New interpretation of vasculitis in the light of evolution

Vasculitis may be the result of an evolution-conserved physiological function to clean the circulation of germs, drugs, and immune-complexes. As polymorphonuclear leukocytes migrate out of vessels loaded with insult (transcellular route), damage to the endothelial cells causes vasculitis. This process is dictated by genes conserved from the ancestor of the phagocytes that play a key role in innate immunity. These ancient inflammatory functions (phagocytosis, diapedesis, toll receptors, cleansing) are already present in the migrating slug amoebas and continue to evolve in the coelomocytes of echinoderms, invertebrate animals without a circulation. I will suggest that a diverse group of vasculitic disease entities, with similar histologic patterns of vascular inflammation, are the result of this mechanism, inherited from the social amoebae and invertebrate echinoderms at the very base of the deuterostome lineage.