Targeting B7-H3 attenuates uremic vascular calcification by suppressing phenotypic switching of VSMCs and regulating VSMCs-macrophage crosstalk

Abstract

Objective: This study aimed to investigate the role of B7-H3-an immune checkpoint implicated in inflammation and vascular remodeling-in uremic vascular calcification (UVC), particularly its effects on calcium deposition, vascular smooth muscle cell (VSMC) phenotype, and VSMC-macrophage crosstalk.

Methods: An in vitro UVC model was established using β-glycerophosphate (β-GP) treated human aortic VSMCs (HA-VSMCs). B7-H3 expression was silenced using siRNA. Calcification was assessed by Alizarin Red S staining, ALP activity, and calcium content assays. VSMCs phenotype switching was evaluated by Western blot for contractile and osteogenic markers. Macrophage recruitment, adhesion, and polarization (M1/M2) were assessed using THP-1 cells in co-culture systems and analyzed by qRT-PCR and flow cytometry. The effect of macrophage polarization on VSMCs calcification was investigated in the presence or absence of B7-H3 knockdown.

Results: β-GP treatment induced HA-VSMC calcification, osteogenic differentiation, and upregulated B7-H3 expression. Silencing B7-H3 attenuated calcification, restored contractile markers, and reduced osteogenic markers in VSMCs. B7-H3 knockdown also suppressed the recruitment and adhesion of macrophages to HA-VSMCs, inhibited M1 polarization of co-cultured macrophages, and promoted their shift toward the M2 phenotype. Furthermore, silencing B7-H3 mitigated M1 macrophage-induced VSMC calcification and enhanced the protective effects of M2 macrophages.

Conclusion: B7-H3 promotes UVC directly by inducing osteogenic transformation of VSMCs and indirectly by enhancing macrophage recruitment and favoring pro-calcific M1 polarization. Thus, targeting B7-H3 may represent a promising therapeutic strategy to mitigate UVC.

Keywords: B7-H3; Osteogenic transdifferentiation; Uremia; Vascular calcification; Vascular smooth muscle cells.