Campylobacter concisus - A new player in intestinal disease

d-aspartate, an amino-acid important for human health, supports anaerobic respiration in several Campylobacter species

Despite being classified as microaerophilic microorganisms, most Campylobacter species can grow anaerobically, using formate or molecular hydrogen (H2) as electron donors, and various nitrogenous and sulfurous compounds as electron acceptors. Herein, we showed that both l-asparagine (l-Asn) and l-aspartic acid (l-Asp) bolster H2-driven anaerobic growth in several Campylobacter species, whereas the d-enantiomer form of both asparagine (d-Asn) and aspartic acid (d-Asp) only increased anaerobic growth in Campylobacter concisus strain 13826 and Campylobacter ureolyticus strain NCTC10941. A gene annotated as racD encoding for a putative d/l-Asp racemase was identified in the genome of both strains. Disruption of racD in Cc13826 resulted in the inability of the mutant strain to use either d-enantiomer during anaerobic growth. Hence, our results suggest that the racD gene is required for campylobacters to use either d-Asp or d-Asn. The use of d-Asp by various human opportunistic bacterial pathogens, including C. concisus, C. ureolyticus, and also possibly select strains of Campylobacter gracilis, Campylobacter rectus and Campylobacter showae, is significant, because d-Asp is an important signal molecule for both human nervous and neuroendocrine systems. To our knowledge, this is the first report of pathogens scavenging a d-amino acid essential for human health.

Characterization of viable but nonculturable state of Campylobacter concisus

Campylobacter concisus is an opportunistic bacterial pathogen linked with a range of human diseases. The objective of this study was to investigate the viable but nonculturable (VBNC) state of the bacterium. To induce the VBNC state, C. concisus cells were maintained in sterilized phosphate-buffered saline at 4°C for three weeks. The VBNC cells were monitored using quantitative analysis by propidium monoazide (PMAxx) coupled with quantitative real-time PCR (PMAxx-qPCR), targeting the DNA gyrase subunit B gene. The results demonstrated that C. concisus ATCC 51562 entered the VBNC state in 15 days, while ATCC 51561 entered the VBNC state in 9 days. The viable cell counts, assessed by PMAxx-qPCR, consistently remained close to the initial level of 107 CFU ml-1, indicating a substantial portion of the cell population had entered the VBNC state. Notably, morphological analysis revealed that the VBNC cells became coccoid and significantly smaller. The cells could be resuscitated through a temperature increase in the presence of a highly nutritious growth medium. In conclusion, under environmental stress, most C. concisus cells converted to the VBNC state. The VBNC state of C. concisus may be important for its environmental survival and spread, and the presence of VBNC forms should be considered in environmental and clinical monitoring.

Uridine Bisphosphonates Differentiate Phosphoglycosyl Transferase Superfamilies

Complex bacterial glycoconjugates drive interactions between pathogens, symbionts, and their human hosts. Glycoconjugate biosynthesis is initiated at the membrane interface by phosphoglycosyl transferases (PGTs), which catalyze the transfer of a phosphosugar from a soluble uridine diphosphosugar (UDP-sugar) substrate to a membrane-bound polyprenol-phosphate (Pren-P). The two distinct superfamilies of PGT enzymes (polytopic and monotopic) show striking differences in their structure and mechanism. We designed and synthesized a series of uridine bisphosphonates (UBPs), wherein the diphosphate of the UDP and UDP-sugar is replaced by a substituted methylene bisphosphonate (CXY-BPs; X/Y = F/F, Cl/Cl, (S)-H/F, (R)-H/F, H/H, CH3/CH3). UBPs and UBPs incorporating an N-acetylglucosamine (GlcNAc) substituent at the β-phosphonate were evaluated as inhibitors of a polytopic PGT (WecA from Thermotoga maritima) and a monotopic PGT (PglC from Campylobacter jejuni). Although CHF-BP most closely mimics diphosphate with respect to its acid/base properties, the less basic CF2-BP conjugate more strongly inhibited PglC, whereas the more basic CH2-BP analogue was the strongest inhibitor of WecA. These surprising differences indicate different modes of ligand binding for the different PGT superfamilies, implicating a modified P-O- interaction with the structural Mg2+. For the monoPGT enzyme, the two diastereomeric CHF-BP conjugates, which feature a chiral center at the Pα-CHF-Pβ carbon, also exhibited strikingly different binding affinities and the inclusion of GlcNAc with the native α-anomer configuration significantly improved binding affinity. UBP-sugars are thus revealed as informative new mechanistic probes of PGTs that may aid development of novel antibiotic agents for the exclusively prokaryotic monoPGT superfamily.

Characterization of PglJ, a Glycosyltransferase in the Campylobacter concisus N-Linked Protein Glycosylation Pathway that Expands Glycan Diversity

The Campylobacter genus of Gram-negative bacteria is characterized by the expression of N-linked protein glycosylation (pgl) pathways. As Campylobacter concisus is an emerging human pathogen, a better understanding of the variation of the biosynthetic pathways across the genus is necessary to identify the relationships between protein glycosylation and disease. The pgl pathways of C. concisus strains have been reported to diverge from other Campylobacter in steps after the biosynthesis of N-acetylgalactosamine-α1,3-N,N'-diacetylbacillosamine-α-1-diphosphate undecaprenyl (GalNAc-diNAcBac-PP-Und), which is catalyzed by PglC and PglA, a phosphoglycosyltransferase (PGT) and a glycosyltransferase (GT), respectively. Here we characterize the PglJ GTs from two strains of C. concisus. Chemical synthesis was employed to access the stereochemically defined glycan donor substrates, uridine diphosphate N-acetyl-d-galactosaminuronic acid (UDP-GalNAcA) and uridine diphosphate N-acetyl-d-glucosaminuronic acid (UDP-GlcNAcA), to allow biochemical investigation of PglJ. Evidence for the PglJ substrate specificity structural determinants for the C6″ carboxylate-containing sugar was obtained through variant-based biochemical assays. Additionally, characterization of a UDP-sugar dehydrogenase encoded in the pgl operon, which is similar to the Pseudomonas aeruginosa WbpO responsible for the oxidization of a UDP-HexNAc to UDP-HexNAcA, supports the availability of a UDP-HexNAcA substrate for a GT that incorporates the modified sugar and provides evidence for the presence of a HexNAcA in the N-linked glycan. Utilizing sequence similarity network (SSN) analysis, we identified conserved sequence motifs among PglJ glycosyltransferases, shedding light on substrate preferences and offering predictive insights into enzyme functions across the Campylobacter genus. These studies now allow detailed characterization of the later steps in the pgl pathway in C. concisus strains and provide insights into enzyme substrate specificity determinants for glycan assembly enzymes.

Specificity determinants revealed by the structure of glycosyltransferase Campylobacter concisus PglA

In selected Campylobacter species, the biosynthesis of N-linked glycoconjugates via the pgl pathway is essential for pathogenicity and survival. However, most of the membrane-associated GT-B fold glycosyltransferases responsible for diversifying glycans in this pathway have not been structurally characterized which hinders the understanding of the structural factors that govern substrate specificity and prediction of resulting glycan composition. Herein, we report the 1.8 Å resolution structure of Campylobacter concisus PglA, the glycosyltransferase responsible for the transfer of N-acetylgalatosamine (GalNAc) from uridine 5'-diphospho-N-acetylgalactosamine (UDP-GalNAc) to undecaprenyl-diphospho-N,N'-diacetylbacillosamine (UndPP-diNAcBac) in complex with the sugar donor GalNAc. This study identifies distinguishing characteristics that set PglA apart within the GT4 enzyme family. Computational docking of the structure in the membrane in comparison to homologs points to differences in interactions with the membrane-embedded acceptor and the structural analysis of the complex together with bioinformatics and site-directed mutagenesis identifies donor sugar binding motifs. Notably, E113, conserved solely among PglA enzymes, forms a hydrogen bond with the GalNAc C6″-OH. Mutagenesis of E113 reveals activity consistent with this role in substrate binding, rather than stabilization of the oxocarbenium ion transition state, a function sometimes ascribed to the corresponding residue in GT4 homologs. The bioinformatic analyses reveal a substrate-specificity motif, showing that Pro281 in a substrate binding loop of PglA directs configurational preference for GalNAc over GlcNAc. This proline is replaced by a conformationally flexible glycine, even in distant homologs, which favor substrates with the same stereochemistry at C4, such as glucose. The signature loop is conserved across all Campylobacter PglA enzymes, emphasizing its importance in substrate specificity.

The role of the host-microbiome and metabolomics in sarcoidosis

Sarcoidosis is a complex inflammatory fibrotic disease that affects multiple organ systems. It is characterized by the infiltration of lymphocytes and mononuclear phagocytes, which form non-caseating granulomas in affected organs. The lungs and intrathoracic lymph nodes are the most commonly affected organs. The underlying cause of sarcoidosis is unknown, but it is believed to occur in genetically predisposed individuals who are exposed to pathogenic organisms, environmental contaminants, or self and non-self-antigens. Recent research has suggested that the microbiome may play a role in the development of respiratory conditions, including sarcoidosis. Additionally, metabolomic studies have identified potential biomarkers for monitoring sarcoidosis progression. This review will focus on recent microbiome and metabolomic findings in sarcoidosis, with the goal of shedding light on the pathogenesis and possible diagnostic and therapeutic approaches.

The Campylobacter concisus BisA protein plays a dual role: oxide-dependent anaerobic respiration and periplasmic methionine sulfoxide repair

IMPORTANCE

Campylobacter concisus is an excellent model organism to study respiration diversity, including anaerobic respiration of physiologically relevant N-/S-oxides compounds, such as biotin sulfoxide, dimethyl sulfoxide, methionine sulfoxide (MetO), nicotinamide N-oxide, and trimethylamine N-oxide. All C. concisus strains harbor at least two, often three, and up to five genes encoding for putative periplasmic Mo/W-bisPGD-containing N-/S-oxide reductases. The respective role (substrate specificity) of each enzyme was studied using a mutagenesis approach. One of the N/SOR enzymes, annotated as "BisA", was found to be essential for anaerobic respiration of both N- and S-oxides. Additional phenotypes associated with disruption of the bisA gene included increased sensitivity toward oxidative stress and elongated cell morphology. Furthermore, a biochemical approach confirmed that BisA can repair protein-bound MetO residues. Hence, we propose that BisA plays a role as a periplasmic methionine sulfoxide reductase. This is the first report of a Mo/W-bisPGD-enzyme supporting both N- or S-oxide respiration and protein-bound MetO repair in a pathogen.

Investigating the Significance of Non-jejuni/coli Campylobacter Strains in Patients with Diarrhea

Campylobacter is one of the most commonly reported foodborne bacteria worldwide. Although Campylobacter jejuni and Campylobacter coli have been reported to be responsible for the great majority of campylobacteriosis, the burden of infections by species other than C. jejuni and C. coli have been increasing as a result of a transition to diagnostic test methods that enable the isolation of emerging species. The aim of the present study was to recover C. jejuni, C. coli, and emerging species from the stool samples of 500 patients with gastroenteritis and 100 healthy subjects via the use of a filtration method and culture techniques using Butzler agar and mCCDA under a microaerobic or hydrogen-enriched atmosphere, identify the species by multiplex PCR methods and assess the significance of emerging species in enteric diseases. Thirty-one (6.2%) Campylobacter spp. were isolated from the stool samples of diarrheic patients but none from healthy individuals. Of 31 isolates, 21 (67.8%), nine (29%), and one (3.2%) were identified as C. jejuni, C. coli, and Campylobacter concisus by multiplex PCR, respectively. The filtration method was superior to the culture technique using mCCDA under a microaerobic atmosphere. C. concisus was evaluated as the etiology of gastroenteritis as a result of laboratory and clinical evaluations. The present study was the first to indicate that emerging Campylobacter species are rarely detected and C. concisus is linked to acute gastroenteritis in Turkey where additional studies are warranted to clarify the significance of emerging species in gastroenteritis.

Characteristics of the esophageal microbiome in patients with achalasia and its changes before and after peroral endoscopic myotomy: A pilot study

BACKGROUND AND AIM

Achalasia often presents with chronic food stasis and fermentation in the esophageal lumen, which may lead to alterations of the esophageal microbiome, with associated mucosal inflammation and dysplastic changes. The study aims to evaluate the characteristics of the esophageal microbiome in achalasia and changes of the esophageal microbiome before and after peroral endoscopic myotomy (POEM).

METHODS

This is a prospective case-control study. This study enrolled patients with achalasia and asymptomatic subjects as control group. Endoscopic brushing for esophageal microbiome collection was performed in all subjects, with additional follow-up endoscopy and brushing 3 months after POEM in achalasia patients. The composition of the esophageal microbiome was determined and compared between (1) achalasia patients and asymptomatic controls and (2) achalasia patients before and after POEM.

RESULTS

Thirty-one achalasia patients (mean age 53.5 ± 16.2 years; male 45.2%) and 15 controls were analyzed. We observed a distinct esophageal microbial community structure in achalasia patients, with increased Firmicutes and decreased Proteobacteria when compared with the control group at the phylum level. The discriminating enriched genera in achalasia patients were Lactobacillus, followed by Megasphaera and Bacteroides, and the amount of Lactobacillus was associated with the severity of achalasia. Twenty patients were re-examined after POEM, and a high prevalence of erosive esophagitis (55%) was noted, alongside an increase in genus Neisseria and decrease in Lactobacillus and Bacteroides.

CONCLUSIONS

The altered esophageal microenvironment in achalasia leads to dysbiosis with a high abundance of genus Lactobacillus. Increased Neisseria and decreased Lactobacillus were observed after POEM. The long-term effect of microbial changes warrants further study.

An integrated computational approach to infer therapeutic targets from Campylobacter concisus and peptidomimetic based inhibition of its pyrimidine metabolism pathway

Campylobacter concisus is a commensal of the human oral flora that has been allied with persistent diarrhea and inflammatory bowel disease (IBD). In children under the age of two, Campylobacter infections are common in the developing countries and have frequently been associated with mortality. They are becoming a prevalent cause of bacterial diarrhea in early adulthood in developed countries as well. The need for identifying new therapeutic targets and drugs is crucial for curbing such infections. Therefore, we identified 18 cytoplasmic potential therapeutic candidates against the type strain of C. concisus and deoxycytidine triphosphate deaminase (dCTP deaminase), involved in pyrimidine synthesis was selected for screening of peptidomimetic inhibitors (n > 30,000 peptidomimetics) against it. To the best of our knowledge, this target has not been studied for Campylobacter spp. Three potent inhibitors of this enzyme were prioritized i.e. peptidomimetic 27, 64, and 150. Dynamics simulation of 100 ns was carried out to validate findings for top-scored inhibitors along with physiology-based pharmacokinetics to estimate behavior in human body and predict dosing parameters. This verification demonstrates a first-in-human pharmacokinetic simulation for these peptidomimetics and can help enhance confidence in these peptide-like structures. Moiety 27 (IUPAC name: 5-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-N-{[2-(2-methoxyethyl)-1-oxo-1H,2H,3H,4H-pyrrolo[1,2-a]pyrazin-3-yl]methyl}furan-2-carboxamide), 64 (IUPAC name: 3-(2-methylpropyl)-1-{3-[5-(5-oxo-1-phenylpyrrolidin-3-yl)-1,2,4-oxadiazol-3-yl]phenyl}urea), and 150 (IUPAC name: N-(3-methoxypropyl)-1-[6-(4-methylphenyl)-4H,6H,7H-[1,2,3]triazolo[4,3-c][1,4]oxazine-3-carbonyl]piperidine-4-carboxamide) were identified as potent inhibitors of C. concisus.Communicated by Ramaswamy H. Sarma.

Campylobacter concisus gastritis masquerading as Helicobacter pylori on gastric biopsy

OBJECTIVE

Campylobacter concisus is a Gram-negative rod closely related to Helicobacter pylori. We sought to identify gastric biopsies positive for C. concisus that had been misdiagnosed as H. pylori gastritis in our routine surgical pathology practice.

MATERIALS AND METHODS

We performed a retrospective review of gastric biopsies in our regional microbiology and pathology electronic records to identify cases that were submitted for H. pylori testing in which C. consicus was identified on culture and how many had concurrent biopsies sent to pathology for histologic assessment over a two-year period (2017-2018). Pathologic findings in the gastric biopsies were reviewed and immunohistochemical staining for H. pylori was performed.

RESULTS

50 of 2191 gastric biopsy specimens submitted to microbiology in 2017-18 grew C. concisus (2.3%), compared to 168 in which H. pylori was identified (7.7%). Twenty-eight cases had concurrent histology. A total of four cases (three from 2017 and one from 2018) demonstrated organisms morphologically identical to H. pylori in the H&E sections, of which all were H. pylori immunoreactive.

CONCLUSIONS

Our case series is the first to demonstrate that C. concisus can mimic H. pylori gastritis in routine biopsy pathology.

Backbone-Anchoring, Solid-Phase Synthesis Strategy To Access a Library of Peptidouridine-Containing Small Molecules

Nucleoside diphosphate sugar (NDP-sugar) substrates provide the inspiration for nucleoside analogue inhibitor scaffolds. By employing solid-phase synthesis, we provide a method to access a library of peptidouridine inhibitors with both minimal compound handling and purification steps. Specifically, this strategy is exemplified by generating uridine diphosphate sugar (UDP-sugar) mimics, which allow for compound elaboration by altering the dipeptide composition, the N-terminal linkage, and a pendant aryl group. To exemplify the versatility, 41 unique nucleoside analogues are presented.

Association of Fungi and Archaea of the Gut Microbiota with Crohn's Disease in Pediatric Patients-Pilot Study

The composition of bacteria is often altered in Crohn’s disease (CD), but its connection to the disease is not fully understood. Gut archaea and fungi have recently been suggested to play a role as well. In our study, the presence and number of selected species of fungi and archaea in pediatric patients with CD and healthy controls were evaluated. Stool samples were collected from children with active CD (n = 54), non-active CD (n = 37) and control subjects (n = 33). The prevalence and the number of selected microorganisms were assessed by real-time PCR. The prevalence of Candida tropicalis was significantly increased in active CD compared to non-active CD and the control group (p = 0.011 and p = 0.036, respectively). The number of Malassezia spp. cells was significantly lower in patients with active CD compared to the control group, but in non-active CD, a significant increase was observed (p = 0.005 and p = 0.020, respectively). There were no statistically significant differences in the colonization by archaea. The obtained results indicate possible correlations with the course of the CD; however, further studies of the entire archeobiome and the mycobiome are necessary in order to receive a complete picture.

Multi-omics of the esophageal microenvironment identifies signatures associated with progression of Barrett's esophagus

BACKGROUND

The enrichment of Gram-negative bacteria of oral origin in the esophageal microbiome has been associated with the development of metaplasia. However, to date, no study has comprehensively assessed the relationships between the esophageal microbiome and the host.

METHODS

Here, we examine the esophageal microenvironment in gastro-esophageal reflux disease and metaplasia using multi-omics strategies targeting the microbiome and host transcriptome, followed by targeted culture, comparative genomics, and host-microbial interaction studies of bacterial signatures of interest.

RESULTS

Profiling of the host transcriptome from esophageal mucosal biopsies revealed profound changes during metaplasia. Importantly, five biomarkers showed consistent longitudinal changes with disease progression from reflux disease to metaplasia. We showed for the first time that the esophageal microbiome is distinct from the salivary microbiome and the enrichment of Campylobacter species as a consistent signature in disease across two independent cohorts. Shape fitting and matrix correlation identified associations between the microbiome and host transcriptome profiles, with a novel co-exclusion relationship found between Campylobacter and napsin B aspartic peptidase. Targeted culture of Campylobacter species from the same cohort revealed a subset of isolates to have a higher capacity to survive within primary human macrophages. Comparative genomic analyses showed these isolates could be differentiated by specific genomic features, one of which was validated to be associated with intracellular fitness. Screening for these Campylobacter strain-specific signatures in shotgun metagenomics data from another cohort showed an increase in prevalence with disease progression. Comparative transcriptomic analyses of primary esophageal epithelial cells exposed to the Campylobacter isolates revealed expression changes within those infected with strains with high intracellular fitness that could explain the increased likelihood of disease progression.

CONCLUSIONS

We provide a comprehensive assessment of the esophageal microenvironment, identifying bacterial strain-specific signatures with high relevance to progression of metaplasia.

Campylobacter concisus as a pathogen of primary canaliculitis: a case report

A 73-year-old woman presented to our hospital with a 1-year history of epiphora associated with discharge on the left eye. On the first examination, there was a swelling in the medial part of the left lower eyelid associated with a cystic change along the lacrimal canaliculus. On digital compression, there was an expression of a yellow mucopurulent discharge from the left-lower punctum. A culture test of the discharge showed Campylobacter concisus (1+), Gemella morbillorum (1+), Fusobacterium nucleatum (1+), and Porphyromonas gingivalis (2+). Complete removal of the canaliculoliths was done with a curette. Dacryoendoscopic examination showed a substantially dilated horizontal canaliculus accompanied with granulation and fibrous tissues on the left-lower side. An ofloxacin ointment-coated bicanalicular tube was inserted. Also, an oral antibiotic was administered for 14 days after surgery. At a 3-month follow-up, the patient did not have any symptoms associated with canaliculitis.

The "Gum-Gut" Axis in Inflammatory Bowel Diseases: A Hypothesis-Driven Review of Associations and Advances

In modern medicine, the oral cavity has often been viewed as a passive conduit to the upper airways and gastrointestinal tract; however, its connection to the rest of the body has been increasingly explored over the last 40 years. For several diseases, the periodontium and gingiva are at the center of this oral-systemic link. Over 50 systemic conditions have been specifically associated with gingival and periodontal inflammation, including inflammatory bowel diseases (IBD), which have recently been elevated from simple "associations" to elegant, mechanistic investigations. IBD and periodontitis have been reported to impact each other's progression via a bidirectional relationship whereby chronic oral or intestinal inflammation can impact the other; however, the precise mechanisms for how this occurs remain unclear. Classically, the etiology of gingival inflammation (gingivitis) is oral microbial dysbiosis in the subgingival crevice that can lead to destructive periodontal disease (periodontitis); however, the current understanding of gingival involvement in IBD is that it may represent a separate disease entity from classical gingivitis, arising from mechanisms related to systemic inflammatory activation of niche-resident immune cells. Synthesizing available evidence, we hypothesize that once established, IBD can be driven by microbiomial and inflammatory changes originating specifically from the gingival niche through saliva, thereby worsening IBD outcomes and thus perpetuating a vicious cycle. In this review, we introduce the concept of the "gum-gut axis" as a framework for examining this reciprocal relationship between the periodontium and the gastrointestinal tract. To support and explore this gum-gut axis, we 1) provide a narrative review of historical studies reporting gingival and periodontal manifestations in IBD, 2) describe the current understanding and advances for the gum-gut axis, and 3) underscore the importance of collaborative treatment and research plans between oral and GI practitioners to benefit this patient population.

Alterations of the salivary and fecal microbiome in patients with primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic, progressive liver disease known for its frequent concurrence with inflammatory bowel disease. PSC can progress to cirrhosis, end-stage liver disease, hepatobiliary cancer, and/or colorectal cancer. The etiopathogenesis of PSC remains poorly understood, and, as such, pharmacotherapy has yet to be definitively established. Little is known about the salivary microbiome in PSC and PSC-IBD. This study aimed to evaluate the oral microbiome of patients with PSC, with association to these patient's fecal microbial composition.

METHODS

Saliva, fecal samples and Food Frequency Questionnaires were collected from 35 PSC patients with or without concomitant inflammatory bowel disease and 30 age- and BMI-matched healthy volunteers. 16S rRNA gene sequencing was performed using Illumina MiSeq platform.

RESULTS

The salivary microbial signature of PSC was significantly altered as compared to healthy controls, independent of concomitant IBD, and was comprised of 19 significantly altered species, of which, eight species were consistently overrepresented in both fecal and saliva of patients with PSC, including Veillonella, Scardovia and Streptococcus.

CONCLUSIONS

PSC is characterized by microbial dysbiosis in the gut and the salivary microbiome, independently from IBD. The PSC dysbiotic signature includes a reduction in autochthonous bacteria and an increased relative abundance of pathogenic bacteria, including an invasion of oral bacteria to the gut. PSC is a strong modulator of the microbial profile, in the gut and the oral microbiome. These results may lead to the development of biomarkers for screening and early diagnosis or the development of personalized medicine in PSC.

Influence of Intratumor Microbiome on Clinical Outcome and Immune Processes in Prostate Cancer

Simple Summary

While the intratumor microbiome has been largely unexplored in relation to prostate cancer development, our research shows that microbes may play an anti-tumor or pro-tumor role to significantly alter clinical course in prostate cancer patients. We found that the presence and absence of specific microbes are strongly correlated with known biomarkers of prostate cancer, including increased androgen receptor expression, prostate-specific antigen level, immune-associated gene dysregulation, stem-cell related gene overexpression, cancer pathways, and known chromosomal alterations. Our results provide important insight on potential mechanisms by which intratumor microbes may greatly contribute to prostate cancer progression and prognosis. We hope our results can be validated in future studies, and the key microbes that we identified can be used as effective targets for more specialized prebiotic and probiotic treatments for prostate cancer.

Abstract

Although 1 in 9 American men will receive a diagnosis of prostate cancer (PC), most men with this diagnosis will not die from it, as most PCs are indolent. However, there is a subset of patients in which the once-indolent PC becomes metastatic and eventually, fatal. In this study, we analyzed microbial compositions of intratumor bacteria in PC to determine the influence of the microbiome on metastatic growth. Using large-scale RNA-sequencing data and corresponding clinical data, we correlated the abundance of microbes to immune pathways and PC risk factors, identifying specific microbes that either significantly deter or contribute to cancer aggressiveness. Interestingly, most of the microbes we found appeared to play anti-tumor roles in PC. Since these anti-tumor microbes were overrepresented in tumor samples, we believe that microbes thrive in the tumor microenvironment, outcompete cancer cells, and directly mitigate tumor growth by recruiting immune cells. These include Listeria monocytogenes, Methylobacterium radiotolerans JCM 2831, Xanthomonas albilineans GPE PC73, and Bradyrhizobium japonicum, which are negatively correlated with Gleason score, Tumor-Node-Metastasis (TNM) stage, prostate-specific antigen (PSA) level, and Androgen Receptor (AR) expression, respectively. We also identified microbes that contribute to tumor growth and are positively correlated with genomic alterations, dysregulated immune-associated (IA) genes, and prostate cancer stem cells (PCSC) genes.

Molecular Hydrogen Metabolism: a Widespread Trait of Pathogenic Bacteria and Protists

Pathogenic microorganisms use various mechanisms to conserve energy in host tissues and environmental reservoirs. One widespread but often overlooked means of energy conservation is through the consumption or production of molecular hydrogen (H2). Here, we comprehensively review the distribution, biochemistry, and physiology of H2 metabolism in pathogens. Over 200 pathogens and pathobionts carry genes for hydrogenases, the enzymes responsible for H2 oxidation and/or production. Furthermore, at least 46 of these species have been experimentally shown to consume or produce H2 Several major human pathogens use the large amounts of H2 produced by colonic microbiota as an energy source for aerobic or anaerobic respiration. This process has been shown to be critical for growth and virulence of the gastrointestinal bacteria Salmonella enterica serovar Typhimurium, Campylobacter jejuni, Campylobacter concisus, and Helicobacter pylori (including carcinogenic strains). H2 oxidation is generally a facultative trait controlled by central regulators in response to energy and oxidant availability. Other bacterial and protist pathogens produce H2 as a diffusible end product of fermentation processes. These include facultative anaerobes such as Escherichia coli, S Typhimurium, and Giardia intestinalis, which persist by fermentation when limited for respiratory electron acceptors, as well as obligate anaerobes, such as Clostridium perfringens, Clostridioides difficile, and Trichomonas vaginalis, that produce large amounts of H2 during growth. Overall, there is a rich literature on hydrogenases in growth, survival, and virulence in some pathogens. However, we lack a detailed understanding of H2 metabolism in most pathogens, especially obligately anaerobic bacteria, as well as a holistic understanding of gastrointestinal H2 transactions overall. Based on these findings, we also evaluate H2 metabolism as a possible target for drug development or other therapies.

Pathogenomics of Emerging Campylobacter Species

Campylobacter is among the four main causes of gastroenteritis worldwide and has increased in both developed and developing countries over the last 10 years. The vast majority of reported Campylobacter infections are caused by Campylobacter jejuni and, to a lesser extent, C. coli; however, the increasing recognition of other emerging Campylobacter pathogens is urgently demanding a better understanding of how these underestimated species cause disease, transmit, and evolve. In parallel to the enhanced clinical awareness of campylobacteriosis due to improved diagnostic protocols, the application of high-throughput sequencing has increased the number of whole-genome sequences available to dozens of strains of many emerging campylobacters. This has allowed for comprehensive comparative pathogenomic analyses for several species, such as C. fetus and C. concisus These studies have started to reveal the evolutionary forces shaping their genomes and have brought to light many genomic features related to pathogenicity in these neglected species, promoting the development of new tools and approaches relevant for clinical microbiology. Despite the need for additional characterization of genomic diversity in emerging campylobacters, the increasing body of literature describing pathogenomic studies on these species deserves to be discussed from an integrative perspective. This review compiles the current knowledge and highlights future work toward deepening our understanding about genome dynamics and the mechanisms governing the evolution of pathogenicity in emerging Campylobacter species, which is urgently needed to develop strategies to prevent or control the spread of these pathogens.

Experiences from multiplex PCR diagnostics of faeces in hospitalised patients: clinical significance of Enteropathogenic Escherichia coli (EPEC) and culture negative campylobacter

BACKGROUND

In hospitalised patients with diarrhoea a positive campylobacter stool Polymerase Chain Reaction (PCR) test with negative culture results as well as Enteropathogenic Escherichia coli (EPEC) positive stool PCRs, challenges the clinician and may lead the unexperienced clinician astray. The aim of the study was to elucidate the clinical significance of positive Campylobacter and/or EPEC test results in hospitalised patients with diarrhoea.

METHODS

We conducted a retrospective case-case study. Case groups with 1) EPEC only and 2) EPEC in combination with any other pathogen in the PCR multiplex array, 3) PCR positive/culture negative Campylobacter, and 4) PCR positive/culture positive Campylobacter were compared. Medical records were reviewed and cases classified according to pre-specified clinical criteria as infectious gastroenteritis or non-infectious causes for diarrhoea. We analyzed the association between laboratory findings (the 4 subgroups) and the pre-specified clinical classification. We further sequenced culture negative campylobacter samples and tested EPEC for bundle forming pilus A (bfpA) gene, distinguishing typical from atypical EPEC.

RESULTS

A total of 291 patients were included, 169 were PCR positive for Campylobacter and 122 for EPEC. For both pathogens, co-infections were more common in culture negative/PCR positive samples than in culture positive samples. Clinical characteristics differed significantly in and between groups. Campylobacter culture positive patients had very high prevalence of characteristics of acute infectious gastroenteritis, whereas patients with PCR positive test results only often had an alternative explanation for their diarrhoea. Culture positives were almost exclusively C. jejuni/coli, whereas in culture negatives, constituting a third of the total PCR positives, C. concisus was the most frequent species. The vast majority of EPEC only positives had documented non-infectious factors that could explain diarrhoea. The EPEC co-infected group mimicked the culture positive campylobacter group, with most patients fulfilling the infectious gastroenteritis criteria.

CONCLUSIONS

In hospitalised patients, positive PCR results for campylobacter and EPEC should be interpreted in a clinical context after evaluation of non-infectious diarrhoea associated conditions, and cannot be used as a stand-alone diagnostic tool.

Tongue coating microbiome as a potential biomarker for gastritis including precancerous cascade

The development of gastritis is associated with an increased risk of gastric cancer. Current invasive gastritis diagnostic methods are not suitable for monitoring progress. In this work based on 78 gastritis patients and 50 healthy individuals, we observed that the variation of tongue-coating microbiota was associated with the occurrence and development of gastritis. Twenty-one microbial species were identified for differentiating tongue-coating microbiomes of gastritis and healthy individuals. Pathways such as microbial metabolism in diverse environments, biosynthesis of antibiotics and bacterial chemotaxis were up-regulated in gastritis patients. The abundance of Campylobacter concisus was found associated with the gastric precancerous cascade. Furthermore, Campylobacter concisus could be detected in tongue coating and gastric fluid in a validation cohort containing 38 gastritis patients. These observations provided biological evidence of tongue diagnosis in traditional Chinese medicine, and indicated that tongue-coating microbiome could be a potential non-invasive biomarker, which might be suitable for long-term monitoring of gastritis.

Diversity of transducer-like proteins (Tlps) in Campylobacter

Campylobacter transducer-like proteins (Tlps), also known as methyl-accepting chemotaxis proteins (MCPs), are associated with virulence as well as niche and host adaptation. While functional attributes of these proteins are being elucidated, little has been published regarding their sequence diversity or chromosomal locations and context, although they appear to define invertible regions within Campylobacter jejuni genomes. Genome assemblies for several species of Campylobacter were obtained from the publicly available NCBI repositories. Genomes from all isolates were obtained from GenBank and assessed for Tlp content, while data from isolates with complete, finished genomes were used to determine the identity of Tlps as well as the gene content of putative invertible elements (IEs) in C. jejuni (Cj) and C. coli (Cc). Tlps from several Campylobacter species were organized into a nomenclature system and novel Tlps were defined and named for Cj and Cc. The content of Tlps appears to be species-specific, though diverse within species. Cj and Cc carried overlapping, related Tlp content, as did the three C. fetus subspecies. Tlp1 was detected in 88% of Cj isolates and approximately 43% of Cc, and was found in a different conserved chromosomal location and genetic context in each species. Tlp1 and Tlp 3 predominated in genomes from Cj whereas other Tlps were detected less frequently. Tlp13 and Tlp20 predominated in genomes from Cc while some Cj/Cc Tlps were not detected at all. Tlps 2–4 and 11–20 were less frequently detected and many showed sequence heterogeneity that could affect substrate binding, signal transduction, or both. Tlps other than Tlp1, 7, and 10 had substantial sequence identity in the C-terminal half of the protein, creating chromosomal repeats potentially capable of mediating the inversion of large chromosomal DNA. Cj and Cc Tlps were both found in association with only 14 different genes, indicating a limited genomic context. In Cj these Tlps defined IEs that were for the most part found at a single chromosomal location and comprised of a conserved set of genes. Cc IEs were situated at very different chromosomal locations, had different structures than Cj IEs, and were occasionally incomplete, therefore not capable of inversion. Tlps may have a role in Campylobacter genome structure and dynamics as well as acting as chemoreceptors mediating chemotactic responses.

Campylobacter Concisus and Acute Gastroenteritis in Children: Lack of Association

The role of Campylobacter concisus as a cause of acute gastroenteritis remains to be demonstrated. This prospective study includes 184 cases and 176 controls. It shows no evidence that C. concisus plays a role in acute gastroenteritis. Considering the very low prevalence in cases and controls, if there is an etiologic link, it would be moderate and difficult to demonstrate.

Campylobacter Concisus and Its Effect on the Expression of CDX1 and COX2

Background: Barrett’s oesophagus (BO) is a pre-malignant condition in which normal squamous epithelium of the lower oesophagus and gastresophageal junction is replaced by columnar cells and progress to oesophageal adenocarcinoma. The increase burden of oesophagus cancer morbidity and mortality worldwide make study of factors involved in the pathogenesis of BO essential. However, most of studies that examine the environmental risk factors associated with increased incidence and prevalence of BO have largely ignored the potential role of bacteria in disease aetiology. Aims: This study examined the role of Campylobacter concisus isolated from Barrett’s and adenocarcinoma patient samples as one of possible environmental factors in the progression of Barrett’s oesophagus to oesophagus adenocarcinoma. Methods: We focused on the effect of C. concisus on the expression caudal type homeobox 1 gene (CDX1) and cyclooxygenase-2 (COX-2) in three BO cell lines using quantitative real-time PCR. In addition, the attachment and invasion characteristics of C. concisus were also tested. Results: Results showed that C. concisus had a strong attachment to the cell lines and induce the expression of CDX1 in Barrett’s cell lines in a time-dependent manner. Conclusion: Findings indicate that C. concisus could be as a new challenge in the progression of BO to adenocarcinoma.

The possible role of bacteria, viruses, and parasites in initiation and exacerbation of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a prolonged and disabling functional gastrointestinal disorder with the incidence rate of 18% in the world. IBS could seriously affect lifetime of patients and cause high economic burden on the community. The pathophysiology of the IBS is hardly understood, whereas several possible mechanisms, such as visceral hypersensitivity, irregular gut motility, abnormal brain-gut relations, and the role of infectious agents, are implicated in initiation and development of this syndrome. Different studies demonstrated an alteration in B-lymphocytes, mast cells (MC), T-lymphocytes, and cytokine concentrations in intestinal mucosa or systemic circulation that are likely to contribute to the formation of the IBS. Therefore, IBS could be developed in those with genetic predisposition. Infections' role in initiation and exacerbation of IBS has been investigated by quite several clinical studies; moreover, the possible role of some pathogens in development and exacerbation of this disease has been described. It appears that the main obligatory pathogens correspond with the IBS disease, Clostridium difficile, Escherichia coli, Mycobacterium avium subspecies paratuberculosis, Campylobacter concisus, Campylobacter jejuni, Chlamydia trachomatis, Helicobacter pylori, Pseudomonas aeruginosa, Salmonella spp, Shigella spp, and viruses, particularly noroviruses. A number of pathogenic parasites (Blastocystis, Dientamoeba fragilis, and Giardia lamblia) may also be involved in the progression and exacerbation of the disease. Based on the current knowledge, the current study concludes that the most common bacterial, viral, and parasitic pathogens may be involved in the development and progression of IBS.

Site-directed mutagenesis of Campylobacter concisus respiratory genes provides insight into the pathogen's growth requirements

Campylobacter concisus is an emerging human pathogen found throughout the entire human oral-gastrointestinal tract. The ability of C. concisus to colonize diverse niches of the human body indicates the pathogen is metabolically versatile. C. concisus is able to grow under both anaerobic conditions and microaerophilic conditions. Hydrogen (H2) has been shown to enhance growth and may even be required. Analysis of several C. concisus genome sequences reveals the presence of two sets of genes encoding for distinct hydrogenases: a H2-uptake-type ("Hyd") complex and a H2-evolving hydrogenase ("Hyf"). Whole cells hydrogenase assays indicate that the former (H2-uptake) activity is predominant in C. concisus, with activity among the highest we have found for pathogenic bacteria. Attempts to generate site-directed chromosomal mutants were partially successful, as we could disrupt hyfB, but not hydB, suggesting that H2-uptake, but not H2-evolving activity, is an essential respiratory pathway in C. concisus. Furthermore, the tetrathionate reductase ttrA gene was inactivated in various C. concisus genomospecies. Addition of tetrathionate to the medium resulted in a ten-fold increase in cell yield for the WT, while it had no effect on the ttrA mutant growth. To our knowledge, this is the first report of mutants in C. concisus.

Stunted childhood growth is associated with decompartmentalization of the gastrointestinal tract and overgrowth of oropharyngeal taxa

Linear growth delay (stunting) affects roughly 155 million children under the age of 5 years worldwide. Treatment has been limited by a lack of understanding of the underlying pathophysiological mechanisms. Stunting is most likely associated with changes in the microbial community of the small intestine, a compartment vital for digestion and nutrient absorption. Efforts to better understand the pathophysiology have been hampered by difficulty of access to small intestinal fluids. Here, we describe the microbial community found in the upper gastrointestinal tract of stunted children aged 2-5 y living in sub-Saharan Africa. We studied 46 duodenal and 57 gastric samples from stunted children, as well as 404 fecal samples from stunted and nonstunted children living in Bangui, Central African Republic, and in Antananarivo, Madagascar, using 16S Illumina Amplicon sequencing and semiquantitative culture methods. The vast majority of the stunted children showed small intestinal bacterial overgrowth dominated by bacteria that normally reside in the oropharyngeal cavity. There was an overrepresentation of oral bacteria in fecal samples of stunted children, opening the way for developing noninvasive diagnostic markers. In addition, Escherichia coli/Shigella sp. and Campylobacter sp. were found to be more prevalent in stunted children, while Clostridia, well-known butyrate producers, were reduced. Our data suggest that stunting is associated with a microbiome "decompartmentalization" of the gastrointestinal tract characterized by an increased presence of oropharyngeal bacteria from the stomach to the colon, hence challenging the current view of stunting arising solely as a consequence of small intestine overstimulation through recurrent infections by enteric pathogens.

Novel Campylobacter concisus lipooligosaccharide is a determinant of inflammatory potential and virulence

The pathogenicity of Campylobacter concisus, increasingly found in the human gastrointestinal (GI) tract, is unclear. Some studies indicate that its role in GI conditions has been underestimated, whereas others suggest that the organism has a commensal-like phenotype. For the enteropathogen C. jejuni, the lipooligosaccharide (LOS) is a main driver of virulence. We investigated the LOS structure of four C. concisus clinical isolates and correlated the inflammatory potential of each isolate with bacterial virulence. Mass spectrometric analyses of lipid A revealed a novel hexa-acylated diglucosamine moiety with two or three phosphoryl substituents. Molecular and fragment ion analysis indicated that the oligosaccharide portion of the LOS had only a single phosphate and lacked phosphoethanolamine and sialic acid substitution, which are hallmarks of the C. jejuni LOS. Consistent with our structural findings, C. concisus LOS and live bacteria induced less TNF-α secretion in human monocytes than did C. jejuni Furthermore, the C. concisus bacteria were less virulent than C. jejuni in a Galleria mellonella infection model. The correlation of the novel lipid A structure, decreased phosphorylation, and lack of sialylation along with reduced inflammatory potential and virulence support the significance of the LOS as a determinant in the relative pathogenicity of C. concisus.

Incidence of Campylobacter concisus and C. ureolyticus in traveler's diarrhea cases and asymptomatic controls in Nepal and Thailand

Background

Campylobacter concisus and C. ureolyticus have emerged in recent years as being associated with acute and prolonged gastroenteritis and implicated in the development of inflammatory bowel diseases. However, there are limited data on the prevalence of these microorganisms in Southeast Asia. In this study, 214 pathogen-negative stool samples after laboratory examination for common enteric pathogens to include C. jejuni and C. coli by culture from two case–control traveler’s diarrhea (TD) studies conducted in Thailand (cases = 26; controls = 30) and Nepal (cases = 83; controls = 75) respectively were assayed by PCR for the detection of Campylobacter 16S rRNA and two specific heat shock protein genes specific for C. concisus (cpn60) and C. ureolyticus (Hsp60) respectively.

Results

Campylobacter 16S rRNA was detected in 28.5% (61/214) of the pathogen-negative TD stool samples (CIWEC Travel Medicine Clinic, Kathmandu, Nepal: cases = 36, control = 14; Bamrungrad International Hospital, Bangkok, Thailand: cases = 9, controls = 2). C. consisus was identified significantly more often in TD cases in Nepal (28.9%; 24/83) as compared to controls (4%; 3/75) (OR = 9.76; 95% CI 2.80–34.02; P = 0.0003) while C. consisus was detected in only two cases (2/26; 7.7%) and none of the controls stool samples from Thailand. C. ureolyticus was detected in four cases (4.8%; 4/83) and four controls (5.3%; 4/75) and in one case (3.8%; 1/26) and one control (3.1%; 1/30) from Nepal and Thailand respectively. C. jejuni and C. coli were isolated in 18.3 and 3.4% of the cases and in 4.0 and 1.4% of the controls in stool samples from both Thailand and Nepal respectively while C. concisus nor C. ureolyticus were not tested for in these samples.

Conclusion

These findings suggest that C. concisus potentially is a pathogen associated with TD in Nepal. To our knowledge, this is the first report of C. concisus and C. ureolyticus detected from traveler’s diarrhea cases from travelers to Nepal and Thailand.

Towards understanding clinical campylobacter infection and its transmission: time for a different approach?

Campylobacter spp. are among the most commonly diagnosed causes of human infection. Methods for detection of the 29 campylobacter species have mainly focused on cultivation of the thermophilic species. More than 99% of clinical campylobacter isolates notified in the UK in the recent past have been from faecal samples and associated with gastroenteritis. Campylobacter enteritis notifications in temperate zones show a seasonal increase during the summer months with a sharp decrease in the winter months, a pattern which remains incompletely understood. The striking seasonality in the expression of many human genes, some concerned with inflammation and immunity, suggests a need for further study of the host regarding the temporal distribution of many human infections, including campylobacteriosis. A tendency for campylobacter to enter a non-cultivable state under adverse conditions effects a reduction in the number of isolations. A Polymerase Chain Reaction (PCR)-based screening approach for the presence of the Campylobacter genus and followed by speciation has provided some insight into the limitations of cultivation for campylobacter, also allowing the discovery of new species. The increased sensitivity of the PCR-based approach over culture-based methods may make it difficult for the laboratory to differentiate asymptomatic campylobacter carriage from clinical campylobacter infection in non-sterile body sites. Campylobacter infection depends on a combination of host factors, and on acquisition of a suitably virulent strain with a tropism for human epithelium. The possibility of persistence of campylobacter in a viable but non-culturable latent form in the human body may also require further investigation. The scope of this review includes a discussion of current methods for diagnosing acute campylobacter infection and for detecting campylobacter in water and foodstuffs. The review also questions the prevailing view that poultry is the most common source of campylobacteriosis.

The human gastrointestinal tract and oral microbiota in inflammatory bowel disease: a state of the science review

Inflammatory bowel disease (IBD) includes a spectrum of diseases from ulcerative colitis (UC) to Crohn's disease (CD). Many studies have addressed the changes in the microbiota of individuals affected by UC and CD. A decrease in biodiversity and depletion of the phyla Bacteroidetes and Firmicutes has been reported, among others. Changes in microbial composition also result in changes in the metabolites generated in the gut from microbial activity that may involve the amount of butyrate and other metabolites such as H₂ S being produced. Other factors such as diet, age, or medication need to be taken into consideration when studying dysbiosis associated with IBD. Diverse bacterial species have been associated specifically or non-specifically to IBD, but none of them have been demonstrated to be its ethiological agent. Recent studies also suggest that micro-eukaryotic populations may also be altered in IBD patients. Last, but not least, viruses, and specially bacteriophages, can play a role in controlling microbial populations in the gastrointestinal tract. This may affect both bacterial diversity and metabolism, but possible implications for IBD still remain to be solved. Dysbiosis in the oral microbiome associated with IBD remains an emerging field for future research.

Campylobacter concisus pathotypes induce distinct global responses in intestinal epithelial cells

The epithelial response to the opportunistic pathogen Campylobacter concisus is poorly characterised. Here, we assessed the intestinal epithelial responses to two C. concisus strains with different virulence characteristics in Caco-2 cells using RNAseq, and validated a subset of the response using qPCR arrays. C. concisus strains induced distinct response patterns from intestinal epithelial cells, with the toxigenic strain inducing a significantly more amplified response. A range of cellular functions were significantly regulated in a strain-specific manner, including epithelial-to-mesenchymal transition (NOTCH and Hedgehog), cytoskeletal remodeling, tight junctions, inflammatory responses and autophagy. Pattern recognition receptors were regulated, including TLR3 and IFI16, suggesting that nucleic acid sensing was important for epithelial recognition of C. concisus. C. concisus zonula occludens toxin (ZOT) was expressed and purified, and the epithelial response to the toxin was analysed using RNAseq. ZOT upregulated PAR2 expression, as well as processes related to tight junctions and cytoskeletal remodeling. C. concisus ZOT also induced upregulation of TLR3, pro-inflammatory cytokines IL6, IL8 and chemokine CXCL16, as well as the executioner caspase CASP7. Here, we characterise distinct global epithelial responses to C. concisus strains, and the virulence factor ZOT, and provide novel information on mechanisms by which this bacterium may affect the host.

Polyphosphate and associated enzymes as global regulators of stress response and virulence in Campylobacter jejuni

Campylobacter jejuni (C. jejuni), a Gram-negative microaerophilic bacterium, is a predominant cause of bacterial foodborne gastroenteritis in humans worldwide. Despite its importance as a major foodborne pathogen, our understanding of the molecular mechanisms underlying C. jejuni stress survival and pathogenesis is limited. Inorganic polyphosphate (poly P) has been shown to play significant roles in bacterial resistance to stress and virulence in many pathogenic bacteria. C. jejuni contains the complete repertoire of enzymes required for poly P metabolism. Recent work in our laboratory and others have demonstrated that poly P controls a plethora of C. jejuni properties that impact its ability to survive in the environment as well as to colonize/infect mammalian hosts. This review article summarizes the current literature on the role of poly P in C. jejuni stress survival and virulence and discusses on how poly P-related enzymes can be exploited for therapeutic/prevention purposes. Additionally, the review article identifies potential areas for future investigation that would enhance our understanding of the role of poly P in C. jejuni and other bacteria, which ultimately would facilitate design of effective therapeutic/preventive strategies to reduce not only the burden of C. jejuni-caused foodborne infections but also of other bacterial infections in humans.

Clinical relevance of infections with zoonotic and human oral species of Campylobacter

Genus Campylobacter has been recognized as a causative bacterial agent of animal and human diseases. Human Campylobacter infections have caused more concern. Campylobacters can be classified into two groups in terms of their original host: zoonotic and human oral species. The major zoonotic species are Campylobacter jejuni and Campylobacter coli, which mostly reside in the intestines of avian species and are transmitted to humans via consumption of contaminated poultry products, thus causing human gastroenteritis and other diseases as sequelae. The other campylobacters, human oral species, include C. concisus, C. showae, C. gracilis, C. ureolyticus, C. curvus, and C. rectus. These species are isolated from the oral cavity, natural colonization site, but have potential clinical relevance in the periodontal region to varying extent. Two species, C. jejuni and C. coli, are believed to be mainly associated with intestinal diseases, but recent studies suggested that oral Campylobacter species also play a significant role in intestinal diseases. This review offers an outline of the two Campylobacter groups (zoonotic and human oral), their virulence traits, and the associated illnesses including gastroenteritis.

Campylobacter concisus utilizes blood but not short chain fatty acids despite showing associations with Firmicutes taxa

Campylobacter concisus is a member of the oral microbiota that has been associated with the development of inflammatory bowel diseases. However, the role of the bacterium in disease aetiology remains poorly understood. Here, we examine optimal conditions for the growth of C. concisus, and the pathogenic potential of this bacterium in human gastrointestinal cells from the upper tract. Further, the presence of C. concisus in the lower tract of Crohn's disease (CD) patients undergoing therapy is observed, and the associations of C. concisus with the abundance of other microbial taxa and compounds they produce are evaluated. C. concisus strains had the ability to tolerate moderate levels of acidity, adhere to and invade esophageal and gastric cells; however, these properties did not correlate with their pathogenic potential in intestinal cells. The presence of the bacterium in the lower gut of CD patients was associated with an increased relative abundance of Faecalibacterium and Lachnospiraceae incertae sedis. Short chain fatty acids that can be produced by these microbial species did not appear to be responsible for this association. However, we identified genetic similarity between C. concisus and Firmicutes, specifically within aspartate and glutamate racemases. The potential pathogenesis of C. concisus in the upper gastrointestinal tract, and the responsiveness of the bacterium to therapy in a subset of CD patients warrant further investigation into whether this bacterium has a causal role in disease or its presence is incidental.

Identification of an anti-inflammatory protein from Faecalibacterium prausnitzii, a commensal bacterium deficient in Crohn's disease

BACKGROUND

Crohn's disease (CD)-associated dysbiosis is characterised by a loss of Faecalibacterium prausnitzii, whose culture supernatant exerts an anti-inflammatory effect both in vitro and in vivo. However, the chemical nature of the anti-inflammatory compounds has not yet been determined.

METHODS

Peptidomic analysis using mass spectrometry was applied to F. prausnitzii supernatant. Anti-inflammatory effects of identified peptides were tested in vitro directly on intestinal epithelial cell lines and on cell lines transfected with a plasmid construction coding for the candidate protein encompassing these peptides. In vivo, the cDNA of the candidate protein was delivered to the gut by recombinant lactic acid bacteria to prevent dinitrobenzene sulfonic acid (DNBS)-colitis in mice.

RESULTS

The seven peptides, identified in the F. prausnitzii culture supernatants, derived from a single microbial anti-inflammatory molecule (MAM), a protein of 15 kDa, and comprising 53% of non-polar residues. This last feature prevented the direct characterisation of the putative anti-inflammatory activity of MAM-derived peptides. Transfection of MAM cDNA in epithelial cells led to a significant decrease in the activation of the nuclear factor (NF)-κB pathway with a dose-dependent effect. Finally, the use of a food-grade bacterium, Lactococcus lactis, delivering a plasmid encoding MAM was able to alleviate DNBS-induced colitis in mice.

CONCLUSIONS

A 15 kDa protein with anti-inflammatory properties is produced by F. prausnitzii, a commensal bacterium involved in CD pathogenesis. This protein is able to inhibit the NF-κB pathway in intestinal epithelial cells and to prevent colitis in an animal model.

The Effect of Campylobacter concisus on Expression of IL-18, TNF-α and p53 in Barrett's Cell Lines

BACKGROUND

Barrett's oesophagus is a pre-malignant condition at gastroesophageal junction in which normal squamous epithelium is replaced by columnar shape epithelium, which predisposes oesophageal adenocarcinoma. It is known that Barrett's oesophagus evolves as a consequence of chronic gastro-oesophageal reflux disease. Although progression of Barrett's oesophagus to adenocarcinoma is still unclear, increasing incidence of oesophageal cancer and mortality worldwide make its study necessary. Several investigations have been made on the aetiology of oesophageal cancer. Most of them assessed genetical or environmental factors. However, potential role of bacteria in the development of oesophageal adenocarcinoma as a new environmental factor has not been addressed. Previous study on Barrett's disease detected presence of Campylobacter concisus as a new emerging pathogen on Barrett's and oesophageal cancer samples compared with healthy individuals. This indicates that this organism might involve in the progression of Barrett's to oesophageal adenocarcinoma.

OBJECTIVES

This study aimed to determine the effects of C. concisus on expression of three biomarkers including interleukin-18 (IL-18), tumour necrosis factor-α (TNF-α) and tumour suppressor gene (p53) in three Barrett's cell lines.

MATERIALS AND METHODS

Quantitative real-time PCR assays were developed to measure expression of pro-inflammatory mediators (IL-18 and TNF-α) and gene expression of p53 in Barrett's cell lines in co-culture with C. concisus.

RESULTS

The mentioned organism was able to modulate considerably expression of p53, TNF-α and IL-18 in a time-dependent manner.

CONCLUSIONS

The results showed that microorganism influences expression of carcinogenesis biomarker and cytokines in cell line models and possibility promotes oesophageal adenocarcinoma.

Campylobacter concisus pathotypes are present at significant levels in patients with gastroenteritis

Given that Campylobacter jejuni is recognized as the most common cause of bacterial gastroenteritis worldwide, recent findings showing comparable levels of Campylobacter concisus in patients with gastroenteritis would suggest that this bacterium is clinically important. The prevalence and abundance of Campylobacter concisus in stool samples collected from patients with acute gastroenteritis was examined using quantitative real-time PCR. The associated virulence determinants exotoxin 9 and zonula occludens toxin DNA were detected for Campylobacter concisus-infected samples using real-time PCR. Campylobacter concisus was detected at high prevalence in patients with gastroenteritis (49.7 %), higher than that observed for Campylobacter jejuni (∼5 %). The levels of Campylobacter concisus were putatively classified into clinically relevant and potentially transient subgroups based on a threshold developed using Campylobacter jejuni levels, as the highly sensitive real-time PCR probably detected transient passage of the bacterium from the oral cavity. A total of 18 % of patients were found to have clinically relevant levels of Campylobacter concisus, a significant number of which also had high levels of one of the virulence determinants. Of these patients, 78 % were found to have no other gastrointestinal pathogen identified in the stool, which strongly suggests a role for Campylobacter concisus in the aetiology of gastroenteritis in these patients. These results emphasize the need for diagnostic laboratories to employ identification protocols for emerging Campylobacter species. Clinical follow-up in patients presenting with high levels of Campylobacter concisus in the intestinal tract is needed, given that it has been associated with more chronic sequelae.

Novel Immunomodulatory Flagellin-Like Protein FlaC in Campylobacter jejuni and Other Campylobacterales

Flagellins not only are important for bacterial motility but are major bacterial proteins that can modulate host responses via Toll-like receptor 5 (TLR5) or other pattern recognition receptors. Campylobacterales colonizing the intestinal tracts of different host species harbor a gene coding for an unusual flagellin, FlaC, that is not involved in motility but is secreted and possesses a chimeric amino acid sequence composed of TLR5-activating and non-TLR5-activating flagellin sequences. Campylobacter jejuni FlaC activates cells to increase in cytokine expression in chicken and human cells, promotes cross-tolerance to TLR4 ligands, and alters chicken cecal microbiota. We propose that FlaC is a secreted effector flagellin that has specifically evolved to modulate the immune response in the intestinal tract in the presence of the resident microbiota and may contribute to bacterial persistence. The results also strengthen the role of the flagellar type III apparatus as a functional secretion system for bacterial effector proteins.

The human diarrheal pathogens Campylobacter jejuni and Campylobacter coli interfere with host innate immune signaling by different means, and their flagellins, FlaA and FlaB, have a low intrinsic property to activate the innate immune receptor Toll-like receptor 5 (TLR5). We have investigated here the hypothesis that the unusual secreted, flagellin-like molecule FlaC present in C. jejuni, C. coli, and other Campylobacterales might activate cells via TLR5 and interact with TLR5. FlaC shows striking sequence identity in its D1 domains to TLR5-activating flagellins of other bacteria, such as Salmonella, but not to nonstimulating Campylobacter flagellins. We overexpressed and purified FlaC and tested its immunostimulatory properties on cells of human and chicken origin. Treatment of cells with highly purified FlaC resulted in p38 activation. FlaC directly interacted with TLR5. Preincubation with FlaC decreased the responsiveness of chicken and human macrophage-like cells toward the bacterial TLR4 agonist lipopolysaccharide (LPS), suggesting that FlaC mediates cross-tolerance. C. jejuni flaC mutants induced an increase of cell responses in comparison to those of the wild type, which was suppressed by genetic complementation. Supplementing excess purified FlaC likewise reduced the cellular response to C. jejuni. In vivo, the administration of ultrapure FlaC led to a decrease in cecal interleukin 1β (IL-1β) expression and a significant change of the cecal microbiota in chickens. We propose that Campylobacter spp. have evolved a novel type of secreted immunostimulatory flagellin-like effector in order to specifically modulate host responses, for example toward other pattern recognition receptor (PRR) ligands, such as LPS.

IMPORTANCE Flagellins not only are important for bacterial motility but are major bacterial proteins that can modulate host responses via Toll-like receptor 5 (TLR5) or other pattern recognition receptors. Campylobacterales colonizing the intestinal tracts of different host species harbor a gene coding for an unusual flagellin, FlaC, that is not involved in motility but is secreted and possesses a chimeric amino acid sequence composed of TLR5-activating and non-TLR5-activating flagellin sequences. Campylobacter jejuni FlaC activates cells to increase in cytokine expression in chicken and human cells, promotes cross-tolerance to TLR4 ligands, and alters chicken cecal microbiota. We propose that FlaC is a secreted effector flagellin that has specifically evolved to modulate the immune response in the intestinal tract in the presence of the resident microbiota and may contribute to bacterial persistence. The results also strengthen the role of the flagellar type III apparatus as a functional secretion system for bacterial effector proteins.

Chicken, beams, and Campylobacter: rapid differentiation of foodborne bacteria via vibrational spectroscopy and MALDI-mass spectrometry

Campylobacter species are one of the main causes of food poisoning worldwide. Despite the availability of established culturing and molecular techniques, due to the fastidious nature of these microorganisms, simultaneous detection and species differentiation still remains challenging. This study focused on the differentiation of eleven Campylobacter strains from six species, using Fourier transform infrared (FT-IR) and Raman spectroscopies, together with matrix-assisted laser desorption ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), as physicochemical approaches for generating biochemical fingerprints. Cluster analysis of data from each of the three analytical approaches provided clear differentiation of each Campylobacter species, which was generally in agreement with a phylogenetic tree based on 16S rRNA gene sequences. Notably, although C. fetus subspecies fetus and venerealis are phylogenetically very closely related, using FT-IR and MALDI-TOF-MS data these subspecies were readily differentiated based on differences in the lipid (2920 and 2851 cm(-1)) and fingerprint regions (1500-500 cm(-1)) of the FT-IR spectra, and the 500-2000 m/z region of the MALDI-TOF-MS data. A finding that was further investigated with targeted lipidomics using liquid chromatography-mass spectrometry (LC-MS). Our results demonstrate that such metabolomics approaches combined with molecular biology techniques may provide critical information and knowledge related to the risk factors, virulence, and understanding of the distribution and transmission routes associated with different strains of foodborne Campylobacter spp.

Global Epidemiology of Campylobacter Infection

Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Update on the burden of Campylobacter in developing countries

PURPOSE OF REVIEW

Recent work has added to the understanding of the burden of Campylobacter jejuni, C. coli, and non-jejuni/coli Campylobacter strains in children living in the developing world.

RECENT FINDINGS

New diagnostic modalities and carefully designed field studies are demonstrating that the burden of Campylobacter diarrhea in children in the developing world has been greatly underestimated. Furthermore, there is emerging recognition of an association between Campylobacter infection and malnutrition. Important progress has been made toward a Campylobacter jejuni vaccine. Finally, evidence of antibiotic resistance continues to be an important issue that is accentuated by the realization that the burden of disease is greater than previously recognized.

SUMMARY

Additional research is needed to refine our understanding of the epidemiology of Campylobacter infections in developing countries, in particular to improve estimates of the burden of Campylobacter diarrhea in endemic settings, to determine the impact of recurrent Campylobacter infections on child development, and to describe the prevalence and clinical significance of non-jejuni/coli Campylobacter infections. Progressive antibiotic resistance of isolates argues for augmented and expanded control measures of antibiotics in livestock. Continued work in vaccine development is warranted as is the extension of data available on the serotypes related to burden in different areas of the world and the relationship of serotypes to disease severity.

Is Campylobacter to esophageal adenocarcinoma as Helicobacter is to gastric adenocarcinoma?

Esophageal adenocarcinoma develops through a cascade of cellular changes that shares similarities to the etiology of Helicobacter pylori-associated intestinal-type gastric adenocarcinoma. While host genetics and immune response have been implicated in the progression to esophageal adenocarcinoma, studies investigating esophageal microbial communities suggest that bacteria may also play an important role in driving the inflammation that leads to disease. Of these, emerging Campylobacter species have been found to be more prevalent and abundant in patients progressing through the esophageal adenocarcinoma cascade compared to controls. Given that these bacteria possess several virulence mechanisms such as toxin production, cellular invasion, and intracellular survival, emerging Campylobacter species should be investigated as etiological agents of the chronic esophageal inflammation that leads to cancer.

The susceptibility of Campylobacter concisus to the bactericidal effects of normal human serum

Campylobacter concisus is an emerging pathogen of the gastrointestinal tract that has been associated with Barrett's oesophagus, enteritis and inflammatory bowel disease. Despite having invasive potential in intestinal epithelial cells in-vitro, bacteraemic cases with C. concisus are extremely scarce, having only been reported once. Therefore, we conducted a serum resistance assay to investigate the bactericidal effects of human complement on C. concisus in comparison to some other Campylobacter species. In total, 22 Campylobacter strains were tested by incubation with normal human serum and subsequent cultivation in microaerobic conditions for 48 hours. Killing time was evaluated by decrease in total CFU over time for incubation with different serum concentrations. Faecal isolates of C. concisus showed inoculum reduction to less than 50% after 30 min. Campylobacter jejuni was sensitive to serum, but killing was delayed and a bacteraemic Campylobacter fetus subsp. fetus isolate was completely serum resistant. Interestingly, sensitivity of enteric C. concisus to human serum was not associated to different faecal-calprotectin levels. We find that faecal isolates of C. concisus are sensitive to the bactericidal effects of serum, which may explain why C. concisus is not associated to bacteraemia.