Localization of interleukin-1ß mRNA in the cerebral ganglion of the protochordate, Styela plicata

There is evidence that interleukin 1β (IL-1β) plays an important role in several biological functions in mammals where it is synthesized by cells of haematological, dermal and neural origin. Moreover, production of cytokine-like molecules has been demonstrated in some blood cells of non-mammalian vertebrates and invertebrates in which also nerve cells are demonstrated to be IL-1β immunoreactive. The purpose of the present study is to demonstrate the IL-1β mRNA expression in nerve cells of the ascidian Styela plicata by use of non-isotopic in situ hybridization technique. The expression of IL-1β messenger was demonstrated in monopolar neurons in the cortical layer of the cerebral ganglion. The neuronal expression of cytokine-like molecules in tunicates suggests that IL-1β is an ancestral and functionally conserved molecule, and that a neuroimmune axis appeared early during the metazoan phylogeny.