Intestinal Alkaline Phosphatase: Potential Roles in Promoting Gut Health in Weanling Piglets and Its Modulation by Feed Additives — A Review

Abstract

The intestinal environment plays a critical role in maintaining swine health. Many factors such as diet, microbiota, and host intestinal immune response influence the intestinal environment. Intestinal alkaline phosphatase (IAP) is an important apical brush border enzyme that is influenced by these factors. IAP dephosphorylates bacterial lipopolysaccharides (LPS), unmethylated cytosine-guanosine dinucleotides, and flagellin, reducing bacterial toxicity and consequently regulating toll-like receptors (TLRs) activation and inflammation. It also desphosphorylates extracellular nucleotides such as uridine diphosphate and adenosine triphosphate, consequently reducing inflammation, modulating, and preserving the homeostasis of the intestinal microbiota. The apical localization of IAP on the epithelial surface reveals its role on LPS (from luminal bacteria) detoxification. As the expression of IAP is reported to be downregulated in piglets at weaning, LPS from commensal and pathogenic gram-negative bacteria could increase inflammatory processes by TLR-4 activation, increasing diarrhea events during this phase. Although some studies had reported potential IAP roles to promote gut health, investigations about exogenous IAP effects or feed additives modulating IAP expression and activity yet are necessary. However, we discussed in this paper that the critical assessment reported can suggest that exogenous IAP or feed additives that could increase its expression could show beneficial effects to reduce diarrhea events during the post weaning phase. Therefore, the main goals of this review are to discuss IAP’s role in intestinal inflammatory processes and present feed additives used as growth promoters that may modulate IAP expression and activity to promote gut health in piglets.

Effects of Probiotic Bacillus as an Alternative of Antibiotics on Digestive Enzymes Activity and Intestinal Integrity of Piglets

“…The intestinal environment plays a critical role in maintaining good health ( Farhadi et al, 2003 ; Melo et al, 2015 ). DAO is one of the indicators of intestinal epithelial integrity ( Tossou et al, 2016 ).…”

“…However, in the present study, piglets administrated with Ba had much lower DAO activity compared with antibiotic group, which may indicate much better state of intestinal integrity. AKPase is a new factor which contributes to maintain gut homeostasis ( Lalles, 2014 ; Melo et al, 2015 ). The deletion of intestinal AKPase gene caused a significant decrease of tight junction protein expression and function ( Liu et al, 2016 ).…”

Effects of in ovo feeding of L‐arginine on the development of digestive organs, intestinal function and post‐hatch performance of broiler embryos and hatchlings

“…The AKP is an enzyme capable of hydrolysing phosphate esters in an alkaline medium. The AKP is also involved in digestive‐absorptive processes of nutrients and the gut health by dephosphorylating bacterial lipopolysaccharides (LPS) and regulating Toll‐like receptors (TLR) activation immune in small intestine (Melo et al., ). Our results showed that IOF of Arg had a 1.5‐fold increase in duodenal AKP activity than other groups, suggesting that IOF of Arg contributed to improving the gut health and digestive‐absorptive function of small intestine.…”

Microbiota-host interplay at the gut epithelial level, health and nutrition

“…Most of the mechanisms of gut epithelial protection by IAP or iHSPs and their modulation by dietary components have been described, at least partly in the swine species too (e.g. for IAP: [47]).…”