Effects of inhibition of nitric oxide synthesis on TNF alpha serum levels in E. coli endotoxemic rats

Tumor Necrosis Factor-Alpha Induces Proangiogenic Profiling of Cardiosphere-Derived Cell Secretome and Increases Its Ability to Stimulate Angiogenic Properties of Endothelial Cells

Ischemic heart disease and its complications, such as myocardial infarction and heart failure, are the leading causes of death in modern society. The adult heart innately lacks the capacity to regenerate the damaged myocardium after ischemic injury. Multiple lines of evidence indicated that stem-cell-based transplantation is one of the most promising treatments for damaged myocardial tissue. Different kinds of stem cells have their advantages for treating ischemic heart disease. One facet of their mechanism is the paracrine effect of the transplanted cells. Particularly promising are stem cells derived from cardiac tissue per se, referred to as cardiosphere-derived cells (CDCs), whose therapeutic effect is mediated by the paracrine mechanism through secretion of multiple bioactive molecules providing immunomodulatory, angiogenic, anti-fibrotic, and anti-inflammatory effects. Although secretome-based therapies are increasingly being used to treat various cardiac pathologies, many obstacles remain because of population heterogeneity, insufficient understanding of potential modulating compounds, and the principles of secretome regulation, which greatly limit the feasibility of this technology. In addition, components of the inflammatory microenvironment in ischemic myocardium may influence the secretome content of transplanted CDCs, thus altering the efficacy of cell therapy. In this work, we studied how Tumor necrosis factor alpha (TNFa), as a key component of the pro-inflammatory microenvironment in damaged myocardium from ischemic injury and heart failure, may affect the secretome content of CDCs and their angiogenic properties. We have shown for the first time that TNFa may act as a promising compound modulating the CDC secretome, which induces its profiling to enhance proangiogenic effects on endothelial cells. These results allow us to elucidate the underlying mechanisms of the impact of the inflammatory microenvironment on transplanted CDCs and may contribute to the optimization of CDC efficiency and the development of the technology for producing the CDC secretome with enhanced proangiogenic properties for cell-free therapy.

Immunonutrition: facilitating mucosal immune response in teleost intestine with amino acids through oxidant-antioxidant balance

Comparative animal models generate fundamental scientific knowledge of immune responses. However, these studies typically are conducted in mammals because of their biochemical and physiological similarity to humans. Presently, there has been an interest in using teleost fish models to study intestinal immunology, particularly intestinal mucosa immune response. Instead of targeting the pathogen itself, a preferred approach for managing fish health is through nutrient supplementation, as it is noninvasive and less labor intensive than vaccine administrations while still modulating immune properties. Amino acids (AAs) regulate metabolic processes, oxidant-antioxidant balance, and physiological requirements to improve immune response. Thus, nutritionists can develop sustainable aquafeeds through AA supplementation to promote specific immune responses, including the intestinal mucosa immune system. We propose the use of dietary supplementation with functional AAs to improve immune response by discussing teleost fish immunology within the intestine and explore how oxidative burst is used as an immune defense mechanism. We evaluate immune components and immune responses in the intestine that use oxidant-antioxidant balance through potential selection of AAs and their metabolites to improve mucosal immune capacity and gut integrity. AAs are effective modulators of teleost gut immunity through oxidant-antioxidant balance. To incorporate nutrition as an immunoregulatory means in teleost, we must obtain more tools including genomic, proteomic, nutrition, immunology, and macrobiotic and metabonomic analyses, so that future studies can provide a more holistic understanding of the mucosal immune system in fish.

Roles of dietary supplementation with arginine or N-carbamylglutamate in modulating the inflammation, antioxidant property, and mRNA expression of antioxidant-relative signaling molecules in the spleen of rats under oxidative stress

This study evaluated the effects of arginine (Arg) or N-carbamylglutamate (NCG) on inflammation, antioxidant property, and antioxidant-related gene expression in rat spleen under oxidative stress. A total of 52 rats were randomly distributed into 4 treatment groups with 13 replicates per group. Rats were fed a basal diet (BD) or BD supplemented with Arg or NCG for 30 days. On day 28, half of the BD-fed rats were intraperitoneally injected with sterile saline (control group), and the other half with 12 mg/kg body weight of diquat (DT; DT group). The other 2 diet groups were intraperitoneally injected with 12 mg/kg body weight of DT with either Arg (1%) (DT + Arg) or NCG (0.1%) (DT + NCG). Rat spleen samples were collected for analysis at 48 h after DT injection. Results showed that DT damaged the antioxidant defense in rats compared with the control group (P < 0.05). Compared with the DT group, the DT + Arg and DT + NCG groups manifested improved anti-hydroxyl radical, catalase, and total superoxide dismutase (T-SOD) activities, increased glutathione content (P < 0.05), and decreased malondialdehyde content (P < 0.05). Moreover, compared with the DT group, the DT + Arg and DT + NCG groups enhanced mRNA expression of superoxide dismutase (SOD), glutathione peroxidase 1 (GPx1), glutathione reductase (GR), nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1(Keap-1), and mammalian target of rapamycin (mTOR) (P < 0.05). Both NCG and Arg significantly increased anti-inflammatory cytokine mRNA level but suppressed the pro-inflammatory cytokine mRNA expression under oxidative stress (P < 0.05). In summary, NCG and Arg effectively alleviated oxidative stress, improved the antioxidant capacity and regulated the antioxidant-related signaling molecular expression in rat spleen. N-carbamylglutamate and Arg reduced the inflammation in the spleen by mediating the gene expression of anti-inflammatory and pro-inflammatory cytokines and transforming growth factor-β (TGF-β).

New insights into the role of dietary spermine on inflammation, immune function and related-signalling molecules in the thymus and spleen of piglets

This study aimed to determine the effects of dietary spermine supplementation on the inflammatory response and immune function of the thymus and spleen in piglets. Eighty suckling piglets were randomly assigned to receive adequate nutrients supplemented with spermine (0.4 mmol/kg body weight) or restricted nutrient intake supplemented with normal saline for 7 h or 3, 6 and 9 days in pairs. Regardless of treatment time, spermine supplementation decreased (p < 0.05, compared with the controls) the following: (1) tumour necrosis factor α (TNF-α), interleukin (IL)-1β, 2 and 6, and interferon (IFN)-γ levels in serum; (2) gene expression of cluster of differentiation 8 and integrin beta-2 in the thymus and spleen and the lymphocyte function-associated antigen 1 in the thymus; (3) mRNA levels of TNF-α, IL 1β, 2, 6, and 12, IFN-γ and inducible nitric oxide synthase in the thymus and spleen, as well as IL-8 in the spleen; and (4) eukaryotic IF4E-binding protein 1, Janus kinase 2, signal transducer and activator of transcription 3, and nuclear factor-kappa B P65 gene transcriptions in the thymus and spleen. By contrast, spermine supplementation increased (p < 0.05) the following: (1) immunoglobulin M, IL-10, and transforming growth factor β1 gene expression, as well as (2) relative mRNA levels of mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase 1 in the thymus and spleen. These effects were also observed upon prolonged spermine administration (p < 0.05). In summary, dietary spermine supplementation can alleviate inflammatory response, enhance the immune function and regulate the gene expression of signalling molecules related to inflammation.

Effect of dietary arginine on the immune response and gene expression in head kidney and spleen following infection of Jian carp with Aeromonas hydrophila

This study was conducted to test the hypothesis that elevated dietary arginine enhances immunity of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed graded levels of dietary arginine for 9 weeks. Subsequently, a challenge test was conducted by injection of Aeromonas hydrophila. Head kidney and spleen weights, as well as erythrocyte and leukocyte counts were significantly influenced by dietary arginine levels. A similar trend was also observed for hemagglutination titre, serum lysozyme activity, IgM concentration, C3 and C4 content. The highest survival rates following A. hydrophila infection were obtained in fish fed the diets containing arginine at 16.1-21.9 g/kg diet. Phagocytic activity of leukocytes was significantly enhanced by dietary arginine supplementation. In contrast, acid phosphatase activity significantly decreased with dietary arginine levels. Dietary arginine levels did not have a significant effect on the total iron-binding capacity. Gene expression of TNF-α and TGF-β in head kidney significantly increased with dietary arginine levels up to 21.9 g/kg diet, and decreased thereafter. Fish fed the basal diet exhibited the highest IL-10 mRNA expression level. Gene expression of IL-1β and TOR increased with dietary arginine addition, reaching a plateau at 18.5 and 21.9 g arginine/kg diet, respectively. In spleen, higher IL-1β and TNF-α gene expressions were obtained in fish fed the diets containing 24.5 g arginine/kg diet than in fish fed the other dietary treatments. TGF-β mRNA expression levels were significantly lower in fish fed the diets containing ≤21.9 g arginine/kg diet. IL-10 and TOR mRNA expression levels were lower in fish fed 16.1 g arginine/kg diet, while 4E-BP mRNA expression levels increased with dietary arginine levels up to 12.7 g/kg diet and decreased thereafter. Our results indicate that arginine has beneficial effects on regulating mRNA expression of inflammatory cytokines, as well as TOR and 4E-BP and improving humoral and cellular immunity, therefore enhancing disease resistance of fish.

Inhibition of inducible nitric oxide synthesis ameliorates liver ischemia and reperfusion injury induced transient increase in arterial stiffness

PURPOSE

Hemodynamic instability is a frequent scenario after reperfusion of ischemic liver due to major liver resection and liver transplantation. Previously, we showed that liver ischemia/reperfusion (I/R) injury induced increases in reactive oxygen/nitrogen species and inducible nitric oxide synthase (iNOS) expression impaired cardiac contractility. In addition, nitric oxide (NO) generated via iNOS may have impacts on large arterial smooth muscle tone, causing transient changes in arterial stiffness and ventricular afterload. In this study, we aim to investigate associations between iNOS and transient alternation in arterial stiffness during liver I/R injury, and effects of treatments with 1,400W, a selective iNOS inhibitor, and L-NG nitroarginine methyl ester (L-NAME), a non-specific NOS inhibitor.

METHODS

The arterial stiffness is evaluated using the pulse wave velocity (PWV(2)), measured by finding the means of two high-fidelity micromanometers positioned at the aortic root and left femoral artery. Liver ischemia was conducted by occluding both the hepatic artery and portal vein for 30 minutes, followed by 120 minutes of reperfusion. Studies were performed on male Sprague-Dawley rats in four groups: a sham-operated group, a liver I/R group, and those groups pretreated with 1,400W (N-[3-(aminomethyl)benzyl]acetamidine) or L-NAME. Serum NO metabolites, tumor necrosis factor-α (TNF-α) and methylguanidine (MG) were measured at baseline, 30 minutes of ischemia, and 120 minutes of reperfusion.

RESULTS

Post-reperfusion arterial stiffness increased by ∼14% as compared with the baseline, along with increases in serum NO metabolites, TNF-α, and MG level (P < .05); 1,400W and L-NAME treatment reduces post-reperfusion arterial stiffness by ∼5% similarly. Treatments with 1,400W and L-NAME both attenuated I/R induced increases in serum TNF-α, MG, and NO metabolites level (P < .05).

CONCLUSIONS

I/R-induced arterial stiffening was strongly associated with increased systemic inflammation. Comparable effects with treatments of 1,400W and L-NAME suggested that iNOS plays a dominant role in I/R-induced transient arterial stiffening.

TNFα in myocardial ischemia/reperfusion, remodeling and heart failure

TNFα is crucially involved in the pathogenesis and progression of myocardial ischemia/reperfusion injury and heart failure. The formation and release of TNFα and its downstream signal transduction cascade following activation of its two receptor subtypes are characterized. Myocardial TNFα and TNF receptor activation have an ambivalent role in myocardial ischemia/reperfusion injury and protection from it. Excessive TNFα expression and subsequent cardiomyocyte TNF receptor type 1 stimulation induce contractile dysfunction, hypertrophy, fibrosis and cell death, while a lower TNFα concentration and subsequent cardiomyocyte TNF receptor type 2 stimulation are protective. Apart from its concentration and receptor subtype, the myocardial action of TNFα depends on the duration of its exposure and its localization. While detrimental during sustained ischemia, TNFα contributes to ischemic preconditioning protection, no matter whether it is the first, second or third window of protection, and both TNF receptors are involved in the protective signal transduction cascade. Finally, the available clinical attempts to antagonize TNFα in cardiovascular disease, notably heart failure, are critically discussed.

Free radical-induced contractile protein dysfunction in endotoxin-induced sepsis

Recent studies have indicated that sepsis is associated with enhanced generation of several free-radical species (nitric oxide [NO], superoxide, hydrogen peroxide) in skeletal muscle. It is also known that this enhanced free-radical generation results in reductions in skeletal muscle force-generating capacity, but the precise mechanism(s) by which free radicals exert this effect in sepsis has not been determined. We postulated that free radicals might react directly with the contractile proteins in this condition, altering contractile protein force-generating capacity. To test this theory, we compared the force generation of single Triton-skinned diaphragmatic fibers (Triton skinning exposes the contractile apparatus, permitting direct assessment of contractile protein function) from the following groups of rats: (1) control animals; (2) endotoxin-treated animal; (3) animals given endotoxin plus polyethylene glycol- superoxide dismutase (PEG-SOD), a superoxide scavenger; (4) animals given endotoxin plus N(omega)-nitro-L-arginine methylester (L-NAME), a NO synthase inhibitor; (5 ) animals given only PEG-SOD or L-NAME; and (6 ) animals given endotoxin plus denatured PEG-SOD. We found that endotoxin administration produced both a reduction in the maximum force-generating capacity (Fmax) (i.e., a decrease in Fmax) of muscle fibers and a reduction in fiber calcium sensitivity (i.e., an increase in the Ca2+ concentration required to produce half-maximal activation [Ca50]). L-NAME and PEG-SOD administration preserved Fmax and Ca50 in endotoxin-treated animals; neither drug affected these parameters in non-endotoxin treated animals. Denatured PEG-SOD failed to inhibit endotoxin-related alterations in contractile protein function. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of skinned fibers from endotoxin-treated animals revealed a selective depletion of several proteins; administration of L-NAME or PEG-SOD to endotoxin-treated animals prevented this protein depletion, paralleling the effect of these two agents to prevent a reduction in contractile protein force-generating capacity. These data indicate that free radicals (superoxide, NO, or daughter species of these radicals) play a central role in altering skeletal muscle contractile protein force-generating capacity in endotoxin-induced sepsis.

Effect of L-NAME, an inhibitor of nitric oxide synthesis, on plasma levels of IL-6, IL-8, TNF alpha and nitrite/nitrate in human septic shock

OBJECTIVES

We tested the effects of NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, on plasma levels of interleukin (IL) IL-6, IL-8, tumor necrosis factor-alpha (TNFalpha) and nitrite/nitrate (NO2-/ NO3-) in patients with severe septic shock.

DESIGN

Prospective clinical study.

SETTING

Surgical intensive care unit at a university hospital.

PATIENTS

11 consecutive patients with severe septic shock.

INTERVENTIONS

Standard hemodynamic measurements were made and blood samples taken at intervals before, during, and after a 12-h infusion of L-NAME 1 mg x kg(-1) x h(-1) for determination of plasma IL-6, IL-8, TNFalpha and NO2-/NO3- concentration.

MEASUREMENTS AND RESULTS

Patients with sepsis had increased plasma levels of IL-6, IL-8, TNFalpha and NO2-/NO3- (p < 0.05). Plasma levels of IL-6. IL-8, and NO2-/NO- were negatively correlated with systemic vascular resistance (r = -0.62, r = -0.65, and r = -0.78, respectively, all p < 0.05). Continuous infusion of L-NAME increased mean arterial pressure and systemic vascular resistance, with a concomitant reduction in cardiac output (all p < 0.01). No significant changes were seen in levels of plasma IL-6, IL-8, and NO-/NO3- during the 24-h observation period. Plasma levels of TNFalpha were significantly reduced during L-NAME infusion compared to baseline (p < 0.05).

CONCLUSIONS

NO plays a role in the cardiovascular derangements of human septic shock. Inhibition of NO synthesis with L-NAME does not promote excessive cytokine release in patients with severe sepsis.