Host-derived CEACAM-laden vesicles engage enterotoxigenic Escherichia coli for elimination and toxin neutralization.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of diarrheal illnesses annually ranging from mildly symptomatic cases to severe, life-threatening cholera-like diarrhea. Although ETEC are associated with long-term sequelae including malnutrition, the acute diarrheal illness is largely self-limited. Recent studies indicate that in addition to causing diarrhea, the ETEC heat-labile toxin (LT) modulates the expression of many genes in intestinal epithelia, including carcinoembryonic cell adhesion molecules (CEACAMs) which ETEC exploit as receptors, enabling toxin delivery. Here, however, we demonstrate that LT also enhances the expression of CEACAMs on extracellular vesicles (EV) shed by intestinal epithelia and that CEACAM-laden EV increase in abundance during human infections, mitigate pathogen-host interactions, scavenge free ETEC toxins, and accelerate ETEC clearance from the gastrointestinal tract. Collectively, these findings indicate that CEACAMs play a multifaceted role in ETEC pathogen-host interactions, transiently favoring the pathogen, but ultimately contributing to innate responses that extinguish these common infections.

Farnesoid X receptor enhances epithelial ACE2 expression and inhibits virally induced IL-6 secretion: implications for intestinal symptoms of SARS-CoV-2.

Intestinal inflammation and diarrhea are often associated with SARS-CoV-2 infection. The angiotensin converting enzyme 2 (ACE2) receptor plays a key role in SARS-CoV-2 pathogenesis, facilitating entry of the virus into epithelial cells, while also regulating mucosal inflammatory responses. Here, we investigated roles for the nuclear bile acid receptor farnesoid X receptor (FXR) in regulating ACE2 expression and virally mediated inflammatory responses in intestinal epithelia. Human colonic or ileal enteroids and cultured T84 and Caco-2 monolayers were treated with the FXR agonists, obeticholic acid (OCA) or GW4064, or infected with live SARS-CoV-2 (2019-nCoV/USA_WA1/2020). Changes in mRNA, protein, or secreted cytokines were measured by qPCR, Western blotting, and ELISA. Treatment of undifferentiated colonic or ileal enteroids with OCA increased ACE2 mRNA by 2.1 ± 0.4-fold (n = 3; P = 0.08) and 2.3 ± 0.2-fold (n = 3; P < 0.05), respectively. In contrast, ACE2 expression in differentiated enteroids was not significantly altered. FXR activation in cultured epithelial monolayers also upregulated ACE2 mRNA, accompanied by increases in ACE2 expression and secretion. Further experiments revealed FXR activation to inhibit IL-6 release from both Caco-2 cells infected with SARS-CoV-2 and T84 cells treated with the viral mimic, polyinosinic:polycytidylic acid, by 46 ± 12% (n = 3, P < 0.05) and 35 ± 6% (n = 8; P < 0.01), respectively. By virtue of its ability to modulate epithelial ACE2 expression and inhibit virus-mediated proinflammatory cytokine release, FXR represents a promising target for the development of new approaches to prevent intestinal manifestations of SARS-CoV-2.NEW & NOTEWORTHY Activation of the nuclear bile acid receptor, farnesoid X receptor (FXR), specifically upregulates ACE2 expression in undifferentiated colonic epithelial cells and inhibits virus-induced proinflammatory cytokine release. By virtue of these actions FXR represents a promising target for the development of new approaches to prevent intestinal manifestations of SARS-CoV-2 infection.

The Queensland Inpatient Diabetes Survey (QuIDS) 2019: the bedside audit of practice.

OBJECTIVES: To assess the quality of care for patients with diabetes in Queensland hospitals, including blood glucose control, rates of hospital-acquired harm, the incidence of insulin prescription and management errors, and appropriate foot and peri-operative care. DESIGN, SETTING: Cross-sectional audit of 27 public hospitals in Queensland: four of five tertiary/quaternary referral centres, four of seven large regional or outer metropolitan hospitals, seven of 13 smaller outer metropolitan or small regional hospitals, and 12 of 88 hospitals in rural or remote locations. PARTICIPANTS: 850 adult inpatients with diabetes mellitus in medical, surgical, mental health, high dependency, or intensive care wards. RESULTS: Twenty-seven of 115 public hospitals that admit acute inpatients participated in the audit, including 4175 of 6652 eligible acute hospital beds in Queensland. A total of 1003 patients had diabetes (24%), and data were collected for 850 (85%). Their mean age was 65.9 years (SD, 15.1 years), 357 were women (42%), and their mean HbA1c level was 66 mmol/mol (SD, 26 mmol/mol). Rates of good diabetes days (appropriate monitoring, no more than one blood glucose measurement greater than 10 mmol/L, and none below 5 mmol/L) were low in patients with type 1 diabetes (22.1 per 100 patient-days) or type 2 diabetes treated with insulin (40.1 per 100 patient-days); hypoglycaemia rates were high for patients with type 1 diabetes mellitus (24.1 episodes per 100 patient-days). One or more medication errors were identified for 201 patients (32%), including insulin prescribing errors for 127 patients (39%). Four patients with type 1 diabetes experienced diabetic ketoacidosis in hospital (8%); 121 patients (14%) met the criteria for review by a specialist diabetes team but were not reviewed by any diabetes specialist (medical, nursing, allied health). CONCLUSIONS: We identified several deficits in inpatient diabetes management in Queensland, including high rates of medication error and hospital-acquired harm and low rates of appropriate glycaemic control, particularly for patients treated with insulin. These deficits require attention, and ongoing evaluation of outcomes is necessary.

Lipofuscin Formation Catalyzed by the Milk Protein ß-Lactoglobulin: Lysine Residues in Cycloretinal Synthesis.

Lipofuscins are toxic autofluorescent byproducts of the visual cycle. The accumulation of lipofuscins such as cycloretinal in the retina is thought to play a role in the progression of age-related macular degeneration (AMD). Intriguingly, the milk protein ß-lactoglobulin (BLG) can promote the cyclodimerization of all-trans-retinal to cycloretinal both in vitro and in vivo. Here, site-directed mutagenesis of BLG and mass spectrometric analysis with substrate analogues demonstrate that lysine residues play a key role in catalysis. It is also shown that catalytic activity necessitates the presence of a physical binding site and cannot be mediated by a peptide chain. These studies provide insight into the mechanism of the cyclodimerization process and provide a model system for biocatalysis and biosynthesis of cycloretinal in vivo. In the long term, these studies may pave the way for drug development and inhibitor design as an early treatment regimen for AMD.

Human Enteroids/Colonoids and Intestinal Organoids Functionally Recapitulate Normal Intestinal Physiology and Pathophysiology.

Identification of Lgr5 as the intestinal stem cell marker as well as the growth factors necessary to replicate adult intestinal stem cell division has led to the establishment of the methods to generate "indefinite" ex vivo primary intestinal epithelial cultures, termed "mini-intestines." Primary cultures developed from isolated intestinal crypts or stem cells (termed enteroids/colonoids) and from inducible pluripotent stem cells (termed intestinal organoids) are being applied to study human intestinal physiology and pathophysiology with great expectations for translational applications, including regenerative medicine. Here we discuss the physiologic properties of these cultures, their current use in understanding diarrhea-causing host-pathogen interactions, and potential future applications.

Human Enteroids as a Model of Upper Small Intestinal Ion Transport Physiology and Pathophysiology.

BACKGROUND & AIMS: Human intestinal crypt-derived enteroids are a model of intestinal ion transport that require validation by comparison with cell culture and animal models. We used human small intestinal enteroids to study neutral Na(+) absorption and stimulated fluid and anion secretion under basal and regulated conditions in undifferentiated and differentiated cultures to show their functional relevance to ion transport physiology and pathophysiology. METHODS: Human intestinal tissue specimens were obtained from an endoscopic biopsy or surgical resections performed at Johns Hopkins Hospital. Crypts were isolated, enteroids were propagated in culture, induced to undergo differentiation, and transduced with lentiviral vectors. Crypt markers, surface cell enzymes, and membrane ion transporters were characterized using quantitative reverse-transcription polymerase chain reaction, immunoblot, or immunofluorescence analyses. We used multiphoton and time-lapse confocal microscopy to monitor intracellular pH and luminal dilatation in enteroids under basal and regulated conditions. RESULTS: Enteroids differentiated upon withdrawal of WNT3A, yielding decreased crypt markers and increased villus-like characteristics. Na(+)/H(+) exchanger 3 activity was similar in undifferentiated and differentiated enteroids, and was affected by known inhibitors, second messengers, and bacterial enterotoxins. Forskolin-induced swelling was completely dependent on cystic fibrosis transmembrane conductance regulator and partially dependent on Na(+)/H(+) exchanger 3 and Na(+)/K(+)/2Cl(-) cotransporter 1 inhibition in undifferentiated and differentiated enteroids. Increases in cyclic adenosine monophosphate with forskolin caused enteroid intracellular acidification in HCO3(-)-free buffer. Cyclic adenosine monophosphate-induced enteroid intracellular pH acidification as part of duodenal HCO3(-) secretion appears to require cystic fibrosis transmembrane conductance regulator and electrogenic Na(+)/HCO3(-) cotransporter 1. CONCLUSIONS: Undifferentiated or crypt-like, and differentiated or villus-like, human enteroids represent distinct points along the crypt-villus axis; they can be used to characterize electrolyte transport processes along the vertical axis of the small intestine. The duodenal enteroid model showed that electrogenic Na(+)/HCO3(-) cotransporter 1 might be a target in the intestinal mucosa for treatment of secretory diarrheas.

Human Intestinal Enteroids: a New Model To Study Human Rotavirus Infection, Host Restriction, and Pathophysiology.

UNLABELLED: Human gastrointestinal tract research is limited by the paucity of in vitro intestinal cell models that recapitulate the cellular diversity and complex functions of human physiology and disease pathology. Human intestinal enteroid (HIE) cultures contain multiple intestinal epithelial cell types that comprise the intestinal epithelium (enterocytes and goblet, enteroendocrine, and Paneth cells) and are physiologically active based on responses to agonists. We evaluated these nontransformed, three-dimensional HIE cultures as models for pathogenic infections in the small intestine by examining whether HIEs from different regions of the small intestine from different patients are susceptible to human rotavirus (HRV) infection. Little is known about HRVs, as they generally replicate poorly in transformed cell lines, and host range restriction prevents their replication in many animal models, whereas many animal rotaviruses (ARVs) exhibit a broader host range and replicate in mice. Using HRVs, including the Rotarix RV1 vaccine strain, and ARVs, we evaluated host susceptibility, virus production, and cellular responses of HIEs. HRVs infect at higher rates and grow to higher titers than do ARVs. HRVs infect differentiated enterocytes and enteroendocrine cells, and viroplasms and lipid droplets are induced. Heterogeneity in replication was seen in HIEs from different patients. HRV infection and RV enterotoxin treatment of HIEs caused physiological lumenal expansion detected by time-lapse microscopy, recapitulating one of the hallmarks of rotavirus-induced diarrhea. These results demonstrate that HIEs are a novel pathophysiological model that will allow the study of HRV biology, including host restriction, cell type restriction, and virus-induced fluid secretion. IMPORTANCE: Our research establishes HIEs as nontransformed cell culture models to understand human intestinal physiology and pathophysiology and the epithelial response, including host restriction of gastrointestinal infections such as HRV infection. HRVs remain a major worldwide cause of diarrhea-associated morbidity and mortality in children ≤5 years of age. Current in vitro models of rotavirus infection rely primarily on the use of animal rotaviruses because HRV growth is limited in most transformed cell lines and animal models. We demonstrate that HIEs are novel, cellularly diverse, and physiologically relevant epithelial cell cultures that recapitulate in vivo properties of HRV infection. HIEs will allow the study of HRV biology, including human host-pathogen and live, attenuated vaccine interactions; host and cell type restriction; virus-induced fluid secretion; cell-cell communication within the epithelium; and the epithelial response to infection in cultures from genetically diverse individuals. Finally, drug therapies to prevent/treat diarrheal disease can be tested in these physiologically active cultures.

Cognitive Load Reduces Perceived Linguistic Convergence Between Dyads.

Speech convergence is the tendency of talkers to become more similar to someone they are listening or talking to, whether that person is a conversational partner or merely a voice heard repeating words. To elucidate the nature of the mechanisms underlying convergence, this study uses different levels of task difficulty on speech convergence within dyads collaborating on a task. Dyad members had to build identical LEGO® constructions without being able to see each other's construction, and with each member having half of the instructions required to complete the construction. Three levels of task difficulty were created, with five dyads at each level (30 participants total). Task difficulty was also measured using completion time and error rate. Listeners who heard pairs of utterances from each dyad judged convergence to be occurring in the Easy condition and to a lesser extent in the Medium condition, but not in the Hard condition. Amplitude envelope acoustic similarity analyses of the same utterance pairs showed that convergence occurred in dyads with shorter completion times and lower error rates. Together, these results suggest that while speech convergence is a highly variable behavior, it may occur more in contexts of low cognitive load. The relevance of these results for the current automatic and socially-driven models of convergence is discussed.

Communication between healthcare providers and communicatively-vulnerable patients with associated health outcomes: A scoping review of knowledge syntheses.

OBJECTIVE: Summarize literature on provider-patient communication linked to health outcomes in communicatively-vulnerable patient populations. METHODS: Scoping review of reviews: systematically searched six databases. INCLUSION CRITERIA: systematic searches and syntheses of literature; one or more providers and communicatively-vulnerable patients; synchronous in-person communication; intermediate or health outcome linked to communication. RESULTS: The search yielded 14,615 citations; 47 reviews - with wide range of providers, communication vulnerabilities, communication practices, and health outcomes - met inclusion criteria. Methodology included qualitative, quantitative, and mixed approaches. Quality ranged from very low to high. Six categories of communication practices linked to health outcomes were identified: 1) motivation-based; 2) accommodation of language, culture, gender, sexual identity, and other concordance with the patient; 3) cultural adaptations of interventions; 4) use of interpreters; 5) other provider-patient communication practices; 6) patient communication practices. CONCLUSION: Communication practices were studied in a wide range of providers, with common themes regarding best practices. A unique finding is the role of the patient's communication practices. The specificity of communication practices studied is heterogeneous, with many reviews providing insufficient details. PRACTICE IMPLICATIONS: Motivation-based practices and culturally- and linguistically-appropriate care have impacts on patient outcomes across a range of settings with different professions and communicatively-vulnerable groups.

Host-derived CEACAM-laden vesicles engage enterotoxigenic E. coli for elimination and toxin neutralization.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of diarrheal illnesses annually ranging from mildly symptomatic cases to severe, life-threatening cholera-like diarrhea. Although ETEC are associated with long-term sequelae including malnutrition, the acute diarrheal illness is largely self-limited. Recent studies indicate that in addition to causing diarrhea, the ETEC heat-labile toxin (LT) modulates the expression of many genes in intestinal epithelia, including carcinoembryonic cell adhesion molecules (CEACAMs) which ETEC exploit as receptors, enabling toxin delivery. Here however, we demonstrate that LT also enhances the expression of CEACAMs on extracellular vesicles (EV) shed by intestinal epithelia and that CEACAM-laden EV increase in abundance during human infections, mitigate pathogen-host interactions, scavenge free ETEC toxins, and accelerate ETEC clearance from the gastrointestinal tract. Collectively, these findings indicate that CEACAMs play a multifaceted role in ETEC pathogen-host interactions, transiently favoring the pathogen, but ultimately contributing to innate responses that extinguish these common infections.

Intestinal epigenomic alterations are associated with a dysregulated nutrient absorption phenotype in obesity.

Obesity is an epidemic with myriad health effects, but little is understood regarding individual obese phenotypes and how they may respond to therapy. Epigenetic changes associated with obesity have been detected in blood, liver, pancreas, and adipose tissues. Previous work found that dietary glucose hyperabsorption occurs in some obese subjects, but detailed transcriptional or epigenomic features of the intestine associated with this phenotype are unknown. This study evaluated differentially expressed genes and relative chromatin accessibility in intestinal organoids established from donors classified as lean, obese, or obese hyperabsorptive by body mass index and glucose transport assays. Transcriptomic analysis indicated that obese hyperabsorptive subjects have significantly upregulated dietary nutrient absorption proteins and downregulated type I interferon targets. Chromatin accessibility and transcription factor footprinting suggested that enhanced binding of HNF4G promotes the obese hyperabsorption phenotype. Quantitative PCR assessment in a larger subject cohort suggested that intestinal epithelial expression of CUBN, GIP, and SLC2A5 have high correlation with hyperabsorption. The obese hyperabsorption phenotype is characterized by transcriptional changes that support increased nutrient uptake and may be driven by differentially accessible chromatin. Recognizing unique intestinal phenotypes in obesity provides new perspective in considering therapeutic targets and options to manage the disease.

Demonstration of starter unit interprotein transfer from a fatty acid synthase to a multidomain, nonreducing polyketide synthase.

The pathway for substrate transacylation between a fungal type I fatty acid synthase (FAS) and a nonreducing polyketide synthase (NR-PKS) was determined by in vitro reconstitution of dissected domains. System kinetics were influenced by domain dissections, and the FAS phosphopantetheinyl transferase (PPT) monodomain exhibited coenzyme A selectivity for the post-translational activation of the FAS acyl carrier protein (ACP).

"Just letting you know " Underestimating others' desire for constructive feedback.

People sometimes avoid giving feedback to others even when it would help fix others' problems. For example, only 2.6% of individuals in a pilot field study provided feedback to a survey administrator who had food or lipstick on their face. Five experiments (N = 1,984) identify a possible reason for the lack of feedback: People underestimate how much others want to receive constructive feedback. Initial experiments demonstrated this underestimation of others' desire for feedback in hypothetical scenarios (Experiment 1), recalled feedback experiences (Experiment 2), and real-time feedback among friends (Experiment 3). We further examine how people ascertain others' desire for feedback, testing how much they consider the potential consequences of feedback for themselves (e.g., discomfort giving feedback or harm to their relationship with the receiver) or the receiver (e.g., discomfort receiving feedback or value from feedback). While we found evidence that people consider both types of consequences, people particularly underestimated how much receivers value their feedback, a mechanism not extensively tested in prior research. Specifically, in Experiment 4, two interventions-making feedback-givers consider receivers' perspectives (enhancing consideration of receivers' consequences) or imagine someone else providing feedback (reducing consideration of givers' consequences)-both improved givers' recognition of others' desire for feedback compared to no intervention, but the perspective-taking intervention was most effective. Finally, Experiment 5 demonstrates the underestimation during a financially incentivized public-speaking contest and shows that giving less constructive feedback resulted in less improvement in feedback-receivers' performances. Overall, people consistently underestimate others' desire for feedback, with potentially negative consequences for feedback-receivers' outcomes. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Kindness in short supply: Evidence for inadequate prosocial input.

In everyday life, people often have opportunities to improve others' lives, whether offering well-intentioned advice or complimenting someone on a job well done. These are opportunities to provide "prosocial input" (information intended to benefit others), including feedback, advice, compliments, and expressions of gratitude. Despite widespread evidence that giving prosocial input can improve the well-being of both givers and recipients, people sometimes hesitate to offer their input. The current paper documents when and why people fail to give prosocial input, noting that potential givers overestimate the costs of doing so (e.g., making recipients uncomfortable) and underestimate the benefits (e.g., being helpful) for at least four psychological reasons. Unfortunately, the reluctance to give prosocial input results in a short supply of kindness.

Ulcerative Colitis: Novel Epithelial Insights Provided by Single Cell RNA Sequencing.

Ulcerative Colitis (UC) is a chronic inflammatory disease of the intestinal tract for which a definitive etiology is yet unknown. Both genetic and environmental factors have been implicated in the development of UC. Recently, single cell RNA sequencing (scRNA-seq) technology revealed cell subpopulations contributing to the pathogenesis of UC and brought new insight into the pathways that connect genome to pathology. This review describes key scRNA-seq findings in two major studies by Broad Institute and University of Oxford, investigating the transcriptomic landscape of epithelial cells in UC. We focus on five major findings: (1) the identification of BEST4 + cells, (2) colonic microfold (M) cells, (3) detailed comparison of the transcriptomes of goblet cells, and (4) colonocytes and (5) stem cells in health and disease. In analyzing the two studies, we identify the commonalities and differences in methodologies, results, and conclusions, offering possible explanations, and validated several cell cluster markers. In systematizing the results, we hope to offer a framework that the broad scientific GI community and GI clinicians can use to replicate or corroborate the extensive new findings that RNA-seq offers.

The role of CFA/I in adherence and toxin delivery by ETEC expressing multiple colonization factors in the human enteroid model.

Enterotoxigenic Escherichia coli (ETEC) is a primary causative agent of diarrhea in travelers and young children in low-to-middle-income countries (LMICs). ETEC adhere to intestinal epithelia via colonization factors (CFs) and secrete heat-stable toxin (ST) and/or heat-labile toxin (LT), causing dysregulated cellular ion transport and water secretion. ETEC isolates often harbor genes encoding more than one CF that are targets as vaccine antigens. CFA/I is a major CF that is associated with ETEC that causes moderate-to-severe diarrhea and plays an important role in pathogenesis. The Global Enteric Multicenter Study finding that 78% of CFA/I-expressing ETEC also encode the minor CF CS21 prompted investigation of the combined role of these two CFs. Western blots and electron microscopy demonstrated growth media-dependent and strain-dependent differences in CFA/I and CS21 expression. The critical role of CFA/I in adherence by ETEC strains expressing CFA/I and CS21 was demonstrated using the human enteroid model and a series of CFA/I- and CS21-specific mutants. Furthermore, only anti-CFA/I antibodies inhibited adherence by global ETEC isolates expressing CFA/I and CS21. Delivery of ST and resulting cGMP secretion was measured in supernatants from infected enteroid monolayers, and strain-specific ST delivery and time-dependent cGMP production was observed. Interestingly, cGMP levels were similar across wildtype and CF-deficient strains, reflecting a limitation of this static aerobic infection model. Despite adherence by ETEC and delivery of ST, the enteroid monolayer integrity was not disrupted, as shown by the lack of decrease in transepithelial electrical resistance and the lack of IL-8 cytokines produced during infection. Taken together, these data demonstrate that targeting CFA/I in global clinical CFA/I-CS21 strains is sufficient for adherence inhibition, supporting a vaccine strategy that focuses on blocking major CFs. In addition, the human enteroid model has significant utility for the study of ETEC pathogenesis and evaluation of vaccine-induced functional antibody responses.

Chronic Inflammation in Ulcerative Colitis Causes Long-Term Changes in Goblet Cell Function.

BACKGROUND & AIMS: One of the features of ulcerative colitis (UC) is a defect in the protective mucus layer. This has been attributed to a reduced number of goblet cells (GCs). However, it is not known whether abnormal GC mucus secretion also contributes to the reduced mucus layer. Our aims were to investigate whether GC secretion was abnormal in UC and exists as a long-term effect of chronic inflammation. METHODS: Colonoids were established from intestinal stem cells of healthy subjects (HS) and patients with UC. Colonoids were maintained as undifferentiated (UD) or induced to differentiate (DF) and studied as three-dimensional or monolayers on Transwell filters. Total RNA was extracted for quantitative real-time polymerase chain reaction analysis. Carbachol and prostaglandin E2 mediated mucin stimulation was examined by MUC2 IF/confocal microscopy and transmission electron microscopy. RESULTS: Colonoids from UC patients can be propagated over many passages; however, they exhibit a reduced rate of growth and transepithelial electrical resistance compared with HS. Differentiated UC colonoid monolayers form a thin and non-continuous mucus layer. UC colonoids have increased expression of secretory lineage markers ATOH1 and SPDEF, along with MUC2 positive GCs, but failed to secrete mucin in response to the cholinergic agonist carbachol and prostaglandin E2, which caused increased secretion in HS. Exposure to tumor necrosis factor α (5 days) reduced the number of GCs, with a greater percentage decrease in UC colonoids compared with HS. CONCLUSIONS: Chronic inflammation in UC causes long-term changes in GCs, leading to abnormal mucus secretion. This continued defect in GC mucus secretion may contribute to the recurrence in UC.

Mode of action and biosynthesis of the azabicycle-containing natural products azinomycin and ficellomycin.

Only a handful of aziridine-containing natural products have been identified out of the more than 100,000 natural products characterized to date. Among this class of compounds, only the azinomycins (azinomycin A and B) and ficellomycin contain an unusual 1-azabicyclo[3.1.0]hexane ring system, which has been reported to be the reason for theDNAcrosslinking abilities and cytotoxicity of these metabolites. Both families of natural products are produced by Streptomyces species, Streptomyces sahachiroi and Streptomyces ficellus, respectively. Up until recently, much of the work on these molecules has focused on the synthesis of these natural products or their corresponding analogs for in vitro investigations evaluating their DNA selectivity. While one of the most intriguing aspects of these natural products is their biosynthesis, progress made in this area was largely impeded by difficulties with obtaining a reliable culture method and securing a consistent source of these natural products. In this review, we will cover the discovery and biological activity of the azinomycins, their mode of action, related synthetic analogs and biosynthesis, and finish with a discussion on the less studied metabolite, ficellomycin.

Evaluation of a Live Attenuated S. sonnei Vaccine Strain in the Human Enteroid Model.

Shigella is a leading cause of bacillary dysentery worldwide, responsible for high death rates especially among children under five in low-middle income countries. Shigella sonnei prevails in high-income countries and is becoming prevalent in industrializing countries, where multi-drug resistant strains have emerged, as a significant public health concern. One strategy to combat drug resistance in S. sonnei is the development of effective vaccines. There is no licensed vaccine against Shigella, and development has been hindered by the lack of an effective small-animal model. In this work, we used human enteroids, for the first time, as a model system to evaluate a plasmid-stabilized S. sonnei live attenuated vaccine strain, CVD 1233-SP, and a multivalent derivative, CVD 1233-SP::CS2-CS3, which expresses antigens from enterotoxigenic Escherichia coli. The strains were also tested for immunogenicity and protective capacity in the guinea pig model, demonstrating their ability to elicit serum and mucosal antibody responses as well as protection against challenge with wild-type S. sonnei. These promising results highlight the utility of enteroids as an innovative preclinical model to evaluate Shigella vaccine candidates, constituting a significant advance for the development of preventative strategies against this important human pathogen.

Research in a time of enteroids and organoids: how the human gut model has transformed the study of enteric bacterial pathogens.

Enteric bacterial pathogens cause significant morbidity and mortality globally. Studies in tissue culture and animal models shaped our initial understanding of these host-pathogen interactions. However, intrinsic shortcomings in these models limit their application, especially in translational applications like drug screening and vaccine development. Human intestinal enteroid and organoid models overcome some limitations of existing models and advance the study of enteric pathogens. In this review, we detail the use of human enteroids and organoids to investigate the pathogenesis of invasive bacteria Shigella, Listeria, and Salmonella, and noninvasive bacteria pathogenic Escherichia coli, Clostridium difficile, and Vibrio cholerae. We highlight how these studies confirm previously identified mechanisms and, importantly, reveal novel ones. We also discuss the challenges for model advancement, including platform engineering to integrate environmental conditions, innate immune cells and the resident microbiome, and the potential for pre-clinical testing of recently developed antimicrobial drugs and vaccines.