Goblet cells functions. (IMAGE)
Caption
Goblet cells (GCs) play a multifaceted role in the mucosal immune system, including (A) Mucin secretion: GCs constantly produce mucins forming a protective gel layer on the surface of the intestine. This mucus barrier acts as a first line of defence, trapping pathogens and preventing them from reaching the underlying tissues. Under normal circumstances, the thickness of this gel remains upheld through continuous mucin secretion. Nevertheless, when the gut faces challenges such as microbial intrusion or harsh stimuli, GCs undergo stimulation to accelerate mucin release. Both, physiological or pathological stimuli, result in a marked increase in intracellular calcium ions (Ca2+)-triggered stimulated mucus secretion. Various factors like neuropeptides, cytokines and lipids further influence the stimulated mucin release. On acetylcholine (ACh) exposure, the activation of muscarinic ACh receptor 1 (mAChR1) also triggers the mobilisation of Ca2+ from intracellular reserves contributing to mucus secretion and effectively displacing pathogens from the gut lining. (B) Other secretory functions: The release of chemokines and cytokines initiates and strengthens Th2 responses facilitating tissue repair and attracting effector cells that perform functions crucial to innate immunity extending beyond mere barrier maintenance. GCs also discharge antimicrobial peptides (AMPs) including resistin-like molecule ß, regenerating islet-derived 3 proteins and trefoil factor which effectively eliminate commensal bacteria and pathogens that breach the mucus layer. (C) GC-associated antigen passages (GAPs): Activation of mAChR4 by ACh initiates a process termed fluid-phase bulk endocytosis culminating in the formation of GAPs in the small intestine. Endocytic vesicles containing luminal fluid-phase cargo are transported through the cell for degradation, membrane recycling and transcytosis. This allows the cargo to be acquired by lamina propria dendritic cells (LP-DCs). The main LP-DCs subset subadjacent to GAPs is the CD103+CX3CR1− subset and possesses preferential tolerogenic properties. Created with BioRender.com. E.R., endoplasmic reticulum; IEC, intestinal epithelial cells.
Credit
By Fernanda Raya Tonetti, Alvaro Eguileor, Cristina Llorente.
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CC BY-NC