Rule, Andrew D.

Background: Chronic kidney disease (CKD) has been linked to elevated inflammatory biomarkers, yet few studies have evaluated these associations using iothalamate-based measures of kidney function, highlighting the need for further research. Research question: Is CKD associated with elevated inflammatory markers when defined by measured glomerular filtration rate (mGFR) and urinary albumin-to-creatinine ratio (UACR)? Methods: Participants from the Genetic Epidemiology Network of Arteriopathy (GENOA) cohort were included if they had data available for at least one inflammatory marker at visit 2. 17 inflammatory markers were assessed, including C-reactive protein (CRP), interleukin-6 (IL-6), IL-18, tumor necrosis factor receptors 1 and 2 (TNFR1, TNFR2), serum amyloid A, intercellular and vascular adhesion molecules (ICAM, VCAM), E-selectin, P-selectin, monocyte chemoattractant protein (MCP), myeloperoxidase (MPO), receptor for advanced glycation end products (RAGE), matrix metalloproteinases 2 and 9 (MMP-2, MMP-9), and tissue inhibitors of metalloproteinases 1 and 2 (TIMP-1, TIMP-2). Kindey function was assessed using the urinary clearance of iothalamate. CKD was defined as mGFR < 60 mL/min/1.73 m 2 or UACR ≥ 30 mg/g. To further assess whether associations persisted without albuminuria, we also defined CKD solely by mGFR < 60 mL/min/1.73 m 2 . Generalized estimating equations (GEE) were used to assess associations between CKD status and inflammatory markers, accounting for familial clustering. Exponentiated beta coefficients from GEE models were used to present geometric mean (GM) ratios of each biomarker by CKD status, adjusted for demographics, lifestyle factors, cardiovascular risk factors, and medication use. Results: Among 1,010 participants (mean age 61 ± 10 years; 67% women; 48% Black adults), 207 were classified as having CKD. After adjusting for potential confounders, individuals with CKD had significantly higher levels of hsCRP, VCAM, TNFR1, and TNFR2 compared to those without CKD (GM ratios > 1; p < 0.05), while the remaining inflammatory markers showed no significant differences ( Figure 1 ). Importantly, these elevations remained significant when CKD was defined by mGFR alone ( Figure 2 ). Conclusion: Our findings suggest that CKD, defined by mGFR, is associated with specific inflammatory biomarkers, underscoring the need for mechanistic studies to investigate these associations.

Key Points Increased protein expression of tissue inhibitor of metalloproteinase-3, glypican 6, synuclein γ , apolipoprotein A-4, and Ecto-5′-nucleotidase was observed in old adults compared with young adults. In old adults, overexpressed proteins were enriched in mitochondrial processes while under expressed proteins enriched in RNA metabolism. Validated differentially expressed proteins were not significantly correlated with kidney pathology after adjusting for age. Background Kidney aging is characterized by a loss of glomeruli, predominantly in the superficial cortex, with a resultant decline in GFR and an increased risk of various kidney-related diseases. The early molecular alterations in glomeruli associated with the aging process are not well studied. Methods We combined laser capture microdissection and mass spectrometry–based unbiased proteomic analysis of nonsclerosed, nonischemic glomeruli in the superficial cortex from young and old adults who underwent a radical nephrectomy for a tumor to understand the age-related molecular changes in glomeruli. Twenty-four young and 30 old adults were used for the discovery dataset, and the significant differentially expressed proteins were further validated using an independent set comprising six young and eight old adults. Results Kidneys from old adults had lower eGFR, less kidney parenchyma on computed tomography imaging, and more glomerulosclerosis and arteriosclerosis on histology. Quantitative proteomic analysis of nonsclerosed, nonischemic glomeruli identified increased expression of tissue inhibitor of metalloproteinase-3, glypican 6, synuclein γ , apolipoprotein A-4, and Ecto-5′-nucleotidase in old adults that were further validated in an independent set. Pathway analysis indicated that proteins with increased expression in old adults were enriched in mitochondrial translational processes, aerobic respiration, and TCA cycle, whereas proteins with decreased expression in old adults were enriched in mRNA splicing, mRNA processing, and nonsense mediated decay. Furthermore, validated differentially expressed proteins did not show any significant correlation with the kidney pathology independent of age group. Conclusions Overall, this study identified proteins that are specifically associated with the aging process in otherwise normal-appearing glomeruli.

Key Points Among US preemptively waitlisted patients with CKD, deceased donor transplants increased for Black and Hispanic patients, comparable with White patients. Dialysis initiation was higher for waitlisted Asian, Black, and Hispanic patients compared with White patients, mirroring lower living donor transplants. Organ Procurement and Transplantation Network wait time credit and Increasing Organ Transplant Access metric could expand preemptive transplantation. Background Preemptive kidney transplantation (before dialysis initiation) is the optimal therapy for most transplant-eligible advanced patients with CKD. Although prior research has documented racial and ethnic disparities in preemptive referrals, less is known about distinct outcomes after preemptive waitlisting. This study examines the association between race and ethnicity and outcomes for preemptively waitlisted patients. Methods We conducted a secondary analysis of a prospectively maintained US cohort using data from the Scientific Registry of Transplant Recipients. The study population included 98,863 adult first-time kidney transplant candidates who were preemptively waitlisted from January 1, 2009, to December 31, 2020, and followed through December 31, 2024. The exposure of interest was race and ethnicity. The primary outcome was 3-year preemptive deceased donor kidney transplantation, living donor kidney transplantation, or dialysis initiation. We used competing risk models to estimate adjusted subdistribution hazard ratios (aSHRs). Data were stratified into 3-year intervals (2009–2011, 2012–2014, 2015–2017, and 2018–2020). Results Black and Hispanic patients received preemptive deceased donor kidney transplants as often as White patients (era 2018–2020, aSHRs [95% confidence interval (CI)]: 0.99 [95% CI, 0.92 to 1.07] and 1.02 [95% CI, 0.93 to 1.12], respectively), while Asian patients had lower rates (0.78 [95% CI, 0.69 to 0.88]). However, Asian, Black, and Hispanic patients were more likely to initiate dialysis (aSHRs: 1.50 [95% CI, 1.39 to 1.61]; 1.41 [95% CI, 1.34 to 1.49]; and 1.21 [95% CI, 1.14 to 1.29], respectively) and were less likely to receive preemptive living donor kidney transplants than White patients (era 2018–2020, aSHRs: 0.49 [95% CI, 0.44 to 0.54]; 0.31 [95% CI, 0.29 to 0.34]; and 0.61 [95% CI, 0.56 to 0.66], respectively). Conclusions Among waitlisted patients with CKD in the United States between 2009 and 2020, rates of preemptive deceased donor kidney transplantation improved for Black and Hispanic patients and became comparable with White patients. However, Asian, Black, and Hispanic patients experienced higher rates of dialysis initiation and lower rates of preemptive living donor kidney transplantation.

BACKGROUND: The performance of estimated glomerular filtration rate (eGFR) among patients with heart failure (HF) may be worse than in the general population due to a higher prevalence of confounding factors affecting creatinine and cystatin C. Studies in this area are scarce and not stratified by type of HF. We evaluated the performance of current creatinine and cystatin C equations (eGFRcr, eGFRcys, and eGFRcrcys) compared with measured GFR (mGFR) among patients with HF stratified by ejection fraction. METHODS: We pulled data on Mayo Clinic patients with an mGFR performed for clinical indications from 2011 to 2023, with serum creatinine and cystatin C measured within 7 days and an echocardiogram performed up to 1 year before the mGFR date. HF was identified by the presence of International Classification of Diseases codes within 1 year before the mGFR and subgrouped into ejection fraction (EF) ≥50% (HFEF≥50%, n=182) or <50% (HFEF<50%, n=115) and compared with no-HF controls (n=1871). CKD-EPI (and EKFC) eGFRcr, eGFRcys, and eGFRcrcys equations were calculated and compared for bias (mGFR minus eGFR) and accuracy (1-P30, proportion of people with ≥30% difference between eGFR and mGFR). CIs were generated by bootstrapping. RESULTS: The HF groups were characterized by older age, higher proportion of males, more diabetes, higher creatinine, and higher cystatin C than controls. In terms of bias, eGFRcr overestimated mGFR to a greater extent in both HF groups compared with controls, whereas eGFRcys and eGFRcrcys showed similar bias in both HF groups and controls. In the HF groups, cystatin C-based equations were more accurate than eGFRcr, particularly within HFEF<50% (1-P30 of 28% and 34% for CKD-EPI eGFRcys and eGFRcrcys, respectively, versus 60% for eGFRcr), whereas eGFRcrcys was more accurate in controls. The CKD-EPI and EKFC equations were overall convergent, showing similar results. CONCLUSIONS: Among patients with HF, eGFRcr demonstrates inferior performance (more bias and less accuracy) compared with cystatin C-based eGFRs, with this effect being more pronounced in those with HFEF<50%.

Key Points Automated cyst segmentation in autosomal dominant polycystic kidney disease could transform care by enabling precise monitoring of cyst progression with minimal manual effort. This technology can facilitate more consistent assessments of cyst burden across patients. Translating these segmentation models from magnetic resonance imaging to computed tomography is crucial for providing comprehensive, modality-independent evaluations. Background Total kidney and liver volumes are key image-based biomarkers to predict the severity of kidney and liver phenotype in autosomal dominant polycystic kidney disease (ADPKD). However, magnetic resonance (MR) imaging-based advanced biomarkers like total cyst number and cyst parenchyma surface area have been shown to more accurately assess cyst burden and improve the prediction of disease progression. The main aim of this study was to extend the calculation of advanced biomarkers to other imaging modalities; thus, we propose a fully automated model to segment kidney and liver cysts in computed tomography (CT) images. Methods Abdominal CTs of patients with ADPKD were gathered retrospectively between 2001 and 2018. A three-dimensional deep learning method using the nnU-Net architecture was trained to learn cyst edges-cores and the noncystic kidney/liver parenchyma. Separate segmentation models were trained for kidney cysts in contrast-enhanced CTs and liver cysts in noncontrast CTs using an active learning approach. Two experienced research fellows manually generated the reference standard segmentation, which were reviewed by an expert radiologist for accuracy. Results Two-hundred CT scans from 148 patients (mean age, 51.2±14.1 years; 48% male) were used for model training (80%) and testing (20%). In the test set, both models showed good agreement with the reference standard segmentations, similar to the agreement between two independent human readers (model versus reader: TCN kidney/liver r =0.96/0.97 and CPSA kidney r =0.98, inter-reader: TCN kidney/liver r =0.96/0.98 and CPSA kidney r =0.99). Conclusions Our study demonstrates that automated models can segment kidney and liver cysts accurately in CT scans of patients with ADPKD.

This study aimed to determine if extended infusion (EI; over > 3 hr) beta-lactam therapy increased IV access requirements compared with traditional dosing (TD; over 30 min). Eighty-six adult ICU patients treated with TD anti-pseudomonal beta-lactams who underwent therapeutic drug monitoring (TDM) were included. Patients who transitioned from TD to EI after TDM (EI group) were matched 1:1 to patients who remained on TD. In the primary analysis, the median (interquartile range) total number of lumens in the 24 hours before TDM compared with the 48 hours after TDM were similar between groups (pre: TD 3 [2–5] vs. EI 4 [3–5]; p = 0.22 and post: TD 3 [2–4] vs. EI 4 [3–5]; p = 0.05). Delivery of beta-lactams via EI was not associated with a need for more IV access. Practical challenges such as access should not limit use of EI beta-lactams when indicated.

Key Points Circulating proteins independently associated with kidney stone diagnosis are related to kidney stone matrix. Lower circulating uromodulin and higher scavenger receptor cysteine-rich domain-containing group B protein levels were associated with higher kidney stone risk, whereas kidney stone presence elevates plasma matrix metalloproteinase 7 level. The protective effect of uromodulin against kidney stones was independent of kidney function. Background Kidney stones are increasingly recognized as a systemic disorder with a high global prevalence. However, large proteomics studies are lacking. Methods An individual-level proteomics study with rigorous adjustments was performed on 35,331 UK Biobank participants to uncover the independent associations between 2922 circulating proteins and prevalent kidney stone disease. Mendelian randomization analysis was used to assess causal relationships. Findings were validated using genomic data from the Mayo Clinic Biobank ( N =43,744), concentration-response analysis, transcriptomics analyses, and additional genome-wide association studies. Results Nine plasma proteins were independently associated with a kidney stone diagnosis, including reduced uromodulin (UMOD; β , −0.10; 95% confidence interval [CI], −0.15 to −0.05) and elevated scavenger receptor cysteine-rich domain-containing group B protein (SSC4D; β , 0.28; 95% CI, 0.17 to 0.38) and were enriched in extracellular matrix pathways. Mendelian randomization analysis revealed that the presence of kidney stone contributed to elevated levels of matrix metalloproteinase 7. Conversely, lower plasma UMOD (odds ratio [OR], 0.93; 95% CI, 0.90 to 0.97) and higher plasma SSC4D (OR, 1.10; 95% CI, 1.02 to 1.18) were associated with kidney stone risk. These associations were consistently replicated in the Mayo Clinic Biobank dataset (UMOD; OR, 0.92; 95% CI, 0.86 to 0.98; SSC4D; OR, 1.13; 95% CI, 1.01 to 1.27) and further validated by a concentration-response analysis. Single-nucleus RNA sequencing and quantitative trait loci analyses confirmed consistent associations between thick ascending limb UMOD expression and stone former status and with blood and urine UMOD concentrations. Genome-wide association study analysis, adjusted for eGFR, suggested that the protective role of UMOD against kidney stones was independent of kidney function. Conclusions This study highlights significant associations between concentrations of specific blood proteins and a history of kidney stones. Several implicated proteins are related to kidney stone matrix, with UMOD independently associated with lower risk and SSC4D with higher risk of kidney stones.