Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026936 (Mycoplasma)
 14,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A suitable procedure for the production of human monokines was defined as 'differentiation-induction' culture. Human monocytic leukemia THP-1 cells were well-differentiated from nonfunctional promonocytes into macrophage-like cells by the induction with a combination of mezerein, retinoic acid, and a Mycoplasma fermentans extract. The differentiated THP-1 cells secreted a high amount of macrophage differentiation-inducing factor (DIF) activity and concomitantly produced other known monokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta), into the medium. These results suggest that other novel human monokines may also be found in the conditioned medium of THP-1 cells induced by the 'differentiation-induction' culture conditions defined in this study. Macrophage DIF was purified to homogeneity and NH2-terminal amino acid sequence analysis revealed that macrophage DIF is very similar or identical to human leukemia inhibitory factor (LIF). The cDNA encoding human LIF was isolated using the polymerase chain reaction, and a clone producing 3.7 micrograms/10(6) cells day recombinant LIF was selected from Chinese hamster ovary (CHO) cells which were transfected with the LIF cDNA. The recombinant LIF production in CHO cells was quantified using MTT reduction assay with M1 cells.
 ...
PMID:"Differentiation induction" culture of human leukemic myeloid cells stimulates high production of macrophage differentiation inducing factor. 136 27

Various species of mycoplasmas were tested for their ability to induce cytokine production in human peripheral blood mononuclear cells (PBMC). Human PBMC were incubated with Mycoplasma pneumoniae, M. hyorhinis, M. arginini, M. salivarium, M. orale, M. gallisepticum or A. laidlawii for 48 hr, and the activities of interleukin-1 beta (IL-1 beta), IL-2, IL-4, IL-6, tumor necrosis factor-alpha (TNF-alpha) and interferon (IFN) in the supernatants were determined by ELISA or bioassay. All mycoplasma species induced IL-1 beta, IL-6 and TNF-alpha, although IL-2 was induced only by M. pneumoniae. IFN was induced by 5 of the 7 species, and the IFN produced was antigenically confirmed to be mainly IFN-alpha. On the other hand, mycoplasma-stimulated cultures did not contain detectable amounts of IFN-beta and IL-4 activities. Furthermore, the cytokines were induced by mycoplasmal contaminating cells in human PBMC as well as by mycoplasma alone. These results suggest that many kinds of cytokines induced by mycoplasma contamination in cell culture affect immunological experiments in vitro.
 ...
PMID:Induction of cytokines in human peripheral blood mononuclear cells by mycoplasmas. 138 Oct 37

The capacity to avoid phagocytosis and the activation of bovine alveolar macrophages (BAM) by encapsulated Mycoplasma dispar or purified M. dispar capsule was investigated. Encapsulated and unencapsulated M. dispar were cocultured with BAM in the presence or absence of antisera prepared against unencapsulated M. dispar or purified capsule antiserum. Unopsonized mycoplasmas resisted phagocytosis, while only anti-capsule antibodies enhanced the phagocytosis of encapsulated mycoplasmas. BAM were cultured in the presence of purified M. dispar capsule or either live or heat-killed encapsulated or unencapsulated M. dispar. These BAM were then activated with Escherichia coli endotoxin or left without further activation. The supernatants of these cultures were assayed for tumor necrosis factor, interleukin 1, and glucose consumption as indicators of macrophage activation. Tumor necrosis factor and interleukin 1 were produced by BAM stimulated with unencapsulated M. dispar but not when encapsulated M. dispar or its purified capsule was used. Similarly, glucose consumption was increased in the presence of unencapsulated M. dispar, but not when BAM were cocultured with encapsulated M. dispar or purified capsule. When BAM were treated with purified capsule or encapsulated mycoplasmas, they could not be subsequently activated by endotoxin. These results indicate that encapsulated M. dispar or purified capsule exerts an inhibitory effect on the activity of BAM and prevents the activation of these cells.
 ...
PMID:Interaction of Mycoplasma dispar with bovine alveolar macrophages. 161 58

Mycoplasma fermentans-derived high-molecular-weight material (MDHM) was originally discovered because of its capacity to generate, through the induction of monokine synthesis, cytolytic T lymphocytes in concanavalin A-stimulated thymocyte cultures. This study shows that MDHM-activated macrophages not only released interleukin-6 (IL-6) but also exhibited increased synthesis of cell-associated IL-1 as well as liberation of tumor necrosis factor and prostaglandin. We determined 6-keto prostaglandin F1 alpha since it is the stable metabolite of the bioactive prostacyclin. MDHM appeared to be as potent as lipopolysaccharide in inducing the synthesis of these mediators. Priming with gamma interferon further increased MDHM-mediated IL-6 release. Since monokines can be pyrogenic, we tested the effects of an intravenous injection of MDHM on rectal temperatures and leukocyte counts in rabbits. At 1 h after a bolus injection of MDHM, leukocyte counts dropped to about 35% of the initial values, reflecting a decrease in both lymphocytes and granulocytes. At 4 to 6 h after injection, granulocyte counts began to increase again, whereas lymphocyte counts remained low. No leukocytosis was noted during this time. The lack of leukocytosis can be explained by the failure of MDHM-stimulated macrophages to release IL-1. The property of MDHM to cause IL-6 release from macrophages and the IL-6 growth dependency of the 7TD1 hybridoma cell line were made use of in a coculture assay system to quantitate the activity of MDHM. With this method and macrophages from C3H/HeJ lipopolysaccharide-nonresponder mice, MDHM activity was found to be equally distributed in the mycoplasma growth medium and the sedimented mycoplasmas after sonication.
 ...
PMID:MDHM, a macrophage-stimulatory product of Mycoplasma fermentans, leads to in vitro interleukin-1 (IL-1), IL-6, tumor necrosis factor, and prostaglandin production and is pyrogenic in rabbits. 193 55

We and other investigators have previously demonstrated that mycoplasmas induce macrophage-mediated lysis of tumor cells, but the mechanism responsible for this process had, thus far, not been clarified. We now report that addition of either viable or heat-killed Mycoplasma orale to murine macrophages induces a cytolytic activity which, due to its neutralization by a specific antiserum against murine cloned recombinant tumor necrosis factor (rTNF), was identified as TNF-mediated. Both thioglycollate-elicited peritoneal macrophages and the normal macrophages cloned from our JBM phi 1.1 bone-marrow-derived cell line effectively produced TNF at levels similar to, or higher than, those obtained in the presence of high concentrations of lipopolysaccharide (LPS). Four other mycoplasma species demonstrated a varied capacity to induce TNF production by macrophages. Elevated TNF levels were also observed during macrophage-mediated cytolysis of murine A9 fibrosarcoma cells in the presence of either M. orale or LPS. Addition of the specific antiserum against rTNF at a concentration which neutralized all TNF activity in the co-cultures partially inhibited concomitant A9 cell killing. We can, therefore, conclude that M. orale induces TNF production which is, at least partially, responsible for subsequent tumor cell killing.
 ...
PMID:Tumor necrosis factor as a mediator of Mycoplasma orale-induced tumor cell lysis by macrophages. 272 Jul 90

It has been reported that mycoplasma-infected cells are more sensitive to lysis by natural cytotoxic (NC) effector cells and that splenic NC cells release tumor necrosis factor (TNF-alpha) when they lyse sensitive target cells. Here we showed that spleen cells released TNF-alpha when they were incubated with NC-sensitive cells that were infected with mycoplasmas or when they were incubated with mycoplasmas alone, but did not release TNF-alpha when incubated with NC-sensitive cells that were not infected with mycoplasmas. Thus, in the presence of mycoplasmas, spleen cell cultures contain both NC effector cells and free TNF-alpha. Because NC-sensitive cells are also sensitive to free TNF-alpha, when mycoplasma-infected cells were incubated with spleen cells, they were lysed by the combination of NC cells and free TNF-alpha. When NC-sensitive cells that were not infected with mycoplasmas were incubated with spleen cells, they were lysed only by NC effector cells and thus appeared to be less sensitive than mycoplasma-infected cells. These results also suggested that the release of TNF-alpha may be part of a host protective response to mycoplasmas.
 ...
PMID:Effect of mycoplasmas on natural cytotoxic activity and release of tumor necrosis factor alpha by spleen cells. 318 71

We find a strong synergism between tumor necrosis factor (TNF) and bacteria or their products. Endotoxin-"free" recombinant TNF, even at very high doses (160 micrograms), did not alone cause hemorrhagic necrosis (HN) in the skin of normal mice. Similarly, TNF alone had a low systemic toxicity in tumor- and pathogen-free mice. However, TNF given intravenously with nanogram quantities of the endotoxin lipopolysaccharide caused lethal shock. Furthermore, subcutaneous injection of lipopolysaccharide made skin susceptible to subsequent induction of HN by TNF injected in the same site 24 hr later. Mycoplasma-infected cells or corynebacteria also synergized with TNF to cause HN or lethal shock. In addition, we find that lymphotoxin, a cytokine functionally and genetically related to TNF, also synergized with the bacteria to cause HN, whereas interleukin 1 alpha or interferon gamma did not. Together, the results indicate that a synergy between TNF and bacteria or their products causes HN and lethal shock in normal mice.
 ...
PMID:Synergy between tumor necrosis factor and bacterial products causes hemorrhagic necrosis and lethal shock in normal mice. 342 44

Mycoplasma fermentans is one of several Mycoplasma species that have been reported to stimulate tumor necrosis factor (TNF) secretion from monocytes. This activity has been associated primarily with the mycoplasma membrane fraction. In this article, we have characterized a membrane protein that stimulates TNF and interleukin 1 beta secretion. The TNF-releasing activity partitioned into the Triton X-114 detergent phase, suggesting that the molecules is hydrophobic. The secretion of TNF is elevated in the presence of serum, which suggests that a serum component may play a role in the interaction between this mycoplasma protein and monocytes. Treatment of monocytes with monoclonal anti-CD14 antibody had no effect on the levels of TNF-releasing activity. By using the monocyte Western blot (immunoblot) technique, we have determined the molecular mass of the active molecule to be 48 kDa. This molecule appears to be distinct from the recently described family of variable lipoproteins of M. fermentans. Mycoplasma particulate material treated with proteinase K lost all inducing activity, whereas lipoprotein lipase-treated samples retained some level of activity.
 ...
PMID:A 48-kilodalton Mycoplasma fermentans membrane protein induces cytokine secretion by human monocytes. 752 Apr 21

The same cytokines that have been implicated in the pathology of central nervous system (CNS) inflammatory diseases and demyelinating diseases are also associated with the induction of nitric oxide (NO) production by macrophages and other somatic cells. Recently we have showed that mycoplasma can trigger the production of tumor necrosis factor (TNF)alpha and eicosanoids in rat astrocytes. In the present study, the effect of mycoplasma on NO production in rat glial cells was assessed. The addition of 10 micrograms/ml of membranes derived from M. capricolum (sheep isolate), M. fermentans (human isolate), or lipopolysaccharide (LPS) led to a 15- to 20-fold increase in NO production. The glucocorticoids dexamethasone and corticosterone, but not progesterone, markedly inhibited NO production. The addition of glucocorticoid prior or conjointly with the activator prevented large amounts of NO from being formed. Even when glucocorticoids were added 5 or 24 h after activation, effective inhibition of NO production was obtained. Thus, it is likely that glucocorticoids exert some of their ameliorating effects in neurological diseases by reducing the production of NO, cytokines and prostaglandins in the CNS.
 ...
PMID:Mycoplasma triggering of nitric oxide production by central nervous system glial cells and its inhibition by glucocorticoids. 801 51

Mycoplasmal products may exert a number of diverse in vitro effects on cells of the immune system. A macrophage-activating substance from Mycoplasma fermentans was described in this laboratory and named mycoplasma-derived high-molecular-weight material (MDHM). Using synthesis of nitric oxide by peritoneal cells from endotoxin low-responder mice as an assay system, MDHM was purified as follows. After freeze-thawing of M. fermentans, MDHM activity was sedimented with the membrane fraction. Membranes were delipidated with chloroform-methanol, and MDHM activity was extracted with octyl glucoside. Coextracted proteins were degraded by proteinase K. MDHM was further purified by reversed-phase high-pressure liquid chromatography and eluted in one major and one minor peak of activity. Neither carbohydrates nor amino acids were found as constituents. MDHM had the following properties: it partitioned into the phenol phase upon phenol-water extraction and into the Triton phase after extraction with Triton X-114. MDHM was not inactivated by either phospholipase A2 or triglyceride lipases. However, mild periodate treatment led to a > 95% loss of activity. Also, alkaline hydrolysis at 25 degrees C completely abolished MDHM activity with a half-life of 2 min. MDHM activity was spread out over a wide molecular weight range upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis of membranes, whereas after proteinase treatment MDHM activity migrated close to the front. These features of MDHM, taken together, speak in favor of an amphiphilic molecule with a lipid moiety carrying fatty acids in ester linkage and a polyol moiety of unknown character. MDHM was active in the nanogram-per-milliliter range, activating macrophages to release nitric oxide, interleukin-6, and tumor necrosis factor.
 ...
PMID:Purification and partial biochemical characterization of a Mycoplasma fermentans-derived substance that activates macrophages to release nitric oxide, tumor necrosis factor, and interleukin-6. 806 96


1 2 3 4 5 6 7 8 9 Next >>