Small Neutralizing Molecules to Inhibit Actions of the Chemokine CXCL12

Muriel Hachet‐Haas ,Ken Y.C Chow,Nelly Frossard,Jacques Haiech,Patrick Gizzi,Marcel Hibert,Rania Dagher,François Rohmer,Bernard Lagane,Françoise Baleux,Sandra Lecat,Christel Franchet,Karl Balabanian,Marc Parmentier,Bruno Didier,Esther Kellenberger,Fernando Arenzana-Seisdedos,Ferrán Pons ,Dominique Bron ,Jean‐Luc Galzi

doi:10.1074/jbc.m803947200

Abstract

The chemokine CXCL12 and the receptor CXCR4 play pivotal roles in normal vascular and neuronal development, in inflammatory responses, and in infectious diseases and cancer. For instance, CXCL12 has been shown to mediate human immunodeficiency virus-induced neurotoxicity, proliferative retinopathy and chronic inflammation, whereas its receptor CXCR4 is involved in human immunodeficiency virus infection, cancer metastasis and in the rare disease known as the warts, hypogammaglobulinemia, immunodeficiency, and myelokathexis (WHIM) syndrome. As we screened chemical libraries to find inhibitors of the interaction between CXCL12 and the receptor CXCR4, we identified synthetic compounds from the family of chalcones that reduce binding of CXCL12 to CXCR4, inhibit calcium responses mediated by the receptor, and prevent CXCR4 internalization in response to CXCL12. We found that the chemical compounds display an original mechanism of action as they bind to the chemokine but not to CXCR4. The highest affinity molecule blocked chemotaxis of human peripheral blood lymphocytes ex vivo. It was also active in vivo in a mouse model of allergic eosinophilic airway inflammation in which we detected inhibition of the inflammatory infiltrate. The compound showed selectivity for CXCL12 and not for CCL5 and CXCL8 chemokines and blocked CXCL12 binding to its second receptor, CXCR7. By analogy to the effect of neutralizing antibodies, this molecule behaves as a small organic neutralizing compound that may prove to have valuable pharmacological and therapeutic potential.

Highlights

Chemokines are small (8 –10-kDa) secreted proteins that play roles in the normal physiology of the immune system as well as in orchestrating leukocyte recruitment and activation in the context of inflammatory and infectious diseases [1]
Searching for Small Compounds That Could Inhibit the Interaction of the Chemokine CXCL12 with Its CXCR4 Receptor— We screened 3,200 molecules from the collection of the medicinal chemistry laboratories from Strasbourg University in a fluorescent binding assay on whole living cells described previaction of CXCL12 with the CXCR4
Chalcone 4 Inhibits Chemotactic Responses to CXCL12—In contrast to other known antagonists of CXCR4 receptors, such as T134, P2G-CXCL12, or AMD3100 (26 –28), we found that chalcone 4 does not inhibit infection of human CD4ϩ CXCR4ϩ T lymphocytes by HIV in an assay carried out as described previously [29]

Summary

Chemokine Neutraligands

The chemokine receptor CXCR4 serves as a coreceptor to HIV type 1 to infect T cells [12]. Considering both qualitative and quantitative aspects of the involvement of the CXCR4/CXCL12 pair in the above mentioned physiological and pathological functions on the one hand and the limited number of pharmacological tools to investigate their function or to correct for defects in their functioning, we set up a screening program to identify new molecules interfering with the binding of CXCL12 to the receptor CXCR4. We describe the discovery of a new class of pharmacologically active molecules that bind to the chemokine itself and neutralize its biological activity in a way similar to that of neutralizing antibodies

EXPERIMENTAL PROCEDURES

RESULTS

Total cells

DISCUSSION