Neutralizing Nanobodies Targeting Diverse Chemokines Effectively Inhibit Chemokine Function*
Background: Chemokines play a prominent role in inflammatory diseases. Results: Nanobodies targeting chemokines display high affinity and potently neutralize chemokine-induced receptor binding and signaling. Conclusion: Neutralizing Nanobodies targeting chemokines effectively inhibit chemokine function. Significance: Nanobodies directed against inflammatory and homeostatic chemokines form a promising new class of potent and specific inhibitors of chemokine function, to be used for research and therapeutic purposes. Chemokine receptors and their ligands play a prominent role in immune regulation but many have also been implicated in inflammatory diseases such as multiple sclerosis, rheumatoid arthritis, allograft rejection after transplantation, and also in cancer metastasis. Most approaches to therapeutically target the chemokine system involve targeting of chemokine receptors with low molecular weight antagonists. Here we describe the selection and characterization of an unprecedented large and diverse panel of neutralizing Nanobodies (single domain camelid antibodies fragment) directed against several chemokines. We show that the Nanobodies directed against CCL2 (MCP-1), CCL5 (RANTES), CXCL11 (I-TAC), and CXCL12 (SDF-1α) bind the chemokines with high affinity (at nanomolar concentration), thereby blocking receptor binding, inhibiting chemokine-induced receptor activation as well as chemotaxis. Together, we show that neutralizing Nanobodies can be selected efficiently for effective and specific therapeutic treatment against a wide range of immune and inflammatory diseases.