Genome-wide association studies reconstructing chronic kidney disease.

Chronic kidney disease (CKD) is a major health problem with an increasing epidemiological burden, and is the 16th leading cause of years of life lost worldwide. It is estimated that more than 10% of the population have a variable stage of CKD, while about 850 million people worldwide are affected. Nevertheless, public awareness remains low, clinical access is inappropriate in many circumstances and medication is still ineffective due to the lack of clear therapeutic targets. One of the main issues that drives these problems is the fact that CKD remains a clinical entity with significant causal ambiguity. Beyond diabetes mellitus and hypertension, which are the two major causes of kidney disease, there are still many gray areas in the diagnostic context of CKD. Genetics nowadays emerges as a promising field in nephrology. The role of genetic factors in CKD's causes and predisposition is well documented and thousands of genetic variants are well established to contribute to the high burden of disease. Next-generation sequencing is increasingly revealing old and new rare variants that cause Mendelian forms of chronic nephropathy while genome-wide association studies (GWAS) uncover common variants associated with CKD-defining traits in the general population. In this article we review how GWAS has revolutionized-and continues to revolutionize-the old concept of CKD. Furthermore, we present how the investigation of common genetic variants with previously unknown kidney significance has begun to expand our knowledge on disease understanding, providing valuable insights into disease mechanisms and perhaps paving the way for novel therapeutic targets.

COVID-19 and cardiovascular disease in patients with chronic kidney disease.

Millions of people worldwide have chronic kidney disease (CKD). Affected patients are at high risk for cardiovascular (CV) disease for several reasons. Among various comorbidities, CKD is associated with the more severe forms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This is particularly true for patients receiving dialysis or for kidney recipients. From the start of the SARS-CoV-2 pandemic, several CV complications have been observed in affected subjects, spanning acute inflammatory manifestations, CV events, thrombotic episodes and arrythmias. Several pathogenetic mechanisms have been hypothesized, including direct cytopathic viral effects on the myocardium, endothelial damage and hypercoagulability. This spectrum of disease can occur during the acute phase of the infection, but also months after recovery. This review is focussed on the CV complications of coronavirus disease 2019 (COVID-19) with particular interest in their implications for the CKD population.

The Mitochondrial-Derived Peptide MOTS-c May Refine Mortality and Cardiovascular Risk Prediction in Chronic Hemodialysis Patients: A Multicenter Cohort Study.

INTRODUCTION: Uremic patients exhibit remarkably increased rates of mortality and cardiovascular (CV) events, but risk prediction in this setting remains difficult. Systemic mitochondrial dysfunction is pervasive in end-stage kidney disease and may contribute to CV complications. We tested the clinical significance of circulating MOTS-c, a small mitochondrial-derived peptide, as a biomarker for improving mortality and CV risk prediction in hemodialysis (HD) patients. METHODS: We conducted a prospective, observational, multicenter study on 94 prevalent HD patients. The study endpoint was a composite of all-cause mortality and non-fatal CV events. The diagnostic and prognostic capacities of predictive models based on cohort-related risk factors were tested before and after the inclusion of MOTS-c. RESULTS: MOTS-c levels were higher in HD patients than in controls (p < 0.001) and even more elevated (p = 0.01) in the 53 individuals experiencing the combined endpoint during follow-up (median duration: 26.5 months). MOTS-c was independently associated with the endpoint at either multivariate logistic (OR 1.020; 95% CI: 1.011-1.109; p = 0.03) or Cox regression analyses (HR 1.004; 95% CI: 1.000-1.025; p = 0.05) and the addition of this biomarker to prognostic models including the other cohort-related risk predictors (age, left ventricular mass, evidence of diastolic dysfunction, diabetes, pulse pressure) significantly improved the calibration, risk variability explanation, discrimination (receiver operating characteristic area under the curve from 0.727 to 0.743; C-index from 0.658 to 0.700), and particularly, the overall reclassification capacity (NRI 15.87%; p = 0.01). CONCLUSIONS: In HD patients, the mitochondrial-derived peptide MOTS-c may impart significant information to refine CV risk prediction, beyond cohort-related risk factors. Future investigations are needed to generalize these findings in larger and more heterogeneous cohorts.

Sex-Specific Differences in Kidney Function and Blood Pressure Regulation.

Premenopausal women generally exhibit lower blood pressure and a lower prevalence of hypertension than men of the same age, but these differences reverse postmenopause due to estrogen withdrawal. Sexual dimorphism has been described in different components of kidney physiology and pathophysiology, including the renin-angiotensin-aldosterone system, endothelin system, and tubular transporters. This review explores the sex-specific differences in kidney function and blood pressure regulation. Understanding these differences provides insights into potential therapeutic targets for managing hypertension and kidney diseases, considering the patient's sex and hormonal status.

Identification of Novel Independent Correlations between Cellular Components of the Immune System and Strain-Related Indices of Myocardial Dysfunction in CKD Patients and Kidney Transplant Recipients without Established Cardiovascular Disease.

The role of immune system components in the development of myocardial remodeling in chronic kidney disease (CKD) and kidney transplantation remains an open question. Our aim was to investigate the associations between immune cell subpopulations in the circulation of CKD patients and kidney transplant recipients (KTRs) with subclinical indices of myocardial performance. We enrolled 44 CKD patients and 38 KTRs without established cardiovascular disease. A selected panel of immune cells was measured by flow cytometry. Classical and novel strain-related indices of ventricular function were measured by speckle-tracking echocardiography at baseline and following dipyridamole infusion. In CKD patients, the left ventricular (LV) relative wall thickness correlated with the CD14++CD16- monocytes (ß = 0.447, p = 0.004), while the CD14++CD16+ monocytes were independent correlates of the global radial strain (ß = 0.351, p = 0.04). In KTRs, dipyridamole induced changes in global longitudinal strain correlated with CD14++CD16+ monocytes (ß = 0.423, p = 0.009) and CD4+ T-cells (ß = 0.403, p = 0.01). LV twist and untwist were independently correlated with the CD8+ T-cells (ß = 0.405, p = 0.02 and ß = -0.367, p = 0.03, respectively) in CKD patients, whereas the CD14++CD16+ monocytes were independent correlates of LV twist and untwist in KTRs (ß = 0.405, p = 0.02 and ß = -0.367, p = 0.03, respectively). Immune cell subsets independently correlate with left ventricular strain and torsion-related indices in CKD patients and KTRs without established CVD.

Albuminuria and cardiorenal risk.

PURPOSE OF REVIEW: This article explores the prognostic association of albuminuria with the risk of adverse health outcomes and also provides an overview of novel guideline-directed therapies that confer cardiorenal protection in chronic kidney disease (CKD) patients with or without type 2 diabetes. RECENT FINDINGS: Although the identification of CKD is based on the simultaneous assessment of estimated glomerular filtration rate and albuminuria, recent studies have shown that the regular screening rate for an increased urinary albumin-to-creatinine ratio is very low in daily clinical practice. Accordingly, a large proportion of high-risk patients with early-stage CKD remain unidentified, missing the opportunity to receive optimized treatment with novel agents that are effective in causing regression of albuminuria and in improving adverse cardiorenal outcomes. SUMMARY: The broader implementation of albuminuria assessment in daily clinical practice facilitates the identification of high-risk patients with early-stage CKD who are candidates for treatment with sodium-glucose co-transporter type 2 inhibitors, glucagon-like peptide-1 receptor agonists and the nonsteroidal mineralocorticoid receptor antagonist finerenone. These novel drug categories have modified the role of albuminuria from a powerful cardiorenal risk predictor to a modifiable target of therapy.

Coronary microcirculation and left ventricular diastolic function but not myocardial deformation indices are impaired early in patients with chronic kidney disease.

AIM: To investigate abnormalities in myocardial strain and classic echocardiographic indices and coronary flow reserve (CFR), in younger versus older CKD patients. METHODS: Sixty consecutive CKD patients (<60 years old n = 30, ≥60 years old n = 30) and 30 healthy controls (age- and gender-matched with younger CKD patients) were recruited. An echocardiographic assessment including myocardial strain indices (i.e. global longitudinal strain -GLS -, TWIST, UNTWIST rate) was performed at baseline and following dipyridamole administration in all participants. RESULTS: Younger CKD patients had higher E/e', left ventricular mass index and relative wall thickness and lower E' (p < .005 for all) compared to healthy controls. Older CKD patients had lower E/A and E' (p < .05 for both) compared to younger CKD patients; these differences did not remain significant after adjustment for age. CFR was higher in healthy controls compared to younger and older CKD patients (p < .05 for both) without a significant difference between CKD groups. There were no significant differences in GLS, TWIST or UNTWIST values among the three groups of patients. Dipyridamole-induced changes did not differ significantly among the three groups. CONCLUSIONS: Compared to healthy controls, impaired coronary microcirculation and left ventricular diastolic function, but not myocardial strain abnormalities, are found in young CKD patients and deteriorate with aging.

Microalbuminuria on admission for acute exacerbation of COPD as a predictor of all-cause mortality and future exacerbations.

OBJECTIVES: Microalbuminuria (MAB) is a sensitive biomarker of cardiovascular risk that is directly associated with cardiovascular events and mortality. Recent studies have evaluated the presence of MAB in patients with stable chronic obstructive pulmonary disease (COPD) or hospitalised for acute exacerbation of COPD (AECOPD). METHODS: We evaluated 320 patients admitted for AECOPD in respiratory medicine departments of two tertiary hospitals. On admission, demographic, clinical and laboratory values and COPD severity were assessed. Patients were evaluated monthly for 1 year, recording new AECOPD and death from any cause. RESULTS: Patients with documented MAB (urinary albumin excretion of 30-300 mg/24 hours) on admission had worse lung function (forced expiratory volume in 1 s, %) (mean (SD) 34.2 (13.6)% vs 61.5 (16.7)%), higher modified Medical Research Council (3.6 (1.2) vs 2.1 (0.8)), lower 6 min walk test (171 (63) vs 366 (104)) and more hospitalisation days (9 (2.8) vs 4.7 (1.9)) (p < 0.001 for all comparisons). MAB was also correlated with Global Initiative for Chronic Obstructive Lung Disease 2020 COPD stages (p < 0.001). In multivariate regression analysis, MAB was a significant predictor of longer hospitalisation duration (OR 6.847, 95% CI 3.050 to 15.370, p < 0.0001). Twelve-month follow-up revealed that patients with MAB experienced more AECOPDs (4.6 (3.6) vs 2.2 (3.5), p < 0.0001) and deaths, n (%) (52 (36.6) vs 14 (7.8), p < 0.001). Kaplan-Meier survival curves demonstrated that patients with MAB presented with increased mortality, AECOPD and hospitalisation for AECOPD risk at 1 year (p < 0.001 for all comparisons). CONCLUSIONS: The presence of MAB on admission for AECOPD was associated with more severe COPD and prolonged hospitalisation, as well as with higher rates of AECOPD and mortality risk at 1-year follow-up.

In Vitro Investigation of Platelet Dysfunction Induced by Osmotic Pressure Variations.

BACKGROUND: Severe variations in osmotic pressure are significant contributors to critical patient morbidity and mortality and might also affect platelet volume. We aimed to investigate possible osmotic-induced changes in mean platelet volume (MPV) and their possible effects on platelet aggregation activity (PLAG). METHODS: We induced experimental variations of serum osmolality in blood samples from healthy volunteers (heparinized whole blood, WB) and isolated platelets (Platelet Rich Plasma, PRP) by adding isotonic, hypertonic, and hypotonic solutions of saline/water (pH = 7.2-7.4). PLAG was tested in WB samples with Impedance Aggregometry (IA) and in PRP samples with Light Transmission Aggregometry (LTA) using three agonists Adenosine Diphosphate (ADP, 10 µΜ), Thrombin Receptor Activating Peptide (TRAP-6, 10 µΜ) and Arachidonic Acid (AA, 500 µΜ). Osmolality was either calculated using a formula or measured directly. RESULTS: We found almost identical osmolalities in WB and PRP preparations. Osmotic stress did not produce significant changes in MPV. In IA testing the hypotonic challenge of WB preparations produced significant reductions at 50 % (p = 0.056) (95 % CI: 11.2-2.4, in Ohms) of ADP and at 31 % (p = 0.017) (95 % CI: 13.4-8.6, in Ohms) of TRAP-6 -induced PLAG respectively. In PRP we did not observe any variations in PLAG with LTA. CONCLUSIONS: We conclude that in vitro hypotonic stress of WB samples has an inhibitory effect on the PAR-1 (TRAP-6 induced) pathway and on the P2Y12 (ADP induced) pathway and reflects a distinct in vivo effect of hypo-osmotic stress on WB human platelet preparations.

Epidemiology of Hypertension among Patients on Peritoneal Dialysis Using Standardized Office and Ambulatory Blood Pressure Recordings.

INTRODUCTION: Prior studies conducted in peritoneal dialysis (PD) patients in the late 1990s provided considerably variable estimates of the prevalence and control of hypertension. The present study aimed to investigate the current state of hypertension management in this high-risk population. METHODS: In 140 stable PD patients, we performed standardized automated office blood pressure (BP) measurements and 24-h ambulatory BP monitoring (ABPM) using the Mobil-O-Graph device (IEM, Germany). Office and ambulatory hypertension was diagnosed in patients with office BP ≥140/90 mm Hg and 24-h BP ≥130/80 mm Hg, respectively. Patients treated with ≥1 BP-lowering medications were also classified as hypertensives. RESULTS: The prevalence of office and ambulatory hypertension was 92.9% and 95%, respectively. In all, 92.1% of patients were being treated with an average of 2.4 BP-lowering medications daily. Adequate BP control was achieved in 52.3% and 38.3% of hypertensives by office BP and ABPM, respectively. The agreement between these 2 techniques in the identification of patients with BP levels above the diagnostic thresholds of hypertension was moderate (k-statistic: 0.524). In all, 5% of patients were normotensives with both techniques, 31.4% had controlled hypertension, 5% had white-coat hypertension, 19.3% had masked hypertension, and 39.3% had sustained hypertension. Isolated nocturnal hypertension was detected in 23.6% of patients, whereas no patient had isolated daytime hypertension. CONCLUSION: Among PD patients, hypertension is highly prevalent and remains often inadequately controlled. The use of ABPM enables the better classification of severity of hypertension and identification of isolated nocturnal hypertension, which is a common BP phenotype in the PD population.

Immunocryosurgery is a safe and feasible treatment for basal cell carcinoma and Bowen disease in renal transplant recipients.

Keratinocyte skin carcinomas (squamous cell carcinoma, basal cell carcinoma [BCC], Bowen disease [BD]) inflict significant morbidity and constitute a treatment challenge in renal transplant recipients (RTR). Immunocryosurgery has shown efficacy >95% in the treatment of BCC and BD in immunocompetent patients. The present study evaluated the safety, feasibility and efficacy, of immunocryosurgery in the treatment of BCC and BD in a series of RTR. During a 3-year period, biopsy-confirmed cases of BCC and BD were treated with a standard immunocryosurgery cycle (5 weeks daily imiquimod and a session of cryosurgery at day 14). Safety was evaluated by comparing graft function markers between immunocryosurgery treated RTR patients and matched controls. Ten BCC (8 nodular, 1 basosquamous, 1 superficial; diameter 6-14 mm; mean 9.2 mm) and nine BD disease lesions in nine patients (7 men, 2 women; age range: 54-70 years, mean: 62.1 years) were treated with immunocryosurgery and followed-up for two to 5 years. Five BCC were located on the "H area" of the face. No patient showed clinical or laboratory signs of transplant dysfunction during treatment or follow-up. Seven out of 10 BCC lesions cleared completely after one 5-week immunocryosurgery cycle, two cleared after repeat and intensified treatment cycles and one responded only partially (clearance rate: 90%). Seven out of nine BD lesions cleared after one 5-week immunocryosurgery cycle and one lesion after two cycles (clearance rate: 88.9%). In conclusion, immunocryosurgery is a safe, feasible and effective minimally invasive treatment alternative to standard surgical modalities for BCC and BD in RTR.

Microalbuminuria on admission for acute exacerbation of COPD as a predictor of all-cause mortality and future exacerbations.

OBJECTIVES: Microalbuminuria (MAB) is a sensitive biomarker of cardiovascular risk that is directly associated with cardiovascular events and mortality. Recent studies have evaluated the presence of MAB in patients with stable chronic obstructive pulmonary disease (COPD) or hospitalised for acute exacerbation of COPD (AECOPD). METHODS: We evaluated 320 patients admitted for AECOPD in respiratory medicine departments of two tertiary hospitals. On admission, demographic, clinical and laboratory values and COPD severity were assessed. Patients were evaluated monthly for 1 year, recording new AECOPD and death from any cause. RESULTS: Patients with documented MAB (urinary albumin excretion of 30-300 mg/24 hours) on admission had worse lung function (forced expiratory volume in 1 s, %) (mean (SD) 34.2 (13.6)% vs 61.5 (16.7)%), higher modified Medical Research Council (3.6 (1.2) vs 2.1 (0.8)), lower 6 min walk test (171 (63) vs 366 (104)) and more hospitalisation days (9 (2.8) vs 4.7 (1.9)) (p < 0.001 for all comparisons). MAB was also correlated with Global Initiative for Chronic Obstructive Lung Disease 2020 COPD stages (p < 0.001). In multivariate regression analysis, MAB was a significant predictor of longer hospitalisation duration (OR 6.847, 95% CI 3.050 to 15.370, p < 0.0001). Twelve-month follow-up revealed that patients with MAB experienced more AECOPDs (4.6 (3.6) vs 2.2 (3.5), p < 0.0001) and deaths, n (%) (52 (36.6) vs 14 (7.8), p < 0.001). Kaplan-Meier survival curves demonstrated that patients with MAB presented with increased mortality, AECOPD and hospitalisation for AECOPD risk at 1 year (p < 0.001 for all comparisons). CONCLUSIONS: The presence of MAB on admission for AECOPD was associated with more severe COPD and prolonged hospitalisation, as well as with higher rates of AECOPD and mortality risk at 1-year follow-up.

The Endothelial Glycocalyx as a Target of Ischemia and Reperfusion Injury in Kidney Transplantation-Where Have We Gone So Far?

The damage of the endothelial glycocalyx as a consequence of ischemia and/or reperfusion injury (IRI) following kidney transplantation has come at the spotlight of research due to potential associations with delayed graft function, acute rejection as well as long-term allograft dysfunction. The disintegration of the endothelial glycocalyx induced by IRI is the crucial event which exposes the denuded endothelial cells to further inflammatory and oxidative damage. The aim of our review is to present the currently available data regarding complex links between shedding of the glycocalyx components, like syndecan-1, hyaluronan, heparan sulphate, and CD44 with the activation of intricate immune system responses, including toll-like receptors, cytokines and pro-inflammatory transcription factors. Evidence on modes of protection of the endothelial glycocalyx and subsequently maintenance of endothelial permeability as well as novel nephroprotective molecules such as sphingosine-1 phosphate (S1P), are also depicted. Although advances in technology are making the visualization and the analysis of the endothelial glycocalyx possible, currently available evidence is mostly experimental. Ongoing progress in understanding the complex impact of IRI on the endothelial glycocalyx, opens up a new era of research in the field of organ transplantation and clinical studies are of utmost importance for the future.

A Systematic Review and Meta-Analysis of Pharmacogenetic Studies in Patients with Chronic Kidney Disease.

Chronic kidney disease (CKD) is an important global public health problem due to its high prevalence and morbidity. Although the treatment of nephrology patients has changed considerably, ineffectiveness and side effects of medications represent a major issue. In an effort to elucidate the contribution of genetic variants located in several genes in the response to treatment of patients with CKD, we performed a systematic review and meta-analysis of all available pharmacogenetics studies. The association between genotype distribution and response to medication was examined using the dominant, recessive, and additive inheritance models. Subgroup analysis based on ethnicity was also performed. In total, 29 studies were included in the meta-analysis, which examined the association of 11 genes (16 polymorphisms) with the response to treatment regarding CKD. Among the 29 studies, 18 studies included patients with renal transplantation, 8 involved patients with nephrotic syndrome, and 3 studies included patients with lupus nephritis. The present meta-analysis provides strong evidence for the contribution of variants harbored in the ABCB1, IL-10, ITPA, MIF, and TNF genes that creates some genetic predisposition that reduces effectiveness or is associated with adverse events of medications used in CKD.

The prognostic role of myocardial strain indices and dipyridamole stress test in renal transplantation patients.

INTRODUCTION: Renal transplantation (RT) increases survival in end-stage kidney disease patients but cardiovascular diseases remain the leading cause of morbidity and mortality. We evaluated the role of myocardial strain (2DSTE) indices and dipyridamole-induced (DIPSE) changes in echocardiographic parameters at baseline for the prediction of clinical events and echocardiographically assessed deterioration of cardiac function in a RT population. METHODS: Forty-five RT patients underwent an echocardiographic study at baseline including 2DSTE and DIPSE. If no cardiovascular/renal event occurred, patients were investigated at 3-year follow-up; eight patients presented a clinical event while 37 patients were re-evaluated. RESULTS: Coronary flow reserve (CFR) was abnormal in 24% of the population. DIPSE induced improvements in classic and 2DSTE systolic and diastolic echocardiographic indices including TWIST, UNTWIST, global longitudinal strain (GLS), and circumferential strain (P < .05 for all). Compared to baseline, deteriorations in E/E', LVEF, E', and TWIST were observed at follow-up (P < .05 for all). DIPSE-induced changes in GLS, global radial strain, and LVEF were associated with changes in these indices at follow-up (P < .05 for all). Higher LV mass index, E/E', and lower MAPSE, E', and CFR at baseline were associated with the occurrence of clinical events at follow-up (P < .05 for all). CONCLUSIONS: In RT patients, coronary vascular dysfunction (ie, low CFR) was associated with the occurrence of adverse events. DIPSE-induced changes in myocardial strain and classic echocardiographic indices could identify individuals with a subclinical deterioration in cardiac function at follow-up. This may indicate that DIPSE could serve as a means to assess myocardial reserve in this population.

Histological grading in primary membranous nephropathy is essential for clinical management and predicts outcome of patients.

AIMS: Diagnosis of primary membranous nephropathy (PMN) is mainly based on immunofluorescence/immunohistochemistry findings. However, assessment of specific features on optical microscopy can help to estimate the severity of the disease, guide treatment and predict the response. The aim of this study was to identify, classify and grade the precise histological findings in PMN to predict renal function outcome and guide treatment. METHODS AND RESULTS: Histological parameters, including focal segmental sclerosis (FSGS), tubular atrophy (TA), interstitial fibrosis (IF) and vascular hyalinosis (VH), were re-evaluated in 752 patients with PMN. Their predictive value was estimated separately, and also in a combination score (FSTIV) graded from 0 to 4. Finally, the impact of histology was assessed in the response to immunosuppressive treatment. Mean age of patients was 53.3 (15-85) years and most presented with nephrotic syndrome. FSGS was present in 32% and VH in 51% of the patients, while TA and IF were graded as stage ≥1 in 52% and 51.4%, respectively. The follow-up period was 122.3 (112-376) months. FSGS, TA and IF and VH were associated with impaired renal function at diagnosis (P = 0.02, P < 0.0001, P = 0.001 and P = 0.02, respectively) and at the end of follow-up (P = 0.004, P < 0.0001, P < 0.0001 and P = 0.04, respectively). In multiple regression and binary logistic analysis, the presence of FSGS and degree of TA were the most significant parameters predicting renal function outcome, defined either by eGFR (end), FSGS (r = 0.6, P < 0.0001) and TA (r = 0.6, P < 0.0001), or by the endpoint of >50% eGFR reduction, FSGS (P = 0.001) and TA (P = 0.02). Also, patients presented with FSGS, IF, VH and/or with FSTIV > 1 could benefit from immunosuppression, regardless of clinical presentation. CONCLUSIONS: The presence and degree of four histological indices, FSGS, VH, TA and IF, assessed separately or in combination, and FSTIV score not only predict renal function outcome after long-term follow-up, but can also help in the choice of appropriate treatment. Decisions concerning immunosuppressive treatment can be guided by pathology regardless of clinical findings.

Oxidative Stress in the Pathogenesis and Evolution of Chronic Kidney Disease: Untangling Ariadne's Thread.

Amplification of oxidative stress is present since the early stages of chronic kidney disease (CKD), holding a key position in the pathogenesis of renal failure. Induction of renal pro-oxidant enzymes with excess generation of reactive oxygen species (ROS) and accumulation of dityrosine-containing protein products produced during oxidative stress (advanced oxidation protein products-AOPPs) have been directly linked to podocyte damage, proteinuria, and the development of focal segmental glomerulosclerosis (FSGS) as well as tubulointerstitial fibrosis. Vascular oxidative stress is considered to play a critical role in CKD progression, and ROS are potential mediators of the impaired myogenic responses of afferent renal arterioles in CKD and impaired renal autoregulation. Both oxidative stress and inflammation are CKD hallmarks. Oxidative stress promotes inflammation via formation of proinflammatory oxidized lipids or AOPPs, whereas activation of nuclear factor κB transcription factor in the pro-oxidant milieu promotes the expression of proinflammatory cytokines and recruitment of proinflammatory cells. Accumulating evidence implicates oxidative stress in various clinical models of CKD, including diabetic nephropathy, IgA nephropathy, polycystic kidney disease as well as the cardiorenal syndrome. The scope of this review is to tackle the issue of oxidative stress in CKD in a holistic manner so as to provide a future framework for potential interventions.

Association of the Inactive Circulating Matrix Gla Protein with Vitamin K Intake, Calcification, Mortality, and Cardiovascular Disease: A Review.

Matrix Gla Protein (MGP), a small Gla vitamin K-dependent protein, is the most powerful natural occurring inhibitor of calcification in the human body. To become biologically active, MGP must undergo vitamin K-dependent carboxylation and phosphorylation. Vitamin K deficiency leads to the inactive uncarboxylated, dephosphorylated form of MGP (dpucMGP). We aimed to review the existing data on the association between circulating dpucMGP and vascular calcification, renal function, mortality, and cardiovascular disease in distinct populations. Moreover, the association between vitamin K supplementation and serum levels of dpucMGP was also reviewed.

Oxidative Stress and the Kidney in the Space Environment.

In space, the special conditions of hypogravity and exposure to cosmic radiation have substantial differences compared to terrestrial circumstances, and a multidimensional impact on the human body and human organ functions. Cosmic radiation provokes cellular and gene damage, and the generation of reactive oxygen species (ROS), leading to a dysregulation in the oxidants⁻antioxidants balance, and to the inflammatory response. Other practical factors contributing to these dysregulations in space environment include increased bone resorption, impaired anabolic response, and even difficulties in detecting oxidative stress in blood and urine samples. Enhanced oxidative stress affects mitochondrial and endothelial functions, contributes to reduced natriuresis and the development of hypertension, and may play an additive role in the formation of kidney stones. Finally, the composition of urine protein excretion is significantly altered, depicting possible tubular dysfunction.

Intact FGF23 and α-Klotho during acute inflammation/sepsis in CKD patients.

BACKGROUND: High FGF23 and low α-Klotho levels associate with systemic inflammation and reduced nitric oxide (NO) bioavailability, but the dynamics of this relationship in patients with CKD has not been investigated. METHODS: We sequentially measured serum intact FGF23 and carboxyl-terminal (iFGF23, cFGF23), the iFGF23/cFGF23 ratio, αKlotho, biomarkers of inflammation (hs-CRP, IL-6 and TNF-α) and sepsis (procalcitonin), nitrotyrosine (reflecting NO synthesis and oxidative stress), serum iron and ferritin and CKD-MBD biomarkers, PTH, 25(OH)VD, 1,25(OH)2 VD at peak of intercurrent sepsis and after complete resolution in a series of 17 patients with CKD. RESULTS: At peak infection, biomarkers of inflammation/sepsis, ferritin and nitrotyrosine were all very high (all P < 0·01) and declined towards the normal range thereafter (P < 0·01). iFGF23 was 191 ± 10 pg/ml (geometric mean, SD) and doubled to 371 ± 8 pg/ml (P = 0·003) after the resolution of infection, while cFGF23 did not change (246 ± 5 pg/mL vs. 248 ± 5 pg/mL, P = 0·50). As a consequence, the iFGF23/cFGF23 ratio, an indicator of the proteolytic cleavage of the FGF23 molecule, was 0·78 ± 3·87 at peak infection and increased to 1·49 ± 3·00 after resolution of infection (P < 0·001). In contrast, serum α-Klotho levels were upregulated at peak infection (peak infection: 526 ± 4 pg/ml, postinfection: 447 ± 4 pg/ml, P = 0·001). The eGFR, PTH and vitamin D did not change significantly throughout. CONCLUSIONS: Acute inflammation/sepsis suppresses the active form of FGF23 and activates α-Klotho, the latter effect being likely attributable to enhance proteolysis of FGF23 molecule. iFGF23 downregulation and α-Klotho upregulation during acute sepsis may participate into the counter-regulatory response to severe inflammation in CKD patients with sepsis.