Adaptive Immunity and Skin Wound Healing in Amphibian Adults

Abstract

Regeneration and repair with scarring of the skin are two different responses to tissue injury that proceed depending on the animal species. Several studies in multiple organisms have shown that the effectiveness of tissue repair gradually decreases with age in most vertebrates, while the molecular and cellular mechanisms underlying the diverse potentials remain incompletely understood. It is clear, however, that immune system actively participates in the whole process and immune-related activities can mediate both negative and positive roles to influence the quality and diversity of tissue response to damage. Compared with innate immunity, our understanding of the significance of adaptive immune cells in normal repair outcome is limited and deserves further investigation. Here, experimental evidence supporting the contribution of lymphocytes and the involvement of lymphoid organs in skin wound healing are discussed, focusing on the findings emerged in adult amphibians, key animal models for tissue repair and regeneration research.

Keywords: adaptive immunity; amphibians; lymphoid organs; skin wound healing.

Figure 1

Light micrographs of the spleen of 15 month old X. laevis adults. The comparison between the sections from unwounded (A) and operated (14 day after the skin wounding) frogs (B) shows structural changes in the white pulp (wp): note the well developed lymphoid follicles with central light cores (arrows in B). C) The melanomacrophage centers (arrows), induced during the repair process, are indicated in splenic white pulp. The sections were stained with PAS/hematoxylin reaction, scale bars = 100 μm (A, B) and 10 μm (C).