FunOMIC: Pipeline with built-in fungal taxonomic and functional databases for human mycobiome profiling

While analysis of the bacterial microbiome has become routine, that of the fungal microbiome is still hampered by the lack of robust databases and bioinformatic pipelines. Here, we present FunOMIC, a pipeline with built-in taxonomic (1.6 million marker genes) and functional (3.4 million non-redundant fungal proteins) databases for the identification of fungi. Applied to more than 2,600 human metagenomic samples, the tool revealed fungal species associated with geography, body sites, and diseases. Correlation network analysis provided new insights into inter-kingdom interactions. With this pipeline and two of the most comprehensive fungal databases, we foresee a fast-growing resource for mycobiome studies.

Gut microbial metabolome in inflammatory bowel disease: From association to therapeutic perspectives

Inflammatory bowel disease (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), is a set of clinically chronic, relapsing gastrointestinal inflammatory disease and lacks of an absolute cure. Although the precise etiology is unknown, developments in high-throughput microbial genomic sequencing significantly illuminate the changes in the intestinal microbial structure and functions in patients with IBD. The application of microbial metabolomics suggests that the microbiota can influence IBD pathogenesis by producing metabolites, which are implicated as crucial mediators of host-microbial crosstalk. This review aims to elaborate the current knowledge of perturbations of the microbiome-metabolome interface in IBD with description of altered composition and metabolite profiles of gut microbiota. We emphasized and elaborated recent findings of several potentially protective metabolite classes in IBD, including fatty acids, amino acids and derivatives and bile acids. This article will facilitate a deeper understanding of the new therapeutic approach for IBD by applying metabolome-based adjunctive treatment.

Chemoprevention with a tea from hawthorn (Crataegus oxyacantha) leaves and flowers attenuates colitis in rats by reducing inflammation and oxidative stress

•

A tea from the leaves and flowers of hawthorn is rich in flavonoids, especially vitexin-2-O-rhamnoside.

•

Mesalamine and hawthorn tea have positive healing effects in rats with colitis.

•

Hawthorn tea reduces the length and area of the brownish necrotic lesions.

•

Hawthorn tea diminishes the levels of the inflammatory markers MPO and IL-1β.

•

Hawthorn tea regulates the activity of the oxidative stress enzymes CAT and GR.

The purpose of the study was to determine the effects of a tea from the leaves and flowers of Crataegus oxyacantha in rats with colitis. Colitis was induced by administration of 2,4,6-trinitrobenzene sulfonic acid. Hawthorn tea (HT) (100 mg/kg) was given via gavage for 21 days and the mesalamine drug (100 mg/kg) was administrated during the period of disease onset. HT was rich in total phenolic compounds (16.5%), flavonoids (1.8%), and proanthocyanidins (1.5%); vitexin-2-O-rhamnoside was the main compound detected. Mesalamine and the HT diminished the length of the lesions formed in the colon, in addition to reducing the levels of myeloperoxidase and interleukin-1β. Mesalamine was able to significantly reverse the body weight loss, while HT improved the activity of glutathione reductase and catalase. Histological scoring was not changed by the interventions, but it was highly correlated with the necrotic area. HT given at 100 mg/kg can be effective against colitis.

Gasdermin D in pyroptosis

Pyroptosis is the process of inflammatory cell death. The primary function of pyroptosis is to induce strong inflammatory responses that defend the host against microbe infection. Excessive pyroptosis, however, leads to several inflammatory diseases, including sepsis and autoimmune disorders. Pyroptosis can be canonical or noncanonical. Upon microbe infection, the canonical pathway responds to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), while the noncanonical pathway responds to intracellular lipopolysaccharides (LPS) of Gram-negative bacteria. The last step of pyroptosis requires the cleavage of gasdermin D (GsdmD) at D275 (numbering after human GSDMD) into N- and C-termini by caspase 1 in the canonical pathway and caspase 4/5/11 (caspase 4/5 in humans, caspase 11 in mice) in the noncanonical pathway. Upon cleavage, the N-terminus of GsdmD (GsdmD-N) forms a transmembrane pore that releases cytokines such as IL-1β and IL-18 and disturbs the regulation of ions and water, eventually resulting in strong inflammation and cell death. Since GsdmD is the effector of pyroptosis, promising inhibitors of GsdmD have been developed for inflammatory diseases. This review will focus on the roles of GsdmD during pyroptosis and in diseases.

Defining the role of CFTR channel blocker and ClC-2 activator in DNBS induced gastrointestinal inflammation

In the present study, we have investigated and/or compared the role of glibenclamide, G as cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor, and lubiprostone, L as chloride channel-2 (ClC-2) activator in the 2,4-dinitrobenzene sulfonic acid (DNBS)-induced gastrointestinal inflammation. GI inflammation was induced by intrarectal administration of DNBS. Rats were randomly allocated in 5 groups as sham control, distilled water + DNBS, sulfasalazine (S) + DNBS, G + DNBS, and L + DNBS. All the groups were pre-treated successively for five days before the induction of colitis. One day before and the first four days after DNBS administration various parameters were studied. Later, blood chemistry, colon’s gross structure, histology, and the antioxidant load was examined. Pre-treatment with G significantly protected the change induced by DNBS concerning the change in body weight, food intake, diarrhea, occult blood in the feces, wet weight of the colon, and spleen. G because of its anti-inflammatory property down-regulated the neutrophil and WBC count and up-regulated the lymphocyte number. Moreover, G efficiently ameliorates the oxidative stress in the colon and declines the level of myeloperoxidase and malondialdehyde and up-regulated the level of superoxide dismutase and glutathione. Lubiprostone has not shown any promising effects, in fact, it causes an increase in diarrheal frequency. Our findings from this study represent that G has good potential to ameliorate GI inflammation induced by DNBS by its multiple actions including CFTR blockage and reducing the release of inflammatory markers from the MCs, anti-inflammatory and free radical scavenging property.

Impaired cognitive function in Crohn's disease: Relationship to disease activity

Background & aims

Impaired attention and response inhibition have been reported in patients with Crohn’s disease (CD) in clinical remission. Prospective studies are needed to determine whether this is a stable feature of CD and whether a similar impairment is evident in ulcerative colitis (UC). Thus, our aims were to examine whether patients with CD and UC exhibited a persistent impairment in attentional performance, and if this impairment was related to key biological indices of relevance to cognition.

Methods

A prospective observational study was conducted on fifteen patients with CD and 7 with UC in clinical remission recruited from a specialty clinic and 30 healthy matched control participants. A neuropsychological assessment was carried out at baseline (visit 1) and at a 6 month follow-up (visit 2). Plasma proinflammatory cytokines, the plasma kynurenine:tryptophan (Kyn:Trp) ratio and the salivary cortisol awakening response (CAR) were also determined at each visit.

Results

Across visits, patients with CD exhibited impaired attentional performance (p ​= 0.023). Plasma IL-6 (P ​= ​0.001) and the Kyn:Trp ratio (P ​= ​0.03) were consistently elevated and the CAR significantly blunted (P ​< ​0.05) in patients with CD. No significant relationships were identified between any biochemical parameter and altered cognitive performance.

Conclusions

Impaired cognitive function is a stable feature of patients with CD. These data suggest that even where remission has been achieved, the functional impact of an organic gastrointestinal disorder on cognition is still evident. However, it is unclear at present if physiological changes due to disease activity play a role in cognitive impairment in CD.

•

Crohn’s disease (CD) patients previously associated with impaired cognition.

•

CD patients consistently exhibited impaired attentional performance at multiple visits.

•

Functional impact of organic gastrointestinal disorder on cognition still evident in remission.

•

Increased IL-6, kynurenine pathway activation and blunted cortisol awakening response in CD.

•

Biochemical parameters not associated with altered cognitive performance.

Disruption of FOXP3-EZH2 Interaction Represents a Pathobiological Mechanism in Intestinal Inflammation

Background & Aims

Forkhead box protein 3 (FOXP3)+ regulatory T cell (Treg) dysfunction is associated with autoimmune diseases; however, the mechanisms responsible for inflammatory bowel disease pathophysiology are poorly understood. Here, we tested the hypothesis that a physical interaction between transcription factor FOXP3 and the epigenetic enzyme enhancer of zeste homolog 2 (EZH2) is essential for gene co-repressive function.

Methods

Human FOXP3 mutations clinically relevant to intestinal inflammation were generated by site-directed mutagenesis. T lymphocytes were isolated from mice, human blood, and lamina propria of Crohn's disease (CD) patients and non-CD controls. We performed proximity ligation or a co-immunoprecipitation assay in FOXP3-mutant+, interleukin 6 (IL6)-treated or CD-CD4+ T cells to assess FOXP3-EZH2 protein interaction. We studied IL2 promoter activity and chromatin state of the interferon γ locus via luciferase reporter and chromatin-immunoprecipitation assays, respectively, in cells expressing FOXP3 mutants.

Results

EZH2 binding was abrogated by inflammatory bowel disease-associated FOXP3 cysteine 232 (C232) mutation. The C232 mutant showed impaired repression of IL2 and diminished EZH2-mediated trimethylation of histone 3 at lysine 27 on interferon γ, indicative of compromised Treg physiologic function. Generalizing this mechanism, IL6 impaired FOXP3-EZH2 interaction. IL6-induced effects were reversed by Janus kinase 1/2 inhibition. In lamina propria-derived CD4+T cells from CD patients, we observed decreased FOXP3-EZH2 interaction.

Conclusions

FOXP3-C232 mutation disrupts EZH2 recruitment and gene co-repressive function. The proinflammatory cytokine IL6 abrogates FOXP3-EZH2 interaction. Studies in lesion-derived CD4+ T cells have shown that reduced FOXP3-EZH2 interaction is a molecular feature of CD patients. Destabilized FOXP3-EZH2 protein interaction via diverse mechanisms and consequent Treg abnormality may drive gastrointestinal inflammation.

Mesenteric Adipose-derived Stromal Cells From Crohn's Disease Patients Induce Protective Effects in Colonic Epithelial Cells and Mice With Colitis

Mesenteric adipose tissue hyperplasia is a hallmark of Crohn's disease (CD). Recently, we showed that mesenteric adipose-derived stromal cells (ADSCs) from CD, ulcerative colitis, and control patients synthesize and release adipokines in a disease-dependent manner. Here we examined the expression profiles of CD and control patient-derived mesenteric ADSCs and studied the effects of their extracellular mediators on colonocyte signaling in vitro and experimental colitis in vivo. ADSCs were isolated from mesenteric fat of control and CD patients. Microarray profiling and network analysis were performed in ADSCs and human colonocytes treated with conditioned media from cultured ADSCs. Mice with acute colitis received daily injections of conditioned media from patient-derived ADSCs, vehicle, or apolactoferrin. Proliferative responses were evaluated in conditioned media-treated colonocytes and mouse colonic epithelium. Total protein was isolated from cultured colonocytes after treatment with apolactoferrin for Western blot analysis of phosphorylated intracellular signaling kinases. Microarray profiling revealed differential mRNA expression in CD patient-derived ADSCs compared with controls, including lactoferrin. Administration of CD patient-derived medium or apolactoferrin increased colonocyte proliferation compared with controls. Conditioned media from CD patient-derived ADSCs or apolactoferrin attenuated colitis severity in mice and enhanced colonocyte proliferation in vivo. ADSCs from control and CD patients show disease-dependent inflammatory responses and alter colonic epithelial cell signaling in vitro and in vivo. Furthermore, we demonstrate lactoferrin production by adipose tissue, specifically mesenteric ADSCs. We suggest that mesenteric ADSC-derived lactoferrin may mediate protective effects and participate in the pathophysiology of CD by promoting colonocyte proliferation and the resolution of inflammation.

Activation of Myofibroblast TRPA1 by Steroids and Pirfenidone Ameliorates Fibrosis in Experimental Crohn's Disease

BACKGROUND & AIMS

The transient receptor potential ankyrin 1 (TRPA1) channel is highly expressed in the intestinal lamina propria, but its contribution to gut physiology/pathophysiology is unclear. Here, we evaluated the function of myofibroblast TRPA1 channels in intestinal remodeling.

METHODS

An intestinal myofibroblast cell line (InMyoFibs) was stimulated by transforming growth factor-β1 to induce in vitro fibrosis. Trpa1 knockout mice were generated using the Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) system. A murine chronic colitis model was established by weekly intrarectal trinitrobenzene sulfonic acid (TNBS) administration. Samples from the intestines of Crohn's disease (CD) patients were used for pathologic staining and quantitative analyses.

RESULTS

In InMyoFibs, TRPA1 showed the highest expression among TRP family members. In TNBS chronic colitis model mice, the extents of inflammation and fibrotic changes were more prominent in TRPA1^-/- knockout than in wild-type mice. One-week enema administration of prednisolone suppressed fibrotic lesions in wild-type mice, but not in TRPA1 knockout mice. Steroids and pirfenidone induced Ca²⁺ influx in InMyoFibs, which was antagonized by the selective TRPA1 channel blocker HC-030031. Steroids and pirfenidone counteracted transforming growth factor-β1-induced expression of heat shock protein 47, type 1 collagen, and α-smooth muscle actin, and reduced Smad-2 phosphorylation and myocardin expression in InMyoFibs. In stenotic intestinal regions of CD patients, TRPA1 expression was increased significantly. TRPA1/heat shock protein 47 double-positive cells accumulated in the stenotic intestinal regions of both CD patients and TNBS-treated mice.

CONCLUSIONS

TRPA1, in addition to its anti-inflammatory actions, may protect against intestinal fibrosis, thus being a novel therapeutic target for highly incurable inflammatory/fibrotic disorders.

Hypoxia Inducible Factor (HIF) Hydroxylases as Regulators of Intestinal Epithelial Barrier Function

Human health is dependent on the ability of the body to extract nutrients, fluids, and oxygen from the external environment while at the same time maintaining a state of internal sterility. Therefore, the cell layers that cover the surface areas of the body such as the lung, skin, and gastrointestinal mucosa provide vital semipermeable barriers that allow the transport of essential nutrients, fluid, and waste products, while at the same time keeping the internal compartments free of microbial organisms. These epithelial surfaces are highly specialized and differ in their anatomic structure depending on their location to provide appropriate and effective site-specific barrier function. Given this important role, it is not surprising that significant disease often is associated with alterations in epithelial barrier function. Examples of such diseases include inflammatory bowel disease, chronic obstructive pulmonary disease, and atopic dermatitis. These chronic inflammatory disorders often are characterized by diminished tissue oxygen levels (hypoxia). Hypoxia triggers an adaptive transcriptional response governed by hypoxia-inducible factors (HIFs), which are repressed by a family of oxygen-sensing HIF hydroxylases. Here, we review recent evidence suggesting that pharmacologic hydroxylase inhibition may be of therapeutic benefit in inflammatory bowel disease through the promotion of intestinal epithelial barrier function through both HIF-dependent and HIF-independent mechanisms.

Mechanisms of Intestinal Epithelial Barrier Dysfunction by Adherent-Invasive Escherichia coli

Pathobiont expansion, such as that of adherent-invasive Escherichia coli (AIEC), is an emerging factor associated with inflammatory bowel disease. The intestinal epithelial barrier is the first line of defense against these pathogens. Inflammation plays a critical role in altering the epithelial barrier and is a major factor involved in promoting the expansion and pathogenesis of AIEC. AIEC in turn can exacerbate intestinal epithelial barrier dysfunction by targeting multiple elements of the barrier. One critical element of the epithelial barrier is the tight junction. Increasing evidence suggests that AIEC may selectively target protein components of tight junctions, leading to increased barrier permeability. This may represent one mechanism by which AIEC could contribute to the development of inflammatory bowel disease. This review article discusses potential mechanisms by which AIEC can disrupt epithelial tight junction function and intestinal barrier function.

A Disease-Associated Microbial and Metabolomics State in Relatives of Pediatric Inflammatory Bowel Disease Patients

BACKGROUND & AIMS

Microbes may increase susceptibility to inflammatory bowel disease (IBD) by producing bioactive metabolites that affect immune activity and epithelial function. We undertook a family based study to identify microbial and metabolic features of IBD that may represent a predisease risk state when found in healthy first-degree relatives.

METHODS

Twenty-one families with pediatric IBD were recruited, comprising 26 Crohn's disease patients in clinical remission, 10 ulcerative colitis patients in clinical remission, and 54 healthy siblings/parents. Fecal samples were collected for 16S ribosomal RNA gene sequencing, untargeted liquid chromatography-mass spectrometry metabolomics, and calprotectin measurement. Individuals were grouped into microbial and metabolomics states using Dirichlet multinomial models. Multivariate models were used to identify microbes and metabolites associated with these states.

RESULTS

Individuals were classified into 2 microbial community types. One was associated with IBD but irrespective of disease status, had lower microbial diversity, and characteristic shifts in microbial composition including increased Enterobacteriaceae, consistent with dysbiosis. This microbial community type was associated similarly with IBD and reduced microbial diversity in an independent pediatric cohort. Individuals also clustered bioinformatically into 2 subsets with shared fecal metabolomics signatures. One metabotype was associated with IBD and was characterized by increased bile acids, taurine, and tryptophan. The IBD-associated microbial and metabolomics states were highly correlated, suggesting that they represented an integrated ecosystem. Healthy relatives with the IBD-associated microbial community type had an increased incidence of elevated fecal calprotectin.

CONCLUSIONS

Healthy first-degree relatives can have dysbiosis associated with an altered intestinal metabolome that may signify a predisease microbial susceptibility state or subclinical inflammation. Longitudinal prospective studies are required to determine whether these individuals have a clinically significant increased risk for developing IBD.

Microgeographic Proteomic Networks of the Human Colonic Mucosa and Their Association With Inflammatory Bowel Disease

BACKGROUND & AIMS

Interactions between mucosal cell types, environmental stressors, and intestinal microbiota contribute to pathogenesis in inflammatory bowel disease (IBD). Here, we applied metaproteomics of the mucosal-luminal interface to study the disease-related biology of the human colonic mucosa.

METHODS

We recruited a discovery cohort of 51 IBD and non-IBD subjects endoscopically sampled by mucosal lavage at 6 colonic regions, and a validation cohort of 38 no-IBD subjects. Metaproteome data sets were produced for each sample and analyzed for association with colonic site and disease state using a suite of bioinformatic approaches. Localization of select proteins was determined by immunoblot analysis and immunohistochemistry of human endoscopic biopsy samples.

RESULTS

Co-occurrence analysis of the discovery cohort metaproteome showed that proteins at the mucosal surface clustered into modules with evidence of differential functional specialization (eg, iron regulation, microbial defense) and cellular origin (eg, epithelial or hemopoietic). These modules, validated in an independent cohort, were differentially associated spatially along the gastrointestinal tract, and 7 modules were associated selectively with non-IBD, ulcerative colitis, and/or Crohn's disease states. In addition, the detailed composition of certain modules was altered in disease vs healthy states. We confirmed the predicted spatial and disease-associated localization of 28 proteins representing 4 different disease-related modules by immunoblot and immunohistochemistry visualization, with evidence for their distribution as millimeter-scale microgeographic mosaic.

CONCLUSIONS

These findings suggest that the mucosal surface is a microgeographic mosaic of functional networks reflecting the local mucosal ecology, whose compositional differences in disease and healthy samples may provide a unique readout of physiologic and pathologic mucosal states.

Crohn's Disease Fibroblasts Overproduce the Novel Protein KIAA1199 to Create Proinflammatory Hyaluronan Fragments

BACKGROUND & AIMS

Crohn's Disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Fibrosis, a serious complication of CD, occurs when activated intestinal fibroblasts deposit excessive amounts of extracellular matrix (ECM) in affected areas. A major component of the ECM is high-molecular-weight hyaluronan (HA) that, when depolymerized to low-molecular-weight fragments, becomes proinflammatory and profibrotic. Mechanisms for HA degradation are incompletely understood, but the novel protein KIAA1199 recently was discovered to degrade HA. We hypothesized that KIAA1199 protein is increased in CD colon fibroblasts and generates HA fragments that foster inflammation and fibrosis.

METHODS

Fibroblasts were isolated from explants of surgically resected colon tissue from CD and non-inflammatory bowel disease control (ND) patients. Protein levels and tissue distribution of KIAA1199 were assessed by immunoblot and immunostaining, and functional HA degradation was measured biochemically.

RESULTS

Increased levels of KIAA1199 protein were produced and deposited in the ECM by cultured CD fibroblasts compared with controls. Treatment of fibroblasts with the proinflammatory cytokine interleukin (IL) 6 increased deposition of KIAA1199 in the ECM. CD fibroblasts also produce significantly higher levels of IL6 compared with controls, and antibody blockade of IL6 receptors in CD colon fibroblasts decreased the level of KIAA1199 protein in the ECM. Colon fibroblasts degrade HA, however, small interfering RNA silencing of KIAA1199 abrogated that ability.

CONCLUSIONS

CD fibroblasts produce increased levels of KIAA1199 primarily through an IL6-driven autocrine mechanism. This leads to excessive degradation of HA and the generation of proinflammatory HA fragments, which contributes to maintenance of gut inflammation and fibrosis.

Granulocyte Macrophage Colony-Stimulating Factor-Activated CD39+/CD73+ Murine Monocytes Modulate Intestinal Inflammation via Induction of Regulatory T Cells

BACKGROUND & AIMS

Granulocyte macrophage colony-stimulating factor (GM-CSF) treatment induces clinical response in patients with active Crohn's disease. To explore whether monocytes mediate GM-CSF effects in vivo, we used a mouse model of chronic colitis induced by dextran sulfate sodium (DSS).

METHODS

Murine bone marrow-derived monocytes were activated with GM-CSF in vitro, and gene expression, phenotype, and function of GM-CSF-activated monocytes (GMaM) were analyzed. Therapeutic effects of GMaM were assessed in a model of chronic colitis induced by repeated cycles of DSS. Monocytes were administered intravenously and their immunomodulatory functions were evaluated in vivo by clinical monitoring, histology, endoscopy, immunohistochemistry, and expression of inflammatory markers in the colon. The distribution of injected monocytes in the intestine was measured by in vivo imaging.

RESULTS

GMaM expressed significantly higher levels of anti-inflammatory molecules. Production of reactive oxygen species was also increased while phagocytosis and adherence were decreased. GMaM up-regulated CD39 and CD73, which allows the conversion of adenosine triphosphate into adenosine and coincided with the induction of Foxp3⁺ (forkhead-box-protein P3 positive) regulatory T cells (Treg) in cocultures of GMaM and naive T cells. In chronic DSS-induced colitis, adoptive transfer of GMaM led to significant clinical improvement, as demonstrated by reduced weight loss, inflammatory infiltration, ulceration, and colon shrinkage. As GMaM migrated faster and persisted longer in the inflamed intestine compared with control monocytes, their presence induced Treg generation in vivo.

CONCLUSIONS

GM-CSF leads to specific monocyte activation that modulates experimental colitis via mechanisms that include the induction of Treg. We demonstrate a possible mechanism of Treg induction through CD39 and CD73 expression on monocytes.

Anti-inflammatory Function of High-Density Lipoproteins via Autophagy of IκB Kinase

BACKGROUND & AIMS

Plasma levels of high-density lipoprotein (HDL) cholesterol are frequently found decreased in patients with inflammatory bowel disease (IBD). Therefore, and because HDL exerts anti-inflammatory activities, we investigated whether HDL and its major protein component apolipoprotein A-I (apoA-I) modulate mucosal inflammatory responses in vitro and in vivo.

METHODS

The human intestinal epithelial cell line T84 was used as the in vitro model for measuring the effects of HDL on the expression and secretion of tumor necrosis factor (TNF), interleukin-8 (IL-8), and intracellular adhesion molecule (ICAM). Nuclear factor-κB (NF-κB)-responsive promoter activity was studied by dual luciferase reporter assays. Mucosal damage from colitis induced by dextran sodium sulphate (DSS) and 2,4,6-trinitrobenzenesulfonic acid (TNBS) was scored by colonoscopy and histology in apoA-I transgenic (Tg) and apoA-I knockout (KO) and wild-type (WT) mice. Myeloperoxidase (MPO) activity and TNF and ICAM expression were determined in intestinal tissue samples. Autophagy was studied by Western blot analysis, immunofluorescence, and electron microscopy.

RESULTS

HDL and apoA-I down-regulated TNF-induced mRNA expression of TNF, IL-8, and ICAM, as well as TNF-induced NF-κB-responsive promoter activity. DSS/TNBS-treated apoA-I KO mice displayed increased mucosal damage upon both colonoscopy and histology, increased intestinal MPO activity and mRNA expression of TNF and ICAM as compared with WT and apoA-I Tg mice. In contrast, apoA-I Tg mice showed less severe symptoms monitored by colonoscopy and MPO activity in both the DSS and TNBS colitis models. In addition, HDL induced autophagy, leading to recruitment of phosphorylated IκB kinase to the autophagosome compartment, thereby preventing NF-κB activation and induction of cytokine expression.

CONCLUSIONS

Taken together, the in vitro and in vivo findings suggest that HDL and apoA-I suppress intestinal inflammation via autophagy and are potential therapeutic targets for the treatment of IBD.

Mechanisms of Immune Signaling in Colitis-Associated Cancer

The inflammatory bowel diseases ulcerative colitis and Crohn's disease are associated with an increased risk for the development of colorectal cancer. During recent years, several immune signaling pathways have been linked to colitis-associated cancer (CAC), largely owing to the availability of suitable preclinical models. Among these, chronic intestinal inflammation has been shown to support tumor initiation through oxidative stress-induced mutations. A proinflammatory microenvironment that develops, possibly as a result of defective intestinal barrier function and host-microbial interactions, enables tumor promotion. Several molecular pathways such as tumor necrosis factor/nuclear factor-κB or interleukin 6/signal transducer and activator of transcription 3 signaling have been identified as important contributors to CAC development and could be promising therapeutic targets for the prevention and treatment of CAC.

The role of autophagy in the intracellular survival of Campylobacter concisus

•

Autophagy is involved in host clearance of Campylobacter concisus.

•

C. concisus can be found within Campylobacter-containing vacuoles.

•

Some C. concisus strains may subvert autophagy to survive intracellularly.

•

Proteins specific to invasive C. concisus may be involved in autophagy subversion.

•

Proteins of interest in C. concisus infection: ATG4B, ATG7, ATG9B, CTSD and LAMP1.

Campylobacter concisus is an emerging pathogen that has been associated with gastrointestinal diseases. Given the importance of autophagy for the elimination of intracellular bacteria and the subversion of this process by pathogenic bacteria, we investigated the role of autophagy in C. concisus intracellular survival. Gentamicin protection assays were employed to assess intracellular levels of C. concisus within Caco-2 cells, following autophagy induction and inhibition. To assess the interaction between C. concisus and autophagosomes, confocal microscopy, scanning electron microscopy, and transmission electron microscopy were employed. Expression levels of 84 genes involved in the autophagy process were measured using qPCR. Autophagy inhibition resulted in two- to four-fold increases in intracellular levels of C. concisus within Caco-2 cells, while autophagy induction resulted in a significant reduction in intracellular levels or bacterial clearance. C. concisus strains with low intracellular survival levels showed a dramatic increase in these levels upon autophagy inhibition. Confocal microscopy showed co-localization of the bacterium with autophagosomes, while transmission electron microscopy identified intracellular bacteria persisting within autophagic vesicles. Further, qPCR showed that following infection, 13 genes involved in the autophagy process were significantly regulated, and a further five showed borderline results, with an overall indication towards a dampening effect exerted by the bacterium on this process. Our data collectively indicates that while autophagy is important for the clearance of C. concisus, some strains may manipulate this process to benefit their intracellular survival.