Cellular crosstalk between endothelial and vascular smooth muscle cells via the BACH1/COL3A1 axis promotes vascular calcification in chronic kidney disease.

BACKGROUND

High phosphate levels lead to significant pathological changes in vascular smooth muscle cells (VSMCs) and endothelial cells, driving vascular disease in chronic kidney disease (CKD). Endothelial cell senescence plays a major role in this process, promoting vascular calcification by fostering a pro-inflammatory and pro-osteogenic environment. Interaction between VSMCs and endothelial cells further accelerates calcification, although the precise mechanisms remain incompletely understood.

METHODS

Exosomes were isolated and characterized, with RT-qPCR, western blot, immunohistochemistry (IHC), and immunofluorescence (IF) assays used to confirm gene and protein expression. Chromatin immunoprecipitation (ChIP) and dual-luciferase assays were conducted to assess interactions between BACH1 and COL3A1. A 5/6 nephrectomy-induced CKD mouse model was established, and Alizarin Red S staining, Von Kossa staining, calcium content measurement, and ALP activity assays were performed to assess vascular calcification and osteogenic differentiation.

RESULTS

Knocking down BACH1 reduced high phosphate-induced senescence in endothelial cells and suppressed TNF-α-induced EndMT in these cells. BACH1 also enhanced COL3A1 expression by activating its transcription. Endothelial cell-derived COL3A1 was associated with exosomes, and HAoEC-derived exosomes were internalized by VSMCs, thereby promoting calcification-related phenotypes in VSMCs. In vivo, systemic COL3A1 knockdown attenuated CKD-associated vascular calcification, EndMT-like changes, and senescence.

CONCLUSION

In summary, BACH1 regulates COL3A1, facilitating communication between endothelial cells and VSMCs through exosomes, thereby promoting vascular calcification in CKD. These findings highlight that targeting the BACH1-COL3A1 axis and exosome-mediated endothelial-VSMC communication may represent a potential therapeutic strategy.