Effects of microbiota on defense system of earthworms

Earthworms are important soil invertebrate organisms that participate in nutrient cycling in terrestrial ecosystems and in the formation of the soil profile from the physical, chemical and also microbial point of view. Soils are considered the most microbially diverse environments on earth. All invertebrates living in soil therefore need to possess a complex immune system. Earthworms are used as a model organism in immunology for decades. Their simple body plan consists of two main body cavities: true coelom and digestive tube. Both coelomic cavity and digestive tract represent open systems with permanent contact with soil microorganisms. Eisenia andrei species is used as a standard immunological model in our laboratory for many years. E andrei earthworms live in compost, microbially abundant environment, which is reflected in their well-developed immune system. Some new mechanisms of E. andrei defense system are described in this work. Two novel pattern recognition receptors (PRRs), Toll-like receptor (TLR) and lipopolysaccharide binding protein/bactericidal permeability-increasing protein (LBP/BPI) were characterized in earthworms. These molecules are expressed in coelomocytes and their production is upregulated after microbial challenge. Moreover, both receptors were detected in digestive tract..