Editorial [ The Wide Roles of Cytokines During Evolution Executive Editors: M. de Eguileor and E. Ottaviani ]

In recent years, the knowledge on cytokines has advanced and even if new data are continuously added, we would contribute throwing light upon the multiple functions that these molecules can accomplish. As documented by the contributions here reported, these molecules are described as cytokine-like and cytokines in invertebrates and vertebrates, respectively. Actually, fish represent the first group in which cytokine genes are found. The collected reviews regarding protozoa, invertebrates, vertebrates including man, report on biological activities of these versatile molecules that range over many fields. Cytokine-like and cytokines play several important roles such as chemical secretion (pheromones), development, immune and neuroendocrine responses, wound repair, aging, longevity and so on. Taken together, the reviewed data confirm the surprising similarity between molecules and processes in invertebrates and vertebrates and suggest that basic common features of fundamental biological events are conserved and extended across diverse species, tissues and developmental phases, supporting the general idea that an increasing number of early acquisitions during metazoan evolution are also common in higher vertebrates. In accordance with these concepts we propose as first review of the issue a speculation about phylogeny that could be useful to set the general problem of conservation of molecules and their functioning in the evolutional background. Lanzavecchia's paper [1], starting from historical data, underlines that on the whole biological evolution appears as a series of modulations more or less accentuated by a grouping of genetic information that are maintained rather constant along all the branches of the phylogenetic tree. The studies on the genomes of diverse animals confirm the existence of a relevant molecular conservation and this fundamental conservation of the general genetic patrimony of the living organisms justifies the use of diverse animal forms for the study and comprehension of general biological phenomena, potentially relevant for human health. In the second article, Luporini and coworkers [2] provide data on structure of the Euplotes raikovi, Euplotes octocarinatus, and Euplotes nobilii pheromone family members. These studies have expanded the knowledge of the biological and evolutionary significance of these ancient, cell type-specific signal proteins. Identified and for a long time studied only for their paracrine mating inducing activity, pheromones have now revealed a more universal and primordial function such as autocrine cell stimulation for the vegetative growth revealing intriguing similarities of structure and cross-reactions with members of cytokines evolved by more advanced multicellular organisms. The paper of Franchini et al. [3] outlines the presence and function of TGF-β and PDGF family members in invertebrates, stressing the early appearance of these molecules in evolution. These molecules play an important role in development, in immune and neuroendocrine responses and in wound repair by activating classical transduction pathways. Grimaldi and coworkers' paper [4] focuses on the comparison of angiogenic process in vertebrates and hirudineans subjected to surgical explant or cytokine treatment. The reviewed data confirm the surprising similarities between leech and vertebrate processes in wound healing and suggest that basic common events such as antigenic expressions of endothelial and hemopoietic cells, cytokine secretion and regulation as well as extracellular matrix interactions, are conserved and extended across diverse species, tissues and developmental phases. The article of Salzet et al. [5] emphasizes the different immunodefense strategies that adaptation undertakes during the course of evolution of two classes of annelids i.e. oligochaetes and achaetes. Innate immunity plays a major role as a first defense against microbes. Effectors of the innate response include pattern recognition receptors (PRR), phagocytic cells, proteolytic cascades and peptides/proteins with antimicrobial properties. Each element of these events has been well studied in vertebrates and in some invertebrates such as annelids. From these different researches, it appears that mammalian innate immunity could be considered as a mosaic of invertebrate immune responses. Annelids belonging to the lophotrochozoans' group are primitive coelomates that possess specially developed cellular immunity against pathogens including phagocytosis, encapsulation and spontaneous cytotoxicity of coelomocytes against allogenic or xenogenic cells. They have also developed an important humoral immunity that is based on antimicrobial, hemolytic and clotting properties of their body fluid.....