Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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

The effects of inoculation of LP-BM5 murine leukemia retrovirus and chronic ethanol (5% v/v) ingestion on immunomodulation and Cryptosporidium parvum infection in C57BL/6 female mice were evaluated. The intestinal mucosae of retrovirally immunosuppressed animals were heavily colonized by Cryptosporidium parasites, and oocysts shedding in the feces persisted throughout the duration of the study. Mortality was exacerbated by murine retrovirus infection alone and exacerbated with concomitant chronic alcohol feeding (42.8 and 69.4%). Chronic ethanol ingestion decreased production of interferon-gamma and soluble interleukin-2 receptor released in supernatants of splenocytes when stimulated with concanavalin A, compared with the control group. Decreased production of interferon-gamma and interleukin-2 receptor was further exacerbated due to retrovirus infection. Tumor necrosis factor production by splenocytes stimulated with lipopolysaccharide, however, was significantly increased because of retrovirus infection. LP-BM5 retrovirus infection alone as well as with concomitant ethanol feeding altered cytokine production, which might have led to immunodeficiency. These changes may help explain the enhanced persistence of Cryptosporidiosis.
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PMID:Alcohol and murine acquired immunodeficiency syndrome suppression of resistance to Cryptosporidium parvum infection during modulation of cytokine production. 833 81

Patients with human immunodeficiency virus (HIV) infection are prone to the development of focal segmental glomerulosclerosis, a lesion in which increased mesangial cell proliferation and matrix synthesis may play a role. We undertook the present study to determine whether HIV sera may affect mesangial cell proliferation and matrix synthesis either directly or indirectly via effects on macrophage supernatants. Pooled HIV sera was found to significantly enhance (P < 0.01) mesangial cell proliferation in a concentration-related manner. Mesangial cell proliferation was significantly suppressed by two medications commonly utilized in HIV-infected patients, azidothymidine and trimethoprim/sulfamethoxazole, and was not significantly altered by lipopolysaccharide, suggesting that these medications as well as recurrent infection are unlikely to account for the proliferative effect of HIV sera. Supernatants from HIV sera-treated macrophages were found to significantly enhance (P < 0.01) mesangial cell incorporation of [3H]proline, a marker for synthesis of the matrix component collagen, compared to supernatants from control sera-treated macrophages. These results suggest that HIV sera may directly enhance mesangial cell proliferation and may indirectly increase mesangial cell matrix synthesis by altering macrophage secretory products. These effects may play a role in the development of glomerulosclerosis in patients with HIV infection.
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PMID:Effects of human immunodeficiency virus sera and macrophage supernatants on mesangial cell proliferation and matrix synthesis. 836 79

The goal of our study was to assess whether the human immunodeficiency virus (HIV) coat protein gp120 induces functional alterations in astrocytes and microglia, known for their reactivity and involvement in most types of brain pathology. We hypothesized that gp120-induced anomalies in glial functions, if present, might be mediated by changes in the levels of intracellular messengers important for signal transduction, such as cAMP. Acute (10 min) exposure of cultured rat cortical astrocytes or microglia to 100 pM gp120 caused only a modest (50-60%), though statistically significant, elevation in cAMP levels, which was antagonized by the beta-adrenergic receptor antagonist propranolol. More importantly, the protein substantially depressed [by 30% (astrocytes) and 50% (microglia)] the large increase in cAMP induced by the beta-adrenergic agonist isoproterenol (10 nM), without affecting that induced by direct adenylate cyclase stimulation by forskolin. Qualitatively similar results were obtained using a glial fibrillary acidic protein (GFAP)-positive human glioma cell line. The depression of the beta-adrenergic response had functional consequences in both astrocytes and microglia. In astrocytes we studied the phosphorylation of the two major cytoskeletal proteins, vimentin and GFAP, which is normally stimulated by isoproterenol, and found that gp120 partially (40-50%) prevented such stimulation. In microglial cells, which are the major producers of inflammatory cytokines within the brain, gp120 partially antagonized the negative beta-adrenergic modulation of lipopolysaccharide (10 ng/ml)-induced production of tumor necrosis factor alpha. Our results suggest that, by interfering with the beta-adrenergic regulation of astrocytes and microglia, gp120 may alter astroglial "reactivity" and upset the delicate cytokine network responsible for the defense against viral and opportunistic infections.
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PMID:Human immunodeficiency virus coat protein gp120 inhibits the beta-adrenergic regulation of astroglial and microglial functions. 838 71

Human epidermal Langerhans cells (LC) isolated from normal skin were infected in vitro with human immunodeficiency virus type 1 (HIV1). To control the permissivity of LC for HIV1, cells isolated from the epidermal sheet of normal skin by trypsinization were cocultured with HIV1-carrying promonocytic cells (U937) and observed by electron microscopy. An early sign of infection occurring in the coculture was the formation of retroviral type buds from LC membrane. Different steps in the process of viral budding up to virus release into the extracellular space were observed by electron microscopy. Treatment with either coupled phorbol esters/bacterial lipopolysaccharide or a recombinant cytokine (tumour necrosis factor alpha) did not significantly enhance viral production. The ability of in vitro infected LC to transmit virus to other haematopoietic cells and the consequences of such an infection on antigen-presenting function of LC remain to be elucidated.
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PMID:In vitro infection of epidermal Langerhans cells with human immunodeficiency virus type 1 (HTLV-IIIB isolate). 844 78

Chronic graft-versus-host disease often results in a combined deficiency of humoral and cell-mediated immunity. Clinical and experimental studies have suggested that the decrease in B cell responsiveness is due to a failure of B cell production in the bone marrow, intrinsic B cell defects, excessive suppressor T cell activity, and deficient T helper activity. In the present study, we analyze the basis of B cell immunodeficiency in C.B-20-->(C.B-20 x B10.D2)F1 animals afflicted with chronic GVHD. The initial decline in B cell production in the BM accounts for the early reduction in the number of B cells in the spleen and BM. Later, as B cells appear in near-normal numbers in the BM, the spleen and lymph node are repopulated by the newly derived B cells. Associated with the appearance of B cells in the BM and spleen is the ability to respond to lipopolysaccharide. In contrast, both B cell populations are severely diminished in their ability to proliferate in response to agar-derived mitogens to form colonies (CFU-B). The reduction in the CFU-B response is most likely a consequence of an inherent B cell defect, since purification of C.B-20-->F1 splenic B cells does not restore the colony-forming potential. Unlike BM and splenic B cells, LN B cells are unable to respond to either mitogen. Taken together, these results imply that a population of B cells derived from a distinct lineage and/or B cell maturation is defective in mice undergoing GVHD.
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PMID:The effect of chronic graft-versus-host disease on B cell development. 845 80

Mononuclear phagocytes generate microbicidal oxygen metabolites spontaneously and after phagocytic stimulation by a NADPH-dependent enzymatic reaction called the oxidative burst. The spontaneous release of reactive oxygen radicals and intermediates (ROI) increases five- to eightfold after treatment of monocytes with the lymphokine interferon-gamma (IFN-gamma). The effect of the IFN-gamma-activated release of ROI by human monocytes on the infectivity of free human immunodeficiency virus (HIV) in the supernatant was investigated with the following results. First, IFN-gamma-activated, but neither control monocytes nor lipopolysaccharide-stimulated monocytes effectively decreased the infectivity of cell-free HIV-1 in culture medium supernatant. Second, the mechanism of inactivation was dependent on the enhanced spontaneous release of ROI by IFN-gamma-activated mononuclear phagocytes, since either the enzyme catalase or the free radical scavenger butylated hydroxyanisole (BHA) could block this activity. Third, soluble and solid-phase HIV-1 outer envelope glycoprotein (gp120) failed to trigger the oxidative burst activity after specific gp120-monocytic CD4 receptor interaction. These results indicate an anti-viral effect of IFN-gamma-activated monocytes/macrophages on HIV-1 which may have important implications for our understanding of spread of the virus in the body and the development of full-blown AIDS after a long period of latency.
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PMID:Interferon-gamma-activated monocytes impair infectivity of HIV particles by an oxygen metabolite-dependent reaction. 847 9

Many effects of lipopolysaccharide (LPS) on gene expression, including that of human immunodeficiency virus (HIV), in monocytic cells are mediated by activation of kappa B DNA-binding proteins. However, the specific members of the NF-kappa B/Rel transcription factor family involved in the LPS response, and the mechanisms through which LPS-generated signals are transduced remain unclear. Here we show that LPS induces nuclear expression of c-Rel/p50 heterodimers as well as p50/p65 (NF-kappa B) kappa B DNA-binding complexes in human monocytic THP-1 cells. Nuclear localization of these proteins occurred concomitantly with a rapid decrease in their cytosolic levels and was independent of phorbol ester-sensitive protein kinase C. Within 24 h following LPS stimulation there was a striking increase in the levels of c-Rel, p105, and p50 in the cytosol. The increased levels of these proteins correlated with increases in the amounts of their mRNAs during LPS activation of THP-1 cells. LPS activation of THP-1 cells resulted in phosphorylation of MAD3 (an I kappa B-like protein), a rapid increase in MAD3 mRNA, and an increase in MAD3 protein by 2 h. Thus, LPS activation of human monocytic cells results in nuclear expression of c-Rel/p50 and p50/p65 (NF-kappa B) and induces phosphorylation of MAD3.
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PMID:Lipopolysaccharide induces phosphorylation of MAD3 and activation of c-Rel and related NF-kappa B proteins in human monocytic THP-1 cells. 850 9

The molecular mechanisms regulating human immunodeficiency virus (HIV) persistence in a major cell reservoir such as the macrophage remain unknown. NF-kappa B is a transcription factor involved in the regulation of the HIV long terminal repeat and is selectively activated following HIV infection of human macrophages. Although little information as to what signal transduction pathways mediate NF-kappa B activation in monocytes-macrophages is available, our previous work indicated that classical protein kinase C (PKC) isoenzymes were not involved in the HIV-mediated NF-kappa B activation. In this study, we have focused on atypical PKC isoenzymes. PKC-zeta belongs to this family and is known to be an important step in NF-kappa B activation in other cell systems. Immunoblotting experiments with U937 cells demonstrate that PKC-zeta is present in these cells, and its expression can be downmodulated by antisense oligonucleotides (AO). The HIV-mediated NF-kappa B activation is selectively reduced by AO to PKC-zeta. In addition, cotransfection of a negative dominant molecule of PKC-zeta (PKC-zeta mut) with NF-kappa B-dependent reporter genes selectively inhibits the HIV- but not phorbol myristate acetate- or lipopolysaccharide-mediated activation of NF-kappa B. That PKC-zeta is specific in regulating NF-kappa B is concluded from the inability of PKC-zeta(mut) to interfere with the basal or phorbol myristate acetate-inducible CREB- or AP1-dependent transcriptional activity. Lastly, we demonstrate a selective inhibition of p24 production by HIV-infected human macrophages when treated with AO to PKC-zeta. Altogether, these results suggest that atypical PKC isoenzymes, including PKC-zeta, participate in the signal transduction pathways by which HIV infection results in the activation of NF-kappa B in human monocytic cells and macrophages.
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PMID:Protein kinase C-zeta mediates NF-kappa B activation in human immunodeficiency virus-infected monocytes. 852 29

In patients with common variable immunodeficiency (CVI), we have previously defined a subgroup of patients (CVIHyper) characterized by decreased numbers of CD4+ lymphocytes in peripheral blood, splenomegaly, and persistent immune activation in vivo, particularly of monocytes/macrophages. To further characterize this hyperactivity, parameters of activation of the tumor necrosis factor (TNF) system (TNF alpha and soluble TNF receptors [sTNFRs]) were measured in 24 patients with CVI and 20 healthy controls. Patients with CVI had significantly higher serum levels of TNF alpha and both types of sTNFRs, with the highest levels in the CVIHyper subgroup. In vitro, peripheral blood mononuclear cells (PBMC) and purified monocytes from CVIHyper patients spontaneously released significantly higher levels, and, after lipopolysaccharide (LPS) stimulation, significantly lower levels of TNF alpha and soluble p75-TNFR than cells from both other CVI patients and healthy controls. CVIHyper patients also had significantly higher TNF alpha:sTNFRs ratios in both serum and in unstimulated PMBC supernatants. The present study demonstrates persistent in vivo activation of the TNF system in CVI, particularly in the CVIHyper subgroup. This activation may contribute to the pathogenesis of both clinical and immunologic manifestations in CVI.
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PMID:Persistent activation of the tumor necrosis factor system in a subgroup of patients with common variable immunodeficiency--possible immunologic and clinical consequences. 855 90

Persistent human immunodeficiency virus (HIV) infection of human monocytes and macrophages increases I kappa B alpha degradation, resulting in the activation of NF-kappa B, a key transcription factor in the regulation of the HIV long terminal repeat. The signal transduction pathways leading to NF-kappa B activation in cells of the monocytic lineage, especially those regulated by HIV infection, and their relevance in regulating viral persistence remain unknown. Both p21ras and its downstream Raf-1 kinase participate in the transduction of signals initiated from a variety of cell surface receptors and in the regulation of transcription factors. We have studied whether the Ras-Raf pathway is functional and participates in HIV-mediated NF-kappa B activation in monocytic cells. Constitutively active p21ras (v-H-Ras) activated NF- kappa B-dependent transcription and induces the nuclear translocation of a bona fide p65/p50 heterodimer by targeting I kappa B alpha. In addition, the constitutively active form of Raf (RafBXB) also increases the NF-kappa B-dependent transcriptional activity. Because of the similarity between HIV and Ras-Raf-induced NF-kappa B activation in monocytic cells, we next tested whether HIV-induced NF-kappa B activation was mediated by the Ras-Raf signal transduction pathway. Negative dominant forms of both Ras (Ras N17) and Raf (Raf 301) decreased the HIV- but not lipopolysaccharide-dependent NF-kappa B activation in U937 cells. Moreover, Raf-1 kinase activity was greater in HIV-infected than uninfected monocytic cells in in vitro kinase assays. Altogether, these results indicate that the Ras-Raf pathway is unregulated in HIV monocytic cells and participates in the virus-induced activation of NF-kappa B.
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PMID:The Ras-Raf pathway is activated in human immunodeficiency virus-infected monocytes and particpates in the activation of NF-kappa B. 864 60


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