High Phosphate and Low Protein Mediate Arterial and Cutaneous Vascular Calcification in CKD Mice

KEY POINTS: A high-phosphate and low-protein combination diet induced medial artery calcification, cutaneous vascular calcification, and kidney fibrosis in CKD mice. p38 mitogen-activated protein kinase signaling was highly activated in CKD mice fed a high-phosphate and low-protein diet. Pharmacologic p38 mitogen-activated protein kinase inhibition reduced vascular calcification and kidney fibrosis, suggesting a novel treatment for patients with CKD. BACKGROUND: Medial artery calcification and cutaneous arteriolar calcification are prevalent in patients with CKD and are strongly associated with higher morbidity and mortality. Current experimental CKD models, however, often fail to fully replicate the patterns of medial artery calcification and cutaneous arteriolar calcification, limiting our ability to elucidate their underlying molecular pathways. Developing a reliable experimental model for CKD-associated calcification and using it to identify therapeutic targets is essential for advancing treatment strategies for these vascular complications. In this study, we used a novel strategy that incorporated a high-phosphate and low-protein (HPi-Lp) diet to promote medial artery and cutaneous vascular calcification in CKD mice. METHODS: Mice underwent five-sixths (5/6) nephrectomy and were then fed various diets. Vascular calcification was assessed using micro-computed tomography scans, Alizarin Red staining, Von Kossa staining, and calcium assays. Kidney impairment and fibrosis were also evaluated. RNA sequencing analysis was performed to identify key molecular pathways. The pharmacologic inhibitor SB203580 was used to determine the significance of p38 mitogen-activated protein kinase (MAPK) signaling in vivo . RESULTS: The HPi-Lp diet markedly induced both medial artery and cutaneous vascular calcification in 5/6 nephrectomized mice while exacerbating kidney dysfunction and fibrosis. The p38 MAPK signaling was specifically highly activated. Pharmacologic inhibition of p38 MAPK signaling significantly reduced medial artery and cutaneous vascular calcification as well as associated kidney fibrosis. CONCLUSIONS: The 5/6 nephrectomy CKD mouse model combined with a HPi-Lp diet effectively replicated medial artery and cutaneous arteriolar calcification.