The parasite Schistosoma mansoni causes chronic infections in humans, because it can evade host immune defences long-term. Such infections alter the immune response in a manner that prevents the development of various immune-mediated diseases, indicating that molecules produced by schistosomes might be useful as immunomodulatory therapeutic agents. Now, a paper published in The Journal of Experimental Medicine shows that S. mansoni eggs secrete a protein that binds certain chemokines, and administration of this protein inhibits inflammation in several animal models of disease.

Because certain viruses have been shown to produce chemokine-binding proteins (CKBPs) and because infection with S. mansoni affects the local recruitment of immune cells, Philip Smith and colleagues examined whether S. mansoni produces CKBPs. Secretions from live eggs (produced by adult worms, which reside in the intestinal blood vessels of infected individuals) were shown to bind the chemokines CXC-chemokine ligand 8 (CXCL8; also known as IL-8) and CC-chemokine ligand 3 (CCL3). A single protein was found to provide this activity, and the gene that encodes this protein was cloned. A recombinant form of this novel CKBP was then shown not only to bind specific chemokines but also to prevent these chemokines from interacting with their receptors, thereby inhibiting the migration and activation of leukocytes that express the cognate chemokine receptors (particularly neutrophils, but also macrophages and eosinophils).

This is the first report of a human pathogen that produces a CKBP. The authors suggest that, because of its potent anti-inflammatory activity, S. mansoni CKBP has potential as a treatment for acute inflammation. This is supported by data from three in vivo models of acute inflammation that show that intravenous administration of recombinant S. mansoni CKBP suppresses leukocyte infiltration.