SuPAR, biomarkers of inflammation, and severe outcomes in patients hospitalized for COVID-19: The International Study of Inflammation in COVID-19.

Severe coronavirus disease 2019 (COVID-19) is a hyperinflammatory syndrome. The biomarkers of inflammation best suited to triage patients with COVID-19 are unknown. We conducted a prospective multicenter observational study of adult patients hospitalized specifically for COVID-19 from February 1, 2020 to October 19, 2022. Biomarkers measured included soluble urokinase plasminogen activator receptor (suPAR), C-reactive protein, interleukin-6, procalcitonin, ferritin, and D-dimer. In-hospital outcomes examined include death and the need for mechanical ventilation. Patients admitted in the United States (US, n = 1962) were used to compute area under the curves (AUCs) and identify biomarker cutoffs. The combined European cohorts (n = 1137) were used to validate the biomarker cutoffs. In the US cohort, 356 patients met the composite outcome of death (n = 197) or need for mechanical ventilation (n = 290). SuPAR was the most important predictor of the composite outcome and had the highest AUC (0.712) followed by CRP (0.642), ferritin (0.619), IL-6 (0.614), D-dimer (0.606), and lastly procalcitonin (0.596). Inclusion of other biomarkers did not improve discrimination. A suPAR cutoff of 4.0 ng/mL demonstrated a sensitivity of 95.4% (95% CI: 92.4%-98.0%) and negative predictive value (NPV) of 92.5% (95% CI: 87.5%-96.9%) for the composite outcome. Patients with suPAR < 4.0 ng/mL comprised 10.6% of the cohort and had a 0.8% probability of the composite outcome. Applying this cutoff to the validation cohort yielded a sensitivity of 93.8% (90.4%-96.7%) and NPV of 95.5% (93.1%-97.8%) for the composite outcome. Among commonly measured biomarkers, suPAR offered stronger discriminatory ability and may be useful in triaging low-risk patients with COVID-19.

Social isolation, loneliness, and inflammation: A multi-cohort investigation in early and mid-adulthood.

Social isolation and loneliness have been associated with poor health and increased risk for mortality, and inflammation might explain this link. We used data from the Danish TRIAGE Study of acutely admitted medical patients (N = 6,144, mean age 60 years), and from two population-representative birth cohorts: the New Zealand Dunedin Longitudinal Study (N = 881, age 45) and the UK Environmental Risk (E-Risk) Longitudinal Twin Study (N = 1448, age 18), to investigate associations of social isolation with three markers of systemic inflammation: C-reactive protein (CRP), interleukin-6 (IL-6), and a newer inflammation marker, soluble urokinase plasminogen activator receptor (suPAR), which is thought to index systemic chronic inflammation. In the TRIAGE Study, socially isolated patients (those living alone) had significantly higher median levels of suPAR (but not CRP or IL-6) compared with patients not living by themselves. Social isolation prospectively measured in childhood was longitudinally associated with higher CRP, IL-6, and suPAR levels in adulthood (at age 45 in the Dunedin Study and age 18 in the E-Risk Study), but only suPAR remained associated after controlling for covariates. Dunedin Study participants who reported loneliness at age 38 or age 45 had elevated suPAR at age 45. In contrast, E-Risk Study participants reporting loneliness at age 18 did not show any elevated markers of inflammation. In conclusion, social isolation was robustly associated with increased inflammation in adulthood, both in medical patients and in the general population. It was associated in particular with systemic chronic inflammation, evident from the consistently stronger associations with suPAR than other inflammation biomarkers.

Soluble urokinase plasminogen activator receptor and decline in kidney function among patients without kidney disease.

Background: Hospitalized patients are at an increased risk of developing kidney disease after discharge, often despite the absence of any clinical indicators during hospitalization. Soluble urokinase plasminogen activator receptor (suPAR) is a marker of systemic chronic inflammation that can be measured from routine blood samples. We determined whether elevated suPAR during hospitalization is associated with a decline in estimated glomerular filtration rate (eGFR) after discharge. Methods: This was a retrospective longitudinal cohort study of patients without detectable kidney disease presenting to the emergency department on two separate occasions during a 3-year period. The association between suPAR and a decline in eGFR was assessed by linear mixed models for repeated measures adjusting for age, sex, C-reactive protein, sodium, diabetes, hypertension and cardiovascular disease. Results: In total, 5124 patients (median age 65.9 years, 51.0% female) were included. The median suPAR was 2.9 ng/mL, the median time to readmission was 144 days and the expected rate of eGFR decline over this period was 5.1 mL/min/1.73 m2/year. Adjusting for other risk factors, patients with suPAR <3, 3-6 or ≥6 ng/mL had an expected eGFR decline of 4.3, 5.2 or 9.0 mL/min/1.73 m2/year, respectively. Similarly, patients with suPAR in the lowest (<2.4 ng/mL), middle (2.4-3.6 ng/mL) or highest (≥3.6 ng/mL) tertile had an expected eGFR decline of 4.2, 4.6 or 6.5 mL/min/1.73 m2/year, respectively. In both cases, a higher suPAR level was significantly and independently associated with a higher rate of eGFR decline (P < .001). Conclusions: A higher suPAR level was associated with accelerated eGFR decline among patients presenting to the emergency department, suggesting that routine suPAR measurements may have utility for the early detection of kidney disease.

Association of Preoperative Basal Inflammatory State, Measured by Plasma suPAR Levels, with Intraoperative Sublingual Microvascular Perfusion in Patients Undergoing Major Non-Cardiac Surgery.

It remains unknown whether chronic systemic inflammation is associated with impaired microvascular perfusion during surgery. We evaluated the association between the preoperative basal inflammatory state, measured by plasma soluble urokinase-type plasminogen activator receptor (suPAR) levels, and intraoperative sublingual microcirculatory variables in patients undergoing major non-cardiac surgery. Plasma suPAR levels were determined in 100 non-cardiac surgery patients using the suPARnostic® quick triage lateral flow assay. We assessed sublingual microcirculation before surgical incision and every 30 min during surgery using Sidestream Darkfield (SDF+) imaging and determined the De Backer score, the Consensus Proportion of Perfused Vessels (Consensus PPV), and the Consensus PPV (small). Elevated suPAR levels were associated with lower intraoperative De Backer score, Consensus PPV, and Consensus PPV (small). For each ng mL−1 increase in suPAR, De Backer score, Consensus PPV, and Consensus PPV (small) decreased by 0.7 mm−1, 2.5%, and 2.8%, respectively, compared to baseline. In contrast, CRP was not significantly correlated with De Backer score (r = −0.034, p = 0.36), Consensus PPV (r = −0.014, p = 0.72) or Consensus PPV Small (r = −0.037, p = 0.32). Postoperative De Backer score did not change significantly from baseline (5.95 ± 3.21 vs. 5.89 ± 3.36, p = 0.404), while postoperative Consensus PPV (83.49 ± 11.5 vs. 81.15 ± 11.8, p < 0.001) and Consensus PPV (small) (80.87 ± 13.4 vs. 78.72 ± 13, p < 0.001) decreased significantly from baseline. In conclusion, elevated preoperative suPAR levels were associated with intraoperative impairment of sublingual microvascular perfusion in patients undergoing elective major non-cardiac surgery.

IL-1 Mediates Tissue-Specific Inflammation and Severe Respiratory Failure in COVID-19.

Acute respiratory distress syndrome (ARDS) in COVID-19 has been associated with catastrophic inflammation. We present measurements in humans and a new animal model implicating a role in danger-associated molecular patterns. Calprotectin (S100A8/A9) and high-mobility group box 1 (HMGB1) were measured in patients without/with ARDS, and admission calprotectin was associated with soluble urokinase plasminogen activator receptor (suPAR). An animal model was developed by intravenous injection of plasma from healthy or patients with COVID-19 ARDS into C57/BL6 mice once daily for 3 consecutive days. Mice were treated with one anti-S100A8/A9 antibody, the IL-1 receptor antagonist anakinra or vehicle, and Flo1-2a anti-murine anti-IL-1α monoclonal antibody or the specific antihuman IL-1α antibody XB2001 or isotype controls. Cytokines and myeloperoxidase (MPO) were measured in tissues. Calprotectin, but not HMGB1, was elevated in ARDS. Higher suPAR indicated higher calprotectin. Animal challenge with COVID-19 plasma led to inflammatory reactions in murine lung and intestines as evidenced by increased levels of TNFα, IL-6, IFNγ, and MPO. Lung inflammation was attenuated with anti-S100A8/A9 pre-treatment. Anakinra treatment restored these levels. Similar decrease was found in mice treated with Flo1-2a but not with XB2001. Circulating alarmins, specifically calprotectin, of critically ill COVID-19 patients induces tissue-specific inflammatory responses through an IL-1-mediated mechanism. This could be attenuated through inhibition of IL-1 receptor or of IL-1α.

Soluble Urokinase Receptor Levels Are Not Affected by the Systemic Inflammatory Response to Anesthesia and Operative Trauma.

INTRODUCTION: Soluble urokinase plasminogen activator receptor (suPAR) is an emerging biomarker of the level of chronic systemic inflammation and the general condition of the patient. We aimed to investigate the impact of general anesthesia and major surgery on perioperative suPAR and C-reactive protein (CRP) levels. METHODS: This study included patients undergoing elective major noncardiac surgery with an expected duration of ≥2 h under general anesthesia. Inclusion criteria were age ≥18 years and American Society of Anesthesiologists' physical status I-IV. Blood was drawn 30 min prior to induction of anesthesia (preoperatively), as well as 30 min after emergence from anesthesia (postoperatively). Plasma suPAR levels were determined using the suPARnostic® Quick Triage lateral flow assay. CRP measurements were performed by particle-enhanced immunoturbidimetric assay. RESULTS: The difference in preoperative and postoperative suPAR levels was not statistically significant (7.7 [5.28-10.4] ng/mL vs. 7.15 [5.68-9.8] ng/mL, p = 0.462). CRP levels increased significantly during surgery (0.81 [0.24-2.1] mg/dL vs. 5.76 [2.2-8.75] mg/dL, p < 0.001). No correlation was observed between CRP and suPAR levels, both preoperatively (rho = 0.127; p = 0.208) and postoperatively (rho = 0.017; p = 0.87). A statistically significant increase was also observed in postoperative white blood cell count (7.576 vs. 10.711, p < 0.001). CONCLUSION: General anesthesia and operative trauma did not affect perioperative suPAR levels despite the activation of systemic inflammatory response.

Elevated preoperative suPAR is a strong and independent risk marker for postoperative complications in patients undergoing major noncardiac surgery (SPARSE).

BACKGROUND: Patients undergoing major surgery are often at risk of developing postoperative complications. We investigated whether a preoperative marker of chronic inflammation, soluble urokinase plasminogen activator receptor, can aid in identifying patients at high risk for postoperative complications, morbidity, and mortality. METHODS: In this prospective observational study (ClinicalTrials.gov identifier: NCT03851965), EDTA blood was collected from consecutive adult White patients scheduled for major noncardiac surgery with expected duration ≥2 hours under general anesthesia. Inclusion criteria were age ≥18 years and American Society of Anesthesiologists physical status I to IV. Plasma soluble urokinase plasminogen activator receptor levels were determined using the suPARnostic quick triage lateral flow assay. The primary endpoint was postoperative complications defined as presence of any complication and/or admission to intensive care unit and/or mortality within the first 90 postoperative days. RESULTS: Preoperative soluble urokinase plasminogen activator receptor had an odds ratio of 1.50 (95% confidence interval: 1.24-1.82) for every ng/mL increase. When including age, sex, American Society of Anesthesiologists score, C-reactive protein, and grouped soluble urokinase plasminogen activator receptor in multivariate analysis, patients with soluble urokinase plasminogen activator receptor between 5.5 and 10 ng/mL had an odds ratio of 11.2 (confidence interval: 3.1-40.8) and patients with soluble urokinase plasminogen activator receptor >10 ng/mL had an odds ratio of 19.9 (95% confidence interval: 4.3-92.9) compared to patients with soluble urokinase plasminogen activator receptor ≤5.5 ng/mL, respectively. Receiver operating characteristic analysis of soluble urokinase plasminogen activator receptor showed an area under the curve of 0.82 (confidence interval: 0.72-0.91). Receiver operating characteristic analysis combining age, sex, C-reactive protein levels, and American Society of Anesthesiologists score and had an area under the curve of 0.71 (95% confidence interval: 0.61-0.82). Adding soluble urokinase plasminogen activator receptor to this model increased the area under the curve to 0.83 (95% confidence interval: 0.74-0.92) (P = .033). CONCLUSION: Preoperative soluble urokinase plasminogen activator receptor provided strong and independent predictive value on postoperative complications in White patients undergoing major noncardiac surgery.

Using soluble urokinase plasminogen activator receptor to stratify patients for medication review in the emergency department.

AIMS: To investigate whether the association between levels of medication use (including polypharmacy and potentially inappropriate medications [PIMs]) and health outcomes such as readmission and mortality is dependent on baseline soluble urokinase plasminogen activator receptor (suPAR). METHODS: This registry-based cohort study included medical patients admitted to the emergency department at Copenhagen University Hospital Hvidovre, Denmark. Patients were grouped according to their admission suPAR levels: low (0-3 ng/mL), intermediate (3-6 ng/mL), or high (>6 ng/mL). Hyper-polypharmacy was defined as ≥10 prescribed medications. PIMs were identified based on the EU(7)-PIM list, and data on admissions and mortality were obtained from national registries. Risk of 90-day readmission and mortality was assessed by Cox regression analysis adjusted for sex, age and Charlson comorbidity index. Results were reported as hazard ratios within 90 days of index discharge. RESULTS: In total, 26 291 patients (median age 57.3 y; 52.7% female) were included. Risk of 90-day readmission and mortality increased significantly for patients with higher suPAR or higher number of medications. Among patients with low suPAR, patients with ≥10 prescribed medications had a hazard ratio of 2.41 (95% confidence interval = 2.09-2.78) for 90-day readmission and 8.46 (95% confidence interval = 2.53-28.28) for 90-day mortality compared to patients with 0 medications. Patients with high suPAR generally had high risk of readmission and mortality, and the impact of medication use was less pronounced in this group. Similar, but weaker, association patterns were observed between suPAR and PIMs. CONCLUSION: The association between levels of medication use and health outcomes is dependent on baseline suPAR.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) as a Biomarker of Systemic Chronic Inflammation.

Systemic chronic inflammation (SCI) is persistent, health-damaging, low-grade inflammation that plays a major role in immunosenescence and in development and progression of many diseases. But currently, there are no recognized standard biomarkers to assess SCI levels alone, and SCI is typically measured by combining biomarkers of acute inflammation and infection, e.g., CRP, IL-6, and TNFα. In this review, we highlight 10 properties and characteristics that are shared by the blood protein soluble urokinase plasminogen activator receptor (suPAR) and SCI, supporting the argument that suPAR is a biomarker of SCI: (1) Expression and release of suPAR is upregulated by immune activation; (2) uPAR and suPAR exert pro-inflammatory functions; (3) suPAR is associated with the amount of circulating immune cells; (4) Blood suPAR levels correlate with the levels of established inflammatory biomarkers; (5) suPAR is minimally affected by acute changes and short-term influences, in contrast to many currently used markers of systemic inflammation; (6) Like SCI, suPAR is non-specifically associated with multiple diseases; (7) suPAR and SCI both predict morbidity and mortality; (8) suPAR and SCI share the same risk factors; (9) suPAR is associated with risk factors and outcomes of inflammation above and beyond other inflammatory biomarkers; (10) The suPAR level can be reduced by anti-inflammatory interventions and treatment of disease. Assessing SCI has the potential to inform risk for morbidity and mortality. Blood suPAR is a newer biomarker which may, in fact, be a biomarker of SCI since it is stably associated with inflammation and immune activation; shares the same risk factors as many age-related diseases; is both elevated by and predicts age-related diseases. There is strong evidence that suPAR is a prognostic marker of adverse events, morbidity, and mortality. It is associated with immune activity and prognosis across diverse conditions, including kidney disease, cardiovascular disease, cancer, diabetes, and inflammatory disorders. Thus, we think it likely represents a common underlying disease-process shared by many diseases; that is, SCI. We review the supporting literature and propose a research agenda that can help test the hypothesis that suPAR indexes SCI, with the potential of becoming the new gold standard for measuring SCI.

Investigating the inflammation marker neutrophil-to-lymphocyte ratio in Danish blood donors with restless legs syndrome.

BACKGROUND: Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder that occurs in the evening and night, thereby impacting quality of sleep in sufferers. The pathophysiology of RLS is poorly understood but inflammation has been proposed as possibly being involved. The neutrophil-to-lymphocyte ratio (NLR) can be used as an inflammation marker but results from small studies have been inconclusive in determining whether NLR is associated with RLS. We aimed to assess whether an association between NLR and RLS exists in a large cohort of healthy individuals. METHODS: Neutrophils and lymphocytes were measured in blood samples of 13,055 individuals from the Danish Blood Donor Study, all of whom completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment. RESULTS: In the sample, 661 individuals were determined as current RLS cases (5.1%). A higher proportion of individuals with RLS were females (62.5% vs 47.5%; P<0.001) and RLS cases were older than controls (P<0.001), but no differences in body mass index (BMI), smoking or alcohol consumption were found between the two groups. An increased NLR was observed in RLS cases compared to controls (median NLR: 1.80 vs 1.72; P = 0.033). In an unadjusted logistic regression model, increased NLR was associated with RLS (OR = 1.10 per NLR unit increase [95%CI:1.01-1.20]; P = 0.032); however, the association was not significant in multivariate models adjusting for sex and age (P = 0.094) or sex, age, alcohol consumption, smoking status and BMI (P = 0.107). CONCLUSION: We found no association between RLS and NLR among Danish blood donors after adjusting for sex, age, alcohol consumption, smoking status and BMI. Further studies are needed to determine whether inflammation is a risk factor for RLS.

Eleven genomic loci affect plasma levels of chronic inflammation marker soluble urokinase-type plasminogen activator receptor.

Soluble urokinase-type plasminogen activator receptor (suPAR) is a chronic inflammation marker associated with the development of a range of diseases, including cancer and cardiovascular disease. The genetics of suPAR remain unexplored but may shed light on the biology of the marker and its connection to outcomes. We report a heritability estimate of 60% for the variation in suPAR and performed a genome-wide association meta-analysis on suPAR levels measured in Iceland (N = 35,559) and in Denmark (N = 12,177). We identified 13 independently genome-wide significant sequence variants associated with suPAR across 11 distinct loci. Associated variants were found in and around genes encoding uPAR (PLAUR), its ligand uPA (PLAU), the kidney-disease-associated gene PLA2R1 as well as genes with relations to glycosylation, glycoprotein biosynthesis, and the immune response. These findings provide new insight into the causes of variation in suPAR plasma levels, which may clarify suPAR's potential role in associated diseases, as well as the underlying mechanisms that give suPAR its prognostic value as a unique marker of chronic inflammation.

An open label trial of anakinra to prevent respiratory failure in COVID-19.

Background: It was studied if early suPAR-guided anakinra treatment can prevent severe respiratory failure (SRF) of COVID-19. Methods: A total of 130 patients with suPAR ≥6 ng/ml were assigned to subcutaneous anakinra 100 mg once daily for 10 days. Primary outcome was SRF incidence by day 14 defined as any respiratory ratio below 150 mmHg necessitating mechanical or non-invasive ventilation. Main secondary outcomes were 30-day mortality and inflammatory mediators; 28-day WHO-CPS was explored. Propensity-matched standard-of care comparators were studied. Results: 22.3% with anakinra treatment and 59.2% comparators (hazard ratio, 0.30; 95% CI, 0.20-0.46) progressed into SRF; 30-day mortality was 11.5% and 22.3% respectively (hazard ratio 0.49; 95% CI 0.25-0.97). Anakinra was associated with decrease in circulating interleukin (IL)-6, sCD163 and sIL2-R; IL-10/IL-6 ratio on day 7 was inversely associated with SOFA score; patients were allocated to less severe WHO-CPS strata. Conclusions: Early suPAR-guided anakinra decreased SRF and restored the pro-/anti-inflammatory balance. Funding: This study was funded by the Hellenic Institute for the Study of Sepsis, Technomar Shipping Inc, Swedish Orphan Biovitrum, and the Horizon 2020 Framework Programme. Clinical trial number: NCT04357366.

People infected with the SARS-CoV-2 virus, which causes COVID-19, can develop severe respiratory failure and require a ventilator to keep breathing, but this does not happen to every infected individual. Measuring a blood protein called suPAR (soluble urokinase plasminogen activator receptor) may help identify patients at the greatest risk of developing severe respiratory failure and requiring a ventilator. Previous investigations have suggested that measuring suPAR can identify pneumonia patients at highest risk for developing respiratory failure. The protein can be measured by taking a blood sample, and its levels provide a snapshot of how the body's immune system is reacting to infection, and of how it may respond to treatment. Anakinra is a drug that forms part of a class of medications called interleukin antagonists. It is commonly prescribed alone or in combination with other medications to reduce pain and swelling associated with rheumatoid arthritis. Kyriazopoulou et al. investigated whether treating COVID-19 patients who had developed pneumonia with anakinra could prevent the use of a ventilator and lower the risk of death. The findings show that treating COVID-19 patients with an injection of 100 milligrams of anakinra for ten days may be an effective approach because the drug combats inflammation. Kyriazopoulou et al. examined various markers of the immune response and discovered that anakinra was able to improve immune function, protecting a significant number of patients from going on a ventilator. The drug was also found to be safe and cause no significant adverse side effects. Administering anakinra decreased of the risk of progression into severe respiratory failure by 70%, and reduced death rates significantly. These results suggest that it may be beneficial to use suPAR as an early biomarker for identifying those individuals at highest risk for severe respiratory failure, and then treat them with anakinra. While the findings are promising, they must be validated in larger studies.

Association Between Elevated suPAR, a New Biomarker of Inflammation, and Accelerated Aging.

BACKGROUND: To understand and measure the association between chronic inflammation, aging, and age-related diseases, broadly applicable standard biomarkers of systemic chronic inflammation are needed. We tested whether elevated blood levels of the emerging chronic inflammation marker soluble urokinase plasminogen activator receptor (suPAR) were associated with accelerated aging, lower functional capacity, and cognitive decline. METHODS: We used data from the Dunedin Study, a population-representative 1972-1973 New Zealand birth cohort (n = 1037) that has observed participants to age 45 years. Plasma suPAR levels were analyzed at ages 38 and 45 years. We performed regression analyses adjusted for sex, smoking, C-reactive protein, and current health conditions. RESULTS: Of 997 still-living participants, 875 (88%) had plasma suPAR measured at age 45. Elevated suPAR was associated with accelerated pace of biological aging across multiple organ systems, older facial appearance, and with structural signs of older brain age. Moreover, participants with higher suPAR levels had greater decline in physical function and cognitive function from childhood to adulthood compared to those with lower suPAR levels. Finally, improvements in health habits between ages 38 and 45 (smoking cessation or increased physical activity) were associated with less steep increases in suPAR levels over those years. CONCLUSIONS: Our findings provide initial support for the utility of suPAR in studying the role of chronic inflammation in accelerated aging and functional decline.

Soluble urokinase plasminogen activator receptor (suPAR) is lower in disease-free patients but cannot rule out incident disease in patients with suspected cancer.

BACKGROUND: Accurate first-line diagnostics are essential for early recognition of cancer but also to identify patients free of disease. The biomarker soluble urokinase plasminogen activator receptor (suPAR) is elevated in patients with cancer or non-malignant disease compared to disease-free patients. We tested if low suPAR could be used to identify disease-free patients in an accelerated cancer diagnostics program, including ruling out cancer. METHODS: Patients with serious nonspecific symptoms and signs of cancer (NSSC) were included at the Diagnostic Outpatient Clinic, Copenhagen University Hospital Hvidovre, Denmark. Data from a clinical examination, including blood tests and imaging, was combined with national registry data on diagnoses and mortality. The association between blood suPAR and the primary outcome of disease-free (i.e., absence of incident disease and mortality) within 1-year follow-up was analysed with logistic regression analysis. RESULTS: Of 1583 patients included, 349 (22.0%) were diagnosed with cancer, 837 (52.9%) with non-malignant disease, and 392 (25.8%) were disease-free within one year. Admission suPAR was significantly lower in disease-free patients compared to patients with cancer or non-malignant disease (P < 0.001), area under the curve 0.67 (95% confidence interval (CI): 0.64-0.70). The highest positive predictive value (PPV) for the outcome of disease-free was 0.55 (95% CI: 0.41-0.68) at a suPAR of 1.65 ng/mL. Patients who died had significantly higher suPAR compared to patients who survived in all disease subgroups. The AUC of suPAR for 1-year mortality was 0.80 (95% CI: 0.77-0.83). CONCLUSIONS: suPAR was significantly lower in disease-free individuals compared to patients with cancer or other conditions, but the PPV was not sufficiently high to terminate further clinical investigation with appropriate safety. Elevated suPAR may be a useful prognostic marker for adverse outcomes.

Association of Adverse Experiences and Exposure to Violence in Childhood and Adolescence With Inflammatory Burden in Young People.

Importance: Childhood stress exposure is associated with inflammation as measured by C-reactive protein (CRP) and interleukin 6 (IL-6). However, findings are inconsistent and effect sizes are small. The addition of soluble urokinase plasminogen activator receptor (suPAR), a new biomarker of chronic inflammation, may improve measurement of stress-related inflammatory burden. Objectives: To assess whether exposure to adverse experiences, stress, and violence is associated with an increase in suPAR levels in young people and to test the hypothesis that measuring suPAR in addition to CRP or IL-6 levels improves the assessment of the inflammatory burden associated with early-life stress. Design, Setting, and Participants: This cohort study included 1391 participants from a 1994 to 1995 birth cohort of twins from the nationally representative Environmental Risk Longitudinal Twin Study in the United Kingdom. Participants were followed up until 18 years of age (93% retention). Plasma samples were analyzed in July 2018, and statistical analysis was performed from October 1, 2018, to May 31, 2019. Exposures: Adverse childhood experiences and childhood and adolescent experience of stress and violence exposure. Main Outcomes and Measures: Plasma CRP, IL-6, and suPAR levels at 18 years of age. Results: Among 1391 young people (mean [SD] age, 18.4 [0.36] years; 733 [52.7%] female), those who had been exposed to stressful experiences had elevated suPAR levels by 18 years of age after controlling for sex, body mass index, and smoking: 0.03-ng/mL (95% CI, 0.01-0.05 ng/mL) increase in suPAR per each additional adverse childhood experience, 0.09-ng/mL (95% CI, 0.01-0.17 ng/mL) increase in suPAR per each additional severe childhood experience of stress or violence, and 0.04-ng/mL (95% CI, -0.02 to 0.10 ng/mL) increase in suPAR per each additional severe adolescent experience of stress or violence. Individuals exposed to multiple types of violence in both childhood and adolescence had 0.26-ng/mL (95% CI, 0.07-0.45 ng/mL) higher suPAR levels compared with children who did not experience stress or violence. These stress-exposed young people were significantly more likely to have elevated suPAR levels at 18 years of age even if they did not have elevated CRP or IL-6 levels. Measuring suPAR in addition to CRP or IL-6 increased the association between stress exposure and inflammatory burden. For example, after adjusting for CRP and IL-6 levels, each additional adverse childhood experience was associated with a 0.05-mL (95% CI, 0.03-0.07 ng/mL) increase in suPAR, each additional severe childhood experience of stress or violence was associated with a 0.14-ng/mL (95% CI, 0.06-0.22 ng/mL) increase in suPAR, and each additional severe adolescent experience of stress or violence was associated with a 0.10-ng/mL (95% CI, 0.04-0.16 ng/mL) increase in suPAR. Conclusions and Relevance: The results suggest that adult inflammation is associated with childhood exposure to stress. Adding information about suPAR to traditional biomarkers of inflammation may improve the measurement of inflammatory burden associated with exposure to stress and violence.

Effects of 1 year of exercise training versus combined exercise training and weight loss on body composition, low-grade inflammation and lipids in overweight patients with coronary artery disease: a randomized trial.

BACKGROUND: Dyslipidaemia and low-grade inflammation are central in atherogenesis and linked to overweight and physical inactivity. Lifestyle changes are important in secondary prevention of coronary artery disease (CAD). We compared the effects of combined weight loss and interval training with interval training alone on physical fitness, body composition, dyslipidaemia and low-grade inflammation in overweight, sedentary participants with CAD. METHODS: Seventy CAD patients, BMI 28-40 kg/m2 and age 45-75 years were randomised to (1) 12 weeks' aerobic interval training (AIT) at 90% of peak heart rate three times/week followed by 40 weeks' AIT twice weekly or (2) a low energy diet (LED) (800-1000 kcal/day) for 8-10 weeks followed by 40 weeks' weight maintenance including AIT twice weekly and a high-protein/low-glycaemic load diet. Effects of the intervention were evaluated by physical fitness, body weight and composition. Dyslipidaemia was described using both biochemical analysis of lipid concentrations and lipoprotein particle subclass distribution determined by density profiling. Low-grade inflammation was determined by C-reactive protein, soluble urokinase-type plasminogen activator receptor and tumour necrosis factor α. Effects on continuous outcomes were tested by mixed-models analysis. RESULTS: Twenty-six (74%) AIT and 29 (83%) LED + AIT participants completed the study. At baseline subject included 43 (78%) men; subjects averages were: age 63 years (6.2), body weight 95.9 kg (12.2) and VO2peak 20.7 mL O2/kg/min (4.9). Forty-six (84%) had pre-diabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance). LED + AIT reduced body weight by 7.2 kg (- 8.4; - 6.1) and waist circumference by 6.6 cm (- 7.7; - 5.5) compared to 1.7 kg (- 0.7; - 2.6) and 3.3 cm (- 5.1; - 1.5) after AIT (within-group p < 0.001, between-group p < 0.001 and p = 0.018, respectively). Treatments caused similar changes in VO2peak and lowering of total cholesterol, triglycerides, non-HDL cholesterol and low-grade inflammation. A shift toward larger HDL particles was seen following LED + AIT while AIT elicited no change. CONCLUSIONS: Both interventions were feasible. Both groups obtained improvements in VO2peak, serum-lipids and inflammation with superior weight loss and greater central fat loss following LED + AIT. Combined LED induced weight loss and exercise can be recommended to CAD patients. Trial registration NCT01724567, November 12, 2012, retrospectively registered (enrolment ended in April 2013).

Soluble urokinase plasminogen activator receptor is linearly associated with dietary quality and predicts mortality.

Chronic inflammation is associated with disease risk and mortality in the general population. Soluble urokinase plasminogen activator receptor (suPAR) is a stable marker of chronic inflammation, and a higher serum-concentration of suPAR is found in individuals with an unhealthy lifestyle such as smoking. This article investigates the association between suPAR and dietary quality measured with the dietary quality score (DQS). The DQS is an index of the overall quality of an individual's dietary habits assessed through a self-administered FFQ. Furthermore, this article investigates the association of both suPAR and the DQS with CVD risk and mortality in the general Danish population. We analysed 5347 individuals aged 30-60 years from the Danish Inter99 study cohort. Multiple linear regression analyses showed a linear inverse association between the DQS and suPAR (P=0·0005). Cox regression analyses showed an 18 (95 % CI 9, 26) % increase in the risk of death from any cause with each 1 ng/ml increase in suPAR. We found no significant association between the DQS and the mortality (hazard ratio: 1·16, 95 % CI 0·79, 1·69). All analyses were adjusted for demographics and lifestyle factors. The association between the DQS and suPAR on the one hand and suPAR and mortality on the other supports the argument that low dietary quality may constitute a health risk through its influence on chronic inflammation. Future research should examine whether suPAR is modifiable through changes in dietary habits.

Healthy lifestyles reduce suPAR and mortality in a Danish general population study.

BACKGROUND: The plasma level of the inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) is a strong predictor of disease development and premature mortality in the general population. Unhealthy lifestyle habits such as smoking or unhealthy eating is known to elevate the suPAR level. We aimed to investigate whether change in lifestyle habits impact on the suPAR level, and whether the resultant levels are associated with mortality. RESULTS: Paired suPAR measurements from baseline- and the 5-year visit of the population-based Inter99 study were compared with the habits of diet, smoking, alcohol consumption, and physical activity. Paired suPAR measurements for 3225 individuals were analyzed by linear regression, adjusted for demographics and lifestyle habits. Compared to individuals with a healthy lifestyle, an unhealthy diet, low physical activity, and daily smoking were associated with a 5.9, 12.8, and 17.6% higher 5-year suPAR, respectively. During 6.1 years of follow-up after the 5-year visit, 1.6% of those with a low suPAR (mean 2.93 ng/ml) died compared with 3.8% of individuals with a high suPAR (mean 4.73 ng/ml), P <  0.001. In Cox regression analysis, adjusted for demographics and lifestyle, the hazard ratio for mortality per 5-year suPAR doubling was 2.03 (95% CI: 1.22-3.37). CONCLUSION: Lifestyle has a considerable impact on suPAR levels; the combination of unhealthy habits was associated with 44% higher 5-year suPAR values and the 5-year suPAR was a strong predictor of mortality. We propose suPAR as a candidate biomarker for lifestyle changes as well as the subsequent risk of mortality.

Cumulative childhood risk is associated with a new measure of chronic inflammation in adulthood.

BACKGROUND: Childhood risk factors are associated with elevated inflammatory biomarkers in adulthood, but it is unknown whether these risk factors are associated with increased adult levels of the chronic inflammation marker soluble urokinase plasminogen activator receptor (suPAR). We aimed to test the hypothesis that childhood exposure to risk factors for adult disease is associated with elevated suPAR in adulthood and to compare suPAR with the oft-reported inflammatory biomarker C-reactive protein (CRP). METHODS: Prospective study of a population-representative 1972-1973 birth cohort; the Dunedin Multidisciplinary Health and Development Study observed participants to age 38 years. Main childhood predictors were poor health, socioeconomic disadvantage, adverse childhood experiences (ACEs), low IQ, and poor self-control. Main adult outcomes were adulthood inflammation measured as suPAR and high-sensitivity CRP (hsCRP). RESULTS: Participants with available plasma samples at age 38 were included (N = 837, 50.5% male). suPAR (mean 2.40 ng/ml; SD 0.91) was positively correlated with hsCRP (r 0.15, p < .001). After controlling for sex, body mass index (BMI), and smoking, children who experienced more ACEs, lower IQ, or had poorer self-control showed elevated adult suPAR. When the five childhood risks were aggregated into a Cumulative Childhood Risk index, and controlling for sex, BMI, and smoking, Cumulative Childhood Risk was associated with higher suPAR (b 0.10; SE 0.03; p = .002). Cumulative Childhood Risk predicted elevated suPAR, after controlling for hsCRP (b 0.18; SE 0.03; p < .001). CONCLUSIONS: Exposure to more childhood risk factors was associated with higher suPAR levels, independent of CRP. suPAR is a useful addition to studies connecting childhood risk to adult inflammatory burden.