Abstract 510: Effect of Repetitive Intra-Arterial Infusion of Bone Marrow Mononuclear Cells in Patients With No-Option Limb Ischemia: The Randomized, Double-Blind, Placebo-Controlled JUVENTAS Trial

Background: Patients with severe limb ischemia may not be eligible for conventional therapeutic interventions. Pioneering clinical trials suggest that bone marrow-derived cell therapy enhances neovascularization, improves tissue perfusion, and prevents amputation. The objective of this trial was to determine whether repetitive intra-arterial infusion of bone marrow mononuclear cells (BMMNCs) in patients with severe, nonrevascularizable limb ischemia can prevent major amputation.

Methods and Results: The Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) trial is a randomized, double-blind, placebo-controlled clinical trial in 160 patients with severe, nonrevascularizable limb ischemia. Patients were randomly assigned to repetitive (3 times; 3-week interval) intraarterial infusion of BMMNC or placebo. No significant differences were observed for the primary outcome, ie, major amputation at 6 months, with major amputation rates of 19% in the BMMNC versus 13% in the placebo group (relative risk, 1.46; 95% confidence interval, 0.62-3.42). The safety outcome (all-cause mortality, occurrence of malignancy, or hospitalization due to infection) was not significantly different between the groups (relative risk, 1.46; 95% confidence interval, 0.63-3.38), neither was all-cause mortality at 6 months with 5% versus 6% (relative risk, 0.78; 95% confidence interval, 0.22-2.80). Secondary outcomes quality of life, rest pain, ankle-brachial index, and transcutaneous oxygen pressure improved during follow-up, but there were no significant differences between the groups.

Conclusions: Repetitive intra-arterial infusion of autologous BMMNCs into the common femoral artery did not reduce major amputation rates in patients with severe, nonrevascularizable limb ischemia in comparison with placebo. The general improvement in secondary outcomes during follow-up in both the BMMNC and the placebo group, as well, underlines the essential role for placebo-controlled design of future trials.

Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00371371.

[Pleiotropic effects of statins]

Statins safely and effectively reduce the morbidity and mortality due to cardiovascular disease. In the trials conducted so far, which have been carried out predominantly on high-risk patients, the observed risk reduction is probably completely attributable to the reduction of the cholesterol level. However, statins also influence the atherosclerotic disease process in a lipid-independent way. This includes beneficial effects on the early pathogenetic components of atherosclerosis, such as endothelial dysfunction and inflammation. These effects are probably not visible in the large clinical trials that usually follow up cohorts of patients with late stages of atherosclerosis during a relatively short period of time. These cholesterol-independent effects do affect intermediate factors in the atherosclerotic process, such as endothelial dysfunction. In clinical practice, where not only short-term effects in patients with manifest vascular disease but also the prevention of the long-term complications of atherosclerosis in high-risk patients is an important goal, these so-called pleiotropic effects may contribute to risk reduction.

A comprehensive transcriptome characterization of individual nuclear receptor pathways in the human small intestine

Nuclear receptors (NRs) are widely expressed transcription factors that bind small, lipophilic compounds and regulate diverse biological processes. In the small intestine, NRs are known to act as sensors that control transcriptional responses to endogenous and exogenous signals, yet their downstream effects have not been characterized extensively. Here, we investigate the activation of six different NRs individually in human intestinal organoids using small molecules agonists. We observe changes in key enterocyte functions such as lipid, glucose, and amino acid absorption, the regulation of electrolyte balance, and drug metabolism. Our findings reinforce PXR, LXR, FXR, and PPARα as regulators of lipid absorption. Furthermore, known hepatic effects of AHR and VDR activation were recapitulated in the human small intestine. Finally, we identify unique target genes for intestinal PXR activation (ERG28, TMEM97, and TM7SF2), LXR activation (RAB6B), and VDR activation (CA12). This study provides an unbiased and comprehensive transcriptomic description of individual NR pathways in the human small intestine. By gaining a deeper understanding of the effects of individual NRs, we might better harness their pharmacological and therapeutic potential.

Abstract 728: The Neutrophil-to-lymphocyte Ratio is Associated With Amputation Free Survival in Critical Limb Ischemia

Introduction: Inflammation plays a key role in ischemic cardiovascular disease. The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive marker for inflammation and correlates with outcomes in critical limb ischemia (CLI). Previous studies have suffered from low power due to low event rates, and show only limited adjustment for confounders. We examined in a prospective cohort whether the peripheral blood (PB) NLR predicts amputation-free-survival (AFS) and has additional predictive power over established risk factors. We also studied bone-marrow (BM) composition and plasma cytokines to elucidate the etiology of NLR alterations.

Methods and Results: Data from CLI patients in the JUVENTAS Trial and ATHERO-EXPRESS registry were pooled (N=351). Median follow-up was 3.16 years during which 128 events (amputation or death) occurred. In patients that experienced an event, the PB NLR was elevated (Event: 4.2 (SD 2.8) vs No event: 3.0 (SD 1.9) p=<0.001), the neutrophil count was higher (6.3 (SD 2.5) vs 5.5 (SD2.3) p=0.0003), and the lymphocyte count was lower (1.7 (SD 0.8) vs 2.1 (SD 0.8) p<0.001). Cox regression showed that the hazard ratio (HR) for AFS was 1.6 (CI: 1.4-1.9), p=2*10 -8 . In a model adjusting for age, sex, diabetes mellitus, BMI, smoking, and GFR the NLR significantly predicted AFS, HR 1.4 (CI 1.2-1.7) p=0.0003. In a sub study in the JUVENTAS cohort, the PB NLR correlated with the BM NLR, but the BM NLR did not correlate with AFS. Additionally, the NLR correlated strongly with the inflammatory cytokines IL-6, IL-8, and CRP.

Discussion and Conclusion: These results show that the NLR is an independent predictor of AFS in CLI. While most studies analyzed the NLR as a binary value, here we show a continuous correlation between the NLR and AFS, even when corrected for major confounders. We show that blood NLR is reflected in BM and correlates with inflammatory cytokines, indicating that our incidental measurements may reflect chronic inflammation-driven alterations in BM.

Abstract 119: Potential Role for Bone Marrow Niche and Endothelial Progenitor Cell Dysfunction in Critical Limb Ischemia

Background

Critical limb ischemia (CLI) is characterized by obstruction of lower extremity arteries and a largely unexplained impaired ischemic neovascularization response. Bone marrow (BM) derived endothelial progenitor cells (EPC) contribute to postnatal neovascularization. We hypothesize that reduced levels and function of circulating progenitor cells and a dysfunctional BM environment contribute to impaired neovascularization in CLI.

Methods

Levels of primitive (CD34+ and CD133+) progenitors and CD34+KDR+ haemangioblastic EPC were analyzed using flow cytometry in peripheral blood (PB) and BM from 101 CLI patients in the JUVENTAS trial ( NCT00371371 ) and healthy controls (n=37 and n=12 for PB and BM, respectively). Endothelial damage markers (sE-selectin, sICAM-1, sVCAM-1, thrombomodulin) and PB levels of progenitor cell mobilizing (VEGF, SDF-1α, SCF, G-CSF) and inflammatory (IL-6, IL-8, IP-10) factors were assessed by ELISA and multiplex. Levels and activity of the EPC mobilizing protease MMP-9 were assessed in BM plasma by ELISA and zymography. Circulating angiogenic cells (CAC) were cultured from PB, and CAC paracrine function was assessed.

Results

Endothelial damage markers were higher in CLI ( p< 0.01). PB levels of VEGF, SDF-1α, SCF, G-CSF ( p< 0.05) and of IL-6, IL-8 and IP-10 were higher in CLI ( p< 0.05). Circulating EPC and CD133+ cells and BM CD34+ cells were significantly lower in CLI (all p <0.05), BM levels and activity of MMP-9 were lower in CLI (both p< 0.01). Multivariate regression analysis showed an inverse association between IL-6 levels and BM CD34+ cell levels ( p= 0.007). CAC outgrowth did not differ significantly between CLI patients and healthy controls ( p= 0.137), however CAC from CLI patients had profoundly reduced migration stimulating potential ( p< 0.0001).

Conclusion

CLI patients have reduced levels of circulating EPC despite profound endothelial injury and an EPC mobilizing response. Moreover, CLI patients have lower BM CD34+ cell levels, which were inversely associated with the inflammatory marker IL-6, and lower BM MMP-9 levels and activity. Our data suggest that reduced levels and function of circulating progenitor cells and BM dysfunction contribute to the defective neovascularization response in CLI.

[The polypill: not an effective strategy for reduction of cardiovascular disease]

The implementation of the intriguing concept of the polypill to prevent cardiovascular events remains doubtful due to a lack of evidence, expected adherence problems, the inevitable overtreatment and undertreatment of individuals, and potential side effects. Lifestyle changes and individual interventions are more preferable strategies.

[Women and cardiovascular disease]

More women die of cardiovascular disease than men; in women, cardiovascular mortality is 1.5 times greater than cancer mortality. The pathophysiology of cardiovascular disease has female-specific aspects such as fragile coronary arteries and microvascular ischaemia. Women with acute coronary syndromes are more likely to present with atypical symptoms such as dyspnoea, nausea or fatigue. With regard to diagnostic tests in women, exercise ECG can be difficult to interpret and a normal coronary angiogram does not exclude coronary heart disease. Myocardial perfusion scintigraphy may be considered for high-risk women who are clinically suspected of having coronary heart disease and have a normal or inconclusive exercise ECG and angiogram. Women are less likely to be treated according to guidelines than men, and their prognosis after a myocardial infarction or a coronary intervention is worse. Female-specific aspects such as gestational hypertension and diabetes allow for early detection and treatment of women at risk for cardiovascular disease.

Renal injury in relation to obesity and the additive effect of hypertension in female and male obese and lean ZSF1 rats

Heart failure with preserved ejection fraction (HFpEF) is characterized by obesity, hypertension, diabetes mellitus and chronic kidney disease. Obese ZSF1 rats, a model of HFpEF, exhibit multiple such comorbidities that can disturb cardiac function. Little attention has been paid to how these comorbidities affect renal disease in ZSF1 rats. HFpEF is found predominantly in women in whom obesity and hypertension are particularly prevalent. Therefore, we characterized renal phenotype in female and male, lean and obese, ZSF1 rats and investigated additional effects of worsened hypertension on disease severity. Systolic blood pressure and renal function were assessed biweekly from 12 to 26 weeks. From 19 weeks, rats were implanted with either a deoxycorticosterone acetate pellet and fed high salt diet (DS) or a placebo pellet and fed normal salt diet. At 26 weeks, terminal GFR was assessed via inulin clearance under isoflurane. Renal sections were processed for histological analysis. Lean and obese ZSF1 rats, both female and male, were mildly hypertensive (systolic blood pressure 140-150 mmHg). All obese ZSF1 rats showed HFpEF. In female normoglycemic ZSF1 rats, obesity associates with mild proteinuria, decreased glomerular filtration rate and glomerular hypertrophy. DS-worsened hypertension enhanced proteinuria and triggered glomerulosclerosis. Male obese ZSF1 rats were hyperglycemic and showed proteinuria, glomerular hypertrophy and sclerosis, and tubulo-interstitial damage. DS-worsened hypertension aggravated this phenotype in male ZSF1 rats. In conclusion, female obese ZSF1 rats develop mild renal dysfunction and DS-worsened hypertension compromises renal function and structure in normoglycemic female obese ZSF1 rats as in hyperglycemic male obese ZSF1 rats.

Renal Biology Driven Macro- and Microscale Design Strategies for Creating an Artificial Proximal Tubule Using Fiber-Based Technologies

Chronic kidney disease affects one in six people worldwide. Due to the scarcity of donor kidneys and the complications associated with hemodialysis (HD), a cell-based bioartificial kidney (BAK) device is desired. One of the shortcomings of HD is the lack of active transport of solutes that would normally be performed by membrane transporters in kidney epithelial cells. Specifically, proximal tubule (PT) epithelial cells play a major role in the active transport of metabolic waste products. Therefore, a BAK containing an artificial PT to actively transport solutes between the blood and the filtrate could provide major therapeutic advances. Creating such an artificial PT requires a biocompatible tubular structure which supports the adhesion and function of PT-specific epithelial cells. Ideally, this scaffold should structurally replicate the natural PT basement membrane which consists mainly of collagen fibers. Fiber-based technologies such as electrospinning are therefore especially promising for PT scaffold manufacturing. This review discusses the use of electrospinning technologies to generate an artificial PT scaffold for ex vivo/in vivo cellularization. We offer a comparison of currently available electrospinning technologies and outline the desired scaffold properties required to serve as a PT scaffold. Discussed also are the potential technologies that may converge in the future, enabling the effective and biomimetic incorporation of synthetic PTs in to BAK devices and beyond.

The general external exposome and the development or progression of chronic kidney disease: A systematic review and meta-analyses

The impact of environmental risk factors on chronic kidney disease (CKD) remains unclear. This systematic review aims to provide an overview of the literature on the association between the general external exposome and CKD development or progression. We searched MEDLINE and EMBASE for case-control or cohort studies, that investigated the association of the general external exposome with a change in eGFR or albuminuria, diagnosis or progression of CKD, or CKD-related mortality. The risk of bias of included studies was assessed using the Newcastle-Ottawa Scale. Summary effect estimates were calculated using random-effects meta-analyses. Most of the 66 included studies focused on air pollution (n = 33), e.g. particulate matter (PM) and nitric oxides (NOx), and heavy metals (n = 21) e.g. lead and cadmium. Few studies investigated chemicals (n = 7) or built environmental factors (n = 5). No articles on other environment factors such as noise, food supply, or urbanization were found. PM2.5 exposure was associated with an increased CKD and end-stage kidney disease incidence, but not with CKD-related mortality. There was mixed evidence regarding the association of NO2 and PM10 on CKD incidence. Exposure to heavy metals might be associated with an increased risk of adverse kidney outcomes, however, evidence was inconsistent. Studies on effects of chemicals or built environment on kidney outcomes were inconclusive. In conclusion, prolonged exposure to PM2.5 is associated with an increased risk of CKD incidence and progression to kidney failure. Current studies predominantly investigate the exposure to air pollution and heavy metals, whereas chemicals and the built environment remains understudied. Substantial heterogeneity and mixed evidence were found across studies. Therefore, long-term high-quality studies are needed to elucidate the impact of exposure to chemicals or other (built) environmental factors and CKD.

A systematic review of kidney-on-a-chip-based models to study human renal (patho-)physiology

As kidney diseases affect ∼10% of the world population, understanding the underlying mechanisms and developing therapeutic interventions are of high importance. Although animal models have enhanced knowledge of disease mechanisms, human (patho-)physiology may not be adequately represented in animals. Developments in microfluidics and renal cell biology have enabled the development of dynamic models to study renal (patho-)physiology in vitro. Allowing inclusion of human cells and combining different organ models, such as kidney-on-a-chip (KoC) models, enable the refinement and reduction of animal experiments. We systematically reviewed the methodological quality, applicability and effectiveness of kidney-based (multi-)organ-on-a-chip models, and describe the state-of-the-art, strengths and limitations, and opportunities regarding basic research and implementation of these models. We conclude that KoC models have evolved to complex models capable of mimicking systemic (patho-)physiological processes. Commercial chips and human induced pluripotent stem cells and organoids are important for KoC models to study disease mechanisms and assess drug effects, even in a personalized manner. This contributes to the Reduction, Refinement and Replacement of animal models for kidney research. A lack of reporting of intra- and inter-laboratory reproducibility and translational capacity currently hampers implementation of these models.

Discrepancies between transcutaneous and estimated glomerular filtration rates in rats with chronic kidney disease

Accurate assessment of the glomerular filtration rate (GFR) is crucial for researching kidney disease in rats. Although validation of methods that assess GFR is crucial, large-scale comparisons between different methods are lacking. Both transcutaneous GFR (tGFR) and a newly developed estimated GFR (eGFR) equation by our group provide a low-invasive approach enabling repeated measurements. The tGFR is a single bolus method using FITC-labeled sinistrin to measure GFR based on half-life of the transcutaneous signal, whilst the eGFR is based on urinary sinistrin clearance. Here, we retrospectively compared tGFR, using both 1- and 3- compartment models (tGFR_1c and tGFR_3c, respectively) to the eGFR in a historic cohort of 43 healthy male rats and 84 male rats with various models of chronic kidney disease. The eGFR was on average considerably lower than tGFR-1c and tGFR-3c (mean differences 855 and 216 μL/min, respectively) and only 20 and 47% of measurements were within 30% of each other, respectively. The relative difference between eGFR and tGFR was highest in rats with the lowest GFR. Possible explanations for the divergence are problems inherent to tGFR, such as technical issues with signal measurement, description of the signal kinetics, and translation of half-life to tGFR, which depends on distribution volume. The unknown impact of isoflurane anesthesia used in determining mGFR remains a limiting factor. Thus, our study shows that there is a severe disagreement between GFR measured by tGFR and eGFR, stressing the need for more rigorous validation of the tGFR and possible adjustments to the underlying technique.

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

Determinants of Caregiver Burden Among Spouses of Patients With Kidney Failure: A Qualitative Study

RATIONALE & OBJECTIVE

Spousal caregivers participate extensively in the care of patients with kidney failure. Although previous studies suggested that these caregivers experience a high burden, a comprehensive understanding of the determinants of this burden and strategies to alleviate it are needed. Therefore, this study sought to explore the contributing and alleviating determinants of burden in spousal caregivers of patients with kidney failure.

STUDY DESIGN

A qualitative interview study with 15 spousal caregivers.

SETTING & PARTICIPANTS

Dutch-speaking, adult spousal caregivers were recruited and interviewed by the Dutch Kidney Patients Association for the Kidney Decision Aid.

ANALYTICAL APPROACH

A directed qualitative content analysis using the stress-appraisal model of caregiver burden as a framework to inform a disease-specific model on spousal caregiver burden for kidney failure that characterizes the impact of care provision on all aspects of spousal caregivers' lives, the burden associated with it, and possible mitigating factors.

RESULTS

Providing care for patients with kidney failure is complex and burdensome for spousal caregivers and results in many lifestyle changes, which are largely caused by kidney failure-specific tasks and the shifting responsibility for daily life tasks. Spouses identified disease-specific determinants of burden including the impact of kidney disease on spouses with the disease as well as the associated caregiver tasks, such as adjusting to dietary restrictions and attending dialysis appointments. Dialysis options (eg, the choice for home or in-center dialysis) were kidney failure-specific moderators of burden. Support of spousal caregivers by health care providers plays a key role in preventing overburdening.

LIMITATIONS

Potential limited transferability owing to the study of only Dutch-speaking spouses willing to be interviewed and videotaped.

CONCLUSIONS

This comprehensive overview of the contributing and alleviating determinants of burden experienced by spousal caregivers of patients with kidney failure highlights 4 principal areas: (1) personal and relational, (2) social environment, (3) health care, and (4) work and legislation, in which such burdens occur and may be alleviated.

PLAIN-LANGUAGE SUMMARY

Spousal caregivers are crucial for supporting patients with kidney failure, but they often experience significant stress and challenges. This study explored factors that contribute to spousal caregiver burden and ways to alleviate it. We interviewed 15 spousal caregivers of patients with kidney failure. We found that providing care for patients with kidney failure is complex, burdensome, and has a major impact on caregivers' lives. We identify factors that contribute to caregiver burden but also factors that may ease this burden. This study underlines the need for acknowledgement of spousal caregivers in 4 areas, namely (1) personal and relational, (2) social environment, (3) health care, and (4) work and legislation.