ADS024, a Bacillus velezensis strain, protects human colonic epithelial cells against C. difficile toxin-mediated apoptosis

Clostridioides difficile infection (CDI) causes intestinal injury. Toxin A and toxin B cause intestinal injury by inducing colonic epithelial cell apoptosis. ADS024 is a Bacillus velezensis strain in development as a single-strain live biotherapeutic product (SS-LBP) to prevent the recurrence of CDI following the completion of standard antibiotic treatment. We evaluated the protective effects of the sterile filtrate and ethyl acetate extract of conditioned media from ADS024 and DSM7 (control strain) against mucosal epithelial injury in toxin-treated human colonic tissues and apoptosis in toxin-treated human colonic epithelial cells. Ethyl acetate extracts were generated from conditioned culture media from DSM7 and ADS024. Toxin A and toxin B exposure caused epithelial injury in fresh human colonic explants. The sterile filtrate of ADS024, but not DSM7, prevented toxin B-mediated epithelial injury in fresh human colonic explants. Both sterile filtrate and ethyl acetate extract of ADS024 prevented toxin-mediated apoptosis in human colonic epithelial cells. The anti-apoptotic effects of ADS024 filtrate and ethyl acetate extract were dependent on the inhibition of caspase 3 cleavage. The sterile filtrate, but not ethyl acetate extract, of ADS024 partially degraded toxin B. ADS024 inhibits toxin B-mediated apoptosis in human colonic epithelial cells and colonic explants.

Distinct Patterns of Gene Expression Changes in the Colon and Striatum of Young Mice Overexpressing Alpha-Synuclein Support Parkinson's Disease as a Multi-System Process

BACKGROUND

Evidence supports a role for the gut-brain axis in Parkinson's disease (PD). Mice overexpressing human wild type α- synuclein (Thy1-haSyn) exhibit slow colonic transit prior to motor deficits, mirroring prodromal constipation in PD. Identifying molecular changes in the gut could provide both biomarkers for early diagnosis and gut-targeted therapies to prevent progression.

OBJECTIVE

To identify early molecular changes in the gut-brain axis in Thy1-haSyn mice through gene expression profiling.

METHODS

Gene expression profiling was performed on gut (colon) and brain (striatal) tissue from Thy1-haSyn and wild-type (WT) mice aged 1 and 3 months using 3' RNA sequencing. Analysis included differential expression, gene set enrichment and weighted gene co-expression network analysis (WGCNA).

RESULTS

At one month, differential expression (Thy1-haSyn vs. WT) of mitochondrial genes and pathways related to PD was discordant between gut and brain, with negative enrichment in brain (enriched in WT) but positive enrichment in gut. Linear regression of WGCNA modules showed partial independence of gut and brain gene expression changes. Thy1-haSyn-associated WGCNA modules in the gut were enriched for PD risk genes and PD-relevant pathways including inflammation, autophagy, and oxidative stress. Changes in gene expression were modest at 3 months.

CONCLUSIONS

Overexpression of haSyn acutely disrupts gene expression in the colon. While changes in colon gene expression are highly related to known PD-relevant mechanisms, they are distinct from brain changes, and in some cases, opposite in direction. These findings are in line with the emerging view of PD as a multi-system disease.

Loss of miR-24-3p promotes epithelial cell apoptosis and impairs the recovery from intestinal inflammation

While apoptosis plays a significant role in intestinal homeostasis, it can also be pathogenic if overactive during recovery from inflammation. We recently reported that microRNA-24-3p (miR-24-3p) is elevated in the colonic epithelium of ulcerative colitis patients during active inflammation, and that it reduced apoptosis in vitro. However, its function during intestinal restitution following inflammation had not been examined. In this study, we tested the influence of miR-24-3p on mucosal repair by studying recovery from colitis in both novel miR-24-3p knockout and miR-24-3p-inhibited mice. We observed that knockout mice and mice treated with a miR-24-3p inhibitor had significantly worsened recovery based on weight loss, colon length, and double-blinded histological scoring. In vivo and in vitro analysis of miR-24-3p inhibition in colonic epithelial cells revealed that inhibition promotes apoptosis and increases levels of the pro-apoptotic protein BIM. Further experiments determined that silencing of BIM reversed the pro-apoptotic effects of miR-24-3p inhibition. Taken together, these data suggest that miR-24-3p restrains intestinal epithelial cell apoptosis by targeting BIM, and its loss of function is detrimental to epithelial restitution following intestinal inflammation.

The Colonic Mucosal MicroRNAs, MicroRNA-219a-5p, and MicroRNA-338-3p Are Downregulated in Irritable Bowel Syndrome and Are Associated With Barrier Function and MAPK Signaling

BACKGROUND & AIMS

Alterations in microRNA (miRNA) and in the intestinal barrier are putative risk factors for irritable bowel syndrome (IBS). We aimed to identify differentially expressed colonic mucosal miRNAs, their targets in IBS compared to healthy controls (HCs), and putative downstream pathways.

METHODS

Twenty-nine IBS patients (15 IBS with constipation [IBS-C], 14 IBS with diarrhea [IBS-D]), and 15 age-matched HCs underwent sigmoidoscopy with biopsies. A nCounter array was used to assess biopsy specimen-associated miRNA levels. A false discovery rate (FDR) < 10% was considered significant. Real-time polymerase chain reaction (PCR) was used to validate differentially expressed genes. To assess barrier function, trans-epithelial electrical resistance (TEER) and dextran flux assays were performed on Caco-2 intestinal epithelial cells that were transfected with miRNA-inhibitors or control inhibitors. Protein expression of barrier function associated genes was confirmed using western blots.

RESULTS

Four out of 247 miRNAs tested were differentially expressed in IBS compared to HCs (FDR < 10%). Real-time PCR validation suggested decreased levels of miR-219a-5p and miR-338-3p in IBS (P = .026 and P = .004), and IBS-C (P = .02 and P = .06) vs. HCs as the strongest associations. Inhibition of miR-219a-5p resulted in altered expression of proteasome/barrier function genes. Functionally, miR-219a-5p inhibition enhanced the permeability of intestinal epithelial cells as TEER was reduced (25-50%, P < .05) and dextran flux was increased (P < .01). Additionally, inhibition of miR-338-3p in cells caused alterations in the mitogen-activated protein kinase (MAPK) signaling pathway genes.

CONCLUSION

Two microRNAs that potentially affect permeability and visceral nociception were identified to be altered in IBS patients. MiR-219a-5p and miR-338-3p potentially alter barrier function and visceral hypersensitivity via neuronal and MAPK signaling and could be therapeutic targets in IBS.

Therapeutic Mechanism of Macrophage Inflammatory Protein 1 α Neutralizing Antibody (CCL3) in Clostridium difficile Infection in Mice

BACKGROUND

Clostridium difficile infection (CDI) causes diarrhea and colitis. We aimed to find a common pathogenic pathway in CDI among humans and mice by comparing toxin-mediated effects in human and mouse colonic tissues.

METHOD

Using multiplex enzyme-linked immunosorbent assay, we determined the cytokine secretion of toxin A- and B-treated human and mouse colonic explants.

RESULTS

Toxin A and toxin B exposure to fresh human and mouse colonic explants caused different patterns of cytokine secretion. Toxin A induced macrophage inflammatory protein (MIP) 1α secretion in both human and mouse explants. Toxin A reduced the expression of chloride anion exchanger SLC26A3 expression in mouse colonic explants and human colonic epithelial cells. Patients with CDI had increased colonic MIP-1 α expression and reduced colonic SLC26A3 (solute carrier family 26, member 3) compared with controls. Anti-MIP-1 α neutralizing antibody prevented death, ameliorated colonic injury, reduced colonic interleukin 1β (IL-1β) messenger RNA expression, and restored colonic SLC26a3 expression in C. difficile-infected mice. The anti-MIP-1 α neutralizing antibody prevented CDI recurrence. SLC26a3 inhibition augmented colonic IL-1 β messenger RNA expression and abolished the protective effect of anti-MIP-1 α neutralizing antibody in mice with CDI.

CONCLUSION

MIP-1 α is a common toxin A-dependent chemokine in human and mouse colon. MIP-1 α mediates detrimental effects by reducing SLC26a3 and enhancing IL-1 β expression in the colon.

Corticotropin-Releasing Hormone Receptor Alters the Tumor Development and Growth in Apcmin/+ Mice and in a Chemically-Induced Model of Colon Cancer

The neuroendocrine circuit of the corticotropin-releasing hormone (CRH) family peptides, via their cognate receptors CRHR1 and CRHR2, copes with psychological stress. However, peripheral effects of the CRH system in colon cancer remains elusive. Thus, we investigate the role of CRHR1 and CRHR2 in colon cancer. Human colon cancer biopsies were used to measure the mRNA levels of the CRH family by quantitative real-time PCR. Two animal models of colon cancer were used: Apcmin/+ mice and azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated mice. The mRNA levels of CRHR2 and UCN III are reduced in human colon cancer tissues compared to those of normal tissues. Crhr1 deletion suppresses the tumor development and growth in Apcmin/+ mice, while Crhr2 deficiency exacerbates the tumorigenicity. Crhr1 deficiency not only inhibits the expression of tumor-promoting cyclooxygenase 2, but also upregulates tumor-suppressing phospholipase A2 in Apcmin/+ mice; however, Crhr2 deficiency does not change these expressions. In the AOM/DSS model, Crhr2 deficiency worsens the tumorigenesis. In conclusion, Crhr1 deficiency confers tumor-suppressing effects in Apcmin/+ mice, but Crhr2 deficiency worsens the tumorigenicity in both Apcmin/+ and AOM/DSS-treated mice. Therefore, pharmacological inhibitors of CRHR1 or activators of CRHR2 could be of significance as anti-colon cancer drugs.

Posttranslational modifications as therapeutic targets for intestinal disorders

A variety of biological processes are regulated by posttranslational modifications. Posttranslational modifications including phosphorylation, ubiquitination, glycosylation, and proteolytic cleavage, control diverse physiological functions in the gastrointestinal tract. Therefore, a better understanding of their implications in intestinal diseases, including inflammatory bowel disease, irritable bowel syndrome, celiac disease, and colorectal cancer would provide a basis for the identification of novel biomarkers as well as attractive therapeutic targets. Posttranslational modifications can be common denominators, as well as distinct biomarkers, characterizing pathological differences of various intestinal diseases. This review provides experimental evidence that identifies changes in posttranslational modifications from patient samples, primary cells, or cell lines in intestinal disorders, and a summary of carefully selected information on the use of pharmacological modulators of protein modifications as therapeutic options.

Blockage of protease-activated receptor 2 exacerbates inflammation in high-fat environment partly through autophagy inhibition

Protease-activated receptor 2 (PAR2) regulates inflammatory responses and lipid metabolism. However, its precise role in colitis remains unclear. In this study, we aimed to investigate the function of PAR2 in high-fat diet-fed mice with colitis and its potential role in autophagy. PAR2^+/+ and PAR2^-/- mice were fed a high-fat diet (HFD) for 7 days before colitis induction with dextran sodium sulfate. Deletion of PAR2 and an HFD significantly exacerbated colitis, as shown by increased mortality, body weight loss, diarrhea or bloody stools, colon length shortening, and mucosal damage. Proinflammatory cytokine levels were elevated in HFD-fed PAR2^-/- mice and in cells treated with the PAR2 antagonist GB83, palmitic acid (PA), and a cytokine cocktail (CC). Damaging effects of PAR2 blockage were associated with autophagy regulation by reducing the levels of YAP1, SIRT1, PGC-1α, Atg5, and LC3A/B-I/II. In addition, mitochondrial dysfunction was demonstrated only in cells treated with GB83, PA, and CC. Reduced cell viability and greater induction of apoptosis, as shown by increased levels of cleaved caspase-9, cleaved caspase-3, and cleaved poly(ADP-ribose) polymerase (PARP), were observed in cells treated with GB83, PA, and CC but not in those treated with only PA and CC. Collectively, protective effects of PAR2 were elucidated during inflammation accompanied by a high-fat environment by promoting autophagy and inhibiting apoptosis, suggesting PAR2 as a therapeutic target for inflammatory bowel disease co-occurring with metabolic syndrome.NEW & NOTEWORTHY Deletion of PAR2 with high-fat diet feeding exacerbates colitis in a murine colitis model. Proinflammatory effects of PAR2 blockage in a high-fat environment were associated with an altered balance between autophagy and apoptosis. Increased colonic levels of PAR2 represent as a therapeutic strategy for IBD co-occurring with metabolic syndrome.

Role and mechanisms of exosomal miRNAs in IBD pathophysiology

Exosomes represent secretory membranous vesicles used for the information exchange between cells and organ-to-organ communication. Exosome crosstalk mechanisms are involved in the regulation of several inflammatory bowel disease (IBD)-associated pathophysiological intestinal processes such as barrier function, immune responses, and intestinal flora. Functional biomolecules, mainly noncoding RNAs (ncRNAs), are believed to be transmitted between the mammalian cells via exosomes that likely play important roles in cell-to-cell communication, both locally and systemically. MicroRNAs (miRNAs) encapsulated in exosomes have generated substantial interest because of their critical roles in multiple pathophysiological processes. In addition, exosomal miRNAs are implicated in the gut health. MiRNAs are selectively and actively loaded into the exosomes and then transferred to the target recipient cell where they manipulate cell function through posttranscriptional silencing of target genes. Intriguingly, miRNA profile of exosomes differs from their cellular counterparts suggesting an active sorting and packaging mechanism of exosomal miRNAs. Even more exciting is the involvement of posttranscriptional modifications in the specific loading of miRNAs into exosomes, but the underlying mechanisms of how these modifications direct ncRNA sorting have not been established. This review gives a brief overview of the status of exosomes and exosomal miRNAs in IBD and also discusses potential mechanisms of exosomal miRNA sorting and delivering.

Autotaxin loss accelerates intestinal inflammation by suppressing TLR4-mediated immune responses

Autotaxin (ATX) converts lysophosphatidylcholine and sphingosyl-phosphorylcholine into lysophosphatidic acid and sphingosine 1-phosphate, respectively. Despite the pivotal function of ATX in lipid metabolism, mechanisms by which ATX regulates immune and inflammatory disorders remain elusive. Here, using myeloid cell lineage-restricted Atx knockout mice, we show that Atx deficiency disrupts membrane microdomains and lipid rafts, resulting in the inhibition of Toll-like receptor 4 (TLR4) complex formation and the suppression of adaptor recruitment, thereby inhibiting TLR4-mediated responses in macrophages. Accordingly, TLR4-induced innate immune functions, including phagocytosis and iNOS expression, are attenuated in Atx-deficient macrophages. Consequently, Atx^-/- mice exhibit a higher bacterial prevalence in the intestinal mucosa compared to controls. When combined with global Il10^-/- mice, which show spontaneous colitis due to the translocation of luminal commensal microbes into the mucosa, myeloid cell lineage-restricted Atx knockout accelerates colitis development compared to control littermates. Collectively, our data reveal that Atx deficiency compromises innate immune responses, thereby promoting microbe-associated gut inflammation.

The IBD-associated long noncoding RNA IFNG-AS1 regulates the balance between inflammatory and anti-inflammatory cytokine production after T-cell stimulation

The inflammatory bowel diseases (IBD) are a complex set of chronic gastrointestinal inflammatory conditions arising from the interplay of genetic and environmental factors. This study focuses on noncoding RNA transcripts as potential mediators of IBD pathophysiology. One particular gene, interferon γ-antisense 1 (IFNG-AS1), has been consistently observed to be elevated in the intestinal mucosa of patients with actively inflamed IBD versus healthy controls. This study builds on these observations, demonstrating that the second splice variant is specifically altered, and this alteration even stratifies within inflamed patients. With the use of a CRISPR-based overexpression system, IFNG-AS1 was selectively overexpressed directly from its genomic loci in T cells. An unbiased mRNA array on these cells identified a large increase in many inflammatory cytokines and a decrease in anti-inflammatory cytokines after IFNG-AS1 overexpression. Media from T cells overexpressing IFNG-AS1 elicited an inflammatory signaling cascade in primary human peripheral blood mononuclear cells, suggesting the potential functional importance of IFNG-AS1 in IBD pathophysiology. The significance of these results is amplified by studies suggesting that a single-nucleotide polymorphism in IFNG-AS1, rs7134599, was associated with both subtypes of patients with IBD independently of race.NEW & NOTEWORTHY Long noncoding RNAs are an emerging field of inflammatory bowel disease (IBD) research. This study mechanistically analyzes the role of a commonly upregulated gene in IBD and shows IFNG-AS1 as a mediator of an inflammatory signaling cascade.

MiR-21 in Substance P-induced exosomes promotes cell proliferation and migration in human colonic epithelial cells

Exosomes are cellular vesicles involved in intercellular communication via their specialized molecular cargo, such as miRNAs. Substance P (SP), a neuropeptide/hormone, and its high-affinity receptor, NK-1R, are highly expressed during colonic inflammation. Our previous studies show that SP/NK-1R signaling stimulates differential miRNA expression and promotes colonic epithelial cell proliferation. In this study, we examined whether SP/NK-1R signaling regulates exosome biogenesis and exosome-miRNA cargo sorting. Moreover, we examined the role of SP/NK-1R signaling in exosome-regulated cell proliferation and migration. Exosomes produced by human colonic NCM460 epithelial cells overexpressing NK-1R (NCM460-NK1R) were isolated from culture media. Exosome abundance and uptake were assessed by Western blot analysis (abundance) and Exo-Green fluorescence microscopy (abundance and uptake). Cargo-miRNA levels were assessed by RT-PCR. Cell proliferation and migration were assessed using xCELLigence technology. Colonic epithelial exosomes were isolated from mice pretreated with SP for 3 days. Cell proliferation in vivo was assessed by K_i-67 staining. SP/NK-1R signaling in human colonic epithelial cells (in vitro) and mouse colons (in vivo) increased 1) exosome production, 2) the level of fluorescence in NCM460s treated with Exo-Green-labeled exosomes, and 3) the level of miR-21 in exosome cargo. Moreover, our results showed that SP/NK-1R-induced cell proliferation and migration are at least in part dependent on intercellular communication via exosomal miR-21 in vitro and in vivo. Our results demonstrate that SP/NK-1R signaling regulates exosome biogenesis and induces its miR-21 cargo sorting. Moreover, exosomal miR-21 promotes proliferation and migration of target cells.NEW & NOTEWORTHY Substance P signaling regulates exosome production in human colonic epithelial cells and colonic crypts in wild-type mice. MiR-21 is selectively sorted into exosomes induced by Substance P stimulation and promotes cell proliferation and migration in human colonocytes and mouse colonic crypts.

Chronic Stress, Inflammation, and Colon Cancer: A CRH System-Driven Molecular Crosstalk

Chronic stress is thought to be involved in the occurrence and progression of multiple diseases, via mechanisms that still remain largely unknown. Interestingly, key regulators of the stress response, such as members of the corticotropin-releasing-hormone (CRH) family of neuropeptides and receptors, are now known to be implicated in the regulation of chronic inflammation, one of the predisposing factors for oncogenesis and disease progression. However, an interrelationship between stress, inflammation, and malignancy, at least at the molecular level, still remains unclear. Here, we attempt to summarize the current knowledge that supports the inseparable link between chronic stress, inflammation, and colorectal cancer (CRC), by modulation of a cascade of molecular signaling pathways, which are under the regulation of CRH-family members expressed in the brain and periphery. The understanding of the molecular basis of the link among these processes may provide a step forward towards personalized medicine in terms of CRC diagnosis, prognosis and therapeutic targeting.

miR-24 Is Elevated in Ulcerative Colitis Patients and Regulates Intestinal Epithelial Barrier Function

Inflammatory bowel disease is characterized by high levels of inflammation and loss of barrier integrity in the colon. The intestinal barrier is a dynamic network of proteins that encircle intestinal epithelial cells. miRNAs regulate protein-coding genes. In this study, miR-24 was found to be elevated in colonic biopsies and blood samples from ulcerative colitis (UC) patients compared with healthy controls. In the colon of UC patients, miR-24 is localized to intestinal epithelial cells, which prompted an investigation of intestinal epithelial barrier function. Two intestinal epithelial cell lines were used to study the effect of miR-24 overexpression on barrier integrity. Overexpression of miR-24 in both cell lines led to diminished transepithelial electrical resistance and increased dextran flux, suggesting an effect on barrier integrity. Overexpression of miR-24 did not induce apoptosis or affect cell proliferation, suggesting that the effect of miR-24 on barrier function was due to an effect on cell-cell junctions. Although the tight junctions in cells overexpressing miR-24 appeared normal, miR-24 overexpression led to a decrease in the tight junction-associated protein cingulin. Loss of cingulin compromised barrier formation; cingulin levels negatively correlated with disease severity in UC patients. Together, these data suggest that miR-24 is a significant regulator of intestinal barrier that may be important in the pathogenesis of UC.

Overexpressing Long Noncoding RNAs Using Gene-activating CRISPR

Long noncoding RNA (lncRNA) biology is a new and exciting field of research, with the number of publications from this field growing exponentially since 2007. These studies have confirmed that lncRNAs are altered in almost all diseases. However, studying the functional roles for lncRNAs in the context of disease remains difficult due to the lack of protein products, tissue-specific expression, low expression levels, complexities in splice forms, and lack of conservation among species. Given the species-specific expression, lncRNA studies are often restricted to human research contexts when studying disease processes. Since lncRNAs function at the molecular level, one way to dissect lncRNA biology is to either remove the lncRNA or overexpress the lncRNA and measure cellular effects. In this article, a written and visualized protocol to overexpress lncRNAs in vitro is presented. As a representative experiment, an lncRNA associated with inflammatory bowel disease, Interferon Gamma Antisense 1 (IFNG-AS1), is shown to be overexpressed in a Jurkat T-cell model. To accomplish this, the activating clustered regularly interspaced short palindromic repeats (CRISPR) technique is used to enable overexpression at the endogenous genomic loci. The activating CRISPR technique targets a set of transcription factors to the transcriptional start site of a gene, enabling a robust overexpression of multiple lncRNA splice forms. This procedure will be broken down into three steps, namely (i) guide RNA (gRNA) design and vector construction, (ii) virus generation and transduction, and (iii) colony screening for overexpression. For this representative experiment, a greater than 20-fold enhancement in IFNG-AS1 in Jurkat T cells was observed.

Identification of novel mRNAs and lncRNAs associated with mouse experimental colitis and human inflammatory bowel disease

Inflammatory bowel disease (IBD) is a complex disorder that is associated with significant morbidity. While many recent advances have been made with new diagnostic and therapeutic tools, a deeper understanding of its basic pathophysiology is needed to continue this trend toward improving treatments. By utilizing an unbiased, high-throughput transcriptomic analysis of two well-established mouse models of colitis, we set out to uncover novel coding and noncoding RNAs that are differentially expressed in the setting of colonic inflammation. RNA-seq analysis was performed using colonic tissue from two mouse models of colitis, a dextran sodium sulfate-induced model and a genetic-induced model in mice lacking IL-10. We identified 81 coding RNAs that were commonly altered in both experimental models. Of these coding RNAs, 12 of the human orthologs were differentially expressed in a transcriptomic analysis of IBD patients. Interestingly, 5 of the 12 of human differentially expressed genes have not been previously identified as IBD-associated genes, including ubiquitin D. Our analysis also identified 15 noncoding RNAs that were differentially expressed in either mouse model. Surprisingly, only three noncoding RNAs were commonly dysregulated in both of these models. The discovery of these new coding and noncoding RNAs expands our transcriptional knowledge of mouse models of IBD and offers additional targets to deepen our understanding of the pathophysiology of IBD. NEW & NOTEWORTHY Much of the genome is transcribed as non-protein-coding RNAs; however, their role in inflammatory bowel disease is largely unknown. This study represents the first of its kind to analyze the expression of long noncoding RNAs in two mouse models of inflammatory bowel disease and correlate them to human clinical samples. Using high-throughput RNA-seq analysis, we identified new coding and noncoding RNAs that were differentially expressed such as ubiquitin D and 5730437C11Rik.

Colonic Inhibition of Phosphatase and Tensin Homolog Increases Colitogenic Bacteria, Causing Development of Colitis in Il10-/- Mice

Background

Phosphatase and tensin homolog (Pten) is capable of mediating microbe-induced immune responses in the gut. Thus, Pten deficiency in the intestine accelerates colitis development in Il10-/- mice. As some ambient pollutants inhibit Pten function and exposure to ambient pollutants may increase inflammatory bowel disease (IBD) incidence, it is of interest to examine how Pten inhibition could affect colitis development in genetically susceptible hosts.

Methods

With human colonic mucosa biopsies from pediatric ulcerative colitis and non-IBD control subjects, we assessed the mRNA levels of the PTEN gene and the gene involved in IL10 responses. The data from the human tissues were corroborated by treating Il10-/-, Il10rb-/-, and wild-type C57BL/6 mice with Pten-specific inhibitor VO-OHpic. We evaluated the severity of mouse colitis by investigating the tissue histology and cytokine production. The gut microbiome was investigated by analyzing the 16S ribosomal RNA gene sequence with mouse fecal samples.

Results

PTEN and IL10RB mRNA levels were reduced in the human colonic mucosa of pediatric ulcerative colitis compared with non-IBD subjects. Intracolonic treatment of the Pten inhibitor induced colitis in Il10-/- mice, characterized by reduced body weight, marked colonic damage, and increased production of inflammatory cytokines, whereas Il10rb-/- and wild-type C57BL/6 mice treated with the inhibitor did not develop colitis. Pten inhibitor treatment changed the fecal microbiome, with increased abundance of colitogenic bacteria Bacteroides and Akkermansia in Il10-/- mice.

Conclusions

Loss of Pten function increases the levels of colitogenic bacteria in the gut, thereby inducing deleterious colitis in an Il10-deficient condition.

Sigmoid colon mucosal gene expression supports alterations of neuronal signaling in irritable bowel syndrome with constipation

Peripheral factors likely play a role in at least a subset of irritable bowel syndrome (IBS) patients. Few studies have investigated mucosal gene expression using an unbiased approach. Here, we performed mucosal gene profiling in a sex-balanced sample to identify relevant signaling pathways and gene networks and compare with publicly available profiling data from additional cohorts. Twenty Rome III+ IBS patients [10 IBS with constipation (IBS-C), 10 IBS with diarrhea (IBS-D), 5 men/women each), and 10 age-/sex-matched healthy controls (HCs)] underwent sigmoidoscopy with biopsy for gene microarray analysis, including differential expression, weighted gene coexpression network analysis (WGCNA), gene set enrichment analysis, and comparison with publicly available data. Expression levels of 67 genes were validated in an expanded cohort, including the above samples and 18 additional participants (6 each of IBS-C, IBS-D, HCs) using NanoString nCounter technology. There were 1,270 differentially expressed genes (FDR < 0.05) in IBS-C vs. HCs but none in IBS or IBS-D vs. HCs. WGNCA analysis identified activation of the cAMP/protein kinase A signaling pathway. Nine of 67 genes were validated by the NanoString nCounter technology (FDR < 0.05) in the expanded sample. Comparison with publicly available microarray data from the Mayo Clinic and University of Nottingham supports the reproducibility of 17 genes from the microarray analysis and three of nine genes validated by nCounter in IBS-C vs. HCs. This study supports the involvement of peripheral mechanisms in IBS-C, particularly pathways mediating neuronal signaling. NEW & NOTEWORTHY Peripheral factors play a role in the pathophysiology of irritable bowel syndrome (IBS), which, to date, has been mostly evident in IBS with diarrhea. Here, we show that sigmoid colon mucosal gene expression profiles differentiate IBS with constipation from healthy controls. These profiling data and analysis of additional cohorts also support the concept that peripheral neuronal pathways contribute to IBS pathophysiology.

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.

Functional role and therapeutic targeting of microRNAs in inflammatory bowel disease

Inflammatory bowel diseases (IBD) are chronic inflammatory gastrointestinal diseases, primarily consisting of ulcerative colitis and Crohn's disease. The complex nature of the disease, as well as the limited therapeutic options characterized by low efficiency and major side effects, highlights the importance of developing novel strategies of therapeutic intervention in IBD. Susceptibility loci related to IBD are present only in a small percentage of IBD patients, implying that epigenetic modifications could influence the pathogenesis of the disease. MicroRNAs (miRNAs) are small noncoding RNAs that regulate multiple molecular pathways involved in IBD pathobiology. MiRNA inhibitors targeting the IBD-activated miRNAs could have therapeutic value for IBD patients. This review provides an overview of the recent advances in miRNA biology related to IBD pathogenesis and the pharmacological development of miRNA-based therapeutics.

Fidaxomicin and OP-1118 Inhibit Clostridium difficile Toxin A- and B-Mediated Inflammatory Responses via Inhibition of NF-κB Activity

Clostridium difficile causes diarrhea and colitis by releasing toxin A and toxin B. In the human colon, both toxins cause intestinal inflammation and stimulate tumor necrosis factor alpha (TNF-α) expression via the activation of NF-κB. It is well established that the macrolide antibiotic fidaxomicin is associated with reduced relapses of C. difficile infection. We showed that fidaxomicin and its primary metabolite OP-1118 significantly inhibited toxin A-mediated intestinal inflammation in mice in vivo and toxin A-induced cell rounding in vitro We aim to determine whether fidaxomicin and OP-1118 possess anti-inflammatory effects against toxin A and toxin B in the human colon and examine the mechanism of this response. We used fresh human colonic explants, NCM460 human colonic epithelial cells, and RAW264.7 mouse macrophages to study the mechanism of the activity of fidaxomicin and OP-1118 against toxin A- and B-mediated cytokine expression and apoptosis. Fidaxomicin and OP-1118 dose-dependently inhibited toxin A- and B-induced TNF-α and interleukin-1β (IL-1β) mRNA expression and histological damage in human colonic explants. Fidaxomicin and OP-1118 inhibited toxin A-mediated NF-κB phosphorylation in human and mouse intestinal mucosae. Fidaxomicin and OP-1118 also inhibited toxin A-mediated NF-κB phosphorylation and TNF-α expression in macrophages, which was reversed by the NF-κB activator phorbol myristate acetate (PMA). Fidaxomicin and OP-1118 prevented toxin A- and B-mediated apoptosis in NCM460 cells, which was reversed by the addition of PMA. PMA reversed the cytoprotective effect of fidaxomicin and OP-1118 in toxin-exposed human colonic explants. Fidaxomicin and OP-1118 inhibit C. difficile toxin A- and B-mediated inflammatory responses, NF-κB phosphorylation, and tissue damage in the human colon.

MicroRNA-31-3p Is Involved in Substance P (SP)-Associated Inflammation in Human Colonic Epithelial Cells and Experimental Colitis

Substance P (SP) mediates colitis. SP signaling regulates the expression of several miRNAs, including miR-31-3p, in human colonocytes. However, the role of miR-31-3p in colitis and the underlying mechanisms has not been elucidated. We performed real-time PCR analysis of miR-31-3p expression in human colonic epithelial cells overexpressing neurokinin-1 receptor (NCM460 NK-1R) in response to SP stimulation and in NCM460 cells after IL-6, IL8, tumor necrosis factor (TNF)-α, and interferon-γ exposure. Functions of miR-31-3p were tested in NCM460-NK-1R cells and the trinitrobenzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS) models of colitis. Targets of miRNA-31-3p were confirmed by Western blot analysis and luciferase reporter assay. Jun N-terminal kinase inhibition decreased SP-induced miR-31-3p expression. miR-31-3p expression was increased in both TNBS- and DSS-induced colitis and human colonic biopsies from ulcerative colitis, compared with controls. Intracolonic administration of a miR-31-3p chemical inhibitor exacerbated TNBS- and DSS-induced colitis and increased colonic TNF-α, CXCL10, and chemokine (C-C motif) ligand 2 (CCL2) mRNA expression. Conversely, overexpression of miR-31-3p ameliorated the severity of DSS-induced colitis. Bioinformatic, luciferase reporter assay, and Western blot analyses identified RhoA as a target of miR-31-3p in NCM460 cells. Constitutive activation of RhoA led to increased expression of CCL2, IL6, TNF-α, and CXCL10 in NCM460-NK-1R cells on SP stimulation. Our results reveal a novel SP-miR-31-3p-RhoA pathway that protects from colitis. The use of miR-31-3p mimics may be a promising approach for colitis treatment.

Role of G protein-coupled receptors-microRNA interactions in gastrointestinal pathophysiology

G protein-coupled receptors (GPCRs) make up the largest transmembrane receptor superfamily in the human genome and are expressed in nearly all gastrointestinal cell types. Coupling of GPCRs and their respective ligands activates various phosphotransferases in the cytoplasm, and, thus, activation of GPCR signaling in intestine regulates many cellular and physiological processes. Studies in microRNAs (miRNAs) demonstrate that they represent critical epigenetic regulators of different pathophysiological responses in different organs and cell types in humans and animals. Here, we reviewed recent research on GPCR-miRNA interactions related to gastrointestinal pathophysiology, such as inflammatory bowel diseases, irritable bowel syndrome, and gastrointestinal cancers. Given that the presence of different types of cells in the gastrointestinal tract suggests the importance of cell-cell interactions in maintaining gastrointestinal homeostasis, we also discuss how GPCR-miRNA interactions regulate gene expression at the cellular level and subsequently modulate gastrointestinal pathophysiology through molecular regulatory circuits and cell-cell interactions. These studies helped identify novel molecular pathways leading to the discovery of potential biomarkers for gastrointestinal diseases.

CRHR2/Ucn2 signaling is a novel regulator of miR-7/YY1/Fas circuitry contributing to reversal of colorectal cancer cell resistance to Fas-mediated apoptosis

Colorectal cancer (CRC) responds poorly to immuno-mediated cytotoxicity. Underexpression of corticotropin-releasing-hormone-receptor-2 (CRHR2) in CRC, promotes tumor survival, growth and Epithelial to Mesenchymal Transition (EMT), in vitro and in vivo. We explored the role of CRHR2 downregulation in CRC cell resistance to Fas/FasL-mediated apoptosis and the underlying molecular mechanism. CRC cell sensitivity to CH11-induced apoptosis was compared between Urocortin-2 (Ucn2)-stimulated parental and CRHR2-overexpressing CRC cell lines and targets of CRHR2/Ucn2 signaling were identified through in vitro and ex vivo analyses. Induced CRHR2/Ucn2 signaling in SW620 and DLD1 cells increased specifically their sensitivity to CH11-mediated apoptosis, via Fas mRNA and protein upregulation. CRC compared to control tissues had reduced Fas expression that was associated with lost CRHR2 mRNA, poor tumor differentiation and high risk for distant metastasis. YY1 silencing increased Fas promoter activity in SW620 and re-sensitized them to CH11-apoptosis, thus suggesting YY1 as a putative transcriptional repressor of Fas in CRC. An inverse correlation between Fas and YY1 expression was confirmed in CRC tissue arrays, while elevated YY1 mRNA was clinically relevant with advanced CRC grade and higher risk for distant metastasis. CRHR2/Ucn2 signaling downregulated specifically YY1 expression through miR-7 elevation, while miR-7 modulation in miR-7^high SW620-CRHR2+ and miR-7^low HCT116 cells, had opposite effects on YY1 and Fas expressions and cell sensitivity to CH11-killing. CRHR2/Ucn2 signaling is a negative regulator of CRC cell resistance to Fas/FasL-apoptosis via targeting the miR-7/YY1/Fas circuitry. CRHR2 restoration might prove effective in managing CRC response to immune-mediated apoptotic stimuli.

Analysis of endogenous lipids during intestinal wound healing

Intestinal wound healing is a new therapeutic goal for inflammatory bowel disease (IBD) as complete healing of the mucosa is the key element of clinical remission in IBD. Previous studies showed that termination of inflammation can be achieved by adding pro-resolving lipids like DHA and EPA exogenously. However, the roles of these lipids in mucosal healing have not been investigated. To recapitulate intestinal healing process, mice were received dextran sodium sulfate (DSS) for 7 days in the drinking water followed by regular tap water for 5 additional days. DSS-induced intestinal inflammation featuring body weight loss, histological tissue damage, increased cytokine production and infiltration of inflammatory cells was gradually reduced upon switching to water. To investigate whether endogenous lipids play a role in mucosal healing, the lipidomics analysis of mouse serum was performed. Reduced levels of arachidonic acid, the biosynthetic precursor of prostaglandin F (PGF)_2α, 19H-PGF_1α, the metabolite of prostacyclin, and 20H-PGF_2α, the metabolite of PGF_2α, suggest subsiding inflammation. In contrast, increased levels of an active metabolite of resolvin D1 along with decreased levels of its precursor DHA as well as decreased levels of the precursor of resolvin E, 18-hydroxy-eicosapentaenoic acid, suggest inauguration of mucosal healing by endogenous lipids. Furthermore, exogenously supplied fish oil enhanced the process even further. These results suggest the presence of mucosal healing regulated by endogenous pro-healing lipids and also indicate that the remission state of IBD could be prolonged by enhancing the levels of these lipids.

Endocannabinoids in the gastrointestinal tract

The endocannabinoid system mainly consists of endogenously produced cannabinoids (endocannabinoids) and two G protein-coupled receptors (GPCRs), cannabinoid receptors 1 and 2 (CB₁ and CB₂). This system also includes enzymes responsible for the synthesis and degradation of endocannabinoids and molecules required for the uptake and transport of endocannabinoids. In addition, endocannabinoid-related lipid mediators and other putative endocannabinoid receptors, such as transient receptor potential channels and other GPCRs, have been identified. Accumulating evidence indicates that the endocannabinoid system is a key modulator of gastrointestinal physiology, influencing satiety, emesis, immune function, mucosal integrity, motility, secretion, and visceral sensation. In light of therapeutic benefits of herbal and synthetic cannabinoids, the vast potential of the endocannabinoid system for the treatment of gastrointestinal diseases has been demonstrated. This review focuses on the role of the endocannabinoid system in gut homeostasis and in the pathogenesis of intestinal disorders associated with intestinal motility, inflammation, and cancer. Finally, links between gut microorganisms and the endocannabinoid system are briefly discussed.

Probiotic Saccharomyces boulardii CNCM I-745 prevents outbreak-associated Clostridium difficile-associated cecal inflammation in hamsters

C. difficile infection (CDI) is a common debilitating nosocomial infection associated with high mortality. Several CDI outbreaks have been attributed to ribotypes 027, 017, and 078. Clinical and experimental evidence indicates that the nonpathogenic yeast Saccharomyces boulardii CNCM I-745 (S.b) is effective for the prevention of CDI. However, there is no current evidence suggesting this probiotic can protect from CDI caused by outbreak-associated strains. We used established hamster models infected with outbreak-associated C. difficile strains to determine whether oral administration of live or heat-inactivated S.b can prevent cecal tissue damage and inflammation. Hamsters infected with C. difficile strain VPI10463 (ribotype 087) and outbreak-associated strains ribotype 017, 027, and 078 developed severe cecal inflammation with mucosal damage, neutrophil infiltration, edema, increased NF-κB phosphorylation, and increased proinflammatory cytokine TNFα protein expression. Oral gavage of live, but not heated, S.b starting 5 days before C. difficile infection significantly reduced cecal tissue damage, NF-κB phosphorylation, and TNFα protein expression caused by infection with all strains. Moreover, S.b-conditioned medium reduced cell rounding caused by filtered supernatants from all C. difficile strains. S.b-conditioned medium also inhibited toxin A- and B-mediated actin cytoskeleton disruption. S.b is effective in preventing C. difficile infection by outbreak-associated via inhibition of the cytotoxic effects of C. difficile toxins.

A long noncoding RNA signature for ulcerative colitis identifies IFNG-AS1 as an enhancer of inflammation

High-throughput technologies revealed new categories of genes, including the long noncoding RNAs (lncRNAs), involved in the pathogenesis of human disease; however, the role of lncRNAs in the ulcerative colitis (UC) has not been evaluated. Gene expression profiling was used to develop lncRNA signatures in UC samples. Jurkat T cells were activated by PMA/ionomycin subsequently interferon-γ (IFNG) and tumor necrosis factor (TNF)-α protein levels were assessed by ELISA. Anti-sense molecules were designed to block IFNG-AS1 expression. A unique set of lncRNAs was differentially expressed between UC and control samples. Of these, IFNG-AS1 was among the highest statistically significant lncRNAs (fold change: 5.27, P value: 7.07E-06). Bioinformatic analysis showed that IFNG-AS1 was associated with the IBD susceptibility loci SNP rs7134599 and its genomic location is adjacent to the inflammatory cytokine IFNG. In mouse models of colitis, active colitis samples had increased colonic expression of this lncRNA. Utilizing the Jurkat T cell model, we found IFNG-AS1 to positively regulate IFNG expression. Novel lncRNA signatures differentiate UC patients with active disease, patients in remission, and control subjects. A subset of these lncRNAs was found to be associated with the clinically validated IBD susceptibility loci. IFNG-AS1 was one of these differentially expressed lncRNAs in UC patients and found to regulate the key inflammatory cytokine, IFNG, in CD4 T cells. Taking these findings together, our study revealed novel lncRNA signatures deregulated in UC and identified IFNG-AS1 as a novel regulator of IFNG inflammatory responses, suggesting the potential importance of noncoding RNA mechanisms on regulation of inflammatory bowel disease-related inflammatory responses.

Neuropeptide substance P and the immune response

Substance P is a peptide mainly secreted by neurons and is involved in many biological processes, including nociception and inflammation. Animal models have provided insights into the biology of this peptide and offered compelling evidence for the importance of substance P in cell-to-cell communication by either paracrine or endocrine signaling. Substance P mediates interactions between neurons and immune cells, with nerve-derived substance P modulating immune cell proliferation rates and cytokine production. Intriguingly, some immune cells have also been found to secrete substance P, which hints at an integral role of substance P in the immune response. These communications play important functional roles in immunity including mobilization, proliferation and modulation of the activity of immune cells. This review summarizes current knowledge of substance P and its receptors, as well as its physiological and pathological roles. We focus on recent developments in the immunobiology of substance P and discuss the clinical implications of its ability to modulate the immune response.

Neurotensin Promotes the Development of Colitis and Intestinal Angiogenesis via Hif-1α-miR-210 Signaling

Neurotensin (NT) via its receptor 1 (NTR1) modulates the development of colitis, decreases HIF-1α/PHD2 interaction, stabilizes and increases HIF-1α transcriptional activity, and promotes intestinal angiogenesis. HIF-1α induces miR-210 expression, whereas miR-210 is strongly upregulated in response to NT in NCM460 human colonic epithelial cells overexpressing NTR1 (NCM460-NTR1). In this study, we examined whether NT activates a NTR1-HIF-1α-miR-210 cascade using in vitro (NCM460-NTR1 cells) and in vivo (transgenic mice overexpressing [HIF-1α-OE] or lacking HIF-1α [HIF-1α-knockout (KO)] in intestinal epithelial cells and mice lacking NTR1 [NTR1-KO]) models. Pretreatment of NCM460-NTR1 cells with the HIF-1α inhibitor PX-478 or silencing of HIF-1α (small interfering HIF-1α) attenuated miR-210 expression in response to NT. Intracolonic 2,4,6-trinitrobenzenesulfonic acid (TNBS) administration (2-d model) increased colonic miR-210 expression that was significantly reduced in NTR1-KO, HIF-1α-KO mice, and wild-type mice pretreated intracolonically with locked nucleic acid anti-miR-210. In contrast, HIF-1α-OE mice showed increased miR-210 expression at baseline that was further increased following TNBS administration. HIF-1α-OE mice had also exacerbated TNBS-induced neovascularization compared with TNBS-exposed wild-type mice. TNBS-induced neovascularization was attenuated in HIF-1α-KO mice, or mice pretreated intracolonically with anti-miR-210. Intracolonic anti-miR-210 also reduced colitis in response to TNBS (2 d). Importantly, miR-210 expression was increased in tissue samples from ulcerative colitis patients. We conclude that NT exerts its proinflammatory and proangiogenic effects during acute colitis via a NTR1-prolyl hydroxylase 2/HIF-1α-miR-210 signaling pathway. Our results also demonstrate that miR-210 plays a proinflammatory role in the development of colitis.

Urocortins and CRF receptor type 2 variants in the male rat colon: gene expression and regulation by endotoxin and anti-inflammatory effect

Urocortins (Ucns) 1, 2, and 3 and corticotropin-releasing factor receptor 2 (CRF2) mRNA are prominently expressed in various layers of the upper gut. We tested whether Ucns and CRF2 variants are also expressed in the different layers of the rat colon, regulated by LPS (100 μg/kg ip) and play a modulatory role in the colonic immune response to LPS. Transcripts of Ucns and CRF2b, the most common isoform in the periphery, were detected in all laser microdissected layers, including myenteric neurons. LPS increased the mRNA level of Ucn 1, Ucn 2, and Ucn 3 and decreased that of CRF2b in both the colonic mucosa and submucosa + muscle (S+M) layers at 2, 6, and 9 h after injection with a return to basal at 24 h. In addition, CRF2a, another variant more prominent in the brain, and a novel truncated splice variant CRF2a-3 mRNA were detected in all segments of the large intestine. LPS reciprocally regulated the colonic expression of these CRF2 variants by decreasing both CRF2a and CRF2b, while increasing CRF2a-3 in the mucosa and S+M. The CRF2 antagonist astressin2-B further enhanced LPS-induced increase of mRNA level of interleukin (IL)-1β, TNF-α, and inducible nitric oxide synthase in S+M layers and IL-1β in the mucosa and evoked TNF-α expression in the mucosa. These data indicate that Ucns/CRF2 variants are widely expressed in all colonic layers and reciprocally regulated by LPS. CRF2 signaling dampens the CD14/TLR4-mediated acute inflammatory response to Gram-negative bacteria in the colon.

Genome-wide DNA methylation profiling of peripheral blood mononuclear cells in irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a stress-sensitive disorder. Environmental factors including stress can trigger epigenetic changes, which have not been well-studied in IBS. We performed a pilot study investigating genome-wide DNA methylation of IBS patients and healthy controls (HCs) to identify potential epigenetic markers and associated pathways. Additionally, we investigated relationships of epigenetic changes in selected genes with clinical traits.

METHODS

Twenty-seven IBS patients (59% women; 10 IBS-diarrhea, 8 IBS-constipation, 9 IBS-mixed) and 23 age- and sex-matched HCs were examined. DNA methylation from peripheral blood mononuclear cells (PBMCs) was measured using HM450 BeadChip, and representative methylation differences were confirmed by bisulphite sequencing. Gene expression was measured using quantitative PCR. Gastrointestinal (GI) and non-GI symptoms were measured using validated questionnaires. Associations were tested using non-parametric methods.

KEY RESULTS

Genome-wide DNA methylation profiling of IBS patients compared with HCs identified 133 differentially methylated positions (DMPs) (mean difference ≥10%; p < 0.05). These genes were associated with gene ontology terms including glutathione metabolism related to oxidative stress and neuropeptide hormone activity. Validation by sequencing confirmed differential methylation of subcommissural organ (SCO)-Spondin (SSPO), glutathione-S-transferases mu 5 (GSTM5), and tubulin polymerization promoting protein genes. Methylation of two promoter CpGs in GSTM5 was associated with epigenetic silencing. Epigenetic changes in SSPO gene were positively correlated with hospital anxiety and depression scores in IBS patients (r > 0.4 and false discovery rate <0.05).

CONCLUSIONS & INFERENCES

This study is the first to comprehensively explore the methylome of IBS patients. We identified DMPs in novel candidate genes which could provide new insights into disease mechanisms; however, these preliminary findings warrant confirmation in larger, independent studies.

Neurotensin-induced miR-133α expression regulates neurotensin receptor 1 recycling through its downstream target aftiphilin

Neurotensin (NT) triggers signaling in human colonic epithelial cells by activating the G protein-coupled receptor, the neurotensin receptor 1 (NTR1). Activated NTR1 traffics from the plasma membrane to early endosomes, and then recycles. Although sustained NT/NTR1 signaling requires efficient NTR1 recycling, little is known about the regulation of NTR1 recycling. We recently showed that NT/NTR1 signaling increases expression of miR-133α. Herein, we studied the mechanism of NT-regulated miR-133α expression and examined the role of miR-133α in intracellular NTR1 trafficking in human NCM460 colonocytes. We found that NT-induced miR-133α upregulation involves the negative transcription regulator, zinc finger E-box binding homeobox 1. Silencing of miR-133α or overexpression of aftiphilin (AFTPH), a binding target of miR-133α, attenuated NTR1 trafficking to plasma membrane in human colonocytes, without affecting NTR1 internalization. We localized AFTPH to early endosomes and the trans-Golgi network (TGN) in unstimulated human colonic epithelial cells. AFTPH overexpression reduced NTR1 localization in early endosomes and increased expression of proteins related to endosomes and the TGN trafficking pathway. AFTPH overexpression and de-acidification of intracellular vesicles increased NTR1 expression. Our results suggest a novel mechanism of GPCR trafficking in human colonic epithelial cells by which a microRNA, miR-133α regulates NTR1 trafficking through its downstream target AFTPH.

Novel approaches to treating Clostridium difficile-associated colitis

Clostridium difficile is being recognized as a growing threat to many health-care systems. Epidemiology data shows that infection rates are soaring and the disease burden is increasing. Despite the efficacy of standard treatments, it is becoming evident that novel therapeutics will be required to tackle this disease. These new treatments aim to enhance the intestinal microbial barrier, activate the immune system and neutralize the toxins that mediate this disease. Many of these therapies are still in the beginning stages of investigation, however, in the next few years, more clinical data will become available to help implement many of these exciting new therapeutic approaches.

The Insect Peptide CopA3 Increases Colonic Epithelial Cell Proliferation and Mucosal Barrier Function to Prevent Inflammatory Responses in the Gut

The epithelial cells of the gut form a physical barrier against the luminal contents. The collapse of this barrier causes inflammation, and its therapeutic restoration can protect the gut against inflammation. EGF enhances mucosal barrier function and increases colonocyte proliferation, thereby ameliorating inflammatory responses in the gut. Based on our previous finding that the insect peptide CopA3 promotes neuronal growth, we herein tested whether CopA3 could increase the cell proliferation of colonocytes, enhance mucosal barrier function, and ameliorate gut inflammation. Our results revealed that CopA3 significantly increased epithelial cell proliferation in mouse colonic crypts and also enhanced colonic epithelial barrier function. Moreover, CopA3 treatment ameliorated Clostridium difficile toxin As-induced inflammation responses in the mouse small intestine (acute enteritis) and completely blocked inflammatory responses and subsequent lethality in the dextran sulfate sodium-induced mouse model of chronic colitis. The marked CopA3-induced increase of colonocyte proliferation was found to require rapid protein degradation of p21(Cip1/Waf1), and an in vitro ubiquitination assay revealed that CopA3 directly facilitated ubiquitin ligase activity against p21(Cip1/Waf1). Taken together, our findings indicate that the insect peptide CopA3 prevents gut inflammation by increasing epithelial cell proliferation and mucosal barrier function.

Corticotropin-Releasing Hormone Receptor 2 Signaling Promotes Mucosal Repair Responses after Colitis

The corticotropin-releasing hormone family mediates functional responses in many organs, including the intestine. Activation of corticotropin-releasing hormone receptor 2 (CRHR2) in the colonic mucosa promotes inflammation during acute colitis but inhibits inflammation during chronic colitis. We hypothesized that specific modulation of CRHR2 signaling in the colonic mucosa can promote restoration of the epithelium through stimulation of cell proliferative, migratory, and wound healing responses. Mucosal repair was assessed after dextran sodium sulfate (DSS)-induced colitis in mice receiving intracolonic injections of a CRHR2 antagonist or vehicle and in Crhr2(-/-) mice. Histologic damage, cytokine expression, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, and Ki-67 immunoreactivity were evaluated. Cell viability, proliferation, and migration were compared between parental and CRHR2-overexpressing colonic epithelial cells. Protein lysates were processed for phosphoprotein assays and a wound healing assay performed in vitro. Administration of a CRHR2 antagonist after DSS-induced colitis increased disease activity, delayed healing, and decreased epithelial cell proliferation in vivo. Colons from these mice also showed increased apoptosis and proinflammatory cytokine expression. Compared with controls, Crhr2(-/-) mice showed increased mortality in the DSS healing protocol. CRHR2-overexpressing cells had increased proliferation and migration compared with parental cells. Wound healing and signal transducer and activator of transcription 3 activity were elevated in CRHR2-overexpressing cells after urocortin 2 and IL-6 treatment, suggesting advanced healing progression. Our results suggest that selective CRHR2 activation may provide a targeted approach to enhance mucosal repair pathways after colitis.

MicroRNA214 Is Associated With Progression of Ulcerative Colitis, and Inhibition Reduces Development of Colitis and Colitis-Associated Cancer in Mice

BACKGROUND & AIMS

Persistent activation of the inflammatory response contributes to the development of inflammatory bowel diseases, which increase the risk of colorectal cancer. We aimed to identify microRNAs that regulate inflammation during the development of ulcerative colitis (UC) and progression to colitis-associated colon cancer (CAC).

METHODS

We performed a quantitative polymerase chain reaction analysis to measure microRNAs in 401 colon specimens from patients with UC, Crohn's disease, irritable bowel syndrome, sporadic colorectal cancer, or CAC, as well as subjects without these disorders (controls); levels were correlated with clinical features and disease activity of patients. Colitis was induced in mice by administration of dextran sodium sulfate (DSS), and carcinogenesis was induced by addition of azoxymethane; some mice also were given an inhibitor of microRNA214 (miR214).

RESULTS

A high-throughput functional screen of the human microRNAome found that miR214 regulated the activity of nuclear factor-κB. Higher levels of miR214 were detected in colon tissues from patients with active UC or CAC than from patients with other disorders or controls and correlated with disease progression. Bioinformatic and genome-wide profile analyses showed that miR214 activates an inflammatory response and is amplified through a feedback loop circuit mediated by phosphatase and tensin homolog (PTEN) and PDZ and LIM domain 2 (PDLIM2). Interleukin-6 induced signal transducer and activator of transcription 3 (STAT3)-mediated transcription of miR214. A miR214 chemical inhibitor blocked this circuit and reduced the severity of DSS-induced colitis in mice, as well as the number and size of tumors that formed in mice given azoxymethane and DSS. In fresh colonic biopsy specimens from patients with active UC, the miR214 inhibitor reduced inflammation by increasing levels of PDLIM2 and PTEN.

CONCLUSIONS

Interleukin-6 up-regulates STAT3-mediated transcription of miR214 in colon tissues, which reduces levels of PDLIM2 and PTEN, increases phosphorylation of AKT, and activates nuclear factor-κB. The activity of this circuit correlates with disease activity in patients with UC and progression to colorectal cancer.

Corticotropin Releasing Hormone and Urocortin 3 Stimulate Vascular Endothelial Growth Factor Expression through the cAMP/CREB Pathway

Colonic epithelium is the first line of defense against various pathological offenses in the gut. Previous studies have shown that the peptides of the corticotropin-releasing hormone (CRH) family modulate vascular endothelial growth factor (VEGF)-A production in other cells. Here we sought to investigate whether CRH and urocortin (Ucn) 3 regulate VEGF-A secretion in colonocytes through CRH receptors and to elucidate the underlying mechanism of action. CRH and Ucn 3 significantly increased the expression levels of VEGF-A mRNA and protein through CRH receptor 1 and 2, respectively, in human colonic epithelial cells and primary mouse intestinal epithelial cells. Underlying mechanisms involve activation of adenylyl cyclase with subsequent increase of intracellular cAMP level and increased DNA binding activity of transcription factor CREB on VEGF-A promoter region. Finally, genetic deficiency of CREB decreased intestinal inflammation and VEGF-A expression in a dextran sodium sulfate-induced colitis model. These results show that activation of CRH receptors by CRH ligands stimulates VEGF-A expression in intestinal epithelial cells through the cAMP/CREB pathway. Since VEGF-A boosts inflammatory responses through angiogenesis, these data suggest that CREB may be a key effector of CRH and Ucn 3-dependent inflammatory angiogenesis.

A Novel Peroxisome Proliferator-activated Receptor (PPAR)γ Agonist 2-Hydroxyethyl 5-chloro-4,5-didehydrojasmonate Exerts Anti-Inflammatory Effects in Colitis

Inflammatory bowel disease (IBD) is a chronic inflammatory disease with increasing incidence and prevalence worldwide. Here we investigated the newly synthesized jasmonate analogue 2-hydroxyethyl 5-chloro-4,5-didehydrojasmonate (J11-Cl) for its anti-inflammatory effects on intestinal inflammation. First, to test whether J11-Cl can activate peroxisome proliferator-activated receptors (PPARs), we performed docking simulations because J11-Cl has a structural similarity with anti-inflammatory 15-deoxy-Δ(12,14)-prostaglandin J2 (15d-PGJ2), one of the endogenous ligands of PPARγ. J11-Cl bound to the ligand binding domain of PPARγ in the same manner as 15d-PGJ2 and rosiglitazone, and significantly increased transcriptional activity of PPARγ. In animal experiments, colitis was significantly reduced in mice with J11-Cl treatment, determined by analyses of survival rate, body weight changes, clinical symptoms, and histological evaluation. Moreover, J11-Cl decreased production of pro-inflammatory cytokines including IL-6, IL-8, and G-CSF as well as chemokines including chemokine (C-C motif) ligand (CCL)20, chemokine (C-X-C motif) ligand (CXCL)2, CXCL3, and chemokine (C-X3-C motif) ligand 1 (CX3CL1) in colon tissues, and LPS or TNF-α-stimulated macrophages and epithelial cells. In contrast, production of anti-inflammatory cytokines including IL-2 and IL-4 as well as the proliferative factor, GM-CSF, was increased by J11-Cl. Furthermore, inhibition of MAPKs and NF-κB activation by J11-Cl was also observed. J11-Cl reduced intestinal inflammation by increasing the transcriptional activity of PPARγ and modulating inflammatory signaling pathways. Therefore, our study suggests that J11-Cl may serve as a novel therapeutic agent against IBD.

Diminished expression of CRHR2 in human colon cancer promotes tumor growth and EMT via persistent IL-6/Stat3 signaling

BACKGROUND & AIMS

Chronic inflammation promotes development and progression of colorectal cancer (CRC). We explored the distribution of Corticotropin-Releasing-Hormone (CRH)-family of receptors and ligands in CRC and their contribution in tumor growth and oncogenic EMT.

METHODS

mRNA expression of CRH-family members was analyzed in CRC (N=56) and control (N=46) samples, 7 CRC cell lines and normal NCM460 cells. Immunohistochemical detection of CRHR2 was performed in 20 CRC and 5 normal tissues. Cell proliferation, migration and invasion were compared between Urocortin-2 (Ucn2)-stimulated parental and CRHR2-overexpressing (CRHR2+) cells in absence or presence of IL-6. CRHR2/Ucn2-targeted effects on tumor growth and EMT were validated in SW620-xenograft mouse models.

RESULTS

CRC tissues and cell lines showed decreased mRNA and protein CRHR2 expression compared to controls and NCM460, respectively. The opposite trend was shown for Ucn2. CRHR2/Ucn2 signaling inhibited cell proliferation, migration, invasion and colony formation in CRC-CRHR2+ cells. In vivo, SW620-CRHR2+ xenografts showed decreased growth, reduced expression of EMT-inducers and elevated levels of EMT-suppressors. IL-1b, IL-6 and IL-6R mRNAs where diminished in CRC-CRHR2+ cells, while CRHR2/Ucn2 signaling inhibited IL-6-mediated Stat3 activation, invasion, migration and expression of downstream targets acting as cell cycle- and EMT-inducers. Expression of cell cycle- and EMT-suppressors was augmented in IL-6/Ucn2-stimulated CRHR2+ cells. In patients, CRHR2 mRNA expression was inversely correlated with IL-6R and vimentin levels and metastasis occurrence, while positively associated with E-cadherin expression and overall survival.

CONCLUSIONS

CRHR2 downregulation in CRC supports tumor expansion and spread through maintaining persistent inflammation and constitutive Stat3 activation. CRHR2^low CRC phenotypes are associated with higher risk for distant metastases and poor clinical outcomes.

Identification of Spinal Cord MicroRNA and Gene Signatures in a Model of Chronic Stress-Induced Visceral Hyperalgesia in Rat

Introduction

Animal studies have shown that stress could induce epigenetic and transcriptomic alterations essential in determining the balance between adaptive or maladaptive responses to stress. We tested the hypothesis that chronic stress in rats deregulates coding and non-coding gene expression in the spinal cord, which may underline neuroinflammation and nociceptive changes previously observed in this model.

Methods

Male Wistar rats were exposed to daily stress or handled, for 10 days. At day 11, lumbar spinal segments were collected and processed for mRNA/miRNA isolation followed by expression profiling using Agilent SurePrint Rat Exon and Rat miRNA Microarray platforms. Differentially expressed gene lists were generated using the dChip program. Microarrays were analyzed using the Ingenuity Pathways Analysis (IPA) tool from Ingenuity Systems. Multiple methods were used for the analysis of miRNA-mRNA functional modules. Quantitative real time RT-PCR for Interleukin 6 signal transducer (gp130), the Signal Transducer And Activator Of Transcription 3 (STAT3), glial fibrillary acidic protein and mir-17-5p were performed to confirm levels of expression.

Results

Gene network analysis revealed that stress deregulated different inflammatory (IL-6, JAK/STAT, TNF) and metabolic (PI3K/AKT) signaling pathways. MicroRNA array analysis revealed a signature of 39 deregulated microRNAs in stressed rats. MicroRNA-gene network analysis showed that microRNAs are regulators of two gene networks relevant to inflammatory processes. Specifically, our analysis of miRNA-mRNA functional modules identified miR-17-5p as an important regulator in our model. We verified miR-17-5p increased expression in stress using qPCR and in situ hybridization. In addition, we observed changes in the expression of gp130 and STAT3 (involved in intracellular signaling cascades in response to gp130 activation), both predicted targets for miR-17-5p. A modulatory role of spinal mir17-5p in the modulation of visceral sensitivity was confirmed in vivo.

Conclusion

Using an integrative high throughput approach, our findings suggest a link between miR-17-5p increased expression and gp130/STAT3 activation providing new insight into the possible mechanisms mediating the effect of chronic stress on neuroinflammation in the spinal cord.

Neurotensin--regulated miR-133α is involved in proinflammatory signalling in human colonic epithelial cells and in experimental colitis

OBJECTIVE

Neurotensin (NT) mediates colonic inflammation through its receptor neurotensin receptor 1 (NTR1). NT stimulates miR-133α expression in colonic epithelial cells. We investigated the role of miR-133α in NT-associated colonic inflammation in vitro and in vivo.

DESIGN

miR-133α and aftiphilin (AFTPH) levels were measured by quantitative PCR. Antisense (as)-miR-133α was administrated intracolonicaly prior to induction of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis and dextran sodium sulfate (DSS)-induced colitis. The effect of AFTPH was examined by gene silencing in vitro.

RESULTS

NT increased miR-133α levels in NCM-460 overexpressing NTR1 (NCM460-NTR1) and HCT-116 cells. NT-induced p38, ERK1/2, c-Jun, and NF-κB activation, as well as IL-6, IL-8 and IL-1β messenger RNA (mRNA) expression in NCM-460-NTR1 cells were reduced in miR-133α-silenced cells, while overexpression of miR-133α reversed these effects. MiR-133α levels were increased in TNBS (2 day) and DSS (5 day) colitis, while NTR1 deficient DSS-exposed mice had reduced miR-133α levels, compared to wild-type colitic mice. Intracolonic as-miR-133α attenuated several parameters of colitis as well expression of proinflammatory mediators in the colonic mucosa. In silico search coupled with qPCR identified AFTPH as a downstream target of miR-133α, while NT decreased AFTPH expression in NCM-460-NTR1 colonocytes. Gene silencing of AFTPH enhanced NT-induced proinflammatory responses and AFTPH levels were downregulated in experimental colitis. Levels of miR-133α were significantly upregulated, while AFTPH levels were downregulated in colonic biopsies of patients with ulcerative colitis compared to controls.

CONCLUSIONS

NT-associated colitis and inflammatory signalling are regulated by miR-133α-AFTPH interactions. Targeting of miR-133α or AFTPH may represent a novel therapeutic approach in inflammatory bowel disease.

Identification of a novel substance P (SP)-neurokinin-1 receptor (NK-1R) microRNA-221-5p inflammatory network in human colonic epithelial cells

BACKGROUND & AIMS

Substance P (SP), a neuropeptide member of the tachykinin family, plays a critical role in colitis. MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression. However, whether SP modulates expression of microRNAs in human colonic epithelial cells remains unknown.

METHODS

We performed microRNA profiling analysis of SP-stimulated human colonic epithelial NCM460 cells overexpressing neurokinin-1 receptor (NCM460-NK-1R). Targets of SP-regulated microRNAs were validated by real time polymerase chain reaction (RT-PCR). Functions of miRNAs were tested in NCM460-NK-1R cells and the TNBS and DSS models of colitis.

RESULTS

SP stimulated differential expression of 29 microRNAs, including miR-221-5p, the highest up regulated miR (by 12.6-fold) upon SP stimulation. Bioinformatic and luciferase reporter analyses identified interleukin 6 receptor (IL-6R) mRNA as a direct target of miR-221-5p in NCM460 cells. Accordingly, SP exposure of NCM460-NK-1R cells increased IL-6R mRNA expression, while overexpression of miR-221-5p reduced IL-6R expression. NF-κB and JNK inhibition decreased SP-induced miR-221-5p expression. MiR-221-5p expression was increased in both TNBS- and DSS-induced colitis and colonic biopsies from Ulcerative Colitis, but not Crohn's Disease subjects, compared to controls. In mice, intracolonic administration of a miR-221-5p chemical inhibitor, exacerbated TNBS-and DSS-induced colitis, and increased colonic TNF-α, Cxcl10, and Col2 α 1 mRNA expression. In situ hybridization in TNBS-and DSS-exposed colons revealed increased miR-221-5p expression primarily in colonocytes.

CONCLUSIONS

Our results reveal a novel NK-1R-miR-221-5p-IL-6R network that protects from colitis. The use of miR-221-5p mimics may be a promising approach for colitis treatment.

Effects of obesity on severity of colitis and cytokine expression in mouse mesenteric fat. Potential role of adiponectin receptor 1

In inflammatory bowel disease (IBD), obesity is associated with worsening of the course of disease. Here, we examined the role of obesity in the development of colitis and studied mesenteric fat-epithelial cell interactions in patients with IBD. We combined the diet-induce obesity with the trinitrobenzene sulfonic acid (TNBS) colitis mouse model to create groups with obesity, colitis, and their combination. Changes in the mesenteric fat and intestine were assessed by histology, myeloperoxidase assay, and cytokine mRNA expression by real-time PCR. Medium from human mesenteric fat and cultured preadipocytes was obtained from obese patients and those with IBD. Histological analysis showed inflammatory cell infiltrate and increased histological damage in the intestine and mesenteric fat of obese mice with colitis compared with all other groups. Obesity also increased the expression of proinflammatory cytokines including IL-1β, TNF-α, monocyte chemoattractant protein 1, and keratinocyte-derived chemokine, while it decreased the TNBS-induced increases in IL-2 and IFN-γ in mesenteric adipose and intestinal tissues. Human mesenteric fat isolated from obese patients and those with and IBD demonstrated differential release of adipokines and growth factors compared with controls. Fat-conditioned media reduced adiponectin receptor 1 (AdipoR1) expression in human NCM460 colonic epithelial cells. AdipoR1 intracolonic silencing in mice exacerbated TNBS-induced colitis. In conclusion, obesity worsens the outcome of experimental colitis, and obesity- and IBD-associated changes in adipose tissue promote differential mediator release in mesenteric fat that modulates colonocyte responses and may affect the course of colitis. Our results also suggest an important role for AdipoR1 for the fat-intestinal axis in the regulation of inflammation during colitis.

MicroRNA-133α regulates neurotensin-associated colonic inflammation in colonic epithelial cells and experimental colitis

Ulcerative colitis (UC) and Crohn's Disease (CD) are the two most common forms of Inflammatory Bowel Diseases (IBD) marked by chronic and persistent inflammation. Neurotensin (NT), together with its receptor, NT receptor 1 (NTR1), are important mediators in intestinal inflammation and their expression is upregulated in the intestine of experimental colitis models and UC colonic biopsies. MicroRNAs (miRNAs) are short, non-coding RNA molecules which act as transcription repressors. We have previously shown that NT exposure upregulates miR-133α expression in human colonocytes NCM460 cells overexpressing NTR1 (NCM460-NTR1). Recently, miR-133α was further examined forits role in NT-associated proinflammatory signaling cascades and acute colitis in vivo. Our study shows that NT-induced miR-133α upregulation modulates NF-κB phosphorylation and promotes proinflammatory cytokine production. In addition, intracolonicinjection of antisense-miR-133α before colitis induction improves histological scores and proinflammatory cytokine transcription. More importantly, dysregulation of miR-133α levels and aftiphilin (AFTPH), a newly-identified miR-133α downstream target, is found only in UC patients, but not in patients with CD. Taken together, we identified NTR1/miR-133α/aftiphilin as a novel regulatory axis involved in NT-associated colonic inflammation in human colonocytes, acute colitis mouse model and in colonic biopsies from UC patients. Our results also provide evidence that colonic levels of NTR1, miR-133α and aftiphilin may also serve as potential biomarkers in UC.

MicroRNA targeting for the therapy of colitis-associated colon cancer

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Background: Inflammatory Bowel Diseases (IBD) consist of ulcerative colitis (UC) and Crohn’s Disease (CD), which are characterized by activation of inflammatory responses. Patients with longstanding UC are at high risk of developing colorectal cancer. The identification of novel molecular targets with therapeutic potential for UC and UC-related dysplasia are of major importance. Methods: Using a high throughput functional suppressor screen of the human microRNAome, we identified microRNAs involved in the regulation nuclear factor kappa beta (NF-κB). We correlated microRNA expression levels with different clinicopathological parameters in 401 colonic specimens derived from patients with UC, CD, irritable bowel syndrome (IBS), sporadic colon cancer (CRC), colitis-associated cancer (CAC) and control subjects. Bioinformatic and molecular analyses were employed for the study of micoRNA-regulated signaling pathways. A microRNA specific chemical inhibitor was used to treat colonic biopsies ex vivo and murine CAC development in vivo. Results: The microRNA screen identified miR-214 as master regulator of NF-κB. MiR-214 levels are increased in colonic tissues from UC and CAC, but not from CD, IBS and CRC patients and positively correlate with UC disease activity and duration. STAT3 regulates miR-214 expression in colonocytes in vitro and STAT3 and miR-214 levels positively correlate in UC and CAC. MiR-214 regulates the expression of phosphatase and tensin homolog (PTEN) and PDZ and LIM domain 2 (PDLIM2) and both are decreased in colonic tissues of UC and CAC patients. MiR-214 is amplified through a feedback loop circuit and its overexpression increases the tumorigenic and invasive phenotype of colon cancer cells. A chemical miR-214 inhibitor perturbs this circuit in colonic biopsies from UC patients ex vivo while intracolonic delivery suppresses CAC growth in mice. Conclusions: Our findings demonstrate a gene controlling the inflammatory response specifically in UC and CAC. The miR-214 molecular circuit activity correlates with UC disease activity and duration. Activation of this circuit contributes to colitis-associated colon carcinogenesis, and its suppression has therapeutic potential for patients with UC-related dysplasia.

Anti-fibrogenic effects of the anti-microbial peptide cathelicidin in murine colitis-associated fibrosis

BACKGROUND AND AIMS

Cathelicidin (LL-37 in human and mCRAMP in mice) represents a family of endogenous antimicrobial peptides with anti-inflammatory effects. LL-37 also suppresses collagen synthesis, an important fibrotic response, in dermal fibroblasts. Here we determined whether exogenous cathelicidin administration modulates intestinal fibrosis in two animal models of intestinal inflammation and in human colonic fibroblasts.

METHODS

C57BL/6J mice (n=6 per group) were administered intracolonically with a trinitrobenzene sulphonic acid (TNBS) enema to induce chronic (6-7 weeks) colitis with fibrosis. mCRAMP peptide (5 mg/kg every 3 day, week 5-7) or cathelicidin gene (Camp)-expressing lentivirus (10⁷ infectious units week 4) were administered intracolonically or intravenously, respectively. 129Sv/J mice were infected with Salmonella typhimurium orally to induce cecal inflammation with fibrosis. Camp expressing lentivirus (10⁷ infectious units day 11) was administered intravenously.

RESULTS

TNBS-induced chronic colitis was associated with increased colonic collagen (col1a2) mRNA expression. Intracolonic cathelicidin (mCRAMP peptide) administration or intravenous delivery of lentivirus-overexpressing cathelicidin gene significantly reduced colonic col1a2 mRNA expression in TNBS-exposed mice, compared to vehicle administration. Salmonella infection also caused increased cecal inflammation associated with collagen (col1a2) mRNA expression that was prevented by intravenous delivery of Camp-expressing lentivirus. Exposure of human primary intestinal fibroblasts and human colonic CCD-18Co fibroblasts to transforming growth factor-beta1 (TGF-beta1) and/or insulin-like growth factor 1 induced collagen protein and mRNA expression, that was reduced by LL-37 (3-5 µM) through a MAP kinase-dependent mechanism.

CONCLUSION

Cathelicidin can reverse intestinal fibrosis by directly inhibiting collagen synthesis in colonic fibroblasts.