Serum albumin concentration and risk of end-stage renal disease: the REGARDS study

Association of Urinary Cadmium Concentration With Cognitive Impairment in US Adults: A Longitudinal Cohort Study

BACKGROUND AND OBJECTIVES

Studies have indicated that cadmium (Cd) exposure is associated with neurotoxicity. However, data linking Cd exposure to cognitive impairment are sparse. We aimed to investigate the association between urinary Cd concentration and cognitive impairment in US adults.

METHODS

The REasons for Geographic and Racial Differences in Stroke (REGARDS) study is an ongoing population-based prospective cohort study that enrolled 30,239 Black and White US adults aged 45 years or older at baseline (2003-2007). In a randomly selected subcohort of REGARDS participants who were free of cognitive impairment or stroke at baseline, certain trace element concentrations, including urinary creatinine-corrected Cd, were measured using biospecimens collected and stored at baseline. During an average of 10 years of follow-up, global cognitive impairment was assessed annually using the Six-Item Screener, and domain-based cognitive impairment, including verbal learning, memory, and executive function, was evaluated every other year using the Enhanced Cognitive Battery. Multivariable-adjusted logistic regression models were used to examine the association between urinary Cd concentration and the odds of global or domain-based cognitive impairment.

RESULTS

A total of 2,172 participants (mean age: 64.1 ± 9.0 years; female: 54.8%; Black participants: 38.7%) with available data on urinary Cd concentration, including 195 cases of global cognitive impairment and 53 cases of domain-based cognitive impairment, were included in the analyses. While there was no association between Cd and cognitive impairment in the full sample, there was a significant positive association of urinary Cd concentration with global cognitive impairment among White but not Black participants. The odds of cognitive impairment for White participants in the high urinary Cd concentration group (≥median) were doubled compared with those in the low urinary Cd group (odds ratio 2.07, 95% CI 1.18-3.64). Sex, age, region, smoking pack-years, alcohol consumption, and other related metals did not materially modify the associations of interest.

DISCUSSION

Findings from this prospective cohort study suggest that urinary Cd concentrations are associated with global cognitive impairment among White but not Black individuals. Further studies with repeatedly measured Cd exposure, larger sample sizes, and longer duration are needed to confirm our findings and explore the potential explanations for the observed racial discrepancy, such as the impact of smoking.

Synergistic modulation of endoplasmic reticulum stress pathway, oxidative DNA damage and apoptosis by β-amyrin and metformin in mitigating hyperglycemia-induced renal damage using adult zebrafish model

Diabetic nephropathy (DN) can be prevented with early therapeutic intervention in diabetic patients. Recent investigations suggest that β-amyrin, a pentacyclic triterpenoid, could offer significant benefits with its potential antihyperglycemic and nephroprotective effects. We investigated the protective effects of β-amyrin alone and combined it with metformin, the cornerstone therapy for diabetes, using a hyperglycemic adult Zebrafish (ZF) model. The ZF were subjected to hyperglycemia by immersing them in 111 mM glucose solutions. Treatment efficacy was assessed by measuring serum glucose and insulin levels and antioxidant, ER stress, apoptosis, and proinflammatory markers. ZF kidneys were also studied for immunohistochemistry and histopathology. Results revealed that the combined treatment of β-amyrin and metformin resulted in a significant decrease (p ≤ 0.05) in blood glucose levels to 104.54 ± 1.63 mg/dL, in comparison to 388.75 ± 4.32 mg/dL in the untreated diseased control group. The reduction in hyperglycemia was more pronounced than treatment with either compound alone. Moreover, treatment with the combination restored renal function in diseased ZF, leading to significantly lower (p ≤ 0.05) serum urea (SU: 19.57 ± 1.61 mg/dL) and serum creatinine (SC: 0.56 ± 0.02 mg/dL) values compared to treatment with β-amyrin (SU:27.02 ± 0.96 mg/dL; SC: 0.7 ± 0.01 mg/dL) or metformin (SU: 24.53 ± 1.29 mg/dL; SC: 0.6 ± 0.02 mg/dL) alone. The treatment also reduced oxidative stress markers, apoptosis and ER stress markers, and proinflammatory cytokines. Histopathological analysis showed improved renal architecture with significantly lower (p ≤ 0.05) renal tubular injury scores with the combination than with individual treatment. This study provides novel insights into the combined therapeutic effects of β-amyrin and metformin in mitigating hyperglycemia-induced renal damage through key molecular pathways, highlighting a potentially effective therapeutic strategy for diabetic nephropathy. The findings hold promising translational relevance for developing combination therapies aimed at improving clinical outcomes in diabetic nephropathy patients.

Nephrotic syndrome: pathophysiology and consequences

In patients with kidney disease, nephrotic syndrome can lead to several complications including progressive kidney dysfunction. Proteinuria may lead to the formation of cellular or fibrous crescents with reciprocal development of rapidly progressive glomerulonephritis or focal glomerulosclerosis. Proteinuria may also cause overload and dysfunction of tubular epithelial cells, eventually resulting in tubular atrophy and interstitial fibrosis. Hypoalbuminemia is usually associated with increased risk of mortality and kidney dysfunction. Dyslipidemia may increase the risk of atherosclerotic complications, cause podocyte dysfunction and contribute to vascular thrombosis. Urinary loss of anticoagulants and overproduction of coagulation factors may facilitate a hypercoagulable state. Edema, hypogammaglobulinemia, loss of complement factors, and immunosuppressive therapy can favor infection. Treatment of these complications may reduce their impact on the severity of NS. Nephrotic syndrome is a kidney disorder that can worsen the quality of life and increase the risk of kidney disease progression.

Persistence of Depressive Symptoms and Risk of Incident Cardiovascular Disease With and Without Diabetes: Results from the REGARDS Study

BACKGROUND

Baseline depressive symptoms are associated with subsequent adverse cardiovascular (CV) events in subjects with and without diabetes but the impact of persistent symptoms vs. improvement remains controversial.

OBJECTIVE

Examine long-term changes in depressive symptoms in individuals with and without diabetes and the associated risk for adverse CV events.

DESIGN

REGARDS is a prospective cohort study of CV risk factors in 30,000 participants aged 45 years and older.

PARTICIPANTS

N = 16,368 (16.5% with diabetes mellitus) who remained in the cohort an average of 11.1 years later and who had complete data.

MAIN MEASURES

Depressive symptoms were measured using the 4-item Centers for Epidemiologic Study of Depression (CES-D) questionnaire at baseline and again at a mean follow-up of 5.07 (SD = 1.66) years. Adjudicated incident stroke, coronary heart disease (CHD), CV mortality, and a composite outcome were assessed in a subsequent follow-up period of 6.1 (SD = 2.6) years.

METHODS

The association of changes in depressive symptoms (CES-D scores) across 5 years with incident CV events was assessed using Cox proportional hazards modeling.

KEY RESULTS

Compared to participants with no depressive symptoms at either time point, participants without diabetes but with persistently elevated depressive symptoms at both baseline and follow-up demonstrated a significantly increased risk of incident stroke (HR (95% CI) = 1.84 (1.03, 3.30)), a pattern which was substantially more prevalent in blacks (HR (95% CI) = 2.64 (1.48, 4.72)) compared to whites (HR (95% CI) = 1.06 (0.50, 2.25)) and in those not taking anti-depressants (HR (95% CI) = 2.01 (1.21, 3.35)) in fully adjusted models.

CONCLUSIONS

The persistence of depressive symptoms across 5 years of follow-up in participants without diabetes identifies individuals at increased risk for incident stroke. This was particularly evident in black participants and among those not taking anti-depressants.

Impact of the Nutrition-Inflammation Status on the Functionality of Patients with Chronic Kidney Disease

Functional capacity of chronic kidney disease (CKD) patients is compromised by their nutrition-inflammation status. We evaluated the functional capacity of advanced chronic kidney disease (ACKD) patients and the influence of the nutrition-inflammation status. In a cross-sectional study, which included ACKD patients from the nephrology department of the Hospital Universitario de la Princesa in Madrid, Spain, we assessed: functional capacity with the Short Physical Performance Battery (SPPB) test, interpreting a result <7 in the test as low functionality; body composition with monofrequency bioimpedance; muscular strength with hand grip strength; nutritional and inflammatory status using biochemical parameters and the Malnutrition Inflammation Scale (MIS). A total of 255 patients with ACKD were evaluated, 65.8% were men, their mean age was 70.65 ± 11.97 years and 70.2% of the patients had an age >65 years. The mean score of SPPB was 8.50 ± 2.81 and 76.4% of the patients presented a score ≥7, with a higher percentage in the group of men. The percentage of patients with limitations increased with age. The patients with SPPB values higher than 7 showed high values of albumin and low soluble C-reactive protein (s-CRP) and MIS. We found better functionality in well-nourished patients. A multivariate logistic regression model established an association of high albumin values with a better functional capacity (OR: 0.245 CI: 0.084−0.714 p < 0.010), while another model showed an association between CRP values and decreased functionality (OR: 1.267 CI: 1.007−1.594 p = 0.044). Conclusion: nutritional status and body composition influence on the functional capacity of patients with ACKD.

Development and implementation of patient-level prediction models of end-stage renal disease for type 2 diabetes patients using fast healthcare interoperability resources

This study aimed to develop a model to predict the 5-year risk of developing end-stage renal disease (ESRD) in patients with type 2 diabetes mellitus (T2DM) using machine learning (ML). It also aimed to implement the developed algorithms into electronic medical records (EMR) system using Health Level Seven (HL7) Fast Healthcare Interoperability Resources (FHIR). The final dataset used for modeling included 19,159 patients. The medical data were engineered to generate various types of features that were input into the various ML classifiers. The classifier with the best performance was XGBoost, with an area under the receiver operator characteristics curve (AUROC) of 0.95 and area under the precision recall curve (AUPRC) of 0.79 using three-fold cross-validation, compared to other models such as logistic regression, random forest, and support vector machine (AUROC range, 0.929–0.943; AUPRC 0.765–0.792). Serum creatinine, serum albumin, the urine albumin-to-creatinine ratio, Charlson comorbidity index, estimated GFR, and medication days of insulin were features that were ranked high for the ESRD risk prediction. The algorithm was implemented in the EMR system using HL7 FHIR through an ML-dedicated server that preprocessed unstructured data and trained updated data.

Low albumin levels are independently associated with neonatal acute kidney injury: a report from AWAKEN Study Group

BACKGROUND

Data from adult and pediatric literature have shown an association between albumin levels and AKI. Whether hypoalbuminemia and neonatal AKI are associated has not been studied.

METHODS

We evaluated the association of albumin with early (during the first postnatal week) and late (after the first postnatal week) AKI for 531 neonates from the Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN) database and for 3 gestational age (GA) subgroups: < 29, 29 to < 36, and ≥ 36 weeks GA.

RESULTS

Low albumin levels were associated with increased odds of neonatal AKI; for every 0.1 g/dL decrease in albumin, the odds of late AKI increased by 12% on continuous analysis. After adjustment for potential confounders, neonates with albumin values in the lowest quartiles (< 2.2 g/dL) had an increased odds of early [Adjusted Odd Ratio (AdjOR) 2.5, 95% CI = 1.1-5.3, p < 0.03] and late AKI [AdjOR 13.4, 95% CI = 3.6-49.9, p < 0.0001] compared to those with albumin in the highest quartile (> 3.1 g/dL). This held true for albumin levels 2.3 to 2.6 g/dL for early [AdjOR 2.5, 95% CI = 1.2-5.5, p < 0.02] and late AKI [AdjOR 6.4, 95% CI = 1.9-21.6, p < 0.01]. Albumin quartiles of (2.7 to 3.0 g/dL) were associated with increased odds of late AKI. Albumin levels of 2.6 g/dL and 2.4 g/dL best predicted early (AUC = 0.59) and late AKI (AUC = 0.64), respectively. Analysis of albumin association with AKI by GA is described.

CONCLUSIONS

Low albumin levels are independently associated with early and late neonatal AKI. Albumin could be a potential modifiable risk factor for neonatal AKI.

Association Between Serum Albumin Levels and Obesity and Risk of Developing Chronic Kidney Disease Using Data from the Korean Multi-Rural Communities Cohort (MRCohort) Population Database

Background

The Multi-Rural Communities Cohort (MRCohort) was established as part of the Korean Genome and Epidemiology Study, which identified risk factors for cardiovascular diseases in the population between January 2005 and December 2011. This was a prospective study, aimed to investigate the association between serum albumin levels and the risk of developing chronic kidney disease (CKD) in obese patients using data from the MRCohort population database.

Material/Methods

For analysis, we selected a total of 9695 people from the MRCohort from 2004 to 2013: 3105 people from Goryeong, 3183 from Yangpyeong, and 3407 from Namwon, without previous history of myocardial infarction, cerebrovascular disease, cancer, and CKD, or missing values on confounders. As a result, 2300 metabolically healthy participants were studied as a whole, and then by body mass index of >23 kg/m². The groups were divided into 4 subgroups by albumin quartiles, and the effects of albumin levels compared to the lowest quartile were studied by Cox proportional hazard analysis, after adjusting for potential confounders.

Results

The results showed that the highest quartile of albumin, compared to the lowest quartile, was a protective factor of CKD development only in the overweight and obese group with adjusted hazard ratio (HR)=0.38 (95% confidence interval (CI) 0.16–0.95, p<0.05). In the normal-weight group, results were insignificant, with adjusted HR=0.54 (95% CI 0.24–1.25, not significant).

Conclusions

Data from the Korean MRCohort population database showed that obesity and increased serum albumin levels were protective factors for the development of CKD.

Serum Albumin Modifies the Effect of Peripheral Blood Monocytes on Severity of Diabetic Nephropathy in an Adult Population

BACKGROUND

Our aim in this study was to characterize clinical associations between peripheral blood immune populations and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus.

METHODS

We queried hospital records from an outpatient diabetes primary care clinic between 2018 and 2019 for clinical and laboratory data, including complete blood counts with differentials, serum albumin and globulin, glycated hemoglobin (A1C) and urine albumin-to-creatinine ratio. One hundred ninety-eight patients had complete cross-sectional data with temporally proximate complete blood counts and urine albumin-to-creatinine ratios. After univariable correlation assessment, we used a forward multivariable linear regression model to test the hypothesis that higher numbers of circulating innate immune populations would be associated with DKD, while accounting for known demographic, clinical and laboratory risk factors. We defined DKD as an albumin-to-creatinine ratio of >3 mg/mmol or an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m² from the Chronic Kidney Disease Epidemiology Collaboration.

RESULTS

Adjusted analyses demonstrated significant (p<0.01) associations between higher urine albumin:creatinine ratio and peripheral circulating monocytes, independent of other established significant risk factors, including blood pressure, A1C, age and sex. We also identified serum albumin as a potentially important modifying factor of albuminuric kidney disease, which interacts with monocytes in more advanced disease. In contrast, the variable most strongly predictive of eGFR was age.

CONCLUSIONS

Circulating monocytes and serum albumin are significantly associated with albuminuria, but not eGFR in DKD. These results support the potential role of the innate immune system in diabetic microvascular end-organ damage and urinary protein loss, and may be readily translatable clinical markers to incorporate into risk-assessment models for prognostication in diabetes.

Sept8/SEPTIN8 involvement in cellular structure and kidney damage is identified by genetic mapping and a novel human tubule hypoxic model

Chronic kidney disease (CKD), which can ultimately progress to kidney failure, is influenced by genetics and the environment. Genes identified in human genome wide association studies (GWAS) explain only a small proportion of the heritable variation and lack functional validation, indicating the need for additional model systems. Outbred heterogeneous stock (HS) rats have been used for genetic fine-mapping of complex traits, but have not previously been used for CKD traits. We performed GWAS for urinary protein excretion (UPE) and CKD related serum biochemistries in 245 male HS rats. Quantitative trait loci (QTL) were identified using a linear mixed effect model that tested for association with imputed genotypes. Candidate genes were identified using bioinformatics tools and targeted RNAseq followed by testing in a novel in vitro model of human tubule, hypoxia-induced damage. We identified two QTL for UPE and five for serum biochemistries. Protein modeling identified a missense variant within Septin 8 (Sept8) as a candidate for UPE. Sept8/SEPTIN8 expression increased in HS rats with elevated UPE and tubulointerstitial injury and in the in vitro hypoxia model. SEPTIN8 is detected within proximal tubule cells in human kidney samples and localizes with acetyl-alpha tubulin in the culture system. After hypoxia, SEPTIN8 staining becomes diffuse and appears to relocalize with actin. These data suggest a role of SEPTIN8 in cellular organization and structure in response to environmental stress. This study demonstrates that integration of a rat genetic model with an environmentally induced tubule damage system identifies Sept8/SEPTIN8 and informs novel aspects of the complex gene by environmental interactions contributing to CKD risk.