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Journal of Biomedical Science Jul 2023Streptococcus pyogenes (group A streptococci; GAS) is the main causative pathogen of monomicrobial necrotizing soft tissue infections (NSTIs). To resist...
BACKGROUND
Streptococcus pyogenes (group A streptococci; GAS) is the main causative pathogen of monomicrobial necrotizing soft tissue infections (NSTIs). To resist immuno-clearance, GAS adapt their genetic information and/or phenotype to the surrounding environment. Hyper-virulent streptococcal pyrogenic exotoxin B (SpeB) negative variants caused by covRS mutations are enriched during infection. A key driving force for this process is the bacterial Sda1 DNase.
METHODS
Bacterial infiltration, immune cell influx, tissue necrosis and inflammation in patient´s biopsies were determined using immunohistochemistry. SpeB secretion and activity by GAS post infections or challenges with reactive agents were determined via Western blot or casein agar and proteolytic activity assays, respectively. Proteome of GAS single colonies and neutrophil secretome were profiled, using mass spectrometry.
RESULTS
Here, we identify another strategy resulting in SpeB-negative variants, namely reversible abrogation of SpeB secretion triggered by neutrophil effector molecules. Analysis of NSTI patient tissue biopsies revealed that tissue inflammation, neutrophil influx, and degranulation positively correlate with increasing frequency of SpeB-negative GAS clones. Using single colony proteomics, we show that GAS isolated directly from tissue express but do not secrete SpeB. Once the tissue pressure is lifted, GAS regain SpeB secreting function. Neutrophils were identified as the main immune cells responsible for the observed phenotype. Subsequent analyses identified hydrogen peroxide and hypochlorous acid as reactive agents driving this phenotypic GAS adaptation to the tissue environment. SpeB-negative GAS show improved survival within neutrophils and induce increased degranulation.
CONCLUSIONS
Our findings provide new information about GAS fitness and heterogeneity in the soft tissue milieu and provide new potential targets for therapeutic intervention in NSTIs.
Topics: Streptococcus pyogenes; Neutrophils; Bacterial Proteins; Exotoxins
PubMed: 37430325
DOI: 10.1186/s12929-023-00947-x -
Advances in Clinical Chemistry 2024The outer membrane of gram-negative bacteria is primarily composed of lipopolysaccharide (LPS). In addition to protection, LPS defines the distinct serogroups used to...
The outer membrane of gram-negative bacteria is primarily composed of lipopolysaccharide (LPS). In addition to protection, LPS defines the distinct serogroups used to identify bacteria specifically. Furthermore, LPS also act as highly potent stimulators of innate immune cells, a phenomenon essential to understanding pathogen invasion in the body. The complex multi-step process of LPS binding to cells involves several binding partners, including LPS binding protein (LBP), CD14 in both membrane-bound and soluble forms, membrane protein MD-2, and toll-like receptor 4 (TLR4). Once these pathways are activated, pro-inflammatory cytokines are eventually expressed. These binding events are also affected by the presence of monomeric or aggregated LPS. Traditional techniques to detect LPS include the rabbit pyrogen test, the monocyte activation test and Limulus-based tests. Modern approaches are based on protein, antibodies or aptamer binding. Recently, novel techniques including electrochemical methods, HPLC, quartz crystal microbalance (QCM), and molecular imprinting have been developed. These approaches often use nanomaterials such as gold nanoparticles, quantum dots, nanotubes, and magnetic nanoparticles. This chapter reviews current developments in endotoxin detection with a focus on modern novel techniques that use various sensing components, ranging from natural biomolecules to synthetic materials. Highly integrated and miniaturized commercial endotoxin detection devices offer a variety of options as the scientific and technologic revolution proceeds.
Topics: Animals; Humans; Rabbits; Endotoxins; Lipopolysaccharides; Gold; Metal Nanoparticles; Cytokines
PubMed: 38280803
DOI: 10.1016/bs.acc.2023.11.001 -
Carbohydrate Polymers Aug 2023Bacterial cellulose (BC) is a chemically pure, non-toxic, and non-pyrogenic natural polymer with high mechanical strength and a complex fibrillar porous structure. Due... (Review)
Review
Bacterial cellulose (BC) is a chemically pure, non-toxic, and non-pyrogenic natural polymer with high mechanical strength and a complex fibrillar porous structure. Due to these unique biological and physical properties, BC has been amply used in the food industry and, to a somewhat lesser extent, in medicine and cosmetology. To expand its application the BC structure can be modified. This review presented some recent developments in electrically conductive BC-based composites. The as-synthesized BC is an excellent dielectric. Conductive polymers, graphene oxide, nanoparticles and other materials are used to provide it with conductive properties. Conductive bacterial cellulose (CBC) is currently investigated in numerous areas including electrically conductive scaffolds for tissue regeneration, implantable and wearable biointerfaces, flexible batteries, sensors, EMI shielding composites. However, there are several issues to be addressed before CBC composites can enter the market, namely, composite mechanical strength reduction, porosity decrease, change in chemical characteristics. Some of them can be addressed both at the stage of synthesis, biologically, or by adding (nano)materials with the required properties to the BC structure. We propose several solutions to meet the challenges and suggest some promising BC applications.
Topics: Cellulose; Polymers; Prostheses and Implants; Electronics; Nanoparticles
PubMed: 37182950
DOI: 10.1016/j.carbpol.2023.120850 -
European Journal of Medicinal Chemistry May 2024Nucleotide-binding oligomerization domain 2 (NOD2) is a receptor of the innate immune system that is capable of perceiving bacterial and viral infections. Muramyl... (Review)
Review
Nucleotide-binding oligomerization domain 2 (NOD2) is a receptor of the innate immune system that is capable of perceiving bacterial and viral infections. Muramyl dipeptide (MDP, N-acetyl muramyl L-alanyl-d-isoglutamine), identified as the minimal immunologically active component of bacterial cell wall peptidoglycan (PGN) is recognized by NOD2. In terms of biological activities, MDP demonstrated vaccine adjuvant activity and stimulated non-specific protection against bacterial, viral, and parasitic infections and cancer. However, MDP has certain drawbacks including pyrogenicity, rapid elimination, and lack of oral bioavailability. Several detailed structure-activity relationship (SAR) studies around MDP scaffolds are being carried out to identify better NOD2 ligands. The present review elaborates a comprehensive SAR summarizing structural aspects of MDP derivatives in relation to NOD2 agonistic activity.
Topics: Nod2 Signaling Adaptor Protein; Acetylmuramyl-Alanyl-Isoglutamine; Structure-Activity Relationship; Humans; Animals; Molecular Structure
PubMed: 38691886
DOI: 10.1016/j.ejmech.2024.116439 -
Environmental Science & Technology Sep 2023Quinones and products of their redox reactions (hydroquinones and semiquinones) have been suggested as important players in the reductive dehalogenation of...
Quinones and products of their redox reactions (hydroquinones and semiquinones) have been suggested as important players in the reductive dehalogenation of organohalogens mediated by natural and pyrogenic organic matter, although based on limited direct evidence. This study focused on the reductive dehalogenation of a model organohalogen (triclosan) by 1,4-benzohydroquinone (HQ). In the presence of HQ only, degradation of triclosan does not occur within the experimental period (up to 288 h); however, it takes place in the presence of HQ and FeCl under anoxic conditions at pH 5 and 7 (above the p of SQ = 4.1) only to be halted in the presence of dissolved oxygen. Kinetic simulation and thermodynamic calculations indicated that benzosemiquinone (SQ) is responsible for the reductive degradation of triclosan, with the fitted rate constant for the reaction between SQ and triclosan being 317 M h. The critical role of semiquinones in reductive dehalogenation can be relevant to a wide range of quinones in natural and engineering systems based on the reported oxidation-reduction potentials of quinones/semiquinones and semiquinones/hydroquinones and supported by experiments with additional model hydroquinones.
Topics: Hydroquinones; Triclosan; Computer Simulation; Ketones; Quinones
PubMed: 37668505
DOI: 10.1021/acs.est.3c03981 -
Microbiology and Molecular Biology... Mar 2024SUMMARYGroup A (GAS), also known as , is a clinically well-adapted human pathogen that harbors rich virulence determinants contributing to a broad spectrum of diseases.... (Review)
Review
SUMMARYGroup A (GAS), also known as , is a clinically well-adapted human pathogen that harbors rich virulence determinants contributing to a broad spectrum of diseases. GAS is capable of invading epithelial, endothelial, and professional phagocytic cells while evading host innate immune responses, including phagocytosis, selective autophagy, light chain 3-associated phagocytosis, and inflammation. However, without a more complete understanding of the different ways invasive GAS infections develop, it is difficult to appreciate how GAS survives and multiplies in host cells that have interactive immune networks. This review article attempts to provide an overview of the behaviors and mechanisms that allow pathogenic GAS to invade cells, along with the strategies that host cells practice to constrain GAS infection. We highlight the counteractions taken by GAS to apply virulence factors such as streptolysin O, nicotinamide-adenine dinucleotidase, and streptococcal pyrogenic exotoxin B as a hindrance to host innate immune responses.
Topics: Humans; Streptococcus pyogenes; Streptococcal Infections; Immunity, Innate; Virulence Factors; Phagocytosis
PubMed: 38451081
DOI: 10.1128/mmbr.00052-22 -
Comprehensive Reviews in Food Science... Nov 2023The marine finfish and crustaceans contribute immensely to human nutrition. Harvesting marine food-fish to meet the global demand has become a challenge due to reduction... (Review)
Review
The marine finfish and crustaceans contribute immensely to human nutrition. Harvesting marine food-fish to meet the global demand has become a challenge due to reduction of the fishery areas and food safety hazards associated with increased pre-harvest and post-harvest contaminations. The causes of low fish availability and contaminations were reviewed following the published literature from 2000 to 2023. The marine fish yields are stressed due to spread of contaminants triggered by rising sea temperatures, transport of microorganisms by marine vessels across the oceans, anthropogenic activities leading to increase in the toxic microorganisms, and the entry of toxic chemicals and antibiotic residues into the seawater through rivers or directly. Processing adds pyrogenic chemicals to foods. The hazardous materials may accumulate in the food-fish, beyond tolerance limits permitted for human foods. While the research and control measures focus on minimizing the hazards due to pathogenic microorganisms and chemicals in market fish, there is less discussion on the unhealthy changes occurring in the oceans affecting the quantity and quality of food-fish, and the origins of microbial and chemical contaminations. This review examines the factors affecting availability of wild food-fish and increased contaminations. It aims to bridge the knowledge gaps between the spread of hazardous agents in the marine environment, and their effects on the food-fish. Meeting the future human food security and safety through marine fish and fish products may need marine cage farming, introduction of genetically modified high yielding food-fish, and cultured contaminant free finless fish muscles as options.
Topics: Animals; Humans; Food Safety; Anti-Bacterial Agents; Fishes; Muscles
PubMed: 37732477
DOI: 10.1111/1541-4337.13239 -
The Journal of Clinical Investigation Oct 2023BACKGROUNDThe biology of Plasmodium vivax is markedly different from that of P. falciparum; how this shapes the immune response to infection remains unclear. To address...
BACKGROUNDThe biology of Plasmodium vivax is markedly different from that of P. falciparum; how this shapes the immune response to infection remains unclear. To address this shortfall, we inoculated human volunteers with a clonal field isolate of P. vivax and tracked their response through infection and convalescence.METHODSParticipants were injected intravenously with blood-stage parasites and infection dynamics were tracked in real time by quantitative PCR. Whole blood samples were used for high dimensional protein analysis, RNA sequencing, and cytometry by time of flight, and temporal changes in the host response to P. vivax were quantified by linear regression. Comparative analyses with P. falciparum were then undertaken using analogous data sets derived from prior controlled human malaria infection studies.RESULTSP. vivax rapidly induced a type I inflammatory response that coincided with hallmark features of clinical malaria. This acute-phase response shared remarkable overlap with that induced by P. falciparum but was significantly elevated (at RNA and protein levels), leading to an increased incidence of pyrexia. In contrast, T cell activation and terminal differentiation were significantly increased in volunteers infected with P. falciparum. Heterogeneous CD4+ T cells were found to dominate this adaptive response and phenotypic analysis revealed unexpected features normally associated with cytotoxicity and autoinflammatory disease.CONCLUSIONP. vivax triggers increased systemic interferon signaling (cf P. falciparum), which likely explains its reduced pyrogenic threshold. In contrast, P. falciparum drives T cell activation far in excess of P. vivax, which may partially explain why falciparum malaria more frequently causes severe disease.TRIAL REGISTRATIONClinicalTrials.gov NCT03797989.FUNDINGThe European Union's Horizon 2020 Research and Innovation programme, the Wellcome Trust, and the Royal Society.
Topics: Humans; Plasmodium vivax; Plasmodium falciparum; Malaria, Vivax; Malaria, Falciparum; Malaria; Lymphocyte Activation
PubMed: 37616070
DOI: 10.1172/JCI152463 -
Scientific Reports Aug 2023Intrinsic or added immune activating molecules are key for most vaccines to provide desired immunity profiles but may increase systemic reactogenicity. Regulatory...
Intrinsic or added immune activating molecules are key for most vaccines to provide desired immunity profiles but may increase systemic reactogenicity. Regulatory agencies require rabbit pyrogen testing (RPT) for demonstration of vaccine reactogenicity. Recently, the monocyte activation test (MAT) gained popularity as in vitro alternative, yet this assay was primarily designed to test pyrogen-free products. The aim was to adjust the MAT to enable testing of pyrogen containing vaccines in an early stage of development where no reference batch is yet available. The MAT and RPT were compared for assessing unknown safety profiles of pertussis outer membrane vesicle (OMV) vaccine candidates to those of Bexsero as surrogate reference vaccine. Pertussis OMVs with wild-type LPS predominantly activated TLR2 and TLR4 and were more reactogenic than Bexsero. However, this reactogenicity profile for pertussis OMVs could be equalized or drastically reduced compared to Bexsero or a whole-cell pertussis vaccine, respectively by dose changing, modifying the LPS, intranasal administration, or a combination of these. Importantly, except for LPS modified products, reactogenicity profiles obtained with the RPT and MAT were comparable. Overall, we demonstrated that this pertussis OMV vaccine candidate has an acceptable safety profile. Furthermore, the MAT proved its applicability to assess reactogenicity levels of pyrogen containing vaccines at multiple stages of vaccine development and could eventually replace rabbit pyrogen testing.
Topics: Animals; Rabbits; Lipopolysaccharides; Whooping Cough; Pyrogens; Monocytes; Biological Assay
PubMed: 37542099
DOI: 10.1038/s41598-023-39908-7 -
Signal Transduction and Targeted Therapy Feb 2024Pyrogen, often as a contaminant, is a key indicator affecting the safety of almost all parenteral drugs (including biologicals, chemicals, traditional Chinese medicines...
Pyrogen, often as a contaminant, is a key indicator affecting the safety of almost all parenteral drugs (including biologicals, chemicals, traditional Chinese medicines and medical devices). It has become a goal to completely replace the in vivo rabbit pyrogen test by using the in vitro pyrogen test based on the promoted 'reduction, replacement and refinement' principle, which has been highly considered by regulatory agencies from different countries. We used NF-κB, a central signalling molecule mediating inflammatory responses, as a pyrogenic marker and the monocyte line THP-1 transfected with a luciferase reporter gene regulated by NF-κB as an in vitro model to detect pyrogens by measuring the intensity of a fluorescence signal. Here, we show that this test can quantitatively and sensitively detect endotoxin (lipopolysaccharide from different strains) and nonendotoxin (lipoteichoic acid, zymosan, peptidoglycan, lectin and glucan), has good stability in terms of NF-κB activity and cell phenotypes at 39 cell passages and can be applied to detect pyrogens in biologicals (group A & C meningococcal polysaccharide vaccine; basiliximab; rabies vaccine (Vero cells) for human use, freeze-dried; Japanese encephalitis vaccine (Vero cells), inactivated; insulin aspart injection; human albumin; recombinant human erythropoietin injection (CHO Cell)). The within-laboratory reproducibility of the test in three independent laboratories was 85%, 80% and 80% and the interlaboratory reproducibility among laboratories was 83.3%, 95.6% and 86.7%. The sensitivity (true positive rate) and specificity (true negative rate) of the test were 89.9% and 90.9%, respectively. In summary, the test provides a novel alternative for pyrogen detection.
Topics: Animals; Chlorocebus aethiops; Rabbits; Humans; Pyrogens; NF-kappa B; Vero Cells; Reproducibility of Results; Cell Line
PubMed: 38369543
DOI: 10.1038/s41392-024-01744-0