Inducible nitric oxide synthase in human diseases

Human classical monocytes control the intracellular stage of Leishmania braziliensis by reactive oxygen species

Leishmania braziliensis are intracellular parasites that cause unique clinical forms of cutaneous leishmaniasis. Previous studies with other leishmania species demonstrated that reactive oxygen species (ROS) control promastigotes, the infective stage of the parasite, but not the amastigote form that exists in the mammalian host. Here we show that ROS inhibits growth of L. braziliensis amastigotes in resting monocytes, and that classical monocytes are primarily responsible for this control. ROS, but not nitric oxide, also contributed to killing of L. braziliensis by IFN-γ activated monocytes. Furthermore, by gene expression profiling of human lesions we found greater expression of genes associated with ROS, but not nitric oxide, compared to normal skin. This study shows that ROS are important for control of L. braziliensis both at the initial stages of infection, as well as at later time points, and highlights that monocyte subsets may play different roles during leishmaniasis.

Synthesis and effects of new caffeic acid derivatives on nitric oxide production in lipopolysaccharide-induced RAW 264.7 macrophages

In this study, 20 new derivatives of caffeic acid esters were synthesized and their inhibitory activities against the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages were determined. Compounds 3l, 3r, 3s and 3t were found to decrease nitrite levels in a dose-dependent manner in LPS-induced cells and showed potent inhibitory activities against the NO production in RAW264.7 macrophages with IC50 values of 7.4, 5.9, 3.3 and 2.2 μM, respectively. They could be selected as compromising compounds for the later pharmacological study.

Influence of olive-derived hydroxytyrosol on the toll-like receptor 4-dependent inflammatory response of mouse peritoneal macrophages

Macrophages play important roles in the host innate immune response and are involved in the onset of diseases caused by inflammation. Toll-like receptor 4 (TLR4)-mediated inflammatory responses of macrophages may be associated with diseases such as diabetes and diseases of the cardiovascular system. Hydroxytyrosol (HT) exerts strong antioxidant and anti-inflammatory effects and may be applied in the treatment of inflammatory diseases. In the present study conducted in vitro, we investigated the effects of the TLR4-dependent anti-inflammatory effect of HT on peritoneal macrophage of BALB/c mice. We show here that the elevated levels of iNOS gene expression and nitric oxide production induced by lipopolysaccharide (LPS) (0.25 μg/ml) were suppressed by HT (12.5 μg/ml). LPS-dependent NF-κB gene expression and phosphorylation of NF-κB were not affected by HT under these conditions. In contrast, the expression of TNF-α was significantly increased in the presence of LPS and HT. These results suggest that HT suppressed nitric oxide production by decreasing iNOS gene expression through a mechanism independent of the NF-κB signaling pathway. These novel findings suggest that the modulation by HT of the expression of genes involved in inflammation may involve multiple mechanisms.

Inhibitory effect of 10-hydroxydecanoic acid on lipopolysaccharide-induced nitric oxide production via translational downregulation of interferon regulatory factor-1 in RAW264 murine macrophages

Toll-like receptors (TLRs) play a critical role in innate immunity by recognizing pathogen-associated molecular patterns. Various environmental materials including lipids may affect TLR signaling and modulate innate immune responses. We previously reported that 10-hydroxy-trans-2-decenoic acid (10H2DA) inhibits lipopolysaccharide (LPS)-induced interleukin (IL)-6 and nitric oxide (NO) production via inhibiting NF-κB activation. In this study, we investigated the effect of 10-hydroxydecanoic acid (10HDA), a saturated fatty acid of 10H2DA, on LPS-induced cytokines/chemokines and NO production. 10HDA inhibited LPS-induced NO production, but not tumor necrosis factor-α or IL-6 production. LPS-induced activation of interferon (IFN)-stimulated response element, but not NF-κB, was inhibited by 10HDA. Phosphorylation of STAT1 and STAT2 was not affected, but IFN-regulatory factor (IRF)-1 production was significantly reduced by 10HDA. The LPS-induced increase of IRF-1 mRNA, however, was not affected by 10HDA. We found that IRF-1 mRNA level in the polysomal fraction was significantly decreased by 10HDA. Further, LPS-induced phosphorylation of Akt and 4E-BP1, which control mRNA translation, was markedly decreased. These results suggest that 10HDA inhibited LPS-induced NO production through inhibiting IRF-1 translation. These findings elucidate a novel mechanism for anti-inflammatory activity of medium-chain fatty acid 10HDA.

Nitric oxide and interleukins are involved in cell proliferation of RAW264.7 macrophages activated by viili exopolysaccharides

Viili has been traditionally regarded as healthy food; viili exopolysaccharides (VEPS) function as antioxidants, but the molecular and cellular mechanisms, especially its immune functions, remain largely unclear. To assess VEPS's immunological roles, VEPS were separated by Sevage's method and purified by anion exchange chromatography. Cell proliferation, phagocytosis, releases of nitric oxide (NO), interleukin (IL)-1β, and IL-6, the inducible nitric oxide synthase (iNOS) gene expression by reverse transcription polymerase chain reaction (RT-PCR) and iNOS protein by Western blotting, and morphology by scanning electron microscopy in lipopolysaccharides (LPS)/VEPS-stimulated and non-stimulated RAW264.7 macrophages were analyzed. VEPS increased cell proliferation at 50-200 μg/mL. The uptake of neutral red for the indication of phagocytosis and releases of NO, IL-6, and IL-1β were enhanced after exposure to LPS and VEPS. Gene expressions of iNOS, IL-6, and IL-1β and protein expressions of iNOS were increased with VEPS. The RAW264.7 cell treated with VEPS became flattened, a strong indication of the activation of macrophages. We concluded that VEPS promoted the activation of macrophages in which NO, IL-6, and IL-1β were involved; the release of NO and other cytokines may eventually activate lymphocytes, increasing nonspecific (innate) and specific immunity in humans.

The role of nitric oxide in Doxorubicin-induced cardiotoxicity: experimental study

Objective: We evaluated the myocardial damage in rats treated with doxorubicin (DOX) alone and in combination with nitric oxide synthase (NOS) inhibitors.

Materials and Methods: Twenty-four male Sprague Dawley rats (12 weeks old, weighing 262±18 g) were randomly assigned into 4 groups (n=6). Group I was the control group. In Group II, rats were treated with intraperitoneal (ip) injections of 3 mg/kg DOX once a week for 5 weeks. In Group III, rats received weekly ip injections of 30 mg/kg L-NAME (nonspecific NOS inhibitor) 30 min before DOX injections for 5 weeks. In Group IV, rats received weekly ip injections of 3 mg/kg L-NIL (inducible NOS inhibitor) 30 min before DOX injections for 5 weeks. Rats were weighed 2 times a week. At the end of 6 weeks, hearts were excised and then fixed for light and electron microscopy evaluation and tissue lipid peroxidation (malondialdehyde). Blood samples were also obtained for measuring plasma lipid peroxidation.

Results: Weight loss was observed in Group II, Group III, and Group IV. Weight loss was statistically significant in the DOX group. Findings of myocardial damage were significantly higher in animals treated with DOX only than in the control group. Histopathological findings of cardiotoxicity in rats treated with DOX in combination with L-NAME and L-NIL were not significantly different compared with the control group. The level of plasma malondialdehyde in the DOX group (9.3±3.4 µmol/L) was higher than those of all other groups.

Conclusion: Our results showed that DOX cardiotoxicity was significantly decreased when DOX was given with NO synthase inhibitors.

Inhibition of nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophages by isolated xanthones from the roots of Cratoxylum formosum ssp. pruniflorum

The inhibitory activity of extract and compounds isolated from the roots of Cratoxylum formosum ssp. pruniflorum against nitric oxide (NO) was evaluated using RAW264.7 cells. Isolation of the CH2Cl2 extract of C. formosum ssp. pruniflorum roots afforded ten known xanthones including six tri-oxygenated xanthones (1-6) and four tetra-oxygenated xanthones (7-10), respectively. Compound 7 showed the highest inhibitory activity against NO release with an IC50 value of 3.9 μM, followed by compound 8 with an IC50 value of 4.3 μM, respectively. In order to understand the mechanism of this anti-inflammatory activity, the transcriptional level of 7 was found to down regulate mRNA expressions of iNOS and COX-2 in dose-dependent manners, whereas 8 inhibited only iNOS mRNA expression but did not affect on that of COX-2 gene. Xanthones might be the main anti-inflammatory components in C. formosum ssp. pruniflorum.

Asiatic acid alleviates hemodynamic and metabolic alterations via restoring eNOS/iNOS expression, oxidative stress, and inflammation in diet-induced metabolic syndrome rats

Asiatic acid is a triterpenoid isolated from Centella asiatica. The present study aimed to investigate whether asiatic acid could lessen the metabolic, cardiovascular complications in rats with metabolic syndrome (MS) induced by a high-carbohydrate, high-fat (HCHF) diet. Male Sprague-Dawley rats were fed with HCHF diet with 15% fructose in drinking water for 12 weeks to induce MS. MS rats were treated with asiatic acid (10 or 20 mg/kg/day) or vehicle for a further three weeks. MS rats had an impairment of oral glucose tolerance, increases in fasting blood glucose, serum insulin, total cholesterol, triglycerides, mean arterial blood pressure, heart rate, and hindlimb vascular resistance; these were related to the augmentation of vascular superoxide anion production, plasma malondialdehyde and tumor necrosis factor-alpha (TNF-α) levels (p<0.05). Plasma nitrate and nitrite (NOx) were markedly high with upregulation of inducible nitric oxide synthase (iNOS) expression, but dowregulation of endothelial nitric oxide synthase (eNOS) expression (p<0.05). Asiatic acid significantly improved insulin sensitivity, lipid profiles, hemodynamic parameters, oxidative stress markers, plasma TNF-α, NOx, and recovered abnormality of eNOS/iNOS expressions in MS rats (p<0.05). In conclusion, asiatic acid improved metabolic, hemodynamic abnormalities in MS rats that could be associated with its antioxidant, anti-inflammatory effects and recovering regulation of eNOS/iNOS expression.

Spatiotemporal expression of KHSRP modulates Schwann cells and neuronal differentiation after sciatic nerve injury

K-homology splicing regulator protein (KHSRP), a multifunctional RNA-binding protein, was originally thought to primarily control mRNA decay. KHSRP was shown to be involved in p38MAPK, NF-κB and the JAK2-STAT-1a pathways. Besides, KHSRP regulated neuronal localization of beta-actin and microtubule-associated protein 2 (MAP2) mRNAs, respectively. However, the expression and roles of KHSRP in peripheral system lesions and repair are still unknown. In our study, we found that KHSRP levels were relatively higher in the crushed sciatic nerves, significantly reached a highest level at day 5. Spatially, we observed that KHSRP had a major colocalization with Schwann cells (SCs) and neurons. KHSRP was connected with promyelinating SCs marker. KHSRP promoted the decay of beta-catenin (β-catenin) mRNA which was inactivated by PI3K-AKT signaling. We doubted that KHSRP might participate in Schwann cells differentiation by regulation of β-catenin mRNA decay. In vitro, in cyclic adenosine monophosphate (cAMP)-induced Schwann cells differentiation system, we detected the increased KHSRP in cytoplasm and decreased β-catenin at protein and mRNA level. In differentiation model of rat pheochromocytoma cells (PC12) induced by nerve growth factor (NGF) and primary dorsal root ganglion (DRG) cell culture, KHSRP also acted on neuronal differentiation. Specially, KHSRP-specific siRNA-transfected cells did not show morphological change, which was similar to β-catenin overexpressed SCs. During SC/neuron co-cultures, KHSRP was transported to cytoplasm and involved in SCs myelination. In conclusion, we speculated that KHSRP was involved in SCs and neuronal differentiation by inducing β-catenin mRNA decay.

Mycobacteria manipulate macrophage recruitment through coordinated use of membrane lipids

The evolutionary survival of Mycobacterium tuberculosis, the cause of human tuberculosis (TB), depends on its ability to invade the host, replicate, and transmit infection. At its initial peripheral infection site in the distal lung airways, M. tuberculosis infects macrophages which transport it to deeper tissues¹. How mycobacteria survive in these broadly microbicidal cells is an important question. Here we show that M. tuberculosis, and its close pathogenic relative Mycobacterium marinum, preferentially recruit and infect permissive macrophages while evading microbicidal ones. This immune evasion is accomplished by using cell surface associated phthiocerol dimycoceroserate (PDIM) lipids² to mask underlying pathogen-associated molecular patterns (PAMPs). In the absence of PDIM, these PAMPs signal a toll-like receptor (TLR)-dependent recruitment of macrophages that produce microbicidal reactive nitrogen species. Concordantly, the related phenolic glycolipids (PGL)², promote recruitment of permissive macrophages via a host chemokine receptor 2 (CCR2)-mediated pathway. Thus, we have identified coordinated roles for PDIM, known to be essential for mycobacterial virulence³ and PGL, which (along with CCR2) is known to be associated with human TB^4,5. Our findings also suggest an explanation for the longstanding observation that M. tuberculosis initiates infection in the relatively sterile environment of the lower respiratory tract, rather than in the upper respiratory tract, where resident microflora and inhaled environmental microbes may continually recruit microbicidal macrophages through TLR-dependent signaling.

Post-translational regulation of endothelial nitric oxide synthase in vascular endothelium

Nitric oxide (NO) is a short-lived gaseous signaling molecule. In blood vessels, it is synthesized in a dynamic fashion by endothelial nitric oxide synthase (eNOS) and influences vascular function via two distinct mechanisms, the activation of soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP)-dependent signaling and the S-nitrosylation of proteins with reactive thiols (S-nitrosylation). The regulation of eNOS activity and NO bioavailability is critical to maintain blood vessel function. The activity of eNOS and ability to generate NO is regulated at the transcriptional, posttranscriptional, and posttranslational levels. Post-translational modifications acutely impact eNOS activity and dysregulation of these mechanisms compromise eNOS activity and foster the development of cardiovascular diseases (CVDs). This review will intergrate past and current literature on the post-translational modifications of eNOS in both health and disease.

Direct interaction of natural and synthetic catechins with signal transducer activator of transcription 1 affects both its phosphorylation and activity

Our previous studies showed that (-)-epigallocatechin-3-gallate (EGCG) inhibits signal transducer activator of transcription 1 (STAT1) activation. Since EGCG may be a promising lead compound for new anti-STAT1 drug design, 15 synthetic catechins, characterized by the (-)-gallocatechin-3-gallate stereochemistry, were studied in the human mammary MDA-MB-231 cell line to identify the minimal structural features that preserve the anti-STAT1 activity. We demonstrate that the presence of three hydroxyl groups of B ring and one hydroxyl group in D ring is essential to preserve their inhibitory action. Moreover, a possible molecular target of these compounds in the STAT1 pathway was investigated. Our results demonstrate a direct interaction between STAT1 protein and catechins displaying anti-STAT1 activity. In particular, surface plasmon resonance (SPR) analysis and molecular modeling indicate the presence of two putative binding sites (a and b) with different affinity. Based on docking data, site-directed mutagenesis was performed, and interaction of the most active catechins with STAT1 was studied with SPR to test whether Gln518 on site a and His568 on site b could be important for the catechin-STAT1 interaction. Data indicate that site b has higher affinity for catechins than site a as the highest affinity constant disappears in the H568A-STAT1 mutant. Furthermore, Janus kinase 2 (JAK2) kinase assay data suggest that the contemporary presence in vitro of STAT1 and catechins inhibits JAK2-elicited STAT1 phosphorylation. The very tight catechin-STAT1 interaction prevents STAT1 phosphorylation and represents a novel, specific and efficient molecular mechanism for the inhibition of STAT1 activation.

Chlorinated didemnins from the tunicate Trididemnum solidum

Chemical investigation of the tunicate Trididemnum solidum resulted in the isolation of two new chlorinated compounds belonging to the didemnin class, along with two known compounds didemnin A and didemnin B. The structural determination of the compounds was based on extensive NMR and mass spectroscopic analysis. The isolated compounds 1-4 were tested for their anti-inflammatory activity using in vitro assays for inhibition of inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-κB) activity. The anti-cell proliferative activity of the above compounds was also evaluated against four solid tumor cell lines.

Apo-9'-fucoxanthinone, isolated from Sargassum muticum, inhibits CpG-induced inflammatory response by attenuating the mitogen-activated protein kinase pathway

Sargassum muticum (S. muticum) is a brown edible alga and widely distributed in Korea. This report was designed to evaluate the anti-inflammatory properties of apo-9'-fucoxanthinone (APO-9') isolated from S. muticum on pro-inflammatory cytokine production. S. muticum extract (SME) exhibited significant inhibitory effects on pro-inflammatory cytokine production in bone marrow-derived macrophages (BMDMs) and dendritic cells (BMDCs). APO-9' pre-treatment in the CpG DNA-stimulated BMDMs and BMDCs showed a strong dose-dependent inhibitory effect on interleukin (IL)-12 p40, IL-6 and tumor necrosis factor (TNF)-α production with IC50 values ranging from 5.31 to 13.79. It exhibited a strong inhibitory effect on the phosphorylation of ERK1/2 and on activator protein (AP)-1 reporter activity. APO-9' pre-treatment exhibited significant inhibition of CpG DNA-induced production of inducible nitric oxide synthase. Taken together, these data suggest that SME and APO-9' have a significant anti-inflammatory property and warrant further studies concerning the potentials of SME and APO-9' for medicinal use.

Ameliorative effect of naringenin on hyperglycemia-mediated inflammation in hepatic and pancreatic tissues of Wistar rats with streptozotocin- nicotinamide-induced experimental diabetes mellitus

In diabetes mellitus (DM), sustained hyperglycemia results in the generation of reactive oxygen species, ultimately leading to increased oxidative stress and inflammation in vital tissues. In the present study, possible ameliorative effects of naringenin on hyperglycemia-mediated inflammation in experimental streptozocin (STZ)-nicotinamide-induced DM were sought. DM was induced experimentally in overnight-fasted Wistar rats (150-180 g) by intra-peritoneal injection of STZ (50 mg/kg.b.w) and of nicotinamide (110 mg/kg.b.w); control rats (n = 6) received only vehicle (0.5 ml of 0.1 M of cold citrate buffer; pH 4.5). One group of diabetic rats (n = 6) was left untreated while another group of diabetic rats (n = 6) received naringenin (50 mg/kg b.w./day) orally for 21 days. At this time, hemotological indices (erythrocyte sedimentation rate [ESR], total white blood cell [WBC] count, differential WBC percentage, and platelet count) were measured. Significant alterations in expression of gene and protein biomarkers of inflammation in hepatic and pancreatic tissues were determined by measuring mRNA levels and the level of protein expressed, respectively, as was the total nitric oxide level in these tissues. Diabetic rats showed significantly higher mean ESR values, total WBC counts, differential WBC percentages, and platelet counts than those in control rats; similarly, mean mRNA levels of C-reactive protein, pro-inflammatory cytokine, nuclear factor-κB and inducible nitric oxide synthase genes and mean intensities of expression of the corresponding proteins in the hepatic and pancreatic tissue samples from diabetic rats significantly exceeded those in control rats. However, in diabetic rats treated with naringenin, the values of hematological, mRNA transcript and protein indices of inflammation were all lower than those in diabetic rats. These results suggest that naringenin possibly alleviates hyperglycemia-mediated inflammation in experimental STZ-nicotinamide-induced DM in Wistar rats.

Elevated incidence of polyp formation in APC(Min/⁺)Msh2⁻/⁻ mice is independent of nitric oxide-induced DNA mutations

Gut microbiota has been linked to a number of human diseases including colon cancer. However, the mechanism through which gut bacteria influence colon cancer development and progression remains unclear. Perturbation of the homeostasis between the host immune system and microbiota leads to inflammation and activation of macrophages which produce large amounts of nitric oxide that acts as a genotoxic effector molecule to suppress bacterial growth. However, nitric oxide also has genotoxic effects to host cells by producing mutations that can predispose to colon cancer development. The major DNA lesions caused by nitric oxide are 8oxoG and deamination of deoxycytosine bases. Cellular glycosylases that belong to the base excision repair pathway have been demonstrated to repair these mutations. Recent evidence suggests that the mismatch repair pathway (MMR) might also repair nitric oxide-induced DNA damage. Since deficiency in MMR predisposes to colon cancer, we hypothesized that MMR-deficient colon epithelial cells are incapable of repairing nitric-oxide induced genetic lesions that can promote colon cancer. Indeed, we found that the MMR pathway repairs nitric oxide-induced DNA mutations in cell lines. To test whether nitric oxide promotes colon cancer, we genetically ablated the inducible nitric oxide synthase (iNOS) or inhibited iNOS activity in the APC(Min/+)Msh2(-/-) mouse model of colon cancer. However, despite the fact that nitric oxide production was strongly reduced in the colon using both approaches, colon cancer incidence was not affected. These data show that nitric oxide and iNOS do not promote colon cancer in APC(Min/+)Msh2(-/-) mice.

ROS production in phagocytes: why, when, and where?

In the phagocytosis field, ROS production by the phagocyte NOX has been associated with pathogen killing for the last 50 years. Since the discovery of nonphagocyte NOX, numerous other roles for ROS production have been identified. Oxidative stress and ROS-mediated signaling have received much attention in recent years. Much lower concentrations of ROS may be required for signaling compared with microbial killing. Based on the discoveries in nonphagocytic cells, it became logical to look for ROS functions distinct from pathogen killing, even in phagocytes. ROS are now linked to various forms of cell death, to chemotaxis, and to numerous modifications of cellular processes, including the NOX itself. ROS functions are clearly concentration-dependent over a wide range of concentrations. How much is required for which function? Which species are required for how much time? Is ROS signaling only a side effect of bactericidal ROS production? One major obstacle to answer these questions is the difficulty of reliable quantitative ROS detection. Signal transduction often takes place on a subcellular scale over periods of seconds or minutes, so the detection methods need to provide appropriate time and space resolution. We present examples of local ROS production, decreased degradation, signaling events, and potentially ROS-sensitive functions. We attempt to illustrate the current limitations for quantitative spatiotemporal ROS detection and point out directions for ongoing development. Probes for localized ROS detection and for combined detection of ROS, together with protein localization or other cellular parameters, are constantly improved.

Hypericum perforatum L. subsp. perforatum induces inhibition of free radicals and enhanced phototoxicity in human melanoma cells under ultraviolet light

OBJECTIVES

Our interest continues in discovering phytocomplexes from medicinal plants with phototoxic activity against human melanoma cells; thus the aim of the present study was to assess antioxidant, anti-inflammatory and phototoxic activity of Hypericum perforatum L. subsp. perforatum, and relate these properties to the plant's chemical composition.

MATERIALS AND METHODS

Components of H. perforatum subsp. perforatum were extracted by hydroalcoholic solution and chemical profiles of preparations (HyTE-3) performed by HPTLC. Linoleic acid peroxidation and DPPH tests were used to assess antioxidant activity, while MTT assay allowed evaluation of anti-proliferative activity with respect to A375 human melanoma cells after irradiation with UVA dose, 1.8 J/cm(2) . Inhibition of nitric oxide production of macrophages was also investigated.

RESULTS

HyTE-3 indicated better antioxidant activity with β-carotene bleaching test in comparison to DPPH assay (IC50 = 0.89 μg/ml); significant phototoxicity in A375 cells at 78 μg/ml concentration resulted in cell destruction of 50%. HyTE-3 caused significant dose-related inhibition of nitric oxide production in murine monocytic macrophage cell line RAW 264.7 with IC50 value of 342 μg/ml.

CONCLUSIONS

The H. perforatum subsp. perforatum-derived product was able to suppress proliferation of human malignant melanoma A375 cells; extract together with UVA irradiation enhanced phototoxicity. This biological activity of antioxidant effects was combined with inhibition of nitric oxide production.

Dipterinyl calcium pentahydrate inhibits intracellular mycobacterial growth in human monocytes via the C-C chemokine MIP-1β and nitric oxide

Tuberculosis remains one of the top three leading causes of morbidity and mortality worldwide, complicated by the emergence of drug-resistant Mycobacterium tuberculosis strains and high rates of HIV coinfection. It is important to develop new antimycobacterial drugs and immunomodulatory therapeutics and compounds that enhance antituberculous immunity. Dipterinyl calcium pentahydrate (DCP), a calcium-complexed pterin compound, has previously been shown to inhibit human breast cancer cells and hepatitis B virus (HBV). DCP inhibitory effects were attributed to induction of apoptosis and/or increased production of interleukin 12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF). In this study, we tested the ability of DCP to mediate inhibition of intracellular mycobacteria within human monocytes. DCP treatment of infected monocytes resulted in a significant reduction in viability of intracellular but not extracellular Mycobacterium bovis BCG. The antimicrobial activity of DCP was comparable to that of pyrazinamide (PZA), one of the first-line antituberculosis drugs currently used. DCP potentiated monocyte antimycobacterial activity by induction of the cysteine-cysteine (C-C) chemokine macrophage inflammatory protein 1β (MIP-1β) and inducible nitric oxide synthase 2. Addition of human anti-MIP-1β neutralizing antibody or a specific inhibitor of the l-arginase-nitric oxide pathway (N(G)-monomethyl l-arginine [l-NMMA] monoacetate) reversed the inhibitory effects of DCP on intracellular mycobacterial growth. These findings indicate that DCP induced mycobacterial killing via MIP-1β- and nitric oxide-dependent effects. Hence, DCP acts as an immunoregulatory compound enhancing the antimycobacterial activity of human monocytes.

Targeting estrogen receptor β in microglia and T cells to treat experimental autoimmune encephalomyelitis

A therapeutic goal in the treatment of certain CNS diseases, including multiple sclerosis, amyotrophic lateral sclerosis, and Parkinson disease, is to down-regulate inflammatory pathways. Inflammatory molecules produced by microglia are responsible for removal of damaged neurons, but can cause collateral damage to normal neurons located close to defective neurons. Although estrogen can inactivate microglia and inhibit the recruitment of T cells and macrophages into the CNS, there is controversy regarding which of the two estrogen receptors (ERs), ERα or ERβ, mediates the beneficial effects in microglia. In this study, we found that ERβ, but not ERα, is expressed in microglia. Using the experimental autoimmune encephalomyelitis (EAE) model in SJL/J mice, we evaluated the benefit of an ERβ agonist as a modulator of neuroinflammation. Treatment of EAE mice with LY3201, a selective ERβ agonist provided by Eli Lilly, resulted in marked reduction of activated microglia in the spinal cord. LY3201 down-regulated the nuclear transcription factor NF-κB, as well as the NF-κB-induced gene inducible nitric oxide synthase in microglia and CD3(+) T cells. In addition, LY3201 inhibited T-cell reactivity through regulation of indoleamine-2,3-dioxygenase. In the EAE model, treatment with LY3201 decreased mortality in the first 2 wk after disease onset, and also reduced the severity of symptoms in mice surviving for 4 wk. Our data show that ERβ-selective agonists, by modulating the immune system in both microglia and T cells, offer promise as a useful class of drugs for treating degenerative diseases of the CNS.

Association of eNOS polymorphisms (-786T>C, 4a4b, 894G>T) with colorectal cancer susceptibility in the Korean population

BACKGROUND

Polymorphisms of endothelial nitric oxide synthases (eNOS) have been shown to be associated with cancer susceptibility. However, the results of such studies are conflicting to date. We investigated whether polymorphisms of the eNOS gene correlated with patients with colorectal cancer (CRC), relative to healthy individuals.

PATIENTS AND METHODS

In the present study, we analyzed three polymorphisms of eNOS (-786T>C, 4a4b, and 894G>T) in 509 healthy controls and 528 patients with CRC. The genotyping of eNOS polymorphisms was performed using polymerase chain reaction or polymerase chain reaction-restriction fragment length polymorphism assays.

RESULTS

We found that the TC+CC genotype of the -786T>C polymorphism was significantly associated with an increased risk of CRC compared with the TT genotype. Similarly, the GT+TT genotype of the 894G>T polymorphism was associated with an increased susceptibility to CRC. However, no evidence was found for any association between the 4a4b polymorphism and CRC risk. In addition, the C/4b/G (-786T>C/4a4b/894G>T) haplotype was significantly associated with increased risk of CRC and C/4b/T (-786T>C/4a4b/894G>T) haplotype was only detected in CRC patients.

CONCLUSIONS

Our study suggests that the eNOS -786T>C and 894G>T polymorphisms may be associated with the development of CRC in the Korean population.

Anti-inflammatory effect of berkeleyacetal C through the inhibition of interleukin-1 receptor-associated kinase-4 activity

Berkeleyacetal C (BAC) isolated from Penicillium sp. which had isolated from a soil sample collected in Fukushima, inhibited NO production and induction of iNOS protein in RAW264.7 cells stimulated by the Toll-like receptor (TLR) 2 ligand, peptidoglycan (PGN) or TLR4 ligand, lipopolysaccharide (LPS). The other inflammatory mediator production by these stimulators was also suppressed by BAC in a concentration-dependent manner. BAC inhibited LPS- or PGN-activated nuclear translocation of nuclear factor (NF)-κB and MyD88-dependent signaling molecules. However, it showed no effect on LPS-induced nuclear translocation of interferon regulatory factor (IRF)-3, a MyD88-independent signaling molecule. To clarify the mechanistic basis for BAC ability to inhibit translocation of NF-κB and activated MyD88-dependent signaling molecules, we examined interleukin-1 receptor-associated kinase (IRAK)-4, existing to the most upstream on MyD88-dependent signaling molecules, in vitro kinase assay. BAC suppressed IRAK-4 kinase activity in a concentration-dependent manner. These findings suggest that BAC inhibits LPS- and PGN- induced NO production and iNOS expression by decreasing the level of the translocating of NF-κB in nuclear through inhibiting the kinase activity of IRAK-4 in inflammatory cells.

17β-Estradiol attenuates cytokine-induced nitric oxide production in rat hepatocyte

OBJECTIVE

Nitric oxide (NO) regulation during shock and sepsis is complex. NO production by endothelial NO synthase maintains microvascular perfusion and prevents shock-induced organ injury. However, the overproduction of NO by inducible NO synthase (iNOS) contributes to liver dysfunction after shock and is associated with increased tissue damage and mortality. Estrogen improves organ function and outcome after shock and sepsis, but the mechanism is unknown. We hypothesized that 17β-estradiol would improve organ function by regulating the production of hepatocyte NO.

METHODS

Isolated rat hepatocytes were stimulated in vitro with pro-inflammatory cytokines to induce NO synthesis with or without estrogen. Nitrite was detected after 24 hours. INOS protein was determined using Western blot analysis.

RESULTS

Cytokine stimulation increased nitrite and iNOS protein in a dose-dependent manner. The cytokine-induced nitrite increase was significantly decreased by estrogen. iNOS expression was also diminished in cultures with the higher doses of estrogen.

CONCLUSION

17β-Estradiol decreases cytokine-stimulated iNOS expression and NO production. The down-regulation of iNOS expression may account for the beneficial role of estrogens in models of sepsis and shock.

Decreased levels of nitric oxide production and nitric oxide synthase-2 expression are associated with the development and metastasis of hepatocellular carcinoma

Many studies have demonstrated the function of nitric oxide (NO) or nitric oxide synthase-2 (NOS-2) in cancer as pro-neoplastic or anti-neoplastic effectors, but the role of NO and NOS-2 in hepatocellular carcinoma (HCC) remains unclear. The aim of this study was to investigate the levels of NO production and NOS-2 expression in HCC and adjacent non-tumor liver tissues and to clarify whether the levels of NO/NOS-2 are related to the clinicopathological features of HCC. The levels of NO production were examined in tumor and adjacent non-tumor liver tissues of 30 patients with HCC. The expression of NOS-2 was detected by real-time polymerase chain reaction (RT-PCR) and immunohistochemical analysis in HCC and/or adjacent non-tumor liver tissues. Mutant p53 and proliferating cell nuclear antigen (PCNA) were also immunohistochemically investigated in liver tissues. The levels of NO in HCC were significantly lower compared to adjacent non-tumor liver tissues (P<0.001). The relative mRNA and protein expression levels of NOS-2 in HCC were also significantly lower compared to adjacent non-tumor liver tissues (P<0.01 for both). We found that the levels of NO in patients suffering from HCC metastasis were lower compared to those without metastasis (P<0.05) and NOS-2 expression was correlated with tumor diameter (P<0.05) and metastasis (P<0.05). In addition, mutant p53 protein was expressed in the majority of HCC samples and the proliferation rate of HCC was significantly higher than that of adjacent non-tumor liver tissues. These data indicate that decreased levels of NO/NOS-2 may partially contribute to overexpression of the mutant p53 protein and excessive proliferation; this may be a potential mechanism in the development and progression of HCC.

Alpha-1-antitrypsin inhibits nitric oxide production

NO is an endogenously produced gas that regulates inflammation, vascular tone, neurotransmission, and immunity. NO production can be increased by exposing cells to several endogenous and exogenous proinflammatory mediators, including IFN-γ, TNF-α, IL-1β, and LPS. As AAT has been shown to inhibit cell activation and suppress cytokine production associated with proinflammatory stimulation, we examined AAT for NO-suppressive function. In RAW 264.7 murine macrophagic cells, physiological AAT concentrations significantly inhibited combined LPS- and IFN-γ-induced NO synthesis, and NO synthesis inhibition was associated with decreased expression of iNOS, suppressed NF-κB activation, and reduced translocation of extracellular AAT into the interior of RAW 264.7 cells. CE-2072, a synthetic inhibitor of serine proteases, also suppressed NO production, iNOS expression, and NF-κB activation. However, AAT did not alter activation of intracellular MAPKs. In subjects with genetic AAT deficiency, exhaled NO was increased significantly compared with exhaled NO in healthy controls. These in vitro and in vivo studies suggest that AAT is an endogenous inhibitor of NO production. Administering AAT or AAT-like molecules may have use as a treatment for diseases associated with excessive NO production.

Molecular Mechanisms Underlying Anti-Inflammatory Actions of 6-(Methylsulfinyl)hexyl Isothiocyanate Derived from Wasabi (Wasabia japonica)

6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC) is a major bioactive compound in wasabi (Wasabia japonica), which is a typical Japanese pungent spice. Recently, in vivo and in vitro studies demonstrated that 6-MSITC has several biological properties, including anti-inflammatory, antimicrobial, antiplatelet, and anticancer effects. We previously reported that 6-MSITC strongly suppresses cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cytokines, which are important factors that mediate inflammatory processes. Moreover, molecular analysis demonstrated that 6-MSITC blocks the expressions of these factors by suppressing multiple signal transduction pathways to attenuate the activation of transcriptional factors. Structure-activity relationships of 6-MSITC and its analogues containing an isothiocyanate group revealed that methylsulfinyl group and the length of alkyl chain of 6-MSITC might be related to high inhibitory potency. In this paper, we review the anti-inflammatory properties of 6-MSITC and discuss potential molecular mechanisms focusing on inflammatory responses by macrophages.

Auditory cells produce nitric oxide in response to bacterial lipopolysaccharide

The NO productivity of auditory cells in response to LPS was examined by using conditionally immortalized murine HEI-OC1 auditory cells. HEI-OC1 cells produced NO in response to LPS ranging from 0.1 µg/ml to 100 µg/ml in a concentration-dependent manner. LPS at 100 µg/ml exhibited no cytotoxic action against HEI-OC1 cells and led to the highest level of NO production. The NO output in LPS-treated HEI-OC1 cells gradually increased up to 72 h. LPS-induced NO production was mediated by the expression of an inducible NO synthase (iNOS) protein. TLR4 and CD14 was expressed on the cell surface of HEI-OC1 cells. LPS augmented the production of IFN-β in the MyD88-independent pathway of LPS signalling. HEI-OC1 cells produced NO in response to a TLR2 ligand but not TLR3 ligand. LPS was suggested to lead to NO production in auditory cells via iNOS expression. The immunological significance of NO production in auditory cells is discussed.

Anti-inflammatory homoisoflavonoids from the tuberous roots of Ophiopogon japonicus

Two new homoisoflavonoids, named ophiopogonone E (1) and ophiopogonanone H (2), together with thirteen known ones (3-15) were isolated from the tuberous roots of Ophiopogon japonicus. Their structures were elucidated by spectroscopic and chemical analyses. Compounds 7 and 15 were isolated from the genus for the first time. In addition, compounds 2-15 were evaluated for their effects on the inhibition of NO production induced by lipopolysaccharide in the murine microglial cell line BV-2. Compounds 2, 4, 6, 7, 10, 11 showed potent inhibitory effects on NO production with IC(50) values of 20.1, 17.0, 7.8, 5.1, 19.2 and 14.4 μM respectively.

Anticancer agent 2-methoxyestradiol improves survival in septic mice by reducing the production of cytokines and nitric oxide

Cytokine production is critical in sepsis. 2-Methoxyestradiol (2ME2), an endogenous metabolite of estradiol, inhibits hypoxia-inducible factor 1α (HIF-1α) and is an antiangiogenic and antitumor agent. We investigated the effect of 2ME2 on cytokine production and survival in septic mice. Using i.p. LPS or cecal ligation and puncture (CLP), sepsis was induced in BALB/c mice that were simultaneously or later treated with 2ME2 or vehicle. Twelve hours after the LPS injection, serum and peritoneal fluid cytokine and nitric oxide (NO) levels were analyzed using enzyme-linked immunosorbent assay and the Griess reaction. Lung injuries were histologically analyzed, and liver and kidney injuries were biochemically analyzed. Survival was determined 7 days after LPS injection or CLP procedure. In vivo and in vitro effects of 2ME2 on LPS-induced macrophage inflammation were determined. The effect of 2ME2 on HIF-1α expression, nuclear factor κB (NF-κB), and inducible NO synthase (iNOS) in LPS-treated RAW264.7 cells, a murine macrophage cell line, was determined using Western blotting. 2-Methoxyestradiol treatment reduced LPS-induced lung, liver, and kidney injury. Both early and late 2ME2 treatment prolonged survival in LPS- and CLP-induced sepsis. 2-Methoxyestradiol significantly reduced IL-1β, IL-6, TNF-α, and NO levels in septic mice as well as in LPS-stimulated peritoneal macrophages. 2-Methoxyestradiol treatment also reduced the LPS-induced expression of HIF-1α, iNOS, and pNF-κB in RAW264.7 cells, as well as iNOS and pNF-κB expression in siHIF-1α-RAW264.7 cells. 2-Methoxyestradiol prolongs survival and reduces lung, liver, and kidney injury in septic mice by inhibiting iNOS/NO and cytokines through HIF-1α and NF-κB signaling.

miRNA-939 regulates human inducible nitric oxide synthase posttranscriptional gene expression in human hepatocytes

Human inducible nitric oxide synthase (hiNOS) gene expression is regulated by transcriptional and posttranscriptional mechanisms. The purpose of this study was to determine whether specific microRNA (miRNA) directly regulate hiNOS gene expression. Sequence analysis of the 496-bp hiNOS 3'-untranslated region (3'-UTR) revealed five putative miR-939 binding sites. The hiNOS 3'-UTR conferred significant posttranscriptional blockade of luciferase activity in human A549, HCT8, and HeLa cells. The hiNOS 3'-UTR also exerted basal and cytokine-stimulated posttranscriptional repression in an orientation-dependent manner. Functional studies demonstrated that transfection of miR-939 into primary human hepatocytes (HCs) significantly inhibited cytokine-induced NO synthesis in a dose-dependent manner that was abrogated by a specific miR-939 inhibitor. MiR-939 (but not other miRNAs) abolished cytokine-stimulated hiNOS protein in human HC, but had no effect on hiNOS mRNA levels. Site-directed mutagenesis of miR-939 bindings sites at +99 or +112 bp in the hiNOS 3'-UTR increased reporter gene expression. Furthermore, intact miR-939 binding sites at +99 or +112 positions were required for posttranscriptional suppression by miR-939. Cytokine stimulation directly increased miR-939 levels in human HC. Transfection of miR-939 inhibitor (antisense miR-939) enhanced cytokine-induced hiNOS protein and increased NO synthesis in vitro in human HC. Finally, cytokine or LPS injection in vivo in mice increased hepatic miR-939 levels. Taken together, these data identify that miR-939 directly regulates hiNOS gene expression by binding in the 3'-UTR to produce a translational blockade. These findings suggest dual regulation of iNOS gene expression where cytokines induce iNOS transcription and also increase miR-939, leading to translational inhibition in a check-and-balance system.

Unchanged interleukin 6 level of protein and energy restricted goats during late gestation: the role of elevated blood nitric oxide

Twelve pregnant goats were assigned to three dietary treatments during late gestation, namely control (C: metabolizable energy, 5.75 MJ/kg; crude protein, 12.6% and dry matter basis), 40% protein restricted (PR) and 40% energy restricted (ER), to examine the effects of nutrient restriction on the immune status of pregnant goats. Plasma was sampled on day 90, 125 and 145 from pregnant goats to determine cytokine production (interleukin 2 (IL2), IL6) and tumor necrosis factor α (TNFα)). Peripheral blood mononuclear cells were obtained on day 145 and activated by lipopolysaccharide to determine cytokine production, and then exposed (PR and ER) to sodium nitroprusside (SNP), a nitric oxide (NO) donor, or control to NG-nitro-l-arginine methyl ester hydrochloride (l-NAME), an NO synthase inhibitor to explore the role of NO in regulating cytokine production. Plasma IL2, IL6 and TNFα were not altered during gestation, but NO was increased (P<0.05) at gestation day 145 for PR and ER. In vitro, compared with control, NO was lower for PR and ER (P<0.001), but IL6 was higher for PR (P<0.001) and ER (P=0.11). The addition of SNP decreased IL6 (P<0.001, PR; P=0.12, ER) in the malnourished group, and l-NAME increased (P<0.001) IL6 in control compared to those treatments without SNP or l-NAME. The results indicate that plasma NO acted as a regulator of cytokine function exhibiting negative feedback to maintain steady plasma IL6 concentration in PR or ER goats during late gestation.

Effects of Litchi chinensis fruit isolates on prostaglandin E(2) and nitric oxide production in J774 murine macrophage cells

BACKGROUND

Litchi chinensis is regarded as one of the 'heating' fruits in China, which causes serious inflammation symptoms to people.

METHODS

In the current study, the effects of isolates of litchi on prostaglandin E(2) (PGE(2)) and nitric oxide (NO) production in J774 murine macrophage cells were investigated.

RESULTS

The AcOEt extract (EAE) of litchi was found effective on stimulating PGE(2) production, and three compounds, benzyl alcohol, hydrobenzoin and 5-hydroxymethyl-2-furfurolaldehyde (5-HMF), were isolated and identified from the EAE. Benzyl alcohol caused markedly increase in PGE(2) and NO production, compared with lipopolysaccharide (LPS) as positive control, and in a dose-dependent manner. Hydrobenzoin and 5-HMF were found in litchi for the first time, and both of them stimulated PGE(2) and NO production moderately in a dose-dependent manner. Besides, regulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNA expression and NF-κB (p50) activation might be involved in mechanism of the stimulative process.

CONCLUSION

The study showed, some short molecular compounds in litchi play inflammatory effects on human.

β-Glucan from Lentinus edodes inhibits nitric oxide and tumor necrosis factor-α production and phosphorylation of mitogen-activated protein kinases in lipopolysaccharide-stimulated murine RAW 264.7 macrophages

Lentinan (LNT), a β-glucan from the fruiting bodies of Lentinus edodes, is well known to have immunomodulatory activity. NO and TNF-α are associated with many inflammatory diseases. In this study, we investigated the effects of LNT extracted by sonication (LNT-S) on the NO and TNF-α production in LPS-stimulated murine RAW 264.7 macrophages. The results suggested that treatment with LNT-S not only resulted in the striking inhibition of TNF-α and NO production in LPS-activated macrophage RAW 264.7 cells, but also the protein expression of inducible NOS (iNOS) and the gene expression of iNOS mRNA and TNF-α mRNA. It is surprising that LNT-S enhanced LPS-induced NF-κB p65 nuclear translocation and NF-κB luciferase activity, but severely inhibited the phosphorylation of JNK1/2 and ERK1/2. The neutralizing antibodies of anti-Dectin-1 and anti-TLR2 hardly affected the inhibition of NO production. All of these results suggested that the suppression of LPS-induced NO and TNF-α production was at least partially attributable to the inhibition of JNK1/2 and ERK1/2 activation. This work discovered a promising molecule to control the diseases associated with overproduction of NO and TNF-α.

Chemoprevention of Colon Cancer by iNOS-Selective Inhibitors

Nitric oxide (NO) is a short-lived pleiotropic regulator and is required for numerous pathophysiological functions, including macrophage-mediated immunity and cancer. It is a highly reactive free radical produced from l-arginine by different isoforms of NO synthases (NOSs). Sustained induction of inducible NOS (iNOS) during chronic inflammatory conditions leads to the formation of reactive intermediates of NO, which are mutagenic and cause DNA damage or impairment of DNA repair, alter cell signaling, and promote proinflammatory and angiogenic properties of the cell, thus contributing to carcinogenesis. Besides its well-established role in inflammation, increased expression of iNOS has been observed in colorectal tumors and other cancers. NO-related signaling pathways involved in colon tumorigenesis seem to progress through stimulation of proinflammatory cytokines and via posttranslational protein modifications of important antiapoptotic molecules in the tumors. NO can stimulate and enhance tumor cell proliferation by promoting invasive, angiogenic, and migratory activities. In contrast, studies also suggest that high levels of NO may be protective against tumor growth by inducing tumor cell death. However, a number of in vitro studies and particularly experimental animal data support the notion that NO and its reactive metabolite peroxynitrite stimulate cyclooxygenase-2 activity, leading to generation of prostaglandins that enhance tumor growth. These prostaglandins further augment tumor promotion and invasive properties of tumor cells. Hence, selective inhibitors of iNOS and combination strategies to inhibit both iNOS and cyclooxygenase-2 may have a preventive role in colon cancer.

In Vitro and in Vivo Therapeutics of β-Thujaplicin on Lps-Induced Inflammation in Macrophages and Septic Shock in Mice

β-thujaplicin, an active constituent from Chamaecyparis obtusa, has been shown to have acaricidal and antimicrobial effects. Very few studies have focused on the potential of the anti-inflammatory effect of β-thujaplicin. Moreover, its capability of inhibiting inflammatory mediators e.g. TNF-α gene transcription, nitric oxide (NO) and prostaglandin E2, remains unknown. Besides those molecular mechanisms behind the anti-inflammatory effect of β-thujaplicin, solid proof of its effectiveness in vivo has not yet been studied. In our study, in vitro effects of β-thujaplicin were verified on RAW 264.7 macrophages which were stimulated by LPS. Indomethacin was used as a positive control. The inducible NO production after stimulation was measured by Griess reagent. PGE2, IL-6 and TNF-α were measured by ELISA methods. Protein expressions of iNOS, COX2, and NF-κB were evaluated by Western blotting. Septic ICR mice were administered 20 mg/kg of LPS and then the mortality rate was monitored. Within the concentration range which was devoid of cytotoxicty, β-thujaplicin exhibited a clear dose-dependent inhibition on LPS-induced NO production. Furthermore, β-thujaplicin inhibited LPS-induced PGE2, IL-6, and TNF-α production as well as iNOS, COX2, and NF-κB protein expression more substantially potent than indomethacin. In agreement with the in vitro study, β-thujaplicin was shown to be effective in vivo for inhibiting LPS-induced NO and TNF-α production and a significant decrease in mortality rate of mice suffering from septic shock was observed. This study demonstrates the potential of β-thujaplicin in treatment of inflammation and sepsis. These effects occur through an efficient blockage of TNF-α and iNOS production, β-thujaplicin efficacy is comparable to that of indomethacin thus it can be a substitution but bear less depletion of PGE2, making this compound very promising in clinical applications.