Oligosaccharide modification by N-acetylglucosaminyltransferase-V in macrophages are involved in pathogenesis of bleomycin-induced scleroderma

Oligosaccharide modification by N-acetylglucosaminyltransferase-V (GnT-V), which catalyses the formation of β1,6 GlcNAc (N-acetylglucosamine) branches on N-glycans, is associated with various pathologies, such as cancer metastasis, multiple sclerosis and liver fibrosis. In this study, we demonstrated the involvement of GnT-V in the pathophysiology of scleroderma. High expression of GnT-V was observed in infiltrating cells in skin section samples from systemic and localized patients with scleroderma. Most of the infiltrating cells were T cells and macrophages, most of which were CD163⁺ M2 macrophages. To determine the role of GnT-V in scleroderma, we next investigated skin sclerosis in GnT-V knockout (MGAT5^-/-) mice. Expression of GnT-V was also elevated in bleomycin (BLM)-injected sclerotic skin, and MGAT5^-/- mice were resistant to BLM-induced skin sclerosis with reduced collagen type 1 α1 content, suggesting the biological significance of GnT-V in skin sclerosis. Furthermore, the number of CD163⁺ M2 macrophages and CD3-positive T cells in BLM-induced skin sclerosis was significantly fewer in MGAT5^-/- mice. In bone marrow-derived macrophages (BMDMs), IL-4-induced expressions of Fizz1 and Ym1 were significantly reduced in MGAT5^-/- mice-derived BMDMs. Taken together, these results suggest the induction of GnT-V in skin sclerosis progression is possibly dependent on increased numbers of M2 macrophages in the skin, which are important for tissue fibrosis and remodelling.