Immunoreactivity for Dab2 and Foxp3 suggests that immune-suppressive cells are present in the regenerating tail blastema of lizard

Abstract

Immunoreactivity for Dab2 and Foxp3 suggests that immune-suppressive cells are present in the regenerating tail blastema of lizard. Acta Zoologica (Stockolm). Tail regeneration in lizards likely occurs in immune-evasive conditions. In order to strengthen this hypothesis, the presence of the tumour suppressor and macrophage marker Dab2 and the lymphocyte regulatory marker, Foxp3, are evaluated by immunofluorescence in lizard regenerating blastema. The observations reveal sparse Dab2 and Foxp3 cells among blastema cells, identified, respectively, as healing M2-macrophages and Tregs-lymphocytes. Dab2 is also detected in basal/suprabasal layers of the apical wound epidermis, suggesting that this protein may participate in controlling cell proliferation of the growing tail by regulating Epidermal Mesenchymal Transition. Tregs marker, Foxp3, is localized in sparse cells among blastema mesenchymal cells and in the regenerating apical ependyma, suggesting the presence of immune cells that stimulate healing and sustain blastema growth. However, due to a similar 14 amino acid-long epitope between Foxp3 and Foxj1, the employed antibody might also recognize the latter protein, known to be involved in ciliogenesis of ependymal cells in fish and amphibians. It is, therefore, possible that Foxj1 may also be produced in the regenerating ependyma of lizards during ciliogenesis. The study further supports the hypothesis that lizard tail regeneration occurs in immune-tolerant conditions and that organ regeneration in vertebrates can only occur in an immune-suppressed or immune-evasive environment.