Canine bone marrow peri-adipocyte cells could therapeutically benefit acute spinal cord injury through migration and secretion of hepatocyte growth factor to inflammatory milieu.

Spinal cord injury (SCI) is a common neurological disorder in dogs. A secondary injury that occurs in the acute phase causes expansion of inflammation, resulting in lesion extension and further loss of function. Mesenchymal stem cells (MSCs) have trophic effects and the ability to migrate toward injured tissues; therefore, MSC-based therapy is considered promising for the treatment of canine SCI. We recently reported that bone marrow peri-adipocyte cells (BM-PACs) can be obtained from canine bone marrow and have stem cell potential superior to that of conventional bone marrow MSCs (BMMSCs). However, their therapeutic potential for SCI have been still unknow. Here, we first evaluated the ability of BM-PACs to secrete hepatocyte growth factor (HGF) and their migration ability toward inflammatory milieu in vitro. BM-PACs can secrete HGF in response to pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and IL-1ß, and exhibit migration ability toward these cytokines. Next, BM-PACs were intravenously administered into nude mice with acute SCI to analyze the homing ability and therapeutic effects of HGF secreted by BM-PACs. BM-PACs homed to the injured spinal cord, where the HGF expression level increased 7 days after administration. Intravenous administration of BM-PACs induced functional recovery and pathological improvement, indicated by less demyelinating area, more preserved axons, and less glial scar formation compared with the mice only received vehicle. These findings suggest that the intravenous administration of BM-PACs can be a novel therapeutic intervention for acute canine SCI.

In vivo evidence for possible up-regulating roles of lysophosphatidic acid around fertilization in rats.

Lysophosphatidic acid (LPA) produced by autotaxin (ATX) is recognized as a multi-functional mediator in mammalian reproduction. This study focused on possible effect(s) of LPA on ovulated cumulus-oocyte complexes (COCs) around fertilization in rats in vivo. Immunohistochemistry revealed the cell-type-dependent localization of candidates of synthetic enzymes, ATX and two phospholipases A2 isofroms, and LPA receptors LPA1-4 in ovulated COCs and in oviductal epithelium. The eggs ovulated with a form of COCs became denuded of cumulus cells and underwent fragmentation in the absence of fertilization. In vivo experiments of local administration in non-copulated rats demonstrated that eggs denudation was increased by LPA and decreased by anti-ATX antibody and that fragmentation was inhibited by LPA and stimulated by an ATX chemical inhibitor. Furthermore, LPA administration in adult copulated rats increased the rate of cleaved embryos significantly. Obtained results suggest the presence of LPA synthesis and action system in ovulated COCs within the oviductal ampulla and positive actions of LPA possibly at multiple sites around fertilization in rats.

Isolation and Characterization of Multipotent Mesenchymal Stem Cells Adhering to Adipocytes in Canine Bone Marrow.

The ceiling culture method has been used to isolate mature adipocytes from adipose tissue that can be dedifferentiated into fibroblastic cells, also known as dedifferentiated fat (DFAT) cells that self-renew and are multipotent, with much higher homogeneity and colony-forming efficiency than those of adipose tissue-derived mesenchymal stem cells. We cultured adipocytes from canine bone marrow using this technique, with the expectation of obtaining DFAT cells. However, contrary to our expectations, continuous monitoring of ceiling cultures by time-lapse microscopy revealed many small cells adhering to adipocytes that proliferated rapidly into cells with a fibroblastic morphology and without any dedifferentiation from adipocytes. We named these cells bone marrow peri-adipocyte cells (BM-PACs) and demonstrated the multipotent properties of BM-PACs compared to that of conventionally cultured canine bone marrow mesenchymal stem cells (BMMSCs). BM-PACs showed significantly greater clonogenicity and proliferation ability than BMMSCs. An in vitro trilineage differentiation assay revealed that BM-PACs possess adipogenic, osteogenic, and chondrogenic capacities superior to those of BMMSCs. Flow cytometric analysis revealed that the expression of CD73, which plays an important role in cell growth and differentiation, was significantly higher in BM-PACs than in BMMSCs. These results indicate that canine BM-PACs have stem cell characteristics that are superior to those of BMMSCs, and that these mesenchymal stem cells (MSCs) appear to be a feasible source for cell-based therapies in dogs.

Characterization of a Shiga toxin 1-neutralizing recombinant Fab fragment isolated by phage display system.

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Molecular structural analysis of Stx-neutralizing monoclonal antibody (mAb) will be helpful for development of therapeutics and prophylactics for STEC infection. In this study, we cloned the genes of Stx 1-neutralizing mAb, termed 5-5B from hybridoma cells by phage display system and characterized its recombinant Fab (rFab) fragment. 5-5B rFab fragment reacted with Stx1, but not with Stx2 and bovine serum albumin (BSA). It also showed the neutralizing activity against the cytotoxicity of Stx1. These results imply that 5-5B rFab fragment is functionally identical to parent mAb. The variable heavy (VH) and light domains were found to be highly homologous with the derived germ line sequences. As for VH domain, the complementarity determining regions (CDRs) showed higher replacement/substitution mutation ratio than that in the frame work regions. Among the regions, CDR2 showed the most frequent nucleotide and amino acid substitutions. These results suggest that heavy chain CDR2 may mainly be associated with the 5-5B function, that is neutralizing cytotoxicity of Stx1.

Characterization of a shiga-toxin 1-resistant stock of vero cells.

Shiga toxins (Stxs, also referred to as verotoxins) were first described as a novel cytotoxic activity against Vero cells. In this study, we report the characterization of an Stx1-resistant (R-) stock of Vero cells. (1) When the susceptibility of R-Vero cells to Stx1 cytotoxicity was compared to that of Stx1-sensitive (S-) Vero cells by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay, cell viability after 48-hr exposure to 10 pg/ml of Stx1 was greater than 80% and less than 15%, respectively. (2) Although both a binding assay of fluorescence-labeled Stx1 and lipid analysis indicated considerable expression of Gb3Cer, a functional receptor for Stxs, in both Vero cells, anti-Gb3Cer monoclonal antibodies capable of binding to S-Vero cells failed to effectively label R-Vero cells, suggesting a conformational difference in the Gb3Cer expressed on R-Vero cells. (3) The lipid analysis also showed that the R-Vero cells contained significant amounts of Gb4Cer. In addition, introduction of exogenous Gb4Cer into S-Vero cells slightly inhibited Stx1 cytotoxicity, suggesting some correlation between glycosphingolipid composition and Stx1 resistance. (4) Both butyrate treatment and serum depression eliminated the Stx1 resistance of R-Vero cells. (5) The results of the analysis by confocal microscopy suggest a difference in intracellular transport of Stx1 between R-Vero and S-Vero cells. Further study of R-Vero cells may provide a model of Stx1 resistance via distinct intracellular transport of Stx1.

Subtyping of Shiga toxin 2 variants in human-derived Shiga toxin-producing Escherichia coli strains isolated in Japan.

Shiga toxin 2 (Stx2) variants have been found to exhibit not only antigenic divergence, but also differences in toxicity for tissue culture cells and animals. To clarify whether all or just a subset of Stx2 variants are important for the virulence of Shiga toxin-producing Escherichia coli, we designed PCR primers to detect and type all reported variants. We classified them into four groups according to the nucleotide sequences of the Stx2 family; for example, group 1 (G1) contains VT2vha and group 2 (G2) contains VT2d-Ount. The 120 strains of Shiga toxin-producing E. coli used in this study were isolated from humans in Japan between 1986 and 1999. Among the four variant groups, the G1 gene only was detected in 23 of the 120 clinical strains (19.2%) and all belonged to the O157 serotype. G1 is considered the most important Stx2 variant group in terms of human pathogenicity. A multiplex PCR that can detect the stx1, stx2, and G1 genes was developed as a means of rapid and easy typing to better understand the roles of the different types of Stx.

Shiga toxin 2 induces macrophage-granulocyte colonies from human bone marrow and cord blood stem cells.

Addition of Shiga toxin 2 to human bone marrow or cord blood cell culture induced macrophage-granulocyte colonies. Although Shiga toxin 2 alone induced colonies mainly composed of macrophages, it induced colonies mainly consisting of granulocytes when combined with physiological doses of interleukin-1beta, granulocyte colony-stimulating factor, or stem cell factor with interleukin-3.

Development of humanized monoclonal antibody TMA-15 which neutralizes Shiga toxin 2.

A murine monoclonal antibody (MAb), VTm1.1, specifically recognizing and neutralizing Shiga toxin 2 (Stx2), was obtained. To prevent a humoral response against murine antibody when used clinically, a humanized antibody was constructed by combining the complementarity-determining regions of VTm1.1 with human framework and constant regions. In addition, several amino acids in the framework were changed to improve the binding affinity of the antibody and further reduce its potential immunogenicity. The humanized antibody, TMA-15, recognized the B-subunit of Stx2 and had affinity for Stx2 of 3.3 x 10(-9) M, within two-fold of that of the original murine antibody. TMA-15 neutralized the cytotoxicity of Stx2 and several different Stx2 variants in vitro, and it completely protected mice from death in a Stx2-challenged mice model. These results suggest that TMA-15 will have clinical potency in Stx-producing Escherichia coli infections, including E. coli O157 infections.

Convenient use of non-malodorous thioglycosyl donors for the assembly of multivalent globo- and isoglobosyl trisaccharides.

New thioglycosyl donors (o-methoxycarbonylphenyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-galactopyranoside and its 6-O-acetyl analogue) were designed and used for the synthesis of glycoconjugate polymers carrying Gb(3) [Gal(alpha1-->4)Gal(beta1-->4)Glc] and isoGb(3) [Gal(alpha1-->3)Gal(beta1-->4)Glc] clusters as side chains. These donors scarcely evolved the unpleasant odor of thiophenols and showed a high alpha-anomeric selectivity in the galactosylation of p-nitrophenyl beta-lactoside derivatives, although in moderate yields. The derived trisaccharides were converted to multivalent carbohydrate ligands and were subjected to a biological assay with Shiga toxins. The multivalent Gb(3) ligand was highly active in inhibiting the toxicity, while the isoGb(3) ligand showed no activity, indicating that Stx-I discriminates between the carbohydrate structures.

Preventive effect of TAK-751S on complications of hemorrhagic colitis (results of clinical study of TAK-751S).

BACKGROUND: The effective therapy for hemolytic uremic syndrome and encephalopathy caused by enterohemorrhagic Escherichia coli have not been established. Great attention has been drawn to the results of the clinical study of TAK-751S, performed in Canada. In Japan, a nationwide clinical study of TAK-751S had been performed since 1997 to investigate the preventive effect on the onset of HUS and the safety. METHODS: TAK-751S was administered in daily doses of 500 mg/kg for one week to 128 pediatric patients with colitis who were suspected of enterohemorrhagic Escherichia coli (EHEC) infection. RESULTS: 1. TAK-751S was confirmed to absorb Shiga toxin (Stx) existing inside the human intestine and to excrete Stx out of the body. 2. The incidence of HUS is 5.9% (4/68) and a tendency to inhibit the onset of HUS was observed as compared with the historical control. The complications of central neuropathy such as encephalopathy were observed in 3 of these patients with HUS. 3. Mild "sweating" and "nausea" were observed. There were 13 mild non-specific abnormalities of laboratory test values in 8 patients. CONCLUSIONS: From these results, it was clarified that TAK-751S absorbed and removed free Stx in the intestinal tract of pediatric patients with EHEC infection. The test drug could not inhibit the onset of HUS completely, but since HUS occurred within 48 hours after the start of administration in 3 of the 4 patients with onset of HUS, TAK-751S is a safe drug for pediatric patients with EHEC infection in which the preventive effect on HUS and encephalopathy are expected when it can be given from an early stage of the diseases. Furthermore, these results suggest that importance of rapid diagnosis of HUS.

Inhibition of shiga toxin cytotoxicity in human renal cortical epithelial cells by nitrobenzylthioinosine.

Nitrobenzylthioinosine (NBTI), a nucleoside-transport inhibitor, has been found to possess the ability to prevent the cytotoxic action of Shiga toxin (Stx) 1 in human renal cortical epithelial cells (HRCECs), thereby protecting HRCECs from cell death. Further examination revealed that NBTI does not affect either the binding or the endocytosis of Stx1 but alters the intracellular transport of Stx1. Generally, endocytosed Stx1 is thought to be transported from endosomes to the endoplasmic reticulum. In NBTI-treated cells, however, the endocytosed Stx1 is delivered to an early endosome, but no further transportation occurs. Moreover, Stx1 is rapidly excreted from NBTI-treated HRCECs, preventing the accumulation of Stx1. Investigation of the NBTI-mediated protection mechanism against Stx cytotoxicity may provide insights into the analysis of Stx-mediated cell damage and lead to improvements in therapeutic approaches for diseases caused by Stx.

Monoclonal antibody to shiga toxin 1, which blocks receptor binding and neutralizes cytotoxicity.

A monoclonal antibody, 5-5B, which neutralizes Shiga toxin 1 (Stx1) cytotoxicity of Escherichia coli, was constructed. An epitope analysis indicated that Asn55 in Stx1 B subunit was an important residue. This result and our previous results using an anti-Stx2 monoclonal antibody indicate that the region around the cysteine residue of the disulfide bond might be important for the neutralization of Stx cytotoxicity, making it a potential vaccination candidate.