Small Intestinal Tuft Cell Activity Associates With Energy Metabolism in Diet-Induced Obesity

Colonic Tuft Cells: The Less-Recognized Therapeutic Targets in Inflammatory Bowel Disease and Colorectal Cancer

Tuft cells are more than guardian chemosensory elements of the digestive tract. They produce a variety of immunological effector molecules in response to stimulation; moreover, they are essential for defense against protozoa and nematodes. Beyond the description of their characteristics, this review aims to elucidate the potential pathogenic and therapeutic roles of colonic tuft cells in inflammatory bowel disease and colorectal cancer, focusing on their primarily immunomodulatory action. Regarding inflammatory bowel disease, tuft cells are implicated in both maintaining the integrity of the intestinal epithelial barrier and in tissue repair and regeneration processes. In addition to maintaining intestinal homeostasis, they display complex immune-regulatory functions. During the development of colorectal cancer, tuft cells can promote the epithelial-to-mesenchymal transition, alter the gastrointestinal microenvironment, and modulate both the anti-tumor immune response and the tumor microenvironment. A wide variety of their biological functions can be targeted for anti-inflammatory or anti-tumor therapies; however, the adverse side effects of immunomodulatory actions must be strictly considered.

Intestinal Tuft Cells: Morphology, Function, and Implications for Human Health

Tuft cells are a rare and morphologically distinct chemosensory cell type found throughout many organs, including the gastrointestinal tract. These cells were identified by their unique morphologies distinguished by large apical protrusions. Ultrastructural data have begun to describe the molecular underpinnings of their cytoskeletal features, and tuft cell-enriched cytoskeletal proteins have been identified, although the connection of tuft cell morphology to tuft cell functionality has not yet been established. Furthermore, tuft cells display variations in function and identity between and within tissues, leading to the delineation of distinct tuft cell populations. As a chemosensory cell type, they display receptors that are responsive to ligands specific for their environment. While many studies have demonstrated the tuft cell response to protists and helminths in the intestine, recent research has highlighted other roles of tuft cells as well as implicated tuft cells in other disease processes including inflammation, cancer, and viral infections. Here, we review the literature on the cytoskeletal structure of tuft cells. Additionally, we focus on new research discussing tuft cell lineage, ligand-receptor interactions, tuft cell tropism, and the role of tuft cells in intestinal disease. Finally, we discuss the implication of tuft cell-targeted therapies in human health and how the morphology of tuft cells may contribute to their functionality.

DEHP and DBP, common phthalates, induce glucose metabolism disorders in rats via oxidative damage of PI3K/Akt/GLUT4 signaling

Phthalic acid esters (PAEs) are environmental endocrine disruptors thought to interfere with glucose metabolism in humans. Most of the related research has focused on population epidemiological studies, with the underlying mechanisms remaining unresolved. Using an in vivo animal model, we examined the effects of oral administration of two commonly used PAEs [di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP)] on glucose homeostasis and insulin secretion. DEHP (750 mg/kg, 1/40 LD50), DBP (500 mg/kg, 1/40 LD50), and DEHP (750 mg/kg) + DBP (500 mg/kg) exert an influence on glucose metabolism and elicit a reduction in insulin sensitivity in rats. Furthermore, these substances induce detrimental effects on the structure and functionality of pancreatic β-cells. DEHP and/or DBP triggered an increase in plasma malondialdehyde (MDA) and reduction in superoxide dismutase (SOD) activity; a reduction in the phosphorylation of phosphatidyl inositol 3 kinase (PI3K) and phospho-protein kinase B (p-Akt473) proteins; an increase in the relative expression of Bax, Caspase-8, cleaved-Caspase-9, and cleaved-Caspase-3; and a reduction in the relative expression of Bcl-2-related Bax in pancreatic tissue and of gastrocnemius glucose transporter 4 (GLUT4) in the gastrocnemius muscle. Based on these findings, these PAEs can disrupt glucose metabolism, possibly via oxidative damage of the PI3K/Akt/GLUT4 pathway; this damage induces pancreatic β-cell apoptosis, affects pancreatic β-cell function, and affects glucose metabolism and insulin resistance in rats. To the best of our knowledge, this study was the first to show that the combined effect of the two PAEs affects glucose metabolism and insulin resistance in rats that is significantly higher than the effects of each PAE. Thus, safety standards and studies do not consider this effect as a significant oversight when blending PAEs. We assert that this must be addressed and corrected for establishing more impactful and safer standards.

Possible connection between intestinal tuft cells, ILC2s and obesity

Intestinal tuft cells (TCs) are defined as chemosensory cells that can "taste" danger and induce immune responses. They play a critical role in gastrointestinal parasite invasion, inflammatory bowel diseases and high-fat diet-induced obesity. Intestinal IL-25, the unique product of TCs, is a key activator of type 2 immunity, especially to promote group 2 innate lymphoid cells (ILC2s) to secret IL-13. Then the IL-13 mainly promotes intestinal stem cell (ISCs) proliferation into TCs and goblet cells. This pathway formulates the circuit in the intestine. This paper focuses on the potential role of the intestinal TC, ILC2 and their circuit in obesity-induced intestinal damage, and discussion on further study and the potential therapeutic target in obesity.

Tuft Cells: Detectors, Amplifiers, Effectors and Targets in Parasite Infection

Tuft cells have recently emerged as the focus of intense interest following the discovery of their chemosensory role in the intestinal tract, and their ability to activate Type 2 immune responses to helminth parasites. Moreover, they populate a wide range of mucosal tissues and are intimately connected to immune and neuronal cells, either directly or through the release of pharmacologically active mediators. They are now recognised to fulfil both homeostatic roles, in metabolism and tissue integrity, as well as acting as the first sensors of parasite infection, immunity to which is lost in their absence. In this review we focus primarily on the importance of tuft cells in the intestinal niche, but also link to their more generalised physiological role and discuss their potential as targets for the treatment of gastrointestinal disorders.

An update on the biological characteristics and functions of tuft cells in the gut

The intestine is a powerful digestive system and one of the most sophisticated immunological organs. Evidence shows that tuft cells (TCs), a kind of epithelial cell with distinct morphological characteristics, play a significant role in various physiological processes. TCs can be broadly categorized into different subtypes depending on different molecular criteria. In this review, we discuss its biological properties and role in maintaining homeostasis in the gastrointestinal tract. We also emphasize its relevance to the immune system and highlight its powerful influence on intestinal diseases, including inflammations and tumors. In addition, we provide fresh insights into future clinical diagnostic and therapeutic strategies related to TCs.

Tuft Cells and Their Role in Intestinal Diseases

The interests in intestinal epithelial tuft cells, their basic physiology, involvement in immune responses and relevance for gut diseases, have increased dramatically over the last fifteen years. A key discovery in 2016 of their close connection to helminthic and protozoan infection has further spurred the exploration of these rare chemosensory epithelial cells. Although very sparse in number, tuft cells are now known as important sentinels in the gastrointestinal tract as they monitor intestinal content using succinate as well as sweet and bitter taste receptors. Upon stimulation, tuft cells secrete a broad palette of effector molecules, including interleukin-25, prostaglandin E2 and D2, cysteinyl leukotriene C4, acetylcholine, thymic stromal lymphopoietin, and β-endorphins, some of which with immunomodulatory functions. Tuft cells have proven indispensable in anti-helminthic and anti-protozoan immunity. Most studies on tuft cells are based on murine experiments using double cortin-like kinase 1 (DCLK1) as a marker, while human intestinal tuft cells can be identified by their expression of the cyclooxygenase-1 enzyme. So far, only few studies have examined tuft cells in humans and their relation to gut disease. Here, we present an updated view on intestinal epithelial tuft cells, their physiology, immunological hub function, and their involvement in human disease. We close with a discussion on how tuft cells may have potential therapeutic value in a clinical context.

Enteric Tuft Cells in Host-Parasite Interactions

Enteric tuft cells are chemosensory epithelial cells gaining attention in the field of host-parasite interactions. Expressing a repertoire of chemosensing receptors and mediators, these cells have the potential to detect lumen-dwelling helminth and protozoan parasites and coordinate epithelial, immune, and neuronal cell defenses against them. This review highlights the versatility of enteric tuft cells and sub-types thereof, showcasing nuances of tuft cell responses to different parasites, with a focus on helminths reflecting the current state of the field. The role of enteric tuft cells in irritable bowel syndrome, inflammatory bowel disease and intestinal viral infection is assessed in the context of concomitant infection with parasites. Finally, the review presents pertinent questions germane to understanding the enteric tuft cell and its role in enteric parasitic infections. There is much to be done to fully elucidate the response of this intriguing cell type to parasitic-infection and there is negligible data on the biology of the human enteric tuft cell—a glaring gap in knowledge that must be filled.