Dendritic Cell Migration to Skin-Draining Lymph Nodes Is Controlled by Dermatan Sulfate and Determines Adaptive Immunity Magnitude.

For full activation of naïve adaptive lymphocytes in skin-draining lymph nodes (LNs), presentation of peptide:MHC complexes by LN-resident and skin-derived dendritic cells (DCs) that encountered antigens (Ags) is an absolute prerequisite. To get to the nearest draining LN upon intradermal immunization, DCs need to migrate from the infection site to the afferent lymphatics, which can only be reached by traversing a collagen-dense network located in the dermis of the skin through the activity of proteolytic enzymes. Here, we show that mice with altered collagen fibrillogenesis resulting in thicker collagen fibers in the skin display a reduced DC migration to the draining LN upon immune challenge. Consequently, the initiation of the cellular and humoral immune response was diminished. Ag-specific CD8+ and CD4+ T cells as well as Ag-specific germinal center B cells and serum immunoglobulin levels were significantly decreased. Hence, we postulate that alterations to the production of extracellular matrix, as seen in various connective tissue disorders, may in the end affect the qualitative outcome of adaptive immunity.

Dermatan Sulfate-Free Mice Display Embryological Defects and Are Neonatal Lethal Despite Normal Lymphoid and Non-Lymphoid Organogenesis.

The epimerization of glucuronic acid into iduronic acid adds structural variability to chondroitin/dermatan sulfate polysaccharides. Iduronic acid-containing domains play essential roles in processes such as coagulation, chemokine and morphogen modulation, collagen maturation, and neurite sprouting. Therefore, we generated and characterized, for the first time, mice deficient in dermatan sulfate epimerase 1 and 2, two enzymes uniquely involved in dermatan sulfate biosynthesis. The resulting mice, termed DKO mice, were completely devoid of iduronic acid, and the resulting chondroitin sulfate chains were structurally different from the wild type chains, from which a different protein binding specificity can be expected. As a consequence, a vast majority of the DKO mice died perinatally, with greatly variable phenotypes at birth or late embryological stages such as umbilical hernia, exencephaly and a kinked tail. However, a minority of embryos were histologically unaffected, with apparently normal lung and bone/cartilage features. Interestingly, the binding of the chemokine CXCL13, an important modulator of lymphoid organogenesis, to mouse DKO embryonic fibroblasts was impaired. Nevertheless, the development of the secondary lymphoid organs, including the lymph nodes and spleen, was normal. Altogether, our results indicate an important role of dermatan sulfate in embryological development and perinatal survival.