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Barry C. Cole - One of the best experts on this subject based on the ideXlab platform.
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Expression of the superantigen Mycoplasma arthritidis mitogen in Escherichia coli and characterization of the recombinant protein.
Infection and immunity, 1997Co-Authors: Kevin L. Knudtson, Elsayed A. Ahmed, Muniraj Manohar, David E. Joyner, Barry C. ColeAbstract:Mycoplasma arthritidis mitogen (MAM), is a soluble protein with classical superantigenic properties and is produced by an organism that causes an acute and chronic proliferative arthritis. Unfortunately, the process of obtaining purified MAM from M. arthritidis culture supernatants is extremely time-consuming and costly, and very little material is recovered. Thus, our laboratory has expressed MAM in Escherichia coli by using a protein fusion expression system. The construction and expression of recombinant MAM (rMAM), as well as a comparison of the biological properties of rMAM to those of native MAM, are discussed. Briefly, conversion of the three UGA codons to UGG codons was required to obtain full-length expression and mitogenic activity of rMAM. Antisera to native MAM recognized both rMAM and the fusion protein. The T-cell receptor Vbeta and major histocompatibility complex class II receptor usages by rMAM and the fusion protein were identical to that of native MAM. In addition, the ability to induce suppression and form the superantigen bridge could also be demonstrated with rMAM. Importantly, dose-response experiments indicated that homogeneous native MAM and rMAM were of equal potency. Thus, MAM has been successfully expressed in E. coli, thereby creating a viable alternative to native MAM.
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The sequence of the Mycoplasma arthritidis superantigen, MAM: identification of functional domains and comparison with microbial superantigens and plant lectin mitogens.
The Journal of experimental medicine, 1996Co-Authors: Barry C. Cole, Elsayed A. Ahmed, Kevin L. Knudtson, A. Oliphant, Allen D. Sawitzke, Ann Pole, Muniraj Manohar, L. S. Benson, Curtis L. AtkinAbstract:Mycoplasma arthritidis, an agent of chronic proliferative arthritis of rodents, secretes a potent soluble superantigen, MAM, that is active for both murine and human T and B lymphocytes. We now report the complete nucleotide and amino acid sequence of MAM and show it to be distinct from other proteins and not closely related phylogenetically to other superantigens. Two functional domains on MAM are identified based on the ability of peptides encompassing these regions to inhibit lymphocyte proliferation by the intact MAM molecule. One of these domains shares short sequences or epitopes with other microbial superantigens. The second domain contains the consensus legume lectin motif-beta, which is important for T cell activation by concanavalin (Con) A. MAM and Con A peptides containing this motif are functionally cross reactive, suggesting a novel secondary pathway for T cell activation by MAM.
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Mycoplasma arthritidis mitogen up-regulates human NK cell activity
Infection and immunity, 1996Co-Authors: John A. D'orazio, Barry C. Cole, J Stein-streileinAbstract:While the effects of superantigens on T lymphocytes are well characterized, how superantigens interact with other immune cells is less clear. This report examines the effects of Mycoplasma arthritidis mitogen (MAM) on human natural killer (NK) cell activity. Incubation of peripheral blood mononuclear cells (PBMC) with MAM for 16 to 20 h augmented NK cytotoxicity (against K562) in a dose-dependent manner (P < or = 0.05). Superantigen-dependent cellular cytotoxicity, an activity of superantigen-activated cytotoxic T cells, was not involved in lysis of K562 cells because the erythroleukemic tumor target cells expressed no class II major histocompatibility complex by fluorescence-activated cell sorter analysis. Kinetic experiments showed that the largest increase in NK activity induced by MAM occurred within 48 h. Incubation with MAM caused a portion of NK cells to become adherent to tissue culture flasks, a quality associated with activation, and augmented NK activity was found in both adherent and nonadherent subpopulations. Experiments using cytokine-specific neutralizing antibodies showed that interleukin-2 contributed to enhancement of the NK activity observed in superantigen-stimulated PBMC. Interestingly, MAM was able to augment NK lysis of highly purified NK (CD56+) cells in the absence of other immune cells in 9 of 12 blood specimens, with the augmented lytic activity ranging from 110 to 170% of unstimulated NK activity. In summary, data presented in this report show for the first time that MAM affects human NK cells directly by increasing their lytic capacity and indirectly in PBMC as a consequence of cytokines produced by T cells. Results of this work suggest that, in vivo, one consequence of interaction with superantigen-secreting microorganisms may be up-regulation of NK lytic activity. These findings may have clinical application as a means of generating augmented NK effector cells useful in the immunotherapy of parasitic infections or neoplasms.
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Human T-cell responses to Mycoplasma arthritidis-derived superantigen.
Infection and immunity, 1994Co-Authors: Nina Bhardwaj, Barry C. Cole, Andrew S. Hodtsev, Shara Kabak, Steven M. Friedman, Anahid J. Nisanian, David N. PosnettAbstract:When injected into mice, Mycoplasma arthritidis causes a chronic arthritis that resembles rheumatoid arthritis, histologically. The organism produces a superantigen termed Mycoplasma arthritidis mitogen or MAM, that in humans preferentially expands T cells whose antigen receptors express V beta 17. T cells with this phenotype appear to be increased in rheumatoid synovial effusions. We describe a novel approach to isolating and characterizing human MAM-reactive T-cell lines and determining their T-cell receptor (TCR) V beta usage. Lines were prepared from T cells that clustered with dendritic cells during a 2-day exposure to MAM. Cluster and noncluster fractions of T cells were then expanded by using feeder cells and a polyclonal mitogen. Most of the MAM reactivity was found in dendritic T-cell clusters, as were most of the T cells expressing TCR V beta 17. After expansion, 76% of the cluster-derived T-cell lines were MAM reactive, while no reactivity was seen in cell lines derived from the noncluster fraction. Of the MAM-reactive lines, 49% expressed V beta 17 on some or all of the cells. Cell lines from both cluster and noncluster fractions were analyzed for TCR V beta mRNA expression by PCR amplification. Other V beta genes (5.1, 7, 8, 12, and 20) were found to be expressed by lines that were MAM reactive, although these were not a major component of the cluster-derived T cells. Some non-cluster-derived lines expressed V beta s 17, 12, and 7, but these proved to be nonreactive to MAM. Therefore, dendritic cells can be used to immunoselect and characterize T cells that express superantigen-reactive TCRs.
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The Mycoplasma arthritidis superantigen MAM: purification and identification of an active peptide.
Infection and immunity, 1994Co-Authors: Curtis L. Atkin, S Wei, Barry C. ColeAbstract:The prototypical superantigen MAM is an extracellular T-cell mitogen produced by Mycoplasma arthritidis, an organism which causes chronic proliferative arthritis of rodents. We here describe purification of MAM to homogeneity. Pure MAM exhibits all of the major properties previously described for partially purified MAM, including preference for H-2E molecules in presention to T cells, V beta T-cell receptor specificity for T-cell activation, and in vivo inhibition of T-cell functions but enhancement of B-cell activity as mediated by the superantigen bridge. Edman degradation of pure MAM gave a 54-residue partial amino-terminal sequence. The oligopeptide MAM15-31-C, synthesized according to the Edman sequence, blocked mitogenicity of MAM and supported assignment of the amino acid sequence.
Kevin Dybvig - One of the best experts on this subject based on the ideXlab platform.
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Identification of an isoschizomer of the HhaI DNA methyltransferase in Mycoplasma arthritidis
FEMS Microbiology Letters, 2008Co-Authors: Wenyi Luo, Zuhua Cao, Kevin DybvigAbstract:The genome of Mycoplasma arthritidis strain 158 has modified cytosine residues at AGCT sequences that render the DNA resistant to digestion with the AluI restriction endonuclease. The DNA methyltransferase responsible for the base modification has previously been designated MarI. From the complete genome sequence of M. arthritidis, we identify Marth_orf138 as a candidate marI gene. Marth_orf138 was cloned in Escherichia coli and its TGA codons converted to TGG. DNA isolated from E. coli cells expressing the modified Marth_orf138 gene was degraded by the AluI nuclease, indicating that Marth_orf138 does not code for MarI. However, the DNA from E. coli was found to have acquired resistance to the restriction endonuclease HhaI. Genomic DNA from M. arthritidis was also found to be resistant to HhaI (recognizes GCGC). The M. arthritidis isoschizomer of the HhaI DNA methyltransferase, coded by Marth_orf138, is designated MarII. Transformation of M. arthritidis was not significantly affected by modification of plasmid at HhaI sites, indicating that the Mycoplasma lacks a restriction endonuclease that recognizes GCGC sites.
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Association of Mycoplasma arthritidis mitogen with lethal toxicity but not with arthritis in mice.
Infection and immunity, 2008Co-Authors: Wenyi Luo, Zuhua Cao, Trenton R. Schoeb, Michele P. Marron, Kevin DybvigAbstract:Mycoplasma arthritidis induces an acute to chronic arthritis in rodents. Arthritis induced in mice histologically resembles human rheumatoid arthritis and can be associated with lethal toxicity following systemic injection. The M. arthritidis mitogen (MAM) superantigen has long been implicated as having a role in pathogenesis, but its significance with respect to toxicity and arthritogenicity in Mycoplasma-induced disease is unclear. To study the pathogenic significance of MAM, M. arthritidis mutants that overproduced or failed to produce MAM were developed. MAM overproduction and knockout mutants were more and less mitogenic, respectively, than the wild-type strain. The degree of mitogenic activity correlated with lethal toxicity in DBA/2J mice. In contrast, histopathological studies detected no correlation between MAM production and the severity of arthritis induced in DBA/2J and CBA/J mice.
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Genome of Mycoplasma arthritidis
Infection and immunity, 2008Co-Authors: Kevin Dybvig, Cao Zuhua, Ping Lao, David S. Jordan, C. Todd French, Ann E. LoraineAbstract:The genomes of several species of Mycoplasma have been sequenced. Most of these species rely on the glycolytic pathway for energy production, with the one exception of Ureaplasma, a species that breaks down urea as its principle source of acquiring energy. Several species, including as Mycoplasma arthritidis, are nonglycolytic and can use arginine as their source of energy. Described here are the genome sequence and a transposon library of M. arthritidis. The genome of 820,453 bp is typical in size for a Mycoplasma and contains two large families of genes that are predicted to code for phase-variable proteins. The transposon library was constructed using a minitransposon that inserts stably into the Mycoplasma genome. Of the 635 predicted coding regions, 218 were disrupted in a library of 1,100 members. Dispensable genes included the gene coding for the MAM superantigen and genes coding for ribosomal proteins S15, S18, and L15.
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Association of a major protein antigen of Mycoplasma arthritidis with virulence.
Infection and immunity, 2005Co-Authors: Brenda Clapper, Trenton R. Schoeb, Ada Elgavish, J. Zhang, L. Liu, Kevin DybvigAbstract:Mycoplasma arthritidis causes acute polyarthritis in rats and chronic proliferative arthritis in mice. M. arthritidis-induced arthritis serves as a model for arthritis caused by infectious agents and as a model for examining the role of the superantigen MAM (M. arthritidis T-cell mitogen) in the development of autoimmunity. M. arthritidis strain 158-1 is a spontaneous mutant of strain 158 that has a drastic reduction in virulence. We show that the mutant is missing a major antigen of 47 kDa (P47) and has acquired a protein of 67 kDa (P67). P47 and P67 partitioned into the detergent phase by extraction with Triton X-114. Coomassie blue staining of sodium dodecyl sulfate-polyacrylamide gels show that P67 is produced in abundance. Analysis of gel-purified P67 by mass spectrometry led to its identification as a lipoprotein (the open reading frame [ORF] 619 gene product) predicted from the genome sequence of M. arthritidis. PCR analysis of genomic DNA from 158 and 158-1 indicates that P47 and P67 are encoded by the same ORF 619 gene and differ only in the number of repeats in a tandem repeat region. By two-dimensional polyacrylamide gel analysis, no protein differences were detectable between 158 and 158-1 other than P47 and P67. Collectively, the data suggest that the tandem repeat region of P47 and P67 influences disease outcome.
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The vir Gene of Bacteriophage MAV1 Confers Resistance to Phage Infection on Mycoplasma arthritidis
Journal of bacteriology, 2004Co-Authors: Brenda Clapper, Ada Elgavish, Kevin DybvigAbstract:Lysogenization of Mycoplasma arthritidis with the MAV1 bacteriophage increases the virulence of the Mycoplasma in rats. The MAV1 vir gene is one of only two constitutively transcribed phage genes in the lysogen. We show here that Vir is a lipoprotein and is located on the outer surface of the cell membrane. To investigate whether Vir is a virulence factor, the vir gene was cloned into the transposon vector Tn4001T and inserted in the genome of the nonlysogen strain 158. The virulence of the resulting transformants was no different from that of the parent strain. Interestingly, all vir-containing transformants were resistant to infection by MAV1. Vir had no effect on MAV1 adsorption. We conclude that Vir is not a virulence factor but functions to exclude superinfecting phage, possibly by blocking the injection of phage DNA into the bacterial cytoplasm.
Leigh Rice Washburn - One of the best experts on this subject based on the ideXlab platform.
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Mutation of two Mycoplasma arthritidis surface lipoproteins with divergent functions in cytadherence.
Infection and immunity, 2008Co-Authors: Daniel W. Bird, Kelly Graber, Allison Knutson, Leigh Rice WashburnAbstract:Mycoplasma arthritidis is a natural pathogen of rats, causing an acute polyarthritis. Previous studies identified two membrane-bound lipoproteins, Maa1 and Maa2, thought to be associated with cytadherence of M. arthritidis strain 158p10p9. We have since confirmed that Maa1 is a major adhesin, although the role of Maa2 has proven more elusive. Both proteins were capable of eliciting protective immunity in rats against challenge with the virulent strain 158p10p9, suggesting that they may be important in pathogenesis. The purpose of this study was to better understand the roles of Maa1 and Maa2 in cytadherence in vitro. Insertion mutants were created for both genes by transposon mutagenesis. In vitro adherence of the Maa1 mutant KOMaa1 to rat L2 lung cells was reduced to the level previously reported for a spontaneous low-adherence mutant of 158p10p9 in which Maa1 is truncated and nonfunctional. Surprisingly, adherence of the Maa2 mutant KOMaa2 was approximately fivefold greater than that of the wild type. Complementation of KOMaa1 and KOMaa2 with wild-type alleles of maa1 and maa2, respectively, returned adherence to wild-type levels. This work confirms our earlier observation that Maa1 is a major adhesin for M. arthritidis strain 158p10p9. Maa2, on the other hand, may play a suppressive or modulatory role, possibly serving to release organisms from microcolonies at certain stages of infection.
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Restoration of cytoadherence to an adherence-deficient mutant of Mycoplasma arthritidis by genetic complementation.
Infection and immunity, 2003Co-Authors: Leigh Rice Washburn, Daniel W. Bird, Kevin DybvigAbstract:Mycoplasma arthritidis causes a severe septic arthritis in rats under natural and experimental conditions. An earlier study implicated a membrane lipoprotein designated MAA1 in cytadherence of M. arthritidis. In addition, a spontaneous adherence-deficient mutant was shown to contain a nonsense mutation in the gene encoding MAA1, resulting in production of a truncated product, MAA1Δ. In the present study, a wild-type maa1 gene carried on transposon Tn4001T was introduced into the low-adherence mutant by polyethylene glycol-mediated transformation. The presence of the tranposon and the wild-type maa1 gene in the chromosome of transformants was confirmed by PCR and Southern hybridization. The latter procedure also confirmed that each transformant contained a single copy of the transposon. Western immunoblotting showed that transformants produced both wild-type MAA1 and MAA1Δ, indicating that the introduced wild-type maa1 gene was functional. This phenotype was stably maintained after multiple subcultures even in the absence of antibiotic selection. Finally, transformants were shown to adhere to rat L-2 lung cells in culture at wild-type levels, providing confirmation for an important role for MAA1 in adherence.
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Molecular Characterization of Mycoplasma arthritidis Membrane Lipoprotein MAA1
Infection and immunity, 2000Co-Authors: Leigh Rice Washburn, Elizabeth J. Miller, Keith E. WeaverAbstract:Genes encoding the Mycoplasma arthritidis surface-exposed lipoprotein MAA1 were cloned and sequenced from MAA1-expressing strains 158p10p9 and PG6, from a low-adherence (LA) variant derived from 158p10p9 that expresses a truncated version of MAA1 (MAA1Delta) and from two MAA1-negative strains, 158 and H39. The deduced amino acid sequences of maa1 from 158p10p9 and PG6 predicted, respectively, 86.5- and 86.4-kDa basic, largely hydrophilic lipoproteins with 29-amino-acid signal peptides and predicted cleavage sites for signal peptidase II (Ala-Ala-Ala downward arrowCys). The truncation in the LA variant resulted from a G-->T substitution at nucleotide 695, which created a premature stop codon. This, in turn, generated a predicted 26.6-kDa prolipoprotein (23.6 kDa after processing), consistent with an M(r) of approximately 24,000 calculated for MAA1Delta. Similarly, absence of MAA1 expression in H39 and 158 resulted from C-->A substitutions at nucleotide 208, generating premature stop codons at that site in both strains.
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Molecular Characterization of Mycoplasma arthritidis Membrane
1999Co-Authors: Lipoprotein Maa, Leigh Rice Washburn, Elizabeth J. Miller, E. WeaverAbstract:Genes encoding the Mycoplasma arthritidis surface-exposed lipoprotein MAA1 were cloned and sequenced from MAA1-expressing strains 158p10p9 and PG6, from a low-adherence (LA) variant derived from 158p10p9 that expresses a truncated version of MAA1 (MAA1D) and from two MAA1-negative strains, 158 and H39. The deduced amino acid sequences of maa1 from 158p10p9 and PG6 predicted, respectively, 86.5- and 86.4-kDa basic, largely hydrophilic lipoproteins with 29-amino-acid signal peptides and predicted cleavage sites for signal peptidase II (Ala-Ala-Ala2Cys). The truncation in the LA variant resulted from a G3T substitution at nucleotide 695, which created a premature stop codon. This, in turn, generated a predicted 26.6-kDa proli-poprotein (23.6 kDa after processing), consistent with an Mr of;24,000 calculated for MAA1D. Similarly, absence of MAA1 expression in H39 and 158 resulted from C3A substitutions at nucleotide 208, generating premature stop codons at that site in both strains. Mycoplasma arthritidis causes an acute, self-limited, septic arthritis of rats under both natural and experimental condi-tions (4). As with most infectious diseases, adherence to host tissues is likely to play an important role. We have identified two surface proteins, MAA1 and MAA2, that may be involve
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Molecular Characterization of Mycoplasma arthritidis Variable Surface Protein MAA2
Infection and immunity, 1998Co-Authors: Leigh Rice Washburn, Keith E. Weaver, Elizabeth J. Weaver, Wendy Donelan, Suhaila Al-sheboulAbstract:Earlier studies implied a role for Mycoplasma arthritidis surface protein MAA2 in cytadherence and virulence and showed that it exhibited both size and phase variability. Here we report the further analysis of MAA2 and the cloning and sequencing of the maa2 gene from two M. arthritidis strains, 158p10p9 and H606, expressing two size variants of MAA2. Triton X-114 partitioning and metabolic labeling with [3H]palmitic acid suggested lipid modification of MAA2. Surface exposure of the C terminus was indicated by cleavage of monoclonal antibody-specific epitopes from intact cells by carboxypeptidase Y. The maa2 genes from both strains were highly conserved, consisting largely of six (for 158p10p9) or five (for H606) nearly identical, 264-bp tandem direct repeats. The deduced amino acid sequence predicted a largely hydrophilic, highly basic protein with a 29-amino-acid lipoprotein signal peptide. The maa2 gene was expressed in Escherichia coli from the lacZ promoter of vector pGEM-T. The recombinant product was approximately 3 kDa larger than the native protein, suggesting that the signal peptide was not processed in E. coli. The maa2 gene and upstream DNA sequences were cloned from M. arthritidis clonal variants differing in MAA2 expression state. Expression state correlated with the length of a poly(T) tract just upstream of a putative -10 box. Full-sized recombinant MAA2 was expressed in E. coli from genes derived from both ON and OFF expression variants, indicating that control of expression did not include alterations within the coding region.
Curtis L. Atkin - One of the best experts on this subject based on the ideXlab platform.
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The sequence of the Mycoplasma arthritidis superantigen, MAM: identification of functional domains and comparison with microbial superantigens and plant lectin mitogens.
The Journal of experimental medicine, 1996Co-Authors: Barry C. Cole, Elsayed A. Ahmed, Kevin L. Knudtson, A. Oliphant, Allen D. Sawitzke, Ann Pole, Muniraj Manohar, L. S. Benson, Curtis L. AtkinAbstract:Mycoplasma arthritidis, an agent of chronic proliferative arthritis of rodents, secretes a potent soluble superantigen, MAM, that is active for both murine and human T and B lymphocytes. We now report the complete nucleotide and amino acid sequence of MAM and show it to be distinct from other proteins and not closely related phylogenetically to other superantigens. Two functional domains on MAM are identified based on the ability of peptides encompassing these regions to inhibit lymphocyte proliferation by the intact MAM molecule. One of these domains shares short sequences or epitopes with other microbial superantigens. The second domain contains the consensus legume lectin motif-beta, which is important for T cell activation by concanavalin (Con) A. MAM and Con A peptides containing this motif are functionally cross reactive, suggesting a novel secondary pathway for T cell activation by MAM.
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The Mycoplasma arthritidis superantigen MAM: purification and identification of an active peptide.
Infection and immunity, 1994Co-Authors: Curtis L. Atkin, S Wei, Barry C. ColeAbstract:The prototypical superantigen MAM is an extracellular T-cell mitogen produced by Mycoplasma arthritidis, an organism which causes chronic proliferative arthritis of rodents. We here describe purification of MAM to homogeneity. Pure MAM exhibits all of the major properties previously described for partially purified MAM, including preference for H-2E molecules in presention to T cells, V beta T-cell receptor specificity for T-cell activation, and in vivo inhibition of T-cell functions but enhancement of B-cell activity as mediated by the superantigen bridge. Edman degradation of pure MAM gave a 54-residue partial amino-terminal sequence. The oligopeptide MAM15-31-C, synthesized according to the Edman sequence, blocked mitogenicity of MAM and supported assignment of the amino acid sequence.
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The Mycoplasma arthritidis superantigen MAM: purification and identification of an active peptide. Infect. Immun
1994Co-Authors: Curtis L. Atkin, Suhua Wei, Barry C. ColeAbstract:The prototypical superantigen MAM is an extracellular T-cell mitogen produced by Mycoplasma arthritidis, an organism which causes chronic proliferative arthritis of rodents. We here describe purification of MAM to homogeneity. Pure MAM exhibits all of the major properties previously described for partially purified MAM, including preference for H-2E molecules in presention to T cells, V. T-cell receptor specificity for T-cell activation, and in vivo inhibition of T-cell functions but enhancement of B-cell activity as mediated by the superantigen bridge. Edman degradation of pure MAM gave a 54-residue partial amino-terminal sequence. The oligopeptide MAM,_,31-C, synthesized according to the Edman sequence, blocked mitogenicity of MAM and supported assignment of the amino acid sequence. The newly recognized class of superantigens is composed of immunomodulatory protein molecules that have been hypoth-esized to induce autoimmune diseases (10, 17, 22, 30, 32). Bacterial exotoxins (4, 24, 29, 30) and cell wall components (34, 35) as well as endogenous mouse tumor provirus and retroviral proteins (1, 23) and rabies virus (27) have been shown to possess superantigenic properties. Mycoplasma arthnitidis, a
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Immunomodulation In Vivo by the Mycoplasma arthritidis Superantigen, MAM
Clinical Infectious Diseases, 1993Co-Authors: Barry C. Cole, Elsayed A. Ahmed, Barbara A. Araneo, Jane Shelby, Craig D. Kamerath, Suhua Wei, S Mccall, Curtis L. AtkinAbstract:Mycoplasma arthritidis produces a potent superantigen (MAM) that activates specific murine and human T lymphocytes to proliferate and secrete lymphokines. We show here that MAM also influences both T- and B-cell functions in vivo. Lymphocytes from mice injected with MAM exhibit a suppression of proliferative responses to MAM in vitro but only a partial suppression of responses to other mitogens. This T-cell anergy not only decreased contact sensitivity to dinitrofluorobenzene but also prolonged survival of skin transplants. In contrast, B-cell reactivity is increased following in vivo injection of MAM, as evidenced by enhanced antibody responses to sheep red blood cells and ovalbumin
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Immunomodulation in vivo by the Mycoplasma arthritidis superantigen, MAM.
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 1993Co-Authors: B C Cole, Barbara A. Araneo, Jane Shelby, Craig D. Kamerath, Suhua Wei, S Mccall, E Ahmed, Curtis L. AtkinAbstract:Mycoplasma arthritidis produces a potent superantigen (MAM) that activates specific murine and human T lymphocytes to proliferate and secrete lymphokines. We show here that MAM also influences both T- and B-cell functions in vivo. Lymphocytes from mice injected with MAM exhibit a suppression of proliferative responses to MAM in vitro but only a partial suppression of responses to other mitogens. This T-cell anergy not only decreased contact sensitivity to dinitrofluorobenzene but also prolonged survival of skin transplants. In contrast, B-cell reactivity is increased following in vivo injection of MAM, as evidenced by enhanced antibody responses to sheep red blood cells and ovalbumin. Also, there is a marked decrease in the ability of splenocytes from MAM-injected mice to produce interleukin-2 (IL-2) but a marked increase in their ability to produce IL-4 and IL-6. The combined results suggest that MAM induces a lymphokine profile that favors activation of B-cell functions, with a resulting potential for triggering of autoimmune disease.
Lothar Rink - One of the best experts on this subject based on the ideXlab platform.
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Mycoplasma arthritidis-derived superantigen (MAM) displays DNase activity.
FEMS immunology and medical microbiology, 2007Co-Authors: Markus Diedershagen, Silke Overbeck, Sabine Arlt, Birgit Plümäkers, Maria Lintges, Lothar RinkAbstract:Bacterial superantigens are potent stimulators of the immune system. In this study, we expressed recombinant superantigens, which were then affinity purified and used for growth curves and DNase activity assays. Overexpression of Mycoplasma arthritidis-derived superantigen in Escherichia coli reduced bacterial growth. This is unique, as staphylococcal enterotoxin A and toxic shock syndrome toxin-1, expressed in the same vector system, showed no growth impairment. The observed growth inhibition was caused by the DNase activity of recombinant M. arthritidis-derived superantigen, thus describing the first superantigen showing enzymatic activity, which may be a result of the separate evolution of this toxin.
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HLA-dependent heterogeneous T cell response to Mycoplasma arthritidis-derived superantigen (MAS).
Medical microbiology and immunology, 1997Co-Authors: Lourdes Alvarez-ossorio, Holger Kirchner, Meike Johannsen, Martin Russlies, Lothar RinkAbstract:Mycoplasma arthritidis induces a chronic arthritis in rodents. The role of M. arthritidis-derived superantigen (MAS) in the arthritis is still a subject of controversy. MAS stimulates mouse and human T cells in a Vβ-restricted manner with the subsequent liberation of cytokines. The presence of the major histocompatibility complex class II molecule is required for such a stimulation. In this study we assessed MAS-induced cytokine production in peripheral blood from patients with different rheumatic diseases and controls using an enzyme-linked immunosorbent assay. Statistically significant differences in cytokine production in response to MAS stimulation allowed the distinction of high responders and low responders within groups of patients and controls. Higher cytokine induction was statistically correlated with the HLA-DR specificities DR4, DR7 and DR12. To confirm these results, murine Vβ 8.1 cytotoxic T lymphocytes (CTL) were stimulated with MAS in the presence of different HLA-DR lymphoblastoid B cells. CTL proliferation was only observed in presence of DR4 and DR7. In conclusion, MAS T cell stimulation and its subsequently cytokine production depends on the presence of certain HLA-DR specificities.
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Functional Analysis of Mycoplasma arthritidis-Derived Mitogen Interactions with Class II Molecules
Infection and immunity, 1997Co-Authors: C Bernatchez, R Al-daccak, P E Mayer, K Mehindate, Lothar Rink, Salah Mecheri, Walid MouradAbstract:The ability of superantigens (SAGs) to trigger various cellular events via major histocompatibility complex (MHC) class II molecules is largely mediated by their mode of interaction. Having two MHC class II binding sites, staphylococcal enterotoxin A (SEA) is able to dimerize MHC class II molecules on the cell surface and consequently induces cytokine gene expression in human monocytes. In contrast, cross-linking with specific monoclonal antibodies or T-cell receptor is required for staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin 1 (TSST-1) to induce similar responses. In the present study, we report how Mycoplasma arthritidis-derived mitogen (MAM) may interact with MHC class II molecules to induce cytokine gene expression in human monocytes. The data presented indicate that MAM-induced cytokine gene expression in human monocytes is Zn2+ dependent. The MAM-induced response is completely abolished by pretreatment with SEA mutants that have lost their capacity to bind either the MHC class II alpha or beta chain, with wild-type SEB, or with wild-type TSST-1, suggesting that MAM induces cytokine gene expression most probably by inducing dimerization of class II molecules. In addition, it seems that SEA and MAM interact with the same or overlapping binding sites on the MHC class II beta chain and, on the other hand, that they bind to the alpha chain most probably through the regions that are involved in SEB and TSST-1 binding.
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Induction of a Proinflammatory Cytokine Network by Mycoplasma arthritidis-Derived Superantigen (MAS)
Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research, 1996Co-Authors: Lothar Rink, Werner Nicklas, Jürgen Luhm, Regine Kruse, Holger KirchnerAbstract:Mycoplasma arthritidis is an arthritogenic organism for rodents, producing a superantigen (MAS). It has been postulated that Mycoplasmas or superantigens thereof might play a role in human rheumato...
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Induction of cytokines in human peripheral blood and spleen cells by the Mycoplasma arthritidis-derived superantigen.
Lymphokine and cytokine research, 1992Co-Authors: Lothar Rink, Werner Nicklas, Andrea Kruse, Hoyer J, Holger KirchnerAbstract:Recently, the mitogenic effects of the Mycoplasma arthritidis supernatant, MAS, and the induction of interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) by MAS have been described. In the present series of experiments we investigated human peripheral blood mononuclear cells (PBM) and human spleen cells with respect to their production of these and other cytokines. In human spleen cell cultures and PBM, MAS induced the synthesis of interleukin-1 alpha (IL-1 alpha) and IL-1 beta. Both interleukins were secreted faster and in higher amounts by PBM. IL-6 was also induced by MAS in PBM and human spleen cells. The amounts of IL-6 measured by ELISA were higher in PBM, whereas the biological activity of IL-6 was higher in spleen cell cultures. T-cell products such as IL-2, IL-4, and IFN-gamma were also induced by MAS in PBM and spleen cells. The kinetics of IFN-gamma and IL-4 induction were negatively correlated. In PBM we found low levels of IL-4 and high IFN-gamma induction, whereas in spleen cells high titers of IL-4 and low IFN-gamma titers were observed. Collectively, our results indicate that MAS induces different networks of cytokine interactions depending on the organ from which the cells are derived.
