Research of inflammatory markers in the medicinal leech, Hirudo medicinalis

The leech Hirudo medicinalis is an interesting model to study inflammatory processes both in nervous system and in peripheral tissues. Here we considered two different molecules involved in peripheral tissues as well as neural immune response: the Macrophage Migration Inhibitory Factor (MIF), a chemotactic cytokine which mediate LPS-induced responses, and the Glia Maturation Factor Gamma (GMFG), a member of ADF-gelsolin superfamily, which seems to be involved in actin cytoskeleton remodelling and TLR4 endocytic pathway in response to LPS. We identified in H. medicinalis two genes coding for products showing high similarity with MIF and GMFG of Vertebrates, respectively. Immunolocalization experiments show a weak expression of both these proteins in the leech CNS whereas a stronger signal is detected in peripheral tissues macrophages. Further studies are needed to assess the expression levels of these molecules in leech tissues. However, this work shows that these molecules are good selective markers of activated macrophages in H. medicinalis, confirming the close correlation between the leech and vertebrates. Moreover, these results suggest the possible presence of more well-conserved molecules across evolution and represent an interesting starting point to analyze the complex crosstalk occurring during the innate immune response as well as the neuroimmunity processes.