The immune marker soluble urokinase plasminogen activator receptor is associated with new-onset diabetes in non-smoking women and men

The D2D3 form of uPAR acts as an immunotoxin and may cause diabetes and kidney disease

Soluble urokinase plasminogen activator receptor (suPAR) is a risk factor for kidney diseases. In addition to suPAR, proteolysis of membrane-bound uPAR results in circulating D1 and D2D3 proteins. We showed that when exposed to a high-fat diet, transgenic mice expressing D2D3 protein developed progressive kidney disease marked by microalbuminuria, elevated serum creatinine, and glomerular hypertrophy. D2D3 transgenic mice also exhibited insulin-dependent diabetes mellitus evidenced by decreased levels of insulin and C-peptide, impaired glucose-stimulated insulin secretion, decreased pancreatic β cell mass, and high fasting blood glucose. Injection of anti-uPAR antibody restored β cell mass and function in D2D3 transgenic mice. At the cellular level, the D2D3 protein impaired β cell proliferation and inhibited the bioenergetics of β cells, leading to dysregulated cytoskeletal dynamics and subsequent impairment in the maturation and trafficking of insulin granules. D2D3 protein was predominantly detected in the sera of patients with nephropathy and insulin-dependent diabetes mellitus. These sera inhibited glucose-stimulated insulin release from human islets in a D2D3-dependent manner. Our study showed that D2D3 injures the kidney and pancreas and suggests that targeting this protein could provide a therapy for kidney diseases and insulin-dependent diabetes mellitus.

Soluble urokinase Plasminogen Activator Receptor (suPAR) levels are predictive of COVID-19 severity: An Italian experience

Background

The soluble urokinase Plasminogen Activator Receptor (suPAR) has been identified as a reliable marker of COVID-19 severity, helping in personalizing COVID-19 therapy. This study aims to evaluate the correlation between suPAR levels and COVID-19 severity, in relation to the traditional inflammatory markers.

Methods

Sera from 71 COVID-19 patients were tested for suPAR levels using Chorus suPAR assay (Diesse Diagnostica Senese SpA, Italy). suPAR levels were compared with other inflammatory markers: IL-1β, IL-6, TNF-α, circulating calprotectin, neutrophil and lymphocyte counts, and Neutrophil/Lymphocytes Ratio (NLR). Respiratory failure, expressed as P/F ratio, and mortality rate were used as indicators of disease severity.

Results

A positive correlation of suPAR levels with IL-6 (r = 0.479, p = 0.000), TNF-α (r = 0.348, p = 0.003), circulating calprotectin (r = 0.369, p = 0.002), neutrophil counts (r = 0.447, p = 0.001), NLR (r = 0.492, p = 0.001) has been shown. Stratifying COVID-19 population by suPAR concentration above and below 6 ng/mL, we observed higher levels of circulating calprotectin (10.1 μg/mL, SD 7.9 versus 6.4 μg/mL, SD 7.5, p < 0.001), higher levels of P/F ratio (207.5 IQR 188.3 vs 312.0 IQR 127.8, p = 0.013) and higher mortality rate. Median levels of suPAR were increased in all COVID-19 patients requiring additional respiratory support (Nasal Cannula, Venturi Mask, BPAP and CPAP) (6.5 IQR = 4.9) compared to the group at room air (4.6 IQR = 4.2).

Conclusion

suPAR levels correlate with disease severity and survival rate of COVID-19 patients, representing a promising prognostic biomarker for the risk assessment of the disease.

Crystal structure and cellular functions of uPAR dimer

Receptor dimerization of urokinase-type plasminogen activator receptor (uPAR) was previously identified at protein level and on cell surface. Recently, a dimeric form of mouse uPAR isoform 2 was proposed to induce kidney disease. Here, we report the crystal structure of human uPAR dimer at 2.96 Å. The structure reveals enormous conformational changes of the dimer compared to the monomeric structure: D1 of uPAR opens up into a large expanded ring that captures a β-hairpin loop of a neighboring uPAR to form an expanded β-sheet, leading to an elongated, highly intertwined dimeric uPAR. Based on the structure, we identify E49P as a mutation promoting dimer formation. The mutation increases receptor binding to the amino terminal fragment of its primary ligand uPA, induces the receptor to distribute to the basal membrane, promotes cell proliferation, and alters cell morphology via β1 integrin signaling. These results reveal the structural basis for uPAR dimerization, its effect on cellular functions, and provide a basis to further study this multifunctional receptor.

Serum soluble urokinase plasminogen activator receptor as a potential biomarker of renal impairment severity in diabetic nephropathy

AIMS

To investigate serum soluble form of urokinase-type plasminogen activator receptor (suPAR) in patients with diabetic kidney disease (DKD) and biopsy-proven diabetic nephropathy (DN), its correlation with histological parameters and its capacity as a biomarker for renal impairment severity.

METHODS

We conducted a cross-sectional study on 75 patients with diabetes mellitus (DM) and DKD, among whom 28 had biopsy-proven DN.

RESULTS

Among the 75 patients, 9 (12%) had type 1 and 66 (88%) type 2 DM. The median value of the serum suPAR level was 2857.2 pg/mL (1916.4-3700) in the entire cohort and 2472.1 pg/mL (1782.6-3745.8) in the biopsy-proven DN subgroup, respectively. suPAR was significantly correlated with diabetes duration, diabetic retinopathy, anti-proteinuric treatment, albuminuria, kidney function, DN class, interstitial fibrosis and tubular atrophy (IFTA) score and with interstitial inflammation score. suPAR had a good accuracy for the association with chronic kidney disease (CKD) stages G3b-5, macroalbuminuria, DN class IV, IFTA score 3 and interstitial inflammation score 2.

CONCLUSIONS

Serum suPAR was increased in DN patients and was associated with DM duration, diabetic retinopathy, renoprotective treatment, kidney function, proteinuria, DN class, IFTA and interstitial inflammation scores. Also, suPAR had a good capacity as a biomarker for advanced renal impairment and severe histological lesions of DN.

Plasma levels of soluble urokinase plasminogen activator receptor (suPAR) and high-sensitivity C-reactive protein after Roux-en-Y gastric bypass or sleeve gastrectomy: a 1-year prospective observational study

PURPOSE

Low-grade inflammation in obesity contributes to the development of cardiovascular disease, diabetes mellitus and cancer, and is associated with increased mortality. The purpose of this 1-year prospective observational study was to examine the weight loss effect of bariatric surgery on plasma concentrations of two inflammatory markers, namely high-sensitivity C-reactive protein (hsCRP) and soluble urokinase-type plasminogen activator receptor (suPAR), in patients with obesity.

METHODS

Sixteen subjects without obesity and 32 patients with obesity class III, who had already settled upon Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were included in the study. Subjects without obesity were examined once, at baseline; patients with obesity were examined preoperatively (baseline) and 3, 6 and 12 months postoperatively.

RESULTS

Plasma suPAR and hsCRP concentrations at baseline were higher in patients with obesity than in lean participants (2.68 ± 0.86 vs 1.86 ± 0.34 ng/mL, p < 0.001 and 9.83 ± 9.55 vs 1.36 ± 1.95 mg/dL, p < 0.001). Levels of suPAR following bariatric surgery increased significantly 3 months after either RYGB or SG (3.58 ± 1.58 vs 3.26 ± 0.7 ng/mL, respectively) and declined at 6 (3.19 ± 1.75 vs 2.8 ± 0.84 ng/mL, respectively) and 12 months (2.6 ± 1.5 vs 2.22 ± 0.49 ng/mL, respectively; p < 0.05 for the effect of time on suPAR levels during the study), whereas those of hsCRP declined consistently after bariatric surgery (3 months: 5.44 ± 3.99 vs 9.47 ± 11.98 mg/dL, respectively; 6 months; 5.39 ± 5.6 vs 10.25 ± 17.22 mg/dL, respectively; and 12 months: 2.23 ± 2.5 vs 3.07 ± 3.63 mg/dL, respectively; p < 0.001 for the effect of time on hsCRP levels during the study). 1-year change in BMI was negatively associated with suPAR levels at 12 months.

CONCLUSION

Our findings support an association between obesity and low-grade inflammation. Weight loss following bariatric surgery is associated with a consistent decline in plasma hsCRP, while plasma suPAR levels increase at 3 months and decline by 12 months.

SuPAR, a potential inflammatory mediator in psoriasis pathogenesis

Psoriasis is an inflammatory skin disorder that is strongly associated with the metabolic syndrome. The sole reliance on clinical examination to guide prognostication and treatment is insufficient at best; accurate diagnostic and prognostic psoriatic molecular biomarkers are needed. Soluble urokinase plasminogen activator receptor (suPAR) has been implicated in inflammation. The aim of this study is to determine whether suPAR plays a role in the pathogenesis of psoriasis and whether an association exists between suPAR levels, disease severity, and other variables like insulin, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). This study also compares the pattern of uPAR staining in healthy vs psoriatic skin: 39 psoriatic and 30 control subjects were included. Two biopsies (affected and unaffected skin) and one biopsy were taken from psoriasis patients and healthy controls, respectively, with uPAR staining of all skin biopsies. Blood samples from all subjects were obtained to determine suPAR, ESR, CRP, and fasting insulin levels. uPAR staining was prominent in unaffected skin from psoriasis patients and healthy individuals vs weak/absent uPAR staining in psoriatic skin. CRP, ESR and suPAR levels were not significantly elevated in the mild psoriasis group compared to healthy controls. The loss of epidermal uPAR is suggestive of its tentative role in the pathogenesis of psoriasis. Patients with mild-moderate psoriasis possibly lack the powerful association attributed to metabolic syndrome in psoriatic patients. Further studies on larger cohorts are needed to ascertain the validity of the mentioned conclusions.

A Review of Recent Evidence from Meal-Based Diet Interventions and Clinical Biomarkers for Improvement of Glucose Regulation

In recent decades, the prevalence of diabetes has rapidly increased worldwide. Medical nutrition therapy has been identified as a major therapeutic support for diabetic patients, while preventive strategies in prediabetic or high-risk individuals have mainly focused on supplementation with bioactive compounds. Recently, meal-based interventions have been investigated as novel and safe long-term strategies for improving glucose regulation. However, evaluation of meal-based interventions is difficult since it requires analysis of sensitive markers. Biomarkers can also be used to identify individuals at risk for diabetes, which is important for disease prevention. In this review, we summarize current evidence from meal-based intervention studies conducted with the aim of improving glucose homeostasis in individuals at risk of diabetes using clinical biomarkers currently used to assess diabetic risk. Very low-calorie diets have significantly improved glucose regulation in obese adults and in adults with type 2 diabetes mellitus. In particular, changing the ratios of macronutrients through calorie restriction reduces fasting glucose level and hemoglobin A1c levels in patients with diabetes mellitus. However, this effect is limited in both obese and healthy adults. To date, multiple glucose-related markers have been identified as clinical biomarkers of diabetes. Additional clinical biomarkers include cholesterol levels, hematological markers, and inflammatory markers. Taken together, the evidence presented in this review may help for selection of clinical biomarkers for meal-based preventive approaches for non- or pre-diabetic individuals to prevent onset of diabetes.

Validation of suPAR turbidimetric assay on Cobas® (c502 and c702) and comparison to suPAR ELISA

suPAR is a plasma marker of chronic inflammation, and an elevated suPAR is consistently associated with worse outcome in a variety of clinical conditions. Quantification of suPAR is useful for determining patient risk in triage, but there is no fast automatized method for quick determination of suPAR. We developed and validated a rapid latex particle-enhanced turbidimetric immunoassay for quantification of plasma suPAR on the c502 and the c702 Roche Cobas® 8000 measurment systems. The turbidimetric assay was validated against the suPARnostic® ELISA (ViroGates, Denmark). This validation demonstrates suPAR can be analysed by turbidimetry giving very similar results (<15% difference) compared to the ELISA method and the observed correlations (n = 103) were strong, r > 0.95. Roche Cobas® 8000 instruments demonstrated repeatability and repoducibility, CV % at 3.4-4.1 and 5.7-11.4, respectively. The estimated limit of detection was 1.30 µg/L and 1.31 µg/L for the Cobas® c502 and c702, respectively. Dilution tests showed linearity of suPAR from 1.8 to 26.5 μg/L. The acceptable concentrations of Bilirubin, Intralipid and Hemoglobin, were 350 µmol/L, 3.3 g/L and 1.4 g/L, respectively. suPAR can be quantified reproducibly within 10 min using a turbidimetry assay. This assay is faster than ELISA with similar results, making it suitable for clinical routine analysis.

Relating GPI-Anchored Ly6 Proteins uPAR and CD59 to Viral Infection

The Ly6 (lymphocyte antigen-6)/uPAR (urokinase-type plasminogen activator receptor) superfamily protein is a group of molecules that share limited sequence homology but conserved three-fingered structures. Despite diverse cellular functions, such as in regulating host immunity, cell adhesion, and migration, the physiological roles of these factors in vivo remain poorly characterized. Notably, increasing research has focused on the interplays between Ly6/uPAR proteins and viral pathogens, the results of which have provided new insight into viral entry and virus-host interactions. While LY6E (lymphocyte antigen 6 family member E), one key member of the Ly6E/uPAR-family proteins, has been extensively studied, other members have not been well characterized. Here, we summarize current knowledge of Ly6/uPAR proteins related to viral infection, with a focus on uPAR and CD59. Our goal is to provide an up-to-date view of the Ly6/uPAR-family proteins and associated virus-host interaction and viral pathogenesis.

Soluble Urokinase Plasminogen Activator Receptor Predicts Cardiovascular Events, Kidney Function Decline, and Mortality in Patients With Type 1 Diabetes

OBJECTIVE

Soluble urokinase plasminogen activator receptor (suPAR) is an important inflammatory biomarker implicated in endothelial and podocyte dysfunction. However, suPAR's predictive qualities for complications in type 1 diabetes have yet to be determined. We investigated the prognostic value of suPAR for the development of cardiovascular events, decline in renal function, and mortality in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

We included 667 patients with type 1 diabetes with various degrees of albuminuria in a prospective study. End points were cardiovascular events (cardiovascular death, nonfatal acute myocardial infarction, nonfatal stroke, or coronary or peripheral arterial interventions), estimated glomerular filtration rate (eGFR) decline ≥30%, progression from lower to higher albuminuric state, development of end-stage renal disease (ESRD), and mortality. Follow-up was 5.2-6.2 years. Results were adjusted for known risk factors. Hazard ratios (HRs) are presented per doubling of suPAR with 95% CI. Relative integrated discrimination improvement (rIDI) was calculated.

RESULTS

Quantification of suPAR was available in all participants; median (interquartile range) was 3.4 ng/mL (2.7-4.5). The adjusted HR (95% CI) for cardiovascular events (n = 94), progression in albuminuria (n = 36), eGFR decline (n = 93), ESRD (n = 23), and mortality (n = 58) were 3.13 (1.96-5.45, P < 0.001), 1.27 (0.51-3.19, P = 0.61), 2.93 (1.68-5.11, P < 0.001), 2.82 (0.73-11.9, P = 0.13), and 4.13 (1.96-8.69, P < 0.001), respectively. rIDI was significant for cardiovascular events (22.6%, P < 0.001), eGFR decline (14.4%, P < 0.001), and mortality (23.9%, P < 0.001).

CONCLUSIONS

In patients with type 1 diabetes and a broad range of albuminuria, a higher level of suPAR is a significant and independent risk factor for cardiovascular events, decline in eGFR ≥30%, and mortality. In addition, suPAR contributes significantly to discrimination for the end points.

SuPAR, an emerging biomarker in kidney and inflammatory diseases

Soluble urokinase plasminogen activator receptor (suPAR) is a circulating form of a physiological and pathophysiological important cell surface receptor, implicated in inflammation. Recent studies showed that suPAR is a promising biomarker, useful for diagnosis, assessment and prognosis of several diseases. This review summarises the majority of preliminary studies and analyses the significance and the clinical application of suPAR in various clinical conditions. SuPAR seems to have a significant value in the diagnosis as well as prognosis of many diseases; nonetheless, it merits large-scale studies to set cut-off values that help physicians in following up their patients and accordingly tailor their treatment plans.

Predicting Mortality in African Americans With Type 2 Diabetes Mellitus: Soluble Urokinase Plasminogen Activator Receptor, Coronary Artery Calcium, and High-Sensitivity C-Reactive Protein

BACKGROUND

Type 2 diabetes mellitus is a major risk factor for cardiovascular disease; however, outcomes in individual patients vary. Soluble urokinase plasminogen activator receptor (suPAR) is a bone marrow-derived signaling molecule associated with adverse cardiovascular and renal outcomes in many populations. We characterized the determinants of suPAR in African Americans with type 2 diabetes mellitus and assessed whether levels were useful for predicting mortality beyond clinical characteristics, coronary artery calcium (CAC), and high-sensitivity C-reactive protein (hs-CRP).

METHODS AND RESULTS

We measured plasma suPAR levels in 500 African Americans with type 2 diabetes mellitus enrolled in the African American-Diabetes Heart Study. We used Kaplan-Meier curves and Cox proportional hazards models adjusting for clinical characteristics, CAC, and hs-CRP to examine the association between suPAR and all-cause mortality. Last, we report the change in C-statistics comparing the additive values of suPAR, hs-CRP, and CAC to clinical models for prediction of mortality. The suPAR levels were independently associated with female sex, smoking, insulin use, decreased kidney function, albuminuria, and CAC. After a median 6.8-year follow-up, a total of 68 deaths (13.6%) were recorded. In a model incorporating suPAR, CAC, and hs-CRP, only suPAR was significantly associated with mortality (hazard ratio 2.66, 95% confidence interval 1.63-4.34). Addition of suPAR to a baseline clinical model significantly improved the C-statistic for all-cause death (Δ0.05, 95% confidence interval 0.01-0.10), whereas addition of CAC or hs-CRP did not.

CONCLUSIONS

In African Americans with type 2 diabetes mellitus, suPAR was strongly associated with mortality and improved risk discrimination metrics beyond traditional risk factors, CAC and hs-CRP. Studies addressing the clinical usefulness of measuring suPAR concentrations are warranted.

Soluble urokinase receptor (suPAR) predicts microalbuminuria in patients at risk for type 2 diabetes mellitus

Early identification of patients at risk of developing diabetic nephropathy is essential. Elevated serum concentrations of soluble urokinase receptor (suPAR) associate with diabetes mellitus and predict onset and loss of renal function in chronic kidney disease. We hypothesize, that suPAR may be an early risk indicator for diabetic nephropathy, preceding microalbuminuria. The relationship of baseline suPAR and incident microalbuminuria was assessed in a prospective long-term cohort of subjects at increased risk for type 2 diabetes (TULIP, n = 258). Association with albuminuria at later stages of disease was studied in a cross-sectional cohort with manifest type 2 diabetes (ICEPHA, n = 266). A higher baseline suPAR was associated with an increased risk of new-onset microalbuminuria in subjects at risk for type 2 diabetes (hazard ratio 5.3 (95% CI 1.1-25.2, p = 0.03) for the highest vs. lowest suPAR quartile). The proportion of subjects with prediabetes at the end of observation was higher in subjects with new-onset microalbuminuria. suPAR consistently correlated with albuminuria in a separate cohort with manifest type 2 diabetes. Elevated baseline suPAR concentrations independently associate with new-onset microalbuminuria in subjects at increased risk of developing type 2 diabetes. suPAR may hence allow for earlier risk stratification than microalbuminuria.

Soluble Urokinase Receptor and the Kidney Response in Diabetes Mellitus

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD) worldwide. DN typically manifests by glomerular hyperfiltration and microalbuminuria; then, the disease progresses to impaired glomerular filtration rate, which leads to ESRD. Treatment options for DN include the strict control of blood glucose levels and pressure (e.g., intraglomerular hypertension). However, the search for novel therapeutic strategies is ongoing. These include seeking specific molecules that contribute to the development and progression of DN to potentially interfere with these "molecular targets" as well as with the cellular targets within the kidney such as podocytes, which play a major role in the pathogenesis of DN. Recently, podocyte membrane protein urokinase receptor (uPAR) and its circulating form (suPAR) are found to be significantly induced in glomeruli and sera of DN patients, respectively, and elevated suPAR levels predicted diabetic kidney disease years before the occurrence of microalbuminuria. The intent of this review is to summarize the emerging evidence of uPAR and suPAR in the clinical manifestations of DN. The identification of specific pathways that govern DN will help us build a more comprehensive molecular model for the pathogenesis of the disease that can inform new opportunities for treatment.

Urokinase plasminogen activator receptor and its soluble form in common biopsy-proven kidney diseases and in staging of diabetic nephropathy

OBJECTIVES

Soluble urokinase plasminogen activator receptor (suPAR), derived from membrane bound uPAR, is associated with inflammatory diseases. In the present study, we explored the expression of uPAR/suPAR in common biopsy-proven kidney diseases and the relationship between suPAR and staging of type 2 diabetic nephropathy (DN).

DESIGN AND METHODS

Serum samples for suPAR and renal tissues for uPAR staining were investigated in various common kidney diseases. The levels of serum suPAR were measured and adequate cut-off values of different stage of DN were calculated by receiver operating characteristic (ROC) curve.

RESULTS

In our results, the expression of uPAR on renal tissues was pronounced in the majority of kidney diseases. Comparing of expression of uPAR among different kidney diseases, it was strongest in minimal change disease (MCD) and weakest in chronic interstitial nephritis. Serum suPAR in most kidney diseases, except of MCD, was significantly elevated and was highest in DN. As for DN and suPAR, we found that suPAR progressively increased with staging of DN. Moreover, suPAR was linearly and negatively related to estimated glomerular filtration rate and positively related to the amount of proteinuria. By ROC curve, the cut-off values of suPAR in DN for assessing development increased with the progression of the disease.

CONCLUSIONS

We concluded that uPAR/suPAR is elevated in most kidney diseases and that suPAR is a useful biomarker for assessing stages of DN.

Soluble urokinase-type plasminogen activator receptor (suPAR) – a possible biomarker for bacteremia in sepsis / Forma solubilă a receptorului pentru activatorul de plasminogen de tip urokinază (suPAR) – un biomarker posibil pentru bacteriemie în sepsis

Background. Validating new sepsis biomarkers can contribute to early diagnosis and initiation of therapy. The aim of this study is to evaluate the sepsis predictive capacity of soluble urokinase plasminogen receptor (suPAR) and its role in evaluating the prognosis of bloodstream infections. Material and method. We conducted a prospective pilot study on 49 systemic inflammatory response syndrome (SIRS) patients admitted to the intensive care unit (ICU), that were divided, on the basis of bacteremia in group A (SIRS with bacteremia, n=14) and group B (SIRS without bacteremia, n=35). Hemoculture and blood samples were drawn on the first day to determine suPAR, C-reactive protein (CRP) and procalcitonin (PCT). We set to identify significant cut-off values in estimating bacteremia and mortality in septic patients. Results. In group A, suPAR values were 14.3 ng/mL (range 10-45.5 ng/mL) and in group B, 9.85 ng/mL (range 3.4-48 ng/mL) p=0.008. Area under the curve (AUC) for suPAR was 0.745 (95% CI: 0.600-0.859), for CRP 0.613 (95% CI: 0.522-0.799) and for PCT 0.718 (95% CI: 0.477-0.769). Cut-off value for suPAR in bacteremia prediction was 9.885 ng/mL, with 100% sensibility and 51.43% specificity. Mortality in group A was 85.7% (12/14) and in group B 74.3% (26/39), p>0.05. Area under the curve (AUC) for suPAR was 0.750 (95% CI: 0.455-0.936), for CRP 0.613 (95% CI: 0.413-0.913) and for PCT 0.618 (95% CI: 0.373-0.888). Cut-off value of suPAR in predicting mortality was 11.5 ng/mL, with 66.67% sensibility and 100% specificity. Conclusions. In our study suPAR had a predictive capacity for bacteremia and seems to be an independent factor for mortality prognosis in septic patients.

Associations of suPAR with lifestyle and cardiometabolic risk factors

BACKGROUND

Soluble urokinase plasminogen activator receptor (suPAR), a novel indicator of low-grade inflammation, is associated with cardiovascular disease and mortality in the general population, while an unhealthy lifestyle influences inflammatory status. We aimed to explore the relationship of suPAR with lifestyle and cardiometabolic risk factors in a black South African population.

DESIGN

This cross-sectional study includes 1068 men and women (56·4 ± 10·1 years) from the North West province who took part in the South African leg of the Prospective Urban and Rural Epidemiology (PURE) study in 2010. Captured data included a detailed lifestyle profile (tobacco use, alcohol consumption, physical activity, psychological and dietary intake status), biochemical analyses (suPAR, C-reactive protein (CRP), glucose and lipids), as well as cardiovascular and anthropometric measurements.

RESULTS

In exploratory analyses, we observed positive relationships between suPAR and lifestyle factors, such as tobacco use (P-trend < 0·001), both alcohol consumption (P-trend = 0·001) and γ-glutamyl transferase (GGT) (P-trend < 0·001) and unemployment (P-trend = 0·002). suPAR and CRP correlated significantly (r = 0·23; P < 0·001). These relationships were confirmed in multiple regression analyses as suPAR independently associated with tobacco use (β = 0·13; P < 0·001), GGT (β = 0·24; P < 0·001) and unemployment (β = 0·07; P = 0·039). suPAR did not associate with the cardiometabolic factors glucose, lipids, blood pressure or measures of adiposity.

CONCLUSION

suPAR was independently associated with unhealthy lifestyle behaviours, but not with cardiometabolic risk factors suggesting that suPAR, as known predictor of cardiovascular disease and mortality, is augmented by modifiable cardiovascular risk factors. These findings emphasise the need for a healthy lifestyle to decrease the burden of cardiovascular disease in Africans.

Longitudinal changes in leukocyte telomere length and mortality in humans

BACKGROUND

Leukocyte telomere length (LTL) ostensibly shortens with age and has been moderately associated with mortality. In humans, these findings have come almost solely from cross-sectional studies. Only recently has LTL shortening within individuals been analyzed in longitudinal studies. Such studies are relevant to establish LTL dynamics as biomarkers of mortality as well as to disentangle the causality of telomeres on aging.

METHODS

We present a large longitudinal study on LTL and human mortality, where the 10-year change of LTL is analyzed in 1,356 individuals aged 30-70 years.

RESULTS

We find age, smoking status, and alcohol consumption to be associated with LTL attrition and confirm a strong association with baseline LTL. The latter association might be an epiphenomenon of regression to the mean. We do not find an association of mortality with either absolute LTL or LTL attrition. Further, we show that DNA quality has an impact on TS ratios.

CONCLUSIONS

This study establishes that certain lifestyle factors influence LTL dynamics. However, it questions the applicability of LTL dynamics as a predictor of mortality. We suggest cautiousness when assessing actual LTL attrition due to the need for high-quality DNA and the phenomena of regression to the mean.

The pro-inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) is associated with incident type 2 diabetes among overweight but not obese individuals with impaired glucose regulation: effect modification by smoking and body weight status

AIMS/HYPOTHESIS

Recent evidence links the soluble urokinase plasminogen activator receptor (suPAR), a stable biomarker of systemic immune activation, to several chronic diseases, including type 2 diabetes. suPAR is also associated with adiposity and smoking. We hypothesised that this biomarker would be linked to incident type 2 diabetes in individuals with impaired glucose regulation and that this association would be modified by smoking and body weight status.

METHODS

The study included 1,933 participants with impaired glucose regulation, who were drawn from the Danish arm of the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen-Detected Diabetes in Primary Care (ADDITION) and for whom data on suPAR, BMI and smoking were available. Logistic regression analysis was used to estimate the odds for incident type 2 diabetes per twofold increase in suPAR levels. Interactions between both smoking and body weight status and suPAR were tested.

RESULTS

During a 3-year follow-up (599 incident diabetes cases), there was a 48% overall increase in the odds of developing type 2 diabetes per twofold increase in suPAR (p = 0.006). This association was modified by body weight status in overweight, but not in obese individuals (OR 2.36, 95% CI 1.48, 3.76 in overweight group), and by smoking status (OR 2.05, 95% CI 1.20, 3.51 in non-smokers). After adjustment for other diabetes risk factors, the association between suPAR and type 2 diabetes was attenuated in the whole sample and among non-smokers, but remained robust among overweight participants.

CONCLUSIONS/INTERPRETATION

suPAR may be a good novel biomarker for systemic sub-clinical inflammation and immune activation linked to incident type 2 diabetes risk in overweight individuals and non-smokers. The observed interactions with adiposity and smoking should be investigated further.

Soluble urokinase plasminogen activator receptor, C-reactive protein and triglyceride are associated with heart rate variability in non-diabetic Danes

BACKGROUND

Heart rate variability (HRV) is associated with an increased risk of cardiovascular morbidity and mortality. HRV is in part a function of the activity of the autonomic nervous system and has been associated with low-grade inflammation. In patients with type 2 diabetes, HRV is decreased and is a predictor of poor outcome. As HRV and its determinants in non-diabetic individuals have not been studied properly, the aim of this observational study was to evaluate possible associations between HRV vs. impaired fasting glucose, insulin resistance, lipidaemia and markers of inflammation and immune activation in these individuals.

MATERIALS AND METHODS

Healthy individuals (n = 596, 55-75 years) from the community were evaluated with ambulant 48-h continuous electrocardiogram monitoring and fasting markers of lipidaemia, inflammation and immune activation, respectively. Insulin resistance was estimated by HOMA-IR. Time domain components of HRV were calculated.

RESULTS

Heart rate and HRV were not associated with glucose metabolic parameters but were inversely associated with soluble urokinase plasminogen activator receptor (suPAR), high-sensitive CRP and leucocyte number (P < 0·001), respectively. Both 24-h and night-time HRV were inversely associated with plasma triglyceride, whereas HDL, LDL and total cholesterol were not. A model including suPAR, CRP, gender, triglyceride, age, systolic blood pressure, physical activity and smoking status explained 12·2% (P < 0·0001) of the 24-h HRV and 7·3% (P < 0·0001) of the night-time HRV. The single strongest factor to explain 24-h and night-time HRV appeared to be suPAR (P = 0·001 and P = 0·0067, respectively).

CONCLUSION

A low HRV is not related to prediabetes, that is, insulin resistance and impaired fasting glucose, but is related to the immune and inflammatory markers suPAR and CRP and plasma triglyceride.

Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque

BACKGROUND AND PURPOSE

Recently, plasma soluble urokinase plasminogen activator receptor (suPAR) has gained interest as a marker of cardiovascular risk. suPAR is released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in monocytes, activated T-lymphocytes and endothelial cells, all involved in atherosclerosis. suPAR levels have been well studied in plasma, but no studies have focused on suPAR in human atherosclerotic plaques. The aim of this study was to determine whether suPAR measured in the plaque is associated with symptomatic plaques and plaque inflammation.

METHODS

Plasma and carotid plaques from 162 patients were analyzed. Lipids, collagen, uPAR, and macrophages were measured histologically. Cytokines and suPAR were measured in homogenized plaque extracts using multiplex immunoassay and ELISA, respectively. Plasma levels of suPAR were analysed with ELISA. CD3, CD4, as well as uPAR mRNA expression were assessed with quantitative real-time polymerase chain reaction in plaque homogenates from 123 patients.

RESULTS

Plaque and plasma suPAR levels were higher in symptomatic patients compared with asymptomatic patients. Plaque suPAR levels correlated with plaque content of lipids and macrophages and with proinflammatory chemokines and cytokines monocyte chemoattractant protein 1, tumor necrosis factor α, interleukin 1β, interleukin 6, platelet-derived growth factor AB/BB, monocyte inflammatory protein 1β, regulated on activation normal T-cell expressed and secreted, and s-CD40L. uPAR mRNA and histological staining for uPAR correlated with plaque content of suPAR.

CONCLUSIONS

This study shows that suPAR in human carotid plaques and plasma is associated with the presence of symptoms and that plaque suPAR is associated with the vulnerable inflammatory plaque. These findings strengthen the hypothesis of suPAR as a future marker of vulnerable atherosclerotic plaques.