HIV-1 Tat Protein Promotes Amyloid beta Generation and Tau Phosphorylation in Rat Hippocampal Slices

HIV-1 Tat protein has been implicated as a causative agent in the pathogenesis of HIV-1-associated neurocognitive disorder (HAND) and Alzheimer's disease (AD)-like pathology in HIV-1 infected patients. Here, we provide insights into the potential roles of extracellular HIV-1 Tat protein in amyloid beta (Abeta) generation and Tau phosphorylation, two major neuropathological features of AD. Exposure of the rat hippocampal slices to the full-length HIV-1 Tat protein (Tat1-86) for 3 days led to the increased levels of Abeta precursor protein (APP) accumulation, which accompanied by Abeta generation in the hippocampus, the brain region most commonly damaged in HIV-1-associated dementia (HAD). Moreover, extracellular HIV-1 Tat significantly stimulated the level of phosphrylated Tau (pTau) identified using immunoblotting with AT8 antibody, which recognizes abnormally hyperphosphorylated Tau. Collectively, our data suggest that HIV-1 Tat plays important roles in increasing the levels of APP accumulation, Abeta generation and Tau phosphorylation in the hippocampus, and thereby might contribute to the development of AD-like pathology in HIV-1-infected patients.

HIV-1 Tat Protein-dependent Cytotoxicity is Attenated by 15-deoxy-Delta12,14-Prostaglandin J2 in Rat Hippocampal Slices: Involvement of the ERK1/2 Signaling Pathway

15-deoxy-delta12,14 prostaglandin J2 (15d-PGJ2) may hold promise in treatment of the pathologies associated with human immunodeficiency virus (HIV) infection of the central nervous system. However, its precise role and neuroprotective mechanism in the hippocampus remain poorly understood. In the present study, rat hippocampal slices were stimulated with HIV-1 Tat protein to investigate the protective role of 15d-PGJ2 on the hippocampal cytotoxicity. Full-length HIV-1 Tat protein (Tat1-86), but neither its Tat32-62 nor Tat30-86 fragment, significantly induced cytotoxicity in the hippocampus, the brain region most commonly damaged in HIV-associated dementia. This Tat-induced cytotoxicity was associated with inactivation of MEK/extracellular signal-regulated kinase (ERK) signaling pathway. In contrast, Tat1-86 did not alter Wnt signaling pathway necessary for cell survival. Pretreatment of slices with 15d-PGJ2 markedly reduced Tat-driven cytotxicity. Interestingly, this reduction was accompanied by suppression of ERK inactivation in response to Tat. Moreover, the inhibition of the MEK/ERK pathway with SL327 enhanced the Tat-induced cytotoxicity, confirming the ERK-dependent mechanism of Tat-driven cytotoxicity. Collectively, these data demonstrate that the protective action of 15d-PGJ2 against the hippocampal cytotoxicity upon Tat stimulation is exerted through suppression of Tat-mediated ERK1/2 inactivation.

Spectrin Cleavage Induced by LLP-1 Lentivirus Lytic Peptide Domain in the Intracytoplasmic Tail of Human Immunodeficiency Virus Type 1 GP41 in Rat Organotypic Hippocampal Slice Cultures

We previously demonstrated that the lentivirus lytic peptide 1 (LLP-1) corresponding to the carboxyl terminus of HIV-1 gp41 induced cell death in human neuronal cells. Present study was conducted to further elucidate the pathogenic mechanisms involved in HIV-1 gp41-induced neurodegeneration in AIDS patients with cognitive deficits. The effect of LLP-1 on activation of calpain-1, a calcium-activated cysteine protease, which has been implicated in neuronal degeneration and death, was monitored by the proteolysis of spectrin in rat organotypic hippocampal slice cultures. Protease specific spectrin breakdown products revealed that LLP-1 generated~150/145-kDa fragments characteristic of calpain-1 activation in hippocampus undergoing cell death as evidenced by LDH release. This spectrin cleavage pattern was further confirmed by in vitro calpain-1 proteolysis. Futhermore, calpectin and MDL28170, inhibitors of calpain activity, blocked calpain-1-mediated spectrin cleavage. Spectrin cleavage likely occurred in the absence of overt synaptic loss, as suggested by the preserved levels of synaptophysin. Among pharmacological agents tested, apocynin, NADPH oxidase inhibitor, ameliorated the LLP-1-induced spectrin. Given the role of spectrin essential for synapse stabilization, LLP-1-induced spectrin cleavage as occurs with the activation of calpain-1 may be an important effector in LLP-1mediated cell injury in hippocampus, which is primarily linked to cognitive dysfunction.

Detection of Adenovirus and Parvovirus in CSF Specimens from Viral Meningitis Adult Patients by Enzyme Immunoassay with Monoclonal Antibody and by Nested - PCR

Viral meningitis and encephalitis are important and serious diseases in young children and adults. There are many causative viruses but it is known that a low percentage of adenovirus (ADV) and parvovirus (PA V) infected individuals develop meningitis or encephalitis. Few reports have been published about central nervous system complications that were rare but fatal. First we used enzyme immunoassay (EIA) with monoclonal antibody to detect ADV antigen (Ag) and PAV Ag in cerebrospinal fluids (CSF) from acute phase of hospitalized adult patients with viral meningitis or viral encephalitis. Second we detected ADV DNA and PAV DNA in the same CSF after cell culture by nested-polymerase chain reaction (PCR). Third we evaluated ADV and PAV dual infection in CSF by EIA and nested-PCR. ADV Ag in CSF by EIA positivity was 42.9% (12l28) and PAV Ag in CSF by EIA positivity was 21.4% (6/28). ADV DNA in CSF by nested-PCR positivity was 89.3% (25/28) and PAV DNA in CSF by nested-PCR positivity was 38.5% (10/26). ADV and PAV dual infection in CSF by 11CSted-PCR was 35.7% (10/28). Detection rate of ADV DNA and PAV DNA in CSF by nested-PCR with viral meningitis or encephalitis adult patients were higher than we expected. Positive detection of nested-PCR was higher than that of EIA with monoclonal antibody for detection of antigens ADV and PAV in CSF with viral meningitis or encephalitis adult patients. Both methods were analnized by the McNemar test.

Molecular Mechanism of TNF-alpha and MMP-9 Production in Response to HIV-1 Core Antigen p24 in Human Monocytie THP-1 Cells

No abstract available.

Detection of Herpes Virus-6 by PCR I Cerebrospinal Fluid from Hospitalized Adult Patients with Aseptic Meningitis or Encephalitis

No Abstract Available.

Interaction of HIV-1 core p24 antigen with human monocytic cell line THP1 results in TNF-alpha dependent secretion of matrix metalloproteinase-9

Immunological mechanisms involving the release of inflammatory factors by HIV-1 infected microglia in the brain have been implicated in the pathogenesis of HIV dementia (HIVD). Since the regulation of matrix metalloproteinases (MMPs) activity can be influenced by variety of inflammatory mediators, this study was undertaken to look for a correlation between the MMP-9 release and the production of TNF-alpha in response to HIV-1 p24 in the human monocyte cell line THP-1 as a model for microglia. First, it was shown that HIV-1 core p24 antigen induced THP-1 to secrete MMP-9 in a dose response manner while it elicited a little effect on MMP-2 release in human astroglial cell line T98G. Next, it was found that p24 induced THP-1 to secrete TNF-alpha without prior differentiation into macrophages by phorbol myristate acetate (PMA) treatment. Furthermore, anti-TNF-alpha neutralizing antibodies significantly blocked p24-induced MMP-9 release in a dose dependent manner. Our data indicate that p24 antigen induces monocytic MMP-9 release by triggering up-regulation of TNF-alpha secretion.

Detection of Astrovirus Infection from Hospitalized Young Children Feces by Reverse Transcription - Polymerase Chain Reaction

Astrovirus is frequently associated with diarrhea in children. It can not be readily isolated by cell culture, and an electronmicroscope is usually used for detection of this agent. Recently in 1995 a combined method of reverse transcription-polymerase chain reaction (RT-PCR) was designed for easier detection of astrovirus, which is based on the conserved sequence in 3'-end of genomes of the 7 known serotypes of human astrovirus. As of yet there has not been any report of astrovirus data in Korea using the RT-PCR methods. The purpose of this study was to detect astrovirus incidence, severity of symptoms, seasonal variation and coinfection rate with rotavirus in Korean children inpatients with diarrhea. Fecal specimens from 61 young children hospitalized with gasteroenteritis Korea from Jan. 1996 through Mar. 1997. They were examined for astroviurs infection by RT-PCR method. Results are as follows: 1. Astrovirus was detected at 9.8% (6/61) from fecal specimens of children with severe diarrhea by EIA using monoclonal antibody coated plates. 2. Astorvirus was detected at 29.5% (18/61) from fecal specimens of children with severe diarrhea by RT-PCR. 3. The age of the 18 children affected by astrovirus ranged from 2 monthes to 7 years with mean of 3.0 years. 4. Mean hospital stay of the 1S children was 6.1 days. 5. Five (27.8%) astrovirus RT-PCR positive strains were confirmed in November and in December, respectively out of 18 specimens in total. 6. Astrovirus coinfection with rotavirus type G1 was confirmed in 15/16 specimens (93.8%), and with type G2 was in 1/16 specimens (6.3%).

Effect of Immobilization Stress on the Expression of Amyloid Precursor Protein in the Mouse Brain

BACKGROUND: The Central nervous system(CNS) plays a essential role in mediating~stress responses. However, the enact mechanism of the CNS in mediating stress responses has not been clarified sufficiently as yet. Stress may cause brain dysfunction including cognitive dysfunction which was most commonly found in Alzheimer's dementia. Amyloid precursor protein(APP) is a large, ubiquitously distributed and evolutionarily conserved molecule whose function remains unknown. Although the precise function of APP following injury to the CNS such as stab and kainic acid lesion. However, there have not been reports on the effects of stress on the expression of amyloid precursor protein in the brain. This study was undertaken to elucidate the effects of stress on the expression of APP in the mouse brain. METHODS: The several brain region was isolated from the mouse that was in the immoblization stress for 30 min, 1 hour, and 2 hours. The mouse brain was divided into 5 regions, cerebral cortex, cerebellum hippocampus, midbrain and thalamus, corpus striatum and brain stem. The change of mRNA was examined in the several brain regions using Northern blot hybridization. RESULTS: The amounts of APP mRNA in the cerebral cortex, hippocampus and brain stem were found to be significantly increased after stress for 30 minutes and to 1.each a maximum after stress for 1 hour and to normal range at stress for 2 hours. On the contray, the contents of APP mRNA in midbrain and thalamus were decreased after stress for 30 minutes and sustained after stress for 2 hours. CONCLUSION: These findings suggest that APP may not be static but functional protein reactive to stress and stress may increase the levels of APP mRNA especially in Alzheimer disease associated sites such as cerebral cortex and hippocampus, which may contriute to the pathogenesis of Alzheimer disease.

VP7 Genotypes of Human Rotavirus from Hospitalized Children with Severe Diarrhea by Reverse Transcription - Polymerase Chain Reaction

Human rotavirus has now been established as the leading cause of gastroenteritis in young children worldwide. At least fourteen serotypes of group A rotavirus have been identified on the basis of antibody responses to major neutralizing glycoprotein, VP7 (G type for glycoprotein), present in the outer capsid of the virus. Serotype 1, 2, 3 and 4 are the most highly prevalent in human. In Korea, rotavirus is also the principal cause of severe nonbacterial diarrhea requiring hospitalization in infants and young children, which is commonly detected by EIA method. The epidemiology of rotavirus infection has been monitored by only serologic methods without electropherotyping in Korea. This study shows seasonal and age related variations .of rotavirus infection in Korea according to the genotype using the reverse transcription polymerase chain reaction (RT-PCR). Fecal specimens were obtained from 39 children hospitalized with acute watery diarrhea and gastroenteritis in Ewha Womans University MokDong Hospital in Seoul from Jan. to Dec. of 1996. All four (1, 2, 3, 4) major G serotypes were identified by amplification of segment of the gene for VP7 using RT-PCR. Rotavirus Gl 749 bp, G2 653 bp, G3 374 bp and G4 583bp were shown on 2.9 or 3.3% NuSieve agar gel. Results were as follows: 1) Rotavirus was detected at 53.8% (21/39) by EIA and 89.7% (35/39) by RT-PCR. 2) Serotype Gl, G2, G3, G4 when detected by RT-PCR accounted for 80.0% (28/35), 14.3% (5/35), 2.9% (1/35) and 2.9% (1/35), respectively. 3) Thirty five strains of rotavirus were detected at the frequency of 17.1% (6/35) in Oct., 20.0% (7/35) in Nov. and 20.0% (7/35) in Dec. 4) As for the age range, children affected by rotavirus were mostly under 1 years.

Effect of HIV-1 Gp41 Peptide on Expression and Metabolism of Amyloid Precursor Protein in Human Astroglioma Cell

Significant neurodegeneration leading to neurocognitive disorder and dementia has been observed in the central nervous system (CNS) of patients with HIV infection. Part of the neurodegenerative cascade in AIDS dementia may involve glial cells, perhaps through inhibiting the release of glial factors that protect neurons from variety of insults. Here, in an effort to find the mediators of HIV-induced brain damage, we examined the possible effect of a HIV-1 transmenbrane protein gp41 peptide (583-599) on expression and metabolism of amyloid precursor protein (APP) using human astroglial cell line. RT-PCR analysis demonstrated that gp 41 peptide did not significantly change expression patterns of APP mRNAs in lipopolysaccharide (LPS) activated astroglial cells for 6h. In contrast, gp41 peptide remarkably downregulated the level of secreted from of APP (sAPPa), which has been recently demonstrated as a potent neuroprotective factor. The reverse peptide, used as control had no such effect. The mechanism of gp41 peptide-induced down regulation of sAPPa production appears to be TGF-beta independent. These results implicate that gp41 peptide could be one of the mediator involved in the modulation of APP secretion within CNS, possibly contributing to the neuronal degeneration in HIV-1 associated neurological disease.