Deciphering the molecular interactions between monocyte chemoattractant protein and its potential inhibitor suramin

Chemokines, in coordination with glycosaminoglycans (GAGs) and G protein-coupled receptors (GPCRs), play a critical role in regulating inflammatory responses. Among these, monocyte chemoattractant protein-1, also known as CCL2 stands out for its role in coordinating with other immune molecules to direct macrophage migration, infiltration, and recruitment to inflamed tissues, highlighting this pathway as a promising target for therapeutic intervention. In the present study, suramin, a polysulfonated napthylurea compound, having structure similarity with heparin, initially developed therapeutic for treating Human African Trypanosomas [HAT] was analyzed for its repressive action against CCL2 arbitrated macrophage migration. The study delves into the binding interaction between suramin (SUR) and CCL2 monomer, elucidating the molecular and biophysical underpinnings of their interaction through various techniques, including isothermal calorimetry, fluorescence spectroscopy, fluorescence lifetime studies, CD spectroscopy, and 2D NMR spectroscopy. Additionally, in-silico mechanistic studies employing molecular dynamic simulations, MMPBSA, and decomposition analysis unravel the intricacies of CCL2-SUR interactions. The molecule is observed to be attenuating the migration of macrophages by interacting with nanomolar affinity (119 ± 11 nM) on the CCL2 with the region overlapping with the CCR2/GAG binding pocket. Thus, this study comprehensively identified suramin, as a possible GAG mimetic for scheming structure-based drug molecules exhibiting anti-inflammatory action by aiming the CCL2-CCR2-GAG axis.