Authors
M Majer1; B Šmídová1; T Macháček1; P Horák1; 1 Charles University, Prague, Czech Republic Discussion
Autoimmune diseases and allergies afflict the human population with persistent incidences. A growing body of research shows the beneficial role of helminths and their products in the course of such diseases. However, the avian schistosomes of the genus Trichobilharzia spp. have been overlooked despite their worldwide occurrence and frequent human infections in temperate areas. Indeed, they cause cercarial dermatitis (or swimmer’s itch), which is regarded as an emerging disease. In humans, most of the parasites are believed to die in the skin, which is accompanied by eosinophilia and a strong Th2 milieu, especially after repeated exposure. However, extensive somatic migration has been recorded in experimentally infected mice. It is often associated with signs of parasite immunomodulatory actions employed to reduce the host damage. For example, T. regenti migrates through the central nervous system, and we observed remarkable induction of anti-inflammatory M2 phenotype in the infected spinal cord. Furthermore, we noticed diminished IL-17 production by splenocytes which raises the question of whether T. regenti antigens could improve the progression of the experimental autoimmune encephalomyelitis. It is a mouse model of multiple sclerosis characterised by pathological Th17 response. Another example might be T. szidati which migrates via the lungs, but only mild pathology without pronounced eosinophilia is observed. Hence, T. szidati could contain antigens able to alleviate the pathology observed during, e.g., asthma. On the other hand, the interaction between asthma and cercarial dermatitis (regarded as a skin allergy) should also be examined due to the possible detrimental interference of both conditions. Taken together, Trichobilharzia species should be considered as novel and relevant-to-human models in the field of helminth-induced immunomodulation. Importantly, they might be a source of immunomodulators precisely designed to prevent immunopathology in the nervous or lung tissues. 
