Genome-wide expression profiling during protection from colitis by regulatory T cells

Mesenchymal stem cells-derived extracellular vesicles containing miR-378a-3p inhibit the occurrence of inflammatory bowel disease by targeting GATA2

This study sought to determine whether mesenchymal stem cells‐derived extracellular vesicles (MSCs‐EVs) carrying microRNA‐378a‐3p (miR‐378a‐3p) could affect the pathogenesis of inflammatory bowel disease (IBD) by regulating the GATA‐binding protein 2 (GATA2)/aquaporin‐4 (AQP4)/peroxisome proliferator‐activated receptor α (PPAR‐α) axis. Initially, colon mucosa biopsy tissues were harvested from healthy controls and patients with IBD for qRT‐PCR and immunohistochemistry analysis. EVs harvested from MSCs and lipopolysaccharide (LPS) were used to stimulate the M064 cells to establish an in vitro inflammation cell model. Besides, 2,4,6‐trinitrobenzene sulfonic acid intracolon administration was performed to establish in vivo IBD mouse models. After loss‐ and gain‐of‐function assays, the regulatory role of MSCs‐derived EVs loaded with manipulated miR‐378a‐3p in IBD in relation to GATA2/AQP4/PPAR‐α were explored. Upregulation of GATA2 was identified in the colon tissue of IBD patients. GATA2, which was a target gene of miR‐378a‐3p, transcriptionally upregulated AQP4. After silencing of GATA2, LPS‐induced apoptosis of M064 cells was reduced by the downregulation of AQP4. Decreased AQP4 contributed to PPAR‐α pathway inactivation and weakened the LPS‐induced apoptosis of M064 cells. MSCs‐EVs delivering miR‐378a‐3p suppressed the GATA2/AQP4/PPAR‐α pathway, which reduced LPS‐induced apoptosis of M064 cells and the occurrence of IBD in mice. Altogether, the current study illustrated that MSCs‐EVs transfer miR‐378a‐3p to reduce the GATA2 expression, which downregulates AQP4 to block the PPAR‐α signalling pathway, thus suppressing the occurrence of IBD.

Cyanidin-3-O-glucoside inhibits NF-kB signalling in intestinal epithelial cells exposed to TNF-α and exerts protective effects via Nrf2 pathway activation

Chronic intestinal inflammatory disorders, such as Inflammatory Bowel Diseases (IBDs), are characterized by excessive release of proinflammatory mediators, intestinal barrier dysfunction and excessive activation of NF-kB cascade. Previous studies shown that TNF-α plays a central role in intestinal inflammation of IBDs and supported beneficial effects of flavonoids against chronic inflammatory diseases. In this study, we employed an in vitro model of acute intestinal inflammation using intestinal Caco-2 cells exposed to TNF-α. The protective effects of cyanidin-3-glucoside (C3G), an anthocyanin widely distributed in mediterranean diet, were then evaluated. Caco-2 cells exposure to TNF-α activated NF-kB proinflammatory pathway and induced IL6 and COX-2 expression. Cells pretreatment for 24h with C3G (20-40μM) prevented TNF-α-induced changes, and improved intracellular redox status. Our results demonstrated that C3G, also without any kind of stimulus, increased the translocation of the transcription factor Nrf2 into the nucleus so activating antioxidant and detoxifying genes. In conclusion, C3G exhibited protective effects through the inhibition of NF-kB signalling in Caco-2 cells and these beneficial effects appear to be due to its ability to activate cellular protective responses modulated by Nrf2. These data suggest that anthocyanins could contribute, as complementary or preventive approaches, to the management of chronic inflammatory diseases.

NOX2-dependent regulation of inflammation

NADPH oxidase (NOX) isoforms together have multiple functions that are important for normal physiology and have been implicated in the pathogenesis of a broad range of diseases, including atherosclerosis, cancer and neurodegenerative diseases. The phagocyte NADPH oxidase (NOX2) is critical for antimicrobial host defence. Chronic granulomatous disease (CGD) is an inherited disorder of NOX2 characterized by severe life-threatening bacterial and fungal infections and by excessive inflammation, including Crohn's-like inflammatory bowel disease (IBD). NOX2 defends against microbes through the direct antimicrobial activity of reactive oxidants and through activation of granular proteases and generation of neutrophil extracellular traps (NETs). NETosis involves the breakdown of cell membranes and extracellular release of chromatin and neutrophil granular constituents that target extracellular pathogens. Although the immediate effects of oxidant generation and NETosis are predicted to be injurious, NOX2, in several contexts, limits inflammation and injury by modulation of key signalling pathways that affect neutrophil accumulation and clearance. NOX2 also plays a role in antigen presentation and regulation of adaptive immunity. Specific NOX2-activated pathways such as nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor that induces antioxidative and cytoprotective responses, may be important therapeutic targets for CGD and, more broadly, diseases associated with excessive inflammation and injury.

Quality of methods reporting in animal models of colitis

BACKGROUND

Current understanding of the onset of inflammatory bowel diseases relies heavily on data derived from animal models of colitis. However, the omission of information concerning the method used makes the interpretation of studies difficult or impossible. We assessed the current quality of methods reporting in 4 animal models of colitis that are used to inform clinical research into inflammatory bowel disease: dextran sulfate sodium, interleukin-10, CD45RB T cell transfer, and 2,4,6-trinitrobenzene sulfonic acid (TNBS).

METHODS

We performed a systematic review based on PRISMA guidelines, using a PubMed search (2000-2014) to obtain publications that used a microarray to describe gene expression in colitic tissue. Methods reporting quality was scored against a checklist of essential and desirable criteria.

RESULTS

Fifty-eight articles were identified and included in this review (29 dextran sulfate sodium, 15 interleukin-10, 5 T cell transfer, and 16 TNBS; some articles use more than 1 colitis model). A mean of 81.7% (SD = ±7.038) of criteria were reported across all models. Only 1 of the 58 articles reported all essential criteria on our checklist. Animal age, gender, housing conditions, and mortality/morbidity were all poorly reported.

CONCLUSIONS

Failure to include all essential criteria is a cause for concern; this failure can have large impact on the quality and replicability of published colitis experiments. We recommend adoption of our checklist as a requirement for publication to improve the quality, comparability, and standardization of colitis studies and will make interpretation and translation of data to human disease more reliable.

Effects of retinoids in mouse models of colitis: benefit or danger to the gastrointestinal tract?

BACKGROUND

In vitro and in vivo data have shown that retinoid treatment promotes an anti-inflammatory milieu with few adverse effects toward the gastrointestinal tract. The in vivo studies reported here further evaluate retinoid effects in 2 mouse models of inflammatory bowel disease.

METHOD

Chronic dextran sulfate sodium colitis was induced in age- and weight-matched C57Bl/6 mice by 4 cycles of dextran sulfate sodium administration (6-8 animals/group). At cycle 4, animals were administered 13-cis-retinoic acid (isotretinoin, 30 mg/kg) or vehicle (oral gavage) or 4-oxo-13-cis-retinoic acid (15 mg/kg, intraperitoneal) daily. T-cell transfer colitis was induced in CB17 SCID mice by transfer of naive CD4CD62L T cells and treated by transfer of regulatory CD4CD25 T cells (4-6 animals/group); isolated from BALB/c mice after treatment with isotretinoin or vehicle, as above, for 2 weeks. Assessments included endoscopic and histological scores, myeloperoxidase activity, serum cytokines, and plasma isotretinoin levels.

RESULTS

Retinoid-treated animals with colitis showed comparable changes in myeloperoxidase activity, and endoscopic and histological scores, versus untreated animals with colitis. Modest and comparable changes were seen in body weight and colon length in animals injected with naive T cells from isotretinoin-treated donors versus those injected with T cells from vehicle-treated donors. Retinoid treatment was consistently associated with lower interleukin-12 levels, which, after the transfer of naive T cells from isotretinoin-treated donors, supported isotretinoin-mediated predisposition of naive T cells toward reduced proinflammatory cytokine expression. Colitis had no effect on isotretinoin exposure.

CONCLUSIONS

Retinoids attenuate the proinflammatory cytokine response in vivo, with only modest effects on body weight and parameters of gastrointestinal morphology.

Consumption of probiotics increases the effect of regulatory T cells in transfer colitis

BACKGROUND

Probiotics may alter immune regulation. Recently, we showed that the probiotic bacteria Lactobacillus acidophilus NCFM™ influenced the activity of regulatory T cells (Tregs) in vitro. The aim of the present work was to demonstrate if L. acidophilus NCFM™ also affects the function of Tregs in vivo.

METHODS

Development of colitis after transfer of CD4+CD25- T cells and protection from colitis by Tregs was studied in immunodeficient SCID mice which were simultaneously tube-fed with L. acidophilus NCFM™ or L. salivarius Ls-33 for 5 weeks.

RESULTS

Probiotic-fed SCID mice transplanted with low numbers of Tregs in addition to the disease-inducing T cells were completely protected from colitis. This was in contrast to the control group, which showed intermediate levels of inflammation. In addition, feeding with probiotics lowered serum levels of inflammatory cytokines in both colitic mice and in mice protected from colitis by Tregs. Gene expression patterns of rectum samples of protected mice that receive either one of the probiotics showed a closer resemblance to naïve SCID mice than did patterns of the control group. The mechanism of action of the probiotics appears to be an indirect effect by inducing a Treg-favorable environment rather than a direct effect on the Tregs.

CONCLUSIONS

L. acidophilus NCFM™ and L. salivarius Ls-33 feeding of SCID mice increases the in vivo effect of Tregs, resulting in a gene expression pattern in the rectum resembling that of the naïve SCID mouse.

Protective pathways against colitis mediated by appendicitis and appendectomy

Appendicitis followed by appendectomy (AA) at a young age protects against inflammatory bowel disease (IBD). Using a novel murine appendicitis model, we showed that AA protected against subsequent experimental colitis. To delineate genes/pathways involved in this protection, AA was performed and samples harvested from the most distal colon. RNA was extracted from four individual colonic samples per group (AA group and double-laparotomy control group) and each sample microarray analysed followed by gene-set enrichment analysis (GSEA). The gene-expression study was validated by quantitative reverse transcription-polymerase chain reaction (RT-PCR) of 14 selected genes across the immunological spectrum. Distal colonic expression of 266 gene-sets was up-regulated significantly in AA group samples (false discovery rates < 1%; P-value < 0·001). Time-course RT-PCR experiments involving the 14 genes displayed down-regulation over 28 days. The IBD-associated genes tnfsf10, SLC22A5, C3, ccr5, irgm, ptger4 and ccl20 were modulated in AA mice 3 days after surgery. Many key immunological and cellular function-associated gene-sets involved in the protective effect of AA in experimental colitis were identified. The down-regulation of 14 selected genes over 28 days after surgery indicates activation, repression or de-repression of these genes leading to downstream AA-conferred anti-colitis protection. Further analysis of these genes, profiles and biological pathways may assist in developing better therapeutic strategies in the management of intractable IBD.

Colonic transcriptional profiling in resistance and susceptibility to trichuriasis: phenotyping a chronic colitis and lessons for iatrogenic helminthosis

BACKGROUND

Helminth therapy is advocated to restore and maintain control of inflammatory responses, particularly chronic colitis. However, helminths can induce chronic colitis in susceptible individuals. Susceptibility has an immunogenetic basis: defining this is essential if nematode therapy is to be successfully and safely targeted in inflammatory bowel disease (IBD). To validate a preclinical mouse model we phenotyped the response to Trichuris muris in mice. We determined colonic transcriptional activity in naïve and infected mice and linked differential gene expression to mechanistic pathways.

METHODS

T. muris-infected resistant (BALB/c) and susceptible (AKR) mice were studied to a chronic colitic timepoint (day 35). Colonic genome-wide expression was performed by microarray. Significant transcriptional changes were analyzed by cluster and gene ontology filtering and KEGG pathway mapping.

RESULTS

Day 35 infected AKR displayed chronic diarrhea, weight loss, and transmural colonic inflammation; BALB/c remained asymptomatic, cleared the infection, and demonstrated normal histology. Compared to BALB/c mice, infected AKR upregulated gene expression clusters were overrepresented by immune response, chemotaxis, and apoptosis pathways. Cellular/tissue homeostasis and tight junction pathways dominated downregulated AKR expression clusters. Infected AKR T-helper cell development/polarization markers demonstrated predominant T(H) 1/T(H) 17 transcriptional activity. Colitic AKR data mirrored established murine models and human colitis.

CONCLUSIONS

T. muris infection in the mouse shows striking phenotypic and transcriptional similarities to widely used models of IBD and human IBD. This preclinical mouse model presents a platform to examine biological commonalities among chronic colitides. However, these data urge caution in untargeted therapeutic helminth use until risk/benefit in susceptible individuals is more fully understood.

Temporal genomewide expression profiling of DSS colitis reveals novel inflammatory and angiogenesis genes similar to ulcerative colitis

Dextran sodium sulfate (DSS)-induced colitis is widely used to study pathological mechanisms and potential treatments of inflammatory bowel disease. Because temporal changes in genome expression profiles remain unknown in this model, we performed whole genome expression profile analysis during the development of DSS colitis in comparison with ulcerative colitis (UC) specimens to identify novel and common responses during disease. Colon tissue from DSS-treated mice was collected at days 0, 2, 4, and 6. Half of each specimen was used for histopathological analysis and half for Affymetrix whole genome expression profiling and qRT-PCR validation. Genesifter and Ingenuity software analysis was used to identify differentially expressed genes and perform interactive network analysis. Identified DSS-associated genes in mice were also compared with UC patient data. We identified 1,609 genes that were significantly altered during DSS colitis; the majority were functionally related to inflammation, angiogenesis, metabolism, biological adhesion, cellular growth and proliferation, and cell-to-cell signaling responses. Five hundred and one genes were progressively upregulated, while one hundred seventy-three genes were progressively downregulated. Changes in gene expression were validated in a subset of 33 genes by qRT-PCR, with r(2) = 0.925. Ingenuity gene interaction network analysis revealed novel relationships among antigen presentation, cell morphology, and other biological functions in the DSS mouse. Finally, DSS colitis gene array data were compared with UC patient array data: 152 genes were similarly upregulated, and 22 genes were downregulated. Temporal genomewide expression profile analysis of DSS-induced colitis revealed novel associations with various immune responses and tissue remodeling events such as angiogenesis similar to those in UC patients. This study provides a comprehensive view of DSS colitis changes in colon gene expression and identifies common molecules with clinical specimens that are interesting targets for further investigation.

Cellular mediators of inflammation: tregs and TH17 cells in gastrointestinal diseases

Human lymphocyte subpopulations were originally classified as T- and B-cells in the 70s. Later, with the development of monoclonal antibodies, it became possible to recognize, within the T-cells, functional populations: CD4⁺ and CD8⁺. These populations were usually referred to as “helper” and “suppressor” cells, respectively. However several investigations within the CD8 cells failed to detect a true suppressor activity. Therefore the term suppressor was neglected because it generated confusion. Much later, true suppressor activity was recognized in a subpopulation of CD4 cells characterized by high levels of CD25. The novel population is usually referred to as T regulatory cells (Tregs) and it is characterized by the expression of FoxP3. The heterogeneity of CD4 cells was further expanded by the recent description of a novel subpopulation characterized by production of IL-17. These cells are generally referred to as T_H17. They contribute to regulate the overall immune response together with other cytokine-producing populations. Treg and T_H17 cells are related because they could derive from a common progenitor, depending on the presence of certain cytokines. The purpose of this review is to summarize recent findings of the role of these novel populations in the field of human gastroenterological disease.

Limitations in assessment of mucosal healing in inflammatory bowel disease

An emerging parameter to define the effectiveness of new therapeutic agents in clinical trials, and by extension, for use in day-to-day clinical practice has been labeled mucosal healing. It has been hypothesized that complete healing of the intestinal mucosa in inflammatory bowel diseases should result in reduced disease complications, reduced hospitalization and reduced surgical treatment. By implication, the natural history of inflammatory bowel disease might then be altered. Measurement of mucosal healing, however, is largely observational, requiring repeated invasive endoscopic examinations, sometimes with mucosal biopsies. Other indirect imaging methods may play a role in this assessment along with other surrogate markers, including intestinal permeability. These measurements may have significant limitations that prohibit precise correlation with symptom-based disease activity indices in clinical trials. This likely reflects the dynamic nature of this evolving and individualized inflammatory process that tends to be focused, but not limited, to the mucosa of the intestinal tract.

Disruption of CCR5-dependent homing of regulatory T cells inhibits tumor growth in a murine model of pancreatic cancer

Tumors evade immune destruction by actively inducing immune tolerance through the recruitment of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg). We have previously described increased prevalence of these cells in pancreatic adenocarcinoma, but it remains unclear what mechanisms are involved in recruiting Tregs into the tumor microenvironment. Here, we postulated that chemokines might direct Treg homing to tumor. We show, in both human pancreatic adenocarcinoma and a murine pancreatic tumor model (Pan02), that tumor cells produce increased levels of ligands for the CCR5 chemokine receptor and, reciprocally, that CD4(+) Foxp3(+) Tregs, compared with CD4(+) Foxp3(-) effector T cells, preferentially express CCR5. When CCR5/CCL5 signaling is disrupted, either by reducing CCL5 production by tumor cells or by systemic administration of a CCR5 inhibitor (N,N-dimethyl-N-{{4-{[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl}amino}}benzyl]-N,N-dimethyl-N- {{{4-{{{[2-(4-methylphenyl)-6,7-dihydro-5H-benzocycloheptan-8-yl]carbonyl}amino}}benzyl}}}tetrahydro-2H-pyran-4-aminiumchloride; TAK-779), Treg migration to tumors is reduced and tumors are smaller than in control mice. Thus, this study demonstrates the importance of Tregs in immune evasion by tumors, how blockade of Treg migration might inhibit tumor growth, and, specifically in pancreatic adenocarcinoma, the role of CCR5 in the homing of tumor-associated Tregs. Selective targeting of CCR5/CCL5 signaling may represent a novel immunomodulatory strategy for the treatment of cancer.

Genome-wide gene expression profiling of SCID mice with T-cell-mediated Colitis

Inflammatory bowel disease (IBD) is a multifactorial disorder with an unknown aetiology. The aim of this study is to employ a murine model of IBD to identify pathways and genes, which may play a key role in the pathogenesis of IBD and could be important for discovery of new disease markers in human disease. Here, we have investigated severe combined immunodeficient (SCID) mice, which upon adoptive transfer with concanavalin A-activated CD4(+) T cells develop inflammation of the colon with predominance in rectum. Mice with increasing level of inflammation was studied. RNA from rectum of transplanted and non-transplanted SCID mice was investigated by a genome-wide gene expression analysis using the Affymetrix mouse expression array 430A (MOE430A) including 22,626 probe sets. A significant change in gene expression (P = 0.00001) is observed in 152 of the genes between the non-transplanted control mice and colitis mice, and among these genes there is an overrepresentation of genes involved in inflammatory processes. Some of the most significant genes showing higher expression encode S100A proteins and chemokines involved in trafficking of leucocytes in inflammatory areas. Classification by gene clustering based on the genes with the significantly altered gene expression corresponds to two different levels of inflammation as established by the histological scoring of the inflamed rectum. These data demonstrate that this SCID T-cell transfer model is a useful animal model for human IBD and can be used for suggesting candidate genes involved in the pathogenesis and for identifying new molecular markers of chronic inflammation in human IBD.