Spotlight
Minireview
MinireviewTh17 Cells in Helicobacter pylori Infection: a Dichotomy of Help and HarmHelicobacter pylori is a Gram-negative bacterium that infects the gastric epithelia of its human host. Everyone who is colonized with these pathogenic bacteria can develop gastric inflammation, termed gastritis. Additionally, a small proportion of colonized people develop more adverse outcomes, including gastric ulcer disease, gastric adenocarcinoma, or gastric mucosa...
Molecular Pathogenesis
Molecular PathogenesisDprA-Dependent Exit from the Competent State Regulates Multifaceted Streptococcus pneumoniae VirulenceStreptococcus pneumoniae (pneumococcus) causes multiple infectious diseases. The pneumococcal competence system facilitates genetic transformation, spreads antibiotic resistance, and contributes to virulence. DNA-processing protein A (DprA) regulates the exit of pneumococcus from the competent state. Previously, we have shown that DprA is important in both bacteremia...
Molecular PathogenesisUnderlying Glycans Determine the Ability of Sialylated Lipooligosaccharide To Protect Nontypeable Haemophilus influenzae from Serum IgM and ComplementNontypeable Haemophilus influenzae (NTHi) efficiently colonizes the human nasopharynx asymptomatically but also causes respiratory mucosal infections, including otitis media, sinusitis, and bronchitis. The lipooligosaccharide (LOS) on the cell surface of NTHi displays complex glycans that mimic host structures, allowing it to evade immune recognition. However, LOS...
Molecular PathogenesisDiscovery and Contribution of Nontypeable Haemophilus influenzae NTHI1441 to Human Respiratory Epithelial Cell InvasionNontypeable Haemophilus influenzae (NTHi) is the primary cause of bacterially induced acute exacerbations of chronic obstructive pulmonary disease (COPD). NTHi adheres to and invades host respiratory epithelial cells as a means to persist in the lower airways of adults with COPD. Therefore, we mined the genomes of NTHi strains isolated from the airways of adults with...
Molecular PathogenesisAntimalarial Activity of Human Group IIA Secreted Phospholipase A2 in Relation to Enzymatic Hydrolysis of Oxidized LipoproteinsThe level of human group IIA secreted phospholipase A2 (hGIIA sPLA2) is increased in the plasma of malaria patients, but its role is unknown. In parasite culture with normal plasma, hGIIA is inactive against Plasmodium falciparum, contrasting with hGIIF, hGV, and hGX sPLA2s, which readily hydrolyze plasma lipoproteins, release...
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsType II Secretion Promotes Bacterial Growth within the Legionella-Containing Vacuole in Infected AmoebaeIt was previously determined that the type II secretion system (T2SS) promotes the ability of Legionella pneumophila to grow in coculture with amoebae. Here, we discerned the stage of intracellular infection that is potentiated by comparing the wild-type and T2SS mutant legionellae for their capacity to parasitize...
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsReplication of Coxiella burnetii in a Lysosome-Like Vacuole Does Not Require Lysosomal HydrolasesCoxiella burnetii is an intracellular bacterium that causes query, or Q fever, a disease that typically manifests as a severe flu-like illness. The initial target of C. burnetii is the alveolar macrophage. Here, it regulates vesicle trafficking pathways and fusion events to establish a large...
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsProximity Labeling To Map Host-Pathogen Interactions at the Membrane of a Bacterium-Containing Vacuole in Chlamydia trachomatis-Infected Human CellsMany intracellular bacteria, including the obligate intracellular pathogen Chlamydia trachomatis, grow within a membrane-bound bacterium-containing vacuole (BCV). Secreted cytosolic effectors modulate host activity, but an understanding of the host-pathogen interactions that occur at the BCV membrane is limited by the difficulty in purifying membrane fractions from...
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions | SpotlightFunctional Characterization of an Interferon Gamma Receptor-Like Protein on Entamoeba histolyticaEntamoeba histolytica is an anaerobic parasitic protozoan and the causative agent of amoebiasis. E. histolytica expresses proteins that are structurally homologous to human proteins and uses them as virulence factors. We have previously shown that...
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsThe Msp Protein of Treponema denticola Interrupts Activity of Phosphoinositide Processing in NeutrophilsPeriodontal disease is a significant health burden, causing tooth loss and poor oral and overall systemic health. Dysbiosis of the oral biofilm and a dysfunctional immune response drive chronic inflammation, causing destruction of soft tissue and alveolar bone supporting the teeth. Treponema denticola, a spirochete abundant in the plaque biofilm of patients with...
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsLong-Term Culture of Giardia lamblia in Cell Culture Medium Requires Intimate Association with Viable Mammalian CellsGiardia lamblia is usually cultured axenically in TYI-S-33, a complex medium which does not permit survival and growth of mammalian cells. Likewise, medium commonly used to maintain and grow mammalian cells does not support healthy trophozoite survival for more than a few hours. The inability to coculture trophozoites and epithelial cells under optimal conditions...
Bacterial Infections
Bacterial InfectionsSpiroplasma eriocheiris Enters Drosophila Schneider 2 Cells and Relies on Clathrin-Mediated Endocytosis and MacropinocytosisSpiroplasma eriocheiris causes great economic losses in the crustacean aquaculture industry. However, the mechanism of S. eriocheiris infecting host cells has been poorly studied. We established a Spiroplasma-infected Drosophila Schneider 2 (S2) cell model and investigated its pathogenic mechanism. First,...
Bacterial InfectionsInterleukin 6 Promotes Brucella abortus Clearance by Controlling Bactericidal Activity of Macrophages and CD8+ T Cell DifferentiationTo date, the implications of interleukin 6 (IL-6) for immune responses in the context of Brucella infection are still unknown. In the present study, we found that Brucella abortus infection induced marked production of IL-6 in mice that was important for sufficient differentiation of CD8+ T cells, a key factor in Brucella clearance.
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Bacterial InfectionsIdentification of Novel Bacteriophages with Therapeutic Potential That Target Enterococcus faecalisThe Gram-positive opportunistic pathogen Enterococcus faecalis is frequently responsible for nosocomial infections in humans and represents one of the most common bacteria isolated from recalcitrant endodontic (root canal) infections. E. faecalis is intrinsically resistant to several antibiotics...
Bacterial InfectionsPotential Mechanisms of Mucin-Enhanced Acinetobacter baumannii Virulence in the Mouse Model of Intraperitoneal InfectionPorcine mucin has been commonly used to enhance the infectivity of bacterial pathogens, including Acinetobacter baumannii, in animal models, but the mechanisms for enhancement by mucin remain relatively unknown. In this study, using the mouse model of intraperitoneal (i.p.) mucin-enhanced A. baumannii...
Host Response and Inflammation
Host Response and InflammationInterleukin-21 (IL-21) Downregulates Dendritic Cell Cytokine Responses to Helicobacter pylori and Modulates T Lymphocyte IL-17A Expression in Peyer’s Patches during InfectionInterleukin-21 (IL-21), a cytokine produced by many subsets of activated immune cells, is critical for driving inflammation in several models. Using Helicobacter pylori infection as a model for chronic mucosal infection, we previously published that IL-21 is required for the development of gastritis in response to infection. Concomitant with protection from chronic...
Host Response and InflammationIntestinal Epithelial Cells Exposed to Bacteroides fragilis Enterotoxin Regulate NF-κB Activation and Inflammatory Responses through β-Catenin ExpressionThe Bacteroides fragilis enterotoxin (BFT), a virulence factor of enterotoxigenic B. fragilis (ETBF), interacts with intestinal epithelial cells and can provoke signals that induce mucosal inflammation. Although β-catenin signaling is reported to be associated with inflammatory responses and BFT is...
Host Response and InflammationInterleukin 17 Receptor E (IL-17RE) and IL-17C Mediate the Recruitment of Neutrophils during Acute Streptococcus pneumoniae PneumoniaNeutrophils contribute to lung injury in acute pneumococcal pneumonia. The interleukin 17 receptor E (IL-17RE) is the functional receptor for the epithelial-derived cytokine IL-17C, which is known to mediate innate immune functions. The aim of this study was to investigate the contribution of IL-17RE/IL-17C to pulmonary inflammation in a mouse model of acute Streptococcus...
Host Response and InflammationElucidation of the Interleukin 12 Production Mechanism during Intracellular Bacterial Infection in Amberjack, Seriola dumeriliIntracellular bacterial infections affect all vertebrates. Cultured fish are particularly vulnerable because no effective protection measures have been established since such infections emerged approximately 50 years ago. As in other vertebrates, the induction of cell-mediated immunity (CMI) plays an important role in protecting fish against infection. However, details of the mechanism of CMI induction in fish have not been clarified....
Host Response and InflammationInterleukin-22 (IL-22) Binding Protein Constrains IL-22 Activity, Host Defense, and Oxidative Phosphorylation Genes during Pneumococcal PneumoniaStreptococcus pneumoniae is the most common cause of community-acquired pneumonia worldwide, and interleukin-22 (IL-22) helps contain pneumococcal burden in lungs and extrapulmonary tissues. Administration of IL-22 increases hepatic complement 3 and complement deposition on bacteria and improves phagocytosis by neutrophils. The effects of IL-22 can be tempered by a...
Host Response and InflammationImmunomodulatory Effects of Lactobacillus plantarum on Inflammatory Response Induced by Klebsiella pneumoniaeSome respiratory infections have been associated with dysbiosis of the intestinal microbiota. The underlying mechanism is incompletely understood, but cross talk between the intestinal microbiota and local immune cells could influence the immune response at distal mucosal sites. This has led to the concept of enhancing respiratory defenses by modulating the intestinal microbiota with exogenous supplementation of beneficial strains....
Host Response and InflammationYersiniabactin-Producing Adherent/Invasive Escherichia coli Promotes Inflammation-Associated Fibrosis in Gnotobiotic Il10−/− MiceFibrosis is a significant complication of intestinal disorders associated with microbial dysbiosis and pathobiont expansion, notably Crohn’s disease (CD). Mechanisms that favor fibrosis are not well understood, and therapeutic strategies are limited. Here we demonstrate that colitis-susceptible Il10-deficient mice develop inflammation-associated fibrosis when monoassociated with adherent/invasive...
Fungal and Parasitic Infections
Fungal and Parasitic InfectionsLeishmania Infection Induces Macrophage Vascular Endothelial Growth Factor A Production in an ARNT/HIF-Dependent MannerCutaneous leishmaniasis is characterized by vascular remodeling. Following infection with Leishmania parasites, the vascular endothelial growth factor A (VEGF-A)/VEGF receptor 2 (VEGFR-2) signaling pathway mediates lymphangiogenesis, which is critical for lesion resolution. Therefore, we investigated the cellular and molecular mediators involved in VEGF-A/VEGFR-2 signaling using a murine model of infection.
Microbial Immunity and Vaccines
Microbial Immunity and VaccinesCurcumin Nanoparticles Enhance Mycobacterium bovis BCG Vaccine Efficacy by Modulating Host Immune ResponsesTuberculosis (TB) is one of the deadliest diseases, causing ∼2 million deaths annually worldwide. Mycobacterium bovis bacillus Calmette-Guérin (BCG), the only TB vaccine in common use, is effective against disseminated and meningeal TB in young children but is not effective against adult pulmonary TB.
Microbial Immunity and VaccinesEosinophils Affect Antibody Isotype Switching and May Partially Contribute to Early Vaccine-Induced Immunity against Coxiella burnetiiCoxiella burnetii is an obligate intracellular Gram-negative bacterium which causes human Q fever. An acidified citrate cysteine medium (ACCM-2) has been developed which mimics the intracellular replicative niche of C. burnetii and allows axenic growth of the bacteria.
Microbial Immunity and VaccinesIntradermal or Sublingual Delivery and Heat-Labile Enterotoxin Proteins Shape Immunologic Responses to a CFA/I Fimbria-Derived Subunit Antigen Vaccine against Enterotoxigenic Escherichia coliEnterotoxigenic Escherichia coli (ETEC) is a major cause of infectious diarrhea in children, travelers, and deployed military personnel. As such, development of a vaccine would be advantageous for public health. One strategy is to use subunits of colonization factors combined with antigen/adjuvant toxoids as an ETEC vaccine.
Microbial Immunity and VaccinesUnexpected Role of CD8 T Cells in Accelerated Clearance of Salmonella enterica Serovar Typhimurium from H-2 Congenic miceSalmonella infection can cause gastroenteritis in healthy individuals or a serious, systemic infection in immunocompromised patients and has a global impact. CD4 Th1 cells represent the main lymphocyte population that participates in bacterial clearance during both primary and secondary infections in mice of the H-2b haplotype.
Microbial Immunity and VaccinesIdentification and Application of Epitopes in EtMIC1 of Eimeria tenella Recognized by the Monoclonal Antibodies 1-A1 and 1-H2Eimeria tenella microneme-1 protein (EtMIC1) has been proposed to be a transmembrane protein, but this characteristic has not yet been confirmed experimentally. Furthermore, despite EtMIC1 being an important candidate antigen, its key epitope has not been reported.
Host-Associated Microbial Communities
Host-Associated Microbial CommunitiesThe Host Immune System Facilitates Disseminated Staphylococcus aureus Disease Due to Phagocytic Attraction to Candida albicans during Coinfection: a Case of Bait and SwitchInvasive Staphylococcus aureus infections account for 15 to 50% of fatal bloodstream infections annually. These disseminated infections often arise without a defined portal of entry into the host but cause high rates of mortality. The fungus Candida albicans and the Gram-positive bacterium...
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Infection and Immunity® (IAI) reports key discoveries that help microbiologists, immunologists, epidemiologists, pathologists, and clinicians to gain new insights into the underlying mechanisms of host-pathogen interactions and develop novel strategies to prevent or treat infectious diseases.