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)

Apart from lymphocytes, mononuclear phagocytes play an essential role as target cells for human immunodeficiency virus (HIV). Circulating blood monocytes (MOs) and tissue macrophages (M phi) may harbor and distribute the virus throughout the body. In addition, proinflammatory monokines [interleukin-1 (IL-1), IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha)] may contribute to the pathogenesis of HIV-mediated diseases. We have established a culture system on hydrophobic Teflon membranes for blood-borne MOs/M phi. Both freshly isolated MOs as well as MO-derived M phi could be infected with a monocytotropic HIV-1 isolate (HIV-1D117III) derived from a perinatally infected child. The virus production monitored by assay for viral antigen in cell-free supernatant is continuous for several weeks. We analyzed the stimulus response and the secretory repertoire of MOs/M phi early after infection with HIV as well as in long-term cultured, virus-replicating cells. Infected MOs/M phi respond to interferon-gamma more effectively than control cells as estimated from the release of neopterin. The response to lipopolysaccharide was regulated differently: whereas the proinflammatory cytokines IL-1, IL-6, IL-8 and TNF-alpha were up-regulated and even constitutively secreted upon infection, the production of the hematopoietin macrophage-colony-stimulating factor decreased. High levels of TNF-alpha and IL-1 might augment the infectibility of M phi by HIV in an autocrine manner. Our results may provide some explanation for the immunologic dysfunction, the hematopoietic failure and the chronic inflammatory disease occurring in HIV-infected patients.
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PMID:Secretory repertoire of HIV-infected human monocytes/macrophages. 190 44

We have investigated the effects of human immunodeficiency virus type-1 (HIV-1) infection on constitutive and lipopolysaccharide (LPS)-induced expression of interleukin-6 (IL-6) in cultured blood monocyte-derived macrophages. Highly productive and cytopathic infection of macrophages was established with the macrophage-tropic HIV-1 BaL strain. On Days 14-28 post infection, infected and mock-infected cells were activated with LPS or control medium for 6-24 hours before harvesting culture supernatants and cellular RNA. IL-6 bioactivity in culture supernatants was measured with the IL-6-dependent B9 cell line. IL-6 mRNA levels were quantitated by Northern blot analysis with scanning densitometry. In the absence of LPS activation, IL-6 activity was near or below the limit of detection in supernatants from both infected and uninfected cultures. Similarly, without LPS stimulation, IL-6 mRNA was not detectable in either infected or uninfected macrophages. After activation with LPS, marked increases in IL-6 mRNA levels and supernatant bioactivity were evident in both infected and uninfected cultures, but the response to LPS was consistently greater in infected macrophages. LPS-induced IL-6 mRNA levels and supernatant bioactivity were 7.4- and 4.4-fold higher, respectively, in infected compared with uninfected macrophages (n = 5, p less than .05). These studies demonstrate that highly productive HIV-1 infection does not increase constitutive IL-6 expression in macrophages, but does prime macrophages for an augmented IL-6 response to LPS. These findings may help define the mechanisms responsible for increased IL-6 production in patients with HIV-1 infection.
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PMID:Interleukin-6 expression in primary macrophages infected with human immunodeficiency virus-1 (HIV-1). 193 Dec 35

We have measured the production of interleukin 1 (IL 1), interleukin 6 (IL 6), and tumor necrosis factor alpha (TNF alpha) by unstimulated monocytes and monocytes stimulated with lipopolysaccharide (LPS) isolated from the peripheral blood of patients infected with human immunodeficiency virus 1 (HIV-1) and healthy controls. Spontaneous and LPS-induced cytokine production were not significantly different between patients and controls. Median lipopolysaccharide-stimulated cytokine secretion for patients and controls was 1.7 and 4.3 U/ml for IL 1, 475 and 625 U/ml for IL 6, and 468 and 580 pg/ml for TNF alpha. Cytokine levels were not related to stage of disease. We conclude that in vivo HIV infection itself does not alter peripheral blood monocyte cytokine secretion.
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PMID:Cytokine secretion by peripheral blood monocytes from human immunodeficiency virus-infected patients is normal. 193 24

Although monocytic cells can provide a reservoir for viral production in vivo, their regulation of human immunodeficiency virus type 1 (HIV-1) transcription can be either latent, restricted, or productive. These differences in gene expression have not been molecularly defined. In THP-1 cells with restricted HIV expression, there is an absence of DNA-protein binding complex formation with the HIV-1 promoter-enhancer associated with markedly less viral RNA production. This absence of binding was localized to the NF-kappa B region of the HIV-1 enhancer; the 65-kDa plus 50-kDa NF-kappa B heterodimer was preferentially lost. Adding purified NF-kappa B protein to nuclear extracts from cells with restricted expression overcomes this lack of binding. In addition, treatment of these nuclear extracts with sodium deoxycholate restored their ability to form the heterodimer, suggesting the presence of an inhibitor of NF-kappa B activity. Furthermore, treatment of nuclear extracts from these cells that had restricted expression with lipopolysaccharide increased viral production and NF-kappa B activity. Antiserum specific for NF-kappa B binding proteins, but not c-rel-specific antiserum, disrupted heterodimer complex formation. Thus, both NF-kappa B-binding complexes are needed for optimal viral transcription. Binding of the 65-kDa plus 50-kDa heterodimer to the HIV-1 enhancer can be negatively regulated in monocytes, providing one mechanism restricting HIV-1 gene expression.
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PMID:Negative regulation of human immunodeficiency virus type 1 expression in monocytes: role of the 65-kDa plus 50-kDa NF-kappa B dimer. 194 56

To assess the value of feline immunodeficiency virus (FIV) infection as a model for human immunodeficiency virus (HIV) infection in man, we studied the impairment of certain immunological functions following natural or experimental FIV infection. Proliferative responses of peripheral blood mononuclear cells (PBMC) from symptomatic and asymptomatic cats after naturally or experimentally acquired FIV infection, induced by activation with the mitogens concanavalin A, pokeweed mitogen, or lipopolysaccharide or by stimulation with human interleukin-2 (IL-2), were significantly lower than the proliferative responses found with PBMC from noninfected control cats. Also IL-2 production levels of mitogen-activated PBMC from naturally infected symptomatic cats were significantly reduced. These data confirm that the pathogenesis of FIV infection in the cat, like HIV infection in man, is characterized by a serious malfunction of the immune system.
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PMID:Feline immunodeficiency virus (FIV) infection in the cat as a model for HIV infection in man: FIV-induced impairment of immune function. 196 59

We have developed an adjuvant formulation (SAF) consisting of a synthetic muramyl dipeptide analogue (N-acetylmuramyl-L-threonyl-D-isoglutamine) in a squalane-Pluronic polymer emulsion. Used with a variety of antigens SAF elicits cell-mediated immunity and antibodies of protective isotypes (IgG2a in the mouse). SAF augments responses to influenza virus haemagglutinin and hepatitis B virus surface antigen. Vaccines using SAF have protected guinea pigs against genital herpes simplex virus infections and subhuman primates against Epstein-Barr virus and simian immunodeficiency virus infections. Properties of SAF are compared with those of other adjuvants, including lipopolysaccharide analogs, ISCOMs and liposomes.
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PMID:Adjuvant formulations and their mode of action. 196 59

Macrophages, unlike CD4+ T cells, can be productively infected by human immunodeficiency virus (HIV) without prior cellular activation. Cytopathic infection ensues without the induction of tumor necrosis factor alpha (TNF alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), or tissue factor genes. In detailed studies on TNF alpha, HIV infection did not affect the regulation of TNF alpha in response to bacterial lipopolysaccharide. In an effort to examine the interferon responsiveness of HIV-infected macrophages, the cells were challenged with vesicular stomatitis virus (VSV) with or without interferon pretreatment. Surprisingly, HIV-infected macrophages were completely resistant to VSV-induced lysis even in the absence of interferon; however, no interferon was detected in the supernatants of these infected cells. The resistance of HIV-infected macrophages to superinfection with VSV indicates a previously undescribed effect of HIV upon macrophage cellular metabolism.
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PMID:Characterization of a macrophage-tropic HIV strain that does not alter macrophage cytokine production yet protects macrophages from superinfection by vesicular stomatitis virus. 217 98

Studies with FLV infected mice, a model for retrovirus induced acquired immunodeficiency, showed that intact lipopolysaccharide rich extract from Serratia marcescens as well as the nontoxic polysaccharide derivative free of lipid A were equally adjuvantic in enhancing antibody formation to sheep erythrocytes, both in vivo and in vitro. The PS-rich endotoxin derivative had little or no toxic activity in leukemic animals as occurred with intact endotoxin. The adjuvanticity of both the nontoxic polysaccharide derivative as well as the intact endotoxin in enhancing antibody formation in FLV infected mice was evident also in vitro when spleen cells from infected animals were immunized with sheep erythrocytes simultaneously with the polysaccharide in comparison with the LPS. Supernatants from normal spleen cells treated in vitro either with the polysaccharide or the intact endotoxin showed immunoenhancing helper activity for both normal and FLV infected spleen cells and this enhancing activity was due to IL-1 induced by either bacterial product. Thus the immunoenhancing soluble mediator, i.e., IL-1, is induced equally by PS or LPS and has immunorestorative activity for FLV infected animals. The potential value of the nontoxic PS as an immunoadjuvant in retrovirus immunosuppressed lymphoid cells is evident. The results of these studies suggest that further investigations concerning the nature and mechanism involved in such adjuvancticity is warranted.
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PMID:Immunoadjuvanticity of endotoxins and nontoxic derivatives for normal and leukemic immunocytes. 218 63

Phagocytic macrophages are known to support noncytopathic, chronic infections of human immunodeficiency virus (HIV). Regulation of viral replication in such cells with either chronic low-grade or latent HIV infection is probably influenced by both viral and cellular factors acting on the viral long terminal repeat (LTR). This study identifies naturally occurring biological response modifiers which are able to affect the HIV-LTR linked to the chloramphenicol acetyl transferase (LTR-CAT) gene in a stable transfection of the human promonocyte cell line, U937, in the absence of other viral proteins. In this model system, endotoxin lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) are able to independently stimulate expression of LTR-CAT. Granulocyte/macrophage-colony-stimulating factor can enhance the effect of TNF-alpha or LPS, but other cytokines tested had minimal or no effect on LTR-CAT. In addition to effects on cellular susceptibility and immune function, the ability of naturally occurring factors to affect HIV-LTR in its integrated state may have particular relevance to progression of active disease from latent infection.
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PMID:Expression of human immunodeficiency virus long terminal repeat in the human promonocyte cell line U937: effect of endotoxin and cytokines. 220 Jun 14

Proliferative responses to mitogens were determined by using peripheral blood mononuclear cells from women with active trichomoniasis, with serological evidence of past infection with Trichomonas vaginalis, and with no evidence of current or past infection. Even after the human immunodeficiency virus antibody status of the patients was taken into account, cells from women with active trichomoniasis showed reduced responses to phytohemagglutinin, concanavalin A, pokeweed mitogen, and bacterial lipopolysaccharide. Similar findings were obtained by using spleen cells from mice inoculated subcutaneously with live trichomonads. Reduction in proliferative responses by these cells could be detected 3 days after inoculation. There was some evidence to suggest that more-pathogenic strains of the parasite induced a greater degree of immunosuppression. The responses of spleen cells from mice inoculated with trichomonad-free culture supernatants were within normal limits, indicating that live trichomonads were needed to induce suppression. Support for this was gained from studies with cells from women who were treated successfully. Cells from these women rapidly regained normal lymphoproliferative function. Interleukin-2 (IL-2) production by spleen cells from infected mice was determined from measurements of mitochondrial activity in an IL-2-dependent T-cell line following incubation with stimulated spleen cell culture supernatants. These tests demonstrated lower IL-2 activity in supernatants from cell cultures from infected mice than in those from uninfected mice. The reduction in IL-2 activity did not, however, appear to correlate with the degree of reduction of mitogen-induced lymphoproliferation. Suppression of T-cell-mediated immunity may be one of the mechanisms by which T. vaginalis is able to evade host responses to infection.
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PMID:Reduced lymphocyte responses to mitogens in natural and experimental trichomoniasis. 222 26


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