Mycoplasma fermentans MALP-2 induces heme oxygenase-1 expression via mitogen-activated protein kinases and Nrf2 pathways to modulate cyclooxygenase 2 expression in human monocytes

Heme oxygenase-1 (HO-1) is a stress-inducible rate-limiting enzyme in heme degradation that confers cytoprotection against oxidative injury and performs a vital function in the maintenance of cell hemostasis. Increasing numbers of reports have indicated that mycoplasma-derived membrane lipoproteins/lipopeptides, such as macrophage-activating lipopeptide-2 (MALP-2), function as agents that stimulate the immune system by producing various inflammatory mediators, such as cytokines and cyclooxygenase 2 (COX-2), which play roles in the pathogenesis of inflammatory responses during mycoplasma infection. Here, we report that MALP-2 induced HO-1 mRNA and protein expression and upregulated HO-1 enzyme activity in THP-1 cells. Specific inhibitors of mitogen-activated protein kinases (MAPKs), SB203580, PD98059, and SP600125, significantly abolished HO-1 expression. In addition, MALP-2 also induced NF-E2-related factor 2 (Nrf2) translocation, and the silencing of Nrf2 expression in THP-1 cells decreased the levels of MALP-2-mediated HO-1 expression. Furthermore, COX-2 protein expression levels were upregulated in THP-1 cells in response to MALP-2, and transfection with small interfering RNAs of HO-1 significantly increased COX-2 accumulation. These results demonstrate that MALP-2 induces HO-1 expression via MAPKs and Nrf2 pathways and, furthermore, that MALP-2-induced COX-2 expression was modulated by HO-1 in THP-1 cells.

Antibodies to various mycoplasmas in patients with coronary heart disease

BACKGROUND

Clinical and epidemiologic features of coronary heart disease may not be explained solely by established risk factors. The role of infectious pathogens in the development and rupture of atherosclerotic plaques remains elusive but an association between Chlamydia pneumoniae, Mycoplasma pneumoniae and CHD has been reported previously.

OBJECTIVES

To determine whether there is an association between mycoplasmal infections and CHD.

METHODS

We conducted a prospective cohort analysis of 150 consecutive hospitalized patients with CHD (85 with acute coronary syndrome and 65 admitted for unrelated reasons) and 98 healthy blood donors. Antibody titers for Mycoplasma pneumoniae, M. fermentans, M. hominis and Ureaplasma urealyticum were measured with the agglutination test or specific enzyme-linked immunosorbent assay in all three groups of patients.

RESULTS

Analysis of the antibody titers did not reveal any significant difference in the presence of mycoplasmal antibodies between the patients with ACS, patients with known stable CHD hospitalized for non-CHD reasons, and healthy blood donors.

CONCLUSIONS

Determination of specific antibodies did not reveal a significant association among different types of mycoplasmal infection and CHD.

HLA-Independent Antibacterial Host Response toward Th1 Immunity Mediated by IL-12: a New Concept for the Pathogenesis of Adamantiades–Behçet's Disease

Yanagihori et al. found an HLA-independent higher frequency of IL-12B promoter polymorphism in Adamantiades-Behçet's disease (ABD) patients than in controls. Stimulation with streptococcal antigens specifically increased expression of patients' peripheral blood mononuclear cells IL-12 p40/p70. The authors provide evidence for an antibacterial host response toward T-helper type 1 immunity mediated by IL-12 in patients with ABD, which is HLA independent.

[Frequency of different infectious agents persistence in mononuclear leukocytes of blood and synovial fluid in patients with rheumatoid arthritis]

The study of persistence in mononuclear leukocytes (ML) of blood and synovial fluid of 218 patients with rheumatoid arthritis (RA) Cytornegalovirus (CMV), the 1-st and 2-nd types of Herpes virus simplex (VH), Epstain-Barr virus (VEB), Mycoplasma arthritidis (Ma), Mycoplasma fermentans (Mf), Ureaplasma urealiticum (U), Chlamidia trachomatis (Ct), viruses of Hepatitis B and C was carry out by direct and indirect immunofruorescence, immunoenzymatic analysis and polymerase chain reaction. An increased frequency of contamination of blood ML with infectious agents in patients with RA was established (57,4% compared with 16,7% in control group). The following infectious agents were revieled more frequently: in ML of blood and synovial fluid the Ma (relatively 20,5% and 15,9%), Mf (15,6% and 13,2%), Ct (18,4% and 13,2%), VH (27,1% and 10,5%), VEB (12,7% and 5,3%) and CMV (11,2% and 7,9%). Types of frequency dynamics of ML contamination with these infectious agents in different time phases of RA were determined.

Production of prostaglandin E2 in monocytes stimulated in vitro by Chlamydia trachomatis, Chlamydophila pneumoniae, and Mycoplasma fermentans

Chlamydia trachomatis (CT) as well as Chlamydophila pneumoniae (CP) cause chronic inflammatory diseases in humans. Persistently infected monocytes are involved in the pathogenesis by inducing mediators of inflammation. An in vitro system of chlamydial persistence in human peripheral blood monocytes (HPBM) was used to investigate prostaglandin E(2) (PGE(2)) production and the expression of the key enzyme for prostaglandin production, cyclooxygenase-2 (COX-2). PGE(2) production was determined by PGE(2)-ELISA of HPBM-culture supernatants. Cox-2 mRNA expression was measured by real-time RT-PCR of total RNA isolated from HPBM. Both, CT and CP, stimulated PGE(2) production of HPBM in vitro. Equivalent numbers of CT per host cell induced a higher PGE(2)-response compared to CP. The amount of synthesized PGE(2) depended on the chlamydial multiplicity of infection (MOI). Even at an MOI of 10 the amount of CT- and CP-induced prostaglandin, respectively, was lower than the amount of prostaglandin induced by E. coli lipopolysaccharide (LPS) at a concentration of 10microg/ml. In contrast to stimulation with LPS, Chlamydia-induced PGE(2) production as well as cox-2 mRNA decreased after day 1 post infection (p.i.). These data indicate that Chlamydia stimulate PGE(2) production in human monocytes. Since Chlamydia are often contaminated by mycoplasma, the influence of mycoplasma on the prostaglandin production was investigated additionally. Mycoplasma fermentans (MF) also stimulated PGE(2) production. The co-infection of mycoplasma and Chlamydia resulted in an additive effect in the production of PGE(2). Thus it is important to use host cells and Chlamydia free of mycoplasma contamination for the analysis of Chlamydia-induced prostaglandin production.

Relationship between structures and biological activities of mycoplasmal diacylated lipopeptides and their recognition by toll-like receptors 2 and 6

The lipopeptide FSL-1 [S-(2,3-bispalmitoyloxypropyl)-Cys-Gly-Asp-Pro-Lys-His-Pro-Lys-Ser-Phe, Pam(2)CGDPKHPKSF] synthesized on the basis of the N-terminal structure of a Mycoplasma salivarium lipoprotein capable of activating normal human gingival fibroblasts to induce the cell surface expression of ICAM-1 revealed an activity to induce production of monocyte chemoattractant protein 1, interleukin-6 (IL-6), and IL-8. FSL-1 also activated macrophages to produce tumor necrosis factor alpha as the Mycoplasma fermentans-derived lipopeptide MALP-2 (Pam(2)CGNNDESNISFKEK), a potent macrophage-activating lipopeptide, did. The level of the activity of FSL-1 was higher than that of MALP-2. This result suggests that the difference in the amino acid sequence of the peptide portion affects the activity because the framework structure other than the amino acid sequence of the former is the same as that of the latter. To determine minimal structural requirements for the activity of FSL-1, the diacylglyceryl Cys and the peptide portions were examined for this activity. Both portions did not reveal the activity. A single amino acid substitution from Phe to Arg and a fatty acid substitution from palmitic acid to stearic acid drastically reduced the activity. Similar results were obtained in measuring the NF-kappaB reporter activity of FSL-1 to human embryonic kidney 293 cells transfected with Toll-like receptor 2 and 6, together with a NF-kappaB-dependent luciferase reporter plasmid. These results suggest that both the diacylglyceryl and the peptide portions of FSL-1 are indispensable for the expression of biological activities and for the recognition by Toll-like receptors 2 and 6 and that the recognition of FSL-1 by Toll-like receptors 2 and 6 appears to be hydrophobic.

In Vivo Immunomodulation by Mycoplasma fermentans Membrane Lipoprotein

The immunomodulatory effects of Mycoplasma fermentans-derived membrane lipoprotein (LAMPf) in BALB/c mice were examined. When injected intraperitoneally into mice, LAMPf induced a transitory splenomegaly followed by a suppression of the spleen cell proliferation in response to concanavalin A, whereas responses to lipopolysaccharide and to LAMPf were unchanged. The intravenous injection of a large dose of LAMPf induced leukopenia and granulocyte-macrophage colony-stimulating factor (GM-CSF) activity in serum. A synthetic analogue of its N-terminal lipopeptide with ability to activate macrophages (MALP-2) was also able to induce GM-CSF in serum. Interestingly, GM-CSF induction by a low dose of MALP-2 was not associated with significant leukopenia. These data revealed that the in vitro moduline properties of mycoplasmal lipoproteins and lipopeptides correlate with interesting in vivo immunomodulatory effects.

A lipoprotein family from Mycoplasma fermentans confers host immune activation through Toll-like receptor 2

Mycoplasma have been reported to be associated with human diseases. Three forms of a mycoplasma lipopeptide/protein with the ability to modulate the host immune system were independently identified and named macrophage-activating lipopeptide 2 (MALP-2), P48 and M161Ag (identical to MALP-404). Although these molecules had polypeptides of different sizes, they exerted similar immunomodulatory effects on macrophages/dendritic cells, such as cytokine induction, NO production and maturation of antigen-presenting cells (APCs). M161Ag exhibited complement-activating ability and bound macrophages via complement C3b/C3bi and their receptors. The diacylated N-terminal palmitates were involved in these activities. Toll-like receptor 2 (TLR2) was found to be responsible for these functional features of these mycoplasma products, except for complement activation. Here, we summarize the functional properties of this family of proteins, namely pathogen-associated molecular pattern (PAMP) and discuss its relationship to the reported pathogenesis of latent mycoplasma infection.

A variety of microbial components induce tolerance to lipopolysaccharide by differentially affecting MyD88-dependent and -independent pathways

Exposure of macrophages to lipopolysaccharide (LPS) induces a hypo-responsive state to a second challenge with LPS that is termed LPS tolerance. LPS tolerance is also induced by pre-exposure to lipopeptides and lipoteichoic acid, which trigger Toll-like receptor (TLR) 2-mediated signaling. LPS signaling involves at least two pathways: a MyD88-dependent cascade that is essential for production of inflammatory cytokines and a MyD88-independent cascade that mediates the expression of IFN-inducible genes. We analyzed the induction of LPS tolerance by several microbial components in mouse peritoneal macrophages. Pre-exposure to LPS led to impaired activation of both the pathways. In contrast, mycoplasmal lipopeptides did not affect the MyD88-independent pathway, but impaired the MyD88-dependent signaling by inhibiting LPS-mediated activation of IL-1 receptor-associated kinase (IRAK) 1. The induction of LPS tolerance by recently identified TLR ligands was analyzed. Pretreatment with double-stranded RNA, which triggers the activation of TLR3, led to defective activation of the MyD88-independent, but not the MyD88-dependent, pathway. Imidazoquinoline compounds, which are recognized by TLR7, had no effect on the MyD88-independent pathway, but inhibited LPS-induced activation of MyD88-dependent signaling through down-regulation of IRAK1 expression. Thus, each microbial component induced LPS tolerance in macrophages.

In vivo effects of a synthetic 2-kilodalton macrophage-activating lipopeptide of Mycoplasma fermentans after pulmonary application

Mycoplasmas can cause interstitial pneumonias inducing critical illness in humans and animals. Mycoplasma infections are characterized by an influx of neutrophils, followed by an accumulation of macrophages and lymphocytes. The present study deals with the question of which mycoplasmal components cause this host reaction. The mycoplasma-derived, macrophage-activating lipopeptide 2S-MALP-2 was used to mimic the sequelae of a mycoplasma infection. To this end, 2S-MALP-2 was intratracheally instilled into the lungs of Lewis rats, and the bronchoalveolar lavage cells were examined at different times after different doses of 2S-MALP-2. Application of 2.5 microg induced a pronounced leukocyte accumulation in the bronchoalveolar space. At 24 h after 2S-MALP-2 administration, the majority of leukocytes consisted of neutrophils, followed by macrophages, peaking on days 2 and 3. Lymphocyte numbers, although amounting to only a few percent of the total bronchoalveolar lavage cells, also increased significantly, with maximal lymphocyte accumulation occurring by 72 h after instillation. The leukocyte count of the lung interstitium was increased on day 3 after treatment. After 10 days all investigated cell populations returned to control levels. Transient chemotactic activity for neutrophils was detected in the bronchoalveolar lavage fluid early after 2S-MALP-2 application, followed by monocyte chemoattractant protein-1 activity (MCP-1) in lung homogenates. MCP-1 was produced by bronchoalveolar lavage cells upon stimulation with 2S-MALP-2. Our data indicate that mycoplasmal lipoproteins and lipopeptides are probably the most relevant mycoplasmal components for the early host reaction. The primary target cells are likely to be the alveolar macrophages liberating chemokines, which attract further leukocytes.

A 4.1-kilodalton polypeptide in the cultural supernatant of Mycoplasma fermentans is one of the substances responsible for induction of interleukin-6 production by human gingival fibroblasts

The cultural supernatant of Mycoplasma fermentans induced interleukin-6 production by human gingival fibroblasts. The active entities were divided into hydrophilic and hydrophobic substances. In this study, we purified a 4.1-kilodalton polypeptide from the hydrophilic substances. It reacted with polyclonal antibodies to M. fermentans and activated human macrophages.

[Molecular mimicry of bacterial polysaccharides and their role in etiology of infectious and autoimmune diseases]

Molecular mimicry is one of the most important pathogenic factor of microorganism and is defined as a structural similarity of microbial molecules to host tissue contributing to the pathogenicity. Mimicry can be observed at the molecular, serological and functional level. In the review the infectious diseases have been discussed where the mimicry phenomenon may occur, and also autoimmune disease where due to the molecular mimicry bacterial structures are potent to induce adverse immune reactions. The cross-reacting molecules mimicking the host structures comprise colominic acid, sialic acid containing capsular polysaccharides of Streptococcus group B, phosphocholine containing antigen, lipopolysaccharides of Campylobacter jejuni contributing in induction of Guillain-Barré syndrome or Lewis antigen containing lipopolysaccharides of Helicobacter pylori inducing gut carcinoma. Knowledge on the phenomenon of molecular mimicry is important when new conjugate vaccine has to be constructed, because great care should be paid not to induce autoantibodies with synthetic immunogen. Investigation of microbial factors reveal that many autoimmune diseases are of infection etiology.

Monoclonal antibody against Mycoplasma fermentans-specific aminoglycoglycerolipid

Previously, we reported that Mycoplasma fermentans has specific antigens (phosphocholine-containing glycoglycerolipids: GGPL-I and GGPL-III) and discussed the possibility of their pathogenic role. In this paper, we report the characterization of a monoclonal antibody (MF-III-1) specific to GGPL-III (phosphocholine-containing aminoglycoglycerolipid) using methods of electron microscopy, immunofluorescence cell surface staining, laser scanning microscopy, immunoelectron microscopy, and thin-layer chromatography immunostaining. The MF-III-1 antibody specifically recognized M. fermentans attached to the surface of HTLV-I-infected human helper T-cells, and it did not cross-react with other lipids nor with human T-cell antigens. Since MF-III-1 distinguishes GGPL-III from GGPL-I, the binding site may include a serinol (2-amino-1,3-propanediol) residue of GGPL-III. MF-III-1 is useful for the in vitro study of M. fermentans, and may also be useful as a tool for the study of the involvement of M. fermentans in human diseases.

Mycoplasma fermentans lipoprotein M161Ag-induced cell activation is mediated by Toll-like receptor 2: role of N-terminal hydrophobic portion in its multiple functions

M161Ag is a 43-kDa surface lipoprotein of Mycoplasma fermentans, serving as a potent cytokine inducer for monocytes/macrophages, maturing dendritic cells (DCs), and activating host complement on affected cells. It possesses a unique N-terminal lipo-amino acid, S:-diacylglyceryl cysteine. The 2-kDa macrophage-activating lipopeptide-2 (MALP-2), recently identified as a ligand for Toll-like receptor 2 (TLR2), is derived from M161Ag. In this study, we identified structural motifs sustaining the functions of M161Ag using wild-type and unlipidated rM161Ag with (SP(+)) or without signal peptides (SP(-)). Because the SP(+) rM161Ag formed dimers via 25Cys, we obtained a monomeric form by mutagenesis (SP(+)C25S). Only wild type accelerated maturation of human DCs as determined by the CD83/86 criteria, suggesting the importance of the N-terminal fatty acids for this function. Wild-type and the SP(+) form of monomer induced secretion of TNF-alpha and IL-12 p40 by human monocytes and DCs. Either lipid or signal peptide at the N-terminal portion of monomer was required for expression of this function. In contrast, murine macrophages produced TNF-alpha in response to wild type, but not to any recombinant form of M161Ag, suggesting the species-dependent response to rM161Ag. Wild-type and both monomeric and dimeric SP(+) forms possessed the ability to activate complement via the alternative pathway. Again, the hydrophobic portion was associated with this function. These results, together with the finding that macrophages from TLR2-deficient mice did not produce TNF-alpha in response to M161Ag, infer that the N-terminal hydrophobic structure of M161Ag is important for TLR2-mediated cell activation and complement activation.

Effect of Mycoplasma fermentans on brain PGE(2): role of glucocorticoids and their receptors

OBJECTIVES

Mycoplasmas are a group of eubacteria, which cause various diseases in animals and in humans, and can contribute to diseases produced by other infectious agents, particularly HIV. We have recently reported that intracerebral administration of Mycoplasma fermentans (MF) produces both neuroendocrine and behavioral alterations. Some of these responses were mediated by MF-induced production of prostaglandin E(2 )(PGE(2)). The aim of this study was to examine the role of glucocorticoids (GC) in regulating MF-induced brain prostaglandin production.

METHODS

Male rats were injected intracerebroventricularly with various doses of heat-inactivated MF, LPS or IL-1 beta and the following parameters were measured: (1) ex vivo production of hippocampal PGE(2), (2) serum levels of ACTH and corticosterone, and (3) binding capacity of [(3)H]-dexamethasone (DEX) to hippocampal cytosol.

RESULTS

MF caused a small increase in hippocampal PGE(2) production, but higher doses failed to produce a further increase. In contrast, the effects of LPS or IL-1 beta on PGE(2) were dose-dependent. Removal of circulating GC by bilateral adrenalectomy significantly enhanced MF-induced brain PGE(2) production. The three immune stimulators increased serum levels of ACTH and corticosterone to the same extent. Finally, MF, but not IL-1 beta increased the specific binding of [(3)H]-DEX to hippocampal cytosol.

CONCLUSIONS

Brain PGE(2) induced by MF is regulated by endogenous GC. These hormones have an attenuating effect on PGE(2 )production, probably through an MF-induced increase in GC binding by brain tissue. This mechanism may be important in the pathological effect of MF within the brain of AIDS patients.

Lack of serological evidence for Mycoplasma fermentans infection in army Gulf War veterans: a large scale case-control study

Mycoplasma firmentans is suspected in the development of 'Gulf War illness' in veterans of Operation Desert Storm. We conducted a matched case-control study for the prevalence of M. firmentans-specific antibodies before and after the operation, as well as seroconversion rates in veterans with and without complaints of 'Gulf War illness'. Cases consisted of Gulf War veterans, who complained of various illnesses and were enrolled in the second phase of the health evaluation by the Army Comprehensive Clinical Examination Program (CCEP). Controls were selected from Gulf War veterans who did not participate in the registry and did not request a health evaluation by the CCEP. Before operation deployment, 34 out of 718 of the cases (48%) and 116 out of 2233 of the controls (5.2%) tested positive for M. fermentans-specific antibodies. There was no difference in rates of seroconversion between cases and controls (1.1 vs. 1.2%) to M. fermentans during Operation Desert Storm. Thus, there is no serological evidence that suggests infectionby M. fermentans is associated with development of 'Gulf War illness'.

Mycoplasma fermentans interaction with monocytes/macrophages: molecular basis

Mycoplasmas are the smallest free-living self-replicating bacteria - having diameters of 200 to 800 nm - widely distributed in animals and plants. Mycoplasma fermentans is a human pathogen suspected to be involved in the progression of autoimmune diseases. Although pathogenesis mechanisms of M. fermentans are currently poorly understood, the role of these microorganisms as immunomodulatory agents is well established. In the present paper, we will review and discuss recent breakthroughs in the field.

Complement activation in Mycoplasma fermentans-induced mycoplasma clearance from infected cells: probing of the organism with monoclonal antibodies against M161Ag

Mycoplasma fermentans, a cell wall-less prokaryote, is capable of infecting humans and has been suggested to serve as a cofactor in AIDS development. Recently, we discovered a novel lipoprotein with a molecular mass of 43 kDa originating from M. fermentans. This protein, named M161Ag, activated human complement via the alternative pathway and efficiently induced the proinflammatory cytokines interleukin 1beta (IL-1beta), tumor necrosis factor alpha, IL-6, IL-10, and IL-12 in human peripheral blood monocytes. It is likely that M161Ag of M. fermentans affects the host immune system upon mycoplasma infection. In this study, we developed monoclonal antibodies (MAbs) against M161Ag and examined the direct role of complement in M. fermentans infection using these MAbs as probes. M. fermentans was rapidly cleared from the surfaces of infected cells by human complement, but a low-grade infection persisted in human tumor cell lines. Mycoplasma particles remaining alive in host cells may cause recurrent infection, and liberated M161Ag may serve as a biological response modifier affecting both innate and acquired immunity.

Cutting edge: preferentially the R-stereoisomer of the mycoplasmal lipopeptide macrophage-activating lipopeptide-2 activates immune cells through a toll-like receptor 2- and MyD88-dependent signaling pathway

Mycoplasmas and their membranes are potent activators of macrophages, the active principle being lipoproteins and lipopeptides. Two stereoisomers of the mycoplasmal lipopeptide macrophage-activating lipopeptide-2 (MALP-2) differing in the configuration of the lipid moiety were synthesized and compared in their macrophage-activating potential, the R-MALP being >100 times more active than the S-MALP in stimulating the release of cytokines, chemokines, and NO. To assess the role of the Toll-like receptor (TLR) family in mycoplasmal lipopeptide signaling, the MALP-2-mediated responses were analyzed using macrophages from wild-type, TLR2-, TLR4-, and MyD88-deficient mice. TLR2- and MyD88-deficient cells showed severely impaired cytokine productions in response to R- and S-MALP. The MALP-induced activation of intracellular signaling molecules was fully dependent on both TLR2 and MyD88. There was a strong preference for the R-MALP in the recognition by its functional receptor, TLR2.

Immunoelectrophoretic analysis of medium-derived antigens bound to the surface of Mycoplasma hominis, Mycoplasma fermentans and Ureaplasma urealyticum

We analyzed Mycoplasma hominis, Mycoplasma fermentans and Ureaplasma urealyticum antigens by immunochemical methods. The immunochemical reaction showed that all three species bound to the surface of one medium component, which origin stemmed from the horse serum. This substance functioned as one of the most potent components of mycoplasma immunogens for all three species.

P48 major surface antigen of Mycoplasma agalactiae is homologous to a malp product of Mycoplasma fermentans and belongs to a selected family of bacterial lipoproteins

A major surface antigenic lipoprotein of Mycoplasma agalactiae, promptly recognized by the host's immune system, was characterized. The mature product, P48, showed significant similarity and shared conserved amino acid motifs with lipoproteins or predicted lipoproteins from Mycoplasma fermentans, Mycoplasma hyorhinis, relapsing fever Borrelia spp., Bacillus subtilis, and Treponema pallidum.

No serologic evidence of an association found between Gulf War service and Mycoplasma fermentans infection

Occult occupational infection with Mycoplasma fermentans has been proposed as a cause for illness among Persian Gulf War veterans. Symptom data and sera from a 1994-1995 cross-sectional survey of Navy Seabees were used to select symptomatic and asymptomatic Gulf War veterans and nondeployed veterans to evaluate this hypothesis. Survey sera from 96 Seabees were matched to prewar (before September 1990) archived sera. Immunoblot serologic analyses were performed for M. fermentans in a controlled, blinded fashion. Both Gulf War veterans and nondeployed veterans had prewar and postwar serologic evidence of M. fermentans infection consistent with natural infection data. Among study subjects collectively, and stratified by Gulf War service, none of the immunoblot banding profiles (prewar or postwar) or their changes over time were associated with postwar symptoms. These serologic data do not support the hypothesis that Gulf War veterans have experienced Gulf War-related morbidity from M. fermentans infection.

Signal transduction pathways involved in the activation of NF-kappa B, AP-1, and c-fos by Mycoplasma fermentans membrane lipoproteins in macrophages

Mycoplasma fermentans-derived membrane lipoproteins (LAMPf) have been demonstrated to stimulate monocytic cells and to induce the secretion of proinflammatory cytokines by a mechanism involving the triggering of protein tyrosine kinase and mitogen-activated protein kinase cascades. Herein, we have examined the effects of LAMPf on the activation of a series of transcription factors potentially involved in cytokine gene expression. LAMPf was capable of inducing NF-kappa B, activated protein 1 (AP-1), and c-fos activation in macrophages and of stimulating NF-kappa B and AP-1 transactivation. Furthermore, we have delineated the contribution of each mitogen-activated protein kinase pathway to the LAMPf-mediated activation of AP-1, c-fos, and NF-kappa B. Whereas the selective extracellular signal-regulated kinase pathway inhibitor PD-98059 did not affect the LAMPf-mediated transactivation of AP-1, c-fos, or NF-kappa B, the specific p38 inhibitor SB203580 abrogated this activity. A c-Jun N-terminal kinase-dominant negative was shown to block the activation of AP-1 without altering NF-kappa B or c-fos activation by LAMPf. In addition, D609, a selective inhibitor of phosphatidylcholine-specific phospholipase C, was shown to block both translocation and transactivation of either NF-kappa B or AP-1 in response to LAMPf. Although LAMPf-mediated macrophage activation is CD14 independent, we could not distinguish between the intracellular mechanisms leading to the macrophage activation triggered by either LPS or LAMPf. This suggests that macrophages display a common signaling machinery leading to the secretion of proinflammatory cytokines in response to different bacterial products. The comprehension of these mechanisms may help to better understanding the bacterial pathogenesis and to elucidate general mechanisms of macrophage activation leading to cytokine secretion.

Involvement of mitogen-activated protein kinase pathways in interleukin-8 production by human monocytes and polymorphonuclear cells stimulated with lipopolysaccharide or Mycoplasma fermentans membrane lipoproteins

Interleukin-8 (IL-8) is a chemokine that belongs to the alpha-chemokine or CXC subfamily and is produced by a wide variety of human cells, including monocytes and polymorphonuclear cells (PMN). IL-8 is secreted in response to inflammatory stimuli, notably bacterial products such as lipopolysaccharide (LPS), but little is known about the mechanisms by which these agents mediate IL-8 induction. In this report, we show that Mycoplasma fermentans lipid-associated membrane proteins (LAMPf) induce the production of high levels of IL-8 by THP-1 (human monocyte) cells and PMN at the same extent as LPS. It was previously demonstrated that stimulation of monocytic cells with either LPS or LAMPf led to a series of common downstream signaling events, including the activation of protein tyrosine kinase and of mitogen-activated protein kinase cascades. By using PD-98059 and SB203580, two potent and selective inhibitors of MEK1 (a kinase upstream of ERK1/2) and p38, respectively, we have demonstrated that both ERK1/2 and p38 cascades play a key role in the production of IL-8 by monocytes and PMN stimulated with bacterial fractions.

Detection of Mycoplasma genus and Mycoplasma fermentans by PCR in patients with Chronic Fatigue Syndrome

Mycoplasma fermentans and other Mycoplasma species are colonizers of human mucosal surfaces and may be associated with human immunodeficiency virus infection. While many infectious agents have been described in different percentages of patients with Chronic Fatigue Syndrome (CFS), little is known about the prevalence of mycoplasmas and especially M. fermentans in CFS patients. A polymerase chain reaction (PCR)-based assay was used to detect Mycoplasma genus and M. fermentans genomes in peripheral blood mononuclear cells (PBMC) of CFS patients. Blood was collected from 100 patients with CFS and 50 control subjects. The amplified products of 717 bp of Mycoplasma genus, and 206 bp of M. fermentans were detected in DNA purified from blood samples in 52% and 34% of CFS samples, respectively. In contrast, these genomes were found in only 14% and 8% of healthy control subjects respectively (P < 0.0001). All samples were confirmed by Southern blot with a specific probe based on internal sequences of the expected amplification product. Several samples, which were positive for Mycoplasma genus, were negative for M. fermentans indicating that other Mycoplasma species are involved. A quantitative PCR was developed to determine the number of M. fermentans genome copies present in 1 microg of DNA for controls and CFS patients. Mycoplasma copy numbers ranging from 130 to 880 and from 264 to 2400 were detected in controls and CFS positive subjects, respectively. An enzyme immunoassay was applied for the detection of antibodies against p29 surface lipoprotein of M. fermentans to determine the relationship between M. fermentans genome copy numbers and antibody levels. Individuals with high genome copy numbers exhibited higher IgG and IgM antibodies against M. fermentans specific peptides. Isolation of this organism by culture from clinical specimens is needed in order to demonstrate specificity of signal detected by PCR in this study.

Mycoplasma fermentans glycolipid triggers inflammatory response in rat astrocytes

Mycoplasma fermentans glycolipid (MfGL-II) is a major lipid in the membranes of this AIDS-associated mycoplasma and constituting up to 20% of the total phospholipids of this organism. It was recently shown that MfGL-II, mainly through its phosphocholine moiety, is responsible for the attachment of M. fermentans to host cells. We now show that MfGL-II is also associated with the secretion of inflammatory mediators by cells of the central nervous system. Stimulation of primary rat astrocytes by MfGL-II caused activation of protein kinase C, secretion of nitric oxide (NO) and prostaglandin E2, and augmented glucose utilization and lactate formation in a dose-dependent manner. In an attempt to define the minimal structural requirements for MfGL-II activity, the two O-acylated fatty acids in the molecule were removed. Deacylation pronouncedly reduced the stimulatory activity of the glycolipid, suggesting that the fatty acyl residues are essential. Incubation of MfGL-II with polyclonal anti-MfGL-II antiserum or with monoclonal anti-phosphocholine antibody diminished NO release, whereas incubation of MfGL-II with normal rabbit serum had no effect. It is, therefore, likely that the terminal phosphocholine moiety plays an important role in MfGL-IIs stimulation of glial cells.

Activation of mitogen-activated protein kinase pathways by Mycoplasma fermentans membrane lipoproteins in murine macrophages: involvement in cytokine synthesis

Stimulation of monocytes and resident macrophages by mycoplasmas induces production of numerous cytokines. We have previously reported that membrane lipoproteins derived from Mycoplasma fermentans are responsible for the induction of proinflammatory cytokines by monocytic cells and that triggering protein tyrosine kinase activation is an essential requirement for this biologic effect. In the present study, we have investigated the effect of M. fermentans-derived membrane lipoproteins (LAMPf) on mitogen-activated protein kinase (MAPK) cascades in the murine macrophage cell line RAW 264.7 and have analyzed the contribution of these pathways to the cytokine induction mediated by this agent. Treatment of murine macrophages with LAMPf resulted in significant activation of MAPK family members extracellular signal-regulated kinase 1 and 2 (ERK1/2), c-Jun NH2-terminal kinase (JNK), and p38. Unlike LPS, these effects were demonstrated to be independent of the presence of serum. The activation of MAPKs paralleled the tyrosine kinase activation and peaked at 30 min after stimulation. The specific p38 inhibitor SB203580 abrogated the mycoplasma-induced IL-6, IL-1beta, and TNF-alpha synthesis. The selective MAPK/extracellular signal-regulated kinase 1 (MEK-1) inhibitor PD-98059 blocked both IL-1beta and TNF-alpha but not IL-6 production by RAW 264.7 cells in response to LAMPf. Additionally, transfection of murine macrophages with a JNK dominant negative mutant significantly reduced only IL-6 production. These data underscore the role of MAPKs as signal transduction molecules controlling the expression of cytokines upon mycoplasma stimulation.

Antibodies to mycoplasma fermentans in HIV-positive heterosexual patients: seroprevalence and association with AIDS

There are conflicting reports concerning the prevalence of Mycoplasma fermentans in HIV-positive patients and its association with AIDS. Serum antibodies to M. fermentans were measured by a modified immunoblotting technique in 48 HIV-positive heterosexual patients and in 30 HIV-negative heterosexual controls. Antibodies to M. fermentans were detected in 19 (40%) of HIV-positive patients and in three (10%) of the HIV-negative controls (P = 0.01). The prevalence of antibodies to Mycoplasma hominis and to Ureaplasma urealyticum was similar in both groups. In the HIV-positive group, 16/19 (84%) M. fermentans-positive patients developed AIDS, compared to eight of 29 (28%) M. fermentans-negative patients (P = 0.0004). The HIV-positive patients with antibodies to M. fermentans had a lower CD4+ cell count and a higher prevalence of antibodies to the other mycoplasma tested (P = 0.007 and P = 0.03, respectively), as compared to the patients without antibodies to M. fermentans. These findings may suggest that the presence of antibodies to M. fermentans indicate an opportunistic infection. Of the 19 M. fermentans-positive patients, 11 were positive on the first examination, and eight became positive during the follow-up period. Seven out of these eight patients developed antibodies to M. fermentans before the development of AIDS. Therefore, the possibility exists that M. fermentans might influence the development of AIDS.

Detection of serum antibodies against phosphocholine-containing aminoglycoglycerolipid specific to Mycoplasma fermentans in HIV-1 infected individuals

Mycoplasma fermentans has been associated with acquired immunodeficiency syndrome (AIDS). The lipids extracted from five strains of M. fermentans and eight other species of mycoplasmas were investigated. By using high-performance thin-layer chromatography (HPTLC) and immunostaining on HPTLC-plates with polyclonal and monoclonal antibodies against lipids of M. fermentans, a glycophospholipid GGPL-III was proved to be a specific lipid and important antigen of the species of M. fermentans. Previously we reported that M. fermentans had phosphocholine-containing glycoglycerolipid (GGPL-I and GGPL-III). TLC immunostaining showed that anti-GGPL-III specific antibodies were detected in HIV-1 infected individuals. By employing purified GGPL-III, an enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of specific antibodies to GGPL-III in human serum. This ELISA showed high sensitivity, specificity and good reproducibility. Frequency of antibodies to GGPL-III was significantly higher in sera from HIV-1 infected people (44.6%, 29/65) than from HIV-1 negative healthy donors (1.7%, 2/117) or patients with three kinds of other diseases we investigated (0-8.7%, 0/20-2/23). Thus M. fermentans infection seemed to be correlated with HIV-1 infection although further investigation is essential for clarification of the role of M. fermentans during the long latency period in HIV infected individuals.

Antibody response to MfGL-II, a phosphocholine-containing major lipid of Mycoplasma fermentans membranes

The choline-containing phosphoglycolipid, MfGL-II, is the major polar lipid of Mycoplasma fermentans PG18. Anti-MfGL-II antisera raised in rabbits using the purified MfGL-II as an immunogen were employed in immunogold electron microscopic and immunofluorescence studies showing that MfGL-II is uniformly distributed and exposed on the cell surface of M. fermentans cells. The specificity of the antibodies was determined by immunostaining of lipid extracts separated by thin layer chromatography. The antibodies recognize lipids specific to M. fermentans but did not cross-react with lipid extracts of M. penetrans, M. capricolum, M. gallisepticum or Acholeplasma laidlawii. As phosphocholine almost completely abolished antibody interaction with MfGL-II in an ELISA assay it is suggested that the anti-MfGL-II repertoire is composed primarily of anti-phosphocholine antibodies. The anti-MfGL-II antisera inhibit the attachment of M. fermentans to Molt-3 lymphocytes suggesting that MfGL-II plays a major role in M. fermentans-host cell interaction.

Phosphocholine-containing glycoglycerolipids (GGPL-I and GGPL-III) are species-specific major immunodeterminants of Mycoplasma fermentans

Mycoplasma fermentans has unique glycoglycerophospholipids (GGPLs: GGPL-I and GGPL-III). Previously, the structure of these lipids was determined as phosphocholine-6'-alpha-glucopyranosyl-(1'-3)-1, 2-diacyl-glycerol (GGPL-I) and 1"-phosphocholine-2"-aminodihydroxypropane-3"-phospho-6'-alph++ + a- glucopyranosyl-(1'-3)-1, 2-diacyl-glycerol (GGPL-III). Thin-layer chromatography (TLC) immunostaining showed that the GGPLs were main lipid-antigens of the M. fermentans species. Anti-M. fermentans serum stained mainly the GGPLs, but the other anti-mycoplasma sera (anti-M. arginini, anti-M. hyorhinis, anti-M. pneumonia, anti-M. primatum, and anti-Acholeplasma laidlawii, anti-M. hominis, anti-M. orale, and M. salivarium) stained neither GGPL-I nor GGPL-III. The TLC analysis of glycolipids and phospholipids of various human related mycoplasmas showed clearly that GGPLs are specifically expressed in M. fermentans species. GGPL-I and GGPL-III ranged from 1.6 to 28% and from an undetectable level to 35% of total phospholipids, respectively. Although there was heterogeneity among the amounts of GGPL-I or GGPL-III of M. fermentans strains, all of the M. fermentans strains had GGPL-I and/or GGPL-III. These observations showed that GGPL structures are species-specific immunodeterminants of M. fermentans. The fact that the GGPLs are main phospholipid components of the M. fermentans species means the M. fermentans has a unique choline metabolic pathway. This observation may raise phylogenetic interest.

Antigenic topology of the P29 surface lipoprotein of Mycoplasma fermentans: differential display of epitopes results in high-frequency phase variation

Antibodies to P29, a major lipid-modified surface protein of Mycoplasma fermentans, reveal phase variation of surface epitopes occurring with high frequency in clonal lineages of the organism. This occurs despite continuous expression of the entire epitope-bearing P29 product (detected by Western immunoblotting) and contrasts with phase variation of other surface antigens mediated by differential expression of proteins. To understand the structure and antigenic topology of P29, the single-copy p29 gene from strain PG18 was cloned and sequenced. The gene encodes a prolipoprotein containing a signal sequence predicted to be modified with lipid and cleaved at the N-terminal Cys-1 residue of the mature P29 lipoprotein. The remaining 218-residue hydrophilic sequence of P29 is predicted to be located external to the single plasma membrane. Additional Cys residues at positions 91 and 128 in the mature protein were shown to form a 36-residue disulfide loop by selectively labeling sulfhydryl groups that were liberated only after chemical reduction of monomeric P29. Two nearly identical charged amino acid sequences occurred in P29, within the disulfide loop and upstream of this structure. Two distinct epitopes binding different monoclonal antibodies were associated with opposite ends of the P29 protein, by mapping products expressed in Escherichia coli from PCR-generated 3' deletion mutations of the p29 gene. Each monoclonal antibody detected high-frequency and noncoordinate changes in accessibility of the corresponding epitopes in colony immunoblots of clonal variants, yet sequencing of the p29 gene from these variants and analysis of disulfide bonds revealed no associated changes in the primary sequence or disulfide loop structure of P29. These results suggest that P29 surface epitope variation may involve masking of selected regions of P29, possibly by other surface components undergoing phase variation by differential expression. Differential masking may be an important mechanism for altering the antigenic or functional surface topology of this mycoplasma and other wall-less mycoplasmas.

Mycoplasma fermentans-derived lipid inhibits class II major histocompatibility complex expression without mediation by interleukin-6, interleukin-10, tumor necrosis factor, transforming growth factor-beta, type I interferon, prostaglandins or nitric oxide

Mycoplasma cause several diseases in man and animals. Some strains can chronically infect humans, leading to fever or inflammatory syndromes such as arthritis, particularly in immunosuppressed patients. A set of pathogenicity factors shared by many mollicutes may be membrane components that activate macrophages to secrete cytokines and other inflammatory mediators. Mycoplasma-derived high molecular weight material (MDHM) is a macrophage-activating amphiphilic lipid which was purified from Mycoplasma fermentans. We studied the influence of MDHM on the expression of major histocompatibility complex (MHC) class II molecules by mouse resident peritoneal macrophages with an ELISA. Highly purified MDHM at 4 ng/ml and 0.8 microgram/ml crude heat-killed M. fermentans (concentrations chosen to give maximal responses) suppressed interferon (IFN)-gamma-dependent class II MHC induction when added simultaneously with IFN-gamma. MDHM was not toxic and did not result in loss of adherent cells. Kinetic data showed that MDHM first up-regulated, then down-regulated the expression of preformed class II MHC molecules, while expression of Mac-1 and F4/80 antigens remained constant. MDHM-dependent suppression of class II MHC molecule expression resulted in impaired antigen presentation to the helper T cell line D10.G4.1. We further attempted to identify hypothetical products of MDHM-stimulated macrophages as secondary mediators of class II MHC suppression such as were described for lipopolysaccharide (LPS)-stimulated macrophages. Type I IFN, prostaglandins and nitric oxide, all reported to cause down-regulation of class II MHC, could be excluded in this context. Of the cytokines tumor necrosis factor, interleukin (IL)-6, IL-10 and transforming growth factor-beta, only IL-10 inhibited class II MHC expression, although less effectively than MDHM. The involvement of IL-10 was ruled out, as no evidence for its MDHM-dependent formation could be found. Our data suggest that MDHM interferes with class II MHC expression by up-regulating its turnover, and at the same time, inhibits the formation of new class II MHC molecules.

Molecular biological bases of resistance to HIV/AIDS (the hypothesis with elements of the theory)

Proceeding from the structure and function of the shell glycoprotein gp120 of the human immunodeficiency virus (HIV) and receptor glycoprotein CD4 on target cells for this virus, the author assumes that in nature there is genetically determined human resistance to the HIV infection and AIDS. This resistance manifests itself indirectly via products of the glycosylation system and via the composition and order of amino-acid residues in receptor CD4 sites responsible for interaction between the receptor and glycoprotein gp120. The author thinks that people in whom the glycosylation system determines either B(III) or AB(IV) blood groups are potential subjects of the HIV infection. But development of AIDS necessitates some conditions more, one of them is susceptibility of the human organism to be infected with mollicute Mycoplasma fermentans. This mycoplasma is able to recognize terminal NeuAc alpha 2-3 Gal in the composition of oligosaccharides of gp120, which permits it to adhere HIV virions on itself and then to transport them directly to the cells expressing receptor CD4 and having oligosaccharides of the same terminal structure. Oligosaccharides of glycocalyx of the mycoplasma protect it from the action of the human immune system and the mycoplasma, having "transported" HIV virions to target cells combines with membranes of the latter, stimulates formation by them of interleukin-1 and tumour necrosis factor, the known effectors of this virus reproduction. On the basis of all these factors the author identifies four types of human resistance to HIV/AIDS.

Identification of phosphocholine-containing glycoglycerolipids purified from Mycoplasma fermentans-infected human helper T-cell culture as components of M. fermentans

Previously, we have reported the occurrence of novel phosphocholine-containing glycoglycerolipids (GGPLs: GGPL-I and GGPL-III) in human helper T-cell (MT-4 cell line) (Mustuda et al, Glycoconjugate J. 10:340). However, the GGPLs disappeared from the MT-4 after treatment with an antimycoplasma agent. This disappearance suggested the involvement of microorganisms in the GGPL expression. In this paper, we show that the novel lipids are components of Mycoplasma fermentans itself. The supernatant fluid of the antimycoplasma agent-untreated Mt-4 cell culture produced mycoplasma-like colonies on PPLO agar plates, and PCR and immunological methods revealed the presence of M. fermentans. GGPLs were expressed again in the treated Mt-4 cells after infection with the isolated M. fermentans. The isolated M. fermentans had glycoglycerolipids corresponding to GGPL-I and GGPL-III. Thin-layer chromatography-mass spectrometry and immunological analyses showed that these glycoglycerolipid which were derived from the isolated M. fermentans were identical with GGPL-I and GGPL-III previously obtained. This is the first report that shows mycoplasma has phosphocholine-containing glycoglycerolipids.

Induced mouse spleen B-cell proliferation and secretion of immunoglobulin by lipid-associated membrane proteins of Mycoplasma fermentans incognitus and Mycoplasma penetrans

Mycoplasmas have been implicated as a possible cofactor in AIDS pathogenesis. Mycoplasma fermentans and M. penetrans infect human immunodeficiency virus-positive patients at a significantly higher frequency than non-human immunodeficiency virus-infected control subjects. Various mycoplasmal membrane preparations are known to affect the functions of immune cells both in vitro and in vivo. A group of lipid-associated membrane proteins (LAMPs) extracted by Triton X-114 from mycoplasmas are major antigenic targets of human host antibody responses. In this study, LAMPs prepared from both M. fermentans and M. penetrans nonspecifically stimulated spleen cells of CBA/CaH mice to proliferate. LAMPs were also stimulatory to spleen cells from athymic mice. On the other hand, enriched splenic T cells from CBA/CaH mice with or without accessory cells responded poorly. Thus, the mitogenic effect of mycoplasmal LAMPs appeared mainly on B cells. High levels of immunoglobulin (Ig) M and low but detectable amounts of IgG were found in the supernatant of LAMP-treated splenic cell culture. M. penetrans LAMPs had a much more potent effect on murine spleen cells than did M. fermentans incognitus LAMPs in inducing both B-cell proliferation and Ig secretion. In conclusion, the mycoplasmal LAMPs contained an active component(s) with T-independent B-cell mitogenic effect.

Differential protein expression and surface presentation generate high-frequency antigenic variation in Mycoplasma fermentans

Mycoplasma fermentans, a wall-less prokaryote, is currently under investigation as a potential human pathogen. Recently, several surface lipoproteins have been shown to vary in expression between M. fermentans strains. Using specific antibodies to these lipoproteins, we investigated the extent and nature of antigenic variation within this species. Immunoscreening of type strain PG18 agar-grown colonies revealed marked heterogeneity in expression of distinct surface lipoproteins. Subsequent isolation and propagation of clonal isolates established isogenic lineages which displayed high-frequency (10(-2) to 10(-5) per generation) antigenic phase variation. [35S]cysteine-labeled protein profiles and Western immunoblots of phase-variant clones showed that several distinct integral membrane proteins undergo noncoordinate variation in expression. In addition to differential expression of epitope-bearing lipoproteins, differential accessibility of epitopes to antibodies was also documented as a mechanism generating surface phenotypic variation. Examination of one strain-variant antigen showed high-frequency phase variation to underlie previously observed antigenic differences between strains of this species. Thus, M. fermentans has a complex system capable of creating rapid changes in surface mosaics. This may profoundly affect mycoplasma-host interactions and may limit the methods by which populations of M. fermentans may be studied in vivo.

Characterization of MHC induction by Mycoplasma fermentans (incognitus strain)

Mycoplasma fermentans (incognitus strain) is a recently identified new human pathogen and suspected cofactor in acquired immune deficiency syndrome. Because this organism appears to exert strong immunosuppressive properties of its own, we decided to investigate whether it was capable of inducing MHC class II expression, as we have observed for other species of mycoplasma. In this report we demonstrate that M. fermentans (incognitus strain) is capable of producing factors that increase MHC class II expression as well as MHC class I expression on the myelomonocytic cell line, WEHI-3 cells. We also present data showing that these mycoplasmal factors induce small, although significant, increases in MHC class I and II antigens on a mouse glioma cell line, G26-20, and MHC class II expression on the human monocyte cell lines, U-937 and HL-60. Using nuclear run-on analysis, we show that the mycoplasma-induced increase in MHC expression is at least partially due to an increase in transcription of the MHC genes. Furthermore, we show that the factor that mediates this activity is sensitive to protease treatment, indicating that it is, at least in part, protein. These results demonstrate that M. fermentans (incognitus strain) is capable of modulating the expression of immunologically important MHC genes in both murine and human cell lines, which may prove to be an important factor in the pathogenesis of this organism.

MDHM, a macrophage-activating product of Mycoplasma fermentans, stimulates murine macrophages to synthesize nitric oxide and become tumoricidal

In continuation of previous work on macrophage activation by a Mycoplasma fermentans-derived product, originally named "mycoplasma-derived high mol. wt. material" (MDHM), we have investigated whether MDHM was capable of inducing synthesis of the reactive nitrogen intermediate nitric oxide (NO), thus rendering macrophages cytocidal. Mycoplasmas were first delipidated with acetone, and MDHM activity was then extracted with 50 mM 1-O-octyl-beta-D-glucopyranoside to yield a particularly active new preparation of MDHM which we have named MDHM-D (D for detergent). In combination with IFN-gamma, MDHM-D activated macrophages to produce reactive nitrogen intermediates and kill P815 mastocytoma cells in co-culture. P815 target cells were chosen because they are TNF-resistant. Macrophages from the LPS-low responder strain C3H/HeJ were used to minimize interference from possible LPS contamination. MDHM-D activity in this system was strictly IFN-gamma-dependent. In the presence of 25 U/ml IFN-gamma MDHM-D gave a half maximal response at a dilution of 1/100,000, showing a parallel concentration dependency for nitrite production and cytocidal activity.

Titers of antibody to Mycoplasma in sera of patients infected with human immunodeficiency virus

One hundred sixty-seven sera collected from human immunodeficiency virus (HIV)-negative blood donors (n = 41), asymptomatic HIV-positive patients (n = 75), and patients with AIDS (n = 51) were compared in a metabolism inhibition serological test employing antigens to four distinct Mycoplasma species. The proportion of sera with antibody titers of > or = 1:32 to Mycoplasma genitalium was significantly higher for patients with AIDS than for HIV-negative blood donors. Serological relationships between Mycoplasma pneumoniae and M. genitalium as well as the possibility of increased susceptibility of AIDS patients to infection with these two mycoplasmas might account for this finding. Few sera showed antibody responses to Mycoplasma pirum or Mycoplasma fermentans.

A family of strain-variant surface lipoproteins of Mycoplasma fermentans

The wall-less procaryote Mycoplasma fermentans is currently being examined as an agent potentially associated with human disease, including infectious processes affecting immunocompromised individuals. To delineate and understand the interactions of M. fermentans with its host, specific membrane surface components were characterized as markers for detecting the organism and for assessing heterogeneity in antigenic surface architecture within this mycoplasma species. Detergent phase fractionation of metabolically labeled organisms of type strain PG18 identified a family of prominent integral membrane proteins; several of these labeled with 35S-cysteine and 3H-palmitate, which are characteristics of procaryotic lipoproteins. Specific monoclonal and polyclonal antibodies raised to strain PG18 components further distinguished seven of these membrane proteins, which were localized on the organism's surface by monitoring their selective susceptibility during trypsin treatment of intact cells. With these antibodies, Western immunoblot profiles of surface membrane antigens expressed on strain PG18 were compared with those expressed on the recently identified Incognitus strain of M. fermentans, as well as with several other human and animal mycoplasma species. While the antibodies were specific for M. fermentans, marked differences were observed between the strains in the size of one surface lipoprotein and in the apparent levels of several antigens expressed in the cultured populations analyzed. Some monoclonal antibodies to strain PG18 and a previously described monoclonal antibody to strain Incognitus showed apparent selectivity for the strain used for immunization. Monoclonal antibodies developed here recognize stable epitopes defining a family of surface lipoproteins and provide critical tools to determine the basis of surface variation in this mycoplasma species and to assess the location and antigenic phenotypes of organisms in the human host.

Enhanced secretion of immune-modulating cytokines by human lung fibroblasts during in vitro infection with Mycoplasma fermentans

Fibroblasts may play an important role in the modulation of immune and inflammatory responses through elaboration of cytokines. To test this hypothesis, human lung fibroblasts were isolated from transbronchial biopsy specimens and assayed for production of interleukin-6 (IL-6) and granulocyte/macrophage colony-stimulating factor (GM-CSF). The sources of fibroblasts included lung allografts, recipient lungs obtained at time of transplant, and normal lung tissue removed during tumor resection. During the course of these studies, several early-passage fibroblasts from transplant recipients were observed to contain mycoplasma (MP)-like organisms as detected by extranuclear fluorescent staining with Hoechst 33258. Positive staining cultures were associated with isolation of Mycoplasma fermentans. IL-6 and GM-GSF as measured by ELISA were found to be elevated over 50-fold in conditioned medium from MP-infected fibroblasts as compared with noninfected lines. Treatment of cells with mycoplasma removal agent (MRA) eliminated extranuclear Hoechst fluorescence and significantly reduced the production of these cytokines. Tumor necrosis factor-beta (TNF-beta) induction of IL-6 and GM-CSF was amplified synergistically in infected cultures. No additional production of IL-6 or GM-CSF was observed in infected cultures treated with interferon-gamma (IFN-gamma) despite the ability of IFN-gamma to modestly induce IL-6 in uninfected cultures. Thus, in vitro infection of lung fibroblasts with MP represents a potent stimulus for the production of inflammatory cytokines and, therefore, necessitates rigorous control for these organisms in cell culture studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Mycoplasma fermentans (incognitus strain) induces TNF alpha and IL-1 production by human monocytes and murine macrophages

We have demonstrated that Mycoplasma fermentans (incognitus strain), as well as M. fermentans KL4, PG 18 and IM 1 strains have the ability to activate human peripheral blood monocytes and murine macrophages of two inbred strains to secrete a high level of tumor necrosis factor alpha (TNF alpha) in a dose-dependent manner. Secretion of interleukin-1 (IL-1) was also stimulated following the incubation of human monocytes with the organism. We suggest that cytokine secretion following infection with M. fermentans (incognitus strain) that was detected in AIDS patients may contribute to the pathological manifestations, including cachexia, in this disease.

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

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.

Involvement of interleukin-1 (IL-1), IL-6, IL-2, and IL-4 in generation of cytolytic T cells from thymocytes stimulated by a Mycoplasma fermentans-derived product

The capacity of Mycoplasma fermentans-derived high-molecular-weight material (MDHM) to generate cytolytic T cells from mitogen-stimulated murine thymocytes was studied in detail. The role of MDHM and the involvement of monokines and lymphokines resulting from the addition of MDHM to thymocyte cultures were examined in complete and adherent cell-depleted culture systems by the addition of neutralizing monoclonal antibodies against interleukin-2 (IL-2), IL-4, and IL-6 and in reconstitution experiments with recombinant mediators. The data presented here suggest that MDHM is crucial only in the first phase of a reaction sequence beginning with the stimulation of adherent accessory cells and resulting in the synthesis of IL-1 and IL-6. The lymphokines IL-2 and, primarily, IL-4 are required in a second step which, once these lymphokines are formed, can proceed in the absence of MDHM and accessory cells and leads to the formation of cytolytic T cells. The elucidation of the MDHM-induced reaction sequence may be of relevance in view of the hypothetical role of mycoplasmas in rheumatic disease in humans. M. fermentans is an organism capable of infecting humans and in an early report has been discussed as a causative agent for rheumatoid arthritis.