PD1/PD-L1 immune checkpoint as a potential target for preventing brain tumor progression

Programmed death-1 (PD-1) is a cell surface receptor that functions as a T cell checkpoint and plays a central role in regulating T cell collapse. The binding of PD-1 to its ligand programmed death-ligand 1 (PD-L1) activates downstream signaling pathways and inhibits T cell activation in the perspective of immune system mechanism and regulation in tumor progression. It is well reported that tumors adopt certain immune-checkpoint pathways as a mechanism of resistance against immune cells such as T cells that are specific for tumor antigens. Indeed, the PD-1/PD-L1 pathway controls the induction and maintenance of immune tolerance within the tumor microenvironment. Thus, the PD-1/PD-L1 checkpoint regulation appears to be of extreme importance as well as the immunotherapy targeting that via and the using of PD-1/PD-L1 inhibitors that have changed the scenario of brain cancer treatment and survival. Here, we review the mechanism of action of PD-1 and PD-L1, the PD/PDL-1 signaling pathway involved in the progression of brain tumors, and its application as cancer immunotherapy counteracting tumor escape in central nervous system.

Protective effect of sodium propionate in Aβ1-42 -induced neurotoxicity and spinal cord trauma

Sodium propionate (SP) is one of the main short chain fatty acids (SCFA) that can be produced naturally through host metabolic pathways. SP have been documented and include the reduction of pro-inflammatory mediators in an in vivo model of colitis. The aim of this study is to evaluate the neuroprotective effects of SP in reducing inflammatory process associated to neurological disorders. We performed both in vitro model of Alzheimer's disease, induced by oligomeric Aβ_1-42 stimulation, and in in vivo model of spinal cord injury (SCI) in which neuroinflammation plays a crucial role. For in vitro model, the human neuroblastoma SH-SY5Y cell line was first differentiated with retinoic acid (100 μM) for 24 h and then stimulated by oligomeric Aβ_1-42 (1 μg/ml) and treated with SP at 0.1- 1-10 μM concentrations for another 24 h. Instead, the in vivo model of SCI was induced by extradural compression of the spinal cord at T6-T8 levels, and animals were treated with SP (10-30-100 mg/kg o.s) 1 and 6 h after SCI. Our results demonstrated that both in in vitro neuroinflammatory model and in vivo model of SCI the treatment with SP significantly reduced NF-κB nuclear translocation and IκBα degradation, as well as decreases COX-2 and iNOS expressions evaluated by Western blot analysis. Moreover, we showed that SP treatment significantly ameliorated histopathology changes and improved motor recovery in a dose-dependent manner. In conclusion, our results demonstrated that SP possesses neuroprotective effects, suggesting it could represent a target for therapeutic intervention in neuroinflammatory disorders.

Sodium Butyrate Exerts Neuroprotective Effects in Spinal Cord Injury

Sodium butyrate (SB) is a dietary microbial fermentation product and serves as an important neuromodulator in the central nervous system. Recent experimental evidence has suggested potential therapeutic applications for butyrate, including its utility in treating metabolic and inflammatory diseases. The aim of the present study was to evaluate the potential beneficial effects of SB in a mouse model of spinal cord injury (SCI) and its possible mechanism of action. SCI was induced by extradural compression for 1 min of the spinal cord at the T6-7 level using an aneurysm clip, and SB (10-30-100 mg/kg) was administered by oral gavage 1 and 6 h after SCI. For locomotor activity, study mice were treated with SB once daily for 10 days. Morphological examination was performed by light microscopy through hematoxylin-eosin (H&E) staining. In addition, NF-κB, IκB-α, COX-2, and iNOS expressions were assayed by western blot analysis and IL-1β and TNF-α levels by immunohistochemistry analysis. The results showed that SB treatment significantly ameliorated histopathology changes and improved recovery of motor function changes in spinal cord injury in a dose-dependent manner. Moreover, we demonstrated that SB modulated the NF-κB pathway showing a significant reduction in cytokine expression. Thus, this study showed that SB exerts neuroprotective effects anti-inflammatory properties following spinal cord injury suggesting that SB may serve as a potential candidate for future treatment of spinal cord injury.

PPAR-α Modulates the Anti-Inflammatory Effect of Melatonin in the Secondary Events of Spinal Cord Injury

Melatonin is the principal secretory product of the pineal gland, and its role as an immunomodulator is well established. Recent evidence shows that melatonin is a scavenger of oxyradicals and peroxynitrite and reduces the development of inflammation and tissue injury events associated with spinal cord trauma. Previous results suggest that peroxisome proliferator-activated receptor α (PPAR-α), a nuclear receptor protein that functions as a transcription factor activated by fatty acids, plays a role in control of secondary inflammatory process associated with spinal cord injury (SCI).With the aim to characterize the role of PPAR-α in melatonin-mediated anti-inflammatory activity, we tested the efficacy of melatonin (30 mg/kg) in an experimental model of spinal cord trauma, induced in mice, by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy, and comparing mice lacking PPAR-α (PPAR-α KO) with wild-type (WT) mice.The results obtained indicate that melatonin-mediated anti-inflammatory activity is weakened in PPAR-α KO mice, as compared to WT controls. In particular, melatonin was less effective in PPAR-α KO, compared to WT mice, as evaluated by inhibition of the degree of spinal cord inflammation and tissue injury, neutrophil infiltration, pro-inflammatory cytokine expression, nuclear factor κB (NF-κB) activation, and inducible nitric oxide synthase (iNOS) expression. This study indicates that PPAR-α can contribute to the anti-inflammatory activity of melatonin in SCI.

Effect of Aminoguanidine in Ligature-induced Periodontitis in Rats

The role of nitric oxide and reactive oxygen species is well-demonstrated in inflammation. In this study, we evaluated the effect of aminoguanidine, a nitric oxide synthase inhibitor, in a rat model of periodontitis. We induced periodontitis in rats by placing a piece of 2/0 braided silk around the lower left 1st molar. At day 8, the gingivomucosal tissue encircling the mandibular 1st molar was removed for biochemical and histological analysis. Ligation significantly increased inducible nitric oxide synthase activity and expression, and damaged tissue revealed increased neutrophil infiltration, lipid peroxidation, and positive staining for nitrotyrosine formation and poly (ADP-ribose) polymerase activation. Ligation significantly increased Evans blue extravasation in gingivomucosal tissue and alveolar bone destruction. Aminoguanidine (100 mg/kg i.p., daily for 8 days) treatment significantly reduced all these inflammatory parameters, indicating that it protects against the tissue damage associated with periodontitis by reducing nitric oxide production and oxidative stress.

Redox modulation of cellular stress response and lipoxin A4 expression by Hericium Erinaceus in rat brain: relevance to Alzheimer's disease pathogenesis

Background

There has been a recent upsurge of interest in complementary medicine, especially dietary supplements and foods functional in delaying the onset of age-associated neurodegenerative diseases. Mushrooms have long been used in traditional medicine for thousands of years, being now increasingly recognized as antitumor, antioxidant, antiviral, antibacterial and hepatoprotective agent also capable to stimulate host immune responses.

Results

Here we provide evidence of neuroprotective action of Hericium Herinaceus when administered orally to rat. Expression of Lipoxin A4 (LXA4) was measured in different brain regions after oral administration of a biomass Hericium preparation, given for 3 month. LXA4 up-regulation was associated with an increased content of redox sensitive proteins involved in cellular stress response, such as Hsp72, Heme oxygenase −1 and Thioredoxin. In the brain of rats receiving Hericium, maximum induction of LXA4 was observed in cortex, and hippocampus followed by substantia Nigra, striatum and cerebellum. Increasing evidence supports the notion that oxidative stress-driven neuroinflammation is a fundamental cause in neurodegenerative diseases. As prominent intracellular redox system involved in neuroprotection, the vitagene system is emerging as a neurohormetic potential target for novel cytoprotective interventions. Vitagenes encode for cytoprotective heat shock proteins 70, heme oxygenase-1, thioredoxin and Lipoxin A4. Emerging interest is now focussing on molecules capable of activating the vitagene system as novel therapeutic target to minimize deleterious consequences associated with free radical-induced cell damage, such as in neurodegeneration. LXA4 is an emerging endogenous eicosanoid able to promote resolution of inflammation, acting as an endogenous “braking signal” in the inflammatory process. In addition, Hsp system is emerging as key pathway for modulation to prevent neuronal dysfunction, caused by protein misfolding.

Conclusions

Conceivably, activation of LXA4 signaling and modulation of stress responsive vitagene proteins could serve as a potential therapeutic target for AD-related inflammation and neurodegenerative damage.

Thyroid hormone autoantibodies: are they a better marker to detect early thyroid damage in patients with hematologic cancers receiving tyrosine kinase inhibitor or immunoregulatory drug treatments?

BACKGROUND

Unlike cytotoxic agents, novel antineoplastic drugs can variably affect thyroid function and so impair patient outcomes. However, the widely used standard thyroid tests have demonstrated low sensitivity for detecting early thyroid damage that leads to dysfunction of the gland. To find a more reliable thyroid marker, we assessed the presence of antibodies binding thyroid hormones (thAbs) in a cancer population undergoing potentially thyrotoxic treatment.

METHODS

From April 2010 to September 2013, 82 patients with hematologic malignancies treated with tyrosine kinase inhibitors or immunoregulatory drugs were recruited. Healthy volunteers (n = 104) served as control subjects. Thyroid function, autoimmunity tests, thAbs, and thyroid sonography were assessed once during treatment.

RESULTS

Overall, thAb positivity was recorded in 13% of the entire cohort. In most cases, the thAbs were of a single type, with a predominance of T3 immunoglobulin G. More specifically, thAbs were detected in 11 cancer patients; and abnormal levels of thyroid-stimulating hormone, thyroglobulin antibody, and thyroperoxidase antibody were detected in 6 (p = 0.05), 0 (p = 0.0006), and 2 cancer patients (p = 0.001) respectively. Ultrasonographic alterations of the thyroid were observed in 12 cancer patients. In contrast, of the 104 healthy control subjects, only 1 was positive for thAbs (1%).

CONCLUSIONS

We have demonstrated for the first time that thAbs are a reliable marker of early thyroid dysfunction when compared with the widely used standard thyroid tests. A confirmatory prospective trial aiming at evaluating thAbs at various time points during treatment could clarify the incidence and timing of antibody appearance.

Redox modulation of cellular stress response and lipoxin A4 expression by Coriolus versicolor in rat brain: Relevance to Alzheimer's disease pathogenesis

Increasing evidence supports the notion that oxidative stress-driven neuroinflammation is an early pathological feature in neurodegenerative diseases. As a prominent intracellular redox system involved in neuroprotection, the vitagene system is emerging as a potential neurohormetic target for novel cytoprotective interventions. Vitagenes encode for cytoprotective heat shock proteins 70, heme oxygenase-1, thioredoxin and lipoxin A4. Emerging interest is now focusing on molecules capable of activating the vitagene system as novel therapeutic targets to minimize deleterious consequences associated with free radical-induced cell damage, such as in neurodegeneration. Mushroom-derived lipoxin A4 (LXA4) is an emerging endogenous eicosanoid able to promote resolution of inflammation, acting as an endogenous "braking signal" in the inflammatory process. Mushrooms have long been used in traditional medicine for thousands of years, being now increasingly recognized as rich source of polysaccharopeptides endowed with significant antitumor, antioxidant, antiviral, antibacterial and cytoprotective effects, thereby capable of stimulating host immune responses. Here we provide evidence of a neuroprotective action of the Coriolus mushroom when administered orally to rat. Expression of LXA4 was measured in different brain regions after oral administration of a Coriolus biomass preparation, given for 30 days. LXA4 up-regulation was associated with an increased content of redox sensitive proteins involved in cellular stress response, such as Hsp72, heme oxygenase-1 and thioredoxin. In the brain of rats receiving Coriolus, maximum induction of LXA4 was observed in cortex and hippocampus. Hsps induction was associated with no significant changes in IkBα, NFkB and COX-2 brain levels. Conceivably, activation of LXA4 signaling and modulation of stress-responsive vitagene proteins could serve as a potential therapeutic target for AD-related inflammation and neurodegenerative damage.

Ultramicronized palmitoylethanolamide reduces inflammation an a Th1-mediated model of colitis

Inflammatory bowel diseases are idiopathic relapsing disorders characterized by chronic inflammation of the intestinal tract. The aim of the present study was to examine the effect of ultramicronized palmitoylethanolamide (PEAultra), underlining its correlation with PPARα and TLR4; in particular, we aimed at evaluating its anti-inflammatory effect in mice subjected to experimental colitis. Colitis was induced in mice by intracolonic instillation of dinitrobenzene sulfonic acid (DNBS), PEAultra was administered daily intraperitoneally (10 mg/kg) for 4 days. On day 4, animals were sacrificed and tissues were taken for histological and biochemical analysis. Four days after DNBS administration, TNF-α and IL-1β productions were increased in association with colon damage. Neutrophil infiltration, evaluated by MPO activity, in the mucosa was associated with upregulation of ICAM-1 and P-selectin. Immunohistochemistry for nitrotyrosine and PARP showed an intense staining in the inflamed colon. Treatment with PEAultra significantly reduced the appearance of colon damage and the loss of body weight. These effects were associated with a remarkable amelioration in the disruption of the colonic architecture and reduction in colonic MPO activity. PEAultra also reduced the pro-inflammatory cytokine release, the appearance of nitrotyrosine and PARP immunoreactivity as well as the upregulation of ICAM-1 and P-selectin; moreover, pro-MMP-9 and MMP-2 expressions were significantly inhibited in the colon of DNBS-treated mice. Furthermore, we studied PEAultra correlation with PPARα and TLR4, demonstrating that PEAultra inhibited TLR4 pathway through a PPARα independent pathway. Taken together, our results clearly show that this new formulation of PEA may be considered as a possible therapeutic approach against Th1-induced colitis.

n-3 fatty acids: role in neurogenesis and neuroplasticity

Omega-3 polyunsaturated fatty acids (PUFA) are essential unsaturated fatty acids with a double bond (C=C) starting after the third carbon atom from the end of the carbon chain. They are important nutrients but, unfortunately, mammals cannot synthesize them, whereby they must be obtained from food sources or from supplements. Amongst nutritionally important polyunsaturated n-3 fatty acids, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are highly concentrated in the brain and have anti-oxidative stress, anti-inflammatory and antiapoptotic effects. They are involved in many bodily processes and may reportedly lead to neuron protection in neurological diseases. aged or damaged neurons and in Alzheimer's disease. Their effect in cognitive and behavioral functions and in several neurological and psychiatric disorders has been also proven. The dentate gyrus (DG), a sub-region of hippocampus, is implicated in cognition and mood regulation. The hippocampus represents one of the two areas in the mammalian brain in which adult neurogenesis occurs. This process is associated with beneficial effects on cognition, mood and chronic pharmacological treatment. The exposure to n-3 fatty acids enhances adult hippocampal neurogenesis associated with cognitive and behavioral processes, promotes synaptic plasticity by increasing long-term potentiation and modulates synaptic protein expression to stimulate the dendritic arborization and new spines formation. On this basis we review the effect of n-3 fatty acids on adult hippocampal neurogenesis and neuroplasticity. Moreover their possible use as a new therapeutic approach for neurodegenerative diseases is pointed out.

NADPH-oxidase 2 activation promotes opioid-induced antinociceptive tolerance in mice

The analgesic effectiveness of long-term opioid therapies is compromised by the development of antinociceptive tolerance linked to the overt production of peroxynitrite (ONOO(-), PN), the product of the interaction between superoxide (O2(-), SO) and nitric oxide (NO), and to neuroinflammatory processes. We have recently reported that in addition to post-translational nitration and inactivation of mitochondrial manganese superoxide dismutase (MnSOD), activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase holoenzyme (NOX) in the spinal cord is a major source for the overt production of superoxide-derived PN during the development of morphine-induced antinociceptive tolerance. However, the NOX complex involved in these processes is not known. The objective of these studies is to identify a potential role for the NOX2 complex, an enzyme involved in inflammation. Mice lacking the catalytic subunit of NOX2 (Nox2(-/-)) or its regulatory subunit, p47(phox) (p47(phox)(-/-)), developed antinociceptive tolerance similar to wildtype (wt) mice after 3 days of continuous morphine. However, while wt mice continue to develop tolerance by day six, morphine analgesia was restored in both Nox2(-/-) and p47(phox)(-/-) mice. Moreover, the loss of Nox2 or p47 did not affect acute morphine analgesia in naïve mice. In wt mice, antinociceptive tolerance was associated with increased activation of NOX, nitration of MnSOD, and proinflammatory cytokines production in the spinal cord. These events were markedly attenuated in Nox2(-/-) and p47(phox)(-/-) mice and instead, there was enhanced formation of antiinflammatory cytokine (IL4 and IL10) production. These results suggest that NOX2 activity provides a significant source of superoxide-derived PN to undertake post-translational modifications of mitochondrial MnSOD and to engage neuroinflammatory signaling in the spinal cord associated with opioid-induced antinociceptive tolerance. Thus, NOX2 may provide a potential target for adjuvant therapy to protect opioid analgesia.

PBS-1086, a Rel Inhibitor of NF-κB, Ameliorates Collagen-Induced Arthritis in Mice

The family of nuclear factor-kappaB (NF-κB) transcription factors is intimately involved in the regulation of expression of numerous genes in the setting of the inflammatory response. Inflammation, cartilage degradation, cell proliferation, angiogenesis and pannus formation are hallmarks of the pathogenesis of both collagen-induced arthritis (CIA) in rodents and rheumatoid arthritis (RA) in humans. The aim of this study is to investigate the effect of PBS-1086, a ReI inhibitor of NF-κB, on the modulation of the inflammatory response in mice subjected to CIA in comparison to the effect of etanercept. CIA was induced in mice by an intradermal injection of bovine type II collagen (CII) emulsion and complete Freund's adjuvant (CFA) at the base of the tail. On day 21, a second injection of CII in CFA was administered. Mice developed erosive hind paw arthritis when immunised with CII in CFA. Macroscopic clinical evidence of CIA first appeared as peri-articular erythema and oedema in the hind paws. The incidence of CIA was 100% by day 28 in the CII challenged mice and the severity of CIA progressed over a 35-day period with a resorption of bone. The histopathology of CIA included erosion of the cartilage at the joint. Treatment with PBS-1086 starting at the onset of arthritis (day 21) ameliorated the clinical signs at days 21–35 and improved histological status in the joint and paw. In addition, it also reduced the neutrophil infiltration which is a key mediator of RA. In this study, we demonstrate that PBS-1086 exerts an anti-inflammatory effect during chronic inflammation and ameliorates the tissue damage associated with CIA. The anti-inflammatory activities of PBS-1086 are comparable to those of etanercept treatment.

Neuroprotective effects of almond skins in experimental spinal cord injury

BACKGROUND & AIMS

Functional deficits following spinal cord injury (SCI) arise from both mechanical injury and from secondary tissue reactions involving inflammation. Natural almond skins (NS) were tested to evaluate anti-inflammatory effects on an animal model of SCI.

METHODS

SCI was induced by the application of vascular clips to the dura via a four-level T5-T8 laminectomy. In the present study, to elucidate whether the protective effects of NS are related to the total phenolic content, we also investigated the effect of a blanched (BS) almond skins (industrially obtained by removing bran from the nut) in SCI. NS and BS (30 mg/kg respectively) were administered per os, 1 h and 6 h, after SCI.

RESULTS

SCI in mice resulted in severe injury characterized by edema, tissue damage, production of inflammatory mediators and apoptosis (measured by Bax, Bcl-2 and Tunel assay). NS treatment, 1 and 6 h after SCI, reduced all parameters of inflammation as neutrophil infiltration, NF-κB activation, PAR formation, iNOS expression and apoptosis. However, treatment with BS did not exert any protective effect.

CONCLUSIONS

Our results suggest that NS treatment, reducing the development of inflammation and tissue injury, may be useful in the treatment of SCI.

The glucocorticoid-induced TNF receptor family-related protein (GITR) is critical to the development of acute pancreatitis in mice

BACKGROUND AND PURPOSE

Pancreatitis represents a life-threatening inflammatory condition where leucocytes, cytokines and vascular endothelium contribute to the development of the inflammatory disease. The glucocorticoid-induced tumour necrosis factor (TNF) receptor family-related protein (GITR) is a costimulatory molecule for T lymphocytes, modulates innate and adaptive immune system and has been found to participate in a variety of immune responses and inflammatory processes. Our purpose was to verify whether inhibition of GITR triggering results in a better outcome in experimental pancreatitis.

EXPERIMENTAL APPROACH

In male GITR knock-out (GITR(-/-)) and GITR(+/+) mice on Sv129 background, acute pancreatitis was induced after i.p. administration of cerulein. Other experimental groups of GITR(+/+) mice were also treated with different doses of Fc-GITR fusion protein (up to 6.25 µg·mouse⁻¹), given by implanted mini-osmotic pump. Clinical score and pro-inflammatory parameters were evaluated.

KEY RESULTS

A less acute pancreatitis was found in GITR(-/-) mice than in GITR(+/+) mice, with marked differences in oedema, neutrophil infiltration, pancreatic dysfunction and injury. Co-treatment of GITR(+/+) mice with cerulein and Fc-GITR fusion protein (6.25 µg·mouse⁻¹) decreased the inflammatory response and tissue injury, compared with treatment with cerulein alone. Inhibition of GITR triggering was found to modulate activation of nuclear factor κB as well as the production of TNF-α, interleukin-1β, inducible nitric oxide synthase, nitrotyrosine, poly-ADP-ribose, intercellular adhesion molecule-1 and P-selectin.

CONCLUSIONS AND IMPLICATIONS

The GITR-GITR ligand system is crucial to the development of acute pancreatitis in mice. Our results also suggest that the Fc-GITR fusion protein could be useful in the treatment of acute pancreatitis.

Apocynin, a Plant-Derived Drug, Might Be Useful in the Treatment of Myocardial Ischemia Reperfusion Injury in Rat Hearts

Apocynin is a potent and selective inhibitor of the NADPH oxidase-dependent production of ROS by stimulated human PMNs. Apocynin was isolated by activity-guided isolation from Picrorhiza kurroa, and in the years following its discovery it has been used in many laboratories around the world. Reactive oxygen species (ROS) production by activated polymorphonuclear neutrophils (PMNs) plays an important role in many cardiovascular disease states, including myocardial ischemia reperfusion injury. The purpose of this study is to examine the beneficial effects of apocynin on myocardial ischemia reperfusion injury. Myocardial I/R injury was caused by clamping the left anterior descending (LAD) coronary artery for 20 min followed by release of the clamp allowing reperfusion for 1 h. Administration of apocynin i.p. (5mg/kg i.p. 10%DMSO) 15 min after ischemia significantly reduced the: 1) histological evidence of myocardial injury; 2) pro-inflammatory cytokines (TNF-α, IL-1β); 3) adhesion molecules (ICAM-1, P-Selectin); 4) nitrotyrosine formation; 5) NF-kB expression; 6) PAR formation; and 7) apoptosis (Bax, Bcl-2, Fas-L and tunel). Based on these findings we propose that apocynin would be useful in the treatment of various ischemia and reperfusion diseases.

GW0742, a high affinity PPAR-β/δ agonist reduces lung inflammation induced by bleomycin instillation in mice

Peroxisome Proliferator-Activated Receptor β/δ belongs to a family of ligand-activated transcription factors. Recent data have clarified its metabolic roles and enhanced the potential role of this receptor as a pharmacological target. Moreover, although its role in acute inflammation remains unclear, being the nuclear receptor PPAR β/δ widely expressed in many tissues, including the vascular endothelium, we assume that the infiltration of PMNs into tissues, a prominent feature in inflammation, may also be related to PPAR β/δ. Mice subjected to intratracheal instillation of bleomycin (BLEO, 1 mg/kg), a glycopeptide produced by the bacterium Streptomyces verticillus, develop lung inflammation and injury characterized by a significant neutrophil infiltration and tissue oedema. Therefore, the aim of this study is to investigate the effects of GW0742, a synthetic high affinity PPAR β/δ agonist, and its possible role in preventing the advance of inflammatory and apoptotic processes induced by bleomycin, that long-term leads to the appearance of pulmonary fibrosis. Our data showed that GW0742-treatment (0.3 mg/Kg, 10 percent DMSO, i.p.) has therapeutic effects on pulmonary damage, decreasing many inflammatory and apoptotic parameters detected by measurement of: 1) cytokine production; 2) leukocyte accumulation, indirectly measured as decrease of myeloperoxidase (MPO) activity; 3) IkBα degradation and NF-kB nuclear translocation; 4) ERK phosphorylation; 5) stress oxidative by NO formation due to iNOS expression; 6) nitrotyrosine and PAR localization; 7) the degree of apoptosis, evaluated by Bax and Bcl-2 balance, FAS ligand expression and TUNEL staining. Taken together, our results clearly show that GW0742 reduces the lung injury and inflammation due to the intratracheal BLEO--instillation in mice.

Ethyl pyruvate therapy attenuates experimental severe arthritis caused by type II collagen (CII) in the mouse (CIA)

This study tested the hypothesis that ethyl pyruvate (EP), a simple aliphatic ester with anti-inflammatory effects, can reduce type II collagen-induced mouse arthritis (CIA). DBA/1J mice were used for the study, developing erosive hind paw arthritis when immunized with CII in an emulsion in complete Freund?s adjuvant (CFA). The incidence of CIA was 100 percent by day 28 in the CII-challenged mice, and the severity of CIA progressed over a 35-day period with radiographic evaluation revealing focal resorption of bone. The histopathology of CIA included erosion of the cartilage at the joint margins. EP-treatment (40 mg/kg/day i.p.) starting at the onset of arthritis (day 25) ameliorated the clinical signs at days 26-35 and improved histological status in the joint and paw. Immunohistochemical analysis for nitrotyrosine, poly (ADP-ribose) (PAR), inducible nitric oxide synthase (iNOS) revealed a positive staining in inflamed joints from mice subjected to CIA, while no staining was observed for HO-1 and Nrf-2 in the same group. The degree of staining for nitrotyrosine, PAR, iNOS, was significantly reduced in CII-challenged mice treated with the EP. Immuno-positive-staining for HO-1 and Nrf-2 was observed instead, in joints obtained from the EP-treated group. Plasma levels of TNF-α, IL-6 and the joint tissue levels of macrophage inflammatory protein (MIP)-1α and MIP-2 were also significantly reduced by EP treatment. Thirty-five days after immunization, EP-treatment significantly increased plasma levels of IL-10. These data demonstrate that EP treatment exerts an anti-inflammatory effect during chronic inflammation and is able to ameliorate the tissue damage associated with CIA.

New therapeutic strategy for Parkinson's and Alzheimer's disease

The development of potential neuroprotective therapies for neurodegenerative diseases (Parkinson's and Alzheimer's Disease) must be based on understanding their molecular and biochemical pathogenesis. Many potential pathways of neuronal cell death have been implicated in a mouse model of neurodegenerative disease, including excitotoxicity, toxicity from reactive oxygen species (superoxide anion, nitric oxide, hydroxyl radical), apoptosis (caspase-dependent and -independent pathways), necrosis and glial injury. Some agents that act on these pathways may be available for protecting the brain against chronic neurodegenerative conditions like Parkinson's and Alzheimer's disease. Drugs currently used to treat neurological disease and injuries provide temporary relief of symptoms but do not stop or slow the underlying neurodegenerative process. Restorative therapies for Parkinson's Disease are currently focused on cell replacement and administration of growth factors and small-molecule neurotrophic agents. The new experimental drugs, by contrast, target the common, underlying cause of destructive process of brain cell death. For example, p53 inhibitors attack a key protein involved in nerve cell death and represent a new strategy for preserving brain function following sudden injury or chronic disease. Analogues of pifithrin-alpha (PFT), which was shown in previous studies to inhibit p53, were designed, synthesized and tested to see whether they would work against cultured brain cells and animal models of neurodegenerative disease. Moreover, several agents based on the predominant anti-amyloid strategy, targeting amyloid-beta (Aβ) peptide, which aggregates in the plaques that are a hallmark of Alzheimer's disease, would affect disease progression. Researchers are already making great strides in developing a vaccine for this progressive brain disorder. Immunization could offer a way to blunt or even prevent the deadly, memory-robbing disease. Here we review many of potential neuroprotective therapies, and strategies that might be suited to the development of innovative approaches that prevent degeneration and restore function in Parkinson's disease.

The 5-lipoxygenase inhibitor, zileuton, suppresses prostaglandin biosynthesis by inhibition of arachidonic acid release in macrophages

BACKGROUND AND PURPOSE

Zileuton is the only 5-lipoxygenase (5-LOX) inhibitor marketed as a treatment for asthma, and is often utilized as a selective tool to evaluate the role of 5-LOX and leukotrienes. The aim of this study was to investigate the effect of zileuton on prostaglandin (PG) production in vitro and in vivo.

EXPERIMENTAL APPROACH

Peritoneal macrophages activated with lipopolysaccharide (LPS)/interferon γ (LPS/IFNγ), J774 macrophages and human whole blood stimulated with LPS were used as in vitro models and rat carrageenan-induced pleurisy as an in vivo model.

KEY RESULTS

Zileuton suppressed PG biosynthesis by interference with arachidonic acid (AA) release in macrophages. We found that zileuton significantly reduced PGE2 and 6-keto prostaglandin F1α (PGF1α) levels in activated mouse peritoneal macrophages and in J774 macrophages. This effect was not related to 5-LOX inhibition, because it was also observed in macrophages from 5-LOX knockout mice. Notably, zileuton inhibited PGE2 production in LPS-stimulated human whole blood and suppressed PGE2 and 6-keto PGF1α pleural levels in rat carrageenan-induced pleurisy. Interestingly, zileuton failed to inhibit the activity of microsomal PGE2 synthase1 and of cyclooxygenase (COX)-2 and did not affect COX-2 expression. However, zileuton significantly decreased AA release in macrophages accompanied by inhibition of phospholipase A2 translocation to cellular membranes.

CONCLUSIONS AND IMPLICATION

Zileuton inhibited PG production by interfering at the level of AA release. Its mechanism of action, as well as its use as a pharmacological tool, in experimental models of inflammation should be reassessed.

Effect of PD98059, a selective MAPK3/MAPK1 inhibitor, on acute lung injury in mice

The aim of the present study is to evaluate the contribution of mitogen-activated protein kinase 1-3 MAPK3/MAPK1) in a model of acute lung inflammation in mice. Injection of carrageenan into the pleural cavity of mice elicited an acute inflammatory response characterized by: accumulation of fluid containing a large number of neutrophils (PMNs) in the pleural cavity, infiltration of PMNs in lung tissues and subsequent adhesion molecule expression (I-CAM and P-selectin), lipid peroxidation, and increased production of tumour necrosis factor-alpha, (TNF-alpha) and interleukin-1beta (IL-1beta). Furthermore, carrageenan induced lung apoptosis (Bax and Bcl-2 expression) as well as nitrotyrosine formation, NF-kB activation, and pJNK expression, as determined by immunohistochemical analysis of lung tissues and the degree of lung inflammation and tissue injury (histological score). Administration of PD98059, an inhibitor of MAPK3/MAPK1 (10 mg/kg) 1 h after carrageenan caused a reduction in all the parameters of inflammation measured. Thus, based on these findings we propose that inhibitors of the MAPK3/MAPK1 signaling pathways, such as PD98059, may be useful in the treatment of various inflammatory diseases.

Selective adenosine A(2a) receptor agonists reduce the apoptosis in an experimental model of spinal cord trauma

Adenosine is an important regulator of inflammatory mechanisms. Functional studies indicate a protective effect of adenosine A2A receptor agonists in spinal cord injury (SCI). The basic molecular mechanisms accounting for their protective effects from spinal cord injury have to be fully elucidated. The aim of this study is to evaluate in vivo protection by two selective A2A receptor agonists, 2-[p-(2-carboxyethyl)phenylethylamino]-50-ethylcarboxamidoadenosine (CGS 21680, 100 microg/kg) and (4-[3-(6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxytetrahydro-furan-2-yl)-9H-purin-2-yl)prop-2-ynyl] piperidine-1-carboxylic acid methyl ester) (ATL 313, 3 microg/kg) on the degree of apoptosis, in the experimental model of spinal cord injury. Spinal cord trauma was induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. Spinal cord trauma in mice was characterised by edema, neutrophilic infiltration and apoptosis. ATL 313, administered by subcutaneously implanted osmotic minipumps after SCI, clearly reduced motor deficit for up to 19 days after operation. The selective A2A receptor agonists ATL 313 and CGS 21680 administered after SCI, reduced tissue damage, TUNEL staining, cytokine (TNF-alpha) expression, Bax, Fas-L and Caspase-3 expression, Annexin-V staining, while increasing Bcl-2 expression. In conclusion, our results demonstrate that treatment with adenosine A2A receptor agonists prevents the apoptotic process that is an important step of secondary damage after SCI.

Heterogeneous expression of cyclooxygenase-2 and inducible nitric oxide synthase within colorectal tumors: correlation with tumor angiogenesis

BACKGROUND

Recent studies have shown that the cyclooxygenase (COX) and the inducible nitric oxide synthase (iNOS) pathways are involved in the development of tumor angiogenesis in human cancers.

AIMS

To investigate whether a different pattern of COX-2 and iNOS expression/activity exists within different areas of colorectal tumors and to analyze the relationship between these two enzymes and tumor angiogenesis.

METHODS

Microvessel density (MVD) and COX-2, iNOS, vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein expression were evaluated at both the invasive front (IF) and the tumor center (TC) in 46 human colorectal cancer specimens. We also investigated the concentration of PGE2 and NO at the same sites.

RESULTS

COX-2 and iNOS protein expression and activity were significantly higher within the IF than the TC of the tumor specimens. Similarly, MVD and VEGF/VEGFR-2 expression significantly increased from the TC to the IF. Only COX-2 expression was significantly correlated with MVD and VEGF/VEGFR-2 expression at both the TC and the IF.

CONCLUSION

Our study shows a heterogeneous expression of COX-2 and iNOS in colorectal cancer. The up-regulation of COX-2 at the IF parallels an increase in vessel density and VEGF/VEGFR-2 expression, thus supporting the hypothesis that the tumor periphery is the most aggressive portion of a colorectal tumor.

TNF-alpha as a therapeutic target in inflammatory diseases, ischemia-reperfusion injury and trauma

Tumor necrosis factor-alpha (TNF-alpha) is a central regulator of inflammation, and TNF-alpha antagonists may be effective in treating inflammatory disorders in which TNF-alpha plays an important pathogenetic role. Recombinant or modified proteins are an emerging class of therapeutic agents. To date, several recombinant or modified proteins which acts as TNF antagonists have been disclosed. In particular, antibodies that bind to and neutralise TNF have been sought as a means to inhibit TNF activity. Inhibition of TNF has proven to be an effective therapy for patients with rheumatoid arthritis and other forms of inflammatory disease including psoriasis, psoriatic arthritis, and ankylosing spondylitis, inflammatory bowel disease. Additionally, the efficacy of preventing septic shock and AIDS has been questioned as a result of recent research. The currently available therapies include a soluble p75 TNF receptor:Fc construct, etanercept, a chimeric monoclonal antibody, infliximab, and a fully human monoclonal antibody, adalimumab. Certolizumab pegol is a novel TNF inhibitor which is an antigen-binding domain of a humanized TNF antibody coupled to polyethylene glycol (PEG) to increase half-life, and thus is Fc-domain-free. In this review, we discuss briefly the present understanding of TNF-alpha-mediated biology and the current therapies in clinical use, and focus on some of the new therapeutic approaches with small-molecule inhibitors. Moreover, we examine recent reports providing important insights into the understanding of efficacy of thalidomide and its analogs, as TNF-alpha activity inhibitories, especially in therapies of several inflammatory diseases within the nervous system.

Role for endothelial nitric oxide synthase in nitrite-induced protection against renal ischemia-reperfusion injury in mice

Nitrite is protective against renal ischemia/reperfusion injury (IRI); an effect due to its reduction to nitric oxide (NO). In addition to other reductase pathways, endothelial NO synthase (eNOS) may also facilitate nitrite reduction in ischemic environments. We investigated the role of eNOS in sodium nitrite (60 microM, 10 ml/kg applied topically 1 min before reperfusion)-induced protection against renal IRI in C57/BL6 wild-type (WT) and eNOS knockout (eNOS KO) mice subjected to bilateral renal ischemia (30 min) and reperfusion (24h). Markers of renal dysfunction (plasma [creatinine] and [urea]), damage (tubular histology) and inflammation (cell recruitment) were elevated following IRI in WT mice; effects significantly reduced following nitrite treatment. Chemiluminescence analysis of cortical and medullary sections of the kidney demonstrated rapid (within 1 min) distribution of nitrite following application. Whilst IRI caused a significant (albeit substantially reduced compared to WT mice) elevation of markers of renal dysfunction and damage in eNOS KO mice, the beneficial effects of nitrite were absent or reduced, respectively. Moreover, nitrite treatment enhanced renal dysfunction in the form of increased plasma [creatinine] in eNOS KO mice. Confirmation of nitrite reductase activity of eNOS was provided by demonstration of nitrite (100 microM)-derived NO production by kidney homogenates of WT mice, that was significantly reduced by L-NMMA. L-NMMA was without effect using kidney homogenates of eNOS KO mice. These results support a role for eNOS in the pathways activated during renal IRI and also identify eNOS as a nitrite reductase in ischemic conditions; activity which in part underlies the protective effects of nitrite.

Supraspinal inactivation of mitochondrial superoxide dismutase is a source of peroxynitrite in the development of morphine antinociceptive tolerance

Effective treatment of chronic pain with morphine is limited by decreases in the drug's analgesic action with chronic administration (antinociceptive tolerance). Because opioids are mainstays of pain management, restoring their efficacy has great clinical importance. We have recently reported that formation of peroxynitrite (ONOO(-), PN) in the dorsal horn of the spinal cord plays a critical role in the development of morphine antinociceptive tolerance and have further documented that nitration and enzymatic inactivation of mitochondrial superoxide dismutase (MnSOD) at that site provides a source for this nitroxidative species. We now report for the first time that antinociceptive tolerance in mice is also associated with the inactivation of MnSOD at supraspinal sites. Inactivation of MnSOD led to nitroxidative stress as evidenced by increased levels of products of oxidative DNA damage and activation of the nuclear factor poly (ADP-ribose) polymerase in whole brain homogenates. Co-administration of morphine with potent Mn porphyrin-based peroxynitrite scavengers, Mn(III) 5,10,15,20-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP5+) and Mn(III) 5,10,15,20-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP5+) (1) restored the enzymatic activity of MnSOD, (2) attenuated PN-derived nitroxidative stress, and (3) blocked the development of morphine-induced antinociceptive tolerance. The more lipophilic analogue, MnTnHex-2-PyP5+ was able to cross the blood-brain barrier at higher levels than its lipophylic counterpart MnTE-2-PyP5+ and was about 30-fold more efficacious. Collectively, these data suggest that PN-mediated enzymatic inactivation of supraspinal MnSOD provides a source of nitroxidative stress, which in turn contributes to central sensitization associated with the development of morphine antinociceptive tolerance. These results support our general contention that PN-targeted therapeutics may have potential as adjuncts to opiates in pain management.

Maternal adaptation in pregnant hypertensive rats: improvement of vascular and inflammatory variables and oxidative damage in the kidney

BACKGROUND

Mechanisms of normalization of blood pressure in spontaneously hypertensive rats (SHR) during pregnancy were investigated. We hypothesized that at the end of pregnancy (20th day), the modified renal renin-angiotensin system (RAS) plays a pivotal role in this effect associated with reduced inflammation and oxidative damage.

METHODS

We measured blood pressure and heart rate (HR) using a noninvasive tail-cuff method in conscious SHR and Wistar Kyoto rats (WKY). Nonpregnant (-NP) or pregnant (-P) SHR and WKY were used to compare the changes of angiotensin II (ANG II) type 1 (AT1) and type 2 (AT2) receptor expression in the kidney. Renal modification of proinflammatory enzyme expression, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) and their transcription factor nuclear factor-kappaB (NF-kappaB) were also evaluated. Renal malonyldialdehyde (MDA) content and protein nitrotyrosylation, as indicators of oxidative stress, were assessed. Moreover monocyte chemotactic protein-1 (MCP-1) mRNA was determined.

RESULTS

Our findings indicate that the significant reduction of blood pressure induced by pregnancy in the SHR strain could be related to reduced AT1 and increased AT2 expression. We also saw a significant decline in renal NF-kappaB, COX-2, iNOS, and macrophage infiltration, as well as the fall in oxidative stress indicators.

CONCLUSIONS

The increased proinflammatory and oxidative variables, seen in SHR, are strongly ameliorated by pregnancy. In pregnant SHR animals, the adaptive and compensative changes of RAS and inflammation in the kidney seem to contribute to the reduction of blood pressure near term.

Design of a New Line in Treatment of Experimental Rheumatoid Arthritis by Artesunate

This study was aimed to evaluate the therapeutic potency of a new antimalarial drug, artesunate, in an experimental model of rheumatoid arthritis. Collagen-induced arthritis (CIA) was induced in Lewis rats.The intraperitoneally administration of artesunate (ARS) and methotrexate (MTX) were started on day 25 postimmunization and continued until final assessment on day 35. During this period, clinical examination was intermittent. The anticollagen type II antibody (CII Ab) and nitric oxide synthesis were measured. The paws and kness were then removed for histopathology and radiography assay. The biocompatibility of ARS and MTX were assessed using fibrosarcoma cell line. Our results showed that i.p. injection of artesunate to arthritic rats induced a significant reduction in paw edema. This beneficial effect was associated with a significant decrease in anti-CII antibody response compared with untreated rats. Histopathological assessment showed reduced inflammatory cells infiltrate in joints of treated rats, and tissue edema and bone erosion in the paws were markedly reduced following ARS therapy. Moreover, our radiographic results paralleled histological findings. Cytotoxicity analysis of ARS showed greater tolerability compared with MTX. Treatment with ARS significantly diminished nitric oxide formation in treated rats compared with untreated controls. Our findings revealed the therapeutic efficacy of artesunate in experimental rheumatoid arthritis compared with a choice drug (methotrexate). This result may recommend it as a second-line drug in the treatment of rheumatoid arthritis.

Effect of tumour necrosis factor-alpha receptor 1 genetic deletion on carrageenan-induced acute inflammation: a comparison with etanercept

In the present study, we used tumour necrosis factor-alpha receptor 1 knock-out mice (TNF-alphaR1KO) to evaluate an in vivo role of TNF-alphaR1 on the pathogenesis of inflammatory diseases. We used a murine model of carrageenan-induced acute inflammation (pleurisy), a preclinical model of airway inflammation. The data proved that TNF-alphaR1KO were resistant to carrageenan-induced acute inflammation compared with TNF-alpha wild-type mice. TNF-alphaR1KO showed a significant reduction in accumulation of pleural exudate and in the number of inflammatory cells, in lung infiltration of polymorphonuclear leucocytes and lipid peroxidation and showed a decreased production of nitrite/nitrate in pleural exudates. Furthermore, the intensity and degree of the adhesion molecule intercellular adhesion molecule-1 and P-selectin, Fas ligand (FasL), inducible nitric oxide sythase and nitrotyrosine determined by immunohistochemical analysis were reduced markedly in lung tissues from TNF-alphaR1KO at 4 h and 24 h after carrageenan injection. Moreover, TNF-alpha and interleukin-1beta concentrations were reduced in inflamed areas and in pleural exudates from TNF-alphaR1KO. To support the results generated using pleural inflammation, carrageenan-induced paw oedema models were also performed. In order to elucidate whether the observed anti-inflammatory effects were related to the inhibition of TNF-alpha, we also investigated the effect of etanercept, a TNF-alpha soluble receptor construct, on carrageenan-induced pleurisy. The treatment with etanercept (5 mg/kg subcutaneously 2 h before the carrageenan injection) reduces markedly both laboratory and histological signs of carrageenan-induced pleurisy. Our results showed that administration of etanercept resulted in the same outcome as that of deletion of the TNF-alphaR1 receptor, adding a new insight to TNF-alpha as an excellent target by therapeutic applications.

Effects of zileuton and montelukast in mouse experimental spinal cord injury

BACKGROUND AND PURPOSE

5-lipoxygenase (5-LO) is the key enzyme in leukotriene (LT) biosynthesis from arachidonic acid (AA). Here, we examined the role of the 5-LO-product, cysteinyl-LT (Cys-LT), with a 5-LO inhibitor (zileuton) and a Cys-LT, receptor antagonist (montelukast), in the inflammatory response and tissue injury associated with spinal cord injury (SCI).

EXPERIMENTAL APPROACH

SCI was induced in mice by the application of vascular clips to the dura via a two-level T6 to T7 laminectomy for 1 min. Cord inflammation was assessed histologically and by measuring inflammatory mediators (ELISA) and apoptosis by annexin V, TUNEL, Fas ligand staining and Bax and Bcl-2 expression (immunohistochemistry and western blots). Motor function in hindlimbs was assessed by a locomotor rating scale, for 10 days after cord injury.

KEY RESULTS

SCI in mice resulted in tissue damage, oedema, neutrophil infiltration, apoptosis, tumour necrosis-alpha (TNF-alpha) and cyclooxygenase-2 (COX-2) expression, prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4)) production, and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in injured tissue. Treatment of the mice with zileuton or montelukast reduced the spinal cord inflammation and tissue injury, neutrophil infiltration, TNF-alpha, COX-2 and pERK1/2 expression, PGE(2) and LTB(4) production, and apoptosis. In separate experiments, zileuton or montelukast significantly improved the recovery of limb function over 10 days.

CONCLUSIONS AND IMPLICATIONS

Zileuton and montelukast produced a substantial reduction of inflammatory events associated with experimental SCI. Our data underline the important role of 5-LO and Cys-LT in neurotrauma.

Glycogen synthase kinase-3beta inhibition attenuates the development of bleomycin-induced lung injury

Glycogen synthase kinase-3 (GSK-3) is an ubiquitous serine-threonine protein kinase that participates in a multitude of cellular processes and has recently been implicated in the pathophysiology of a number of diseases. The aim of this study is to investigate the effects of TDZD-8, a potent and selective GSK-3beta inhibitor, on the development of lung injury caused by administration of bleomycin (BLM). Mice subjected to intra-tracheal administration of BLM developed significant lung injury characterized by marked neutrophil infiltration and tissue edema. An increase in immunoreactivity to nitrotyrosine, iNOS, TNF-alpha and IL-1beta was also observed in the lungs of BLM-treated mice. In contrast, administration of BLM-treated mice with TDZD-8 (1 mg/kg daily) significantly reduced (I) the degree of lung injury, (II) the increase in staining (immunohistochemistry) for myeloperoxidase (MPO), nitrotyrosine, iNOS, TNF-alpha and IL-1beta and (III) the degree of apoptosis, as evaluated by Bax and Bcl-2 immunoreactivity and TUNEL staining. Taken together, these results clearly demonstrate treatment with the GSK-3beta inhibitor TDZD-8 reduces the development of lung injury and inflammation induced by BLM in mice.

Combination of dexamethasone and etanercept reduces secondary damage in experimental spinal cord trauma

The aim of our study was to evaluate the therapeutic efficacy of combination therapy with etanercept and dexamethasone (DEX) in vivo in experimental murine model of spinal cord trauma, which was induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration, and cytokine production followed by recruitment of other inflammatory cells, production of inflammation mediators, tissue damage, apoptosis and disease. Treatment of the mice with etanercept (1.25 mg/kg) and DEX (0.025 mg/kg) when administered as a combination therapy but not as a single treatment significantly reduced the degree of (1) spinal cord inflammation and tissue injury (histological score), (2) infiltration of neutrophils (MPO evaluation), (3) inducible nitric oxide synthase, nitrotyrosine, and cytokines expression (tumor necrosis factor-alpha and interleukin-1 beta), (4) and apoptosis (Terminal deoxynucleotidyltransferase-mediated UTP end labeling staining, Fas-ligand expression and Bax and Bcl-2 expression). In a separate set of experiments we have also clearly demonstrated that the combination therapy significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results clearly demonstrate for the first time that strategies targeting multiple proinflammatory pathways may be more effective than a single effector molecule for the treatment of spinal cord trauma.

Protective role of PI3-kinase-Akt-eNOS signalling pathway in intestinal injury associated with splanchnic artery occlusion shock

BACKGROUND AND PURPOSE

Endothelial NO synthase (eNOS) is a dynamic enzyme tightly controlled by co- and post-translational lipid modifications, phosphorylation and regulated by protein-protein interactions. Here we have pharmacologically modulated the activation of eNOS, at different post-translational levels, to assess the role of eNOS-derived NO and of these regulatory mechanisms in intestinal injury associated with splanchnic artery occlusion (SAO) shock.

EXPERIMENTAL APPROACH

SAO shock was induced by clamping both the superior mesenteric artery and the celiac trunk for 45 min followed by 30 min of reperfusion. During ischemia, 15 min prior to reperfusion, mice were given geldanamycin, an inhibitor of hsp90 recruitment to eNOS, or LY-294002 an inhibitor of phosphatidylinositol 3-kinase (PI3K), an enzyme that initiates Akt-catalysed phosphorylation of eNOS on Ser1179. After 30 min of reperfusion, samples of ileum were taken for histological examination or for biochemical studies.

KEY RESULTS

Either LY-294002 or geldanamycin reversed the increased activation of eNOS and Akt observed following SAO shock. These molecular effects were mirrored in vivo by an exacerbation of the intestinal damage. Histological damage also correlated with neutrophil infiltration, assessed as myeloperoxidase activity, and with an increased expression of the adhesion proteins: ICAM-I, VCAM, P-selectin and E-selectin.

CONCLUSIONS AND IMPLICATIONS

Overall these results suggest that activation of the Akt pathway in ischemic regions of reperfused ileum is a protective event, triggered in order to protect the intestinal tissue from damage induced by ischaemia/reperfusion through a fine tuning of the endothelial NO pathway.

Molecular mechanisms involved in the reciprocal regulation of cyclooxygenase and nitric oxide synthase enzymes

The nitric oxide (NO) and cyclooxygenase (COX) pathways share a number of similarities. NO is the mediator generated from the NO synthase (NOS) pathway and COX converts arachidonic acid to prostaglandins (PGs), prostacyclin, and thromboxane A2. Two major forms of NOS and COX have been identified to date. The constitutive isoforms of these enzymes play an important role in the regulation of several physiological states. On the other hand, in an inflammatory setting, the inducible isoforms of these enzymes are induced in a variety of cells resulting in the production of large amounts NO and PGs, which play pathological roles in several disease states. An important link between the NOS and COX pathways was made by our group when we demonstrated that NO activates the COX enzymes, an event leading to overt production of PGs, suggesting that COX enzymes represent important endogenous 'receptor' targets for modulating the multifaceted roles of NO. More importantly, mechanistic studies of how NO activates the COX enzymes have been undertaken and additional pathways through which NO modulates PG production unraveled. The purpose of this article is to cover the advances, which have occurred over the years and in particular to summarize experimental data that outline how the discovery that NO modulates PG production has impacted and extended our understanding of these two systems in physiopathological events.