Abstract Background Biobanks that hold blood, urine and kidney tissue are key for translational nephrology research but are few and have limited availability. We describe the organization, baseline characteristics, and generalizability of a low-cost national biobank. Materials and methods Eight Norwegian hospitals participated in this multi-center, prospective cohort study and biobank initiative. Patients referred for routine clinical native kidney biopsies were eligible for inclusion, starting September 2020. Extensive information on medical history and risk factors were collected into an encrypted on-line database by the treating nephrologist. A comprehensive standardized panel of blood and urine tests were analyzed in the clinical routine and registered along with the full histology report. Extra urine and blood samples were collected, aliquoted and prepared locally within two hours, frozen at -80 C, and later sent to a central government-funded biorepository together with remaining kidney biopsy material. Results By September 2023, a total of 633 patients were included out of 1050 eligible patients. Mean age was 52.6 years (SD 18.7), 384 (61%) were men, and participants displayed a wide spectrum of kidney disease with mean estimated glomerular filtration rate (eGFR) 53 mL/min/1.73m 2 . The most frequent biopsy indications were progressive chronic kidney disease (CKD) of unknown cause, acute kidney disease, and isolated hematuria/proteinuria. The most frequent diagnoses were IgA nephropathy (21%), arterionephrosclerosis (13%), and diabetes nephropathy (9%). Biopsy indications and diagnoses were similar to the spectrum typically seen in Norway and other western countries, and similar population level kidney health measures were demonstrated for Norway, United Kingdom, and USA. Discussion We demonstrate the feasibility of establishing a large national kidney biopsy biobank across a variety of clinical and histopathologic diagnoses. Blood and urine were stored, accompanied by kidney tissue, at a moderate cost due to a combination of a dedicated nephrology workforce, routine clinical care, and established biobank facilities.
Hypertensive nephrosclerosis is considered the second most common cause of end-stage renal disease (ESRD), but it is still an insufficiently studied and controversial disease entity. More information on the phenotype and prognosis is needed to improve clinical diagnostics and treatment.We included all Norwegian patients with chronic kidney disease (CKD) referred for kidney biopsy between 1988 and 2012 whose clinical presentation was consistent with, but not primarily suspicious for, hypertensive nephrosclerosis (n = 4920); follow-up continued until 2013.A total of 918 patients (19%) had biopsy-verified hypertensive nephrosclerosis (i.e., arterionephrosclerosis). Their most common biopsy indications were proteinuria (57%), low estimated glomerular filtration rate (eGFR) (44%), hematuria (34%), or combinations of these indications. Multivariable logistic regression analysis revealed that arterionephrosclerosis was significantly associated with higher age, male sex, not having diabetes, higher blood pressure, lower proteinuria, and not having hematuria (P < 0.01 for all). Body mass index, cholesterol, high-density lipoprotein cholesterol, and eGFR were not significantly associated with arterionephrosclerosis (P > 0.05 for all). The most common biopsy-verified diagnoses in patients fulfilling the clinical criteria for hypertensive nephrosclerosis were arterionephrosclerosis (40%), glomerulonephritis (22%), and interstitial nephritis (14%), reflecting that the criteria had low sensitivity (0.17) and high specificity (0.94). ESRD and mortality risks did not differ in patients with arterionephrosclerosis compared to patients with glomerulonephritis, interstitial nephritis, or other relevant diagnoses (P > 0.1 for both), whereas patients with diabetic kidney disease had a 2-fold higher risk (P < 0.001 for both).Arterionephrosclerosis is a high-risk disease, often with an atypical phenotype with proteinuria and hematuria contributing to low accuracy for current clinical criteria for hypertensive nephrosclerosis.
Objective: Hypertensive nephropathy (HN) represents a major cause of chronic kidney disease, but it is incompletely understood why some patients show disease progression. Our project aim is to identify potential markers of disease progression and novel therapeutic targets. Design and method: Adult patients (n=43; n=16 females, mean age 53 years) with biopsy-verified HN were categorized as ’early’ (estimated glomerular filtration rate (eGFR) >45 ml/min/1.73m2) or ’late’ disease (eGFR <45 ml/min/1.73m2) at the time of biopsy. Patients were further divided into “stable” (eGFR decline <3 ml/min/year) or “progressive” (eGFR decline >3 ml/min/year or start of renal replacement therapy) after median follow-up of 10 years (5-22). TruSeq Exome sequencing was executed after RNA extraction (miRNeasy FFPE kit, Qiagen) at Novogene, Cambridge, UK. Quality control and data analysis was performed using R Studio (v4.2.0) and QIAGEN Ingenuity Pathway Analysis. Results: We analyzed the following subgroups of HN patients: early stable (ES, n=11), early progressive (EP, n=11), late stable (LS, n=9) and late progressive (LP, n=12). Differentially expressed genes (DEG, fold change (FC) >1.5 and p-value < 0.05) were identified, with n=265 in ES vs. EP, and n=674 in LS vs. LP. Principal component analysis (PCA) showed separation of ES vs. EP and LS vs. LP, as depicted in Figure 1A and B. K-nearest neighbour (KNN) analysis of DEG identified a 6-gene classifier in LS vs. LP (19/21 samples correctly classified), while IER5L and CNTNAP5 were the top 2-gene classifier in ES vs. EP (20/21 samples). These classifiers, as well as other DEGs such as PER1, YB1, TIMP3, ADAMTS4, IGFBP5 and EGF could represent novel targets to inhibit disease progression. Differentially regulated pathways were associated with regulation of TP53 activity and circadian rhythm involving melatonin metabolism in ES vs. EP, and metabolic processes related to water-soluble vitamins, glutathione and sphingolipids in LS vs. LP. Conclusions: Transcriptomic profiling from diagnostic kidney biopsies with HN can distinguish future disease progression from non-progression and may identify novel therapeutic targets.
Background: Chronic kidney disease (CKD) is a growing global public health issue. Physical exercise mitigates several kidney-related pathophysiological pathways, yet its impact on kidney function remains underexplored. We investigated the dose-response effect of physical exercise on kidney function preservation in older adults. Methods: Post-hoc analysis of the Generation 100 Study, a 5-year open-label, randomized, parallel-arm clinical trial conducted from 2012 to 2018 in Trondheim, Norway. All inhabitants aged 70-77 years were invited (n=6,966). Main exclusion criteria were dementia; severe, uncontrolled cardiovascular disease or hypertension; or conditions precluding exercise. The control group (n=385) received information on national physical activity recommendations. Intervention groups underwent supervised moderate-intensity continuous training (70% of peak heart rate) for 50 minutes (n=380) twice weekly for five years or high-intensity interval training (90% of peak heart rate) for 4 minutes x4 (n=391) twice weekly for five years. The primary outcome was cystatin C-based rapid eGFR decline (>5mL/min/1.73m 2 per year). Results: A total of 1,156 participants were randomized with median (interquartile range) age 72 (3) years and eGFR 95 (20) mL/min/1.73 m 2 . Oxygen uptake increased by 1.8, 2.3, and 3.3 mL/kg/min in the control, moderate-intensity, and high-intensity groups. Rapid eGFR decline occurred in 117 (30%), 108 (28%), and 92 (23%) participants, respectively. Compared to controls, relative risk (RR) was 0.93 (0.75-1.16) for moderate-intensity and 0.75 (95% CI 0.59-0.95) for high-intensity, demonstrating a significant dose-response relationship (P for trend 0.02). In observational analyses, participants with decreasing moderate-vigorous activity (> -20 minute/week) had RR 1.30 (95% CI 0.93-1.83) for rapid eGFR decline, while those with increasing activity (> +20 minutes/week) had RR 0.73 (0.53-0.99) compared to stable activity after adjusting for baseline age, sex, VO 2peak and eGFR. Conclusions: High-intensity interval training significantly reduced the risk of rapid eGFR decline in older adults.
Abstract Background and Aims Hypertensive nephropathy (HN) is a significant contributor to chronic kidney disease, yet the factors influencing the disease progression remains elusive. Notably, late-stage chronic kidney disease significantly impacts patient outcome. This project aims to unveil novel therapeutic targets for late-stage of HN using transcriptomic approach. Method A cohort of adult patients (n = 21; n = 9 females, mean age 57 years) with biopsy-confirmed HN were selected from the Norwegian Kidney Biopsy Registry (NKBR). Patients were classified as late-stage if eGFR≤45 ml/min/1.73 m2 at the time of biopsy. Patients were thereafter divided into “stable” (eGFR decline <3 ml/min/year) or “progressive” (eGFR decline ≥3 ml/min/year or start of renal replacement therapy) after a median follow-up of 9 years (5-15). TruSeq Exome sequencing was performed post-RNA extraction (miRNeasy FFPE kit, Qiagen) at Novogene, Cambridge, UK. R Studio (v4.2.0) and drug CTD repository in ShinyGO 0.80 facilitated data and drug interaction analysis. Results We focused on two distinct subgroups of HN patients: late stable (LS, n = 9) and late progressive (LP, n = 12). A total of n = 674 of differentially expressed genes (DEG, p-value < 0.05 and fold change (FC) ≥1.5) was identified in LS vs. LP. The subsequent drug interactive analysis of these DEGs unveiled 336 pathways with false discovery rate (FDR) < 0.05. Notably, the probenecid-related pathway demonstrated significant fold enrichment (FE=9, FDR = 1.5E-04), as depicted in Fig. 1. Particularly, key members of the SLC22 family, including SLC22A6 (FC=2.49, p-value = 0.002), SLC22A8 (FC=2.65, p-value = 0.004), SLC22A11 (FC=1.65, p-value = 0.036) and SLC22A12 (FC=1.97, p-value = 0.009) were prominently featured in this pathway. Besides their role as sole transporters, it is postulated that these proteins have central role in modulating local and systemic physiology, such as blood pressure, suggesting a potential significance of probenecid in the context of hypertensive nephropathy. Conclusion Transcriptomic profiling of kidney biopsies has strong potential to discover novel therapeutic targets, such as the probenecid-related pathway, in hypertensive nephropathy patients.
Hypertensive nephrosclerosis is among the leading causes of end-stage renal disease, but its pathophysiology is poorly understood. We wanted to explore early metabolic changes using gene expression and targeted metabolomics analysis.We analyzed gene expression in kidneys biopsied from 20 patients with nephrosclerosis and 31 healthy controls with an Affymetrix array. Thirty-one amino acids were measured by liquid chromatography coupled with mass spectrometry (LC-MS) in urine samples from 62 patients with clinical hypertensive nephrosclerosis and 33 age- and sex-matched healthy controls, and major findings were confirmed in an independent cohort of 45 cases and 15 controls.Amino acid catabolism and synthesis were strongly underexpressed in hypertensive nephrosclerosis (13- and 7-fold, respectively), and these patients also showed gene expression patterns indicating decreased fatty acid oxidation (12-fold) and increased interferon gamma (10-fold) and cellular defense response (8-fold). Metabolomics analysis revealed significant distribution differences in 11 amino acids in hypertensive nephrosclerosis, among them tyrosine, phenylalanine, dopamine, homocysteine, and serine, with 30% to 70% lower urine excretion. These findings were replicated in the independent cohort. Integrated gene-metabolite pathway analysis showed perturbations of renal dopamine biosynthesis. There were also significant differences in homocysteine/methionine homeostasis and the serine pathway, which have strong influence on 1-carbon metabolism. Several of these disturbances could be interconnected through reduced regeneration of tetrahydrofolate and tetrahydrobiopterin.Early hypertensive nephrosclerosis showed perturbations of intrarenal biosynthesis of dopamine, which regulates natriuresis and blood pressure. There were also disturbances in serine/glycine and methionine/homocysteine metabolism, which may contribute to endothelial dysfunction, atherosclerosis, and renal fibrosis.
