Enterochromaffin Research Articles

Characterizing Graft-Vs-Host Disease of the Bone Marrow Post Allogeneic Hematopoietic Cell Transplantation in Mice

Graft-vs-Host Disease (GVHD) is a common complication post allogeneic hematopoietic cell transplantation (allo-HCT). In contrast to classical target organs alloreactivity directed against hematopoietic and non-hematopoietic bone marrow (BM) structures has been poorly characterized, even though hematopoietic dysfunction following allo-HCT is frequently observed.Here, we studied in MHC-matched, minor antigen mismatched HCT models (C3H-SW > C57BL/6 (B6)) the effects of lethal total body irradiation and HCT of HSC (cKIT+Sca1+Lin-) alone or in combination with Tc / Tc subsets (CD4+, CD8+ or total (CD4+CD8) T cells (Tc)) on the hematopoietic compartment (HC) and non-hematopoietic compartment (NHC) of the BM. Up to 8 weeks (w) post-HCT bones and marrow were analyzed by flow cytometry and 3D-confocal microscopy imaging.Post allo-HCT there was a transient weight loss and decrease of total BM cell counts in all experimental groups, but no signs of overt GVHD. At 2w mice given HSC had significantly higher absolute BM counts compared with HSC+Tc/Tc subset recipients. Most pronouncedly affected were B-cells that recovered promptly in HSC recipients but were severely delayed beyond w8 in the HSC+Tc groups (particularly in CD4 recipients). Likewise, BM granulocyte recovery during the first 4w was significantly better in HSC vs. HSC+Tc recipients. Moreover, alloreactive (but not congenic) Tc severely disrupted the NHC: at 2w post allo-HCT HSC recipients showed prompt recovery of BM endothelial cells (EC; CD45-Ter119-CD31+), and CXCL12-abundant reticular cells (CAR; CD45-Ter119-CD31-CD140B+). In contrast, HSC+Tc recipients had significantly lower EC and CAR cells counts and their recovery was significantly delayed. 3D-confocal microscopy confirmed these observations and revealed rapid recovery of extracellular matrix and sinusoidal vascular structures, with simultaneous disappearance of adipocytes at 2w post-HCT in the HSC group, whereas HSC+Tc recipients displayed severe disruption of the structural integrity with impaired recovery of the BM microvessels but rather occupation of space by adipocytes. To visualize CAR cells by 3D imaging we used B6.CXCL12-GFP recipients and found, again, impaired CAR cell regeneration in HSC+Tc, but not pure HSC recipients. We next addressed the question whether alloreactive Tc exert direct GVH-related damage to NHC structures, or alternatively, only the recipient's HC is attacked whereas suppression of EC and CAR cells results from the inflammatory milieu. By transplanting C3H.SW BM into lethally irradiated B6 recipients chimeras with a C3H.SW HC and B6 NHC were generated. In a 2nd HCT HSC +/- Tc were transplanted from (i) C3H.SW (allo to NHC; syngeneic to HC) or (ii) B6 (congenic to NHC, allo to HC) donors into these chimeras. (i) At 2w post-2nd HCT BM cellularity, EC and CAR cell numbers were decreased when donor Tc were allogeneic to the NHC, but syngeneic to the HC. NHC populations were normal in number when pure allogeneic HSC (without Tc) were given. (ii) When grafts for 2nd HCT were from B6 donors (allo to HC, congenic to NHC), donor Tc had no effect on EC numbers. CAR cells were reduced in numbers, but less severely compared with after transfer of allogeneic HSC+Tc. Together, these findings suggest, that EC can be directly targeted by alloreactive Tc; CAR cells are affected by both, alloreactive Tc, and inflammatory conditions generated by attack of the HC. Finally, to test the influence of GVH-related cytokines on the NHC we used B6.TNFaR-/- and B6.IFNyR-/- mice as recipients of C3H.SW HSC +/- Tc. Recovery of HC and NHC was identical in WT and TNFaR-/- recipients of C3H.SW grafts. In contrast, IFNyR-/- recipients of allogeneic HSC+CD4 grafts had significantly higher CAR cell counts compared with WT.B6 recipients (but lower than recipients of pure HSC). These findings support the hypothesis that CAR cells are also susceptible to inflammatory damage.In clinical HCT delayed hematopoietic reconstitution presents a major problem contributing to increased morbidity and mortality. GVH reactions of the BM have been poorly characterized. Our data show that not only host hematopoiesis, but also non-hematopoietic stromal and vascular compartments of the BM are affected by both alloreactivity of donor Tc and their inflammatory microenvironment, even in the absence of clinical GVHD. DisclosuresNo relevant conflicts of interest to declare.

Female serotonin transporter-knockout rat: A potential model of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disease. Although visceral hypersensitivity (VH) and disturbed gastrointestinal motility are typical pathophysiological features of IBS, the pathological mechanisms underlying this disease remain unclear. Serotonin system abnormalities are considered to play an important role in the pathomechanisms of IBS. Here, we hypothesize that similar alterations, including VH and colonic motility, induced by serotonin transporter (SERT) knockout result from altered serotonin signaling. We sought to determine the molecular mechanism underlying VH and colonic dysmotility induced by SERT knockout. We found that female SERT (slc6a4)-knockout (KO; ie, slc6a4-/- ) rats exhibited lower pain pressure thresholds (PPTs) than wild-type (WT; ie, slc6a4+/+ ) rats in response to colorectal distension (CRD). Significantly increased fecal pellet output and reduced concentration of serum tryptophan were observed in the female SERT KO rats. The concentrations of 5-hydroxytryptamine (5-HT) in platelet-rich plasma (PRP) and serum in SERT KO rats were lower than those in WT rats, but the numbers of enterochromaffin cells (ECs) and the concentrations of 5-HT in colon of SERT KO rats were higher than those of WT rats. Finally, increased expression levels of 5-HT1B receptors, 5-HT2C receptors, 5-HT3A receptors, 5-HT3B receptors, 5-HT6 receptors, 5-HT7 receptors, and glycosylated dopamine transporters (DATs) were found in the female SERT KO rats. We concluded that alterations in the serotonin system induced by the knockout of slc6a4 might result in VH and accelerated gastrointestinal motility in female SERT KO rats, which can be used as an animal model of IBS.

MiR-133a-3p inhibits the malignant progression of oesophageal cancer by targeting CDCA8.

The study aims to explore the interaction between miR-133a-3p and cell division cycle associated 8 (CDCA8) in oesophageal cancer (EC) and their effect on malignant behaviour of EC cells. Differential miRNAs and mRNAs were obtained from The Cancer Genome Atlas (TCGA) database. Quantitative real-time PCR (qRT-PCR) was used to detect the expression levels of miR-133a-3p and CDCA8 mRNA in EC cells. Western blot was used to detect the expression of CDCA8 protein. CCK-8, flow cytometry and Transwell assays were conducted to detect cell proliferation, cell cycle and apoptosis, as well as migration and invasion, respectively. The targeting relationship between miR-133a-3p and CDCA8 was verified by dual-luciferase reporter gene assay. In EC, miR-133a-3p expression was evidently low and CDCA8 expression was prominently high. MiR-133a-3p downregulated CDCA8 expression. A range of cell function experiments revealed that CDCA8 promoted the proliferation, migration and invasion of EC cells, reduced cell cycle arrest in G0/G1 phase and inhibited cell apoptosis, while miR-133a-3p could reverse the above effects by regulating CDCA8. MiR-133a-3p is a crucial tumour suppressor miRNA in EC, playing a tumour suppressor role by targeting CDCA8.

Amino Acid Trp: The Far Out Impacts of Host and Commensal Tryptophan Metabolism.

Tryptophan (Trp) is an essential amino acid primarily derived from the diet for use by the host for protein synthesis. The intestinal tract is lined with cells, both host and microbial, that uptake and metabolize Trp to also generate important signaling molecules. Serotonin (5-HT), kynurenine and its downstream metabolites, and to a lesser extent other neurotransmitters are generated by the host to signal onto host receptors and elicit physiological effects. 5-HT production by neurons in the CNS regulates sleep, mood, and appetite; 5-HT production in the intestinal tract by enterochromaffin cells regulates gastric motility and inflammation in the periphery. Kynurenine can signal onto the aryl hydrocarbon receptor (AHR) to elicit pleiotropic responses from several cell types including epithelial and immune cells, or can be further metabolized into bioactive molecules to influence neurodegenerative disease. There is a remarkable amount of cross-talk with the microbiome with regard to tryptophan metabolites as well. The gut microbiome can regulate the production of host tryptophan metabolites and can use dietary or recycled trp to generate bioactive metabolites themselves. Trp derivatives like indole are able to signal onto xenobiotic receptors, including AHR, to elicit tolerogenic effects. Here, we review studies that demonstrate that tryptophan represents a key intra-kingdom signaling molecule.

MLN4924 inhibits cell proliferation by targeting the activated neddylation pathway in endometrial carcinoma.

ObjectiveTo explore the neddylation pathway, found to be highly activated in various cancers, as a potential therapeutic target in endometrial carcinoma, one of the three most frequent malignant tumours in the female reproductive system.MethodsData from The Cancer Genome Atlas were analysed using online servers. Expression levels of key neddylation genes were validated by reverse-transcription polymerase chain reaction and western blots of tumour and adjacent tissues. Underlying mechanisms and the effects on cell activities of the neddylation pathway-specific inhibitor, MLN4924, were investigated in endometrial cancer cell lines.ResultsKey neddylation enzymes, ubiquitin conjugating enzyme E2 M (UBC12), ubiquitin conjugating enzyme E2 F (UBE2F), ring-box 1 (RBX1) and ring finger protein 7 (RBX2), were significantly overexpressed in endometrial carcinoma tissues versus normal tissues, but only UBE2F and RBX2 positively correlated with patient survival. MLN4924 significantly suppressed proliferation and colony formation in EC cells by inducing DNA re-replication, cell cycle arrest and apoptosis. Mechanism study revealed that MLN4924 induced the accumulation of cullin-RING ligase substrates in vitro.ConclusionsThe neddylation pathway was identified to play an important role in endometrial cancer. The neddylation specific inhibitor, MLN4924, may be a potential therapeutic drug for endometrial carcinoma.

Identification and molecular study on the interaction of Schisandrin C with human 5-HT3A receptor

Schisandrin C (Sch C) is one of the main components of Schisandra chinensis (Schisandra). Since the olden times, Schisandra has been used as a traditional herbal medicine in Asia. Recent studies have shown that Schisandra is effective against irritable bowel syndrome (IBS) in an animal model and affects IBS through the 5-HT3A pathway in the IBS rat model. However, there lacks fundamental research on the interaction of specific components of Schisandra with the 5-HT3A receptor for the treatment of IBS. We hypothesized that a component of Schisandra binds to the 5-HT3A receptor and identified Sch C via a screening work using two electrode-voltage clamps (TEVC). Thus, we aimed to elucidate the neuropharmacological actions between Sch C and the 5-HT3A receptor at molecular and cellular levels. Co-treatment of Sch C with 5-HT inhibited I5-HT in a reversible, concentrate-dependent, like-competition, and voltage-independent manner, and IC50 values of Sch C. Besides, the main binding positions of Sch C were identified through 3D modeling and point mutation were V225A and V288Y on 5-HT3A receptor. Thus, we suggest the potential of Sch C in treating IBS in a manner that suppresses excessive neuronal serotonin signaling in the synapse of sensory neurons and enterochromaffin (EC) cells. In conclusion, the results demonstrate the mechanism of interaction between Sch C and 5-HT3A receptor and reveal Sch C as a novel antagonist.

Incidence and patterns of secondary malignancies in patients with neuroendocrine neoplasms: A SEER database analysis.

e16208 Background: Neuroendocrine neoplasms (NENs) are a group of biologically and clinically heterogenous malignancies of different anatomic sites, the majority of which lie within the gastrointestinal (GI) tract. Prior literature has reported on the association between NENs and other primary malignancies (OPM), but these studies are limited by small sample sizes. We aim to further analyze the association of NENs and OPM on a larger scale using a population-based cancer registry. Methods: Primary malignancies with NEN features were identified from the Surveillance Epidemiology and Ends Results registry between 1975-2017. The histology/behavior of NEN included carcinoid tumor, neuroendocrine carcinoma (NEC), pancreatic endocrine tumor, atypical carcinoid tumor, and other (insulinoma, glucagonoma, gastrinoma, VIPoma, somatostatinoma and enterochromaffin cell carcinoid). First NEN observation from each patient was examined. Patients with NEN were grouped into 3 categories: NEN only, NEN first followed by OPM, and non-NEN first followed by NEN based on sequence number of primary cancer. Secondary malignancy sites were analyzed. Distribution of NEN between GI and non-GI sites was described. Demographics were compared by NEN sequence groups and between GI and non-GI sites. Results: 45,896 patients with NEN were analyzed (77.9% Caucasian, 47.0% male, median age 62.0 yrs). 65.7% of NENs were observed in GI sites. Within the GI tract, 31.3% were small intestine, 25.1% rectum, 16.6% pancreatobiliary, and < 11% in other GI locations. Age at NEN diagnosis was younger in those with GI NENs (median 60.0 vs 65.0, p < 0.001). 71.2% of patients had NEN only, 10.4% had NEN first followed by OPM, and 18.4% had a non-NEN primary followed by NEN. Mean age was 58.9 for NEN primary only, 61.0 for NEN primary first and 68.3 for non-NEN primary first (p < 0.0001). More Caucasian patients had non-NEN primary first (82.3%) compared to NEN primary only (76.9%) and NEN primary first (75.5%). There were no gender differences amongst the three groups. Carcinoid tumor histology was more prevalent in NEN primary first (78.6%) compared to NEN primary only (67.3%) and non-NEN primary first (66.6%), while NEC histology was more prevalent in NEN only (27.4%) and non-NEN first (29.3%) compared to NEN first. Among patients with NEN first followed by a second primary malignancy (SPM), 23.6% of females had a secondary breast malignancy and 28.9% of males had a secondary prostate malignancy. Conclusions: 28.8% of patients with NENs were found to have OPM, either preceding or following their NEN diagnosis. Of those with a SPM following NEN, breast and prostate were the most common sites for women and men, respectively. It is imperative that patients with NEN undergo age-appropriate cancer screening to help identify any concurrent malignancies. Further research is warranted to identify the timeframe in which they occur in relation to the NEN.

Elevated expression of LPCAT1 predicts a poor prognosis and is correlated with the tumour microenvironment in endometrial cancer

BackgroundEndometrial cancer (EC) is one of the three malignant reproductive tumours that threaten women’s lives and health. Glycerophospholipids (GPLs) are important bioactive lipids involved in various physiological and pathological processes, including cancer. Immune infiltration of the tumour microenvironment (TME) is positively associated with the overall survival in EC. Exploring GPL-related factors associated with the TME in endometrial cancer can aid in the prognosis of patients and provide new therapeutic targets.MethodsDifferentially expressed GPL-related genes were identified from TCGA-UCEC datasets and the Molecular Signatures Database (MSigDB). Univariate Cox regression analysis was used to select GPL-related genes with prognostic value. The Random forest algorithm, LASSO algorithm and PPI network were used to identify critical genes. ESTIMATEScore was calculated to identify genes associated with the TME. Then, differentiation analysis and survival analysis of LPCAT1 were performed based on TCGA datasets. GSE17025 and immunohistochemistry (IHC) verified the results of the differentiation analysis. An MTT assay was then conducted to determine the proliferation of EC cells. GO and KEGG enrichment analyses were performed to explore the underlying mechanism of LPCAT1. In addition, we used the ssGSEA algorithm to explore the correlation between LPCAT1 and cancer immune infiltrates.ResultsTwenty-three differentially expressed GPL-related genes were identified, and eleven prognostic genes were selected by univariate Cox regression analysis. Four significant genes were identified by two different algorithms and the PPI network. Only LPCAT1 was significantly correlated with the tumour microenvironment. Then, we found that LPCAT1 was highly expressed in tumour samples compared with that in normal tissues, and lower survival rates were observed in the groups with high LPCAT1 expression. Silencing of LPCAT1 inhibited the proliferation of EC cells. Moreover, the expression of LPCAT1 was positively correlated with the histologic grades and types. The ROC curve indicated that LPCAT1 had good prognostic accuracy. Receptor ligand activity, pattern specification process, regionalization, anterior/posterior pattern specification and salivary secretion pathways were enriched as potential targets of LPCAT1. By using the ssGSEA algorithm, fifteen kinds of tumor-infiltrating cells (TICs) were found to be correlated with LPCAT1 expression.ConclusionThese findings suggested that LPCAT1 may act as a valuable prognostic biomarker and be correlated with immune infiltrates in endometrial cancer, which may provide novel therapy options for and improved treatment of EC.

Performance of photovoltaic-driven electrochemical cell systems for CO2 reduction

Photovoltaic-driven electrochemical cell (PV-EC) systems have drawn tremendous attention as one method of artificial photosynthesis that can obtain energy fuels from solar power and mitigate current environmental issues. PV-EC systems are composed of catalysts toward CO2 reduction reaction (CO2RR) and oxygen evolution reaction (OER), solar cells, and catholyte/anolyte. CO, C2H4, formate, and acetate have been considered as direct target products from solar-driven CO2RR using PV-EC devices. PV-EC systems are reviewed by covering their operating principle and various research activities related to CO2RR/OER catalysts and solar cells with a main focus on their current/current density - voltage (I/J-V) characteristics. By analyzing the PV-EC component materials, the I/J-V characteristics of PV-EC systems, and the corresponding solar-to-fuel efficiency altogether, a comparison between various PV-EC systems would be much easier from an industrial viewpoint. CO is the most popular CO2RR product, and the solar-to-CO efficiency has increased from ∼6% to ∼19% in recent years. The solar-to-C2H4 efficiency manages to reach 1.5% with a combined solar-to-C2 product efficiency of ∼3%. The solar-to-formate/acetate efficiencies are ∼7% and ∼4%, respectively. The effectiveness of using a bipolar membrane, which enables the operation of EC cells adopting electrolytes of different acidity in reducing the EC cell voltage, has not been verified conclusively. A couple of PV-EC systems that are likely to produce CO and C2H4 efficiently and economically are suggested based on their I/J-V characteristics.

Immune-neural transmission regulates gut sensation

Abstract The gastrointestinal tract is known as the largest endocrine organ that encounters and integrates various immune stimulations and neuronal responses due to constant environmental challenges. Enterochromaffin (EC) cells, which function as chemosensors on the gut epithelium, are known to translate environmental cues into serotonin (5-HT) production, contributing to intestinal physiology. However, how immune signals participate in gut sensation and neuroendocrine response remains unclear. Interleukin-33 (IL-33) acts as an alarmin cytokine by alerting the system of potential environmental stresses. We here demonstrate that IL-33 induced instantaneous peristaltic movement and facilitated Trichuris muris expulsion. We found that IL-33 could be sensed by EC cells, inducing release of 5-HT. IL-33-mediated 5-HT release activated enteric neurons, subsequently promoting gut motility. Mechanistically, IL-33 triggered calcium influx via a non-canonical signaling pathway specifically in EC cells to induce 5-HT secretion. Our data establish an immune-neuroendocrine axis in calibrating rapid 5-HT release for intestinal homeostasis.

Serotonin Induces Inflammatory Cytokine Production and Regulates Lymphatic Endothelial Cell Function

Serotonin or 5-hydroxytryptamine (5-HT) is a neuromodulator, with both neuroendocrine and neurotransmitter functions, which is synthesized in serotonergic neurons in the central nervous system and enterochromaffin cells throughout the gastrointestinal tract. The lymphatics play a central role in inflammatory and immune response and lymphatic endothelial cells (LECs) are active participants in these processes. Several immune cells store or respond to 5-HT thereby implicating it in inflammatory pathways and it is also known as a growth factor for several types of non-tumoral cells. Lymphatic muscle has been shown to be significantly responsive to 5-HT however the effects of 5-HT on modulation of lymphatic endothelial phenotype or inflammatory function is not well understood. In this study, we hypothesized that increased levels of 5-HT modulate LEC morphological and phenotypic behavior and also induces cytokine and chemokine production that contribute to inflammation. LECs were initially evaluated for the expression of specific receptors by real time PCR. HDLECs were treated with 5-HT and its receptor antagonist and the effects of 5-HT on LEC proliferation, migration and tube formation was evaluated. Real time PCR was carried out to evaluate the alterations in specific cytokines, chemokines and growth factors produced by LECs in response to 5-HT treatment. In addition, conditioned medium was collected from LECs treated with 5-HT and/or its receptor inhibitor and subjected to cytokine and chemokine array analysis. Our real time PCR analysis show that LECs show varying basal level expression of the 5-HT receptors (5-HTR1-7) with 5-HTR7 showing the highest level of expression. Serotonin treatment of the LECs significantly induces LEC proliferation and migration shown by XTT and Boyden chamber assays. Further, LECs treated with 5-HT for 24hrs show significant induction of several growth factors, inflammatory and lymphangiogenic molecules including angiogenin, endoglin and IL23 indicating the activation of key inflammatory or lymphangiogenic pathways. In keeping with these findings, our results also show that 5-HT treatment enhances lymphatic tube formation that is abrogated by 5-HTR inhibition. Further, 5-HT also activates the PI3K/AKT and ERK MAPK key lymphangiogenic and growth promoting pathways in the LECs. Taken together, we show that 5-HT alters phenotypic and morphological behavior of LECs and activate several growth factors and signaling molecules that are pro-lymphangiogenic and thus can be a viable therapeutic strategy for modulation of lymphangiogenesis and LEC function during inflammation.

Succinate‐Induced Tuft Cell Hyperplasia Enhances FFA2/5‐HT Mediated Anion Secretion in Mouse Duodenum

Tuft cells are one of luminal chemosensing components in the small intestine, while the role of tuft cell in mucosal secretory responses to luminal chemicals such as short-chain fatty acids (SCFA) has not been elucidated. We thus hypothesized that tuft cell hyperplasia may increase the secretory responses to luminal SCFA due to the increased cholinergic signals since tuft cells express choline acetyltransferase (ChAT). Tuft cell hyperplasia was induced by oral sodium succinate (NaSuc, 100 mM) in the drinking water for 7 days. Sodium propionate (NaP, 10 mM, m), the selective free fatty acid receptor 2 (FFA2) agonist 4-CMTB (10 µM, s), or the TRPA1 agonist allyl isothiocyanate (AITC, 1 mM, m) were applied to the mucosal (m) or serosal (s) baths of an Ussing chamber mounted with muscle-stripped mucosa-submucosa preparations of mouse proximal duodenum or jejunum. The density of tuft cells (doublecortin-like kinase 1; DCLK1), enteroendocrine L cells (proglucagon, glucagon-like peptide-2), and enterochromaffin (EC) cells (5-HT, tryptophan hydroxylase 1; TPH1) were assessed by real-time PCR and immunostaining. NaSuc treatment significantly increased the number of DCLK1-positive tuft cells in the duodenal and jejunal villi. mRNA expression of DCLK1 and FFA2 were increased in the duodenal and jejunal mucosa, whereas TPH1 was increased only in the duodenal mucosa, and ChAT was increased in the jejunal mucosa, but proglucagon was unchanged in both. 5-HT-positive mast cell density rather than EC cell density was increased in the duodenum. Isc in response to luminal NaP was enhanced in the jejunum, which was atropine sensitive. In contrast, Isc responses to serosal 4-CMTB and luminal AITC were enhanced in the duodenum, which were mediated by 5-HT3 and 5-HT4 receptors. These results suggest that NaSuc differentially enhances secretory responses, with 5-HT signals in the duodenum and with cholinergic signals in the jejunum. These data may be implicated in the pathogenesis of functional dyspepsia (FD), since increased duodenal mast cell density and enhanced 5-HT signals are present in FD patients.

Expression of VAChT and 5-HT in Ulcerative colitis dendritic cells

Ulcerative colitis is a chronic inflammatory condition of the gastrointestinal tract that can affect people of worldwide. In contrast with Crohn’s disease, that can relate the entire thickness of the bowel wall, the inflammation of ulcerative colitis is limited to the colonic mucosa. Immune cells including activated T cells, plasma cells, mast cells, macrophages, and dendritic cells (DCs) trigger the inflammation. Furthermore, dendritic cells are antigen presenting cells involved in maintaining intestinal immune homeostasis. It has been described an increment of number in DCs colonic mucosa of patients with ulcerative colitis. The immune cells such as antigen-presenting cells can act as autocrine or paracrine modulators. Recent studies showed that dendritic cells synthetized and released classical neurotransmitters as glutamate, dopamine, acetylcholine, and serotonin. Paraformaldehyde-fixed intestinal tissues, obtained from the stricture sites of ten patients with ulcerative colitis were analyzed by immunostaining for Langerin/CD207, serotonin and vesicular acetylcholine transporter. As controls, unaffected (normal) portions of five patients were also investigated. Aim of this study was to characterize for the first time the human gut dendritic cells of ulcerative colitis patients, with Langerin/CD207 that is a c-type lectin expressed by different types of DCs and to colocalize in the same cells the expression of serotonin and vesicular acetylcholine transporter, showing the link between dendritic cells, gut enterochromaffin cells or autonomic nerves in immune activation and generation of intestinal inflammation.

Water intake releases serotonin from enterochromaffin cells in rat jejunal villi.

The present study aims to investigate the roles of water intake in serotonin production and release in rat jejunum. We evaluated the changes in concentrations of serotonin in the portal vein and mesenteric lymph vessel induced by the intragastric administration of distilled water. The density of granules in enterochromaffin cells and the immunoreactivity of serotonin in the jejunal villi were investigated before and after water intake. The effects of intravenous administration of serotonin and/or ketanserin on mesenteric lymph flow and concentrations of albumin and IL-22 in the lymph were also addressed. Water intake increased serotonin concentration in the portal vein, but not in the mesenteric lymph vessel. The flux of serotonin through the portal vein was significantly larger than that through the mesenteric lymph vessel. Water intake decreased the density of granules in the enterochromaffin cells and increased the immunoreactivity of serotonin in the jejunal villi. The intravenous administration of serotonin increased significantly mesenteric lymph flow and the concentrations of albumin and IL-22; both were significantly reduced by the intravenous pretreatment with ketanserin. We showed that serotonin released from enterochromaffin cells by water intake was mainly transported through the portal vein. Additionally, serotonin in blood was found to increase mesenteric lymph formation with permeant albumin in the jejunal villi via the activation of 5-HT2 receptor.

Colonic Motility Is Improved by the Activation of 5-HT2B Receptors on Interstitial Cells of Cajal in Diabetic Mice

Constipation is commonly associated with diabetes. Serotonin (5-HT), produced predominantly by enterochromaffin (EC) cells via tryptophan hydroxylase 1 (TPH1), is a key modulator of gastrointestinal (GI) motility. However, the role of serotonergic signaling in constipation associated with diabetes is unknown. We generated EC cell reporter Tph1-tdTom, EC cell-depleted Tph1-DTA, combined Tph1-tdTom-DTA, and interstitial cell of Cajal (ICC)-specific Kit-GCaMP6 mice. Male mice and surgically ovariectomized female mice were fed a high-fat high-sucrose diet to induce diabetes. The effect of serotonergic signaling on GI motility was studied by examining 5-HT receptor expression in the colon and invivo GI transit, colonic migrating motor complexes (CMMCs), and calcium imaging in mice treated with either a 5-HT2B receptor (HTR2B) antagonist or agonist. Colonic transit was delayed in males with diabetes, although colonic Tph1+ cell density and 5-HT levels were increased. Colonic transit was not further reduced in diabetic mice by EC cell depletion. The HTR2B protein, predominantly expressed by colonic ICCs, was markedly decreased in the colonic muscles of males and ovariectomized females with diabetes. Ca2+ activity in colonic ICCs was decreased in diabetic males. Treatment with an HTR2B antagonist impaired CMMCs and colonic motility in healthy males, whereas treatment with an HTR2B agonist improved CMMCs and colonic motility in males with diabetes. Colonic transit in ovariectomized females with diabetes was also improved significantly by the HTR2B agonist treatment. Impaired colonic motility in mice with diabetes was improved by enhancing HTR2B signaling. The HTR2B agonist may provide therapeutic benefits for constipation associated with diabetes.

Consumption of indigestible saccharides and administration of Bifidobacterium pseudolongum reduce mucosal serotonin in murine colonic mucosa.

SCFA increase serotonin (5-hydroxytryptamine, 5-HT) synthesis and content in the colon in vitro and ex vivo, but little is known in vivo. We tested whether dietary indigestible saccharides, utilised as a substrate to produce SCFA by gut microbiota, would increase colonic 5-HT content in mice. Male C57BL/6J mice were fed a purified diet and water supplemented with 4 % (w/v) 1-kestose (KES) for 2 weeks. Colonic 5-HT content and enterochromaffin (EC) cell numbers were lower in mice supplemented with KES than those without supplementation, while monoamine oxidase A activity and mRNA levels of tryptophan hydroxylase 1 (Tph1), chromogranin A (Chga), Slc6a4 and monoamine oxidase A (Maoa) genes in the colonic mucosa, serum 5-HT concentration and total 5-HT content in the colonic contents did not differ between groups. Caecal acetate concentration and Bifidobacterium pseudolongum population were higher in KES-supplemented mice. Similar trends were observed in mice supplemented with other indigestible saccharides, that is, fructo-oligosaccharides, inulin and raffinose. Intragastric administration of live B. pseudolongum (108 colony-forming units/d) for 2 weeks reduced colonic 5-HT content and EC cell numbers. These results suggest that changes in synthesis, reuptake, catabolism and overflow of 5-HT in the colonic mucosa are not involved in the reduction of colonic 5-HT content by dietary indigestible saccharides in mice. We propose that gut microbes including B. pseudolongum could contribute to the reduction of 5-HT content in the colonic mucosa via diminishing EC cells.

Effect of Obesity on the Expression of Nutrient Receptors and Satiety Hormones in the Human Colon.

Background: Receptors located on enteroendocrine cells (EECs) of the colon can detect nutrients in the lumen. These receptors regulate appetite through a variety of mechanisms, including hormonal and neuronal signals. We assessed the effect of obesity on the expression of these G-protein coupled receptors (GPCRs) and hormones at both mRNA and protein level. Methods: qPCR and immunohistochemistry were used to examine colonic tissue from cohorts of patients from the Netherlands (proximal and sigmoid tissue) and the United Kingdom (tissue from across the colon) and patients were grouped by body mass index (BMI) value (BMI < 25 and BMI ≥ 25). Results: The mRNA expression of the hormones/signaling molecules serotonin, glucagon, peptide YY (PYY), CCK and somatostatin were not significantly different between BMI groups. GPR40 mRNA expression was significantly increased in sigmoid colon samples in the BMI ≥ 25 group, but not proximal colon. GPR41, GPR109a, GPR43, GPR120, GPRC6A, and CaSR mRNA expression were unaltered between low and high BMI. At the protein level, serotonin and PYY containing cell numbers were similar in high and low BMI groups. Enterochromaffin cells (EC) showed high degree of co-expression with amino acid sensing receptor, CaSR while co-expression with PYY containing L-cells was limited, regardless of BMI. Conclusions: While expression of medium/long chain fatty acid receptor GPR40 was increased in the sigmoid colon of the high BMI group, expression of other nutrient sensing GPCRs, and expression profiles of EECs involved in peripheral mechanisms of appetite regulation were unchanged. Collectively, these data suggest that in human colonic tissue, EEC and nutrient-sensing receptor expression profiles are not affected despite changes to BMI.

Understanding the Central Nervous System Symptoms of Rotavirus: A Qualitative Review.

This qualitative review on rotavirus infection and its complications in the central nervous system (CNS) aims to understand the gut–brain mechanisms that give rise to CNS driven symptoms such as vomiting, fever, feelings of sickness, convulsions, encephalitis, and encephalopathy. There is substantial evidence to indicate the involvement of the gut–brain axis in symptoms such as vomiting and diarrhea. The underlying mechanisms are, however, not rotavirus specific, they represent evolutionarily conserved survival mechanisms for protection against pathogen entry and invasion. The reviewed studies show that rotavirus can exert effects on the CNS trough nervous gut–brain communication, via the release of mediators, such as the rotavirus enterotoxin NSP4, which stimulates neighboring enterochromaffin cells in the intestine to release serotonin and activate both enteric neurons and vagal afferents to the brain. Another route to CNS effects is presented through systemic spread via lymphatic pathways, and there are indications that rotavirus RNA can, in some cases where the blood brain barrier is weakened, enter the brain and have direct CNS effects. CNS effects can also be induced indirectly as a consequence of systemic elevation of toxins, cytokines, and/or other messenger molecules. Nevertheless, there is still no definitive or consistent evidence for the underlying mechanisms of rotavirus-induced CNS complications and more in-depth studies are required in the future.

Neuroendocrine Peptides of the Gut and Their Role in the Regulation of Food Intake.

The regulation of food intake encompasses complex interplays between the gut and the brain. Among them, the gastrointestinal tract releases different peptides that communicate the metabolic state to specific nuclei in the hindbrain and the hypothalamus. The present overview gives emphasis on seven peptides that are produced by and secreted from specialized enteroendocrine cells along the gastrointestinal tract in relation with the nutritional status. These established modulators of feeding are ghrelin and nesfatin-1 secreted from gastric X/A-like cells, cholecystokinin (CCK) secreted from duodenal I-cells, glucagon-like peptide 1 (GLP-1), oxyntomodulin, and peptide YY (PYY) secreted from intestinal L-cells and uroguanylin (UGN) released from enterochromaffin (EC) cells. © 2021 American Physiological Society. Compr Physiol 11:1679-1730, 2021.

Integrative bioinformatics analysis identifies LINC01614 as a potential prognostic signature in esophageal cancer.

BackgroundEsophageal cancer (EC) is one of the most common gastrointestinal cancers and the incidence is on the increase in recent years. The aim of the present study was to assess novel long non-coding RNA (lncRNA) biomarkers for the prognosis of EC through the analysis of gene expression microarrays.MethodsThree datasets (GSE53622, GSE53624, and GSE53625) were downloaded from the Gene Expression Omnibus (GEO) database and EC patients’ clinical information were from The Cancer Genome Atlas (TCGA) databases. Differentially expressed genes (DEGs) were screened by comparing tumor tissues with normal tissues using limma R package. The Gene Expression Profiling Interactive Analysis 2 (GEPIA2) database was used to obtain the novel lncRNAs and their co-expression genes in EC and these were visualized with the Cytoscape software. The Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology Based Annotation System (KOBAS) database was used to analyze the functions enrichment of selected DEGs. Cell Counting Kit-8 (CCK8) and Transwell assays were used to further confirm the function of target lncRNAs.ResultsWe identified 24 differentially expressed (DE) lncRNAs and 659 DE mRNAs from the intersection of GEO and TCGA databases. And we found that only LINC01614 was concerned with a candidate prognostic signature in EC. “Extracellular matrix (ECM)-receptor interaction” and “PI3K-Akt signaling pathway” were observed, and we constructed a lncRNA-mRNA co-expression network for EC that includes LINC01614 and 64 mRNAs. The results of CCK8 and Transwell assays showed that suppression of LINC01614 inhibited EC cell proliferation and migration.ConclusionsOur study might provide LINC01614 as a novel lncRNA biomarker for diagnosis and prognosis in EC.