The Promise of Tubule Biomarkers in Kidney Disease: A Review

Long nighttime sleep duration and risk of renal tubular damage: evidence from rural China and a Mendelian randomization analysis

OBJECTIVE

Renal tubular damage, a pivotal pathological feature of chronic kidney disease (CKD), predicts disease progression. While extreme nighttime sleep duration is linked to glomerular injury by prior studies, its impact on tubular damage remains unclear. Given that 7-9 h of sleep per night is widely recommended for maintaining overall health, this study aimed to assess whether long nighttime sleep duration is associated with renal tubular damage using both observational and genetic evidence.

METHODS

We analyzed 2,683 adults in rural China to assess the link between nighttime sleep duration and renal tubular damage (measured by retinol-binding protein and β2-microglobulin). Mendelian randomization (MR) analysis was performed to assess the causal relationship between prolonged nighttime sleep duration and elevated kidney injury molecule-1 (KIM-1) levels.

RESULTS

Multivariate logistic regression indicated that sleeping more than 9 h per night was associated with a 1.38-fold increased risk of renal tubular damage (95% CI: 1.11-1.71) compared to 7-9 h of sleep, with particularly pronounced effects observed in elderly individuals and women. MR analysis further supported a causal relationship between genetically predicted long nighttime sleep duration and elevated KIM-1 levels (β: 0.994, 95% CI: 0.282-1.707), suggesting a genetic predisposition linking prolonged sleep duration with renal tubular damage.

CONCLUSIONS

Our findings provide observational and genetic evidence linking prolonged nighttime sleep to increased renal tubular damage risk. Given that 7-9 h of sleep per night is the widely accepted recommendation for maintaining overall health, our results emphasize the potential risks of excessive sleep duration exceeding 9 h.

Epithelial-Immune-Stromal Interactions Define Divergent Repair and Fibrosis Pathways After Acute Kidney Injury in Human Renal Transplants

Acute kidney injury (AKI) is a major cause of early graft dysfunction after kidney transplantation, particularly in recipients of high-risk donor kidneys prone to ischemia-reperfusion injury. However, the cellular mechanisms dictating whether injury resolves or progresses to fibrosis remain unclear. This study combines single-nucleus RNA sequencing and imaging mass cytometry (IMC) analysis of human kidney allograft biopsies collected within eight weeks posttransplant, stratified by long-term functional outcomes. Grafts that recovered function were enriched in regenerative proximal tubular (PT) cells co-expressing PROM1, CD24, and injury markers, consistent with scattered tubular cells (STCs). In contrast, non-recovering grafts contained a unique subpopulation of transitional proximal tubule cells (tPT4) characterized by dedifferentiation, loss of epithelial identity, and acquisition of fibroblast-like features. Fibroblast trajectory analysis revealed a profibrotic lineage, progressing from stromal progenitors to myofibroblasts, exclusive to nonrecovery grafts. Immune profiling showed divergent macrophage (MΦ) polarization, with reparative MΦ2 cells and regulatory dendritic cell (DC)-like signatures in recovering grafts, versus inflammatory MΦ1 and pro-fibrotic DCs in non-recovery. IMC confirmed spatial colocalization of injured tubules, activated fibroblasts, and immune cells in fibrotic regions, validated in an independent cohort. Functional assays demonstrated that ischemic epithelial injury activated monocyte-derived MΦs with mixed inflammatory/reparative profiles and induced fibroblast-related gene expression, while PAX8 knockdown impaired epithelial proliferation and promoted pro-inflammatory signaling. These findings reveal epithelial cell plasticity as a central driver of divergent repair outcomes following renal transplant AKI and highlight epithelial-immune-stromal crosstalk as a therapeutic target to promote recovery and prevent chronic graft injury.

One Sentence Summary

Single-cell and spatial mapping of human kidney transplants reveal regenerative and fibrotic cell programs across tubular, immune, and stromal compartments that determine whether acute injury resolves or progresses to chronic allograft injury.

Defining Kidney Health Dimensions and Their Associations with Adverse Outcomes in Persons with Diabetes and CKD

Key Points

We identified three kidney health dimensions using 17 urine and plasma biomarkers across two cohorts of persons with diabetes and CKD. Worse scores for tubule injury, tubule function, and systemic inflammation/filtration were associated with a higher risk of CKD progression and death. A multibiomarker approach could help capture tubulointerstitial health in persons with diabetes and CKD.

Background

Individual kidney tubule biomarkers are associated with risks of CKD progression and mortality in persons with diabetes. Integrating multiple kidney biomarkers using a latent variable method of exploratory factor analysis could define distinct dimensions of kidney health and their associations with adverse outcomes.

Methods

We conducted a factor analysis of 17 candidate urine and plasma biomarkers in 1256 participants with diabetes and eGFR <60 ml/min per 1.73 m2 from the Chronic Renal Insufficiency Cohort (CRIC; N =701) and the REasons for Geographic And Racial Differences in Stroke (REGARDS; N =555) studies. We used Cox proportional hazards models to evaluate the associations of identified factors with CKD progression and mortality, adjusting for baseline clinical risk factors, eGFR, and albuminuria.

Results

Three factor scores comprising ten biomarkers were identified: systemic inflammation and filtration (plasma TNF receptor-1 and TNF receptor-2, plasma soluble urokinase plasminogen activator receptor, and plasma symmetric dimethylarginine), tubular function (urine EGF, urine asymmetric dimethylarginine, and urine symmetric dimethylarginine), and tubular damage (urine α -1 microglobulin, urine kidney injury molecule-1, and urine monocyte chemoattractant protein-1). In CRIC, there were 244 incident ESKD events, 102 with ≥40% eGFR decline from baseline, and 259 deaths; in REGARDS, there were 121 incident ESKD events and 462 deaths. In CRIC, lower tubular function (hazard ratio per 1-SD, 0.36; 95% confidence interval, 0.25 to 0.52) and higher tubular damage (1.45; 1.18 to 1.78) scores were independently associated with higher CKD progression risk. Associations in REGARDS were weaker but directionally consistent (tubular function score [0.81; 0.47 to 1.39] and tubular damage score [1.12; 0.73 to 1.72]). Higher tubular damage (1.47; 1.15 to 1.87) scores were associated with higher mortality risk in CRIC, but not REGARDS (1.15; 0.96 to 1.38). Higher systemic inflammation and filtration factor scores were associated with higher mortality risk in both cohorts (CRIC: 1.35; 1.07 to 1.71; REGARDS: 1.41; 1.20 to 1.65).

Conclusions

Three distinct kidney health dimensions were identified, and each associated with CKD progression and/or all-cause mortality in persons with diabetes and CKD.

Associations of Urine Biomarkers During Ambulatory Acute Kidney Injury With Subsequent Recovery in Kidney Function: Findings From the SPRINT Study

RATIONALE & OBJECTIVE

Serum creatinine elevations in the ambulatory setting frequently occur during antihypertensive treatment and complicate clinical management, but few tools are available to distinguish whether kidney function will recover in this setting. This study evaluated if urine biomarkers of glomerular and tubular health are associated with subsequent recovery of eGFR after acute kidney injury (AKI) occurred in the ambulatory setting during blood pressure treatment.

STUDY DESIGN

Longitudinal analysis of clinical trial participants.

SETTING & PARTICIPANTS

652 participants in the Systolic Blood Pressure Intervention Trial (SPRINT) who developed AKI in the ambulatory setting, defined as a rise in serum creatinine of ≥0.3 mg/dL from baseline detected at the 1-year or 2-year study visits.

EXPOSURE

Eight urine biomarkers measured at baseline and at the study visit when ambulatory AKI was detected.

OUTCOME

<50% recovery in eGFR ("non-recovery") at 12-months.

ANALYTICAL APPROACH

Multivariable logistic regression models, stratified by randomization arm, to evaluate biomarker associations with the odds of non-recovery in eGFR.

RESULTS

Mean age was 70 ±10 years; eGFR at baseline was 62 ± 25 mL/min/1.73 m2, and eGFR at the time of serum creatinine elevation was 42 ± 12 mL/min/1.73 m2. Among biomarkers measured at the time ambulatory AKI was detected, higher urine albumin (OR per 1-SD higher: 1.72; 95% CI: 1.10, 2.70) and lower epidermal growth factor (OR 0.46; 95% CI: 0.26, 0.79) were associated with non-recovery in the standard BP treatment arm; higher urine α-1 microglobulin (OR 1.45; 1.09, 1.92), lower epidermal growth factor (OR 0.62; 95% CI: 0.46, 0.83) and lower kidney injury molecule-1 (OR 0.75; 95% CI: 0.59, 0.96) were associated with non-recovery of eGFR in the intensive BP treatment arm.

LIMITATIONS

Persons with diabetes and proteinuria >1 g/d were excluded.

CONCLUSIONS

Among adults enrolled in a BP treatment trial who developed ambulatory AKI, urine biomarkers reflecting glomerular injury and tubular dysfunction may help to distinguish whether kidney function will subsequently recover.

PLAIN-LANGUAGE SUMMARY

Elevations in serum creatinine can occur when treating hypertension and complicate clinical management, but there are few tools available to distinguish whether an individual's kidney function will subsequently recover. In this study, we investigated the association of kidney biomarkers measured in the urine with subsequent kidney function among individuals in the outpatient setting who develop a rise in serum creatinine. We found that biomarkers reflecting worse glomerular injury and tubular dysfunction are associated with the risk of an individual's kidney function not recovering. These results suggest that a broader assessment of kidney health when serum creatinine increases in the outpatient setting may help distinguish subsequent trajectories in kidney function.

Uranium exposure and kidney tubule biomarkers in the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Experimental studies indicate that uranium exposure is toxic to the kidney tubules. We evaluated the association of urinary uranium concentrations with biomarkers of tubule cell dysfunction (alpha-1-microglobulin [A1M], uromodulin [UMOD], epidermal growth factor [EGF]), and tubule cell injury (kidney injury molecule-1 [KIM-1], monocyte chemoattractant protein-1 [MCP-1], and chitinase-3-like protein 1 [YKL-40]), as well as with albuminuria and estimated glomerular filtration rate (eGFR) among participants in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

We conducted a cross-sectional study that included 461 participants selected for the absence of diabetes, chronic kidney disease (CKD), and cardiovascular disease, evaluated with six kidney tubule biomarker measurements. Urinary uranium concentrations were measured using inductively coupled plasma mass spectrometry in spot urine samples. Linear models were used to determine associations of urinary uranium concentrations with each kidney tubule biomarker, calculated by the geometric mean ratio (GMR), after adjustment for participant's urinary creatinine concentrations, age, sex, race/ethnicity, MESA field center, highest level of education completed, cigarette smoking status, alcohol consumption, body mass index (BMI), albuminuria levels, and eGFR.

RESULTS

Median (interquartile range) urinary uranium concentration was 5.2 (2.9, 10.4) ng/L, and mean (standard deviation) eGFR was 99 (16) mL/min/1.73 m2. The adjusted GMRs (95%CI) of KIM-1 and MCP-1 were 1.11 (1.01, 1.22) and 1.10 (1.01, 1.20), respectively per 7.5 ng/L (interquartile range) higher urinary uranium concentration, while no statistically significant associations were observed for YKL-40, A1M, UMOD, EGF, albuminuria, or eGFR. In flexible dose-response models, the associations were positive and largely linear between urinary uranium concentrations and higher KIM-1 and MCP-1.

CONCLUSIONS

Among healthy community-living individuals, chronic low-level uranium exposure, as measured in urine, was associated with markers of kidney tubule cell injury. Chronic low-level uranium exposure observed in contemporary US urban centers may adversely affect kidney tubule health and related outcomes.

Urinary presepsin can efficiently detect T-cell-mediated rejection in patients who have undergone kidney transplantation

Urinary presepsin (uPSEP) is a marker of tubular interstitial injury. For patients who have undergone kidney transplantation, the early diagnosis of rejection is important to early treatment and preservation of the transplanted kidney function. We investigated whether uPSEP is useful for predicting T-cell-mediated rejection (TCMR). Patients who underwent graft biopsy in 2020 and 2023 after kidney transplantation at our hospital were included. We excluded protocol biopsy samples obtained at 1 h. We measured uPSEP and divided the patients into groups based on the presence or absence of TCMR; then, group comparisons were performed. A total of 39 patients (17 female and 22 male patients) with a median age of 57 years (interquartile range [IQR], 46.5-63 years) at the time of biopsy were included. Thirty-one patients underwent protocol biopsies and eight underwent episode biopsies. TCMR occurred in three patients. The uPSEP value of the TCMR group was 6788.63 ng/gCr (IQR, 5374.57-9931.87 ng/gCr), and that of the non-TCMR group was 777.61 ng/gCr (IQR, 321.57-1299.63 ng/gCr) (P < 0.01). The receiver-operating characteristic curve for predicting TCMR had a cutoff value of 3961 ng/gCr and an area under the curve of 0.982 (95% confidence interval [CI], 0.942-1). The odds ratio of TCMR based on uPSEP (per 1000-ng/gCr increase in uPSEP) was 1.90 (95% CI, 1.10-3.28; P = 0.02). uPSEP levels may predict TCMR with high accuracy.

Dietary Polyunsaturated Fatty Acid Deficiency Impairs Renal Lipid Metabolism and Adaptive Response to Proteinuria in Murine Renal Tubules

Background/Objectives: Kidneys are fatty acid (FA)-consuming organs that use adenosine triphosphate (ATP) for tubular functions, including endocytosis for protein reabsorption to prevent urinary protein loss. Peroxisome proliferator-activated receptor α (PPARα) is a master regulator of FA metabolism and energy production, with high renal expression. Although polyunsaturated fatty acids (PUFAs) are essential nutrients that are natural PPARα ligands, their role in tubular protein reabsorption remains unclear. As clinical PUFA deficiency occurs in humans under various conditions, we used a mouse model that mimics these conditions. Methods: We administered a 2-week intraperitoneal protein-overload (PO) treatment to mice that had been continuously fed a PUFA-deficient diet. We compared the phenotypic changes with those in mice fed a standard diet and those in mice fed a PUFA-deficient diet with PUFA supplementation. Results: In the absence of PO, the PUFA-deficient diet induced increased lysosomal autophagy activation; however, other phenotypic differences were not detected among the diet groups. In the PO experimental condition, the PUFA-deficient diet increased daily urinary protein excretion and tubular lysosomes; suppressed adaptive endocytosis activation, which was probably enhanced by continuous autophagy activation; and worsened FA metabolism and PPARα-mediated responses to PO, which disrupted renal energy homeostasis. However, these changes were attenuated by PUFA supplementation at the physiological intake level. Conclusions: PUFAs are essential nutrients for the tubular adaptive reabsorption response against urinary protein loss. Therefore, active PUFA intake may be important for patients with kidney disease-associated proteinuria, especially those with various PUFA deficiency-inducing conditions.

Ubiquitin-specific peptidase 10 promotes renal interstitial fibrosis progression through deubiquitinating and stabilizing P53 protein

Renal interstitial fibrosis is the main factor determining chronic kidney disease (CKD) progression, and renal tubular epithelial cells are the key drivers of this pathological process. Herein, we revealed significantly increased ubiquitin-specific peptidase 10 (USP10) expression in the kidney tissues of both patients with CKD and mice induced by unilateral ureteral obstruction, as well as in transforming growth factor-beta 1 (TGFβ1)-induced renal tubular epithelial cells. In vivo, treatment with the USP10 small molecule inhibitor Spautin-1, which inhibits its deubiquitinating activity, weakened renal interstitial fibrosis progression and alleviated the subsequent inflammatory response and oxidative stress in male mice. In vitro, knocking down USP10 or inhibiting its deubiquitinating activity through Spautin-1 significantly reduced fibronectin expression and ameliorated TGFβ1-induced renal tubular epithelial cell dedifferentiation. Additionally, our results revealed that USP10 directly binds to P53 and removes the K48-linked polyubiquitin chains from P53, thereby affecting its ubiquitination, stability, and nuclear translocation, which subsequently leads to the upregulation of P21 and promotes fibrotic gene expression in injured renal tubular epithelial cells, ultimately exacerbating renal interstitial fibrosis. In conclusion, USP10 is inhibited through the P53 signaling pathway to alleviate the progression of renal interstitial fibrosis and serve as a potential target for treating CKD.

Role of LncRNA in Pathogenesis, Diagnosis and Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is a clinical syndrome of metabolic disorder caused by progressive kidney impairment for more than 3 months. CKD has become a global public health problem due to its high morbidity and mortality, which is difficult to be cured for most patients. The pathogenesis of CKD is still unclear, which is closely related to glomerulosclerosis, kidney tubular injury and kidney fibrosis. LncRNA is a non-coding RNA with a length of more than 200 nucleotides. It not only participates in intracellular transcriptional regulation, post-transcriptional regulation and epigenetic activities, but also forms a regulatory network together with miRNA and mRNA, to further conduct the reticular regulation in cells. Recently, it has been found that lncRNA participates in pathophysiological mechanism of CKD by regulating glomerulosclerosis, kidney tubular injury and kidney fibrosis. This has also become a new direction of lncRNA in early diagnosis and targeted therapy of CKD.

Clinical implications of proximal tubular multicilia in glomerular diseases

Introduction

Multiciliated cells (MCCs) have been identified in the proximal tubules of patients with kidney disease; however, their clinical significance is unknown. We aimed to investigate whether MCCs are associated with clinical outcomes in patients with glomerular diseases.

Methods

Between August 2012 and April 2021, 134 patients (including 126 with glomerular disease patients and 8 controls) who were hospitalized at Seoul National University Boramae Medical Center and Seoul National University Hospital were included in this study. The ratio of MCCs to total proximal tubular cells was calculated using immunohistochemistry. The relationship between the MCC ratio and kidney disease-related clinical features was then analyzed.

Results

MCCs were exclusively detected in patients with glomerular diseases (68.3 %), not those in the control group. Patients with diabetic kidney disease (88.9 %) or antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (GN, 86.4 %) had higher MCC ratios. MCC-positivity and MCC ratios were significantly associated with increased age and proteinuria, and a decreased estimated glomerular filtration rate (eGFR). Patients with higher MCC ratios had a significantly higher risk of end-stage kidney disease (ESKD) and composite outcomes with death. In multivariable analysis, MCC ratios were significantly correlated with an increased risk of ESKD (hazard ratio [HR], 1.413; 95 % confidence interval [CI], 1.012-1.972) and composite outcome (HR, 1.401; 95 % CI, 1.028-1.909).

Conclusion

Higher MCC ratios were correlated with poorer prognosis; therefore, quantification of MCCs in the proximal tubules can serve as a valuable prognostic marker in clinical practice.

LOX-induced tubulointerstitial fibrosis via the TGF-β/LOX/Snail axis in diabetic mice

BACKGROUND

The partial epithelial-mesenchymal transition (EMT) is emerging as a significant mechanism in diabetic nephropathy (DN). LOX is a copper amine oxidase conventionally thought to act by crosslinking collagen. However, the role of LOX in partial EMT and fibrotic progression in diabetic nephropathy has not been investigated experimentally.

METHODS

The bulk RNA sequencing and single-nuclei RNA sequencing (snRNA-seq) analysis were explored to find the role of LOX in diabetic nephropathy. We then investigated the partial EMT and the possible signaling pathway of LOX, both in vivo and in vitro by LOX inhibition experiments in diabetic mice and HK-2 cells. Besides, we further assessed kidney fibrosis and renal function.

RESULTS

LOX expression was elevated in kidneys of diabetic mice. Additionally, snRNA-seq results indicated that LOX expression was higher in partial epithelial-mesenchymal transition proximal tubular (PemtPT) epithelial cells. Moreover, we found that increased LOX prompted partial EMT of renal tubular epithelial cells (RTECs) by modulating the transcription factor Snail both in vivo and in vitro. Remarkably, inhibition of LOX effectively mitigated the partial EMT of RTECs in diabetic mice, thereby attenuating kidney fibrosis and enhancing renal function. Additionally, we identified the TGF-β signaling pathway as an upstream regulator of LOX, and inhibiting LOX partially reversed the partial EMT program in HK-2 cells induced by the TGF-β signaling pathway.

CONCLUSIONS

Hyperglycemia induces partial EMT of RTECs via the TGF-β/LOX/Snail axis, thereby contributing to diabetic kidney fibrosis. Inhibiting LOX can effectively reverse the partial EMT of RTECs, diminish diabetic kidney fibrosis, and improve renal function.

Mendelian Randomization Studies: Opening a New Window in the Study of Metabolic Diseases and Chronic Kidney Disease

It is widely recognized that a strong correlation exists between metabolic diseases and chronic kidney disease (CKD). Based on bibliometric statistics, the overall number of Mendelian randomization (MR) analysis in relation to metabolic diseases and CKD has increased since 2005. In recent years, this topic has emerged as a significant area of research interest. In clinical studies, RCTs are often limited due to the intricate causal interplay between metabolic diseases and CKD, which makes it difficult to ascertain the precise etiology of these conditions definitively. In MR studies, genetic variation is incorporated as an instrumental variable (IV). They elucidate the possible causal relationships between associated risk factors and disease risks by including individual innate genetic markers. It is widely believed that MR avoids confounding and can reverse effects to the greatest extent possible. As an increasingly popular technology in the medical field, MR studies have become a popular technology in causal relationships investigation, particularly in epidemiological etiology studies. At present, MR has been widely used for the investigation of medical etiologies, drug development, and decision-making in public health. The article aims to offer insights into the causal relationship between metabolic diseases and CKD, as well as strategies for prevention and treatment, through a summary of MR-related research on these conditions.

Tubular MYDGF Slows Progression of Chronic Kidney Disease by Maintaining Mitochondrial Homeostasis

Mitochondrial dysfunction is a key event driving the maladaptive repair of tubular epithelial cells during the transition from acute kidney injury to chronic kidney disease (CKD). Therefore, identifying potential targets involved in mitochondrial dysfunction in tubular epithelial cells is clinically important. Myeloid-derived growth factor (MYDGF), a novel secreted protein, plays important roles in multiple cardiovascular diseases, but the function of MYDGF in tubular epithelial cells remains unknown. In the present study, it is found that MYDGF expression is significantly reduced in the cortex of the kidney, especially in the proximal tubules, from mice with CKD. Notably, lower expression of MYDGF is observed in tubules from patients with CKD and the level of MYDGF correlated with key factors related to kidney fibrosis and estimated glomerular filtration rate (eGFR) in patients with CKD. Tubule-specific deletion of Mydgf exacerbates kidney injury in mice with CKD; however, Mydgf overexpression attenuates kidney fibrosis by remodeling mitochondrial homeostasis in tubular epithelial cells. Mechanistically, renal tubular MYDGF positively regulates the expression of isocitrate dehydrogenase 2 (IDH2), restores mitochondrial homeostasis, and slows CKD progression. Thus, this study indicates that MYDGF derived from tubules may be an effective therapeutic strategy for patients with CKD.

Estimated Proximal Tubule Fluid Phosphate Concentration and Renal Tubular Damage Biomarkers in Early Stages of Chronic Kidney Disease

OBJECTIVE

An increase in proximal tubule fluid phosphate concentration is caused by increased serum fibroblast growth factor-23 (FGF23) levels, which resulted in renal tubular damage in a mouse model of chronic kidney disease (CKD). However, few human studies have supported this concept. This study aimed to explore the association among estimated proximal tubule fluid phosphate concentration (ePTFp), serum FGF23 levels, and renal tubular damage biomarkers in middle-aged and older populations with mild decline in renal function.

METHODS

This cross-sectional study included 218 participants aged ≥45 with CKD stages G2-G4. Anthropometric measurements, blood tests, spot urine biomarkers, renal ultrasonography, cardiovascular assessment, smoking status, and medication usage were obtained in the morning in fasted states. The ePTFp was calculated using serum creatinine, urine phosphate, and creatinine concentrations. Urinary β2-microglobulin (β2-MG) and liver-type fatty acid-binding protein (L-FABP) levels were evaluated to assess renal tubular damage.

RESULTS

PTFp, serum FGF23, urinary β2-MG, and urinary L-FABP levels increased with CKD stage progression (stages G2, G3, and G4). However, serum and urine phosphate concentrations were comparable across the CKD stages. Univariate analysis revealed a stronger correlation of ePTFp with serum FGF23, urinary β2-MG, and urinary L-FABP levels than with the corresponding serum and urine phosphate concentrations. Multivariate analyses demonstrated that increased ePTFp was independently associated with elevated serum FGF23 and urinary β2-MG levels, even after adjusting for potential covariates, including the estimated glomerular filtration rate and urinary albumin-to-creatinine ratio.

CONCLUSIONS

Our results are consistent with the concept in mouse model and suggest that increased ePTFp are associated with increased serum FGF23 levels and renal tubular damage during the early stages of CKD.

Urinary presepsin is a novel biomarker capable of directly assessing monocyte/macrophage infiltration in kidney diseases

Serum presepsin levels are elevated during sepsis and are widely employed in clinical practice. However, the association between urinary presepsin and kidney diseases remains elusive. Given that monocytes/macrophages, primary presepsin producers, are closely associated with the pathophysiology of nephritis, we explored the potential of urinary presepsin as a kidney disease biomarker. In a cross-sectional study involving patients who underwent kidney biopsy (n = 463 patients; 43% female, median age 58 years), the median urinary presepsin/creatinine levels were 590 (interquartile range [IQR], 244-1276), 1023 (IQR, 491-2749), 1429 (IQR, 644-2725), and 3518 (IQR, 2084-6321) ng/g creatinine, indicating minimal (< 5%), mild (5-25%), moderate (26-50%), and severe (> 50%) interstitial inflammatory cell infiltration in biopsy samples, respectively. The area under the curve of urinary presepsin/creatinine (0.81) had a higher accuracy for distinguishing severe interstitial inflammatory cell infiltration than that of the N-acetyl-β-D-glucosaminidase/creatinine (0.70) (P = 0.003). The tubulointerstitial nephritis group had the highest urinary presepsin/creatinine level. Immunofluorescence staining revealed that monocytes and macrophages predominantly expressed presepsin in the kidney interstitium, with the stained area positively and significantly correlated with presepsin/creatinine values (r = 0.57, P = 0.02). Urinary presepsin could be a biomarker for directly assessing monocyte/macrophage infiltration in kidney disease.

Plasma Biomarkers of Kidney Health and Mortality in Diabetes and Chronic Kidney Disease in the REGARDS Study

Key Points

In diabetes and CKD, creatinine- and cystatin C–based eGFR has a strong inverse correlation with plasma TNF receptor 1, TNF receptor 2, and soluble urokinase-type plasminogen activator receptor. Higher plasma soluble TNF receptors 1 and 2 and soluble urokinase-type plasminogen activator receptor were each individually associated with mortality, independent of baseline kidney measures.

Background

Several plasma biomarkers of kidney health have been associated with CKD progression in persons with diabetes, but their associations with mortality risk have been largely unexplored.

Methods

In a random sample of 594 participants with diabetes and creatinine-based eGFR <60 ml/min per 1.73 m2 from the REGARDS cohort study, Cox proportional hazards regression was used to determine hazard ratios of mortality by plasma concentrations of soluble TNF receptors 1 and 2 (TNFR1 and TNFR2), soluble urokinase-type plasminogen activator receptor (suPAR), kidney injury molecule 1 (KIM-1), chitinase 3–like 1 (YKL-40), and monocyte chemotactic protein 1 (MCP-1). Covariates included sociodemographic and clinical factors, urine albumin-to-creatinine ratio (UACR), and creatinine- and cystatin C–based eGFR (eGFRcr-cys).

Results

At baseline, the mean age was 70 years, 47% were male, 53% self-identified as Black, mean±SD eGFRcr-cys was 41±13 ml/min per 1.73 m2, and median (interquartile range) UACR was 32 (9–224) mg/g. Correlations with eGFRcr-cys were stronger for TNFR1, TNFR2, and suPAR (r =−0.72 to −0.76) than for KIM-1, YKL-40, and MCP-1 (r =−0.10 to −0.40). With a median follow-up of 7 years, 332 participants died. In models adjusted for sociodemographic and clinical factors, each SD higher baseline concentration of plasma TNFR1 (hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.20 to 1.38), TNFR2 (HR, 1.61; 95% CI, 1.42 to 1.82), suPAR (HR, 1.33; 95% CI, 1.22 to 1.44), KIM-1 (HR, 1.20; 95% CI, 1.08 to 1.33), and YKL-40 (HR, 1.23; 95% CI, 1.11 to 1.38) was associated with higher risk of all-cause mortality, whereas MCP-1 was not. Upon further adjustment for baseline eGFRcr-cys and UACR, only the associations for TNFR1 (HR, 1.16; 95% CI, 1.04 to 1.29), TNFR2 (HR, 1.34; 95% CI, 1.12 to 1.60), and suPAR (HR, 1.23; 95% CI, 1.11 to 1.36) persisted.

Conclusions

Among adults with diabetes and CKD, higher plasma TNFR1, TNFR2, and suPAR were associated with all-cause mortality, independent of baseline kidney function.

Exploring therapeutic mechanisms of Chuan Huang Fang-II in the treatment of acute kidney injury on chronic kidney disease patients from the perspective of lipidomics

OBJECTIVE

This study aims to assess the clinical efficacy and safety of CHF-II in combination with RG for treating AKI on CKD (A on C), and to explore potential therapeutic mechanisms through lipidomics analysis.

METHODS

98 patients were enrolled and randomly assigned to the RG or RG + CHF groups. Both groups received RG therapy, with RG + CHF group additionally receiving CHF-II treatment over a duration of two weeks. Evaluation endpoints included changes in renal function, blood lipid profiles, urinary AKI biomarkers, and TCM symptoms before and after treatment. Serum samples were collected for lipid metabolite analysis.

RESULTS

The total clinical effective rate in RG + CHF group was 73.5%, and that of RG group was 40.8%. TCM syndrome scores in RG + CHF group showed a more pronounced decrease (p < 0.05). Scr, BUN, and UA levels decreased while eGFR levels increased in both groups (p < 0.05), with a greater magnitude of change observed in the RG + CHF group. Urinary AKI biomarkers decreased more in RG + CHF group (p < 0.05). No serious adverse events occurred during the trial. 58 different lipid metabolites and 48 lipid biomarkers were identified. According to the KEGG database, the possible metabolic pathways involved triglyceride metabolic pathway and fat digestion and absorption metabolic pathways.

CONCLUSION

CHF-II effectively alleviated kidney injury and improved TCM syndrome scores in patients with A on C. Lipid differential metabolites could serve as diagnostic indicators for AKI in patients with CKD. The possible metabolic pathways might be implicated in therapeutic action of CHF-II in the prevention and treatment of patients with A on C.

Single-cell RNA sequencing in diabetic kidney disease: a literature review

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD), and its pathogenesis has not been clarified. Current research suggests that DKD involves multiple cell types and extra-renal factors, and it is particularly important to clarify the pathogenesis and identify new therapeutic targets. Single-cell RNA sequencing (scRNA-seq) technology is high-throughput sequencing of the transcriptomes of individual cells at the single-cell level, which is an effective technology for exploring the development of diseases by comparing genetic information, reflecting the differences in genetic information between cells, and identifying different cell subpopulations. Accumulating evidence supports the role of scRNA-seq in revealing the pathogenesis of diabetes and strengthening our understanding of the molecular mechanisms of DKD. We reviewed the scRNA-seq data this time. Then, we analyzed and discussed the applications of scRNA-seq technology in DKD research, including annotation of cell types, identification of novel cell types (or subtypes), identification of intercellular communication, analysis of cell differentiation trajectories, gene expression detection, and analysis of gene regulatory networks, and lastly, we explored the future perspectives of scRNA-seq technology in DKD research.

Absence of Kidney Tubular Injury in Patients With Acute Heart Failure With Acute Kidney Injury

BACKGROUND

Worsening renal function (WRF) is common in hospitalized patients being treated for acute heart failure. However, discriminating clinically significant WRF remains challenging. In patients hospitalized with acute heart failure, we evaluated if blood and urine biomarkers of cardiac and kidney dysfunction were associated with adverse outcomes.

METHODS

We identified 175 of 927 participants in the AKINESIS study (Acute Kidney Neutrophil Gelatinase-Associated Lipocalin Evaluation of Symptomatic Heart Failure Study) who met criteria for stage 1 or 2 Kidney Disease: Improvement Global Outcomes acute kidney injury during the first 3 days of hospitalization. We measured 24 blood and urine biomarkers from specimens collected within 24 hours of meeting acute kidney injury criteria. The primary composite outcome consisted of worsening WRF (higher acute kidney injury stage), need for dialysis, or death at 30 days. Biomarkers' association with the composite outcome was assessed with logistic regression by tertiles and area under the curve (AUC).

RESULTS

Of the 175 participants, 32 (18%) developed the primary composite outcome. Only history of chronic kidney disease was significantly different between those with and without the composite outcome. The highest tertile of plasma Gal-3 (galectin-3) and urine epidermal growth factor were associated with increased odds of the composite outcome compared with the lowest tertile in unadjusted analyses. After adjusting for serum creatinine, systolic blood pressure, and blood urea nitrogen, only the highest tertile of Gal-3 was associated with greater odds of the composite outcome (odds ratio, 4.6 [95% CI, 1.4-16.0). Gal-3 had the highest AUC (0.70 [95% CI, 0.58-0.82]), while epidermal growth factor had a lower AUC (0.63 [95% CI, 0.53-0.74]). Notably, urine biomarkers of kidney tubule injury were not associated with the composite outcome.

CONCLUSIONS

Tubular injury does not occur in most patients with acute heart failure experiencing WRF, consistent with the functional mechanisms of WRF in this patient population.

REGISTRATION

URL: https://www.clinicaltrials.gov/study/NCT01291836?term=NCT01291836&rank=1; Unique identifier: NCT01291836.

Kidney Injury Evoked by Fine Particulate Matter: Risk Factor, Causation, Mechanism and Intervention Study

Fine particulate matter (PM2.5) is suggested to pose a severe risk to the kidneys by inducing functional degradation and chronic kidney diseases (CKD). This study aims to explore the nephrotoxicity of PM2.5 exposure and the underlying mechanism. Herein, based on the UK Biobank, it is found that per interquartile range (IQR) increase in PM2.5 is associated with a 6% (95% CI: 1%-11%), 7% (95% CI: 3%-11%), 9% (95% CI: 4%-13%), 11% (95% CI: 9%-13%), and 10% (95% CI: 8%-12%) increase in the risk of nephritis, hydronephrosis, kidney stone, acute renal failure, and CKD, respectively. In experimental study, noticeable kidney injury, which is the initiation of kidney diseases, is observed with PM2.5 exposure in C57BL/6N mice (n = 8), accompanied with oxidative stress, autophagy and pyroptosis. In vitro, HK-2 cells with PM2.5-stimulation exhibit tubulopathy, increased reactive oxygen species (ROS) generation and activated pyroptosis and autophagy. All changes are abolished by ROS scavenger of N-acetyl-L-cysteine (NAC) both in vivo and in vitro. In conclusion, the study provides evidence showing that PM2.5 exposure is associated with 5 kinds of kidney diseases by directly inducing nephrotoxicity, in which ROS may be the potential target by triggering autophagy and pyroptosis.

Pharmacokinetic profiling of ZCL-278, a cdc42 inhibitor, and its effectiveness against chronic kidney disease

ZCL-278 is a selective small molecule specifically inhibiting the Cdc42-intersectin interaction, yet its in-vivo pharmacokinetic and pharmacodynamic properties against renal diseases had not been determined. Thus, our study explored the absorption, distribution and excretion of ZCL-278 as well as its pharmacological efficacy against chronic kidney disease (CKD). With the optimized detection method, absolute oral bioavailability of ZCL-278 was determined as 10.99 % in male and 17.34 % in female rats. ZCL-278 was rapidly and abundantly distributed in various tissues, especially the kidney and heart, while few excreted through urine and feces. In the adenine-induced CKD mice, the increased plasma creatinine and urea, the decreased body weight as well as the renal pathological alterations, including vacuolization of renal tubular epithelial cells, granular degeneration, cell flattening, luminal dilation, and cylindruria, were significantly ameliorated after ZCL-278 administration. Moreover, ZCL-278 could also reverse the increased intensities of renal inflammation and fibrosis in the CKD mice. These results clarified the pharmacokinetics of ZCL-278 in rats and preliminarily indicated that ZCL-278 has favorable pharmacodynamic properties for CKD primed for lead development and optimization, warranting further drug development.

Iron metabolism indexes as predictors of the incidence of cardiac surgery-associated acute kidney surgery

BACKGROUND

Acute kidney injury (AKI) is a major complication following cardiac surgery. We explored the clinical utility of iron metabolism indexes for identification of patients at risk for AKI after cardiac surgery.

METHODS

This prospective observational study included patients who underwent cardiac surgery between March 2023 and June 2023. Iron metabolism indexes were measured upon admission to the intensive care unit. Multivariable logistic regression analyses were performed to explore the relationship between iron metabolism indexes and cardiac surgery-associated AKI (CSA-AKI). Receiver operating characteristic (ROC) curve was used to assess the predictive ability of iron, APACHE II score and the combination of the two indicators. Restricted cubic splines (RCS) was used to further confirm the linear relationship between iron and CSA-AKI.

RESULTS

Among the 112 recruited patients, 38 (33.9%) were diagnosed with AKI. Multivariable logistic regression analysis indicated that APACHE II score (odds ratio [OR], 1.208; 95% confidence interval [CI], 1.003-1.455, P = 0.036) and iron (OR 1.069; 95% CI 1.009-1.133, P = 0.036) could be used as independent risk factors to predict CSA-AKI. ROC curve analysis showed that iron (area under curve [AUC] = 0.669, 95% CI 0.572-0.757), APACHE II score (AUC = 0.655, 95% CI 0.557-0.744) and iron and APACHE II score combination (AUC = 0.726, 95% CI 0.632-0.807) were predictive indicators for CSA-AKI. RCS further confirmed the linear relationship between iron and CSA-AKI.

CONCLUSIONS

Elevated iron levels were independently associated with higher risk of CSA-AKI, and there was a linear relationship between iron and CSA-AKI.

A Comprehensive Review of Biomarkers for Chronic Kidney Disease in Older Individuals: Current Perspectives and Future Directions

Chronic kidney disease (CKD) is a progressive condition characterized by a gradual loss of kidney function, leading to significant health complications and an increased risk of cardiovascular events. Early detection and effective management are crucial for slowing disease progression and improving patient outcomes. Biomarkers are valuable tools in CKD diagnosis, prognosis, and treatment. Traditional biomarkers, such as serum creatinine and urine protein, are widely used, but emerging biomarkers like cystatin C, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) offer enhanced diagnostic precision and insights into disease severity. These advanced biomarkers are particularly important in older adults, who may present with age-related physiological changes and comorbid conditions that complicate CKD management. This review explores the current state of biomarker research in CKD, focusing on their application in older populations. It highlights the role of traditional and emerging biomarkers, discusses their relevance for early detection and prognosis, and examines future directions in biomarker research, including technological innovations and personalized medicine approaches. By integrating biomarkers into clinical practice, healthcare providers can achieve more accurate diagnoses, tailor treatments to individual patient needs, and potentially improve the overall management of CKD. Continued research and development in this field are essential for addressing the complexities of CKD and advancing patient care.

Functional state of the kidneys in patients with acute coronary syndrome against the background of newly identified disorders of carbohydrate metabolism: a multidisciplinary problem

BACKGROUND

Determining the relationship between cardiovascular risks, carbohydrate metabolism disorders, and renal dysfunction can help in creating new tools for their management and for better interaction of specialists in a multidisciplinary team. The purpose of this study was to determine the functional state of the kidneys and carbohydrate metabolism in patients with acute coronary syndrome without a history of such disorders.

METHODS

200 patients of the cardiology department of the City Clinical Hospital No. 7 in Almaty were examined using laboratory diagnostics and subsequent statistical data processing.

RESULTS

Acute coronary syndrome develops in 63% of cases against the background of previous disorders of carbohydrate metabolism - prediabetes (45.5%) and type 2 diabetes mellitus (17.5%). In this group of patients, in the presence of disorders of carbohydrate metabolism, in all cases, it is accompanied by acute renal damage. It was noted that diabetes mellitus in newly diagnosed patients actually had a certain duration and occurred much earlier than cardiovascular complications - this was evidenced by an increased level of glycated hemoglobin.

CONCLUSIONS

Such results indicate the need for early diagnosis of cardio-reno-metabolic syndrome in patients with cardiovascular complications, as well as timely administration of drugs that simultaneously have antidiabetic, cardio- and nephroprotective effects.

Is renal dysfunction amplified in an arginine vasopressin induced rat model of preeclampsia?

Renal dysfunction is important in preeclampsia (PE) pathophysiology and has not been fully explored in the arginine vasopressin (AVP) rat model of PE. This study aimed to determine kidney toxicity associated with this model. Female Sprague Dawley rats (n = 24) were subcutaneously infused with AVP or saline for 18 days. Urine samples (GD8, 14 and 18) were used to determine the levels of albumin, VEGF-A, clusterin, NGAL/Lipocalin-2, KIM-1, cystatin C, TIMP-1, β2M and OPN via Multiplex ELISAs. Albumin, and NGAL/lipocalin-2 were significantly elevated in the PAVP vs PS group on GD14 and GD18 (p < 0.001) respectively. VEGF-A significantly decreased in the pregnant vs non-pregnant groups on GD14 and 18 (p < 0.001). Clusterin (p < 0.001) and OPN (p < 0.05) were significantly higher in the PAVP vs PS group on GD18. Cystatin C and KIM-1 are significantly upregulated in the PAVP vs PS groups throughout gestation (p < 0.05). β2M is significantly elevated in the PAVP vs PS group on GD14 and 18 (p < 0.05). AVP elevated the urinary levels of the kidney injury biomarkers and replicated the renal dysfunction associated with PE development. Our findings confirm the potential applications of this model in studying the mechanisms underlying renal damage in PE.

Emerging multisystem biomarkers in hereditary transthyretin amyloidosis: a pilot study

Hereditary transthyretin (ATTRv) amyloidosis is a rare, adult-onset, progressive, multisystemic condition caused by TTR pathogenic variants. Reliable biomarkers are needed to allow early diagnosis and to monitor disease severity and progression. We measured serum concentrations of growth differentiation factor-15 (GDF-15) and uromodulin (Umod) in ATTRv patients to evaluate correlations with standard markers of disease severity (FAP stage and PND score). Blood samples were collected from 16 patients diagnosed with ATTRv amyloidosis and a verified TTR variant and from 26 healthy controls. ATTRv patients were stratified by clinical phenotype (neurologic vs. mixed), genotype (V30M vs. non-V30M), and disease severity. We found significantly higher levels of serum GDF-15 in ATTRv patients compared with controls. Mean serum Umod levels were significantly lower in patients with ATTRv than controls. A positive correlation was found between serum Umod and estimated glomerular filtration rate (eGFR), while an inverse correlation was found with cystatin C levels. Conversely, GDF-15 showed a negative correlation with eGFR, and a direct correlation with cystatin C levels. No correlation was demonstrated between GDF-15 or Umod levels and traditional cardiac biomarkers. The results identify alteration of serum levels of GDF-15 and Umod in ATTRv amyloidosis.

CAR, mGPS and hs-mGPS: What is among them the best gero-biomarker for age-related diseases? And for what clinical application?

The identification of biomarkers linked to the onset, progression, and prevention of age-related diseases (ARD), in the era of personalized medicine, represents the best goal of geroscience. Geroscience has the fundamental role of exploring and identifying the biological mechanisms of aging to suggest interventions capable of stopping/delaying the many pathological conditions and disabilities related to age. Therefore, it has become its key priority, as well as that of clinical practice and research, based on identifying and validating a range of biomarkers, geromarkers, which can be used to diagnostic, prognostic, or predictive clinical purposes. Indeed, geromarkers have, the potential to predict ARD trajectories and facilitate targeted interventions to slow down the related disabilities. Here our attention is paid to the inflammatory indexes (CAR, mGPS, hs-mGPS) linked to the relationship between the plasma levels of two inflammatory analytes, the typical positive protein of the acute phase, and the negative one, i.e. c-reactive protein (CRP) and albumin, respectively. These indexes allow us to understand the magnitude of the two main mechanisms predicted to influence the aging process, including inflammation and immunosenescence, as well as the degree of ARD severity. Evidence on their relationship with ARD is widely reported and discussed, to understand which can represent the best ARD geromarker, and its clinical application.

Hepatic-derived BMP9 is involved in hepatic fibrosis-induced kidney injury through inhibition of renal VEGFA

Clinical observations suggest that acute kidney injury (AKI) occurs in approximately 20-50% of hospitalized cirrhotic patients, suggesting a link between the liver and kidney. Bone morphogenetic protein 9 (BMP9) is a protein produced primarily by the liver and can act on other tissues at circulating systemic levels. Previous studies have demonstrated that controlling abnormally elevated BMP9 in acute liver injury attenuates liver injury; however, reports on whether BMP9 plays a role in liver injury-induced AKI are lacking. By testing we found that liver injury in mice after bile duct ligation (BDL) was accompanied by a significant upregulation of the kidney injury marker kidney injury molecule (KIM-1). Interestingly, all these impairments were alleviated in the kidneys of hepatic BMP9 knockout (BMP9-KO) mice. Peritubular capillary injury is a key process leading to the progression of AKI, and previous studies have demonstrated that vascular endothelial growth factor A (VEGFA) plays a key role in maintaining the renal microvascular system. In animal experiments, we found that high levels of circulating BMP9 had an inhibitory effect on VEGFA expression, while renal tubular epithelial cell injury was effectively attenuated by VEGFA supplementation in the hypoxia-enriched-oxygen (H/R) constructs of the AKI cell model in both humans and mice. Overall, we found that elevated BMP9 in hepatic fibrosis can affect renal homeostasis by regulating VEGFA expression. Therefore, we believe that targeting BMP9 therapy may be a potential means to address the problem of clinical liver fibrosis combined with AKI.

Biomarkers of chronic kidney disease in older individuals: navigating complexity in diagnosis

Chronic kidney disease (CKD) in older individuals is a matter of growing concern in the field of public health across the globe. Indeed, prevalence of kidney function impairment increases with advancing age and is often exacerbated by age-induced modifications of kidney function, presence of chronic diseases such as diabetes, hypertension, and cardiovascular disorders, and increased burden related to frailty, cognitive impairment and sarcopenia. Accurate assessment of CKD in older individuals is crucial for timely intervention and management and relies heavily on biomarkers for disease diagnosis and monitoring. However, the interpretation of these biomarkers in older patients may be complex due to interplays between CKD, aging, chronic diseases and geriatric syndromes. Biomarkers such as serum creatinine, estimated glomerular filtration rate (eGFR), and albuminuria can be significantly altered by systemic inflammation, metabolic changes, and medication use commonly seen in this population. To overcome the limitations of traditional biomarkers, several innovative proteins have been investigated as potential, in this review we aimed at consolidating the existing data concerning the geriatric aspects of CKD, describing the challenges and considerations in using traditional and innovative biomarkers to assess CKD in older patients, highlighting the need for integration of the clinical context to improve biomarkers' accuracy.

Urine biomarkers in type 2 diabetes mellitus with or without microvascular complications

OBJECTIVE

To investigate the distribution of nine (9) urine biomarkers in people living with type 2 diabetes mellitus (T2DM), with or without microvascular complications.

METHODS

In total, 407 people with T2DM were enrolled from 2021 to 2022. According to diabetic retinopathy (DR) and urinary albumin-creatinine ratio (UACR), the 407 people were divided into four (4) groups, DR(-)UACR(-), DR(+)UACR(-), DR(-)UACR(+), and DR( + )UACR(+). In addition, 112 healthy volunteers were enrolled during the same period. The nine (9) urine markers included α1-microglobulin (u-α1MG), immunoglobulin G (u-IgG), neutrophil gelatinase-associated lipid carrier protein (u-NGAL), cystatin C (u-CysC), retinol-binding protein (u-RBP), β2-microglobulin (u-β2MG), N-acetyl-β-D-glucosaminidase (u-NAG), transferrin (u-Trf), and collagen type IV (u-Col). For each marker, the respective level of 97.5 percentile in healthy volunteers was taken as an upper reference limit.

RESULTS

Among the 407 people, 248 individuals (61%) were DR(-)UACR(-), 100 (25%) were DR(-)UACR(+), 37 (9%) were DR(+)UACR(-), and 22 (5%) were DR(+)UACR(+). The u-NAG/Cr biomarker level showed a significant difference between healthy participants and people with T2DM. In the DR(-)UACR(-)group, u-Trf/Cr showed the highest positive rate (21.37%), followed by u-IgG/Cr (14.52%); u-NAG/Cr (10.48%); u-β2MG/Cr (4.44%); u-CysC/Cr (4.03%); u-NGAL/Cr (4.03%); u-RBP/Cr (2.82%); u-α1MG/Cr (2.42%); 17.34% of people with T2DM showed multiple biomarkers positive (≥2 biomarkers). The positive rates of one biomarker (21.33%) and two biomarkers (18.67%) in people who have less than five (5) years of T2DM were almost close to those of the DR(-)UACR(-) group (21.37%, and 12.10%, respectively).

CONCLUSION

Renal tubule biomarkers may be used as an indicator in the early detection and monitoring of renal injury in diabetes mellitus. The u-NAG biomarker should be measured for the people with T2DM of the first-time diagnosis.

Deciphering the molecular nexus between Omicron infection and acute kidney injury: a bioinformatics approach

Background

The ongoing global health crisis of COVID-19, and particularly the challenges posed by recurrent infections of the Omicron variant, have significantly strained healthcare systems worldwide. There is a growing body of evidence indicating an increased susceptibility to Omicron infection in patients suffering from Acute Kidney Injury (AKI). However, the intricate molecular interplay between AKI and Omicron variant of COVID-19 remains largely enigmatic.

Methods

This study employed a comprehensive analysis of human RNA sequencing (RNA-seq) and microarray datasets to identify differentially expressed genes (DEGs) associated with Omicron infection in the context of AKI. We engaged in functional enrichment assessments, an examination of Protein-Protein Interaction (PPI) networks, and advanced network analysis to elucidate the cellular signaling pathways involved, identify critical hub genes, and determine the relevant controlling transcription factors and microRNAs. Additionally, we explored protein-drug interactions to highlight potential pharmacological interventions.

Results

Our investigation revealed significant DEGs and cellular signaling pathways implicated in both Omicron infection and AKI. We identified pivotal hub genes, including EIF2AK2, PLSCR1, GBP1, TNFSF10, C1QB, and BST2, and their associated regulatory transcription factors and microRNAs. Notably, in the murine AKI model, there was a marked reduction in EIF2AK2 expression, in contrast to significant elevations in PLSCR1, C1QB, and BST2. EIF2AK2 exhibited an inverse relationship with the primary AKI mediator, Kim-1, whereas PLSCR1 and C1QB demonstrated strong positive correlations with it. Moreover, we identified potential therapeutic agents such as Suloctidil, Apocarotenal, 3'-Azido-3'-deoxythymidine, among others. Our findings also highlighted a correlation between the identified hub genes and diseases like myocardial ischemia, schizophrenia, and liver cirrhosis. To further validate the credibility of our data, we employed an independent validation dataset to verify the hub genes. Notably, the expression patterns of PLSCR1, GBP1, BST2, and C1QB were consistent with our research findings, reaffirming the reliability of our results.

Conclusion

Our bioinformatics analysis has provided initial insights into the shared genetic landscape between Omicron COVID-19 infections and AKI, identifying potential therapeutic targets and drugs. This preliminary investigation lays the foundation for further research, with the hope of contributing to the development of innovative treatment strategies for these complex medical conditions.

Urine Epidermal Growth Factor and Kidney Function Decline in Middle-Aged Adults

Rationale & Objective

The diagnosis and prognostication of chronic kidney disease (CKD) largely rely on glomerular measures that may not reflect tubular damage. We investigated the associations of urine kidney tubule biomarkers with estimated glomerular filtration rate (eGFR) change among middle-aged adults, when chronic diseases typically emerge.

Study Design

An observational cohort study.

Setting & Participants

A total of 1,145 participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study without CKD, hypertension, or cardiovascular disease at the year 20 visit.

Exposures

Seven different biomarkers of tubular health: urine epidermal growth factor (EGF), alpha-1-microglobulin (α1m), interleukin-18, kidney injury molecule-1, monocyte chemoattractant protein-1, uromodulin, and chitinase-3-like protein 1.

Outcomes

Ten-year eGFR change and incident reduced eGFR (new onset of eGFR < 60 mL/min/1.73 m2).

Analytical Approach

We examined associations of tubular health biomarkers with 10-year eGFR change and incident reduced eGFR with linear mixed models and interval-censored proportional hazards regression models, respectively. Both minimally and fully adjusted models were controlled for urine creatinine levels.

Results

The mean age of participants was 44.8 ± 3.7 years, with 39% African American and 56% female. The average 10-year change in eGFR was -18.6 mL/min/1.73 m2 (95% CI, -19.4 to -17.8). In contrast to the other tubular biomarkers, which showed conflicting results, EGF demonstrated strong, consistent associations with both kidney outcomes. Each 1-standard deviation (SD) higher EGF was associated with a 2.37 mL/min/1.73 m2 (95% CI, 0.64-4.10) smaller 10-year decrease in eGFR and a 42% (95% CI, 4%-64%) lower risk of incident reduced eGFR in the fully adjusted model.

Limitations

Observational design, measurements of eGFR were done only at 5-year intervals during follow-up.

Conclusions

In middle-aged, community-dwelling adults without hypertension, cardiovascular disease or CKD, higher urine EGF concentrations are associated with slower eGFR decline, whereas other kidney tubule biomarkers lacked a consistent association with kidney function decline.

Changes in tubular biomarkers with dietary intervention and metformin in patients with autosomal dominant polycystic kidney disease: a post-hoc analysis of two clinical trials

BACKGROUND

Tubular biomarkers, which reflect tubular dysfunction or injury, are associated with incident chronic kidney disease and kidney function decline. Several tubular biomarkers have also been implicated in the progression of autosomal dominant polycystic kidney disease (ADPKD). We evaluated changes in multiple tubular biomarkers in four groups of patients with ADPKD who participated in one of two clinical trials (metformin therapy and diet-induced weight loss), based on evidence suggesting that such interventions could reduce tubule injury.

METHODS

66 participants (26 M/40 F) with ADPKD and an estimated glomerular filtration rate (eGFR) ≥ 30 ml/min/1.73m2 who participated in either a metformin clinical trial (n = 22 metformin; n = 23 placebo) or dietary weight loss study (n = 10 daily caloric restriction [DCR]; n = 11 intermittent fasting [IMF]) were included in assessments of urinary tubular biomarkers (kidney injury molecule-1 [KIM-1], fatty-acid binding protein [FABP], interleukin-18 [IL-18], monocyte chemoattractant protein-1 [MCP-1], neutrophil gelatinase-associated lipocalin [NGAL], clusterin, and human cartilage glycoprotein-40 [YKL-40]; normalized to urine creatinine), at baseline and 12 months. The association of baseline tubular biomarkers with both baseline and change in height-adjusted total kidney volume (HtTKV; percent change from baseline to 12 months) and estimated glomerular filtration rate (eGFR; absolute change at 12 months vs. baseline), with covariate adjustment, was also assessed using multiple linear regression.

RESULTS

Mean ± s.d. age was 48 ± 8 years, eGFR was 71 ± 16 ml/min/1.73m2, and baseline BMI was 30.5 ± 5.9 kg/m2. None of the tubular biomarkers changed with any intervention as compared to placebo. Additionally, baseline tubular biomarkers were not associated with either baseline or change in eGFR or HtTKV over 12 months, after adjustments for demographics, group assignment, and clinical characteristics.

CONCLUSIONS

Tubular biomarkers did not change with dietary-induced weight loss or metformin, nor did they associate with kidney disease progression, in this cohort of patients with ADPKD.

IGFBP1 stabilizes Umod expression through m6A modification to inhibit the occurrence and development of cystitis by blocking NF-κB and ERK signaling pathways

Cystitis is a common disease closely associated with urinary tract infections, and the specific mechanisms underlying its occurrence and development remain largely unknown. In this study, we discovered that IGFBP1 suppresses the occurrence and development of cystitis by stabilizing the expression of Umod through m6A modification, inhibiting the NF-κB and ERK signaling pathways. Initially, we obtained a bladder cystitis-related transcriptome dataset from the GEO database and identified the characteristic genes Umod and IGFBP1. Further exploration revealed that IGFBP1 in primary cells of cystitis can stabilize the expression of Umod through m6A modification. Overexpression of both IGFBP1 and Umod significantly inhibited cell apoptosis and the NF-κB and ERK signaling pathways, ultimately suppressing the production of pro-inflammatory factors. Finally, using a rat model of cystitis, we demonstrated that overexpression of IGFBP1 stabilizes the expression of Umod, inhibits the NF-κB and ERK signaling pathways, reduces the production of pro-inflammatory factors, and thus prevents the occurrence and development of cystitis. Our study elucidates the crucial role of IGFBP1 and Umod in cystitis and reveals the molecular mechanisms that inhibit the occurrence and development of cystitis. This research holds promise for offering new insights into the treatment of cystitis in the future.

Tartronic Acid as a Potential Inhibitor of Pathological Calcium Oxalate Crystallization

Kidney stones are a pervasive disease with notoriously high recurrence rates that require more effective treatment strategies. Herein, tartronic acid is introduced as an efficient inhibitor of calcium oxalate monohydrate (COM) crystallization, which is the most prevalent constituent of human kidney stones. A combination of in situ experimental techniques and simulations are employed to compare the inhibitory effects of tartronic acid with those of its molecular analogs. Tartronic acid exhibits an affinity for binding to rapidly growing apical surfaces of COM crystals, thus setting it apart from other inhibitors such as citric acid, the current preventative treatment for kidney stones. Bulk crystallization and in situ atomic force microscopy (AFM) measurements confirm the mechanism by which tartronic acid interacts with COM crystal surfaces and inhibits growth. These findings are consistent with in vivo studies that reveal the efficacy of tartronic acid is similar to that of citric acid in mouse models of hyperoxaluria regarding their inhibitory effect on stone formation and alleviating stone-related physical harm. In summary, these findings highlight the potential of tartronic acid as a promising alternative to citric acid for the management of calcium oxalate nephropathies, offering a new option for clinical intervention in cases of kidney stones.

Tubular biomarkers and histology in lupus nephritis

INTRODUCTION

The relevance of tubulo-interstitial involvement for kidney prognosis has recently been emphasized, but validated biomarkers for predicting histology are still lacking. The aim of our study was to evaluate different serum and urinary markers of tubular damage in patients with lupus nephritis (LN) and to correlate them with kidney histopathology.

METHODS

A single-center retrospective study was conducted from January 2016 to December 2021. Serum and urine samples were collected on the same day of kidney biopsy and correlated with histologic data from a cohort of 15 LN patients. We analyzed the following urinary markers, adjusted for urine creatinine: beta 2-microglobulin, alpha 1-microglobulin, NGAL, uKIM-1, MCP-1, uDKK-3, and uUMOD. The serum markers sKIM-1 and sUMOD were also analyzed.

RESULTS

A positive and strong correlation was observed between the degree of interstitial fibrosis (rho = 0.785, p = .001) and tubular atrophy (rho = 0.781, p = .001) and the levels of uDKK3. uUMOD also showed an inverse and moderate correlation with interstitial fibrosis (rho = -0.562, p = .037) and tubular atrophy (rho = -0.694, p = .006). Patients with >10% cortical interstitial inflammation had higher levels of uKIM-1 [4.9 (3.9, 5.5) vs. 0.8 (0.6, 1.5) mcg/mg, p = .001], MCP-1 [3.8 (2. 3, 4.2) vs. 0.7 (0.3, 1.2) mcg/mg, p = .001], sKIM-1 [9.2 (5.9, 32.7) vs. 1.4 (0, 3.5) pg/mL, p = .001], and lower sUMOD [8.7 (0, 39.7) vs. 46.1 (35.7, 53) ng/mL, p = .028].

CONCLUSION

The use of specific urinary and serum biomarkers of tubular dysfunction or injury may help to predict certain histologic parameters in LN patients.

Ubiquitin-Specific Protease 18 in Chronic Kidney Disease-Another Emerging Biomarker to Consider?

Ubiquitin-specific protease 18 (USP18) is a protein recognized for its dual enzymatic and non-enzymatic nature. It is involved in many physiological processes like the cell cycle and cell signaling. It also suppresses heart muscle remodeling upon an increase in the afterload. The role of USP18 in kidney pathology remains unknown. The objective of the study was to assess the relationship between serum and urine USP18 levels, the factors contributing to cardiovascular risk, and the markers of kidney disease activity at different stages of chronic kidney disease (CKD). One hundred participants, aged between 24 and 85 years (mean 53.1 ± 17.1 years), were included. Five groups (n = 20 each) were recruited according to their renal status (healthy individuals, patients with proteinuric glomerulonephritis, patients with non-proteinuric CKD, patients who were treated with hemodialysis, and kidney transplant recipients). The measurements of serum and urine USP18 levels were performed using ELISA. The median serum USP18 level was the highest in healthy participants (1143.0 pg/mL) and kidney transplant recipients (856.6 pg/mL), whereas, in individuals with different forms of CKD, it fitted within the range of 402.1-471.9 pg/mL. Urinary USP18 reached the highest level in the group of CKD patients not yet on dialysis (303.3 pg/mL). Only in this group did it correlate with serum creatinine and urea concentrations. Our results suggest the inhibition of cardioprotective USP18 signaling when kidney function is impaired. Moreover, an increased level of urinary USP18 may indicate chronic tubular damage.

Association of Urinary Dickkopf-3 Levels with Cardiovascular Events and Kidney Disease Progression in Systolic Blood Pressure Intervention Trial

Key Points

In unadjusted analyses, elevated urinary Dickkopf-3 levels were strongly associated with higher risks of cardiovascular disease, ESKD, AKI, and mortality. However, associations were substantially weakened after adjustment for eGFR and albuminuria, suggesting limited prognostic value.

Background

Urinary Dickkopf-3 (uDKK3) is a tubular epithelial-derived profibrotic protein secreted into the urine under tubular stress. It is associated with kidney disease progression in persons with CKD and diabetes and postoperative and contrast-associated AKI. We explored associations of uDKK3 with cardiovascular disease (CVD), kidney, and mortality outcomes within the subset of Systolic Blood Pressure Intervention Trial participants with nondiabetic CKD.

Methods

We included 2344 participants with eGFR <60 ml/min per 1.73 m2 at baseline. We used Cox proportional hazards models to evaluate associations of uDKK3 with CVD (acute decompensated heart failure, myocardial infarction, acute coronary syndrome, stroke, or CVD death), kidney outcomes (incident ESKD, incident AKI, and eGFR decline ≥30%), and all-cause mortality. We used linear mixed models to examine the association of uDKK3 with annual percentage change in eGFR. Models were adjusted for demographic and clinical characteristics, eGFR, and albuminuria.

Results

Over a median follow-up of 3.5 years, there were 292 CVD, 73 ESKD, 183 AKI, 471 eGFR decline, and 228 mortality events. In multivariable models without adjustment for eGFR and albuminuria, uDKK3 was strongly associated with CVD, ESKD, AKI, eGFR decline ≥30%, and mortality. However, after further adjustment for eGFR and albuminuria, uDKK3 was no longer associated with risks for composite CVD (hazard ratio, 1.07; 95% confidence interval, 0.92 to 1.23), ESKD (0.80; 0.62 to 1.02), AKI (1.01; 0.85 to 1.21), eGFR decline ≥30% (0.88; 0.79 to 0.99), or mortality (1.02; 0.87 to 1.20). For the linear eGFR change outcome, higher uDKK3 also had no association in the fully adjusted model (−0.03; −0.41 to 0.36).

Conclusions

Among individuals with hypertension and nondiabetic CKD, higher uDKK3 appeared to have associations with a greater risk of CVD events, incident ESKD, incident AKI, eGFR decline ≥30%, and mortality but these associations were not independent of eGFR and albuminuria.

Evaluation of N-acetyl-β-D-glucosaminidase as a prognostic marker for diabetic nephropathy in type 2 diabetics: systematic review and meta-analysis

OBJECTIVE

This review aimed to assess the utility of urinary N-acetyl-β-D-glucosaminidase (uNAG) as a prognostic biomarker for nephropathy in patients with type 2 diabetes mellitus.

METHODS

The search for relevant studies was conducted across multiple databases, including PubMed (Medline), EMBASE, LILACS, CENTRAL, IBECS, and gray literature. We employed a random effects model to calculate the standardized mean difference and 95% confidence interval. Furthermore, we assessed heterogeneity using Cochrane's Q test and Higgins' I2 statistics.

RESULTS

This review included a total of 16 articles involving 1669 patients, with 13 being case-control studies and three being cohorts. The meta-analysis conducted across all studies revealed significant heterogeneity. However, subgroup analysis of four studies indicated that an increase in uNAG among normoalbuminuric patients was associated with the development of macroalbuminuria (DMP = - 1.47; 95% CI = - 1.98 to 0.95; p < 0.00001; I2 = 45%). Conversely, it did not demonstrate effectiveness in predicting the development of microalbuminuria (DMP = 0.26; 95% CI = - 0.08 to 0.60; p = 0.13; I2 = 17%).

CONCLUSIONS

Elevated uNAG levels in normoalbuminuric patients may indicate an increased risk for the development of macroalbuminuria, but not microalbuminuria. However, the high heterogeneity observed among the studies highlights the necessity for further research to validate these findings.

Tubular biomarkers in proteinuric kidney disease: histology correlation and kidney prognosis of tubular biomarkers

Background

Proteinuria is not only a biomarker of chronic kidney disease (CKD) but also a driver of CKD progression. The aim of this study was to evaluate serum and urinary tubular biomarkers in patients with biopsied proteinuric kidney disease and to correlate them with histology and kidney outcomes.

Methods

A single-center retrospective study was conducted on a cohort of 156 patients from January 2016 to December 2021. The following urinary and serum biomarkers were analyzed on the day of kidney biopsy: beta 2 microglobulin (β2-mcg), alpha 1 microglobulin (α1-mcg), neutrophil gelatinase-associated lipocalin (NGAL), urinary kidney injury molecule-1 (uKIM-1), monocyte chemoattractant protein-1 (MCP-1), urinary Dickkopf-3 (uDKK3), uromodulin (urinary uUMOD), serum kidney injury molecule-1 (sKIM-1) and serum uromodulin (sUMOD). A composite outcome of kidney progression or death was recorded during a median follow-up period of 26 months.

Results

Multivariate regression analysis identified sUMOD (β-0.357, P < .001) and uDKK3 (β 0.483, P < .001) as independent predictors of interstitial fibrosis, adjusted for age, estimated glomerular filtration rate (eGFR) and log proteinuria. Elevated levels of MCP-1 [odds ratio 15.61, 95% confidence interval (CI) 3.52-69.20] were associated with a higher risk of cortical interstitial inflammation >10% adjusted for eGFR, log proteinuria and microhematuria. Upper tertiles of uDKK3 were associated with greater eGFR decline during follow-up. Although not a predictor of the composite outcome, doubling of uDKK3 was a predictor of kidney events (hazard ratio 2.26, 95% CI 1.04-4.94) after adjustment for interstitial fibrosis, eGFR and proteinuria.

Conclusions

Tubular markers may have prognostic value in proteinuric kidney disease, correlating with specific histologic parameters and identifying cases at higher risk of CKD progression.

Mediation analysis of chronic kidney disease risk factors using kidney biomarkers in women living with HIV

OBJECTIVE

Novel urinary biomarkers reflecting kidney tubule health are associated with chronic kidney disease (CKD) risk in persons living with HIV. However, it is unknown whether these biomarkers provide mechanistic insight into the associations between clinical risk factors for CKD and subsequent CKD risk.

METHODS

Among 636 women living with HIV in the Women's Interagency HIV Study with estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m 2 , we used a counterfactual approach to causal mediation analysis to evaluate the extent to which systolic blood pressure (SBP), diastolic blood pressure (DBP), hemoglobin a1c (Hba1c) and serum albumin associations with incident CKD were mediated by eight urine proteins. These biomarkers reflect proximal tubular reabsorptive dysfunction (α1-microglobulin [a1m], β2-microglobulin, trefoil factor 3); tubular injury (interleukin 18 [IL-18], kidney injury molecule 1 [KIM-1]); kidney repair (epidermal growth factor); tubular reserve (uromodulin); and glomerular injury (urinary albumin). Incident CKD was defined as eGFR <60 ml/min/1.73 m 2 measured at two consecutive 6-month visits with an average annual eGFR decline ≥3% per year.

RESULTS

During a median follow-up of 7 years, 11% developed CKD. Urinary albumin and KIM-1 mediated 32% (95% CI: 13.4%, 76.6%) and 23% (6.9%, 60.7%) of the association between SBP and incident CKD, respectively; and 19% (5.1%, 42.3%) and 22% (8.1%, 45.7%) of the association between DBP and incident CKD, respectively. Urinary albumin, α1m, and IL-18 were significant mediators of the association between Hba1c and incident CKD. None of the eight biomarkers mediated the association between serum albumin and incident CKD.

CONCLUSIONS

Among women living with HIV, several urinary biomarkers reflecting distinct dimensions of kidney health may partially explain the associations between SBP, DBP, and Hba1c and subsequent CKD risk.

Obesity-related glomerulopathy: recent advances in inflammatory mechanisms and related treatments

Obesity-related glomerulopathy, which is an obesity-triggered kidney damage, has become a significant threat to human health. Several studies have recently highlighted the critical role of inflammation in obesity-related glomerulopathy development. Additionally, excess adipose tissue and adipocytes in patients with obesity produce various inflammatory factors that cause systemic low-grade inflammation with consequent damage to vascular endothelial cells, exacerbating glomerular injury. Therefore, we conducted a comprehensive review of obesity-related glomerulopathy and addressed the critical role of obesity-induced chronic inflammation in obesity-related glomerulopathy pathogenesis and progression, which leads to tubular damage and proteinuria, ultimately impairing renal function. The relationship between obesity and obesity-related glomerulopathy is facilitated by a network of various inflammation-associated cells (including macrophages, lymphocytes, and mast cells) and a series of inflammatory mediators (such as tumor necrosis factor α, interleukin 6, leptin, adiponectin, resistin, chemokines, adhesion molecules, and plasminogen activator inhibitor 1) and their inflammatory pathways. Furthermore, we discuss a recently discovered relationship between micronutrients and obesity-related glomerulopathy inflammation and the important role of micronutrients in the body's anti-inflammatory response. Therefore, assessing these inflammatory molecules and pathways will provide a strong theoretical basis for developing therapeutic strategies based on anti-inflammatory effects to prevent or delay the onset of kidney injury.

Pre-clinical evaluation of biomarkers for the early detection of nephrotoxicity following alpha-particle radioligand therapy

PURPOSE

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as an additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLT nephrotoxicity.

METHODS

A bifunctional cyclic peptide, melanocortin 1 ligand (MC1L), labeled with [203Pb]Pb-MC1L, was used for [212Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [212Pb]Pb-MC1L in a dose-escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers.

RESULTS

Biodistribution analysis identified [212Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [212Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [212Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings.

CONCLUSION

Urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

The association between C-reactive protein levels and the risk of kidney stones: a population-based study

OBJECTIVES

The relationship between C-reactive protein (CRP) and the risk of developing kidney stones is unclear, and we aimed to assess the association between CRP and kidney stones in US adults.

METHODS

We used data from NHANES 2007-2010, and we excluded participants who were under 18 years of age and lacked data on CRP and kidney stones. Finally, we included a total of 11,033 participants and performed weighted multivariate regression analysis and subgroup analysis to assess the independent relationship between CRP and kidney stones.

RESULTS

The mean prevalence of kidney stones among the participants was 9.8%. Notably, as CRP levels increased, the prevalence of kidney stones exhibited a corresponding rise across quartiles (Kidney stones: Quartile 1: 7.59%; Quartile 2: 8.77%; Quartile 3: 9.64%; Quartile 4: 10.89%). CRP was positively associated with the risk of kidney stones (Model 1: OR = 1.09, 95% CI: 1.01-1.18, p = 0.03; Model 2: OR = 1.09, 95% CI: 1.00-1.18, p = 0.03, Model 3: OR = 1.14, 95%CI: 1.02-1.26, p = 0.04). Participants in the highest CRP quartile experienced a 69% increased risk of kidney stones compared to those in the lowest quartile (OR = 1.64, 95% CI: 1.04-2.59, p = 0.03). Notably, interaction tests revealed that gender, BMI, diabetes, hypertension, CKD and smoking or alcohol consumption status did not significantly influence the association between CRP and kidney stones.

CONCLUSIONS

Our findings reveal a significant association between higher CRP levels and an increased risk of kidney stones. In clinical practice, heightened awareness of CRP as a potential biomarker could aid in risk assessment and management strategies for kidney stone patients.

Integrated analysis reveals crosstalk between pyroptosis and immune regulation in renal fibrosis

PURPOSE

The pathogenesis of renal fibrosis (RF) involves intricate interactions between profibrotic processes and immune responses. This study aimed to explore the potential involvement of the pyroptosis signaling pathway in immune microenvironment regulation within the context of RF. Through comprehensive bioinformatics analysis and experimental validation, we investigated the influence of pyroptosis on the immune landscape in RF.

METHODS

We obtained RNA-seq datasets from Gene Expression Omnibus (GEO) databases and identified Pyroptosis-Associated Regulators (PARs) through literature reviews. Systematic evaluation of alterations in 27 PARs was performed in RF and normal kidney samples, followed by relevant functional analyses. Unsupervised cluster analysis revealed distinct pyroptosis modification patterns. Using single-sample gene set enrichment analysis (ssGSEA), we examined the correlation between pyroptosis and immune infiltration. Hub regulators were identified via weighted gene coexpression network analysis (WGCNA) and further validated in a single-cell RNA-seq dataset. We also established a unilateral ureteral obstruction-induced RF mouse model to verify the expression of key regulators at the mRNA and protein levels.

RESULTS

Our comprehensive analysis revealed altered expression of 19 PARs in RF samples compared to normal samples. Five hub regulators, namely PYCARD, CASP1, AIM2, NOD2, and CASP9, exhibited potential as biomarkers for RF. Based on these regulators, a classifier capable of distinguishing normal samples from RF samples was developed. Furthermore, we identified correlations between immune features and PARs expression, with PYCARD positively associated with regulatory T cells abundance in fibrotic tissues. Unsupervised clustering of RF samples yielded two distinct subtypes (Subtype A and Subtype B), with Subtype B characterized by active immune responses against RF. Subsequent WGCNA analysis identified PYCARD, CASP1, and NOD2 as hub PARs in the pyroptosis modification patterns. Single-cell level validation confirmed PYCARD expression in myofibroblasts, implicating its significance in the stress response of myofibroblasts to injury. In vivo experimental validation further demonstrated elevated PYCARD expression in RF, accompanied by infiltration of Foxp3+ regulatory T cells.

CONCLUSIONS

Our findings suggest that pyroptosis plays a pivotal role in orchestrating the immune microenvironment of RF. This study provides valuable insights into the pathogenesis of RF and highlights potential targets for future therapeutic interventions.

Role of MCP-1 as an inflammatory biomarker in nephropathy

The Monocyte chemoattractant protein-1 (MCP-1), also referred to as chemokine ligand 2 (CCL2), belongs to the extensive chemokine family and serves as a crucial mediator of innate immunity and tissue inflammation. It has a notable impact on inflammatory conditions affecting the kidneys. Upon binding to its receptor, MCP-1 can induce lymphocytes and NK cells' homing, migration, activation, differentiation, and development while promoting monocytes' and macrophages' infiltration, thereby facilitating kidney disease-related inflammation. As a biomarker for kidney disease, MCP-1 has made notable advancements in primary kidney diseases such as crescentic glomerulonephritis, chronic glomerulonephritis, primary glomerulopathy, idiopathic proteinuria glomerulopathy, acute kidney injury; secondary kidney diseases like diabetic nephropathy and lupus nephritis; hereditary kidney diseases including autosomal dominant polycystic kidney disease and sickle cell kidney disease. MCP-1 not only predicts the occurrence, progression, prognosis of the disease but is also closely associated with the severity and stage of nephropathy. When renal tissue is stimulated or experiences significant damage, the expression of MCP-1 increases, demonstrating a direct correlation with the severity of renal injury.

Potential Biomarkers for the Earlier Diagnosis of Kidney and Liver Damage in Acute Intermittent Porphyria

Acute intermittent porphyria (AIP) is an inherited metabolic disorder associated with complications including kidney failure and hepatocellular carcinoma, probably caused by elevations in the porphyrin precursors porphobilinogen (PBG) and delta-aminolevulinic acid (ALA). This study explored differences in modern biomarkers for renal and hepatic damage between AIP patients and controls. Urine PBG testing, kidney injury panels, and liver injury panels, including both routine and modern biomarkers, were performed on plasma and urine samples from AIP cases and matched controls (50 and 48 matched pairs, respectively). Regarding the participants' plasma, the AIP cases had elevated kidney injury marker-1 (KIM-1, p = 0.0002), fatty acid-binding protein-1 (FABP-1, p = 0.04), and α-glutathione S-transferase (α-GST, p = 0.001) compared to the matched controls. The AIP cases with high PBG had increased FABP-1 levels in their plasma and urine compared to those with low PBG. In the AIP cases, KIM-1 correlated positively with PBG, CXCL10, CCL2, and TCC, and the liver marker α-GST correlated positively with IL-13, CCL2, and CCL4 (all p < 0.05). In conclusion, KIM-1, FABP-1, and α-GST could represent potential early indicators of renal and hepatic damage in AIP, demonstrating associations with porphyrin precursors and inflammatory markers.

Trends and perspectives for improving quality of chronic kidney disease care: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Chronic kidney disease (CKD) affects over 850 million people globally, and the need to prevent its development and progression is urgent. During the past decade, new perspectives have arisen related to the quality and precision of care for CKD, owing to the development of new tools and interventions for CKD diagnosis and management. New biomarkers, imaging methods, artificial intelligence techniques, and approaches to organizing and delivering healthcare may help clinicians recognize CKD, determine its etiology, assess the dominant mechanisms at given time points, and identify patients at high risk for progression or related events. As opportunities to apply the concepts of precision medicine for CKD identification and management continue to be developed, an ongoing discussion of the potential implications for care delivery is required. The 2022 KDIGO Controversies Conference on Improving CKD Quality of Care: Trends and Perspectives examined and discussed best practices for improving the precision of CKD diagnosis and prognosis, managing the complications of CKD, enhancing the safety of care, and maximizing patient quality of life. Existing tools and interventions currently available for the diagnosis and treatment of CKD were identified, with discussion of current barriers to their implementation and strategies for improving the quality of care delivered for CKD. Key knowledge gaps and areas for research were also identified.