Dach1 transcription factor regulates the expression of peripheral node addressin and lymphocyte trafficking in lymph nodes

Lymphocytes regulate the immune response by circulating between the vascular and lymphatic systems. High endothelial venules, HEVs, special blood vessels expressing selective adhesion molecules, such as PNAd and MAdCAM-1, mediate naïve lymphocyte migration from the vasculature into the lymph nodes and Peyer's patches. We have identified that DACH1 is abundantly expressed in developing HEV-type endothelial cells. DACH1 showed a restricted expression pattern in lymph node blood vessels during the late fetal and early neonatal periods, corresponding to HEV development. The proportion of MAdCAM-1⁺ and CD34⁺ endothelial cells is reduced in the lymph nodes of neonatal conventional and vascular-specific Dach1-deficient mice. Dach1-deficient lymph nodes in adult mice demonstrated a lower proportion of PNAd⁺ cells and lower recruitment of intravenously administered lymphocytes from GFP transgenic mice. These findings suggest that DACH1 promotes the expression of HEV-selective adhesion molecules and mediates lymphocyte trafficking across HEVs into lymph nodes.