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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

New hippocampal neurons are continuously generated in the adult brain. Here, we demonstrate that lipopolysaccharide-induced inflammation, which gives rise to microglia activation in the area where the new neurons are born, strongly impairs basal hippocampal neurogenesis in rats. The increased neurogenesis triggered by a brain insult is also attenuated if it is associated with microglia activation caused by tissue damage or lipopolysaccharide infusion. The impaired neurogenesis in inflammation is restored by systemic administration of minocycline, which inhibits microglia activation. Our data raise the possibility that suppression of hippocampal neurogenesis by activated microglia contributes to cognitive dysfunction in aging, dementia, epilepsy, and other conditions leading to brain inflammation.
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PMID:Inflammation is detrimental for neurogenesis in adult brain. 1458 18

Patients with lupus (SLE) experience progressive cognitive loss without evidence of CNS vascular disease or inflammation. SLE patients produce anti-DNA antibodies that crossreact with NMDA receptors and are capable of mediating excitotoxic death. We now show that mice induced by antigen to express these antibodies have no neuronal damage until breakdown of the blood-brain barrier occurs. Following administration of lipopolysaccharide (LPS) to immunized mice, antibodies gain access to the brain. They bind preferentially to hippocampal neurons and cause neuronal death with resulting cognitive dysfunction and altered hippocampal metabolism on magnetic resonance spectroscopy. Memantine, an NMDA receptor antagonist, given prior to LPS administration, prevents neuronal damage. Thus, systemic immune responses can cause cognitive impairment in the absence of an inflammatory cascade, implicating the immune system in yet another arena of human pathobiology. Furthermore, NMDA receptor antagonists prevent antibody-mediated damage and may constitute a new approach to therapy in SLE.
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PMID:Cognition and immunity; antibody impairs memory. 1530 99

Acute cognitive impairment (i.e., delirium) is common in elderly emergency department patients and frequently results from infections that are unrelated to the central nervous system. Since activation of the peripheral innate immune system induces brain microglia to produce inflammatory cytokines that are responsible for behavioral deficits, we investigated if aging exacerbated neuroinflammation and sickness behavior after peripheral injection of lipopolysaccharide (LPS). Microarray analysis revealed a transcriptional profile indicating the presence of primed or activated microglia and increased inflammation in the aged brain. Furthermore, aged mice had a unique gene expression profile in the brain after an intraperitoneal injection of LPS, and the LPS-induced elevation in the brain inflammatory cytokines and oxidative stress was both exaggerated and prolonged compared with adults. Aged mice were anorectic longer and lost more weight than adults after peripheral LPS administration. Moreover, reductions in both locomotor and social behavior remained 24 h later in aged mice, when adults had fully recovered, and the exaggerated neuroinflammatory response in aged mice was not reliably paralleled by increased circulating cytokines in the periphery. Taken together, these data establish that activation of the peripheral innate immune system leads to exacerbated neuroinflammation in the aged as compared with adult mice. This dysregulated link between the peripheral and central innate immune system is likely to be involved in the severe behavioral deficits that frequently occur in older adults with systemic infections.
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PMID:Exaggerated neuroinflammation and sickness behavior in aged mice following activation of the peripheral innate immune system. 1591 60

Recent studies indicate that chronic inflammation plays a pathogenic role in both the central nervous system (CNS) and periphery in Alzheimer's disease (AD). We have screened for cytokines differentially produced by peripheral blood mononuclear cells (PBMCs) isolated from subjects with mild cognitive impairment (MCI) and mild AD subjects who had progressed from MCI using a commercially available cytokine array. Following determination of expressed cytokines, we quantified levels of the proinflammatory cytokines TNF-alpha, IL-6, and IL-8, and the anti-inflammatory cytokine IL-10 using flow cytometry. We have found a significant increase in the levels of IL-6, IL-8, and IL-10 produced by PBMCs stimulated for 24 h with phytohemagglutinin (PHA) in MCI subjects compared to healthy elderly controls. However, in PBMCs stimulated for 48 h with lipopolysaccharide (LPS), lower TNF-alpha/IL-10, IL-6/IL-10, and IL-8/IL-10 ratios were seen in MCI subjects. There were no differences in plasma levels of IL-8 between aged controls, MCI, and mild AD, and the levels of circulating IL-6 and IL-10 were below detection limits. Our data indicate that changes in cytokine production by PBMCs may be detected early in MCI, and an alteration of the immune response may precede clinical AD.
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PMID:Increased production of inflammatory cytokines in mild cognitive impairment. 1708 1

Neuropsychiatric systemic lupus erythematosus, which often entails cognitive disturbances and memory loss, has become a major complication for lupus patients. Previously, we developed a murine model of neuropsychiatric lupus based on Abs that cross-react with dsDNA and the NMDA receptor (NMDAR). We showed that these murine Abs impair cognition when they access the CNS through a breach in the blood-brain barrier (BBB) triggered by lipopolysaccharide. Because studies show that lupus patients possess anti-NMDAR Abs in their serum and cerebrospinal fluid, we decided to investigate whether these human Abs contribute to cognitive dysfunction. Here, we show that serum with reactivity to DNA and NMDAR extracted from lupus patients elicited cognitive impairment in mice receiving the serum intravenously and given lipopolysaccharide to compromise the BBB integrity. Brain histopathology showed hippocampal neuron damage, and behavioral testing revealed hippocampus-dependent memory impairment. To determine whether anti-NMDAR Abs exist in the brains of systemic lupus erythematosus patients, we eluted IgG from a patient's brain. The IgG bound DNA and NMDAR and caused neuronal apoptosis when injected into mouse brains. We examined four more brains of patients with neuropsychiatric lupus and found that they displayed endogenous IgG colocalizing with anti-NMDAR Abs. Our results indicate that lupus patients have circulating anti-NMDAR Abs capable of causing neuronal damage and memory deficit, if they breach the BBB, and that the Abs exist within patients' brains. Which aspects of neuropsychiatric lupus may be mediated by anti-NMDAR Abs, how often, and in which patients are now important clinical questions.
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PMID:Human lupus autoantibodies against NMDA receptors mediate cognitive impairment. 1717 Jan 37

Inflammation has been argued to play a fundamental role in the pathogenesis of Alzheimer's disease. Mice transgenic for mutant human amyloid precursor protein (APP) develop progressive amyloid deposition, gliosis, and cognitive impairment. Paradoxically, intracranial administration of lipopolysaccharide (LPS) to promote neuroinflammation results in a reduction in amyloid-beta peptide (Abeta) burden concurrent with the inflammatory response. To determine whether microglia mediate Abeta clearance after LPS, we used dexamethasone to inhibit the microglial response. Amyloid precursor protein mice were injected intrahippocampally with either LPS or saline and were allowed to survive for 7 days with or without dexamethasone cotreatment. Brain tissue was then analyzed by immunohistochemistry. Hippocampal Abeta burden was reduced 7 days after LPS injection, and this was prevented by cotreatment with dexamethasone. Markers of microglial activation [CD45, complement receptor 3 (CR3), and macrosialin (CD68)] were increased by LPS, and these increases were attenuated by dexamethasone. Dexamethasone failed to block LPS-induced increases in all microglial markers, and Fcgamma receptors II/III and scavenger receptor A were increased by LPS but were unaffected by dexamethasone cotreatment. These results indicate a complex response by microglia to acute LPS treatment, with only some responses sensitive to steroidal anti-inflammatory drug treatment. Nonetheless, microglial activation was necessary to remove Abeta in this model of neuroinflammation.
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PMID:Microglial activation is required for Abeta clearance after intracranial injection of lipopolysaccharide in APP transgenic mice. 1804 Aug 47

Neonatal exposure to infectious agents may result in long-term neurological disability, and is particularly associated with the subsequent development of motor and cognitive disturbances. Our previous studies have shown that treatment with alpha-phenyl-n-tert-butyl-nitrone (PBN) following exposure to lipopolysaccharide (LPS) reduces LPS-induced brain injury in the neonatal rat. To examine whether PBN has long-lasting protective effects and ameliorates LPS-induced motor and cognitive dysfunction, PBN (100 mg/kg) was administered intraperitoneally 5 min after an LPS (1 mg/kg) intracerebral injection in postnatal day 5 (P5) Sprague-Dawley rat pups. Neurobehavioral tests were carried out from P3 to P21, and brain injury was examined at 24 h and 16 days after LPS injection. Neonatal LPS exposure resulted in hyperactivity from P13 to P17 in the open field task as compared with the control rat. Neurobehavioral deficits that were still observable at P21 included dysfunction in the beam-walking and pole tests, learning and memory deficits in the passive avoidance task, and less anxiety-like response in the elevated plus-maze task. These behavioral findings were matched by LPS-induced axonal injury in the CA1 region of the middle dorsal hippocampus (HP), reduction in the size of the HP and the number of neurons in the CA1 region of the middle dorsal HP, and loss of tyrosine hydroxylase immunoreactivity in neurons in the substantia nigra and ventral tegmental areas. Treatment with PBN provided long-lasting protection against the LPS-induced axonal injury and neuronal loss, and improved the associated neurological dysfunctions in juvenile rats.
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PMID:Alpha-phenyl-n-tert-butyl-nitrone ameliorates hippocampal injury and improves learning and memory in juvenile rats following neonatal exposure to lipopolysaccharide. 1836 24

Cytokine-induced CNS inflammation has been theorized to contribute to cognitive dysfunction in sickness and neurodegenerative disease. We investigated the effects of systemic endotoxin-induced acute immune activation and inflammation on working memory and attention functions in pigeons assessed through two variations of an operant symbolic matching-to-sample (SMTS) task, employing doses of lipopolysaccharide (LPS) sufficient to induce fever. LPS produced moderate impairments in comparison to saline on the SMTS task designed to measure visual vigilance and attention, but the impairments were not as marked as those produced by chlordiazepoxide (CDP) which is known to disrupt attention. In contrast, LPS had no significant effect on short-term working memory performance compared to saline, while scopolamine, a cholinergic antagonist known to disrupt working memory, did impair performance. The results have implications for the cognitive impairments seen in illnesses characterized by chronic cytokine activation (e.g., Alzheimer's disease) as well as illnesses treated with cytokines (e.g., multiple sclerosis) suggesting that some cognitive failures attributed to working memory impairments per se may better be attributed to prior attention impairments.
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PMID:Lipopolysaccharide-induced immune activation impairs attention but has little effect on short-term working memory. 1865 7

Alzheimer's Disease (AD) is the most common age-related dementia, with a current prevalence in excess of five million individuals in the United States. The aggregation of amyloid-beta (A beta) into fibrillar amyloid plaques is a key pathological event in the development of the disease. Microglial proinflammatory activation is widely known to cause neuronal and synaptic damage that correlates with cognitive impairment in AD. However, current pharmacological attempts at reducing neuroinflammation mediated via microglial activation have been largely negative in terms of slowing AD progression. Previously, we have shown that microglia express proinflammatory cytokines and a reduced capacity to phagocytose A beta in the context of CD40, A beta peptides and/or lipopolysaccharide (LPS) stimulation, a phenomenon that can be opposed by attenuation of p44/42 mitogen-activated protein kinase (MAPK) signaling. Other groups have found that blueberry (BB) extract both inhibits phosphorylation of this MAPK module and also improves cognitive deficits in AD model mice. Given these considerations and the lack of reduced A beta quantities in behaviorally improved BB-fed mice, we wished to determine whether BB supplementation would alter the microglial proinflammatory activation state in response to A beta. We found that BB significantly enhances microglial clearance of A beta, inhibits aggregation of A beta(1-42), and suppresses microglial activation, all via suppression of the p44/42 MAPK module. Thus, these data may explain the previously observed behavioral recovery in PSAPP mice and suggest a means by which dietary supplementation could mitigate an undesirable microglial response toward fibrillar A beta.
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PMID:Blueberry opposes beta-amyloid peptide-induced microglial activation via inhibition of p44/42 mitogen-activation protein kinase. 1878

Infantile spasms are characterized by age-specific expression of epileptic spasms and hypsarrhythmia and often result in significant cognitive impairment. Other epilepsies or autism often ensue especially in symptomatic IS (SIS). Cortical or subcortical damage, including white matter, have been implicated in the pathogenesis of SIS. To generate a model of SIS, we recreated this pathology by injecting rats with lipopolysaccharide and doxorubicin intracerebrally at postnatal day (P) 3 and with p-chlorophenylalanine intraperitoneally at P5. Spasms occurred between P4 and 13 and were associated with ictal EEG correlates, interictal EEG abnormalities and neurodevelopmental decline. After P9 other seizures, deficits in learning and memory, and autistic-like behaviors (indifference to other rats, increased grooming) were observed. Adrenocorticotropic hormone (ACTH) did not affect spasms. Vigabatrin transiently suppressed spasms at P5. This new model of SIS will be useful to study the neurobiology and treatment of SIS, including those that are refractory to ACTH.
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PMID:A model of symptomatic infantile spasms syndrome. 1994 33


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