Rosuvastatin improves vascular function of arteriovenous fistula in a diabetic rat model

Elevated Leukocyte Glucose Index Is Associated with Long-Term Arteriovenous Fistula Failure in Dialysis Patients

(1) Background: Arteriovenous fistula (AVF) is the preferred type of vascular access for dialysis in patients with end-stage kidney disease (ESKD). However, the primary patency of AVF at one year is under 70% due to several risk factors and comorbidities. Leukocyte glucose index (LGI), a new biomarker based on blood leukocytes and glucose values, has been found to be associated with poor outcomes in cardiovascular disease. The aim of this study is to analyze the impact of LGI on the long-term primary patency of AVF following dialysis initiation. (2) Methods: We conducted a retrospective observational study in which we initially enrolled 158 patients with ESKD admitted to the Vascular Surgery Department of the Emergency County Hospital of Targu Mures, Romania, to surgically create an AVF for dialysis between January 2020 and July 2023. The primary endpoint was AVF failure, defined as the impossibility of performing a chronic dialysis session due to severe restenosis or AVF thrombosis. After follow-up, we categorized patients into two groups based on their AVF status: "functional AVF" for those with a permeable AVF and "AVF failure" for those with vascular access dysfunction. (3) Results: Patients with AVF failure had a higher prevalence of atrial fibrillation (p = 0.013) and diabetes (p = 0.028), as well as a higher LGI value (1.12 vs. 0.79, p < 0.001). At ROC analysis, LGI had the strongest association with the outcome, with an AUC of 0.729, and an optimal cut-off value of 0.95 (72.4% sensitivity and 68% specificity). In Kaplan-Meier survival analyses, patients in the highest tertile (T3) of LGI had a significantly higher incidence of AVF failure compared to those in tertile 1 (p = 0.019). Moreover, we found that patients with higher baseline LGI values had a significantly higher risk of AVF failure during follow-up (HR: 1.48, p = 0.003). The association is independent of age and sex (HR: 1.65, p = 0.001), cardiovascular risk factors (HR: 1.63, p = 0.012), and pre-operative vascular mapping determinations (HR: 3.49, p = 0.037). (4) Conclusions: In conclusion, high preoperative values of LGI are positively associated with long-term AVF failure. The prognostic role of the biomarker was independent of age, sex, cardiovascular risk factors, and pre-operative vascular mapping determinations.

The rodent models of arteriovenous fistula

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

Rosuvastatin Improves Endothelial Dysfunction in Diabetes by Normalizing Endoplasmic Reticulum Stress via Calpain-1 Inhibition

BACKGROUND

Rosuvastatin contributes to the improvement of vascular complications in diabetes, but the protective mechanisms remain unclear. The aim of the present study was to investigate the effect and mechanism of rosuvastatin on endothelial dysfunction induced by diabetes.

METHODS

Calpain-1 knockout (Capn1 EK684-/-) and C57BL/6 mice were intraperitoneally injected with STZ to induce type 1 diabetes. Human umbilical vein endothelial cells (HUVECs) were incubated with high glucose in this study. The function of isolated vascular rings, apoptosis, and endoplasmic reticulum stress (ERS) indicators were measured in this experiment.

RESULTS

The results showed that rosuvastatin (5 mg/kg/d) and calpain-1 knockout improved impaired vasodilation in an endothelial-dependent manner, and this effect was abolished by an ERS inducer. Rosuvastatin administration inhibited calpain-1 activation and ERS induced by high glucose, as well as apoptosis and oxidative stress both in vivo and in vitro. In addition, an ERS inducer (tunicamycin) offset the beneficial effect of rosuvastatin on endothelial dysfunction and ERS, which was accompanied by increased calpain-1 expression. The ERS inhibitor showed a similar improvement in endothelial dysfunction with rosuvastatin but could not increase the improvement in endothelial function of rosuvastatin.

CONCLUSION

These results suggested that rosuvastatin improves endothelial dysfunction by suppressing calpain- 1 and normalizing ERS, subsequently decreasing apoptosis and oxidative stress.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

ProT-α gene transfer attenuates cardiopulmonary remedying and mortality in a flow-induced pulmonary hypertension rat model

BACKGROUND

ProT is a cell survival gene, which modulates oxidative stress and transforming growth factor (TGF)-β signaling. We hypothesized that the delivery of the ProT cDNA gene in rats could protect against right heart dysfunction secondary to pulmonary hypertension (PH) induced by left-to-right shunt.

METHODS

A 2-hit rat model of flow-induced PH was used, and a single intravenous injection of adenoviral vectors (2 billion plaque-forming unit) carrying ProT or Luc gene was administered. The animals were euthanized 21 days after gene delivery to assess cardiopulmonary function, serum biochemistry, pulmonary artery (PA), and vasomotor reactivity. Immunohistology and immunoblotting of PA tissues were also performed.

RESULTS

ProT transduction significantly reduced PA pressure, right ventricle muscle mass, and wall stress, thereby improving the overall survival of the treated rat. Increased production of ProT through gene therapy preserved both the smooth muscle myosin heavy chain-II and α-smooth muscle actin while counteracting the abundance of TGF-β in PA. Protein abundances of phosphorylated p47-phox, heme oxygenase-1, caspase-3, inducible nitric oxide synthase, cyclo-oxygenase 2, and monocyte chemoattractant protein-1 in PA tissues were reduced. ProT also preserved microRNA-223, thereby suppressing the abundance of PARP-1, which is independent of hypoxia-inducible factor-1α signaling.

CONCLUSIONS

ProT gene transduction improved PA function by reducing oxidative stress, attenuating inflammation, and preserving the contractile phenotype of vascular smooth muscle cells. The modification of microRNA-223-associated downstream signaling through ProT transduction may play an important role in mitigating cardiopulmonary remodeling in flow-induced PH.

Atorvastatin Reduces In Vivo Fibrin Deposition and Macrophage Accumulation, and Improves Primary Patency Duration and Maturation of Murine Arteriovenous Fistula

BACKGROUND

Arteriovenous fistulas placed surgically for dialysis vascular access have a high primary failure rate resulting from excessive inward remodeling, medial fibrosis, and thrombosis. No clinically established pharmacologic or perisurgical therapies currently address this unmet need. Statins' induction of multiple anti-inflammatory and antithrombotic effects suggests that these drugs might reduce arteriovenous fistula failure. Yet, the in vivo physiologic and molecular effects of statins on fistula patency and maturation remain poorly understood.

METHODS

We randomized 108 C57Bl/6J mice to receive daily atorvastatin 1.14 mg/kg or PBS (control) starting 7 days before end-to-side carotid artery-jugular vein fistula creation and for up to 42 days after fistula creation. We then assessed longitudinally the effects of statin therapy on primary murine fistula patency and maturation. We concomitantly analyzed the in vivo arteriovenous fistula thrombogenic and inflammatory macrophage response to statin therapy, using the fibrin-targeted, near-infrared fluorescence molecular imaging agent FTP11-CyAm7 and dextranated, macrophage-avid nanoparticles CLIO-VT680.

RESULTS

In vivo molecular-structural imaging demonstrated that atorvastatin significantly reduced fibrin deposition at day 7 and macrophage accumulation at days 7 and 14, findings supported by histopathologic and gene-expression analyses. Structurally, atorvastatin promoted favorable venous limb outward remodeling, preserved arteriovenous fistula blood flow, and prolonged primary arteriovenous fistula patency through day 42 (P<0.05 versus control for all measures).

CONCLUSIONS

These findings provide new in vivo evidence that statins improve experimental arteriovenous fistula patency and maturation, indicating that additional clinical evaluation of statin therapy in patients on dialysis undergoing arteriovenous fistula placement is warranted.

Elevated Platelet Galectin-3 and Rho-Associated Protein Kinase Activity Are Associated with Hemodialysis Arteriovenous Shunt Dysfunction among Subjects with Diabetes Mellitus

Introduction

Hyperglycemia is a major factor in influencing the patency rate of arteriovenous shunts, potentially associated with the RhoA/Rho-associated protein kinase (ROCK) pathway. Besides, galectin-3 mediates thrombotic mechanisms in venous thrombosis and peripheral artery disease. We hypothesized that high ROCK activity and galectin-3 levels are associated with arteriovenous shunt dysfunction.

Methods

We prospectively enrolled 38 patients diagnosed with arteriovenous shunt dysfunction. 29 patients received a complete follow-up and each provided two blood samples, which were collected at the first visit for occluded status of arteriovenous shunts and 1 month later for patent status. A Western blot assay for a myosin phosphatase target subunit (MYPT) was performed to examine Rho-kinase activity. A Western blot assay for platelet galectin-3 and enzyme-linked immunosorbent assay (ELISA) for circulating galectin-3 were completed.

Results

Higher platelet MYPT ratios and galectin-3 levels were identified at occluded arteriovenous shunts (MYPT ratio: 0.5 [0.3-1.4] vs. 0.4 [0.3-0.6], p = 0.01; galectin-3: 1.2 [0.4-1.6] vs. 0.7 [0.1-1.2], p = 0.0004). The plasma galectin-3 binding protein ELISA was also higher at occluded arteriovenous shunts (8.4 [6.0-9.7] μg/mL vs. 7.1 [4.5-9.1] μg/mL, p = 0.009). Biomarker ratios (occluded/patent status) trended high in patients with poorly controlled diabetes (MYPT ratio: 1.7 [1.0-3.0] vs. 1.1 [0.7-1.3], p = 0.06; galectin-3: 1.6 [1.3-3.4] vs. 1.1 [0.8-1.9], p = 0.05).

Conclusion

High platelet ROCK activity and galectin-3 levels are associated with increased risk in arteriovenous shunt dysfunction, especially in patients with poorly controlled diabetes.

Restoration of Autologous Arteriovenous Fistula by Removal of the Occluded Short Venous Part and Venovenous End-To-End Anastomosis in a Hemodialysis Patient

Standard salvage procedures for occuluded autologous arteriovenous fistula (AVF) in a hemodialysis patient are endovascular and/or surgical therapy. When endovascular therapy and thrombectomy prove unsuccessful, it is most likely that creating a new AVF or arteriovenous graft will be considered. However, if the occuluded venous part is short, we have adopted an operative technique for repair of AVF by removal of the occluded short venous part and venovenous end-to-end anastomosis. To our knowledge, the efficacy and clinical course of restoration of AVF by the technique have not been reported to date. Here, we describe the technique and report the successful treatment of a hemodialysis patient who developed AVF occlusion.

Glucagon-like peptide-1 receptor agonist activation ameliorates venous thrombosis-induced arteriovenous fistula failure in chronic kidneyd isease

High shear stress that develops in the arteriovenous fistula of chronic kidney diseases (CKD) may increase H2O2 and thromboxane A2 (TXA2) release, thereby exacerbating endothelial dysfunction, thrombosis, and neointimal hyperplasia. We investigated whether glucagon-like peptide-1 receptor agonist/exendin-4, a potentially cardiovascular protective agent, could improve TXA2-induced arteriovenous fistula injury in CKD. TXA2 administration to H2O2-exposed human umbilical vein endothelial cells increased apoptosis, senescence, and detachment; these phenotypes were associated with the downregulation of phosphorylated endothelial nitric oxide synthase/heme oxygenase-1 (eNOS/HO-1) signalling. Exendin-4 reduced H2O2/TXA2-induced endothelial injury via inhibition of apoptosis-related mechanisms and restoration of phosphorylated eNOS/HO-1 signalling. Male Wistar rats subjected to right common carotid artery-external jugular vein anastomosis were treated with exendin-4 via cervical implant osmotic pumps for 16–42 days. High shear stress induced by the arteriovenous fistula significantly increased venous haemodynamics, blood and tissue H2O2 and TXB2 levels, macrophage/monocyte infiltration, fibrosis, proliferation, and adhesion molecule-1 expression. Apoptosis was also increased due to NADPH oxidase gp91 activation and mitochondrial Bax translocation in the proximal end of the jugular vein of CKD rats. Exendin-4-treatment of rats with CKD led to the restoration of normal endothelial morphology and correction of arteriovenous fistula function. Exendin-4 treatment or thromboxane synthase gene deletion in CKD mice markedly reduced ADP-stimulated platelet adhesion to venous endothelium, and prevented venous occlusion in FeCl3-injured vessels by upregulation of HO-1. Together, these data reveal that the use of glucagon-like peptide-1 receptor agonists is an effective strategy for treatment of CKD-induced arteriovenous fistula failure.

Exendin-4 improves cardiovascular function and survival in flow-induced pulmonary hypertension

OBJECTIVES

Systemic left-to-right shunting causes pulmonary arteriopathy, leading to progressive cardiopulmonary failure and a poor prognosis. In this study, we examined the extraglycemic effect of a synthetic glucagon-like peptide, exendin-4, on pulmonary arteriopathy regression and cardiopulmonary function in nondiabetic rats.

METHODS

Pulmonary hypertension (PH) was induced by monocrotaline (60 mg/kg, subcutaneous) injection followed by the creation of an aortocaval fistula. After 4 weeks, exendin-4 (1 μg/kg/day) was administered intraperitoneally for 3 consecutive weeks, followed by an assessment of cardiopulmonary function, pulmonary artery vasoreactivity, tissue and blood biochemistry, and lung histology.

RESULTS

Exendin-4 significantly reduced right ventricle mass and pulmonary artery pressure, which improved right ventricle function and the survival rate in rats with PH. Tissue and blood interleukin-1β levels decreased, whereas pulmonary artery cyclic adenosine monophosphate levels were restored by exendin-4. Smooth muscle-myosin heavy chain-II and α-smooth muscle actin protein levels increased in the pulmonary arteries of exendin-4-treated rats. Histology showed that exendin-4 decreased the main and intra-acinar pulmonary artery medial thickness.

CONCLUSIONS

Exendin-4 treatment improved pulmonary artery function in flow-induced PH via its direct vasoactive properties, anti-inflammatory effects, and vascular smooth muscle cell phenotypic modulation. Mitigation of pulmonary arteriopathy further potentiated right ventricle performance and reduced overall mortality. These responses were associated with suppressed expression and activity of interleukin-1β and its downstream signaling molecules. Glucagon-like peptide analogs may possess pleiotropic therapeutic potential in flow-induced PH.

Impact of Statins on Arteriovenous Fistulas Outcomes: A Meta-Analysis

Statins are effective lipid-lowering drugs with beneficial pleiotropic effects for vascular remodeling processes, statins may have a beneficial effect on the function of arteriovenous fistulas (AVFs) in hemodialysis (HD) patients. Therefore, we performed this systematic review to assess the protective effects of statin therapy in HD patients. The randomized controlled trials (RCTs) or quasi-RCTs and retrospective cohort studies (RCS) of statin therapy for the function of AVFs in HD patients were searched from multiple databases. Relevant studies were screened according to predefined inclusion criteria and then pooled-analyses were performed using RevMan 5.2 software. One RCT and six RCS containing 20 246 HD patients were included in this meta-analysis, of whom 9847 were treated with statins and 10 399 were treated with placebo. Our meta-analysis showed that there was no significant difference between statins and placebo groups, with those who received statin therapy showing similar AVF failure rates compared to control (pooled risk ratio = 0.89; 95% CI, 0.70 to 1.12, P = 0.32), and there was obvious evidence of statistical heterogeneity (P = 0.005; I²  = 68%). In addition, subgroup pooled analyses revealed that statin therapy did not ameliorate AVF failure in participants from the same racial background or similar sample size trials. There was no evidence that statins therapy could reduce the AVFs failure. However, due to methodological limitations and obvious statistical heterogeneity, high-quality, long-term and multicenter trials are required to fully elucidate the clinical value of statins administration for the outcomes of AVFs in HD patients.

Hemodynamic, biological, and right ventricular functional changes following intraatrial shunt repair in patients with flow-induced pulmonary hypertension

OBJECTIVES

Atrial septal defects may result in pulmonary hypertension and right heart remodeling. We analyzed improvements in patients with flow-induced pulmonary hypertension and the activation of endothelial progenitor cells after flow reduction.

DESIGN

This prospective cohort study included 37 patients who were admitted for an occluder implantation. Blood samples were collected before and after the procedure. We determined the number of endothelial progenitor cells in outgrowth colonies and serum Hsp27 concentrations. Daily performance and cardiothoracic ratio were reevaluated later.

RESULTS

Closure of the defect significantly reduced the pulmonary pressure and B-type natriuretic peptide levels. The cardiothoracic ratio and daily performance status also improved. The number of endothelial progenitor cell outgrowth colony-forming units significantly increased and was positively correlated with daily performance. In patients with enhanced colony formation, Hsp27 levels were significantly increased.

CONCLUSIONS

The implantation of an occluder successfully improved hemodynamic, right ventricular, and daily performance. Qualitative enhancement of colony formation for endothelial progenitor cells was also noted and positively correlated with daily performance. Closure of defects may serve as a valid, reliable model to obtain a deeper understanding of the modulation of endothelial progenitor cell activity and its relationship with pulmonary hypertension prognosis.

Efficacy of statin on vascular access patency in diabetic hemodialysis patients

INTRODUCTION

An effective approach to prevent hemodialysis vascular access dysfunction is still unclear despite previous studies, which have shown conflicting results of several drugs on vascular access outcomes. In this study, we focused on diabetic hemodialysis patients with native arteriovenous fistula and evaluated the impact of statin treatment on vascular access patency.

METHODS

A retrospective cohort study of 268 consecutive patients who newly started hemodialysis due to diabetic nephropathy between January 2011 and December 2013 at Japan Community Health Care Organization Sendai Hospital was performed and the patients were followed for two years. The primary outcome was vascular access dysfunction. Effect of statin treatment was examined using Kaplan Meier analysis and Cox proportional hazard, after adjusting for covariates.

RESULTS

The mean follow-up period was 426.7 days, and 117 (52.2%) patients developed vascular access dysfunction. The two-year patency rate was 55.0% among statin users and 36.1% in non-users. Vascular access survival period was significantly longer among statin users (log-rank test, p = 0.004). In multivariable analysis, statin treatment is significantly associated with better vascular access outcomes, in which the hazard ratio was 0.71 (95% CI, 0.52 to 0.97; p = 0.028) in the unadjusted model and 0.63 (95% CI, 0.45 to 0.88; p = 0.007) after adjustment for covariates.

CONCLUSIONS

Statin treatment could be associated with improved vascular access dysfunction among diabetic hemodialysis patients.

Use of Statins to Augment Progenitor Cell Function in Preclinical and Clinical Studies of Regenerative Therapy: a Systematic Review

BACKGROUND

Mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs) are used in cell-based regenerative therapy. HMG CoA reductase inhibitors (statins) appear promising in blocking apoptosis, prolonging progenitor cell survival and improving their capacity to repair organ function.

METHODS

We performed a systematic review of preclinical and clinical studies to clarify whether statins can improve cell-based repair of organ injury. MEDLINE, EMBASE, and PUBMED databases were searched (1947 to June 25, 2013). Controlled clinical and pre-clinical studies were included that evaluated statin therapy used alone or in combination with MSCs or EPCs in patients or animals with organ injury.

RESULTS

After screening 771 citations, 100 records underwent full eligibility screening of which 38 studies met eligibility and were included in the review: Studies were grouped into pre-clinical studies that involved statin treatment in combination with cell therapy (18 studies), preclinical studies of statin therapy alone (13 studies) and clinical studies of statin therapy (7 studies). Studies addressed cardiac injury (14 studies), vascular disorders (15 studies), neurologic conditions (8 studies) and bone fractures (1 study). Pre-clinical studies of statins in combination with MSC infusion (15 studies) or EPC therapy (3 studies) were described and despite marked heterogeneity in reporting outcomes of cellular analysis and organ function, all of these cell-based pre-clinical studies reported improved organ recovery with the addition of statin therapy. Moreover, 13 pre-clinical studies involved the administration of a statin drug alone to animals. An increase in EPC number and/or function (no studies of MSCs) was reported in 11 of these studies (85 %) and improved organ function in 12 studies (92 %). We also identified 7 clinical studies and none involved the administration of cells but described an increased number and/or function of EPCs (no studies of MSCs) and improved organ function with statin therapy (1.2-fold to 35-fold improvement over controls) in all 7 studies.

CONCLUSION

Our systematic review provides a foundation of encouraging results that support further study of statins in regenerative therapy to augment the number and/or function of MSCs used in cell-based repair and to augment the number and function of EPCs in vivo to repair damaged tissues. Larger studies are needed to ensure safety and confirm clinical benefits.

Use of a proactive duplex ultrasound protocol for hemodialysis access

OBJECTIVE

Arteriovenous fistula (AVF) creation is the preferred approach for hemodialysis access; however, the maturation of AVFs is known to be poor. We established a proactive early duplex ultrasound (DUS) surveillance protocol for evaluating AVFs before attempted access. This study determined the effect of this protocol related to improving AVF maturation.

METHODS

From 2008 to 2013, 153 patients received new upper extremity AVFs and an early DUS surveillance protocol at a single academic institution. The protocol involved an early DUS evaluation before hemodialysis cannulation of the AVF at 4 to 8 weeks after AVF creation. A positive DUS result was identified as a peak systolic velocity of >375 cm/s or a >50% stenosis on gray scale imaging, along with decreased velocity in the outflow vein. Patients with positive DUS findings underwent prophylactic endovascular or open intervention to assist with AVF maturation. Nature of secondary interventions, as well as AVF patency and maturation, were assessed. Overall clinical outcomes and fistula patency were investigated.

RESULTS

During the study period, 183 upper extremity AVFs were created in 153 patients, including 82 radiocephalic, 63 brachiocephalic, and 38 brachiobasilic AVFs. A mortality rate of 43% (n = 66) was observed in a median follow-up period of 34.5 months (interquartile range, 19.6-46.9). A total of 164 early DUS were performed at a median of 6 weeks (interquartile range, 3.4-9.6 weeks) after the initial creation. Early DUS showed nine AVFs were occluded and were excluded from further analysis. Hemodynamically significant lesions were found in 62 AVFs (40%); however, only 17 (11%) were associated with an abnormal physical examination. Positive DUS finding prompted a secondary intervention in 81% of the patients. Among those with positive early DUS findings, AVF maturation was 70% in those undergoing a secondary intervention compared with 25% in those not undergoing a prophylactic intervention (P = .011). Primary-assisted patency for AVFs with early positive and negative DUS findings were 83% and 96% at 6 months, 64% and 89% at 1 year, and 52% and 82% at 2 years, respectively (P < .001).

CONCLUSIONS

Early DUS surveillance of AVFs before initial access is reasonable to identify problematic AVFs that may not be reliably detected on clinical examination. Although DUS criteria for AVFs have yet to be universally accepted, proactive early postoperative DUS interrogation assists in the early detection of dysfunctional AVFs and improvement of fistula maturation. Despite improved patency in those with positive DUS findings who undergo prophylactic secondary intervention, overall patency remains inferior to those without an abnormality detected on early DUS imaging.

Mobilization of Endothelial Progenitor Cells Following Creation of Arteriovenous Access in Patients with End-Stage Renal Disease

BACKGROUND

A patent arteriovenous (AV) fistula induces activation of regional vascular endothelium and vascular shear force. Shear stress is an important physiological force in mobilizing endothelial progenitor cells (EPCs). This study aimed to explore the perioperative changes of circulating EPC levels for patients who require hemodialysis and underwent radiocephalic fistula operation.

METHODS

This prospective cohort study included patients who received a radiocephalic fistula surgery when they were between 25 and 65 years of age. The subjects were followed for 90 days postoperatively for any stenotic events or immaturity of the fistula. Blood samples were obtained on the day before surgery and at postoperation day (POD) 3 and 30. CD133+/KDR+ cells, defined as EPCs, were analyzed using flow cytometry. Blood flow of the fistula was followed on POD 3 and 30.

RESULTS

A total of 30 patients were enrolled in the study from July 2009 to December 2011. One patient dropped out of the study and seven patients developed a stenotic (or immature) AV fistula (7/29, 24.1%). There were positive linear relationships between EPC numbers and shear rate postoperatively, which were more significant on POD 30. In addition, postoperative mobilization of EPCs was significantly higher in patients who developed a stenotic fistula than those without.

CONCLUSIONS

The mobilization of circulating EPCs correlated with a compromised arteriovenous fistula. The biological significance of increased EPC numbers need to be determined in future studies.

KEY WORDS

Arteriovenous fistula; Endothelial progenitor cells.

Statins Improve Long Term Patency of Arteriovenous Fistula for Hemodialysis

The protective effects of statins against stenosis for permanent hemodialysis access have been repeatedly demonstrated in animal studies, but remain controversial in human studies. This study aims to evaluate the association between statin use and permanent hemodialysis access patency using a nationwide hemodialysis cohort. A total of 9862 pairs of statin users and non-users, matched by age and gender, were selected for investigation from 75404 new hemodialysis patients during 2000-2008. The effect of statins on permanent hemodialysis access patency was evaluated using Cox proportional hazards models. Compared with non-users, statin users had an overall 18% risk reduction in the composite endpoint in which angioplasty and recreation were combined (adjusted hazard ratio = 0.82 [95%CI, 0.78-0.87]) and 21% in recreation of permanent hemodialysis access (adjusted hazard ratio = 0.79 [95%CI, 0.69-0.80]). Specifically, the protective effect was found for arteriovenous fistula (adjusted hazard ratio = 0.78[95% CI, 0.73-0.82] for composite endpoint and 0.74 [95% CI, 0.69-0.80] for vascular recreation), but not for arteriovenous grafts (adjusted hazard ratio = 1.10 [95% CI, 0.98-1.24] and 0.94 [95% CI, 0.83-1.07]). Statins possess a protective effect for arteriovenous fistula against the recreation of permanent hemodialysis access. The results provide a pharmaco-epidemiologic link between basic research and clinical evidence.

Risk of arteriovenous fistula failure associated with hypnotic use in hemodialysis patients: a nested case-control study

PURPOSE

Hypnotic use might cause altered inflammatory processes, which have been suggested as being related to the mechanisms of arteriovenous fistula (AVF) failure. Therefore, we examined the association between the risk of AVF failure and hypnotic use in patients receiving hemodialysis (HD).

METHODS

A nested case-control study was conducted using data from the National Health Insurance Research Database of Taiwan. From 34 165 HD patients, 3676 patients receiving percutaneous transluminal angioplasty or surgical thrombectomy for AVF failure were matched to 14 704 control patients according to sex, age (±1 year), and the year of initial HD therapy. The risk of AVF failure was estimated based on conditional logistic regression after adjustment for the timing of AVF creation, HD frequency, comorbidities, and prescribed medications. Hypnotic use was measured prior to the date of AVF failure of case patients and the date of pseudo-AVF failure of controls.

RESULTS

Compared with matched controls, case patients were more likely to be exposed to hypnotics 30 days or an average daily defined dose > 0.5 within 90 days before the date of AVF failure, with an adjusted odds ratio of 1.21 (95% confidence interval [CI]: 1.09-1.35, p < 0.001) and 1.36 (95%CI: 1.13-1.63, p = 0.001), respectively. Risk of AVF failure associated with hypnotic use was also observed among HD patients who were male, were younger than 65 years, had hypertension, and did not use statins.

CONCLUSIONS

Hypnotic use among HD patients was associated with an increased risk of AVF failure. Copyright © 2016 John Wiley & Sons, Ltd.

IL-1β, RAGE and FABP4: targeting the dynamic trio in metabolic inflammation and related pathologies

Within the past decade, inflammatory and lipid mediators, such as IL-1β, FABP4 and RAGE, have emerged as important contributors to metabolic dysfunction. As growing experimental and clinical evidence continues to tie obesity-induced chronic inflammation with dysregulated lipid, insulin signaling and related pathologies, IL-1β, FABP4 and RAGE each are being independently implicated as culprits in these events. There are also convincing data that molecular pathways driven by these molecules are interconnected in exacerbating metabolic consequences of obesity. This article highlights the roles of IL-1β, FABP4 and RAGE in normal physiology as well as focusing specifically on their contribution to inflammation, insulin resistance, atherosclerosis, Type 2 diabetes and cancer. Studies implicating the interconnection between these pathways, current and emerging therapeutics, and their use as potential biomarkers are also discussed. Evidence of impact of IL-1β, FABP4 and RAGE pathways on severity of metabolic dysfunction underlines the strong links between inflammatory events, lipid metabolism and insulin regulation, and offers new intriguing approaches for future therapies of obesity-driven pathologies.

Pleiotropic vascular protective effects of statins in perioperative medicine

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor (statins) is one of the most commonly prescribed agents for controlling hyperlipidemia. Apart from their lipid-lowering property, statins are well known for their pleiotropic effects, such as improvement of vascular endothelial dysfunction, attenuation of inflammatory responses, stabilization of atherosclerotic plaques, inhibition of vascular smooth muscle proliferation, and modulation of procoagulant activity and platelet function. The vasculo-protective effect of statins is mainly mediated by inhibition of the mevalonate pathway and oxidized low-density lipoprotein generation, thereby enhancing the biosynthesis of endothelium-derived nitric oxide. Accumulating clinical evidence strongly suggests that administration of statins reduces overall mortality, the development myocardial infarction and atrial fibrillation, and length of hospital stay after a major cardiac/noncardiac surgery. This review updates the clinical pharmacology and therapeutic applications of statins during major operations, and highlights the anesthesia considerations for perioperative statin therapy.