Association between the ABO blood group and the human intestinal microbiota composition

ABSTRACT: BACKGROUND: The mucus layer covering the human intestinal epithelium forms a dynamic surface for host-microbial interactions. In addition to the environmental factors affecting the intestinal equilibrium, such as diet, it is well established that the microbiota composition is individually driven, but the host factors determining the composition have remained unresolved. RESULTS: In this study, we show that ABO blood group is involved in differences in relative proportion and overall profiles of intestinal microbiota. Specifically, the microbiota from the individuals harbouring the B antigen (secretor B and AB) differed from the non-B antigen groups and also showed higher diversity of the Eubacterium rectale-Clostridium coccoides (EREC) and Clostridium leptum (CLEPT) -groups in comparison with other blood groups. CONCLUSIONS: Our novel finding indicates that the ABO blood group is one of the genetically determined host factors modulating the composition of the human intestinal microbiota, thus enabling new applications in the field of personalized nutrition and medicine.     

Cloning, expression, and characterization of novel thermostable family 7 cellobiohydrolases

As part of the effort to find better cellulases for bioethanol production processes, we were looking for novel GH-7 family cellobiohydrolases, which would be particularly active on insoluble polymeric substrates and participate in the rate-limiting step in the hydrolysis of cellulose. The enzymatic properties were studied and are reported here for family 7 cellobiohydrolases from the thermophilic fungi Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum. The Trichoderma reesei Cel7A enzyme was used as a reference in the experiments. As the native T. aurantiacus Cel7A has no carbohydrate-binding module (CBM), recombinant proteins having the CBM from either the C. thermophilum Cel7A or the T. reesei Cel7A were also constructed. All these novel acidic cellobiohydrolases were more thermostable (by 4-10 degrees C) and more active (two- to fourfold) in hydrolysis of microcrystalline cellulose (Avicel) at 45 degrees C than T. reesei Cel7A. The C. thermophilum Cel7A showed the highest specific activity and temperature optimum when measured on soluble substrates. The most effective enzyme for Avicel hydrolysis at 70 degrees C, however, was the 2-module version of the T. aurantiacus Cel7A, which was also relatively weakly inhibited by cellobiose. These results are discussed from the structural point of view based on the three-dimensional homology models of these enzymes.     

Confronting fusion protein-based membrane protein topology mapping with reality: the Escherichia coli ClcA H+/Cl- exchange transporter

The topology of bacterial inner membrane proteins is commonly determined using topology reporters such as alkaline phosphatase and green fluorescent protein fused to a series of C-terminally truncated versions of the protein in question. Here, we report a detailed topology mapping of the Escherichia coli inner membrane H⁺/Cl⁻ exchange transporter ClcA. Since the 3-D structure of ClcA is known, our results provide a critical test of the reporter fusion approach and offer new insights into the ClcA folding pathway.     

CD47 expression on T cell is a self-control negative regulator of type 1 immune response

The cytokine milieu and dendritic cells (DCs) direct Th1 development. Yet, the control of Th1 polarization by T cell surface molecules remains ill-defined. We here report that CD47 expression on T cells serves as a self-control mechanism to negatively regulate type 1 cellular and humoral immune responses in vivo. Th2-prone BALB/c mice that lack CD47 (CD47(-/-)) displayed a Th1-biased Ab profile at steady state and after immunization with soluble Ag. CD47(-/-) mice mounted a T cell-mediated exacerbated and sustained contact hypersensitivity (CHS) response. After their adoptive transfer to naive CD47-deficient hosts 1 day before immunization with soluble Ag, CD47(-/-) as compared with CD47(+/+)CD4(+) transgenic (Tg) T cells promoted the deviation of Ag-specific T cell responses toward Th1 that were characterized by a high IFN-gamma:IL-4 cytokine ratio. Although selective CD47 deficiency on DCs led to increased IL-12p70 production, CD47(-/-)Tg T cells produced more IFN-gamma and displayed higher T-bet expression than CD47(+/+) Tg T cells in response to OVA-loaded CD47(-/-) DCs. CD47 as part of the host environment has no major contribution to the Th1 polarization responses. We thus identify the CD47 molecule as a T cell-negative regulator of type 1 responses that may limit unwanted collateral damage to maximize protection and minimize host injury.     

Identification of a posttranslational mechanism for the regulation of hERG1 K+ channel expression and hERG1 current density in tumor cells

A common feature of tumor cells is the aberrant expression of ion channels on their plasma membrane. The molecular mechanisms regulating ion channel expression in cancer cells are still poorly known. K(+) channels that belong to the human ether-a-go-go-related gene 1 (herg1) family are frequently misexpressed in cancer cells compared to their healthy counterparts. We describe here a posttranslational mechanism for the regulation of hERG1 channel surface expression in cancer cells. This mechanism is based on the activity of hERG1 isoforms containing the USO exon. These isoforms (i) are frequently overexpressed in human cancers, (ii) are retained in the endoplasmic reticulum, and (iii) form heterotetramers with different proteins of the hERG family. (iv) The USO-containing heterotetramers are retained intracellularly and undergo ubiquitin-dependent degradation. This process results in decreased hERG1 current (I(hERG1)) density. We detailed such a mechanism in heterologous systems and confirmed its functioning in tumor cells that endogenously express hERG1 proteins. The silencing of USO-containing hERG1 isoforms induces a higher I(hERG1) density in tumors, an effect that apparently regulates neurite outgrowth in neuroblastoma cells and apoptosis in leukemia cells.     

The diversity and complexity of the cyanobacterial thioredoxin systems

Cyanobacteria perform oxygenic photosynthesis, which makes them unique among the prokaryotes, and this feature together with their abundance and worldwide distribution renders them a central ecological role. Cyanobacteria and chloroplasts of plants and algae are believed to share a common ancestor and the modern chloroplast would thus be the remnant of an endosymbiosis between a eukaryotic cell and an ancestral oxygenic photosynthetic prokaryote. Chloroplast metabolic processes are coordinated with those of the other cellular compartments and are strictly controlled by means of regulatory systems that commonly involve redox reactions. Disulphide/dithiol exchange catalysed by thioredoxin is a fundamental example of such regulation and represents the molecular mechanism for light-dependent redox control of an ever-increasing number of chloroplast enzymatic activities. In contrast to chloroplast thioredoxins, the functions of the cyanobacterial thioredoxins have long remained elusive, despite their common origin. The sequenced genomes of several cyanobacterial species together with novel experimental approaches involving proteomics have provided new tools for re-examining the roles of the thioredoxin systems in these organisms. Thus, each cyanobacterial genome encodes between one and eight thioredoxins and all components necessary for the reduction of thioredoxins. Screening for thioredoxin target proteins in cyanobacteria indicates that assimilation and storage of nutrients, as well as some central metabolic pathways, are regulated by mechanisms involving disulphide/dithiol exchange, which could be catalysed by thioredoxins or related thiol-containing proteins.     

Characterization of 111In and 177Lu-labeled antibodies binding to CD44v6 using a novel automated radioimmunoassay

Targeted cancer therapies rely on bifunctional molecules, typically a protein that specifically recognizes tumor cells and a toxic component which is linked to the protein. Therefore, development of such therapies includes detailed characterizations of protein-cell interactions in order to find a good targeting agent. Knowledge of factors such as antibody-antigen specificity, as well as cellular uptake, retention and affinity of the antibody are necessary in order to be successful.In this paper, we have used a novel instrument, LigandTracer Yellow, to characterize the interactions of (111)In and (177)Lu-labeled monoclonal antibodies (MAbs) with CD44v6. Uptake studies with varying specific radioactivity of the chimeric MAb U36 and with an irrelevant antibody for the CD44v6 receptor verified the reliability of the method, as well as the specificity of the antibody-receptor binding. Uptake, retention, and affinity were very similar for the (111)In and (177)Lu-labeled conjugate, and were in line with earlier studies using manual methods. The fact that no adverse effects from labeling were seen, together with the high retention, could make these conjugates promising candidates for imaging and therapy of certain cancer types in the future. The novel LigandTracer technology reduced the workload and reagent spending while providing data with superior time resolution. The obtained results were in agreement with previously reported findings. In addition the real-time detection and higher time resolution made more detailed studies of the interactions possible.     

One drug for two targets: Biological evaluation of antiretroviral agents endowed with antiproliferative activity

AIDS-related cancer diseases are malignancies with low incidence on healthy people that affect mostly subjects already immunocompromised. The connection between HIV/AIDS and these cancers has not been established yet, but a weakened immune system is certainly the main cause. We envisaged the possibility to screen a small library of compounds synthesized in our laboratory against opportunistic tumors mainly due to HIV infection like Burkitt’s Lymphoma. From cellular assays and gene expression analysis we identified two promising compounds. These derivatives have the dual action required inhibiting HIV replication in human TZM-bl cells infected with HIV-1 NL4.3 and showing cytotoxic activity on human colon HT-29 and breast adenocarcinoma MCF-7 cells. In addition, preclinical in vitro adsorption, distribution, metabolism, and excretion studies highlighted a satisfactory pharmacokinetic profile.     

The epitope recognized by pan-HLA class I-reactive monoclonal antibody W6/32 and its relationship to unusual stability of the HLA-B27/β2-microglobulin complex

A broadly used pan-HLA class I-reactive monoclonal antibody W6/32 is believed to recognize a conformational epitope dependent on association between heavy chains and beta2-microglobulin (beta2m). However, in the present study we report that W6/32 does recognize at least some free HLA class I heavy chains under the partially denaturating conditions of nonreducing Western blotting, namely nearly all HLA-B allelic products. Furthermore, we confirm and largely extend our previous observation that complexes of beta2m with heavy chains of a few HLA class I allelic forms (most notably HLA-B27) exhibit unusual resistance to dissociation by SDS, which is reminiscent of MHC class II molecules. In addition, our data indicate the existence of covalent (disulfide-linked) heterodimers of certain HLA class I heavy chains (namely Cw1 and Cw4) and beta2m.