Multi-Parametric Evaluation of Chronic Kidney Disease by MRI: A Preliminary Cross-Sectional Study

Background

The current clinical classification of chronic kidney disease (CKD) is not perfect and may be overestimating both the prevalence and the risk for progressive disease. Novel markers are being sought to identify those at risk of progression. This preliminary study evaluates the feasibility of magnetic resonance imaging based markers to identify early changes in CKD.

Methods

Fifty-nine subjects (22 healthy, 7 anemics with no renal disease, 30 subjects with CKD) participated. Data using 3D volume imaging, blood oxygenation level dependent (BOLD) and Diffusion MRI was acquired. BOLD MRI acquisition was repeated after 20 mg of iv furosemide.

Results

Compared to healthy subjects, those with CKD have lower renal parenchymal volumes (329.6±66.4 vs. 257.1±87.0 ml, p<0.005), higher cortical R2* values (19.7±3.2 vs. 23.2±6.3 s⁻¹, p = 0.013) (suggesting higher levels of hypoxia) and lower response to furosemide on medullary R2* (6.9±3.3 vs. 3.1±7.5 s⁻¹, p = 0.02). All three parameters showed significant correlation with estimated glomerular filtration rate (eGFR). When the groups were matched for age and sex, cortical R2* and kidney volume still showed significant differences between CKD and healthy controls. The most interesting observation is that a small number of subjects (8 of 29) contributed to the increase in mean value observed in CKD. The difference in cortical R2* between these subjects compared to the rest were highly significant and had a large effect size (Cohen’s d = 3.5). While highly suggestive, future studies may be necessary to verify if such higher levels of hypoxia are indicative of progressive disease. Diffusion MRI showed no differences between CKD and healthy controls.

Conclusions

These data demonstrate that BOLD MRI can be used to identify enhanced hypoxia associated with CKD and the preliminary observations are consistent with the chronic hypoxia model for disease progression in CKD. Longitudinal studies are warranted to further verify these findings and assess their predictive value.     

Diagnostic Value of Urinary Kidney Injury Molecule 1 for Acute Kidney Injury: A Meta-Analysis

Background

Urinary Kidney Injury Molecule 1 (KIM-1) is a proximal tubular injury biomarker for early detection of acute kidney injury (AKI), with variable performance characteristics depending on clinical and population settings.

Methods

Meta-analysis was performed to assess the diagnostic value of urinary KIM-1 in AKI. Relevant studies were searched from MEDLINE, EMBASE, Pubmed, Elsevier Science Direct, Scopus, Web of Science, Google Scholar and Cochrane Library. Meta-analysis methods were used to pool sensitivity and specificity and to construct summary receiver operating characteristic (SROC) curves.

Results

A total of 2979 patients from 11 eligible studies were enrolled in the analysis. Five prospective cohorts, two cross-sectional and four case-control studies were identified for meta-analysis. The estimated sensitivity of urinary KIM-1 for the diagnosis of AKI was 74.0% (95% CI, 61.0%–84.0%), and specificity was 86.0% (95% CI, 74.0%–93.0%). The SROC analysis showed an area under the curve of 0.86(0.83–0.89). Subgroup analysis suggested that population settings and detection time were the key factors affecting the efficiency of KIM-1 for AKI diagnosis.

Limitation

Various population settings, different definition of AKI and Serum creatinine level used as the standard might have influence on AKI diagnosis. The relatively small number of studies and heterogeneity between them also affected the evaluation.

Conclusion

Urinary KIM-1 may be a promising biomarker for early detection of AKI with considerable predictive value, especially for cardiac surgery patients, and its potential value needs to be validated in large studies and across a broader scope of clinical settings.     

The Association of Pioglitazone and Urinary Tract Disease in Type 2 Diabetic Taiwanese: Bladder Cancer and Chronic Kidney Disease

Objective

Although studies have shown an association between pioglitazone and bladder cancer, the associated factors have not been identified. The aim of this study was to investigate the factors that may link pioglitazone to bladder cancer.

Materials and Methods

In total, 34,970 study subjects were identified from the National Health Insurance Research Database in 2003 with follow-up from 2005 to 2009. The demographic characteristics of patients who had used and had never used pioglitazone, including age, sex, diabetes duration, urinary tract disease, nephropathy, bladder cancer, and cumulative dose and duration of pioglitazone therapy, were analyzed using the χ2 test. Cox proportional hazard regression models were used to determine the independent effects of pioglitazone on bladder cancer and newly developed chronic kidney disease.

Results

Among 3,497 ever users and 31,473 never users of pioglitazone, the respective incident cases of bladder cancer were 12 (0.4%) and 72 (0.2%), and for newly developed chronic kidney disease 245 (8.1%) and 663 (2.3%), respectively. Ever use of pioglitazone [1.59(1.32–1.91)], cumulative dose of pioglitazone <10,500 mg [1.69 (1.37–2.01)] and >10,500 mg [1.34 (1.04–1.73)], and duration of therapy <12 months [1.68 (1.36–2.08)] and >12 months [1.39 (1.09–1.76)] were associated with the development of chronic kidney disease.

Conclusions

There was no association of pioglitazone use with bladder cancer development, however, there was an association with an increased risk of newly developed chronic kidney disease.     

Decrease in Urinary Creatinine Excretion in Early Stage Chronic Kidney Disease

Background

Little is known about muscle mass loss in early stage chronic kidney disease (CKD). We used 24-hour urinary creatinine excretion rate to assess determinants of muscle mass and its evolution with kidney function decline. We also described the range of urinary creatinine concentration in this population.

Methods

We included 1072 men and 537 women with non-dialysis CKD stages 1 to 5, all of them with repeated measurements of glomerular filtration rate (mGFR) by ⁵¹Cr-EDTA renal clearance and several nutritional markers. In those with stage 1 to 4 at baseline, we used a mixed model to study factors associated with urinary creatinine excretion rate and its change over time.

Results

Baseline mean urinary creatinine excretion decreased from 15.3±3.1 to 12.1±3.3 mmol/24 h (0.20±0.03 to 0.15±0.04 mmol/kg/24 h) in men, with mGFR falling from ≥60 to <15 mL/min/1.73 m², and from 9.6±1.9 to 7.6±2.5 (0.16±0.03 to 0.12±0.03) in women. In addition to mGFR, an older age, diabetes, and lower levels of body mass index, proteinuria, and protein intake assessed by urinary urea were associated with lower mean urinary creatinine excretion at baseline. Mean annual decline in mGFR was 1.53±0.12 mL/min/1.73 m² per year and that of urinary creatinine excretion rate, 0.28±0.02 mmol/24 h per year. Patients with fast annual decline in mGFR of 5 mL/min/1.73 m² had a decrease in urinary creatinine excretion more than twice as big as in those with stable mGFR, independent of changes in urinary urea as well as of other determinants of low muscle mass.

Conclusions

Decrease in 24-hour urinary creatinine excretion rate may appear early in CKD patients, and is greater the more mGFR declines independent of lowering protein intake assessed by 24-hour urinary urea. Normalizing urine analytes for creatininuria may overestimate their concentration in patients with reduced kidney function and low muscle mass.     

The RenTg Mice: A Powerful Tool to Study Renin-Dependent Chronic Kidney Disease

Background

Several studies have shown that activation of the renin-angiotensin system may lead to hypertension, a major risk factor for the development of chronic kidney disease (CKD). The existing hypertension-induced CDK mouse models are quite fast and consequently away from the human pathology. Thus, there is an urgent need for a mouse model that can be used to delineate the pathogenic process leading to progressive renal disease. The objective of this study was dual: to investigate whether mice overexpressing renin could mimic the kinetics and the physiopathological characteristics of hypertension-induced renal disease and to identify cellular and/or molecular events characterizing the different steps of the progression of CKD.

Methodology/Principal Findings

We used a novel transgenic strain, the RenTg mice harboring a genetically clamped renin transgene. At 3 months, heterozygous mice are hypertensive and slightly albuminuric. The expression of adhesion markers such as vascular cell adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 are increased in the renal vasculature indicating initiation of endothelial dysfunction. At 5 months, perivascular and periglomerular infiltrations of macrophages are observed. These early renal vascular events are followed at 8 months by leukocyte invasion, decreased expression of nephrin, increased expression of KIM-1, a typical protein of tubular cell stress, and of several pro-fibrotic agents of the TGFβ family. At 12 months, mice display characteristic structural alterations of hypertensive renal disease such as glomerular ischemia, glomerulo- and nephroangio-sclerosis, mesangial expansion and tubular dilation.

Conclusions/Significance

The RenTg strain develops CKD progressively. In this model, endothelial dysfunction is an early event preceding the structural and fibrotic alterations which ultimately lead to the development of CKD. This model can provide new insights into the mechanisms of chronic renal failure and help to identify new targets for arresting and/or reversing the development of the disease.     

成人型多囊肾病的遗传研究

３＇ＨＶＲ是成人型多囊肾病基因诊断中最常用的探针。我们分析了５１个无亲缘关系健康学生和３个成人多囊肾病家系的３＇ＨＶＲ－ＰｖｕＩＩ ＲＦＬＰ,所得多态信息用计算机软件ＬＩＮＫ－ＡＧＥ和ＨＯＭＯＧ进行连锁分析和同质性检验,其中１个家系致病基因位点与３＇ＨＶＲ不连锁,因而判定为ｎｏｎ ＰＫＤ１。剩下的两个家系中１个有明显的重组,但还不能判定为ｎｏｎ ＰＫＤ１,另１个与３＇ＨＶＲ连锁,属于ＰＫＤ１。成人     

The Prevalence of Chronic Kidney Disease in a Primary Care Setting: A Swiss Cross-Sectional Study

Chronic kidney disease (CKD) often remains clinically silent and therefore undiagnosed until a progressed stage is reached. Our aim was to estimate the prevalence of CKD in a primary care setting in Switzerland. A multicenter, cross-sectional study with randomly selected general practitioners was performed. Adults visiting their general physician’s cabinet during defined periods were asked to participate. Baseline information was reported on a questionnaire, urine and blood samples were analyzed in a central laboratory. Renal status was assessed using the Kidney Disease: Improving Global Outcomes (KDIGO) classification. Extrapolation of results to national level was adjusted for age and gender. One thousand individuals (57% females) with a mean age of 57±17 years were included. Overall, 41% of the patients had normal estimated glomerular filtration rate (eGFR) and albumin creatinine ratio (ACR), whereas 36% of the subjects had slightly reduced excretory renal function with physiological albuminuria based on normal ACR. Almost one fourth of the subjects (23%) had either a substantially reduced eGFR or high levels of ACR. About 10% of the patients had a substantially reduced eGFR of <60 ml/min/1.73 m², and 17% showed relevant proteinuria (ACR >30 mg/g creatinine). Extrapolation to national level suggests that about 18% of primary care patients may suffer from CKD. CKD prevalence in a primary care population is therefore high, and preventive interventions may be advisable, in particular as CKD prevalence is likely to rise over the next decades.     

A New Protein Superfamily: TPPP-Like Proteins

The introduction of the term ‘Tubulin Polymerization Promoting Protein (TPPP)-like proteins’ is suggested. They constitute a eukaryotic protein superfamily, characterized by the presence of the p25alpha domain (Pfam05517, IPR008907), and named after the first identified member, TPPP/p25, exhibiting microtubule stabilizing function. TPPP-like proteins can be grouped on the basis of two characteristics: the length of their p25alpha domain, which can be long, short, truncated or partial, and the presence or absence of additional domain(s). TPPPs, in the strict sense, contain no other domains but one long or short p25alpha one (long- and short-type TPPPs, respectively). Proteins possessing truncated p25alpha domain are first described in this paper. They evolved from the long-type TPPPs and can be considered as arthropod-specific paralogs of long-type TPPPs. Phylogenetic analysis shows that the two groups (long-type and truncated TPPPs) split in the common ancestor of arthropods. Incomplete p25alpha domains can be found in multidomain TPPP-like proteins as well. The various subfamilies occur with a characteristic phyletic distribution: e. g., animal genomes/proteomes contain almost without exception long-type TPPPs; the multidomain apicortins occur almost exclusively in apicomplexan parasites. There are no data about the physiological function of these proteins except two human long-type TPPP paralogs which are involved in developmental processes of the brain and the musculoskeletal system, respectively. I predict that the superfamily members containing long or partial p25alpha domain are often intrinsically disordered proteins, while those with short or truncated domain(s) are structurally ordered. Interestingly, members of this superfamily connected or maybe connected to diseases are intrinsically disordered proteins.     

Recognition of Higher Order Patterns in Proteins: Immunologic Kernels

By applying analysis of the principal components of amino acid physical properties we predicted cathepsin cleavage sites, MHC binding affinity, and probability of B-cell epitope binding of peptides in tetanus toxin and in ten diverse additional proteins. Cross-correlation of these metrics, for peptides of all possible amino acid index positions, each evaluated in the context of a ±25 amino acid flanking region, indicated that there is a strongly repetitive pattern of short peptides of approximately thirty amino acids each bounded by cathepsin cleavage sites and each comprising B-cell linear epitopes, MHC–I and MHC-II binding peptides. Such “immunologic kernel” peptides comprise all signals necessary for adaptive immunologic cognition, response and recall. The patterns described indicate a higher order spatial integration that forms a symbolic logic coordinating the adaptive immune system.     

Naturally Occurring Human Urinary Peptides for Use in Diagnosis of Chronic Kidney Disease

Because of its availability, ease of collection, and correlation with physiology and pathology, urine is an attractive source for clinical proteomics/peptidomics. However, the lack of comparable data sets from large cohorts has greatly hindered the development of clinical proteomics. Here, we report the establishment of a reproducible, high resolution method for peptidome analysis of naturally occurring human urinary peptides and proteins, ranging from 800 to 17,000 Da, using samples from 3,600 individuals analyzed by capillary electrophoresis coupled to MS. All processed data were deposited in an Structured Query Language (SQL) database. This database currently contains 5,010 relevant unique urinary peptides that serve as a pool of potential classifiers for diagnosis and monitoring of various diseases. As an example, by using this source of information, we were able to define urinary peptide biomarkers for chronic kidney diseases, allowing diagnosis of these diseases with high accuracy. Application of the chronic kidney disease-specific biomarker set to an independent test cohort in the subsequent replication phase resulted in 85.5% sensitivity and 100% specificity. These results indicate the potential usefulness of capillary electrophoresis coupled to MS for clinical applications in the analysis of naturally occurring urinary peptides.Chronic kidney disease (CKD)1 is often characterized by a slow, progressive loss of renal function with a loss of glomerular filtration over a period of months or years that may eventually lead to end stage renal disease (ESRD). Patients with ESRD require renal replacement therapy (dialysis or kidney transplantation). The most common causes of CKD in North America, Europe, and Japan are diabetic nephropathy, hypertension, and glomerulonephritis (1). Together, these diseases account for ∼75% of all adult cases of ESRD. Historically, kidney diseases were classified according to the anatomical compartment of the kidney that is involved. On this basis, vascular diseases include large and small vessel diseases, such as hypertensive nephropathy and vasculitis. Glomerular diseases comprise a diverse group of histologically defined primary glomerulopathies (e.g. focal segmental glomerulosclerosis (FSGS), membranous glomerulonephritis (MGN), minimal change disease (MCD), and IgA nephropathy (IgAN)) and secondary glomerulopathies due to diabetes mellitus (diabetic nephropathy), systemic autoimmune disorders (e.g. lupus erythematosus and hemolytic-uremic syndrome), or chronic viral infection (e.g. hepatitis and HIV). Tubular diseases are characterized by low molecular weight proteinuria and multiple transport defects (e.g. DeToni-Debré-Fanconi syndrome).In clinical practice, renal damage is generally detected by proteinuria/albuminuria on urinalysis or quantitative measurement, changes in serum creatinine concentration for estimation of glomerular filtration rate, or both. However, these methods have major limitations as they are nonspecific and frequently are also late manifestations of renal damage. Therefore, we have sought to define alternative biomarkers for renal damage that may enable earlier and more accurate disease assessment.Analysis of urine plays a central role in clinical diagnostics as it can be collected non-invasively. Urine as a body fluid for clinical analysis is relatively stable, probably due to the fact that it is “stored” for hours in the bladder; hence, proteolytic degradation by endogenous proteases may be essentially complete by the time of voiding (2). This is in sharp contrast to blood for which the activation of proteases and, consequently, generation of an array of proteolytic breakdown products are inevitably associated with its collection (3). The human urinary peptidome has been extensively investigated to gain insight about disease processes affecting the kidney and the urogenital tract (4–6). Urinary proteins and peptides originate not only from glomerular filtration but also from tubular secretion, epithelial cells shed from the kidney and urinary tract, secreted exosomes, and seminal secretions (7–9). Urine is a rich source of biomarkers for a wide range of diseases due to specific changes in its proteome (10–13). To test the feasibility of urinary proteomics as a non-invasive diagnostic tool, large scale studies are needed to analyze urine samples with reliable and quantitative experimental procedures. Various techniques have been applied to this effort, including two-dimensional electrophoresis combined with mass spectrometry (MS) and/or immunochemical identification of proteins (14–16), liquid chromatography coupled to mass spectrometry (LC-MS) (17, 18), and surface-enhanced laser desorption/ionization mass spectrometry (SELDI-MS) (19).Because of mostly technical challenges, studies relying on proteomics experimental procedures are often restricted to the comparison of two groups of subjects (i.e. healthy controls versus patients with a well defined disease entity) with only a few individuals in each group. The lack of comparability severely limits the suitability of such data for a meta-analysis approach to define broadly applicable biomarkers. Consequently, findings from several studies cannot be used to explore the human urinary proteome/peptidome in its entirety. In addition, the health state of patients with kidney disease is often too heterogeneous to be reliably classified by biomarkers identified by such a strictly single disease-oriented approach. Diagnosis of individuals with different stages or types of kidney disease (disease controls) is conceivable by multiplex screening of proteomics data. Realization of such an approach critically depends on the use of a measurement platform allowing analysis of proteomic profiles within a reasonably short time and with high resolution and on the generation of a reference database for the human urinary proteome/peptidome.Capillary electrophoresis coupled to mass spectrometry (CE-MS) enables reproducible and robust high resolution analysis of several thousand low molecular weight urinary proteins/peptides in less than an hour (5). In comparison with other proteomics methods, CE-MS offers several advantages. (i) It provides fast separation with high resolution. (ii) It is robust: capillaries are inexpensive and can be reconditioned efficiently using NaOH. (iii) It is compatible with most volatile buffers and analytes generally required for ESI. (iv) It provides a stable constant flow, avoiding the necessity of buffer gradients (for more details, see recent reviews (3, 5, 20)).This approach has recently been used to analyze urine samples from healthy individuals and patients with various chronic kidney diseases in several independent masked studies (21–27), including IgAN (28), diabetic nephropathy (29), and ANCA-associated vasculitis (30). The high number of data sets analyzed under identical conditions using the same technological platform allows comprehensive characterization of the low molecular weight proteome (peptidome) that can then become a primary source of information for the diagnosis, classification, and monitoring of a wide range of diseases. Here, we report the analysis of the human urinary peptidome by CE-MS and the identification of peptide urinary biomarkers for the detection of pathological changes in the kidney during the development of many forms of CKD. Furthermore, we have replicated these findings in an independent cohort.     

Benign and Malignant Breast Disease in South Wales: A Study of Urinary Steroids

The levels of aetiocholanolone, androsterone, and 17-hydroxycorticosteroids were measured in women without known disease of the breast, in women with benign breast disease, and in women with primary and advanced breast cancer. Statistical analysis showed there was no difference in the excretion of urinary 17-hydroxycorticosteroids in the various groups of patients. Detailed analysis of the aetiocholanolone and androsterone levels, however, indicated that patients with advanced localized disease excreted significantly less of these 11-deoxy-17-oxosteroids than those in the other groups.     

C-反应蛋白及CD146在慢性肾脏病中的诊断意义

目的:探讨C-反应蛋白(CRP)及CD146在慢性肾脏病(CKD)诊断中的意义。方法:测定52例非透析CKD患者血CRP及肾功能指标,分析它们之间的相关性;ELISA方法(酶联免疫吸附实验)对52例慢性肾脏疾病患者与20例正常人进行外周血CD146检测结果进行统计学分析。结果:血循环CRP随肾功能减退而增高(P<0.01),CRP与肾小球滤过率(GFR)呈负相关(r=-0.648,P<0.001);各期肾损伤疾患的外周血CD146均有不同程度的升高,与正常对照组比较,差异均有统计学意义(P<0.05)。结论:CD146和C-反应蛋白的联合检测能较好地反映CKD患者的肾功能进展情况。     

The Epidemiology of Chronic Kidney Disease in Northern Tanzania: A Population-Based Survey

Background

In sub-Saharan Africa, kidney failure has a high morbidity and mortality. Despite this, population-based estimates of prevalence, potential etiologies, and awareness are not available.

Methods

Between January and June 2014, we conducted a household survey of randomly-selected adults in Northern Tanzania. To estimate prevalence we screened for CKD, which was defined as an estimated glomerular filtration rate ≤ 60 ml/min/1.73m2 and/or persistent albuminuria. We also screened for human immunodeficiency virus (HIV), diabetes, hypertension, obesity, and lifestyle practices including alcohol, tobacco, and traditional medicine use. Awareness was defined as a self-reported disease history and subsequently testing positive. We used population-based age- and gender-weights in estimating prevalence, and we used generalized linear models to explore potential risk factors associated with CKD, including living in an urban environment.

Results

We enrolled 481 adults from 346 households with a median age of 45 years. The community-based prevalence of CKD was 7.0% (95% CI 3.8-12.3), and awareness was low at 10.5% (4.7-22.0). The urban prevalence of CKD was 15.2% (9.6-23.3) while the rural prevalence was 2.0% (0.5-6.9). Half of the cases of CKD (49.1%) were not associated with any of the measured risk factors of hypertension, diabetes, or HIV. Living in an urban environment had the strongest crude (5.40; 95% CI 2.05-14.2) and adjusted prevalence risk ratio (4.80; 1.70-13.6) for CKD, and the majority (79%) of this increased risk was not explained by demographics, traditional medicine use, socioeconomic status, or co-morbid non-communicable diseases (NCDs).

Conclusions

We observed a high burden of CKD in Northern Tanzania that was associated with low awareness. Although demographic, lifestyle practices including traditional medicine use, socioeconomic factors, and NCDs accounted for some of the excess CKD risk observed with urban residence, much of the increased urban prevalence remained unexplained and will further study as demographic shifts reshape sub-Saharan Africa.     

Uncoupling Protein 2 Expression Modulates Obesity in Chronic Kidney Disease Patients

Background:Obesity is a multifactorial metabolic disease resulting from behavioral and genetic factors. Obesity is linked to diabetes mellitus and hypertension, which are considered as major risk factors for chronic kidney disease (CKD); moreover, it has a direct effect on developing CKD and end stage renal disease (ESRD). Here was aimed to examine the association between uncoupling protein 2 (UCP2) gene expression and obesity in CKD patients. Methods:UCP2 gene expression was analyzed by real time polymerase chain reaction (RT-PCR) in 93 participants divided into three groups. The groups included 31 non-obese CKD patients, 31 obese CKD patients, and 31 healthy, age-matched, unrelated volunteers as a control group. Results:UCP2 gene expression was significantly relevant when comparing the non-obese CKD and obese CKD groups to the control group (p< 0.001). No significant association was found when the groups were compared by gender; Chi-square (X2) was 2.38 and p= 0.304. A significant negative correlation was found between UCP2 gene expression and BMI in CKD (p< 0.05).Conclusion:These results indicate that UCP2 gene expression plays a significant role as a risk factor for obesity in CKD patients. Key Words: Chronic Kidney Disease (CKD), Obesity, Uncoupling Protein 2 (UCP2) Gene Expression, Real-Time Polymerase Chain Reaction (RT-PCR)