Inducible nitric oxide synthase and tumor necrosis factor in animal models of myocardial necrosis induced by coronary artery ligation or isoproterenol injection

Anti-Inflammatory Activity ofSchizonepeta tenuifoliathrough the Inhibition of MAPK Phosphorylation in Mouse Peritoneal Macrophages

Schizonepeta tenuifolia (ST) is a well-known herb to treat the cold and its associated headache. However, the anti-inflammatory mechanism of ST in mouse peritoneal macrophages is not clear. In this study, we demonstrated that ST inhibited lipopolysaccaride (LPS)-induced tumor necrosis factor (TNF)-α and interleukin (IL)-6 production. The maximal inhibition rate of TNF-α and IL-6 production by ST (2 mg/ml) was 48.01 ± 2.8% and 56.45 ± 2.8%, respectively. During the inflammatory process, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) were increased in mouse peritoneal macrophages. However, treated with ST decreased the protein level of COX-2 and iNOS, as well as the production of PGE2and NO in LPS-stimulated mouse peritoneal macrophages. In addition, ST inhibited the phosphorylation of MAPK. Taken together, the results of this study suggest an important molecular mechanism by which ST reduces inflammation, which may explain its beneficial effect in the regulation of inflammatory reactions.

Anti-Inflammatory Activity of Hyperoside Through the Suppression of Nuclear Factor-κB Activation in Mouse Peritoneal Macrophages

Hyperoside (quercetin-3-O-galactoside) is a flavonoid compound mainly found in the herb plants Hypericum perforatum L and Crataegus pinnatifida. Although hyperoside has a variety of pharmacological effects including anti-viral, anti-oxidative, and anti-apoptotic activities, the anti-inflammatory mechanism of hyperoside in mouse peritoneal macrophages remains unclear. In this study, hyperoside was shown to exert an anti-inflammatory action through suppressed production of tumor necrosis factor, interleukin-6, and nitric oxide in lipopolysaccharide-stimulated mouse peritoneal macrophages. The maximal inhibition rate of tumor necrosis factor-α, interleukin-6, and nitric oxide production by 5 μM hyperoside was 32.31 ± 2.8%, 41.31 ± 3.1%, and 30.31 ± 4.1%, respectively. In addition, hyperoside inhibited nuclear factor-κB activation and IκB-α degradation. The present study suggests that an important molecular mechanism by hyperoside reduces inflammation, which might explain its beneficial effect in the regulation of inflammatory reactions.

Anti-inflammatory effects of Scutellaria baicalensis water extract on LPS-activated RAW 264.7 macrophages

AIM OF THE STUDY

The root of Scutellaria baicalensis Georgi (Labiatae), also known as Scutellariae Radix, possesses anticancer, antiviral, and anti-inflammatory properties. And it is one of the most widespread herbal remedies used in Oriental medicine. In the present study, we investigated the effects of Scutellariae Radix water extract (SR) on proinflammatory mediators secreted from lipopolysaccharide (LPS)-induced RAW 264.7 macrophages.

MATERIAL AND METHODS

Cell viability was assessed by MTT assay and nitric oxide (NO) concentration in the cultured medium was determined by the Griess reaction. Various Cytokines released from LPS-induced Raw 264.7 cells were measured in the cell culture supernatants using a multiplex bead array assay based on xMAP technology.

RESULTS

We found that SR significantly inhibited the production of NO, interleukin (IL)-3, IL-6, IL-10, IL-12p40, IL-17, interferon-inducible protein (IP)-10, keratinocyte-derived chemokine (KC), and vascular endothelial growth factor (VEGF) in LPS-induced RAW 264.7 cells at the concentrations of 25, 50, 100, 200 microg/ml (p<0.05).

CONCLUSIONS

These results suggest that SR has anti-inflammatory activity related with its inhibition of NO, cytokine, chemokine, and growth factor production in macrophages.

Isoproterenol-induced heart failure in the rat is associated with nitric oxide-dependent functional alterations of cardiac function

AIMS

The role of nitric oxide (NO) in heart failure (HF) is complex and remains controversial. We tested the hypothesis that the role of NO in isolated atria and cardiomyocytes is altered in isoproterenol-induced HF.

METHODS AND RESULTS

Rats received isoproterenol (ISO, 5 mg/kg/day, intraperitoneally) or vehicle for 1 week. Haemodynamic parameters were obtained by left ventricular catheterization. Effects of NOS inhibition on isolated atria and on electrically paced left ventricular myocytes were determined. Additionally, expressions of nitric oxide synthases and their allosteric modulators hsp90, caveolin-1, and caveolin-3 proteins in the left ventricles were measured. ISO increased left ventricular mass by 33% and decreased indices of left ventricular systolic and diastolic function dp/dtmin and dp/dtmax (both P<0.05). Isolated atria from HF rats had a lower spontaneous beating rate (P<0.05). NOS inhibition by L-NAME increased basal frequency and attenuated the positive chronotropic effect of beta-adrenergic stimulation in the HF group (P<0.05). Ventricular myocytes from failing hearts had impaired cell shortening. L-NAME decreased contractility of control, but not failing myocytes. Left ventricular expressions of eNOS, hsp90, iNOS, but not nNOS or caveolins, were increased.

CONCLUSION

Despite the increased capacity for NO synthesis in isoproterenol-induced HF, NO does not sustain contractility of failing myocytes. NO may contribute to the decreased basal heart rate and it may accelerate beta-adrenergic stimulation of chronotropy.

Anti-inflammatory activity of gumiganghwaltang through the inhibition of nuclear factor-kappa B activation in peritoneal macrophages

Gumiganghwaltang (GMGHT) is an Oriental herbal prescription, which has been commonly used to treat a cold and inflammatory diseases in Korea. However, the mechanism of GMGHT is not clear. In this study, we investigated the anti-inflammatory mechanism of GMGHT in mouse peritoneal macrophages. GMGHT exerted an anti-inflammatory action through inhibiting lipopolysaccaride (LPS)-induced tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production in mouse peritoneal macrophages. The maximal inhibition rate of TNF-alpha, and IL-6 production by GMGHT (1 mg/ml) was 52.31+/-2.8% and 56.31+/-3.1%, respectively. In the inflammatory process, cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) increased in peritoneal macrophages. GMGHT decreased the protein level of COX-2 and iNOS in LPS-stimulated mouse peritoneal macrophages. In addition, GMGHT inhibited nuclear factor-kappaB activation and IkappaB-alpha degradation. Our study suggests that an important molecular mechanism by GMKHT reduce inflammation, which might explain its beneficial effect in the regulation of inflammatory reactions.

The role of selective nitric oxide synthase inhibitor on nitric oxide and PGE2 levels in refractory hemorrhagic-shocked rats

BACKGROUND

The up-regulation of nitric oxide (NO) and cyclooxgenase-2 (COX-2) has been implicated in the pathophysiology of hemorrhagic shock. We examined the effects of aminoguanidine (AG), which is a known inducible nitric oxide synthase (iNOS) inhibitor, and NS-398, a known COX-2 inhibitor, in our rat model of refractory hemorrhagic shock (RHS).

MATERIAL AND METHODS

We measured tissue iNOS and COX-2 protein expression, brain and plasma nitrate/nitrite and prostaglandin E2 (PGE2) levels, plasma creatinine and glutamic oxalacetic transaminase (GOT) levels, quantified the histological damages in kidney, liver, lung, and brain, survival rate, and mean arterial blood pressure (MABP) in RHS rats.

RESULTS

Semiquantitative analysis of tissues showed iNOS protein was not detected in AG + RHS rats but was detected in normal saline and NS-398 RHS rats. Tissue COX-2 protein was not detected in AG and NS-398 RHS rats but was detected in normal saline + RHS rats. The levels of brain and plasma nitrate/nitrite and PGE2 and plasma creatinine and GOT were significantly lower in the AG + RHS rat group when compared with the normal saline RHS rat group. Histological examinations also showed a reduction in organ damage for AG + RHS rats when compared with treated RHS rats. AG + RHS rats showed significantly increased survival and MABP level when compared with treated RHS rats.

CONCLUSION

Our present findings suggest that NO produced by iNOS might result in organ damages. This in turn might lead to COX-2 up-regulation, and it increases the production of reactive oxygen species and toxic prostanoids. NO-mediated organ damage might be one way in which toxic products of COX-2 might further contribute to NO's deleterious effect in the later stages of RHS. It is therefore suggested that treatment of AG via inhibition of NO might contribute to improved physiological parameters and survival rates following RHS.

Mechanisms of Combined Treatment With Celiprolol and Candesartan for Ventricular Remodeling in Experimental Heart Failure

BACKGROUND

Both beta-adrenergic blockers and angiotensin-II receptor blockers were reported to improve the prognosis of patients with heart failure, but the efficacy of combination therapy with these agents has not been fully elucidated. Also the efficacy of celiprolol, a beta1-selective adrenoceptor antagonist with partial beta2-agonist properties, for heart failure treatment is still controversial. We examined the cardioprotective effects and mechanisms of the therapy with celiprolol or candesartan, an angiotensin-II receptor blockers and their combination in heart failure induced by isoproterenol (ISO).

METHODS AND RESULTS

ISO 300 mg/kg was injected in rats to produce heart failure. Two months after the injection, the ISO-injected rats were divided into 4 groups (8 rats each) and treated for 4 weeks as follows: (a) vehicle; (b) celiprolol 10 mg/kg per day (BB); (c) candesartan 0.2 mg/kg per day (ARB); and (d) their combination BB+ARB. ISO significantly elevated left ventricular (LV) end-diastolic pressure, decreased peak-negative dP/dt and LV ejection fraction. BB and ARB similarly ameliorated cardiac dysfunction due to ISO, but BB+ARB were more potent than the individual therapies. Separately, ARB preserved the histological structure in LV myocardium. In contrast, BB ameliorated calcium handling, as shown by the increased ratio of SERCA2 to phospholamban protein, despite having little effect on the histology.

CONCLUSION

Both celiprolol and candesartan showed cardioprotective effects in this heart failure model. The potential use of the combination treatment in heart failure might result in a synergistic effect through the different cardioprotective mechanisms of celiprolol and candesartan.

Acute myocardial infarction induces hypothalamic cytokine synthesis

The inflammatory milieu of acute myocardial infarction (MI) is theoretically conducive to enhanced cytokine synthesis within the brain. We tested the hypothesis that synthesis of tumor necrosis factor-alpha (TNF-alpha), an indicator of proinflammatory cytokine activity, increases in brain after MI. MI was induced in rats by ligating the left anterior descending coronary artery and confirmed by echocardiography. Plasma and tissue levels of TNF-alpha were measured using ELISA; TNF-alpha mRNA was measured with real-time PCR. Heart, brain, and plasma samples were obtained 0.5, 1, 4, or 24 h or 4 wk after MI. TNF-alpha synthesis increased in the brain, heart, and plasma within minutes to hours after MI and was sustained over the interval tested. Among the brain tissues examined, TNF-alpha increased selectively in hypothalamus. Chronic treatment with pentoxifylline prevented the increases in TNF-alpha in brain, heart, and plasma measured 4 wk after MI. MI-induced cytokine synthesis in the hypothalamus and its prevention by pentoxifylline have important implications in the context of the development of heart failure after MI.

Influence of selective nitric oxide synthetase inhibitor for treatment of refractory haemorrhagic shock

OBJECTIVE

Haemorrhagic shock (HS) is implicated in the induction of inducible nitric oxide synthase that leads to increased production of nitric oxide (NO). We investigated the influence of aminoguanidine (AG), a selective iNOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor and S-Nitroso-N-acetylpenicillamine (SNAP), a NO donor, each of which was given with (+) or without (-) angiotensin II (ANGII), a vasoconstrictor, on the survival rate of HS decompensatory phased (HSDP) rats.

MATERIALS AND METHODS

HSDP was achieved via a constant pressure method. Organs were harvested and analyzed from rats sacrificed 72 h after HSDP or upon death. Plasma collected from HSDP rats were used to measure nitrate/nitrite, GOT and creatinine levels.

RESULTS

AG+ANGII-treated rats had significantly higher survival rates compared to the other treatment groups, 72 h following HSDP. A marked increase in MABP level was observed in AG+ANGII-treated rats when compared to other treatment groups. Histological examinations also showed a reduction of organ damage in AG+ANGII-treated rats compared to other treatment groups. Nitrate/nitrite level, glutamic oxalacetic transaminase (GOT) level and creatinine level were also significantly improved in AG+ANGII-treated rats compared to the other groups.

CONCLUSIONS

A greater beneficial effect was achieved with treatment by the AG+ANGII combination. Our experiments showed that the inhibition of excessive NO formation that occurred during HSDP, had augmented the vascular responsiveness effect of ANGII following protracted HS.

Lipopolysaccharide-induced increase of prostaglandin E(2) is mediated by inducible nitric oxide synthase activation of the constitutive cyclooxygenase and induction of membrane-associated prostaglandin E synthase

NO produced by the inducible NO synthase (NOS2) and prostanoids generated by the cyclooxygenase (COX) isoforms and terminal prostanoid synthases are major components of the host innate immune and inflammatory response. Evidence exists that pharmacological manipulation of one pathway could result in cross-modulation of the other, but the sense, amplitude, and relevance of these interactions are controversial, especially in vivo. Administration of 6 mg/kg LPS to rats i.p. resulted 6 h later in induction of NOS2 and the membrane-associated PGE synthase (mPGES) expression, and decreased constitutive COX (COX-1) expression. Low level inducible COX (COX-2) mRNA with absent COX-2 protein expression was observed. The NOS2 inhibitor aminoguanidine (50 and 100 mg/kg i.p.) dose dependently decreased both NO and prostanoid production. The LPS-induced increase in PGE(2) concentration was mediated by NOS2-derived NO-dependent activation of COX-1 pathway and by induction of mPGES. Despite absent COX-2 protein, SC-236, a putative COX-2-specific inhibitor, decreased mPGES RNA expression and PGE(2) concentration. Ketoprofen, a nonspecific COX inhibitor, and SC-236 had no effect on the NOS2 pathway. Our results suggest that in a model of systemic inflammation characterized by the absence of COX-2 protein expression, NOS2-derived NO activates COX-1 pathway, and inhibitors of COX isoforms have no effect on NOS2 or NOS3 (endothelial NOS) pathways. These results could explain, at least in part, the deleterious effects of NOS2 inhibitors in some experimental and clinical settings, and could imply that there is a major conceptual limitation to the use of NOS2 inhibitors during systemic inflammation.

Retinoic acid attenuates inducible nitric oxide synthase (NOS2) activation in cultured rat cardiac myocytes and microvascular endothelial cells

S. Grosjean, Y. Devaux, C. Seguin, C. Meistelman, F. Zannad, P.-M. Mertes, R. A. Kelly and D. Ungureanu-Longrois. Retinoic Acid Attenuates Inducible Nitric Oxide Synthase (NOS2) Activation in Cultured Rat Cardiac Myocytes and Microvascular Endothelial Cells. Journal of Molecular and Cellular Cardiology (2001) 33, 933-945. The inducible NO synthase (NOS2) in cardiac tissue contributes to myocardial and coronary inflammation and dysfunction. Several natural (endogenous) hormones such as retinoic acid, the active metabolite of vitamin A, have the ability to attenuate NOS2 activation in inflammatory cells. The aim of this study was to investigate the effect of RA on NOS2 activation in cultured cardiac microvascular endothelial cells (CMEC) and adult rat ventricular myocytes (ARVM). CMEC were stimulated either with a combination of 10 microg/ml lipopolysaccharide (LPS) and 50 IU/ml interferon- gamma (IFN- gamma) or with a combination of 1 ng/ml interleukin-1 beta (IL-1 beta)+IFN- gamma whereas ARVM were stimulated with 1 ng/ml IL-1 beta and 50 IU/ml IFN- gamma in the absence or presence of all-trans retinoic acid (atRA). Activation of the NOS2 pathway was estimated by measurement of mRNA (Northern blot) and protein (Western blot) expression, enzyme activity by conversion of [(3)H]L -arginine to [(3)H]L -citrulline, and nitrite accumulation. NOS2 mRNA half-life was studied in CMEC and ARVM in the presence of actinomycin D. In CMEC and ARVM stimulated with a combination of LPS and/or cytokines, atRA (10(-6), 10(-5)M) significantly (P<0.05) attenuated NOS2 mRNA and protein expression, enzymatic activity and reduced supernatant nitrite concentration. Upon stimulation with LPS/IFN- gamma, atRA significantly decreased NOS2 mRNA half-life. This was not seen after stimulation with IL-1 beta/IFN- gamma. These results document for the first time an effect of RA on NOS2 activation in cardiac cells. They may contribute to the characterization of the immunomodulatory effects of retinoids in myocardial and coronary inflammatory disorders.

The role of tumor necrosis factor alpha in the pathophysiology of congestive heart failure

A variety of clinical and experimental investigations have suggested that tumor necrosis factor alpha (TNF-alpha) may play a role in the pathophysiology of heart failure. Serum levels of TNF-alpha are elevated in patients with heart failure, and both cardiac and infiltrating cells of the myocardium can produce this proinflammatory cytokine. Both cardiac myocytes and nonmyocytes also express receptors for TNF-alpha, and experimental studies on isolated cells, muscles, and transgenic models demonstrate the ability of TNF-alpha to recapitulate functional and biochemical alterations resembling that observed in human congestive heart failure. The intracellular pathways affected by TNF-alpha include production of ceramide and an alteration in calcium metabolism. Recent studies in both animal models and clinical investigations suggest that anti-TNF-alpha therapies may limit the pathophysiologic consequences of congestive heart failure.