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Liposomal prednisolone inhibits vascular inflammation and enhances venous outward remodeling in a murine arteriovenous fistula model.

ABSTRACT: Arteriovenous fistulas (AVF) for hemodialysis access have a 1-year primary patency rate of only 60%, mainly as a result of maturation failure that is caused by insufficient outward remodeling and intimal hyperplasia. The exact pathophysiology remains unknown, but the inflammatory vascular response is thought to play an important role. In the present study we demonstrate that targeted liposomal delivery of prednisolone increases outward remodeling of the AVF in a murine model. Liposomes accumulate in the post-anastomotic area of the venous outflow tract in which the vascular pathology is most prominent in failed AVFs. On a histological level, we observed a reduction of lymphocytes and granulocytes in the vascular wall. In addition, a strong anti-inflammatory effect of liposomal prednisolone on macrophages was demonstrated in vitro. Therefore, treatment with liposomal prednisolone might be a valuable strategy to improve AVF maturation.

SUBMITTER: Wong C

PROVIDER: S-EPMC4962038 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Liposomal prednisolone inhibits vascular inflammation and enhances venous outward remodeling in a murine arteriovenous fistula model.

Wong ChunYu C Bezhaeva Taisiya T Rothuizen Tonia C TC Metselaar Josbert M JM de Vries Margreet R MR Verbeek Floris P R FP Vahrmeijer Alexander L AL Wezel Anouk A van Zonneveld Anton-Jan AJ Rabelink Ton J TJ Quax Paul H A PH Rotmans Joris I JI

Scientific reports 20160727

Arteriovenous fistulas (AVF) for hemodialysis access have a 1-year primary patency rate of only 60%, mainly as a result of maturation failure that is caused by insufficient outward remodeling and intimal hyperplasia. The exact pathophysiology remains unknown, but the inflammatory vascular response is thought to play an important role. In the present study we demonstrate that targeted liposomal delivery of prednisolone increases outward remodeling of the AVF in a murine model. Liposomes accumulat ...[more]

PMID: 27460883

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Project description:Following creation, an arteriovenous fistula (AVF) must mature (i.e., enlarge lumen to allow high blood flow) before being used for hemodialysis. AVF maturation failure rates are high, and currently, there are no effective therapy to treat this problem. The maturation process is likely affected by the integrity of the vascular extracellular matrix (ECM). Natural Vascular Scaffolding (NVS) Therapy is a new technology that interlinks collagen and elastin via photoactivation of a locally delivered small molecule (4-amino-1,8-naphtalamide). We hypothesized that NVS Therapy may improve AVF remodeling by preserving ECM integrity. AVFs were created in Wistar male rats by connecting the femoral vein (end) to femoral artery (side) in the same limb. Immediately after blood flow was restored to dilate the femoral vein by arterial pressure, a 10 ?l-drop of the NVS compound (2 mg/ml) was placed on the anastomosis perivascularly. Following 5-min incubation, the NVS treated area was exposed to 1-min illumination by 450-nm light. The control group received 10 ?l-drop of phosphate buffered saline (PBS) and the same light activation. The skin was closed, and rats were euthanized 4 weeks (n = 6-9 per group) post-AVF creation for histology, morphometry, immunohistochemistry (IHC), and multiphoton microscopy for second-harmonic-generation evaluation of collagen fibers. The vascular thickness was similar in both groups. The AVF vein's open lumen area and % open lumen area in NVS-treated rats were significantly larger than in PBS-treated rats (4.2-fold p = 0.014 and 2-fold p = 0.009, respectively). The inflammatory markers IL-6 and MMP-9 in the AVF walls were significantly decreased in the NVS group than the PBS group. Collagen fibers in the vascular wall trended toward perpendicular alignment to the lumen circumference in the NVS-treated AVFs, with more defined shape but less area than in the PBS-treated AVFs. These results indicate that the NVS Therapy exerted changes in collagen, which may influence AVF maturation. Rats tolerated the NVS treatment well, and the lack of cell death by the treatment was confirmed in cell culture experiments. These results suggest that NVS treatment is safe and may have therapeutic potential by facilitating lumen expansion to enhanced AVF maturation in patients.

Project description:Background: Although clinical outcome of arteriovenous fistula (AVF) as a preferred vascular access for hemodialysis has been inadequate, biological mechanisms of AVF maturation and failure is still poorly understood. Since our mouse AVF model recapitulates human AVF maturation and partial failure, we hypothesized that high throughput RNA sequencing (RNA-seq) analysis would identify early changes in gene expression that might predict AVF maturation and failure. Method: Aortocaval fistula creation (AVF group) or sham operation (sham group) was performed with C57BL/6 mice (10 wk). Ultrasound was performed to confirm the AVF patency and to measure hemodynamics. Venous limbs were collected on postoperative day 7 and total RNA was extracted. After Poly-A mRNA libraries were constructed, RNA-seq was performed. Differentially expressed genes (DEG) were identified, and subsequent enrichment analyses of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were performed with bioinformatics techniques. Results: 1057 DEG were identified between the AVF and sham groups. Genes in metabolic pathways were significantly downregulated in the AVF. Since gene expression patterns among the AVF group were significantly heterogenous, the AVF group was divided into 2 groups (‘normal’ AVF group; nAVF and ‘outliers’ group; OUT), and subgroup analyses were performed. Although physiological data of body weight change and hemodynamics were not different between the nAVF and OUT groups, 413 DEG were identified between them. Enrichment analyses showed significant overrepresentation of metabolism, immunity, and coagulation in the OUT group. Comparing the nAVF group with the sham group, 403 DEG were identified. Enrichment analyses showed increase of gene expression related to cell cycle, extracellular matrix, and immunity. Comparing these results with previously published data, the gene expression patterns of the nAVF group was consistent with AVF maturation and adaptive remodeling, whereas the OUT group showed attenuated difference, suggesting the heterogeneity of the AVF group reflects early gene expression changes in the process of AVF maturation and failure. Significant sex differences were not observed in the AVF group. Conclusions: A small subset of AVF undergoes aberrant biological processes in the early phase including diminished ECM remodeling, activated coagulation and upregulated metabolism, that could lead to fistula failure. Detection of these processes might be a viable translational strategy to predict fistula failure and reduce patient morbidity.

Dataset Information

Liposomal prednisolone inhibits vascular inflammation and enhances venous outward remodeling in a murine arteriovenous fistula model.

Publications

Liposomal prednisolone inhibits vascular inflammation and enhances venous outward remodeling in a murine arteriovenous fistula model.

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