# Intestinal Alkaline Phosphatase Expression in Response to Escherichia coli Infection in Nursery Pigs

## TL;DR

This study shows that infection with E. coli in young pigs increases intestinal alkaline phosphatase (IAP), which may help defend against gut infections.

## Contribution

The study demonstrates that IAP is upregulated in response to E. coli infection in pigs, suggesting a potential role as a gut health biomarker.

## Key findings

- IAP levels increased significantly in the small intestine of pigs infected with E. coli K88.
- IAP expression was upregulated on the apical surface of intestinal villi following bacterial challenge.
- The increase in IAP is likely triggered by lipopolysaccharides from Gram-negative bacteria.

## Abstract

Intestinal alkaline phosphatase (IAP) is an enzyme produced by cells lining the small intestine that plays a key role in maintaining gut health. In this study, we investigated how IAP responds in young pigs infected with Escherichia coli (E. coli) K88, a bacterium known to cause diarrhea. After exposure to E. coli, we found that IAP levels were significantly increased in the small intestine, particularly on the surface of the intestinal villi. This increase was observed using laboratory techniques such as immunohistochemistry and molecular analysis. The results suggest that IAP is activated in response to bacterial infection and may serve as a natural defense mechanism against harmful substances such as lipopolysaccharides (LPSs) from bacteria. Our findings highlight the potential use of IAP as a marker for gut health and a tool for detecting intestinal infections in animals.

Intestinal alkaline phosphatase (IAP) is a brush border enzyme secreted by enterocytes, playing a crucial role in maintaining gut mucosal defense. This study investigated the expression dynamics of IAP in the small intestine of pigs challenged with Escherichia coli (E. coli) K88, compared to healthy controls. Five-week-old pigs (n = 8) were orally administered E. coli K88 at a concentration of 2 × 108 CFU/mL, with a dose of 2 mL per pig at 0 and 24 h. Five days post-challenge, tissue samples from the duodenum, jejunum, and ileum were collected for mucosal morphometric analysis and evaluation of IAP expression via immunohistochemistry, Western blotting, and real-time PCR. The results revealed the presence of IAP on the apical surface of villi throughout the small intestine, along with significantly upregulated IAP expression in E. coli-challenged pigs compared to controls. These findings suggest that Gram-negative bacteria such as E. coli can induce IAP expression, likely through lipopolysaccharide (LPS) stimulation, thereby enhancing its enzymatic activity as part of the intestinal defense mechanism. This study provides insight into the protective role of IAP and highlights its potential as a biomarker for assessing gut health and diagnosing enteric infections in animals.