SjE16.7 activates macrophages and promotes Schistosoma japonicum egg-induced granuloma development.

SjE16.7 is an egg-specific protein from Schistosoma japonicum that recruits neutrophils and initiates an inflammatory granuloma response in host tissue. However, since macrophages are known to be important regulators of egg granuloma formation we investigated the effect of SjE16.7 on this cell type. Here we report that SjE16.7 is a potent macrophage activator, inducing macrophage chemotaxis and stimulating cytokine production. Treatment of murine primary macrophages with SjE16.7 resulted in upregulation of both pro- and anti-inflammatory cytokines (IL-10, IL-12, IL-6 and TNF-α), as well as phosphorylation of mitogen-activated protein kinases (MAPKs). Moreover, SjE16.7 treatment increased MHC Class II expression on the surface of macrophages. Importantly, in vivo blockade of SjE16.7 significantly reduced egg-induced pathology, as a result of decreased leucocyte infiltration and reduced granuloma size. Our results suggest that SjE16.7 is an important pathogenic factor and a potential treatment target for this disease.