Intestinal epithelial cells and enteric nervous system (IEC-ENS)

The intestinal epithelial cells (IECs) and the enteric nervous system (ENS) form a highly integrated functional unit that maintains gastrointestinal homeostasis and facilitates communication along the gut-brain axis (Furness, 2012). IECs serve as a physical and biochemical barrier, regulating nutrient absorption and secreting hormones like serotonin from enteroendocrine cells to signal the underlying nervous tissue (Mayer, 2011). The ENS, often referred to as the "second brain," consists of a complex network of neurons and glia that autonomously control gut motility, secretion, and blood flow (Furness, 2012). Dysregulation of the interactions between these two components is a hallmark of functional gastrointestinal disorders, such as irritable bowel syndrome (IBS), and organic diseases like inflammatory bowel disease (IBD) (Okumura & Nozu, 2018). While the IEC-ENS system itself is not a single molecular target, it contains a multitude of specific receptors—including 5-HT4 receptors and guanylate cyclase-C—that are targeted by drugs to treat motility and secretory disorders (Mayer, 2011). Therapeutic strategies often focus on modulating the neuro-epithelial interface to restore normal transit and barrier integrity. Emerging research also suggests this system plays a role in neurodegenerative diseases, where gut pathology may precede central nervous system symptoms. Understanding the synergy between epithelial sensing and neuronal response is crucial for developing next-generation gastrointestinal therapies.

Other names

Gut-brain axisEnteric neuro-epithelial unitGastrointestinal mucosal-neural interfaceEnteric neuro-immune system

Pharmacological agents modulate this system by targeting specific receptors (e.g., 5-HT4, GC-C, mu-opioid), ion channels, or enzymes located on intestinal epithelial cells or enteric neurons to regulate intestinal secretion, barrier permeability, and motor patterns (Furness, 2012; Mayer, 2011).