Role of tumour necrosis factor in the induction of nitric oxide synthase in a rat model of endotoxin shock

The Effects of Ionotropic GABA Receptor Blockage on the Brain in Rats with Induced Sepsis

Encephalopathy following sepsis is defined as life-threatening organ failure due to the irregular response of the host to infection and has high mortality and morbidity rates. The present study aimed to investigate the effects of inflammation and the gamma-aminobutyric acid-A (GABAA) receptor antagonist, bicuculline, on brain tissue in rats with sepsis. Sepsis was experimentally generated using lipopolysaccharide (LPS). The rats were divided into four groups: control, LPS (10 mg/kg i.p.), bicuculline (1.5 mg/kg s.c.), and LPS+Bic. Electrophysiologic recordings and body temperature measurements were completed at the 24th hour, and samples were taken. TNF-α, IL-10, GABA, and MDA levels were measured. Tissue imaging was performed using S100-ß, NEUN, and synaptophysin antibodies. One-way ANOVA followed by the Tukey test was performed for statistical analysis. Inflammatory parameters significantly increased in brain tissue in the LPS group compared with the other groups (TNF-α, [F (3.14) = 6.015, p = 0.042]; IL-10, [F (3.15) = 9.013, p = 0.02]). Tissue imaging results were as follows: S100-ß involvement increased, and NeuN and synaptophysin involvement decreased in the LPS group [F (3.21) = 18.016, p = 0.006, for S100-ß; F (3.21) = 19.071, p = 0.003, for NeuN; F (3.21) = 18.098, p = 0.005, for synaptophysin]. In electrophysiologic recordings, we observed activity consistent with acute non-focal seizures in the LPS group. Contrarily, the control and other comparison groups exhibited normal resting neural activity. Bicuculline may be used as a therapeutic agent in sepsis to maintain the neurotransmitter and pro- and anti-inflammatory cytokine balance and reduce lipid peroxidation with its effects of acetylcholine esterase inhibition and GABAA receptor antagonism.

Myeloid ACE2 protects against septic hypotension and vascular dysfunction through Ang-(1-7)-Mas-mediated macrophage polarization

Angiotensin converting enzyme 2 (ACE2) is a new identified member of the renin-angiotensin-aldosterone system (RAAS) that cleaves angiotensin II (Ang II) to Ang (1-7), which exerts anti-inflammatory and antioxidative activities via binding with Mas receptor (MasR). However, the functional role of ACE2 in sepsis-related hypotension remains unknown. Our results indicated that sepsis significantly reduced blood pressure and led to disruption between ACE-Ang II and ACE2-Ang (1-7) balance. ACE2 knock-in mice exhibited improved sepsis-induced mortality, hypotension and vascular dysfunction, while ACE2 knockout mice exhibited the opposite effects. Bone marrow transplantation and in vitro experiments confirmed that myeloid ACE2 exerted a protective role by suppressing oxidative stress, NO production and macrophage polarization via the Ang (1-7)-MasR-NF-κB and STAT1 pathways. Thus, ACE2 on myeloid cells could protect against sepsis-mediated hypotension and vascular dysfunction, and upregulating ACE2 may represent a promising therapeutic option for septic patients with hypotension.

IL-34 exacerbates pathogenic features of Alzheimer's disease and calvaria osteolysis in triple transgenic (3x-Tg) female mice

Hallmark features of Alzheimer's disease (AD) include elevated accumulation of aggregated Aβ40 and Aβ42 peptides, hyperphosphorylated Tau (p-Tau), and neuroinflammation. Emerging evidence indicated that interleukin-34 (IL-34) contributes to AD and inflammatory osteolysis via the colony-stimulating factor-1 receptor (CSF-1r). In addition, CSF-1r is also activated by macrophage colony-stimulating factor-1 (M-CSF). While the role of M-CSF in bone physiology and pathology is well addressed, it remains controversial whether IL-34-mediated signaling promotes osteolysis, neurodegeneration, and neuroinflammation in relation to AD. In this study, we injected 3x-Tg mice with mouse recombinant IL-34 protein over the calvaria bone every other day for 42 days. Then, behavioral changes, brain pathology, and calvaria osteolysis were evaluated using various behavioral maze and histological assays. We demonstrated that IL-34 administration dramatically elevated AD-like anxiety and memory loss, pathogenic amyloidogenesis, p-Tau, and RAGE expression in female 3x-Tg mice. Furthermore, IL-34 delivery promoted calvaria inflammatory osteolysis compared to the control group. In addition, we also compared the effects of IL-34 and M-CSF on macrophages, microglia, and RANKL-mediated osteoclastogenesis in relation to AD pathology in vitro. We observed that IL-34-exposed SIM-A9 microglia and 3x-Tg bone marrow-derived macrophages released significantly elevated amounts of pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6, compared to M-CSF treatment in vitro. Furthermore, IL-34, but not M-CSF, elevated RANKL-primed osteoclastogenesis in the presence of Aβ40 and Aβ42 peptides in bone marrow derived macrophages isolated from female 3x-Tg mice. Collectively, our data indicated that IL-34 elevates AD-like features, including behavioral changes and neuroinflammation, as well as osteoclastogenesis in female 3x-Tg mice.

Baicalin improves the survival in endotoxic mice and inhibits the inflammatory responses in LPS-treated RAW 264.7 macrophages

Introduction:

Sepsis is a severe disease with a high morbidity and mortality. Baicalin, an active compound of Chinese medicine, Scutellaria baicalensis Georgi (Huang Qui), exhibits several beneficial effects. In this study, we examined whether administration of baicalin increases the survival in mice with endotoxemia and investigated its anti-inflammatory mechanisms in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

Methods:

The production of NOx, PGE2, and pro-inflammatory cytokines, the mRNA and protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the nuclear translocation of NF-κB in LPS-stimulated macrophages or endotoxic mice were determined. The model of severe endotoxic mice was established by injection of LPS (60 mg/kg, i.p.).

Results:

Baicalin significantly inhibited the production of NO, PGE2, and pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6 in LPS-stimulated macrophages. Baicalin treatment also markedly suppressed LPS-induced iNOS and COX-2 expression at the transcriptional and translational levels, and the nuclear translocation of NF-κB in macrophages. Similarly, the serum concentrations of NOx, PGE2, and pro-inflammatory cytokines, and the lung myeloperoxidase activity were greatly reduced in baicalin-treated endotoxic mice. Notably, after LPS injection, the 3-day survival rate of mice treated with pre- or post-administration of baicalin (50 mg/kg, i.p.) remarkably increased to 100% and 90%, respectively compared with LPS-injected alone mice with a survival rate of 0%.

Conclusion:

Baicalin has a potent anti-inflammatory activity in LPS-stimulated macrophages and endotoxic mice. Moreover, treatment with baicalin dramatically increased the survival in the severe septic mice, suggesting that baicalin may be a potential agent for sepsis therapy.

Alpha-lipoic acid prevents endotoxic shock and multiple organ dysfunction syndrome induced by endotoxemia in rats

Alpha-lipoic acid (ALA), a naturally occurring disulfide derivative of octanoic acid, serves as a strong antioxidant and has been reported to possess anti-inflammatory effects. The aim of the present study is to investigate the preventive and therapeutic effects of ALA on multiple organ dysfunction syndrome (MODS) caused by endotoxemia in rats. Male Wistar rats were intravenously infused with lipopolysaccharide (LPS) (10 mg/kg) to induce endotoxemia. Alpha-lipoic acid 10, 20, or 40 mg/kg was administered intravenously 60 min before (pretreatment) LPS challenge, and ALA 40 mg/kg was administered intravenously 30 min after (posttreatment) LPS challenge. Pretreatment and posttreatment with ALA significantly improved the deleterious hemodynamic changes 8 h after LPS challenge, including hypotension and bradycardia. Alpha-lipoic acid reduced the plasma levels of glutamic pyruvic transaminase, blood urea nitrogen, lactate dehydrogenase, tumor necrosis factor-α, nitric oxide metabolites, and thrombin-antithrombin complex, which increased markedly after LPS challenge. The induction of inducible nitric oxide synthase both in the liver and the lung and vascular superoxide anion production were also significantly suppressed by ALA. Moreover, ALA significantly attenuated LPS-induced caspase-3 activation in cardiomyocytes and improved survival rate. In conclusion, ALA effectively attenuated LPS-induced acute inflammatory response and improved MODS. The antioxidant and anti-inflammatory effects of ALA may contribute to these beneficial effects. Alpha-lipoic acid might be considered as a novel therapeutic strategy in the prevention of sepsis-induced MODS and inflammatory vascular diseases.

Anti-inflammatory activity of horseradish (Armoracia rusticana) root extracts in LPS-stimulated macrophages

Horseradish (Armoracia rusticana) is a perennial crop belonging to the Brassicaceae family.

Glucocorticoids downregulate systemic nitric oxide synthesis and counteract overexpression of hepatic heme oxygenase-1 during endotoxin tolerance

Heme oxygenase (HO)-1 has antioxidant and cytoprotective properties if properly expressed, whereas nitric oxide (NO) impairs tissue perfusion when greatly increased in the blood circulation. Here we hypothesized that the NO and HO-1 systems are altered during lipopolysaccharide (LPS) tolerance, and that glucocorticoids are crucial modulators of systemic NO production and hepatic HO-1 expression during this intriguing phenomenon of cellular reprogramming. Adrenalectomized (ADX) rats with or without administration of dexamethasone (DEX) were challenged with LPS for 3 consecutive days. The plasma levels of corticosterone and nitrate (NOx), and expression of HO-1 protein were assessed. During tolerance, corticosterone levels were elevated, NOx reduced, and HO-1 overexpressed. ADX rats challenged with LPS for 3 consecutive days exhibited a ∼9-fold increase in NOx and a ∼6-fold increase in HO-1, reverted by DEX. Our findings strongly support the fact that glucocorticoids downregulate systemic NO synthesis and counteract hepatic HO-1 overexpression during LPS tolerance.

The uremic toxin indoxyl sulphate enhances macrophage response to LPS

Indoxyl sulphate (IS) is a protein-bound uremic toxin that results from the metabolism of dietary tryptophan normally excreted by kidney through the proximal tubules. Thus the toxin accumulates in the blood of patients with impaired renal function such as in chronic kidney disease (CKD). High IS serum levels in patients with CKD suggest its involvement in CKD progression and in the onset of complications. Its presence in plasma is also a powerful predictor of overall and cardiovascular morbidity/mortality. IS is a well known nephrovascular toxin but very little is known regarding its effects on the immune system and in particular during inflammation. In this study we examined the effect of IS on macrophage activation in response to lipopolysaccharide from E. coli (LPS), a gram negative bacterial endotoxin associated with inflammation and septic shock. To simulate the uremic condition, J774A.1 macrophages were incubated with IS at concentrations observed in uremic patients (1000-62.5 µM) both alone and during LPS challenge. IS alone induced release of reactive oxygen species (ROS), through a mechanism involving pro- and anti-oxidant systems, and alteration in intracellular calcium homeostasis. When added to J774A.1 macrophages in presence of LPS, IS significantly increased the nitric oxide (NO) release, inducible nitric oxide synthase (iNOS) and cycloxygenase-2 (COX-2) expression. IS pre-treatment was also associated with an increase in tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production by macrophages stimulated with LPS. Mechanistic studies revealed that IS increased LPS-induced NF-kB nuclear translocation, ROS release and altered calcium concentrations, mainly because of mitochondrial calcium overloading. Moreover also in primary mouse peritoneal macrophages IS enhances the inflammatory response to LPS increasing ROS, NO, iNOS, COX-2, TNF-α, IL-6 and NF-kB levels. This study provides evidences that IS stimulates macrophage function and enhances inflammatory reasponse associated with LPS, thus contributing to altered immune response dysfunctions observed in CKD.

P2X7 receptor activation contributes to an initial upstream mechanism of lipopolysaccharide-induced vascular dysfunction

Pro-inflammatory cytokines, chemokines and ROS (reactive oxygen species) are excessively produced in endotoxaemia. However, attempting to inhibit all of these inflammatory signalling pathways at the same time in order to prevent endotoxaemia is difficult. In a previous study we observed that activation of P2X7 receptors elicited the release of IL (interleukin)-1β from LPS (lipopolysaccharide)-incubated vessels. In the present study, we hypothesize that P2X7 receptor activation is the initial event leading to vascular dysfunction following LPS treatment. LPS-induced decreases in MAP (mean arterial pressure) and pressor responses to NE (noradrenaline) were attenuated in P2X7KO (P2X7-knockout) mice. Hyporeactivity in response to PE (phenylephrine) in isolated mesenteric arteries by LPS treatment was also observed in C57BL/6 [WT (wild-type)] mice, which was prevented by IL1ra (IL-1 receptor antagonist), L-NAME (N(G)-nitro-L-arginine methyl ester) and indomethacin and in P2X7KO mice. In addition, treatment with IL1ra plus L-NAME produced an additive inhibition of LPS-induced vascular hyporeactivity, suggesting different signalling pathways between IL-1β and NOS (NO synthase). LPS-induced plasma levels of IL-1β, TNFα (tumour necrosis factor α), IL-10, vascular eNOS (endothelial NOS) and COX2 (cyclo-oxygenase 2) protein expression, as determined by ELISA and Western blot, observed in WT mice were inhibited by IL1ra and in P2X7KO mice. These results suggest that P2X7 receptor activation involves an initial upstream mechanism of LPS-induced vascular dysfunction, which is associated with IL-1β-mediated eNOS, COX2 activation and TNFα release.

Calcitonin gene-related peptide is a promising marker in ulcerative colitis

BACKGROUND

Assessment of the severity and extent of disease activity continues to present challenges for physicians in the treatment of ulcerative colitis. Standard markers that can objectively reflect disease activity are useful for physicians to both evaluate the course of ulcerative colitis and monitor the effectiveness of therapy for any given patient.

AIMS

We hypothesize that calcitonin gene-related peptide (CGRP) can reflect the activity and severity of ulcerative colitis and be used as a marker to assess the effectiveness of various therapies.

METHODS

We examined the expression levels of CGRP by reverse transcription polymerase chain reaction (RT-PCR) and semi-quantitative immunohistochemisty in mucosal biopsies from 38 patients with UC and 18 controls. Levels of CGRP mRNA and protein expression were compared between patients and controls with the clinical activity index (CAI) and the endoscopic activity index (EAI) for various levels of UC severity.

RESULTS

Our results showed that the levels of CGRP mRNA and protein expression were significantly reduced in UC patients compared to controls. This effect was more pronounced in patients with more severe cases of UC. There is a statistically significant negative correlation between levels of CGRP mRNA expression and CAI/EAI scores. A statistically significant negative correlation was also found between levels of CGRP protein expression and CAI/EAI scores. Overall, high CAI and EAI scores were accompanied by low CGRP mRNA and protein expression levels.

CONCLUSION

Levels of CGRP protein and mRNA expression in the colonic mucosa of patients are closely associated with UC severity and corroborate traditional indices used to assess the disease.

Spirodela polyrhiza (L.) Sch. ethanolic extract inhibits LPS-induced inflammation in RAW264.7 cells

OBJECTIVE

Spirodela polyrhiza (L.) Sch. is widely used in Korean traditional medicine. No previous work has investigated in detail the anti-inflammatory activities of S. polyrhiza or assessed in vitro their potential underlying mechanism(s). We assessed the effects of S. polyrhiza ethanolic extract (SPEE) on the production of inflammatory mediators in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and investigated some potential underlying mechanisms. Additionally, we performed simultaneous determination of seven flavonoids in S. polyrhiza by high-performance liquid chromatography (HPLC)-photodiode array (PDA).

MATERIALS AND METHODS

RAW264.7 cells were subjected to 5, 10, 20, and 50 μg/mL of SPEE for 1 h then treated with LPS for 24 h. Production of namely nitric oxide (NO), prostaglandin E(2) and cytokine levels were measured by the Griess reagent and ELISA, respectively. To investigate the underlying mechanisms of the anti-inflammatory activities of SPEE, expression of NO synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor-kappa B (NF-κB) proteins were evaluated by western blot analysis. HPLC analysis was performed using a Gemini C(18) column at 40°C and PDA detection at 340 nm.

RESULTS

SPEE treatment significantly inhibited the LPS-induced production of NO, prostaglandin E(2), interleukin-6, and tumor necrosis factor-α and inhibited the expression of iNOS and COX-2 via attenuation of NF-κB p65 expression. The contents of the seven flavonoids in S. polyrhiza range from 0.25 to 8.77 mg/g.

CONCLUSIONS

These results indicate that the anti-inflammatory activity of SPEE may be NF-κB p65 signaling. Also, the method will help to improve quality control of S. polyrhiza.

Simvastatin inhibits pro-inflammatory mediators through induction of heme oxygenase-1 expression in lipopolysaccharide-stimulated RAW264.7 macrophages

It has been reported that the anti-inflammatory activity of 3-hydroxy-3-methyl-glutary coenzyme A (HMG-CoA) reductase inhibitors (statins) is independent of their hypocholesterolemic effect. Previous studies indicated that induction of heme oxygenase-1 (HO-1) exerts a cytoprotective activity in several inflammatory diseases. Here, the possibility that HO-1 is involved in the anti-inflammatory action of simvastatin, using lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages as a model system has been specifically addressed. Our results demonstrated that in the presence of LPS, simvastatin significantly increased HO-1 expression and activity in a dose-dependent manner compared to that of LPS-stimulated alone macrophages. Moreover, simvastatin significantly inhibited LPS-induced inducible nitric oxide synthase (NOS) expression, and formation of pro-inflammatory mediators, including tumor necrosis factor-α (TNF-α), nitrite and free radicals, but enhanced interleukin-10 (IL-10) production. Similarly, the IκB-α degradation and nuclear transcription factor-κB translocation and activation caused by LPS were significantly suppressed by simvastatin. However, these anti-inflammatory activities of simvastatin were markedly reversed by addition of a HO-1 inhibitor zinc protoporphyrin (ZnPP). Accordingly, the present results indicate that the anti-inflammatory activity of simvastatin could, at least in part, be regulated by induction of HO-1-mediated processes.

The neuropeptide calcitonin gene-related peptide (CGRP) prevents inflammatory liver injury in mice

BACKGROUND/AIMS

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and supposed to be responsible for neurogenic inflammation involved in migraine. Its role in inflammatory diseases of other organs is controversial and poorly investigated regarding liver inflammation, although the organ is innervated by CGRP containing primary sensory nerve fibers.

METHODS

Male Balb/c and IL-10(-/-) mice were pretreated with either alphaCGRP or the CGRP receptor antagonists CGRP(8-37) or BIBN4096BS. Immune-mediated liver injury was induced by administration of lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNFalpha) to galactosamine (GalN)-sensitized mice and evaluated by serum transaminase activities and cytokine levels. Furthermore, intrahepatic CGRP receptor expression and hepatic CGRP concentrations were examined.

RESULTS

CGRP receptor 1 was expressed by immune cells and hepatocytes in human and murine liver. During liver injury CGRP receptor expression was increased whereas hepatic CGRP concentrations concomitantly decreased. While CGRP receptor antagonists failed to affect liver damage, pretreatment with alphaCGRP protected mice from GalN/LPS-induced liver injury by suppression of the pro-inflammatory cytokine response independently from IL-10 but related to the induction of the transcriptional repressor inducible cAMP early repressor (ICER). In contrast, alphaCGRP failed to protect against GalN/TNFalpha-induced liver failure.

CONCLUSION

In the liver, CGRP exerts anti-inflammatory properties, which are characterized by a reduced production of pro-inflammatory cytokines.

Role of neutrophil elastase in development of pulmonary vascular injury and septic shock in rats

Prostacyclin prevents pulmonary vascular injury and shock by inhibiting increases in lung tissue levels of TNF in rats administered endotoxin. We previously reported that NO derived from eNOS increases endothelial production of prostacyclin. Because neutrophil elastase has been shown to decrease endothelial production of prostacyclin by inhibiting NOS activity, we examined whether neutrophil elastase inhibitors reduce pulmonary vascular injury and hypotension by inhibiting the decrease in pulmonary endothelial production of prostacyclin in rats administered endotoxin. Animals were pretreated with sivelestat or L-658,758, neutrophil elastase inhibitors, before endotoxin administration. Lung tissue levels of 6-keto-prostaglandin F1alpha were markedly increased after endotoxin administration, followed by a rapid decrease to baseline levels. Sivelestat and L-658,758 inhibited these decreases as well as inhibiting increases in lung tissue levels of TNF and lung wet-to-dry weight ratios in animals administered endotoxin. These inhibitors also reduced hypotension and inhibited increases in lung tissue levels of mRNA of the inducible form of NOS in animals administered endotoxin. The effects of neutrophil elastase inhibitors were completely reversed by pretreatment with nitro-L-arginine methyl ester, an inhibitor of NOS, or indomethacin, a nonspecific cyclooxygenase inhibitor. These observations suggested that neutrophil elastase might decrease the pulmonary endothelial production of prostacyclin by inhibiting endothelial NO production, thereby contributing to the development of pulmonary vascular injury and shock through increases in lung tissue levels of TNF in rats administered endotoxin.

Therapeutic effects of melatonin on peritonitis-induced septic shock with multiple organ dysfunction syndrome in rats

The pathogenesis of multiple organ dysfunction syndrome (MODS) in septic shock is complicated and not fully understood. Some studies show that an overproduction of nitric oxide (NO) leads to the refractory hypotension and multiple organ failure, while other studies suggest that free radicals, e.g. superoxide (O(2)(-)), contribute to the detrimental effect on vascular responsiveness and tissue/organ damage. Thus, this study was performed on the Wistar rat by using cecal ligation and puncture (CLP) to induce septic shock-associated MODS. We evaluated the effect of an antioxidant melatonin in CLP-induced septic rats and demonstrated that melatonin (3 mg/kg, i.v. at 3, 6, 12 hr after CLP) significantly (a) attenuated hyporeactivity to norepinephrine and delayed hypotension, (b) reduced plasma index of hepatic and renal dysfunction, (c) diminished plasma NO and interleukin-1beta (IL-1beta) concentrations as well as aortic O(2)(-) levels, (d) reduced marked infiltration of polymorphonuclear neutrophils (PMNs) in the lung and liver tissues, and (e) promoted the survival rate at 18 hr to twofold compared with the CLP alone group. The current study underlined the inhibition of plasma NO and IL-1beta as well as aortic O(2)(-) production and the reduction of PMN infiltration may lead to the amelioration of MODS, which may contribute to the beneficial effect of antioxidants (e.g. melatonin in this study) in conscious rats with peritonitis-induced lethality. Thus, the antioxidant could be a novel agent for the treatment of septic animals or patients in the early stage.

Therapeutic effects of hypertonic saline on peritonitis-induced septic shock with multiple organ dysfunction syndrome in rats

OBJECTIVE

Significant mortality in patients with sepsis results from the development of multiple organ dysfunction syndrome. Small-volume resuscitation with 7.5% NaCl hypertonic saline has been proposed to restore physiologic hemodynamics in hemorrhagic shock. Therefore, we hypothesized that hypertonic saline resuscitation could alleviate the development of multiple organ dysfunction syndrome in sepsis induced by cecal ligation and puncture.

DESIGN

Randomized, prospective animal experiment.

SETTING

Academic research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

The animals were randomly allocated to one of four groups: 1) sham operation (0.9% NaCl, 4 mL/kg intravenously, at 3 hrs after laparotomy); 2) sham operation plus hypertonic saline (7.5% NaCl, 4 mL/kg intravenously, at 3 hrs after laparotomy); 3) cecal ligation and puncture (0.9% NaCl, 4 mL/kg intravenously, at 3 hrs after cecal ligation and puncture); and 4) cecal ligation and puncture plus hypertonic saline (7.5% NaCl, 4 mL/kg intravenously, at 3 hrs after cecal ligation and puncture).

MEASUREMENTS AND MAIN RESULTS

Cecal ligation and puncture for 18 hrs was associated with circulatory failure (i.e., hypotension and vascular hyporeactivity to norepinephrine), multiple organ dysfunction syndrome (examined by biochemical variables and histologic studies), and 18-hr mortality. Hypertonic saline not only ameliorated the deterioration of hemodynamic changes but also attenuated neutrophil infiltration in the lung and the liver of septic animals. Hypertonic saline increased the survival rate at 9 and 18 hrs compared with the cecal ligation and puncture group. Moreover, hypertonic saline reduced plasma nitric oxide and interleukin-1beta and organ O2-* levels in rats that underwent cecal ligation and puncture.

CONCLUSIONS

Hypertonic saline prevented circulatory failure, alleviated multiple organ dysfunction syndrome, and decreased the mortality rate in animals receiving cecal ligation and puncture. These beneficial effects of hypertonic saline may be attributed to reducing the plasma concentration of nitric oxide and interleukin-1beta as well as the organ O2-* level and decreasing lung neutrophil infiltration and liver necrosis. Our study suggests that hypertonic saline could be a potential and inexpensive therapeutic agent in the early sepsis of animals or patients.

Antithrombin inhibits lipopolysaccharide-induced tumor necrosis factor-alpha production by monocytes in vitro through inhibition of Egr-1 expression

BACKGROUND

Antithrombin (AT) improves the outcome of septic patients with intravascular coagulation. However, the mechanisms underlying the therapeutic benefits of AT are not fully understood. Tumor necrosis factor-alpha (TNF-alpha) plays a critical role in the development of organ failure and intravascular coagulation in sepsis.

AIM

This study aimed to elucidate a molecular mechanism by which AT inhibits TNF-alpha production.

METHODS

Human peripheral monocyte was stimulated by lipopolysaccharide (LPS) and TNF-alpha concentration in media was measured. Levels of phosphorylation of extracellular signal-regulated protein kinases (ERK) 1/2 and early growth response factor-1 (Egr-1) were estimated by western blotting or by electrophoretic mobility shift assay.

RESULTS

Antithrombin (3 U mL(-1)) inhibited TNF-alpha production by monocytes stimulated with LPS. Conversely, chemically modified AT that lacks affinity for heparin did not. AT inhibited the phosphorylation of ERK 1/2 and decreased the expression of Egr-1 in LPS-stimulated monocytes. However, it did not affect the activation of either nuclear factor-kappaB or activator protein-1. Pretreatment with KT5720, a protein kinase A inhibitor, reversed the inhibitory effect of AT on the LPS-induced phosphorylation of ERK1/2. Although 2 U mL(-1) AT slightly inhibited TNF-alpha production by LPS-stimulated monocytes, it significantly inhibited TNF-alpha production in the presence of a low concentration of beraprost, a stable derivative of prostacyclin.

CONCLUSIONS

These observations suggest that AT might inhibit LPS-induced production of TNF-alpha by inhibiting the increase in Egr-1 expression in monocytes via interaction with heparin-like substances expressed on the cell surface.

Alterations in forearm vascular reactivity in patients with septic shock

Patients with septic shock are haemodynamically unstable and suffer from vasodilation. Studying the human forearm vascular bed in patients with septic shock, we tested the hypothesis that the responses to regionally infused endothelium-(in)dependent vasodilators and vasoconstrictors are uniformly impaired. Forearm blood flow (FBF, venous occlusion plethysmography) and brachial arterial pressure were determined to calculate forearm vascular resistance (FVR) in eight consecutive sedated, mechanically ventilated patients with septic shock (APACHE II Score range 21-34, SOFA Score 11-16) and 11 healthy volunteers. Despite increased baseline FBF in patients with septic shock (6.1 (SD 1.5) ml x min(-1) x (100 ml of tissue)(-1) compared to 4.7 (1.4) in volunteers) the significant decreases in FVR seen in response to exogenous nitric oxide (nitroprusside) and acetylcholine did not differ between groups. However, compared to volunteers, mitigation of endogenous nitric oxide production by a low dose of N(G)-methyl-L-arginine acetate (L-NMMA) caused a significant increase (+6.7 mmHg x min x ml(-1)) in septic patients. Regional vasoconstriction in response to phenylephrine (FVR: +9.9 vs +30.7 mmHg x min x ml(-1) in controls) and angiotensin II (FVR: +9.0 vs +67.4 mmHg x min x ml(-1)) was markedly impaired. In contrast, vasopressin, in dosages evoking no vasoconstriction in volunteers, induced a significant increase in FVR in septic patients (+10.0 mmHg x min x ml(-1)). In the forearm of patients with septic shock, vasoconstriction by alpha1- and angiotensin II receptor agonists is selectively impaired, whereas the vasoconstrictor response to vasopressin is exaggerated. These findings exclude a generalised impairment of vasomotor activity in patients with septic shock and provide a rationale for vasopressin administration.

Role of nitric oxide production in anaphylaxis and its relevance for the treatment of anaphylactic hypotension with methylene blue

OBJECTIVE

To review the role of nitric oxide production in anaphylaxis.

DATA SOURCES

We performed MEDLINE searches of the literature. In addition, some references known to the authors but not listed in MEDLINE, such as abstracts and a CD-ROM, were included. Finally, additional clinical details of the cases were provided by one of the authors.

STUDY SELECTION

Primary reports were preferentially selected for inclusion. However, some secondary publications are also cited.

RESULTS

Histamine along with other mediators, such as leukotrienes, tumor necrosis factor, and platelet-activating factor, induce the production of nitric oxide. Nitric oxide can inhibit the release and effects of catecholamines. Sympathetic amines may inhibit production of nitric oxide. Studies in animals have demonstrated the generation of nitric oxide during anaphylaxis. Inhibition of nitric oxide synthase improves survival in an animal model of anaphylaxis. Nitric oxide causes vasodilation indirectly by increasing the activation of guanylyl cyclase, which then causes smooth muscle relaxation by increasing the concentration of smooth muscle cyclic guanosine monophosphate. Methylene blue is an inhibitor of guanylyl cyclase, which increases systemic vascular resistance and reverses shock in animal studies. The previously reported successful treatment with methylene blue of 11 patients with anaphylactic hypotension is reviewed.

CONCLUSION

Nitric oxide plays a significant role in the pathophysiology of anaphylaxis. Treatment with methylene blue should be considered in patients with anaphylactic hypotension that has not responded to other interventions.

Anti-inflammatory activity of c-phycocyanin in lipopolysaccharide-stimulated RAW 264.7 macrophages

C-phycocyanin (C-PC), found in blue green algae, is often used as a dietary nutritional supplement. C-PC has been found to have an anti-inflammatory activity and exert beneficial effect in various diseases. However, little is known about its mechanism of action. Overproduction of nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) plays an important role in the pathogenesis of inflammation. The aim of this study was to determine whether C-PC inhibits production of nitrite, an index of NO, and iNOS expression in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Our results indicated that C-PC significantly inhibited the LPS-induced nitrite production and iNOS protein expression accompanied by an attenuation of tumor necrosis factor-alpha (TNF-alpha) formation but had no effect on interleukin-10 production in macrophages. Furthermore, C-PC also suppressed the activation of nuclear factor-kappaB (NF-kappaB) through preventing degradation of cytosolic IkappaB-alpha in LPS-stimulated RAW 264.7 macrophages. Thus, the inhibitory activity of C-PC on LPS-induced NO release and iNOS expression is probably associated with suppressing TNF-alpha formation and nuclear NF-kappaB activation, which may provide an additional explanation for its anti-inflammatory activity and therapeutic effect.

ELUCIDATION OF TOLL-LIKE RECEPTOR AND ADAPTER PROTEIN SIGNALING IN VASCULAR DYSFUNCTION INDUCED BY GRAM-POSITIVE STAPHYLOCOCCUS AUREUS OR GRAM-NEGATIVE ESCHERICHIA COLI

Pathogens contain specific pathogen-associated molecular patterns, which activate pattern recognition receptors of the innate immune system such as Toll-like receptors (TLRs). Although there is a clear evidence of how macrophages sense pathogens, we know less about such processes in vessels. This is critical to understand because activation of vascular cells and the subsequent induction of inflammatory genes by bacteria are crucial events in the development of septic shock. In the current study we have used genetically modified mice to investigate the role of TLRs, adapter proteins, tumor necrosis factor alpha (TNFalpha), and nitric oxide synthase II (NOSII) in vascular dysfunction induced by Gram-positive (Staphylococcus aureus) or Gram-negative (Escherichia coli) bacteria. Our data show that Gram-positive S. aureus or Gram-negative E. coli causes vascular dysfunction via the induction of NOSII. For S. aureus, this process requires TLR2, TLR6, myeloid differentiation factor 88 (MyD88) adapter-like, MyD88, and TNF, but not TLR4 or TLR1. Vascular dysfunction induced by E. coli requires TLR4 but has no requirement for TLR2, TLR1, TLR6, or TNF, and a partial but incomplete requirement of MyD88 and TIR domain-containing adapter inducing interferon-beta. Staphylococcus aureus induced NOSII protein expression in vascular smooth muscle cells but not in macrophages, whereas E. coli induced NOSII in both cell types. Our data are the first to establish the definitive roles of specific TLRs in the sensing of Gram-positive and Gram-negative bacteria by vessels and demonstrate that macrophages and blood vessels may differ in their response to pathogens.

Protective effect of baicalein against endotoxic shock in rats in vivo and in vitro

Dried roots of Scutellaria baicalensis Georgi (Huang qin) are widely used in traditional Chinese medicine. Baicalein is a major bioactive flavonoid component of H. qin that shows a wide range of biological activities, including antioxidant and anti-inflammatory actions. We evaluated therapeutic effects and possible mechanisms of action of baicalein on circulatory failure and vascular dysfunction during sepsis induced by lipopolysaccharide (LPS; 10 mg/kg, i.v.) in anesthetized rats. Treatment of the rats with baicalein (20 mg/kg, i.v.) significantly attenuated the deleterious hemodynamic changes of hypotension and tachycardia caused by LPS and significantly inhibited the elevation of plasma tumor necrosis factor alpha (TNF-alpha). Baicalein also decreased levels of inducible nitric oxide synthase (iNOS) and the overproduction of NO and superoxide anions caused by LPS. It also increased the survival rate of ICR mice (25-30 g) challenged by LPS (60 mg/kg). Moreover, infiltration of neutrophils into the liver and lungs of rats 6h after treatment with LPS was also reduced by baicalein. To investigate the mechanism of action of baicalein on sepsis, RAW 264.7 cells were used as a model. Baicalein inhibited iNOS protein production, and suppressed LPS-induced degradation of IkappaBalpha, the formation of a nuclear factor kappa B (NF-kappaB)-DNA complex and NF-kappaB-dependent reporter gene expression. Thus, the therapeutic effects of baicalein were associated with reductions in TNF-alpha and superoxide anion levels during sepsis. The inhibitory effects of baicalein on iNOS production may be mediated by inhibition of the activation of NF-kappaB. Baicalein may thus prove a potential agent against endotoxemia.

Beneficial effects of LK-4, an analog of dextromethorphan on lipopolysaccharide-induced sepsis in rats

Dextromethorphan (DM), an anti-tussive agent, has been claimed to have anti-inflammatory and immunomodulatory effects in vitro. In our preliminary screening test, LK-4, an analog of DM, can afford more protection against circulatory failure induced by LPS than that of DM. Thus, the aim of this study was to evaluate the effects of LK-4 on sepsis induced by intravenous (i.v.) administration of lipopolysaccharide (LPS; 10 mg/kg) in anesthetized Wistar rats and survival rate by intraperitoneal administration of LPS (70 mg/kg) in conscious ICR mice. Results demonstrated that posttreatment with LK-4 (3 and 5 mg/kg, i.v.) significantly attenuated the deleterious hemodynamic changes (e.g., hypotension and tachycardia) in rats treated with LPS. Meanwhile, LK-4 (3 mg/kg) significantly inhibited the elevation of plasma tumor necrosis factor-alpha, as well as values of GOT and GPT, and BUN and creatinine caused by LPS. The induction of inducible NO synthase and the overproduction of NO and superoxide anions by LPS were also reduced by LK-4. Moreover, infiltration of neutrophils into the lungs and liver of rats 8 h after treatment with LPS was also reduced by LK-4. Furthermore, LK-4 increased the survival rate of mice insulted by toxic dose of LPS. In conclusion, the beneficial effects of LK-4 on LPS-induced sepsis result from its anti-inflammatory and anti-oxidant effects. Thus, LK-4 can be potentially used as a therapeutic agent for sepsis in the future.

Nitric oxide synthases are involved in the modulation of cardiovascular adaptation in hemorrhaged rats

AIM

Nitric oxide has been implicated in the cardiovascular adaptation to hemorrhagic shock. Our aim was to study the potential role of nitric oxide synthases (NOS) in the cardiovascular response in hemorrhagic hypotension produced experimentally in anesthetized rats.

METHODS

Groups of animals (n = 14, per group): (a) normotensive; (b) hypovolemic (20% blood loss); (c) normotensive and pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME); (d) hypovolemic and pretreatment with L-NAME.

RESULTS

L-NAME restored the hypotension induced by hemorrhage. Blood loss decreased heart rate in the first stage increasing at 60 and 120 min. L-NAME blunted this effect. Right atria and left ventricle histochemical NOS activities increased at 60 and 120 min (atria 8% and 24%, respectively; ventricle 21% and 45%, respectively). This activity increased 17% in smooth muscle at 120 min. Heart endothelial NOS protein levels increased in heart at 60 min being attenuated at 120 min. Inducible NOS protein levels raised significantly in right atria, left ventricle and aorta at 120 min.

CONCLUSION

Hemorrhagic shock induced a time-dependent and specific NOS activation modulating cardiovascular function. The inhibition of nitric oxide system appears to prevent the acceleration of heart rate during late phases after acute hypovolemic state induced by blood loss.

Cloricromene, a coumarine derivative, reduced the development of periodontitis in rats

Recent studies have demonstrated that cloricromene, a coumarin derivative, exerts protective effects in models of inflammation and shock. Tumour necrosis factor plays a pivotal role in the induction of genes involved in physiological processes, as well as in the response to inflammation. We investigated the effect of cloricromene in a rat model of periodontitis. Periodontitis was induced in rats by placing a 2/0 braided silk ligature around the lower left first molar. At day 8 the gingivomucosal tissue encircling the mandibular first molar was removed for evaluation of tumour necrosis factor production, neutrophil infiltration, tissue permeability, nitrotyrosine formation, poly (ADP-ribose) polymerase activation, radiography and histology. Ligation significantly induced an increased tumour necrosis factor production, neutrophil infiltration and a positive staining for nitrotyrosine formation and poly (ADP-ribose) polymerase activation. Ligation significantly increased Evans blue extravasation in gingivomucosal tissue and alveolar bone erosion as evaluated by radiography analysis. Intraperitonal injection of cloricromene (10 mg/kg daily for 8 days) significantly decreased all of the parameters of inflammation as described above. This suggests that cloricromene treatment, which reduced tumour necrosis factor production, may be of benefit in the treatment of periodontitis.

Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis

The phosphodiesterase-4 (PDE4) inhibitors may be an important target in the treatment of several inflammatory conditions. The anti-inflammatory effect of PDE4 inhibitors bears similarities with that of steroids, without interfering with the hypophysary-adrenal-axis. We compared the effect of rolipram, a selective PDE4 inhibitor, with steroids on the clinical course of experimental colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). Three groups of rats (n = 20) received TNBS. One group received methylprednisolone from day 7, another group received rolipram from the same day, and control group received no further treatment. On days 14 and 21 after TNBS instillation, sets of 10 rats underwent colonic dialysis to measure eicosanoid release. Colonic lesions were blindly scored, and colons were homogenized for quantification of myeloperoxidase (MPO) activity and collagen content. Concentration of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta1 (TGF-beta1) in colonic tissue was also measured. Both treatments reduced significantly the eicosanoid release and MPO activity. On day 14, both rolipram and methylprednisolone significantly reduced TNF-alpha content, but TGF-beta1 was only inhibited by rolipram. On day 21, lesion scores and collagen content were significantly reduced only in rolipram-treated group. In conclusion, PDE4 inhibition by rolipram markedly ameliorates the course of chronic colitis and it is superior to methylprednisolone in preventing late collagen deposition.

Pulmonary perfusion during lipopolysaccharide (LPS) induced fetal endotoxemia in the preterm fetal sheep

OBJECTIVE

To study endotoxin induced changes in pulmonary blood flow during normoxia and hypoxia and analyzed the role of nitric oxide (NO) and endothelin (ET) in this process.

STUDY DESIGN

Twenty-seven fetal sheep were chronically instrumented at 107+/-1 days (term is 147 days). Experiments were performed 3 days after surgery. Fetuses were randomized into four groups. Group 1: control group (n=5); Group 2: LPS group (n=6) with lipopolysaccharide (LPS) injection at t -60min; Group 3: L-NAME (n=6) with nitro-l-arginine methyl ester (l-NAME) treatment at t -75min; Group 4: l-NAME+LPS group (n=6) with nitro-l-arginine methyl ester (l-NAME) pre-treatment at t -75min and LPS administration at t -60min as described above; Group 5: BQ123+LPS group (n=4) with BQ123 pre-treatment at t -75min and LPS injection at t -60min as described above.

RESULTS

Unlike in control fetuses, there was a marked elevation in pulmonary perfusion in response to LPS induced endotoxemia during normoxia (+112%; p<0.01), which was even further increased during hypoxia (+434%; p<0.001). This increase was partially blocked by BQ123 (p<0.05) and completely abolished by pre-treatment with l-NAME (p<0.001).

CONCLUSION

During fetal endotoxemia, pulmonary perfusion is increased by LPS induced production of nitric oxide. This may have a significant impact in the fetal inflammatory response syndrome, particularly in the inflammation of the fetal lungs observed in response to intrauterine infection.

Inducible nitric oxide synthase mediates cytokine release: the time course in conscious and septic rats

Nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), and interleukin 1-beta (IL-1beta) are postulated to play a key pathophysiologic role during sepsis. In this study, we examined the time course of inducible NO synthase (iNOS) mRNA expression and the plasma TNF-alpha and IL-1beta in lipopolysaccharide (LPS)-treated conscious rats. The hemodynamic pattern in septic shock is more similar to clinical conditions without anesthesia. The data showed that a significant increase in iNOS mRNA levels was found in the spleen, lung, liver, with slight elevation in the heart and kidney at 3 h after LPS administration. However, iNOS mRNA levels were not elevated significantly in all tissues examined at 24 h. In the plasma, TNF-alpha and IL-1beta culminated within 1 h, and reduced gradually to baseline levels in a relatively short period (within 9 h). The results suggest that local NO production by activation of iNOS mRNA expression and cytokine release may contribute to LPS-induced organ dysfunction at various time points.

Dextromethorphan prevents circulatory failure in rats with endotoxemia

Dextromethorphan (DM), an antitussive agent, has been claimed to have anti-inflammatory and immunomodulatory effects in vitro. Thus, the aim of this study was to evaluate the effects of DM on sepsis induced by intravenous (i.v.) administration of lipopolysaccharide (LPS) in anesthetized Wistar rats and by intraperitoneal administration in conscious ICR mice. Results demonstrated that pretreatment with DM (1, 5 and 10 mg/kg, i.v.) significantly attenuated the deleterious hemodynamic changes (e.g., hypotension and tachycardia) in rats treated with LPS. Meanwhile, DM (5 mg/kg) significantly inhibited the elevation of plasma tumor necrosis factor-alpha and interleukin-10 levels, as well as values of GOT and GPT (as an index of liver function), and BUN and creatinine (as an index of renal function) caused by LPS. The induction of inducible NO synthase and the overproduction of NO and superoxide anions by LPS were also reduced by DM. Moreover, infiltration of neutrophils into the lungs and liver of rats 6 h after treatment with LPS was also reduced by DM. In conclusion, the beneficial effects of DM on LPS-induced sepsis result from its anti-inflammatory and antioxidant effects. Thus, DM can possibly be used as a prophylactic agent for sepsis in the future.

Inducible Nitric Oxide Synthase Inhibition Potentiates Multiple Organ Dysfunction Induced by Endotoxin in Conscious Rats

This study was designed to investigate the effects of inducible nitric oxide synthase (iNOS) inhibition with S-methylisothiourea (SMT) and L-N-(1-iminoethyl)-lysine (L-Nil) on the endotoxemia induced by intravenous lipopolysaccharide (LPS, 10 mg/kg) in conscious rats. Arterial pressure (AP), heart rate (HR), WBC, platelets, plasma nitrite/nitrate, tumor necrosis factor alpha (TNF alpha), and biochemical factors were measured for 24 hours after LPS with or without iNOS inhibitors. RT-PCR was employed to determine the iNOS and endothelial NOS (eNOS) mRNA. Pathologic examinations of the liver and heart were performed. SMT and L-Nil improved the systemic hypotension and increased the HR after LPS. These agents attenuated the LPS-induced leukocytopenia and thrombocytopenia and the increase in nitrite/nitrate. However, iNOS inhibition aggravated the LPS-induced changes in TNF alpha, all biochemical factors, and the hepatic and cardiac tissue damage. The iNOS mRNA, but not the eNOS, was reduced. Our results in conscious rats indicate that iNOS inhibition enhances the organ dysfunction and tissue damage in sepsis. The discrepancy may be attributed to the method for evaluating the sepsis and the effects of anesthesia. Further investigation is required to ensure the effects of iNOS inhibition on sepsis before iNOS inhibitors can be applied in clinical cases with sepsis.

Role of sensory neuron in reduction of endotoxin-induced hypotension in rats

OBJECTIVE

We attempted to determine whether activation of the sensory neuron contributes to reduction of endotoxin-induced hypotension by inhibiting tumor necrosis factor (TNF)-alpha production via calcitonin gene-related peptide (CGRP) release in rats.

DESIGN

Prospective, randomized, controlled study.

SETTING

Research laboratory at a university medical center.

SUBJECTS

Wistar rats weighing 220-280 g.

INTERVENTIONS

Mean arterial blood pressure was measured in rats administered endotoxin intravenously. Animals were pretreated with capsazepine (a vanilloid receptor antagonist), CGRP(8-37) (a CGRP receptor antagonist), and indomethacin before endotoxin administration. Levels of CGRP, 6-keto-prostaglandin F1alpha, TNF-alpha, and cytokine-induced neutrophil chemoattractant (CINC) were measured by enzyme immunoassay methods. The concentration of NO2/NO3 was measured using the Griess reagent. Tissue levels of messenger RNA of the inducible form of nitric oxide synthase (iNOS) and TNF-alpha were determined by reverse transcription polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Both lung levels of CGRP and plasma levels of 6-keto-prostaglandin F1alpha were increased after intravenous administration of endotoxin (5 mg/kg), peaking at 90 mins after endotoxin administration. Increases in plasma levels of 6-keto-prostaglandin F1alpha at 90 mins after endotoxin administration (766 +/- 134 pg/mL) were inhibited by pretreatment with capsazepine (373 +/- 44 pg/mL, p < .05), CGRP(8-37) (406 +/- 64 pg/mL, p < .05), and indomethacin (154 +/- 40 pg/mL, p < .05). Although none of the pretreatments affected a series of endotoxin-induced responses, including increases in lung tissue levels of TNF-alpha, CINC, and iNOS and the resultant hypotension in animals given 5 mg/kg endotoxin, such pretreatments enhanced these pathologic responses in animals given a smaller dose of endotoxin (1 mg/kg) to the same extent as those induced by 5 mg/kg of endotoxin, suggesting that shock responses induced by 5 mg/kg endotoxin are maximum responses and activation of sensory neurons in endotoxin-treated rats is essentially a reparative response.

CONCLUSION

Activation of sensory neurons might contribute to reduction of endotoxin-induced hypotension by releasing CGRP, which is capable of promoting endothelial production of prostacyclin.

Absence of host tumor necrosis factor receptor 1 attenuates manifestations of idiopathic pneumonia syndrome

The interaction of TNF-alpha with TNF receptor 1 (TNFR1) activates several signal transduction pathways that lead to apoptosis or NF-kappa B-dependent inflammation and immunity. We hypothesized that host TNFR1 expression contributes to noninfectious lung injury and inflammation commonly observed after bone marrow transplantation (BMT), termed idiopathic pneumonia syndrome (IPS). C57BL/6 TNFR1-sufficient (TNFR1(+/+)) and -deficient (TNFR1(-/-)) mice were total body irradiated with or without cyclophosphamide conditioning and were given bone marrow plus IPS-inducing donor spleen T cells from B10.BR wild-type mice. TNFR1(-/-) recipient mice exhibited improved early post-BMT survival associated with decreased permeability edema. In addition, the low lung compliance measured in anesthetized, ventilated TNFR1(+/+) mice on day 7 after BMT was restored to baseline during TNFR1 deficiency. Importantly, bronchoalveolar lavage fluid (BALF) inflammatory cells from TNFR1(-/-) vs. TNFR1(+/+) mice generated less nitric oxide (.NO) and nitrating species and exhibited suppressed programmed cell death as assessed using flow cytometry. However, cellular infiltration and levels of proinflammatory cytokines and chemokines were generally higher in BALF collected on day 7 after BMT from TNFR1(-/-) compared with TNFR1(+/+) recipient mice. Our results support a major role of host TNFR1 in regulation of .NO production and lung dysfunction after allogeneic BMT.

Urinary trypsin inhibitor reduces LPS-induced hypotension by suppressing tumor necrosis factor-alpha production through inhibition of Egr-1 expression

Although urinary trypsin inhibitor (UTI) has been shown to inhibit tumor necrosis factor (TNF)-alpha- production, the detailed mechanism(s) remains unclear. This study was undertaken to elucidate the molecular mechanism(s) underlying this inhibitory effect in monocytes in vitro and in rats given lipopolysaccharide (LPS). TNF-alpha production by monocytes stimulated with LPS (100 ng/ml) was inhibited by UTI at concentrations higher than 100 U/ml. Expression of early growth response factor-1 (Egr-1) and phosphorylation of extracellular signal-regulated protein kinases 1/2 in monocytes stimulated with LPS were inhibited by UTI. UTI (50,000 U/kg i.v.) inhibited LPS (5 mg/kg i.v.)-induced increases in lung tissue levels of Egr-1, TNF-alpha mRNA, and TNF-alpha in rats. UTI inhibited LPS-induced hypotension by inhibiting pulmonary induction of inducible nitric oxide synthase (iNOS). We previously demonstrated that anti-TNF-alpha antibody and aminoguanidine, a selective inhibitor of iNOS, reduced LPS-induced hypotension in this animal model. Furthermore, we also reported that reduction of LPS-induced coagulation abnormalities in rats did not affect inflammatory responses and hypotension in this animal model. Taken together, these observations strongly suggested that UTI inhibited LPS-induced production of TNF-alpha by inhibiting activation of the extracellular signal-regulated protein kinases 1/2-Egr-1 pathway in monocytes, which might at least partly contribute to reduction of hypotension through inhibition of iNOS induction in rats given LPS.

BICUCULLINE METHIODIDE ATTENUATES HEPATIC INJURY AND DECREASES MORTALITY IN SEPTIC RATS: ROLE OF CYTOKINES

Bicuculline methiodide attenuates inflammation by inhibiting the production of proinflammatory cytokines, such as tumor necrosis factor-alpha, and by increasing the production of the anti-inflammatory cytokine interleukin-10, both of which play important roles in the pathogenesis of sepsis. The aim of this study was to examine the effects of bicuculline methiodide on sepsis in the cecal ligation and puncture septic-rat model. Cytokine production was measured by enzyme-linked immunosorbent assay. Oxidative stress was assessed by determining serum lipid peroxidation and nitrite levels. Hepatic injury was evaluated by determining the levels of serum aspartate aminotransferase, alkaline phosphatase, and total bilirubin. Mortality was recorded within 24 h. Bicuculline methiodide potently decreased the production of tumor necrosis factor-alpha and interleukin-1beta but increased interleukin-10 in serum. Bicuculline methiodide significantly decreased serum lipid peroxidation and nitrite levels. Further, bicuculline methiodide attenuated hepatic injury and reduced mortality after cecal ligation and puncture. Therefore, the alteration of cytokine production may be involved in the effects of bicuculline methiodide on hepatic injury and mortality in septic rats.

Therapeutic effect of in vivo transfection of transcription factor decoy to NF-kappaB on septic lung in mice

Nuclear factor-kappaB (NF-kappaB) plays a key role in regulating expression of several genes involved in the pathophysiology of endotoxic shock. We investigated whether in vivo introduction of synthetic double-stranded DNA with high affinity for the NF-kappaB binding site could block expression of genes mediating pulmonary vascular permeation and thereby provide effective therapy for septic lung failure. Endotoxic shock was induced by an intravenous injection of 10 mg/kg Escherichia coli endotoxin in mice. We introduced NF-kappaB decoy oligodeoxynucleotide (ODN) in vivo 1 h after endotoxic shock by using a gene transfer kit. At 10 h, blood samples were collected for measurement of histamine and for blood-gas analysis. Gene and protein expression levels of target molecules were determined by means of Northern and Western blot analyses, respectively. The transpulmonary flux of (125)I-labeled albumin was used as an index of lung vascular permeability. Administration of endotoxin caused marked increases in plasma histamine and gene and protein expressions of histidine decarboxylase, histamine H(1) receptors, and inducible nitric oxide synthase in lung tissues. Elevated lung vascular permeability was also found. Blood-gas analysis showed concurrent decreases in arterial Po(2), Pco(2), and pH. All of these events induced by endotoxin were significantly inhibited by transfection of NF-kappaB decoy ODN but not by its mutated (scrambled) form (used as a control). Our results indicate for the first time the potential usefulness of NF-kappaB decoy ODN for gene therapy of endotoxic shock.

Enhancement of endotoxin-induced vascular hyporeactivity to phenylephrine in the thoracic aortas of Mg-deficient rats ex vivo

Since endotoxin lethality is enhanced by Mg deficiency in animals, we determined whether endotoxin-induced vascular hyporeactivity to phenylephrine (PE) is enhanced in Mg-deficient rats. Normal and Mg-deficient adult male Wistar rats were injected with Escherichia coli 011: B4 lipopolysaccharide (1 or 5 mg/kg, i.p.). Six h later, rings prepared from their thoracic aortas showed severe hyporeactivity to PE. This was more pronounced in the Mg-deficient rats, and was reversed by in vitro treatment with a highly selective inducible nitric oxide (NO) synthase inhibitor, 1400 W, or a highly selective soluble guanylyl cyclase inhibitor, ODQ. However, reversal required high doses of both inhibitors in Mg-deficient rats. Endotoxemia for 6 h was associated with elevated serum interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha levels, and strong TNF receptor mRNA expression in the abdominal aortas, which were significantly greater in the Mg-deficient rats. Treatment of the thoracic aortas, isolated from control and Mg-deficient rats before endotoxic challenge, with IL-1beta or TNF-alpha for 6 h in vitro caused hyporeactivity to PE, but its severity did not differ significantly between the two groups. These results suggest that high serum IL-1beta and TNF-alpha levels, and increased TNF receptor production in the vascular tissue, contribute to vascular hyporeactivity to PE in endotoxemia, and to its enhancement in Mg-deficient rats, via NO/cGMP signaling.

Haemodynamic effects of endothelin receptor antagonist, tezosentan, in tumour necrosis factor-alpha treated anaesthetized rats

Administration of tumour necrosis factor-alpha (TNF-alpha) produces progressive reduction in cardiac output (CO) by affecting preload, afterload and cardiac contractility. We have examined the effect of an endothelin receptor antagonist, tezosentan (1, 3 or 10 mg/kg), on CO, heart rate (HR), blood pressure (BP), mean circulatory filling pressure (P(mcf)), resistance to venous return (RVR), arterial resistance (AR), dP/dt, stroke volume (SV), plasma levels of NO(2)(-)/NO(3)(-), and inducible nitric oxide synthase (iNOS) activity in lungs, ex vivo, following treatment with TNF-alpha (30 microg/kg) in anaesthetized rats. Treatment with TNF-alpha alone resulted in significant reduction in CO (40+/-4%), dP/dt (24+/-2%), P(mcf) (24+/-2%), BP (21+/-3%) and SV (38+/-5%) ( n=6; mean +/- SEM), and significant increases in RVR (38+/-9%) and AR (45+/-6%). There were no significant changes in HR or in plasma levels of NO(2)(-)/NO(3)(-) in animals treated with TNF-alpha but there was a modest but significant increase in iNOS activity. Tezosentan alone did not have any effect on haemodynamics, plasma levels of NO(2)(-)/NO(3)(-) or iNOS activity. Tezosentan at the highest dose abolished the effects of TNF-alpha on dP/dt, AR, and RVR. In animals treated with a combination of TNF-alpha and highest dose of tezosentan CO, P(mcf), BP, and SV were reduced by 28+/-5%, 16+/-3%, 21+/-4%, and 27+/-5%, respectively. Tezosentan was able to inhibit the negative impact of TNF-alpha on AR and dP/dt but not on P(mcf). It is likely that the negative impact of TNF-alpha on CO in tezosentan-treated animals could be entirely attributed to reduction in preload.

Suppression of tumor necrosis factor-alpha and inducible nitric oxide synthase gene expression by THI 52, a new synthetic naphthyl-benzylisoquinoline alkaloid

The effects of THI 52 (1-naphthylethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) on (a) inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) expression in RAW 264.7 cells stimulated by lipopolysaccharide (LPS)/interferon gamma (IFN-gamma), (b) plasma nitrate concentration as well as iNOS protein expression (lung) in vivo in LPS-treated rats, and (c) the restoration of vascular contractility to vasoconstrictor agents in LPS-treated vessels in vitro were investigated. THI 52 concentration-dependently reduced not only nitric oxide (NO) production (IC(50) value, 12.5 microM) but also the expression of TNF-alpha and iNOS mRNA in RAW 264.7 cells. Incubation of rat endothelium-denuded thoracic aorta with LPS (300 ng/mL) in vitro for 8 hr resulted in the suppression of vasoconstrictor effects to phenylephrine (PE), effects that were restored by co-incubation with THI 52. Administration of THI 52 (10 and 20mg/kg, i.p.) 30 min before injection of LPS (10mg/kg, i.p.) resulted in a significant reduction of the expression of iNOS protein in rat lung tissue and in the plasma nitrite/nitrate (NOx) level. Addition of THI 52-treated macrophage-conditioned medium to a TNF-sensitive L929 fibroblast cell line (CCL1) increased cell viability, depending on the concentration of THI 52. Finally, THI 52 inhibited the activation of nuclear factor kappaB (NF-kappaB) by inhibition of IkappaB degradation through the prevention of IkappaB phosphorylation. Collectively, these results strongly suggest that THI 52 suppresses both TNF-alpha and iNOS gene expression by inhibiting NF-kappaB. Thus, THI 52, a new synthetic isoquinoline alkaloid, may be beneficial in inflammatory disorders where the overproduction of NO and TNF-alpha is a matter of concern.

Cytokines down-regulate alpha1-adrenergic receptor expression during endotoxemia

OBJECTIVE

The reduced pressure response to norepinephrine in septic patients has directed our interest to the regulation of alpha1-adrenergic receptors in vitro and in vivo during conditions mimicking acute sepsis.

DESIGN

Prospective animal trial followed by a controlled cell culture study.

SETTING

Laboratory of the Department of Anesthesiology.

SUBJECTS

Male Sprague-Dawley rats weighing 200 to 250 g and a mesangial cell line.

INTERVENTIONS

Experimental endotoxemia was induced in rats with lipopolysaccharide, and blood pressure dose-response studies with norepinephrine were performed. Alpha1-receptor gene expression was determined in various organs by a specific RNase protection assay, and tissue concentrations of the proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha were measured. Rat renal mesangial cells were incubated with these cytokines or with nitric oxide donors to investigate the regulation of alpha1-adrenergic receptors during severe inflammation on a cellular level.

MEASUREMENTS AND MAIN RESULTS

The pressor effect of norepinephrine was markedly diminished during endotoxemia. The animals showed down-regulated mRNA levels of alpha1A-, alpha1B- and alpha1D-receptors in all organs investigated, and the tissue concentrations of interleukin-1beta and tumor necrosis factor-alpha were highly increased during experimental endotoxemia. Incubation of cultured rat renal mesangial cells with the cytokines resulted in diminished alpha -receptor gene expression and [3H]prazosin binding capacity, whereas incubation of the cells with nitric oxide donors did not affect alpha1B-receptor expression. In line, blocking of cytokine-induced nitric oxide synthesis by coincubation of mesangial cells with N(G)-nitro-L-arginine methyl ester did not influence cytokine-induced down-regulation of alpha1B-receptors.

CONCLUSIONS

Our data show that endotoxemia causes a systemic down-regulation of alpha1-receptors on the level of gene expression and suggest that this effect is likely mediated by proinflammatory cytokines in a synergistic but nitric oxide-independent fashion. We propose that this down-regulation of alpha1-adrenergic receptors contributes to the attenuated blood pressure response to norepinephrine and, therefore, to septic circulatory failure in patients.

Cyclooxygenase-2 inhibition attenuates lipopolysaccharide-induced cardiovascular failure

The present study aimed to determine the relevance of cyclooxygenase-2 (COX-2)-derived prostanoids for the adverse effects of lipopolysaccharides (LPSs) on cardiovascular function. For this goal, male Sprague-Dawley rats received a single intravenous dose of LPS (10 mg/kg) and were treated with different cyclooxygenase inhibitors. Injection of LPS caused a marked decrease of systolic arterial pressure, from 128 to 79 mm Hg, and a concomitant increase of heart rate, from 380 to 530 minutes(-1). Both the decrease of systemic arterial pressure and the increase of heart rate induced by LPS were almost absent if the animals also received the COX-2 blocker rofecoxib (20 mg/kg), regardless whether the drug was given 1 hour before or 1 hour after LPS. Although plasma and organ levels of prostanoids were lowered by rofecoxib, the characteristic LPS-induced increases of NO synthase II and COX-2 gene expression, as well as of plasma and tissue nitrate/nitrite concentrations, were not affected by rofecoxib. Although rofecoxib treatment did also not change LPS-induced tissue cytokine concentrations, it markedly improved LPS-induced liver damage, as indicated by the decrease of transaminases. Moreover, the overall well-being of the LPS-injected animals improved on concomitant treatment with the COX-2 inhibitor. Taken together, our data suggest that COX-2-derived prostanoids are major mediators for the detrimental effects of LPS on cardiovascular and organ function.

Tumor necrosis factor-alpha inhibits renin gene expression

Renin, produced in renal juxtaglomerular (JG) cells, is a fundamental regulator of blood pressure. Accumulating evidence suggests that cytokines may directly influence renin production in the JG cells. TNF-alpha, which is one of the key mediators in immunity and inflammation, is known to participate in the control of vascular proliferation and contraction and hence in the pathogenesis of cardiovascular diseases. Thus TNF-alpha may exert its effects on the cardiovascular system through modulation of renal renin synthesis. Therefore we have tested the effect of TNF-alpha on renin transcription in As4.1 cells, which represent transformed mouse JG cells, and in native mouse JG cells in culture. Renin gene expression was also determined in mice lacking the gene for TNF-alpha (TNF-alpha knockout mice). TNF-alpha inhibited renin gene expression via an inhibition of the transcriptional activity, targeting the proximal 4.1 kb of the renin promoter in As4.1 cells. TNF-alpha also attenuated forskolin-stimulated renin gene expression in primary cultures of mouse JG cells. Mice lacking the TNF-alpha gene had almost threefold higher basal renal renin mRNA abundance relative to the control strain. The general physiological regulation of renin expression by salt was not disturbed in TNF-alpha knockout mice. Our data suggest that TNF-alpha inhibits renin gene transcription at the cellular level and thus may act as a modulator of renin synthesis in (physio)pathological situations.

Cardiovascular responses and nitric oxide production in cerebral ischemic rats

We investigated that the role of nitric oxide (NO) on ischemic rats in brain and heart. Ischemia was induced by both common carotid arteries (CCA) occlusion for 24h following reperfusion. Then tissue samples were removed and measured NOx. In brain, NOx was increased by about 40% vs. normal and it was significantly inhibited by aminoguanidine, selective iNOS inhibitor. This result showed that NOx concentration was increased by iNOS. We investigated the role of Ca2+ during ischemia. Nimodipine, L-type calcium channel blocker, didn't inhibit the increases of NOx concentration during ischemia. It suggested that increased NOx was due to calcium-independent NOS. MK-801, which N-methyl-D-aspartate (NMDA) receptor antagonist, didn't significantly prevent the increases of NOx. In heart, ischemia caused NOx decrease and it is inconsistent with NOx increase in brain. Aminoguanidine and nimodipine didnt affect on NOx decrease. But MK-801 more lowered NOx concentration than those of ischemia control group. It seemed that Ca2+ influx in heart partially occurred via NMDA receptor and inhibited by NMDA receptor antagonist. The mean arterial pressure (MAP) in ischemic rats after 24h of CCA occlusion was decreased when compared to normal value, whereas the heart rates (HR) was not different between two groups. Aminoguanidine or MK801 had no effect on MAP or HR, but nimodipine reduced MAP. There was no difference the effects of aminoguanidine, nimodipine, or MK-801, on MAP and HR between normal rats and ischemic rats. In summary, ischemic model caused an increase of NOx concentration, suggesting that this may be produced via iNOS, which is calcium independent in brain. However in heart, ischemia decreased NOx concentration and NMDA receptor was partially involved. The basal MAP was decreased in ischemic rats but HR was not different from normal control, suggesting that increased NOx in brain of ischemic rat may result in the hypotension.

Testicular macrophage modulation of Leydig cell steroidogenesis

This review will highlight recent advances in the study of the immuno-endocrinology of the testis, in particular how macrophage-derived inflammatory mediators affect Leydig cell functions. Both the beneficial and deleterious outcomes resulting from macrophage-Leydig cell interactions are discussed. A brief overview of testicular physiology is provided that discusses the functional and anatomical compartmentalization of the testis into the gamete and endocrine compartments where spermatogenesis and testosterone biosynthesis take place, respectively. The process of steroidogenesis including the activities of the steroidogenic enzymes and the role of steroidogenic acute regulatory protein (StAR) are described. The close physical association between Leydig cells and interstitial testicular macrophages suggests that these cells are functionally related. Under normal physiological and non-inflammatory conditions macrophages play an important role in Leydig cell development. If macrophages are absent from the testicular interstitium, Leydig cells fail to develop normally, which suggest that macrophages provide essential growth and differentiation factors for Leydig cells. In contrast, when macrophages are activated and elaborate inflammatory mediators, Leydig cell steroidogenesis is inhibited. Activated macrophages produce pro-inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor (TNF) that are profoundly inhibitory to Leydig cells and appear to act as transcriptional repressors of steroidogenic enzyme gene expression. Macrophages also produce reactive oxygen species (ROS) such as hydrogen peroxide, which also inhibits Leydig cell functions. ROS appear to act acutely by perturbing Leydig cell mitochondria resulting in the inhibition of StAR protein expression. One important consequence of this immune modulation of Leydig cell function may be manifest behaviorally by switching the affected animal from 'testosterone' behavior, to 'sickness' behavior. Increased interest in immune-endocrine control of reproductive function over the past decade has stimulated research into the molecular and biochemical immunopathophysiology of the reproductive system. As investigations unravel mechanisms underlying reproductive dysfunction caused by inflammation and infection, an understanding of the role that immune-endocrine interactions play in the normal physiology of the reproductive system has emerged.