Association of serum fetuin-A levels with mortality in dialysis patients

Screening of novel biomarkers for acute kidney transplant rejection using DIA-MS based proteomics

BACKGROUND

Kidney transplantation is the preferred treatment for patients with end-stage renal disease. However, acute rejection poses a threat to the graft long-term survival. The aim of this study was to identify novel biomarkers to detect acute kidney transplant rejection.

METHODS

The serum proteomic profiling of kidney transplant patients with T cell-mediated acute rejection (TCMR) and stable allograft function (STA) was analyzed using data-independent acquisition mass spectrometry (DIA-MS). The differentially expressed proteins (DEPs) of interest were further verified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 131 DEPs were identified between STA and TCMR patients, 114 DEPs were identified between mild and severe TCMR patients. The verification results showed that remarkable higher concentrations of serum amyloid A protein 1 (SAA1) and insulin like growth factor binding protein 2 (IGFBP2), and lower fetuin-A (AHSG) concentration were found in TCMR patients when compared with STA patients. We also found higher SAA1 concentration in severe TCMR group when compared with mild TCMR group. The receiver operating characteristics (ROC) analysis further confirmed that combination of SAA1, AHSG, and IGFBP2 had excellent performance in the acute rejection diagnosis.

CONCLUSIONS

Our data demonstrated that serum SAA1, AHSG, and IGFBP2 could be effective biomarkers for diagnosing acute rejection after kidney transplantation. DIA-MS has great potential in biomarker screening of kidney transplantation.

The Relationship of Fetuin-A with Coronary Calcification, Carotid Atherosclerosis, and Mortality Risk in Non-Dialysis Chronic Kidney Disease

Objective

This study investigated the relationship of fetuin-A with coronary calcification, carotid atherosclerosis, and mortality risk in non-dialysis chronic kidney disease (CKD).

Methods

The study included 135 adult patients with CKD at stages 3-5, who were divided into coronary artery calcification (CAC) and non-CAC groups. We excluded current smokers and individuals with diabetes mellitus, inflammatory conditions, liver diseases, acute kidney failure, chronic hemodialysis, and cancer. We conducted kidney function tests, complete blood counts, and measured serum levels of fetuin-A, tumor necrosis factor-alpha (TNF-α), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), total cholesterol (TC), total triglycerides (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Cardiac spiral computed tomography was used to calculate the CAC score, employing the Agatston method. Carotid ultrasonography was performed to assess carotid intima-media thickness (CIMT) and to detect the presence of plaques.

Results

CAC patients had considerably higher levels of TNF-α (p<0.001), IL-6 (p<0.001), hs-CRP (p=0.006), TC, TG, parathyroid hormone (PTH) (p<0.001) and phosphorus (p<0.001) than non-CAC patients. They also had significantly lower levels of fetuin-A (p<0.001). Fetuin-A was considerably lower in CKD subgroups as CKD progressed. Fetuin-A (p=0.046), age (p=0.009), TNF-α (p=0.027), IL-6 (p=0.005), TG (p=0.002), PTH (p=0.002), and phosphorus (p=0.004) were significant predictors of CAC. CAC and fetuin-A were strong predictors of all-cause mortality and cardiovascular (CV) mortality. Fetuin-A was a significant predictor of CIMT (p=0.045).

Conclusion

Fetuin-A reliably predicted CAC and CIMT. Fetuin-A and CAC emerged as significant risk factors for all-cause and CV mortality in non-dialysis CKD.

Vascular calcification inhibitors and cardiovascular events in peritoneal dialysis patients

The prevalence of cardiovascular diseases is high among patients with chronic kidney disease (CKD) and peritoneal dialysis (PD) patients, which increases morbidity and mortality in this population and represents a significant financial burden for both the patients and the healthcare systems. Vascular calcification (VC) is associated with increased morbidity and mortality and VC risk is higher in patients with CKD than in healthy individuals. Calcification inhibitors, compounds that inhibit VC, were discovered as a result of efforts to explain why some patients are spared. It was found that certain proteins (e.g., fetuin-A, osteopontin, osteoprotegerin, bone morphogenetic protein-7) inhibit calcification in dialysis patients. In this narrative review, we provide an overview of known calcification inhibitors, describe the relevant regulatory mechanisms, and discuss their relation to VC development in PD patients.

Phosphate in Cardiovascular Disease: From New Insights Into Molecular Mechanisms to Clinical Implications

Hyperphosphatemia is a common feature in patients with impaired kidney function and is associated with increased risk of cardiovascular disease. This phenomenon extends to the general population, whereby elevations of serum phosphate within the normal range increase risk; however, the mechanism by which this occurs is multifaceted, and many aspects are poorly understood. Less than 1% of total body phosphate is found in the circulation and extracellular space, and its regulation involves multiple organ cross talk and hormones to coordinate absorption from the small intestine and excretion by the kidneys. For phosphate to be regulated, it must be sensed. While mostly enigmatic, various phosphate sensors have been elucidated in recent years. Phosphate in the circulation can be buffered, either through regulated exchange between extracellular and cellular spaces or through chelation by circulating proteins (ie, fetuin-A) to form calciprotein particles, which in themselves serve a function for bulk mineral transport and signaling. Either through direct signaling or through mediators like hormones, calciprotein particles, or calcifying extracellular vesicles, phosphate can induce various cardiovascular disease pathologies: most notably, ectopic cardiovascular calcification but also left ventricular hypertrophy, as well as bone and kidney diseases, which then propagate phosphate dysregulation further. Therapies targeting phosphate have mostly focused on intestinal binding, of which appreciation and understanding of paracellular transport has greatly advanced the field. However, pharmacotherapies that target cardiovascular consequences of phosphate directly, such as vascular calcification, are still an area of great unmet medical need.

Differential associations of fetuin-A and calcification propensity with cardiovascular events and subsequent mortality in patients undergoing hemodialysis

Background

Fetuin-A inhibits precipitation of calcium-phosphate crystals by forming calciprotein particles (CPP). A novel T50 test, which measures transformation time from primary to secondary CPP, is an index for calcification propensity. Both lower fetuin-A and shorter T50 levels were associated with cardiovascular disease (CVD) risk in patients with chronic kidney disease (CKD). Extremely high risk for CVD death in advanced CKD patients consists of high-incidental CVD event and high mortality after CVD event. To date, it is unclear whether fetuin-A and/or T50 can equally predict each CVD outcome.

Methods

This prospective cohort study examined patients undergoing maintenance hemodialysis. The exposures were fetuin-A and T50. The outcomes of interests were new CVD events and subsequent deaths. The patients were categorized into tertiles of fetuin-A or T50 (T1 to T3).

Results

We identified 190 new CVD events during the 5-year follow-up of the 513 patients and 59 deaths subsequent to the CVD events during 2.5-year follow-up. A lower fetuin-A but not T50 was significantly associated with new CVD events [subdistribution hazard ratio (HR) 1.73, 95% confidence interval (CI) 1.15-2.61, P = .009 for T1 vs T3]. In contrast, a shorter T50 but not fetuin-A was a significant predictor of deaths after CVD events (HR 3.31, 95% CI 1.42-7.74, P = .006 for T1 + T2 vs T3). A lower fetuin-A was predictive of new CVD events, whereas a shorter T50 was more preferentially associated with subsequent death.

Conclusion

These results indicate that fetuin-A and T50 are involved in cardiovascular risk in different manners.

Pathophysiology and Clinical Impacts of Chronic Kidney Disease on Coronary Artery Calcification

The global prevalence of chronic kidney disease (CKD) has increased in recent years. Adverse cardiovascular events have become the main cause of life-threatening events in patients with CKD, and vascular calcification is a risk factor for cardiovascular disease. Vascular calcification, especially coronary artery calcification, is more prevalent, severe, rapidly progressive, and harmful in patients with CKD. Some features and risk factors are unique to vascular calcification in patients with CKD; the formation of vascular calcification is not only influenced by the phenotypic transformation of vascular smooth muscle cells, but also by electrolyte and endocrine dysfunction, uremic toxin accumulation, and other novel factors. The study on the mechanism of vascular calcification in patients with renal insufficiency can provide a basis and new target for the prevention and treatment of this disease. This review aims to illustrate the impact of CKD on vascular calcification and to discuss the recent research data on the pathogenesis and factors involved in vascular calcification, mainly focusing on coronary artery calcification, in patients with CKD.

Level of Serum Fetuin-A Correlates with Heart Rate in Obstructive Sleep Apnea Patients without Metabolic and Cardiovascular Comorbidities

Obstructive sleep apnea (OSA) is the most common type of sleep-induced breathing disorder in the adult population and significantly affects the condition of the cardiovascular system. Fetuin-A (Fet-A) is a hepato- and adipokine, which prevents vessel calcification, and its level correlates with atherogenesis and metabolic disorders. The associations of cardiovascular diseases (CVD) both with OSA, which increases CVD risk, and Fet-A, which prevents CVD, justify the question of their mutual interactions in patients with OSA. Therefore, we sought to analyze Fet-A as an early biomarker of CVD risk in OSA patients without metabolic and cardiovascular comorbidities except for properly controlled arterial hypertension. We have found that in these patients, OSA does not appear to directly affect Fet-A levels. However, high Fet-A levels were more common in the group of patients with OSA, and the hypopnea index was significantly higher among subjects with the highest Fet-A levels. The level of Fet-A in OSA patients positively correlates with pulse rate, and it does not correlate with pulse pressure in this group unlike in the control group, where such a relationship exists. To our best knowledge, this is the first study to analyze this relationship in OSA patients without any significant cardiovascular comorbidities.

Decreases in hepatokine Fetuin-A levels are associated with hepatic hypoperfusion and predict cardiac outcomes in patients with heart failure

BACKGROUND

Interactions of the heart and the liver remain to be fully understood in the pathophysiology of heart failure (HF). Hepatokines are proteins synthesized and secreted from the liver and regulate systemic metabolisms of peripheral tissues. This study sought to clarify the clinical relevance of hepatokine Fetuin-A in patients with HF.

METHODS AND RESULTS

We enrolled 217 participants including 187 hospitalized patients with HF and 30 control subjects who were sought with a comparable age- and sex profile and who had never had HF or structural cardiac abnormalities. First, we examined the levels of Fetuin-A and found that its levels were significantly lower in patients with HF than in the controls. Next, HF patients were categorized into four groups based on hepatic hemodynamics assessed by abdominal ultrasonography which determines liver hypoperfusion by peak systolic velocity (PSV) of the celiac artery and liver stiffness by shear wave elastography (SWE). Fetuin-A levels were significantly decreased in HF patients with liver hypoperfusion compared to those without, but were not different between HF patients with and without elevated liver stiffness. Correlation analysis revealed that circulating Fetuin-A was positively correlated with PSV of the celiac artery but not with SWE of the liver. Kaplan-Meier analysis demonstrated that HF patients with lower Fetuin-A levels were significantly associated with increased adverse outcomes including cardiac deaths and decompensated HF.

CONCLUSIONS

Liver-derived hepatokine Fetuin-A may be a novel target involved in the cardio-hepatic interactions, as well as a useful biomarker for predicting the prognosis in patients with HF.

Association of Fetuin-A with Thr256Ser exon polymorphism of α2-Heremans Schmid Glycoprotein (AHSG) gene in type 2 diabetic patients with overt nephropathy

BACKGROUND

Circulatory Fetuin-A has been well reported to elevate the risk for Diabetic Nephropathy (DN) and is associated with many vascular complications. Compelling reports have well documented that the circulatory levels of Fetuin-A directly have an impact on its AHSG (α2- Heremans- Schmid Glycoprotein) gene single nucleotide polymorphisms (SNP). Thus, in this study among the South Indian T2DM population, we aim to explore the association of AHSG Thr256Ser (rs4918) SNP in subjects with DN and correlate with the circulatory levels of Fetuin-A at various stages of DN patients.

METHODS

A total of 975 subjects were recruited, such as Group-I, consisting of Controls (n = 300), Group-II, with normoalbuminuria (n = 300), Group-IIIa, with incipient microalbuminuria (n = 195), Group-IIIb, with persistent macroalbuminuria (n = 180)] and were subjected for genotyping using PCR-Restriction Fragment Length Polymorphism (RFLP). Circulatory Fetuin-A was measured using sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

The 'G' allele of AHSG exon-7 (C/G) SNP is significantly concomitant and conferred significant risk for normoalbuminuria subjects. In the DN subjects, the 'G' allele showed the risk for persistent macroalbuminuria. A noticeable stepwise decrease was evidenced in the circulatory Fetuin-A among persistent macroalbuminuria over incipient microalbuminuria from normoalbuminuria. Further, the circulatory Fetuin-A was lowered in DN subjects with mutant GG genotype than the wild CC.

CONCLUSION

AHSG Thr256Ser (rs4918) SNP was associated with renal complications among South Indian T2DM subjects.

Níveis mais Baixos de Fetuína-A Sérica estão Associados a um Maior Risco de Mortalidade em Dez Anos em Pacientes com Infarto do Miocárdio por Supradesnivelamento do Segmento ST

Fundamento

A fetuína-A é um fator anti-inflamatório e anticalcificação envolvido no curso da doença arterial coronariana (DAC). Em alinhamento com essas funções, investigou-se a fetuína-A como marcador de risco cardiovascular em vários estudos. Porém, a associação entre a fetuína-A e o prognóstico dos pacientes com DAC ainda é controversa.

Objetivos

O presente estudo foi conduzido para identificar a associação entre o nível de fetuína-A sérica e doença cardiovascular (DCV) de longo prazo e a mortalidade global por infarto do agudo do miocárdio por supradesnivelamento do segmento ST (STEMI).

Métodos

Foram cadastrados no estudo cento e oitenta pacientes consecutivos com STEMI. A população do estudo foi dividida em subgrupos (mais baixo, ≤288 µg/ml; e mais alto, >288 µg/ml) de acordo com a mediana do nível de fetuína-A. Dados de acompanhamento clínico foram obtidos por contato telefônico anual com pacientes ou familiares. As causas das mortes também foram confirmadas pelo banco de dados de saúde nacional. P-valores bilaterais <0,05 foram considerados estatisticamente significativos.

Resultados

Durante um acompanhamento médio de 10 anos, foram registradas 71 mortes, das quais 62 foram devidas a DCV. Identificou-se um índice de mortalidade global e por DCV significativamente mais alto no grupo com nível de fetuína-A mais baixo que no grupo com nível de fetuína-A mais alto (44% versus 24%, p= 0,005; 48% versus 31%, p= 0,022, respectivamente). Nas análises de risco proporcionais por regressão de Cox, detectou-se que a fetuína-A era um preditor independente de mortalidade global e por DCV.

Conclusões

A baixa concentração de fetuína-A está associada ao prognóstico de longo prazo ruim pós-STEMI, independentemente de fatores de risco cardiovascular tradicionais. Nossos achados fortaleceram estudos prévios demonstrando consistentemente o papel determinante dos mediadores anti-inflamatórios em síndromes coronárias agudas.

The relationship between calcification inhibitor levels in chronic kidney disease and the development of atherosclerosis

Aim

We aimed to investigate the factors affecting the development of atherosclerosis and the role of calcification inhibitors fetuin-A, matrix-Gla protein (MGP), osteoprotegerin (OPG) in atherosclerosis progress.

Material and methods

The study was planned to investigate the relationship of serum OPG, MGP and fetuin-A levels with the development of atherosclerosis in the stage 2–3–4–5 chronic kidney disease (CKD) patients who did not require dialysis treatment.

Results

32 (17 female, 15 male) healthy individuals and 92 (49 females, 43 males) CKD patients were included. The mean carotid intima-media thickness (CIMT), C-reactive protein (CRP), fetuin-A, OPG and MGP of the two groups were compared statistically. In CKD patients, age, body mass index (BMI), CRP, triglyceride, urea, systolic blood pressure (SBP), fasting blood sugar have a positive linear relationship, fetuin-A, OPG, GFR have a negative linear relationship with CIMT. The mean CIMT, right CIMT, left CIMT, blood urea, CRP, urinary albumin excretion creatinine and age show a negative linear relationship with fetuin-A.

Conclusion

Fetuin-A levels begin to decline from the early stages of CKD and are significantly lower in patients with atherosclerosis as expressed with CIMT. This suggests that fetuin-A may be used as an early marker in CKD for increased cardiovascular risk. Early recognition of these risk factors is important and large-scale studies on vascular calcification inhibitors are needed.

Effects of fetuin-A-containing calciprotein particles on posttranslational modifications of fetuin-A in HepG2 cells

Fetuin-A is an inhibitor of ectopic calcification that is expressed mainly in hepatocytes and is secreted into the circulation after posttranslational processing, including glycosylation and phosphorylation. The molecular weight (MW) of fully modified fetuin-A (FM-fetuin-A) is approximately 60 kDa in an immunoblot, which is much higher than the estimated MW by amino acid sequence. Under conditions of calcification stress such as advanced stage chronic kidney disease, fetuin-A prevents calcification by forming colloidal complexes, which are referred to as calciprotein particles (CPP). Since the significance of CPP in this process is unclear, we investigated the effect of synthetic secondary CPP on the level of FM-fetuin-A in HepG2 cells. Secondary CPP increased the level of FM-fetuin-A in dose- and time-dependent manners, but did not affect expression of mRNA for fetuin-A. Treatment with O- and/or N-glycosidase caused a shift of the 60 kDa band of FM-fetuin-A to a lower MW. Preincubation with brefeldin A, an inhibitor of transport of newly synthesized proteins from the endoplasmic reticulum to the Golgi apparatus, completely blocked the secondary CPP-induced increase in FM-fetuin-A. Treatment with BAPTA-AM, an intracellular calcium chelating agent, also inhibited the CPP-induced increase in the FM-fetuin-A level. Secondary CPP accelerate posttranslational processing of fetuin-A in HepG2 cells.

The cardiovascular-dialysis nexus: the transition to dialysis is a treacherous time for the heart

Chronic kidney disease (CKD) patients require dialysis to manage the progressive complications of uraemia. Yet, many physicians and patients do not recognize that dialysis initiation, although often necessary, subjects patients to substantial risk for cardiovascular (CV) death. While most recognize CV mortality risk approximately doubles with CKD the new data presented here show that this risk spikes to >20 times higher than the US population average at the initiation of chronic renal replacement therapy, and this elevated CV risk continues through the first 4 months of dialysis. Moreover, this peak reflects how dialysis itself changes the pathophysiology of CV disease and transforms its presentation, progression, and prognosis. This article reviews how dialysis initiation modifies the interpretation of circulating biomarkers, alters the accuracy of CV imaging, and worsens prognosis. We advocate a multidisciplinary approach and outline the issues practitioners should consider to optimize CV care for this unique and vulnerable population during a perilous passage.

Positive Associations between Adipocyte Fatty Acid-Binding Protein Level and Central Arterial Stiffness in Peritoneal Dialysis Patients

Background

Adipocyte fatty acid-binding protein (A-FABP) plays essential roles in lipolysis, insulin resistance, and atherosclerosis. This study aimed to evaluate the relationship between serum A-FABP levels and carotid-femoral pulse wave velocity (cfPWV) in peritoneal dialysis (PD) patients.

Methods

This study obtained fasting blood samples from 76 PD patients. A validated tonometry system was used to measure cfPWV. Patients with cfPWV values >10 m/s were classified into the high arterial stiffness group, whereas patients with values ≤10 m/s were classified into the low arterial stiffness group, according to the ESH-ESC 2013 guidelines. Serum A-FABP levels were measured using a commercial enzyme-linked immunosorbent assay kit.

Results

Twenty-five (32.9%) of the 76 PD patients were classified in the high arterial stiffness group. Compared with the patients in the low arterial stiffness group, the high arterial stiffness group was older (P = 0.002) and had a longer PD vintage (P = 0.011), higher diastolic blood pressure (DBP, P = 0.036), higher fasting glucose levels (P = 0.012), higher serum C reactive protein levels (P = 0.001), and higher serum A-FABP levels (P < 0.001). A multivariate logistic regression analysis of the factors significantly associated with central arterial stiffness revealed that A-FABP (odds ratio (OR): 1.165, 95% confidence interval (CI): 1.056–1.284, P = 0.002), age (OR: 1.423, 95% CI: 1.153–1.757, P = 0.001), PD vintage (OR: 1.049, 95% CI: 1.015–1.085, P = 0.005), and DBP (OR: 1.152, 95% CI: 1.033–1.285, P = 0.011) were independent predictors of central arterial stiffness in PD patients. Furthermore, serum A-FABP levels (β = 0.476, adjusted R² change: 0.197, P < 0.001) were significantly positively correlated with cfPWV according to the multivariable forward stepwise linear regression analysis.

Conclusions

A-FABP levels are an independent marker of central arterial stiffness in PD patients.

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.

Biomarkers of vascular calcification in serum

Over the last decades, the association between vascular calcification (VC) and all-cause/cardiovascular mortality, especially in patients with high atherogenic status, such as those with diabetes and/or chronic kidney disease, has been repeatedly highlighted. For over a century, VC has been noted as a passive, degenerative, aging process without any treatment options. However, during the past decades, studies confirmed that mineralization of the arteries is an active, complex process, similar to bone genesis and formation. The main purpose of this review is to provide an update of the existing biomarkers of VC in serum and develop the various pathogenetic mechanisms underlying the calcification process, including the pivotal roles of matrix Gla protein, osteoprotegerin, bone morphogenetic proteins, fetuin-a, fibroblast growth-factor-23, osteocalcin, osteopontin, osteonectin, sclerostin, pyrophosphate, Smads, fibrillin-1 and carbonic anhydrase II.

Association of serum FGF-23, klotho, fetuin-A, osteopontin, osteoprotegerin and hs-CRP levels with coronary artery disease

Environmental, genetic, oxidative and biochemical factors play an important role in the atherosclerotic process. We investigated the association of serum fibroblast growth factor (FGF-23), klotho, fetuin-A, osteoprotegerin (OPG), osteopontin (OPN) and high-sensitive-CRP (Hs-CRP) markers with coronary artery disease and whether one was superior to others or not. A study group of 52 patients with coronary artery disease (CAD) and a control group of 30 patients with angiographically normal epicardial coronary arteries were included in the study. Serum FGF-23, klotho, fetuin-A, OPN, OPG and Hs-CRP marker levels were studied. Patients with CAD were classified in two groups as low (SYNTAX ≤22, n = 29) and moderate-high (SYNTAX ≥ 23, n = 23) according to anatomic SYNTAX score. FGF-23 (p = .033), klotho (p < .001), fetuin-A (p = .005) and OPG (p = .001) serum marker levels were significantly lower in CAD patients than the control group. Serum levels of FGF-23 (p = .012), klotho (p = .001), fetuin-A (p = .015) and OPG (p = 0.002) were significantly different between SYNTAX tertiles and control group. Klotho (p = .025, odd ratio (OR) = 0.542, 95% confidence interval (CI): 0.317-0.926) and HT (p = .004, OR = 34.598, 95%CI:1.054-1135.657) were the independent predictors of CAD presence. Serum klotho levels of 91.48 pmol/L predicts the presence of CAD with 60% sensitivity and 96.55% specificity (p < .001, area under curve = 0.864, 95% CI = 0.768, 0.931). We found that serum klotho level is an independent predictor of presence, extent and severity of CAD.

Circulating Fetuin-A and Risk of All-Cause Mortality in Patients With Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Background: Investigations on the association of circulating fetuin-A with all-cause mortality risk in patients with chronic kidney disease (CKD) are conflicting. This meta-analysis aimed to provide a comprehensive estimation of the relationship between fetuin-A and all-cause mortality in CKD patients.

Methods: A systematic literature search was performed in PubMed, EMBASE, and The Cochrane Library up until 12 December 2018. Hazard risk (HR) and 95% confidence interval (CI) were pooled using random-effect or fixed-effect model models.

Results: A total of 13 studies comprising 5,169 CKD patients were included in the meta-analysis. In a comparison of individuals in the bottom third vs. the top third of baseline fetuin-A levels, the pooled multivariate-adjusted HR for the risk of all-cause mortality was 1.92 (95% CI 1.31–2.80), and the significant association was observed only in dialysis patients, but not non-dialysis patients. When fetuin-A was treated as continuous variables, per 0.1 g/L increase of fetuin-A levels was associated with a 8% lower mortality risk in dialysis patients (HR 0.92, 95% CI 0.87–0.97, p = 0.001), but per 0.01 g/L was not. Sensitivity analysis indicated the association was not adjusted by diabetes and inflammation.

Conclusion: Lower fetuin-A levels are associated with an increased risk of all-cause mortality independent of diabetes and inflammation in dialysis patients, and there may be a dose-response relationship between them.

Serum fetuin-A is associated with the components of MIAC(malnutrition, inflammation, atherosclerosis, calcification) syndrome in different stages of chronic kidney disease

Background/aim

Fetuin-A, a circulating inhibitor of calcification, is a marker of inflammatory-nutritional state. We evaluated the association between serum fetuin-A levels and vascular calcification, intima-media thickness, and nutritional and inflammatory markers in different stages of chronic kidney disease (CKD).

Materials and methods

CKD patients were sampled for calcium-phosphate parameters and nutritional and inflammatory markers [highly sensitive C-reactive protein (hs-CRP)], and serum fetuin-A levels. Intima-media thicknesses of the common carotid arteries (CIMT) were measured. Peripheral artery calcification scores were obtained.

Results

A total of 238 patients were included in the study. Fetuin-A levels in patients with end-stage renal disease were significantly lower than those in patients with stage-3 and stage-4 CKD (stage-5 vs. stage-4, P < 0.001; stage-5 vs. stage-3, P < 0.001). Fetuin-A was negatively correlated with creatinine (P < 0.001), Ca × P product (P < 0.001), hs-CRP (P = 0.01), vascular calcification score (P < 0.001), and CIMT (P < 0.001), and positively correlated with BMI (P < 0.001, r = 0.30) and serum albumin (P < 0.001).

Conclusion

Lower levels of fetuin-A were associated with higher vascular calcification scores, CIMT, hs-CRP levels, and lower BMI and albumin. Fetuin-A deficiency may be a key element for MIAC syndrome.

Cardiovascular Autonomic Neuropathy and its Association with Cardiovascular and All-cause Mortality in Patients with End-stage Renal Disease

Background End-stage renal disease frequently leads to increased cardiovascular mortality. Cardiovascular autonomic neuropathy (CAN) may be predictive of cardiac arrhythmias and sudden cardiac death in patients with end-stage renal disease. Methods A total of 70 patients with end-stage renal disease were included in the study. The assessment of cardiac dysautonomia was based on the four standardized tests performed at the baseline and, again, at the end of the study. The criteria for CAN included at least two abnormal test results. Results Fifty of 70 patients completed the study and were followed-up after one year. Out of the 50 patients, 44 (88%) had CAN at baseline. Twelve (24%) patients died at the one-year follow-up. Sudden cardiac death was reported in seven out of 12 (58%) patients. All seven patients who died had high dysautonomia scores (three abnormal tests) at the baseline. There was a significantly higher percentage of patients with all four abnormal tests amongst patients who died of any cause (56% vs. 17%; RR 6.07, 95% CI 1.29-28.49; p-value 0.02) or due to sudden cardiac death (43% vs. 10.5%; RR 6.37, 95% CI 1.03-39.36; p-value 0.04). All five patients who did not have CAN at the baseline developed this abnormality on repeat testing after one year. Conclusion The prevalence of CAN in patients with end-stage renal disease on maintenance hemodialysis was significantly higher. CAN was an independent predictor of all-cause and cardiovascular mortality, which highlights it as a risk stratification tool in patients with end-stage renal disease.

Low serum butyrylcholinesterase is independently related to low fetuin-A in patients on hemodialysis: a cross-sectional study

PURPOSE

Fetuin-A, which plays a protective role against the atherosclerosis and progression of vascular calcification, is decreased in patients on hemodialysis (HD). Fetuin-A and serum butyrylcholinesterase (BChE) levels decrease during malnutrition. We explored whether BChE was independently related to fetuin-A in patients on HD.

METHODS

Laboratory data including BChE and serum fetuin-A were acquired from 230 patients on HD between August 2017 and April 2018. Nutritional status was evaluated using the Geriatric Nutritional Risk Index (GNRI). Abdominal aortic calcification index (ACI) was measured using computed tomography. Patients were stratified into two groups: low fetuin-A (< lowest quartile) and non-low fetuin-A (≥ lowest quartile) groups. Patient background, medication, and laboratory data were compared. The receiver operating characteristic analysis was conducted to determine the optimal cutoff values of BChE and GNRI for lower fetuin-A level. Factors independently related with lower fetuin-A levels were determined using multivariate logistic regression analysis.

RESULTS

The lowest quartile value of fetuin-A and optimal cutoff values of BChE and GNRI were 0.213 g/L, 200 IU/L, and 92.6, respectively. The study included 57 and 173 patients in the low fetuin-A and non-low fetuin-A groups, respectively. Significant between-group differences were observed for age, C-reactive protein (CRP), history of cardiovascular disease, serum albumin, GNRI, and BChE. Multivariate analysis showed that BChE of < 200 IU/L [odds ratio (OR) 3.05], CRP (OR 2.49), and GNRI of < 92.6 (OR 2.34) were independent factors for lower fetuin-A level after adjusting for confounders.

CONCLUSIONS

BChE was a significant independent marker for fetuin-A levels in patients on HD, in addition to GNRI.

Lower Plasma Fetuin-A Levels Are Associated With a Higher Mortality Risk in Patients With Coronary Artery Disease

Objective—

The present study was designed to evaluate the association of circulating fetuin-A with cardiovascular disease (CVD) and all-cause mortality.

Approach and Results—

We measured plasma fetuin-A in 1620 patients using an enzyme-linked immunosorbent assay kit. The patients were members of the Guangdong coronary artery disease cohort and were recruited between October 2008 and December 2011. Cox regression models were used to estimate the association between plasma fetuin-A and the risk of mortality. A total of 206 deaths were recorded during a median follow-up of 5.9 years, 146 of whom died from CVD. The hazard ratios for the second and third tertiles of the fetuin-A levels (using the first tertile as a reference) were 0.65 (95% confidence interval, 0.44–0.96) and 0.51 (95% confidence interval, 0.33–0.78) for CVD mortality ( P =0.005) and 0.65 (95% confidence interval, 0.47–0.91) and 0.48 (95% confidence interval, 0.33–0.70) for all-cause mortality ( P <0.001), respectively.

Conclusions—

Lower plasma fetuin-A levels were associated with an increased risk of all-cause and CVD mortality in patients with coronary artery disease independently of traditional CVD risk factors.

Worsening calcification propensity precedes all-cause and cardiovascular mortality in haemodialyzed patients

A novel in-vitro test (T₅₀-test) assesses ex-vivo serum calcification propensity which predicts mortality in HD patients. The association of longitudinal changes of T₅₀ with all-cause and cardiovascular mortality has not been investigated. We assessed T₅₀ in paired sera collected at baseline and at 24 months in 188 prevalent European HD patients from the ISAR cohort, most of whom were Caucasians. Patients were followed for another 19 [interquartile range: 11–37] months. Serum T₅₀ exhibited a significant decline between baseline and 24 months (246 ± 64 to 190 ± 68 minutes; p < 0.001). With serum Δ-phosphate showing the strongest independent association with declining T₅₀ (r = −0.39; p < 0.001) in multivariable linear regression. The rate of decline of T₅₀ over 24 months was a significant predictor of all-cause (HR = 1.51 per 1SD decline, 95% CI: 1.04 to 2.2; p = 0.03) and cardiovascular mortality (HR = 2.15; 95% CI: 1.15 to 3.97; p = 0.02) in Kaplan Meier and multivariable Cox-regression analysis, while cross-sectional T₅₀ at inclusion and 24 months were not. Worsening serum calcification propensity was an independent predictor of mortality in this small cohort of prevalent HD patients. Prospective larger scaled studies are needed to assess the value of calcification propensity as a longitudinal parameter for risk stratification and monitoring of therapeutic interventions.

Serum osteoprotegerin in prevalent hemodialysis patients: associations with mortality, atherosclerosis and cardiac function

Background

To assess whether serum osteoprotegerin (OPG) and/or fetuin-A predict mortality and cardiovascular (CV) morbidity and mortality in hemodialysis patients.

Methods

Multicenter, observational, prospective study that included 220 hemodialysis patients followed up for up to 6 years. Serum OPG and fetuin-A levels were measured at baseline and their possible association with clinical characteristics, CV risk biomarkers, carotid ultrasonographic findings, as well as their association with overall and CV mortality and CV events were assessed.

Results

During a mean follow-up of 3.22 ± 1.91 years, there were 74 deaths (33.6%) and 86 new cardiovascular events. In the Kaplan-Meier survival analysis, the highest tertile of OPG levels was associated with higher overall mortality (p = 0.005), as well as a higher, although non-significant, incidence of CV events and CV mortality. In contrast, fetuin-A levels did not predict any of these events. OPG levels were directly associated with age, the Charlson comorbidity index (CCI), prevalent cardiovascular disease, carotid intima-media thickness, adiponectin, troponin-I and brain natriuretic peptide (BNP). OPG showed a negative correlation with left ventricular ejection fraction (LVEF) and phosphate levels. In the multivariate Cox proportional hazard analysis, all-cause mortality was associated with the highest tertile of OPG (HR:1.957, p = 0.018), age (HR:1.031, p = 0.036), smoking history (HR:2.122, p = 0.005), the CCI (HR:1.254, p = 0.004), troponin-I (HR:3.894, p = 0.042), IL-18 (HR:1.061, p < 0.001) and albumin levels (HR:0.886, p < 0.001). In the bootstrapping Cox regression analysis, the best cut-off value of OPG associated with mortality was 17.69 pmol/L (95%CI: 5.1–18.02).

Conclusions

OPG, but not fetuin-A levels, are independently associated with overall mortality, as well as clinical and subclinical atherosclerosis and cardiac function, in prevalent hemodialysis patients.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0701-8) contains supplementary material, which is available to authorized users.

Inflammation and premature aging in advanced chronic kidney disease

Systemic inflammation in end-stage renal disease is an established risk factor for mortality and a catalyst for other complications, which are related to a premature aging phenotype, including muscle wasting, vascular calcification, and other forms of premature vascular disease, depression, osteoporosis, and frailty. Uremic inflammation is also mechanistically related to mechanisms involved in the aging process, such as telomere shortening, mitochondrial dysfunction, and altered nutrient sensing, which can have a direct effect on cellular and tissue function. In addition to uremia-specific causes, such as abnormalities in the phosphate-Klotho axis, there are remarkable similarities between the pathophysiology of uremic inflammation and so-called "inflammaging" in the general population. Potentially relevant, but still somewhat unexplored in this respect, are abnormal or misplaced protein structures, as well as abnormalities in tissue homeostasis, which evoke danger signals through damage-associated molecular patterns, as well as the senescence-associated secretory phenotype. Systemic inflammation, in combination with the loss of kidney function, can impair the resilience of the body to external and internal stressors by reduced functional and structural tissue reserves, and by impairing normal organ crosstalk, thus providing an explanation for the greatly increased risk of homeostatic breakdown in this population. In this review, the relationship between uremic inflammation and a premature aging phenotype, as well as potential causes and consequences, are discussed.

Cardiac Autonomic Neuropathy Predicts All-Cause and Cardiovascular Mortality in Patients With End-Stage Renal Failure: A 5-Year Prospective Study

Introduction

Chronic renal disease is associated with increased cardiovascular (CV) mortality. Cardiac autonomic neuropathy (CAN) is predictive of mortality for diseases that affect the autonomic nervous system. We prospectively evaluated the prognostic value of indexes of left ventricular (LV) function and CAN in all-cause and CV mortality of patients with end-stage renal failure (ESRF).

Methods

A total of 133 patients with ESRF were recruited. LV function was evaluated by echocardiography, whereas cardiac autonomic function was assessed using the battery of the 4 standardized tests proposed by Ewing.

Results

A total of 123 of 133 (92.5%) patients completed the study and were followed for a mean of 4.9 ± 2.6 years. Mean LV ejection fraction (LVEF) was 50.9 ± 6.9%, whereas 70 (57.9%) patients had CAN. Sixty-nine all-cause and 36 CV deaths were recorded. The survival rates at 3, 5, and 7 years were 77.2%, 57.4%, and 33.7%, respectively. Multivariate analysis after adjustment for waist circumference, current smoking, history of diabetes, and coronary artery disease demonstrated that the only independent predictors of all-cause mortality during follow-up were age, serum triglycerides, LVEF, and presence of CAN. Competing risk regression analysis, after adjusting for waist circumference, coronary heart disease, serum glucose, and triglycerides, indicated that age and presence of CAN were independent risk factors for CV mortality.

Discussion

Age and presence of CAN are independent predictors of all-cause and CV mortality in patients with ESRF. The functionality of the cardiac autonomic nervous system activity can be used for the risk stratification in patients with ESRF.

Association of inflammatory cytokines with mortality in peritoneal dialysis patients

Aims: Previous study on association between pro-inflammatory cytokines and mortality in PD population is limited. We aimed to investigate here.

Methods: Total 50 patients who underwent incident PD were enrolled in this study. We measured the titers of pro-inflammatory cytokines Interleukin-18(IL-18), Interleukin-6 (IL-6), and Interleukin-1ß (IL-1ß). Study outcomes were all-cause mortality, cardiovascular-related mortality, and infection-caused mortality. Cox-regression model was used.

Results: In this 7 year prospective study, IL-18 ≥ 804.3pg/ml, IL-6 ≥ 3.92 pg/ml, IL-1ß ≥ 0.86pg/ml, age ≥ 50 years-old, and existence of diabetes could be used as individual significant predictors for mortality in PD patients. Higher titers of IL-6 were associated with lower averaging albumin levels within 1^st year of PD. Increasing numbers of these risk markers of mortality was associated with decreasing survival advantages (P = 0.001).

Conclusion: Age ≥ 50 years-old, diabetes, and inflammatory cytokines profiles at the start of PD therapy could predict for 7-year mortality in PD population.

Association of plasma fetuin-a levels with peripheral arterial disease and lower extremity arterial calcification in subjects with type 2 diabetes mellitus

AIMS

Fetuin-A is a hepatic glycoprotein that is involved in insulin resistance and atherosclerosis. Herein we examined the association of plasma fetuin-A levels with peripheral arterial disease (PAD) in patients with type 2 diabetes mellitus (T2DM).

MATERIAL AND METHODS

A total of 71 patients with T2DM and 57 non-diabetic individuals were recruited. Diagnosis of PAD was based on the absence of triphasic waveform at pedal arteries, while ankle-brachial index (ABI) was calculated. Radiographs of both feet and ankles were taken for the assessment of lower extremity arterial calcification (LEAC). Plasma fetuin-A levels were measured using ELISA.

RESULTS

Patients with T2DM had higher fetuin-A levels than non-diabetic participants. Participants with diabetes and PAD had lower fetuin-A levels than non-PAD diabetic patients. In subjects with T2DM fetuin-A levels were associated with ABI. Multivariate analysis demonstrated that in patients with T2DM the odds of PAD increased with long diabetes duration, smoking, presence of arterial hypertension and dyslipidemia, as well as with lower fetuin-A levels. A trend towards higher fetuin-A levels in subjects with less severe LEAC was found.

CONCLUSION

Plasma fetuin-A levels are lower in patients with T2DM and PAD and are associated with PAD, irrespective of traditional cardiovascular risk factors. Moreover, fetuin-A may be involved in arterial calcification.

FGF-23 and Osteoprotegerin but not Fetuin-A are associated with death and enhance risk prediction in non-dialysis chronic kidney disease stages 3-5

AIM

Numerous biomarkers have been shown to associate with clinical endpoints in chronic kidney disease (CKD). There is limited evidence whether biomarkers improve risk prediction in relation to clinical outcomes. Our study investigates whether a small suite of key chronic kidney disease-mineral and bone disorder biomarkers could be used to enhance risk assessment in CKD.

METHODS

Fetuin-A, fibroblast growth factor-23 and osteoprotegerin were measured on baseline plasma samples from 463 patients recruited to the Chronic Renal Insufficiency Standards Implementation Study. The biomarkers were analysed in relation to progression to end stage kidney disease, death and major cardiovascular events.

RESULTS

Over a median follow up of 46 months (interquartile range 21-69), fibroblast growth factor-23 was associated with risk for renal replacement therapy (hazard ratio (HR) 1.35, P = 0.05, 95% confidence interval (CI) 1.001-1.820), cardiovascular events (HR 1.74 P < 0.001, 95% CI 1.303-1.305) and death (HR 1.4 P = 0.005, 95% CI 1.109-1.767). Osteoprotegerin was associated with risk for death (HR 1.06, P = 0.03, 95% CI 1.006-1.117). There was no clear association between Fetuin-A and any of the clinical endpoints. The addition of biomarkers to risk models led to marginal improvement in model discrimination and reclassification.

CONCLUSION

Biomarkers are often associated with clinical endpoints, and we observed such associations in our study of patients with advanced CKD. However, the markers analysed in our study were of limited benefit in improving the prediction of these outcomes. Any extra information biomarkers may provide to improve risk prediction in clinical practice needs to be carefully balanced against the potential cost of these tools.

Emerging Human Fetuin A Assays for Biomedical Diagnostics

Human fetuin A (HFA) plays a prominent pathophysiological role in numerous diseases and pathophysiological conditions with considerable biomedical significance; one example is the formation of calciprotein particles in osteoporosis and impaired calcium metabolisms. With impressive advances in in vitro diagnostic assays during the last decade, ELISAs have become a workhorse in routine clinical diagnostics. Recent diagnostic formats involve high-sensitivity immunoassay procedures, surface plasmon resonance, rapid immunoassay chemistries, signal enhancement, and smartphone detection. The current trend is toward fully integrated lab-on-chip platforms with smartphone readouts, enabling health-care practitioners and even patients to monitor pathological changes in biomarker levels. This review provides a critical analysis of advances made in HFA assays along with the challenges and future prospects.

Urine and serum fetuin-A levels in patients with urolithiasis

Introduction:

Fetuin-A is a glycoprotein secreted by liver and has been shown to inhibit extraosseous mineralization. Urolithiasis may be a manifestation in the urinary tract due to fetuin deficiency in urine. The objective of this study was to compare the 24-h urine and serum fetuin-A levels of patients with and without urolithiasis.

Methods:

Serum and 24-h urine fetuin-A levels were measured in 41 patients with bilateral, multiple, or recurrent urinary tract calculi (Group A) and 41 matched controls with no calculi (Group B). Fetuin levels were measured by enzyme linked immunosorbent assay. Serum and urine fetuin-A levels in the two groups were compared.

Results:

The median (range) 24-h urine fetuin-A value in Group A was 11.9 (1.12–221) mg/day and in Group B was 37.7 (1.28–125) mg/day. This difference was statistically significant (Mann–Whitney test, P = 0.0169). The median (range) serum fetuin-A in Group A was 0.67 (0.05–2.68) g/L and in Group B was 0.99 (0.01–5.5) g/L. The difference between serum values in the two arms was not statistically significant (Mann–Whitney test, P = 0.1817). However, the serum creatinine-adjusted mean log serum fetuin and urine fetuin were significantly different in the two arms (P = 0.003). The mean ± standard deviation (range) serum creatinine in Group A was 0.98 ± 0.25 (0.56–1.58) mg% and in Group B was 0.83 ± 0.16 (0.58–1.18) mg% (two sample t-test, P = 0.0031).

Conclusions:

Patients with urolithiasis have lower urine fetuin-A and creatinine-adjusted serum fetuin-A levels.

Hyperphosphatemia. The hidden killer in chronic kidney disease

Hyperphosphatemia is a major cause of morbidity and mortality in patients with chronic kidney disease. The association between hyperphosphatemia and increased risk of death from cardiovascular disease/vascular calcification has been well established for a long time. This review explores the new aspects of pathogenesis of vascular calcification, as demonstrated by recent advances showing a recognized regulating role of phosphorus in vascular smooth muscle cell calcification. This novel mechanism may help in finding a new pharmacological therapy to reduce, or prevent blood vessel calcification. Furthermore, recent experimental and clinical studies involved in the treatment of hyperphosphatemia are reviewed in this article.

Calcium Phosphate Crystals from Uremic Serum Promote Osteogenic Differentiation in Human Aortic Smooth Muscle Cells

Recent study demonstrated that calcium phosphate (CaP) crystals isolated from high phosphate medium were a key contributor to arterial calcification. The present study further investigated the effects of CaP crystals induced by uremic serum on calcification of human aortic smooth muscle cells. This may provide a new insight for the development of uremic cardiovascular calcification. We tested the effects of uremic serum or normal serum on cell calcification. Calcification was visualized by staining and calcium deposition quantified. Expression of various bone-calcifying genes was detected by real-time PCR, and protein levels were quantified by western blotting or enzyme-linked immunosorbent assays. Pyrophosphate was used to investigate the effects of CaP crystals' inhibition. Finally, CaP crystals were separated from uremic serum to determine its specific pro-calcification effects. Uremic serum incubation resulted in progressively increased calcification staining and increased calcium deposition in HASMCs after 4, 8 and 12 days (P vs 0 day <0.001 for all). Compared to cells incubated in control serum, uremic serum significantly induced the mRNA expression of bone morphogenetic factor-2, osteopontin and RUNX2, and increased their protein levels as well (P < 0.05 for all). Inhibition of CaP crystals with pyrophosphate incubation prevented calcium deposition and bone-calcifying gene over-expression increased by uremic serum. CaP crystals, rather than the rest of uremic serum, were responsible for these effects. Uremic serum accelerates arterial calcification by mediating osteogenic differentiation. This effect might be mainly attributed to the CaP crystal content.

Reappraisal of effects of serum chemerin and adiponectin levels and nutritional status on cardiovascular outcomes in prevalent hemodialysis patients

Although chemerin, an adipokine, increases the cardiovascular (CV) risk in obese people, it is associated with a survival advantage in incident hemodialysis (HD) patients. We explored the potential effects of chemerin on CV outcomes in prevalent HD patients. This prospective study included 343 prevalent HD patients. The composite outcome was the occurrence of CV events and death during follow-up. We used multivariate Cox regression analysis to test the predictive power of different chemerin and adiponectin levels and geriatric nutritional risk index (GNRI) for the outcomes. HD patients with higher chemerin levels (≥211.4 ng/mL) had a lower risk of CV events (adjusted hazard ratio [HR], 0.64; 95% confidence interval [CI], 0.41-0.98) and composite CV outcome (adjusted HR, 0.67; 95% CI, 0.45-0.99) than those with lower chemerin levels (<211.4 ng/mL). When evaluating CV outcomes, we identified an interaction between chemerin levels and GNRI, but not between chemerin and adiponectin levels. The findings remained robust in the sensitivity analysis. Thus, in prevalent HD patients with negligible residual renal function, higher chemerin levels predict more favourable CV outcomes.

Serum Fetuin A Levels: Are They a Reliable Marker for Hepatic Steatosis and Regional Adiposity in Renal Transplant Recipients?

BACKGROUND

Fetuin A is a protein expressed in the liver and it is an important inhibitor of ectopic calcification. High levels of fetuin A correlate with insulin resistance, hepatic steatosis, and regional adiposity in the general population. The association between hepatic steatosis and fetuin A level in renal transplant recipients (RTRs) remains unclear.

AIM

The aim of this study was to explore the relationships between fetuin A, hepatic steatosis, and regional adiposity in RTRs.

METHODS

Data from 44 patients with normal renal functions were included, all subjected to history taking for clinical data, assessment of central obesity and regional adiposity, assessment of hepatic steatosis using abdominal ultrasound (US), and measurements of serum fetuin A concentration using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Our study included 20 females (45.4%) and 24 males (54.6%) with mean age of 41.26 ± 11.2 years. Twenty-four subjects had hepatic steatosis. Fetuin A level in RTRs with hepatic steatosis with a mean of 1642.92 ± 358.91 is significantly higher (P < .001) than those without hepatic steatosis with a mean of 711.74 ± 57.85. Serum fetuin A level was positively correlated with regional adiposity (P = .021) and hepatic steatosis grade (P = .017). Fetuin A level increased with increased duration after renal transplantation (P < .001). The best cutoff value for detecting entrance into phase 3 or 4 steatosis is fetuin of 1862 with sensitivity of 88.9% and specificity of 87.7%.

CONCLUSIONS

Fetuin A is positively correlated with hepatic steatosis and regional adiposity in RTRs. Fetuin increases with increased duration after renal transplantation. Accordingly it may be used as a marker for hepatic steatosis and regional adiposity in these patients.

Relationship between Fetuin A, Vascular Calcification and Fracture Risk in Dialysis Patients

Background

Fractures are a common morbidity that lead to worse outcomes in dialysis patients. Fetuin A inhibits vascular calcification (VC), potentially promotes bone mineralization and its level positively correlates with bone mineral density in the general population. On the other hand, the presence of VC is associated with low bone volume in dialysis patients. Whether the fetuin A level and VC can predict the occurrence of fractures in dialysis patients remains unknown.

Methods

We performed this prospective, observational cohort study including 685 dialysis patients (629 hemodialysis and 56 peritoneal dialysis) from a single center in Taiwan for a median follow-up period of 3.4 years. The baseline fetuin A level and status of presence of aortic arch calcification (VC) and incidence of major fractures (hip, pelvis, humerus, proximal forearm, lower leg or vertebrae) were assessed using adjusted Cox proportional hazards models, recursive partitioning analysis and competing risk models.

Results

Overall, 177 of the patients had major fractures. The incidence rate of major fractures was 3.29 per 100 person-years. In adjusted analyses, the patients with higher baseline fetuin A levels had a lower incidence of fractures (adjusted hazard ratio (HR), 0.3; 95% CI, 0.18‒0.5, fetuin A tertile 3 vs. tertile 1 and HR, 0.52; 95% CI, 0.34‒0.78, tertile 2 vs. tertile 1). The presence of aortic arch calcification (VC) independently predicted the occurrence of fractures (adjusted HR, 1.95; 95% CI, 1.34‒2.84) as well. When accounting for death as an event in competing risk models, the patients with higher baseline fetuin A levels remained to have a lower incidence of fractures (SHR, 0.31; 95% CI, 0.17‒0.56, fetuin A tertile 3 vs. tertile 1 and 0.51; 95% CI, 0.32‒0.81, tertile 2 vs. tertile 1).

Interpretations

Lower baseline fetuin A levels and the presence of VC were independently linked to higher risk of incident fractures in prevalent dialysis patients.

Parathyroidectomy Improves Restless Leg Syndrome in Patients on Hemodialysis

Background

Restless leg syndrome (RLS) is a sleep disorder with high prevalence among patients on hemodialysis. It has been postulated that high phosphate and high parathyroid hormone may be implicated in its pathogenesis. Standard international criteria and face-to-face interview are not always applied.

Methods

this was an interventional prospective study in which 19 patients (6 men, aged 48±11 years) with severe hyperparathyroidism were evaluated. RLS diagnosis and rating scale were accessed based on the International RLS Study Group pre- and post-parathyroidectomy. Patients also underwent standard polysomnography.

Results

At baseline, RLS was present in 10 patients (52.6%), and pain was the most reported symptom associated with the diagnosis. Patients with RLS had higher serum phosphate (p = 0.008) that remained independently associated with RLS in a logistic regression model, adjusted for hemoglobin, age and gender (HR = 7.28;CI = 1.14–46.3, p = 0.035). After parathyroidectomy, there was a reduction of serum parathyroid hormone, phosphate, calcium and alkaline phosphatase, and an increase of 25(OH)-vitamin D, and Fetuin-A. Parathyroidectomy alleviated RLS (from 52% to 21%; p = 0.04), which was accompanied by a decrease in severity scale, in association with relief of pain and pruritus. Polysomnography in these patients showed an improvement of sleep parameters as measured by sleep efficiency, sleep latency and percentage of REM sleep.

Conclusion

RLS is associated with high levels of phosphate in patients with severe secondary hyperparathyroidism on hemodialysis. Pain is most reported complain in these patients. Parathyroidectomy provided an opportunity to relief RLS. Whether the reduction of serum phosphorus or parathyroid hormone contributed to this improvement merits further investigation.

Markers of increased atherosclerotic risk in patients with chronic kidney disease: a preliminary study

BACKGROUND

The prevalence of chronic kidney disease is rising continuously. Cardiovascular disease is among leading causes of death and premature mortality of patients with chronic kidney disease. Even the earliest stages of chronic kidney disease are associated with higher risk of subsequent coronary heart disease. The aim of this study was to determine markers of increased risk of atherosclerosis in CKD.

METHODS

The study group consisted of a total of 80 patients (20 patients with stage I/II CKD, 20 with stage III CKD, 20 stage IV CKD and 20 stage V/dialysis) and 24 healthy volunteers. Levels of proteins (osteoprotegerin, osteopontin, osteocalcin, matrix γ-carboxyglutamic acid protein, fetuin A, MMP-2, MMP-9, TIMP-1, TIMP-2) and biochemical parameters were measured to analyse their influence on atherosclerosis risk in CKD patients. Cardiac echocardiography was performed to assess structural integrity and function, presence of left ventricular hypertrophy and systolic and diastolic function dysfunction.

RESULTS

This study shows that the prevalence of ventricular hypertrophy (95.3 %) and diastolic dysfunction (93.2 %) in CKD patients is high. Also E/E' ratio was significantly higher (13.6 ± 4.4, p = 0.001), tricuspid insufficiency (27.3 in CKD I/II vs. 71.4 in CKD V, p = 0.016), contractile dysfunction (33.3 in CKD I/II vs. 78.9 in CKD V, p = 0.040), mitral valve calcification (0 in CKD I/II vs. 28.6 in CKD V, p = 0.044) and aortic valve calcification (0 in CKD I/II vs. 61.9 in CKD V, p = 0.0008) were significantly more frequent in patients with CKD stage V/dialysis than in other groups. Only MMP-2, MMP-2/TIMP-2 ratio and TIMP-1 differed significantly between groups.

CONCLUSIONS

This study shows high prevalence of ventricular hypertrophy and diastolic dysfunction in CKD patients. Contractile dysfunction, mitral and aortic valve calcification in HD patients were significantly more frequent than in patients with other CKD stages. Significantly increased levels of MMP-2, MMP-2/TIMP-2 ratio and lower TIMP-1 suggests that these factors may be involved in the pathogenesis of atherosclerosis in CKD patients.

Fetuin-A and vascular calcification in Indian end-stage renal disease population

Fetuin-A levels, its correlation with vascular calcification and other biochemical markers of chronic kidney disease-mineral and bone disorder (CKD-MBD) has not been studied in Indian end-stage renal disease population. Forty patients on dialysis for more than 3 months were studied. Biochemical parameters of CKD-MBD, highly sensitive-C reactive protein (hs-CRP), lipid profile and fetuin-A levels were estimated. Multi-slice computed tomography (MSCT) at the level of L1-L4 was done, and calcification score calculated using AJ 130 smart score. Levels of fetuin-A were correlated with calcification score and biochemical markers of CKD-MBD. Mean fetuin-A levels were 0.33 ± 0.098 g/l. Positive correlation of abdominal aortic calcification scores was found with age (P < 0.01) and duration of dialysis (P = 0.018). No correlation was detected between MSCT score, calcium phosphate product, intact parathyroid hormone, vitamin D, triglycerides and fetuin-A, and there was no correlation between fetuin-A levels, age, dialysis duration and calcium phosphate product but a significant correlations with vitamin D3 (P = 0.034), serum albumin (P = 0.002) was detected. Inverse correlation with hs-CRP was obtained. Patients with ischemic heart disease had numerically lower levels of fetuin-A (P = 0.427) and numerically higher MSCT score (P = 0.135). Patients with low hs-CRP (<10) had numerically higher fetuin-A levels (P = 0.090) and significantly low MSCT scores (P = 0.020). Calcium deposition seen on MSCT increases with age and duration of dialysis but is not related to fetuin-A levels. Inconclusive relationship exists with other parameters of CKD-MBD. Large controlled studies are needed to establish the role of fetuin-A in vascular calcification in Indian population.

Association between serum fetuin-A level and erectile function

Recent studies have shown that ED is an early symptom of atherosclerosis. Fetuin-A, a glycoprotein secreted by the liver, kidneys and choroid plexus, has been linked to systemic fibrosis and calcification in human and rat studies. Deficiency of this compound may play a role in atherosclerosis and cardiovascular disease progression. The aim of the study was to examine whether serum fetuin-A level is related to erectile function or severity of ED. Sixty ED patients without cardiovascular disease were assigned to one of the three groups (mild, moderate or severe ED) depending on ED severity. Twenty healthy volunteers were included as the control group. The International Index of Erectile Function-5 questionnaire was used to measure erection quality in all four groups. Mean age, body mass index, total testosterone, low- and high-density lipoprotein cholesterol, and triglyceride levels did not significantly differ between the three erectile dysfunction and control groups (P > 0.05). The group with severe ED had a significantly lower mean fetuin-A level than the mild ED and control groups. For both mild and moderate ED groups, the mean serum fetuin-A level was significantly lower in comparison with the control group (P < 0.001). Serum fetuin-A level may be used as a supplemental biochemical parameter in preliminary evaluation of ED.

Use of sevelamer in chronic kidney disease: beyond phosphorus control

Sevelamer is a non-calcium phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis for hyperphosphataemia control. Several experimental, observational studies and clinical trials have shown that sevelamer has pleiotropic effects, beyond hyperphosphataemia control, including actions on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and the reduction of several uremic toxins. This is the biological basis for its global effect on cardiovascular morbidity and mortality in patients with chronic kidney disease. This review focuses on these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than ten years of clinical expertise.

Matrix γ-carboxyglutamate protein and Fetuin-A, in wet type age-related macular degeneration

AIM

To evaluate the high sensitivity C-reactive protein (hsCRP), Fetuin-A and matrix γ-carboxyglutamate protein (MGP) as the main factors for vascular calcification and inflammation in serum of patients with advanced age-related macular degeneration (ARMD) in comparison to healthy controls.

METHODS

The subjects were 40 patients with choroidal neovascularization (CNV) having a mean age of 70.9±9.1y and a matched group of 49 apparently healthy control subjects. The ARMD was diagnosed using a slit-lamp with superfield lens, fundus photography and fluorescein angiography. Measurement of hsCRP was done by nephelometry method. Levels of Fetuin-A and MGP were measured by enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

hsCRP [0.45(0.07-2.63) mg/L vs 0.25(0.03-1.2) mg/L, P=0.02)] and Fetuin-A levels (50.27±5.04 vs 44.99±10.28 ng/mL, P=0.009) were higher in the patients than in the control groups. We could not find significant difference in MGP level between two groups (P=0.08). There was not a significant correlation between MGP with Fetuin-A and hsCRP among the patients (P=0.7, P=0.9 respectively). A significant negative correlation of hsCRP with Fetuin-A was observed in both case and control groups (P=0.004, r=-0.33 and P=0.001, r=-0.54, respectively).

CONCLUSION

Although our study shows that serum hsCRP and Fetuin-A is increased in CNV patients as well as negatively correlated with both study groups, their direct role on pathogenesis of ARMD required future studies.

Indoxyl sulfate suppresses hepatic fetuin-A expression via the aryl hydrocarbon receptor in HepG2 cells

BACKGROUND

Fetuin-A is a liver-derived circulating protein that has potent calcification-inhibitory activity. Uraemic patients exhibit decreased serum fetuin-A levels, increased vascular calcification and elevated cardiovascular mortality. Because the mechanisms for fetuin-A deficiency are unknown, we hypothesized that some uraemic toxins suppressed hepatic fetuin-A production, which resulted in accelerated vascular calcification and poor outcome. Among these potential candidates, indoxyl sulfate (IS) has highly toxic properties.

METHODS

We examined the direct effects of IS on hepatic fetuin-A expression using the human hepatoma HepG2 cell line.

RESULTS

IS, but not p-cresyl sulfate, suppressed the mRNA and protein expression of fetuin-A in a dose- and time-dependent manner. As reported previously, IS stimulated p38 MAPK phosphorylation and reactive oxygen species (ROS) production, although the knockdown of p38 and inhibition of ROS generation had no effect on IS-induced fetuin-A suppression. Then, because IS is a potent endogenous ligand of the aryl hydrocarbon receptor (AhR), we assessed whether IS suppresses fetuin-A production via AhR. The knockdown of AhR prevented IS-induced fetuin-A suppression. However, some attention should be paid to no effect of IS on fetuin-A expression in mouse and human primary cultured hepatocytes.

CONCLUSIONS

These findings suggest that IS could suppress hepatic fetuin-A expression by activating AhR, suggesting a relationship between uraemia and fetuin-A deficiency.

The role of fetuin-A in mineral trafficking and deposition

Calcium and phosphate are the principle ions involved in the deposition of mineral in the human body. Inhibitors of mineralisation are essential for the prevention of ectopic mineral precipitation and deposition. In the past decade, through in vitro, in vivo and clinical observation studies, we have come to appreciate the importance of fetuin-A (Fet-A), a circulating glycoprotein, in preventing ectopic calcium phosphate mineralisation. Moreover, the detection of Fet-A-containing mineral complex, termed calciprotein particles (CPPs), has provided new ways to assess an individual's calcific risk. The pathophysiological significance of CPPs in disease states is yet to be defined, but it provides an exciting avenue to further our understanding of the development of ectopic mineralisation.