Intestinal and systemic inflammation induced by symptomatic and asymptomatic enterotoxigenic E. coli infection and impact on intestinal colonization and ETEC specific immune responses in an experimental human challenge model

Benzoic acid as a dietary supplement mitigates inflammation and intestinal injury in acute enterotoxigenic Escherichia coli-infected mice without adverse effects in healthy mice

Benzoic acid is a naturally occurring compound found in fruits and is also commercially synthesized as an additive in the food, feed, and pharmaceutical industries. This study investigated the effects of benzoic acid as a dietary supplement on inflammation and intestinal injury in acute Escherichia coli (ETEC)-infected or healthy mice. Thirty-six BALB/c mice were divided into three groups, with 12 mice in each group for a 16-day feeding trial. In group 1, mice were fed a basal diet, six mice were sacrificed, and six mice were intraperitoneally injected with phosphate-buffered saline on day 15. Groups 2 and 3 were fed a basal diet and a diet containing 0.6% benzoic acid, respectively. Half of the mice in each group were sacrificed, while the others were intraperitoneally injected with ETEC on day 15. The results indicated that benzoic acid had no adverse effects on healthy mice regarding growth, organ indices, inflammation, intestinal injury parameters, and cecal short-chain fatty acid levels. Importantly, benzoic acid reduced inflammation in ETEC-infected mice, as evidenced by decreased serum IL-1β, TNF-α, and INF-γ levels, along with increased jejunal TLR-2 and MyD88 mRNA expression. Besides, benzoic acid mitigated intestinal injury in ETEC-infected mice by increasing the jejunal villus height (VH) and the ratio of VH to crypt depth, elevating jejunal Occludin mRNA levels, decreasing serum D-lactate and diamine oxidase levels, and increasing the cecal acetic acid level. 16s rRNA sequencing revealed that benzoic acid altered the β-diversity of ETEC-infected mice and increased the abundances of Erysipelotrichaceae, Faecalibaculum, and Turicibacter in their gut microbiota. Spearman correlation analysis further indicated that the protective effects of benzoic acid against ETEC infection were closely linked to specific gut microbiota, namely Erysipelotrichaceae, Faecalibaculum, Bifidobacterium, and Limosilactobacillus. Collectively, these findings suggest that benzoic acid could serve as a safe dietary supplement for healthy mice and may alleviate inflammation and intestinal injury in mice with acute ETEC infection.

Modulation of Macrophages TLR4-Mediated Transcriptional Response by Lacticaseibacillus rhamnosus CRL1505 and Lactiplantibacillus plantarum CRL1506

Lacticaseibacillus rhamnosus CRL1505 and Lactiplantibacillus plantarum CRL1506 increase the resistance of mice to Gram-negative pathogens infections. In this work, we advanced the characterization of the CRL1505 and CRL1506 immunomodulatory properties by evaluating their effect on the Toll-like receptor 4 (TLR4)-triggered immune response in macrophages. We performed experiments in murine RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS) to evaluate the transcriptomic changes induced by lactobacilli. These in vitro experiments were complemented with in vivo studies in mice to determine the effect of CRL1505 and CRL1506 strains on Peyer's patches and peritoneal macrophages. Microarray transcriptomic studies and qPCR confirmation showed that the CRL1505 and CRL1506 strains modulated the expression of inflammatory cytokines and chemokines as well as adhesion molecules in LPS-challenged RAW macrophages, making the effect of L. rhamnosus CRL1505 more remarkable. Lactobacilli also modulate regulatory factors in macrophages. L. plantarum CRL1506 increased il10 and socs2 while L. rhamnosus CRL1505 upregulated il27, socs1, and socs3 in RAW cells, indicating a strain-specific effect. However, in vivo, both strains induced similar effects. Peyer's patches and peritoneal macrophages from mice treated with lactobacilli produced higher levels of tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-6, and colony stimulating factor (CSF)-3 after LPS stimulation. This effect would allow improved protection against pathogens. In addition, both lactobacilli equally modulated socs1 and socs2 expressions and IL-10 and IL-27 production in Peyer's patches macrophages and socs3 and IL-10 in peritoneal cells. Furthermore, lactobacilli reduced the production of IL-1β, IL-12, CSF2, C-C motif chemokine ligand (CCL)-2, and CCL8 in LPS-challenged macrophages. This differential modulation of regulatory and inflammatory factors would allow minimal inflammatory-mediated tissue damage during the generation of the innate immune response. This work provides evidence that L. rhamnosus CRL1505 and L. plantarum CRL1506 modulate macrophages' TLR4-mediated immunotranscriptomic response, helping to improve protection against Gram-negative bacterial infections.

Bacillus safensis M01 reversed the inflammatory injury of mice jejunum caused by enterotoxigenic Escherichia coli K88

Enterotoxigenic Escherichia coli (ETEC) is a major pathogen causing neonatal diarrhea in livestock, with antibiotics commonly used for control. However, antibiotic overuse has led to issues such as residues and bacterial resistance, underscoring the need for alternative prevention strategies. This study investigated the potential of Bacillus safensis (B. safensis) M01, isolated from healthy porcine feces in Shandong, China, to prevent ETEC infections. M01 exhibited over 80% inhibition of ETEC in vitro and was selected for further analysis. Pre-treatment of IPEC-J2 cells with M01 significantly reduced ETEC-induced cellular damage, enhanced cell viability, and inhibited bacterial adhesion. It modulated inflammatory responses by down-regulating IL-1β and TNF-α while up-regulating IL-10. Additionally, M01 promoted the expression of tight junction proteins, including Claudin-1, Occludin, and ZO-1. In the C57BL/6 mouse model, pre-feeding with M01 for 14 days improved jejunal injury caused by ETEC, as indicated by increased villus height/crypt depth ratios. Similar to in vitro findings, M01 reduced IL-1β and TNF-α expression while enhancing tight junction protein levels. These results suggest that B. safensis M01 is a promising probiotic candidate for preventing ETEC infections in livestock, offering an effective alternative to antibiotics.

Rapid and sensitive whole cell E. coli detection using deep eutectic solvents/graphene oxide/gold nanoparticles field-effect transistor

Every year, millions of people suffer from gastrointestinal inflammation caused by E. coli. The increase of antibiotic-resistant strains and similar inflammatory and infectious syndromes symptoms have made rapid and sensitive diagnosis of this pathogen challenging. This study developed a Field-Effect Transistor based on deep eutectic solvents, graphene oxide, and gold nanoparticles (DES/GO/AuNPs-FET) to detect E. coli. Comparing the output current showed DES, which was a mixture of ethylene glycol and choline chloride, with ionic behavior, in addition to improving the electrical properties of GO, also led to the formation of AuNPs by self-assembly, which significantly increased the sensor's sensing performance. E. coli lipopolysaccharide aptamer immobilized on DES/GO/AuNPs-FET; capturing E. coli and changing the conformation caused changes in the charge carrier flow in the FET. This nanobiosensor detected E. coli in a completely selective manner in complex matrices like human blood serum. The excellent sensing performance of this nanobiosensor compared to other biosensors with a low detection limit (LOD = 3 CFU/ml), label-free, fast, and real-time detection showed that DES/GO/AuNPs-FET could be a reliable alternative to existing detection methods.

Oral delivery of electrohydrodynamically encapsulated Lactiplantibacillus plantarum CRD7 modulates gut health, antioxidant activity, and cytokines-related inflammation and immunity in mice

The current study aimed to evaluate the effects of L. plantarum CRD7 on performance and gut health biomarkers in a Swiss albino mouse model. The results showed that supplementation with non-encapsulated (NLP) and electrohydrodyanamically encapsulated L. plantarum CRD7 (ELP) for four weeks significantly increased (P < 0.05) body weight and weekly feed intake of mice. Specifically, these interventions strengthened the gut barrier functions, as evidenced by the increased expression of tight junction proteins (claudin-1, ZO-1, and occludin), inhibiting pro-inflammatory factors (TNF-α, MCP-1, and IL-6), and promoting short-chain fatty acid production. Histopathological examination revealed no probiotic-related adverse effects in liver and intestinal tissues. Furthermore, ELP and NLP possess the ability to regulate immunity and antioxidant capacity in mice. Notably, the supplementation of ELP modified the gut microbiota by promoting beneficial bacteria (Lactobacillus and Bifibacterium) and suppressing pathogenic bacteria (E. coli and C. perfringens), thereby restoring a balanced gut microbiota. Taken together, oral delivery of encapsulated L. plantarum CRD7 can modify the composition of the gut microbiota, fortify the intestinal barrier functions, maintain the gastrointestinal equilibrium, and augment the immune and antioxidant capacity. This comprehensive study provides valuable insights for the potential application of encapsulated probiotic products in food and feed formulations aimed at alleviating gut diseases.

Sublethal Effects of α-Cypermethrin on the Behavioral Asymmetries and Mating Success of Alphitobius diaperinus

Sublethal exposure to insecticides can adversely impact various biological and behavioral characteristics of insects. Although α-cypermethrin has been previously tested for its effects on control of Alphitobius diaperinus, there is no knowledge about the effect of this insecticide on its behavioral asymmetries and mating success. Μales at all exposures (control, LC10, and LC30), that first approached their mate, showed right-biased tendency (approached their mate from their right side) in mate recognition. Females, however, showed variation in this behavior between the three exposures. Right-biased tendency of males in all treatment scenarios led to a higher percentage of successful copulations compared to the three other directions. For males that first approached their mate, the insecticide did not affect their lateralization of the first approach but did affect their copulation success. The duration of copulation time was reduced after the exposure to the insecticide, with the longest duration noted in the control females (63.0 s) and the lowest in the α-cypermethrin LC30 females (46.9 s). Moreover, at the α-cypermethrin LC10 exposure, mate recognition time was reduced, as opposed to α-cypermethrin LC30 exposure where mate recognition time was increased. These results can be further utilized to uncover the behavioral impacts of insecticides, enhancing the effectiveness of pest management in warehouses and poultry production facilities.

Dietary Bacteriophage Administration Alleviates Enterotoxigenic Escherichia coli-Induced Diarrhea and Intestinal Impairment through Regulating Intestinal Inflammation and Gut Microbiota in a Newly Weaned Mouse Model

This study aimed to investigate the effects of dietary bacteriophage administration on diarrhea and intestinal impairment induced by enterotoxigenic Escherichia coli (ETEC) in a newly weaned mouse model. Forty-four newly weaned C57BL/6 mice were divided into four treatment groups, where they were provided either the control diet or the bacteriophage-supplemented diet, with or without ETEC infection. The results show that the bacteriophage administration resulted in increased body weight, decreased diarrhea score, and improved jejunal histopathology in ETEC-infected mice. The bacteriophage administration enhanced the intestinal barrier function of the ETEC-infected mice, as indicated by the reduced serum DAO level and the increased expression of Claudin-1, Occludin, and ZO-1 at both the mRNA and protein levels in the jejunum. Also, the bacteriophage administration resulted in a decrease in serum TNF-α and IL-1β levels, a down-regulation of TNF-α and IL-6 mRNA levels in the jejunum, and the inhibition of jejunal TLR-4/NF-κB pathway activation induced by ETEC infection. Moreover, the bacteriophage administration increased the levels of acetic acid, propionic acid, butyric acid, and total short-chain fatty acids in the caecum content. The bacteriophage administration increased the Shannon index, increased the abundance of Bacteroidota and Muribaculaceae, and decreased the abundance of Verrucomicrobiota and Akkermansiaceae in the colon contents of the ETEC-infected mice. Spearman's correlation analysis indicates that the protective effects of bacteriophage on ETEC-induced intestinal impairment, inflammation, and intestinal barrier function are associated with regulating the abundance of Bacteroidota and Muribaculaceae in the colon contents of mice. Collectively, bacteriophage administration alleviates ETEC-induced diarrhea and intestinal impairment through regulating intestinal inflammation and gut microbiota in newly weaned mice.

Bacillus halotolerans attenuates inflammation induced by enterotoxigenic Escherichia coli infection in vivo and in vitro based on its metabolite soyasaponin I regulating the p105-Tpl2-ERK pathway

Soyasaponins, recognized for their anti-inflammatory and antioxidant effects, have not yet been fully explored for their role in combating enterotoxigenic Escherichia coli (ETEC) infections. Recent findings identified them in small-molecule metabolites of Bacillus, suggesting their broader biological relevance. This research screened 88 strains of B. halotolerans, identifying the strain BH M20221856 as significantly inhibitory against ETEC growth in vitro. It also reduced cellular damage and inflammatory response in IPEC-J2 cells. The antimicrobial activity of BH M20221856 was attributed to its small-molecule metabolites rather than secretory proteins. A total of 69 small molecules were identified from the metabolites of BH M20221856 using liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS). Among these, soyasaponin I (SoSa I) represented the largest multiple change in the enrichment analysis of differential metabolites and exhibited potent anti-ETEC effects in vivo. It significantly reduced the bacterial load of E. coli in mouse intestines, decreased serum endotoxin, D-lactic acid, and oxidative stress levels and alleviated intestinal pathological damage and inflammation. SoSa I enhanced immune regulation by mediating the p105-Tpl2-ERK signaling pathway. Further evaluations using transepithelial electrical resistance (TEER) and cell permeability assays showed that SoSa I alleviated ETEC-induced damage to epithelial barrier function. These results suggest that BH M20221856 and SoSa I may serve as preventative biologics against ETEC infections, providing new insights for developing strategies to prevent and control this disease.

Dietary aflatoxins exposure, environmental enteropathy, and their relation with childhood stunting

Childhood stunting is a global phenomenon affecting more than 149 million children under the age of 5 worldwide. Exposure to aflatoxins (AFs) in utero, during breastfeeding, and consumption of contaminated food affect the gut microbiome, resulting in intestinal dysfunction and potentially contributing to stunting. This review explores the potential relationship between AF exposure, environmental enteropathy and childhood stunting. AFs bind to DNA, disrupt protein synthesis and elicit environmental enteropathy (EE). An EE alters the structure of intestinal epithelial cells, impairs nutrient uptake and leads to malabsorption. This article proposes possible intervention strategies for researchers and policymakers to reduce AF exposure, EE and childhood stunting, such as exposure reduction, the implementation of good agricultural practices, dietary diversification and improving environmental water sanitation and hygiene.

The 2022 Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference: Summary of breakout workshops

The global public health nonprofit organization PATH hosted the third Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC, from November 29 to December 1, 2022. This international gathering focused on cutting-edge research related to the development of vaccines against neglected diarrheal pathogens including Shigella, enterotoxigenic Escherichia coli (ETEC), Campylobacter, and non-typhoidal Salmonella. In addition to the conference's plenary content, the agenda featured ten breakout workshops on topics of importance to the enteric vaccine field. This unique aspect of VASE Conferences allows focused groups of attendees to engage in in-depth discussions on subjects of interest to the enteric vaccine development community. In 2022, the workshops covered a range of topics. Two focused on the public health value of enteric vaccines, with one examining how to translate evidence into policy and the other on the value proposition of potential combination vaccines against bacterial enteric pathogens. Two more workshops explored new tools for the development and evaluation of vaccines, with the first on integrating antigen/antibody technologies for mucosal vaccine and immunoprophylactic development, and the second on adjuvants specifically for Shigella vaccines for children in low- and middle-income countries. Another pair of workshops covered the status of vaccines against two emerging enteric pathogens, Campylobacter and invasive non-typhoidal Salmonella. The remaining four workshops examined the assessment of vaccine impact on acute and long-term morbidity. These included discussions on the nature and severity of intestinal inflammation; cellular immunity and immunological memory in ETEC and Shigella infections; clinical and microbiologic endpoints for Shigella vaccine efficacy studies in children; and intricacies of protective immunity to enteric pathogens. This article provides a brief summary of the presentations and discussions at each workshop in order to share these sessions with the broader enteric vaccine field.

Inflammation, the kynurenines, and mucosal injury during human experimental enterotoxigenic Escherichia coli infection

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children and travelers, especially in low- and middle-income countries. ETEC is a non-invasive gut pathogen colonizing the small intestinal wall before secreting diarrhea-inducing enterotoxins. We sought to investigate the impact of ETEC infection on local and systemic host defenses by examining plasma markers of inflammation and mucosal injury as well as kynurenine pathway metabolites. Plasma samples from 21 volunteers experimentally infected with ETEC were collected before and 1, 2, 3, and 7 days after ingesting the ETEC dose, and grouped based on the level of intestinal ETEC proliferation: 14 volunteers experienced substantial proliferation (SP) and 7 had low proliferation (LP). Plasma markers of inflammation, kynurenine pathway metabolites, and related cofactors (vitamins B2 and B6) were quantified using targeted mass spectrometry, whereas ELISA was used to quantify the mucosal injury markers, regenerating islet-derived protein 3A (Reg3a), and intestinal fatty acid-binding protein 2 (iFABP). We observed increased concentrations of plasma C-reactive protein (CRP), serum amyloid A (SAA), neopterin, kynurenine/tryptophan ratio (KTR), and Reg3a in the SP group following dose ingestion. Vitamin B6 forms, pyridoxal 5'-phosphate and pyridoxal, decreased over time in the SP group. CRP, SAA, and pyridoxic acid ratio correlated with ETEC proliferation levels. The changes following experimental ETEC infection indicate that ETEC, despite causing a non-invasive infection, induces systemic inflammation and mucosal injury when proliferating substantially, even in cases without diarrhea. It is conceivable that ETEC infections, especially when repeated, contribute to negative health impacts on children in ETEC endemic areas.

Schizochytrium sp. and lactoferrin supplementation alleviates Escherichia coli K99-induced diarrhea in preweaning dairy calves

Calf diarrhea, a common disease mainly induced by Escherichia coli infection, is one of the main reasons for nonpredator losses. Hence, an effective nonantibacterial approach to prevent calf diarrhea has become an emerging requirement. This study evaluated the microalgae Schizochytrium sp. (SZ) and lactoferrin (LF) as a nutrient intervention approach against E. coli O101:K99-induced preweaning calve diarrhea. Fifty 1-d-old male Holstein calves were randomly divided into 5 groups (n = 10): (1) control, (2) blank (no supplement or challenge), (3) 1 g/d LF, (4) 20 g/d SZ, or (5) 1 g/d LF plus 20 g/d SZ (LFSZ). The experimental period lasted 14 d. On the morning of d 7, calves were challenged with 1 × 1011 cfu of E. coli O101:K99, and rectum feces were collected on 3, 12, 24, and 168 h postchallenge for the control, LF, SZ, and LFSZ groups. The rectal feces of the blank group were collected on d 14. Data were analyzed using the mixed procedure of SAS (version 9.4; SAS Institute Inc.). The E. coli K99 challenge decreased the average daily gain (ADG) and increased feed-to-gain ratio (F:G) and diarrhea frequency (control vs. blank). Compared with the control group, the LFSZ group had a higher ADG and lower F:G, and the LFSZ and SZ groups had lower diarrhea frequency compared with the control group. In addition, the LFSZ and SZ groups have no differences in diarrhea frequency compared with the blank group. Compared with the control group, the blank group had lower serum nitric oxide (NO), endothelin-1, d-lactic acid (D-LA), and lipopolysaccharide (LPS) concentrations, as well as serum IgG, IL-1β, IL-6, IL-10, and TNF-α levels on d 7 and 14. On d 7, compared with the control group, all treatment groups had lower serum NO level, the SZ group had a lower serum D-LA concentration, and the LF and LFSZ groups had lower serum LPS concentration. On d 14, compared with the control group, the fecal microbiota of the blank group had lower Shannon, Simpson, Chao1, and ACE indexes, the LFSZ group had lower Shannon and Simpson indexes, the SZ and LFSZ groups had a higher Chao1 index, and all treatment groups had a higher ACE index. In fecal microbiota, Bifidobacterium and Actinobacteria were negatively associated with IL-10 and d-lactate, while Akkermansia was negatively associated with endothelin-1 and positively correlated with LPS, fecal scores, and d-lactate levels. Our results indicated that LF and SZ supplements could alleviate E. coli O101:K99-induced calf diarrhea individually or in combination. Supplementing 1 g/d LF and 20 g/d SZ could be a potential nutrient intervention approach to prevent bacterial diarrhea in calves.

Sargramostim for Prophylactic Management of Gastrointestinal Immune-Related Adverse Events of Immune Checkpoint Inhibitor Therapy for Cancer

Immune checkpoint inhibitor (ICI) therapy improves outcomes in several cancers. Unfortunately, many patients experience grade 3-4 treatment-related adverse events, including gastrointestinal (GI) toxicities which are common. These GI immune-related adverse events (irAEs) induced by ICIs present significant clinical challenges, require prompt intervention, and result in treatment delays or discontinuations. The treatment for these potentially severe and even fatal GI irAEs which include enterocolitis, severe diarrhea, and hepatitis may interfere with the anti-cancer approach. Sargramostim (glycosylated, yeast-derived, recombinant human GM-CSF) is an agent that has been used in clinical practice for more than 30 years with a well-recognized safety profile and has been studied in many therapeutic areas. The mechanism of action of sargramostim may treat moderate-to-severe GI irAEs without impairing the anti-cancer therapy. Some early data also suggest a potential survival benefit. Through the differentiation/maturation of monocytes, macrophages, and neutrophils and induction of anti-inflammatory T cell responses, GM-CSF aids in GI homeostasis, mucosal healing, and mucosal immunity. GM-CSF knockout mice are susceptible to severe colitis which was prevented with murine GM-CSF administration. For some patients with GI mucosa and immune cell function impairment, e.g., Crohn's disease, sargramostim reduces disease severity. In a prospective, randomized study (ECOG 1608), advanced melanoma patients had a reduction in grade 3-5 GI irAEs and less frequent colonic perforation in the sargramostim plus ipilimumab arm compared to ipilimumab alone. Sargramostim continues to be studied with ICIs for the prophylactic management of irAEs while also potentially providing a survival benefit.

Secrets and lies of host-microbial interactions: MHC restriction and trans-regulation of T cell trafficking conceal the role of microbial agents on the edge between health and multifactorial/complex diseases

Here we critically discuss data supporting the view that microbial agents (pathogens, pathobionts or commensals alike) play a relevant role in the pathogenesis of multifactorial diseases, but their role is concealed by the rules presiding over T cell antigen recognition and trafficking. These rules make it difficult to associate univocally infectious agents to diseases' pathogenesis using the paradigm developed for canonical infectious diseases. (Cross-)recognition of a variable repertoire of epitopes leads to the possibility that distinct infectious agents can determine the same disease(s). There can be the need for sequential infection/colonization by two or more microorganisms to develop a given disease. Altered spreading of infectious agents can determine an unwanted activation of T cells towards a pro-inflammatory and trafficking phenotype, due to differences in the local microenvironment. Finally, trans-regulation of T cell trafficking allows infectious agents unrelated to the specificity of T cell to modify their homing to target organs, thereby driving flares of disease. The relevant role of microbial agents in largely prevalent diseases provides a conceptual basis for the evaluation of more specific therapeutic approaches, targeted to prevent (vaccine) or cure (antibiotics and/or Biologic Response Modifiers) multifactorial diseases.

The Controlled Human Infection Model for Enterotoxigenic Escherichia coli

The controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC) has been instrumental in defining ETEC as a causative agent of acute watery diarrhea, providing insights into disease pathogenesis and resistance to illness, and enabling preliminary efficacy evaluations for numerous products including vaccines, immunoprophylactics, and drugs. Over a dozen strains have been evaluated to date, with a spectrum of clinical signs and symptoms that appear to replicate the clinical illness seen with naturally occurring ETEC. Recent advancements in the ETEC CHIM have enhanced the characterization of clinical, immunological, and microbiological outcomes. It is anticipated that omics-based technologies applied to ETEC CHIMs will continue to broaden our understanding of host-pathogen interactions and facilitate the development of primary and secondary prevention strategies.

Protective effect of Limosilactobacillus reuteri-fermented yogurt on mouse intestinal barrier injury induced by enterotoxigenic Escherichia coli

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) is a pathogen that causes traveler's diarrhea, for which an effective vaccine is lacking. Previous studies showed that Limosilactobacillus reuteri could inhibit E. coli, effectively increase the expression of its tight junction protein, and reduce the adhesion of ETEC to the intestinal epithelial Caco-2 cell line. In this study, three kinds of yogurt with different starter cultures were first prepared: Lm. reuteri yogurt (fermented by Lm. reuteri alone), traditional yogurt (fermented by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus at a ratio of 1:1) and mixed yogurt (fermented by Lm. reuteri, S. thermophilus and L. delbrueckii subsp. bulgaricus at a ratio of 1:1:1). The physiological properties, oxidative stress, intestinal barrier function, tight junction protein, pathological conditions and intestinal microbiota composition were investigated.

RESULTS

The data showed that Lm. reuteri-fermented yogurt pregavage could effectively alleviate the intestinal barrier impairment caused by ETEC in mice. It alleviated intestinal villus shortening and inflammatory cell infiltration, decreased plasma diamine oxidase concentration and increased claudin-1 and occludin expression in the jejunum of ETEC-infected mice. In addition, Lm. reuteri-fermented yogurt significantly reduced the ETEC load in fecal samples, reversed the increase in Pseudomonadota abundance and decreased Bacteroidota abundance caused by ETEC infection. Furthermore, the composition of the intestinal microbiota could maintain a stable state similar to that in healthy mice.

CONCLUSION

These findings indicate that Lm. reuteri-fermented yogurt could alleviate intestinal barrier damage, inhibit ETEC growth and maintain the stability of the intestinal microbiota during ETEC infection. © 2023 Society of Chemical Industry.

Characterization of the internal working-life exposome using minimally and non-invasive sampling methods - a narrative review

During recent years, we are moving away from the 'one exposure, one disease'-approach in occupational settings and towards a more comprehensive approach, taking into account the totality of exposures during a life course by using an exposome approach. Taking an exposome approach however is accompanied by many challenges, one of which, for example, relates to the collection of biological samples. Methods used for sample collection in occupational exposome studies should ideally be minimally invasive, while at the same time sensitive, and enable meaningful repeated sampling in a large population and over a longer time period. This might be hampered in specific situations e.g., people working in remote areas, during pandemics or with flexible work hours. In these situations, using self-sampling techniques might offer a solution. Therefore, our aim was to identify existing self-sampling techniques and to evaluate the applicability of these techniques in an occupational exposome context by conducting a literature review. We here present an overview of current self-sampling methodologies used to characterize the internal exposome. In addition, the use of different biological matrices was evaluated and subdivided based on their level of invasiveness and applicability in an occupational exposome context. In conclusion, this review and the overview of self-sampling techniques presented herein can serve as a guide in the design of future (occupational) exposome studies while circumventing sample collection challenges associated with exposome studies.

Vaccine value profile for enterotoxigenic Escherichia coli (ETEC)

Enterotoxigenic Escherichia coli (ETEC) is one of the leading bacterial causes of diarrhoea, especially among children in low-resource settings, and travellers and military personnel from high-income countries. WHO's primary strategic goal for ETEC vaccine development is to develop a safe, effective, and affordable ETEC vaccine that reduces mortality and morbidity due to moderate-to-severe diarrhoeal disease in infants and children under 5 years of age in LMICs, as well as the long-term negative health impact on infant physical and cognitive development resulting from infection with this enteric pathogen. An effective ETEC vaccine will also likely reduce the need for antibiotic treatment and help limit the further emergence of antimicrobial resistance bacterial pathogens. The lead ETEC vaccine candidate, ETVAX, has shown field efficacy in travellers and has moved into field efficacy testing in LMIC infants and children. A Phase 3 efficacy study in LMIC infants is projected to start in 2024 and plans for a Phase 3 trial in travellers are under discussion with the U.S. FDA. Licensing for both travel and LMIC indications is projected to be feasible in the next 5-8 years. Given increasing recognition of its negative impact on child health and development in LMICs and predominance as the leading etiology of travellers' diarrhoea (TD), a standalone vaccine for ETEC is more cost-effective than vaccines targeting other TD pathogens, and a viable commercial market also exists. In contrast, combination of an ETEC vaccine with other vaccines for childhood pathogens in LMICs would maximize protection in a more cost-effective manner than a series of stand-alone vaccines. This 'Vaccine Value Profile' (VVP) for ETEC is intended to provide a high-level, holistic assessment of available data to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations. All contributors have extensive expertise on various elements of the ETEC VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.

Efficacy of an Enterotoxigenic Escherichia coli (ETEC) Vaccine on the Incidence and Severity of Traveler's Diarrhea (TD): Evaluation of Alternative Endpoints and a TD Severity Score

The efficacy of an Oral Whole Cell ETEC Vaccine (OEV) against Travelers' Diarrhea (TD) was reexamined using novel outcome and immunologic measures. More specifically, a recently developed disease severity score and alternative clinical endpoints were evaluated as part of an initial validation effort to access the efficacy of a vaccine intervention for the first time in travelers to an ETEC endemic area. A randomized, double-blind, placebo-controlled trial followed travelers to Guatemala or Mexico up to 28 days after arrival in the country following vaccination (two doses two weeks apart) with an ETEC vaccine. Fecal samples were collected upon arrival, departure, and during TD for pathogen identification. Serum was collected in a subset of subjects to determine IgA cholera toxin B subunit (CTB) antibody titers upon their arrival in the country. The ETEC vaccine's efficacy, utilizing a TD severity score and other alternative endpoints, including the relationship between antibody levels and TD risk, was assessed and compared to the per-protocol primary efficacy endpoint. A total of 1435 subjects completed 7-28 days of follow-up and had available data. Vaccine efficacy was higher against more severe (≥5 unformed stools/24 h) ETEC-attributable TD and when accounting for immunologic take (PE ≥ 50%; p < 0.05). The vaccine protected against less severe (3 and 4 unformed stools/24 h) ETEC-attributable TD when accounting for symptom severity or change in activity (PE = 76.3%, p = 0.01). Immunologic take of the vaccine was associated with a reduced risk of infection with ETEC and other enteric pathogens, and with lower TD severity. Clear efficacy was observed among vaccinees with a TD score of ≥4 or ≥5, regardless of immunologic take (PE = 72.0% and 79.0%, respectively, p ≤ 0.03). The vaccine reduced the incidence and severity of ETEC, and this warrants accelerated evaluation of the improved formulation (designated ETVAX), currently undergoing advanced field testing. Subjects with serum IgA titers to CTB had a lower risk of infection with ETEC and Campylobacter jejuni/coli. Furthermore, the TD severity score provided a more robust descriptor of disease severity and should be included as an endpoint in future studies.

T helper cell responses in adult diarrheal patients following natural infection with enterotoxigenic Escherichia coli are primarily of the Th17 type

Background

Infection with enterotoxigenic Escherichia coli (ETEC) gives rise to IgA antibodies against both the heat labile toxin (LT) and colonization factors (CFs), which are considered to synergistically protect against ETEC diarrhea. Since the development of ETEC-specific long lived plasma cells and memory B cells is likely to be dependent on T helper (Th) cells, we investigated if natural ETEC diarrhea elicits ETEC-specific Th cells and their relation to IgA responses.

Methods

Th cell subsets were analyzed in adult Bangladeshi patients hospitalized due to ETEC diarrhea by flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) isolated from blood collected day 2, 7, 30 and 90 after hospitalization as well as in healthy controls. The LT- and CF-specific Th responses were determined by analysis of IL-17A and IFN-γ in antigen stimulated PBMC cultures using ELISA. ETEC-specific IgA secreted by circulating antibody secreting cells (plasmablasts) were analyzed by using the antibodies in lymphocyte supernatants (ALS) ELISA-based method and plasma IgA was also measured by ELISA.

Results

ETEC patients mounted significant ALS and plasma IgA responses against LTB and CFs on day 7 after hospitalization. ETEC patients had significantly elevated proportions of memory Th cells with a Th17 phenotype (CCR6+CXCR3-) in blood compared to controls, while frequencies of Th1 (CCR6-CXCR3+) or Th2 (CCR6-CXCR3-) cells were not increased. Antigen stimulation of PBMCs revealed IL-17A responses to LT, most clearly observed after stimulation with double mutant heat labile toxin (dmLT), but also with LT B subunit (LTB), and to CS6 in samples from patients with LT+ or CS6+ ETEC bacteria. Some individuals also mounted IFN-γ responses to dmLT and LTB. Levels of LTB specific IgA antibodies in ALS, but not plasma samples correlated with both IL-17A (r=0.5, p=0.02) and IFN-γ (r=0.6, p=0.01) responses to dmLT.

Conclusions

Our results show that ETEC diarrhea induces T cell responses, which are predominantly of the Th17 type. The correlations between IL-17A and IFN-g and intestine-derived plasmablast responses support that Th responses may contribute to the development of protective IgA responses against ETEC infection. These observations provide important insights into T cell responses that need to be considered in the evaluation of advanced ETEC vaccine candidates.

Shigella and childhood stunting: Evidence, gaps, and future research directions

Early childhood growth deficits have been shown to have lifelong health and economic impacts, yet their connection to one of their underlying causes, diarrheal diseases, has remained difficult to characterize. Identifying the processes and mechanisms that underlie this link has remained a challenge due to the complexity of the relationship and limitations in access to more advanced laboratory methods. In recent years, however, several large-scale, multisite studies have extensively investigated and reported the prevalence, etiology, and impacts of diarrheal diseases in children under 5 years (CU5) in low- to middle-income countries (LMICs). These studies, in combination with several single-site studies, have applied more advanced laboratory methods to uncover the etiology, true prevalence, infection mechanisms, and inflammation biomarkers of diarrheal disease. Of the multiple pathogens that have been shown to be strongly associated with diarrheal disease in CU5, Shigella is one of the more prevalent and impactful of these pathogens. In this narrative review, we highlight key insights from these studies and identify knowledge gaps and directions for future research. According to these studies, Shigella is most commonly detected in toddlers and young children; however, it can cause more severe disease and has a greater impact on linear growth for infants. Shigella often has a stronger relationship to linear growth faltering (LGF) than other enteropathogens, with higher Shigella loads resulting in greater growth deficits. Future studies should employ more Shigella-specific molecular assays and identify diarrheal etiologies using standardized diagnostics to improve child anthropometric and Shigella surveillance. Also, they should focus on uncovering the mechanisms of the relationship underlying Shigella and growth faltering to better characterize the role of asymptomatic infections and intestinal inflammation in this relationship.

Heat-Labile Enterotoxin Decreases Macrophage Phagocytosis of Enterotoxigenic Escherichia coli

Enterotoxigenic E. coli (ETEC) are endemic in low-resource settings and cause robust secretory diarrheal disease in children less than five years of age. ETEC cause secretory diarrhea by producing the heat-stable (ST) and/or heat-labile (LT) enterotoxins. Recent studies have shown that ETEC can be carried asymptomatically in children and adults, but how ETEC subvert mucosal immunity to establish intestinal residency remains unclear. Macrophages are innate immune cells that can be exploited by enteric pathogens to evade mucosal immunity, so we interrogated the ability of ETEC and other E. coli pathovars to survive within macrophages. Using gentamicin protection assays, we show that ETEC H10407 is phagocytosed more readily than other ETEC and non-ETEC isolates. Furthermore, we demonstrate that ETEC H10407, at high bacterial burdens, causes nitrite accumulation in macrophages, which is indicative of a proinflammatory macrophage nitric oxide killing response. However, at low bacterial burdens, ETEC H10407 remains viable within macrophages for an extended period without nitrite accumulation. We demonstrate that LT, but not ST, intoxication decreases the number of ETEC phagocytosed by macrophages. Furthermore, we now show that macrophages exposed simultaneously to LPS and LT produce IL-33, which is a cytokine implicated in promoting macrophage alternative activation, iron recycling, and intestinal repair. Lastly, iron restriction using deferoxamine induces IL-33 receptor (IL-33R) expression and allows ETEC to escape macrophages. Altogether, these data demonstrate that LT provides ETEC with the ability to decrease the perceived ETEC burden and suppresses the initiation of inflammation. Furthermore, these data suggest that host IL-33/IL-33R signaling may augment pathways that promote iron restriction to facilitate ETEC escape from macrophages. These data could help explain novel mechanisms of immune subversion that may contribute to asymptomatic ETEC carriage.

Heat-Stable Enterotoxin Secretions Assessed via ICP-MS Reveal Iron-Mediated Regulation of Virulence in CFA/I- and CS6-Expressing ETEC Isolates

Enterotoxigenic Escherichia coli (ETEC) are a significant cause of childhood diarrhea in low-resource settings. ETEC are defined by the production of heat-stable enterotoxin (ST) and/or heat-labile enterotoxin (LT), which alter intracellular cyclic nucleotide signaling and cause the secretion of water and electrolytes into the intestinal lumen. ETEC take cues from chemicals (e.g., glycans, bile salts, and solutes) that may be liberated following enterotoxin activity to recognize entrance into the host. ETEC then alter the expression of surface adhesins called colonization factors (CFs) to attach to the intestinal epithelium, proliferate, and cause disease. Here, we used an in vivo model of oral ST intoxication to determine its impact on luminal ion concentrations via ICP-MS. We also used functional assays, including Western blots, qPCR, and toxin activity assays, to assess the impact of luminal ion flux on CF and toxin expression. Finally, we assessed ETEC strains with CFs CFA/I or CS6 in a streptomycin mouse model of ETEC colonization. ST causes rapid and significant increases in luminal chloride but significant decreases in luminal magnesium and iron. We confirmed that increased sodium chloride suppresses CFA/I production in ETEC H10407 but does not affect CS6 production in ETEC 214-4. CFA/I production in ETEC H10407 is increased when magnesium becomes limiting, although it does not affect CS6 production in ETEC 214-4. Iron restriction via deferoxamine induces CFA/I expression in ETEC H10407 but not CS6 expression in ETEC 214-4. We demonstrate that ST production is suppressed via iron restriction in H10407, 214-4, and over 50 other ETEC clinical isolates. Lastly, we demonstrate that the iron restriction of mice using oral deferoxamine pre-treatment extends the duration of ETEC H10407 (CFA/I+) fecal shedding while accelerating ETEC 214-4 (CS6+) fecal shedding. Combined, these data suggest that enterotoxins modulate luminal ion flux to influence ETEC virulence including toxin and CF production.

Protocatechuic acid and quercetin attenuate ETEC-caused IPEC-1 cell inflammation and injury associated with inhibition of necroptosis and pyroptosis signaling pathways

BACKGROUND

Necroptosis and pyroptosis are newly identified forms of programmed cell death, which play a vital role in development of many gastrointestinal disorders. Although plant polyphenols have been reported to protect intestinal health, it is still unclear whether there is a beneficial role of plant polyphenols in modulating necroptosis and pyroptosis in intestinal porcine epithelial cell line (IPEC-1) infected with enterotoxigenic Escherichia coli (ETEC) K88. This research was conducted to explore whether plant polyphenols including protocatechuic acid (PCA) and quercetin (Que), attenuated inflammation and injury of IPEC-1 caused by ETEC K88 through regulating necroptosis and pyroptosis signaling pathways.

METHODS

IPEC-1 cells were treated with PCA (40 μmol/L) or Que (10 μmol/L) in the presence or absence of ETEC K88.

RESULTS

PCA and Que decreased ETEC K88 adhesion and endotoxin level (P < 0.05) in cell supernatant. PCA and Que increased cell number (P < 0.001) and decreased lactate dehydrogenases (LDH) activity (P < 0.05) in cell supernatant after ETEC infection. PCA and Que improved transepithelial electrical resistance (TEER) (P < 0.001) and reduced fluorescein isothiocyanate-labeled dextran (FD4) flux (P < 0.001), and enhanced membrane protein abundance of occludin, claudin-1 and ZO-1 (P < 0.05), and rescued distribution of these tight junction proteins (P < 0.05) after ETEC infection. PCA and Que also declined cell necrosis ratio (P < 0.05). PCA and Que reduced mRNA abundance and concentration of tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-8 (P < 0.001), and down-regulated gene expression of toll-like receptors 4 (TLR4) and its downstream signals (P < 0.001) after ETEC infection. PCA and Que down-regulated protein abundance of total receptor interacting protein kinase 1 (t-RIP1), phosphorylated-RIP1 (p-RIP1), p-RIP1/t-RIP1, t-RIP3, p-RIP3, mixed lineage kinase domain-like protein (MLKL), p-MLKL, dynamin- related protein 1 (DRP1), phosphoglycerate mutase 5 (PGAM5) and high mobility group box 1 (HMGB1) (P < 0.05) after ETEC infection. Moreover, PCA and Que reduced protein abundance of nod-like receptor protein 3 (NLRP3), nod-like receptors family CARD domain-containing protein 4 (NLRC4), apoptosis-associated speck-like protein containing a CARD (ASC), gasdermin D (GSDMD) and caspase-1 (P < 0.05) after ETEC infection.

CONCLUSIONS

In general, our data suggest that PCA and Que are capable of attenuating ETEC-caused intestinal inflammation and damage via inhibiting necroptosis and pyroptosis signaling pathways.

Lactiplantibacillus plantarum Strains Modulate Intestinal Innate Immune Response and Increase Resistance to Enterotoxigenic Escherichia coli Infection

Currently, probiotic bacteria with not transferable antibiotic resistance represent a sustainable strategy for the treatment and prevention of enterotoxigenic Escherichia coli (ETEC) in farm animals. Lactiplantibacillus plantarum is among the most versatile species used in the food industry, either as starter cultures or probiotics. In the present work, the immunobiotic potential of L. plantarum CRL681 and CRL1506 was studied to evaluate their capability to improve the resistance to ETEC infection. In vitro studies using porcine intestinal epithelial (PIE) cells and in vivo experiments in mice were undertaken. Expression analysis indicated that both strains were able to trigger IL-6 and IL-8 expression in PIE cells in steady-state conditions. Furthermore, mice orally treated with these strains had significantly improved levels of IFN-γ and TNF-α in the intestine as well as enhanced activity of peritoneal macrophages. The ability of CRL681 and CRL1506 to beneficially modulate intestinal immunity was further evidenced in ETEC-challenge experiments. In vitro, the CRL1506 and CRL681 strains modulated the expression of inflammatory cytokines (IL-6) and chemokines (IL-8, CCL2, CXCL5 and CXCL9) in ETEC-stimulated PIE cells. In vivo experiments demonstrated the ability of both strains to beneficially regulate the immune response against this pathogen. Moreover, the oral treatment of mice with lactic acid bacteria (LAB) strains significantly reduced ETEC counts in jejunum and ileum and prevented the spread of the pathogen to the spleen and liver. Additionally, LAB treated-mice had improved levels of intestinal IL-10 both at steady state and after the challenge with ETEC. The protective effect against ETEC infection was not observed for the non-immunomodulatory TL2677 strain. Furthermore, the study showed that L. plantarum CRL1506 was more efficient than the CRL681 strain to modulate mucosal immunity highlighting the strain specific character of this probiotic activity. Our results suggest that the improved intestinal epithelial defenses and innate immunity induced by L. plantarum CRL1506 and CRL681 would increase the clearance of ETEC and at the same time, protect the host against detrimental inflammation. These constitute valuable features for future probiotic products able to improve the resistance to ETEC infection.

Controlled Human Infection Models To Accelerate Vaccine Development

The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.

Controlled human infectious models, a path forward in uncovering immunological correlates of protection: Lessons from enteric fevers studies

Enteric infectious diseases account for more than a billion disease episodes yearly worldwide resulting in approximately 2 million deaths, with children under 5 years old and the elderly being disproportionally affected. Enteric pathogens comprise viruses, parasites, and bacteria; the latter including pathogens such as Salmonella [typhoidal (TS) and non-typhoidal (nTS)], cholera, Shigella and multiple pathotypes of Escherichia coli (E. coli). In addition, multi-drug resistant and extensively drug-resistant (XDR) strains (e.g., S. Typhi H58 strain) of enteric bacteria are emerging; thus, renewed efforts to tackle enteric diseases are required. Many of these entero-pathogens could be controlled by oral or parenteral vaccines; however, development of new, effective vaccines has been hampered by lack of known immunological correlates of protection (CoP) and limited knowledge of the factors contributing to protective responses. To fully comprehend the human response to enteric infections, an invaluable tool that has recently re-emerged is the use of controlled human infection models (CHIMs) in which participants are challenged with virulent wild-type (wt) organisms. CHIMs have the potential to uncover immune mechanisms and identify CoP to enteric pathogens, as well as to evaluate the efficacy of therapeutics and vaccines in humans. CHIMs have been used to provide invaluable insights in the pathogenesis, host-pathogen interaction and evaluation of vaccines. Recently, several Oxford typhoid CHIM studies have been performed to assess the role of multiple cell types (B cells, CD8+ T, Tregs, MAIT, Monocytes and DC) during S. Typhi infection. One of the key messages that emerged from these studies is that baseline antigen-specific responses are important in that they can correlate with clinical outcomes. Additionally, volunteers who develop typhoid disease (TD) exhibit higher levels and more activated cell types (e.g., DC and monocytes) which are nevertheless defective in discrete signaling pathways. Future critical aspects of this research will involve the study of immune responses to enteric infections at the site of entry, i.e., the intestinal mucosa. This review will describe our current knowledge of immunity to enteric fevers caused byS. Typhi and S. Paratyphi A, with emphasis on the contributions of CHIMs to uncover the complex immunological responses to these organisms and provide insights into the determinants of protective immunity.

Exposure to Veterinary Antibiotics via Food Chain Disrupts Gut Microbiota and Drives Increased Escherichia coli Virulence and Drug Resistance in Young Adults

Exposure to veterinary antibiotics (VAs) and preferred as veterinary antibiotics (PVAs) via the food chain is unavoidable for their extensive use not only for treating bacterial infections, but also for use as growth promoters in livestock and aquaculture. One of the consequences is the disturbance of gut microbiota. However, its impact on the virulence and drug resistance of opportunistic pathogens is still unclear. In this study, a total of 26 antibiotics were detected in the urine of 300 young undergraduates in Anhui Province. We found that excessive intake of milk was positively correlated to high levels of VAs and PVAs. It led to the dysbiosis of gut microbiota characterized by high abundance of Bacteroidetes and Proteobacteria. The increase in Proteobacteria was mainly due to a single operational taxonomic unit (OTU) of Escherichia coli (E. coli). We isolated several E. coli strains from participants and compared their drug resistance and virulence using PCR assay and virulence-related assays. We observed that exposure to high levels of VAs and PVAs induced more resistant genes and drove E. coli strain to become more virulent. At last, we conducted transcriptome analysis to investigate the molecular mechanism of virulent and drug-resistant regulators in the highly virulent E. coli strain. We noted that there were multiple pathways involved in the drug resistance and virulence of the highly virulent strain. Our results demonstrated that participants with high-level VAs and PVAs exposure have a disrupted gut microbiota following the appearance of highly drug-resistant and virulent E. coli and, therefore may be at elevated risk for long-term health complications.

Phylogrouping and characterization of Escherichia coli isolated from colonic biopsies and fecal samples of patients with flare of inflammatory bowel disease in Iran

BACKGROUND

Although the etiopathogenesis of inflammatory bowel disease (IBD) is still poorly understood, Escherichia coli has been described as a potential causative microorganism in IBD pathogenesis and also disease progression, offering a potential therapeutic target for disease management. Therefore, we conducted this study to investigate the pathotypes, phylogenetic groups, and antimicrobial resistance of E. coli isolates from patients with IBD in Iran.

METHODS

Fecal and biopsy colonic samples were collected from IBD patients experiencing flare-up episodes referred to Taleghani hospital in Tehran, Iran, between August 2020 and January 2021. Identification of E. coli strains was performed based on biochemical and molecular methods. Antibiotic susceptibility testing was performed as recommended by the Clinical and Laboratory Standards Institute. Phylogrouping and pathotyping of each isolate were carried out using polymerase chain reaction (PCR) and multilocus sequence typing (MLST) assays.

RESULTS

A total of 132 non-duplicate E. coli strains were isolated from 113 IBD patients, including 96 ulcerative colitis (UC), and 17 Crohn's disease (CD) patients. In our study, 55% of CD-related E. coli and 70.5% of UC-related isolates were non-susceptible to at least three or more unique antimicrobial classes, and were considered as multidrug-resistant (MDR) strains. E. coli strains exhibited a high level of resistance to cefazolin, ampicillin, tetracycline, ceftazidime, ciprofloxacin, and cefotaxime. Enterotoxigenic E. coli (ETEC) and diffusely adherent E. coli (DAEC) were the most prevalent pathotypes, and groups B2 and D were the predominant phylogroups.

CONCLUSION

In the present study, we found that E. coli strains that colonize the gut of Iranian patients with IBD most frequently belonged to phylogenetic groups B2 and D. We also conclude that E. coli isolates from IBD patients have been revealed to be resistant to commonly used antibiotics, in which most of them harbored strains that would be categorized as MDR.

Whole Genome Sequencing and CRISPR/Cas9 Gene Editing of Enterotoxigenic Escherichia coli BE311 for Fluorescence Labeling and Enterotoxin Analyses

Some prevention strategies, including vaccines and antibiotic alternatives, have been developed to reduce enterotoxigenic Escherichia coli proliferation in animal production. In this study, a wild-type strain of BE311 with a virulent heat-stable enterotoxin gene identical to E. coli K99 was isolated for its high potential for gene expression ability. The whole genome of E. coli BE311 was sequenced for gene analyses and editing. Subsequently, the fluorescent gene mCherry was successfully knocked into the genome of E. coli BE311 by CRISPR/Cas9. The E. coli BE311−mCherry strain was precisely quantified through the fluorescence intensity and red colony counting. The inflammatory factors in different intestinal tissues all increased significantly after an E. coli BE311−mCherry challenge in Sprague−Dawley rats (p < 0.05). The heat-stable enterotoxin gene of E. coli BE311 was knocked out, and an attenuated vaccine host E. coli BE311-STKO was constructed. Flow cytometry showed apoptotic cell numbers were lower following a challenge of IPEC-J2 cells with E. coli BE311-STKO than with E. coli BE311. Therefore, the E. coli BE311−mCherry and E. coli BE311-STKO strains that were successfully constructed based on the gene knock-in and knock-out technology could be used as ideal candidates in ETEC challenge models and for the development of attenuated vaccines.

Association between Pathogenic Variants of Diarrheagenic Escherichia coli and Growth in Children under 5 Years of Age in the Global Enteric Multicenter Study

There is a lack of information highlighting associations between different pathogenic variants of diarrheagenic Escherichia coli and childhood growth. Pathogenic variants of E. coli from stool samples, collected from 22,567 children enrolled in the Global Enteric Multicenter Study from December 2007 to March 2011, were detected by real-time polymerase chain reaction. We estimated the associations of different pathogenic variants of diarrheagenic E. coli with child growth. The association between an explanatory variable and the outcome variable was assessed using multiple linear regression, where the dependent variables were height-for-age, weight-for-age, and weight-for-height z-scores, and the independent variable was the presence of different pathogenic variants of diarrheagenic E. coli. After adjusting for potential covariates, such as age, gender, diarrhea, breastfeeding status, mother’s education, number of under-5 children, handwashing practice, handwashing material, source of drinking water, wealth index, available toilet facility, copathogens, comorbidity, time, and study site, the multivariable model identified a negative association between different pathogenic variants of diarrheagenic E. coli and child growth. Our analyses may provide the cornerstone for prospective epidemiologic investigation for the development of preventive measures for diarrheagenic E. coli and combat childhood undernutrition.

Lentils and Yeast Fibers: A New Strategy to Mitigate Enterotoxigenic Escherichia coli (ETEC) Strain H10407 Virulence?

Dietary fibers exhibit well-known beneficial effects on human health, but their anti-infectious properties against enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is a major food-borne pathogen that causes acute traveler’s diarrhea. Its virulence traits mainly rely on adhesion to an epithelial surface, mucus degradation, and the secretion of two enterotoxins associated with intestinal inflammation. With the increasing burden of antibiotic resistance worldwide, there is an imperious need to develop novel alternative strategies to control ETEC infections. This study aimed to investigate, using complementary in vitro approaches, the inhibitory potential of two dietary-fiber-containing products (a lentil extract and yeast cell walls) against the human ETEC reference strain H10407. We showed that the lentil extract decreased toxin production in a dose-dependent manner, reduced pro-inflammatory interleukin-8 production, and modulated mucus-related gene induction in ETEC-infected mucus-secreting intestinal cells. We also report that the yeast product reduced ETEC adhesion to mucin and Caco-2/HT29-MTX cells. Both fiber-containing products strengthened intestinal barrier function and modulated toxin-related gene expression. In a complex human gut microbial background, both products did not elicit a significant effect on ETEC colonization. These pioneering data demonstrate the promising role of dietary fibers in controlling different stages of the ETEC infection process.

The Probiotic Lactobacillus paracasei Ameliorates Diarrhea Cause by Escherichia coli O8via Gut Microbiota Modulation1

Introduction

Koumiss is a fermented horse milk food containing abundant probiotics. Lactobacillus paracasei is a bacterial strain isolated from koumiss that helps regulate the intestinal microbiota. One of the major cause of diarrhea is an imbalance of the intestinal flora. The aim of this study was to investigate whether Lactobacillus paracasei can ameliorate E. coli-induced diarrhea and modulate the gut microbiota.

Methods

Mouse models of diarrhea were established via intragastric E. coli O₈ administration. We then attempted to prevent or treat diarrhea in the mice via intragastric administration of a 3 × 10⁸ CFU/mL L. paracasei cell suspension. The severity of diarrhea was evaluated based on the body weight, diarrhea rate, and index, fecal diameter, ileum injury, hematoxylin-eosin (H&E) staining, and diamine oxidase (DAO) and zonulin expression. Expression of the tight junction (TJ) proteins claudin-1, occludin, and zona occludens (ZO-)1 were detected by immunohistochemistry (IHC). Gastrointestinal mRNA expression levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α were detected by real-time polymerase chain reaction (RT-PCR). The microbial composition was analyzed by 16s rRNA sequencing.

Results

The L. paracasei demonstrated excellent therapeutic efficacy against diarrhea. It elevated the TJ protein levels and downregulated proinflammatory cytokines IL-6, IL-1β, TNF-α, and p65, myosin light chain 2 (MLC2), myosin light chain kinase (MLCK). Moreover L. paracasei increased those bacteria, which can product short-chain fatty acid (SCFA) such Alistipes, Odoribacter, Roseburia, and Oscillibacter.

Conclusion

L. paracasei ameliorated diarrhea by inhibiting activation of the nuclear factor kappa B (NF-κB)-MLCK pathway and increasing the abundance of gut microbiota that produce SCFA.

Immune Response after Skin Delivery of a Recombinant Heat-Labile Enterotoxin B Subunit of Enterotoxigenic Escherichia coli in Mice

Enterotoxigenic Escherichia coli (ETEC) infections have been identified as a major cause of acute diarrhoea in children in developing countries, associated with substantial morbidity and mortality rates. Additionally, ETEC remains the most common cause of acute diarrhea of international travellers to endemic areas. The heat-labile toxin (LT) is a major virulence factor of ETEC, with a significant correlation between the presence of antibodies against LT and protection in infected patients. In the present work, we constructed a recombinant LTB unit (rLTB) and studied the capacity of this toxoid incorporated in microneedles (rLTB-MN) to induce a specific immune response in mice. MN were prepared from aqueous blends of the polymer Gantrez AN^® [poly (methyl vinyl ether-co-maleic anhydride)], which is not cytotoxic and has been shown to possess immunoadjuvant properties. The mechanical and dissolution properties of rLTB-MNs were evaluated in an in vitro Parafilm M^® model and in mice and pig skin ex vivo models. The needle insertion ranged between 378 µm and 504 µm in Parafilm layers, and MNs fully dissolved within 15 min of application inside porcine skin. Moreover, female and male BALB/c mice were immunized through ear skin with one single dose of 5 μg·rLTB in MNs, eliciting significant fecal anti-LT IgA antibodies, higher in female than in male mice. Moreover, we observed an enhanced production of IL-17A by spleen cells in the immunized female mice, indicating a mucosal non-inflammatory and neutralizing mediated response. Further experiments will now be required to validate the protective capacity of this new rLTB-MN formulation against this deadly non-vaccine-preventable disease.

Dietary Supplementation with Vitamin D, Fish Oil or Resveratrol Modulates the Gut Microbiome in Inflammatory Bowel Disease

Gastrointestinal health is influenced by the functional genes and metabolites generated by the human microbiome. As the volume of current biomedical and translational research indicates, the importance and impact of this ecosystem of microorganisms, especially those comprising the gut microbiome on human health, has become increasingly apparent. Changes to the gut microbiome are associated with inflammatory bowel disease (IBD), which is characterized by persistent intestinal inflammation. Furthermore, the lifetime dietary choices of their host may positively or negatively affect both the gut microbiome and its impact on IBD. As such, "anti-inflammatory" dietary supplements, their impact, and mechanisms in restoring gut microbiota homeostasis during IBD is an area of intensive research. Dietary supplementation may represent an important adjuvant treatment avenue for limiting intestinal inflammation in IBD. Overall, this review addresses the development of the gut microbiome, the significance of the gut microbiome in IBD, and the use of dietary supplements such as vitamin D, fish oil, and resveratrol in the mitigation of IBD-associated gut dysbiosis and intestinal inflammation.

Confronting challenges to enterotoxigenic Escherichia coli vaccine development

The enterotoxigenic Escherichia coli (ETEC) are a diverse and genetically plastic pathologic variant (pathovar) of E. coli defined by their production of heat-labile (LT) and heat-stable (ST) enterotoxins. These pathogens, which came to recognition more than four decades ago in patients presenting with severe cholera-like diarrhea, are now known to cause hundreds of millions of cases of symptomatic infection annually. Children in low-middle income regions of the world lacking access to clean water and basic sanitation are disproportionately affected by ETEC. In addition to acute diarrheal morbidity, these pathogens remain a significant cause of mortality in children under the age of five years and have also been linked repeatedly to sequelae of childhood malnutrition and growth stunting. Vaccines that could prevent ETEC infections therefore remain a high priority. Despite several decades of effort, a licensed vaccine that protects against the breadth of these pathogens remains an aspirational goal, and the underlying genetic plasticity of E. coli has posed a fundamental challenge to development of a vaccine that can encompass the complete antigenic spectrum of ETEC. Nevertheless, novel strategies that include toxoids, a more complete understanding of ETEC molecular pathogenesis, structural details of target immunogens, and the discovery of more highly conserved antigens essential for virulence should accelerate progress and make a broadly protective vaccine feasible.

In Vitro Evaluation of Dietary Fiber Anti-Infectious Properties against Food-Borne Enterotoxigenic Escherichia coli

Dietary fibers have well-known beneficial effects on human health, but their anti-infectious properties against human enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is the main agent of travelers’ diarrhea, against which targeted preventive strategies are currently lacking. ETEC pathogenesis relies on multiple virulence factors allowing interactions with the intestinal mucosal layer and toxins triggering the onset of diarrheal symptoms. Here, we used complementary in vitro assays to study the antagonistic properties of eight fiber-containing products from cereals, legumes or microbes against the prototypical human ETEC strain H10407. Inhibitory effects of these products on the pathogen were tested through growth, toxin production and mucus/cell adhesion inhibition assays. None of the tested compounds inhibited ETEC strain H10407 growth, while lentil extract was able to decrease heat labile toxin (LT) concentration in culture media. Lentil extract and specific yeast cell walls also interfered with ETEC strain H10407 adhesion to mucin beads and human intestinal cells. These results constitute a first step in the use of dietary fibers as a nutritional strategy to prevent ETEC infection. Further work will be dedicated to the study of fiber/ETEC interactions within a complex gut microbial background.