A single-nucleotide polymorphism in the gene encoding osteoprotegerin, an anti-inflammatory protein produced in response to infection with diarrheagenic Escherichia coli, is associated with an increased risk of nonsecretory bacterial diarrhea in North American travelers to Mexico

Multispecies synbiotics alleviate dextran sulfate sodium (DSS)-induced colitis: Effects on clinical scores, intestinal pathology, and plasma biomarkers in male and female mice

BACKGROUND

Inflammatory bowel disease (IBD) is characterized by recurrent inflammation of the gastrointestinal tract and has been linked to an imbalance in gut bacteria. Synbiotics, which combine probiotics and prebiotics, are emerging as potential IBD treatments.

AIM

To examine the effects of four synbiotic formulations on intestinal inflammation and peripheral biomarkers in a rodent IBD model of both sexes.

METHODS

Colitis was induced in male and female C57BL/6 mice using 1% dextran sulfate sodium (DSS). Concurrently, a non-exposed control group was maintained. Starting on day 4 post-induction, DSS-exposed mice received one of four synbiotic preparations (Synbio1-4 composed of lactic acid bacteria, Bifidobacterium and dietary fibres), an anti-inflammatory drug used to treat IBD (mesalazine), or placebo (water) until day 14. Clinical symptoms and body weight were monitored daily. Blood samples (taken on days -3, 4, and 14, relative to DSS introduction), were used to analyze plasma biomarkers. At the end of the study, intestinal tissues underwent histological and morphological evaluation.

RESULTS

Compared to placebo, the Synbio1-, 2- and 3-treated groups had improved clinical scores by day 14. Synbio1 was the only preparation that led to clinical improvements to scores comparable to those of controls. The Synbio1-and 3-treated groups also demonstrated histological improvements in the colon. Plasma biomarker analyses revealed significant Synbio1-induced changes in plasma IL17A, VEGFD, and TNFRSF11B levels that correlated with improved clinical or histological scores. Sex-stratified analyses revealed that most therapeutic-like effects were more pronounced in females.

CONCLUSION

Our findings underscore the potential therapeutic benefits of specific synbiotics for IBD management. However, further research is needed to validate these outcomes in human subjects.

Processed ready-to-eat (RTE) foods sold in Yenagoa Nigeria were colonized by diarrheagenic Escherichia coli which constitute a probable hazard to human health

The study aimed to recover diarrheagenic Escherichia coli strains from processed ready-to-eat (RTE) foods in Yenagoa, Nigeria and characterize them using culture-based and molecular methods. Three hundred RTE food samples were collected randomly from different food outlets between February 2021 and August 2021 and assessed for the occurrence of E. coli using standard bacteriological procedures. The virulence factor formation and antibiotic susceptibility profile of the isolates was carried out using standard microbiological procedures. Polymerase chain reaction (PCR) was used to confirm the identity of the isolates via specific primers and further used to assay the diarrheagenic determinants of the E. coli isolates. The prevalence of E. coli positive samples based on the proliferation of E. coli on Chromocult coliform agar forming purple to violet colonies was 80(26.7%). The population density of E. coli from the RTE foods ranged from 0–4.3 × 10⁴ ± 1.47 CFU/g. The recovered E. coli isolates (n = 62) were resistant to antibiotics in different proportions such as ampicillin 62(100%), aztreonam 47(75.81%) and chloramphenicol 43(69.35%). All the recovered E. coli isolates were resistant to ≥ 2 antibiotics. The multiple antibiotic-resistant index (MARI) ranged from 0.13–0.94 with 47(75.8%) of isolates having MARI >2. A total of 48(77.4%) of the isolates were multidrug-resistant (MDR). The proportion of extracellular virulence factor formation is as follows: protease 12(19.35%), curli 39(62.9%), cellulose 21(33.89%), ornithine decarboxylase 19(30.65%) and aesculin hydrolysis 14(22.58%). The overall proportion of diarrheagenic E. coli was 33/62(53.2%). The distributions of typical diarrheagenic E. coli includes: tETEC 9(14.5%), tEPEC 13(20.9%), tEAEC 6(9.7%), tEIEC 2(3.2%) and tEHEC 3(4.8%). The proportions of atypical strains include aETEC 10(16.1%), aEAEC 5(8.1%), aEPEC 1(1.6%) and aEIEC 3(4.8%). This study demonstrated that some RTE foods sold in Yenagoa, Nigeria, are contaminated and constitute a probable human health hazard. Thus, there is a need for intensive surveillance of this isolate in RTE foods variety to spot evolving AMR phenotypes and avert food-borne infections.

TNFRSF11B Suppresses Memory CD4+ T Cell Infiltration in the Colon Cancer Microenvironment: A Multiomics Integrative Analysis

Background

Colorectal cancer is a lethal cancer worldwide. Due to the low tumor mutation burden and low proportion of tumor-infiltrating lymphocytes in the microenvironment of most patients, innovative immunotherapeutic approaches need to be identified.

Methods

Using the TCGA-COAD dataset (n = 514), we identified TNFRSF11B as a prognostic factor of colon cancer. An immunohistochemistry (IHC) dataset (n = 86), 290 single colorectal cancer cells (GSE81861), and 31 paired colon cancer transcriptional datasets were further applied to validate the function of TNFRSF11B, which was confirmed via fluorescence-activated cell sorting (FACS) analysis.

Results

A risk score system consisting of eight immune-related genes (IRGs) (FGFR2, ZC3HAV1L, TNFRSF11B, CD79A, IGHV3-11, IGHV3-21, IGKV2D-30, and IGKV6D-21) was constructed to predict the prognosis of colon cancer patients. Only TNFRSF11B was closely correlated with late-stage lymph node metastasis and worse survival outcomes (p = 0.010, p = 0.014, and p = 0.0061). In our IHC dataset, 72.09% (62/86) of the colon cancer patients had TNFRSF11B overexpression with significantly shorter overall survival times (p = 0.072). High TNFRSF11B expression typically had a later TNM stage (p = 0.067), a higher frequency of lymph node (p = 0.029) and lymphovascular (p = 0.007) invasion, and a higher incidence of pneumonia (p = 0.056) than their counterparts. The expression of six genes (KRT18, ARPC5L, ACTG1, ARPC2, EZR, and YWHAZ) related to pathogenic E. coli infection was simultaneously increased with TNFRSF11B overexpression via gene set enrichment analysis (GSEA). These genes are involved in the regulation of the actin cytoskeleton, shigellosis, bacterial invasion of epithelial cells, and Salmonella infection. Finally, only activated memory CD4⁺ T cells (p = 0.017) were significantly decreased in the high TNFRSF11B expression group via CIBERSORT comparison, which was confirmed by TIMER2.0 analysis of the TCGA-COAD dataset. We also performed FACS analysis to show that TNFRSF11B decreased the infiltration of central memory CD4⁺ T cells and effector memory CD4⁺ T cells in the colorectal cancer microenvironment (all p <0.001).

Conclusion

TNFRSF11B acts as a prognostic factor for colon cancer patients and could affect the colon cancer immune response. TNFRSF11B was closely related to lymph node invasion and pathogenic E. coli. infection, which may negatively affect memory-activated CD4+ T cell infiltration in colon cancer.

Characterization of large yellow croaker (Larimichthys crocea) osteoprotegerin and its role in the innate immune response against to Vibrio alginolyticus

Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily, contributing to inflammation, apoptosis, and differentiation. However, the function of OPG in the host immune system of teleosts remains unclear. Here, we cloned the cDNA of the LcOPG gene from large yellow croaker. LcOPG mRNA was expressed in all analyzed tissues and was upregulated by Vibrio alginolyticus infection in immune tissues and monocytes/macrophages (MO/MФ). Subsequently, the LcOPG protein was expressed and purified using a prokaryotic expression system. Recombinant LcOPG protein (rLcOPG) treatment suppressed V. alginolyticus-induced pro-inflammatory cytokine and enhanced V. alginolyticus-induced anti-inflammatory cytokine mRNA expression. Furthermore, rLcOPG decreased V. alginolyticus-induced MO/MФ apoptosis. Therefore, the results indicate that LcOPG might play a role in the immune response of V. alginolyticus-infected large yellow croaker.

Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Drinking Water Samples From a Forcibly Displaced, Densely Populated Community Setting in Bangladesh

Introduction: Community-acquired infections due to extended-spectrum beta-lactamase (ESBL) producing Escherichia coli are rising worldwide, resulting in increased morbidity, mortality, and healthcare costs, especially where poor sanitation and inadequate hygienic practices are very common.

Objective: This study was conducted to investigate the prevalence and characterization of multidrug-resistant (MDR) and ESBL-producing E. coli in drinking water samples collected from Rohingya camps, Bangladesh.

Methods: A total of 384 E. coli isolates were analyzed in this study, of which 203 were from household or point-of-use (POU) water samples, and 181 were from source water samples. The isolates were tested for virulence genes, ESBL-producing genes, antimicrobial susceptibility by VITEK 2 assay, plasmid profiling, and conjugal transfer of AMR genes.

Results: Of the 384 E. coli isolates tested, 17% (66/384) were found to be ESBL producers. The abundance of ESBL-producers in source water contaminated with E. coli was observed to be 14% (27/181), whereas, 19% (39/203) ESBL producers was found in household POU water samples contaminated with E. coli. We detected 71% (47/66) ESBL-E. coli to be MDR. Among these 47 MDR isolates, 20 were resistant to three classes, and 27 were resistant to four different classes of antibiotics. Sixty-four percent (42/66) of the ESBL producing E. coli carried 1 to 7 plasmids ranging from 1 to 103 MDa. Only large plasmids with antibiotic resistance properties were found transferrable via conjugation. Moreover, around 7% (29/384) of E. coli isolates harbored at least one of 10 virulence factors belonging to different E. coli pathotypes.

Conclusions: The findings of this study suggest that the drinking water samples analyzed herein could serve as an important source for exposure and dissemination of MDR, ESBL-producing and pathogenic E. coli lineages, which therewith pose a health risk to the displaced Rohingya people residing in the densely populated camps of Bangladesh.

The BE GONE trial study protocol: a randomized crossover dietary intervention of dry beans targeting the gut microbiome of overweight and obese patients with a history of colorectal polyps or cancer

BACKGROUND

Mouse and human studies support the promise of dry beans to improve metabolic health and to lower cancer risk. In overweight/obese patients with a history of colorectal polyps or cancer, the Beans to Enrich the Gut microbiome vs. Obesity's Negative Effects (BE GONE) trial will test whether and how an increase in the consumption of pre-cooked, canned dry beans within the context of usual diet and lifestyle can enhance the gut landscape to improve metabolic health and reduce cancer risk.

METHODS/DESIGN

This randomized crossover trial is designed to characterize changes in (1) host markers spanning lipid metabolism, inflammation, and obesity-related cancer risk; (2) compositional and functional profiles of the fecal microbiome; and (3) host and microbial metabolites. With each subject serving as their own control, the trial will compare the participant's usual diet with (intervention) and without (control) dry beans. Canned, pre-cooked dry beans are provided to participants and the usual diet continually assessed and monitored. Following a 4-week run-in and equilibration period, each participant provides a total of 5 fasting blood and 6 stool samples over a total period of 16 weeks. The intervention consists of a 2-week ramp-up of dry bean intake to 1 cup/d, which is then continued for an additional 6 weeks. Intra- and inter-individual outcomes are assessed across each crossover period with consideration of the joint or modifying effects of the usual diet and baseline microbiome.

DISCUSSION

The BE GONE trial is evaluating a scalable dietary prevention strategy targeting the gut microbiome of high-risk patients to mitigate the metabolic and inflammatory effects of adiposity that influence colorectal cancer risk, recurrence, and survival. The overarching scientific goal is to further elucidate interactions between diet, the gut microbiome, and host metabolism. Improved understanding of the diet-microbiota interplay and effective means to target these relationships will be key to the future of clinical and public health approaches to cancer and other major diet- and obesity-related diseases.

TRIAL REGISTRATION

This protocol is registered with the U.S. National Institutes of Health trial registry, ClinicalTrials.gov, under the identifier NCT02843425. First posted July 25, 2016; last verified January 25, 2019.

Diarrheagenic Escherichia coli

Most Escherichia coli strains live harmlessly in the intestines and rarely cause disease in healthy individuals. Nonetheless, a number of pathogenic strains can cause diarrhea or extraintestinal diseases both in healthy and immunocompromised individuals. Diarrheal illnesses are a severe public health problem and a major cause of morbidity and mortality in infants and young children, especially in developing countries. E. coli strains that cause diarrhea have evolved by acquiring, through horizontal gene transfer, a particular set of characteristics that have successfully persisted in the host. According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. coli pathotypes, which are collectively known as diarrheagenic E. coli. In this review, we have gathered information on current definitions, serotypes, lineages, virulence mechanisms, epidemiology, and diagnosis of the major diarrheagenic E. coli pathotypes.

Osteoprotegerin: A novel biomarker for inflammatory bowel disease and gastrointestinal carcinoma

Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily of proteins. Although initial data illustrated the key role that OPG plays in bone turnover, numerous recent reports indicate that OPG is also an important factor in inflammatory pathways and tumor cell survival. OPG contributes directly to inflammatory processes and has been evaluated as a novel non-invasive biomarker of gut inflammation. Furthermore, OPG affects cell turn-over, differentiation, death, and survival via extracellular pathways, correlating with worse prognosis in inflammatory bowel diseases and several gastrointestinal carcinomas. It is now clear that OPG has multiple functions and characteristics. This review gives an overview of OPG, highlights its roles in different extracellular pathways, and outlines how OPG could be used as a novel non-invasive biological marker in inflammatory bowel diseases and gastrointestinal carcinomas.

Single nucleotide polymorphisms in the promoter of the gene encoding the lipopolysaccharide receptor CD14 are associated with bacterial diarrhea in US and Canadian travelers to Mexico

BACKGROUND

Under normal conditions, the expression of CD14, which is the principal receptor for bacterial lipopolysaccharide, is down-regulated in the intestinal mucosa but increases in response to inflammatory stimuli. The aim of the present study was to investigate whether fecal CD14 levels increased in response to infection with diarrheagenic Escherichia coli and whether single nucleotide polymorphisms (SNPs) in the CD14 gene were associated with an increased susceptibility to traveler's diarrhea (TD) in US visitors to Mexico.

METHODS

Six SNPs located at the promoter, exon, and untranslated regions of CD14 were typed in a prospective cohort study of 1360 visitors to Mexico at risk for TD. Stools from visitors with TD were studied for enteric pathogens by culture, colony hybridization, and polymerase chain reaction. Fecal soluble CD14 (sCD14) was measured in a subgroup of 203 adults with diarrhea and 66 healthy controls by enzyme-linked immunosorbent assay.

RESULTS

The minor allele frequencies for CD14 SNPs were significantly different among the various racial and ethnic groups studied. Two SNPs in the promoter region of CD14 (-159 C > T; rs2569190 and -4191 C > T; rs5744441) were found to be associated with TD in White visitors. The -159 TT genotype was associated with a higher risk for TD (Relative risk [RR], 1.21; 95% confidence interval [CI], 1.05-1.38; P = .008), whereas individuals with the -4191 TT genotype were protected from infection (RR, 0.82; 95% CI, 0.71-0.92; P = .006). Subjects with TD excreted higher levels of fecal CD14 than did healthy controls (33,480 pg/mL vs 6178 pg/mL; P < .02). Fecal sCD14 levels were higher in stool samples from visitors with TD and the -159 TT genotype than they were in visitors with the CC/CT genotypes (P = .02), and stool samples from subjects with the -4191 CC genotype had higher fecal sCD14 levels than did stool samples from visitors with the CT/TT (P = .005) genotype. In a multivariate analysis with haplotypes constructed with the 6 SNPs studied, subjects with the haplotype containing the -159 C and the -4191 T allele were less likely to acquire TD (P = .015).

CONCLUSIONS

Our study suggests that CD14 levels increase in response to bacterial diarrhea and that polymorphisms in the CD14 gene influence susceptibility to TD. Intestinal CD14 plays an important role in the innate immune response to enteric pathogens.

Host parasite interactions and pathophysiology in Giardia infections

Giardia is a protozoan parasite of the small intestine, and a leading cause of diarrhoeal disease worldwide in a variety of animals, including humans. The host-parasite interaction and pathophysiological processes of giardiasis remain incompletely understood. Current research suggests that Giardia-induced diarrhoeal disease is mediated by small intestinal malabsorption and maldigestion, chloride hypersecretion and increased rates of small intestinal transit. Small intestinal malabsorption and maldigestion results from the CD8+ lymphocyte-induced diffuse shortening of brush border microvilli. Activation of CD8+ lymphocytes occurs secondary to small intestinal barrier dysfunction, which results from heightened rates of enterocyte apoptosis and disruption of epithelial tight junctions. Both host and parasite factors contribute to the pathogenesis of giardiasis and ongoing research in this field may elucidate genotype/assemblage-specific pathogenic mechanisms. Giardia infections can result in chronic gastrointestinal disorders such as post-infectious Irritable Bowel Syndrome and symptoms may manifest at extra-intestinal sites, even though the parasite does not disseminate beyond the gastrointestinal tract. The infection can cause failure to thrive in children. Furthermore, there is now evidence suggesting that Giardia symptoms may vary between industrialised and developing areas of the world, for reasons that remain obscure. More research is needed to improve our understanding of this parasitic infection which was recently included in the World Health Organisation "Neglected Disease Initiative".

New Developments in Traveler's Diarrhea

Traveler's diarrhea (TD) is a crucial area for research, as it affects millions of tourists each year and creates a large economic burden. More than 60% of TD cases are caused by a variety of bacterial enteropathogens: diarrhea-producing Escherichia coli, Shigella, Campylobacter, Salmonella, Aeromonas, Plesiomonas, and noncholera Vibrios. Noroviruses are also an important cause of morbidity among travelers. Recent studies have identified host genetic risk factors associated with susceptibility to pathogen-specific TD. Prevention strategies should be emphasized, as all individuals with TD experience approximately 24 hours of disability and 5-10% experience chronic functional bowel disease. Poorly absorbed rifaximin provides protection for trips lasting 2 weeks or less. TD vaccines are also currently in development. All individuals planning trips to developing regions should be armed with 1 of the 3 agents that have shown efficacy for self-treatment of TD: ciprofloxacin (or levofloxacin), rifaximin, or azithromycin, depending upon the location of the trip. Although global epidemiologic changes in etiologic agents as well as antibiotic resistance patterns have been better understood recently, changes should be expected during the next decade due to new prevention and treatment approaches.

Defining causality in emerging agents of acute bacterial diarrheas: a step beyond the Koch’s postulates

Diarrheal illnesses account for significant morbidity and mortality worldwide. Most cases of diarrhea are caused by bacteria, viruses or parasites. Advances in molecular biology and epidemiology have allowed the identification of emerging pathogens that may cause or, at least, may be associated with diarrhea. However, the same advances have also revealed the complexity of the gut microbiome, suggesting that a potential agent of diarrhea may also been found in healthy individuals. In addition, most of the newly identified emerging agents of diarrhea are ubiquitous and have not yet fulfilled Koch’s postulates. Research investigations should address appropriate matched controls and integrate findings from medical microbiology, epidemiology and molecular biology. This integrative approach should provide insights to our knowledge regarding exposition to common source or risk factors. Here, we aim to review some of these emerging bacterial agents of diarrheas and propose guidelines or prescriptions that may help in defining causality.

Genetics of susceptibility to infection with enteric pathogens

PURPOSE OF REVIEW

This review examines recent developments in human genetic susceptibility to enteropathogens that cause infectious diarrhea.

RECENT FINDINGS

The affinity of specific norovirus genogroups to different histoblood group antigens (HBGAs) on secretor cells has been studied in different epidemiologic studies. HBGAs are also used as receptors by Vibrio cholerae with different degrees of affinity between biotypes. Polymorphisms in the CD14, lactoferrin and osteoprotegerin promoter genes were associated to diarrhea in travelers. Single nucleotide polymorphisms in the IL-8 genes are also associated to increased risk for enteroaggregative Escherichia coli and Clostridium difficile infection. IL-10 haplotypes were associated to enterotoxigenic E. coli associated diarrhea in exposed individuals. A family-based study showed a significant association of the LPLUNC1 gene and cholera. The major histocompatibility complex class II antigens are associated to different degrees of susceptibility and resistance to Salmonella, Cryptosporidium and Entamoeba infection.

SUMMARY

Variants in genes that encode molecules that mediate attachment, pathogen recognition, inflammatory cytokine response, innate and acquired immunity are being identified as determinants of host genetic susceptibility to infectious diarrhea.

Systematic review: the epidemiology and clinical features of travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea is the most common medical complaint among persons venturing into developing areas from industrialized regions.

AIM

To review recent developments dealing with microbiological, clinical, pathophysiological and therapeutic aspects of travellers' diarrhoea.

METHODS

The author's extensive file plus a review of publications listed in PubMed on January 22, 2009 on the topic of travellers' diarrhoea were reviewed.

RESULTS

Travellers' diarrhoea is largely caused by detectable and undetected bacterial enteropathogens, explaining the remarkable effectiveness of antibacterial agents in prophylaxis and therapy of the illness. A number of host genetic polymorphisms have been recently linked with susceptibility to travellers' diarrhoea. Novel antisecretory agents are being developed for treatment considering their physiological effects in acute diarrhoea. All travellers should be armed with one of three antibacterial drugs, ciprofloxacin, rifaximin or azithromycin, before their trips to use in self therapy should diarrhoea occur during travel. Loperamide may treat milder forms of travellers' diarrhoea and can be employed with antibacterial drugs.

CONCLUSIONS

Diarrhoea will continue to plague international travellers to high-risk regions. More studies of the incidence rate, relative important of the various pathogens by geographical region of the world, host risk factors and optimal therapeutic approach are needed.