Absence of inducible nitric oxide synthase modulates early reperfusion-induced NF-kappaB and AP-1 activation and enhances myocardial damage

Inhibition of the AP-1/TFPI2 axis contributes to alleviating cerebral ischemia/reperfusion injury by improving blood-brain barrier integrity

Reperfusion after cerebral ischemia leads to secondary damage to the nervous system, called cerebral ischemia/reperfusion injury (CIRI). The blood-brain barrier (BBB) consists of endothelial cells and tight junction (TJ) proteins, and its disruption aggravates CIRI. Two GSE datasets identified Tissue Factor Pathway Inhibitor 2 (TFPI2) as a differentially upregulated gene (Log2FC > 1, p < 0.01) in the cerebral cortex of ischemic rats, and TFPI2 affects angiogenesis of endothelial cells. Moreover, genes (c-Jun, c-Fos, FosL1) encoding subunits of Activator Protein-1 (AP-1), a transcription factor involved in IRI, were highly expressed in ischemic samples. Thus, the effects of the AP-1/TFPI2 axis on CIRI were explored. We determined increased TFPI2 expression in the cerebral cortex of rats receiving middle cerebral artery occlusion (MCAO) for 90 min and reperfusion (R) for 48 h. Then AAV2-shTFPI2 particles (5 × 1010 vg) were injected into the right lateral ventricle of rats 3 weeks before MCAO/R. TFPI2 knockdown decreased infarct size and neuronal injury in ischemic rats. It improved BBB integrity, demonstrated by reduced FITC-dextran leakage in brain tissues of MCAO/R-operated rats. Furthermore, it increased the expression of TJ proteins (Occludin, Claudin-5, TJP-1) in the cerebral cortex of rats with CIRI. Consistently, we found that TFPI2 knockdown mitigated cell damage in mouse endothelial bEND.3 cells with oxygen and glucose deprivation (ODG) for 6 h and reoxygenation (R) for 18 h (OGD/R) treatment. High co-expression of c-Jun and c-Fos significantly elevated TFPI2 promoter activity. c-Jun knockdown inhibited TFPI2 expression in OGD/R-treated bEND.3 cell. Collectively, our findings demonstrate that inhibition of the AP-1/TFPI2 axis alleviates CIRI.

NO-IL-6/10-IL-1β axis: a new pathway in steatotic and non-steatotic liver grafts from brain-dead donor rats

Introduction

Brain death (BD) and steatosis are both risk factors for organ dysfunction or failure in liver transplantation (LT).

Material and methods

Here, we examine the role of interleukin 6 (IL- 6) and IL-10 in LT of both non-steatotic and steatotic liver recovered from donors after brain death (DBDs), as well as the molecular signaling pathways underlying the effects of such cytokines.

Results

BD reduced IL-6 levels only in nonsteatotic grafts, and diminished IL-10 levels only in steatotic ones. In both graft types, BD increased IL-1β, which was associated with hepatic inflammation and damage. IL-6 administration reduced IL-1β only in non-steatotic grafts and protected them against damage and inflammation. Concordantly, IL-1β inhibition via treatment with an IL-1 receptor antagonist caused the same benefits in non-steatotic grafts. Treatment with IL-10 decreased IL-1β only in steatotic grafts and reduced injury and inflammation specifically in this graft type. Blockading the IL-1β effects also reduced damage and inflammation in steatotic grafts. Also, blockade of IL-1β action diminished hepatic cAMP in both types of livers, and this was associated with a reduction in liver injury and inflammation, then pointing to IL-1β regulating cAMP generation under LT and BD conditions. Additionally, the involvement of nitric oxide (NO) in the effects of interleukins was evaluated. Pharmacological inhibition of NO in LT from DBDs prompted even more evident reductions of IL-6 or IL-10 in non-steatotic and steatotic grafts, respectively. This exacerbated the already high levels of IL-1β seen in LT from DBDs, causing worse damage and inflammation in both graft types. The administration of NO donors to non-steatotic grafts potentiated the beneficial effects of endogenous NO, since it increased IL-6 levels, and reduced IL-1β, inflammation, and damage. However, treatment with NO donors in steatotic grafts did not modify IL-10 or IL-1β levels, but induced more injurious effects tan the induction of BD alone, characterized by increased nitrotyrosine, lipid peroxidation, inflammation, and hepatic damage.

Conclusion

Our study thus highlights the specificity of new signaling pathways in LT from DBDs: NO-IL-6-IL-1β in non-steatotic livers and NO-IL-10-IL-1β in steatotic ones. This opens up new therapeutic targets that could be useful in clinical LT.

IgG Galactosylation status combined with MYOM2-rs2294066 precisely predicts anti-TNF response in ankylosing spondylitis

Background

Tumor necrosis factor (TNF) blockers have a high efficacy in treating Ankylosing Spondylitis (AS), yet up to 40% of AS patients show poor or even no response to this treatment. In this paper, we aim to build an approach to predict the response prior to clinical treatment.

Methods

AS patients during the active progression were included and treated with TNF blocker for 3 months. Patients who do not fulfill ASASAS40 were considered as poor responders. The Immunoglobulin G galactosylation (IgG-Gal) ratio representing the quantity of IgG galactosylation was calculated and candidate single nucleotide polymorphisms (SNPs) in patients treated with etanercept was obtained. Machine-learning models and cross-validation were conducted to predict responsiveness.

Results

Both IgG-Gal ratio at each time point and differential IgG-Gal ratios between week 0 and weeks 2, 4, 8, 12 showed significant difference between responders and poor-responders. Area under curve (AUC) of the IgG-Gal ratio prediction model was 0.8 after cross-validation, significantly higher than current clinical indexes (C-reactive protein (CRP) = 0.65, erythrocyte sedimentation rate (ESR) = 0.59). The SNP MYOM2-rs2294066 was found to be significantly associated with responsiveness of etanercept treatment. A three-stage approach consisting of baseline IgG-Gal ratio, differential IgG-Gal ratio in 2 weeks, and rs2294066 genotype demonstrated the ability to precisely predict the response of anti-TNF therapy (100% for poor-responders, 98% for responders).

Conclusions

Combination of different omics can more precisely to predict the response of TNF blocker and it is potential to be applied clinically in the future.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0093-2) contains supplementary material, which is available to authorized users.

Leukocyte iNOS is required for inflammation and pathological remodeling in ischemic heart failure

In the failing heart, iNOS is expressed by both macrophages and cardiomyocytes. We hypothesized that inflammatory cell-localized iNOS exacerbates left ventricular (LV) remodeling. Wild-type (WT) C57BL/6 mice underwent total body irradiation and reconstitution with bone marrow from iNOS^-/- mice (iNOS^-/-c) or WT mice (WTc). Chimeric mice underwent coronary ligation to induce large infarction and ischemic heart failure (HF), or sham surgery. After 28 days, as compared with WTc sham mice, WTc HF mice exhibited significant (p < 0.05) mortality, LV dysfunction, hypertrophy, fibrosis, oxidative/nitrative stress, inflammatory activation, and iNOS upregulation. These mice also exhibited a ~twofold increase in circulating Ly6C^hi pro-inflammatory monocytes, and ~sevenfold higher cardiac M1 macrophages, which were primarily CCR2^- cells. In contrast, as compared with WTc HF mice, iNOS^-/-c HF mice exhibited significantly improved survival, LV function, hypertrophy, fibrosis, oxidative/nitrative stress, and inflammatory activation, without differences in overall cardiac iNOS expression. Moreover, iNOS^-/-c HF mice exhibited lower circulating Ly6C^hi monocytes, and augmented cardiac M2 macrophages, but with greater infiltrating monocyte-derived CCR2⁺ macrophages vs. WTc HF mice. Lastly, upon cell-to-cell contact with naïve cardiomyocytes, peritoneal macrophages from WT HF mice depressed contraction, and augmented cardiomyocyte oxygen free radicals and peroxynitrite. These effects were not observed upon contact with macrophages from iNOS^-/- HF mice. We conclude that leukocyte iNOS is obligatory for local and systemic inflammatory activation and cardiac remodeling in ischemic HF. Activated macrophages in HF may directly induce cardiomyocyte contractile dysfunction and oxidant stress upon cell-to-cell contact; this juxtacrine response requires macrophage-localized iNOS.

Altered AP-1/Ref-1 redox pathway and reduced proliferative response in iNOS-deficient vascular smooth muscle cells

We previously reported that injury-induced medial vascular smooth muscle cell (VSMC) proliferation and neointima formation in carotid arteries of inducible nitric oxide synthase knockout (iNOS KO) mice were significantly reduced compared with wild type (WT). However, the molecular pathway underlying such differences is not known. In this in vitro study, we discovered that the AP-1/Ref-1/thioredoxin signaling pathway is altered in aortic VSMC from iNOS KO mice, which leads to reduced growth response when compared with aortic VSMC from WT mice. After equal initial seeding, the cell number after 7 days in serum medium was less in iNOS KO cells compared with WT VSMC (1.2-0.6-105 vs 3.2-1.1-105; p < 0.05). Significantly more iNOS KO cells remained in the G0/G1 phase compared with WT cells after 24-h serum treatment (82.6-13.7% vs 62.3-14.6%; p < 0.05) by cell-cycle analysis. Nuclear PCNA expression was also less in the iNOS KO cells, which was not affected by exogenous NO or superoxide. Superoxide generation after 24-h serum stimulation was less in the iNOS KO cells compared with WT cells. After 30-min serum stimulation, AP-1 DNA binding was reduced and a lack of increase in nuclear c-Jun protein was observed in iNOS KO VSMC. RT-PCR analysis confirmed a lack of inducible c-Jun mRNA after serum stimulation in the KO cells. In addition, KO cells had less nuclear reducing factor-1 (Ref-1) and serum-inducible thioredoxin protein expression. Reduced proliferative response of iNOS KO VSMC to serum treatment is associated with altered AP-1/Ref-1/thioredoxin pathway activation.

The mechanisms of cardio-protective effects of desflurane and sevoflurane at the time of reperfusion: anaesthetic post-conditioning potentially translatable to humans?

Myocardial conditioning is actually an essential strategy in the management of ischaemia-reperfusion injury. The concept of anaesthetic post-conditioning is intriguing, its action occurring at a pivotal moment (that of reperfusion when ischaemia reperfusion lesions are initiated) where the activation of these cardio-protective mechanisms could overpower the mechanisms leading to ischaemia reperfusion injuries. Desflurane and sevoflurane are volatile anaesthetics frequently used during cardiac surgery. This review focuses on the efficacy of desflurane and sevoflurane administered during early reperfusion as a potential cardio-protective strategy. In the context of experimental studies in animal models and in human atrial tissues in vitro, the mechanisms underlying the cardio-protective effect of these agents and their capacity to induce post-conditioning have been reviewed in detail, underlining the role of reactive oxygen species generation, the activation of the cellular signalling pathways, and the actions on mitochondria along with the translatable actions in humans; this might well be sufficient to set the basis for launching randomized clinical studies, actually needed to confirm this strategy as one of real impact.

Aschantin targeting on the kinase domain of mammalian target of rapamycin suppresses epidermal growth factor-induced neoplastic cell transformation

Mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, forms two different complexes, complex 1 and 2, and plays a key role in the regulation of Akt signaling-mediated cell proliferation and transformation. This study reveals aschantin, a natural compound abundantly found in Magnolia flos, as a novel mTOR kinase inhibitor. Aschantin directly targeted the active pocket of mTOR kinase domain by competing with adenosine triphosphate (ATP), but not PI3K and PDK1. Aschantin inhibited epidermal growth factor (EGF)-induced full activation of Akt by phosphorylation at Ser473/Thr308, resulting in inhibition of the mTORC2/Akt and Akt/mTORC1/p70S6K signaling pathways and activation of GSK3β by abrogation of Akt-mediated GSK3β phosphorylation at Ser9. The activated GSK3β inhibited cell proliferation by c-Jun phosphorylation at Ser243, which facilitated destabilization and degradation of c-Jun through the ubiquitination-mediated proteasomal degradation pathway. Notably, aschantin treatment decreased c-Jun stability through inhibition of the mTORC2-Akt signaling pathway, which suppressed EGF-induced anchorage-independent cell transformation in non-malignant JB6 Cl41 and HaCaT cells and colony growth of LNCaP and MIAPaCa-2 cancer cells in soft agar. Altogether, the results show that aschantin targets mTOR kinase and destabilizes c-Jun, which implicate aschantin as a potential chemopreventive or therapeutic agent.

Clair DK. Nuclear interaction between ADR-induced p65 and p53 mediates cardiac injury in iNOS (-/-) mice

Adriamycin (ADR) treatment causes an imbalance in the levels of nitric oxide (^•NO) and superoxide (O₂^•−) production leading to cardiac injury. Previously we demonstrated that mice lacking inducible nitric oxide synthase (iNOS) have increased oxidative stress and mitochondrial injury. The molecular events leading to increased mitochondrial injury in iNOS deficient mice is unknown. ADR in the absence of iNOS preferentially activates a proapoptotic pathway without a concurrent increase in prosurvival pathways. Treatment with ADR leads to an increase in DNA binding activity of nuclear factor kappa B (NFκB) and p53 in wildtype mice. Following ADR treatment, p53, but not NFκB DNA binding activity, as well as the level of Bax, a p53 target gene, was increased in iNOS (−/−) mice. This apoptotic signaling effect in iNOS (−/−) is alleviated by overexpression of manganese superoxide dismutase (MnSOD). Increases in NFκB and p53 in ADR-treated wildtype mice did not lead to increases in target genes such as MnSOD, bcl-xL, or Bax. Moreover, co-immunoprecipitation analysis revealed that p65, a prominent member of the NFκB family, interacts with p53 in the nucleus. These results suggest that NFκB and p53 may counter act one another's actions in ADR-treated wildtype (WT) mice. Further, these results identify a novel mechanism by which oxidative stress may regulate transcription of proapoptotic genes.

Adiponectin inhibits oxidative/nitrative stress during myocardial ischemia and reperfusion via PKA signaling

The cardioprotective effects of adiponectin (APN) against myocardial ischemia/reperfusion (MI/R) injury are well known. However, comprehension of the mechanisms mediating intracellular APN signaling remains incomplete. We recently demonstrate the antioxidant/antinitrative effects of APN are not dependent on AMPK. Protein kinase A (PKA) has been previously shown to be activated by APN, with uncertain relevance to APN cardiac protection. The current study determined whether the antioxidative/antinitrative effect of APN is mediated by PKA. Administration of APN (2 μg/g) 10 min before reperfusion significantly enhanced cardiac PKA activity, reduced oxidative stress, and decreased infarct size. Knockdown of cardiac PKA expression (PKA-KD) by intramyocardial injection of PKA-siRNAs (>70% suppression) significantly inhibited APN cardioprotection determined by cardiac apoptosis, infarct size, and cardiac function. Moreover, PKA-KD virtually abolished the suppressive effect of APN on MI/R-induced NADPH oxidase overexpression and superoxide overproduction and partially inhibited the effect of APN on nitrative protein modification in MI/R heart. Mechanistically, APN significantly inhibited MI/R-induced IKK/IκB phosphorylation and NF-κB activation, which were blocked in PKA-KD heart. Finally, the PKA-mediated antioxidant/antinitrative and cardioprotective effects of APN are intact in AMPK-deficient mice, suggesting that there is no cross talk between AMPK and PKA signaling in APN cardioprotection. Collectively, we demonstrate for the first time that APN inhibits oxidative/nitrative stress during MI/R via PKA-dependent NF-κB inhibition.

Effect of S-methylisothiourea in acetaminophen-induced hepatotoxicity in rat

Nitric oxide synthesized from inducible nitric oxide synthase (iNOS) plays role in acetaminophen (APAP)-induced liver damage. The present study was undertaken to evaluate the effect of iNOS inhibitor S-methylisothiourea (SMT) in APAP-induced hepatotoxicity in rats (1 g/kg, i.p.). SMT was (10, 30, and 100 mg/kg; i.p.) given 30 min before and 3 h after APAP administration. At 6 and 24 h, blood was collected to measure alanine transaminase (ALT), aspartate transaminase (AST), and nitrate plus nitrite (NOx) levels in serum. At 48 h, animals were sacrificed, and blood and liver tissues were collected for biochemical estimation. SMT reduced significantly the serum ALT, AST, and NOx levels at 24 and 48 h and liver NOx levels at 48 h as compared with APAP-treated control. The amount of peroxynitrite measured by rhodamine assay was significantly reduced by SMT, as compared with APAP-treated control group. SMT treatment (30 mg/kg) has significantly reduced the lipid peroxidation and protein carbonyl levels, increased SOD and catalase, and reduced glutathione and total thiol levels significantly as compared with APAP-treated control. SMT 30 mg/kg dose has protected animals from APAP-induced hypotension and reduced iNOS gene expression. Hepatocytes were isolated from animals, and effect of SMT on apoptosis, MTP, and ROS generation was studied, and their increased value in APAP intoxicated group was found to be significantly decreased by SMT (30 mg/kg) at 24 and 48 h. In conclusion, nitric oxide produced from iNOS plays important role in toxicity at late hours (24 to 48 h), and SMT inhibits iNOS and reduces oxidative and nitrosative stress.

Role of inducible nitric oxide synthase in mitochondrial depolarization and graft injury after transplantation of fatty livers

This study investigated the role of inducible nitric oxide synthase (iNOS) in failure of ethanol-induced fatty liver grafts. Rat livers were explanted 20 h after gavaging with ethanol (5 g/kg) and storing in UW solution for 24h before implantation. Hepatic oil red O staining-positive areas increased from ∼2 to ∼33% after ethanol treatment, indicating steatosis. iNOS expression increased ∼8-fold after transplantation of lean grafts (LG) and 25-fold in fatty grafts (FG). Alanine aminotransferase release, total bilirubin, hepatic necrosis, TUNEL-positive cells, and cleaved caspase-3 were higher in FG than LG. A specific iNOS inhibitor 1400W (5 μM in the cold-storage solution) blunted these alterations by >42% and increased survival of fatty grafts from 25 to 88%. Serum nitrite/nitrate and hepatic nitrotyrosine adducts increased to a greater extent after transplantation of FG than LG, indicating reactive nitrogen species (RNS) overproduction. Phospho-c-Jun and phospho-c-Jun N-terminal kinase-1/2 (JNK1/2) were higher in FG than in LG, indicating more JNK activation in fatty grafts. RNS formation and JNK activation were blunted by 1400W. Mitochondrial polarization and cell death were visualized by intravital multiphoton microscopy of rhodamine 123 and propidium iodide, respectively. After implantation, viable cells with depolarized mitochondria were 3-fold higher in FG than in LG and 1400W decreased mitochondrial depolarization in FG to the levels of LG. Taken together, iNOS is upregulated after transplantation of FG, leading to excessive RNS formation, JNK activation, mitochondrial dysfunction, and severe graft injury. The iNOS inhibitor 1400W could be an effective therapy for primary nonfunction of fatty liver grafts.

Upregulation of β-1,4-galactosyltransferase I in rat spinal cord with experimental autoimmune encephalomyelitis

Inflammatory infiltration has been recently emphasized in the demyelinating diseases of the central nervous system including multiple sclerosis. β-1,4-Galactosyltransferase I (β-1,4-GalT-I) is a major galactosyltransferase responsible for selectin-ligand biosynthesis, mediating rolling of the inflammatory lymphocytes. In the present study, Western blot showed that expression of β-1,4-GalT-I was low in normal or complete Freund's adjuvant (CFA) control rats' spinal cords, and it began to increase since early stage and peaked at E4 stage of experimental autoimmune encephalomyelitis (EAE) and restored approximately at normal level in the recovery stage. Immunohistochemisty revealed that upregulation of β-1,4-GalT-I was predominantly distributed in the white matter of spinal cord , while there was also some increased staining of β-1,4-GalT-I in the grey matter. Meanwhile, the expression of E-selectin, the substrate of β-1,4-GalT-I, was significantly increased, with a peak at E4 stage of EAE, and gradually decreased thereafter. Lectin blot showed that the protein bands with molecular weights of 65-25 kDa reacted a remarkable increase at the peak stage of EAE when compared with the normal and CFA control. Ricinus Communis Agglutinin-I (RCA-I) histochemistry revealed that RCA-Ι-positive signals were most intense in white matter of lumbosacral spinal cord at the peak stage of EAE (E4). Immunohistochemistry showed that β-1,4-GalT-I and CD62E, a marker for E-selectin stainings located in a considerable number of ED1 (+) macrophages in perivascular or in the white matter in EAE lesions, and a good co-localization of ED1 (+) cells with CD62E was observed. All these results suggest that β-1,4-GalT-I might serve as an inflammatory mediator regulating adhesion and migration of inflammatory cells in EAE, possibly through influencing the modification of galactosylated carbohydrate chains to modulate selectin-ligand biosynthesis and interaction with E-selectin.

l-Tetrahydropalmatine, an active component of Corydalis yanhusuo W.T. Wang, protects against myocardial ischaemia-reperfusion injury in rats

l-Tetrahydropalmatine (l-THP) is an active ingredients of Corydalis yanhusuo W.T. Wang, which protects against acute global cerebral ischaemia-reperfusion injury. In this study, we show that l-THP is cardioprotective in myocardial ischaemia-reperfusion injury and examined the mechanism. Rats were treated with l-THP (0, 10, 20, 40 mg/kg b.w.) for 20 min before occlusion of the left anterior descending coronary artery and subjected to myocardial ischaemia-reperfusion (30 min/6 h). Compared with vehicle-treated animals, the infarct area/risk area (IA/RA) of l-THP (20, 40 mg/kg b.w.) treated rats was reduced, whilst l-THP (10 mg/kg b.w.) had no significant effect. Cardiac function was improved in l-THP-treated rats whilst plasma creatine kinase activity declined. Following treatment with l-THP (20 mg/kg b.w.), subunit of phosphatidylinositol 3-kinase p85, serine⁴⁷³ phosphorylation of Akt and serine¹¹⁷⁷ phosphorylation of endothelial NO synthase (eNOS) increased in myocardium, whilst expression of inducible NO synthase (iNOS) decreased. However, the expression of HIF-1α and VEGF were increased in I_{30 min}R_{6 h}, but decreased to normal level in I_{30 min}R_{24 h}, while treatment with l-THP (20 mg/kg b.w.) enhanced the levels of these two genes in I_{30 min}R_{24 h}. Production of NO in myocardium and plasma, activity of myeloperoxidase (MPO) in plasma and the expression of tumour necrosis factor-α (TNF-α) in myocardium were decreased by l-THP. TUNEL assay revealed that l-THP (20 mg/kg b.w.) reduced apoptosis in myocardium. Thus, we show that l-THP activates the PI3K/Akt/eNOS/NO pathway and increases expression of HIF-1α and VEGF, whilst depressing iNOS-derived NO production in myocardium. This effect may decrease the accumulation of inflammatory factors, including TNF-α and MPO, and lessen the extent of apoptosis, therefore contributing to the cardioprotective effects of l-THP in myocardial ischaemia-reperfusion injury.

The protective effect of cilostazol on isolated rabbit femoral arteries under conditions of ischemia and reperfusion: the role of the nitric oxide pathway

OBJECTIVES

The clinical significance of ischemia/reperfusion of the lower extremities demands further investigation to enable the development of more effective therapeutic alternatives. This study investigated the changes in the vascular reactivity of the rabbit femoral artery and nitric oxide metabolites under partial ischemia/ reperfusion conditions following cilostazol administration.

METHODS

Ischemia was induced using infrarenal aortic clamping. The animals were randomly divided into seven groups: Control 90 minutes, Ischemia/Reperfusion 90/60 minutes, Control 120 minutes, Ischemia/Reperfusion 120/90 minutes, Cilostazol, Cilostazol before Ischemia/Reperfusion 120/90 minutes, and Ischemia 120 minutes/Cilostazol/ Reperfusion 90 minutes. Dose-response curves for sodium nitroprusside, acetylcholine, and the calcium ionophore A23187 were obtained in isolated femoral arteries. The levels of nitrites and nitrates in the plasma and skeletal muscle were determined using chemiluminescence.

RESULTS

Acetylcholine-and A23187-induced relaxation was reduced in the Ischemia/Reperfusion 120/90 group, and treatment with cilostazol partially prevented this ischemia/reperfusion-induced endothelium impairment. Only cilostazol treatment increased plasma levels of nitrites and nitrates. An elevation in the levels of nitrites and nitrates was observed in muscle tissues in the Ischemia/Reperfusion 120/90, Cilostazol/Ischemia/Reperfusion, and Ischemia/ Cilostazol/Reperfusion groups.

CONCLUSION

Hind limb ischemia/reperfusion yielded an impaired endothelium-dependent relaxation of the femoral artery. Furthermore, cilostazol administration prior to ischemia exerted a protective effect on endothelium-dependent vascular reactivity under ischemia/reperfusion conditions.

The potent activity of sulfated polysaccharide, ascophyllan, isolated from Ascophyllum nodosum to induce nitric oxide and cytokine production from mouse macrophage RAW264.7 cells: Comparison between ascophyllan and fucoidan

Ascophyllan isolated from the brown alga Ascophyllum nodosum is a fucose-containing sulfated polysaccharide, which has similar but distinct characteristic monosaccharide composition and entire chemical structure to fucoidan. In this study, we examined the effects of ascophyllan, fucoidan isolated from A. nodosum (A-fucoidan), and fucoidan from Sigma (S-fucoidan) as a representative fucoidan derived from other source (Fucus vesiculosus) on mouse macrophage cell line RAW264.7 cells. No significant cytotoxic effects of ascophyllan and A-fucoidan on RAW264.7 cells were observed up to 1000μg/ml, while S-fucoidan showed cytotoxic effect in a concentration-dependent manner. Ascophyllan induced extremely higher level of nitric oxide (NO) production from RAW264.7 cells than those induced by fucoidans over the concentration range tested (0-200μg/ml). Reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis revealed that expression level of inducible NO synthase (iNOS) in ascophyllan-treated RAW264.7 cells was much higher than the levels detected in the cells treated with fucoidans. Furthermore, the activities of ascophyllan to induce the secretion of tumor necrosis factor-α (TNF-α) and granulocyte colony-stimulating factor (G-CSF) from RAW264.7 cells were also greater than those induced by fucoidans especially at lower concentration range (3.1-50μg/ml). The activities of ascophyllan to induce NO and cytokine production in mouse peritoneal macrophages were also stronger than those of fucoidans. Electrophoretic mobility shift assay (EMSA) using infrared dye labeled nuclear factor-kappa B (NF-κB) and AP-1 consensus sequences suggested that ascophyllan can strongly activate these transcription factors. Marked increase in the nuclear translocation of p65, and the phosphorylation and degradation of IκB-α were also observed in ascophyllan-treated RAW264.7 cells. Analysis using mitogen-activated protein (MAP) kinase inhibitors and western blot analysis suggested that c-Jun N-terminal kinase (JNK) and p38 MAP kinase are mainly involved in ascophyllan-induced NO production.

C-peptide, a novel inhibitor of lung inflammation following hemorrhagic shock

C-peptide is a 31-amino acid peptide cleaved from proinsulin during insulin synthesis. Initially thought to be inert, C-peptide may modulate the inflammatory response in the setting of endotoxemia and ischemia reperfusion. However, the spectrum of its biological effects is unclear. We hypothesized that exogenous administration of C-peptide would modulate pro- and anti-inflammatory signaling pathways and thereby attenuate lung inflammation in an in vivo model of hemorrhagic shock. Hemorrhagic shock was induced in male Wistar rats (aged 3-4 mo) by withdrawing blood to a mean arterial pressure of 50 mmHg. At 3 h after hemorrhage, rats were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, animals received C-peptide (280 nmol/kg) or vehicle parenterally. Animals were euthanized at 1 and 3 h after resuscitation. C-peptide administration at resuscitation following hemorrhagic shock ameliorated hypotension and blunted the systemic inflammatory response by reducing plasma levels of IL-1, IL-6, macrophage inflammatory protein-1α, and cytokine-induced neutrophil chemoattractant-1. This was associated with a reduction in lung neutrophil infiltration and plasma levels of receptor for advanced glycation end products. Mechanistically, C-peptide treatment was associated with reduced expression of proinflammatory transcription factors activator protein-1 and NF-κB and activation of the anti-inflammatory transcription factor peroxisome proliferator-activated receptor-γ. Our data suggest that C-peptide ameliorates the inflammatory response and lung inflammation following hemorrhagic shock. These effects may be modulated by altering the balance between pro- and anti-inflammatory signaling in the lung.

Comparative study on modeccin- and phytohemagglutinin (PHA)-induced secretion of cytokines and nitric oxide (NO) in RAW264.7 cells

The effects of cytotoxic lectins, modeccin and phytohemagglutinin (PHA) on mouse macrophage cell line RAW264.7 was studied by detecting the induction of inflammatory mediators. Results showed that modeccin induced the release of tumor necrosis factor-α (TNF-α) from RAW264.7 cells with a bell-shape concentration-dependent profile. PHA that showed no significant cytotoxicity on RAW264.7 cells up to 100,000 ng/ml induced much higher level of TNF-α than modeccin. PHA simultaneously induced the secretion of granulocyte colony stimulation factor (G-CSF) from RAW264.7 cells with even much higher level than that of TNF-α, whereas modeccin did not. Furthermore, PHA induced the secretion of nitric oxide (NO) in RAW264.7 cells, while no significant level of NO was detected in the modeccin-treated cells. NH₄Cl (a lysomotoropic agent) and cycloheximide (a ribosome inhibitor) strongly inhibited modeccin-induced TNF-α secretion, but no significant inhibitory effects of these reagents on the PHA-induced TNF-α secretion were observed. Contrary to modeccin-induced TNF-α secretion, even slightly increased TNF-α secretion was observed in PHA-treated cells in the presence of 10 mM NH₄Cl. In addition, the inhibition profiles of modeccin-induced TNF-α secretion by various kinase inhibitors were different from those of PHA. These results suggested that the action mode of modeccin to stimulate RAW264.7 cells leading to the secretion of inflammatory molecules, including TNF-α, is distinct from that of PHA. On the other hand, significantly increased translocation of activator protein-1 (AP-1), a crucial transcription factor involved in expression of inflammatory molecules, into nucleus was observed in RAW264.7 cells treated with PHA and modeccin.

Inhibition of inducible nitric oxide synthase prevents graft injury after transplantation of livers from rats after cardiac death

This study investigated the roles of inducible nitric oxide synthase (iNOS) in the failure of rat liver grafts from cardiac death donors (GCDD). Livers were explanted after 30-minute aorta clamping and implanted after 4-hour storage in University of Wisconsin solution. The iNOS expression increased slightly in grafts from non-cardiac death donors (GNCDD) but markedly in GCDD. Serum nitrite and nitrate and hepatic 3-nitrotyrosine adducts, indicators of NO and peroxynitrite production, respectively, were substantially higher after transplantation of GCDD than GNCDD. Production of reactive nitrogen species (RNS) was largely blocked by 1400W (N-[1-naphthyl]ethylenediamine dihydrochloride; 5 μM), a specific iNOS inhibitor. Alanine aminotransferase release, bilirubin, necrosis, and apoptosis were 6.4-fold, 6.5-fold, 2.3-fold, and 2.7-fold higher, respectively, after transplantation of GCDD than GNCDD. The inhibitor 1400W effectively blocked these alterations and also increased survival of GCDD to 80% from 33%. Increased RNS production and failure of GCDD were associated with activation of c-Jun-N-terminal kinase (JNK), an effect that was blocked by inhibition of iNOS. Inhibition of JNK also improved the outcome after transplantation of GCDD. Together, the data indicate that iNOS increases substantially in GCDD, leading to RNS overproduction, JNK activation, and more severe graft injury. Inhibitors of iNOS are suggested as effective therapies to improve the outcome after transplantation of GCDD.

Ethyl pyruvate has anti-inflammatory and delayed myocardial protective effects after regional ischemia/reperfusion injury

PURPOSE

Ethyl pyruvate has anti-inflammatory properties and protects organs from ischemia/reperfusion (I/R)-induced tissue injury. The aim of this study was to determine whether ethyl pyruvate decreases the inflammatory response after regional I/R injury and whether ethyl pyruvate protects against delayed regional I/R injury in an in vivo rat heart model after a 24 hours reperfusion.

MATERIALS AND METHODS

Rats were randomized to receive lactated Ringer's solution or ethyl pyruvate dissolved in Ringer's solution, which was given by intraperitoneal injection 1 hour prior to ischemia. Rats were subjected to 30 min of ischemia followed by reperfusion of the left coronary artery territory. After a 2 hours reperfusion, nuclear factor κB, myocardial myeloperoxidase activity, and inflammatory cytokine levels were determined. After the 24 hours reperfusion, the hemodynamic function and myocardial infarct size were evaluated.

RESULTS

At 2 hours after I/R injury, ethyl pyruvate attenuated I/R-induced nuclear factor κB translocation and reduced myeloperoxidase activity in myocardium. The plasma circulating levels of inflammatory cytokines decreased significantly in the ethyl pyruvate-treated group. At 24 hours after I/R injury, ethyl pyruvate significantly improved cardiac function and reduced infarct size after regional I/R injury.

CONCLUSION

Ethyl pyruvate has the ability to inhibit neutrophil activation, inflammatory cytokine release, and nuclear factor κB translocation. Ethyl pyruvate is associated with a delayed myocardial protective effect after regional I/R injury in an in vivo rat heart model.

Inducible nitric oxide synthase deficiency in myeloid cells does not prevent diet-induced insulin resistance

Recent findings denote an important contribution of macrophage inflammatory pathways in causing obesity-related insulin resistance. Inducible nitric oxide synthase (iNOS) is activated in proinflammatory macrophages and modestly elevated in insulin-responsive tissues. Although the benefits of systemic iNOS inhibition in insulin-resistant models have been demonstrated, the role of macrophage iNOS in metabolic disorders is not clear. In the current work, we used bone marrow transplantation (BMT) to generate mice with myeloid iNOS deficiency [iNOS BMT knockout (KO)]. Interestingly, disruption of iNOS in myeloid cells did not protect mice from high-fat diet-induced obesity and insulin resistance. When mice were treated with the iNOS inhibitor, N6-(1-Iminoethyl)-L-lysine hydrochloride (L-NIL), we observed a significant and comparable improvement of glucose homeostasis and insulin sensitivity in both wild-type and iNOS BMT KO mice. We further demonstrated that absence of iNOS in primary macrophages did not affect acute TLR4 signaling pathways and had only a modest and mixed effect on inflammatory gene expression. With respect to TNFalpha treatment, iNOS KO macrophages showed, if anything, a greater inflammatory response. In summary, we conclude that iNOS inhibition in tissues other than myeloid cells is responsible for the beneficial effects in obesity/insulin resistance.

Phospholipase D2 acts as an important regulator in LPS-induced nitric oxide synthesis in Raw 264.7 cells

The purpose of this study was to identify the role of phospholipase D2 (PLD2) in lipopolysaccharide (LPS)-induced nitric oxide (NO) synthesis. LPS enhanced NO synthesis and inducible nitric oxide synthase (iNOS) expression in macrophage cell line, Raw 264.7 cells. When Raw 264.7 cells were stimulated with LPS, the expressions of PLDs were increased. Thus, to investigate the role of PLD in NO synthesis, we transfected PLD1, PLD2, and their dominant negative forms to Raw 264.7 cells, respectively. Interestingly, only PLD2 overexpression, but not that of PLD1, increased NO synthesis and iNOS expression. Moreover, LPS-induced NO synthesis and iNOS expression were blocked by PLD2 siRNA, suggesting that LPS upregulates NO synthesis through PLD2. Next, we investigated the S6K1-p42/44 MAPK-STAT3 signaling pathway in LPS-induced NO synthesis mechanism. Knockdown of PLD2 with siRNA also decreased phosphorylation of S6K1, p42/44 MAPK and STAT3 induced by LPS. Furthermore, we found that STAT3 bound with the iNOS promoter, and their binding was mediated by PLD2. Taken together, our results demonstrate the importance of PLD2 for LPS-induced NO synthesis in Raw 264.7 cells with involvement of the S6K1-p42/44 MAPK-STAT3 pathway.

c-Jun DNAzymes Inhibit Myocardial Inflammation, ROS Generation, Infarct Size, and Improve Cardiac Function After Ischemia-Reperfusion Injury

Objectives— Coronary reperfusion has been the mainstay therapy for reduced infarct size after a heart attack. However, this intervention also results in myocardial injury by initiating a marked inflammatory reaction, and new treatments are keenly sought.

Methods and Results— The basic-region leucine zipper protein, c-Jun is poorly expressed in the normal myocardium and is induced within 24 hours after myocardial ischemia-reperfusion injury. Synthetic catalytic DNA molecules (DNAzymes) targeting c-Jun (Dz13) reduce infarct size in the area-at-risk (AAR) regardless of whether it is delivered intramyocardially at the initiation of ischemia or at the time of reperfusion. Dz13 attenuates neutrophil infiltration, c-Jun and ICAM-1 expression in vascular endothelium, cardiomyocyte apoptosis, and the generation of reactive oxygen species in the reperfused myocardium. It inhibits infiltration into the AAR of complement 3 (C3), C3a receptor (C3aR), membrane attack complex-1 (Mac-1), or matrix metalloproteinase-2 (MMP-2) positive inflammatory cells. Dz13 also improves cardiac function without influencing myocardial vascularity or fibrosis.

Conclusion— These findings demonstrate the regulatory role of c-Jun in the pathogenesis of myocardial inflammation and infarction following ischemia-reperfusion injury, and inhibition of this process using catalytic DNA.

Selectin Inhibition Modulates NF-κ B and AP-1 Signaling After Liver Ischemia/Reperfusion

The infiltration of neutrophils after ischemia and reperfusion (I/R) is facilitated by the expression of adhesion molecules on the surface of both leukocytes and endothelial cells. Adhesion molecules of the selectin family are of particular importance at the onset of neutrophil mediated injury, as demonstrated by the occurrence of many cellular interactions with the final extravasation of inflammatory leukocytes at the site of I/R damage. Previous studies demonstrated a prevention of neutrophil extravasation and protection of ischemic damage when a small anti-selectin molecule was used. In this study, we tested a new small anti-selectin compound (OC-229) in a murine model of partial hepatic I/R. The aim of this study was to determine the effect of OC-229 on liver function and histology after I/R and to evaluate its role in the modulation of the inflammatory molecular signaling pathways of NF-kappa B and AP-1 under the same experimental condition. Mice subjected to 90 min of partial (70-80%) hepatic ischemia and 3 h of reperfusion were divided into three groups (n = 9/group): sham, ischemic control, and treated group, which received 25 mg/kg of the anti-selectin small molecule OC-229. These groups were studied when the treatment was given at the time of reperfusion (no pretreatment was given). The parameters measured at 3 h of reperfusion included liver function tests (ALT and AST), liver histology, and liver tissue electrophoretic mobility shift assay (EMSA) for NF-kappa B and AP-1. It was demonstrated that the multiselectin inhibitor OC-229 offered significant protection for the ischemic liver when given at 25 mg/kg at the time of reperfusion. ALT and AST serum levels significantly decreased when the ischemic control and the group receiving OC-229 were compared (p = .01). Treated animals demonstrated better histological findings as well. The EMSA showed dissociation of NF-kappa B and AP-1 activity in the liver nuclear extracts after selectin inhibition treatment. A reduction in the activity of AP-1 and an increment in NF-kappa B activation was seen. In this work, we obtained evidence that the small-molecule selectin inhibitor OC-229 offered functional and histological protection of the ischemic liver when given at 25 mg/kg at the time for reperfusion. There was dissociation in the activation signals of NF-kappa B and AP-1. Increase in NF-kappa B and reduction of the activation of AP-1 were noted at 3 h of reperfusion.

Deficiency of iNOS Does Not Prevent Isoproterenol-induced Cardiac Hypertrophy in Mice

We investigated whether deficiency of inducible nitric oxide synthase (iNOS) could prevent isoproterenol-induced cardiac hypertrophy in iNOS knockout (KO) mice. Isoproterenol was continuously infused subcutaneously (15 mg/kg/day) using an osmotic minipump. Isoproterenol reduced body weight and fat mass in both iNOS KO and wild-type mice compared with saline-infused wild-type mice. Isoproterenol increased the heart weight in both iNOS KO and wild-type mice but there was no difference between iNOS KO and wild-type mice. Posterior wall thickness of left ventricle showed the same tendency with heart weight. Protein level of iNOS in the left ventricle was increased in isoproterenol-infused wild-type mice. The gene expression of interleukin-6 (IL-6) and transforming growth factor-beta (TGF-beta) in isoproterenol-infused wild-type was measured at 2, 4, 24, and 48-hour and isoproterenol increased both IL-6 (2, 4, 24, and 48-hour) and TGF-beta (4 and 24-hour). Isoproterenol infusion for 7 days increased the mRNA level of IL-6 and TGF-beta in iNOS KO mice, whereas the gene expression in wild-type mice was not increased. Phosphorylated form of extracellular signal-regulated kinases (pERK) was also increased by isoproterenol at 2 and 4-hour but was not increased at 7 days after infusion in wild-type mice. However, the increased pERK level in iNOS KO mice was maintained even at 7 days after isoproterenol infusion. These results suggest that deficiency of iNOS does not prevent isoproterenol-induced cardiac hypertrophy and may have potentially harmful effects on cardiac hypertrophy.

Overexpression of Hsp20 prevents endotoxin-induced myocardial dysfunction and apoptosis via inhibition of NF-kappaB activation

The occurrence of cardiovascular dysfunction in sepsis is associated with a significantly increased mortality rate of 70% to 90% compared with 20% in septic patients without cardiovascular impairment. Thus, rectification or blockade of myocardial depressant factors should partly ameliorate sepsis progression. Heat shock protein 20 (Hsp20) has been shown to enhance myocardial contractile function and protect against doxorubicin-induced cardiotoxicity. To investigate the possible role of Hsp20 in sepsis-mediated cardiac injury, we first examined the expression profiles of five major Hsps in response to lipopolysaccharide (LPS) challenge, and observed that only the expression of Hsp20 was downregulated in LPS-treated myocardium, suggesting that this decrease might be one of the mechanisms contributing to LPS-induced cardiovascular defects. Further studies using loss-of-function and gain-of-function approaches in adult rat cardiomyocytes verified that reduced Hsp20 levels were indeed correlated with the impaired contractile function. In fact, overexpression of Hsp20 significantly enhanced cardiomyocyte contractility upon LPS treatment. Moreover, after administration of LPS (25 microg/g) in vivo, Hsp20 transgenic mice (10-fold overexpression) displayed: 1) an improvement in myocardial function; 2) reduced the degree of cardiac apoptosis; and 3) decreased NF-kappaB activity, accompanied with reduced myocardial cytokines IL-1beta and TNF-alpha production, compared to the LPS-treated non-transgenic littermate controls. Thus, the increases in Hsp20 levels can protect against LPS-induced cardiac apoptosis and dysfunction, associated with inhibition of NF-kappaB activity, suggesting that Hsp20 may be a new therapeutic agent for the treatment of sepsis.

Nitric oxide mechanisms of nebivolol

β-blockers are among the most widely used drugs in the prevention and treatment of cardiovascular disease, although they are associated with increased peripheral resistance. Third-generation β-blockers avoid this adverse effect by inducing vasodilation through different mechanisms. In particular, nebivolol, a highly selective blocker of β1-adrenergic receptors, is the only β-blocker known to induce vascular production of nitric oxide, the main endothelial vasodilator. The specific mechanism of nebivolol is particularly relevant in hypertension, where nitric oxide dysfunction occurs. Indeed, nebivolol is able to reverse endothelial dysfunction. Nebivolol induces nitric oxide production via activation of β3-adrenergic receptors, which can explain the good metabolic profile observed after treatment with this drug. Moreover, nebivolol can also stimulate the β3-adrenergic receptor-mediated production of nitric oxide in the heart, and this stimulation can result in a greater protection against heart failure. In conclusion, nebivolol has a unique profile among antihypertensive drugs, adding to a very high selectivity against β1 adrenergic receptors, and an agonist action on β3 receptors and nitric oxide (NO), which has led to clinically significant improvements in hypertensive patients.

Effect of atorvastatin on expression of IL-10 and TNF-alpha mRNA in myocardial ischemia-reperfusion injury in rats

Myocardial ischemia and reperfusion (MI/R) is associated with an intense inflammatory reaction, which may lead to myocyte injury. Because statins protect the myocardium against ischemia-reperfusion injury via a mechanism unrelated to cholesterol lowering, we hypothesized that the protective effect of statins was related to the expression of TNF-alpha (TNF-alpha) and interleukin-10 (IL-10) mRNA. Seventy-two rats were randomly divided into three groups as follows: sham, I/R and I/R+atorvastatin. Atorvastatin (20 mg kg(-1)day(-1)) treatment was administered daily via oral gavage to rats for 2, 7 or 14 days. Ischemia was induced via a 30-min coronary occlusion. Reperfusion was allowed until 2, 7 or 14 days while atorvastatin treatment continued. We measured infarct size, hemodynamics and the plasma levels and the mRNA expression of TNF-alpha and IL-10 in the three groups. We demonstrated that the up-regulation of expression of both TNF-alpha mRNA and IL-10 mRNA was associated the increased plasma levels of TNF-alpha and IL-10 in the ischemic and reperfused myocardium compared with that in the sham group (P<0.01). Atorvastatin treatment prevented ischemia-reperfusion-induced up-regulation of both TNF-alpha and IL-10 mRNA, and improved left ventricular function (P<0.01). Our findings suggested that atorvastatin may attenuate MI/R and better recovery of left ventricle function following ischemia and reperfusion and IL-10 was not directly likely involved in this protective mechanism.

Interaction of major genes predisposing to hepatocellular carcinoma with genes encoding signal transduction pathways influences tumor phenotype and prognosis

Studies on rodents and humans demonstrate an inherited predisposition to hepatocellular carcinoma (HCC). Analysis of the molecular alterations involved in the acquisition of a phenotype resistant or susceptible to hepatocarcinogenesis showed a deregulation of G1 and S phases in HCC of genetically susceptible F344 rats and a G1-S block in lesions of resistant Brown norway (BN) rats. Unrestrained extracellular signal-regulated kinase (ERK) activity linked to proteasomal degradation of dual-specificity phosphatase 1 (DUSP1), a specific ERK inhibitor, by the CKS1-SKP2 ubiquitin ligase complex occurs in more aggressive HCC of F344 rats and humans. This mechanism is less active in HCC of BN rats and human HCC with better prognosis. Upregulation of iNos cross-talk with IKK/NF-κB and RAS/ERK pathways occurs in rodent liver lesions at higher levels in the most aggressive models represented by HCC of F344 rats and c-Myc-TGF-α transgenic mice. iNOS, IKK/NF-κB, and RAS/ERK upregulation is highest in human HCC with a poorer prognosis and positively correlates with tumor proliferation, genomic instability and microvascularization, and negatively with apoptosis. Thus, cell cycle regulation and the activity of signal transduction pathways seem to be modulated by HCC modifier genes, and differences in their efficiency influence the susceptibility to hepatocarcinogenesis and probably the prognosis of human HCC.

Ciglitazone ameliorates lung inflammation by modulating the inhibitor kappaB protein kinase/nuclear factor-kappaB pathway after hemorrhagic shock

OBJECTIVE

Peroxisome proliferator-activated receptor-gamma is a ligand-activated transcription factor. Ciglitazone, a peroxisome proliferator-activated receptor-gamma ligand, has been shown to provide beneficial effects in experimental models of sepsis and ischemia/reperfusion injury. We investigated the effects of ciglitazone on lung inflammation after severe hemorrhage.

DESIGN

Prospective, laboratory study, rodent model of hemorrhagic shock.

SETTING

University hospital laboratory.

SUBJECTS

Male rats.

INTERVENTIONS

Hemorrhagic shock was induced by withdrawing blood to a mean arterial pressure of 50 mm Hg. At 3 hrs after hemorrhage, rats were rapidly resuscitated by returning their shed blood. At the time of resuscitation and every hour thereafter, animals received ciglitazone (10 mg/kg) or vehicle intraperitoneally. Heart rate and mean arterial pressure were measured throughout the experiment. Plasma and lung tissue were collected for analysis up to 3 hrs after resuscitation.

MEASUREMENTS AND MAIN RESULTS

Ciglitazone treatment ameliorated mean arterial pressure, reduced lung injury, significantly blunted lung neutrophil infiltration, and lowered plasma interleukin-6, interleukin-10, and monocyte chemoattractant protein-1 levels. In a time course analysis, vehicle-treated rats had a significant increase in nuclear factor-kappaB DNA binding, which was preceded by increased inhibitor kappaB protein kinase activity and inhibitor kappaB alpha degradation in the lung. Treatment with ciglitazone significantly reduced inhibitor kappaB protein kinase activity and inhibitor kappaB alpha degradation and completely inhibited nuclear factor-kappaB DNA binding. This reduction of inhibitor kappaB protein kinase activity afforded by ciglitazone appeared to be a consequence of a physical interaction between peroxisome proliferator-activated receptor-gamma and increased inhibitor kappaB protein kinase.

CONCLUSION

Ciglitazone ameliorates the inflammatory response and may reduce lung injury after hemorrhagic shock. These protective effects appear to be mediated through inhibition of the inhibitor kappaB protein kinase/nuclear factor-kappaB pathway.

Lysophosphatidic acid inhibits bacterial endotoxin-induced pro-inflammatory response: potential anti-inflammatory signaling pathways

Previous studies have demonstrated that heterotrimeric guanine nucleotide-binding regulatory (Gi) protein-deficient mice exhibit augmented inflammatory responses to lipopolysaccharide (LPS). These findings suggest that Gi protein agonists will suppress LPS-induced inflammatory gene expression. Lysophosphatidic acid (LPA) activates G protein-coupled receptors leading to Gi protein activation. We hypothesized that LPA will inhibit LPS-induced inflammatory responses through activation of Gi-coupled anti-inflammatory signaling pathways. We examined the anti-inflammatory effect of LPA on LPS responses both in vivo and in vitro in CD-1 mice. The mice were injected intravenously with LPA (10 mg/kg) followed by intraperitoneal injection of LPS (75 mg/kg for survival and 25 mg/kg for other studies). LPA significantly increased the mice survival to endotoxemia (P < 0.05). LPA injection reduced LPS-induced plasma TNF-alpha production (69 +/- 6%, P < 0.05) and myeloperoxidase (MPO) activity in lung (33 +/- 9%, P < 0.05) as compared to vehicle injection. LPS-induced plasma IL-6 was unchanged by LPA. In vitro studies with peritoneal macrophages paralleled results from in vivo studies. LPA (1 and 10 microM) significantly inhibited LPS-induced TNFalpha production (61 +/- 9% and 72 +/- 9%, respectively, P < 0.05) but not IL-6. We further demonstrated that the anti-inflammatory effect of LPA was reversed by ERK 1/2 and phosphatase inhibitors, suggesting that ERK 1/2 pathway and serine/threonine phosphatases are involved. Inhibition of phosphatidylinositol 3 (PI3) kinase signaling pathways also partially reversed the LPA anti-inflammatory response. However, LPA did not alter NFkappaB and peroxisome proliferator-activated receptor gamma (PPARgamma) activation. Inhibitors of PPARgamma did not alter LPA-induced inhibition of LPS signaling. These studies demonstrate that LPA has significant anti-inflammatory activities involving activation of ERK 1/2, serine/threonine phosphatases, and PI3 kinase signaling pathways.

Nitric oxide-releasing compounds inhibit the production of interleukin-2, -4 and -10 in activated human lymphocytes

In the present study, we investigated the effects of nitric oxide donors, GEA 3162 (1,2,3,4-oxatriazolium,5-amino-3(3,4-dichlorophenyl)-chloride), GEA 3175 (1,2,3,4-oxatriazolium,3-(3-chloro-2-methylphenyl)-5-[[(4-methylphenyl) sulfonyl]amino]-, hydroxide inner salt) and S-nitroso-N-acetylpenicillamine (SNAP), on the production of Th1 [interleukin (IL)-2] and Th2 (IL-4 and IL-10) type cytokines in activated human lymphocytes. Lymphocytes were stimulated with concanavalin A or a combination of thapsigargin and phorbol myristate acetate in the absence or in the presence of nitric oxide donors. Concanavalin A induced expression of IL-2 mRNA and production of IL-2, and the combination of thapsigargin and phorbol myristate acetate induced expression of IL-4 and IL-10 mRNAs and production of IL-4 and IL-10. These effects were inhibited by the nitric oxide donors in a dose-dependent manner, GEA 3162 and GEA 3175 being more potent than SNAP on a molar basis. The results show that nitric oxide donors have immunomodulatory properties in both Th1- and Th2-derived responses.

Hypochlorite-oxidized low density lipoproteins reduce production and bioavailability of nitric oxide in RAW 264.7 macrophages by distinct mechanisms

Oxidative modification of low density lipoproteins is thought to play a pivotal role in the development and exacerbation of atherosclerosis and atherogenesis, and is believed to be closely associated with alterations in the vascular production of nitric oxide (NO). Previous work has shown that several products emerging from lipid peroxidation (e.g. lipid hydroperoxides, lysophospholipids, oxidized cholesterol) are able to reduce NO production in macrophages. The naturally occurring oxidant hypochlorite has been shown to be responsible for the in vivo formation of hypochlorite-oxidized LDL and such OxLDL are known to lack lipid peroxidation products. In this work we demonstrate that hypochlorite-oxidized LDL mediate profound effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages. By means of the membrane-permeable NO indicator 4,5-diaminofluorescein diacetate, we are able to show decreased levels of intracellular authentic nitric oxide following incubation with hypochlorite-oxidized LDL. The observed effects are dose-dependent and comparable to results obtained in the presence of the NOS inhibitor NG-monomethyl-L-arginine. This marked reduction of intracellular NO is accompanied by a dose-dependent inhibition of inducible nitric oxide synthase (iNOS) protein and mRNA expression. Furthermore, hyp-OxLDL lead to the generation of peroxynitrite, thereby also reducing bioavailability of NO. By mediating these effects on production and bioavailability of NO, hyp-OxLDL might also contribute to atherogenesis by reducing the antiatherogenic effects of nitric oxide.

In vitro antioxidant and anti-inflammatory activities of Jaceosidin from Artemisia princeps Pampanini cv. Sajabal

Oxidized low-density lipoprotein (oxLDL) plays a key role in the inflammatory processes of atherosclerosis. Jaceosidin isolated from the methanolic extracts of the aerial parts of Artemisia princeps Pampanini cv. Sajabal was tested for antioxidant and anti-inflammatory activities. Jaceosidin inhibited the Cu(2+)-mediated LDL oxidation with IC(50) values of 10.2 microM in the thiobarbituric acid-reactive substances (TBARS) assay as well as the macrophage-mediated LDL oxidation. The antioxidant activities of jaceosidin were exhibited in the conjugated diene production, relative electrophoretic mobility, and apoB-100 fragmentation on copper-mediated LDL oxidation. Jaceosidin also inhibited the generation of reactive oxygen species (ROS) concerning in regulation of NF-kappaB signaling. And jaceosidin inhibited nuclear factor-kappa B (NF-kappaB) activity, nitric oxide (NO) production, and suppressed expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.

Effect of 5-O-Methylhirsutanonol on nuclear factor-kappaB-dependent production of NO and expression of iNOS in lipopolysaccharide-induced RAW264.7 cells

Diarylheptanoids are known to have anti-inflammatory and anti-atherosclerotic activities in various cell types, including macrophages. 5- O-Methylhirsutanonol (5-MH) isolated from the leaves of Alnus japonica Steud exhibited the antioxidant activities on Cu (2+)- and AAPH-mediated low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substances (TBARS) assay as well as the macrophage-mediated LDL oxidation. In the main study, we examined anti-inflammatory activities of 5- O-methylhirsutanonol (5-MH) on nuclear factor kappaB (NF-kappaB)-dependent nitric oxide (NO) production and expression of inducible nitric oxide synthease (iNOS) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. 5-MH inhibited NO production with an IC 50 value of 14.5 microM and expression of both iNOS protein and iNOS mRNA in a parallel dose-response manner. Then, expression of inflammation-associated genes, such as TNF-alpha, COX-2, and IL-1beta, was suppressed by 5-MH, as determined by reverse transcriptase polymerase chain reaction analysis. Moreover, 5-MH attenuated NF-kappaB activation by inhibition of hyperphosphorylation of IkappaB-alpha and its subsequent proteolytic degradation and p65 nuclear translocation, as well as preventing DNA-binding ability. In addition, 5-MH suppressed the mRNA expression of the gene reactive oxygen species (ROS) concerned in the regulation of NF-kappaB signaling.

Caspase inhibition reduces cardiac myocyte dyshomeostasis and improves cardiac contractile function after major burn injury

In the heart, thermal injury activates a group of intracellular cysteine proteases known as caspases, which have been suggested to contribute to myocyte inflammation and dyshomeostasis. In this study, Sprague-Dawley rats were given either a third-degree burn over 40% total body surface area plus conventional fluid resuscitation or sham burn injury. Experimental groups included 1) sham burn given vehicle, 400 microl DMSO; 2) sham burn given Q-VD-OPh (6 mg/kg), a highly specific and stable caspase inhibitor, 24 and 1 h prior to sham burn; 3) burn given vehicle, DMSO as above; 4) burn given Q-VD-OPh (6 mg/kg) 24 and 1 h prior to burn. Twenty-four hours postburn, hearts were harvested and studied with regard to myocardial intracellular sodium concentration, intracellular pH, ATP, and phosphocreatine (23Na/31P nuclear magnetic resonance); myocardial caspase-1, -3,and -8 expression; myocyte Na+ (fluorescent indicator, sodium-binding benzofurzan isophthalate); myocyte secretion of TNF-alpha, IL-1beta, IL-6, and IL-10; and myocardial performance (Langendorff). Burn injury treated with vehicle alone produced increased myocardial expression of caspase-1, -3, and -8, myocyte Na+ loading, cytokine secretion, and myocardial contractile depression; cellular pH, ATP, and phosphocreatine were stable. Q-VD-OPh treatment in burned rats attenuated myocardial caspase expression, prevented burn-related myocardial Na+ loading, attenuated myocyte cytokine responses, and improved myocardial contraction and relaxation. The present data suggest that signaling through myocardial caspases plays a pivotal role in burn-related myocyte sodium dyshomeostasis and myocyte inflammation, perhaps contributing to burn-related contractile dysfunction.

Nitrosative stress and pathogenesis of insulin resistance

Insulin resistance is a major causative factor for type 2 diabetes and is associated with increased risk of cardiovascular disease. Despite intense investigation for a number of years, molecular mechanisms underlying insulin resistance remain to be determined. Recently, chronic inflammation has been highlighted as a culprit for obesity-induced insulin resistance. Nonetheless, upstream regulators and downstream effectors of chronic inflammation in insulin resistance remain unclarified. Inducible nitric oxide synthase (iNOS), a mediator of inflammation, has emerged as an important player in insulin resistance. Obesity is associated with increased iNOS expression in insulin-sensitive tissues in rodents and humans. Inhibition of iNOS ameliorates obesity-induced insulin resistance. However, molecular mechanisms by which iNOS mediates insulin resistance remain largely unknown. Protein S-nitrosylation, a covalent attachment of NO moiety to thiol sulfhydryls, has emerged as a major mediator of a broad array of NO actions. S-nitrosylation is elevated in patients with type 2 diabetes, and increased S-nitrosylation of insulin signaling molecules, including insulin receptor, insulin receptor substrate-1, and Akt/PKB, has been shown in skeletal muscle of obese, diabetic mice. Akt/PKB is reversibly inactivated by S-nitrosylation. Based on these findings, S-nitrosylation has recently been proposed to play an important role in the pathogenesis of insulin resistance.

Can hyperbaric oxygen be used as adjunctive heart failure therapy through the induction of endogenous heat shock proteins?

Heart failure (HF) is a chronic condition that is expected to increase in incidence along with increased life expectancy and an aging population. As the incidence of HF increases, the cost to national healthcare budgets is expected to run into the billions. The costs of lost productivity and increased social reliance on state support must also be considered. Recently, acute myocardial infarction (AMI) has come to be seen as the major contributing factor to HF. Although thrombolysis may restore coronary perfusion after an AMI, it may also introduce ischemic reperfusion injury (IRI). In an attempt to ameliorate sustained protein damage caused by IRI, endogenous chaperone proteins known as heat shock proteins (HSPs) are induced as a consequence of the stress of IRI. Recently, hyperbaric oxygen has been shown to induce the production of HSPs in noncardiac tissue, with a resultant protective effect. This current opinion review article suggests a possible role for hyperbaric oxygen, as a technologically modern drug, in augmenting the induction of endogenous HSPs to repair and improve the function of failing hearts that have been damaged by AMI and IRI. In addition, this simple, safe, noninvasive drug may prove useful in easing the economic burden of HF on already overextended health resources.

Endothelial nitric oxide synthase (NOS3) knockout decreases NOS2 induction, limiting hyperoxygenation and conferring protection in the postischemic heart

Although it has been shown that endothelial nitric oxide synthase (eNOS)-derived nitric oxide downregulates mitochondrial oxygen consumption during early reperfusion, its effects on inducible NOS (iNOS) induction and myocardial injury during late reperfusion are unknown. Wild-type (WT) and eNOS(-/-) mice were subjected to 30 min of coronary ligation followed by reperfusion. Expression of iNOS mRNA and protein levels and peroxynitrite production were lower in postischemic myocardium of eNOS(-/-) mice than levels in WT mice 48 h postreperfusion. Significantly improved hemodynamics (+/-dP/dt, left ventricular systolic pressure, mean arterial pressure), increased rate pressure product, and reduced myocardial infarct size (18 +/- 2.5% vs. 31 +/- 4.6%) were found 48 h after reperfusion in eNOS(-/-) mice compared with WT mice. Myocardial infarct size was also significantly decreased in WT mice treated with the specific iNOS inhibitor 1400W (20.5 +/- 3.4%) compared with WT mice treated with PBS (33.9 +/- 5.3%). A marked reperfusion-induced hyperoxygenation state was observed by electron paramagnetic resonance oximetry in postischemic myocardium, but Po(2) values were significantly lower from 1 to 72 h in eNOS(-/-) than in WT mice. Cytochrome c-oxidase activity and NADH dehydrogenase activity were significantly decreased in postischemic myocardium in WT and eNOS(-/-) mice compared with baseline control, respectively, and NADH dehydrogenase activity was significantly higher in eNOS(-/-) than in WT mice. Thus deficiency of eNOS exerted a sustained beneficial effect on postischemic myocardium 48 h after reperfusion with preserved mitochondrial function, which appears to be due to decreased iNOS induction and decreased iNOS-derived peroxynitrite in postischemic myocardium.

Activation of sensory neurons contributes to reduce spinal cord injury in rats

We previously demonstrated that activation of sensory neurons increases endothelial prostaglandin I(2) (PGI(2)) production by releasing calcitonin gene-related peptide (CGRP). Since PGI(2) reduces post-traumatic spinal cord injury (SCI) by inhibiting tumor necrosis factor (TNF) production, activation of sensory neurons in the spinal cord tissue may ameliorate spinal cord injury. This study examines these possibilities using rat models of compression trauma-induced SCI. Both SB366791, a specific vanilloid receptor antagonist, and CGRP (8-37), a CGRP receptor antagonist, significantly inhibited trauma-induced increases in spinal cord tissue 6-keto-PGF(1alpha) levels. SB366791, CGRP (8-37) and indomethacin (IM) enhanced increases in spinal cord tissue TNF levels at 2h after trauma and exacerbated motor disturbances. Administration of CGRP significantly reduced motor disturbances and inhibited increases in spinal cord tissue TNF levels through enhancement of increases in tissue levels of 6-keto-PGF(1alpha). These observations strongly suggest that activation of sensory neurons might ameliorate compression trauma-induced SCI, inhibiting TNF production through enhancement of endothelial PGI(2) production. Thus, although the spinal cord sensory neurons function as nociceptive neurons, they could also be critically involved in the cytoprotective system that attenuates SCI development and, thus, pharmacological stimulation of spinal cord sensory neurons might contribute to reduce spinal cord injury.

cGMP-dependent protein kinase type I inhibits TAB1-p38 mitogen-activated protein kinase apoptosis signaling in cardiac myocytes

Cardiac myocyte apoptosis during ischemia and reperfusion (I/R) is tightly controlled by a complex network of stress-responsive signaling pathways. One pro-apoptotic pathway involves the interaction of the scaffold protein TAB1 with p38 mitogen-activated protein kinase (p38 MAPK) leading to the autophosphorylation and activation of p38 MAPK. Conversely, NO and its second messenger cGMP protect cardiac myocytes from apoptosis during I/R. We provide evidence that the cGMP target cGMP-dependent protein kinase type I (PKG I) interferes with TAB1-p38 MAPK signaling to protect cardiac myocytes from I/R injury. In isolated neonatal cardiac myocytes, activation of PKG I inhibited the interaction of TAB1 with p38 MAPK, p38 MAPK phosphorylation, and apoptosis induced by simulated I/R. During I/R in vivo, mice with a cardiac myocyte-restricted deletion of PKG I displayed a more pronounced interaction of TAB1 with p38 MAPK and a stronger phosphorylation of p38 MAPK in the myocardial area at risk during reperfusion and more apoptotic cardiac myocytes in the infarct border zone as compared with wild-type littermates. Notably, adenoviral expression of a constitutively active PKG I mutant truncated at the N terminus(PKGI-DeltaN1-92) did not inhibit p38 MAPK phosphorylation and apoptosis induced by simulated I/R in vitro, indicating that the N terminus of PKG I is required. As shown by co-immunoprecipitation experiments in HEK293 cells, cGMP-activated PKG I, but not constitutively active PKG I-DeltaN1-92 or PKG I mutants carrying point mutations in the N-terminal leucine-isoleucine zipper, interacted with p38 MAPK, and prevented the binding of TAB1 to p38 MAPK. Together, our data identify a novel interaction between the cGMP target PKG I and the TAB1-p38 MAPK signaling pathway that serves as a defense mechanism against myocardial I/R injury.

NF-κB signaling blockade by Bay 11-7085 during early cardiac morphogenesis induces alterations of the outflow tract in chicken heart

Nuclear factor kappaB (NF-kappaB) is a pleiotropic transcription factor implicated in the regulation of diverse morphologic cardiac alterations, for which the p50 and p65 subunits form the most prevalent dimeric form in the heart. NF-kappaB is inactivated by proteins of the IkappaB family, which trap it in the cytoplasm. It is not known whether NF-kappaB influences cardiac development.

OBJECTIVE

Here we investigated the role of NF-kappaB in regulating transcription in chicken heart morphogenesis. Specifically, we tested whether NF-kappaB activation is required for normal formation of the outflow tract (OFT) during a critical stage of heart development.

METHODS AND RESULTS

We designed a reporter vector with kappaB binding sites for Rel family members in the promoter, upstream from the cDNA of Green Fluorescent Protein (GFP). This construct was injected directly into the developing heart of chicken embryos. NF-kappaB activation was subsequently inhibited by administration of the specific pharmacological agent Bay 11-7085. We found that forced NF-kappaB expression was associated with multiple congenital cardiac alterations of the OFT (mainly IVC, DORV and great arteries stenosis).

CONCLUSION

These findings indicate that blockade of NF-kappaB induces apoptosis and is an important factor in the development of OFT during cardiogenesis. However, it remains unknown which members of the Rel family are relevant in this process.

Ischemic preconditioning or p38 MAP kinase inhibition attenuates myocardial TNF α production and mitochondria damage in brief myocardial ischemia

Coronary artery occlusion increased the TNF alpha level in the membrane fraction of the rat heart, almost maximally at 30 min. TNF alpha immunofluorescence labeled streak-like reticular structures inside of the cardiomyocyte but not vascular or interstitial cells in myocardial ischemia. Immuno-electron microscopy confirmed the localization of TNF alpha between myofibrils, mitochondria, or other membrane structures in the ischemic cardiomyocyte. Ischemic preconditioning (IP) is the protection of myocardium conferred by cycles of brief ischemia-reperfusion. The increases in TNF alpha production, as well as phosphorylation of p38 MAP kinase and S6 kinase after ischemia were inhibited by IP or p38 MAP kinase inhibitors (SB203580, FR167653). TNF alpha production appeared to be regulated possibly at the post-transcriptional step by ribosomal S6 phosphorylation given that IP did not suppress TNF alpha mRNA up-regulation and was independent of NFkappaB activation. Electron microscopy (EM) showed mitochondria damage in ischemic cardiomyocyte, which was inhibited either by IP or SB203580. This is the first demonstration of the TNF alpha up-regulation in membrane structures of ischemic cardiomyocyte through p38 MAP kinase-mediated post-transcriptional mechanism, in association with mitochondrial damage.

Donor graft adenoviral iNOS gene transfer ameliorates rat liver transplant preservation injury and improves survival

The exact role of inducible NOS (iNOS) in liver ischemia/reperfusion (I/R) injury is controversial. This study was designed to investigate whether donor liver pretreatment with adenovirus encoding iNOS (AdiNOS) ameliorates I/R injury associated with liver transplantation. Orthotopic syngeneic LEW rat liver transplantation (OLT) was performed after 18 or 24 hours' preservation in cold UW. AdiNOS or control gene vector (AdLacZ) was delivered to the liver by donor intravenous pretreatment 4 days before graft harvesting. Uninfected grafts also served as control. Recipients were sacrificed 1 to 48 hours posttransplantation. An abundant hepatic iNOS protein expression and marked serum NO elevation was observed in the AdiNOS-treated group, without affecting endothelial nitric oxide synthase (eNOS) expression, before harvesting and after OLT. AdiNOS pretreatment markedly improved liver function assessed by serum aspartate aminotransferase/alanine aminotransferase levels and reduced liver necrosis formation. AdiNOS treatment also was associated with reduced ICAM-1 mRNA expression and neutrophil accumulation in the liver graft after OLT compared with untransfected or AdLacZ-treated group. Furthermore, AdiNOS delivery significantly improved transplant survival, compared with AdLacZ or saline controls. AdiNOS pretreatment did not attenuate I/R-induced apoptotic cell death in the liver graft. Administration of a selective inhibitor for iNOS abrogated the protection afforded by AdiNOS pretreatment. In conclusion, donor pretreatment with AdiNOS led to improved liver graft injury and posttransplantation survival. Downregulation of ICAM-1 mRNA and neutrophil infiltration may be associated with the mechanisms by which AdiNOS pretreatment confer the protection against transplant-associated hepatic I/R injury.