Involvement of OX40-OX40L interactions in the intestinal manifestations of the murine acute graft-versus-host disease.

Background & Aims: The intestinal histology of murine semiallogeneic graft-versus-host (GVH) disease is characterized by lymphocytic infiltrates, crypt hyperplasia, and villous atrophy. Mechanisms of T cell-mediated changes of the mucosal architecture were investigated.
Methods: The rate of cellular apoptosis and proliferation, changes in the composition of extracellular matrix (ECM), and the role of OX40-OX40L interactions in the pathogenesis of villous atrophy and crypt hyperplasia were examined.
Results: The rate of apoptosis and the number of proliferating cells were significantly increased in GVH animals compared with control animals. In addition, expression of tenascin, an ECM component, was down-regulated in GVH animals. Inhibition of OX40-OX40L interactions in GVH animals by administration of an OX40-Ig fusion protein completely prevented the development of crypt hyperplasia and villous atrophy in GVH animals. Tenascin expression was up-regulated in OX40-Ig-treated mice compared with GVH animals, suggesting an important function of this ECM component in mucosal repair.
Conclusions: The OX40-OX40L interaction is crucial in the pathogenesis of GVH, a T cell-mediated intestinal disease. The data suggest that the ECM component tenascin is probably relevant for the regeneration and maintenance of intestinal tissue architecture.