Secreted effectors of the innate mucosal barrier
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
Enteroendocrine cells account for approximately 1% of intestinal epithelial cells with about 15 different subtypes that express various enteric hormones. Downstream of the Notch–Math1 pathway is the bHLH transcription factor Neurogenin 3, which is required for development of the enteroendocrine cell lineage. Downstream of Neurogenin 3, additional bHLH and homeodomain transcription factors have been shown to be important for the development of specific enteroendocrine subtypes. Another relatively infrequent differentiated epithelial cell type is tuft cells that have a unique morphology with long and thick microvilli projecting into the lumen. These cells share morphologic and functional features with taste-receptor cells that express the cation channel Trpm5 and play a role in type 2 immune responses initiated by protozoa and helminth parasite infections, where they are the source of IL-25.
Regulation of Food Intake
Nathalie Bergeron, Patty W. Siri-Tarino, George A. Bray, Ronald M. Krauss in Nutrition and Cardiometabolic Health, 2017
Enteroendocrine cells (EECs) are distributed throughout the gastrointestinal tract and are responsible for the secretion of these peptide hormones. There are open and closed types of EECs that are located throughout the GI tract. Open EECs are cone-shaped cells with microvilli at their open end while the closed end lies abutting the basal lamina. The microvilli at the open end sense the macronutrients in food via G-protein-coupled receptors (by stimulating the chemosensors on these receptors). This leads to release of gut hormones that act through endocrine, paracrine, and neural mechanisms to regulate food intake and energy homeostasis. Closed EECs do not have direct contact with luminal contents but utilize the neural mechanisms to exert their role. Sensory information from the gastrointestinal tract and abdominal viscera as well as taste information from the oral cavity are initially integrated by the NTS.
Gastrointestinal Function and Toxicology in Minipigs
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
Brunner’s glands are present in the minipig duodenum, and aid goblet cells (located along the length of the entire small intestine) in producing mucin and bicarbonate to increase intestinal pH, protect the intestinal mucosa, and aid in absorption of nutrients (Allen and Garner 1980, Allen and Flemstrom 2005, Van Ginneken 2012). The small intestine contains a large variety of enteroendocrine cells, and their function depends on location within the intestinal crypt. Deeper in the crypts the enteroendocrine cells have an endocrine function, and release hormones that influence a variety of intestinal activities (secretions, motility, etc.). Enteroendocrine cells located further from the crypts, towards the tips of the villus aid in absorbing nutrients. Peyer’s patches are seen throughout the ileum of minipigs, with a long continuous band of Peyer’s patches within the jejunum (Rothkotter and Pabst 1989). Motility within the small intestine of pigs is less variable than that of the stomach. While feeding regimen and meal size can affect intestinal motility (Ruckenbusch and Bueno 1976), transit times of ingested solids and liquids are similar to that of humans (Suenderhauf and Parrott 2013).
Evaluation of plasma cholecystokinin levels and gallbladder functions in hyperemesis gravidarum: a prospective cohort study
Published in Journal of Obstetrics and Gynaecology, 2022
Müge Keskin, Tuba Çandar, Mehmet Çoban, Kaan Gökçe Ataç, Aslı Yarci Gürsoy, Gamze Sinem Çağlar
Cholecystokinin (CCK) is a gastrointestinal hormone and a neurotransmitter peptide expressed in the brain. It is secreted by enteroendocrine cells (I cells) located in the mucosa of the duodenum, jejunum and proximal ileum and by specialised neurons in the myenteric plexus and brain. CCK stimulates contraction of the gallbladder (GB) and relaxation of the sphincter of Oddi (Liddle 2000; Wang et al. 2017). Pregnancy induces morphological and functional biliary tract changes, and both animal and human studies have reported elevated CCK levels during pregnancy (Rådberg et al. 1987; Frick et al. 1990). Even if the pathophysiology has not yet been clarified, the proposed mechanisms depend on either enhanced secretion or reduced elimination of CCK (Rådberg et al. 1987). Concerning the physiological implications of enhanced CCK levels, GB contractility does not increase during pregnancy (Rådberg et al. 1987; Portincasa et al. 2003; Housset et al. 2016), possibly because of reduced GB sensitivity to CCK (Kline and Karpinski 2005) with the decrease in the CCK-A receptor expression or impaired signalling through this receptor during pregnancy (Ladyman et al. 2011).
Healthy Intestinal Function Relies on Coordinated Enteric Nervous System, Immune System, and Epithelium Responses
Published in Gut Microbes, 2021
Fatima B. Saldana-Morales, Dasom V. Kim, Ming-Ting Tsai, Gretchen E. Diehl
IECs have specialized functions. Enterocytes, the most common IECs, are responsible for nutrient and water absorption. Goblet cells secrete mucins, the glycoprotein constituent of mucus. Mucus creates a barrier limiting direct microbial interactions with the epithelium.13 Enteroendocrine cells secrete hormones such as glucagon-like peptide 1 and cholecystokinin to support digestion and metabolism.14 Paneth cells are limited to the small intestine and release growth factors that promote proliferation and differentiation of stem cells and antimicrobial peptides that shape the composition of the microbiota and limit microbial growth near the epithelium.15 M cells overlay organized immune structures including Peyer’s patches and isolated lymphoid follicles to transfer luminal antigens to underlying immune cells allowing for immune surveillance.16 M cells can also allow entry of pathogenic and nonpathogenic microorganisms into the tissue. Within the epithelium, intraepithelial lymphocytes (IELs) are also found. IELs are innate like T cells that can rapidly respond to pathogen infection and are critical to intestinal tolerance and epithelial barrier function.17
Spatiotemporal organization of enteroendocrine peptide expression in Drosophila
Published in Journal of Neurogenetics, 2021
Sooin Jang, Ji Chen, Jaekyun Choi, Seung Yeon Lim, Hyejin Song, Hyungjun Choi, Hyung Wook Kwon, Min Sung Choi, Jae Young Kwon
The gastrointestinal tract carries out various functions such as digesting food and absorbing nutrients necessary for maintaining daily life, as well as immune defense. It is also regarded as the largest endocrine organ involved in metabolic homeostasis, mediated by enteroendocrine cells that secrete peptide hormones (Batterham et al., 2002; Mikani, Wang, & Takeda, 2012). Enteroendocrine cells fall into many classes based on the peptides they express. Studies on the organization and function of these different enteroendocrine cells provide essential insight into the metabolism and physiology of an organism as a whole (Gribble & Reimann, 2015). More than 15 peptides have been identified to date in the mammalian gut, and more than 10 peptides in the Drosophila melanogaster gut. Enteroendocrine cells have been found to express combinations of these peptides, and these combinations vary with location along the anterior-posterior axis of the gut (Hartenstein, Takashima, Hartenstein, Asanad, & Asanad, 2017).
Related Knowledge Centers
- Chemoreceptor
- Enteric Nervous System
- Gastrointestinal Tract
- Nervous System
- Pancreas
- Paracrine Signaling
- Endocrine System
- Cell
- Gastrointestinal Hormone
- Short-Chain Fatty Acid