Misoprostol protects mice against severe Clostridium difficile infection and promotes recovery of the gut microbiota after antibiotic perturbation.

Clostridium difficile infection (CDI) is one of the most common nosocomial infections worldwide and an urgent public health threat. Epidemiological and experimental studies have demonstrated an association between nonsteroidal anti-inflammatory drug (NSAID) exposure and enhanced susceptibility to, and severity of, CDI. NSAIDs target cyclooxygenase enzymes and inhibit the production of prostaglandins (PGs), but the therapeutic potential of exogenous introduction of PGs for the treatment of CDI has not been explored. In this study, we report that treatment with the FDA-approved stable PGE1 analogue, misoprostol, protects mice against C. difficile-associated mortality, intestinal pathology, and CDI-mediated intestinal permeability. Furthermore, we report that the effect of misoprostol on the gastrointestinal tract contributes to increased recovery of the gut microbiota following antibiotic perturbation. Together, these data implicate PGs as an important host-factor associated with recovery to C. difficile-associated disease and demonstrate the potential for misoprostol in the treatment of CDI. Further studies to explore the safety and efficacy of misoprostol treatment of CDI in humans is needed.

Nonsteroidal Anti-inflammatory Drugs Alter the Microbiota and Exacerbate Clostridium difficile Colitis while Dysregulating the Inflammatory Response.

Clostridium difficile infection (CDI) is a major public health threat worldwide. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with enhanced susceptibility to and severity of CDI; however, the mechanisms driving this phenomenon have not been elucidated. NSAIDs alter prostaglandin (PG) metabolism by inhibiting cyclooxygenase (COX) enzymes. Here, we found that treatment with the NSAID indomethacin prior to infection altered the microbiota and dramatically increased mortality and the intestinal pathology associated with CDI in mice. We demonstrated that in C. difficile-infected animals, indomethacin treatment led to PG deregulation, an altered proinflammatory transcriptional and protein profile, and perturbed epithelial cell junctions. These effects were paralleled by increased recruitment of intestinal neutrophils and CD4+ cells and also by a perturbation of the gut microbiota. Together, these data implicate NSAIDs in the disruption of protective COX-mediated PG production during CDI, resulting in altered epithelial integrity and associated immune responses.IMPORTANCEClostridium difficile infection (CDI) is a spore-forming anaerobic bacterium and leading cause of antibiotic-associated colitis. Epidemiological data suggest that use of nonsteroidal anti-inflammatory drugs (NSAIDs) increases the risk for CDI in humans, a potentially important observation given the widespread use of NSAIDs. Prior studies in rodent models of CDI found that NSAID exposure following infection increases the severity of CDI, but mechanisms to explain this are lacking. Here we present new data from a mouse model of antibiotic-associated CDI suggesting that brief NSAID exposure prior to CDI increases the severity of the infectious colitis. These data shed new light on potential mechanisms linking NSAID use to worsened CDI, including drug-induced disturbances to the gut microbiome and colonic epithelial integrity. Studies were limited to a single NSAID (indomethacin), so future studies are needed to assess the generalizability of our findings and to establish a direct link to the human condition.

Protein kinase D mediates inflammatory responses of human placental macrophages to Group B Streptococcus.

PROBLEM: During pregnancy, Group B Streptococcus (GBS) can infect fetal membranes to cause chorioamnionitis, resulting in adverse pregnancy outcomes. Macrophages are the primary resident phagocyte in extraplacental membranes. Protein kinase D (PKD) was recently implicated in mediating pro-inflammatory macrophage responses to GBS outside of the reproductive system. This work aimed to characterize the human placental macrophage inflammatory response to GBS and address the extent to which PKD mediates such effects. METHOD: Primary human placental macrophages were infected with GBS in the presence or absence of a specific, small molecule PKD inhibitor, CRT 0066101. Macrophage phenotypes were characterized by evaluating gene expression, cytokine release, assembly of the NLRP3 inflammasome, and NFκB activation. RESULTS: GBS evoked a strong inflammatory phenotype characterized by the release of inflammatory cytokines (TNFα, IL-1ß, IL-6 (P ≤ 0.05), NLRP3 inflammasome assembly (P ≤ 0.0005), and NFκB activation (P ≤ 0.05). Pharmacological inhibition of PKD suppressed these responses, newly implicating a role for PKD in mediating immune responses of primary human placental macrophages to GBS. CONCLUSION: PKD plays a critical role in mediating placental macrophage inflammatory activation in response to GBS infection.

Indomethacin increases severity of Clostridium difficile infection in mouse model.

AIM: To evaluate the effect on the nonsteroidal anti-inflammatory drug indomethacin on Clostridium difficile infection (CDI) severity. MATERIALS & METHODS: Indomethacin was administered in two different mouse models of antibiotic-associated CDI in two different facilities, using a low and high dose of indomethacin. RESULTS: Indomethacin administration caused weight loss, increased the signs of severe infection and worsened histopathological damage, leading to 100% mortality during CDI. Indomethacin-treated, antibiotic-exposed mice infected with C. difficile had enhanced intestinal inflammation with increased expression of KC, IL-1ß and IL-22 compared with infected mice unexposed to indomethacin. CONCLUSION: These results demonstrate a negative impact of nonsteroidal anti-inflammatory drugs on antibiotic-associated CDI in mice and suggest that targeting the synthesis or signaling of prostaglandins might be an approach to ameliorating the severity of CDI.

Group B Streptococcus Induces Neutrophil Recruitment to Gestational Tissues and Elaboration of Extracellular Traps and Nutritional Immunity.

Streptococcus agalactiae, or Group B Streptococcus (GBS), is a gram-positive bacterial pathogen associated with infection during pregnancy and is a major cause of morbidity and mortality in neonates. Infection of the extraplacental membranes surrounding the developing fetus, a condition known as chorioamnionitis, is characterized histopathologically by profound infiltration of polymorphonuclear cells (PMNs, neutrophils) and greatly increases the risk for preterm labor, stillbirth, or neonatal GBS infection. The advent of animal models of chorioamnionitis provides a powerful tool to study host-pathogen relationships in vivo and ex vivo. The purpose of this study was to evaluate the innate immune response elicited by GBS and evaluate how antimicrobial strategies elaborated by these innate immune cells affect bacteria. Our work using a mouse model of GBS ascending vaginal infection during pregnancy reveals that clinically isolated GBS has the capacity to invade reproductive tissues and elicit host immune responses including infiltration of PMNs within the choriodecidua and placenta during infection, mirroring the human condition. Upon interacting with GBS, murine neutrophils elaborate DNA-containing extracellular traps, which immobilize GBS and are studded with antimicrobial molecules including lactoferrin. Exposure of GBS to holo- or apo-forms of lactoferrin reveals that the iron-sequestration activity of lactoferrin represses GBS growth and viability in a dose-dependent manner. Together, these data indicate that the mouse model of ascending infection is a useful tool to recapitulate human models of GBS infection during pregnancy. Furthermore, this work reveals that neutrophil extracellular traps ensnare GBS and repress bacterial growth via deposition of antimicrobial molecules, which drive nutritional immunity via metal sequestration strategies.

Staphylococcus aureus Infection of Human Gestational Membranes Induces Bacterial Biofilm Formation and Host Production of Cytokines.

Staphylococcus aureus, a metabolically flexible gram-positive pathogen, causes infections in a variety of tissues. Recent evidence implicates S. aureus as an emerging cause of chorioamnionitis and premature rupture of membranes, which are associated with preterm birth and neonatal disease. We demonstrate here that S. aureus infects and forms biofilms on the choriodecidual surface of explanted human gestational membranes. Concomitantly, S. aureus elicits the production of proinflammatory cytokines, which could ultimately perturb maternal-fetal tolerance during pregnancy. Therefore, targeting the immunological response to S. aureus infection during pregnancy could attenuate disease among infected individuals, especially in the context of antibiotic resistance.

Immediate detailed feedback to test-enhanced learning: an effective online educational tool.

BACKGROUND: Test-enhanced learning has gained popularity because it is an effective way to increase retention of knowledge; provided the student receives the correct answer soon after the test is taken. AIM: To determine whether detailed feedback provided to test-enhanced learning questions is an effective online educational tool for improving performance on complex biomedical information exams. METHODS: A series of online multiple choice tests were developed to test knowledge of biomedical information that students were expected to know after each patient-case. Following submission of the student answers, one cohort (n = 52) received answers only while the following year, a second cohort (n = 51) received the answers with detailed feedback explaining why each answer was correct or incorrect. RESULTS: Students in both groups progressed through the series of online tests with little assessor intervention. Students receiving the answers along with the explanations within their feedback performed significantly better in the final biomedical information exam than those students receiving correct answers only. CONCLUSIONS: This pilot study found that the detailed feedback to test-enhanced learning questions is an important online learning tool. The increase in student performance in the complex biomedical information exam in this study suggests that detailed feedback should be investigated not only for increasing knowledge, but also be investigated for its effect on retention and application of knowledge.