The Adherent/Invasive Escherichia coli Strain LF82 Invades and Persists in Human Prostate Cell Line RWPE-1, Activating a Strong Inflammatory Response

Intestinal biofilms: pathophysiological relevance, host defense, and therapeutic opportunities

SUMMARYThe human intestinal tract harbors a profound variety of microorganisms that live in symbiosis with the host and each other. It is a complex and highly dynamic environment whose homeostasis directly relates to human health. Dysbiosis of the gut microbiota and polymicrobial biofilms have been associated with gastrointestinal diseases, including irritable bowel syndrome, inflammatory bowel diseases, and colorectal cancers. This review covers the molecular composition and organization of intestinal biofilms, mechanistic aspects of biofilm signaling networks for bacterial communication and behavior, and synergistic effects in polymicrobial biofilms. It further describes the clinical relevance and diseases associated with gut biofilms, the role of biofilms in antimicrobial resistance, and the intestinal host defense system and therapeutic strategies counteracting biofilms. Taken together, this review summarizes the latest knowledge and research on intestinal biofilms and their role in gut disorders and provides directions toward the development of biofilm-specific treatments.

A New "Non-Traditional" Antibacterial Drug Fluorothiazinone-Clinical Research in Patients with Complicated Urinary Tract Infections

In order to combat resistance, it is necessary to develop antimicrobial agents that act differently from conventional antibiotics. Fluorothiazinone, 300 mg tablet (The Gamaleya National Research Center), is an original antibacterial drug based on a new small molecule T3SS and flagellum inhibitor. A total of 357 patients with complicated urinary tract infections (UTIs) were divided into two groups and given Fluorothiazinone 1200 mg/day or a placebo for 7 days to evaluate the efficacy and safety of the drug. Additionally, all patients were given Cefepime 2000 mg/day. Fluorothiazinone with Cefepime showed superiority over placebo/Cefepime based on the assessment of the proportion of patients with an overall outcome in the form of a cure after 21 days post-therapy (primary outcome), overall outcome in cure rates, clinical cure rates, and microbiological efficacy at the end of therapy and after 21 days post-therapy (secondary outcomes). In patients who received Fluorothiazinone, the rate of infection recurrences 53 and 83 days after the end of the therapy was lower by 18.9%, compared with patients who received placebo. Fluorothiazinone demonstrated a favorable safety profile with no serious unexpected adverse events reported. The results showed superiority of the therapy with Fluorothiazinone in combination with Cefepime compared with placebo/Cefepime in patients with cUTIs.

Gentamicin loaded niosomes against intracellular uropathogenic Escherichia coli strains

Urinary tract infections (UTIs) are the most common bacterial infections and uropathogenic Escherichia coli (UPEC) is the main etiological agent of UTIs. UPEC can persist in bladder cells protected by immunological defenses and antibiotics and intracellular behavior leads to difficulty in eradicating the infection. The aim of this paper is to design, prepare and characterize surfactant-based nanocarriers (niosomes) able to entrap antimicrobial drug and potentially to delivery and release antibiotics into UPEC-infected cells. In order to validate the proposed drug delivery system, gentamicin, was chosen as "active model drug" due to its poor cellular penetration. The niosomes physical-chemical characterization was performed combining different techniques: Dynamic Light Scattering Fluorescence Spectroscopy, Transmission Electron Microscopy. Empty and loaded niosomes were characterized in terms of size, ζ-potential, bilayer features and stability. Moreover, Gentamicin entrapped amount was evaluated, and the release study was also carried out. In addition, the effect of empty and loaded niosomes was studied on the invasion ability of UPEC strains in T24 bladder cell monolayers by Gentamicin Protection Assay and Confocal Microscopy. The observed decrease in UPEC invasion rate leads us to hypothesize a release of antibiotic from niosomes inside the cells. The optimization of the proposed drug delivery system could represent a promising strategy to significatively enhance the internalization of antimicrobial drugs.

Two-component system RstAB promotes the pathogenicity of adherent-invasive Escherichia coli in response to acidic conditions within macrophages

Adherent-invasive Escherichia coli (AIEC) strain LF82, isolated from patients with Crohn's disease, invades gut epithelial cells, and replicates in macrophages contributing to chronic inflammation. In this study, we found that RstAB contributing to the colonization of LF82 in a mouse model of chronic colitis by promoting bacterial replication in macrophages. By comparing the transcriptomes of rstAB mutant- and wild-type when infected macrophages, 83 significant differentially expressed genes in LF82 were identified. And we identified two possible RstA target genes (csgD and asr) among the differentially expressed genes. The electrophoretic mobility shift assay and quantitative real-time PCR confirmed that RstA binds to the promoters of csgD and asr and activates their expression. csgD deletion attenuated LF82 intracellular biofilm formation, and asr deletion reduced acid tolerance compared with the wild-type. Acidic pH was shown by quantitative real-time PCR to be the signal sensed by RstAB to activate the expression of csgD and asr. We uncovered a signal transduction pathway whereby LF82, in response to the acidic environment within macrophages, activates transcription of the csgD to promote biofilm formation, and activates transcription of the asr to promote acid tolerance, promoting its replication within macrophages and colonization of the intestine. This finding deepens our understanding of the LF82 replication regulation mechanism in macrophages and offers new perspectives for further studies on AIEC virulence mechanisms.

Prospective and challenges of live bacterial therapeutics from a superhero Escherichia coli Nissle 1917

Escherichia coli Nissle 1917 (EcN), the active component of Mutaflor(R), is a notable probiotic from Gram-negative to treat Crohn's disease and irritable bowel syndrome. Therefore, a comprehensive genomic database maximizes the systemic probiotic assessment to discover EcN's role in human health. Recently, advanced synthetic and genetic tools have opened up a rich area to execute EcN as "living medicines" with controllable functions. Incorporating unique biomarkers allows the engineered EcN to switch genes on and off in response to environmental cues. Since EcN holds promise as a safe nature vehicle, more studies are desired to fully realize a wide range of probiotic potential for disease treatment. This review aims to deliver a historical origin of EcN, discuss the recent promising genetic toolbox in the rational design of probiotics, and pinpoint the clinical translation and evaluation of engineered EcN in vitro and in vivo. The summary of safety concerns, strategies of biotherapeutics development, and the challenges and prospects of engineered EcN is also concluded.

Updated immunomodulatory roles of gut flora and microRNAs in inflammatory bowel diseases

Inflammatory bowel disease is a heterogeneous intestinal inflammatory disorder, including ulcerative colitis (UC) and Crohn's disease (CD). Existing studies have shown that the pathogenesis of IBD is closely related to the host's genetic susceptibility, intestinal flora disturbance and mucosal immune abnormalities, etc. It is generally believed that there are complicated interactions between host immunity and intestinal microflora/microRNAs during the occurrence and progression of IBD. Intestinal flora is mainly composed of bacteria, fungi, viruses and helminths. These commensals are highly implicated in the maintenance of intestinal microenvironment homeostasis alone or in combination. MiRNA is an endogenous non-coding small RNA with a length of 20 to 22 nucleotides, which can perform a variety of biological functions by silencing or activating target genes through complementary pairing bonds. A large quantity of miRNAs are involved in intestinal inflammation, mucosal barrier integrity, autophagy, vesicle transportation and other small RNA alterations in IBD circumstance. In this review, the immunomodulatory roles of gut flora and microRNAs are updated in the occurrence and progression of IBD. Meanwhile, the gut flora and microRNA targeted therapeutic strategies as well as other immunomodulatory approaches including TNF-α monoclonal antibodies are also emphasized in the treatment of IBD.

Preclinical models and evaluation criteria of prostatitis

Prostatitis is a common urological condition that affects almost half of all men at some point in their life. The prostate gland has a dense nerve supply that contributes to the production of fluid to nourish sperm and the mechanism to switch between urination and ejaculation. Prostatitis can cause frequent urination, pelvic pain, and even infertility. Long-term prostatitis increases the risk of prostate cancer and benign prostate hyperplasia. Chronic non-bacterial prostatitis presents a complex pathogenesis, which has challenged medical research. Experimental studies of prostatitis require appropriate preclinical models. This review aimed to summarize and compare preclinical models of prostatitis based on their methods, success rate, evaluation, and range of application. The objective of this study is to provide a comprehensive understanding of prostatitis and advance basic research.

Fluorothiazinon inhibits the virulence factors of uropathogenic Escherichia coli involved in the development of urinary tract infection

Uropathogenic Escherichia coli (UPEC) is the most common pathogenic bacterium associated with urinary tract infection. Due to the development of antibiotic resistance and MDR, UPEC infection has become a serious problem in the last decade. In order to combat resistance, it is necessary to develop innovative antimicrobial agents that act by different mechanisms than conventional antibiotics. Among the new therapeutic strategies, suppression of pathogen virulence has become a promising alternative, since it fundamentally reduces selective pressure and the development of resistance. In our study, we showed that the compound Fluorothiazinon suppressed UPEC's ability to form biofilms and to move using the flagellum, as well as to penetrate into cells. Prophylactic use with subsequent treatment of FT in rodent models led to an improvement in survival and significantly reduced the bacterial load in the organs of the urinary system, thereby inhibiting the development of ascending infection and preventing the development of pathological changes in prostate tissues. These results suggest that FT affects several UPEC virulence factors at once and if similar results can be found in clinical trials it can potentially be used as a new drug against UPEC.

Evaluation of the Immunomodulatory Effects of a Probiotics and Natural Extract-Based Formulation in Bacterial-Induced Prostatitis

Among the many factors inducing prostate inflammation, bacterial contribution is potentially underrated according to the scientific community. Bacterial prostatitis is characterized by modifications of the prostatic microenvironment, mainly driven by the immune system. Macrophages play a major role in bacterial prostatitis, secreting a plethora of proinflammatory and chemoattractive cytokines and proteolytic enzymes able to degrade the ECM, so facilitating the invasion of other immune cells. Consequently, macrophages represent a link between bacterial infection and prostate inflammation, as well as being the main target of prostate anti-inflammatory drugs and dietary supplements. This study aims to investigate the effect of a formulation composed of active principles and a probiotic strain with a particular focus on the anti-inflammatory effect in an in vitro bacterial prostatitis model. The results obtained showed that the formulation reduces the inflammatory response of prostatic epithelium induced by bacterial infection. This effect is mediated by the modulation of activated macrophages. Analysis of the cytokines released highlights that the tested formulation is able to reduce the expression of key proinflammatory cytokines involved in the pathogenesis of prostate diseases, in particular prostate cancer, and represents a valuable tool to prevent bacterial prostatitis and ensure favorable prostate health.

Battle royale: Immune response on biofilms – host-pathogen interactions

The research interest of the scientific community in biofilm-forming microorganisms is growing due to the problems caused by their infections affecting humans and animals, mainly because of the difficulty of the host immune system in eradicating these microbial complex communities and the increasing antimicrobial resistance rates worldwide. This review describes the virulence factors and their interaction with the microbial communities of four well-known and highly biofilm-forming pathogens, more exactly, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus spp., and Candida spp. The innate and adaptive immune responses caused by the infection with these microorganisms and their evasion to the host immune system by biofilm formation are discussed in the present work. The relevance of the differences in the expression of certain virulence factors and the immune response in biofilm-associated infections when compared to planktonic infections is usually described as the biofilm architecture protects the pathogen and alters the host immune responses, here we extensively discussed these mechanisms.

Adherent-Invasive and Non-Invasive Escherichia coli Isolates Differ in Their Effects on Caenorhabditis elegans' Lifespan

The adherent-invasive Escherichia coli (AIEC) pathotype has been implicated in the pathogenesis of inflammatory bowel diseases in general and in Crohn’s disease (CD) in particular. AIEC strains are primarily characterized by their ability to adhere to and invade intestinal epithelial cells. However, the genetic and phenotypic features of AIEC isolates vary greatly as a function of the strain’s clonality, host factors, and the gut microenvironment. It is thus essential to identify the determinants of AIEC pathogenicity and understand their role in intestinal epithelial barrier dysfunction and inflammation. We reasoned that soil nematode Caenorhabditis elegans (a simple but powerful model of host-bacterium interactions) could be used to study the virulence of AIEC vs. non- AIEC E. coli strains. Indeed, we found that the colonization of C. elegans (strain N2) by E. coli impacted survival in a strain-specific manner. Moreover, the AIEC strains’ ability to invade cells in vitro was linked to the median lifespan in C. elegans (strain PX627). However, neither the E. coli intrinsic invasiveness (i.e., the fact for an individual strain to be characterized as invasive or not) nor AIEC’s virulence levels (i.e., the intensity of invasion, established in % from the infectious inoculum) in intestinal epithelial cells was correlated with C. elegans’ lifespan in the killing assay. Nevertheless, AIEC longevity of C. elegans might be a relevant model for screening anti-adhesion drugs and anti-invasive probiotics.

|Isolation and characterization of novel bacteriophages as a potential therapeutic option for Escherichia coli urinary tract infections

Urinary tract infections (UTIs) are mainly caused by uropathogenic Escherichia coli (UPEC), whose impact can be exacerbated by multidrug-resistant (MDR) strains. Effective control strategies are, therefore, urgently needed. Among them, phage therapy represents a suitable alternative. Here, we describe the isolation and characterization of novel phages from wastewater samples, as well as their lytic activity against biofilm and adherence of UPEC to HEp-2 cells. The results demonstrated that phage vB_EcoM-phiEc1 (ϕEc1) belongs to Myoviridae family, whereas vB_EcoS-phiEc3 (ϕEc3) and vB_EcoS-phiEc4 (ϕEc4) belong to Siphoviridae family. Phages showed lytic activity against UPEC and gut commensal strains. Phage ϕEc1 lysed UPEC serogroups, whereas phages ϕEc3 and ϕEc4 lysed only UTI strains with higher prevalence toward the O25 serogroup. Moreover, phages ϕEc1 and ϕEc3 decreased both biofilm formation and adherence, whereas ϕEc4 was able to decrease adherence but not biofilm formation. In conclusion, these novel phages showed the ability to decrease biofilm and bacterial adherence, making them promising candidates for effective adjuvant treatment against UTIs caused by MDR UPEC strains. KEY POINTS: Phage with lytic activity against MDR UPEC strains were isolated and characterized under in vitro conditions. A novel method was proposed to evaluate phage activity against bacterial adherence in HEp-2 cell.. Phages represent a suitable strategy to control infections caused by MDR bacteria.

Nanoemulsions of Satureja montana Essential Oil: Antimicrobial and Antibiofilm Activity against Avian Escherichia coli Strains

Satureja montana essential oil (SEO) presents a wide range of biological activities due to its high content of active phytochemicals. In order to improve the essential oil’s (EO) properties, oil in water nanoemulsions (NEs) composed of SEO and Tween-80 were prepared, characterized, and their antimicrobial and antibiofilm properties assayed against Escherichia coli strains isolated from healthy chicken. Since surfactant and oil composition can strongly influence NE features and their application field, a ternary phase diagram was constructed and evaluated to select a suitable surfactant/oil/water ratio. Minimal inhibitory concentration and minimal bactericidal concentration of NEs, evaluated by the microdilution method, showed that the SEO NE formulation exhibited higher inhibitory effects against planktonic E. coli than SEO alone. The quantification of biofilm production in the presence of NEs, assessed by crystal violet staining and scanning electron microscopy, evidenced that sub-MIC concentrations of SEO NEs enable an efficient reduction of biofilm production by the strong producer strains. The optimized nanoemulsion formulation could ensure food safety quality, and counteract the antibiotic resistance of poultry associated E. coli, if applied/aerosolized in poultry farms.

Poultry-origin extraintestinal Escherichia coli strains carrying the traits associated with urinary tract infection, sepsis, meningitis and avian colibacillosis in India

AIM

In-depth 'One Health' risk assessment of extraintestinal pathogenic Escherichia coli (ExPEC) strains carrying the traits of urinary tract infection, sepsis, meningitis and avian colibacillosis in poultry of India.

METHODS AND RESULTS

A total of 230 E. coli isolates were recovered from chicken samples representing the different sources (faeces vs caeca), stages (poultry farms vs retails butcher shop) or environments (rural vs urban) of poultry in India. Among all poultry-origin E. coli isolates, 49 (21·1%) strains were identified as ExPEC possessing multiple virulence determinants regardless of their association with any specific phylogenetic lineages. Of particular, potentially virulent ExPEC pathotypes, that is, uropathogenic E.coli (UPEC, 20·4%), avian pathogenic E. coli (APEC, 34·6%), septicaemia-associated E. coli (SEPEC, 47·0%) and neonatal meningitis-causing E.39 coli (NMEC, 2·0%) were also detected among all ExPEC strains.

CONCLUSIONS

Our study is the first to assess ExPEC strains circulating in the different settings of poultry in India and significantly demonstrates their potential ability to cause multiple extraintestinal infections both in humans and animals.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data of our study are in favour of the possibility that poultry-origin putative virulent ExPEC pathotypes consequently constitute a threat risk to 'One Health' or for food safety and a great concern for poultry production of India.

Testosterone regulates the intracellular bacterial community formation of uropathogenic Escherichia coli in prostate cells via STAT3

BACKGROUND

UPEC can internalize clonally in prostate to form biofilm-like intracellular bacterial communities (IBCs) for recurrent or chronic infection. We previously indicated that the exposure of prostate cells to testosterone could suppress UPEC invasion and their persistent survival within cells by effectively inhibiting the JAK/STAT1 signaling pathway. However, the regulatory mechanism by which testosterone affects UPEC-induced prostatitis via STAT3, another latent transcription factor signaling pathway is still unclear. The present study aimed to clarify the role of STAT3 in the process of UPEC-induced inflammation and colonization in prostate epithelial cells.

METHODS

The effects of testosterone-mediated inhibition were compared between the prostatitis by different UPEC strains (CFT073 and J96) through the specific GFP-UPEC-infected prostate cell model. Fluorescence microscopy was used for UPEC IBCs detection and quantifying, and Flow cytometry, RT-PCR and western blotting were used for analyzing related gene and protein expressions. Pretreatment of JAK and STAT3 inhibitors were also applied to verify the regulation of transduction pathway in testosterone-mediated anti-UPEC infection.

RESULTS

This study revealed that testosterone effectively suppresses UPEC infection and IBC formation in prostate cells through the JAK/STAT3 pathway. The results show that CFT073 and J96 UPEC infection rates and colony numbers were dose-dependently reduced in RWPE-1 cells pretreated with 5 and 20 μg/mL testosterone at 0 and 24 h post-infection. Further, testosterone reduced the amounts of UPEC infecting and surviving within the prostate cells, as well as suppressed the size of IBCs formed. We demonstrated that pretreating testosterone effectively inhibited UPEC infection along with dose-dependent suppression of STAT3 and the phosphorylated-STAT3 expression in prostate cells, especially in 24 h J96 UPEC infected groups. The STAT inhibitor, SOCS3 also up-regulated at the same time. In addition, we pretreated the JAK1 or STAT3 inhibitor with testosterone to block the signaling transduction before CFT073 and J96 UPEC infection, and found the significant restoring in both the sizes of IBCs and bacterial numbers in RWPE-1 cells. Therefore, our results suggest that the suppression of STAT3 by testosterone treatment attenuate UPEC growing within IBCs and interfere with their infection to prostate cells.

CONCLUSIONS

Overall, our study demonstrates that testosterone suppresses the initial infection of prostate epithelial cells by UPEC and reduces the survival of UPEC within IBCs after infection. These results indicate a critical role for STAT3 in facilitating UPEC infection and persistence, and its participation in driving testosterone-suppressive responses in prostate epithelial cells. In conclusion, this study suggests that testosterone may be beneficial in treating clinically recurrent UPEC infections and, thus, the persistent recurrence of prostatic inflammation.

Study of a classification algorithm for AIEC identification in geographically distinct E. coli strains

Adherent-invasive Escherichia coli (AIEC) have been extensively implicated in Crohn’s disease pathogenesis. Currently, AIEC is identified phenotypically, since no molecular marker specific for AIEC exists. An algorithm based on single nucleotide polymorphisms was previously presented as a potential molecular tool to classify AIEC/non-AIEC, with 84% accuracy on a collection of 50 strains isolated in Girona (Spain). Herein, our aim was to determine the accuracy of the tool using AIEC/non-AIEC isolates from different geographical origins and extraintestinal pathogenic E. coli (ExPEC) strains. The accuracy of the tool was significantly reduced (61%) when external AIEC/non-AIEC strains from France, Chile, Mallorca (Spain) and Australia (82 AIEC, 57 non-AIEC and 45 ExPEC strains in total) were included. However, the inclusion of only the ExPEC strains showed that the tool was fairly accurate at differentiating these two close pathotypes (84.6% sensitivity; 79% accuracy). Moreover, the accuracy was still high (81%) for those AIEC/non-AIEC strains isolated from Girona and Mallorca (N = 63); two collections obtained from independent studies but geographically close. Our findings indicate that the presented tool is not universal since it would be only applicable for strains from similar geographic origin and demonstrates the need to include strains from different origins to validate such tools.

Bacterial Biofilm and its Role in the Pathogenesis of Disease

Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.

The role of major virulence factors and pathogenicity of adherent-invasive Escherichia coli in patients with Crohn's disease

Inflammatory bowel disease (IBD) is a term that describes Crohn's disease (CD) and ulcerative colitis (UC), and these two conditions are characterised by chronic inflammation of the gastrointestinal tract. Dysbiosis of intestinal microbiota has been consistently linked to patients with IBD. In the last two decades, the progressive implication of adherent-invasive Escherichia coli (AIEC) pathogenesis in patients with CD has been increasing. Here we discuss recent findings that indicate the role and mechanisms of AIEC in IBD. We also highlight AIEC virulence factor genes and mechanisms that suggest an important role in the severity of inflammation in CD patients. Finally, we emphasise data on the prevalence of AIEC in CD patients.

A simple, fast and reliable scan-based technique as a novel approach to quantify intracellular bacteria

Background

Quantification of intracellular bacteria is fundamental in many areas of cellular and clinical microbiology to study acute and chronic infections. Therefore, rapid, accurate and low-cost methods represent valuable tools in determining bacterial ability to persist and proliferate within eukaryotic cells.

Results

Herein, we present the first application of the immunofluorescence In-Cell Western (ICW) assay aimed at quantifying intracellular bacteria in in vitro infection models. The performance of this new approach was evaluated in cell culture infection models using three microorganisms with different lifestyles. Two facultative intracellular bacteria, the fast-growing Shigella flexneri and a persistent strain of Escherichia coli, as well as the obligate intracellular bacterium Chlamydia trachomatis were chosen as bacterial models. The ICW assay was performed in parallel with conventional quantification methods, i.e. colony forming units (CFUs) and inclusion forming units (IFUs). The fluorescence signal intensity values from the ICW assay were highly correlated to CFU/IFUs counting and showed coefficients of determination (R²), ranging from 0,92 to 0,99.

Conclusions

The ICW assay offers several advantages including sensitivity, reproducibility, high speed, operator-independent data acquisition and overtime stability of fluorescence signals. All these features, together with the simplicity in performance, make this assay particularly suitable for high-throughput screening and diagnostic approaches.

Comparative genomics of a subset of Adherent/Invasive Escherichia coli strains isolated from individuals without inflammatory bowel disease

There is increased evidence demonstrating the association between Crohn's Disease (CD), a type of Inflammatory Bowel Disease (IBD), and non-diarrheagenic Adherent/Invasive Escherichia coli (AIEC) isolates. AIEC strains are phenotypically characterized by their adhesion, invasion and intra-macrophage survival capabilities. In the present study, the genomes of five AIEC strains isolated from individuals without IBD (four from healthy donors and one from peritoneal liquid) were sequenced and compared with AIEC prototype strains (LF82 and NRG857c), and with extra-intestinal uropathogenic strain (UPEC CFT073). Non-IBD-AIEC strains showed an Average Nucleotide Identity up to 98% compared with control strains. Blast identities of the five non-IBD-AIEC strains were higher when compared to AIEC and UPEC reference strains than with another E. coli pathotypes, suggesting a relationship between them. The SNPs phylogeny grouped the five non-IBD-AIEC strains in one separated cluster, which indicates the emergence of these strains apart from the AIEC group. Additionally, four genomic islands not previously reported in AIEC strains were identified. An incomplete Type VI secretion system was found in non-IBD-AIEC strains; however, the Type II secretion system was complete. Several groups of genes reported in AIEC strains were searched in the five non-IBD-AIEC strains, and the presence of fimA, fliC, fuhD, chuA, irp2 and cvaC were confirmed. Other virulence factors were detected in non-IBD-AIEC strains, which were absent in AIEC reference strains, including EhaG, non-fimbrial adhesin 1, PapG, F17D-G, YehA/D, FeuC, IucD, CbtA, VgrG-1, Cnf1 and HlyE. Based on the differences in virulence determinants and SNPs, it is plausible to suggest that non-IBD AIEC strains belong to a different pathotype.

Oligomannose-Rich Membranes of Dying Intestinal Epithelial Cells Promote Host Colonization by Adherent-Invasive E. coli

A novel mechanism is revealed by which clinical isolates of adherent-invasive Escherichia coli (AIEC) penetrate into the epithelial cell layer, replicate, and establish biofilms in Crohn's disease. AIEC uses the FimH fimbrial adhesin to bind to oligomannose glycans on the surface of host cells. Oligomannose glycans exposed on early apoptotic cells are the preferred binding targets of AIEC, so apoptotic cells serve as potential entry points for bacteria into the epithelial cell layer. Thereafter, the bacteria propagate laterally in the epithelial intercellular spaces. We demonstrate oligomannosylation at two distinct sites of a glycoprotein receptor for AIEC, carcinoembryonic antigen related cell adhesion molecule 6 (CEACAM6 or CD66c), on human intestinal epithelia. After bacterial binding, FimH interacts with CEACAM6, which then clusters. The presence of the highest-affinity epitope for FimH, oligomannose-5, on CEACAM6 is demonstrated using LC-MS/MS. As mannose-dependent infections are abundant, this mechanism might also be used by other adherent-invasive pathogens.

Adherent-invasive Escherichia coli in inflammatory bowel disease

Intestinal microbiome dysbiosis has been consistently described in patients with IBD. In the last decades, Escherichia coli, and the adherent-invasive E coli (AIEC) pathotype in particular, has been implicated in the pathogenesis of IBD. Since the discovery of AIEC, two decades ago, progress has been made in unravelling these bacteria characteristics and its interaction with the gut immune system. The mechanisms of adhesion of AIEC to intestinal epithelial cells (via FimH and cell adhesion molecule 6) and its ability to escape autophagy when inside macrophages are reviewed here. We also explore the existing data on the prevalence of AIEC in patients with Crohn's disease and UC, and the association between the presence of AIEC and disease location, activity and postoperative recurrence. Finally, we highlight potential therapeutic strategies targeting AIEC colonisation of gut mucosa, including the use of phage therapy, bacteriocins and antiadhesive molecules. These strategies may open new avenues for the prevention and treatment of IBD in the future.

The effects of mucosal media on some pathogenic traits of Crohn's disease-associated Escherichia coli LF82

Aim: Adherent-invasive Escherichia coli (AIEC) pathovar has been identified in intestinal mucosa of patients with Crohn's disease. Our aim was to compare the impact of sterile mucosal media (Muc-M) originated from different parts of the intestine on some pathogenic traits of AIEC LF82 strain. Materials & methods: Muc-M composed of certain rates of cell culture medium or M63 minimal medium and mucosal contents obtained from different part of intestine were designed for cell-infection experiments and biofilm-formation assays. Results: The results showed that Muc-M reduced usually pathogenic properties of AIEC LF82. However, LF82 adhesion, invasion and specific biofilm formations were markedly higher in Muc-MCR than those in Muc-MIR . Conclusion: In this context, the findings of present study could help the endeavors related to determining molecular targets for AIEC bacteria.

Testosterone suppresses uropathogenic Escherichia coli invasion and colonization within prostate cells and inhibits inflammatory responses through JAK/STAT-1 signaling pathway

Prostatitis is a common condition in adult men of all ages. Uropathogenic Escherichia coli (UPEC) are most frequent pathogen involved in bacterial prostatitis by refluxing the infected urine into prostatic ducts and resulting in an ascending urethral infection. However, the study about the mechanisms of UPEC to invade, replicate and persist in normal prostate epithelial cell is only few. Given the fact that UPEC is pathogen most frequently involved in prostatitis and that testosterone has been demonstrated to attenuate prostate inflammation caused by other etiologies. In this study we investigated whether the testosterone reduces the prostatitis and related mechanism by regulating IFN-γ/STAT1 signaling pathway. In the current study aimed to clarify whether testosterone influences the process of UPEC-induced prostate inflammation and invasion into the prostate epithelial cells. In addition, we set up a normal prostate cell model for UPEC infection to evaluate the ability to invade the urothelial cells as well as the colonization of intercellular bacterial communities in vitro. By using the model, we examine the effects of testosterone to suppress effectively the invasion and survival of UPEC in the prostate cells, and inhibit LPS-induced inflammatory responses through the JAK/STAT1 pathway have also been indicated. Our results demonstrated testosterone not only suppressed the invasion and colonization of UPEC, but also inhibited the expression of pro-inflammatory IL-1β, IL-6 and IL-8 cytokines expression induced by UPEC in a dose-dependent manner. We found the effective dose of testosterone to suppress UPEC infect prostate cells may be appropriate under 40μg/ml. Our data also revealed 20μg/ml testosterone treated PZ-HPV-7 cells significantly suppressed the LPS-induced JAK/STAT1 pathway and inflammatory responses, and reached to maximal effects at 40μg/ml treatment. These results indicate that testosterone plays an anti-inflammatory role in LPS-induced prostate cell inflammation by down-regulating JAK/STAT1 signaling pathway. Interestingly, the JAK inhibitor and testosterone for 24hr pretreatment rather markedly induced the colonization of UPEC in the PZ-HPV-7 cells. Based on the above data, the suppression of UPEC colonization in the prostate cells by testosterone seems to be unrelated with JAK/STAT signaling pathway, whereas the JAK may involve into the UPEC infection. Summing up these data, our findings have demonstrated the suppressive effects of testosterone on the invasion and survival of UPEC and induced inflammation in prostate epithelial cells. These findings indicate the action mechanism of testosterone as an anti-inflammatory mediator in the prostate cells is regulated through JAK/STAT1 signaling pathway, may be beneficial in treating prostate inflammation. Altogether, this study has provided the possibility that using testosterone in the prevention and clinical treatment of prostatitis is a new direction.