5-Aminosalicylic acid downregulates the growth and virulence of Escherichia coli associated with IBD and colorectal cancer, and upregulates host anti-inflammatory activity

5-aminosalicylic acid alleviates colitis and protects intestinal barrier function by modulating gut microbiota in mice

5-aminosalicylic acid (5-ASA) is widely used in the treatment of ulcerative colitis (UC), but its anti-inflammatory mechanism is complex and has not been fully understood. DSS model was used to test the effect of 5-ASA. Tight junction and Ki-67 were detected by western blot, immunofluorescence, and immunohistochemistry or qPCR. 16S rRNA gene sequencing of gut microbiota and subsequent bioinformatics and statistical analysis were performed to identify the specific bacteria which were associated with the treatment effect of 5-ASA. GC-MS was performed to test short-chain fatty acids (SCFAs). Antibiotic-treated mice were used to demonstrate the key role of endogenous gut microbiota. Here, we found that 5-ASA alleviated dextran sulfate sodium (DSS)-induced colitis in mice. Moreover, 5-ASA significantly repaired the intestinal barrier. At the molecular level, 5-ASA markedly raised the expression of tight junction proteins including JAM-A and occludin and cell proliferation marker Ki-67 in mice. In addition, bacterial 16S rRNA gene sequencing and bioinformatics analysis showed that 5-ASA significantly modulated the DSS-induced gut bacterial dysbiosis. In detail, it stimulated the growth of protective bacteria belonging to Faecalibaculum and Dubosiella, which were negatively correlated with colitis parameters, and blocked the expansion of pro-inflammatory bacteria such as Escherichia-Shigella and Oscillibacter, which were positively correlated with colitis in mice. Meanwhile, 5-ASA increased the cecal acetate level. Most notably, 5-ASA was no longer able to treat colitis and reverse gut barrier dysfunction in antibiotic-treated mice that lacked endogenous gut microbiota. Our data suggested that the anti-inflammatory activity of 5-ASA required the inherent intestinal flora, and the gut microbiota was a potential and effective target for the treatment of ulcerative colitis.

Colorectal Cancer in Inflammatory Bowel Disease: A Review of the Role of Gut Microbiota and Bacterial Biofilms in Disease Pathogenesis

The risk of colorectal cancer [CRC] is increased in patients with inflammatory bowel disease [IBD], particularly in extensive ulcerative colitis [UC] and Crohn's colitis. Gut microbiota have been implicated in the pathogenesis of CRC via multiple mechanisms, including the release of reactive oxygen species and genotoxins, and induction of inflammation, as well as activation of the immune response. Gut microbiota can enhance their carcinogenic and proinflammatory properties by organising into biofilms, potentially making them more resistant to the host's immune system and to antibiotics. Colonic biofilms have the capacity to invade colonic tissue and accelerate tumorigenesis in tumour-prone models of mice. In the context of IBD, the prevalence of biofilms has been estimated to be up to 95%. Although the relationship between chronic inflammation and molecular mediators that contribute to IBD-associated CRC is well established, the role of gut microbiota and biofilms in this sequence is not fully understood. Because CRC can still arise in the absence of histological inflammation, there is a growing interest in identifying chemopreventive agents against IBD-associated CRC. Commonly used in the treatment of UC, 5-aminosalicylates have antimicrobial and anticarcinogenic properties that might have a role in the chemoprevention of CRC via the inhibition or modulation of carcinogenic gut microbiota and potentially of biofilm formation. Whether biologics and other IBD-targeted therapies can decrease the progression towards dysplasia and CRC, via mechanisms independent of inflammation, is still unknown. Further research is warranted to identify potential new microbial targets in therapy for chemoprevention of dysplasia and CRC in IBD.

Current understandings of colibactin regulation

The biosynthetic machinery for the production of colibactin is encoded by 19 genes (clbA - S) within the pks pathogenicity island harboured by many E. coli of the B2-phylogroup. Colibactin is a potent genotoxic metabolite which causes DNA-damage and which has potential roles in microbial competition and fitness of pks+ bacteria. Colibactin has also been strongly implicated in the development of colorectal cancer. Given the genotoxicity of colibactin and the metabolic cost of its synthesis, the regulatory system governing the clb cluster is accordingly highly complex, and many of the mechanisms remain to be elucidated. In this review we summarise the current understanding of regulation of colibactin biosynthesis by internal molecular components and how these factors are modulated by signals from the external environment.

Crohn's disease-associated Escherichia coli LF82 in the gut damage of germ-free honeybees: A laboratory study

Escherichia coli LF82 (LF82) is associated with Crohn's disease. The simplicity and genetic maneuverability of honeybees' gut microbiota make them suitable for studying host-microbe interactions. To understand the interaction between LF82 and host gut, LF82 was used to infect germ-free honeybees (Apis mellifera) orally. We found that LF82 successfully colonized the gut and shortened the lifespan of germ-free bees. LF82 altered the gut structure and significantly increased gut permeability. RT-qPCR showed that LF82 infection activated anti-infective immune pathways and upregulated the mRNAs levels of antimicrobial peptides in the gut of germ-free bees. The gut transcriptome showed that LF82 significantly upregulated genes involved in Notch signaling, adhesion junctions, and Toll and Imd signaling pathways and downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, protein digestion and absorption, and tyrosine metabolism. In conclusion, the human-derived enteropathogenic bacterium LF82 can successfully colonize the gut of germ-free honeybees and cause enteritis-like changes, which provides an ideal model organism for revealing the pathogenesis of bacterial-associated diseases.

Salicylic acids and pathogenic bacteria: new perspectives on an old compound

Salicylic acids have been used in human and veterinary medicine for their anti-pyretic, anti-inflammatory, and analgesic properties for centuries. A key role of salicylic acid-immune modulation in response to microbial infection-was first recognized during studies of their botanical origin. The effects of salicylic acid on bacterial physiology are diverse. In many cases, they impose selective pressures leading to development of cross-resistance to antimicrobial compounds. Initial characterization of these interactions was in Escherichia coli, where salicylic acid activates the multiple antibiotic resistance (mar) operon, resulting in decreased antibiotic susceptibility. Studies suggest that stimulation of the mar phenotype presents similarly in closely related Enterobacteriaceae. Salicylic acids also affect virulence in many opportunistic pathogens by decreasing their ability to form biofilms and increasing persister cell populations. It is imperative to understand the effects of salicylic acid on bacteria of various origins to illuminate potential links between environmental microbes and their clinically relevant antimicrobial-resistant counterparts. This review provides an update on known effects of salicylic acid and key derivatives on a variety of bacterial pathogens, offers insights to possible potentiation of current treatment options, and highlights cellular regulatory networks that have been established during the study of this important class of medicines.

Interplay between inflammatory bowel disease therapeutics and the gut microbiome reveals opportunities for novel treatment approaches

Inflammatory bowel disease (IBD) is a complex heterogeneous disorder defined by recurring chronic inflammation of the gastrointestinal tract, attributed to a combination of factors including genetic susceptibility, altered immune response, a shift in microbial composition/microbial insults (infection/exposure), and environmental influences. Therapeutics generally used to treat IBD mainly focus on the immune response and include non-specific anti-inflammatory and immunosuppressive therapeutics and targeted therapeutics aimed at specific components of the immune system. Other therapies include exclusive enteral nutrition and emerging stem cell therapies. However, in recent years, scientists have begun to examine the interplay between these therapeutics and the gut microbiome, and we present this information here. Many of these therapeutics are associated with alterations to gut microbiome composition and functionality, often driving it toward a "healthier profile" and preclinical studies have revealed that such alterations can play an important role in therapeutic efficacy. The gut microbiome can also improve or hinder IBD therapeutic efficacy or generate undesirable metabolites. For certain IBD therapeutics, the microbiome composition, particularly before treatment, may serve as a biomarker of therapeutic efficacy. Utilising this information and manipulating the interactions between the gut microbiome and IBD therapeutics may enhance treatment outcomes in the future and bring about new opportunities for personalised, precision medicine.

Role of adherent invasive Escherichia coli in pathogenesis of inflammatory bowel disease

Gut microbiota imbalances play an important role in inflammatory bowel disease (IBD), but no single pathogenic microorganism critical to IBD that is specific to the IBD terminal ileum mucosa or can invade intestinal epithelial cells has been found. Invasive Escherichia coli (E. coli) adhesion to macrophages is considered to be closely related to the pathogenesis of inflammatory bowel disease. Further study of the specific biological characteristics of adherent invasive E. coli (AIEC) may contribute to a further understanding of IBD pathogenesis. This review explores the relationship between AIEC and the intestinal immune system, discusses the prevalence and relevance of AIEC in Crohn's disease and ulcerative colitis patients, and describes the relationship between AIEC and the disease site, activity, and postoperative recurrence. Finally, we highlight potential therapeutic strategies to attenuate AIEC colonization in the intestinal mucosa, including the use of phage therapy, antibiotics, and anti-adhesion molecules. These strategies may open up new avenues for the prevention and treatment of IBD in the future.

Probiotic-Based Intervention in the Treatment of Ulcerative Colitis: Conventional and New Approaches

Although there are number of available therapies for ulcerative colitis (UC), many patients are unresponsive to these treatments or experience secondary failure during treatment. Thus, the development of new therapies or alternative strategies with minimal side effects is inevitable. Strategies targeting dysbiosis of gut microbiota have been tested in the management of UC due to the unquestionable role of gut microbiota in the etiology of UC. Advanced molecular analyses of gut microbiomes revealed evident dysbiosis in UC patients, characterized by a reduced biodiversity of commensal microbiota. Administration of conventional probiotic strains is a commonly applied approach in the management of the disease to modify the gut microbiome, improve intestinal barrier integrity and function, and maintain a balanced immune response. However, conventional probiotics do not always provide the expected health benefits to a patient. Their benefits vary significantly, depending on the type and stage of the disease and the strain and dose of the probiotics administered. Their mechanism of action is also strain-dependent. Recently, new candidates for potential next-generation probiotics have been discovered. This could bring to light new approaches in the restoration of microbiome homeostasis and in UC treatment in a targeted manner. The aim of this paper is to provide an updated review on the current options of probiotic-based therapies, highlight the effective conventional probiotic strains, and outline the future possibilities of next-generation probiotic and postbiotic supplementation and fecal microbiota transplantation in the management of UC.

Anticolitic activity of prodigiosin loaded with selenium nanoparticles on acetic acid-induced colitis in rats

Ulcerative colitis (UC) is a chronic autoimmune inflammatory disease associated with extensive mucosal damage. Prodigiosins (PGs) are natural bacterial pigments with well-known antioxidant and immunosuppressive properties. In the current study, we examined the possible protective effect of PGs loaded with selenium nanoparticles (PGs-SeNPs) against acetic acid (AcOH)-induced UC in rats. Thirty-five rats were separated into five equal groups with seven animals/group: control, UC, PGs (300 mg/kg), sodium selenite (Na2SeO3, 2 mg/kg), PGs-SeNPs (0.5 mg/kg), and 5-aminosalicylates (5-ASA, 200 mg/kg). Interestingly, PGs-SeNPs administration lessened colon inflammation and mucosal damage as indicated by inhibiting inflammatory markers upon AcOH injection. Furthermore, PGs-SeNPs improved the colonic antioxidant capacity and prevented oxidative insults as evidenced by the upregulation of Nrf2- and its downstream antioxidants along with the decreased pro-oxidants [reactive oxygen species (ROS), carbonyl protein, malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), and nitric oxide (NO] in the colon tissue. Furthermore, PGs-SeNPs protected intestinal cell loss through blockade apoptotic cascade by decreasing pro-apoptotic proteins [Bcl-2-associated X protein (Bax) and caspase-3] and increasing anti-apoptotic protein, B cell lymphoma 2 (Bcl2). Collectively, PGs-SeNPs could be used as an alternative anti-colitic option due to their strong anti-inflammatory, antioxidant, and anti-apoptotic activities.

Microenvironmental Factors that Shape Bacterial Metabolites in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a significant global health problem that involves chronic intestinal inflammation and can involve severe comorbidities, including intestinal fibrosis and inflammation-associated colorectal cancer (CRC). Disease-associated alterations to the intestinal microbiota often include fecal enrichment of Enterobacteriaceae, which are strongly implicated in IBD development. This dysbiosis of intestinal flora accompanies changes in microbial metabolites, shaping host:microbe interactions and disease risk. While there have been numerous studies linking specific bacterial taxa with IBD development, our understanding of microbial function in the context of IBD is limited. Several classes of microbial metabolites have been directly implicated in IBD disease progression, including bacterial siderophores and genotoxins. Yet, our microbiota still harbors thousands of uncharacterized microbial products. In-depth discovery and characterization of disease-associated microbial metabolites is necessary to target these products in IBD treatment strategies. Towards improving our understanding of microbiota metabolites in IBD, it is important to recognize how host relevant factors influence microbiota function. For example, changes in host inflammation status, metal availability, interbacterial community structure, and xenobiotics all play an important role in shaping gut microbial ecology. In this minireview, we outline how each of these factors influences gut microbial function, with a specific focus on IBD-associated Enterobacteriaceae metabolites. Importantly, we discuss how altering the intestinal microenvironment could improve the treatment of intestinal inflammation and associated disorders, like intestinal fibrosis and CRC.

Tackling the Threat of Cancer Due to Pathobionts Producing Colibactin: Is Mesalamine the Magic Bullet?

Colibactin is a genotoxin produced primarily by Escherichia coli harboring the genomic pks island (pks⁺ E. coli). Pks⁺ E. coli cause host cell DNA damage, leading to chromosomal instability and gene mutations. The signature of colibactin-induced mutations has been described and found in human colorectal cancer (CRC) genomes. An inflamed intestinal environment drives the expansion of pks⁺ E. coli and promotes tumorigenesis. Mesalamine (i.e., 5-aminosalycilic acid), an effective anti-inflammatory drug, is an inhibitor of the bacterial polyphosphate kinase (PPK). This drug not only inhibits the production of intestinal inflammatory mediators and the proliferation of CRC cells, but also limits the abundance of E. coli in the gut microbiota and diminishes the production of colibactin. Here, we describe the link between intestinal inflammation and colorectal cancer induced by pks⁺ E. coli. We discuss the potential mechanisms of the pleiotropic role of mesalamine in treating both inflammatory bowel diseases and reducing the risk of CRC due to pks⁺ E. coli.

Ostarine attenuates pyocyanin in Pseudomonas aeruginosa by interfering with quorum sensing systems

Antimicrobial resistance has been an increasingly serious threat to global public health. Anti-virulence strategies are being developed to manage antibiotic resistance because they apply a lower selective pressure for antimicrobial-resistant pathogens than that created using traditional bactericides. We aimed to discover novel small molecules that can reduce the production of virulence factors in Pseudomonas aeruginosa and determine the mechanism of action underlying these effects. A clinical compound library was screened, and ostarine was identified as a potential anti-virulence agent. The effects of ostarine were studied via antimicrobial susceptibility testing, bacterial growth assays, pyocyanin quantitation assays, transcriptomic analysis, quorum sensing signal molecule quantification, and real-time PCR assays. Ostarine treatment significantly decreased the synthesis of pyocyanin without any bactericidal action. Besides, ostarine treatment did not affect the relative growth rate and cell morphology of bacteria. Treatment with ostarine interfered with quorum sensing by decreasing the transcription of genes associated with quorum sensing systems and the production of signalling molecules. The inhibition of ostarine on pyocyanin production and gene expression can be alleviated when signalling molecules were supplemented externally. Overall, ostarine may act as a novel anti-virulence agent that can attenuate P. aeruginosa pyocyanin by interfering with quorum sensing systems.

Clinical characteristics and long-term outcome of E. coli-associated granulomatous ileocolitis in dogs: five cases (2010-2014)

OBJECTIVES

To describe the clinical characteristics and long-term outcome of Escherichia coli-associated granulomatous ileocolitis in dogs.

METHODS

Retrospective review of medical records from dogs with periodic acid-Schiff positive (PAS+) granulomatous ileocolitis and mucosally invasive E. coli in the ileum and colon. Initial bacterial colonisation was evaluated using fluorescence in situ hybridization (FISH) in all dogs and corroborated with colonic and/or ileal culture, when performed.

RESULTS

Four boxer dogs and 1 French Bulldog with PAS+ granulomatous ileocolitis (GIC) were evaluated. All dogs had chronic diarrhoea refractory to empirical therapy. Ileocolonoscopy revealed mucosal haemorrhage and ulceration in the ileum (3/4) and colon (5/5). E. coli were visualised as clusters within the ileal and colonic mucosa. Complete (CR, 4/5) or partial (PR, 1/5) clinical response to fluoroquinolones was noted in all dogs within 30 days. CR was sustained in three of four dogs (median disease-free interval 40 months, range 16 to 60). Two dogs relapsed while receiving fluoroquinolones. Repeat biopsy isolated multidrug-resistant, mucosally invasive E. coli in the ileum (1/2) and colon (2/2). Targeted antimicrobial therapy was associated with long-term PR (78 months) in both dogs.

CLINICAL SIGNIFICANCE

Concurrent E. coli-associated granulomatous inflammation in the ileum and colon did not impart a poor clinical outcome or lack of response to the conventional standard of care for granulomatous colitis in dogs that were aggressively diagnosed and treated. Clinical outcome was influenced by antimicrobial resistance, with response dependent upon antimicrobial therapy informed by susceptibility testing.

Microbiota and Drug Response in Inflammatory Bowel Disease

A mutualistic relationship between the composition, function and activity of the gut microbiota (GM) and the host exists, and the alteration of GM, sometimes referred as dysbiosis, is involved in various immune-mediated diseases, including inflammatory bowel disease (IBD). Accumulating evidence suggests that the GM is able to influence the efficacy of the pharmacological therapy of IBD and to predict whether individuals will respond to treatment. Additionally, the drugs used to treat IBD can modualate the microbial composition. The review aims to investigate the impact of the GM on the pharmacological therapy of IBD and vice versa. The GM resulted in an increase or decrease in therapeutic responses to treatment, but also to biotransform drugs to toxic metabolites. In particular, the baseline GM composition can help to predict if patients will respond to the IBD treatment with biologic drugs. On the other hand, drugs can affect the GM by incrementing or reducing its diversity and richness. Therefore, the relationship between the GM and drugs used in the treatment of IBD can be either beneficial or disadvantageous.

5-Aminosalicylic Acid Ameliorates Colitis and Checks Dysbiotic Escherichia coli Expansion by Activating PPAR-γ Signaling in the Intestinal Epithelium

An expansion of Enterobacterales in the fecal microbiota is a microbial signature of dysbiosis that is linked to many noncommunicable diseases, including ulcerative colitis. Here, we used Escherichia coli, a representative of the Enterobacterales, to show that its dysbiotic expansion during colitis can be remediated by modulating host epithelial metabolism.

5-Aminosalicylic acid (5-ASA), a peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, is a widely used first-line medication for the treatment of ulcerative colitis, but its anti-inflammatory mechanism is not fully resolved. Here, we show that 5-ASA ameliorates colitis in dextran sulfate sodium (DSS)-treated mice by activating PPAR-γ signaling in the intestinal epithelium. DSS-induced colitis was associated with a loss of epithelial hypoxia and a respiration-dependent luminal expansion of Escherichia coli, which could be ameliorated by treatment with 5-ASA. However, 5-ASA was no longer able to reduce inflammation, restore epithelial hypoxia, or blunt an expansion of E. coli in DSS-treated mice that lacked Pparg expression specifically in the intestinal epithelium. These data suggest that the anti-inflammatory activity of 5-ASA requires activation of epithelial PPAR-γ signaling, thus pointing to the intestinal epithelium as a potential target for therapeutic intervention in ulcerative colitis.

The Polyphosphate Kinase of Escherichia coli Is Required for Full Production of the Genotoxin Colibactin

Colibactin induces DNA damage in mammalian cells and has been linked to the virulence of Escherichia coli and the promotion of colorectal cancer (CRC). By looking for mutants attenuated in the promoter activity of clbB encoding one of the key enzymes for the production of colibactin, we found that a mutant of the gene coding for the polyphosphate kinase (PPK) produced less colibactin than the parental strain. We observed this phenotype in different strains ranging from pathogens responsible for meningitis, urinary tract infection, or mouse colon carcinogenesis to the probiotic Nissle 1917. We confirmed the role of PPK by using an inhibitor of PPK enzymatic activity, mesalamine (also known as 5-aminosalicylic acid). Interestingly, mesalamine has a local anti-inflammatory effect on the epithelial cells of the colon and is used to treat inflammatory bowel disease (IBD). Upon treatment with mesalamine, a decreased genotoxicity of colibactin-producing E. coli was observed both on epithelial cells and directly on purified DNA. This demonstrates the direct effect of mesalamine on bacteria independently from its anti-inflammatory effect on eukaryotic cells. Our results suggest that the mechanisms of action of mesalamine in treating IBD and preventing CRC could also lie in the inhibition of colibactin production. All in all, we demonstrate that PPK is required for the promoter activity of clbB and the production of colibactin, which suggests that PPK is a promising target for the development of anticolibactin and antivirulence strategies.IMPORTANCE Colibactin-producing E. coli induces DNA damage in eukaryotic cells and promotes tumor formation in mouse models of intestinal inflammation. Recent studies have provided strong evidence supporting the causative role of colibactin in human colorectal cancer (CRC) progression. Therefore, it is important to understand the regulation of the production of this genotoxin. Here, we demonstrate that polyphosphate kinase (PPK) is required for the promoter activity of clbB and the production of colibactin. Interestingly, PPK is a multifunctional player in bacterial virulence and stress responses and has been proposed as a new target for developing antimicrobial medicine. We observed inhibition of colibactin production by using a previously identified PPK inhibitor (i.e., mesalamine, an anti-inflammatory drug commonly prescribed for inflammatory bowel diseases). These data brought us a new perspective on the regulatory network of colibactin production and provided us a clue for the development of anticolibactin strategies for CRC treatment/prophylaxis.

Escherichia coli-associated granulomatous colitis in dogs treated according to antimicrobial susceptibility profiling

Background

Eradication of intramucosal Escherichia coli correlates with remission of periodic acid‐Schiff‐positive E coli‐associated granulomatous colitis (GC). Treatment failures attributed to multidrug resistant (MDR) bacteria necessitate alternative approaches.

Hypothesis/objectives

Determine clinical outcome of E coli‐associated GC in dogs treated based on antimicrobial susceptibility profiling and characterize E coli phylogeny and resistance mechanisms.

Animals

Twenty Boxers and 4 French Bulldogs with E coli‐associated GC.

Methods

Culture, antimicrobial susceptibility profiling, and molecular characterization of E coli were performed and response to treatment was evaluated.

Results

Initial biopsy sample culture yielded fluoroquinolone‐sensitive (FQ‐S) E coli from 9/24 dogs and fluoroquinolone‐resistant (FQ‐R) E coli from 15/24. All but 1 FQ‐R E coli were MDR with susceptibility to macrophage‐penetrating antimicrobials restricted to carbapenems in 13/15 dogs. Of 22/24 treated based on susceptibility profiling, 8/9 FQ‐S dogs had complete initial clinical response (CR) during fluoroquinolone (FQ) treatment, whereas 9/13 FQ‐R dogs had complete or partial response (PR) during meropenem or doxycycline treatment. In 5/9 FQ‐S and 12/13 FQ‐R dogs with follow‐up ≥3 months, CR was sustained in 5/5 FQ‐S (median, 25 months; range, 4‐46) whereas 6/12 FQ‐R had long‐term CR (median, 59 months; range 15‐102), 4/12 PR (median, 19 months; range, 5‐65), and 2/12 had no response (NR). Four dogs with long‐term follow‐up died within 4 years of diagnosis, including 2 euthanized for refractory colitis. Escherichia coli were genetically diverse. Fluoroquinolone resistance was associated with mutations in gyrA and parC, with plasmid‐mediated resistance less common.

Conclusions and Clinical Importance

Antimicrobial treatment guided by susceptibility profiling was associated with positive long‐term outcomes in >80% of cases. Fluoroquinolone‐resistance was widespread and not clonal. Further study is required to optimize treatment for dogs with MDR E coli‐associated GC.

Involvement of Fusobacterium Species in Oral Cancer Progression: A Literature Review Including Other Types of Cancer

Chronic inflammation caused by infections has been suggested to be one of the most important cause of cancers. It has recently been shown that there is correlation between intestinal bacteria and cancer development including metastasis. As over 700 bacterial species exist in an oral cavity, it has been concerning that bacterial infection may cause oral cancer. However, the role of bacteria regarding tumorigenesis of oral cancer remains unclear. Several papers have shown that Fusobacterium species deriving the oral cavities, especially, play a crucial role for the development of colorectal and esophageal cancer. F. nucleatum is a well-known oral bacterium involved in formation of typical dental plaque on human teeth and causing periodontal diseases. The greatest characteristic of F. nucleatum is its ability to adhere to various bacteria and host cells. Interestingly, F. nucleatum is frequently detected in oral cancer tissues. Moreover, detection of F. nucleatum is correlated with the clinical stage of oral cancer. Although the detailed mechanism is still unclear, Fusobacterium species have been suggested to be associated with cell adhesion, tumorigenesis, epithelial-to-mesenchymal transition, inflammasomes, cell cycle, etc. in oral cancer. In this review, we introduce the reports focused on the association of Fusobacterium species with cancer development and progression including oral, esophageal, and colon cancers.

Short Chain Fatty Acids Modulate the Growth and Virulence of Pathosymbiont Escherichia coli and Host Response

Short chain fatty acids (SCFA), principally acetate, propionate, and butyrate, are produced by fermentation of dietary fibers by the gut microbiota. SCFA regulate the growth and virulence of enteric pathogens, such as enterohemorrhagic E. coli (EHEC), Klebsiella and Salmonella. We sought to investigate the impact of SCFA on growth and virulence of pathosymbiont E. coli associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC), and their role in regulating host responses to bacterial infection in vitro. We found that under ileal conditions (pH = 7.4; 12 mM total SCFA), SCFA significantly (p < 0.05) potentiate the growth and motility of pathosymbiont E. coli. However, under colonic conditions (pH = 6.5; 65 to 123 mM total SCFA), SCFA significantly (p < 0.05) inhibit growth in a pH dependent fashion (up to 60%), and down-regulate virulence gene expression (e.g., fliC, fimH, htrA, chuA, pks). Functional analysis reveals that colonic SCFA significantly (p < 0.05) inhibit E. coli motility (up to 95%), infectivity (up to 60%), and type 1 fimbria-mediated agglutination (up to 50%). In addition, SCFA significantly (p < 0.05) inhibit the activation of NF-κB, and IL-8 production by epithelial cells. Our findings provide novel insights on the role of the regional chemical microenvironment in regulating the growth and virulence of pathosymbiont E. coli and opportunities for therapeutic intervention.

Fusobacterium nucleatum promotes colorectal cancer metastasis by modulating KRT7-AS/KRT7

The enrichment of Fusobacterium nucleatum (Fn) has been identified in CRC patients and associated with worse outcomes. However, whether Fn was involved in the metastasis of CRC was not well determined. Here, we found that the abundance of Fn was significantly increased in CRC patients with lymph nodes metastasis. To further clarify the role of Fn in CRC metastasis, we performed transwell and wound healing assays after incubating CRC cell lines with or without Fn and injected Fn-treated or untreated CRC cells into nude mice via tail vein. The results indicated that Fn infection promoted CRC cells migration in vitro, as well as lung metastasis in vivo. Interestingly, colonization of Fn was detected in metastatic lung lesions of nude mice by fluorescence in situ hybridization. Mechanistically, RNA sequencing and validation study revealed that Fn significantly upregulated the expression of long non-coding RNA Keratin7-antisense (KRT7-AS) and Keratin7 (KRT7) in CRC cells. Importantly, Fn-induced CRC lung metastasis was attenuated by the depletion of KRT7-AS. In addition, KRT7-AS facilitated CRC cells migration by upregulating KRT7. Subsequently, we found that NF-κB signaling pathway was involved in the upregulation of KRT7-AS upon Fn infection. In conclusion, Fn infection upregulated KRT7-AS/KRT7 by activating NF-κB pathway, which promoted CRC cell migration in vitro and metastasis in vivo.

Integrating omics for a better understanding of Inflammatory Bowel Disease: a step towards personalized medicine

Background

Inflammatory Bowel Disease (IBD) is a multifactorial chronic disease. Understanding only one aspect of IBD pathogenesis does not reflect the complex nature of IBD nor will it improve its clinical management. Therefore, it is vital to dissect the interactions between the different players in IBD pathogenesis in order to understand the biology of the disease and enhance its clinical outcomes.

Aims

To provide an overview of the available omics data used to assess the potential mechanisms through which various players are contributing to IBD pathogenesis and propose a precision medicine model to fill the current knowledge gap in IBD.

Results

Several studies have reported microbial dysbiosis, immune and metabolic dysregulation in IBD patients, however, this data is not sufficient to create signatures that can differentiate between the disease subtypes or between disease relapse and remission.

Conclusions

We summarized the current knowledge in the application of omics in IBD patients, and we showed that the current knowledge gap in IBD hinders the improvements of clinical decision for treatment as well as the prediction of disease relapse. We propose one way to fill this gap by implementing integrative analysis of various omics datasets generated from one patient at a single time point.

Sexual Dimorphism of Gut Microbiota Dictates Therapeutics Efficacy of Radiation Injuries

Accidental or iatrogenic ionizing radiation exposure precipitates acute and chronic radiation injuries. The traditional paradigm of mitigating radiotherapy-associated adverse side effects has ignored the gender-specific dimorphism of patients' divergent responses. Here, the effects of sexual dimorphism on curative efficiencies of therapeutic agents is examined in murine models of irradiation injury. Oral gavage of simvastatin ameliorates radiation-induced hematopoietic injury and gastrointestinal tract dysfunction in male mice, but adversely deteriorates these radiation syndromes in female animals. In a sharp contrast, feeding animals with high-fat diet (HFD) elicites explicitly contrary results. High-throughput sequencing of microbial 16S rRNA, host miRNA, and mRNA shows that simvastatin or HFD administration preventes radiation-altered enteric bacterial taxonomic structure, preserves miRNA expression profile, and reprogrammes the spectrum of mRNA expression in small intestines of male or female mice, respectively. Notably, faecal microbiota transplantation of gut microbes from opposite sexual donors abrogates the curative effects of simvastatin or HFD in respective genders of animals. Together, these findings demonstrate that curative efficiencies of therapeutic strategies mitigating radiation toxicity might be dependent on the gender of patients, thus simvastatin or HFD might be specifically useful for fighting against radiation toxicity in a sex-dependent fashion partly based on sex-distinct gut microbiota composition in preclinical settings.