Synthesis of nitric oxide from L-arginine: a recently discovered pathway induced by cytokines with antitumour and antimicrobial activity

L-Arginine and immune modulation: A pharmacological perspective on inflammation and autoimmune disorders

L- Arginine (2-Amino-5-guanidinovaleric acid, L-Arg) is a semi-essential amino acid that is mainly produced within the urea cycle. It acts as a key precursor in the synthesis of proteins, urea, creatine, prolamines (including putrescine, spermine, and spermidine), proline, and nitric oxide (NO). WhenL-Arg is metabolized, it produces NO, glutamate, and prolamines, which all play important regulatory roles in various physiological functions. In addition to its metabolic roles,L-Arg significantly influences immune responses, especially in the context of inflammation and autoimmune diseases. It affects the activity of immune cells by modulating T-cell function, the polarization of macrophages, and the release of cytokines. Importantly,L-Arg plays a dual role in immune regulation, functioning as both an immunostimulatory and immunosuppressive agent depending on the specific cellular and biochemical environments. This review examines the immunopharmacological mechanisms of L-Arg, emphasizing its involvement in inflammatory responses and its potential therapeutic uses in autoimmune conditions like rheumatoid arthritis, multiple sclerosis, and inflammatory bowel disease. By influencing the pathways of nitric oxide synthase (NOS) and arginase (ARG), L-Arg helps maintain immune balance and contributes to the pathophysiology of diseases. Gaining a better understanding of the pharmacological effects of L-Arg on immune regulation could yield new perspectives on targeted treatments for immune-related diseases. Exploring its impact on immune signaling and metabolic pathways may result in novel therapeutic approaches for chronic inflammatory and autoimmune disorders.

Photoinitiated Nitric Oxide Release as an Antibacterial Treatment for Chronic Wounds

Taking advantage of their innate roles as antibacterial strategies, the dual activity of photobiomodulation (PBM) and nitric oxide (NO) was combined to provide a tunable, on-demand chronic wound therapeutic. S-nitrosothiol-modified mesoporous silica nanoparticles (RSNO-MSNs) were doped into polyurethane (PU) to demonstrate preliminary utility as an antibacterial wound dressing treatment for chronic wounds. Photoinitiated and resultant NO-release kinetics and payloads were evaluated at 405, 430, and 530 nm for multiple irradiances. The use of photons and the NO-releasing MSNs against common chronic wound pathogens, such as Pseudomonas aeruginosa and Staphylococcus aureus, proved to be highly bactericidal. Cytocompatibility of the treatment was confirmed using human epidermal keratinocytes, a representative skin cell line.

Human pulmonary microvascular endothelial cell DDAH1-mediated nitric oxide production promotes pulmonary smooth muscle cell apoptosis in co-culture

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in preterm infants, and pulmonary hypertension (PH) develops in 25%-40% of patients with BPD, increasing morbidity and mortality. BPD-PH is characterized by vasoconstriction and vascular remodeling. Nitric oxide (NO) is a pulmonary vasodilator and apoptotic mediator made in the pulmonary endothelium by NO synthase (eNOS). Asymmetric dimethylarginine (ADMA) is an endogenous eNOS inhibitor, primarily metabolized by dimethylarginine dimethylaminohydrolase-1 (DDAH1). Our hypothesis is that DDAH1 knockdown in human pulmonary microvascular endothelial cells (hPMVEC) will result in lower NO production, decreased apoptosis, and greater proliferation of human pulmonary arterial smooth muscle cells (hPASMC), whereas DDAH1 overexpression will have the opposite effect. hPMVECs were transfected with small interfering RNA targeting DDAH1 (siDDAH1)/scramble or adenoviral vector containing DDAH1 (AdDDAH1)/AdGFP for 24 h and co-cultured for 24 h with hPASMC. Analyses included Western blot for cleaved and total caspase-3, caspase-8, caspase-9, β-actin; trypan blue exclusion for viable cell numbers; terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL); and BrdU incorporation. Small interfering RNA targeting DDAH1 (siDDAH1) transfected into hPMVEC resulted in lower media nitrites, cleaved caspase-3 and caspase-8 protein expression, and TUNEL staining; and greater viable cell numbers and BrdU incorporation in co-cultured hPASMC. Adenoviral-mediated transfection of the DDAH1 gene (AdDDAH1) into hPMVEC resulted in greater cleaved caspase-3 and caspase-8 protein expression and lower viable cell numbers in co-cultured hPASMC. Partial recovery of hPASMC viable cell numbers after AdDDAH1-hPMVEC transfection was observed when media were treated with hemoglobin to sequester NO. In conclusion, hPMVEC-DDAH1-mediated NO production positively regulates hPASMC apoptosis, which may prevent/attenuate aberrant pulmonary vascular proliferation/remodeling in BPD-PH.NEW & NOTEWORTHY BPD-PH is characterized by vascular remodeling. NO is an apoptotic mediator made in the pulmonary endothelium by eNOS. ADMA is an endogenous eNOS inhibitor metabolized by DDAH1. EC-DDAH1 overexpression resulted in greater cleaved caspase-3 and caspase-8 protein expression and lower viable cell numbers in co-cultured SMC. After NO sequestration, SMC viable cell numbers partially recovered despite EC-DDAH1 overexpression. EC-DDAH1-mediated NO production positively regulates SMC apoptosis, which may prevent/attenuate aberrant pulmonary vascular proliferation/remodeling in BPD-PH.

Anti-Inflammatory Property of 5-Demethylnobiletin (5-Hydroxy-6, 7, 8, 3', 4'-pentamethoxyflavone) and Its Metabolites in Lipopolysaccharide (LPS)-Induced RAW 264.7 Cells

Hydroxylated polymethoxyflavones (PMFs) are a unique class of flavonoid compounds mainly found in citrus plants. We investigated the anti-inflammatory effects of one major 5-hydroxy PMF, namely 5-demethylnobiletin (5DN) and its metabolites 5, 3'-didemethylnobiletin (M1), 5, 4'-didemethylnobiletin (M2), and 5, 3', 4'-tridemethylnobiletin (M3) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The results showed that M2 and M3 produced stronger inhibitory effects on the production of nitric oxide (NO) than their parent compound at non-cytotoxic concentrations. Western blotting and real-time PCR analyses demonstrated that M2 and M3 significantly decreased iNOS and COX-2 gene expression. The results also showed that M1 and M3 induced heme oxygenase-1(HO-1) gene expression. Overall, our results demonstrated that metabolites of 5DN significantly inhibited LPS-induced inflammation in RAW 264.7 macrophage cells and generally possessed more potent anti-inflammatory activity than the parent compound, 5DN.

Activation of Nrf2 by Esculetin Mitigates Inflammatory Responses through Suppression of NF-κB Signaling Cascade in RAW 264.7 Cells

Inflammation is a major root of several diseases such as allergy, cancer, Alzheimer’s, and several others, and the present state of existing drugs provoked researchers to search for new treatment strategies. Plants are regarded to be unique sources of active compounds holding pharmacological properties, and they offer novel designs in the development of therapeutic agents. Therefore, this study aimed to explore the anti-inflammatory mechanism of esculetin in lipoteichoic acid (LTA)-induced macrophage cells (RAW 264.7). The relative expression of inducible nitric oxide synthase (iNOS), nitric oxide (NO) production and COX-2 expression were intensified in LTA-induced RAW cells. The phosphorylation status of mitogen-activated protein kinases (extracellular signal-regulated kinase (ERK)1/2, p38 MAPK, and c-Jun N-terminal kinase (JNK)) and nuclear factor kappa B (NF-κB) p65 were detected by using Western blot assay. The nuclear translocation of p65 was assessed by confocal microscopic image analysis. Esculetin significantly and concentration-dependently inhibited LTA-induced NO production and iNOS expression, but not COX-2 expression, in RAW cells. Esculetin was not effective in LTA-induced MAPK molecules (ERK, p38 and JNK). However, esculetin recovered LTA-induced IκBα degradation and NF-κB p65 phosphorylation. Moreover, esculetin at a higher concentration of 20 µM evidently inhibited the nuclear translocation of NF-κB p65. At the same high concentration, esculetin augmented Nrf2 expression and decreased DPPH radical generation in RAW 264.7 cells. This study exhibits the value of esculetin for the treatment of LTA-induced inflammation by targeting NF-κB signaling pathways via its antioxidant properties.

Synergistic anti-inflammatory activity of apigenin and curcumin co-encapsulated in caseins assessed with lipopolysaccharide-stimulated RAW 264.7 macrophages

Dietary polyphenols are potential anti-inflammatory agents, and their combinations with enhanced biological activities may lower toxicity and side effects. The objective of this work was to investigate the potential synergistic anti-inflammatory activities of apigenin and curcumin co-nanoencapsulated in sodium caseinate, with comparison to unencapsulated polyphenol combinations. Non-toxic concentrations of apigenin, curcumin, and their combinations in the free and co-encapsulated forms were studied in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. Combinations of free polyphenols produced stronger inhibition of nitric oxide (NO) production, more significant at a higher proportion of curcumin, which was further enhanced after co-encapsulation. The enhanced reduction of NO was concomitant with the decreased expression of iNOS, the enhanced inhibition of pro-inflammatory cytokines of IL-6 and TNF-α, and the reduced production of intracellular reactive oxygen species. The potential multi-target effects and the enhanced solubility, proximity, and bioavailability of AP and CUR after co-encapsulation contributed to the synergistic activities. These results demonstrated that co-nanoencapsulation of apigenin and curcumin may enable the practical application utilizing the synergistic anti-inflammation effects to improve health.

First molecular modelling report on tri-substituted pyrazolines as phosphodiesterase 5 (PDE5) inhibitors through classical and machine learning based multi-QSAR analysis

Phosphodiesterase 5 (PDE5) falls under a broad category of metallohydrolase enzymes responsible for the catalysis of the phosphodiesterase bond, and thus it can terminate the action of cyclic guanosine monophosphate (cGMP). Overexpression of this enzyme leads to development of a number of pathological conditions. Thus, targeting the enzyme to develop inhibitors could be useful for the treatment of erectile dysfunction as well as pulmonary hypertension. In the current study, several molecular modelling techniques were utilized including Bayesian classification, single tree and forest tree recursive partitioning, and genetic function approximation to identify crucial structural fingerprints important for optimization of tri-substituted pyrazoline derivatives as PDE5 inhibitors. Later, various machine learning models were also developed that could be utilized to predict and screen PDE5 inhibitors in the future.

Identification of 4'-Demethyltangeretin as a Major Urinary Metabolite of Tangeretin in Mice and Its Anti-inflammatory Activities

The present study showed that oral administration of tangeretin (TAN) in mice resulted in the production of 4'-demethyltangeretin (4DT) as a major urinary metabolite. The anti-inflammatory efficacy of TAN and 4DT was determined in RAW 264.7 macrophages stimulated by lipopolysaccharides (LPS). 4DT produced considerably stronger inhibition on the overproduction of prostaglandin E₂ and nitric oxide than TAN did at the same concentrations. Western blot and quantitative polymerase chain reaction analyses indicated that 4DT exerted more potent suppressive activity on the over-expression of interleukin-1β, inducible nitric oxide synthase, and cyclooxygenase-2 than TAN. Treatments with TAN and 4DT diminished LPS-stimulated nuclear factor κB (NFκB) translocation via suppressing the degradation of inhibitor κB (IκBα). Furthermore, both compounds attenuated mitogen-activated protein kinases (MAPKs) and Akt signaling upregulated by LPS. Overall, our findings showed that TAN and 4DT inhibited the LPS-stimulated inflammatory response in macrophages by suppressing Akt/MAPKs/NFκB proinflammatory pathways, while 4DT showed more potent activity than TAN, its parent compound.

A Comparative Study on Phenolic Content, Antioxidant Activity and Anti-Inflammatory Capacity of Aqueous and Ethanolic Extracts of Sorghum in Lipopolysaccharide-Induced RAW 264.7 Macrophages

Sorghum is an important cereal with diverse phenolic compounds that have potential health promoting benefits. The current study comparatively characterized the phenolic contents of two novel black-seeded sorghum lines (SC84 and PI570481) using different extraction systems (water, ethanol and their acidified counterparts) and evaluated their antioxidant and anti-inflammatory activities. Phenolic compositions were determined by spectrophotometric assays and HPLC analysis. Antioxidant activities were assessed by radical scavenging effects on nitric oxide (NO) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals, and the oxygen radical absorbance capacity (ORAC). Anti-inflammatory capacity was estimated by measuring levels of pro-inflammatory markers produced by lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Results showed that effects of solvent types and HCl on extraction efficiency differed among phenolic compounds and sorghum samples. Tannins were the most dominant polyphenols in the studied extracts (11.11-136.11 mg epicatechin equivalent/g sorghum). Sorghum extracts exerted more potent scavenging activity on DPPH than NO radicals. In LPS-activated RAW264.7 cells, sorghum extracts dose-dependently inhibited the production of NO, interleukin-6 (IL-6), and intracellular reactive oxygen species (ROS), with ethanolic extracts showing greater anti-inflammatory activity. Positive correlations were noted between tannin content and DPPH radical scavenging activity, and anti-inflammatory capacity. These results suggest the potential role of tannin-rich sorghum extracts against inflammation and associated diseases.

Motile ciliopathies

Motile cilia are highly complex hair-like organelles of epithelial cells lining the surface of various organ systems. Genetic mutations (usually with autosomal recessive inheritance) that impair ciliary beating cause a variety of motile ciliopathies, a heterogeneous group of rare disorders. The pathogenetic mechanisms, clinical symptoms and severity of the disease depend on the specific affected genes and the tissues in which they are expressed. Defects in the ependymal cilia can result in hydrocephalus, defects in the cilia in the fallopian tubes or in sperm flagella can cause female and male subfertility, respectively, and malfunctional motile monocilia of the left-right organizer during early embryonic development can lead to laterality defects such as situs inversus and heterotaxy. If mucociliary clearance in the respiratory epithelium is severely impaired, the disorder is referred to as primary ciliary dyskinesia, the most common motile ciliopathy. No single test can confirm a diagnosis of motile ciliopathy, which is based on a combination of tests including nasal nitric oxide measurement, transmission electron microscopy, immunofluorescence and genetic analyses, and high-speed video microscopy. With the exception of azithromycin, there is no evidence-based treatment for primary ciliary dyskinesia; therapies aim at relieving symptoms and reducing the effects of reduced ciliary motility.

Oxidative Stress and Reproductive Function in the Aging Male

With the delay of parenthood becoming more common, the age at which men father children is on the rise. While the effects of advanced maternal age have been well documented, only recently have studies started to focus on the impact of advanced paternal age (APA) in the context of male reproduction. As men age, the antioxidant defense system gradually becomes less efficient and elevated levels of reactive oxygen species (ROS) accumulate in spermatozoa; this can impair their functional and structural integrity. In this review, we present an overview of how oxidative stress is implicated in male reproductive aging by providing a summary of the sources and roles of ROS, the theories of aging, and the current animal and human studies that demonstrate the impacts of APA on the male germ line, the health of progeny and fertility, and how treatment with antioxidants may reverse these effects.

Fowl Adenovirus Serotype 4 Influences Arginine Metabolism to Benefit Replication

Hydropericardium syndrome (HPS) is caused by fowl adenovirus serotype 4 (FAdV-4). HPS has caused outbreaks in Chinese populations of broiler chickens since 2015. However, little is known about the molecular mechanisms underlying HPS. In this study, we used transcriptomic analysis to screen differentially expressed genes (DEGs) in the livers of FAdV-4-infected and noninfected chicks. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the gene network associated with the arginine metabolism pathway was enriched in livers infected by FAdV-4; 10 genes were downregulated and 8 genes were upregulated in these livers when compared to noninfected livers. The DEGs identified in livers were reanalyzed by real-time fluorescence quantitative PCR (qPCR); results indicated that the mRNA levels of the DEGs concurred with the data derived from KEGG analysis. Next, we used qPCR to detect the DEGs of the arginine metabolism pathway in a hepatocellular carcinoma cell line (LMH) after infection with FAdV-4 for 24 hr; this also indicated that the mRNA levels of the DEGs concurred with that seen in the liver. We also used si-RNA oligonucleotides to knock down the mRNA levels of iNOS in LMH cells infected with FAdV-4 and found that the viral load of FAdV-4 was increased. Further investigation revealed that the addition of 240 µg/ml of arginine into the culture medium of LMH cells infected with FAdV-4 for 24 hr led to a significant increase in the mRNA levels of iNOS but a significant reduction in the viral load of FAdV-4. Therefore, our data indicated that when broiler chickens become infected with FAdV-4, the arginine metabolic pathway in the liver becomes dysfunctional and the iNOS mRNA level decreases. This will add benefit to the replication of FAdV-4 but can be inhibited by the addition of an appropriate amount of arginine.

Oncolytic Measles Virus Encoding Interleukin-12 Mediated Antitumor Activity and Immunologic Control of Colon Cancer In Vivo and Ex Vivo

Background: In this study, we used an oncolytic measles virus encoding interleukin 12 (IL-12) to treat colon cancer in vivo and ex vivo to investigate its effect on the viability and apoptosis of colon cancer cells. Method: A rat model was established to evaluate the immunostimulatory capabilities and therapeutic efficacy of vectors encoding an IL-12 fusion protein (MeVac FmIL-12 vectors). TUNEL staining, western blot, and enzyme-linked immunosorbent assay were performed to examine the impacts of MeVac FmIL-12 on the expression of inflammatory cytokines. Cell transfection was carried out to validate the anti-tumor role of MeVac FmIL-12 in vitro. Flow cytometry and MTT assay were performed to assess the effects of MeVac FmIL-12 on cell apoptosis and viability. Result: High concentrations (10-1000 ng/mL) of murine IL-12 fusion protein (FmIL-12) decreased the production of interferon γ (IFN-γ) in a concentration-dependent manner and reflected FmIL-12-induced overstimulation. Rats treated with MeVac vectors encoding FmIL-12 showed a significantly increased level of FmIL-12 overtime and a concentration-dependent (0.01-10 ng/mL) increase in IFN-γ production. MeVac FmIL-12 also increased the expression of inflammatory cytokines (IFN-γ, tumor necrosis factor α, and IL-6) both in vivo and in vitro. MeVac FmIL-12 promoted cell apoptosis and reduced cell viability, which helped to trigger a systemic anti-tumor immune response, both in vivo and in vitro. Conclusion: In this study, we suggested that MeVac FmIL-12 enhanced the therapeutic efficacy of tumor treatment by improving anti-tumor immunity.

Nitric Oxide Production in Peritoneal Macrophages from Peritoneal Dialysis Patients with Bacterial Peritonitis

Nitric oxide (NO) is produced by various cell types, and it is an important mediator in many biological processes, including macrophage-mediated cellular host defense. The relevance and amount of NO production in peritonitis during peritoneal dialysis (PD) treatment is still not clear.

We studied whether human peritoneal macrophages (PMΦ) isolated from healthy PD patients or PD patients with peritonitis showed different spontaneous or lipo-polysaccharide (LPS)linterferon gamma (IFN-y) -induced NO production (LPS, 1 nglmL 10 μglmL; IFN-y, 101000 UlmL; incubation between 6 -48 hours; measured by Griess reagent). Results were compared with human blood monocytes (HBM) isolated from buffy coats. Inducible nitric oxide synthetase (iNOS) mRNA expression was looked for in PMΦ by reverse transcriptase polymerase chain reaction (RT-PCR). Furthermore, plasma (P) and peritoneal dialysate effluent (D) nitrite concentrations were measured in vivo.

The dialysate-to-plasma ratio (DIP) of nitrite concentration was inverse in the case of peritonitis compared to infection-free patients (peritonitis DIP = 1.3, non peritonitis DIP = 0.4; p < 0.01). PMΦ from peritonitis patients produced higher amounts of NO than did those from infection-free patients (0.040 ± 0.044 nmol per microgram cell protein versus 0.018 ± 0.015 nmol per microgram cell protein, p < 0.05). NO release could not be further enhanced by stimulation with LPS plus IFN-y (1 ng/mL, 250 UlmL, respectively). However, NO production in PMΦ from infection-free patients increased during in vitro stimulation (0.044 ± 0.031 nmol per microgram cell protein versus 0.018± 0.015 nmol per microgram cell protein, p < 0.01). An increase of iNOS mRNA expression could be demonstrated by RT-PCR. Blood monocytes from healthy donors also increased NO release during cytokine stimulation (0.032± 0.015 nmol per microgram cell protein versus 0.019 ± 0.009 nmol per microgram cell protein, p < 0.05).

Our results indicate that significant amounts of NO are released intraperitoneally in the case of bacterial peritonitis. PMΦ represent a site of NO production, though the absolute amounts released in vitro are only moderate. NO production can be induced in PMΦ and HBM by LPSIIFN-y stimulation in vitro.

Anti-inflammatory effect of xanthomicrol, a major colonic metabolite of 5-demethyltangeretin

5-Demethyltengeretin (5DT) is a citrus flavonoid with various potential health benefits. To provide physiologically relevant information on the anti-inflammatory properties of 5DT, we identified the major metabolite of 5DT in the mouse colon and established its anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. CD-1 mice were fed with a 5DT-containing diet for four weeks, and colonic mucosa samples were collected and subjected to LC-MS analysis. Xanthomicrol (XAN) was identified as the major metabolite of 5DT in the mouse colon. More importantly, the colonic level of XAN was about 3.1-fold higher than that of 5DT. The anti-inflammatory effects of 5DT and XAN were determined in LPS-stimulated macrophages. XAN produced significant inhibitory effects on the production of nitric oxide and PGE2. Western blotting and real-time PCR analyses demonstrated that XAN greatly decreased the protein and mRNA levels of iNOS as well as the protein level of COX-2. Furthermore, XAN also reduced the production of pro-inflammatory cytokine IL-1β and induced the expression of anti-oxidative enzyme HO-1.

CONCLUSION

Our results demonstrated that XAN is a major metabolite of 5DT in the colon of mice fed with 5DT, and XAN may play important roles in the anti-inflammatory effects elicited by orally administered 5DT.

The renaissance of nitric oxide: from improvement of stability to enhancement of endocytosis

The local generation and intracellular release of NO is no less vital than improving the stability of carriers.

Immunostimulated Arginase II Expression in Intestinal Epithelial Cells Reduces Nitric Oxide Production and Apoptosis

Increased production of nitric oxide (NO) and subsequent local cytotoxicity to mucosal epithelial cells has been proposed as a putative mechanism involved in the development of necrotizing enterocolitis (NEC). Intestinal epithelial cells (IECs) metabolize L-arginine to either nitric oxide (NO) by NO synthase (NOS) or to L-ornithine and urea by arginase. L-ornithine is the first step in polyamine synthesis important for cell proliferation, while NO production can lead to apoptosis. We hypothesized that in IECs immunostimulation increases both NOS and arginase expression, and that arginase activity mitigates NO production and apoptosis. Rat intestinal epithelial cells (rIEC-6) were immunostimulated by either incubation with lipopolysaccharide (LPS) alone for 24 h or by incubation with conditioned media (CM) for 24 h. CM was obtained from RAW 264.7 cells (a macrophage cell line) treated with LPS (E. coli 0127:B8; 1 μg/ml) for 4 h. The rIEC-6 stimulated with LPS or with CM had significantly higher levels of inducible NOS (iNOS) protein, NO production, and arginase II protein than did the control cells. Direct LPS stimulation of rIEC-6 produced a less robust increase in iNOS expression and NO (represented as nitrite percent of control) than did CM stimulation. Inhibition of arginase using N^ω hydroxyl-L-arginine (NOHA) further increased stimulated NO production in rIEC-6. Viable cell numbers were significantly lower in CM stimulated cells after 24 h than in controls, and inhibition of arginase activity with NOHA resulted in a further significant decrease in viable cell numbers. We conclude that immunostimulated arginase expression of rIEC-6 cells tempers cytokine-induced iNOS-derived NO production and apoptosis.

Citrulline Can Preserve Proliferation and Prevent the Loss of CD3 ζ Chain Under Conditions of Low Arginine

BACKGROUND

Arginine depletion by the enzyme Arginase I, decreases expression of the TCR zeta chain preventing T-cell activation and causing T-cell dysfunction. We hypothesized that citrulline could substitute for arginine under conditions of increased arginase expression. Thus, the goal was to establish a possible mechanism of how citrulline could overcome arginine depletion caused by arginase.

METHODS

Jurkat cells were cultured, with or without arginase, in media containing different amino-acid constituents: complete RPMI containing arginine (C-RPMI) (arginine), Arginine-Free-RPMI (Arg-Free RPMI) and Citrulline-containing RPMI (Cit RPMI). Incorporation of citrulline was measured via uptake of 3H-citrulline, whereas proliferation was measured via 3H-thymidine incorporation. zeta Chain was analyzed by 2-color flow cytometry. Argininosuccinate synthase (AS) and argininosuccinate lyase expression was detected using Northern blots, RT-PCR, and Western blots.

RESULTS

Jurkat cells exhibited a significant decrease in proliferation and 5 chain expression when cultured in the presence of arginase or in the absence of arginine. With citrulline, zeta chain expression and proliferation were maintained in the absence of arginine or in the presence of the enzyme arginase. Jurkat cells, cultured in the absence of arginine, were associated with a 5-fold increase in citrulline uptake. The absence of arginine was also associated with increased expression of AS.

CONCLUSIONS

T cells exhibit the molecular capability of increasing citrulline membrane transport and up-regulating AS expression, thus exhibiting the necessary mechanisms for converting citrulline into arginine and escaping the ill effects of arginine depletion. Therefore, citrulline has the potential to be a substitute for supplemental arginine in diseases associated with arginase-mediated T cell dysfunction.

The injury of fine particulate matter from cooking oil fumes on umbilical cord blood vessels in vitro

Cooking oil fumes (COFs) derived PM_2.5 is the major source of indoor air pollution in Asia. For this, a pregnant rat model within different doses of cooking oil fumes (COFs) derived PM_2.5 was established in pregnancy in our research. Our previous studies have showed that exposure to COFs-derived PM_2.5 was related to adverse pregnancy outcomes. However, the mechanisms of signaling pathways remain unknown. Therefore, this study aimed to investigate the underlying mechanisms induced by COFs-derived PM2.5 injury on umbilical cord blood vessels (UCs) in vitro. Exposure to COFs-derived PM_2.5 resulted in changing the expression of eNOS, ET-1, ETRA, and ETRB. In additions, western blot analysis indicated that the HIF-1α/iNOS/NO signaling pathway and VEGF/VEGFR1/iNOS signaling pathway were involved in UCs injury triggered by COFs-derived PM_2.5. In conclusion, our data suggested that exposure to COFs-derived PM_2.5 resulted in increasing of oxidative stress and inflammation, as well as dysfunction of UCs.

Recent advances in the chemical biology of nitroxyl (HNO) detection and generation

Nitroxyl or azanone (HNO) represents the redox-related (one electron reduced and protonated) relative of the well-known biological signaling molecule nitric oxide (NO). Despite the close structural similarity to NO, defined biological roles and endogenous formation of HNO remain unclear due to the high reactivity of HNO with itself, soft nucleophiles and transition metals. While significant work has been accomplished in terms of the physiology, biology and chemistry of HNO, important and clarifying work regarding HNO detection and formation has occurred within the last 10 years. This review summarizes advances in the areas of HNO detection and donation and their application to normal and pathological biology. Such chemical biological tools allow a deeper understanding of biological HNO formation and the role that HNO plays in a variety of physiological systems.

[Production of nitric oxide metabolites during transplanted tumors growth with different metastatic potential]

The endogenous formation of metabolites of NO - nitrite (NI), nitrates (NA) and volatile nitrosamines in the body, tumor tissue and by abdominal cavity by macrophages for dynamics was investigated in mice F1(C57BlxCBA), Balb/c and BDF with subcutaneous transplanted tumors (Erlich carcinoma - EC and metastatic Lewis lung carcinoma - LLC). It was shown that growth of EC was accompanied by a statistically significant increase in the concentrations of NI and NA in tumor tissue to (7.3±4.67)'10-6 - (7.8±2.57)'10-5 (mol/kg) for the first three weeks and a sharp increase in urinary excretion of NI and NA. The maximum total concentration of NI and NA - (3.,6±0.46)'10-5 in tissue LLC was registered during the early stage of the tumor growth (7 days); it later declined, negatively correlating with the mass of the tumor. NI secretion by abdominal cavity macrophages demonstrated statistically significantly decrease at the stage of intensive growth LLC (14, 21 days). The tissue of EC contained varied concentration of cancerogenic N-nitrosodimethylamine and N-nitrosodiethylamine at all investigated time points. Thus, the ability of different gistogenesis tumor tissue to synthesize metabolites NO depended on time parameters and was more pronounced for EC, than LLC.

Effects of dietary nutrients on volatile breath metabolites

Breath analysis is becoming increasingly established as a means of assessing metabolic, biochemical and physiological function in health and disease. The methods available for these analyses exploit a variety of complex physicochemical principles, but are becoming more easily utilised in the clinical setting. Whilst some of the factors accounting for the biological variation in breath metabolite concentrations have been clarified, there has been relatively little work on the dietary factors that may influence them. In applying breath analysis to the clinical setting, it will be important to consider how these factors may affect the interpretation of endogenous breath composition. Diet may have complex effects on the generation of breath compounds. These effects may either be due to a direct impact on metabolism, or because they alter the gastrointestinal flora. Bacteria are a major source of compounds in breath, and their generation of H₂, hydrogen cyanide, aldehydes and alkanes may be an indicator of the health of their host.

Biological nitric oxide signalling: chemistry and terminology

Biological nitrogen oxide signalling and stress is an area of extreme clinical, pharmacological, toxicological, biochemical and chemical research interest. The utility of nitric oxide and derived species as signalling agents is due to their novel and vast chemical interactions with a variety of biological targets. Herein, the chemistry associated with the interaction of the biologically relevant nitrogen oxide species with fundamental biochemical targets is discussed. Specifically, the chemical interactions of nitrogen oxides with nucleophiles (e.g. thiols), metals (e.g. hemeproteins) and paramagnetic species (e.g. dioxygen and superoxide) are addressed. Importantly, the terms associated with the mechanisms by which NO (and derived species) react with their respective biological targets have been defined by numerous past chemical studies. Thus, in order to assist researchers in referring to chemical processes associated with nitrogen oxide biology, the vernacular associated with these chemical interactions is addressed.

Immunomodulatory effects of Bacillus subtilis (natto) B4 spores on murine macrophages

To investigate the immunomodulatory effects of Bacillus subtilis (B. subtilis) (natto) B4 spores on murine macrophage, RAW 264.7 cells were cultured alone or with B subtilis (natto) B4 spores at 37°C for 12 hrs, then both cells and culture supernatants were collected for analyses. Exposure of RAW 264.7 cells to B. subtilis (natto) B4 spores had no significant effects on macrophage viability and amounts of extracellular lactate dehydrogenase (LDH). However, it remarkably increased the activities of acid phosphatase (ACP), lactate dehydrogenase (LDH) and inducible nitric oxide synthase (iNOS) in cells and the amounts of nitric oxide (NO) and cytokines (tumor necrosis factor-alpha, interferon-gamma, interleukin [IL]-1 beta, IL-6, IL-12, IL-10 and macrophage inflammatory protein-2) in culture supernatants. These results demonstrate that B. subtilis (natto) B4 spores are harmless to murine macrophages and can stimulate their activation through up-regulation of ACP and LDH activities and enhance their immune function by increasing iNOS activity and stimulating NO and cytokine production. The above findings suggest that B. subtilis (natto) B4 spores have immunomodulatory effects on macrophages.

The role of reactive oxygen species and proinflammatory cytokines in type 1 diabetes pathogenesis

Type 1 diabetes (T1D) is a T cell–mediated autoimmune disease characterized by the destruction of insulin-secreting pancreatic β cells. In humans with T1D and in nonobese diabetic (NOD) mice (a murine model for human T1D), autoreactive T cells cause β-cell destruction, as transfer or deletion of these cells induces or prevents disease, respectively. CD4⁺ and CD8⁺ T cells use distinct effector mechanisms and act at different stages throughout T1D to fuel pancreatic β-cell destruction and disease pathogenesis. While these adaptive immune cells employ distinct mechanisms for β-cell destruction, one central means for enhancing their autoreactivity is by the secretion of proinflammatory cytokines, such as IFN-γ, TNF-α, and IL-1. In addition to their production by diabetogenic T cells, proinflammatory cytokines are induced by reactive oxygen species (ROS) via redox-dependent signaling pathways. Highly reactive molecules, proinflammatory cytokines are produced upon lymphocyte infiltration into pancreatic islets and induce disease pathogenicity by directly killing β cells, which characteristically possess low levels of antioxidant defense enzymes. In addition to β-cell destruction, proinflammatory cytokines are necessary for efficient adaptive immune maturation, and in the context of T1D they exacerbate autoimmunity by intensifying adaptive immune responses. The first half of this review discusses the mechanisms by which autoreactive T cells induce T1D pathogenesis and the importance of ROS for efficient adaptive immune activation, which, in the context of T1D, exacerbates autoimmunity. The second half provides a comprehensive and detailed analysis of (1) the mechanisms by which cytokines such as IL-1 and IFN-γ influence islet insulin secretion and apoptosis and (2) the key free radicals and transcription factors that control these processes.

IL-27 promotes nitric oxide production induced by LPS through STAT1, NF-κB and MAPKs

Interleukin (IL)-27, a member of the IL-6/IL-12 heterodimeric cytokine family, induces pro-inflammatory responses including early T helper (Th)1 differentiation and generation of cytotoxic T lymphocytes, and also anti-inflammatory responses including the differentiation to IL-10-producing regulatory T cells, inhibition of Th2 and Th17 differentiation, and suppression of pro-inflammatory cytokine production. Nitric oxide (NO) is a potent source of reactive nitrogen species that play an important role in killing intracellular pathogens and forms a crucial component of host defense. Inducible NO synthase (iNOS), which catalyzes the production of NO, is induced by a range of stimuli including cytokines and microbes. Recently, IL-27 was reported to play an anti-inflammatory role in microglia by blocking oncostatin M-induced iNOS expression and neuronal toxicity. In the present study, we investigated the effects of IL-27 on NO production in thioglycollate-elicited peritoneal macrophages. IL-27 together with lipopolysaccharide (LPS) induced morphological change into more spread and elongated cells and synergistically enhanced NO production. The combined stimulation also enhanced iNOS mRNA expression and the NO production was abrogated by an iNOS inhibitor, NG-monomethyl L-arginine. The synergistic NO production could be attributed to the augmented Toll-like receptor (TLR)4 mRNA expression by the combination. Signal transducer and activator of transcription (STAT)1 was indispensable for the morphological change and NO production. The combination induced nuclear factor κB (NF-κB) translocation into nuclear and phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), and their inhibitors suppressed NO production. These results suggest that in contrast to the anti-proinflammatory role in microglia, IL-27 exerts a pro-inflammatory role by enhancing NO production in peritoneal macrophages stimulated with LPS through activation of STAT1, NF-κB and MAPKs.

Synergistic anti-inflammatory effects of nobiletin and sulforaphane in lipopolysaccharide-stimulated RAW 264.7 cells

Inflammation plays important roles in the initiation and progress of many diseases including cancers in multiple organ sites. Herein, we investigated the anti-inflammatory effects of two dietary compounds, nobiletin (NBN) and sulforaphane (SFN), in combination. Noncytotoxic concentrations of NBN, SFN, and their combinations were studied in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The results showed that combined NBN and SFN treatments produced much stronger inhibitory effects on the production of nitric oxide (NO) than NBN or SFN alone at higher concentrations. These enhanced inhibitory effects were synergistic based on the isobologram analysis. Western blot analysis showed that combined NBN and SFN treatments synergistically decreased iNOS and COX-2 protein expression levels and induced heme oxygenase-1 (HO-1) protein expression. Real-time polymerase chain reaction analysis indicated that low doses of NBN and SFN in combination significantly suppressed LPS-induced upregulation of IL-1 mRNA levels and synergistically increased HO-1 mRNA levels. Overall, our results demonstrated that NBN and SFN in combination produced synergistic effects in inhibiting LPS-induced inflammation in RAW 264.7 cells.

The challenges of diagnosing primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disorder of ciliary structure and function. The diagnosis can be challenging, particularly when using nongenetic assays. The "gold standard" diagnostic test is ultrastructural analysis of respiratory cilia obtained by nasal scrape or brush biopsy. A few specialized centers use high-speed videomicroscopy to examine ciliary beat. Certain beat patterns correlate with ultrastructural defects, and, in some cases, subtle alterations in beat pattern can be seen when ultrastructure is normal. Recent studies have shown that nasal nitric oxide (NO) is very low in patients with PCD compared with healthy control subjects; therefore, this assay may be a useful screening or adjunctive test for PCD. Because acute respiratory illnesses may yield alterations in ciliary ultrastructure, ciliary beat, and nasal NO values, these tests should be performed during a stable baseline period. Identification of an array of PCD genes has provided the opportunity for making a definitive genetic diagnosis for PCD in some cases. All of these approaches have a role in diagnosing PCD. For example, PCD has been confirmed by identifying disease-causing mutations in a heavy dynein chain gene in individuals with normal ciliary ultrastructure but subtle defects in ciliary beat and low nasal NO. Priorities to improve nongenetic diagnostic capability include standardization of nasal NO as a screening test and the development of specialized centers using uniform approaches for the analysis of ciliary ultrastructure and ciliary beat pattern. Another chapter in this issue (see Zariwala and colleagues, pp. 430) addresses the progress toward improved capabilities for definitive genetic testing.

The specificity of nitroxyl chemistry is unique among nitrogen oxides in biological systems

The importance of nitric oxide in mammalian physiology has been known for nearly 30 years. Similar attention for other nitrogen oxides such as nitroxyl (HNO) has been more recent. While there has been speculation as to the biosynthesis of HNO, its pharmacological benefits have been demonstrated in several pathophysiological settings such as cardiovascular disorders, cancer, and alcoholism. The chemical biology of HNO has been identified as related to, but unique from, that of its redox congener nitric oxide. A summary of these findings as well as a discussion of possible endogenous sources of HNO is presented in this review.

Expression and prognostic significance of iNOS in uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular tumor in adults. Disease metastasis occurs in half of the patients and is uniformly fatal despite systemic therapy. Inducible nitric oxide synthase (iNOS) is associated with disease progression in various malignancies including cutaneous melanoma. In this retrospective cohort, we examined the prognostic value of iNOS in UM by performing immunohistochemistry on paraffin-embedded sections of primary tumors (90 patients) and matched primary and metastatic hepatic tumors (19 patients) with complete histopathological and clinical data. We show that iNOS is expressed in UM (57% of the patients) and high iNOS levels significantly (p = 0.04; hazard ratio (HR) = 2.3) predict disease-specific survival (DSS) as assessed by Kaplan-Meier analysis and univariate Cox's proportional hazards regression model. Furthermore, high iNOS expression in the UM primary tissue was significantly associated with metastatic disease and vice versa. Expression of iNOS in hepatic metastases significantly (p = 0.02) predicted a shortened survival as assessed by Kaplan-Meier analysis. However, iNOS did not appear to be a significant (p = 0.16; HR = 1.9) factor in the multivariate Cox's regression analysis performed together with the clinical parameters tumor diameter, tumor cell type, and tumor location in which only tumor diameter predicted DSS. In conclusion, iNOS predicts DSS in UM and may play a role in disease progression but it is not an independent prognostic factor.

Waging war against uropathogenic Escherichia coli: winning back the urinary tract

Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a substantial economic and societal burden-a formidable public health issue. Symptomatic UTI causes significant discomfort in infected patients, results in lost productivity, predisposes individuals to more serious infections, and usually necessitates antibiotic therapy. There is no licensed vaccine available for prevention of UTI in humans in the United States, likely due to the challenge of targeting a relatively heterogeneous group of pathogenic strains in a unique physiological niche. Despite significant advances in the understanding of UPEC biology, mechanistic details regarding the host response to UTI and full comprehension of genetic loci that influence susceptibility require additional work. Currently, there is an appreciation for the role of classic innate immune responses-from pattern receptor recognition to recruitment of phagocytic cells-that occur during UPEC-mediated UTI. There is, however, a clear disconnect regarding how factors involved in the innate immune response to UPEC stimulate acquired immunity that facilitates enhanced clearance upon reinfection. Unraveling the molecular details of this process is vital in the development of a successful vaccine for prevention of human UTI. Here, we survey the current understanding of host responses to UPEC-mediated UTI with an eye on molecular and cellular factors whose activity may be harnessed by a vaccine that stimulates lasting and sterilizing immunity.

Naphthoquinones and bioactive compounds from tobacco as modulators of neuronal nitric oxide synthase activity

Studies were conducted with extracts of several varieties of tobacco in search of neuronal nitric oxide synthase (nNOS) inhibitors which may be of value in the treatment of stroke. Current therapies do not directly exploit modulation of nNOS activity due to poor selectivity of the currently available nNOS inhibitors. The properties of a potentially novel nNOS inhibitor(s) derived from tobacco extracts, and the concentration-dependent, modulatory effects of the tobacco-derived naphthoquinone compound, 2,3,6-trimethyl-1,4-naphthoquinone (TMN), on nNOS activity were investigated, using 2-methyl-1,4-naphthoquinone (menadione) as a control. Up to 31 microM, both TMN and menadione stimulated nNOS-catalysed L-citrulline production. However, at higher concentrations of TMN (62.5-500 microM), the stimulation was lost in a concentration-dependent manner. With TMN, the loss of stimulation did not decrease beyond the control activity. With menadione (62.5-500 microM), the loss of stimulation surpassed that of the control (78+/-0.01% of control activity), indicating a true inhibition of nNOS activity. This study suggests that potential nNOS inhibitors are present in tobacco, most of which remain to be identified.

Arginase activity in mitochondria--An interfering factor in nitric oxide synthase activity assays

Previously, in tightly controlled studies, using three independent, yet complementary techniques, we refuted the claim that a mitochondrial nitric oxide synthase (mtNOS) isoform exists within pure, rat liver mitochondria (MT). Of those techniques, the NOS-catalyzed [(14)C]-L-arginine to [(14)C]-L-citrulline conversion assay (NOS assay) with MT samples indicated a weak, radioactive signal that was NOS-independent. Aliquots of samples from the NOS assays were then extracted with acetone, separated by high performance thin-layer chromatography (HPTLC) and exposed to autoradiography. Results obtained from these samples showed no radioactive band for L-citrulline. However, a fast-migrating, diffuse, radioactive band was observed in the TLC lanes loaded with MT samples. In this manuscript, we identify and confirm that this radioactive signal in MT samples is due to the arginase-catalyzed conversion of [(14)C]-L-arginine to [(14)C]-urea. The current results, in addition to reconfirming the absence of NOS activity in rat liver MT, also show the need to include arginase inhibitors in studies using MT samples in order to avoid confounding results when using NOS activity assays.

Prognostic significance of tumor iNOS and COX-2 in stage III malignant cutaneous melanoma

PURPOSE

New prognostic markers are needed for malignant melanoma. Inducible nitric oxide synthase (iNOS) and cyclooxygenase type 2 (COX-2) have been described to correlate with progression of melanoma. Moreover, activating mutations in BRAF/NRAS oncogenes are often detected in melanoma. The BRAF/NRAS mutation status and expression of COX-2 and iNOS were examined to compare their prognostic value for overall survival (OS) in stage III malignant cutaneous melanoma.

EXPERIMENTAL DESIGN

The expression of iNOS and COX-2 in metastatic lymph nodes from 21 rapidly progressing (OS from date of diagnosis of stage III disease < or =14 months) and 17 slowly progressing (OS > or =60 months) stage III cutaneous melanoma patients was examined by immunohistochemistry. The presence of BRAF/NRAS mutations was analyzed using direct DNA sequencing. Chi2 exact trend test and logistic regression analysis were used for statistical analysis.

RESULTS

Both iNOS (P = 0.002) and COX-2 (P = 0.048) alone significantly predicted OS. The BRAF/NRAS mutation status did not significantly differ between patient groups, although iNOS significantly (P = 0.013) correlated with BRAF mutation frequency. Furthermore, the odds ratio (OR) with respect to OS of iNOS (OR = 10.4) was higher than that of COX-2 (OR = 5.6) and was stable in the multivariate analysis of OS together with disease stage IIIB/C, ulceration, number of metastatic lymph nodes, and Breslow tumor thickness.

CONCLUSION

Our data show that iNOS is an independent and stronger prognostic factor for OS in stage III malignant cutaneous melanoma than COX-2.

Clinical and genetic aspects of primary ciliary dyskinesia/Kartagener syndrome

Primary ciliary dyskinesia is a genetically heterogeneous disorder of motile cilia. Most of the disease-causing mutations identified to date involve the heavy (dynein axonemal heavy chain 5) or intermediate(dynein axonemal intermediate chain 1) chain dynein genes in ciliary outer dynein arms, although a few mutations have been noted in other genes. Clinical molecular genetic testing for primary ciliary dyskinesia is available for the most common mutations. The respiratory manifestations of primary ciliary dyskinesia (chronic bronchitis leading to bronchiectasis, chronic rhino-sinusitis, and chronic otitis media)reflect impaired mucociliary clearance owing to defective axonemal structure. Ciliary ultrastructural analysis in most patients (>80%) reveals defective dynein arms, although defects in other axonemal components have also been observed. Approximately 50% of patients with primary ciliary dyskinesia have laterality defects (including situs inversus totalis and, less commonly, heterotaxy, and congenital heart disease),reflecting dysfunction of embryological nodal cilia. Male infertility is common and reflects defects in sperm tail axonemes. Most patients with primary ciliary dyskinesia have a history of neonatal respiratory distress, suggesting that motile cilia play a role in fluid clearance during the transition from a fetal to neonatal lung. Ciliopathies involving sensory cilia, including autosomal dominant or recessive polycystic kidney disease, Bardet-Biedl syndrome, and Alstrom syndrome, may have chronic respiratory symptoms and even bronchiectasis suggesting clinical overlap with primary ciliary dyskinesia.

Molecular mechanisms for discrete nitric oxide levels in cancer

Nitric oxide (NO) has been invoked in nearly every normal and pathological condition associated with human physiology. In tumor biology, nitrogen oxides have both positive and negative affects as they have been implicated in both promoting and preventing cancer. Our work has focused on NO chemistry and how it correlates with cytotoxicity and cancer. Toward this end, we have studied both concentration- and time-dependent NO regulation of specific signaling pathways in response to defined nitrosative stress levels that may occur within the tumor microenvironment. Threshold levels of NO required for activation and stabilization of key proteins involved in carcinogenesis including p53, ERK, Akt and HIF have been identified. Importantly, threshold NO levels are further influenced by reactive oxygen species (ROS) including superoxide, which can shift or attenuate NO-mediated signaling as observed in both tumor and endothelial cells. Our studies have been extended to determine levels of NO that are critical during angiogenic response through regulation of the anti-angiogenic agent thrombospondin-1 (TSP-1) and pro-angiogenic agent matrix metalloproteinase-9 (MMP-9). The quantification of redox events at the cellular level has revealed potential mechanisms that may either limit or potentiate tumor growth, and helped define the positive and negative function of nitric oxide in cancer.

Arginine and immunity

For many years, dietary arginine supplementation, often combined with other substances, has been used as a mechanism to boost the immune system. Considerable controversy, however, exists as to the benefits and indications of dietary arginine due in part to a poor understanding of the role played by this amino acid in maintaining immune function. Emerging knowledge promises to clear this controversy and allow for arginine's safe use. In myeloid cells, arginine is mainly metabolized either by inducible nitric oxide (NO) synthases (iNOS) or by arginase 1, enzymes that are stimulated by T helper 1 or 2 cytokines, respectively. Thus, activation of iNOS or arginase (or both) reflects the type of inflammatory response in a specific disease process. Myeloid suppressor cells (MSC) expressing arginase have been described in trauma (in both mice and humans), intra-abdominal sepsis, certain infections, and prominently, cancer. Myeloid cells expressing arginase have been shown to accumulate in patients with cancer. Arginase 1 expression is also detected in mononuclear cells after trauma or surgery. MSC efficiently deplete arginine and generate ornithine. Through arginine depletion, MSC may control NO production and regulate other arginine-dependent biological processes. Low circulating arginine has been documented in trauma and cancer, suggesting that MSC may exert a systemic effect and cause a state of arginine deficiency. Simultaneously, T lymphocytes depend on arginine for proliferation, zeta-chain peptide and T-cell receptor complex expression, and the development of memory. T-cells cocultured with MSC exhibit the molecular and functional effects associated with arginine deficiency. Not surprisingly, T-cell abnormalities, including decreased proliferation and loss of the zeta-chain, are observed in cancer and after trauma.

Evaluation of nitroalkenes as nitric oxide donors

Chemiluminescence experiments demonstrate that simple nitroalkenes release low levels of nitric oxide. UV and EPR measurements suggest but cannot confirm direct NO release from nitroalkenes. Given the biological activity of nitrated unsaturated fatty acids, these results suggest the possible metabolic conversion of nitroalkenes to NO.

Demonstration of nitric oxide synthase activity in crustacean hemocytes and anti-microbial activity of hemocyte-derived nitric oxide

We determined the biochemical characteristics of nitric oxide synthase (NOS) in hemocytes of the crayfish Procambarus clarkii and investigated the roles of hemocyte-derived NO in host defense. Biochemical analysis indicated the presence of a Ca2+ -independent NOS activity, which was elevated by lipopolysaccharide (LPS) treatment. When bacteria (Staphylococcus aureus) and hemocytes were co-incubated, adhesion of bacteria to hemocytes was observed. NO donor sodium nitroprusside (SNP) significantly increased the numbers of hemocytes to which bacteria adhered. Similarly, LPS elicited bacterial adhesion and the LPS-induced adhesion was prevented by NOS inhibitor NG-monomethyl-L-arginine (L-NMMA). Finally, plate count assay demonstrated that addition of LPS to the hemocytes/bacteria co-incubation resulted in a significant decrease in bacterial colony forming unit (CFU), and that L-NMMA reversed the decreasing effect of LPS on CFU. The combined results demonstrate the presence of a Ca2+ -independent LPS-inducible NOS activity in crayfish hemocytes and suggest that hemocyte-derived NO is involved in promoting bacterial adhesion to hemocytes and enhancing bactericidal activity of hemocytes.

3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), a food-born carcinogenic heterocyclic amine, promotes nitric oxide production in murine macrophages

A heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) is one of the potent food-born dietary carcinogens derived mainly from burnt meat products. In the present study, we investigated the inductive effect of Trp-P-1 on nitric oxide (NO) production in murine macrophages since NO and its oxidized derivatives are directly involved in triggering mutagenesis and carcinogenesis. Our results show that Trp-P-1 induced mRNA expression of inducible NO synthase (iNOS) and NO production without co-stimulation in murine peritoneal macrophages and RAW 264.7 cells. Trp-P-1 further enhanced both iNOS mRNA expression and NO production, which were primarily induced by lipopolysaccharide (LPS). Electrophoretic mobility shift assay demonstrated that Trp-P-1, alone or in the presence of LPS, facilitated the DNA binding activity of the transcription factor NF-kappaB, and the trans-acting activity of the NF-kappaB was confirmative as determined by in vitro transfection and a luciferase reporter gene assay. Moreover, Trp-P-1 induced increasing intracellular reactive oxygen species (ROS), which play an important role in NF-kappaB activation. These results suggest that Trp-P-1 induces NO production mediated by an increased intracellular ROS, NF-kappaB activation, and subsequent iNOS gene expression.

Differential inducible nitric oxide synthase activity in circulating neutrophils vs. mononuclears of septic shock patients

OBJECTIVE

To compare nitric oxide synthase (NOS) activity in circulating neutrophils and mononuclear cells of patients with septic shock to healthy subjects.

DESIGN AND SETTING

Prospective study in the general intensive care unit (30 beds) of a university affiliated-hospital and the A.C. Burton Vascular Biology Research Laboratory.

PATIENTS

Six septic patients and seven healthy volunteers.

MEASUREMENTS AND RESULTS

We measured NOS in circulating neutrophils and mononuclears. Constitutive (cNOS) and inducible (iNOS) activities were analyzed by the [3H]L-arginine-L-citrulline assay. Plasma NOx- was determined by chemiluminescence. NOx- was higher in septic vs. controls (median 110, IQR 39-250 vs. 23, 14-46 microM; p<0.05). cNOS in septic cells was unmeasurable. iNOS in septic neutrophils was higher (median 34.9, IQR 10.4-95.8 vs. controls 2.5, 0-2.7 U; p<0.05) while iNOS in septic mononuclears was unaltered (median 16.4, IQR 9.1-52.6 vs. controls 8.9, 5.9-20.3 U; p=0.240).

CONCLUSIONS

Increased iNOS activity was found in circulating neutrophils of septic shock patients compared to healthy volunteers. Moreover, differential iNOS activity was evident in circulating neutrophils vs. mononuclears of patients with septic shock. Further investigations are warranted to confirm this differential iNOS activity and to explore its significance.

Primary ciliary dyskinesia: clinical presentation, diagnosis and genetics

Primary ciliary dyskinesia (PCD) is a phenotypically and genetically heterogeneous disorder with an autosomal-recessive inheritance pattern. Only rarely other modes of inheritance such as X-linked transmission are observed. The disease phenotype is caused by defects of respiratory cilia, sperm tails and the cilia of the embryonic node. The lack of mucociliary clearance contributes to recurrent respiratory tract infections, that might progress to permanent lung damage (bronchiectasis). The goal of therapy is prevention of bronchiectasis. Male infertility due to sperm tail dysmotility is another frequent finding in PCD. Half of affected individuals have situs inversus (Kartagener's syndrome) due to randomization of left/right body asymmetry. Currently three genes (DNAI1, DNAH5, DNAH11) that encode for dynein proteins have been linked to recessive PCD. Mutations in RPGR located on the X chromosome have been identified in males with retinitis pigmentosa and PCD. As a screening test nasal nitric oxide (NO) measurement is widely used. Establishment of diagnosis currently relies on electron microscopy, direct evaluation of ciliary beat by light microscopy, and/or the novel method of high-resolution immunofluorecent analysis of respiratory cilia.