Role of mitochondrial uncoupling protein 2 in cancer cell resistance to gemcitabine

Cancer cells exhibit an endogenous constitutive oxidative stress higher than that of normal cells, which renders tumours vulnerable to further reactive oxygen species (ROS) production. Mitochondrial uncoupling protein 2 (UCP2) can mitigate oxidative stress by increasing the influx of protons into the mitochondrial matrix and reducing electron leakage and mitochondrial superoxide generation. Here, we demonstrate that chemical uncouplers or UCP2 over-expression strongly decrease mitochondrial superoxide induction by the anticancer drug gemcitabine (GEM) and protect cancer cells from GEM-induced apoptosis. Moreover, we show that GEM IC(50) values well correlate with the endogenous level of UCP2 mRNA, suggesting a critical role for mitochondrial uncoupling in GEM resistance. Interestingly, GEM treatment stimulates UCP2 mRNA expression suggesting that mitochondrial uncoupling could have a role also in the acquired resistance to GEM. Conversely, UCP2 inhibition by genipin or UCP2 mRNA silencing strongly enhances GEM-induced mitochondrial superoxide generation and apoptosis, synergistically inhibiting cancer cell proliferation. These events are significantly reduced by the addition of the radical scavenger N-acetyl-l-cysteine or MnSOD over-expression, demonstrating a critical role of the oxidative stress. Normal primary fibroblasts are much less sensitive to GEM/genipin combination. Our results demonstrate for the first time that UCP2 has a role in cancer cell resistance to GEM supporting the development of an anti-cancer therapy based on UCP2 inhibition associated to GEM treatment.

Green tea polyphenol extract attenuates colon injury induced by experimental colitis

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.

Doppler analysis and placental nitric oxide synthase expression during fetal growth restriction

OBJECTIVE

To assess placental nitric oxide (NO) metabolism related to changes in the uteroplacental circulation during fetal growth restriction (FGR).

METHODS

The resistance index (RI) from the uterine arteries and pulsatility index (PI) from the umbilical artery were determined by Doppler analysis in 15 patients with FGR and 12 healthy controls, before elective cesarean section. Inducible (iNOS) and endothelial (eNOS) NO synthase expression were measured in placental samples. Immunohistochemistry was performed for iNOS location in the placenta.

RESULTS

During FGR, we observed a significant elevation of iNOS when compared with controls. Conversely, eNOS did not differ between the two groups. A negative correlation with eNOS (r = -0.85) and a positive correlation with iNOS (r = 0.91) was found correlating to umbilical PI. The iNOS proteins were reduced in syncytiotrophoblast cells and increased in endothelium in the FGR group compared to the controls.

CONCLUSIONS

During FGR, placental iNOS expression is significantly increased; this increase possibly represents an adaptive physiological mechanism for overcoming a fetoplacental circulation deficiency.

Targeting STAT1 by myricetin and delphinidin provides efficient protection of the heart from ischemia/reperfusion-induced injury

Flavonoids exhibit a variety of beneficial effects in cardiovascular diseases. Although their therapeutic properties have been attributed mainly to their antioxidant action, they have additional protective mechanisms such as inhibition of signal transducer and activator of transcription 1 (STAT1) activation. Here, we have investigated the cardioprotective mechanisms of strong antioxidant flavonoids such as quercetin, myricetin and delphinidin. Although all of them protect the heart from ischemia/reperfusion-injury, myricetin and delphinidin exert a more pronounced protective action than quercetin by their capacity to inhibit STAT1 activation. Biochemical and computer modeling analysis indicated the direct interaction between STAT1 and flavonoids with anti-STAT1 activity.

Protective effects of St. John's wort extract and its component hyperforin against cytokine-induced cytotoxicity in a pancreatic beta-cell line

In both type 1 and type 2 diabetes, increased production of cytokines on autoimmune or metabolic basis is supposed to trigger an inflammatory process leading to dysfunction and death of pancreatic beta-cells. Therefore, anti-inflammatory pharmacological approaches aimed at blocking cytokine signalling pathways and consequent cytotoxicity in beta-cells are highly advisable. Based on previous evidence of cytokine antagonistic effects in other cell types, we explored the protective action of Hypericum perforatum (St-John's-wort) extract and its component hyperforin against cytokine-induced functional impairment and apoptosis in the INS-1E beta-cell line, searching for the underlying mechanisms. The results showed that either St-John's-wort extract or hyperforin (at 1-3 microM) prevented cytokine-induced impairment in glucose-stimulated insulin secretion and protected cells against apoptosis in a dose-dependent fashion. Inducible-NO-synthase expression was also potently hindered by the vegetal compounds. Interestingly, cytokine-induced activations of the signal-transducer-and-activator-of-transcription-1 (STAT-1) and the nuclear-factor-kappaB (NF-kappaB) were both down-regulated by SJW extract or HPF (range 0.5-5 microM) when evaluated by electrophoretic-mobility-shift-assay. Other transcription factors (CBF-1, SP-1) were unaffected. Components of SJW extract other than HPF were much less effective in down-regulating cytokine signalling. Significantly, inhibition of cytokine-elicited STAT-1 and NF-kappaB activation was confirmed in isolated rat and human islets incubated in the presence of these vegetal compounds. In conclusion, St-John's-wort extract and hyperforin are non-peptidyl compounds which, at low concentrations, target key mechanisms of cytokine-induced beta-cell injury, thereby improving beta-cell function and survival. Thus, they are potentially valuable for the prevention or limitation of beta-cell loss in diabetes.

Transcription factor expression, RNA synthesis and NADPH-diaphorase across the rat brain and exposure to spatial novelty

The molecular hypothesis of learning and memory processes is based on changes in synaptic weights in neural networks. Aim of this study was to map neural traces of exposure to a spatial novelty were mapped by (i) the transcription factors (TFs) c-fos, c-jun and jun-B using Northern blot and immunocytochemistry (ICC), (ii) RNA synthesis by (3)H-uridine autoradiography and RNA level, (iii) NADPH-diaphorase (NADPH-d) expression by histochemistry. Thus, adult male albino rats were exposed to a Làt-maze and sacrificed at different times. Non-exposed rats served as controls. The latter showed a low constitutive expression of TF, RNA synthesis and NADPH-d across the brain. Northern blots showed a three-fold increase in TFs in exposed versus non-exposed rats in the cerebral cortex. ICC showed in exposed rats several TFs positive cells in the granular and pyramidal layers of the hippocampus and later in all layers of the somatosensory cortex, in the granular layer of the cerebellar cortex. The TF-positivity was stronger in rats exposed for the first time, and was time and NMDA-dependent. Autoradiography for RNA synthesis showed positive cells in the ependyma, hippocampus and cerebellum 6h after testing, and in the somatosensory cortex 24h later. In addition, exposure to novelty induced NADPH-d in the dorsal hippocampus, the caudate-putamen, all the layers of the somatosensory cortex. and the cerebellum. The positivity was absent immediately after exposure, appeared within 2h and disappeared 24h later. A strong neuronal discharge by the convulsant pentylenetetrazol, strongly induced TFs but not din not affect NADPH-d 2h later. Thus, data suggest that the processing of spatial and emotional components of experience activates neural networks across different organization levels of the CNS.

Protective effect of Hypericum perforatum in zymosan-induced multiple organ dysfunction syndrome: Relationship to its inhibitory effect on nitric oxide production and its peroxynitrite scavenging activity

Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Since polyphenolic compounds have high antioxidant potential, we have investigated the effects of H. perforatum extract on the development of multiple organ dysfunction syndrome caused by zymosan (500 mg/kg, administered i.p. as a suspension in saline) in mice. Organ failure and systemic inflammation in rats was assessed 18 h after administration of zymosan and/or H. perforatum extract and monitored for 12 days (for loss of body weight and mortality). Treatment of mice with H. perforatum extract (30 mg/kg i.p., 1 and 6h after zymosan) attenuated the peritoneal exudation and the migration of polymorphonuclear cells caused by zymosan, pulmonary, intestinal and pancreatic injury, and renal dysfunction as well as the increase in myeloperoxidase in the lung and intestine. Immunohistochemical analysis for inducible nitric oxide synthase (iNOS), nitrotyrosine, and poly(ADP-ribose) (PAR) revealed positive staining in lung and intestine tissues obtained from zymosan-injected mice. The degree of staining for nitrotyrosine, iNOS, and PAR was markedly reduced in tissue sections obtained from zymosan-treated mice, which received H. perforatum extract. In conclusion, this study provides evidence, for the first time, that H. perforatum extract attenuates the degree of zymosan-induced multiple organ dysfunction syndrome in mice.

Lipopolysaccharide-induced tumor necrosis factor alpha production and not monocyte human leukocyte antigen-DR expression is correlated with survival in septic trauma patients

Multiple trauma patients have an impaired immune system and thus frequently develop life-threatening septic complications. Because there is an ongoing debate on which are the most predictive immunologic parameters of clinical outcome, we prospectively studied 19 multiple trauma patients with sepsis (mean age, 38.7 +/- 15.8 years; mean Injury Severity Score, 40.6 +/- 11.6) over a period of 14 days. The following parameters were measured daily after admission to the intensive care unit: ex vivo lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-alpha) production, monocyte human leukocyte antigen (HLA)-DR expression, constitutive interleukin (IL) 6 secretion, white blood cell count, and C-reactive protein. In addition, procalcitonin, neopterin, LPS-binding protein, and constitutive TNF-alpha secretion were measured every third day. Immediately after trauma, all patients had significantly lower levels of HLA-DR and ex vivo LPS-stimulated TNF-alpha secretion than healthy controls (n = 7; P < 0.001). On the day after clinical diagnosis of sepsis, before any other parameter differed between survivors (n = 13) and nonsurvivors (n = 6), ex vivo LPS-induced TNF-alpha secretion was significantly lower (P < 0.05) in nonsurvivors than in survivors. We conclude that ex vivo LPS-induced TNF-alpha production is an earlier predictor of clinical outcome in multiple trauma patients with sepsis than monocyte HLA-DR expression, constitutive IL-6 secretion, or any other parameter assessed.

Hypericum perforatum attenuates the development of cerulein-induced acute pancreatitis in mice

A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects of inflammation and shock. Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Because polyphenolic compounds have high antioxidant potential, in this study we evaluated the effect of Hypericum perforatum extract on acute pancreatitis induced by cerulein administration in male CD mice. Intraperitoneal injection of cerulein in mice resulted in a severe, acute pancreatitis, which was characterized by edema, neutrophil infiltration, tissue hemorrhage, and cell necrosis as well as increases in the serum levels of amylase and/or lipase in comparison to sham-treated mice. The infiltration of the pancreatic tissue of these animals with neutrophils (measured as increase in myeloperoxidase activity) was associated with expression of the adhesion molecule ICAM-1. Immunohistochemical examination demonstrated a marked increase in the staining (immunoreactivity) for nitrotyrosine and poly(ADP-ribose) (PAR) in the pancreas of cerulein-treated mice in comparison to sham-treated mice. In contrast, the degree of (a) pancreatic inflammation and tissue injury (histological score), (b) expression of ICAM-1, (c) the staining for nitrotyrosine and PAR, and (d) myeloperoxidase activity was markedly reduced in pancreatic tissue sections obtained from cerulein-treated mice administered Hypericum perforatum extract (30 mg/kg, suspended in 0.2 mL of saline solution, o.s.). Moreover, the treatment with Hypericum perforatum extract significantly reduced the mortality rate at 5 days after cerulein administration. Taken together, our results indicate that Hypericum perforatum extract reduces the development of acute pancreatitis.

Neuroprotection and enhanced recovery with hypericum perforatum extract after experimental spinal cord injury in mice

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants, and/or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects of inflammation. Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely, flavonoids and phenolic acids. Because polyphenolic compounds have high antioxidant potential, in this study, we evaluated the effect of H. perforatum (given at 30 mg . kg (-1)) in an experimental animal model of spinal cord injury, which was induced by the application of vascular clips to the dura via a four-level T5 through T8 laminectomy. The degree of (a) spinal cord inflammation and tissue injury (histological score), (b) nitrotyrosine, (c) poly(adenosine diphosphate-ribose), (d) neutrophils infiltration, and (e) the activation of signal transducer and activator transcription 3 was markedly reduced in spinal cord tissue obtained from H. perforatum extract-treated mice. We have also demonstrated that H. perforatum extract significantly ameliorated the recovery of limb function.

Early nuclear factor–κB activation and inducible nitric oxide synthase expression in injured spinal cord neurons correlating with a diffuse reduction of constitutive nitric oxide synthase activity

Object

Because of toxicity at high concentrations, nitric oxide (NO) contributes to spinal cord injury (SCI) secondary lesions. At low concentrations NO modulates nuclear factor–κB (NF-κB) activation. The authors investigated the activity of neuronal and endothelial NO synthase (nNOS and eNOS) to determine correlations with NF-κB activation and inducible NOS (iNOS) expression soon after SCI.

Methods

In 48 adult male Wistar rats clip-based (50 g/mm2/10 seconds) SCI was induced, and spinal cords were removed at different intervals for the following evaluations: 1) assaying specific activity of nNOS and eNOS; 2) electrophoresis mobility shift assay for activated NF-κB; 3) Northern blotting for iNOS; 4) immunohistochemistry for iNOS and NF-κB; and 5) immunofluorescence for iNOS and NF-κB.

At 15 minutes postinjury, eNOS activity decreased significantly (p < 0.001), as did nNOS activity at 1 hour compared with these levels in control animals and rats killed at 15 and 30 minutes after SCI (p < 0.001). Basal NF-κB levels were variable in controls and at 15 and 30 minutes after injury. One hour postinjury, NF-κB activation was diffuse. Inducible NOS messenger RNA localized diffusely, peaking 6 hours after injury and remaining stable until 24 hours postinjury. Immunohistochemical analysis showed diffuse iNOS and NF-κB staining, especially in neurons inside and around the lesion. Immunofluorescence demonstrated that injured neurons were a source of NF-κB and iNOS soon after injury.

Conclusions

Both nNOS and eNOS exhibited different regulation and roles soon after injury: nNOS correlated with NF-κB activation, whereas eNOS may have participated in vascular changes of the injured spinal cord. Neurons seemed to play a pivotal role in modulating and amplifying the inflammatory response in the injured spinal cord.

Epigallocatechin-3-gallate reduces allergen-induced asthma-like reaction in sensitized guinea pigs

In this study, we have evaluated the effects of the polyphenol epigallocatechin-3-gallate (EGCG), an antioxidant molecule that also enhances constitutive nitric-oxide synthase (NOS) activity, on antigen-induced asthma-like reaction in sensitized guinea pigs. For comparison, we used epicatechin, which shares antioxidant but not NOS-modulating properties with EGCG. Ovalbumin-sensitized guinea pigs placed in a respiratory chamber were challenged with ovalbumin. EGCG (25 mg/kg b.wt.) or epicatechin (25 mg/kg b.wt.) was given i.p. 20 min before ovalbumin challenge. We analyzed latency time for the onset of respiratory abnormalities, cough severity, duration of dyspnea, lung tissue histopathology, mast cell activation (by granule release), leukocyte/eosinophilic infiltration (by major basic protein and myeloperoxidase), oxygen free radical-mediated injury (by nitrotyrosine and 8-hydroxy-2-deoxyguanosine and superoxide dismutase), NOS activity, and bronchial inflammatory response [by tumor necrosis factor-alpha in bronchoalveolar lavage (BAL)]. In the sensitized animals, severe respiratory abnormalities appeared soon after the antigen challenge, accompanied by bronchoconstriction, alveolar inflation, and a marked increase in the assayed parameters of inflammatory cell recruitment, free radical lung injury, and release of proinflammatory molecules in BAL fluid. This was associated with marked depression of constitutive NOS activity. Pretreatment with EGCG, but not epicatechin, significantly reduced all the above parameters and sustained endothelial-type NOS activity. These findings provide evidence that EGCG, probably by modulating NOS activity, can counteract allergic asthma-like reaction in sensitized guinea pigs and suggest its possible future use for the treatment of asthma.

Hypericum perforatum attenuates the development of carrageenan-induced lung injury in mice

Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Since polyphenolic compounds have a high antioxidant potential, in this study we evaluated the effect of H. perforatum in an animal model of acute inflammation, carrageenan-induced pleurisy. We report here that H. perforatum extract (given at 30 mg/kg orally, bolus prior to carrageenan) exerts potent anti-inflammatory effects in an animal model of acute inflammation. Injection of carrageenan into the pleural cavity of mice elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity which contained a large number of neutrophils (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation (as determined by thiobarbituric acid-reactant substance measurement) and increased production of tumor necrosis factor-alpha, (TNF-alpha) and interleukin-1beta (IL-1 beta). All parameters of inflammation were attenuated by H. perforatum extract. Furthermore, carrageenan induced an upregulation of the expression of adhesion molecules ICAM-1, as well as an increase in the amounts of nitrotyrosine and poly(ADP-ribose) (PAR), as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, nitrotyrosine, and PAR was significantly reduced by H. perforatum extract. Additionally, we demonstrate that these inflammatory events were associated with the activation of nuclear factor-kappaB (NF-kappaB) and signal transducer and activator transcription-3 (STAT-31) activation in the lung. NF-kappaB and STAT-3 activation were significantly inhibited by H. perforatum extract treatment. Taken together, our results indicate that prevention of the activation of NF-kappaB and STAT-3 by H. perforatum extract reduces the development of acute inflammation.

Modulation of nitric oxide homeostasis in a mouse model of spinal cord injury

Object

A traumatic spinal cord injury (SCI) immediately induces primary damage, and this is followed by secondary damage characterized by a series of events among which is a progressive extension of cell death within the damaged tissue. In this study, the authors investigated the role of inducible nitric oxide synthase (iNOS) in an experimental model of SCI in mice.

Methods

In wild-type (iNOS+/+) mice, SCI rapidly induced an inflammatory response as shown by nitrotyrosine formation, activation of the nuclear enzyme poly(adenosine diphosphate-ribose) polymerase (PARP), neutrophil infiltration, and spinal cord tissue histopathological changes, indicating the involvement of iNOS-derived massive amounts of NO in SCI.

Conclusions

Genetic inhibition of iNOS, however, resulted in a significant reduction in secondary damage, and this therapeutic efficacy was associated with the prevention of an SCI-induced drop in neuronal and endothelial NOS activity.

Gadd45beta is induced through a CAR-dependent, TNF-independent pathway in murine liver hyperplasia

We previously observed that Gadd45/MyD118, a member of the Gadd45 family of inducible factors, showed the strongest immediate-early induction common to two distinctive proliferation responses of the liver: (1) regeneration induced by surgical partial hepatectomy and (2) hyperplasia induced by the primary mitogen TCPOBOP, a ligand of the constitutive androstane receptor (CAR). Gadd45 is known to be stimulated by nuclear factor (NF) B, which is activated by tumor necrosis factor alpha (TNF) in the early response to partial hepatectomy. We therefore investigated whether TNF and NFB also stimulated Gadd45 as part of the response to CAR ligands, or whether activation occurred by an alternative pathway. TCPOBOP effects were characterized in three mouse genotypes: wild-type, TNFR1-/-, and TNFR1-/-TNFR2-/-. The results showed that TCPOBOP did not activate NFB in any of the mice, but a strong induction of Gadd45 messenger RNA was observed in all three genotypes, where TCPOBOP also induced CyP2b10, a classical target gene of activated CAR, and cyclin D1, a proliferation linked gene. Thus, the absence of TNFR signaling and induction of NFB did not impair CAR-mediated gene induction. Moreover, hepatocyte proliferation was strongly induced, and at significantly higher levels than wild type, in both TNFR1-/- and TNFR1-/-TNFR2-/- mice. Further studies evaluated TCPOBOP-induced gene expression in CAR-/- mice, by microarray expression profiling and Northern blot. The induced changes in gene expression, including the stimulation of Gadd45, were almost completely abolished--hence all were mediated via CAR activation. In conclusion, in the liver, Gadd45 can be induced by a distinctive pathway that requires CAR and is independent of TNF-NFB. The greater induction of proliferation in TNFR-null mice suggests negative cross-talk between the CAR and TNF-NFB controls that regulate proliferation.

Placental expression of nitric oxide synthase during HELLP syndrome: the correlation with maternal-fetal Doppler velocimetry

BACKGROUND

To correlate Doppler waveform of the uterine and umbilical vessels to placental nitric oxide synthase (NOS) expression in pregnant women with HELLP (hemolysis, elevated liver enzymes, low platelets count) syndrome.

METHODS

mRNA expression of inducible NOS (iNOS) and endothelial NOS (eNOS) was assessed, after cesarean section, in placental samples from 10 women affected by HELLP syndrome and 10 controls. Pulsatility indices on Doppler waveform analysis from uterine and umbilical arteries were measured.

RESULTS

iNOS expression was significantly lower in placenta from women with HELLP syndrome than controls. When comparing the results with Doppler flow measurements, we found a negative correlation between umbilical pulsatility index and eNOS expression (r = -0.91) and a positive correlation with iNOS expression (r = 0.86).

CONCLUSIONS

The reduced iNOS expression in women with HELLP syndrome may indicate the extreme placental dysfunction that is unable to compensate for the endothelial derangement and related hypertension in spite of trying to improve fetoplacental perfusion and the delivery of nutrients to the fetus.

EFFECTS OF HYPERICUM PERFORATUM EXTRACT IN A RAT MODEL OF ISCHEMIA AND REPERFUSION INJURY

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants, and/or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects ischemia and reperfusion. Hypericum perforatum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Because polyphenolic compounds have high antioxidant potential, in this study we evaluated the effect of H. perforatum extract on splanchnic artery occlusion (SAO) shock-mediated injury. SAO shock was induced in rats by clamping the superior mesenteric artery and the celiac trunk for 45 min. After 1 h of reperfusion, SAO-shocked rats developed a significant fall in mean arterial blood pressure. Treatment of rats with H. perforatum extract (applied at 25 mg/kg 15 min before reperfusion) significantly reduced a significant fall in mean arterial blood pressure and the migration of polymorphonuclear cells caused by SAO-shock. H. perforatum extract also attenuated the ileum injury (histology) as well as the increase in the tissue levels of myeloperoxidase and malondialdehyde caused by SAO shock in the ileum. Immunohistochemical analysis for nitrotyrosine and for poly ADP-ribosylated proteins revealed a positive staining in ileum from SAO-shocked rats. The degree of staining for nitrotyrosine and poly ADP-ribosylated proteins was markedly reduced in tissue sections obtained from SAO-shocked rats that had received H. perforatum extract. Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin and for intercellular adhesion molecule-1 in the vascular endothelial cells. H. perforatum extract treatment markedly reduced the intensity and degree of P-selectin and intercellular adhesion molecule-1 in tissue section from SAO-shocked rats. H. perforatum extract treatment significantly improved survival. In conclusion, this study demonstrates that H. perforatum extract exerts multiple protective effects in splanchnic artery occlusion-reperfusion shock and suggests that H. perforatum extract may be a candidate for consideration as a therapeutic intervention for ischemia-reperfusion injury.

STAT1 as a New Molecular Target of Anti-Inflammatory Treatment

Cyclooxygenase (COX) is widely considered as the molecular target of non-steroid anti-inflammatory drugs (NSAIDs). However, due to the harmful side effect frequently observed following chronic use, the development of new anti-inflammatory agents is the matter of many studies. Signal transducers and activators of transcription (STAT) are a family of nuclear proteins mediating the action of a number of cytokines. Among them, STAT1 plays a critical role in the signal transduction pathway of interferon-gamma (IFN-gamma) and growth hormone. STAT1 cascade is one major signalling pathway converting the IFN-gamma signal into gene expression, such as inducible nitric oxide synthase (iNOS), COX, vascular cell adhesion molecules (VCAM) and intercellular cell adhesion molecules (ICAM), critically involved in different pathologies correlated to the inflammatory process. This review focuses the attention on an alternative approach to the development of novel drugs based on inhibition of STAT1 pathway. In this context, a growing interest has been focused on natural compounds. We have recently reported a several data indicating that green tea extract (GTE), St. John's Wort extract and epigallocatechin-3-gallate (EGCG) exhibit a specific and strong anti-STAT1 activity which is independent of their acclaimed strong anti-oxidant activity. More recently, GTE has been shown to protect heart damage from ischaemia/reperfusion in rats, suggesting that the protective effect of green tea might be correlated to its anti-STAT1 activity. The present review is aimed at providing data that STAT1 may potentially be claimed as a new molecular target of an anti-inflammatory treatment and that among natural compounds there are a number of anti-STAT1 substances.

Green tea polyphenol extract attenuates ischemia/reperfusion injury of the gut

Various studies have clearly demonstrated that green tea catechins possess potent antioxidative properties, and the preventive effects against various oxidative diseases have been reported. The aim of this study was to investigate the effect of green tea extract on the tissue injury caused by ischemia/reperfusion (I/R) of the gut. I/R injury of the intestine was caused by clamping both the superior mesenteric artery and the celiac trunk for 45 min followed by release of the clamp allowing reperfusion for 1 h or 4 h. This procedure results in splanchnic artery occlusion (SAO) shock. Rats subjected to SAO developed a significant fall in mean arterial blood pressure, and only 10% of the animals survived for the entire 4-h reperfusion period. Surviving animals were sacrificed for histological examination and biochemical studies. Rats subjected to SAO displayed a significant increase in tissue myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels, significant increases in plasma tumor necrosis factor (TNF)-alpha levels and marked injury to the distal ileum. Increased immunoreactivity to nitrotyrosine was observed in the ileum of rats subjected to SAO. Staining of sections of the ileum obtained from SAO rats with anti-intercellular adhesion molecule (ICAM-1) antibody and with anti-P-selectin antibody resulted in diffuse staining. Administration of green tea extract (20 and 10 mg kg(-1) i.v.) 15 min prior to the onset of gut reperfusion significantly reduced in a dose-dependent manner the fall in mean arterial blood pressure, the mortality rate, infiltration of the reperfused intestine with polymorphonuclear neutrophils (MPO activity), lipid peroxidation (MDA levels), production of TNF-alpha, and histological evidence of gut injury. Administration of green tea extract also markedly reduced nitrotyrosine formation and the up-regulation of ICAM-1 and P-selectin during reperfusion. In order to clarify that green tea extract might be useful in the therapy of I/R injury, we also investigated the effect of green tea extract (20 mg kg(-1) i.v.) when administered 5 min after the onset of gut reperfusion. Similar to the pretreatment approach, the post-treatment also significantly reduced the gut injury induced by I/R. These results demonstrate that green tea extract significantly reduces I/R injury of the intestine.

Green tea polyphenol extract attenuates lung injury in experimental model of carrageenan-induced pleurisy in mice

Here we investigate the effects of the green tea extract in an animal model of acute inflammation, carrageenan-induced pleurisy. We report here that green tea extract (given at 25 mg/kg i.p. bolus 1 h prior to carrageenan), exerts potent anti-inflammatory effects in an animal model of acute inflammation in vivo.

Injection of carrageenan (2%) into the pleural cavity of mice elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained many neutrophils (PMNs), an infiltration of PMNs in lung tissues and increased production of nitrite/nitrate, tumour necrosis factor alpha. All parameters of inflammation were attenuated by green tea extract treatment. Furthermore, carrageenan induced an up-regulation of the adhesion molecule ICAM-1, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS) formation, as determined by immunohistochemical analysis of lung tissues. Staining for the ICAM-1, nitrotyrosine, and PARS was reduced by green tea extract.

Our results clearly demonstrate that treatment with green tea extract exerts a protective effect and offers a novel therapeutic approach for the management of lung injury.

The variations during the circadian cycle of liver CD1d-unrestricted NK1.1+TCR gamma/delta+ cells lead to successful ageing. Role of metallothionein/IL-6/gp130/PARP-1 interplay in very old mice

NKT cells derive from the thymus and home to the liver. Liver NKT cells can be divided in two groups: 'classical' and 'non-classical'. The first is CD1d-restricted, the second is CD1d-unrestricted. NKT cells (classical and non-classical) co-express T-cell receptor (TCR) and NK-cell marker (NK1.1), display cytotoxicity and produce IFN-gamma under IL-12 stimulation affecting, thereby, Th1 response and innate immunity. NK1.1(+)TCR alpha/beta(+) cells belong to both groups. NK1.1(+)TCR gamma/delta(+) cells belong to the second group. Anyway, both NKT cell subtypes, via IFN-gamma production, protect against viruses and bacteria from early in life. Immune variations as well as zinc rhythmicity during the circadian cycle confer the immune plasticity, which is essential for successful ageing. Liver NK1.1(+)TCR gamma/delta(+) cells, rather than TCR alpha/beta(+), from young and very old mice display 'in vitro' (under IL-12 stimulation) nocturnal peaks in cytotoxicity and IFN-gamma production. The acrophase of liver NK1.1(+)TCR gamma/delta(+) cells is present in young and very old mice, not in old. The interplay among zinc-bound metallothionein (MT)/IL-6/gp130/poly(ADP-ribose) polymerase-1 (PARP-1) may be involved in conferring plasticity to liver NK1.1(+)TCR gamma/delta(+) cells. IL-6, via sub-unit receptor gp130, induces MTmRNA. At night, gene expressions of MT, IL-6, gp130 are lower in very old mice than old and young MT-I transgenic mice (MT-I*). In very old mice, this phenomenon allows limited sequester of intracellular zinc from MT leading to good free zinc ion bioavailability for immune efficiency and zinc-dependent PARP-1 activity. Indeed (1) in vitro, high IL-6 provokes strong accumulation of MT, impaired cytotoxicity and low zinc ion bioavailability in liver NK1.1(+)TCR gamma/delta(+) cells exclusively from old and MT-I* mice. (2) The ratio total/endogen PARP-1 activity is higher in very old than in old and MT-I* mice, suggesting a higher capacity of PARP-1 in base excision DNA-repair in very old age thanks to low zinc-bound MT. Cytotoxicity and IFN-gamma production from liver NK1.1(+)TCR gamma/delta(+) cells are thus preserved leading to successful ageing. In conclusion, MT/IL-6/gp130/PARP-1 interplay may confer plasticity to liver CD1d-unrestricted NK1.1(+)TCR gamma/delta(+) cells, where MT, IL-6, gp130 are the main upstream protagonists, and PARP-1 is the main downstream protagonist in immunosenescence.

Epigallocatechin-3-gallate inhibits STAT-1 activation and protects cardiac myocytes from ischemia/reperfusion-induced apoptosis

We have previously demonstrated that STAT-1 plays a critical role in promoting apoptotic cell death in cardiac myocytes following ischemia/reperfusion (I/R) injury. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has recently been reported to inhibit STAT-1 activity in noncardiac cells. In the present study, we have assessed the protective effects of EGCG and green tea extract (GTE) infusion on both cultures of cardiac myocytes and the isolated rat heart. EGCG reduced STAT-1 phosphorylation and protected cardiac myocytes against I/R-induced apoptotic cell death. Moreover, EGCG reduced the expression of a known STAT-1 pro-apoptotic target gene, Fas receptor. More interestingly, oral administration of GTE as well as EGCG infusion limited the extent of infarct size and attenuated the magnitude of myocyte apoptosis in the isolated rat heart exposed to I/R injury. This reduction cell death was associated with improved hemodynamic recovery and ventricular function in the ischemic/reperfused rat heart. This is the first report to show that consumption of green tea is able to mediate cardioprotection and enhance cardiac function during I/R injury. Because GTE-mediated cardioprotection is achieved, at least in part, through inhibition of STAT-1 activity, we may postulate that a similar action can be implemented in the clinical setting to minimize STAT-1 activation levels in patients with acute coronary artery disease (CAD).

Biochemical Aspects of Nitric Oxide

Nitric oxide (NO), a free radical molecule, produced by NO synthase (NOS) in the body exerts a number of pathophysiological actions due to its chemical reactivity. Low amounts of NO (nM) normally produced by constitutive NOS play a critical role in different physiological events such as vasodilation and neurotransmission. Higher amounts of NO ( micro M) locally and spatially produced by inducible NOS during inflammation act as double-edged sword exerting either beneficial or detrimental effects. Recently, new vision on the biological role of NO has been proposed based on the possible cross-talk between constitutive and inducible NOS. Accordingly, normally produced low amounts of NO may be involved in the regulation of NF-kappaB activation and successively the expression of inducible NOS. Under normal conditions NF-kappaB activation is suppressed by low amounts of NO. Under conditions in which massive amounts of NO produced by inducible NOS act detrimentally, NO-elicited down-regulation of NF-kappaB activation is compromised due to the drop in NO at the early phase of inflammation caused by inactivation of constitutive NOS. Any treatment which counterparts the drop in NO, therefore, may present a new approach either in preventing or in treating inflammatory diseases.

Green tea inhibits human inducible nitric-oxide synthase expression by down-regulating signal transducer and activator of transcription-1alpha activation

Green tea has been reported to show anti-inflammatory properties because of its inhibitory effects on the expression of several pro-inflammatory genes. Because the inducible nitricoxide synthase (iNOS) plays an important role in chronic inflammatory diseases, we have focused our attention on the regulation of iNOS expression by green tea in two different human epithelial cell lines, alveolar A549/8 and colon DLD-1 cells. With the use of electrophoretic mobility shift assays, we found a green tea-mediated down-regulation of the DNA binding activity of the transcription factor signal transducer and activator of transcription-1alpha (STAT-1alpha), but not of nuclear factor-kappaB. This down-regulation of the STAT-1alpha DNA binding was shown to result from reduced tyrosine phosphorylation of the STAT-1alpha protein and not from antioxidative effects of the green tea extract. Green tea extract inhibited human iNOS expression in a concentration-dependent manner, quantified in terms of iNOS mRNA, iNOS protein, and nitric oxide production in both cell lines. This inhibitory effect of green tea resulted from transcriptional inhibition as shown in reporter gene experiments. These data suggest that green tea extracts may be promising at least as an auxiliary anti-inflammatory principle in chronic inflammatory diseases.

Anti-inflammatory actions of St. John's wort: inhibition of human inducible nitric-oxide synthase expression by down-regulating signal transducer and activator of transcription-1alpha (STAT-1alpha) activation

St. John's wort (SJW) has been described to show anti-inflammatory properties due to its inhibitory effects on the expression of pro-inflammatory genes like cyclooxygenase-2, interleukin-6, and inducible nitric-oxide synthase (iNOS). Since iNOS plays a critical role in chronic inflammatory diseases, we have focused our attention on the regulation of iNOS expression by SJW in two different human epithelial cell lines, alveolar A549/8 and colon DLD-1 cells. SJW extract concentration dependently inhibited human iNOS expression evaluated by measuring the amounts of iNOS mRNA, iNOS protein, and NO production in both cell lines. This inhibitory effect resulted from transcriptional inhibition as shown in reporter gene experiments. With electrophoretic mobility shift experiments, we found a SJW-mediated down-regulation of the DNA binding activity of the transcription factor signal transducer and activator of transcription-1alpha (STAT-1alpha), but not of nuclear factor-kappaB. This down-regulation of the STAT-1alpha DNA binding was shown to result from reduced tyrosine phosphorylation of the STAT-1alpha protein. The diminished STAT-1alpha tyrosine phosphorylation resulted from SJW-mediated reduction of Janus kinase 2 activity. These data suggest that extracts from SJW may be a promising anti-inflammatory principle in chronic inflammatory diseases.