Glomerular proteomic profiling reveals early differences between preexisting and de novo type 2 diabetes in human renal allografts

BACKGROUND

Diabetes mellitus (DM), either preexisting or developing after transplantation, remains a crucial clinical problem in kidney transplantation. To obtain insights into the molecular mechanisms underlying PTDM development and early glomerular damage before the development of histologically visible diabetic kidney disease, we comparatively analysed the proteome of histologically normal glomeruli from patients with PTDM and normoglycaemic (NG) transplant recipients. Moreover, to assess specificities inherent in PTDM, we also comparatively evaluated glomerular proteomes from transplant recipients with preexisting type 2 DM (T2DM).

METHODS

Protocol biopsies were obtained from adult NG, PTDM and T2DM patients one year after kidney transplantation. Biopsies were formalin-fixed and embedded in paraffin, and glomerular cross-sections were microdissected. A total of 4 NG, 7 PTDM and 6 T2DM kidney biopsies were used for the analysis. The proteome was determined by liquid chromatography-tandem mass spectrometry. Relative differences in protein abundance and significantly dysregulated pathways were analysed.

RESULTS

Proteins involved in cell adhesion, immune response, leukocyte transendothelial filtration, and cell localization and organization were less abundant in glomeruli from PTDM patients than in those from NG patients, and proteins associated with supramolecular fibre organization and protein-containing complex binding were more abundant in PTDM patients. Overall, proteins related to adherens and tight junctions and those related to the immune system, including leukocyte transendothelial migration, were more abundant in NG patients than in transplanted patients with DM, irrespective of the timing of its development. However, proteins included in cell‒cell junctions and adhesion, insulin resistance, and vesicle-mediated transport were all less abundant in PTDM patients than in T2DM patients.

CONCLUSIONS

The glomerular proteome profile differentiates PTDM from NG and T2DM, suggesting specific pathogenetic mechanisms. Further studies are warranted to validate these results, potentially leading to an improved understanding of PTDM kidney transplant pathophysiology and to the identification of novel biomarkers.

Renal Functional Response-Association With Birth Weight and Kidney Volume

Introduction

Renal functional response (RFR) is the acute increase in glomerular filtration rate (GFR) after a protein load. Low RFR is a marker of single nephron hyperfiltration. Low birth weight (LBW) is associated with reduced number of nephrons, lower kidney function, and smaller kidneys in adults. In the present study, we investigate the associations among LBW, kidney volume, and RFR.

Methods

We studied adults aged 41 to 52 years born with either LBW (≤2300 g) or normal birth weight (NBW; 3500-4000 g). GFR was measured using plasma clearance of iohexol. A stimulated GFR (sGFR) was measured on a separate day after a protein load of 100 g using a commercially available protein powder, and RFR was calculated as delta GFR. Kidney volume was estimated from magnetic resonance imaging (MRI) images using the ellipsoid formula.

Results

A total of 57 women and 48 men participated. The baseline mean ± SD GFR was 118 ± 17 ml/min for men and 98 ± 19 ml/min for women. The overall mean RFR was 8.2 ± 7.4 ml/min, with mean RFR of 8.3 ± 8.0 ml/min and 8.1 ± 6.9 ml/min in men and women, respectively (P = 0.5). No birth-related variables were associated with RFR. Larger kidney volume was associated with higher RFR, 1.9 ml/min per SD higher kidney volume (P = 0.009). Higher GFR per kidney volume was associated with a lower RFR, -3.3ml/min per SD (P < 0.001).

Conclusion

Larger kidney size and lower GFR per kidney volume were associated with higher RFR. Birth weight was not shown to associate with RFR in mainly healthy middle-aged men and women.

Proteomic signature of tubulointerstitial tissue predicts prognosis in IgAN

BACKGROUND

IgA nephropathy (IgAN) is associated with a significant risk of progression to kidney failure. Tubular atrophy is an established important risk factor for progressive disease, but few studies have investigated tubulointerstitial molecular markers and mechanisms of progression in IgAN.

METHODS

Based on data from the Norwegian Renal Registry, two groups were included: IgAN patients with (n = 9) or without (n = 18) progression to kidney failure during 10 years of follow-up. Tubulointerstitial tissue without discernible interstitial expansion or pronounced tubular alterations was microdissected, proteome was analysed using tandem mass spectrometry and relative protein abundances were compared between groups.

RESULTS

Proteome analyses quantified 2562 proteins with at least 2 unique peptides. Of these, 150 proteins had significantly different abundance between progressive and non-progressive IgAN patients, 67 were more abundant and 83 less abundant. Periostin was the protein with the highest fold change between progressive and non-progressive IgAN (fold change 8.75, p < 0.05) and periostin staining was also stronger in patients with progressive vs non-progressive IgAN. Reactome pathway analyses showed that proteins related to inflammation were more abundant and proteins involved in mitochondrial translation were significantly less abundant in progressive vs non-progressive patients.

CONCLUSIONS

Microdissection of tubulointerstitial tissue with only mild damage allowed for identification of proteome markers of early progressive IgAN. Periostin abundance showed promise as a novel and important risk marker of progression.

Birth Weight Is Associated With Kidney Size in Middle-Aged Women

Introduction

Low birth weight (LBW) is associated with increased risk of kidney disease due to lower nephron endowment leading to hyperfiltration and subsequent nephron loss. Kidney size is commonly used as a proxy for nephron number. We compared kidney volume measured by magnetic resonance imaging (MRI) with measured glomerular filtration rate (mGFR) in adults with either normal birth weight (NBW) or low birth weight (LBW).

Methods

Healthy individuals aged 42 to 52 years with LBW (1100−2300 g) and NBW (3500 −4000 g) were invited to participate. The GFR was measured using plasma clearance of iohexol. Kidney volume was measured on magnetic resonance images using axial T2 images and coronal T1 images with fat saturation without contrast enhancement; calculations were performed according to the ellipsoid formula π/6 × length × width × depth.

Results

We included 102 individuals (54 LBW and 48 NBW). Total kidney volume was 302 ± 51 ml for female NBW vs 258 ± 48 ml for female LBW individuals (P = 0.002). For male individuals, total kidney volume was 347 ± 51 ml vs. 340 ± 65 ml (P = 0.7). The mGFR was significantly associated with kidney volume, with r = 0.52 (P < 0.001) for women and r = 0.39 (P = 0.007) for men. A mediation analysis showed that the association between birth weight and mGFR (significant in total sample and women) was mediated by kidney volume.

Conclusion

Healthy female individuals born with LBW have smaller kidneys than healthy females born with NBW. The previously shown associations between LBW and lower mGFR in adult women might be explained by smaller kidney volume.

Familial Contributions to the Association Between Low Birth Weight and Risk of CKD in Adult Life

Introduction

Previous studies have revealed that individuals with low birth weight (LBW) have higher risk of chronic kidney disease (CKD) and that LBW and CKD cluster in families. This study investigates how familial factors affect the association between birth-related risk markers and risk of CKD.

Methods

The Medical Birth Registry (MBR) of Norway has registered all births in Norway since 1967. Sibling data were available through the Norwegian Population Registry. The Norwegian Patient Registry has registered diagnostic codes for all admissions and outpatient visits to Norwegian hospitals since 2008. Data from these registries were linked. Risk of CKD according to whether the individual himself or at least one of his siblings had LBW was analyzed using logistic regression statistics.

Results

Of 1,847,565 individuals, 3336 had been diagnosed with CKD. Compared with individuals without LBW and no siblings with LBW, individuals without LBW but who had a sibling with LBW had adjusted odds ratio (aOR) of 1.33 (1.19–1.49), those with LBW but no siblings with LBW had aOR of 1.74 (1.55–1.95), and those with LBW and a sibling with LBW had aOR of 1.77 (1.54–2.04) for CKD. Similar results were found for LBW for gestational age, but preterm birth revealed weaker associations.

Conclusion

Individuals who have a sibling with LBW have an increased risk of CKD later in life, and individuals who themselves have LBW have an even higher risk. Our findings suggest that there are familial contributions to the nephron endowment in utero hypothesis.

FC 086GLOMERULI PROTEOME ANALYSIS REVEALS EARLY DIFFERENCES BETWEEN PRE-EXISTING AND DE-NOVO TYPE 2 DIABETES IN HUMAN RENAL ALLOGRAFTS

Background and Aims

Diabetes mellitus, either preexisting or developing after kidney transplantation remains a crucial clinical problem. The aim of this study is to compare the proteome of histologically normal glomeruli from normoglycemic (NG), T2DM, and PTDM patients one year after kidney transplantation to identify novel early biomarkers detectable prior to the development of histologically visible diabetic nephropathy.

Method

We comparatively analyzed the proteome of histologically normal glomeruli from normoglycemic (NG) recipients, and recipients with pre-existing type 2 diabetes mellitus (T2DM), or post-transplant diabetes mellitus (PTDM), in protocol biopsies obtained one year after kidney transplantation. Glomerular cross-sections were microdissected in core biopsies from 8 NG, 8 PTDM and 8 T2DM kidney transplant recipients. Proteome was determined by liquid chromatography-tandem mass spectrometry. Relative differences in protein abundance and significantly dysregulated pathways were analyzed.

Results

Proteins related to immune response and inflammation, transport regulation and cell organization and communication, including the nephrin family, were more abundant in NG, as compared to the combined groups of diabetic patients. Proteins involved in cell morphogenesis and adhesion were less abundant in PTDM, as compared to T2DM. In contrast, CCT3, CCT4 and CNDP2 diabetic nephropathy markers, LDHB and tacrolimus binding protein FKBP1A were significantly overrepresented in glomeruli from PTDM, as compared to T2DM patients.

Conclusion

These data suggest that glomerular proteome profile differentiates PTDM from NG and T2DM, and disruption of cell-cell interactions at molecular level represents an early event in PTDM development.

MO504LOW BIRTH WEIGHT ASSOCIATES WITH SMALLER KIDNEY SIZE IN MIDDLE-AGED WOMEN

Background and Aims

Low birth weight is associated with increased risk of kidney disease due to lower nephron endowment leading to hyperfiltration and subsequent nephron loss. Nephron number is thought to associate with kidney size. We compared kidney size measured by magnetic resonance imaging (MRI) with ultrasonography and measured glomerular filtration rate (mGFR) in adults with normal versus low birth weight.

Method

Healthy individuals aged 42-52 years with Low birth weight (LBW – 1100-2300g) and normal birth weight (NBW - 3500-4000g) were invited. GFR was measured using plasma clearance of iohexol. Kidney volume was measured on MRI images using axial T2 images and coronal T1 images with fat saturation without contrast enhancement, calculations were performed according to the ellipsoid formula - π/6 x Length x Width x Depth. Ultrasonographic imaging was done using a dorsal approach. In the maximal longitudinal view the parenchymal area was calculated subtracting the area of a manual tracing around the renal pelvis from the area of a manual tracing of the whole kidney. Volume and area from the two kidneys were added and total value was used for analyses. Kidney size measurements were compared between the two groups of LBW vs NBW, and analysis using Pearson’s correlation coefficient R between kidney volume and measured GFR and parenchymal area was performed.

Results

We included 102 individuals (54 LBW, 48 NBW). Total kidney volume was 302 ± 51 ml for female NBW vs 258 ± 48 ml for female LBW (p=0.002). For men, total kidney volume was 347 ± 51 ml vs 340 ± 65 ml (p=0.7). Measured GFR was significantly associated with kidney volume with R=0.52 (p&lt;0.001) for women and R=0.39 (p=0.007) for men. Kidney parenchymal area measurements using ultrasonography showed similar results with an R=0.77 between the MRI and the ultrasonography measurement and similar differences for sex and birth weight were seen.

Conclusion

Healthy middle-aged females born with LBW have smaller kidneys than healthy middle-aged females born with NBW, no difference were seen for males. Kidney volume associate with measured GFR.

A woman in her fifties with abdominal pain and severe lactic acidosis

BACKGROUND

Pheochromocytoma is referred to as 'the great mimic' with a broad spectrum of presenting symptoms. In the following case, the diagnosis had an unusual presentation as a medical emergency - pheochromocytoma crisis.

CASE PRESENTATION

A previously healthy woman in her fifties was admitted due to abdominal pain and dyspnoea. At admission she was haemodynamically stable, with stable respiration, but arterial blood gas showed serious lactic acidosis with pH 6.8 (7.35-7.45), HCO3 3 mmol/l (22-26) and lactate 28 mmol/L (0.4-1.8). Her haemoglobin level was 12 g/dl (11,7-17,0). Further examination with CT and gastroscopy confirmed a duodenal bleeding. The lactic acidosis was corrected quickly, but the patient developed acute kidney injury, rhabdomyolysis and increased liver enzymes. The complex composition of organ manifestations could not be explained by the duodenal bleeding alone. An adrenal mass with high density was identified through re-evaluation of the CT scans. In the following case, a duodenal bleeding provoked catecholamine-induced haemodynamic instability and end-organ damage in a patient with an undiagnosed pheochromocytoma.

INTERPRETATION

Endocrine emergencies are important differential diagnoses in critically ill patients. Pheochromocytoma crisis most commonly presents as hypertensive crisis or catecholamine cardiomyopathy but can also lead to lactic acidosis and multi-organ failure.

Low birthweight is associated with lower glomerular filtration rate in middle-aged mainly healthy women

Background

Low birthweight (LBW) has been shown to increase the risk of severe kidney disease. Studies have also shown associations between LBW and lower estimated glomerular filtration rate (GFR) in young adults. In this study we investigated whether LBW associates with measured GFR (mGFR) in middle-aged mainly healthy adults.

Methods

We invited individuals with LBW (1100–2300 g) and individuals with normal BW (NBW; 3500–4000 g) ages 41–52 years. GFR was measured using plasma clearance of iohexol. BW and BW for gestational age (BWGA) were obtained from the Medical Birth Registry of Norway and tested as main predictors. GFR was the main outcome.

Results

We included 105 individuals (57 LBW and 48 NBW). The mean GFR was 95 ± 14 mL/min/1.73 m² in the LBW group and 100 ± 13 mL/min/1.73 m² in the NBW group (P = 0.04). There was a significant sex difference: in women the mean GFR was 90 ± 12 versus 101 ± 14 mL/min/1.73 m² in the LBW and NBW groups, respectively (P = 0.006), whereas corresponding values for men were 101 ± 15 versus 100 ± 11 mL/min/1.73 m² (P = 0.7). Using linear regression, we found the GFR was 4.5 mL/min/1.73 m² higher per 1 kg higher BW for women (P = 0.02), with a non-significant 1.2 mL/min/1.73 m² lower GFR for men (P = 0.6). In analyses of BWGA, there was also a significant association for women, but not for men.

Conclusions

Middle-aged mainly healthy women with LBW had lower mGFR as compared with women with NBW. No such difference was found for men.

Intrauterine growth restriction, preterm birth and risk of end-stage renal disease during the first 50 years of life

Background

Low birth weight (LBW) is associated with a higher risk of end-stage renal disease (ESRD). The relative impacts of absolute birth weight, birth weight in relation to gestational age and preterm birth are, however, uncertain.

Methods

The Medical Birth Registry of Norway has since 1967 recorded data on all births. All patients with ESRD since 1980 have been registered in the Norwegian Renal Registry. Data from these registries were linked. All individuals registered in the Medical Birth Registry were included and the development of ESRD was used as endpoint in Cox regression statistics. LBW and LBW for gestational age [small for gestational age (SGA)] according to the 10th percentiles were used as the main predictor variables.

Results

Of the 2 679 967 included subjects, 1181 developed ESRD. Compared with subjects without LBW, subjects with LBW had an adjusted hazard ratio (aHR) for ESRD of 1.61 (1.38–1.98). SGA had an aHR of 1.44 (1.22– 1.70). Further analyses showed that as compared with subjects who had none of the risk factors LBW, SGA and preterm birth, subjects with one risk factor had an aHR of 1.05 (0.84–1.31), subjects with two risk factors had an aHR of 1.67 (1.40–1.98) and subjects with three risk factors had an aHR of 2.96 (1.84–4.76).

Conclusions

We conclude that LBW was associated with increased risk for ESRD during the first 50 years. Our analyses add to previous knowledge showing that only subjects with at least two of the risk factors LBW, SGA or preterm birth have increased risk.

Intrauterine Growth Restriction and Risk of Diverse Forms of Kidney Disease during the First 50 Years of Life

BACKGROUND AND OBJECTIVES

Previous studies have shown that individuals with low birth weight (LBW) or small for gestational age (SGA) have higher risk of kidney failure. This study investigates birth-related exposures and risk of CKD and other kidney diagnoses.

DESIGN, SETTING, PARTICIPANT, & MEASUREMENTS

The Medical Birth Registry of Norway has registered extensive medical data on all births in Norway since 1967. The Norwegian Patient Registry has registered diagnostic codes for all admissions and outpatient visits to Norwegian hospitals since 2008. Data from these registries were linked, and risk of CKD and other groups of kidney disease were analyzed using logistic regression statistics. LBW (below the tenth percentile), SGA (birth weight below the tenth percentile for gestational age), and preterm birth (<37 weeks) were analyzed as exposures.

RESULTS

A total of 2,663,010 individuals were included. After a mean follow-up of 26 years (maximum 50 years), 4495 had been diagnosed with CKD and 12,818 had been diagnosed with other groups of kidney disease. LBW was associated with an odds ratio (OR) for CKD of 1.72 (95% confidence interval [95% CI], 1.60 to 1.90), SGA with an OR of 1.79 (95% CI, 1.65 to 1.94), and preterm birth with an OR of 1.48 (95% CI, 1.33 to 1.66). Analyses using diagnosis of CKD at stages 3-5 as end point showed similar results. Results were similar for men and women. We analyzed adjusted ORs for other groups of kidney disease and found that LBW was associated with an adjusted OR of 1.44 (95% CI, 1.33 to 1.56) for acute kidney disease, 1.24 (95% CI, 1.14 to 1.36) for GN, 1.35 (95% CI, 1.17 to 1.56) for cystic kidney disease, and 1.15 (95% CI, 1.06 to 1.25) for kidney disease resulting from kidney or urinary tract malformations.

CONCLUSIONS

LBW, SGA, and preterm birth are associated with higher risk of CKD in the first 50 years of life. Risk of other groups of kidney disease was less pronounced.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_08_17_CJN04080320.mp3.

P0337PROTEOME CHANGES IN TUBULOINTERSTITIAL TISSUE OF PROGRESSIVE VS NON-PROGRESSIVE IGAN

Background and Aims

IgA nephropathy (IgAN), a common glomerulonephritis worldwide, is associated with a significant risk of progression to end-stage renal failure. In the Oxford classification, tubular atrophy is an established important risk factor for the risk of progression but few studies have investigated possible tubulointerstitial markers and the mechanisms of progression in IgAN. The present study investigated changes in the tubulointerstitial proteome from patients with IgAN.

Method

Based on data from the Norwegian Kidney Biopsy Registry and the Norwegian Renal Registry, two groups were included: IgAN patients with (n=9) or without (n=16) progression to ESRD during 10 years. Tubulointerstitial tissue without discernible interstitial expansion or pronounced tubular alterations were microdissected, proteome was analysed using mass spectrometry and protein abundances were compared between groups.

Results: Proteomic analyses quantified 2562 proteins with 2 or more unique peptides . Of these, 201 proteins had significant different abundance between progressive and non-progressive IgAN patients, 96 were more abundant and 105 less abundant. Periostin was the protein with the highest fold change between progressive and non progressive IgAN (fc 9.59, p&lt;0.05). Proteins related to inflammation were more abundant and proteins involved in the aerobic energy metabolism and energy demanding ion channels were significantly less abundant in progressive vs non-progressive patients.

Conclusion

Our study describes extensive proteome changes of tubulo-interstitial tissue in patients with progressive IgAN and indicates several proteins and pathways that are important in the progression of the disease.

P0731LOW BIRTH WEIGHT IS ASSOCIATED WITH LOWER MEASURED GLOMERULAR FILTRATION RATE IN ADULT AGE

Background and Aims

Low birth weight (LBW) has been shown to increase the risk of severe kidney disease. Studies have also shown that LBW is associated with lower estimated glomerular filtration rate (eGFR) or creatinine clearance in young adults. In the present study we investigated whether LBW associate with measured glomerular filtration rate (mGFR) in 40-50 year old adults.

Method

Retrospective longitudinal cohort study using the Medical Birth Registry of Norway to invite 200 individuals with LBW (birth weight ≤ 2300 gram) and 200 individuals with normal birth weight (NBW, 3500 – 4000 grams). All participants were aged 41 – 52 at time of examination. GFR was measured using plasma clearance of iohexol. Birth weight and gestational age were reported from the Medical Birth Registry. Main outcome was difference in measured GFR.

Results

We included 105 individuals – 57 LBW and 48 NBW – 55% females. Mean GFR was 94.8 ± 14.2 ml/min/1.73m2 in the LBW group and 100.2 ± 12.5 ml/min/1.73m2 in the NBW group (p=0.043). In females the mean GFR was 90.4 ± 12.2 ml/min/1.73m2 in the LBW group and 100.5 ± 14.0 ml/min/1.73m2 in the NBW group (p=0.005). In males the mean GFR was 101.4 ± 14.5 and 100 ± 11.2 ml/min/1.73m2 in the LBW and NBW groups respectively (p=0.7). In a multi-regression model adjusting for age, maternal age and maternal civil status, we found an increase in mGFR of 4.5 ml/min/1.73m2 for an increase of 1 kg in birth weight (p= 0.02) for women. For men there was a non-significant decrease of 1.2 ml/min/1.73m2 for an increase of 1 kg in birth weight (p=0.6).

Conclusion

Women aged 41-52 years with low birth weight had significantly lower measured GFR as compared with participants with normal birth weight, there was no difference for men.

P0767INTRAUTERINE GROWTH RESTRICTION AND RISK OF KIDNEY DISEASE DURING THE FIRST 50 YEARS OF LIFE

Background and Aims

Previous studies have shown that Low Birth Weight (LBW) and small for gestational age (SGA) are associated with increased risk of end-stage renal disease. Few population-based studies have however investigated risk of less severe kidney disease and in the present study, we investigate risk of chronic kidney disease and other kidney disease diagnoses.

Method

The Norwegian Patient Registry (NPR) has registered ICD diagnostic codes for all admissions and outpatient visits to Norwegian hospitals since 2008 (available for 2008-2016 in this study). The Norwegian Medical Birth Registry (MBR) has registered birth weight, gestational age and several other data on maternal and offspring health for all birth in Norway since 1967. Data from these registries were linked and risk of chronic kidney disease (CKD) and other groups of kidney disease were analyzed with logistic regression statistics. LBW (less than the 10th percentile), SGA (less than the 10th percentile) and preterm birth (less than 37 weeks) were analyzed as risk markers. Adjusted analyses were performed for the main analyses by including birth year, gender, maternal disease, maternal preeclampsia, maternal marital status and malformations in the newborn.

Results

Of the 2,663,010 included individuals, 4,495 had been diagnosed with CKD and 12,818 with acute kidney disease, glomerulonephritis, hereditary kidney disease or kidney disease due to kidney or urinary tract malformations. LBW was associated with an adjusted odds ratio (aOR) for CKD of 1.61 (1.48-1.74), SGA with an aOR of 1.51 (1.39-1.63) and preterm birth with an aOR of 1.47 (1.31-1.66). As compared to subjects with none of these risk factors (LBW, SGA or preterm birth), subjects with only one risk factor had an aOR of 1.49 (1.35-1.66), subjects with 2 risk factors had adjusted aOR of 1.72 (1.57-1.88) and subjects with 3 risk factors had aOR of 2.56(1.99-3.29). Analyses of chronic kidney disease stage 3, 4 and 5 showed similar results. There were no significant gender differences. We further analysed aOR for other groups of kidney disease and found that LBW was associated with aOR of 1.52 (1.40-1.65) for acute kidney disease, 1.26 (1.16-1.38) for glomerulonephritis, 1.55 (1.34-1.80) for hereditary kidney disease and 1.38 (1.27-1.49) for kidney disease due to kidney or urinary tract malformations; analyses for the other risk factors showed similar results.

Conclusion

LBW and SGA are strong risk factors for diagnosis of all stages of CKD during the first 50 years of life and the risks seem to be increased also for other groups of kidney disease. Our results underline the public health importance of LBW and SGA.

Measurement of renal functional response using iohexol clearance-a study of different outpatient procedures

Background

Glomerular filtration rate (GFR) increases after a heavy protein load; an increase termed renal functional response (RFR). Decreased RFR could be a marker of early kidney damage, but published methods are cumbersome in the outpatient setting. The present study investigates the use of iohexol clearance to measure RFR in outpatients using both one- and two-sample methods.

Methods

Fourteen healthy volunteers with a mean ± SD age of 42 ± 12 years were included (six males and eight females). GFR was measured using plasma iohexol clearance with one- and two-sample methodologies. Four measurements in each individual were performed: one baseline test and three protein loading tests containing 80 g protein (commercially available protein supplementations from Myo Nutrition and Proteinfabrikken and 350 g chicken breast). RFR was calculated as percentage increase in GFR from the baseline test.

Results

Mean RFR was 11.4 ± 5.4% and 12.1 ± 6.4% using one- and two-sample methods, respectively. The three different protein loads resulted in similar mean RFR but there was considerable intra-individual variability. One- and two-sample methods for measurement of RFR showed similar results with near-identical means, but there was some intra-individual variation that was similar for different protein loads. The overall 95% limit of agreement between one- and two-sample methods for calculating RFR was -8.7 to 7.3.

Conclusions

RFR can be investigated using plasma iohexol clearance in an outpatient setting. Protocols using commercially available protein supplementation showed a mean RFR of about 12%. One- and two-sample methods for measuring RFR yield similar results.

Characterization of glomerular extracellular matrix in IgA nephropathy by proteomic analysis of laser-captured microdissected glomeruli

Background

IgA nephropathy (IgAN) involves mesangial matrix expansion, but the proteomic composition of this matrix is unknown. The present study aimed to characterize changes in extracellular matrix in IgAN.

Methods

In the present study we used mass spectrometry-based proteomics in order to quantitatively compare protein abundance between glomeruli of patients with IgAN (n = 25) and controls with normal biopsy findings (n = 15).

Results

Using a previously published paper by Lennon et al. and cross-referencing with the Matrisome database we identified 179 extracellular matrix proteins. In the comparison between IgAN and controls, IgAN glomeruli showed significantly higher abundance of extracellular matrix structural proteins (e.g periostin, vitronectin, and extracellular matrix protein 1) and extracellular matrix associated proteins (e.g. azurocidin, myeloperoxidase, neutrophil elastase, matrix metalloproteinase-9 and matrix metalloproteinase 2). Periostin (fold change 3.3) and azurocidin (3.0) had the strongest fold change between IgAN and controls; periostin was also higher in IgAN patients who progressed to ESRD as compared to patients who did not.

Conclusion

IgAN is associated with widespread changes of the glomerular extracellular matrix proteome. Proteins important in glomerular sclerosis or inflammation seem to be most strongly increased and periostin might be an important marker of glomerular damage in IgAN.

Prevalence and prognostic ability of the GOLD 2017 classification compared to the GOLD 2011 classification in a Norwegian COPD cohort

Rationale

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2017 is based on an ABCD assessment tool of symptoms and exacerbation history and grade 1–4 of airflow limitation severity, facilitating classification either into 4 groups (ABCD) or 16 groups (1A-4D). We aimed to compare the GOLD 2011, GOLD 2017 ABCD, and GOLD 2017 1A-4D classifications in terms of their distribution and prediction of mortality and hospitalizations.

Methods

In the GenKOLS study, 912 COPD patients with FEV1 less than 80% of the predicted answered questionnaires and performed lung function testing in 2003–2005. The patients were recruited from a hospital patient registry (n=662) and from the general population (n=250), followed up until 2011 with respect to all-cause and respiratory mortality, and all-cause and respiratory hospitalizations. We performed logistic regression and receiver operating curve (ROC) analyses for the different classifications with estimations of area under the curve (AUC) for comparisons.

Results

Mean age at baseline was 60 years (SD 11), 55% were male. Mean duration of follow-up was 91 months. By GOLD 2011, 21% were classified as group A, 29% group B, 6% group C, and 43% as group D, corresponding percentages for GOLD 2017 were: 25%, 52%, 3%, and 20%. The GOLD 2011 classification had higher AUC values than the GOLD 2017 group ABCD classification for respiratory mortality and hospitalization, but after inclusion of airflow limitation severity in GOLD 2017 groups 2A–4D, AUC values were significantly higher with GOLD 2017.

Conclusion

In a clinically relevant sample of COPD patients, the GOLD 2017 classification doubles the prevalence of group B and halves the prevalence of groups C and D as compared to the GOLD 2011 classification. The prediction of respiratory mortality and respiratory hospitalization was better for GOLD 2017 2A–4D taking airflow limitation severity into account, as compared to GOLD 2017 ABCD and GOLD 2011.

Transcriptome-proteome integration of archival human renal cell carcinoma biopsies enables identification of molecular mechanisms

Renal cell cancer is among the most common forms of cancer in humans, with around 35,000 deaths attributed to kidney carcinoma in the European Union in 2012 alone. Clear cell renal cell carcinoma (ccRCC) represents the most common form of kidney cancer and the most lethal of all genitourinary cancers. Here, we apply omics technologies to archival core biopsies to investigate the biology underlying ccRCC. Knowledge of these underlying processes should be useful for the discovery and/or confirmation of novel therapeutic approaches and ccRCC biomarker development. From partial or full nephrectomies of 11 patients, paired core biopsies of ccRCC-affected tissue and adjacent (“peritumorous”) nontumor tissue were both sampled and subjected to proteomics analyses. We combined proteomics results with our published mRNA sequencing data from the same patients and with published miRNA sequencing data from an overlapping patient cohort from our institution. Statistical analysis and pathway analysis were performed with JMP Genomics and Ingenuity Pathway Analysis (IPA), respectively. Proteomics analysis confirmed the involvement of metabolism and oxidative stress-related pathways in ccRCC, whereas the most affected pathways in the mRNA sequencing data were related to the immune system. Unlike proteomics or mRNA sequencing alone, a combinatorial cross-omics pathway analysis approach captured a broad spectrum of biological processes underlying ccRCC, such as mitochondrial damage, repression of apoptosis, and immune system pathways. Sirtuins, immunoproteasome genes, and CD74 are proposed as potential targets for the treatment of ccRCC.

Low birth weight associates with glomerular area in young male IgA nephropathy patients

Background

In a recent study we demonstrated that low birth weight (LBW) was associated with increased risk of progressive IgA nephropathy (IgAN). In the present study we investigate whether this could be explained by differences in glomerular morphological parameters.

Methods

The Medical Birth Registry of Norway has registered all births since 1967 and the Norwegian Kidney Biopsy Registry has registered all kidney biopsies since 1988. Patients diagnosed with IgAN, registered birth weight and estimated glomerular filtration rate above 60 ml/min/1.73m² at time of diagnosis were eligible for inclusion. Patients were included in a case-control manner based on whether or not they had LBW or were small for gestational age (SGA). Glomerular area, volume and density were measured using high resolution digital images and differences were compared between groups.

Results

We included 51 IgAN patients with a mean age of 23.6 years, 47.1% male. Compared to IgAN patients without LBW or SGA, IgAN patients with LBW and/or SGA had larger glomerular area (16,235 ± 3744 vs 14,036 ± 3502 μm², p-value 0.04). This was significant for total cohort and male but not female. On separate analysis by gender, glomerular area was significantly larger only in males (17,636 ± 3285 vs 13,346 ± 2835 μm², p-value 0.004). Glomerular density was not different between groups. In adjusted linear regression analysis, glomerular area was negatively associated with birth weight.

Conclusion

Among young adult IgAN patients, low birth weight is associated with having larger glomerular area, especially in males. Larger glomeruli may be a sign of congenital nephron deficit that may explain the increased risk of progressive IgAN.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1070-7) contains supplementary material, which is available to authorized users.

Glomerular abundance of complement proteins characterized by proteomic analysis of laser-captured microdissected glomeruli associates with progressive disease in IgA nephropathy

Background

The clinical course of IgA nephropathy (IgAN) is variable and complement activation may predict prognosis. The present study investigated whether glomerular abundance of complement proteins associates with progression to end-stage renal disease (ESRD) in patients for whom prognosis could not be predicted based on clinical variables.

Methods

Based on data from the Norwegian Kidney Biopsy Registry and the Norwegian Renal Registry, three groups were included: IgAN patients with (n = 9) or without (n = 16) progression to ESRD during 10 years, and controls (n = 15) with a normal kidney biopsy. IgAN patients had eGFR > 45 ml/min/1.73 m² and non-nephrotic proteinuria at time of biopsy. Using stored formalin-fixed paraffin embedded kidney biopsy tissue, about 100 glomerular cross sections were microdissected for each patient. Samples were analyzed by liquid chromatography–tandem mass spectrometry and relative abundances of complement proteins were compared between groups.

Results

Proteomic analyses quantified 2018 proteins, of which 28 proteins belong to the complement system. As compared to IgAN patients without progressive disease, glomeruli from patients with progressive IgAN had significantly higher abundance of components of the classical and the terminal complement pathways, and inhibitory factors such as Factor H and factor H related proteins. Abundance of complement proteins classified progressors from non-progressors with an area under ROC curve of 0.91 (p = 0.001). Clinical and morphological data were similar between the two patient groups and could not predict progressive IgAN.

Conclusions

In conclusion, higher glomerular abundance of complement proteins was associated with a progressive clinical course in IgAN and are candidate biomarkers to predict prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-017-9165-x) contains supplementary material, which is available to authorized users.

Low Birth Weight and Risk of Progression to End Stage Renal Disease in IgA Nephropathy--A Retrospective Registry-Based Cohort Study

Background

Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero. In this study, we investigate whether having been born LBW and/or small for gestational age (SGA) predict progression to ESRD in IgA nephropathy (IgAN) patients.

Study Design

Retrospective registry-based cohort study.

Settings & Participants

The Medical Birth Registry has recorded all births since 1967 and the Norwegian Renal Registry has recorded all patients with ESRD since 1980. Based on data from the Norwegian Kidney Biopsy Registry we included all patients diagnosed with IgAN in Norway from 1988–2013. These registries were linked and we analysed risk of progression to ESRD associated with LBW (defined as birth weight less than the 10^th percentile) and/or SGA (defined as birth weight less than the 10^th percentile for gestational week) by Cox regression statistics.

Results

We included 471 patients, of whom 74 developed ESRD. As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1–3.7) for the total cohort, 2.2 (1.1–4.4) for males and 1.3 (0.30–5.8) for females. Corresponding HRs for SGA were 2.2 (1.1–4.2), 2.7 (1.4–5.5) and 0.8 (0.10–5.9). Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3–1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5–6.8).

Limitation

Mean duration of follow-up only 10 years and maximum age only 46 years.

Conclusion

Among IgAN patients, LBW and/or SGA was associated with increased risk for progression to ESRD, the association was stronger in males.

Proteomic Analysis of Minimally Damaged Renal Tubular Tissue from Two-Kidney-One-Clip Hypertensive Rats Demonstrates Extensive Changes Compared to Tissue from Controls

BACKGROUND

Tubular atrophy and interstitial fibrosis mark the final stage in most forms of progressive kidney diseases. Little is known regarding changes in the tubular proteome. In this study, we investigated changes in the tubular proteome of normal or minimally damaged tubular tissue in the non-clipped kidney from rats with two-kidney one-clip (2K1C) hypertension.

METHODS

Formalin-fixed paraffin-embedded kidney sections from four 2K1C rats with hypertensive kidney damage and 6 sham rats were used. Tubulointerstitial tissue without discernable interstitial expansion or pronounced tubular alterations was microdissected and this was assumed to represent an early stage of chronic tubular damage in 2K1C. Samples were analyzed by mass spectrometry and relative protein abundances were compared between 2K1C and sham.

RESULTS

A total of 1,160 proteins were identified with at least 2 unique peptides, allowing for relative quantitation between samples. Among these, 151 proteins were more abundant, and 192 proteins were less abundant in 2K1C compared with sham. Transgelin, vimentin and creatine kinase B-type were among the proteins that were most increased in 2K1C. Ingenuity Pathway Analysis showed increased abundance of proteins related to Rho signaling and protein turnover (eIF2 signaling and protein ubiquitination), and decreased abundance of proteins related to fatty acid β-oxidation.

CONCLUSION

Tubular tissue from normal or minimally damaged hypertensive kidney damage demonstrate extensive proteomic changes with upregulation of pathways associated with progressive kidney damage, such as Rho signaling and protein turnover. Thus, proteomics presents itself to be a promising tool for the discovery of early damage markers from not yet morphologically visible tubular damage.

Familial Factors, Low Birth Weight, and Development of ESRD: A Nationwide Registry Study

BACKGROUND

Previous studies have demonstrated that low birth weight (LBW) is associated with higher risk for end-stage renal disease (ESRD). However, both LBW and ESRD cluster in families. The present study investigates whether familial factors explain the association between LBW and ESRD.

STUDY DESIGN

Retrospective registry-based cohort study.

SETTING & PARTICIPANTS

Since 1967, the Medical Birth Registry of Norway has recorded medical data for all births in the country. Sibling data are available through the Norwegian Population Registry. Since 1980, all patients with ESRD in Norway have been registered in the Norwegian Renal Registry. Individuals registered in the Medical Birth Registry with at least 1 registered sibling were included.

PREDICTOR

LBW in the participant and/or LBW in at least 1 sibling.

OUTCOME

ESRD.

RESULTS

Of 1,852,080 included individuals, 527 developed ESRD. Compared with individuals without LBW and with no siblings with LBW, individuals without LBW but with a sibling with LBW had an HR for ESRD of 1.20 (95% CI, 0.91-1.59), individuals with LBW but no siblings with LBW had an HR of 1.59 (95% CI, 1.18-2.14), and individuals with LBW and a sibling with LBW had an HR of 1.78 (95% CI, 1.26-2.53). Similar results were observed for individuals who were small for gestational age (SGA). Separate analyses for the association of age 18 to 42 years and noncongenital ESRD showed stronger associations for SGA than for LBW, and the associations were not statistically significant for age 18 to 42 years for LBW.

LIMITATIONS

Follow-up only until 42 years of age.

CONCLUSIONS

LBW and SGA are associated with higher risk for ESRD during the first 40 years of life, and the associations were not explained by familial factors. Our results support the hypothesis that impaired intrauterine nephron development may be a causal risk factor for progressive kidney disease.

Addition of eGFR and Age Improves the Prognostic Absolute Renal Risk-Model in 1,134 Norwegian Patients with IgA Nephropathy

BACKGROUND

Predicting outcome in individual patients with IgA nephropathy (IgAN) is difficult but important. For this purpose, the absolute renal risk (ARR) model has been developed in a French cohort to calculate the risk of end-stage renal disease (ESRD) and death. ARR (0-3) is scored in individual IgAN patients based on the presence of proteinuria ≥1 g/24 h, hypertension, and severe histopathological lesions (1 point per risk factor). We have validated the ARR model in a Norwegian cohort of IgAN patients and tested whether adding data on initial estimated glomerular filtration rate (eGFR) and age improved prediction.

METHODS

IgAN patients diagnosed between 1988 and 2012 were identified in the Norwegian Kidney Biopsy Registry, and endpoints were identified by record linkage with the Norwegian Renal Registry (ESRD) and the Population Registry (deaths).

RESULTS

We identified 1,134 IgAN patients. The mean duration of follow-up was 10.2 years (range 0.0 to 25.7 years). Two hundred and fifty one patients developed ESRD and there were 69 pre-ESRD deaths. The ARR model significantly stratified the IgAN cohort according to risk of ESRD/death. The inclusion of eGFR and age significantly improved the ARR prognostic model; in the receiver operator characteristics (ROC) analysis, area under the curve (AUC) at 10-years of follow-up increased from 0.79 to 0.89, p < 0.001.

CONCLUSIONS

ARR is a suitable prognostic model for stratifying IgAN patients according to the risk of ESRD or death. Including initial eGFR and age in the model substantially improved its accuracy in our nationwide cohort.

Proteomic analysis of formalin-fixed paraffin-embedded glomeruli suggests depletion of glomerular filtration barrier proteins in two-kidney, one-clip hypertensive rats

Background

It is well known that hypertension may cause glomerular damage, but the molecular mechanisms involved are still incompletely understood.

Methods

In the present study, we used formalin-fixed paraffin-embedded (FFPE) tissue to investigate changes in the glomerular proteome in the non-clipped kidney of two-kidney one-clip (2K1C) hypertensive rats, with special emphasis on the glomerular filtration barrier. 2K1C hypertension was induced in 6-week-old Wistar Hannover rats (n = 6) that were sacrificed 23 weeks later and compared with age-matched sham-operated controls (n = 6). Tissue was stored in FFPE tissue blocks and later prepared on tissue slides for laser microdissection. Glomeruli without severe morphological damage were isolated, and the proteomes were analysed using liquid chromatography–tandem mass spectrometry.

Results

2K1C glomeruli showed reduced abundance of proteins important for slit diaphragm complex, such as nephrin, podocin and neph1. The podocyte foot process had a pattern of reduced abundance of transmembrane proteins but unchanged abundances of the podocyte cytoskeletal proteins synaptopodin and α-actinin-4. Lower abundance of important glomerular basement membrane proteins was seen. Possible glomerular markers of damage with increased abundance in 2K1C were transgelin, desmin and acyl-coenzyme A thioesterase 1.

Conclusions

Microdissection and tandem mass spectrometry could be used to investigate the proteome of isolated glomeruli from FFPE tissue. Glomerular filtration barrier proteins had reduced abundance in the non-clipped kidney of 2K1C hypertensive rats.

Familial clustering of ESRD in the Norwegian population

BACKGROUND AND OBJECTIVES

Studies and clinical experience suggest that kidney disease clusters in families, but few population-based studies have been performed. This study investigates risks and causes of ESRD in Norwegians with and without a first-degree relative with ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

On the basis of data from the Norwegian Population Registry, first-degree relatives for most Norwegians were identified. All Norwegians with ESRD (defined as chronic RRT) since 1980 have been registered in the Norwegian Renal Registry. All Norwegians born in Norway who were alive in 1980 and had at least one registered relative were included. For this study, data on ESRD were available through 2009, and individuals without ESRD were censored at December 31, 2009. Data were analyzed in a cohort design, with ESRD in a first-degree relative of the included person as the main explanatory variable. Risks of ESRD and different causes of ESRD were analyzed using Cox regression statistics.

RESULTS

In total, 5,119,134 individuals were included, of whom 8203 individuals developed ESRD during follow-up and 27,046 individuals had a first-degree relative with ESRD. Compared with individuals without a first-degree relative with ESRD, individuals with a first-degree relative with ESRD had a relative risk of ESRD of 7.2 (95% confidence interval, 6.5 to 8.1). Similar analyses showed that relative risk of ESRD caused by nonhereditary causes was 3.7 (95% confidence interval, 3.1 to 4.4), relative risk of ESRD caused by glomerular disease was 5.2 (95% confidence interval, 4.1 to 6.6), relative risk of ESRD caused by interstitial disease was 4.7 (95% confidence interval, 3.1 to 7.3), relative risk of ESRD caused by diabetic nephropathy was 2.6 (95% confidence interval, 1.6 to 4.1), and relative risk of ESRD caused by hypertensive nephrosclerosis was 2.6 (95% confidence interval, 1.6 to 4.1). Relative risk of nonhereditary parenchymal renal disease was 3.8 (95% confidence interval, 3.1 to 4.7).

CONCLUSIONS

As expected, ESRD clusters in families. Interestingly, ESRD without known hereditary cause also clusters in families.

Preeclampsia in healthy women and endothelial dysfunction 10 years later

OBJECTIVE

Recent studies have shown that women with a history of preeclampsia have an increased risk of cardiovascular disease. The present study investigated cardiovascular risk factors 10 years after preeclampsia in previously healthy women.

STUDY DESIGN

Based on data from the Medical Birth Registry in Norway, we selected 182 women with and 180 women without preeclampsia in their first pregnancy 9-11 years earlier, excluding women with cardiovascular or renal disease before pregnancy. Flow-mediated dilation of the brachial artery (FMD) and intima-media thickness (IMT) of the carotid artery were measured and blood samples were drawn. Blood samples were analyzed for cardiovascular risk markers and for circulating markers of endothelial function.

RESULTS

A total of 89 women with previous preeclampsia and 69 women without preeclampsia participated, an overall attendance rate of 44%. FMD and IMT were similar between groups. Women with previous preeclampsia more often had urate and soluble fms-like tyrosine kinase values above the 75th percentile (odds ratio [OR], 2.4; P = .03, and OR, 2.4; P = .04, respectively) and high-density lipoprotein cholesterol values below the 25th percentile (OR, 2.3; P = .04). Women with preeclampsia with low birthweight offspring were associated with asymmetric dimethylarginine, L-arginine, and homoarginine above the 75th percentile, whereas the women with preeclampsia with normal-weight offspring were associated with urate and soluble fms-like tyrosine kinase above the 75th percentile.

CONCLUSION

Preeclampsia was not associated with impaired FMD or increased IMT 10 years after pregnancy in previously healthy women, but preeclampsia was associated with changes in circulating markers that might represent early endothelial dysfunction.

Mortality in patients with IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis globally. Few studies have investigated mortality in patients with IgAN compared with the age- and sex-adjusted general population.

STUDY DESIGN

Cohort study with record linkage between the Norwegian Kidney Biopsy Registry, Norwegian Cause of Death Registry, and Norwegian Renal Registry.

SETTING & PARTICIPANTS

633 patients diagnosed with IgAN in 1988-2004.

PREDICTOR

Estimated glomerular filtration rate (eGFR), age, and sex.

OUTCOMES

Deaths and causes of death before and after the onset of end-stage renal disease through 2008.

RESULTS

Mean follow-up was 11.8 (range, 0-20.8) years. During the observation period, the observed number of deaths was 80 and the expected number was 42.1, resulting in a standardized mortality ratio (SMR) of 1.9 (95% CI, 1.5-2.4). Risk stratification based on initial eGFR showed that SMR was 1.0 (95% CI, 0.6-1.6) if eGFR was ≥60 mL/min/1.73 m(2), 1.9 (95% CI, 1.3-2.8) if eGFR was 30-60 mL/min/1.73 m(2), and 3.6 (95% CI, 2.6-5.0) in patients with eGFR <30 mL/min/1.73 m(2). Renal replacement therapy (RRT) was initiated in 146 patients and 35 of the 80 deaths occurred after the start of RRT. The age- and sex-adjusted SMR was not increased significantly in the pre-RRT period (1.3; 95% CI, 1.0-1.7), but was increased after initiation of RRT (4.9; 95% CI, 3.5-7.0). The most common cause of death was cardiovascular disease, accounting for 45% of all deaths.

LIMITATIONS

Treatment during follow-up is not known.

CONCLUSIONS

Mortality in patients with IgAN was twice the expected rate, but not significantly increased before RRT. The risk of end-stage renal disease was substantially higher than risk of death.

Preeclampsia and prevalence of microalbuminuria 10 years later

BACKGROUND AND OBJECTIVES

A recent meta-analysis found that about 30% of women with a previous preeclamptic pregnancy had persistent microalbuminuria at follow-up. The analysis was, however, based on small studies, and more data are needed.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using data from the Medical Birth Registry in Norway, this study identified women with or without preeclampsia in their first pregnancy 9-11 years previously (1998-2000). Women with diabetes, rheumatic disease, essential hypertension, or renal disease before first pregnancy and/or preeclampsia in later pregnancies were excluded. Eighty-nine women with and 69 women without preeclampsia participated in the study. Urinary albumin-to-creatinine ratio (ACR) was measured in three morning urine samples. Estimated GFR (eGFR) was calculated using the CKD-Epidemiology Collaboration formula.

RESULTS

Median urinary ACR in follow-up urine samples was 0.53 mg/mmol for women with and 0.50 mg/mmol for women without preeclampsia (P=0.54). Only one woman (1%) with previous preeclampsia had urinary ACR >2.5 mg/mmol in two of three urine samples. Preeclampsia was not associated with urinary ACR above the 75th percentile. Women with preeclampsia did not have significantly higher eGFR than women without preeclampsia (107.9 versus 104.9 ml/min per 1.73 m(2); P=0.12), but preterm preeclampsia was significantly associated with eGFR above the 75th percentile (P=0.03).

CONCLUSIONS

In this population-based study of otherwise healthy women, preeclampsia 10 years earlier was not associated with increased risk of persisting microalbuminuria. Estimated GFR was not significantly different between women with and those without preeclampsia, but preterm preeclampsia was associated with high normal eGFR.

Agalsidase benefits renal histology in young patients with Fabry disease

The effect of early-onset enzyme replacement therapy on renal morphologic features in Fabry disease is largely unknown. Here, we evaluated the effect of 5 years of treatment with agalsidase alfa or agalsidase beta in 12 consecutive patients age 7-33 years (median age, 16.5 years). We performed renal biopsies at baseline and after 5 years of enzyme replacement therapy; 7 patients had additional biopsies after 1 and 3 years. After a median of 65 months, biopsy findings from all patients showed total clearance of glomerular endothelial and mesangial cell inclusions, and findings from 2 patients showed complete clearance of inclusions from epithelial cells of the distal tubule. The 4 patients who received the highest dose of agalsidase exhibited substantial clearance of podocyte inclusions, and the youngest patient had nearly complete clearance of these inclusions. Linear regression analysis showed a highly significant correlation between podocyte globotriaocylceramide clearance and cumulative agalsidase dose (r=0.804; P=0.002). Microalbuminuria normalized in five patients. In summary, long-term enzyme replacement therapy in young patients can result in complete globotriaocylceramide clearance of mesangial and glomerular endothelial cells across all dosage regimens, and clearance of podocyte inclusions is dose-dependent.

Cardiovascular mortality after pre-eclampsia in one child mothers: prospective, population based cohort study

OBJECTIVE

To assess the association of pre-eclampsia with later cardiovascular death in mothers according to their lifetime number of pregnancies, and particularly after only one child.

DESIGN

Prospective, population based cohort study.

SETTING

Medical Birth Registry of Norway.

PARTICIPANTS

We followed 836,147 Norwegian women with a first singleton birth between 1967 and 2002 for cardiovascular mortality through linkage to the national Cause of Death Registry. About 23,000 women died by 2009, of whom 3891 died from cardiovascular causes. Associations between pre-eclampsia and cardiovascular death were assessed by hazard ratios, estimated by Cox regression analyses. Hazard ratios were adjusted for maternal education (three categories), maternal age at first birth, and year of first birth

RESULTS

The rate of cardiovascular mortality among women with preterm pre-eclampsia was 9.2% after having only one child, falling to 1.1% for those with two or more children. With term pre-eclampsia, the rates were 2.8% and 1.1%, respectively. Women with pre-eclampsia in their first pregnancy had higher rates of cardiovascular death than those who did not have the condition at first birth (adjusted hazard ratio 1.6 (95% confidence interval 1.4 to 2.0) after term pre-eclampsia; 3.7 (2.7 to 4.8) after preterm pre-eclampsia). Among women with only one lifetime pregnancy, the increase in risk of cardiovascular death was higher than for those with two or more children (3.4 (2.6 to 4.6) after term pre-eclampsia; 9.4 (6.5 to 13.7) after preterm pre-eclampsia). The risk of cardiovascular death was only moderately elevated among women with pre-eclamptic first pregnancies who went on to have additional children (1.5 (1.2 to 2.0) after term pre-eclampsia; 2.4 (1.5 to 3.9) after preterm pre-eclampsia). There was little evidence of additional risk after recurrent pre-eclampsia. All cause mortality for women with two or more lifetime births, who had pre-eclampsia in first pregnancy, was not elevated, even with preterm pre-eclampsia in first pregnancy (1.1 (0.87 to 1.14)).

CONCLUSIONS

Cardiovascular death in women with pre-eclampsia in their first pregnancy is concentrated mainly in women with no additional births. This association might be due to health problems that discourage or prevent further pregnancies rather than to pre-eclampsia itself. As a screening criterion for cardiovascular disease risk, pre-eclampsia is a strong predictor primarily among women with only one child-particularly with preterm pre-eclampsia.

Familial factors in the association between preeclampsia and later ESRD

BACKGROUND AND OBJECTIVES

Women with preeclampsia have increased risk of developing ESRD. This study assessed whether this can be explained by preeclampsia itself or by familial aggregation of common risk factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Since 1967, the Medical Birth Registry of Norway has registered data on all births in the country. By linkage with the Norwegian Population Registry, different, but overlapping, cohorts were defined: the first and second cohorts included women and a sibling (first cohort) or child (second cohort) with a registered first birth between 1967 and 2008. Similar cohorts were defined for men. The Norwegian Renal Registry provided data on ESRD from 1980 to June 2009.

RESULTS

Cohort 1 was used for the main analyses and included 570,675 women, 291 of whom developed ESRD after a median 18.2 years. Compared with women without preeclampsia and no siblings with preeclampsia, women without preeclampsia but a sibling with preeclampsia had a relative risk (RR) of ESRD of 0.96 (95% confidence interval, 0.59-1.6), women with preeclampsia but no siblings with preeclampsia had a RR of 6.0 (4.4-8.1), and women with preeclampsia and a sibling with preeclampsia had a RR of 2.8 (0.88-8.6). Further analyses of women showed no increased risk of ESRD if a child had preeclampsia in first pregnancy.

CONCLUSIONS

Familial aggregation of risk factors does not seem to explain increased ESRD risk after preeclampsia. These findings support the hypothesis that preeclampsia per se may lead to kidney damage.

Safety and complications of percutaneous kidney biopsies in 715 children and 8573 adults in Norway 1988-2010

BACKGROUND AND OBJECTIVES

Skepticism about performing renal biopsies is often because of uncertainty regarding risk of complications. The aim of this study was to evaluate safety and relevant complications of renal biopsies in pediatric and adult patients in a large national registry study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Kidney biopsies reported in the Norwegian Kidney Biopsy Registry from 1988 to 2010 were included. Risk factors for major complications (blood transfusion and/or surgical or catheter intervention) were analyzed using logistic regression statistics.

RESULTS

Of the 9288 biopsies included, 715 were from children, and 8573 were from adults (≥18 years). Median age was 49 years (range=2 weeks to 94 years). Gross hematuria appeared after biopsy in 1.9% of the patients; 0.9% of patients needed blood transfusion, and 0.2% of patients needed surgical intervention/catheterization. The frequencies were 1.9%, 0.9%, and 0.2% in adults and 1.7%, 0.1% and 0.1% in children, respectively; 97.9% of the biopsies were without complications. In unadjusted analyses, risk factors for major complications were age>60 years, estimated GFR<60 ml/min per 1.73 m(2), systolic hypertension, acute renal failure, and smaller clinical center size (<30 biopsies/yr). Adjusted analyses (adjusted for age and/or estimated GFR) showed higher odds ratios (OR) only for smaller clinical center (OR=1.60 [1.02-2.50]) and low estimated GFR (estimated GFR=30-59 ml/min per 1.73 m(2) [OR=4.90 (1.60-14.00)] and estimated GFR<30 ml/min per 1.73 m(2) [OR 15.50 (5.60-43.00)]).

CONCLUSIONS

Percutaneous renal biopsy is a low-risk procedure in all ages. Reduced estimated GFR and smaller center size are associated with an increased risk of major complications.

Long-term risk of ESRD in IgAN; validation of Japanese prognostic model in a Norwegian cohort

BACKGROUND

Recently, a Japanese model used to predict 10-year risk of end-stage renal disease (ESRD) in IgA nephropathy (IgAN) patients was published. We tested the applicability of the Japanese model in predicting 10- to 20-year risk of ESRD and all-cause mortality in a cohort of Norwegian IgAN patients.

METHODS

A cohort of IgAN patients (1988-2004) were identified in the Norwegian Kidney Biopsy Registry (NKBR) and ESRD or death during follow-up through 2008 was identified through record linkage with the Norwegian Renal Registry (ESRD) and the Norwegian Population Registry (deaths). Data from the NKBR were used to classify patients into nine different prognostic groups (0-1, 1-5, 5-10, 10-20, 20-30, 30-50, 50-70, 70-90 and >90% risk of ESRD) according to the Japanese prognostic model. The predicted risk was compared to the measured risk of ESRD in the different prognostic groups.

RESULTS

In eight of the nine risk groups, representing 597/633 (94%) of the patients in our cohort, the observed 10-year risk was within or close to the expected 10-year risk of ESRD. ESRD occurring after >10 years of observation was most frequent in the groups with 5-30% expected risk at 10 years of follow-up. A close association between risk of ESRD and risk of death prior to ESRD was observed.

CONCLUSIONS

The Japanese prognostic model is applicable to predict 10-year risk of ESRD in Norwegian IgAN patients. A new finding in the present study is that the model can also be used to predict which patients have the highest risk of developing ESRD after 10-20 years of follow-up as well as all-cause mortality risk.

Are adverse pregnancy outcomes risk factors for development of end-stage renal disease in women with diabetes?

BACKGROUND

It is unknown whether adverse pregnancy-related outcomes in women with pregestational diabetes are associated with later development of end-stage renal disease (ESRD) or death.

METHODS

We linked data from the Medical Birth Registry of Norway with data from the Norwegian Renal Registry and the Norwegian Cause of Death Registry. Data from up to three pregnancies for women with a first singleton delivery from 1967 to 1994 were included and analysed in a cohort design using Cox regression.

RESULTS

Altogether, 639,018 women were included in the analyses, among whom 2204 women had diabetes mellitus before pregnancy. Their first pregnancy was complicated by pre-eclampsia in 13.2%, low birth weight offspring (<2.5 kg) in 11.0% and preterm birth in 25.1%, and their risk of ESRD and death in the follow-up period of up to 37 years was markedly higher. In women with pregestational diabetes, pre-eclampsia and preterm birth were associated with significantly increased risks of ESRD and death in women with only one pregnancy, but not in women with two or more pregnancies.

CONCLUSIONS

In women with pregestational diabetes, pre-eclampsia and preterm birth were associated with long-term increased risk of ESRD and death, but only in women who had only one pregnancy.

Distribution and determinants of serum creatinine in the general population: the Hordaland Health Study

BACKGROUND

Serum creatinine is a well-recognized risk factor for cardiovascular disease (CVD) and is also a rough measure of glomerular filtration rate. The purpose of the present study was to investigate determinants of serum creatinine in the general population.

METHODS

The participants were recruited as a part of the Hordaland Health Study, and included 6952 men aged 41-49 years, 8218 women aged 41-49 years, 1470 men aged 71-74 years and 1865 women aged 71-74 years. Data on lifestyle factors, medical history and medication were obtained through questionnaires. Body size and blood pressure measurements as well as non-fasting blood samples were obtained during a health examination. Determinants of serum creatinine were identified using multiple linear and logistic regression analyses.

RESULTS

Male and older participants had higher levels of serum creatinine than female and middle-aged participants. For older participants, creatinine was associated with serum triglycerides, CVD, upper-arm circumference and use of antihypertensive drugs as well as inversely associated with cigarette smoking. For middle-aged participants, creatinine was associated with upper-arm circumference, serum lipids and physical exercise, as well as inversely associated with smoking and alcohol intake. The associations with CVD risk factors were much stronger for older participants than for middle-aged participants and most associations were significant after adjustments as well as present within the reference range of serum creatinine.

CONCLUSIONS

In this general population sample, high serum creatinine levels were associated with risk factors for CVD. These associations were stronger in older subjects, whereas in middle-aged subjects lifestyle variables were relatively more important.

Kidney function and future risk for adverse pregnancy outcomes: a population-based study from HUNT II, Norway

BACKGROUND

Current knowledge on prepregnancy reduced kidney function and the risk of adverse pregnancy outcomes mainly relies on small studies in selected populations. We aim to investigate whether reduced kidney function is associated with the risk of adverse pregnancy-related outcomes in the general population.

METHODS

A population-based study linking all women attending the Second Health Study in Nord-Trøndelag, Norway (1995-97) and subsequent pregnancies registered in the Medical Birth Registry. Multivariable random-effect logistic regression analysis was used to explore the association between renal function and study outcome.

RESULTS

The mean eGFR among 3405 women was 107.6 +/- 19.4 ml/min/1.73 m(2) at baseline; 18.8% and 0.1% had eGFR of 60-89 and <60, respectively. Over the next 11 years, they gave birth to 5655 singletons of whom 885 (17.7%) were complicated with preeclampsia, small for gestational age (SGA) or preterm birth. Women with eGFR 60-89 were not at increased risk for this combined outcome compared to women with eGFR > or =90, although women with eGFR 60-74 tended to have an increased risk. Neither was reduced kidney function a risk factor among women with microalbuminuria, but those with an eGFR of 60-89 plus hypertension had a significantly increased risk: odds ratios for preeclampsia, SGA or preterm birth were 2.58 (95% CI 1.40-4.75, P < 0.001) and 10.09 (95% CI 2.38-42.87, P < 0.001) in hypertensive women with eGFR 75-89 and 60-74, respectively. Relative excess risk due to interaction between reduced kidney function and hypertension was 2.23 (95% CI 1.35-3.10, P < 0.001). Women with a reduced kidney function were not at increased risk for other pregnancy complications like caesarean section, maternal bleeding, dystocia, pre-labour rupture of membranes, Apgar score < or =7, stillbirth or congenital malformations.

CONCLUSIONS

Women with eGFR 60-89 ml/min/1.73 m(2) were not at increased risk for preeclampsia, SGA or preterm birth unless they were also hypertensive.