Abstract
Secretory immunoglobulin A (SIgA) is one important line of defense in the intestinal mucosal surface to protect the intestinal epithelium from enteric toxins and pathogenic microorganisms. Multiple factors, such as intestinal microbiota, intestinal cytokines, and nutrients are highly involved in production of SIgA in the intestine. Recently, glutamine has been shown to affect intestinal SIgA production; however, the underlying mechanism by which glutamine stimulates secretion of intestinal SIgA is unknown. Here, we review current knowledge regarding glutamine in intestinal immunity and show that glutamine-enhanced secretion of SIgA in the intestine may involve intestinal microbiota, intestinal antigen sampling and presentation, induction pathways for SIgA production by plasma cells (both T-dependent and T-independent pathway), and even transport of SIgA. Altogether, the glutamine-intestinal SIgA axis has broad therapeutic implications for intestinal SIgA-associated diseases, such as celiac disease, allergies, and inflammatory bowel disease.
Highlights
The mammalian intestine is home to large numbers of bacteria, many of which invade the intestinal epithelium to enter the systemic circulation
Intestinal epithelia can be classified as villus epithelium (VE), which is mainly involved in digestion and absorption of nutrients, and follicle-associated epithelium (FAE), which promotes contact with luminal antigens to induce mucosal immune responses
The uptake of dIgA or pIgA is mediated by polymeric immunoglobulin receptor (pIgR). pIgR is a 120 kDa transmembrane protein consisting of five extracellular immunoglobulin (Ig) homology domains, a transmembrane region and a cytoplasmic domain, and is expressed on the basolateral surface of epithelial cells. pIgR binds dIgA or pIgA at the basolateral side of epithelial cells, the dIgA-pIgR or pIgA-pIgR complex is shuttled to the apical membrane of epithelial cells by vesicles
Summary
The mammalian intestine is home to large numbers of bacteria, many of which invade the intestinal epithelium to enter the systemic circulation. Secretory immunoglobulin A (SIgA) is the principal regulator of adaptive defenses on the intestinal mucosal surface of humans and many other mammals, such as mice, pigs, and rats. The characterized functions of SIgA in the intestine include: [1] immune exclusion via interacting with environmental antigens (e.g., bacteria, viruses, and toxins); [2] anti-inflammation by sampling intestinal antigens to induce Th2 or regulatory T cell-biased mucosal immune responses; [3] homeostasis of commensals by enhancing the cross talk between the probiotic bacteria and the intestinal mucosa [2, 3]. Compelling evidence from well-designed investigations have shown that glutamine supplementation increases the abundance of SIgA in the intestine in various hosts, including rats [4, 5], mice [6, 7], Chinese Holstein calves [8], pigs [9], humans [10], and even broiler chickens [11]. We discuss the current evidence about underlying mechanisms whereby glutamine enhances production of intestinal SIgA
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
