Comparative analysis of endocytosis: uptake mechanisms of biological and artificial particles by earthworm and human immunocytes

Abstract

Due to evolutionary conserved innate immune mechanisms between invertebrates and vertebrates, invertebrate immunocytes are hypothesized to be functionally similar to human macrophages. Hence, in our research, we aimed to compare the endocytosis pathways used by invertebrate macrophages (earthworm coelomocytes) and vertebrate phagocytes (human THP1 cells) for uptake of particles of biological (bacteria) and synthetic (nanoparticles) origin. In the first part of the thesis we identify and compare endocytosis pathways involved in Escherichia coli and Staphylococcus aureus uptake by human and earthworm immunocytes applying various endocytosis inhibitors. Moreover, we investigated the mRNA expressions of immune receptor-related molecules and bacteria/lysosomes colocalization after uptake inhibition. We found that during bacterial uptake both earthworm and human cells share the evolutionary conserved actin-dependent phagocytosis mechanism, which was inhibited by preincubation of cells with cytochalasins B and D. Decreased numbers of colocalized lysosomes/bacteria supported these findings. Our data strengthen the hypothesis about the conserved phagocyte-like functions of earthworm coelomocytes as possible functional similarities of human myeloid cells.