BX-471

Spinal cord injury (SCI) leads to severe and lasting impairments in motor and sensory functions. The intense inflammatory response following SCI is a significant challenge, and autophagy has emerged as a key factor in the recovery process. The C-C chemokine receptor type 1 (CCR1), a G-protein coupled receptor, plays a crucial role in managing the chemokine response under stress. BX471, a selective and potent CCR1 antagonist, has been explored in various disease contexts for its therapeutic potential. In this study, we assessed the effects of BX471 in a mouse model of SCI. The treatment was administered at doses of 3 and 10 mg/kg, 1 h and 6 h after the injury occurred. Results showed that BX471 significantly improved tissue structure by positively influencing autophagy and reducing inflammation. Inflammatory markers, including CCR1 ligands RANTES, MIP-1α, TNF-α, and IL-1β, were measured using Western blot analysis. Additionally, histological evaluations revealed that BX471 effectively decreased infiltration and reduced astrocyte and microglial activation, supporting the idea that enhancing autophagy through CCR1 inhibition could promote neuronal survival. The highest efficacy was observed at the 10 mg/kg dose, leading to optimal out-comes across the assessments. These findings suggest that CCR1 blockade with BX471 may offer a promising therapeutic strategy for SCI, addressing a critical gap in the current pharmacological treatment options.

To study the effect of CCR1 and its ligands on macrophage polarization and evaluate its effect on chondrocytes in relieving the progression of osteoarthritis.

RAW cells were polarized to M1/M2 subtype, and then different concentrations of BX471 were added to selectively inhibit CCR1. The polarization of the cells was detected by RT-qPCR, immunofluorescence and flow cytometry. CCL5 and CCL7 genes were silenced by SiRNA and its role in macrophage polarization was analyzed. Macrophage conditioned medium was further used to stimulate chondrocytes. Histological observation was carried out on models of medial meniscus (DMM) with or without BX471 treatment.

We found that blocking of CCR1 and silencing of its ligand, CCL5 and CCL7, reduced the polarization of M1 macrophages. In terms of mechanism, we found that blocking CCR1 could reduce the activation of NF-κB pathway and inhibit the phosphorylation of IKK, IκBα and P65. In addition, blocking of CCR1 could also reduce cartilage injury induced by macrophage conditioned medium. In vivo, blocking of CCR1 reduced the infiltration and accumulation of M1 macrophages and alleviated articular cartilage injury.

CCL5/CCL7-CCR1 axis was involved in macrophage polarization, and blocking it could reduce synovitis and alleviate the process of OA.