The structure and properties of MFG-E8 and the In vitro assessment of its toxic effects on myoblast cells.

Four high-molecular-weight protein fractions of milk fat globule membrane (MFGM) were isolated from bovine milk. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), MALDI-TOF/TOF™ and Liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) were used to measure the molecular sizes of the MFGM. Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) were performed to determine the conformations of the MFGM. The results showed that the main protein (98.33%) in MFGM protein fraction 2 was Milk fat globule epidermal growth factor-VIII (MFG-E8), with a molecular weight of 47.82 kDa. The secondary structural component measurements showed that the MFG-E8 consisted of 5% helix, 70% sheet and 25% random coil, and the results matched well with the prediction by SSPro 5.1 bioinformatic analysis. The thermograms analysis revealed that Td and△H of MFG-E8 were 60.50°Cand 132.29 kJ/mol. The in vitro digestibility of MFG-E8 showed that it can be enzymatically hydrolyzed in the stomach and relatively stable in the intestinal fluid. The in vitro C2C12 and Caco2 cell activity tests indicated that MFG-E8 promoted the proliferation of C2C12 myoblast cells without cytotoxicity. The biological functional properties of MFG-E8 may be related to the fact that MFG-E8 possesses a high level of ß-sheet structure. Our results suggested that MFG-E8 possesses broad prospects not only for use in functional food products but also as a source of natural anti-sarcopenia drugs.

Endothelial Immune Activation by Medin: Potential Role in Cerebrovascular Disease and Reversal by Monosialoganglioside-Containing Nanoliposomes.

Background The function of medin, one of the most common human amyloid proteins that accumulates in the vasculature with aging, remains unknown. We aim to probe medin's role in cerebrovascular disease by comparing cerebral arterial medin content between cognitively normal and vascular dementia (VaD) patients and studying its effects on endothelial cell (EC) immune activation and neuroinflammation. We also tested whether monosialoganglioside-containing nanoliposomes could reverse medin's adverse effects. Methods and Results Cerebral artery medin and astrocyte activation were measured and compared between VaD and cognitively normal elderly brain donors. ECs were exposed to physiologic dose of medin (5 µmol/L), and viability and immune activation (interleukin-8, interleukin-6, intercellular adhesion molecule-1, and plasminogen activator inhibitor-1) were measured without or with monosialoganglioside-containing nanoliposomes (300 µg/mL). Astrocytes were exposed to vehicle, medin, medin-treated ECs, or their conditioned media, and interleukin-8 production was compared. Cerebral collateral arterial and parenchymal arteriole medin, white matter lesion scores, and astrocyte activation were higher in VaD versus cognitively normal donors. Medin induced EC immune activation (increased interleukin-8, interleukin-6, intercellular adhesion molecule-1, and plasminogen activator inhibitor-1) and reduced EC viability, which were reversed by monosialoganglioside-containing nanoliposomes. Interleukin-8 production was augmented when astrocytes were exposed to medin-treated ECs or their conditioned media. Conclusions Cerebral arterial medin is higher in VaD compared with cognitively normal patients. Medin induces EC immune activation that modulates astrocyte activation, and its effects are reversed by monosialoganglioside-containing nanoliposomes. Medin is a candidate novel risk factor for aging-related cerebrovascular disease and VaD.

Oxidative Stress Alters the Morphology and Toxicity of Aortic Medial Amyloid.

The aggregation and fibril deposition of amyloid proteins have been implicated in a range of neurodegenerative and vascular diseases, and yet the underlying molecular mechanisms are poorly understood. Here, we use a combination of cell-based assays, biophysical analysis, and atomic force microscopy to investigate the potential involvement of oxidative stress in aortic medial amyloid (AMA) pathogenesis and deposition. We show that medin, the main constituent of AMA, can induce an environment rich in oxidative species, increasing superoxide and reducing bioavailable nitric oxide in human cells. We investigate the role that this oxidative environment may play in altering the aggregation process of medin and identify potential posttranslational modification sites where site-specific modification and interaction can be unambiguously demonstrated. In an oxidizing environment, medin is nitrated at tyrosine and tryptophan residues, with resultant effects on morphology that lead to longer fibrils with increased toxicity. This provides further motivation to investigate the role of oxidative stress in AMA pathogenicity.

Enhancement of the cytotoxic activity of Clostridium difficile toxin A by surface-associated antigens.

Cell-surface antigens of Clostridium difficile and LPS from Escherichia coli were investigated for modulating effects on the activity of C. difficile toxin A on Vero and Caco2 cells. The antigens of C. difficile tested comprised: (i) an EDTA extract, which contained several major and minor cell-surface proteins and the membrane-associated lipocarbohydrate (LC); (ii) a guanidine hydrochloride extract, which mainly contained the surface-layer proteins; (iii) an aqueous phenol-extracted, protein-free LC. On their own, none of the antigens had a detrimental effect on the cells, with the EDTA extract and LC having a marginally protective effect. When these antigens were added to suboptimal levels of toxin A, there was significant enhancement of its cytotoxicity by the EDTA and LC preparations on both cell types. LPS showed some enhancement of the effect of toxin on Vero cells at the lowest levels of toxin investigated. It was concluded that this effect seen in vitro may have a role to play in the colon during infection with C. difficile.

Recombinant adenovirus mediated prostate-specific enzyme pro-drug gene therapy regulated by prostate-specific membrane antigen (PSMA) enhancer/promoter.

Gene directed enzyme pro-drug therapy (GDEPT) is one of the adjuvant therapeutic regimens for advanced prostate adenocarcinoma, and this research intended to explore how to apply targeting therapy of prostate adenocarcinoma under the mediation of a promoter/enhancer of prostate-specific membrane antigen (PSMA(EP)) as a specific regulatory element. Recombinant adenoviruses (Ad-PSMA(E-P)-enhanced green fluorescent protein [EGFP], Ad-CMV-EGFP, Ad-PSMA(E-P)-CD, and Ad-CMV-CD) were constructed and could express cytosine deaminase (CD) or the EGFP reporter gene driven by a PSMA(EP) or cytomegalovirus (CMV) promoter. LNCaP, CL-1, MCF-7, and A549 were infected with CD-produced recombinant adenoviruses and treated with pro-drug 5-fluorocytosine (5-FC) in vivo and vitro; then, the growth inhibition of the cells and the cell cycle variation were assessed by an [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay and flow cytometry. Growth suppression of the xenograft tumor was also adopted to evaluate the efficiency of the suicide system. Morphologic changes after treatment in vivo were assessed with hematoxylin and eosin staining. In the 4 examined cancer cell lines, PSMA-positive prostate cancer cells LNCap and CL-1 were exclusively sensitive to the Ad-PSMA(E-P)-CD/5-FC system. The S phase of cell cycle arrest was thought to be involved in the cytotoxicity of 5-fluorouracil (5-FU) converted from 5-FC by CD. CL-1 implanted Athymic BALB/c mice showed growth inhibition of tumors when they were treated with the Ad-PSMA(E-P)-CD/5-FC system without systemic conversion toxicity. The PSMA-based, CD-produced adenovirus, deserving further investigation in the future, might be a good candidate for targeting gene therapy of prostate adenocarcinoma.

Apoptosis-inducing membrane vesicles. A novel agent with unique properties.

The CD95 ligand (FasL) transmembrane protein is found on activated T cells and cells outside the immune system. A well-known turnover process of membrane FasL is mediated by matrix metalloproteinase, which generates soluble FasL (sFasL). Here, we demonstrate that membrane FasL turnover occurs effectively through the release of membrane vesicles. Quantitative analysis indicates that this process is as effective as sFasL release for FasL-3T3 cells but somewhat less effective for FasL-expressing T cells. The apoptosis-inducing membrane vesicles display unique properties not found in FasL-expressing cells and sFasL. Unlike sFasL, vesicle-associated FasL remained bioactive, killing the same panel of targets that are susceptible to FasL-expressing cells. In contrast to FasL-expressing T cells, FasL-mediated killing by vesicles do not involve LFA-1/ICAM interaction and do not depend on de novo protein synthesis. These observations indicate that the release of FasL-bearing vesicles contributes to the turnover of cell-associated FasL, but the impact of the bioactive FasL-expressing vesicles on the function of cell-associated FasL is different from that of sFasL.

Differential pathogenesis of lethal mousepox in congenic DBA/2 mice implicates natural killer cell receptor NKR-P1 in necrotizing hepatitis and the fifth component of complement in recruitment of circulating leukocytes to spleen.

Innate resistance of C57BL/6 (B6) mice to lethal mousepox is controlled by multiple genes. Previously, four resistance genes were localized to specific subchromosomal regions and transferred onto a susceptible DBA/2 (D2) background by serial backcrossing and intercrossing to produce congenic strains. Intraperitoneally inoculated ectromelia virus was uniformly lethal and achieved similar titers in B6 and D2 mice but elicited differential responses in liver, spleen, and circulating blood leukocytes. The distribution of these response phenotypes in congenic strains linked control of phenotypes with specific subchromosomal regions. D2.R1 mice, which carried a differential segment of chromosome 6, exhibited a B6 liver response and intermediate spleen and circulating leukocyte responses. D2.R2 and D2.R4 mice, which carried differential segments of chromosomes 2 and 1, respectively, exhibited a D2 liver response, a B6 spleen response, and an intermediate circulating leukocyte response. The localization of control of liver response phenotypes to chromosome 6 implicates cells that express natural killer (NK) cell receptor NKR-P1 alloantigens. The localization of control of spleen and circulating leukocyte responses to chromosomes 1, 2, and 6 implicates NK cells, the fifth component of complement, and a gene near the selectin gene complex in recruitment of circulating leukocytes to spleen.

Encephalitogenic epitopes of myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein for experimental allergic encephalomyelitis induction in Biozzi ABH (H-2Ag7) mice share an amino acid motif.

Myelin basic protein (MBP) and synthetic MBP peptides were screened for their ability to induce experimental allergic encephalomyelitis in Biozzi ABH (H-2Ag7) mice. In contrast to the failure of native MBP to induce experimental allergic encephalomyelitis, the use of overlapping MBP peptides revealed epitopes within MBP 12-26 and MBP 21-35, which induced mild disease. In comparison with disease induced by spinal cord homogenate or peptides of myelin oligodendrocyte glycoprotein (MOG) or proteolipid protein (PLP), the low incidence indicates that, at least in ABH mice, MBP is a minor encephalitogen. However, the data suggest the presence of a peptide core between MBP 21-26 (HARHGF), which contains similar elements to the previously defined encephalitogenic MOG 1-22 and PLP 56-70 peptides. The fine specificity of these epitopes was further investigated using frame-shifted peptides, which indicated cores between MOG 9-15 (GYPIRAL) and PLP 62-68 (NVIHAFQ). Based on these pathogenic peptides, a putative H-2Ag7 binding motif is suggested that contains a series of hydrophobic, basic, small, and large hydrophobic residues within a 6 to 7 amino acid core. The core and particular importance of these four residues in PLP 56-70 was confirmed in vitro using amino acid substitution studies. These findings support many of the predictions made by computer modeling of peptide:H-2Ag7 interactions. This may have relevance in the design of strategies in the treatment of experimental autoimmune diseases in animals that express this haplotype.

Safety and immunogenicity of an outer surface protein A vaccine in subjects with previous Lyme disease.

The safety and immunogenicity of a recombinant outer surface protein A (OspA) Lyme vaccine in patients previously diagnosed with Lyme disease was assessed in a dose-ranging, prospective study. Thirty healthy volunteers were consecutively assigned to receive three doses of 3, 10, or 30 micrograms of OspA vaccine at 0, 1, and 2 months. Subjects were seen 3 days after each vaccine dose and 1 month after completion of the three-dose schedule. Local side effects included soreness, induration, swelling, and redness. Transient systemic side effects occurred in 21 subjects, the majority of which (81%) were characterized as mild. Solicited symptoms included migratory mild arthralgias that lasted 24 h in 3 subjects. Side effects were not more evident after the second or third dose. Of the patients, 93% developed high-titer OspA antibodies. Thus, an OspA vaccine may be safe and immunogenic in patients with a history of Lyme disease.

Local Fas/APO-1 (CD95) ligand-mediated tumor cell killing in vivo.

Fas/APO-1 (CD95) is a cell surface receptor which mediates apoptosis when ligated by specific antibodies or by its recently cloned natural ligand, FasL. We have studied the cytotoxic potential of FasL in vivo using Fas/APO-1-expressing Yac-1 cells as targets. Supernatant harvested from Neuro-2a cells transfected with the murine FasL cDNA contains FasL and transduces a potent apoptotic signal to Yac-1 cells in vitro. Specificity of FasL-mediated cytotoxicity was confirmed by competition assays using soluble Fas or anti-Fas/APO-1 F(ab')2 fragments which specifically interfere with FasL-Fas/APO-1 interactions. Intraperitoneal injection of FasL-containing supernatant efficiently killed Yac-1 target cells which had been implanted in capsules into the peritoneal cavity of mice. Analysis of the target cells revealed DNA fragmentation and nuclear changes typical of apoptosis. As previously shown, intraperitoneal injection of anti-Fas/APO-1 antibodies caused liver failure (Ogasawara, J., Watanabe, F.R., Adachi, M., Matsuzawa, A., Kasugai, T., Kitamura, Y., Itoh, N., Suda, T. and Nagata, S., Nature 1993. 364:806) and was observed at doses which did not reduce Yac-1 cell viability. In contrast, FasL did not induce histopathology in the liver when applied intraperitoneally at doses cytotoxic for Yac-1 cells. However, intravenous administration of FasL induced lethal liver hemorrhages and hepatocyte apoptosis. Thus, locally applied FasL kills tumor cells very efficiently without systemic toxicity and may therefore represent a candidate for local tumor treatment.

An OspB mutant of Borrelia burgdorferi has reduced invasiveness in vitro and reduced infectivity in vivo.

Most Borrelia burgdorferi strains have two major surface proteins, OspA and OspB. In the present study, we selected from a clonal population of infectious B. burgdorferi an OspB escape mutant, identified the genetic basis for this phenotype, and evaluated its functional activities. Selection with the anti-OspB antibody H614 was performed in vitro in medium and extended in vivo in scid mice. Mutants with a truncated OspB protein were selected at a frequency of 1 x 10(-5) to 3 x 10(-5). After no major rearrangements in DNA were detected, sequence analysis of the mutant's ospAB locus revealed a single base change in the consensus ribosomal binding sequence for ospB and a single nucleotide deletion in the ospB gene itself. The effect of these mutations was reduced expression of a truncated OspB protein. When functional abilities of the wild type and mutant were compared, the mutant had a threefold-lower capacity to penetrate a human endothelium umbilical vein cell monolayer. Infectivity of wild-type and mutant cells for scid mice was evaluated by culturing different organs, and the median infectious dose was calculated. The inoculum of mutant cells for infecting the mice was 30- to 300-fold higher than that of wild-type cells. This study shows that reduced size and expression of OspB are associated with lowered virulence of B. burgdorferi. Selection of mutants that to some degree remain infectious is one approach to defining the role of different surface proteins in the pathogenesis of Lyme disease.

The role of the O-antigen lipopolysaccharide and capsule on an experimental Klebsiella pneumoniae infection of the rat urinary tract.

We obtained, by different methods, isogenic lipopolysaccharide (O antigen) and capsular polysaccharide (K antigen) mutants from Klebsiella pneumoniae strains able to induce experimental infections (cystitis and pyelonephritis) in rats. We compared the induction of experimental infections in rats by wild-type strains and the lipopolysaccharide and capsular polysaccharide mutants. The high-molecular mass lipopolysaccharide of K. pneumoniae is clearly implicated in the infection process of the rat urinary tract, whilst the capsular polysaccharide seems not to be involved to the same extent.

[The safety of a new chemical typhoid preparation containing a complex of Vi and K antigens in tests of its acute and chronic toxicity]. / Bezvrednost' novogo khimicheskogo briushnotifoznogo preparata, soderzhashchego kompleks Vi- i K-antigenov, v testakh ostroi i khronicheskoi toksichnosti.

Acute and chronic toxicity of a new chemical typhoid preparation containing the complex of surface Vi- and K-antigens has been studied. The study has revealed that the preparation, when introduced subcutaneously and intravenously in immunizing doses in a single injection or in multiple injections, produces no toxic effect on the organs and tissues of experimental animals. In experiments of chronic toxicity the microscopic study has shown pronounced hyperplasia of the lymphoid system with enhanced macrophage reaction in the spleen, thymus, mesenteric lymph nodes and Peyer's patches in the small intestine.

[The role of the surface antigens of Pseudomonas pseudomallei in the pathogenesis of melioidosis]. / Rol' poverkhnostnykh antigenov Pseudomonas pseudomallei v patogeneze melioidoza.

As established with the use of electron-immunochemical techniques, glycoprotein antigen 6 is the outer membrane component of P. pseudomallei cell wall, while glycoprotein antigen 8 is localized on the cell surface as a capsule-like formation. Antigen 6 plays no perceptible role in the realization of the pathogenic properties of the infective agent, but serves as a reliable sign in the differentiation of P. pseudomallei strains into serovars. Subcultures, defective in the synthesis of antigen 8, have sharply reduced virulence for laboratory animals. As revealed in this study, the pathogenetic action of antigen 8 is linked with its pronounced antiphagocytic function. Thus, antigen 8 is considered to be one of the key pathogenicity factors of P. pseudomallei.

The toxicity of Bacteroides thetaiotaomicron cell-surface antigens to chicken embryos.

The toxicity of B. thetaiotaomicron lipopolysaccharides and capsular antigen to 11-day-old chicken embryos was examined. CELD50 (chicken embryo LD50) of these preparations were determined. All examined preparations showed the lethal activity for chicken embryos. The toxicity of lipopolysaccharides was much higher than the toxicity of capsular antigen.

Evidence that a glycolipid tail anchors antigen 117 to the plasma membrane of Dictyostelium discoideum cells.

We describe the biochemical features of the putative cell cohesion molecule antigen 117, indicating that it is anchored to the plasma membrane by a glycolipid tail. Antigen 117 can be radiolabeled with [3H]myristate, [3H]palmitate, and [14C]ethanolamine. The fatty acid label is removed by periodate oxidation and nitrous acid deamination, indicating that the fatty acid is attached to the protein by a structure containing carbohydrate and an unsubstituted glucosamine. As cells develop aggregation competence, the antigen is released from the cell surface in a soluble form that can still be radiolabeled with [14C]ethanolamine but not with [3H]myristate or [3H]palmitate. The molecular weight of the released antigen is similar to that found in the plasma membrane, but it preferentially partitions in Triton X-114 as a hydrophilic, as opposed to a hydrophobic, protein. Plasma membranes contain the enzyme activity responsible for the release of the antigen in a soluble form.

The importance of extracellular antigens in Pseudomonas cepacia infections.

A clinical isolate of Pseudomonas cepacia from a cystic fibrosis patient was examined for its ability to produce extracellular toxic material. The organism was grown to stationary phase in a defined medium and toxic material was isolated by ultrafiltration, ion-exchange chromatography on DEAE-Sephacel and gel-filtration chromatography on Sepharose 4B. It consisted of a surface carbohydrate antigen, lipopolysaccharide and protein, and had an LD50 (when injected intraperitoneally into mice) of 395 +/- 20 micrograms. The toxicity appeared to be associated with the lipopolysaccharide portion of the complex, because boiling for 15 min and exposure to proteolytic enzymes had no effect on toxicity. However, saponification destroyed the toxicity of the compound. Studies employing radial immunodiffusion with the sera of mice infected with this organism demonstrated production of the complex in vivo at levels approaching those sufficient to produce death. When sublethal amounts of this complex were placed in the lungs of specific-pathogen-free rats, the lung pathology observed after 12, 24, 36 and 48 h was extensive. However, antibody generated in rabbits against this material could protect mice against the complex, as well as against challenge by the homologous organism. These data indicate that extracellular toxic material produced by P. cepacia may be responsible for the lethality and lung tissue destruction normally associated with an active pneumonia caused by this organism.

Coli surface antigens 1 and 3 of colonization factor antigen II-positive enterotoxigenic Escherichia coli: morphology, purification, and immune responses in humans.

Enterotoxigenic Escherichia coli (ETEC) of serotype O6:H16, biotype A, bearing colonization factor antigen II (CFA/II) possesses two distinct coli surface antigens, CS1 and CS3, whereas CFA/II-positive ETEC of serotype O8:H9 manifests only CS3. CS1 has been shown to be fimbrial in nature, but heretofore the morphology of CS3 has not been described. Accordingly, by immune electron microscopy we investigated the morphological characteristics of CS3 on bacterial cells and after purification. CS3 was found to consist of thin (2-nm), flexible, wiry, "fibrillar" fimbriae, visible both on bacteria (O6:H16, biotype A, and O8:H9 strains) and in the pure state. In contrast, CS1 exists as wider (6-nm), rigid fimbriae on the surface of O6:H16, biotype A, strains. By the use of antisera to CS1 and CS3 in immune electron microscopy, immunodiffusion in gel, and immunoblotting techniques, CS1 and CS3 were found to be immunologically as well as morphologically distinct. Six of nine volunteers who developed diarrhea after challenge with an O139:H28 ETEC strain bearing CS1 and CS3 had significant serological rises to purified CS1 and CS3 antigens, suggesting that both antigens are elaborated in vivo, play a role in pathogenesis, and stimulate an immune response.

[Isolation and characteristics of E. coli plasmid-determined K88 antigen]. / Vydelenie i kharakteristika determinirovannogo plazmidoi antigena K88 kishechnoi palochki.

The advantage of ultracentrifugation over isoelectric focusing in the isolation of antigen K88 from E. coli is shown. The production of antigen K88 is recA-independent. The antigen has been found to be nontoxic for mice, to have the isoionic point at pH 4.1 and the sedimentation coefficient 16.6S, to completely consist of protein subunits of 25,000 daltons. The expression of antigen K88 enhances the adhesive properties of the host cell. No relationship between antigen K88 and the supposed adhesins of both Vibrio cholerae biotypes has been established.

[Enterotoxic activity of the pseudotuberculosis microbe]. / Issledovanie énterotoksicheskoi aktivnosti psevdotuberkuleznogo mikroba.

For the first time the activity of Y. pseudotuberculosis, its extracellular, surface antigen and Westphal's lipolysaccharide has been studied with the use of biological models (the ligated loop of the small intestine of a rabbit, the pulmonary model, the intradermal tests). This microorganism has been found capable of inducing the accumulation of exudate in the ligated loop of the small intestine of a rabbit and interfering with the permeability of the vascular walls. The toxic action of Y. pseudotuberculosis is neutralized by immunization.