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Journal articleMatthews S, McKenna S, Malito E, et al., 2020,
Structure, dynamics and immunogenicity of a catalytically inactive CXC Chemokine-degrading Protease SpyCEP from Streptococcus pyogenes
, Computational and Structural Biotechnology Journal, Vol: 18, Pages: 650-660, ISSN: 2001-0370Over 18 million disease cases and half a million deaths worldwide are estimated to be caused annually by Group A Streptococcus. A vaccine to prevent GAS disease is urgently needed. SpyCEP (Streptococcus pyogenes Cell-Envelope Proteinase) is a surface-exposed serine protease that inactivates chemokines, impairing neutrophil recruitment and bacterial clearance, and has shown promising immunogenicity in preclinical models. Although SpyCEP structure has been partially characterized, a more complete and higher resolution understanding of its antigenic features would be desirable prior to large scale manufacturing. To address these gaps and facilitate development of this globally important vaccine, we performed immunogenicity studies with a safety-engineered SpyCEP mutant, and comprehensively characterized its structure by combining X-ray crystallography, NMR spectroscopy and molecular dynamics simulations. We found that the catalytically-inactive SpyCEP antigen conferred protection similar to wild-type SpyCEP in a mouse infection model. Further, a new higher-resolution crystal structure of the inactive SpyCEP mutant provided new insights into this large chemokine protease comprising nine domains derived from two non-covalently linked fragments. NMR spectroscopy and molecular simulation analyses revealed conformational flexibility that is likely important for optimal substrate recognition and overall function. These combined immunogenicity and structural data demonstrate that the full-length SpyCEP inactive mutant is a strong candidate human vaccine antigen. These findings show how a multi-disciplinary study was used to overcome obstacles in the development of a GAS vaccine, an approach applicable to other future vaccine programs. Moreover, the information provided may also facilitate the structure-based discovery of small-molecule therapeutics targeting SpyCEP protease inhibition.
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Journal articleMichael DR, Jack AA, Masetti G, et al., 2020,
A randomised controlled study shows supplementation of overweight and obese adults with lactobacilli and bifidobacteria reduces bodyweight and improves well-being
, Scientific Reports, Vol: 10<jats:title>Abstract</jats:title><jats:p>In an exploratory, block-randomised, parallel, double-blind, single-centre, placebo-controlled superiority study (ISRCTN12562026, funded by Cultech Ltd), 220 Bulgarian participants (30 to 65 years old) with BMI 25–34.9 kg/m<jats:sup>2</jats:sup> received Lab4P probiotic (50 billion/day) or a matched placebo for 6 months. Participants maintained their normal diet and lifestyle. Primary outcomes were changes in body weight, BMI, waist circumference (WC), waist-to-height ratio (WtHR), blood pressure and plasma lipids. Secondary outcomes were changes in plasma C-reactive protein (CRP), the diversity of the faecal microbiota, quality of life (QoL) assessments and the incidence of upper respiratory tract infection (URTI). Significant between group decreases in body weight (1.3 kg, <jats:italic>p</jats:italic> < 0.0001), BMI (0.045 kg/m<jats:sup>2</jats:sup>, <jats:italic>p</jats:italic> < 0.0001), WC (0.94 cm, <jats:italic>p</jats:italic> < 0.0001) and WtHR (0.006, <jats:italic>p</jats:italic> < 0.0001) were in favour of the probiotic. Stratification identified greater body weight reductions in overweight subjects (1.88%, <jats:italic>p</jats:italic> < 0.0001) and in females (1.62%, <jats:italic>p</jats:italic> = 0.0005). Greatest weight losses were among probiotic hypercholesterolaemic participants (−2.5%, <jats:italic>p</jats:italic> < 0.0001) alongside a significant between group reduction in small dense LDL-cholesterol (0.2 mmol/L, <jats:italic>p</jats:italic> = 0.0241). Improvements in QoL and the incidence rate ratio of URTI (0.60, <jats:italic>p</jats:italic> <&thins
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ReportOtter J, Brophy K, Palmer J, et al., 2020,
Smart surfaces to tackle infection and antimicrobial resistance
, Briefing Paper -
Journal articleOvadia C, Perdones-Montero A, Fan HM, et al., 2020,
Ursodeoxycholic acid enriches intestinal bile salt hydrolase-expressing Bacteroidetes in cholestatic pregnancy
, Scientific Reports, Vol: 10<jats:title>Abstract</jats:title><jats:p>Ursodeoxycholic acid (UDCA) treatment can reduce itch and lower endogenous serum bile acids in intrahepatic cholestasis of pregnancy (ICP). We sought to determine how it could influence the gut environment in ICP to alter enterohepatic signalling. The gut microbiota and bile acid content were determined in faeces from 35 pregnant women (14 with uncomplicated pregnancies and 21 with ICP, 17 receiving UDCA). Faecal bile salt hydrolase activity was measured using a precipitation assay. Serum fibroblast growth factor 19 (FGF19) and 7α-hydroxy-4-cholesten-3-one (C4) concentrations were measured following a standardised diet for 21 hours. Women with a high ratio of<jats:italic>Bacteroidetes</jats:italic>to<jats:italic>Firmicutes</jats:italic>were more likely to be treated with UDCA (Fisher’s exact test p = 0.0178) than those with a lower ratio. Bile salt hydrolase activity was reduced in women with low<jats:italic>Bacteroidetes</jats:italic>:<jats:italic>Firmicutes</jats:italic>. Women taking UDCA had higher faecal lithocholic acid (p < 0.0001), with more unconjugated bile acids than women with untreated ICP or uncomplicated pregnancy. UDCA-treatment increased serum FGF19, and reduced C4 (reflecting lower bile acid synthesis). During ICP, UDCA treatment can be associated with enrichment of the gut microbiota with<jats:italic>Bacteroidetes</jats:italic>. These demonstrate high bile salt hydrolase activity, which deconjugates bile acids enabling secondary modification to FXR agonists, enhancing enterohepatic feedback via FGF19.</jats:p>
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Journal articleAllsopp LP, Bernal P, Nolan LM, et al., 2020,
Causalities of war: the connection between type VI secretion system and microbiota
, Cellular Microbiology, Vol: 22, Pages: 1-9, ISSN: 1462-5814Microbiota niches have space and/or nutrient restrictions, which has led to the coevolution of cooperation, specialisation, and competition within the population. Different animal and environmental niches contain defined resident microbiota that tend to be stable over time and offer protection against undesired intruders. Yet fluxes can occur, which alter the composition of a bacterial population. In humans, the microbiota are now considered a key contributor to maintenance of health and homeostasis, and its alteration leads to dysbiosis. The bacterial type VI secretion system (T6SS) transports proteins into the environment, directly into host cells or can function as an antibacterial weapon by killing surrounding competitors. Upon contact with neighbouring cells, the T6SS fires, delivering a payload of effector proteins. In the absence of an immunity protein, this results in growth inhibition or death of prey leading to a competitive advantage for the attacker. It is becoming apparent that the T6SS has a role in modulating and shaping the microbiota at multiple levels, which is the focus of this review. Discussed here is the T6SS, its role in competition, key examples of its effect upon the microbiota, and future avenues of research.
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Journal articleSumrall ET, Schefer CRE, Rismondo J, et al., 2020,
Galactosylated wall-teichoic acid, but not lipoteichoic acid, retains InlB on the surface of serovar 4b Listeria monocytogenes
, Molecular Microbiology, Vol: 113, Pages: 638-649, ISSN: 0950-382XListeria monocytogenes is a Gram-positive, intracellular pathogen harboring the surface-associated virulence factor InlB, which enables entry into certain host cells. Structurally diverse wall-teichoic acids (WTAs), which can also be differentially glycosylated, determine the antigenic basis of the various Listeria serovars. WTAs have many physiological functions; they can serve as receptors for bacteriophages, and provide a substrate for binding of surface proteins such as InlB. In contrast, the membrane-anchored lipoteichoic acids (LTAs) do not show significant variation and do not contribute to serovar determination. It was previously demonstrated that surface-associated InlB non-covalently adheres to both WTA and LTA, mediating its retention on the cell wall. Here, we demonstrate that in a highly virulent serovar 4b strain, two genes gtlB and gttB are responsible for galactosylation of LTA and WTA, respectively. We evaluated the InlB surface retention in mutants lacking each of these two genes, and found that only galactosylated WTA is required for InlB surface presentation and function, cellular invasiveness, and phage adsorption, while galactosylated LTA plays no role thereof. Our findings demonstrate that a simple pathogen-defining serovar antigen, that mediates bacteriophage susceptibility, is necessary and sufficient to sustain the function of an important virulence factor.
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Journal articleSubbarao S, Sanchez-Garrido J, Krishnan N, et al., 2020,
Genetic and pharmacological inhibition of inflammasomes reduces the survival of Mycobacterium tuberculosis strains in macrophages
, Scientific Reports, Vol: 10, ISSN: 2045-2322Mycobacterium tuberculosis infection causes high rates of morbidity and mortality. Host-directed therapy may enhance the immune response, reduce tissue damage and shorten treatment duration. The inflammasome is integral to innate immune responses but over-activation has been described in tuberculosis (TB) pathology and TB-immune reconstitution syndrome. Here we explore how clinical isolates differentially activate the inflammasome and how inflammasome inhibition can lead to enhanced bacterial clearance. Wild-type, Nlrp3−/−/Aim2−/−, Casp1/11−/− and Asc−/− murine bone-marrow derived macrophages (BMDMs) were infected with laboratory strain M. tuberculosis H37Rv or clinical isolates from various lineages. Inflammasome activation and bacterial numbers were measured, and pharmacological inhibition of NLRP3 was achieved using MCC950. Clinical isolates of M. tuberculosis differed in their ability to activate inflammasomes. Beijing isolates had contrasting effects on IL-1β and caspase-1 activation, but all clinical isolates induced lower IL-1β release than H37Rv. Our studies suggest the involvement of NLRP3, AIM2 and an additional unknown sensor in IL-1β maturation. Pharmacological blockade of NLRP3 with MCC950 reduced bacterial survival, and combined treatment with the antimycobacterial drug rifampicin enhanced the effect. Modulating the inflammasome is an attractive adjunct to current anti-mycobacterial therapy that warrants further investigation.
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Journal articleWettstadt S, Filloux A, 2020,
Manipulating the type VI secretion system spike to shuttle passenger proteins
, PLoS One, Vol: 15, Pages: 1-20, ISSN: 1932-6203The type VI secretion system (T6SS) is a contractile injection apparatus that translocates a spike loaded with various effectors directly into eukaryotic or prokaryotic target cells. Pseudomonas aeruginosa can load either one of its three T6SSs with a variety of toxic bullets using different but specific modes. The T6SS spike, which punctures the bacterial cell envelope allowing effector transport, consists of a torch-like VgrG trimer on which sits a PAAR protein sharpening the VgrG tip. VgrG itself sits on the Hcp tube and all elements, packed into a T6SS sheath, are propelled out of the cell and into target cells. On occasion, effectors are covalent extensions of VgrG, PAAR or Hcp proteins, which are then coined “evolved” components as opposed to canonical. Here, we show how various passenger domains could be fused to the C terminus of a canonical VgrG, VgrG1a from P. aeruginosa, and be sent into the bacterial culture supernatant. There is no restriction on the passenger type, although the efficacy may vary greatly, since we used either an unrelated T6SS protein, β-lactamase, a covalent extension of an “evolved” VgrG, VgrG2b, or a Hcp-dependent T6SS toxin, Tse2. Our data further highlights an exceptional modularity/flexibility for loading the T6SS nano-weapon. Refining the parameters to optimize delivery of passenger proteins of interest would have attractive medical and industrial applications. This may for example involve engineering the T6SS as a delivery system to shuttle toxins into either bacterial pathogens or tumour cells which would be an original approach in the fight against antimicrobial resistant bacteria or cancer.
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Journal articleZhao Y, van Woudenbergh E, Zhu J, et al., 2020,
The Orphan Immune Receptor LILRB3 Modulates Fc Receptor-Mediated Functions of Neutrophils
, JOURNAL OF IMMUNOLOGY, Vol: 204, Pages: 954-966, ISSN: 0022-1767- Author Web Link
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- Citations: 15
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Journal articleBottai D, Frigui W, Sayes F, et al., 2020,
TbD1 deletion as a driver of the evolutionary success of modern epidemic <i>Mycobacterium tuberculosis</i> lineages
, NATURE COMMUNICATIONS, Vol: 11, ISSN: 2041-1723- Author Web Link
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- Citations: 34
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