Common evolutionary origin of the immune and neuroendocrine systems: from morphological and functional evidences to in silico approaches

Ten years ago, we surmised that there was a commonevolutionary origin for the immune and neuroendocrinesystems. This was based on morphological and functionalresults indicating that a common pool of moleculesis shared by the two systems, both ininvertebrates and vertebrates. In the past decade,numerous molecular biology experiments have confirmedsequence similarity between invertebrate andvertebrate neuroimmune mediators, such as corticotrophin-releasing hormone. However, sequence similaritybasedapproaches were inadequate for analyzing otherimmune-related molecules, such as helical cytokines.This review covers older, and more recent findings oninvertebrate immune- and neuroendocrine-related moleculeswith an evolutionary perspective, and suggeststhat protein-folding recognition algorithms are a fundamentaltool in understanding the evolution of immuneandneuroendocrine-related molecules.