Murine Colonic Epithelial Cells Research Articles

Critical role of thrombospondin-1 in promoting intestinal mucosal wound repair.

Thrombospondin-1 (TSP1) is a matricellular protein associated with the regulation of cell migration through direct binding interactions with integrin proteins and by associating with other receptors known to regulate integrin function, including CD47 and CD36. We previously demonstrated that deletion of an epithelial TSP1 receptor, CD47, attenuates epithelial wound repair following intestinal mucosal injury. However, the mechanisms by which TSP1 contributes to intestinal mucosal repair remain poorly understood. Our results show upregulated TSP1 expression in colonic mucosal wounds and impaired intestinal mucosal wound healing in vivo upon intestinal epithelium-specific loss of TSP1 (VillinCre/+ Thbs1fl/fl or Thbs1ΔIEC mice). We report that exposure to exogenous TSP1 enhanced migration of intestinal epithelial cells in a CD47- and TGF-β1-dependent manner and that deficiency of TSP1 in primary murine colonic epithelial cells resulted in impaired wound healing. Mechanistically, TSP1 modulated epithelial actin cytoskeletal dynamics through suppression of RhoA activity, activation of Rho family small GTPase (Rac1), and changes in filamentous-actin bundling. Overall, TSP1 was found to regulate intestinal mucosal wound healing via CD47 and TGF-β1, coordinate integrin-containing cell-matrix adhesion dynamics, and remodel the actin cytoskeleton in migrating epithelial cells to enhance cell motility and promote wound repair.

A Facile Method to Append a Bio-ID Tag to Endogenous Mutant Kras Alleles.

KRAS mutations occur in approximately ~50% of colorectal cancers (CRCs) and are associated with poor prognosis and resistance to therapy. While these most common mutations found at amino acids G12, G13, Q61, and A146 have long been considered oncogenic drivers of CRC, emerging clinical data suggest that each mutation may possess different biological functions, resulting in varying consequences in oncogenesis. Currently, the mechanistic underpinnings associated with each allelic variation remain unclear. Elucidating the unique effectors of each KRAS mutant could both increase the understanding of KRAS biology and provide a basis for allele-specific therapeutic opportunities. Biotinylation identification (BioID) is a method to label and identify proteins located in proximity of a protein of interest. These proteins are captured through the strong interaction between the biotin label and streptavidin bead and subsequently identified by mass spectrometry. Here, we developed a protocol using CRISPR-mediated gene editing to generate endogenous BioID2-tagged KrasG12D and KrasG12V isogenic murine colon epithelial cell lines to identify unique protein proximity partners by BioID.

TRPA1 protects mice from pathogenic Citrobacter rodentium infection via maintaining the colonic epithelial barrier function.

Transient receptor potential ankyrin 1 (TRPA1) is expressed in gastrointestinal tract and plays important roles in intestinal motility and visceral hypersensitivity. However, the potential role of TRPA1 in host defense, particularly against intestinal pathogens, is unknown. Here, we show that Trpa1 knockout mice exhibited increased susceptibility to Citrobacter rodentium infection, associated with the increased severity of diarrhea and intestinal permeability associated with the disrupted tight junctions (TJs) in colonic epithelia. We further demonstrated the expression of TRPA1 in murine colonic epithelial cells (CECs) and human epithelial Caco-2 cells both at protein level and transcription level. Using calcium imaging, TRPA1 agonists allyl isothiocyanates (AITC) and hydrogen peroxide were observed to induce a transient Ca2+ response in Caco-2 cells, respectively. Moreover, TRPA1 knockdown in Caco-2 cells resulted in the decreased expression of TJ proteins, ZO-1 and Occludin, and in the increased paracellular permeabilities and the reduced TEER values of Caco-2 monolayers in vitro. Furthermore, inhibition of TRPA1 by HC-030031 in the confluent Caco-2 cells caused the altered distribution and expression of TJ proteins, ZO-1, Occludin, and Claudin-3, and exacerbated the bacterial endotoxin lipopolysaccharide (LPS)-induced damage to these TJ proteins and actin cytoskeleton. By contrast, AITC pretreatment restored the distribution and expression of these TJ proteins in the confluent Caco-2 cells upon LPS challenge. Our results identify an unrecognized protective role of TRPA1 in host defense against an enteric bacterial pathogen by maintaining colonic epithelium barrier function, at least in part, via preserving the distribution and expression of TJ proteins in CECs.

Intestinal epithelial BLT1 promotes mucosal repair.

Acute and chronic intestinal inflammation is associated with epithelial damage, resulting in mucosal wounds in the forms of erosions and ulcers in the intestinal tract. Intestinal epithelial cells (IECs) and immune cells in the wound milieu secrete cytokines and lipid mediators to influence repair. Leukotriene B4 (LTB4), a lipid chemokine, binds to its receptor BLT1 and promotes migration of immune cells to sites of active inflammation; however, a role for intestinal epithelial BLT1 during mucosal wound repair is not known. Here we report that BLT1 was expressed in IECs both in vitro and in vivo, where it functioned as a receptor not only for LTB4 but also for another ligand, resolvin E1. Intestinal epithelial BLT1 expression was increased when epithelial cells were exposed to an inflammatory microenvironment. Using human and murine primary colonic epithelial cells, we reveal that the LTB4/BLT1 pathway promoted epithelial migration and proliferation leading to accelerated epithelial wound repair. Furthermore, in vivo intestinal wound repair experiments in BLT1-deficient mice and bone marrow chimeras demonstrated an important contribution of epithelial BLT1 during colonic mucosal wound repair. Taken together, our findings show a potentially novel prorepair in IEC mechanism mediated by BLT1 signaling.

Editors' Selections from Relevant Scientific Publications

Transient bacterial infection leads to colon tumorigenesis (art work from Cancer Discovery)New research links the enteropathogenic and enterohemorrhagic strains of Escherichia coli bacteria responsible for hundreds of millions of cases of diarrheal disease annually to heightened cancer risk. Liu et al. have identified a genotoxin produced by the murine counterpart of these pathogens, Citrobacter rodentium, that can fuel onset of colon cancer. This protein, UshA, inflicted considerable genomic damage on murine colon epithelial cells even after transient exposure, and C. rodentium infection led to accelerated tumorigenesis in a cancer-prone mouse model. UshA is also produced by human-infecting E. coli, and this mechanism could pose a critical link between high prevalence of diarrheal disease and climbing colon cancer rates in sub-Saharan Africa.Liu Y, … Wan F. Cancer Discov. 2022 Jan;12(1):236-249.Illustration of breast tumor and tumor microenvironment (adapted from an image by Adrián Blanco-Gómez for Cancer Research)This HTAN Breast PreCancer Atlas study of ductal carcinoma in situ (DCIS) used a multiplex ion beam imaging by time of flight and a 37-plex antibody staining panel to analyze tumor microenvironment (TME) in 79 patient-matched surgical samples. Risom et al. found four TME states that were defined based on the location and function of myoepithelium, fibroblasts, and immune cells. Critically, disruption of the myoepithelial was more advanced in DCIS patients that did not develop invasive breast cancer, suggesting this process could be protective against disease recurrence. This study improves understanding of the drivers of breast cancer relapse and emphasizes the crucial role of TME in disease progression.Risom T, … Angelo M. Cell. 2022 Jan 20;185(2):299-310.e18.Ductal carcinoma in situ (by Kauczuk via Wikimedia Commons)This histological, molecular, and immunological profiling study explored the diverse, interconnected immune landscapes in 39 premalignant lesions from patients with ductal carcinoma in situ. Nachmanson et al. used multiple microdissected regions to analyze phenotype and subtype heterogeneity, B- and T-lymphocyte spatial analysis, mutational profiling, driver mutations, and immunological status. The authors successfully isolated regions within the same sample to characterize different histological features and infer phylogenetic relationships. This study provided richness to the breast pre-cancer atlas and contributed to better models for outcomes and progress risk.Nachmanson D, …Harismendy O. NPJ Breast Cancer. 2022 Jan 13;8(1):6.Illustration of gene variants and cancer cumulative risk (adapted from figures by Michael J. Hall for Cancer Prevention Research)A pair of recent clinical studies identified nine genes that, when disrupted by truncating or missense mutations, can meaningfully increase breast cancer risk. The researchers of the Breast Cancer Association Consortium have now conducted a follow-up investigation of nearly 90,000 participants from one of these trials, BRIDGES, to determine which tumor types are associated with these mutations. This analysis revealed distinctive patterns in terms of age of onset and histological type—for example, triple-negative tumors were notably overrepresented in women with BRCA1 or BARD1 mutations. These results could thus enable more accurate risk prediction based on genetic test results and inform the development of improved screening guidelines.Breast Cancer Association Consortium, … Easton DF. JAMA Oncol. 2022 Jan 27:e216744.44.Colorectal cancer (by Dcoetzee via Wikimedia Commons)People who were obese in early adulthood have an increased risk of early-onset colorectal cancer later in life. Obesity has long been known as a risk factor for many cancers, but weight loss prior to diagnosis can confound the association. Li et al. analyzed the medical records of 6602 colorectal cancer patients enrolled in a German screening study and compared them to 7950 matched controls. They found that people who had been obese at age 20 or 30 were 2.6 times and 2 times, respectively, more likely to develop colorectal cancer before age 55 as those of normal weight at those ages. The authors say that body mass history, not just current weight, should be considered when assessing a person's risk of colorectal cancer.Li H, … Brenner H. Gastroenterology. 2021 Dec 13:S0016-5085(21)04074-9.Illustration of declines in cancer screening and diagnosis due to the Covid-19 pandemic (SARS-Cov-2 image is by Iketsi via Wikimedia Commons)Cancer screenings and diagnosis procedures – and the number of new cancers diagnosed – declined significantly due to the Covid-19 pandemic. Restrictions on elective medical procedures resulted in the widespread cancellation of appointments and decreased many people's access to care. Englum et al. reviewed the medical records of more than 9 million veterans who visited 1244 Veterans’ Affairs facilities across the United States between 2016 and 2020. They found that these facilities performed 45% fewer colonoscopies in 2020 than the average from previous years, as well as fewer CT scans, biopsies, and cystoscopies. The number of new cancer diagnoses dropped by 13% to 23%, which the authors say necessitates a recovery plan to ensure that health centers can catch up with the backlog and meet the needs of patients whose healthcare access was disrupted.Englum BR… Lal BK. Cancer. 2022 Mar 1;128(5):1048-1056.

Ban-Lan-Gen Granule Alleviates Dextran Sulfate Sodium-Induced Chronic Relapsing Colitis in Mice via Regulating Gut Microbiota and Restoring Gut SCFA Derived-GLP-1 Production.

PurposeGLP-1 based therapy represents a new treatment option for inflammatory bowel disease. Ban-Lan-Gen (BLG) granule, a known anti-viral TCM formulation, exhibits potential anti-inflammatory activities in treating various kinds of inflammation. However, its anti-inflammatory effect on colitis and the underlying mechanisms remain unknown.MethodsDextran sulfate sodium (DSS)-induced chronic relapsing colitis in mice was established. The disease activity index, histological sign of damage, and levels of proinflammatory cytokines were performed to assess the protective effects of BLG. Serum GLP-1 level and colonic Gcg, GPR41 and GRP43 expression, the community compositions of gut microbiota, the levels of SCFAs in the feces and GLP-1 release from primary murine colon epithelial cells were performed to characterize the effects of BLG on gut microbiota and gut SCFA derived-GLP-1 production.ResultsBLG treatment significantly alleviated body weight loss, DAI, colon shortening, colon tissue damage, and pro-inflammatory cytokine levels of TNF-α, IL-1β and IL-6 in the colon tissues. Moreover, BLG treatment could observably restore colonic Gcg, GPR41 and GRP43 expression and serum GLP-1 level of colitic mice, as well as correct the alteration of gut microbiota in colitic mice by increasing the abundances of SCFA-producing bacteria, eg, Akkermansia and Prevotellaceae_UCG-001, and decreasing the abundances of bacteria, eg, Eubacterium_xylanophilum_group, Ruminococcaceae_UCG-014, Intestinimonas, and Oscillibacter. Furthermore, BLG treatment could markedly increase the levels of SCFAs in feces of colitic mice. In parallel, ex vivo assay also showed that and the extract of feces from BLG-treatment mice could greatly stimulate the secretion of GLP-1 from primary murine colon epithelial cells.ConclusionThese findings suggest that the anti-colitis effects of BLG are achieved at least partly by regulating gut microbiota and restoring gut SCFA derived-GLP-1 production, and BLG has the potential to be developed as a promising agent for the treatment of chronic relapsing colitis.

P057 Mucosal microbiota adapts to ATF6-induced alterations in host lipid metabolism with prognostic value in colorectal cancer

Abstract Background Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. The endoplasmic reticulum unfolded protein response (UPRER) signal transducer activating transcription factor 6 (ATF6) is a clinically relevant pre-cancerous marker in CRC and colitis-associated CRC. We established the interrelated role of the microbiota and ATF6 signalling as a novel tumor-promoting mechanism in our transgenic mouse model of spontaneous microbiota-dependent ATF6-driven CRC (nATF6IEC). Methods To elucidate the transcriptional program initiated by acute and chronic ATF6 signalling, mRNA sequencing analyses of murine colonic intestinal epithelial cells were performed 4 days or 5 weeks after induction of ATF6, respectively. Germfree (GF) mice served to dissect microbiota contribution to the transcriptional response. CRC patient datasets (TCGA) were used to estimate ATF6 activity and validate ATF6-driven signatures. To investigate the impact of ATF6 signalling on metabolites, untargeted metabolomics of faeces and targeted lipidomics of tissue were performed. Mucosal microbiota was spatially characterised by 16S rRNA profiling at mm resolution along the colonic longitudinal axis. Based on 16S rRNA data, Phylogenetic Investigation of Communities Reconstruction of Unobserved States (PICRUSt2) was used to infer microbiota lipid-specific functional content. Results We identified an ATF6-UPR core of 368 differentially expressed genes fully activated by acute ATF6 signalling. Functional analysis using KEGG pathways showed that chronic ATF6 signalling predominantly alters UPR-related and metabolic pathways, with 22% of metabolic pathway genes classified as lipid metabolism. GF mice confirmed that the microbiota enhances ATF6-induced metabolic changes. Kaplan-Meier analyses significantly associate our microbiota-dependent ATF6-driven and lipid-specific ATF6-driven gene signatures with decreased disease-free survival in CRC patients since primary therapy. Moreover, ATF6 activity correlates with the presence of CRC-associated bacteria in TCGA samples. Tumor-susceptible mice show alterations in lipid metabolites, particularly long-chain fatty acids (FA) and elongation of saturated FA. PICRUSt2 revealed bacterial lipid detoxification mechanisms, with an increased total abundance of oleate hydratase-positive species. Conclusion Chronic ATF6-signalling alters host lipid metabolism and the lipid milieu in tumor-developing nATF6IEC mice. ATF6-driven microbiota changes are concomitant with bacterial lipid detoxification mechanisms in the tumor niche. We postulate that chronic ATF6 signalling represents a clinically relevant pathologic response that alters the intestinal lipid milieu and thus selects for a tumor-promoting microbiota.

Stem/Proliferative and Differentiated Cells within Primary Murine Colonic Epithelium Display Distinct Intracellular Free Ca2+ Signal Codes.

The second messenger, intracellular free calcium (Ca2+ ), acts to transduce mitogenic and differentiation signals incoming to the colonic epithelium. A self-renewing monolayer of primary murine colonic epithelial cells is formed over a soft, transparent hydrogel matrix for the scalable analysis of intracellular Ca2+ transients. Cultures that are enriched for stem/proliferative cells exhibit repetitive, high frequency (≈25 peaks h-1 ), and short pulse width (≈25 s) Ca2+ transients. Upon cell differentiation the transient frequency declines by 50% and pulse width widens by 200%. Metabolites and growth factors that are known to modulate stem cell proliferation and differentiation through Wnt and Notch signaling pathways, including CHIR-99021, N-[(3,5-Difluorophenyl)acetyl]-L-alanyl-2-phenylglycine-1,1-dimethylethyl ester (DAPT), bone morphogenetic proteins (BMPs), and butyrate, also modulate Ca2+ oscillation patterns in a consistent manner. Increasing the stiffness of the supportive matrix from 200 Pa to 3 GPa shifts Ca2+ transient patterns toward those resembling differentiated cells. The ability to monitor Ca2+ oscillations with the spatial and temporal resolution offered by this platform, combined with its amenability to high-content screens, provides a powerful tool for investigating real-time communication within a wide range of primary tissues in addition to the colonic epithelium.

Genomic aberrations after short-term exposure to colibactin-producing E. coli transform primary colon epithelial cells

Genotoxic colibactin-producing pks+ Escherichia coli induce DNA double-strand breaks, mutations, and promote tumor development in mouse models of colorectal cancer (CRC). Colibactin’s distinct mutational signature is reflected in human CRC, suggesting a causal link. Here, we investigate its transformation potential using organoids from primary murine colon epithelial cells. Organoids recovered from short-term infection with pks+ E. coli show characteristics of CRC cells, e.g., enhanced proliferation, Wnt-independence, and impaired differentiation. Sequence analysis of Wnt-independent organoids reveals an enhanced mutational burden, including chromosomal aberrations typical of genomic instability. Although we do not find classic Wnt-signaling mutations, we identify several mutations in genes related to p53-signaling, including miR-34a. Knockout of Trp53 or miR-34 in organoids results in Wnt-independence, corroborating a functional interplay between the p53 and Wnt pathways. We propose larger chromosomal alterations and aneuploidy as the basis of transformation in these organoids, consistent with the early appearance of chromosomal instability in CRC.

A Facile Method to Engineer Mutant Kras Alleles in an Isogenic Cell Background.

Oncogenic KRAS mutations are common in colorectal cancer (CRC), found in ~50% of tumors, and are associated with poor prognosis and resistance to therapy. There is substantial diversity of KRAS mutations observed in CRC. Importantly, emerging clinical and experimental analysis of relatively common KRAS mutations at amino acids G12, G13, A146, and Q61 suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although clinical evidence suggests biological differences between mutant KRAS alleles, these differences and the mechanisms underlying them are not well understood, and further exploration of allele-specific differences may provide evidence for individualized therapeutics. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous KRAS mutants. Here we developed an assay using fluorescent co-selection for CRISPR-driven gene editing to generate various Kras mutations in an isogenic murine colon epithelial cell line background. This assay involves generation of a cell line stably expressing Cas9 linked to BFP and simultaneous introduction of single-guide RNAs (sgRNAs) to two different gene loci resulting in double-editing events. Single-stranded donor oligonucleotides are introduced for a GFP gene and a Kras mutant allele of our choice as templates for homologous recombination (HDR). Cells that successfully undergo HDR are GFP-positive and have a higher probability of containing the desired Kras mutation. Therefore, selection for GFP-positive cells allows us to identify those with phenotypically silent Kras edits. Ultimately, this method allows us to toggle between different mutant alleles and preserve the wild-type allele while maintaining an isogenic background.

TRPV3 endogenously expressed in murine colonic epithelial cells is inhibited by the novel TRPV3 blocker 26E01

TRPV3 is a Ca2+-permeable cation channel, prominently expressed by keratinocytes where it contributes to maintaining the skin barrier, skin regeneration, and keratinocyte differentiation. However, much less is known about its physiological function in other tissues and there is still a need for identifying novel and efficient TRPV3 channel blockers. By screening a compound library, we identified 26E01 as a novel TRPV3 blocker. 26E01 blocks heterologously expressed TRPV3 channels overexpressed in HEK293 cells as assessed by fluorometric intracellular free Ca2+ assays (IC50 = 8.6 μM) but does not affect TRPV1, TRPV2 or TRPV4 channels. Electrophysiological whole-cell recordings confirmed the reversible block of TRPV3 currents by 26E01, which was also effective in excised inside-out patches, hinting to a rather direct mode of action. 26E01 suppresses endogenous TRPV3 currents in the mouse 308 keratinocyte cell line and in the human DLD-1 colon carcinoma cell line (IC50 = 12 μM). In sections of the gastrointestinal epithelium of mice, the expression of TRPV3 mRNA follows a gradient along the gastrointestinal tract, with the highest expression in the distal colon. 26E01 efficiently attenuates 2-aminoethoxydiphenyl borate-induced calcium influx in primary colonic epithelial cells isolated from the distal colon. As 26E01 neither shows toxic effects on DLD-1 cells at concentrations of up to 100 μM in MTT assays nor on mouse primary colonic crypts as assessed by calcein-AM/propidium iodide co-staining, it may serve as a useful tool to further study the physiological function of TRPV3 in various tissues.

Epithelial TLR4 Signaling Activates DUOX2 to Induce Microbiota-Driven Tumorigenesis

Chronic colonic inflammation leads to dysplasia and cancer in patients with inflammatory bowel disease. We have described the critical role of innate immune signaling via Toll-like receptor 4 (TLR4) in the pathogenesis of dysplasia and cancer. In the current study, we interrogate the intersection of TLR4 signaling, epithelial redox activity, and the microbiota in colitis-associated neoplasia. Inflammatory bowel disease and colorectal cancer data sets were analyzed for expression of TLR4, dual oxidase 2 (DUOX2), and NADPH oxidase 1 (NOX1). Epithelial production of hydrogen peroxide (H2O2) was analyzed in murine colonic epithelial cells and colonoid cultures. Colorectal cancer models were carried out in villin-TLR4 mice, carrying a constitutively active form of TLR4, their littermates, and villin-TLR4 mice backcrossed to DUOXA-knockout mice. The role of the TLR4-shaped microbiota in tumor development was tested in wild-type germ-free mice. Activation of epithelial TLR4 was associated with up-regulation of DUOX2 and NOX1 in inflammatory bowel disease and colorectal cancer. DUOX2 was exquisitely dependent on TLR4 signaling and mediated the production of epithelial H2O2. Epithelial H2O2 was significantly increased in villin-TLR4 mice; TLR4-dependent tumorigenesis required the presence of DUOX2 and a microbiota. Mucosa-associated microbiota transferred from villin-TLR4 mice to wild-type germ-free mice caused increased H2O2 production and tumorigenesis. Increased TLR4 signaling in colitis drives expression of DUOX2 and epithelial production of H2O2. The local milieu imprints the mucosal microbiota and imbues it with pathogenic properties demonstrated by enhanced epithelial reactive oxygen species and increased development of colitis-associated tumors. The inter-relationship between epithelial reactive oxygen species and tumor-promoting microbiota requires a 2-pronged strategy to reduce the risk of dysplasia in colitis patients.

Promotion of wound healing by acetate in murine colonic epithelial cell via c-Jun N-terminal kinase activation.

Mucosal healing is an important clinical goal in patients with inflammatory bowel disease. Recently, short-chain fatty acids (SCFAs) have been reported to have multifaceted effects to host. However, the effects of SCFAs on wound healing in intestinal epithelial cells are unclear. In the present study, we investigated the effects of acetate, one of the major SCFAs, on the wound healing of murine colonic epithelial cells. Young adult mouse colonic epithelial cells were used to determine the effect of acetate using wound healing assay. Mitogen-activated protein kinase and Rho kinase inhibitor were used to elucidate intracellular signal of wound healing treated with acetate. Meanwhile, Rho activation assays were utilized to measure Rho activation levels. To assess in vivo effects, C57B6 mice with dextran sodium sulfate for 7days were treated with enema administration of acetate for 7days. Body weight, disease activity index, colon length, and mucosal break ratio in histology were examined. Acetate enhanced wound healing and fluorescence intensity of actin stress fiber compared with control. These effects were canceled with pretreatment of c-Jun N-terminal kinase (JNK) inhibitor or Rho kinase inhibitor. Furthermore, JNK inhibitor reduced the activation of Rho induced by acetate. In the dextran sodium sulfate-induced colitis model, the mice with enema treatment of acetate significantly exhibited recovery. In this study, we demonstrated that acetate promoted murine colonic epithelial cell wound healing via activation of JNK and Rho signaling pathways. These findings suggested that acetate could have applications as a therapeutic agent for patients with intestinal mucosal damage, such as inflammatory bowel disease.

Abstract # 3181 Effect of acute and chronic stress on the expression of GPR43 and GPR41 receptors in murine ileum and colon epithelial cells

GPR41 and GPR43 receptors are located at the level of the ileum and colon in the enteroendocrine cells, being activated by short-chain bacterial fatty acids, products of fermentation, these become a key to activate the mechanisms involved in this intestinal homeostasis. GPR43 and GPR41 mediate inflammatory processes such as colitis, but it has not been demonstrated their participation in vivo models of stress. In a model of acute and chronic restraint stress BALB/c mice we evaluated their expression. The measurement of serum corticosterone was performed to validate our model. Gene expression of Gpr41/Gpr43 through qPCR and protein expression of GPR41/GPR43 by Western Blot in both Large Intestine (IG) and Small Intestine (ID). Our results show that stress increases corticosterone levels being higher in chronic stress. Gene expression may show an increase for both receptors in chronic stress. Protein expression, unlike gene, has a greater increase in acute stress, except for GPR41 in ID where its increase is not significant. This suggests that an acute stimulation increases the expression of this receptor to conserve intestinal homeostasis, which initially deplete the gene machinery and then increase it by the constant appearance of the stressor stimulus although there seem to be post-translational mechanisms that do not allow. This shows us that the gradual increase of corticosterone apparently affects the expression of the protein of both receptors.

HDAC inhibitors promote intestinal epithelial regeneration via autocrine TGFβ1 signalling in inflammation.

Intact epithelial barrier function is pivotal for maintaining intestinal homeostasis. Current therapeutic developments aim at restoring the epithelial barrier in inflammatory boweldisease. Histone deacetylase (HDAC) inhibitors are known to modulate immune responses and to ameliorate experimental colitis. However, their direct impact on epithelial barrier function and intestinal wound healing is unknown. In human and murine colonic epithelial cell lines, the presence of the HDAC inhibitors Givinostat and Vorinostat not only improved transepithelial electrical resistance under inflammatory conditions but also attenuated the passage of macromolecules across the epithelial monolayer. Givinostat treatment mediated an accelerated wound closure in scratch assays. In vivo, Givinostat treatment resulted in improved barrier recovery and epithelial wound healing in dextran sodium sulphate-stressed mice. Mechanistically, these regenerative effects could be linked to an increased secretion of transforming growth factor beta1 and interleukin 8, paralleled by differential expression of the tight junction proteins claudin-1, claudin-2 and occludin. Our data reveal a novel tissue regenerative property of the pan-HDAC inhibitors Givinostat and Vorinostat in intestinal inflammation, which may have beneficial implications by repurposing HDAC inhibitors for therapeutic strategies for inflammatory bowel disease.

Lipopolysaccharide and lipoteichoic acid enhance serum amyloid A3 mRNA expression in murine alveolar epithelial cells.

Serum amyloid A (SAA) is an acute-phase protein indicative of inflammation. In murine colonic epithelial cells, lipopolysaccharide (LPS), a gram-negative bacterial antigen, strongly enhanced mRNA expression of SAA3, but not SAA1 or SAA2, suggesting that SAA3 might respond to bacterial infection in other epithelia. We examined SAA1/2 and SAA3 mRNA expression in murine alveolar epithelial cells exposed to LPS or the gram-positive bacterial antigen, lipoteichoic acid (LTA), using real-time PCR. LPS enhanced SAA3 mRNA expression at lower concentrations than did LTA, whereas SAA1/2 mRNA expression was not enhanced by either LPS or LTA. These results suggest that SAA3 expression is enhanced in lung epithelium upon bacterial infection as part of innate immunity, with higher sensitivity to LPS than to LTA.

Biflavonoids Isolated from Selaginella tamariscina and Their Anti-Inflammatory Activities via ERK 1/2 Signaling.

Selaginella tamariscina (S. tamariscina) (Beauv.) Spring (Selaginellaceae) has been used in oriental medicine for the treatment of dysmenorrhea, chronic hepatitis, hyperglycemia, amenorrhea, hematuria, prolapse of the anus and metrorrhagia. In the present study, we isolated two strong anti-inflammatory compounds, the biflavonoids hinokiflavone (H) and 7′-O-methyl hinokiflavone (mH), from S. tamariscina and examined their anti-inflammatory activities in lipopolysaccharide (LPS)-mediated murine macrophages (RAW 264.7) and colon epithelial cells (HT-29). H and mH suppressed the production of the inflammatory mediators nitric oxide (NO), interleukin (IL)-6, IL-8, and tumor-necrosis factor (TNF)-α, which are most highly activated in inflammatory bowel disease (IBD). In addition, Western blot analysis revealed that H and mH suppressed the LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, and the activation of nuclear factor-κB (NF-κB) and extracellular regulated kinases (ERK) 1/2. These results suggest that H and mH are compounds having potent anti-inflammatory effects that could be used to treat such diseases as IBD.

Large-Scale Integrative Analysis of Epigenetic Modifications Induced by Isotretinoin, Doxycycline and Metronidazole in Murine Colonic Intestinal Epithelial Cells

Environmental factors are playing a central role in triggering inflammatory responses in the intestine. There is increasing evidence that the development of inflammatory bowel disease (IBD) is deriving from an aberrant immune response to the commensal gut microbiota triggered by various environmental factors in a susceptible host. A vitamin A derivate used in acne therapy (isotretinoin) has been inconsistently associated with the onset of IBD. However, what needs to be considered is the previous treatment of acne patients with antibiotics that are also associated with the development of IBD, thus representing a crucial confounding factor. Here, we studied whether doxycycline (acne therapy), metronidazole (IBD therapy) or isotretinoin are able to induce alterations in DNA methylation and microRNA expression patterns in murine colonic intestinal epithelial cells (IECs). Additionally, we analyzed time-dependent changes in the aforementioned epigenetic mechanisms to study how epigenetic signatures evolve over time. As for changes in DNA methylation, we found isotretinoin to have strong demethylating effects, while antibiotic treatment had only a moderate impact. Isotretinoin-mediated demethylation resolved after a washout phase, not supporting an association between isotretinoin treatment and IBD. Regarding microRNA and mRNA expression, isotretinoin and doxycycline, but not metronidazole, potentially induce long-term changes in microRNA/mRNA expression profiles towards the down-regulation of immune responses. Analysis of time-dependent DNA methylation showed stable marks over a time frame of 4 weeks. Furthermore, novel microRNAs were identified (e.g., microRNA-877-3p), which might be of relevance in IEC development.

Commensal-infected macrophages induce dedifferentiation and reprogramming of epithelial cells during colorectal carcinogenesis.

The colonic microbiome contributes to the initiation of colorectal cancer through poorly characterized mechanisms. We have shown that commensal-polarized macrophages induce gene mutation, chromosomal instability, and endogenous transformation through microbiome-induced bystander effects (MIBE). In this study we show that MIBE activates Wnt/β-catenin signaling and pluripotent transcription factors associated with dedifferentiation, reprogramming, and the development of colorectal cancer stem cells (CSCs). Exposure of murine primary colon epithelial cells (YAMC) to Enterococcus faecalis-infected macrophages increased Wnt3α expression while suppressing Wnt inhibitor factor 1 (Wif1). Wnt/β-catenin activation was confirmed by increased active β-catenin and Tcf4. in vivo, active β-catenin was evident in colon biopsies from E. faecalis-colonized Il10 knockout mice compared to sham-colonized mice. This effect was mediated, in part, by 4-hydroxy-2-nonenal and tumor necrosis factor α. MIBE also activated pluripotent transcription factors c-Myc, Klf4, Oct4, and Sox2 in YAMC cells and colons from E. faecalis-colonized Il10 knockout mice. These transcription factors are associated with cellular reprogramming, dedifferentiation, and induction of colorectal CSC progenitors. In support of this was an increase in the expression of Dclk1 and CD44, two colorectal CSC markers, in YAMC cells that were exposed to MIBE. Finally, compared to normal colon biopsies and hyperplastic polyps, DCLK1 expression increased in human tubular adenomas and invasive colorectal cancers. Blocking β-catenin/TCF4 signaling using FH535 and CTNNB1-specific small interfering RNA decreased DCLK1 expression in HCT116 human colon cancer cells. These findings provide mechanism for microbiome-induced colorectal cancer and identify new potential targets for colorectal cancer prevention.

Comparison of byakujutsu (Atractylodes rhizome) and sojutsu (Atractylodes lancea rhizome) on anti-inflammatory and immunostimulative effects in vitro.

The Japanese Pharmacopoeia defines byakujutsu (Atractylodes rhizome) as the rhizome of Atractylodes japonica or A. macrocephala and sojutsu (Atractylodes lancea rhizome) as the rhizome of A. lancea, A. chinensis, or their interspecific hybrids. Because their pharmaceutical uses differ in traditional Japanese Kampo medicine and traditional Chinese medicine, with less apparent scientific evidence, we compared the pharmacological properties between byakujutsu and sojutsu. Crude drug specimens of byakujutsu (n=40) and sojutsu (n=49) obtained in markets were identified by their species using DNA profiling. Their pharmacological properties were evaluated by the inhibitory effect of a MeOH extract of the samples on nitric oxide (NO) production by lipopolysaccharide-stimulated murine macrophage-like RAW264.7 cells and by the inducing effect of boiling water extract of the samples on granulocyte-colony stimulating factor (G-CSF) secretion from murine normal colonic epithelial MCE301 cells. We authenticated A. macrocephala (n=8), A. japonica (n=35), and the hybrid between A. macrocephala and A. japonica (n=1), and they were used as byakujutsu. We authenticated A. chinensis (n=25), A. lancea (n=14), and the hybrid between A. chinensis and A. lancea (n=6), and they were used as sojutsu. The inhibitory effects of byakujutsu on NO production were significantly higher than those of sojutsu (P<0.05). This activity of A. japonica rhizome was significantly higher than that of A. macrocephala rhizome and A. lancea rhizome (P<0.01). The activity of A. chinensis rhizome was significantly higher than that of A. lancea rhizome (P<0.05). The extract of A. japonica rhizome significantly induced G-CSF secretion from MCE301 cells in a concentration-dependent manner. These effects of byakujutsu samples were not significantly different from those of sojutsu samples. A. japonica rhizome had significantly higher activity than A. macrocephala rhizome; however, there were no statistically significant differences among A. japonica, A. chinensis, and A. lancea. The pharmacological differences of byakujutsu and sojutsu may not be large among highly variated crude drug samples with average values, and quality control with the identification of the original plant species of byakujutsu and sojutsu may guarantee their pharmacological properties.