Connecting TNF-alpha signaling pathways to iNOS expression in a mouse model of Alzheimer's disease: relevance for the behavioral and synaptic deficits induced by amyloid beta protein.
ABSTRACT Increased brain deposition of amyloid beta protein (Abeta) and cognitive deficits are classical signals of Alzheimer's disease (AD) that have been highly associated with inflammatory alterations. The present work was designed to determine the correlation between tumor necrosis factor-alpha (TNF-alpha)-related signaling pathways and inducible nitric oxide synthase (iNOS) expression in a mouse model of AD, by means of both in vivo and in vitro approaches. The intracerebroventricular injection of Abeta(1-40) in mice resulted in marked deficits of learning and memory, according to assessment in the water maze paradigm. This cognition impairment seems to be related to synapse dysfunction and glial cell activation. The pharmacological blockage of either TNF-alpha or iNOS reduced the cognitive deficit evoked by Abeta(1-40) in mice. Similar results were obtained in TNF-alpha receptor 1 and iNOS knock-out mice. Abeta(1-40) administration induced an increase in TNF-alpha expression and oxidative alterations in prefrontal cortex and hippocampus. Likewise, Abeta(1-40) led to activation of both JNK (c-Jun-NH2-terminal kinase)/c-Jun and nuclear factor-kappaB, resulting in iNOS upregulation in both brain structures. The anti-TNF-alpha antibody reduced all of the molecular and biochemical alterations promoted by Abeta(1-40). These results provide new insights in mouse models of AD, revealing TNF-alpha and iNOS as central mediators of Abeta action. These pathways might be targeted for AD drug development.
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ABSTRACT: 5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.Molecular Neurobiology 11/2014; · 5.29 Impact Factor
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ABSTRACT: Rheumatoid arthritis (RA) is considered to be, in many respects, an archetypal autoimmune disease that causes activation of pro-inflammatory pathways resulting in joint and systemic inflammation. RA remains a major clinical problem with the development of several new therapies targeted at cytokine inhibition in recent years. In RA, biologic therapies targeted at inhibition of tumor necrosis factor alpha (TNFα) have been shown to reduce joint inflammation, limit erosive change, reduce disability and improve quality of life. The cytokine TNFα has a central role in systemic RA inflammation and has also been shown to have pro-inflammatory effects in the brain. Emerging data suggests there is an important bidirectional communication between the brain and immune system in inflammatory conditions like RA. Recent work has shown how TNF inhibitor therapy in people with RA is protective for Alzheimer's disease. Functional MRI studies to measure brain activation in people with RA to stimulus by finger joint compression, have also shown that those who responded to TNF inhibition showed a significantly greater activation volume in thalamic, limbic, and associative areas of the brain than non-responders. Infections are the main risk of therapies with biologic drugs and infections have been shown to be related to disease flares in RA. Recent basic science data has also emerged suggesting that bacterial components including lipopolysaccharide induce pain by directly activating sensory neurons that modulate inflammation, a previously unsuspected role for the nervous system in host-pathogen interactions. In this review, we discuss the current evidence for neuro-inflammation as an important factor that impacts on disease persistence and pain in RA.Frontiers in Neuroscience 11/2014; 8(357):1-11.
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ABSTRACT: Despite the outbreak in dental science, oral and dental complications in Alzheimer are of the unsolved problems. It is assumed that tumor necrosis factor-α, which is a key factor in Alzheimer, has a relation with periodontal complications in patients with Alzheimer disease. The present study evaluated the effect of chronic periodontitis on serum levels of tumor necrosis factor-α in Alzheimer disease. This case-control study was performed on 80 patients with Alzheimer disease seeking medical care at Nour Hospital, Isfahan, Iran. Eighty patients with Alzheimer disease between 40 and 70 years old attended this study. Forty had chronic periodontitis (case group), and 40 patients had healthy periodontium (control group). Blood sample was taken, and serum levels of tumor necrosis factor-α were measured by means of an ELISA Reader device. Independent T-Test was used to analyze data, and P < 0.05 was considered significant. The mean of tumor necrosis factor-α was 749.1 ng/μL in case group and 286.8 ng/μL in control group. Independent t-test showed that the mean of tumor necrosis factor-α in patients with Alzheimer and periodontitis was approximately three folds higher than the patients only with Alzheimer, and this difference was statistically significant (P < 0.001). According to the results of this study, it seems that there is a difference between serum levels of tumor necrosis factor-α in patient with Alzheimer and chronic periodontitis and patients with Alzheimer disease and healthy periodontium. Tumor necrosis factor-α level in serum may act as a diagnostic marker of periodontal disease in patients with Alzheimer disease.Dental research journal. 11(5):549-552.