Assessment of Intestinal Permeability in Young Piglet to Pave the Way to Oral Vaccination

Abstract

\n The small intestine of the piglet has evolved to be permeable immediately after birth to facilitate the uptake of colostrum-derived immunoglobulins, other macromolecules, and cells. However, the precise timing of gut closure in today’s precocious pig is not known. We gavaged piglets immediately after birth and at 1 hour after birth with Cy5-labeled Ovalbumin (Cy5-Ova) then harvested their small intestine’s 6-7 hours later. To assess localization of Cy5-Ova in the small intestinal epithelial cells, we perform immunohistochemistry using a basolateral surface marker and a recycling endosome marker called pIgR, the late endosomal marker Rab7, and the lysosomal marker LAMP-1. Cy5-Ova co-localized with Rab7 and LAMP-1 in the duodenum and jejunum of 0 hour old and 1 hour old gavaged piglets, but only in the ileum of 0 hour gavaged piglets. These data suggest that movement of Cy5-Ova through the late endosomes to the lysosomes was much reduced in the ileum of 1 hour gavaged piglets, possibly impacted by prior processing of colostral macromolecules. Cy5-Ova was largely present in epithelial cell digestive and transport vacuoles, but it did not colocalize with pIgR-positive endosomes in 0 hour and 1 hour gavaged piglets. Understanding the relationship between the localization of Cy5-Ova and small intestinal permeability may contribute to establishing whether oral vaccination in the newborn can capitalize on the transient permeability before gut closure to promote immune protection.