Hypoxia-inducible factors in arteriovenous fistula maturation: A prospective cohort study

Metabolomics revealed pharmacodynamic effects of aspirin and indobufen in patients after percutaneous transluminal angioplasty surgery

Introduction

Aspirin and indobufen are commonly used therapeutic drugs for the prevention of vascular restenosis (VR) after percutaneous transluminal angioplasty surgery. They both exhibited antiplatelet effects but molecular mechanisms underlying metabolic changes induced by them remain unclear.

Methods

In this study, we collected plasma samples from patients on aspirin medication (n = 5), patients on indobufen medication, patients with no medication after PTA, and healthy controls (CKs) (n = 5). Our investigation aimed to reveal the metabolic processes in patients during vascular restenosis and its amelioration through drug therapy using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results

Our data showed significant alterations in amino acid and choline metabolism in patients without medication after PTA. Aspirin and indobufen were able to regulate these metabolic pathways to alleviate VR symptoms. We identified several characteristic amino acids, including pro-leu, L-citrulline, his-glu, and L-glutamate, as important biomarkers for VR assessment in patients without medication after PTA. A total of 17 and 4 metabolites involved in arginine and phenylalanine metabolism were specifically induced by aspirin and indobufen, respectively. Their expression levels were significantly regulated by aspirin or indobufen, nearly reaching normal levels.

Discussion

Taken together, our identification of metabolites involved in metabolic changes affected by aspirin and indobufen medication enhances the understanding of VR pathology after PTA. This may help identify early diagnostic biomarkers and therapeutic targets.

Sex hormones impact early maturation and immune response in the arteriovenous fistula mouse model

Arteriovenous fistulae (AVF) fail to mature more frequently in female patients compared with male patients, leading to inferior outcomes and decreased utilization. Since our mouse AVF model recapitulates sex differences in human AVF maturation, we hypothesized that sex hormones mediate these differences during AVF maturation. C57BL/6 mice (9-11 wk) were treated with aortocaval AVF surgery and/or gonadectomy. AVF hemodynamics were measured via ultrasound (days 0-21). Blood was collected for FACS and tissue for immunofluorescence and ELISA (days 3 and 7); wall thickness was assessed by histology (day 21). Inferior vena cava shear stress was higher in male mice (P = 0.0028) after gonadectomy, and they had increased wall thickness (22.0 ± 1.8 vs. 12.7 ± 1.2 µm; P < 0.0001). Conversely, female mice had decreased wall thickness (6.8 ± 0.6 vs. 15.3 ± 0.9 µm; P = 0.0002). Intact female mice had higher proportions of circulating CD3+ T cells on day 3 (P = 0.0043), CD4+ (P = 0.0003) and CD8+ T cells (P = 0.005) on day 7, and CD11b+ monocytes on day 3 (P = 0.0046). After gonadectomy, these differences disappeared. In intact female mice, CD3+ T cells (P = 0.025), CD4+ T cells (P = 0.0178), CD8+ T cells (P = 0.0571), and CD68+ macrophages (P = 0.0078) increased in the fistula wall on days 3 and 7. This disappeared after gonadectomy. Furthermore, female mice had higher IL-10 (P = 0.0217) and TNF-α (P = 0.0417) levels in their AVF walls than male mice. Sex hormones mediate AVF maturation, suggesting that hormone receptor signaling may be a target to improve AVF maturation.NEW & NOTEWORTHY After arteriovenous fistula creation, females have lower rates of maturation and higher rates of failure than males. In a mouse model of venous adaptation that recapitulates human fistula maturation, sex hormones may be mechanisms of the sexual dimorphism: testosterone is associated with reduced shear stress, whereas estrogen is associated with increased immune cell recruitment. Modulating sex hormones or downstream effectors suggests sex-specific therapies and could address disparities in sex differences in clinical outcomes.

Pathological analysis of vascularization of the arterialized veins in failed arteriovenous fistulas among uremic patients

PURPOSE

To assess venous wall vascularization and its correlation with neointimal hyperplasia (NIH) in failed arteriovenous fistulas (AVFs).

METHODS

A total of 43 uremic patients who received a first AVF creation and 39 patients who received reconstruction of failed fistulas were enrolled in the study. A 5-10 mm vein segment adjacent to future fistula creation or reconstruction site was surgically removed and assessed using histopathological analyses and stained by immunohistochemistry to quantify vasa vasorum density (VVD).

RESULTS

Both the intimal thickness (70.68 [28.81-99.54] vs. 4.53 [2.69-7.30] μm, P < 0.001) and the intimal thickness/medial thickness ratio (2.20 [0.77-4.36] vs. 0.15 [0.10-0.30], P < 0.001) were higher in failed AVFs than in pre-access veins. CD31 and factor VIII marked VVDs both in the intima (6.31 [1.62-12.53] vs. 0.0 [0.0-0.0], P < 0.001; 7.82 [3.33-11.61] vs. 0.0 [0.0-0.0], P < 0.001) and media (10.0 [7.59-12.95] vs. 3.71 [2.44-4.87], P < 0.001; 8.33 [5.55-13.0] vs. 3.57 [2.53-4.82], P < 0.001), and the intimal VVD/medial VVD ratio (0.67 [0.19-1.08] vs. 0.0 [0.0-0.0], P < 0.001; 0.71 [0.39-1.14] vs. 0.0 [0.0-0.0], P < 0.001) were significantly higher in failed AVFs than in pre-access veins. There was also a positive relationship between the intimal VVD/medial VVD ratio and the intimal thickness/medial thickness ratio (P < 0.001). In addition, compared to pre-access veins, vascular endothelial cell growth factor-A (VEGF-A) expression was higher in failed AVFs.

CONCLUSIONS

Vascularization of the vessel wall was noticeably more developed in the arterialized veins, especially among the NIH regions in failed AVFs.