5-Methoxytryptophan improves cerebrovascular injury induced by chronic kidney disease through NF-κB pathway.

5-Methoxytryptophan (5-MTP), a candidate biomarker for chronic kidney disease (CKD), has an undefined role in cerebrovascular pathophysiology. To investigate this, we employed a folic acid (FA)-induced CKD to simulate cerebrovascular complications in vivo. Additionally, in vitro models of cerebral ischemia and cerebrovascular endothelial cell injury were established. 5-MTP was administered to rats and cells, along with nuclear factor-κB (NF-κB) expression. The pathological characteristics of kidney and brain tissue were observed by histological staining. Cell proliferation was assessed using the Cell Counting Kit 8, while tube formation and migration were examined using tube formation and wound healing assays. Cell apoptosis was detected using both TdT-mediated dUTP-biotin nick end labeling and flow cytometry. Levels of renal injury markers, blood biomarkers of cerebrovascular disease, and inflammatory cytokines were measured using biochemical assays. Quantitative real-time PCR and Western blot were used to detect the mRNA and protein expression, respectively. Key findings revealed that FA successfully induced CKD in rats, which subsequently exacerbated cerebrovascular dysfunction. 5-MTP reduced the levels of proteinuria, N-acetyl-beta-D-glucosaminidase, nephrin, endothelin-1, von Willebrand factor, and thrombomodulin; improved the degree of renal fibrosis and structural damage to the brain tissue; and inhibited cell apoptosis in rats. In vitro, 5-MTP promoted cell proliferation, tube formation, migration, and the upregulation of B-cell lymphoma-2 and caspase-3 expression. This treatment also led to an increase in interleukin (IL)-10 levels while suppressing cell apoptosis, Bcl-2-associated X protein (Bax), and cleaved caspase-3 expression. Furthermore, it reduced the IL-6 and tumor necrosis factor-alpha levels. NF-κB overexpression reversed the effects of 5-MTP in vitro and in vivo. Our results demonstrate that 5-MTP ameliorated CKD-induced cerebrovascular injury through the NF-κB pathway, indicating its potential as an innovative and efficacious therapeutic target for CKD-induced cerebrovascular dysfunction.