Associations of Serum Uromodulin and Urinary Epidermal Growth Factor with Measured Glomerular Filtration Rate and Interstitial Fibrosis in Kidney Transplantation

INTRODUCTION

Noninvasive biomarkers that reflect tubular health and allow early recognition of accelerated graft fibrosis development are warranted. Serum uromodulin (sUmod) and urinary epidermal growth factor (uEGF) originate from kidney tubules and may reflect functional nephron mass. The aim of this study was to investigate the associations between sUmod and uEGF with measured glomerular filtration rate (mGFR) and kidney allograft interstitial fibrosis percentage (IF%) score.

METHODS

sUmod and uEGF measurements, mGFR by iohexol-clearance and kidney allograft biopsies were obtained from kidney transplant recipients (KTRs) included in the Omega-3 fatty acids in Renal Transplantation (ORENTRA) trial at 8 weeks (baseline) and at 1 year after transplantation (end of study). Associations were analyzed with univariable and multivariable linear regression.

RESULTS

Ninety patients at baseline and 48 patients at end of study had complete study variable assessments. uEGF normalized to urinary creatinine (uEGF/Cr) was associated with mGFR both at baseline (standardized β-coefficient [Std. β-coeff] = 0.457 [p = <0.001]) and at end of study (Std. β-coeff = 0.637 [p = <0.001]). sUmod was only associated with mGFR at end of study (Std. β-coeff = 0.443 [p = 0.002]). uEGF/Cr, sUmod, and mGFR were associated with graft IF% score both at baseline (Std. β-coeff = -0.349 [p = 0.001], -0.274 [p = 0.009] and -0.289 [p = 0.006], respectively) and at end of study (Std. β-coeff = -0.365 [p = 0.011], -0.347 [p = 0.016] and -0.405 [p = 0.004], respectively). The results remained largely unchanged in multivariable analysis.

CONCLUSION

uEGF/Cr and sUmod were associated with mGFR and graft IF% score. Our results indicate a possible role of uEGF/Cr and sUmod in the follow-up of KTRs.

Marine n-3 Polyunsaturated Fatty Acids and Cellular Senescence Markers in Incident Kidney Transplant Recipients: The Omega-3 Fatty Acids in Renal Transplantation (ORENTRA) Randomized Clinical Trial

Rationale & Objective

Deterioration of kidney graft function is associated with accelerated cellular senescence. Marine n-3 polyunsaturated fatty acids (PUFAs) have favorable properties that may counteract cellular senescence development and damage caused by the senescence-associated secretory phenotype (SASP) secretome. Our objective was to investigate the potential effects of marine n-3 PUFA supplementation on the SASP secretome in kidney transplant recipients.

Study Design

Exploratory substudy of the Omega-3 Fatty Acids in Renal Transplantation trial.

Setting & Participants

Adult kidney transplant recipients with a functional kidney graft (defined as having an estimated glomerular filtration rate of >30 mL/min/1.73 m²) 8 weeks after engraftment were included in this study conducted in Norway.

Analytical Approach

The intervention consisted of 2.6 g of a marine n-3 PUFA or olive oil (placebo) daily for 44 weeks. The outcome was a predefined panel of SASP components in the plasma and urine.

Results

A total of 132 patients were enrolled in the Omega-3 Fatty Acids in Renal Transplantation trial, and 66 patients were allocated to receive either the study drug or placebo. The intervention with the marine n-3 PUFA was associated with reduced plasma levels of granulocyte colony-stimulating factor, interleukin 1α, macrophage inflammatory protein 1α, matrix metalloproteinase (MMP)-1, and MMP-13 compared with the intervention in the control group.

Limitations

Post hoc analysis.

Conclusions

The results suggest that marine n-3 PUFA supplementation has mitigating effects on the plasma SASP components granulocyte colony-stimulating factor, interleukin 1α, macrophage inflammatory protein 1α, MMP-1, and MMP-13 in kidney transplant recipients. Future studies with kidney transplant recipients in maintenance phase, combined with an evaluation of cellular senescence markers in kidney transplant biopsies, are needed to further elucidate the potential antisenescent effect of marine n-3 PUFAs. This trial is registered as NCT01744067.

Marine n-3 Polyunsaturated Fatty Acid Supplementation and Quality of Life After Kidney Transplant

Marine n-3 polyunsaturated fatty acids (PUFAs) may improve cardiovascular, renal, and mental health. No previous trial has investigated the effects of marine n-3 PUFA supplementation on quality of life (QoL) indices after renal transplant.

METHODS

In this trial, 132 renal transplant recipients were randomized to receive daily either 2.6 g of marine n-3 PUFAs or an equivalent dose of olive oil (controls) on top of standard care for 44 weeks. We used a Short Form 36 (SF-36) questionnaire at baseline (8 weeks post transplant) and at the end of the study (1 year after transplant) to assess QoL. Results were expressed as net change (Δ) in SF-36 individual and composite mental and physical scores during follow-up.

RESULTS

We found no improvement of Δ SF-36 individual or composite scores after marine n-3 PUFA supplementation compared with controls. In per-protocol analysis, patients who received marine n-3 PUFAs had a Δ emotional role function (mean, 17% [SD, 50%] vs mean, 3% [SD, 37%]; P = .11). In addition, plasma marine n-3 PUFA levels showed a weak but statistically significant correlation with Δ composite mental function score (r = .18; P =  .04).

CONCLUSION

Marine n-3 PUFA supplementation did not improve QoL after renal transplant.

Effects of marine n-3 fatty acid supplementation in renal transplantation: A randomized controlled trial

Marine n-3 fatty acids (FAs) may exert beneficial effects on inflammation, fibrosis, and endothelial function, which could preserve renal graft function. In this randomized controlled trial, 132 Norwegian renal transplant recipients received either 2.6 g of marine n-3 FAs or olive oil (control) daily for 44 weeks, in addition to standard care. Thirty patients did not complete the trial. The primary endpoint was change (Δ) in measured glomerular filtration rate (mGFR) during follow-up. We found no significant difference in Δ mGFR between the marine n-3 FA group and controls (6.7 vs 3.8 mL/min per 1.73 m² , P = .15). Significant beneficial effects from marine n-3 FA supplementation were, however, seen in secondary endpoints plasma triglycerides, plasma high-sensitivity C-reactive protein, and brachial artery flow-mediated dilation. In the per-protocol population, the renal graft indices percent interstitial fibrosis and Chronic Allograft Damage Index also were significantly lower in the marine n-3 FA group. The cumulative incidence of adverse events did not differ between the marine n-3 FA group (n = 218) and controls (n = 240). In conclusion, marine FA supplementation did not improve renal function compared with controls, but was safe, lowered plasma triglyceride and high-sensitivity C-reactive protein levels, and improved endothelial function (Clinical.Trials.gov identifier NCT01744067).

Development of Kidney Transplant Fibrosis Is Inversely Associated With Plasma Marine Fatty Acid Level

OBJECTIVE(S)

We assessed associations between plasma levels of polyunsaturated fatty acids (PUFAs) and degree of inflammation and interstitial fibrosis in transplanted kidneys.

DESIGN

The design of the study was single center cohort study.

SUBJECTS

A study population of 156 patients who received a kidney transplant at Oslo University Hospital during 2010.

MAIN OUTCOME MEASURE

Kidney transplant biopsies were obtained at 2 months and 1 year after transplantation. Degree of inflammation and interstitial fibrosis in the cortex of transplanted kidneys were estimated semi-quantitatively. Plasma phospholipid fatty acids levels were measured in a stable phase 2 months posttransplant. We used multivariate linear regression to assess associations between plasma levels of PUFAs and degree of inflammation and interstitial fibrosis at 2 months and 1 year postoperatively and change in degree of interstitial fibrosis during the first year after transplantation, adjusting for inflammation and fibrosis risk factors.

RESULTS

Higher plasma marine n-3 PUFA levels were associated with less development of interstitial fibrosis in the kidney transplant (unstandardized β-coefficient -1.12, standardized β-coefficient -0.18, P = .03) during the first year after transplantation. Plasma levels of alpha linoleic acid, linoleic acid, and arachidonic acid were not associated with development of interstitial fibrosis. No associations were found between plasma levels of PUFAs and inflammation inside fibrotic areas or outside fibrotic areas in the kidney transplant at neither 2 months nor 1 year postoperatively. Linolenic acid levels in plasma were positively associated with change in renal function during the first year after transplantation.

CONCLUSION

The inverse association between plasma marine n-3 PUFA levels and development of interstitial fibrosis during the first year after kidney transplantation suggests that marine fatty acid consumption might halt progression of fibrosis.

Plasma Levels of Marine n-3 Fatty Acids Are Inversely Correlated With Proinflammatory Markers sTNFR1 and IL-6 in Renal Transplant Recipients

OBJECTIVE

Marine n-3 polyunsaturated fatty acids (PUFAs) exert potential anti-inflammatory effects and might improve long-term outcomes after renal transplantation. We assessed associations between plasma phospholipid levels of marine n-3 PUFAs and plasma inflammatory biomarkers 10 weeks after renal transplantation.

DESIGN

Cross-sectional single-center study.

SUBJECTS

A study population of 861 renal transplant recipients transplanted at Oslo University Hospital between 2007 and 2011.

METHODS AND MAIN OUTCOME MEASURE

Plasma phospholipid fatty acids were determined by gas chromatography. Marine n-3 PUFA levels were defined as the sum of eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid levels in weight percentage of total plasma phospholipid fatty acids. Plasma inflammatory biomarkers were measured by enzyme immunoassays. We used multivariable linear regression analysis to assess associations between levels of marine n-3 PUFAs and inflammatory biomarkers in plasma.

RESULTS

Plasma marine n-3 PUFA levels were inversely associated with plasma levels of proinflammatory biomarkers soluble tumor necrosis factor receptor 1 (standardized regression coefficient -0.11, P < .001) and interleukin-6 (standardized regression coefficient -0.09, P = .01). In contrast, there was no association between plasma levels of marine n-3 PUFAs and the anti-inflammatory mediator interleukin-10.

CONCLUSIONS

In this renal transplant cohort, inverse associations between plasma levels of marine n-3 PUFAs and markers of inflammation were demonstrated.

Plasma levels of marine n-3 polyunsaturated fatty acids and renal allograft survival

BACKGROUND

Marine n-3 polyunsaturated fatty acids (PUFAs) may exert beneficial effects on inflammation, fibrosis, endothelial function, lipid profile and blood pressure that may prevent graft loss.

METHODS

In this observational cohort study in Norwegian renal transplant recipients (n = 1990), transplanted between 1999 and 2011, associations between plasma marine n-3 PUFA levels and graft loss were assessed by multivariable Cox proportional hazard regression analysis. Plasma phospholipid fatty acid composition was determined by gas chromatography and individual fatty acids recorded as weight percentage (wt%) of total fatty acids in a stable phase 10 weeks after transplantation.

RESULTS

During a median follow-up time of 6.8 years, 569 (28.6%) renal allografts were lost, either due to patient death (n = 340, 59.8% of graft loss) or graft loss in surviving patients (n = 229, 40.2%). Plasma marine n-3 PUFA levels ranged from 1.35 to 23.87 wt%, with a median level of 7.95 wt% (interquartile range 6.20-10.03 wt%). When adjusting for established graft loss risk factors, there was a 11% reduced risk of graft loss for every 1.0 wt% increase in marine n-3 PUFA level [adjusted hazard ratio (HR) 0.89; 95% confidence interval (CI) 0.84-0.93], and a 10% reduced risk of graft loss in surviving patients (adjusted HR 0.90; 95% CI 0.84-0.97).

CONCLUSION

High levels of plasma marine n-3 PUFAs were associated with better renal allograft survival.

The association between marine n-3 polyunsaturated fatty acid levels and survival after renal transplantation

BACKGROUND AND OBJECTIVES

Several studies have reported beneficial cardiovascular effects of marine n-3 polyunsaturated fatty acids. To date, no large studies have investigated the potential benefits of marine n-3 polyunsaturated fatty acids in recipients of renal transplants.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this observational cohort study of 1990 Norwegian recipients of renal transplants transplanted between 1999 and 2011, associations between marine n-3 polyunsaturated fatty acid levels and mortality were investigated by stratified analysis and multivariable Cox proportional hazard regression analysis adjusting for traditional and transplant-specific mortality risk factors. Marine n-3 polyunsaturated fatty acid levels in plasma phospholipids were measured by gas chromatography in a stable phase 10 weeks after transplantation.

RESULTS

There were 406 deaths (20.4%) during a median follow-up period of 6.8 years. Mortality rates were lower in patients with high marine n-3 polyunsaturated fatty acid levels (≥7.95 weight percentage) compared with low levels (<7.95 weight percentage) for all age categories (pooled mortality rate ratio estimate, 0.69; 95% confidence interval, 0.57 to 0.85). When divided into quartiles according to marine n-3 polyunsaturated fatty acid levels, patients in the upper quartile compared with the lower quartile had a 56% lower risk of death (adjusted hazard ratio, 0.44; 95% confidence interval, 0.26 to 0.75) using multivariable Cox proportional hazard regression analysis. There was a lower hazard ratio for death from cardiovascular disease with high levels of marine n-3 polyunsaturated fatty acid and a lower hazard ratio for death from infectious disease with high levels of the marine n-3 polyunsaturated fatty acid eicosapentaenoic acid, whereas there was no association between total or individual marine n-3 polyunsaturated fatty acid levels and cancer mortality.

CONCLUSIONS

Higher plasma phospholipid marine n-3 polyunsaturated fatty acid levels were independently associated with better patient survival.

In patients with type 1 diabetes simultaneous pancreas and kidney transplantation preserves long-term kidney graft ultrastructure and function better than transplantation of kidney alone

AIMS/HYPOTHESIS

In patients with type 1 diabetes and end-stage renal disease (ESRD) we aimed to determine whether long-term normoglycaemia, as achieved by successful simultaneous pancreas and kidney (SPK) transplantation, would preserve kidney graft structure and function better than live donor kidney (LDK) transplantation alone.

METHODS

Estimated GFR (eGFR) was calculated in SPK (n = 25) and LDK (n = 17) recipients in a stable phase 3 months after transplantation and annually during follow-up. Kidney graft biopsies were obtained at follow-up for measurement of glomerular volume (light microscopy), glomerular basement membrane (GBM) and podocyte foot process widths and mesangial volume fraction (electron microscopy).

RESULTS

SPK and LDK recipients were similar in age and diabetes duration at engraftment. Donor age was higher in the LDK group. Median follow-up time was 10.1 years. Mean HbA1c levels during follow-up were 5.5 ± 0.4% (37 ± 5 mmol/mol) and 8.3 ± 1.5% (68 ± 16 mmol/mol) in the SPK and LDK group, respectively (p < 0.001). Compared with SPK recipients, LDK recipients had wider GBM (369 ± 109 nm vs 281 ± 57 nm; p = 0.008) and increased mesangial volume fraction (median 0.23 [range 0.13-0.59] vs 0.16 [0.10-0.41]; p = 0.007) at follow-up. Absolute eGFR change from baseline was -11 ± 21 and -23 ± 15 ml min(-1) 1.73 m(-2) (p = 0.060), whereas eGFR slope was -1.1 (95% CI -1.7, -0.5) and -2.6 (95% CI -3.1, -2.1) ml min(-1) 1.73 m(-2) per year in the SPK and LDK group, respectively (p = 0.001).

CONCLUSIONS/INTERPRETATION

In patients with type 1 diabetes and long-term normoglycaemia after successful SPK transplantation, kidney graft ultrastructure and function were better preserved compared with LDK transplantation alone.

[Urinary problems and prostate-specific antigen in a Norwegian normal population]

BACKGROUND

Measurements of PSA in serum is crucial in the diagnostic work-up of prostatic diseases.

MATERIAL AND METHODS

We have studied the distribution of PSA values in an unselected population of 609 men, and the relation between PSA level and urinary symptoms, age and prostate volume.

RESULTS

87 (14%) men had a PSA concentration at or above the reference value of 4.0 ng/ml. Prostate cancer was verified in 14 (16%) of these men. The probability of having PSA equal to or above 4.0 ng/ml was 12 times greater for men with a prostate volume of 40 cm3 or less than for men with a prostate volume less than 20 cm3. Mean PSA values were higher in men with severe than with mild urinary symptoms, but symptoms were poor predictors of PSA levels. Age was not associated with an increase in PSA level independent of prostate volume.

INTERPRETATION

Absence of urinary symptoms does not exclude elevated PSA values and thus not cancer. Most men with PSA equal to or above 10.0 ng/ml will have prostate cancer, but enlarged prostate without cancer can also give elevated PSA values.

[Prostate-specific antigen]

BACKGROUND

Serum PSA has been commercially available for more than ten years, and has proved to be the most important tumour marker for prostate cancer. We review the clinical usefulness and limitations of serum PSA as a tumour marker of prostate cancer.

MATERIAL AND METHODS

The international literature and medical databases were searched for studies on the contributions and limitations of PSA in clinical practice.

RESULTS

Serum PSA > or = 4.0 ng/ml is commonly regarded as elevated, and give rise suspicion of prostate cancer. However, only one out of four men with serum PSA level between 4.0 ng/ml and 10.0 ng/ml has prostate cancer. The most common cause of elevated serum PSA value in this group is benign prostatic hyperplasia. In an attempt to increase the sensitivity as well as the specificity for serum PSA in the detection of prostate cancer, the serum PSA level has been combined with age of patients (age-specific serum PSA), time (PSA velocity), prostate volume (PSA density), different molecular PSA forms, like per cent of free PSA. Some of these new methods have shown promising results.

INTERPRETATION

PSA is the best and most widely used tumour marker in urology. However, it is important that clinicians know the limitations of this marker.