Clinical Risk Factors For Kidney Tubule Biomarker Abnormalities Among Hypertensive Adults With Reduced eGFR in the SPRINT Trial

Urinary β2-Microglobulin Predicts the Risk of Hypertension in Populations Chronically Exposed to Environmental Cadmium

Chronic exposure to the pollutant cadmium (Cd) is inevitable for most people because it is present in nearly all food types. Concerningly, the risk of developing hypertension has been linked to dietary Cd exposure lower than 58 µg/day for a 70 kg person. The mechanisms involved are, however, unclear. Since the kidneys play an indispensable role in long-term blood pressure regulation, and they are also the main site of Cd accumulation and toxicity, a retrospective analysis was conducted to examine if kidney damage and malfunction, reflected by urinary β2-microglobulin excretion (Eβ2M), and the estimated glomerular filtration rate (eGFR), are related to Cd excretion (ECd) and blood pressure variation. Data were obtained from 689 Thai Nationals without diabetes or occupational exposure to Cd, of which 32.4% had hypertension and 7.3% had β2-microglobulinuria, defined as an increase in the β2M excretion rate ≥ 300 µg/g creatinine. Respective prevalence odds ratio (POR) and 95% confidence interval (CI) values for β2-microglobulinuria and hypertension were 10.7 (1.36-83.4), p = 0.024 and 2.79 (1.60-4.87) p < 0.001, comparing the top quartile of ECd with the bottom quartile. Only in subjects with eGFR below 90 mL/min/1.73 m2 did systolic blood pressure (SBP) and diastolic blood pressure (DBP) both increase linearly with Eβ2M (respective β = 0.182 and 0.192 for SBP and DBP) after adjustment for age, body mass index, gender, and smoking. The present study confirms the significant impact of Cd on the risk of having hypertension, following GFR loss induced by Cd. A simple mediation model analysis for cause-effect inference has provided, for the first time, evidence that may link rising SBP and DBP in Cd-exposed people to a novel role of β2M as a predictor of blood pressure variability.

Urinary Biomarkers Of Kidney Function As Predictors Of Cardiovascular Health: A Systematic Review

PURPOSE OF REVIEW

The growing burden of cardiovascular diseases has become a significant concern in both adult and youth populations. Urinary biomarkers of kidney function could provide useful insights that may aid in the early identification of individuals at higher risk of adverse cardiovascular outcomes. This systematic review aimed to assess associations between urinary biomarkers of kidney function and different measures of cardiovascular health.

RECENT FINDINGS

PubMed, Scopus, and EBSCOhost were searched for articles published between January 2018 and December 2023. Studies exploring associations between urinary kidney biomarkers (alpha-1 microglobulin (uA1M), neutrophil gelatinase-associated lipocalin (uNGAL), uromodulin (uUMOD) and CKD273 classifier) and measures of cardiovascular health (blood pressure and markers of target organ damage) were included. We identified 1186 articles, with 22 studies eligible for inclusion. Among 12 studies reporting associations between uA1M and measures of cardiovascular health, six studies indicated positive associations with office blood pressure and three studies observed associations with different markers of target organ damage. Out of the nine studies that explored the link between uUMOD and cardiovascular health parameters, four found negative associations between uUMOD and blood pressure. With regard to uNGAL, only two out of the seven studies analysed reported varying associations with blood pressure, while neither of the two studies focusing on CKD273 observed any statistically significant results. Biomarkers of kidney tubule function, represented by uA1M and uUMOD, are relevant in the setting of cardiovascular health and should be assessed for utilisation in clinical practice to identify adverse cardiovascular outcomes at an early stage allowing for timely intervention.

Albuminuria in People Chronically Exposed to Low-Dose Cadmium Is Linked to Rising Blood Pressure Levels

Exposure to low-dose environmental pollutant cadmium (Cd) increases the risks of both albuminuria and hypertension by mechanisms which are poorly understood. Here, multiple regression and mediation analyses were applied to data from 641 Thai subjects of whom 39.8%, 16.5%, 10.8%, and 4.8% had hypertension, albuminuria, diabetes, and chronic kidney disease (CKD), defined as the estimated glomerular filtration rate (eGFR) ≤ 60 mL/min/1.73 m2, respectively. To correct for interindividual differences in urine dilution and surviving nephrons, the excretion rates of Cd (ECd), albumin (Ealb), and β2-microglobulin (Eβ2M) were normalized to the creatinine clearance (Ccr) as ECd/Ccr, Ealb/Ccr, and Eβ2M/Ccr. The respective risks of having CKD and hypertension rose to 3.52 (95% CI: 1.75, 7.05) and 1.22 (95% CI: 1.12, 1.3) per doubling of the Cd body burden. The respective risk of having albuminuria increased 2.95-fold (p = 0.042) and 4.17-fold (p = 0.020) in subjects who had hypertension plus severe and extremely severe tubular dysfunction, defined according to the elevated β2M excretion rates. In multiple regression analysis, the Ealb/Ccr increased linearly with both the systolic blood pressure (SBP, β = 0.263) and diastolic blood pressure (DBP, β = 0.150), while showing an inverse association with eGFR (β = -0.180). The mediation model analyses inferred that a declining eGFR induced by Cd contributed to 80.6% of the SBP increment (p = 0.005), which then fully mediated an elevation of albumin excretion (p < 0.001). The present study provides, for the first time, evidence that causally links Cd-induced eGFR reductions to blood pressure elevations, which enhance albumin excretion.

Phenotyping Kidney Function in Young Adults With High Blood Pressure: The African-PREDICT Study

Biomarkers of kidney function, including glomerular, tubular, and fibrotic markers, have been associated with blood pressure in elderly populations and individuals with kidney and cardiovascular diseases. However, limited information is available in young adults. In this study, we compared levels of several kidney function biomarkers between normotensive and hypertensive young adults and explored the associations of these biomarkers with blood pressure within these groups. In this cross-sectional assessment, twenty-four-hour (24-h) blood pressure measurements of 1055 participants (mean age = 24.6 years) were used to classify hypertension as per the 2018 ESC/ESH guidelines. Biomarkers of kidney function included estimated glomerular filtration rate, urinary albumin, alpha-1 microglobulin (uA1M), neutrophil gelatinase-associated lipocalin (uNGAL), uromodulin (uUMOD), and the CKD273 classifier. All urinary biomarkers, except for the CKD273 classifier, were standardized for urinary creatinine (Cr). In the hypertensive group (61.0% White; 73.2% men), urinary albumin-to-creatinine ratio (uACR), uNGAL/Cr and uUMOD/Cr were lower than the normotensive group. In multiple regression analyses, 24-h systolic blood pressure (SBP) (β = 0.14; p = 0.042), 24-h diastolic blood pressure (DBP) (β = 0.14; p = 0.040), and 24-h mean arterial pressure (MAP) (β = 0.16; p = 0.020) associated positively with uA1M/Cr in the hypertensive group, while 24-h MAP positively associated with uACR (β = 0.17; p = 0.017). In exploratory factor analysis, positive associations of 24-h DBP and 24-h MAP with a factor pattern including tubular biomarkers were observed in the hypertensive group (24-h DBP: β = 0.18; p = 0.026, 24-h MAP: β = 0.17; p = 0.032). In the setting of hypertension, high perfusion pressure in the kidneys may play a role in the development of proximal tubule damage and promote early deterioration in kidney function in young adults. Trial Registration: ClinicalTrials.gov identifier: NCT03292094.

YKL-40 as a biomarker in various inflammatory diseases: A review

YKL-40 or Chitinase-3-Like Protein 1 (CHI3L1) is a highly conserved glycoprotein that binds heparin and chitin in a non-enzymatic manner. It is a member of the chitinase protein family 18, subfamily A, and unlike true chitinases, YKL-40 is a chitinase-like protein without enzymatic activity for chitin. Although its accurate function is yet unknown, the pattern of its expression in the normal and disease states suggests its possible engagement in apoptosis, inflammation and remodeling or degradation of the extracellular matrix. During an inflammatory response, YKL-40 is involved in a complicated interaction between host and bacteria, both promoting and attenuating immune response and potentially being served as an autoantigen in a vicious circle of autoimmunity. Based on its pathophysiology and mechanism of action, the aim of this review was to summarize research on the growing role of YKL-40 as a persuasive biomarker for inflammatory diseases' early diagnosis, prediction and follow-up (e.g., cardiovascular, gastrointestinal, endocrinological, immunological, musculoskeletal, neurological, respiratory, urinary, infectious) with detailed structural and functional background of YKL-40.