Investigation of the physiological response of cold-adapted microorganisms to extreme environmental stress factors.

Exploring the limits of life is one of the objectives for better understanding how organisms have arisen on Earth, how they tolerate extreme conditions and how they might survive on other planets or moons. These investigations could help with understanding which Earth microorganisms could survive on other celestial bodies, such as the icy Moons: Europa (Jupiter) and Enceladus (Saturn). Furthermore, it might help with indicating how life could have developed on Earth or on the icy Moons of the Solar system. This project focuses on the insights from prokaryotic, eukaryotic and archaea organisms which can tolerate the simulated subsurface ocean environment of Europa and Enceladus. The moons have been speculated to have subsurface oceans which are heated by tidal movements or hydrothermal vents. These combined factors could create an environment suitable for life. Furthermore, the mechanism of radiation, desiccation and temperature survival could help us understand whether the organisms could survive a hitchhike on spacecraft surfaces travelling to the moons. During space exploration it is essential to avoid the contamination of planets and moons of astrobiological interest by microorganisms from Earth. [...

Lack of Cell Cycle Inhibitor p21 and Low CD4⁺ T Cell Suppression in Newborns After Exposure to IFN-β

Contains fulltext : 233564.pdf (Publisher’s version ) (Open Access

Bacterial lysis through interference with peptidoglycan synthesis increases biofilm formation by nontypeable haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen that mainly causes otitis media in children and community-acquired pneumonia or exacerbations of chronic obstructive pulmonary disease in adults. A large variety of studies suggest that biofilm formation by NTHi may be an important step in the pathogenesis of this bacterium. However, the underlying mechanisms involved in this process are poorly elucidated. In this study, we used a transposon mutant library to identify bacterial genes involved in biofilm formation. The growth and biofilm formation of 4,172 transposon mutants were determined, and the involvement of the identified genes in biofilm formation was validated in in vitro experiments. Here, we present experimental data showing that increased bacterial lysis, through interference with peptidoglycan synthesis, results in elevated levels of extracellular DNA, which increased biofilm formation. Interestingly, similar results were obtained with subinhibitory concentrations of β-lactam antibiotics, known to interfere with peptidoglycan synthesis, but such an effect does not appear with other classes of antibiotics. These results indicate that treatment with β-lactam antibiotics, especially for β-lactam-resistant NTHi isolates, might increase resistance to antibiotics by increasing biofilm formation

Impact of Experimental Human Pneumococcal Carriage on Nasopharyngeal Bacterial Densities in Healthy Adults

Colonization of the nasopharynx by Streptococcus pneumoniae is a necessary precursor to pneumococcal diseases that result in morbidity and mortality worldwide. The nasopharynx is also host to other bacterial species, including the common pathogens Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis. To better understand how these bacteria change in relation to pneumococcal colonization, we used species-specific quantitative PCR to examine bacterial densities in 52 subjects 7 days before, and 2, 7, and 14 days after controlled inoculation of healthy human adults with S. pneumoniae serotype 6B. Overall, 33 (63%) of subjects carried S. pneumoniae post-inoculation. The baseline presence and density of S. aureus, H. influenzae, and M. catarrhalis were not statistically associated with likelihood of successful pneumococcal colonization at this study’s sample size, although a lower rate of pneumococcal colonization in the presence of S. aureus (7/14) was seen compared to that in the presence of H. influenzae (12/16). Among subjects colonized with pneumococci, the number also carrying either H. influenzae or S. aureus fell during the study and at 14 days post-inoculation, the proportion carrying S. aureus was significantly lower among those who were colonized with S. pneumoniae (p = 0.008) compared to non-colonized subjects. These data on bacterial associations are the first to be reported surrounding experimental human pneumococcal colonization and show that co-colonizing effects are likely subtle rather than absolute

IgM Augments Complement Bactericidal Activity with Serum from a Patient with a Novel CD79a Mutation

Antibody replacement therapy for patients with antibody deficiencies contains only IgG. As a result, concurrent IgM and IgA deficiency present in a large proportion of antibody deficient patients persists. Especially patients with IgM deficiency remain at risk for recurrent infections of the gastrointestinal and respiratory tract. The lack of IgM in the current IgG replacement therapy is likely to contribute to the persistence of these mucosal infections because this antibody class is especially important for complement activation on the mucosal surface. We evaluated whether supplementation with IgM increased serum bactericidal capacity in vitro. Serum was collected from a patient with agammaglobulinemia and supplemented with purified serum IgM to normal levels. Antibody and complement deposition on the bacterial surface was determined by multi-color flow cytometry. Bacterial survival in serum was determined by colony-forming unit counts. We present a patient previously diagnosed with agammaglobulinemia due to CD79A (Igα) deficiency revealing a novel pathogenic insertion variant in the CD79a gene (NM_001783.3:c.353_354insT). Despite IgG replacement therapy and antibiotic prophylaxis, this patient developed a Campylobacter jejuni spondylodiscitis of lumbar vertebrae L4–L5. We found that serum IgM significantly contributes to complement activation on the bacterial surface of C. jejuni. Furthermore, supplementation of serum IgM augmented serum bactericidal activity significantly. In conclusion, supplementation of intravenous IgG replacement therapy with IgM may potentially offer greater protection against bacterial infections, also in the context of increasing antibiotic resistance

Lipidation of Pneumococcal Antigens Leads to Improved Immunogenicity and Protection

Streptococcus pneumoniaeinfections lead to high morbidity and mortality rates worldwide.Pneumococcal polysaccharide conjugate vaccines significantly reduce the burden of disease but havea limited range of protection, which encourages the development of a broadly protective protein-basedalternative. We and others have shown that immunization with pneumococcal lipoproteins that lackthe lipid anchor protects against colonization. Since immunity againstS. pneumoniaeis mediatedthrough Toll-like receptor 2 signaling induced by lipidated proteins, we investigated the effects ofa lipid modification on the induced immune responses in either intranasally or subcutaneouslyvaccinated mice. Here, we demonstrate that lipidation of recombinant lipoproteins DacB and PnrAstrongly improves their immunogenicity. Mice immunized with lipidated proteins showed enhancedantibody concentrations and different induction kinetics. The induced humoral immune responsewas modulated by lipidation, indicated by increased IgG2/IgG1 subclass ratios related to Th1-typeimmunity. In a mouse model of colonization, immunization with lipidated antigens led to a moderatebut consistent reduction of pneumococcal colonization as compared to the non-lipidated proteins,indicating that protein lipidation can improve the protective capacity of the coupled antigen. Thus,protein lipidation represents a promising approach for the development of a serotype-independentpneumococcal vaccine

The vaccine potential of Bordetella pertussis biofilm-derived membrane proteins

Pertussis is an infectious respiratory disease of humans caused by the gram-negative pathogen Bordetella pertussis. The use of acellular pertussis vaccines (aPs) which induce immunity of relative short duration and the emergence of vaccine-adapted strains are thought to have contributed to the recent resurgence of pertussis in industrialized countries despite high vaccination coverage. Current pertussis vaccines consist of antigens derived from planktonic bacterial cultures. However, recent studies have shown that biofilm formation represents an important aspect of B. pertussis infection, and antigens expressed during this stage may therefore be potential targets for vaccination. Here we provide evidence that vaccination of mice with B. pertussis biofilm-derived membrane proteins protects against infection. Subsequent proteomic analysis of the protein content of biofilm and planktonic cultures yielded 11 proteins which were ≥ three-fold more abundant in biofilms, of which Bordetella intermediate protein A (BipA) was the most abundant, surface-exposed protein. As proof of concept, mice were vaccinated with recombinantly produced BipA. Immunization significantly reduced colonization of the lungs and antibodies to BipA were found to efficiently opsonize bacteria. Finally, we confirmed that bipA is expressed during respiratory tract infection of mice, and that anti-BipA antibodies are present in the serum of convalescent whooping cough patients. Together, these data suggest that biofilm proteins and in particular BipA may be of interest for inclusion into future pertussis vaccines.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Fermentaciones Industriale

The vaccine potential of Bordetella pertussis biofilm-derived membrane proteins

Pertussis is an infectious respiratory disease of humans caused by the gram-negative pathogen Bordetella pertussis. The use of acellular pertussis vaccines (aPs) which induce immunity of relative short duration and the emergence of vaccine-adapted strains are thought to have contributed to the recent resurgence of pertussis in industrialized countries despite high vaccination coverage. Current pertussis vaccines consist of antigens derived from planktonic bacterial cultures. However, recent studies have shown that biofilm formation represents an important aspect of B. pertussis infection, and antigens expressed during this stage may therefore be potential targets for vaccination. Here we provide evidence that vaccination of mice with B. pertussis biofilm-derived membrane proteins protects against infection. Subsequent proteomic analysis of the protein content of biofilm and planktonic cultures yielded 11 proteins which were ≥ three-fold more abundant in biofilms, of which Bordetella intermediate protein A (BipA) was the most abundant, surface-exposed protein. As proof of concept, mice were vaccinated with recombinantly produced BipA. Immunization significantly reduced colonization of the lungs and antibodies to BipA were found to efficiently opsonize bacteria. Finally, we confirmed that bipA is expressed during respiratory tract infection of mice, and that anti-BipA antibodies are present in the serum of convalescent whooping cough patients. Together, these data suggest that biofilm proteins and in particular BipA may be of interest for inclusion into future pertussis vaccines.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Fermentaciones Industriale

Subanalytic sets and feedback control

AbstractThe theory of subanalytic sets is used to prove: If a real analytic control system is completely controllable, then for every point p in the state space there exists a piecewise analytic feedback control that steers every state into p

β2→ 1-fructans modulate the immune system in vivo by direct interaction with the mucosa in a microbiota-independent fashion

It has been shown in vitro that only specific dietary fibers contribute to immunity, but studies in vivo are not conclusive. Here, we investigated degree of polymerization (DP) dependent effects of beta2-->1-fructans on immunity via microbiota-dependent and -independent effects. To this end, conventional or germ-free mice received short- or long-chain beta2-->1-fructan for 5 days. Immune cell populations in the spleen, mesenteric lymph nodes (MLNs), and Peyer's patches (PPs) were analyzed with flow cytometry, genome-wide gene expression in the ileum was measured with microarray, and gut microbiota composition was analyzed with 16S rRNA sequencing of fecal samples. We found that beta2-->1-fructans modulated immunity by both microbiota and microbiota-independent effects. Moreover, effects were dependent on the chain-length of the beta2-->1-fructans type polymer. Both short- and long-chain beta2-->1-fructans enhanced T-helper 1 cells in PPs, whereas only short-chain beta2-->1-fructans increased regulatory T cells and CD11b-CD103- dendritic cells (DCs) in the MLN. A common feature after short- and long-chain beta2-->1-fructan treatment was enhanced 2-alpha-l-fucosyltransferase 2 expression and other IL-22-dependent genes in the ileum of conventional mice. These effects were not associated with shifts in gut microbiota composition, or altered production of short-chain fatty acids. Both short- and long-chain beta2-->1-fructans also induced immune effects in germ-free animals, demonstrating direct effect independent from the gut microbiota. Also, these effects were dependent on the chain-length of the beta2-->1-fructans. Short-chain beta2-->1-fructan induced lower CD80 expression by CD11b-CD103- DCs in PPs, whereas long-chain beta2-->1-fructan specifically modulated B cell responses in germ-free mice. In conclusion, support of immunity is determined by the chemical structure of beta2-->1-fructans and is partially microbiota independent