Investigation of prion proteins in normal and Tunicamycin-treated mouse secondary lymphoid tissues

The peripheral lymphoid organs, which consist of the lymph nodes, the spleen, and the mucosal immune systems, are organized to promote the development of adaptive immune responses. Except from the spleen, leukocyte migration to these systems occurs via specialized post-capillary venules (high endothelial venulesHEVs). In the present study molecules which are responsible for transendothelial migration of the leukocyte and prion proteins which may trigger neurodegenerative disorders when they undergo structural shift have been investigated in mesenteric lymph node and ileums of experimentally endoplasmic reticulum stress-induced mice. Our immunohistochemistry and immunoflourence findings indicated that prion protein is expressed in mesenteric lymph node and Peyer's patches HEVs and, germinal centers of mesenteric lymph nodes and villus tips of ileum. There was no significant effect of Tunicamycin treatment on prion protein expression in the lymph nodes and ileums (p > 0.05). CAV-1 expression, which is significantly decreased by tunicamycin treatment in the mesenteric lymph nodes, was similar in the ileum. On the other hand, when compared the control and Tunicamycin-treated groups, PECAM-1 (CD31) expression was not altered in the lymph nodes but significantly decreased in small intestine villi (p < 0.05). In the Peyer's patches, the number of MAdCAM-1-positive cells was decreased after the Tunicamycin treatment (p < 0.05). However, the expression of PNAds in mesenteric lymph node HEVs was strongly increased upon the tunicamycin treatment (p < 0.05). Western blotting findings were confirmed our immunohistochemistry and immunoflourence results. We concluded that 1) short-term endoplasmic reticulum stress may cause an alteration in leukocyte homing mechanisms and, 2) Prion proteins enter mesenteric lymph nodes through HEVs and XII localized in germinal centers. However, in the ileum, these proteins may also use intestinal villi besides HEVs for entering the lymphoid parenchyma. This is probably important, because oral intake of prion protein may play a crucial role in the pathogenesis of prion-related disorders. Key Words: Prion, Adhesion molecules, Immunohistochemistry, Mesenteric lymph node, Peyer's patches