ヒト初乳由来分泌型IgAはボツリヌスB型16S毒素と結合し，毒素のT84細胞への結合を抑制する

Botulinum neurotoxin produced by Clostridium botulinum type B is in the form of a complex of 12S and 16S toxins. Food-borne botulism is caused by these complex toxins which are ingested orally and absorbed from the digestive tract. Here, we show that the human milk SIgA binds to the type B16S toxin. The binding of SIgA to 16S toxin and HA was inhibited by carbohydrates such as galactose, suggesting that the interaction of carbohydrate side chain of the SIgA with the HA of the 16S toxin is important for SIgA-16S complex formation. We also demonstrate that SIgA inhibits the attachment of 16S toxin to intestinal epithelial cells. These data suggest that the interaction of antigen nonspecific SIgA with 16S toxin has a large influence on the absorption of 16S toxin from the intestinal epithelium, and that SIgA may provide insight into developing a therapeutic agent for type B food-borne botulism

Botulinum hemagglutinin disrupts the intercellular epithelial barrier by directly binding E-cadherin

Botulinum neurotoxin's nontoxic HA protein binds E-cadherin to disrupt cell–cell adhesion in a species-specific manner

Collagen adhesion gene is associated with blood stream infections caused by methicillin-resistant Staphylococcus aureus

Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) causes hospital- and community-acquired infections. It is not clear whether genetic characteristics of the bacteria contribute to disease pathogenesis in MRSA infection. We hypothesized that whole genome analysis of MRSA strains could reveal the key gene loci and/or the gene mutations that affect clinical manifestations of MRSA infection. Methods: Whole genome sequences (WGS) of MRSA of 154 strains were analyzed with respect to clinical manifestations and data. Further, we evaluated the association between clinical manifestations in MRSA infection and genomic information. Results: WGS revealed gene mutations that correlated with clinical manifestations of MRSA infection. Moreover, 12 mutations were selected as important mutations by Random Forest analysis. Cluster analysis revealed strains associated with a high frequency of bloodstream infection (BSI). Twenty seven out of 34 strains in this cluster caused BSI. These strains were all positive for collagen adhesion gene (cna) and have mutations in the locus, those were selected by Random Forest analysis. Univariate and multivariate analysis revealed that these gene mutations were the predictor for the incidence of BSI. Interestingly, mutant CNA protein showed lower attachment ability to collagen, suggesting that the mutant protein might contribute to the dissemination of bacteria. Conclusions: These findings suggest that the bacterial genotype affects the clinical characteristics of MRSA infection. (c) 2019 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases

Age, gender, will, and use of home-visit nursing care are critical factors in home care for malignant diseases; a retrospective study involving 346 patients in Japan

<p>Abstract</p> <p>Background</p> <p>We aimed to clarify the factors affecting outcomes of home care for patients with malignant diseases.</p> <p>Methods</p> <p>Of 607 patients who were treated in 10 clinics specialized in home care between January and December 2007 at Chiba, Fukuoka, Iwate, Kagoshima, Tochigi and Tokyo prefectures across Japan, 346 (57%; 145 men and 201 women) had malignant diseases. We collected information on medical and social backgrounds, details of home care, and its outcomes based on their medical records.</p> <p>Results</p> <p>Median age of the patients was 77 years (range, 11-102), and 335 patients were economically self-sufficient. Their general condition was poor; advanced cancer (n = 308), performance status of 3-4 (n = 261), and dementia (n = 121). At the beginning of home care, 143 patients and 174 family members expressed their wish to die at home. All the patients received supportive treatments including fluid replacement and oxygenation. Median duration of home care was 47 days (range, 0-2,712). 224 patients died at home. For the remaining 122, home care was terminated due to complications (n = 109), change of attending physicians (n = 8), and others (n = 5). The factors which inhibited the continuity of home care were the non-use of home-visit nursing care (hazard ratio [HR] = 1.78, 95% confidence interval [CI]: 1.05-3.00, <it>p </it>= 0.03), the fact that the patients themselves do not wish to die at home (HR = 1.83, CI: 1.09-3.07, <it>p </it>= 0.02), women (HR = 1.81, CI: 1.11-2.94, <it>p </it>= 0.02), and age (HR = 0.98, CI: 0.97-1.00, <it>p </it>= 0.02).</p> <p>Conclusions</p> <p>Continuation of home care is influenced by patients' age, gender, will, and use of home-visit nursing.</p

ボツリヌス神経毒素複合体と腸管免疫系細胞との相互作用の解析

金沢大学医薬保健研究域医学系ボツリヌス食中毒はボツリヌス神経毒素複合体を経口的に摂取することにより発症する。我々はこれまでに、中毒発症に必須な過程であるにも関わらず不明であった血清型A1型神経毒素複合体の腸管吸収機構を明らかにした。本研究において、我々は血清型B1型神経毒素複合体がA1型とは異なる機構で腸管から宿主内へ侵入することを発見した。さらにA1型、B1型いずれの神経毒素複合体も腸管上皮直下のsub-epithelial dome (SED)において免疫細胞と共局在していた。これらの結果から、腸管免疫細胞はA1型およびB1型神経毒素の血中への移行に影響しており、ボツリヌス食中毒の発症に関与していることが示唆された。Food-borne botulism is caused by ingestion of botulinum neurotoxin (BoNT) complexes which composed of BoNT and one or more neurotoxin-associated proteins (NAPs). We have uncovered the site(s) and mechanism of intestinal absorption of type A1 BoNT complex, heretofore largely unknown, which is essential for the onset of food-borne botulism.In this study, we found that type B1 BoNT complex invades into the host from intestine by different mechanisms from type A1. Furthermore, we observed that both type A and type B BoNT complex interact with immune cells which are located in sub-epithelial dome (SED). These results suggest that intestinal immune cells influence the entry of type A1 or type B1 BoNT into the blood stream and are involved in the onset of food-borne botulism.研究課題/領域番号:16K19123, 研究期間(年度):2016-04-01 - 2018-03-3

腸管上皮バリアを破壊するボツリヌスHAの基質分子の探索及び作用機構の解析

本研究では、ボツリヌス神経毒素複合体中の無毒成分の一つであるHemagglutinin(HA)の持つ腸管上皮細胞間バリア破壊作用について解析した。HAのバリア破壊作用を引き起こす基質分子の探索において、Recombinant HAを用いた解析により、ヒト腸管上皮細胞からHAと特異的に結合する標的分子が得られた。次にHAの作用メカニズムを解析する目的で、生体内における動態を解析した結果、HAは特異的な細胞から取り込まれ、その細胞からバリア破壊を引き起こすことが明らかとなった。In this study, we analyzed the mechanism of disruption of epithelial paracellular barrier function caused by botulinum HA. Using recombinant HA, we purified HA-binding proteins from human intestinal epithelial cell lines. Next, we analyzed the localization of botulinum toxins in vivo . The HA bound and transcytosed to the basolateral side and disrupted the epithelial barrier at the specific cells

HA/B complex binds to mucins through carbohydrate recognition by HA1/B and HA3/B.

<p>(A) Mucin binding of GST-HA1/B. Mucin binding of GST, GST-HA1/B, and GST-HA1/B harboring Asn286 to Ala mutation (N286A) was assessed as described in Materials and Methods. Binding of GST-HA1/B was measured in the presence or absence of 100 mM glucose (Glc) or galactose (Gal). HA1/B preferentially bound to PGM in a galactose-binding-dependent manner. (B) Mucin binding of GST, GST-HA3/B, and GST-HA3/B harboring Arg528 to Ala mutation (R528A). Binding of GST-HA3/B was assessed with the coated mucin pretreated with (+Neu) or without 5 mU/ml neuraminidase. HA3/B preferentially bound to BSM in a sialic-acid-dependent manner. (C) Mucin binding of HA/B complex (WT) and those harboring either HA1/B N286A or HA3/B R528A, or both (HA/B harboring HA1 N286A mutation, HA1 m; HA/B harboring HA3 R528A mutation, HA3 m; HA/B harboring HA1N286A and HA3 R528A mutations, HA1 m/HA3 m). The results show that carbohydrate binding activities of HA1 and HA3 are fully functional in the HA/B complex. Values are means ± S.E.M. from three independent experiments. *<i>p</i><0.05, unpaired <i>t</i> test.</p

Crystal structure and the carbohydrate and E-cadherin binding sites of the HA/B complex.

<p>The galactose binding sites of HA1 (Asn286) are colored blue and marked with dotted blue circles. The sialic acid-binding sites of HA3 (Arg528) are colored magenta and marked with dotted magenta circles. The E-cadherin binding sites of HA3 (Leu473, M508, and Lys607) are colored red and marked with dotted red circles. These sites are structurally independent. Each of the three HA monomers is colored pale cyan, pale yellow, or pink.</p