far as blood circulation nor that proinflammatory mediators are significantly released from inflamed lung tissues, nor that blood coagulability is critically altered. As a whole, data in humans indicate that short-term inflammatory responses to PM are not always detected; they are usually mild and loosely correlated with functional changes. Among these studies, the diversity of PM characteristics, dose metrics, and endpoints hampers a clear discerning of inflammatory mechanism(s). Thus, the question arises as to whether inflammation represents the mechanism of acute cardiopulmonary PM toxicities in susceptible individuals, or rather an event that may coexist with other relevant mechanism(s). This review article discusses the evidence in humans linking short-term PM increments to inflammation and to exacerbations of cardiopulmonary diseases. Although there is a large amount of data available, there still remains a gulf between the number of epidemiological and panel studies and that of controlled exposures. Research on controlled exposure needs expanding, so that the results of time-series and panel studies will be better understood and short-term standards for human exposure may be more confidently allocated.

Acute immune and non-immune inflammatory response in spontaneously hypertensive rats and normotensive rats. Role of endogenous nitric oxide

The present study investigated the acute inflammatory response (increase in vascular permeability and leukocytes migration) in the pleura of spontaneously hypertensive rats (SHR) and normotensive rats (NTR), using two different stimulus: carrageenan and active anaphylaxis. In addition, the role of endogenous nitric oxide in these responses was investigated.

RESULTS

The inflammatory response induced by intrapleural carrageenan injection in SHR developed similarly to that in NTR. Treatment with L-NAME, reduced the intensity of this response in both groups of rats. The inflammatory response induced by active anaphylaxis in SHR and NTR was different. The increase in vascular permeability occurred later in the SHR compared to NTR. The number of leukocyte present in inflammatory exudates was increased at 4 h in both groups of rats. L-NAME treatment did not inhibit exudation at the intervals under analysis, however, reduced the number of mononuclear cells in the inflammatory exudate of SHR.

CONCLUSION

The development of the inflammatory response in SHR differs from that in NTR, depending on the nature of the inflammatory stimulus. Endogenous NO plays a clear role in carrageenan-induced inflamma-tion, but not in immunologically mediated inflammation in the analyzed period.

Analysis of the inducible nitric oxide synthase gene polymorphisms in Czech patients with atopic diseases

BACKGROUND

Nitric oxide (NO) is an important mediator of physiologic processes in the airways; it plays a significant role in the regulation of the T helper type 1/type 2 balance and contributes to the development of atopic diseases.

OBJECTIVE

We analysed several polymorphisms mainly in the promoter region of the inducible NO synthase (NOS2, iNOS) gene and investigated their associations with asthma and/or atopic phenotypes.

METHODS

We performed a case-control study in 994 subjects (661 patients with atopic disorders, with subgroups of 304 patients with allergic asthma, and 333 healthy individuals), matched for sex, living in the same geographical area. Screening for polymorphisms was performed by combination of PCR and direct sequencing analysis.

RESULTS

We analysed 14 nucleotide sequence variants, seven most common of which were typed in quite large groups of our asthmatic, atopic and control populations. None of these seven frequent polymorphisms was associated with the phenotype bronchial asthma or other atopic diseases. Nevertheless, three from six common promoter polymorphisms showed a significant relation to feather's positivity (P value from 0.01 to 0.03) and the NOS2 608Leu variant was significantly associated with asthma severity [p(corr) = 0.0005; odds ratio (OR) = 5.00, 95% confidence interval (CI): 1.88-13.33]. In haplotype analysis, the most common -2447C/-1659C/-1026G/-0.7del/-277A/Ser608 haplotype was associated with a lower risk of asthma when compared with the common haplotypes with frequency more than 5% (P = 0.01, p(corr) < 0.05; OR = 0.65, 95% CI: 0.56-0.77).

CONCLUSION

Our findings suggest that inducible NOS can play a role in atopic disorders, and several polymorphisms in its gene may be important for asthma protection or susceptibility.

In vitro production of nitrite by low and high density sperm subpopulations of human, bull and ram

The aim of present study was to characterize nitric oxide production via nitrite measurement as its stable metabolite in the different species of spermatozoa (human, bull and ram). Sperm samples were fractionated on the basis of density with the use of a three-layer Percoll gradient. Spermatozoa collected from the various percoll gradient interfaces (50/70 and 70/95%). Results showed that nitrite is produced by human, bull and ram spermatozoa, but in the same sample, there were no significant difference between high density (with higher percentage of motility) sperm subpopulation and low density (with lower percentage of motility) sperm subpopulation Therefore, it seems that spermatozoa with different motility in the one sperm population have the same production of NO in physiological conditionthat is different from pathological condition (e.g., in the subfertile men).

Possible mechanism of acute effect of ethanol on intestinal IgA expression in rat

The purpose of this study was to investigate the possible mechanism of acute effect of ethanol on IgA expression in rat intestine. To this end, adult female Wistar rats showing diestrus day 1 were treated with (a) ethanol (2 or 4 g/kg, i.p.); (b) N omega-nitro-L-arginine-methyl ester (L-NAME), which inhibits the activity of all isoforms of nitric oxide synthase, (30 mg/kg, s.c.) followed by ethanol 3 h later; and (c) L-NAME (30 mg/kg, s.c.) followed by saline 3 h later. Saline-injected and untreated rats were used as controls. The animals were sacrificed 0.5 h after ethanol administration. Intestinal expression of IgA was evaluated by both immunohistochemistry and Western immunoblotting. Morphometric analysis showed that acute ethanol treatment increased the number of IgA-immunoreactive cells in a dose-dependent manner. Pretreatment with L-NAME abolished this action of alcohol. Injection of L-NAME followed by saline had no influence on the number of IgA+cells. The results, obtained by Western immunoblotting, paralleled our immunohistochemical findings. Taken together, these data suggest that acute effect of ethanol on intestinal IgA might be mediated by endogenous nitric oxide.

Bioanalytical profile of the L-arginine/nitric oxide pathway and its evaluation by capillary electrophoresis

This review briefly summarizes recent progress in fundamental understanding and analytical profiling of the L-arginine/nitric oxide (NO) pathway. It focuses on key analytical references of NO actions and the experimental acquisition of these references in vivo, with capillary electrophoresis (CE) and high-performance capillary electrophoresis (HPCE) comprising one of the most flexible and technologically promising analytical platform for comprehensive high-resolution profiling of NO-related metabolites. Another aim of this review is to express demands and bridge efforts of experimental biologists, medical professionals and chemical analysis-oriented scientists who strive to understand evolution and physiological roles of NO and to develop analytical methods for use in biology and medicine.

Nitric oxide mediates prostaglandins' deleterious effect on lipopolysaccharide-triggered murine fetal resorption

Genital tract bacterial infections could induce abortion and are some of the most common complications of pregnancy; however, the mechanisms remain unclear. We investigated the role of prostaglandins (PGs) in the mechanism of bacterial lipopolysaccharide (LPS)-induced pregnancy loss in a mouse model, and we hypothesized that PGs might play a central role in this action. LPS increased PG production in the uterus and decidua from early pregnant mice and stimulated cyclooxygenase (COX)-II mRNA and protein expression in the decidua but not in the uterus. We also observed that COX inhibitors prevented embryonic resorption (ER). To study the possible interaction between nitric oxide (NO) and PGs, we administered aminoguanidine, an inducible NO synthase inhibitor. NO inhibited basal PGE and PGF(2alpha) production in the decidua but activated their uterine synthesis and COX-II mRNA expression under septic conditions. A NO donor (S-nitroso-N-acetylpenicillamine) produced 100% ER and increased PG levels in the uterus and decidua. LPS-stimulated protein nitration was higher in the uterus than in the decidua. Quercetin, a peroxynitrite scavenger, did not reverse LPS-induced ER. Our results suggest that in a model of septic abortion characterized by increased PG levels, NO might nitrate and thus inhibit COX catalytic activity. ER prevention by COX inhibitors adds a possible clinical application to early pregnancy complications due to infections.

Inflammatory effect of endosulfan via NF-κB activation in macrophages

Macrophages are essential for the inflammatory response process because they release a wide variety of proinflammatory mediators. Endosulfan is extremely toxic to invertebrates and has been implicated in various mammalian toxicities. However, its influence on production of cytokine or on the functions of macrophages is unclear. This study examined the effects of endosulfan on the production of nitric oxide (NO) and proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha), and examined the molecular mechanism in macrophages. Exposing macrophages to endosulfan induced the production of NO and proinflammatory cytokines and the expression of these genes. The transient transfection and electrophoretic mobility shift assays with the NF-kappaB binding sites showed that the NF-kappaB transcription factor mediated the endosulfan-induced increase in the expression levels of iNOS and proinflammatory cytokines. These results show that endosulfan stimulates the production of NO and proinflammatory cytokines and can up-regulate the gene expression levels through NF-kappaB transactivation. Overall, these results suggest that endosulfan has inflammatory potential.

A new class of nitric oxide-releasing derivatives of cetirizine; pharmacological profile in vascular and airway smooth muscle preparations

BACKGROUND AND PURPOSE

The pharmacological properties of compounds NCX 1512 and NCX 1514, synthesized by linking the histamine H1-receptor antagonist cetirizine to NO-releasing spacer groups, are reported. The aim was to establish if the compounds retained the antihistamine action of the parent compound, to assess their efficacy as NO donors and to test if they had broader antiallergic activity than cetirizine in the lung.

EXPERIMENTAL APPROACH

Antihistamine activity of NCX 1512 and NCX 1514 was investigated in vitro in the guinea pig ileum, in tracheal rings (GPTR) and lung parenchymal strips (GPLP) of the guinea-pig. The NO-releasing capacity was investigated in vascular preparations; the isolated rabbit and guinea-pig aorta and guinea-pig pulmonary artery. Kinetics of NO release were assessed in a rat whole blood assay.

KEY RESULTS

Both NCX 1512 and NCX 1514 retained activity as H1-receptor antagonists in the guinea pig ileum and airway preparations. The NO-releasing NCX compounds relaxed the rabbit aorta, an action prevented by the guanylyl cyclase inhibitor ODQ (10 microM). NCX 1512 and NCX 1514 did not relax the antigen (ovalbumin) pre-contracted GPTR, whereas the NO donors NCX 2057 and DEA-NONOate relaxed guinea-pig pre-contracted vascular and tracheal preparations. Cetirizine (1-100 microM) and NCX 1512 (1-100 microM) reduced the cumulative (0.01-100 microg ml(-1)) ovalbumin-induced constriction in GPTR, but had no significant effect in GPLP.

CONCLUSIONS AND IMPLICATIONS

NCX 1512 and NCX 1514 act as antihistamines and NO donors. However, there was no improved effect compared to cetirizine on antigen-induced constriction of the central and peripheral lung.

Apolipoprotein E3- and Nitric Oxide–Dependent Modulation of Endothelial Cell Inflammatory Responses

Objective— Although apolipoprotein E3 (apoE3) is known to be atheroprotective, its mechanisms of protection in endothelial cells remain unclear.

Methods and Results— Cultured human aortic endothelial cells were stimulated with tumor necrosis factor (TNF)-α in the presence of human recombinant apoE3 solubilized in dimyristoyl phosphatidylcholine liposomes. Using flow cytometry and real-time polymerase chain reaction, a significant increase of inflammatory cell adhesion proteins (vascular cell adhesion molecule-1 and E-Selectin), and MCP-1, interleukin-8, and intercellular adhesion molecule-1 gene expression was observed within 5 hours of TNF-α exposure, which was markedly attenuated in cells coincubated with apoE3. Treatment with apoE4 resulted in increased inflammatory gene expression relative to either TNF treatment alone or TNF + apoE3 treatment. NO synthase inhibition experiments demonstrated NO to be an active participant in the actions of both TNF and apoE. To clarify the role of NO, dose-response experiments were performed with 0.03 to 300 μmol/L DEA-NONOate. Using flow cytometry and real-time polymerase chain reaction, a modulatory role of NO in TNF-induced endothelial cell activation was observed.

Conclusions— These data suggest a role of vascular wall apoE3 to balance the intracellular redox state in injured endothelial cells via NO-dependent pathways.

The activity of an extract and fraction of Agrimonia eupatoria L. against reactive species

Agrimonia eupatoria L. (agrimony) is a medicinal plant largely used in traditional medicine. Recently, phytochemical studies on an agrimony hydro-alcoholic extract and a polyphenol-enriched fraction obtained from it were carried out. The fraction was found to possess a high concentration of flavan-3-ols, flavonols, flavones and phenolic acids. So, the main purpose of this study was to search out, the extract and fraction antioxidant potential and scavenging activity against the reactive species formed during inflammation and to establish a relationship between such activity and the phenolic composition. Results showed that both the extract and the fraction promptly reacted with DPPH denoting a general radical scavenger activity and a potential antioxidant capacity. They also reacted with superoxide anion, peroxyl and hydroxyl radicals as well as with the oxidant species, hydrogen peroxide, hypochlorous acid and peroxynitrite, strengthening their radical scavenger and antioxidant activities. In most assays, the polyphenol-enriched fraction was more efficient, pointing to a significant contribution of the polyphenols content to those activities. Our data suggest that the significant scavenging capacity of reactive species by polyphenols from Agrimonia eupatoria L., could be a mechanism of its anti-inflammatory activity.

Nitric oxide, a double edged sword in cancer biology: Searching for therapeutic opportunities

Nitric oxide (NO) is a pleiotropic molecule critical to a number of physiological and pathological processes. The last decade has witnessed major advances in dissecting NO biology and its role in cancer pathogenesis. However, the complexity of the interactions between different levels of NO and several aspects of tumor development/progression has led to apparently conflicting findings. Furthermore, both anti-NO and NO-based anticancer strategies appear effective in several preclinical models. This paradoxical dichotomy is leaving investigators with a double challenge: to determine the net impact of NO on cancer behavior and to define the therapeutic role of NO-centered anticancer strategies. Only a comprehensive and dynamic view of the cascade of molecular and cellular events underlying tumor biology and affected by NO will allow investigators to exploit the potential antitumor properties of drugs interfering with NO metabolism. Available data suggest that NO should be considered neither a universal target nor a magic bullet, but rather a signal transducer to be modulated according to the molecular makeup of each individual cancer and the interplay with conventional antineoplastic agents.

Pathways involved in alanyl-glutamine-induced changes in neutrophil amino- and α-keto acid homeostasis or immunocompetence

We examined the effects of DON [glutamine-analogue and inhibitor of glutamine-requiring enzymes], alanyl-glutamine (regarding its role in neutrophil immunonutrition) and alanyl-glutamine combined with L-NAME, SNAP, DON, beta-alanine and DFMO on neutrophil amino and alpha-keto acid concentrations or important neutrophil immune functions in order to establish whether an inhibitor of *NO-synthase [L-NAME], an *NO donor [SNAP], an analogue of taurine and a taurine transport antagonist [beta-alanine], an inhibitor of ornithine-decarboxylase [DFMO] as well as DON could influence any of the alanyl-glutamine-induced effects. In summary, irrespective of which pharmacological, metabolism-inhibiting or receptor-mediated mechanisms were involved, our results showed that impairment of granulocytic glutamine uptake, modulation of intracellular glutamine metabolisation and/or de novo synthesis as well as a blockade of important glutamine-dependent metabolic processes may led to significant modifications of physiological and immunological functions of the affected cells.

Systemic NO production during (septic) shock depends on parenchymal and not on hematopoietic cells: in vivo iNOS expression pattern in (septic) shock

Septic shock is the leading cause of death in noncoronary intensive care units and the 10th leading cause of death overall. Several lines of evidence support an important role for the vasodilator NO in hypotension, a hallmark of septic shock. However, NO may also positively or negatively regulate inflammation, apoptosis, and oxidative stress. These dual effects of NO may relate to its isoform specific production but also to differences in cellular and/or temporal expression. Via bone marrow transplantations, we examined the contribution of hematopoietic cells to the dramatically elevated NO levels seen in (septic) shock. Surprisingly, hematopoietic cells are not responsible at all for the production of circulating NO after systemic tumor necrosis factor or lipopolysaccharide challenge and contribute only marginally in a bacteremic (Salmonella) model of septic shock. Immunohistochemistry identified the nonhematopoietic sources of NO as hepatocytes, paneth cells, and intestinal and renal epithelial cells. In contrast, during granulomatous Bacillus Calmette-Guérin inflammation, the hematopoietic cell population represents the sole source of systemic NO. These mouse data demonstrate that, in contrast to the general conjecture, the dramatically elevated levels of NO during (septic) shock are not produced by hematopoietic cells such as monocytes/macrophages but rather by parenchymal cells in liver, kidney and gut.

NO modulates NADPH oxidase function via heme oxygenase-1 in human endothelial cells

NO is known to induce expression of heme oxygenase-1, an antioxidant enzyme in blood vessels. We tested whether NO might modulate the endothelial NADPH oxidase function via heme oxygenase-1. In human microvascular endothelial cells, the NO donor DETA-NONOate (0.1 to 1 mmol/L) strongly induced expression of heme oxygenase-1 but not Cu/Zn superoxide dismutase. This was associated with a reduction of the superoxide-generating capacity of NADPH oxidase, an effect that depended on de novo gene transcription and heme oxygenase-1 activity. Activation of NADPH oxidase by tumor necrosis factor (TNF) alpha increased generation of reactive oxygen species. DETA-NONOate alone had little effect on TNF-stimulated reactive oxygen species, but it enhanced the TNF response when: (1) heme oxygenase-1 expression was blocked with specific small-interfering RNA; (2) heme oxygenase-1 activity was blocked by zinc-protoporphyrin; or (3) NADPH oxidase activity was blocked by diphenyleneiodonium. Moreover, the heme oxygenase-1 end product bilirubin directly inhibited fully functional NADPH oxidase and seemed to interrupt the assembly and activation of the oxidase. In conclusion, NO may modulate superoxide production by NADPH oxidase in human vascular endothelial cells, at least partly by inducing heme oxygenase-1. Our results indicate that suppression of NADPH oxidase-dependent reactive oxygen species formation may represent a novel mechanism underlying the cardiovascular protective actions of heme oxygenase-1 and bilirubin.

Blood cell NO synthesis in response to exercise

Nitric oxide (NO) is important for the maintenance of cardiovascular homeostasis and is also involved in immunity and inflammation. The aim of our work was to determine the effects of intense exercise on plasma and blood cell NO handling. Nine voluntary male professional cyclists participated in the study. Blood samples were taken in basal conditions and 3h after finishing a mountain cycling stage. Exercise-induced neutrophilia, lymphopenia, and hemolysis. Plasma and erythrocytes maintained basal nitrite levels, whereas neutrophils and lymphocytes decreased nitrite concentration after intense exercise. Basal iNOS levels and SOD activity were similar in neutrophils and lymphocytes. iNOS levels and SOD activity dropped in neutrophils and rose in lymphocytes after exercise. Arginase activity rose only in lymphocytes. Neutrophil nitrite was correlated with SOD activity and iNOS levels, but not in lymphocytes. iNOS levels were correlated with SOD in both neutrophils and lymphocytes. Intense exercise maintained plasma basal arginine and ornithine concentration, and decreased citrulline concentration. Intense exercise induced important changes in NO handling in neutrophils and lymphocytes, yet the basal picture was maintained in erythrocytes.

Evaluation of endothelial and inducible nitric oxide synthase mRNA expression in the lung of broiler chickens with developmental pulmonary hypertension due to cold stress

To clarify the effect of cold-induced pulmonary hypertension on endothelial and inducible nitric oxide synthase (eNOS and iNOS) mRNA expression in the lung of broiler chickens, semi quantitative reverse transcription-PCR was performed on total RNAs isolated from lungs of the broiler chickens exposed to 5 weeks of cold stress. The eNOS gene was expressed increasingly with the increasing age during the rearing period. Comparing the treatment group with its related control group eNOS was expressed significantly only at d 21. Expression of iNOS mRNA also increased in both control and treatment groups with increasing age until d 28 and then decreased at d 35 and 42. Comparing the treatment group with its control group, iNOS mRNA level was significantly higher at 21 d of age in the cold-exposed chickens. It was concluded that, although cold exposure could significantly increase eNOS and iNOS gene expression, cold-induced pulmonary hypertension is not associated with significant variations of eNOS and iNOS expression in the lungs of broiler chickens.

Alterations in selenium status influences reproductive potential of male mice by modulation of transcription factor NFkappaB

Selenium (Se), an essential dietary trace element, is required for the maintenance of male fertility. In order to study its role in spermatogenesis, Balb/c mice with different Se status (Se deficient, group I; adequate, group II and excess, group III) were generated by feeding yeast based Se deficient diet for group I and deficient diet supplemented with Se as sodium selenite at adequate (0.2 ppm) and excess (1 ppm) for group II and III, respectively, for a period of 4 and 8 weeks. Percentage fertility was reduced in group I and III as compared to group II. A significant decrease in Se levels and glutathione peroxidase (GSH-Px) activity were observed in group I animals, whereas increase in GSH-Px activity was seen in group III. Further, significant increase in lipid peroxidation was observed in both Se deficient and excess groups. This indicated that dietary manipulation of Se levels either deficiency or excess leads to increased oxidative stress. Nuclear factor kappa B (NFkappaB), a well-known redox regulated transcription factor has also been suggested to play a crucial role in spermatogenesis. The expression of both p65 and p50 genes (components of NFkappaB) increased in Se deficient group I mice while the expression of the inhibitory IkappaBalpha declined significantly. This indicated activation of NFkappaB in Se deficiency. We also studied iNOS expression, which is a known target gene of NFkappaB, by RT-PCR. Significant elevation in the iNOS levels as well as NO levels was recorded. Both enhanced NO levels and NFkappaB are harmful in the progression of normal spermatogenic cycle. Therefore, present result clearly demonstrates the effect of reduced supply of Se on up-regulation and activation of NFkappaB in testis and its influence on spermatogenesis.

Evidence for a role of inducible nitric oxide synthase in gastric relaxation of mdx mice

Alterations of gastric mechanical activity have been reported in mdx mouse, animal model for Duchenne muscular dystrophy. This study examined if alterations in the vasoactive intestinal polypeptide (VIP) system are present in mdx stomach. Gastric mechanical activity was recorded in vitro as changes of endoluminal pressure and neurally or pharmacologically evoked relaxations were analysed in mdxvs normal stomach. Reverse-transcription polymerase chain reaction was used to detect inducible nitric oxide synthase (iNOS) expression. Relaxations to sodium nitroprusside in mdx stomach showed no difference in comparison with normal preparations. In normal stomach, VIP produced relaxation, which was reduced by VIP6-28, antagonist of VIP receptors, but was not modified by Nomega-nitro-L-arginine methyl ester (L-NAME), 1-H-oxodiazol-[1,2,4]-[4,3-a]quinoxaline-1-one (ODQ) or by N-(3-(aminomethyl)-benzyl)acetamidine (1400W) and aminoguanidine, inhibitors of iNOS. In contrast, in mdx stomach VIP responses were antagonized not only by VIP6-28, but also by L-NAME, ODQ, 1400W or aminoguanidine. In normal stomach, the slow relaxation evoked by stimulation at high frequency was reduced by VIP6-28, but it was unaffected by 1400W or aminoguanidine. In mdx stomach, it was reduced by VIP6-28 or 1400W, which did not show additive effects. iNOS mRNA was expressed only in mdx stomach. The results suggest that in mdx gastric preparations, iNOS is functionally expressed, being involved in the slow relaxation induced by VIP.

Expression of nitric oxide synthase isoforms in the mouse kidney: cellular localization and influence by lipopolysaccharide and Toll-like receptor 4

We determined the cellular mRNA expression of all intrarenal nitric oxide (NO)-producing NO synthase (NOS) isoforms, endothelial NOS (eNOS) and neuronal NOS (nNOS) and inducible NOS (iNOS) in kidneys from wild-type mice (WT) and immune deficient Toll-like receptor 4 (TLR4) mutant mice, during normal physiological conditions and during a short-term (6-16 h) endotoxic condition caused by systemically administered lipopolysaccaride (LPS). Investigations were performed by means of in situ hybridization and polymerase chain reaction amplification techniques. In WT, LPS altered the expression rate of all intrarenal NOS isoforms in a differentiated but NOS-isoform coupled expression pattern, with iNOS induction, and up- and down-regulation of the otherwise constitutively expressed NOS isoforms, e.g. eNOS and nNOS and an iNOS isotype. In TLR4 mutants, LPS caused none or a lowered iNOS induction, but altered the expression rate of the constitutive NOS isoforms. It is concluded that the intrarenal spatial relation of individual NOS-isoforms and their alteration in expression provide the basis for versatile NO-mediated renal actions that may include local interactions between NOS isoforms and their individual NO-target sites, and that the NOS-isoform dependent events are regulated by TLR4 during endotoxic processes. These regulatory mechanisms are likely to participate in different pathophysiological conditions affecting NO-mediated renal functions.

Nitric oxide inhibits T cell adhesion and migration by down-regulation of β1-integrin expression in immunologically liver-injured mice

Our previous study has reported that nitric oxide (NO) exerts a protective role in immunologically liver-injured mice induced by delayed-type hypersensitivity to picryl chloride. To explore the mechanism of the protection, we have now examined the effect of NO on T cell adhesion and migration. First, we isolated hepatocytes and nonparenchymal cells from the liver-injured mice and separated the nonparenchymal cells into Kupffer cell-enriched and lymphocyte-enriched populations. When these hepatocytes or the fractions of nonparenchymal cells were co-cultured with spleen T cells of the liver-injured mice in a Transwell system, the adhesive potential of the T cells was significantly inhibited in the presence of hepatocytes or the Kupffer cell-enriched population but not the lymphocyte-enriched population of nonparenchymal cells. This effect was dependent on NO production. The NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) could reverse this inhibition of cell adhesion and also decrease NO production. To confirm this effect of NO on T cells, we further examined the role of exogenous or endogenous NO on the adhesive activity of the Jurkat T cell line. As a result, the NO donor, S-nitroso-N-acetyl penicillamine (SNAP) caused a dose-dependent inhibition of the adhesion of Jurkat T cells. Furthermore, the binding ability of Jurkat T cells to collagen decreased gradually after co-incubation with macrophages stimulated by LPS+IFN-gamma, an effect which correlated well with the increasing NO level in the medium. Such opposite changes in cell adhesion and in NO production were also markedly reversed by L-NMMA. Moreover, treatment with SNAP reduced adhesion, transmigration, matrix metalloproteinase-9 production and beta1-integrin expression of spleen T cells of the liver-injured mice. Taken together, these findings suggest that NO can function as a down-regulator of T cell mobility, which might be one of the mechanisms by which NO exerts its protective effect in T cell-mediated liver injury.

Nitric oxide and polyamine pathway-dependent modulation of neutrophil free amino- and α-keto acid profiles or host defense capability

We have examined the effects of N(omega)-nitro-L-arginine-methylester-hydrochloride [L-NAME; inhibitor of nitric oxide synthase], S-nitroso-N-acetyl-penicillamine [SNAP; nitric oxide donor], alpha-difluoro-methyl-ornithine [DFMO; inhibitor of ornithine decarboxylase] arginine or ornithine as well as the combination of arginine or ornithine with L-NAME, SNAP or DFMO on intracellular free amino- and alpha-keto acid profiles and the immune function markers superoxide anion and hydrogen peroxide generation as well as released myeloperoxidase activity in neutrophils (PMN). Although the underlying mechanisms still remain unclear, we believe from our results that nitric oxide as well as polyamine-dependent pathways are involved in the signal transmission of free radical molecule, beneficial nutritional therapy or maleficient pharmacological stress-induced alterations in PMN nutrient composition. Relevant changes in intragranulocyte free amino- and alpha-keto acid homeostasis and metabolism, especially, may be one of the determinants in PMN nutrition that positively or negatively influences and modulate neutrophil host defence capability and immunocompetence.

LightUp probes in clinical diagnostics

The LightUp^® Probe technology has now matured and reached the phase where it has been implemented in commercial reagent kits, i.e. the ReSSQ^® product line. Several properties of the LightUp^® probes make them particularly suitable for clinical settings. For instance, extraordinary shelf life and a chemical stability that allows convenient fridge storage. The origin of the higher stability of LightUp^® probe kits compared to others, based on alternative probe technologies, is partly the relatively good stability of cyanine dyes but also the resistance towards nucleases and proteases of the synthetic DNA analogue peptide nucleic acid that is used as the sequence recognizing element in LightUp probes. It is clear from recent trends in the PCR amplification hardware technology that the instrumentation is becoming more flexible and less adapted for dedicated probe chemistries. This will pave the way for increased standardization in the field of DNA diagnostics and the development of cross-platform assays.

In the present review the LightUp technology will briefly be presented and discussed. The utility of the technology will be illustrated by examples from cytomegalovirus quantification and monitoring of the viral load of the SARS Coronavirus. An example of cancer diagnostics by detection of altered gene expression patterns will also be shown.

Glucosamine abrogates the acute phase of experimental autoimmune encephalomyelitis by induction of Th2 response

Glucosamine, a natural glucose derivative and an essential component of glycoproteins and proteoglycans, has been safely used to relieve osteoarthritis in humans. Recent studies have shown that glucosamine also possesses immunosuppressive properties and is effective in prolonging graft survival in mice. Whether this reagent is effective in human multiple sclerosis (MS), an inflammatory demyelination in the CNS, is not known. We thus investigated the therapeutic effect of glucosamine on experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We demonstrated that oral, i.p., or i.v. administration of glucosamine significantly suppressed acute EAE, with reduced CNS inflammation and demyelination. A significant, albeit not strong, blockade of Th1 response and an up-regulation of Th2 cytokines (IL-5 and IL-10) are observed in the splenocytes of glucosamine-treated mice. Glucosamine also regulates IL-5 and IL-10 in vitro. As glucosamine is able to effectively suppress acute EAE, has low or absent toxicity, and has been safely used in humans orally, our study suggests a potential use for this drug alone or in combination with other disease-modifying immunotherapies to enhance their efficacy and reduce their doses in MS and possibly other autoimmune disorders. Furthermore, because glucosamine functions not simply as an immunosuppressant, but as a mild immunomodulator, administration of glucosamine provides a novel immunoregulatory approach for autoimmune disorders.

Effects of ultrasound and diclofenac phonophoresis on inflammatory pain relief: suppression of inducible nitric oxide synthase in arthritic rats

BACKGROUND AND PURPOSE

The direct effects of ultrasound (US) and phonophoresis of a nonsteroidal anti-inflammatory drug (NSAID) on injured peripheral tissue have been widely investigated, but evidence concerning the effects of central spinal nociceptive modulation seems to be lacking. The purpose of this study was to investigate the peripheral influences of US and phonophoresis on the modulation of spinal inducible nitric oxide synthase (iNOS) expression elicited by hind paw stimulation with an ankle injection of complete Freund adjuvant (CFA).

SUBJECTS AND METHODS

Inflammatory arthritis was induced in 18 male Wistar rats with intra-articular tibiotarsal injections of CFA. Serial changes in inflammatory pain reactions, including hind-limb edema, and the locomotor activity of the arthritic animals were measured. Arthritic rats underwent US (n=6), diclofenac phonophoresis (n=6), or sham treatment (n=6) on the CFA-injected leg at 18 hours after injection. At 20 hours after injection, spinal inducible nitric oxide synthase-like immunoreactive (iNOS-LI) cells were examined.

RESULTS

Following the CFA injection, all animals' paw diameters and ankle circumferences ipsilateral to the injected leg were significantly increased compared with the values prior to injection. The rearing behavior of arthritic animals had improved significantly after US and diclofenac phonophoresis treatments. The mean total number (+/-SD) of iNOS-LI cells per section of segments L1 and L2 of the bilateral spinal cord of the sham treatment, US, and phonophoresis groups were 531.20+/-6.11, 124.20+/-4.09, and 114.80+/-3.23, respectively. The total numbers of iNOS-LI cells in rats treated with US and diclofenac phonophoresis were significantly smaller than in those receiving sham treatment. There were no significant differences in the total number of iNOS-LI cells ipsilateral to the injected leg between the US and diclofenac phonophoresis groups.

DISCUSSION AND CONCLUSION

Ultrasound and phonophoresis treatments probably modulate and prevent the CFA-insult-induced increase in total and regional iNOS-LI neurons. Peripheral use of diclofenac phonophoresis offers little advantage over US alone in affecting the central mechanisms of nociception. The peripheral influences of US and phonophoresis on the central modulation of the spinal nociceptive processing system are important and may reflect the work being done through the neuroplasticity of spinal cord in response to peripheral input of US and phonophoresis.

GW274150, a novel and highly selective inhibitor of the inducible isoform of nitric oxide synthase (iNOS), shows analgesic effects in rat models of inflammatory and neuropathic pain

Nitric oxide (NO), synthesised by different isoforms of nitric oxide synthase (NOS), has been linked with the development and maintenance of nociception. We studied the role of the inducible isoform, iNOS, in two different rat pain models with an inflammatory component. iNOS was immunohistochemically detected locally in the paw 6h after Freund's Complete Adjuvant (FCA) injection, showing a plateau at 24-72 h and falling slowly in the following weeks. This correlated with the late phase of the hypersensitivity to pain revealed in the behavioural tests. A highly selective iNOS inhibitor GW274150 (1-30 mg/kg orally, 24h after FCA) suppressed the accumulation of nitrite in the inflamed paw indicating substantial iNOS inhibition. At the same time it partially reversed FCA-induced hypersensitivity to pain and edema in a dose-dependent manner. After Chronic Constriction Injury (CCI) surgery to the sciatic nerve, iNOS presence was only detected locally in the region of the nerve (inflammatory cells). GW274150 (3-30 mg/kg orally, 21 days after surgery) also reversed significantly the CCI-associated hypersensitivity to pain. No iNOS was detectable in dorsal root ganglia, spinal cord or brain in either model. This study demonstrates a role for peripherally-expressed iNOS in pain conditions with an inflammatory component and the potential value of iNOS inhibitors in such conditions.

Exhaled nitric oxide in paediatric asthma

Assessment of airway function is difficult in young children with asthma, and in addition, only reflects the status of the disease at the time of the measurement. Thus, there is increasing interest in monitoring airway inflammation in asthma, which may provide a longer term assessment of disease activity. Most methods of assessing asthmatic inflammation are invasive, and are not feasible in the paediatric population. This review discusses exhaled nitric oxide as a marker of asthmatic inflammation, and compares it with other recognized markers. Exhaled nitric oxide has the potential to become a noninvasive method of assessing asthma control in the paediatric population.

Levels of endothelial and platelet microparticles and their interactions with leukocytes negatively correlate with organ dysfunction and predict mortality in severe sepsis

OBJECTIVE

Mortality in sepsis is believed to be associated with exaggerated inflammatory responses, but recent evidence suggests that poor outcome is associated with reduced inflammation. To test this hypothesis, we measured several inflammatory markers to determine whether any of them or any combinations are associated with mortality or organ dysfunction.

DESIGN

Clinical study.

SETTING

School of medicine.

PATIENTS

Thirty-five patients with severe sepsis.

INTERVENTIONS

Markers of endothelial, platelet, and leukocyte activation were measured on days 1, 2, and 3 after enrollment. The markers were a) endothelial microparticles (EMPs) and their conjugates with monocytes (EMP/MONO); b) platelet microparticles (PMPs) and platelet activation marker CD62P; c) platelet-leukocyte conjugates (PLT/LEU) and leukocyte activation marker CD11b; and d) intracellular nitric oxide in leukocytes.

MEASUREMENTS AND MAIN RESULTS

The 28-day mortality rate was 51% (18 of 35). Significant differences between survivors and nonsurvivors on day 1 were found in PLT/LEU (p = .001), CD11b (p = 0.02), and EMP/MONO (p = .02) groups. Using logistic regression to assess if these markers predict mortality on day 1, we found that PLT/LEU had the best predictive value among the markers used (area under receiver operating characteristics curve = 0.82). All markers of cell activation and inflammation were significantly higher among survivors on days 2 and 3, except nitric oxide, which was lower. This marker showed significant negative correlation with the Sequential Organ Failure Assessment score throughout the study.

CONCLUSIONS

Our data support the hypothesis that early increased, not decreased, inflammatory response as measured by our markers is associated with improved survival rate. A high negative correlation was found between some of these markers and Sequential Organ Failure Assessment score.

Biodegradable microspheres alone do not stimulate murine macrophages in vitro, but prolong antigen presentation by macrophages in vitro and stimulate a solid immune response in mice

The purpose of this study was to analyze the potential of various types of biodegradable microspheres (MS) (i) to activate in vitro cell line-derived macrophages (RAW 264.7, Mphi), and primary peritoneal and bone marrow-derived mouse Mphi, to prolong the release and presentation of microencapsulated synthetic malaria antigens by Mphi after uptake of antigen-loaded MS, and (ii) to stimulate an immune response in mice against a microencapsulated synthetic malaria antigen. The MS were made of various types of poly(lactide-co-glycolide) (PLGA) or chitosan cross-linked with tripolyphosphate. PLGA, but not chitosan MS, were efficiently ingested by Mphi. Upon exposure to the various MS types, Mphi increased only the production of reactive oxygen intermediates (ROI), while the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), and the expression of cyclooxigenase-2 (COX-2), inducible NO synthase (iNOS), the cell surface markers MHC class I and II, and CD 86 remained unaffected. In vitro release of the microencapsulated antigen from PLGA50:50 MS followed a pulsatile pattern and extended over 14 weeks. This prolonged antigen release was also mirrored in the significantly prolonged antigen presentation over more than 7 days by Mphi after uptake of antigen-loaded PLGA MS. Finally, antigen-loaded PLGA MS induced a solid immune response in mice after a single s.c.-injection, which was only slightly inferior to the antibody titers measured with the control formulation with Montanide ISA720. These results suggest that MS are well tolerated by Mphi. The prolonged antigen presentation by Mphi, as measured in vitro, along with the capacity to induce a strong immune response in animals emphasize that biodegradable MS are a very promising delivery system for both preventive and immunotherapeutic vaccines.

Polymorphisms of chemokine receptors and eNOS in Brazilian patients with sickle cell disease

Sickle cell disease (SCD) is an inherited disorder that presents extremely variable clinical manifestations. For the past few decades, it has been approached as an inflammatory disorder, and several researchers have tried to determine the factors involved in such characteristic. In order to contribute to the identification of the genetic differences underlying this phenotypic diversity in SCD, we proposed to study the distribution of polymorphic variants of the genes encoding the chemokine receptors CCR2 and CCR5, as well as three polymorphisms in the NOS3 gene, in Brazilian SCD patients. These genes are involved in the development of inflammatory immune reactions, a feature believed to be of extreme importance in SCD pathology. Our results indicate that the polymorphisms studied here are not directly associated with severe clinical manifestations in SCD patients. Nevertheless, we observed a tendency for the development of a severe clinical course in carriers of the variant alleles CCR2-64I and CCR5delta32 and in homozygotes for the -786C variant of the NOS3 gene. Further studies should be carried out in order to assess the role of such variants in the clinical picture of SCD.

Molecular mechanisms involved in enhancing HO-1 expression: de-repression by heme and activation by Nrf2, the "one-two" punch

Heme oxygenase (HO)-1 is a stress response protein, which confers cytoprotection against oxidative injury and provides a vital function in maintaining tissue homeostasis. Molecular mechanisms involved in the inducible transcription of ho-1 occurring in response to numerous and diverse stressful conditions have remained elusive. Since the discovery of E1 and E2, the two upstream enhancers regulating induction of ho-1 transcription in 1989, there have been many studies dealing with molecular mechanisms involved in enhancing HO-1 expression. In this commentary, recent advances in our understanding of the mechanisms involved in the induction of HO-1 expression in mammalian cells are summarized with some supportive results reported by others. Currently available data indicate that activation of ho-1 transcription involves both the heme (native substrate)-dependent selective alleviation of repressor and the oxidative stress-dependent activation of transcriptional activator. The stress-released free-heme (HO-1 substrate) from hemoproteins involved in causing oxidative stress itself appears to act as a molecular switch controlling the repressor- activator antagonism on the enhancer sequences of ho-1. Thus, induction of HO-1 appears to operate in a manner like a simple feedback loop. dox Signal. 7, 1674-1687.

Overexpression of inducible nitric oxide synthase and cyclooxygenase-2 in rat zinc-deficient lung: Involvement of a NF-kappaB dependent pathway

Reactive oxygen and nitrogen species have been implicated in the pathogenesis of pulmonary diseases. The goal of this study was to measure the response of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 enzymes (COX-2) in lung with moderate zinc deficiency. Adult male Wistar rats were divided into two groups receiving (1) a zinc-deficient diet (ZD) or (2) a zinc-adequate control diet. After 2 months of treatment, the zinc-deficient group showed a significant pulmonary edema. This was associated to a reduction of protein thiols and to a significant increase of metallothionein and glutathione disulfide levels. In addition, a higher serum and lung NO production in ZD group was positively related to the higher activity and expression of iNOS and COX-2 found in lungs. Western blot analysis revealed increased IkappaBalpha degradation, an indicator of NF-kappaB activation in ZD lungs. Anatomopathologic analysis of ZD lungs showed an increase of connective tissue fibers with an influx of polymorphonuclear cells. These cells and type II cells from the alveoli showed specific immunohistochemical signals for iNOS. The conclusion is that, during the development of zinc-deficiency, iNOS activity increases in lung and contributes to lung injury. Zinc deficiency implications must be taken into account to design therapies and public health interventions involving targeted zinc supplementation for high-risk subjects or certain diseases, such as asthma.

Pro-inflammatory effect of Arum maculatum lectin and role of resident cells

Arum maculatum agglutinin (AMA) is a monocot lectin isolated from tubers of Arum maculatum L. (Araceae) which exhibits different specificity towards oligo-mannosidic-type and N-acetyllactosaminic-type glycans. We have investigated the effect of this lectin on the cells of the immune system. Models of neutrophil migration in vivo, neutrophil chemotaxis in vitro and macrophage cultures were used to study the lectin inflammatory activity. When administered into rat peritoneal cavities, AMA (80, 200 and 500 microg/mL/cavity) induced significant and dose-dependent neutrophil migration. This effect was inhibited by incubation with alpha-methyl-d-mannoside. A 83% depletion in the number of resident cells following peritoneal lavage did not reduce the AMA-induced neutrophil migration, as compared to sham animals (not washed). However, pre-treatment with 3% thioglycolate which increases the peritoneal macrophage population by 236%, enhanced the neutrophil migration induced by AMA (200 microg/mL/cavity) (119%, p < 0.05). Reduction of peritoneal mast cell population by chronic treatment of cavities with compound 48/80 did not modify AMA-induced neutrophil migration. The neutrophil chemotaxy assay in vitro shows that the lectin (300 microg/mL) induces neutrophil chemotaxy (368% p < 0.05) compared to RPMI. Finally, injection into peritoneal cavities of supernatants from macrophage cultures obtained after stimulation with AMA (300 microg/mL) enhanced neutrophil migration (110% p < 0.05). Summarizing, our data suggest that A. maculatum agglutinin presents pro-inflammatory activity, inducing neutrophil migration by two ways, one which is independent on resident cells and another one dependent on the presence of these cells.

Methoxychlor-induced inducible nitric oxide synthase and proinflammatory cytokines expression in macrophages via NF-κB, ERK, and p38 mitogen-activated protein kinases

Methoxychlor (MXC) is a pesticide that was developed as a replacement for dichlorodiphenyltrichloroethane. The influence of MXC on cytokine production or the functions of macrophages is unclear. This study examined the effects of MXC on the production of nitric oxide (NO) and the proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), and analyzed the molecular mechanism in mouse macrophages. The addition of MXC to macrophages induced the production of NO and proinflammatory cytokines and expression levels of these genes in a dose-dependent manner. The NF-kappaB sites were identified in the promoter of the iNOS and proinflammatory cytokines genes. The transient expression and electrophoretic mobility shift assays revealed that the NF-kappaB transcription factor mediated the MXC-induced increase in the iNOS and proinflammatory cytokines expression levels. In addition, MXC induced the rapid phosphorylation of the ERK1/2 and p38 MAPK. This demonstrates that MXC stimulates the production of NO and proinflammatory cytokines and can up-regulate the expression levels of these genes via NF-kappaB transactivation and ERK1/2 and p38 MAPK phosphorylation. Overall, this study provides evidence showing that MXC has inflammatory potential that is previously unrecognized immunomodulating activity.

Inhibition of nitric-oxide synthase enhances antigen-induced contractions and increases release of cysteinyl-leukotrienes in guinea pig lung parenchyma: nitric oxide as a protective factor

Nitric oxide (NO) in exhaled air is a biomarker of airway inflammation. However, the role of NO in the peripheral lung is not known. The aim of this study was to determine the role of endogenous NO in antigen-induced contractions of ovalbumin (OVA)-sensitized guinea pig lung parenchyma (GPLP). The contraction in this in vitro model of the peripheral lung closely resembles the corresponding response in human airways. Cumulatively increasing concentrations (10-10,000 microg/l) of OVA induced concentration-dependent contractions of the GPLP that were enhanced by the NO synthase (NOS) inhibitors N(omega)-nitro-L-arginine (L-NOARG; 100 microM), N(omega)-monomethyl-L-arginine (100 microM), N(omega)-nitro-L-arginine methyl ester (100 microM), and N-(3-(aminomethyl)benzyl)acetamidine (1400W; 1 microM). The enhancement induced by L-NOARG was reversed by coadministration with the 5-lipoxygenase inhibitor (R)-2-[4-(quinolin-2-yl-methoxy)phenyl]-2-cyclopentyl acetic acid (BAY x1005; 3 microM), whereas coadministration of L-NOARG with the cyclooxygenase inhibitor indomethacin (10 microM) did not change the effect of L-NOARG alone. L-NOARG (100 microM) did not affect the cumulative concentration-response relations for either leukotriene (LT) D4 (0.1-100 nM) or histamine (1-30 microM). The NO donor NONOate (0.001-100 microM) was ineffective in GPLP but potently relaxed precontracted guinea pig pulmonary artery. Furthermore, L-NOARG enhanced the release of LTE4 and decreased the release of prostaglandin E2 induced by OVA. In conclusion, endogenous NO exerts an inhibitory effect on antigen-induced contractions in the peripheral lung. The action of NO apparently involves inhibition of the release of mediators rather than direct relaxation of airway smooth muscle. The findings support the belief that endogenous NO has a protective anti-inflammatory effect in the airways.

Inducible nitric oxide synthase links NF-kappaB to PGE2 in polyunsaturated fatty acid altered fibroblast in-vitro wound healing

BACKGROUND

This study investigated mechanisms of altered fibroblast collagen production induced by polyunsaturated fatty acids. 3T3-Swiss fibroblasts were grown in medium containing either eicosapentaenoic or arachidonic acid. The effects of nuclear factor-kappaB activation by lipopolysaccharide on inducible nitric oxide synthase, nitric oxide, prostaglandin E2, collagen production, and in-vitro wound healing were studied.

RESULTS

Eicosapentaenoic acid treated cells produced less prostaglandin E2 but had increased inducible nitric oxide synthase expression, nitric oxide production, collagen formation, and recoverage area during in-vitro wound healing than cells treated with arachidonic acid. Activation of nuclear factor-kappaB with lipopolysaccharide increased inducible nitric oxide synthase expression, the production of nitric oxide, prostaglandin E2, collagen, and the in-vitro wound recoverage area. The nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester, decreased lipopolysaccharide-induced nitric oxide, but the amount of nitric oxide was greater in eicosapentaenoic acid treated cells. NG-nitro-L-arginine methyl ester plus lipopolysaccharide treatment increased collagen production and cellular recoverage area while treatment with NG-nitro-L-arginine methyl ester alone decreased it in wounded fibroblasts.

CONCLUSION

The activation of the NF-kappaB pathway and PGE2 can be linked by the cross-talk of iNOS and NO in the PUFA altered fibroblast collagen production and wound healing. Additional studies are needed to determine how polyunsaturated fatty acids can be used as adjuvants in combination with other treatments (i.e, drugs) to design therapies to either enhance healthy collagen production or inhibit production and reduce fibrosis.

Reduction in Induced Pain by Ultrasound May Be Caused by Altered Expression of Spinal Neuronal Nitric Oxide Synthase-Producing Neurons

OBJECTIVE

To examine the peripheral influence of therapeutic ultrasound (US) on central spinal nociceptive modulation.

DESIGN

Controlled, experimental animal trial.

SETTING

Neuroscience laboratory of a medical university in Taiwan.

ANIMALS

Ten male Wistar rats weighing 250 to 300 g.

INTERVENTION

To induce inflammatory arthritis, the rats were injected intracapsularly with complete Freund's adjuvant (CFA) into the right tibiotarsal joint. Eighteen hours later, at the inflammatory phase of arthritis, US or sham-operated treatment was applied to the arthritic limb.

MAIN OUTCOME MEASURES

The numbers and distributional proportions of immunoreactive spinal neuronal nitric oxide synthase-like (nNOS-LI) neurons were assessed.

RESULTS

The nNOS-LI neurons were abundant bilaterally in the L1 and L2 regions of the spinal cord areas after CFA-induced arthritis with sham-operated treatment. US treatment significantly suppressed this increase in the numbers of nNOS-LI neurons bilaterally in the superficial laminae (laminae I-II, P < .001), nucleus proprius (laminae III-IV, P < .01), deep laminae (laminae V-VI, P < .001), and ventral horn (laminae VII-X, P < .001) of the spinal cord. When expressed as a percentage of the total labeled cells, the proportions of nNOS-LI neurons showed significant differences in laminae III-IV (P < .001) and laminae V-VI (P < .01) between sham-treated rats and those treated with US.

CONCLUSIONS

US treatment may modulate the CFA insult-induced increase in total and regional nNOS-LI neurons. I propose that the peripheral influences of US on central modulation of the spinal nociceptive processing system is important and may reflect the neuroplasticity of the spinal cord in response to peripheral input.

Reciprocal changes in endothelium-derived hyperpolarizing factor- and nitric oxide-system in the mesenteric artery of adult female rats following ovariectomy

1. To explore the effects of estrogen on arterial functions, we examined endothelium-derived hyperpolarizing factor (EDHF)- and NO-mediated responses in isolated mesenteric arteries of female rats, 4 weeks after sham-operation (CON), ovariectomy (OVX) and OVX plus chronic estrogen treatment (OVX+E(2)). Tissue levels of connexins-40, 43 (major components of gap junction), inducible NOS (iNOS), endothelial NOS (eNOS) and eNOS regulator proteins such as calmodulin, heat shock protein 90 (hsp90) and caveolin-1 were also examined using Western blot. 2. In OVX, acetylcholine (ACh)-induced EDHF-mediated relaxation and membrane hyperpolarization of arterial smooth muscles were reduced, whereas ACh-induced NO-mediated relaxation was enhanced, leading to no change in ACh-induced relaxation. 3. In OVX, connexin-40 and 43 were decreased. Tissue levels of eNOS and its positive regulators (calmodulin and hsp90) were unchanged, but that of its negative regulator, caveolin-1, was decreased. The levels of iNOS in mesenteric artery and aorta and plasma levels of NO metabolites and cholesterol were elevated. 4. In OVX, contraction of the artery by phenylephrine was reduced, but augmented by nonspecific inhibitor of NOS to the comparable level as that in CON group. The contraction in OVX group unlike that in CON group was augmented by specific iNOS inhibitor, and the difference between contractions in the presence of nonspecific and specific inhibitor as an index of eNOS activity was increased. 5. In OVX+E(2), all these changes were recovered. 6. In all groups, EDHF-mediated relaxation was suppressed by 18beta-glycyrrhetinic acid, an inhibitor of gap junction. 7. These results indicate that estrogen deficiency does not change the diameter of mesenteric artery: it reduces EDHF-mediated relaxation by decreasing gap junction, whereas it augments NO-mediated relaxation via an increase in NO release. Increased NO result from increased activity of eNOS subsequent to a decrease in caveolin-1 and from induction of iNOS. However, excessive NO generation with elevated plasma cholesterol would raise a risk for atherosclerosis.

Different sensitivity of lamina propria T-cell subsets to nitric oxide-induced apoptosis explains immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine in rodent colitis

BACKGROUND & AIMS

Uncontrolled T-cell activation plays a critical role in the pathogenesis of inflammatory bowel diseases. Therefore, pharmacological strategies directed toward restoring the normal responsiveness of the immune system could be effective in the treatment of these pathologic conditions. The addition of a nitric oxide-releasing moiety to conventional drugs, such as aspirin and other anti-inflammatory analgesic drugs, results in new chemical entities with potent immunomodulatory activities. The aim of this study was to investigate the immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine (NCX-456), as compared with standard mesalamine, in 2,4,6-trinitrobenzene sulfonic acid-induced colitis in mice.

METHODS

Cells and tissues from mice with 2,4,6-trinitrobenzene sulfonic acid-induced colitis and from interleukin 10-deficient mice with spontaneous chronic colitis receiving treatment with several doses of NCX-456 or mesalamine were analyzed for morphology, cytokine production, and apoptosis.

RESULTS

NCX-456, but not mesalamine, administration resulted in a marked reduction in clinical, histological, and immunologic signs of colitis in both models. NCX-456 inhibited the release of T-helper type 1-derived cytokines and increased the release of the regulatory T cell-derived cytokines interleukin 10 and transforming growth factor beta. In vitro analyses showed that NCX-456 inhibited proliferation and caused selective apoptosis of the subset of activated lamina propria T-helper type 1 cells, whereas it was ineffective for regulatory T-cell function and survival.

CONCLUSIONS

Collectively, these data show that NCX-456 inhibits lamina propria T-helper type 1 function and stimulates the activity of interleukin 10- and transforming growth factor beta-secreting cells, thus restoring mucosal immune homeostasis and suppressing intestinal inflammation.