The Bone-Vascular Axis in Chronic Kidney Disease: From Pathophysiology to Treatment.

PURPOSE OF REVIEW: This review aims to describe the pathogenic factors involved in bone-vessel anomalies in CKD which are the object of numerous experimental and clinical research. RECENT FINDINGS: Knowledge on the pathophysiological mechanisms involved in the regulation of vascular calcification and mineral-bone disorders is evolving. Specific bone turnover anomalies influence the vascular health while recent studies demonstrate that factors released by the calcified vessels also contribute to bone deterioration in CKD. Current therapies used to control mineral dysregulations will impact both the vessels and bone metabolism. Available anti-osteoporotic treatments used in non-CKD population may negatively or positively affect vascular health in the context of CKD. It is essential to study the bone effects of the new therapeutic options that are currently under investigation to reduce vascular calcification. Our paper highlights the complexity of the bone-vascular axis and discusses how current therapies may affect both organs in CKD.

Chronic kidney disease is a key risk factor for aortic stenosis progression.

BACKGROUND: Rapid progression of aortic stenosis (AS) has been observed in patients undergoing dialysis, but existing cross-sectional evidence is contradictory in non-dialysis-dependent chronic kidney disease (CKD). The present study sought to evaluate whether CKD is associated with the progression of AS over time in a large cohort of patients with AS. METHODS: We retrospectively studied all consecutive patients diagnosed with AS [peak aortic jet velocity (Vmax) ≥2.5 m/s] and left ventricular ejection fraction ≥50% in the echocardiography laboratories of two tertiary centers between 2000 and 2018. The estimated glomerular filtration rate (eGFR) (mL/min/1.73 m2) was calculated from serum creatinine values. Patients were divided into five CKD stages according to the baseline eGFR. Annual rates of change in the aortic valve area (AVA) were determined by a linear mixed-effects model. RESULTS: Among the 647 patients included, 261 (40%) had CKD. After a median follow-up of 2.9 (interquartile range 1.8-4.8) years, the mean overall rate of change in AVA was -0.077 (95% confidence interval -0.082; -0.073) cm2/year. There was an inverse relationship between the progression rate and kidney function. The more severe the CKD stage, the greater the AVA narrowing (P < .001). By multivariable linear regression analysis, the eGFR was also negatively associated (P < .001) with AS progression. An eGFR strata below 45 mL/min/1.73 m2 was associated with higher odds of rapid progression of AS than normal kidney function. During the clinical follow-up, event-free survival (patients free of aortic valve replacement or death) decreased as CKD progressed. Rapid progression of AS in patients with kidney dysfunction was associated with worse outcomes. CONCLUSIONS: Patients with CKD exhibit more rapid progression of AS over time and require close monitoring. The link between kidney dysfunction and rapid progression of AS is still unknown and requires further research.

Indoxyl-sulfate activation of the AhR- NF-κB pathway promotes interleukin-6 secretion and the subsequent osteogenic differentiation of human valvular interstitial cells from the aortic valve.

BACKGROUND: Calcific aortic stenosis (CAS) is more prevalent, occurs earlier, progresses faster and has worse outcomes in patients with chronic kidney disease (CKD). The uremic toxin indoxyl sulfate (IS) is powerful predictor of cardiovascular mortality in these patients and a strong promoter of ectopic calcification whose role in CAS remains poorly studied. The objective of this study was to evaluate whether IS influences the mineralization of primary human valvular interstitial cells (hVICs) from the aortic valve. METHODS: Primary hVICs were exposed to increasing concentrations of IS in osteogenic medium (OM). The hVICs' osteogenic transition was monitored by qRT-PCRs for BMP2 and RUNX2 mRNA. Cell mineralization was assayed using the o-cresolphthalein complexone method. Inflammation was assessed by monitoring NF-κB activation using Western blots as well as IL-1ß, IL-6 and TNF-α secretion by ELISAs. Small interfering RNA (siRNA) approaches enabled us to determine which signaling pathways were involved. RESULTS: Indoxyl-sulfate increased OM-induced hVICs osteogenic transition and calcification in a concentration-dependent manner. This effect was blocked by silencing the receptor for IS (the aryl hydrocarbon receptor, AhR). Exposure to IS promoted p65 phosphorylation, the blockade of which inhibited IS-induced mineralization. Exposure to IS promoted IL-6 secretion by hVICs, a phenomenon blocked by silencing AhR or p65. Incubation with an anti-IL-6 antibody neutralized IS's pro-calcific effects. CONCLUSION: IS promotes hVIC mineralization through AhR-dependent activation of the NF-κB pathway and the subsequent release of IL-6. Further research should seek to determine whether targeting inflammatory pathways can reduce the onset and progression of CKD-related CAS.

No Impact of Corticosteroid Use During the Acute Phase on Persistent Symptoms Post-COVID-19.

Persistent COVID-19 symptoms may be related to residual inflammation, but no preventive treatment has been evaluated. This study aimed to analyze, in a prospective cohort, whether corticosteroid use in the acute phase of COVID-19 in hospitalized patients may reduce the risk of persistent COVID-19 symptoms. A total of 306 discharged patients, including 112 (36.6%) from the ICU, completed a structured face-to-face assessment 4 months after admission. Of these, 193 patients (63.1%) had at least one persistent symptom, mostly dyspnea (38.9%) and asthenia (37.6%). One-hundred and four patients have received corticosteroids. In multivariable adjusted regression analysis, corticosteroid use was not associated with the presence of at least one symptom (OR=1.00, 95% CI: 0.58-1.71, p=0.99) or with the number of persistent symptoms (p=0.74). Corticosteroid use remained ineffective when analyzing the ICU subpopulation separately. Our study suggests that corticosteroid use had no impact on persistent symptoms after COVID-19 in discharged patients.

Number of initial symptoms is more related to long COVID-19 than acute severity of infection: a prospective cohort of hospitalized patients.

OBJECTIVES: Post-COVID-19 symptoms experienced by many survivors have a further devastating effect. This study aimed to analyze the risk factors associated with long COVID-19 in a prospective cohort of hospitalized patients including those requiring intensive care unit (ICU) transfer, taking into account objective measures of COVID-19 severity. METHODS: Hospitalized patients with confirmed COVID-19 were enrolled. A structured follow-up visit was performed 4 months after hospital admission. Multivariable adjusted regression models were used to analyse the association between parameters at the acute phase and persistent symptoms. RESULTS: A follow-up visit was performed in 316 patients including 115 (36.4%) discharged from the ICU. Mean age was 64.1 years, and 201 patients (58.3%) were men. Female sex (odds ratio [OR], 1.94; 95% confidence interval [CI], 1.17-3.22; P =.01), hypertension (OR, 2.01; 95% CI, 1.22-3.31; P <.01), and the number of initial symptoms (NIS) (OR, 1.35; 95% CI, 1.17-1.54; P <.001) were significantly associated with long COVID-19. Number of persistent symptoms was significantly associated with NIS (adjusted incidence rate ratio [aIRR], 1.16; 95% CI, 1.11-1.22; P <.001), female sex (aIRR, 1.56; 95% CI 1.29-1.87; P <.001), hypertension (aIRR, 1.23; 95% CI, 1.02-1.50; P =.03), and length of stay in hospital (aIRR, 1.01; 95% CI, 1.005-1.017; P <.001). CONCLUSION: Our study suggested that female sex, hypertension, and NIS had a significant impact on persistent symptoms in hospitalized patients in contrast to severity of acute COVID-19 infection.

COVID-19-related mortality in kidney transplant and haemodialysis patients: a comparative, prospective registry-based study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has exposed haemodialysis (HD) patients and kidney transplant (KT) recipients to an unprecedented life-threatening infectious disease, raising concerns about kidney replacement therapy (KRT) strategy during the pandemic. This study investigated the association of the type of KRT with COVID-19 severity, adjusting for differences in individual characteristics. METHODS: Data on KT recipients and HD patients diagnosed with COVID-19 between 1 February 2020 and 1 December 2020 were retrieved from the European Renal Association COVID-19 Database. Cox regression models adjusted for age, sex, frailty and comorbidities were used to estimate hazard ratios (HRs) for 28-day mortality risk in all patients and in the subsets that were tested because of symptoms. RESULTS: A total of 1670 patients (496 functional KT and 1174 HD) were included; 16.9% of KT and 23.9% of HD patients died within 28 days of presentation. The unadjusted 28-day mortality risk was 33% lower in KT recipients compared with HD patients {HR 0.67 [95% confidence interval (CI) 0.52-0.85]}. In a fully adjusted model, the risk was 78% higher in KT recipients [HR 1.78 (95% CI 1.22-2.61)] compared with HD patients. This association was similar in patients tested because of symptoms [fully adjusted model HR 2.00 (95% CI 1.31-3.06)]. This risk was dramatically increased during the first post-transplant year. Results were similar for other endpoints (e.g. hospitalization, intensive care unit admission and mortality >28 days) and across subgroups. CONCLUSIONS: KT recipients had a greater risk of a more severe course of COVID-19 compared with HD patients, therefore they require specific infection mitigation strategies.

Metformin prevents stroke damage in non-diabetic female mice with chronic kidney disease.

Chronic kidney disease (CKD) worsens ischemic stroke severity in both patients and animals. In mice, these poorer functional outcomes are associated with decreased brain activity of AMP-activated protein kinase (AMPK), a molecule that recently emerged as a potential therapeutic target for ischemic stroke. The antidiabetic drug metformin, a well-known activator of AMPK, has improved stroke outcomes in diabetic patients with normal renal function. We investigated whether chronic metformin pre-conditioning can rescue AMPK activity and prevent stroke damage in non-diabetic mice with CKD. Eight-week-old female C57BL/6J mice were assigned to CKD or SHAM groups. CKD was induced through right kidney cortical electrocautery, followed by left total nephrectomy. Mice were then allocated to receive metformin (200 mg/kg/day) or vehicle for 5 weeks until stroke induction by transient middle cerebral artery occlusion (tMCAO). The infarct volumes were lower in CKD mice exposed to metformin than in vehicle-treated CKD mice 24 h after tMCAO. Metformin pre-conditioning of CKD mice improved their neurological score, grip strength, and prehensile abilities. It also enhanced AMPK activation, reduced apoptosis, increased neuron survival and decreased microglia/macrophage M1 signature gene expression as well as CKD-induced activation of the canonical NF-κB pathway in the ischemic lesions of CKD mice.

Aortic stenosis in patients with kidney failure: Is there an advantage for a PD-first policy?

Aortic stenosis (AS) is the most common valvular disease. It is twice as prevalent in patients with kidney failure as compared to the general population. In addition, AS progresses at a faster rate and is associated with a higher risk of death and poorer quality of life in patients on dialysis. Chronic kidney disease-mineral and bone disorder (CKD-MBD), inflammation, and hemodynamic disturbances contribute to the pathophysiology and progression of AS. Whether the type of dialysis modality, that is, hemodialysis (HD) versus peritoneal dialysis (PD), has a differential impact on the development and progression of AS in patients with kidney failure remains debated. Recent data indicate that the prevalence of valvular calcifications might be lower and the development of AS delayed in PD patients, as compared to those treated with HD. This could be accounted for by several mechanisms including reduced valvular shear stress, better preservation of residual kidney function (with better removal of protein-bound uremic toxins and CKD-MBD profile), and lower levels of systemic inflammation. Given the high morbidity and mortality rates related to interventional procedures in the population with kidney failure, surgical and transcatheter aortic valve replacement should be considered in selected patients with severe AS. Strategies slowing down the progression of aortic valve remodeling should remain the cornerstone in the management of individuals with kidney failure and mild to moderate AS. This review explores the potential benefits of PD in patients with kidney failure and AS and provides some clues to help clinicians in the decision-making process when options for kidney replacement therapy are considered in patients with AS.

Severe Aortic Stenosis and Chronic Kidney Disease: Outcomes and Impact of Aortic Valve Replacement.

Background The prognostic significance of chronic kidney disease (CKD) in severe aortic stenosis is poorly understood and no studies have yet evaluated the effect of aortic-valve replacement (AVR) versus conservative management on long-term mortality by stage of CKD. Methods and Results We included 4119 patients with severe aortic stenosis. The population was divided into 4 groups according to the baseline estimated glomerular filtration rate: no CKD, mild CKD, moderate CKD, and severe CKD. The 5-year survival rate was 71±1% for patients without CKD, 62±2% for those with mild CKD, 54±3% for those with moderate CKD, and 34±4% for those with severe CKD (P<0.001). By multivariable analysis, patients with moderate or severe CKD had a significantly higher risk of all-cause (hazard ratio [HR] [95% CI]=1.36 [1.08-1.71]; P=0.009 and HR [95% CI]=2.16 [1.67-2.79]; P<0.001, respectively) and cardiovascular mortality (HR [95% CI]=1.39 [1.03-1.88]; P=0.031 and HR [95% CI]=1.69 [1.18-2.41]; P=0.004, respectively) than patients without CKD. Despite more symptoms, AVR was less frequent in moderate (P=0.002) and severe CKD (P<0.001). AVR was associated with a marked reduction in all-cause and cardiovascular mortality versus conservative management for each CKD group (all P<0.001). The joint-test showed no interaction between AVR and CKD stages (P=0.676) indicating a nondifferentialeffect of AVR across stages of CKD. After propensity matching, AVR was still associated with substantially better survival for each CKD stage relative to conservative management (all P<0.0017). Conclusions In severe aortic stenosis, moderate and severe CKD are associated with increased mortality and decreased referral to AVR. AVR markedly reduces all-cause and cardiovascular mortality, regardless of the CKD stage. Therefore, CKD should not discourage physicians from considering AVR.

Absence of SARS-CoV-2 in the effluent of peritoneal dialysis patients.

The pandemic of respiratory disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is life-threatening in peritoneal dialysis (PD) patients. In PD patients with systemic viral infections, peritoneal effluent may be theoretically contaminated. We searched for the presence of SARS-CoV-2 genetic material by real-time reverse transcriptase-polymerase chain reaction assays in serial PD effluents of three PD infected patients. Nasopharyngeal swabs obtained at admission showed high viral load in all three patients, whereas none of the PD effluent specimen tested positive, even after dialysate concentration. Those results support at most a very low SARS-CoV-2 dissemination risk by the peritoneal effluent of PD patients. Imposing special disposal procedures, such as the instillation of hypochlorite in the drainage bags to prevent viral spread to health-care workers, are probably not required.

New Insights into the Roles of Monocytes/Macrophages in Cardiovascular Calcification Associated with Chronic Kidney Disease.

Cardiovascular disease (CVD) is an important cause of death in patients with chronic kidney disease (CKD), and cardiovascular calcification (CVC) is one of the strongest predictors of CVD in this population. Cardiovascular calcification results from complex cellular interactions involving the endothelium, vascular/valvular cells (i.e., vascular smooth muscle cells, valvular interstitial cells and resident fibroblasts), and monocyte-derived macrophages. Indeed, the production of pro-inflammatory cytokines and oxidative stress by monocyte-derived macrophages is responsible for the osteogenic transformation and mineralization of vascular/valvular cells. However, monocytes/macrophages show the ability to modify their phenotype, and consequently their functions, when facing environmental modifications. This plasticity complicates efforts to understand the pathogenesis of CVC-particularly in a CKD setting, where both uraemic toxins and CKD treatment may affect monocyte/macrophage functions and thereby influence CVC. Here, we review (i) the mechanisms by which each monocyte/macrophage subset either promotes or prevents CVC, and (ii) how both uraemic toxins and CKD therapies might affect these monocyte/macrophage functions.