Tunicamycin induced endoplasmic reticulum stress in the small intestine

Because the small intestine is exposed to variety of foreign substances, it participates in host immune response. We investigated whether the expression levels of intestinal MAdCAM-1, PECAM-1 (CD31) and CAV-1 are affected by endoplasmic reticulum (ER) stress following brief treatment with tunicamycin (TN). We administered a single dose of TN intraperitoneally. Twenty-four hours later, MAdCAM-1, PECAM-1 and CAV-1 expression levels in Peyer's patches and villi were examined using immunohistochemistry (IHC), immunofluorescence (IF) and western blotting. Immunostaining of MAdCAM-1 and CAV-1 in control and TN treated Peyer's patches and villi exhibited similar staining patterns. The immunoreactivity of PECAM-1 was similar for the control and TN treated Payer's patches, whereas staining was decreased significantly in TN treated villi. Our findings suggest that short term TN treatment did not affect leukocyte movement to lymphoid compartments of the small intestine, but it altered villus architecture due to decreased PECAM-1 expression.