IS and TSP1 promote VSMC senescence through CD47-dependent ERK1/2 and AhR signalling, and CD47 deletion protects against CKD-induced vascular remodelling, suggesting that CD47 blockade may represent a novel therapeutic strategy to mitigate vascular complications in CKD.
Key Findings
Results
Indoxyl sulphate (IS) increased TSP1 expression in human aortic vascular smooth muscle cells (hVSMCs).
Human aortic VSMCs were exposed to IS to assess TSP1 expression changes.
TSP1 expression was measured by immunohistochemistry and molecular analyses.
This effect was attenuated by CD47 blockade.
TSP1 protein and CKD plasma also independently increased TSP1 expression in hVSMCs.
Results
IS, TSP1, and CKD plasma reduced proliferation and elevated β-galactosidase activity in hVSMCs, indicating induction of cellular senescence.
β-galactosidase activity is a marker of cellular senescence.
Both IS and TSP1 treatments produced these effects in human aortic VSMCs.
CKD plasma further enhanced IS- and TSP1-induced senescence.
These senescence-associated effects were attenuated by CD47 blockade.
Results
IS, TSP1, and CKD plasma activated phosphorylated ERK1/2 and cytoplasmic aryl hydrocarbon receptor (AhR) in hVSMCs.
Phosphorylated ERK1/2 (pERK1/2) activation was observed following IS, TSP1, and CKD plasma exposure.
Cytoplasmic aryl hydrocarbon receptor (AhR) was also activated under these conditions.
These signalling effects were attenuated by CD47 blockade.
This identifies CD47-dependent ERK1/2 and AhR signalling as the mechanistic pathway for VSMC senescence.
Results
5/6 nephrectomy induced aortic wall thickening in wild-type (WT) mice but not in CD47-deficient (CD47KO) mice.
CKD was induced using 5/6 nephrectomy in both WT and CD47KO mice.
Vascular changes were assessed by histology and immunohistochemistry.
Aortic wall thickening, indicative of vascular remodelling, was present in WT CKD mice but absent in CD47KO CKD mice.
This demonstrates that CD47 deletion confers protection against CKD-induced vascular remodelling in vivo.
Results
Aortic pERK1/2 was reduced in CD47KO mice despite persistent TSP1 upregulation following 5/6 nephrectomy.
In CD47KO mice subjected to 5/6 nephrectomy, TSP1 remained upregulated in aortic tissue.
Despite TSP1 upregulation, aortic pERK1/2 levels were reduced in CD47KO compared to WT mice.
This finding suggests that CD47 is required for TSP1-mediated downstream ERK1/2 signalling in vivo.
The dissociation between TSP1 expression and pERK1/2 activation in CD47KO mice supports the role of CD47 as a signalling intermediary.
Background
TSP1 and CD47 have been implicated in vascular pathology, but their role in CKD-associated vascular remodelling was previously unknown.
CKD accelerates vascular dysfunction and cardiovascular disease partly through accumulation of the uraemic toxin indoxyl sulphate (IS).
TSP1 and its receptor CD47 were known to be involved in vascular pathology prior to this study.
This study is the first to investigate the contribution of TSP1-CD47 signalling to VSMC dysfunction specifically in the context of CKD.