Coeliac disease-specific autoantibodies targeted against transglutaminase 2 disturb angiogenesis

Coeliac disease is characterized by immunoglobulin-A (IgA)-class autoantibodies targeted against transglutaminase 2 (TG2), a multi-functional protein also with a role in angiogenesis. These antibodies are present in patient serum but are also found bound to TG2 below the epithelial basement membrane and around capillaries in the small intestinal mucosa. Based on these facts and the information that the mucosal vasculature of coeliac patients on a gluten-containing diet is disorganized, we studied whether the coeliac disease-specific autoantibodies targeted against TG2 would disturb angiogenesis. The effects of coeliac disease-specific autoantibodies on in vitro angiogenesis were studied in angiogenic cell cultures. The binding of the antibodies to cells, endothelial sprouting, migration of both endothelial and vascular mesenchymal cells, the integrity of the actin cytoskeleton in both cell types and the differentiation of vascular mesenchymal cells were recorded. In vitro, IgA derived from coeliac disease patients on a gluten-containing diet binds to surface TG2 on endothelial and vascular mesenchymal cells and this binding can be inhibited by the removal of TG2. In addition, coeliac disease-specific autoantibodies targeting TG2 disturb several steps of angiogenesis: endothelial sprouting and the migration of both endothelial and vascular mesenchymal cells. Furthermore, the autoantibodies cause disorganization of the actin cytoskeleton in both capillary cell types that account most probably for the defective cellular migration. We conclude that coeliac disease-specific autoantibodies recognizing TG2 inhibit angiogenesis in vitro. This disturbance of the angiogenic process could lead in vivo to the disruption of the mucosal vasculature seen in coeliac disease patients on a gluten-containing diet.