Design, validation and implementation of an automated e-alert for acute kidney injury: 6-month pilot study shows increased awareness

BACKGROUND

Acute kidney injury (AKI) is defined as a sudden episode of kidney failure but is known to be under-recognized by healthcare professionals. The Kidney Disease Improving Global Outcome (KDIGO) guidelines have formulated criteria to facilitate AKI diagnosis by comparing changes in plasma creatinine measurements (PCr). To improve AKI awareness, we implemented these criteria as an electronic alert (e-alert), in our electronic health record (EHR) system.

METHODS

For every new PCr measurement measured in the University Medical Center Utrecht that triggered the e-alert, we provided the physician with actionable insights in the form of a memo, to improve or stabilize kidney function. Since e-alerts qualify for software as a medical device (SaMD), we designed, implemented and validated the e-alert according to the European Union In Vitro Diagnostic Regulation (IVDR).

RESULTS

We evaluated the impact of the e-alert using pilot data six months before and after implementation. 2,053 e-alerts of 866 patients were triggered in the before implementation, and 1,970 e-alerts of 853 patients were triggered after implementation. We found improvements in AKI awareness as measured by (1) 2 days PCr follow up (56.6-65.8%, p-value: 0.003), and (2) stop of nephrotoxic medication within 7 days of the e-alert (59.2-63.2%, p-value: 0.002).

CONCLUSION

Here, we describe the design and implementation of the e-alert in line with the IVDR, leveraging a multi-disciplinary team consisting of physicians, clinical chemists, data managers and data scientists, and share our firsts results that indicate an improved awareness among treating physicians.

Migration background and COVID-19 related intensive care unit admission and mortality in the Netherlands: A cohort study

BACKGROUND

Since the beginning of the SARS-CoV-2 pandemic, studies have been reporting inconsistently on migration background as a risk factor for COVID-19 outcomes. The aim of this study was to evaluate the association between migration background and clinical outcomes with COVID-19 in the Netherlands.

METHODS

This cohort study included 2,229 adult COVID-19 patients admitted in two Dutch hospitals between February 27, 2020 and March 31, 2021. Odds ratios (ORs) for hospital admission, intensive care unit (ICU) admission and mortality with 95% confidence intervals (CIs) were calculated for non-Western (Moroccan, Turkish, Surinamese or other) persons as compared with Western persons in the general population of the province of Utrecht (the Netherlands) as source population. Furthermore, among hospitalized patients, Hazard ratios (HRs) with 95% CIs for in-hospital mortality and intensive care unit (ICU) admission were calculated using Cox proportional hazard analyses. Hazard ratios were adjusted for age, sex, body mass index, hypertension, Charlson Comorbidity Index, chronic corticosteroid use before admission, income, education and population density to investigate explanatory variables.

RESULTS

Of the 2,229 subjects, 1,707 were of Western origin and 522 were of non-Western origin. There were 313 in-hospital deaths and 503 ICU admissions. As compared with persons with a Western origin in the general population of the province of Utrecht, the ORs for non-Western persons was 1.8 (95% CI 1.7-2.0) for hospitalization, 2.1 (95% CI 1.7-2.5) for ICU admission and 1.3 (95% CI 1.0-1.7) for mortality. Among hospitalized patients, HR for ICU admission was 1.1 (95% CI 0.9-1.4) and 0.9 (95% CI 0.7-1.3) for mortality for non-Western hospitalized persons as compared with hospitalized patients of Western origin after adjustment.

CONCLUSION

Non-Western persons, including Moroccan, Turkish and Surinamese subjects, had increased risks of hospital admission, ICU admission and COVID-19 related death on a population level. Among hospitalized COVID-19 patients, no association was found between migration background and ICU admission or mortality.

MO313: Haematological Ratios as Risk Factor for Acute Kidney Injury in Patients Suspected of an Infection at the Emergency Department

BACKGROUND AND AIMS

Evidence exists that inflammation plays an important role in the pathogenesis of acute kidney injury (AKI) in sepsis patients. Haematological ratios can be used to measure systemic and silent inflammation. Therefore, we investigated what haematological ratios could be identified as risk factors to predict AKI < 30 days in patients suspected of infection at the emergency department (ED).

METHOD

Data from the SPACE-cohort (SePsis in the Acutely ill patients in the ED) were used. This cohort consists of all patients ≥ 18 years, that present at the ED of the UMC Utrecht for the internal medicine with suspicion of infection. AKI was defined based on the KDIGO criteria. Haematological markers were determined with the Abbott Cell-DYN Sapphire haematology analyser. In total, 7 haematological ratios were included. A Cox regression was performed after the ratios were divided into tertiles. Consequently, Kaplan–Meier curves for 30-day mortality were constructed for the significant predictors from the Cox analysis.

RESULTS

In univariate Cox regression, neutrophil-to-lymphocyte ratio (NLR), segmented neutrophil-to-monocyte ratio (SeMo) and neutrophil-to-lymphocyte-and-platelet ratio (NLPR) were all significant risk factors for the occurrence of AKI < 30 days after ED presentation (Fig. 1). After correction for multiple confounders, NLR, SeMo and NLPR remained significant. There were significant differences in survival for all these three ratios (Fig. 2).

CONCLUSION

In this study, we show that several haematological ratios are risk factors for AKI and mortality in patients suspected of infection at the ED. Using these risk factors in prediction models might enable ED physicians to treat AKI in an early phase and prevent any short- and long-term complications. A limitation of this study is the retrospective character. Because of this, not all patients in the cohort had follow-up creatinine levels, and the occurrence of AKI could not be determined in these patients.

Chronic kidney disease and atrial fibrillation: A dangerous combination

Background

Chronic kidney disease (CKD) and atrial fibrillation (AF) are both risk factors for bleeding, stroke and mortality. The aim of our study was to investigate the interaction between CKD and atrial fibrillation and outcomes.

Methods

We included 12,394 subjects referred to the University Medical Center Utrecht (the Netherlands) from September 1996 to February 2018 for an out-patient visit (Utrecht Cardiovascular Cohort Second Manifestation of Arterial disease cohort). Hazard ratios (HRs) with 95% confidence intervals (CIs) for bleeding, ischemic stroke or mortality were calculated with Cox proportional hazard analyses. Presence of interaction between AF and CKD was examined by calculating the relative excess risk due to interaction (RERI), the attributable proportion (AP) due to interaction and the synergy index (S).

Results

Of the 12,394 patients, 699 patients had AF, 2,752 patients had CKD and 325 patients had both AF and CKD. Patients with both CKD and AF had a 3.0-fold (95% CI 2.0–4.4) increased risk for bleeding, a 4.2-fold (95% CI 3.0–6.0) increased ischemic stroke risk and a 2.2-fold (95% CI 1.9–2.6) increased mortality risk after adjustment as compared with subjects without atrial fibrillation and CKD. We did not find interaction between AF and CKD for bleeding and mortality. However, we found interaction between AF and CKD for ischemic stroke risk (RERI 1.88 (95% CI 0.31–3.46), AP 0.45 (95% CI 0.17–0.72) and S 2.40 (95% CI 1.08–5.32)).

Conclusion

AF and CKD are both associated with bleeding, ischemic stroke and mortality. There is a positive interaction between AF and CKD for ischemic stroke risk, but not for bleeding or mortality.

Ambiguous definitions for baseline serum creatinine affect acute kidney diagnosis at the emergency department

Background

Acute kidney injury (AKI) incidence is increasing, however AKI is often missed at the emergency department (ED). AKI diagnosis depends on changes in kidney function by comparing a serum creatinine (SCr) measurement to a baseline value. However, it remains unclear to what extent different baseline values may affect AKI diagnosis at ED.

Methods

Routine care data from ED visits between 2012 and 2019 were extracted from the Utrecht Patient Oriented Database. We evaluated baseline definitions with criteria from the RIFLE, AKIN and KDIGO guidelines. We evaluated four baseline SCr definitions (lowest, most recent, mean, median), as well as five different time windows (up to 365 days prior to ED visit) to select a baseline and compared this to the first measured SCr at ED. As an outcome, we assessed AKI prevalence at ED.

Results

We included 47,373 ED visits with both SCr-ED and SCr-BL available. Of these, 46,100 visits had a SCr-BL from the − 365/− 7 days time window. Apart from the lowest value, AKI prevalence remained similar for the other definitions when varying the time window. The lowest value with the − 365/− 7 time window resulted in the highest prevalence (21.4%). Importantly, applying the guidelines with all criteria resulted in major differences in prevalence ranging from 5.9 to 24.0%.

Conclusions

AKI prevalence varies with the use of different baseline definitions in ED patients. Clinicians, as well as researchers and developers of automatic diagnostic tools should take these considerations into account when aiming to diagnose AKI in clinical and research settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02581-x.

Immune checkpoint inhibitor-associated acute kidney injury and mortality: An observational study

BACKGROUND

Immune checkpoint inhibitors, approved for the treatment of various types of cancer, are known to cause a unique spectrum of side effects, including acute kidney injury (AKI). The aim of this study was to describe the incidence, risk factors, renal outcomes, and mortality of AKI in patients receiving checkpoint inhibitors.

METHODS

Patients receiving checkpoint inhibitors between January 2013 and May 2020 at the University Medical Center Utrecht, the Netherlands, were identified using the Utrecht Patient Oriented Database. AKI was defined as an increase in serum creatinine of ≥1.5 times the baseline value, based on the Kidney Disease: Improving Global Outcomes criteria. Cox proportional hazard regression analysis was used to assess risk factors for AKI and to evaluate the relationship between AKI and mortality. Persistent renal dysfunction was diagnosed in AKI patients with a final serum creatinine measurement of >1.3 times the baseline value.

RESULTS

Among 676 patients receiving checkpoint inhibitors, the overall incidence of AKI was 14.2%. Baseline variables independently associated with AKI were a gynecologic malignancy, monotherapy with ipilimumab, and the use of a diuretic, angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker, or proton pump inhibitor at baseline. AKI was checkpoint inhibitor-associated in one third of all patients with AKI. Checkpoint inhibitor-associated AKI was mostly low-grade, occurred a median of 15 weeks after checkpoint inhibitor initiation, and resulted in persistent renal dysfunction in approximately 40% of the patients. Patients with all-cause AKI had a twofold increased mortality risk, but checkpoint inhibitor-associated AKI was not associated with increased mortality.

CONCLUSIONS

In this study, patients receiving checkpoint inhibitors frequently developed AKI due to various etiologies. AKI directly related to the effect of checkpoint inhibitor toxicity did not increase mortality. However, AKI not related to the effect of checkpoint inhibitor toxicity was associated with increased mortality.

MO356THE INCIDENCE, MORTALITY AND RENAL OUTCOMES OF ACUTE KIDNEY INJURY IN PATIENTS WITH SUSPECTED INFECTION AT THE EMERGENCY DEPARTMENT

Background and Aims

Acute kidney injury (AKI) is a major health problem associated with considerable mortality and morbidity. The epidemiology of AKI in hospitalized and critically ill patients at the Intensive Care Unit with severe infection and sepsis has been well described, however data on mortality and clinical outcomes of AKI at the emergency department in patients with suspected infection are scarce. In this study, we investigated the incidence, mortality and renal outcomes after AKI up to one year after initial AKI-episode patients with suspected infection at the emergency department.

Method

We used data from the SPACE-cohort (SePsis in the ACutely ill patients in the Emergency department), which consisted of all consecutive patients that presented to the emergency department of the internal medicine with suspected infection in the period between 2016 and 2018 at the University Medical Center Utrecht. Clinical and laboratory data were prospectively collected of all patients. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria. Outcomes were 1-year all-cause mortality and renal function. Hazards ratios were assessed using Cox regression to investigate the association between AKI, 1-year mortality and renal function decline after AKI. HRs were adjusted for potential confounders including age, gender, Charlson Comorbidity Index, immune status, smoking status, medication use (diuretics, proton-pump inhibitors, non-steroidal anti-inflammatory drugs (NSAIDs) and angiotensin converting enzyme inhibitors (ACEi)), disease severity, diagnosis in the emergency department. Decline of renal function after AKI episode at emergency department visit was defined as Serum Creatinine (SCr) level ≥30% above baseline. Survival in patients with and without AKI was assessed using Kaplan-Meier analyses.

Results

Of the 3105 patients in the SPACE-cohort with suspected infection, we included 1716, who fulfilled the inclusion criteria and had a baseline SCr measurement. Patients without SCr at baseline (401 patients), at emergence department visit (113 patients), during follow-up (33 patients), on renal replacement therapy (66 patients) or had a repeated emergency department visit (776 patients) were excluded. Of the 1716 patients presenting with suspected infection patients (median age 62y, 52.9% male), 185 patients (10.8%) had an AKI episode. Mortality was 23.8% for the AKI group and 20.4% for the non-AKI group. The adjusted HR for all-cause mortality at 1-year after presentation at the emergency department in AKI patients was 2.1 (95% CI 1.5 – 3.1). Moreover, the cumulative incidence of renal function decline was 69.8% for patients with AKI and 39.3% for patients without AKI. Patients with an episode of AKI had higher risks of developing renal function decline (adjusted HR 3.3, 95% CI 2.4-4.5) at one year after initial AKI-episode at the emergency department.

Conclusion

Acute kidney injury is common in patients with suspected infection in the emergency department and is significantly associated with mortality and renal function decline one year after AKI.

MO363CHECKPOINT-INHIBITOR-ASSOCIATED ACUTE KIDNEY INJURY AND MORTALITY: AN OBSERVATIONAL STUDY

Background and Aims

Immune checkpoint inhibitors, approved for the treatment of various types of cancer, are known to cause a unique spectrum of autoimmune-related side effects, including acute kidney injury (AKI). The aim of this study was to describe the incidence, risk factors, renal outcomes, and mortality of AKI in patients receiving checkpoint inhibitors.

Method

Patients receiving checkpoint inhibitors between January 2013 and May 2020 were identified using the Utrecht Patient Oriented Database. AKI was defined as an increase in creatinine of ≥1.5 times the baseline value. Cox proportional hazard regression analysis was used to assess risk factors for AKI and to evaluate the relationship between AKI and mortality. Persistent kidney injury was diagnosed in AKI patients with a final creatinine measurement of >1.3 times the baseline value.

Results

Out of 676 patients receiving checkpoint inhibitors, AKI occurred in 96 (14.2%) patients. Chart review showed that AKI was checkpoint inhibitor-associated in 32 (4.7%) patients. Baseline variables associated with AKI were a primary gynecological malignancy (HR 3.91, 95% CI 1.55 to 9.85), treatment with checkpoint inhibitor ipilimumab (HR 2.31, 95% CI 1.03 to 5.20), and pre-existent use of a diuretic (HR 2.61, 95% CI 1.21 to 5.60), an angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker (HR 2.49, 95% CI 1.10 to 5.60), and a proton pump inhibitor (HR 1.69, 95% CI 1.04 to 2.75). In 35.4% of the patients who had developed AKI, persistent kidney dysfunction was observed at the end of follow-up. Patients who developed AKI had a 2.13-fold (95% CI 1.58 to 2.87) increased mortality risk compared to patients who did not develop AKI. Mortality risk was not increased by checkpoint inhibitor-associated AKI (HR 1.11, 95% CI 0.64 to 1.92), but only by AKI related to other causes (HR 2.87, 95% CI 2.04 to 4.04).

Conclusion

Patients receiving checkpoint inhibitors frequently develop AKI, however, checkpoint inhibitor-associated AKI does not seem to increase mortality.

FC 069

Background and Aims

Chronic kidney disease (CKD) and atrial fibrillation (AF) are both risk factors for bleeding, stroke and mortality. Whether the combination of CKD and AF leads to higher risks of bleeding, stroke and mortality than CKD or AF alone is not known. The aim of our study was to investigate the interaction between CKD and AF and outcomes.

Method

We included 12,394 subjects referred to the University Medical Center Utrecht (the Netherlands) from September 1996 to February 2018f for an out-patient visit with classical risk factors for arterial disease or with symptomatic arterial disease (Utrecht Cardiovascular Cohort Second Manifestation of Arterial disease (UCC-SMART) cohort). Hazard ratios (HRs) with 95% confidence intervals (CIs) for bleeding, ischemic stroke or mortality were calculated with Cox proportional hazards analyses. Presence of additive interaction between AF and CKD was examined by calculating the relative excess risk due to interaction (RERI), the attributable proportion (AP) due to interaction and the synergy index (S).

Results

Of the 12,394 patients, 699 patients had AF, 2,752 patients had CKD and 325 patients had both AF and CKD. Overall, 382 patients developed a first bleeding event, 421 patients had a first ischemic stroke and 2203 patients died. Patients with both CKD and AF had a 3.0-fold (95% CI 2.0-4.4) increased risk for bleeding, a 4.2-fold (95% CI 3.0-6.0) increased ischemic stroke risk and a 2.2-fold (95% CI 1.9-2.6) increased mortality risk after adjustment as compared with subjects without AF and CKD (Table 1). Although bleeding and mortality risks were highest for the combination of AF and CKD, we did not find interaction between AF and CKD. However, we found an interaction between AF and CKD for ischemic stroke risk (RERI 1.88 (95% CI 0.31-3.46), AP 0.45 (95% CI 0.17-0.72) and S 2.40 (95% CI 1.08-5.32)) (Table 1).

Conclusion

The combination of CKD and AF is associated with high risks for bleeding, ischemic stroke and mortality. There is a positive interaction between AF and CKD for ischemic stroke risk, but not for bleeding or mortality.

Dosage reduction of low weight heparin in patients with renal dysfunction: Effects on anti-Xa levels and clinical outcomes

Background

To prevent bio-accumulation of low molecular weight heparins (LMWHs) in patients with decreased kidney function, dosage reduction and anti-Xa monitoring has been suggested. The aim of this study was to investigate the effect of pre-emptive dosage reduction of LMWH on anti-Xa levels. Furthermore, we investigated the association between anti-Xa levels and bleeding, thrombotic events and mortality.

Methods

In this single center study, we followed 499 patients with decreased renal function in whom anti-Xa levels were measured. We observed how many patients had anti-Xa levels that fell within the reference range, with a standard protocol of a pre-emptive dosage reduction of LMWH (25% reduction in patients with an estimated glomerular filtration rate (eGFR) between 30 and 60 ml/min/1.73m² and a reduction of 50% in patients with an eGFR below the 30 ml/min/1.73m²). Furthermore, Cox proportional hazard analyses were used to estimate hazard ratios to investigate the association between anti-Xa levels and major bleeding, thrombotic events and mortality within three months of follow-up.

Results

In a cohort of 499 patients (445 dalteparin and 54 nadroparin users), a pre-emptive dosage reduction of LMWH led to adequate levels of anti-Xa in only 19% of the patients (12% for the dalteparin users and 50% for nadroparin users). We did not find an association between anti-Xa levels and bleeding, thrombosis or mortality.

Conclusion

Pre-emptive dosage reduction of LMWH leads to low anti-Xa levels in a large proportion, but this was not associated with bleeding, thrombosis or mortality.

P0810DOSAGE REDUCTION OF LOW MOLECULAR WEIGHT HEPARIN IN PATIENTS WITH RENAL DYSFUNCTION: EFFECTS ON ANTI-XA LEVELS AND CLINICAL OUTCOMES

Background and Aims

To prevent bio-accumulation of low molecular weight heparins (LMWHs) in patients with an impaired kidney function, guidelines recommend dosage reduction and anti-Xa monitoring. The aim of this study was to investigate the effect of pre-emptive dosage reduction of LMWH on anti-Xa levels. Furthermore, we investigated the association between anti-Xa levels and bleeding, thrombotic events and mortality.

Method

In this single center study, we followed 499 patients with an estimated glomerular filtration rate (eGFR) below 60 ml/min/1.73m2 in whom anti-Xa levels were measured. We observed how many patients had anti-Xa levels that fell within the target range (between 1.0 U/ml and 2.0 U/ml with once daily LMWH and between 0.6 U/ml and 1.0 U/ml with twice daily LMWH), with a standard protocol of a pre-emptive dosage reduction of LMWH (25% reduction in patients with an eGFR between 30 and 60 ml/min/1.73m2 and a reduction of 50% in in patients with an eGFR below the 30 ml/min/1.73m2).

Furthermore, Cox proportional hazard analyses were used to estimate hazard ratios with 95% confidence intervals (CIs) to investigate the association between anti-Xa levels and major bleeding, thrombotic events (ischemic stroke or venous thrombosis) and mortality within three months of follow-up. Hazard ratios were adjusted for age, sex, body mass index, type of LMWH, once or twice daily dosing, antiplatelet drug use, indication for anticoagulation, comorbidities, hemoglobin concentration and eGFR.

Results

In a cohort of 499 patients (445 dalteparin and 54 nadroparin users), the median anti-Xa level was 0.44 U/ml (IQR 0.21-0.75) for the total group (n=499). A pre-emptive dosage reduction of LMWH led to adequate levels of anti-Xa in only 19% of the patients (12% for the dalteparin users and 50% for nadroparin users).

Of the 499 patients, 104 patients had a major bleeding, 27 had a thrombotic event and 146 died within three months. We did not find an association between anti-Xa levels and bleeding or mortality (Table 1). An anti-Xa level below the target range was associated with a non-significant increased risk estimate for thrombosis (HR 2.5, 95% CI 0.7-8.8) after adjustment (Table 1).

Conclusion

Pre-emptive dosage reduction of LMWH leads to low anti-Xa levels in a large proportion of patients and may lead to an undertreatment of patients with an impaired kidney function.

Case series of three adult patients with exceptional clinical presentations of haemophagocytic lymphohistiocytosis

Macrophage activation syndrome (MAS) is a secondary form of haemophagocytic lymphohistiocytosis (HLH). MAS-HLH is an underrecognised and life-threatening condition associated with a heterogeneous group of diseases including connective tissue disease and inflammatory disorders. Here, we report three cases of adult patients with MAS-HLH triggered by different entities, including systemic lupus erythematosus, Griscelli syndrome type 2, and Adult onset Still's disease.

Simultaneous pancreas-kidney transplantation in patients with type 1 diabetes reverses elevated MBL levels in association with MBL2 genotype and VEGF expression

AIMS/HYPOTHESIS

High levels of circulating mannan-binding lectin (MBL) are associated with the development of diabetic nephropathy and hyperglycaemia-induced vasculopathy. Here, we aimed to assess the effect of glycaemic control on circulating levels of MBL and the relationship of these levels with vascular damage.

METHODS

We assessed MBL levels and corresponding MBL2 genotype, together with vascular endothelial growth factor (VEGF) levels as a marker of vascular damage, in type 1 diabetes patients with diabetic nephropathy before and after simultaneous pancreas-kidney (SPK) transplantation. We included diabetic nephropathy patients (n = 21), SPK patients (n = 37), healthy controls (n = 19), type 1 diabetes patients (n = 15) and diabetic nephropathy patients receiving only a kidney transplant (n = 15). Fourteen diabetic nephropathy patients were followed up for 12 months after SPK.

RESULTS

We found elevated circulating MBL levels in diabetic nephropathy patients, and a trend towards elevated circulating MBL levels in type 1 diabetes patients, compared with healthy control individuals. MBL levels in SPK patients completely normalised and our data indicate that this predominantly occurs in patients with a polymorphism in the MBL2 gene. By contrast, MBL levels in kidney transplant only patients remained elevated, suggesting that glycaemic control but not reversal of renal failure is associated with decreased MBL levels. In line, levels of glucose and HbA1c, but not creatinine levels and estimated GFR, were correlated with MBL levels. VEGF levels were associated with levels of MBL and HbA1c in an MBL-polymorphism-dependent manner.

CONCLUSIONS/INTERPRETATION

Taken together, circulating MBL levels are associated with diabetic nephropathy and are dependent on glycaemic control, possibly in an MBL2-genotype-dependent manner.

Circulating microRNAs associate with diabetic nephropathy and systemic microvascular damage and normalize after simultaneous pancreas-kidney transplantation

Because microvascular disease is one of the most important drivers of diabetic complications, early monitoring of microvascular integrity may be of clinical value. By assessing profiles of circulating microRNAs (miRNAs), known regulators of microvascular pathophysiology, in healthy controls and diabetic nephropathy (DN) patients before and after simultaneous pancreas-kidney transplantation (SPK), we aimed to identify differentially expressed miRNAs that associate with microvascular impairment. Following a pilot study, we selected 13 candidate miRNAs and determined their circulating levels in DN (n = 21), SPK-patients (n = 37), healthy controls (n = 19), type 1 diabetes mellitus patients (n = 15) and DN patients with a kidney transplant (n = 15). For validation of selected miRNAs, 14 DN patients were studied longitudinally up to 12 months after SPK. We demonstrated a direct association of miR-25, -27a, -126, -130b, -132, -152, -181a, -223, -320, -326, -340, -574-3p and -660 with DN. Of those, miR-25, -27a, -130b, -132, -152, -320, -326, -340, -574-3p and -660 normalized after SPK. Importantly, circulating levels of some of these miRNAs tightly associate with microvascular impairment as they relate to aberrant capillary tortuosity, angiopoietin-2/angiopoietin-1 ratios, circulating levels of soluble-thrombomodulin and insulin-like growth factor. Taken together, circulating miRNA profiles associate with DN and systemic microvascular damage, and might serve to identify individuals at risk of experiencing microvascular complications, as well as give insight into underlying pathologies.

Hematopoietic microRNA-126 protects against renal ischemia/reperfusion injury by promoting vascular integrity

Ischemia/reperfusion injury (IRI) is a central phenomenon in kidney transplantation and AKI. Integrity of the renal peritubular capillary network is an important limiting factor in the recovery from IRI. MicroRNA-126 (miR-126) facilitates vascular regeneration by functioning as an angiomiR and by modulating mobilization of hematopoietic stem/progenitor cells. We hypothesized that overexpression of miR-126 in the hematopoietic compartment could protect the kidney against IRI via preservation of microvascular integrity. Here, we demonstrate that hematopoietic overexpression of miR-126 increases neovascularization of subcutaneously implanted Matrigel plugs in mice. After renal IRI, mice overexpressing miR-126 displayed a marked decrease in urea levels, weight loss, fibrotic markers, and injury markers (such as kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin). This protective effect was associated with a higher density of the peritubular capillary network in the corticomedullary junction and increased numbers of bone marrow-derived endothelial cells. Hematopoietic overexpression of miR-126 increased the number of circulating Lin(-)/Sca-1(+)/cKit(+) hematopoietic stem and progenitor cells. Additionally, miR-126 overexpression attenuated expression of the chemokine receptor CXCR4 on Lin(-)/Sca-1(+)/cKit(+) cells in the bone marrow and increased renal expression of its ligand stromal cell-derived factor 1, thus favoring mobilization of Lin(-)/Sca-1(+)/cKit(+) cells toward the kidney. Taken together, these results suggest overexpression of miR-126 in the hematopoietic compartment is associated with stromal cell-derived factor 1/CXCR4-dependent vasculogenic progenitor cell mobilization and promotes vascular integrity and supports recovery of the kidney after IRI.

Association of kidney function with changes in the endothelial surface layer

BACKGROUND AND OBJECTIVES

ESRD is accompanied by endothelial dysfunction. Because the endothelial glycocalyx (endothelial surface layer) governs interactions between flowing blood and the vessel wall, perturbation could influence disease progression. This study used a novel noninvasive sidestream-darkfield imaging method, which measures the accessibility of red blood cells to the endothelial surface layer in the microcirculation (perfused boundary region), to investigate whether renal function is associated with endothelial surface layer dimensions.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Perfused boundary region was measured in control participants (n=10), patients with ESRD (n=23), participants with normal kidney function after successful living donor kidney transplantation (n=12), and patients who developed interstitial fibrosis/tubular atrophy after kidney transplantation (n=10). In addition, the endothelial activation marker angiopoietin-2 and shed endothelial surface layer components syndecan-1 and soluble thrombomodulin were measured using ELISA.

RESULTS

Compared with healthy controls (1.82 ± 0.16 µm), ESRD patients had a larger perfused boundary region (+0.23; 95% confidence interval, 0.46 to <0.01; P<0.05), which signifies loss of endothelial surface layer dimensions. This large perfused boundary region was accompanied by higher circulating levels of syndecan-1 (+57.71; 95% confidence interval, 17.38 to 98.04; P<0.01) and soluble thrombomodulin (+12.88; 95% confidence interval, 0.29 to 25.46; P<0.001). After successful transplantation, the perfused boundary region was indistinguishable from healthy controls (without elevated levels of soluble thrombomodulin or syndecan-1). In contrast, however, patients who developed interstitial fibrosis and tubular atrophy showed a large perfused boundary region (+0.36; 95% confidence interval, 0.09 to 0.63; P<0.01) and higher levels of endothelial activation markers. In addition, a significant correlation between perfused boundary region, angiopoietin-2, and eGFR was observed (perfused boundary region versus GFR: Spearman's ρ=0.31; P<0.05; perfused boundary region versus angiopoietin-2: Spearman's ρ=-0.33; P<0.05).

CONCLUSION

Reduced renal function is strongly associated with low endothelial surface layer dimensions. After successful kidney transplantation, the endothelial surface layer is indistinguishable from control.

Renal ischemia-reperfusion induces a dysbalance of angiopoietins, accompanied by proliferation of pericytes and fibrosis

Endothelial cells (ECs) are highly susceptible to hypoxia and easily affected upon ischemia-reperfusion (I/R) during renal transplantation. Pericytes and angiopoeitins play important role in modulating EC function. In the present study, we investigate the effect of renal I/R on the dynamics of angiopoietin expression and its association with pericytes and fibrosis development. Male Lewis rats were subjected to unilateral renal ischemia for 45 min followed by removal of the contralateral kidney. Rats were killed at different time points after reperfusion. Endothelial integrity (RECA-1), pericytes [platelet-derived growth factor receptor-β (PDGFR-β)], angiopoietin-2 (Ang-2)/angiopoietin-1 (Ang-1) expression, and interstitial collagen deposition (Sirius red and α-smooth muscle actin) were assessed using immunohistochemistry and RT-PCR. Our study shows an increase in protein expression of Ang-2 starting at 5 h and remaining elevated up to 72 h, with a consequently higher Ang-2/Ang-1 ratio after renal I/R (P < 0.05 at 48 h). This was accompanied by an increase in protein expression of the pericytic marker PDGFR-β and a loss of ECs (both at 72 h after I/R, P < 0.05). Nine weeks after I/R, when renal function was restored, we observed normalization of the Ang-2/Ang-1 ratio and PDGFR-β expression and increase in cortical ECs, which was accompanied by fibrosis. Renal I/R induces a dysbalance of Ang-2/Ang-1 accompanied by proliferation of pericytes, EC loss, and development of fibrosis. The Ang-2/Ang-1 balance was reversed to baseline at 9 wk after renal I/R, which coincided with restoration of cortical ECs and pericytes. Our findings suggest that angiopoietins and pericytes play an important role in renal microvascular remodeling and development of fibrosis.

Microvascular damage in type 1 diabetic patients is reversed in the first year after simultaneous pancreas-kidney transplantation

Simultaneous pancreas-kidney transplantation (SPK) is an advanced treatment option for type 1 diabetes mellitus (DM) patients with microvascular disease including nephropathy. Sidestreamdarkfield (SDF) imaging has emerged as a noninvasive tool to visualize the human microcirculation. This study assessed the effect of SPK in diabetic nephropathy (DN) patients on microvascular alterations using SDF and correlated this with markers for endothelial dysfunction. Microvascular morphology was visualized using SDF of the oral mucosa in DN (n = 26) and SPK patients (n = 38), healthy controls (n = 20), DM1 patients (n = 15, DM ≥ 40 mL/min) and DN patients with a kidney transplant (KTx, n = 15). Furthermore, 21 DN patients were studied longitudinally up to 12 months after SPK. Circulating levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and soluble thrombomodulin (sTM) were measured using ELISA. Capillary tortuosity in the DN (1.83 ± 0.42) and DM ≥ 40 mL/min (1.55 ± 0.1) group was increased and showed reversal after SPK (1.31 ± 0.3, p < 0.001), but not after KTx (1.64 ± 0.1). sTM levels were increased in DN patients and reduced in SPK and KTx recipients (p < 0.05), while the Ang-2/Ang-1 ratio was normalized after SPK and not after KTx alone (from 0.16 ± 0.04 to 0.08 ± 0.02, p < 0.05). Interestingly, in the longitudinal study, reversal of capillary tortuosity and decrease in Ang-2/Ang-1 ratio and sTM was observed within 12 months after SPK. SPK is effective in reversing the systemic microvascular structural abnormalities in DN patients in the first year after transplantation.

Human Bone Marrow- and Adipose Tissue-derived Mesenchymal Stromal Cells are Immunosuppressive In vitro and in a Humanized Allograft Rejection Model

Background

Recent studies with bone marrow (BM)-derived Mesenchymal Stromal Cells (MSC) in transplant recipients demonstrate that treatment with MSC is safe and clinically feasible. While BM is currently the preferred source of MSC, adipose tissue is emerging as an alternative. To develop efficient therapies, there is a need for preclinical efficacy studies in transplantation. We used a unique humanized transplantation model to study the in vivo immunosuppressive effect of human BM-MSC and adipose tissue-derived MSC (ASC).

Methods

Gene expression of BM-MSC and ASC and their capacity to inhibit activated PBMC proliferation was evaluated. The in vivo immunosuppressive effect of BM-MSC and ASC was studied in a humanized mouse model. SCID mice were transplanted with human skin grafts and injected with human allogeneic PBMC with or without administration of BM-MSC or ASC. The effect of MSC on skin graft rejection was studied by immunohistochemistry and PCR.

Results

BM-MSC and ASC expressed TGFβ, CXCL-10 and IDO. IDO expression and acitivity increased significantly in BM-MSC and ASC upon IFN-γ stimulation. IFN-γ stimulated BM-MSC and ASC inhibited the proliferation of activated PBMC in a significant and dose dependent manner. In our humanized mouse model, alloreactivity was marked by pronounced CD45+ T-cell infiltrates consisting of CD4+ and CD8+ T cells and increased IFN-γ expression in the skin grafts which were all significantly inhibited by both BM-MSC and ASC.

Conclusion

BM-MSC and ASC are immunosuppressive in vitro and suppress alloreactivity in a preclinical humanized transplantation model.

Urological complications and their impact on survival after kidney transplantation from deceased cardiac death donors

Urological complications after kidney transplantation may result in significant morbidity and mortality. However, the incidence of such complications after deceased cardiac death (DCD) donor kidney transplantation and their effect on survival is unknown. Purpose of this study was to estimate the incidence of urological complications after DCD kidney transplantation, and to estimate their impact on survival. Patient records of all 76 DCD kidney transplantations in the period 1997-2004 were reviewed for (urological) complications during the initial hospitalization until 30 days after discharge, and graft survival until the last hospital visit. Urological complications occurred in 32 patients (42.1%), with leakage and/or obstruction occurring in seven patients (9.2%). The latter seems to be comparable with the incidence reported in the literature for deceased heart-beating (DHB) transplantations (range 2.5-10%). Overall graft survival was 92% at 1 year and 88% at 3 years, comparable to the rates reported in the literature for kidneys from DHB donors, and was not affected by urological complications (chi(2) = 0.27, P = 0.61). Only a first warm-ischaemia time of 30 min or more reduced graft survival (chi(2) = 4.38, P < 0.05). We conclude that urological complications occur frequently after DCD kidney transplantation, but do not influence graft survival. The only risk factor for reduced graft survival in DCD transplant recipients was the first warm-ischaemia time.