Comparison of listeriolysin O and phospholipases PlcA and PlcB activities, and initial intracellular growth capability among food and clinical strains of Listeria monocytogenes

The noncanonical inflammasome-induced pyroptosis and septic shock

Sepsis remains one of the most common and lethal conditions globally. Currently, no proposed target specific to sepsis improves survival in clinical trials. Thus, an in-depth understanding of the pathogenesis of sepsis is needed to propel the discovery of effective treatment. Recently attention to sepsis has intensified because of a growing recognition of a non-canonical inflammasome-triggered lytic mode of cell death termed pyroptosis upon sensing cytosolic lipopolysaccharide (LPS). Although the consequences of activation of the canonical and non-canonical inflammasome are similar, the non-canonical inflammasome formation requires caspase-4/5/11, which enzymatically cleave the pore-forming protein gasdermin D (GSDMD) and thereby cause pyroptosis. The non-canonical inflammasome assembly triggers such inflammatory cell death by itself; or leverages a secondary activation of the canonical NLRP3 inflammasome pathway. Excessive cell death induced by oligomerization of GSDMD and NINJ1 leads to cytokine release and massive tissue damage, facilitating devastating consequences and death. This review summarized the updated mechanisms that initiate and regulate non-canonical inflammasome activation and pyroptosis and highlighted various endogenous or synthetic molecules as potential therapeutic targets for treating sepsis.

[Diagnostic predictive factors in listeria meningitis]

PURPOSE

The purpose of this study was to elucidate the diagnostic predictive factors of listeria meningitis.

SUBJECTS AND METHOD

Twenty-eight patients with bacterial meningitis (age; 65.9 ± 14.8 years, 11 female) who were admitted to Chikamori Hospital from October 1, 2006 to December 31, 2021 were included. Bacterial meningitis was defined as cerebrospinal fluids (CSF) pleocytosis with evidence of bacterial infection in CSF or blood. The blood and CSF data were reviewed for analysis.

RESULTS

9 patients were diagnosed as listeria meningitis, 19 patients were in non-listeria meningitis. Multiple logistic regression analysis showed that higher CSF lymphocyte ratio was significantly associated with listeria meningitis (Odds ratio 1.123, 95% Confidence interval 1.006-1.2155, P = 0.039). CSF lymphocyte ratio of 30% or more was found to predict listeria meningitis with a sensitivity of 55.6% and a specificity of 100%.

CONCLUSION

CSF lymphocyte ratio may be useful for differentiating between listeria meningitis and non-listeria meningitis.

A Human 2D Primary Organoid-Derived Epithelial Monolayer Model to Study Host-Pathogen Interaction in the Small Intestine

Gut organoids are stem cell derived 3D models of the intestinal epithelium that are useful for studying interactions between enteric pathogens and their host. While the organoid model has been used for both bacterial and viral infections, this is a closed system with the luminal side being inaccessible without microinjection or disruption of the organoid polarization. In order to overcome this and simplify their applicability for transepithelial studies, permeable membrane based monolayer approaches are needed. In this paper, we demonstrate a method for generating a monolayer model of the human fetal intestinal polarized epithelium that is fully characterized and validated. Proximal and distal small intestinal organoids were used to generate 2D monolayer cultures, which were characterized with respect to epithelial cell types, polarization, barrier function, and gene expression. In addition, viral replication and bacterial translocation after apical infection with enteric pathogens Enterovirus A71 and Listeria monocytogenes were evaluated, with subsequent monitoring of the pro-inflammatory host response. This human 2D fetal intestinal monolayer model will be a valuable tool to study host-pathogen interactions and potentially reduce the use of animals in research.

Hyperinvasiveness of Listeria monocytogenes sequence type 1 is independent of lineage I-specific genes encoding internalin-like proteins

Listeriosis is a severe disease caused by the opportunistic bacterial pathogen Listeria monocytogenes (L. monocytogenes). Previous studies indicate that of the four phylogenetical lineages known, lineage I strains are significantly more prevalent in clinical infections than in the environment. Among lineage 1, sequence type (ST1) belongs to the most frequent genotypes in clinical infections and behaves hyperinvasive in experimental in vitro infections compared to lineage II strains suggesting that yet uncharacterized virulence genes contribute to high virulence of certain lineage I strains. This study investigated the effect of four specific lineage I genes encoding surface proteins with internalin-like structures on cellular infection. CNS derived cell lines (fetal bovine brain cells, human microglia cells) and non-CNS derived cell lines (bovine macrophage cells, human adenocarcinoma cells) that represent the various target cells of L. monocytogenes were infected with the parental ST1 strain and deletion mutants of the four genes. Despite their association with lineage I, deletion of the four genes investigated did not dampen the hyperinvasiveness of the ST1 strain. Similarly, these genes did not contribute to the intracellular survival and intercellular spread of L. monocytogenes ST1, indicating that these genes may have other functions, either during the infection process or outside the host.

Biofilms in the Food Industry: Health Aspects and Control Methods

Diverse microorganisms are able to grow on food matrixes and along food industry infrastructures. This growth may give rise to biofilms. This review summarizes, on the one hand, the current knowledge regarding the main bacterial species responsible for initial colonization, maturation and dispersal of food industry biofilms, as well as their associated health issues in dairy products, ready-to-eat foods and other food matrixes. These human pathogens include Bacillus cereus (which secretes toxins that can cause diarrhea and vomiting symptoms), Escherichia coli (which may include enterotoxigenic and even enterohemorrhagic strains), Listeria monocytogenes (a ubiquitous species in soil and water that can lead to abortion in pregnant women and other serious complications in children and the elderly), Salmonella enterica (which, when contaminating a food pipeline biofilm, may induce massive outbreaks and even death in children and elderly), and Staphylococcus aureus (known for its numerous enteric toxins). On the other hand, this review describes the currently available biofilm prevention and disruption methods in food factories, including steel surface modifications (such as nanoparticles with different metal oxides, nanocomposites, antimicrobial polymers, hydrogels or liposomes), cell-signaling inhibition strategies (such as lactic and citric acids), chemical treatments (such as ozone, quaternary ammonium compounds, NaOCl and other sanitizers), enzymatic disruption strategies (such as cellulases, proteases, glycosidases and DNAses), non-thermal plasma treatments, the use of bacteriophages (such as P100), bacteriocins (such us nisin), biosurfactants (such as lichenysin or surfactin) and plant essential oils (such as citral- or carvacrol-containing oils).