Spotlight
Molecular Pathogenesis
Molecular PathogenesisCompeting Substrates for the Bifunctional Diaminopimelic Acid Epimerase/Glutamate Racemase Modulate Peptidoglycan Synthesis in Chlamydia trachomatisThe Chlamydia trachomatis genome encodes multiple bifunctional enzymes, such as DapF, which is capable of both diaminopimelic acid (DAP) epimerase and glutamate racemase activity. Our previous work demonstrated the bifunctional activity of chlamydial DapF in vitro and in a heterologous system (...
Molecular Pathogenesis | SpotlightRole of metAB in Methionine Metabolism and Optimal Chicken Colonization in Campylobacter jejuniCampylobacter jejuni is a zoonotic pathogen and is one of the leading causes of human gastroenteritis worldwide. C. jejuni IA3902 (representative of the sheep abortion clone) is genetically similar to C. jejuni W7 (representative...
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsEffects of Myeloid Hif-1β Deletion on the Intestinal Microbiota in Mice under Environmental HypoxiaExternal environmental factors can cause an imbalance in intestinal flora. For people living in the extremes of a plateau climate, lack of oxygen is a primary health challenge that leads to a series of reactions. We wondered how intestinal microorganisms might change in a simulated plateau environment and what changes might occur in the host organism and intestinal microorganisms in the absence of hypoxia-related factors. In this study...
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsThe Extracellular Polysaccharide Matrix of Pseudomonas aeruginosa Biofilms Is a Determinant of Polymorphonuclear Leukocyte ResponsesBacterial biofilms may cause chronic infections due to their ability to evade clearance by the immune system and antibiotics. The persistent biofilms induce a hyperinflammatory state that damages the surrounding host tissue. Knowledge about the components of biofilms that are responsible for provoking the harmful but inefficient immune response is limited. Flagella are known to stimulate the response of polymorphonuclear leukocytes (...
Bacterial Infections
Bacterial InfectionsGigC, a LysR Family Transcription Regulator, Is Required for Cysteine Metabolism and Virulence in Acinetobacter baumanniiA critical facet of mammalian innate immunity involves the hosts’ attempts to sequester and/or limit the availability of key metabolic products from pathogens. For example, nutritional immunity encompasses host approaches to limit the availability of key heavy metal ions such as zinc and iron. Previously, we identified several hundred genes in a multidrug-resistant isolate of...
Bacterial InfectionsThe Impact of Circulating Antibody on Group B Streptococcus Intestinal Colonization and Invasive DiseaseGastrointestinal (GI) colonization with group B Streptococcus (GBS) is an important precursor to late-onset (LO) disease in infants. The host-pathogen interactions that mediate progression to invasive disease remain unknown due, in part, to a paucity of robust model systems. Passively acquired maternal GBS-specific antibodies protect newborns from early-onset disease, yet their impact on GI colonization and LO disease is...
Bacterial InfectionsBronchial Epithelial Tet2 Maintains Epithelial Integrity during Acute Pseudomonas aeruginosa PneumoniaRespiratory epithelial cells are important for pulmonary innate immune responses during Pseudomonas aeruginosa infection. Tet methylcytosine dioxygenase 2 (Tet2) has been implicated in the regulation of host defense by myeloid and lymphoid cells, but whether Tet2 also contributes to epithelial responses during pneumonia is unknown. The aim of this study was to...
Bacterial InfectionsBurkholderia pseudomallei as an Enteric Pathogen: Identification of Virulence Factors Mediating Gastrointestinal InfectionBurkholderia pseudomallei is a Gram-negative bacterium and the causative agent of melioidosis. Despite advances in our understanding of the disease, B. pseudomallei poses a significant health risk, especially in regions of endemicity, where treatment requires prolonged antibiotic therapy. Even...
Host Response and Inflammation
Host Response and Inflammation | SpotlightRegulation of Pulmonary Bacterial Immunity by Follistatin-Like Protein 1Klebsiella pneumoniae is a common cause of antibiotic-resistant pneumonia. Follistatin-like protein 1 (FSTL-1) is highly expressed in the lung and is critical for lung homeostasis. The role of FSTL-1 in immunity to bacterial pneumonia is unknown. Wild-type (WT) and FSTL-1 hypomorphic (Hypo) mice were infected with...
Host Response and InflammationEffect of CARD9 Deficiency on Neutrophil-Mediated Host Defense against Pulmonary Infection with Streptococcus pneumoniaeStreptococcus pneumoniae is a major causative bacterium of community-acquired pneumonia. Dendritic cell-associated C-type lectin-2 (dectin-2), one of the C-type lectin receptors (CLRs), was previously reported to play a pivotal role in host defense against pneumococcal infection through regulating phagocytosis by neutrophils while not being involved in neutrophil...
Host Response and InflammationToll-Like Receptor 2-Tpl2-Dependent ERK Signaling Drives Inverse Interleukin 12 Regulation in Dendritic Cells and MacrophagesThis study investigated responses to Toll-like receptor 2 (TLR2)-driven extracellular signal-related kinase (ERK) signaling in dendritic cells (DCs) versus macrophages. TLR2 signaling was induced with Pam3Cys-Ser-Lys4, and the role of ERK signaling was interrogated pharmacologically with MEK1/2 inhibitor U0126 or genetically with bone marrow-derived macrophages or DCs from Tpl2−/− mice. We...
Host Response and InflammationFailure of CD4 T Cell-Deficient Hosts To Control Chronic Nontyphoidal Salmonella Infection Leads to Exacerbated Inflammation, Chronic Anemia, and Altered MyelopoiesisImmunocompromised patients are more susceptible to recurrent nontyphoidal Salmonella (NTS) bacteremia. A key manifestation of HIV infection is the loss of CD4 T cells, which are crucial for immunity to Salmonella infection. We characterized the consequences of CD4 T cell depletion in mice where virulent Salmonella establish chronic infection, similar to chronic NTS disease in humans. Salmonella-...
Host Response and InflammationSilencing of Ac45 Simultaneously Inhibits Osteoclast-Mediated Bone Resorption and Attenuates Dendritic Cell-Mediated Inflammation through Impairing Acidification and Cathepsin K SecretionEndodontic disease is characterized by inflammation and destruction of periapical tissues, leading to severe bone resorption and tooth loss. ATP6AP1 (Ac45) has been implicated in human immune diseases, yet the mechanism underlying how Ac45 regulates immune response and reaction in inflammatory diseases remains unknown. We generated endodontic disease mice through bacterial infection as an inflammatory disease model and used adeno-...
Host Response and InflammationAkkermansia muciniphila and Its Pili-Like Protein Amuc_1100 Modulate Macrophage Polarization in Experimental PeriodontitisPeriodontitis is a chronic inflammatory disease triggered by dysbiosis of the oral microbiome. Porphyromonas gingivalis is strongly implicated in periodontal inflammation, gingival tissue destruction, and alveolar bone loss through sustained exacerbation of the host response. Recently, the use of other bacterial species, such as...
Host Response and InflammationEscherichia coli K12 Upregulates Programmed Cell Death Ligand 1 (PD-L1) Expression in Gamma Interferon-Sensitized Intestinal Epithelial Cells via the NF-κB PathwayProgrammed cell death ligand-1 (PD-L1) is an immune checkpoint protein which is used by tumor cells for immune evasion. PD-L1 is upregulated in inflamed intestinal tissues. The intestinal tract is colonized by millions of bacteria, most of which are commensal bacterial species. We hypothesized that under inflammatory conditions, some commensal bacterial species contribute to increased PD-L1 expression in intestinal epithelium and...
Fungal and Parasitic Infections
Fungal and Parasitic InfectionsLactic Acid Supplementation Increases Quantity and Quality of Gametocytes in Plasmodium falciparum CultureMalaria infection by Plasmodium falciparum continues to afflict millions of people worldwide, with transmission being dependent upon mosquito ingestion of the parasite gametocyte stage. These sexually committed stages develop from the asexual stages, yet the factors behind this transition are not completely understood. Here, we found that lactic acid increases...
Fungal and Parasitic InfectionsInterleukin-8 Receptor 2 (IL-8R2)-Deficient Mice Are More Resistant to Pulmonary Coccidioidomycosis than Control MiceThe pathology of human coccidioidomycosis is granulomatous inflammation with many neutrophils surrounding ruptured spherules, but the chemotactic pathways that draw neutrophils into the infected tissues are not known. We previously showed that formalin-killed spherules (FKS) stimulate mouse macrophages to secret macrophage inflammatory protein 2 (MIP-2), which suggested that CXC ELR+ chemokines might be involved in neutrophil...
Microbial Immunity and Vaccines
Microbial Immunity and VaccinesAntibody Opsonization Enhances Early Interactions between Yersinia pestis and Neutrophils in the Skin and Draining Lymph Node in a Mouse Model of Bubonic PlagueBubonic plague results when Yersinia pestis is deposited in the skin via the bite of an infected flea. Bacteria then traffic to the draining lymph node (dLN) where they replicate to large numbers. Without treatment, this infection can result in highly fatal septicemia. Several plague vaccine candidates are currently at various stages of development, but no licensed...
Microbial Immunity and Vaccines | SpotlightChlamydia-Specific IgA Secretion in the Female Reproductive Tract Induced via Per-Oral Immunization Confers Protection against Primary Chlamydia ChallengeChlamydia trachomatis is an obligate intracellular pathogen that causes sexually transmitted disease. In women, chlamydial infections may cause pelvic inflammatory disease (PID), ectopic pregnancy, and infertility. The role of antibodies in protection against a primary Chlamydia infection is unclear and was a focus of this work. Using the...
Microbial Immunity and Vaccines | SpotlightEfficient 5-OP-RU-Induced Enrichment of Mucosa-Associated Invariant T Cells in the Murine Lung Does Not Enhance Control of Aerosol Mycobacterium tuberculosis InfectionMucosa-associated invariant T (MAIT) cells are an innate-like T cell subset in mammals that recognize microbial vitamin B metabolites presented by the evolutionarily conserved major histocompatibility complex class I (MHC I)-related molecule, MR1. Emerging data suggest that MAIT cells may be an attractive target for vaccine-induced protection against bacterial infections because of their rapid cytotoxic responses at mucosal services to...
Host-Associated Microbial Communities
Host-Associated Microbial CommunitiesThe Arg753Gln Polymorphism of Toll-Like Receptor 2 Has a Lower Occurrence in Patients with Syphilis, Suggesting Its Protective Effect in Czech and Slovak IndividualsSyphilis is a bacterial infection caused by Treponema pallidum subsp. pallidum. Infection with T. pallidum subsp. pallidum and its dissemination lead to the synthesis of proinflammatory cytokines triggered by the interaction of bacterial lipoproteins with Toll-like receptor 2 (TLR2...
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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.