The host-parasite neuroimmunoendocrine network in schistosomiasis: consequences to the host and the parasite

The physiological interactions during the course of any immune response are complex. Infection induces antigen-specific recognition by the immune system, which is consequently charged with the responsibility of marshalling the appropriate effector responses necessary to destroy the pathogen, or at the very least inhibit its progression. Obviously, the immune system should accomplish this while minimizing collateral damage to the host or it risks, winning a Pyrrhic victory. As our understanding of the neuroendocrine system grows, it has become increasingly clear that this complex network of neurotransmitters, hormones and cytokines plays an important role in mediating immunity. Schistosomes present an especially complex relationship between pathogen and these physiological systems, with hormonally dependent host factors such as sex and age correlated with parasite success. In this report, we review the current literature on sex and age associations between infection and progression of disease. We then follow with a discussion on interactions between the host neuroendocrine and immune systems. We also speculate on strategies to apply this knowledge to novel treatment strategies. Results argue for a complex network comprising the immune, endocrinological and nervous systems of both host and schistosome in the regulation of the plural outcomes of infection.