Soluble urokinase plasminogen activator receptor suPAR as a marker for inflammation in pediatric inflammatory bowel disease

The Soluble Urokinase Plasminogen Activator Receptor as a Severity Biomarker in Children With Acute COVID-19 or Multisystem Inflammatory Syndrome

BACKGROUND

Elevated soluble urokinase plasminogen activator receptor (suPAR) has been associated with a poor prognosis in serious infections. The aim of this study was to evaluate the clinical value of suPAR in children with acute coronavirus disease 2019 (COVID-19) or multisystem inflammatory syndrome (MIS-C).

METHODS

Serum suPAR was measured using the suPARnostic AUTO Flex enzyme-linked immunosorbent assay in hospitalized children with COVID-19, MIS-C, bacterial pneumonia, and healthy controls.

RESULTS

A total of 211 children with a mean (±SD) age of 6.9 ± 4.96 years were tested; with COVID-19: 59 (28%), MIS-C: 36 (17%), pneumonia: 78 (37%) and healthy controls: 38 (18%). In the acute phase, the levels of suPAR (mean ± SD) were: MIS-C: 8.11 ± 2.80 ng/mL, COVID-19: 4.91 ± 1.90 ng/mL, pneumonia: 4.25 ± 1.44 ng/mL and controls: 2.09 ± 0.47 ng/mL ( P < 0.001). Children with acute COVID-19 and a severe or moderate clinical presentation had higher values than those with mild symptoms: 5.79 ± 1.58 versus 5.40 ± 1.94 versus 3.19 ± 0.73 ng/mL, respectively ( P < 0.001). In the MIS-C group, children hospitalized in the intensive care unit and in need of mechanical ventilation had higher suPAR than those who were not admitted to an intensive care unit: 9.32 ± 3.06 versus 7.13 ± 2.19 ng/mL, respectively ( P = 0.023). In children with COVID-19 or MIS-C, a correlation was detected between suPAR values and length of hospitalization ( rs = 0.418, P < 0.001).

CONCLUSIONS

The findings suggest that suPAR may be a valuable biomarker of disease severity in children with COVID-19 or MIS-C. This could facilitate the identification of children in need of intensive anti-inflammatory treatment, as it has been shown in adults with severe COVID-19.

The Roles of Fibrinolytic Factors in Bone Destruction Caused by Inflammation

Chronic inflammatory diseases, such as rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus, Crohn's disease, periodontitis, and carcinoma metastasis frequently result in bone destruction. Pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-17 are known to influence bone loss by promoting the differentiation and activation of osteoclasts. Fibrinolytic factors, such as plasminogen (Plg), plasmin, urokinase-type plasminogen activator (uPA), its receptor (uPAR), tissue-type plasminogen activator (tPA), α2-antiplasmin (α2AP), and plasminogen activator inhibitor-1 (PAI-1) are expressed in osteoclasts and osteoblasts and are considered essential in maintaining bone homeostasis by regulating the functions of both osteoclasts and osteoblasts. Additionally, fibrinolytic factors are associated with the regulation of inflammation and the immune system. This review explores the roles of fibrinolytic factors in bone destruction caused by inflammation.

Evaluation of plasma soluble urokinase plasminogen activator receptor (SuPAR) levels in ulcerative colitis

BACKGROUND AND STUDY AIM

Soluble urokinase plasminogen activator receptor (SuPAR), a soluble form of the urokinase-type plasminogen activator receptor, is a biomarker produced by macrophages, monocytes, neutrophils, active T cells, endothelial cells, and circulating tumor cells. SuPAR is a novel biomarker showing altered inflammation in many inflammatory diseases. This study aims to investigate the SuPAR level in ulcerative colitis (UC) patients, and to evaluate the SuPAR level in active, and remission patients.

PATIENTS AND METHODS

Patient and healthy control SuPAR levels were analyzed by immunoassay method. SuPAR levels between UC patients and control group were compared. The difference between SuPAR levels in patients with active UC and UC in remission was analyzed. The relationship between C-reactive protein level, Total Mayo score, Mayo Endoscopic score used to predict disease activity, and amount of SuPAR were evaluated.

RESULTS

SuPAR levels were determined in the UC patient group (2170,3 ± 121,0 pg/ml), and healthy controls (2130,7 ± 164,8 pg/ml) (p = 0. 805). Median SuPAR levels were determined in moderate UC (2479 pg/ml), mild UC (1944 pg/ml), and patients in remission (1774 pg/ml) (p = 0,207). There were no significant relationships between SuPAR levels and CRP levels, Total Mayo score, disease duration in the UC group (r = 0.177, r = 0.267, and r = 0,007; respectively p > 0.05). A slightly positive correlation was found between Mayo Endoscopic Score and SuPAR level (r = 0.303; p = 0.031).

CONCLUSION

SuPAR is of limited value in the diagnosis of ulcerative colitis and in the assessment of disease activation.

Serum levels of soluble urokinase plasminogen activator receptor in juvenile idiopathic arthritis: a single-center Swedish case-control study

OBJECTIVES

Reliable biomarkers in the early stages of idiopathic arthritis (JIA) are scarce and the disease heterogeneity makes it clinically challenging to predict the risk of joint damage. Biomarkers with prognostic potential are warranted in order to individualize treatment and follow-up in JIA. The soluble urokinase plasminogen activator receptor (suPAR) has been reported as an easily measurable biomarker for prognosis and severity in several rheumatic diseases but it has never been studied in JIA.

METHODS

Sera from 51 well-characterized patients with JIA and 50 age- and sex-matched control subjects were collected and stored for later analysis of suPAR. Patients were carefully followed clinically over 3 years and analysis of erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor (RF) and antibodies against cyclic citrullinated peptides (anti-CCP) were analyzed as part of clinical routine. Signs of joint erosions were evaluated by radiography.

RESULTS

Overall, the levels of suPAR did not differ significantly between JIA patients and controls but those with polyarticular involvement showed higher suPAR (p = 0.013). In addition, elevated suPAR were associated with joint erosions (p = 0.026). Two RF/anti-CCP negative individuals with erosions showed high levels of suPAR.

CONCLUSIONS

We present new data on the biomarker suPAR in JIA. Our results indicate that, apart from RF and anti-CCP, analysis of suPAR could be of additional value in assessing the risk of erosions. Analysis of suPAR early could potentially guide treatment decision-making in JIA, but our observations should be confirmed in prospective studies.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) in Autoimmune Rheumatic and Non Rheumatic Diseases

The soluble urokinase plasminogen activator receptor (suPAR) is the bioactive form of uPAR, a membrane-bound glycoprotein, and it is primarily expressed on the surface of immunologically active cells. Mirroring local inflammation and immune activation, suPAR has gained interest as a potential prognostic biomarker in several inflammatory diseases. Indeed, in many diseases, including cancer, diabetes, cardiovascular diseases, kidney diseases, and inflammatory disorders, higher suPAR concentrations have been associated with disease severity, disease relapse, and mortality. Our review describes and discusses the supporting literature concerning the promising role of suPAR as a biomarker in different autoimmune rheumatic and non-rheumatic diseases.

Urokinase-type plasminogen activator blockade ameliorates experimental colitis in mice

Although several angiogenesis-related factors are reportedly involved in the pathogenesis of ulcerative colitis (UC), the mechanisms by which they contribute to disease are unclear. We first examined the expression of angiogenesis-related factors in inflamed colorectal tissue of UC patients using antibody array, and identified the 5 factors with highest expression, which included matrix metalloproteinase-8, urokinase-type plasminogen activator (uPA), angiostatin/plasminogen, hepatocyte growth factor and endoglin. Subsequent real-time PCR experiments using additional colorectal tissues revealed that uPA mRNA levels were significantly higher in inflamed tissues than in non-inflamed tissues, and significantly correlated with the severity of UC. Mirror section immunohistochemistry revealed that uPA was expressed in the neutrophils of inflamed colorectal tissues. We administered dextran sulfate sodium (DSS) in drinking water to uPA knockout (uPA^-/-) mice, and found that the disease activity index in uPA^-/- mice was marginally lower and the histological score in uPA^-/- mice was significantly lower than those in wild-type mice, suggesting the importance of uPA in colitis. When an uPA-selective inhibitor, UK122, was administered to DSS-treated C57BL6J mice, the disease activity index and histological score in those mice were significantly lower compared with control mice. Multiple cytokine/chemokine assay using colorectal tissues from uPA^-/- and UK122-treated mice revealed significantly lowered level of RANTES. In conclusion, uPA was highly expressed in neutrophils of the inflamed mucosa of UC patients, and the expression level correlated with the severity of UC. Genetic uPA deletion or pharmacological uPA blockade significantly ameliorated colitis in mice, concomitant with downregulation of RANTES.

Soluble Urokinase Plasminogen Activator Receptor Levels Are Associated with Severity of Fibrosis in Patients with Primary Sclerosing Cholangitis

The soluble urokinase-type plasminogen activator receptor (suPAR) has evolved as a useful biomarker for different entities of chronic liver disease. However, its role in patients with primary sclerosing cholangitis (PSC) is obscure. We analyzed plasma levels of suPAR in 84 patients with PSC and compared them to 68 patients with inflammatory bowel disease (IBD) without PSC and to 40 healthy controls. Results are correlated with clinical records. suPAR concentrations were elevated in patients with PSC compared to patients with IBD only and to healthy controls (p < 0.001). Elevated suPAR levels were associated with the presence of liver cirrhosis (p < 0.001) and signs of portal hypertension (p < 0.001). suPAR revealed a high accuracy for the discrimination of the presence of liver cirrhosis comparable to previously validated noninvasive fibrosis markers (area under the curve (AUC) 0.802 (95%CI: 0.702−0.902)). Further, we demonstrated that suPAR levels may indicate the presence of acute cholangitis episodes (p < 0.001). Finally, despite the high proportion of PSC patients with IBD, presence of IBD and its disease activity did not influence circulating suPAR levels. suPAR represents a previously unrecognized biomarker for diagnosis and liver cirrhosis detection in patients with PSC. However, it does not appear to be confounded by intestinal inflammation in the context of IBD.

HIF-Dependent NFATC1 Activation Upregulates ITGA5 and PLAUR in Intestinal Epithelium in Inflammatory Bowel Disease

Intestinal epithelial cells exist in physiological hypoxia, leading to hypoxia-inducible factor (HIF) activation and supporting barrier function and cell metabolism of the intestinal epithelium. In contrast, pathological hypoxia is a common feature of some chronic disorders, including inflammatory bowel disease (IBD). This work was aimed at studying HIF-associated changes in the intestinal epithelium in IBD. In the first step, a list of genes responding to chemical activation of hypoxia was obtained in an in vitro intestinal cell model with RNA sequencing. Cobalt (II) chloride and oxyquinoline treatment of both undifferentiated and differentiated Caco-2 cells activate the HIF-signaling pathway according to gene set enrichment analysis. The core gene set responding to chemical hypoxia stimulation in the intestinal model included 115 upregulated and 69 downregulated genes. Of this set, protein product was detected for 32 genes, and fold changes in proteome and RNA sequencing significantly correlate. Analysis of publicly available RNA sequencing set of the intestinal epithelial cells of patients with IBD confirmed HIF-1 signaling pathway activation in sigmoid colon of patients with ulcerative colitis and terminal ileum of patients with Crohn's disease. Of the core gene set from the gut hypoxia model, expression activation of ITGA5 and PLAUR genes encoding integrin α5 and urokinase-type plasminogen activator receptor (uPAR) was detected in IBD specimens. The interaction of these molecules can activate cell migration and regenerative processes in the epithelium. Transcription factor analysis with the previously developed miRGTF tool revealed the possible role of HIF1A and NFATC1 in the regulation of ITGA5 and PLAUR gene expression. Detected genes can serve as markers of IBD progression and intestinal hypoxia.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) Independently Predicts Severity and Length of Hospitalisation in Patients With COVID-19

Background: Efficient healthcare based on prognostic variables in hospitalised patients with COVID-19 could reduce the risk of complications and death. Recently, soluble urokinase Plasminogen Activator Receptor (suPAR) was shown to predict respiratory failure, kidney injury, and clinical outcome in patients with SARS-CoV-2 infection. The aim of this study was to investigate the value of suPAR as a prognostic tool, in comparison with other variables, regarding disease severity and length of hospital stay in patients with COVID-19. Patients and Methods: Individuals hospitalised with COVID-19 (40 males, 20 females; median age 57.5 years) with a median symptom duration of 10 days and matched, healthy controls (n = 30) were included. Admission levels of suPAR were measured in serum by enzyme-linked immunosorbent assay. Blood cell counts, C-reactive protein (CRP) levels, lactate dehydrogenase (LDH), plasma creatinine and estimated glomerular filtration rates were analysed and oxygen demand, level of care and length of hospitalisation recorded. Results: Patients had significantly higher suPAR levels compared to controls (P < 0.001). Levels were higher in severely/critically (median 6.6 ng/mL) compared with moderately ill patients (median 5.0 ng/mL; P = 0.002). In addition, suPAR levels correlated with length of hospitalisation (rho = 0.35; P = 0.006). Besides suPAR, LDH, CRP, neutrophil count, neutrophil-to-monocyte and neutrophil-to-lymphocyte ratio, body mass index and chronic renal failure were discriminators of COVID-19 severity and/or predictors of length of hospitalisation. Conclusion: Admission levels of suPAR were higher in patients who developed severe/critical COVID-19 and associated with length of hospital stay. In addition, we showed that suPAR functioned as an independent predictor of COVID-19 disease severity.

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.

Soluble Vascular Biomarkers in Rheumatoid Arthritis and Ankylosing Spondylitis: Effects of 1-year Antitumor Necrosis Factor-α Therapy

OBJECTIVE

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) have been associated with cardiovascular disease. The treatment of arthritis by tumor necrosis factor-α (TNF-α) inhibitors may decrease the serum concentrations of vascular biomarkers. We determined circulating levels of oxidized low-density lipoprotein (oxLDL)/β₂ glycoprotein I (β₂-GPI) complexes, antibodies to 60 kDa heat shock protein (anti-Hsp60), soluble urokinase plasminogen activator receptor (suPAR), and B-type natriuretic peptide (BNP) fragment in sera of RA and AS patients undergoing anti-TNF treatment.

METHODS

Fifty-three patients with RA/AS were treated with etanercept or certolizumab pegol for 1 year. Circulating oxLDL/β₂-GPI complex (AtherOx), anti-Hsp60 IgG, and BNP8-29 fragment levels were assessed by ELISA. suPAR levels were determined by suPARnostic Quick Triage test. Flow-mediated vasodilation (FMD), carotid intima-media thickness (CIMT), and arterial pulse wave velocity (PWV) were determined by ultrasound.

RESULTS

One-year anti-TNF treatment significantly decreased oxLDL/β₂-GPI levels, as well as suPAR levels in patients with critically high suPAR levels at baseline. In RA, BNP levels were higher in seropositive vs seronegative patients. Serum levels of these vascular biomarkers variably correlated with lipids, anticitrullinated protein antibodies, rheumatoid factor, and C-reactive protein. CIMT positively correlated with BNP, and PWV with suPAR and anti-Hsp60, whereas FMD inversely associated with anti-Hsp60. In repeated measures ANOVA analysis, disease activity supported the effects of anti-TNF treatment on 12-month changes in oxLDL/β₂-GPI. CIMT supported the effects of therapy on changes in anti-Hsp60 and suPAR.

CONCLUSION

These biomarkers may be involved in the pathogenesis of atherosclerosis underlying RA/AS. TNF inhibition variably affects the serum levels of oxLDL/β₂-GPI, suPAR, and BNP.

Plasma level of soluble urokinase plasminogen activator receptor (suPAR) predicts long-term mortality after first acute alcohol-induced pancreatitis

BACKGROUND

Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker associated with inflammatory and certain malignancies. Earlier we have shown that plasma suPAR (P-suPAR) predicts severity of acute alcohol-induced pancreatitis (AAP) on admission. Our aim was to investigate whether P-suPAR levels predict AAP recurrences or mortality during long-term follow-up after first AAP.

METHODS

Eighty-three patients (median age 47.5, range 25-71 years) suffering their first AAP during 2001-2005 were recruited and followed prospectively for 9 years with a median follow-up time of 7.0 (range 0.3-9.8) years. P-suPAR was measured by enzyme-linked immunosorbent assay (ELISA) from the samples taken at follow-up visits. Survival was registered in November 2014.

RESULTS

P-suPAR level on admission or after recovery of the first AAP did not predict the recurrence of AAP. However, higher P-suPAR measured after recovery of first AAP (3.6 vs. 2.9 ng/mL) predicted mortality during follow-up period (hazard ratio 1.48, p = .008). Cut-off value for P-suPAR indicating a higher risk for 10-year mortality resulted a value of ≥3.4 ng/mL. When adjusted for other covariates, P-suPAR above cut-off level retained its statistical significance as an independent factor.

CONCLUSIONS

P-suPAR level on admission or after recovery of the first AAP does not predict the recurrence of AAP during long-term follow-up. However, P-suPAR ≥3.4 mg/mL measured after recovery from first AAP is associated with an increased risk of 10-year mortality as an independent factor. This can be used to detect patients with highest risk after AAP, in order to focus the preventive healthcare actions.

Soluble urokinase-type plasminogen activator receptor (suPAR) in patients with acute pancreatitis (AP) - Progress in prediction of AP severity

BACKGROUND

Soluble urokinase-type plasminogen activator receptor (suPAR) is a glycoprotein secreted during inflammation and infections. Moreover, increased levels of suPAR are observed after hypoxia and ischaemia. The aim of the study was to assess whether suPAR could represent a useful marker of acute pancreatitis (AP) severity.

PATIENTS AND METHODS

We have observed a cohort of 126 prospectively enrolled patients. Based on the presence of persistent organ failure (more than 48 h) and local complications (diagnosis of moderate AP [MSAP]), patients were classified into three groups: mild AP (MAP), moderate and severe AP (SAP). The blood samples were taken on admission for detecting suPAR concentrations.

RESULTS

AP was considered severe in 33 patients (26.2%), MSAP was found in 37 patients (29.4%), and MAP was found in 56 patients (44,4%). The AUC for SAP predicted by suPAR was 0.993. The calculated cut-off point for prognosis SAP is 4.75 ng/mL. The BISAP score of ≥3 for detection of SAP had sensitivity and specificity of 94.6% and 63.6%, respectively. The AUC for severity predicted by BISAP amounted to 0.916. Additionally, suPAR turned out to be a good predictor of fatal AP: for the cut-off point 7.05 ng/mL, the AUC was 0.917. The AUC for death prediction in AP patients based on the BISAP score ≥3 was 0.894.

CONCLUSIONS

suPAR concentration is a promising new diagnostic and prognostic indicator in SAP obtainable in the early stage of disease. Larger studies are recommended to evaluate this role further.

The diagnostic value of soluble urokinase plasminogen activator receptor (suPAR) compared to C-reactive protein (CRP) and procalcitonin (PCT) in children with systemic inflammatory response syndrome (SIRS)

BACKGROUND

The aim of the present study was to determine the diagnostic and prognostic values of suPAR and to compare them to CRP and PCT in pediatric patients with systemic inflammatory response syndrome (SIRS).

MATERIAL-METHODS

A prospective case-control study was performed.The study was performed in a tertiary university hospital which has a 649-bed capacity. Patients included 27 children with SIRS and 27 control subjects without any infection or immunosuppressive condition. Blood samples were obtained on the day of admission and on the 4-7th days of the hospital stay.

RESULTS

The median (min-max) serum levels of suPAR obtained on the first day of the admission were 10.06 (2.7-57.46) and 2.22 (1.08-5.13) ng/Ml for the SIRS group and control group, respectively. The median serum levels of suPAR in the SIRS group was significantly higher than that in the control group (p < 0.05). The serum suPAR levels was significantly higher in nonsurvivors than in survivors in SIRS group (p < 0.05). In the SIRS group, the area under the receiver operating characteristics curve (AUC^ROC) for suPAR revealed an optimum cut-off value, sensitivity, specificity, NPV and PPV of 0.978, 3.8 ng/mL, 96%, 96%, 96%, and 96%, respectively.

CONCLUSIONS

We conclude that suPAR does have diagnostic value in children with SIRS. Additionally, persistent high serum suPAR level predicts mortality in SIRS in children.

Assessment of disease activity in pediatric ulcerative colitis

To date, we encounter more and more pediatric patients with ulcerative colitis (UC). For yet unclear reasons, UC in pediatric patients seems to be a more aggressive and extensive disease than in their adult counterparts. In the majority of pediatric patients, the disease presents as pancolitis. The severity of the disease is reflected in the high use of corticosteroids and immunosuppressants and a high rate of surgery for medically refractory patients. The means by which to assess disease activity or to accurately predict its course are far from optimal. This review summarizes the current knowledge on the means for assessing UC activity in children. Research for developing new tools by which to monitor and forecast disease activity, are needed in all areas including invasive endoscopy, clinical evaluation, and treatment follow-up.

The diagnostic value of soluble urokinase plasminogen activator receptor compared with C-reactive protein and procalcitonin in children with febrile neutropenia

The aim of the present study was to determine the diagnostic value of soluble urokinase plasminogen activator receptor (suPAR) in pediatric patients with febrile neutropenia. A prospective case-control study was performed. Patients included 29 children with febrile neutropenia (FN) and 27 control subjects without any infection or immunosuppressive condition. Blood samples were obtained on the day of admission and on the 4th to 7th days of the hospital stay. The median (minimum-maximum) serum levels of suPAR obtained on the first day of the admission were 2.08 (0.93-9.42) and 2.22 (1.08-5.13) ng/mL for the FN group and the control group, respectively. The median serum levels of suPAR in the FN and control groups were not significantly different (P = .053). The mean serum suPAR level was significantly higher in nonsurvivors than in survivors in the FN group (P < .05). In the FN group, the area under the receiver operating characteristics curve (AUCROC) for suPAR was 0.546, but no optimum cutoff value, sensitivity, specificity, negative predictive value (NPV), or positive predictive value (PPV) was obtained. We conclude that suPAR is not useful as a diagnostic biomarker in children with febrile neutropenia; however, persistent high serum suPAR level may predict mortality in FN in children.

The urokinase plasminogen activator receptor (uPAR) controls macrophage phagocytosis in intestinal inflammation

OBJECTIVE

Inflammation plays crucial roles in the pathogenesis of several chronic inflammatory disorders, including Crohn's disease (CD) and UC, the two major forms of IBD. The urokinase plasminogen activator receptor (uPAR) exerts pleiotropic functions over the course of both physiological and pathological processes. uPAR not only has a key role in fibrinolysis but also modulates the development of protective immunity. Additionally, uPAR supports extracellular matrix degradation and regulates cell migration, adhesion and proliferation, thus influencing the development of inflammatory and immune responses. This study aimed to evaluate the role of uPAR in the pathogenesis of IBD.

DESIGN

The functional role of uPAR was assessed in established experimental models of colitis. uPAR deficiency effects on cytokine release, polarisation and bacterial phagocytosis were analysed in colonic macrophages. uPAR expression was analysed in surgical specimens collected from normal subjects and patients with IBD.

RESULTS

In mice, uPAR expression is positively regulated as colitis progresses. uPAR-KO mice displayed severe inflammation compared with wild-type littermates, as indicated by clinical assessment, endoscopy and colon histology. The absence of uPAR led to an increased production of inflammatory cytokines by macrophages that showed an M1 polarisation and impaired phagocytosis. In human IBD, CD68(+) macrophages derived from the inflamed mucosa expressed low levels of uPAR.

CONCLUSIONS

These findings point to uPAR as an essential component of intestinal macrophage functions and unravel a new potential target to control mucosal inflammation in IBD.

Soluble urokinase-type plasminogen activator levels are related to plasma cytokine levels but have low predictive value for mortality in trauma patients

INTRODUCTION

Soluble urokinase-type plasminogen activator (suPAR) represents a marker for immune activation and has predictive value in critically ill patients. The kinetics of suPAR and its correlation with the immune response and outcome in trauma patients are unknown.

METHODS

Plasma concentrations of inflammatory cytokines and suPAR were determined in adult trauma patient (n = 69) samples obtained by the Helicopter Emergency Medical Services at arrival at the emergency department (ED) and at days 1, 3, 5, 7, 10, and 14.

RESULTS

Initial suPAR levels were unrelated to injury severity score and higher in nonsurvivors compared with survivors, although no difference was observed between early and late mortality. The area under the receiver operating characteristic curve to predict mortality was 0.6 (95% confidence interval, 0.48-0.72). Soluble urokinase-type plasminogen activator levels increased over time in 94% of patients, although suPAR increase did not precede death. Tumor necrosis factor α at the ED correlated with suPAR at that time point, whereas concentrations of other proinflammatory cytokines at the ED correlated with suPAR levels at days 1 and 5.

CONCLUSIONS

After trauma, initial suPAR plasma concentrations are higher in nonsurvivors compared with survivors, but its predictive value is low. Soluble urokinase-type plasminogen activator levels increase over time after trauma, and concentrations at later time points are related to cytokine levels at the ED.

Serum soluble urokinase-type plasminogen activator receptor levels and idiopathic FSGS in children: a single-center report

BACKGROUND AND OBJECTIVES

FSGS is the primary cause of childhood nephrotic syndrome leading to ESRD. Permeability factors, including circulating serum soluble urokinase-type plasminogen activator receptor (suPAR), have been postulated as putative causes in adults with primary FSGS. Similar results have yet to be proven in children.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This cross-sectional single-center study assessed the association of serum suPAR in children with FSGS or other glomerular and nonglomerular kidney diseases.

RESULTS

This study examined 110 samples retrieved from 99 individuals (between January 2011 and April 2012), aged 1-21 years; of these individuals, 20 had primary FSGS, 24 had non-FSGS glomerular disease, 26 had nonglomerular kidney disease, and 29 were healthy controls. suPAR levels were not significantly different in children with FSGS, non-FSGS glomerular disease, and healthy controls (P>0.05). However, suPAR levels (median [25%-75%]) were higher in children with nonglomerular kidney disease (3385 pg/ml [2695-4392]) versus FSGS (2487 pg/ml [2191-3351]; P<0.05). Female patients with nephrotic-range proteinuria (U-Pr/Cr >2) had lower suPAR levels than those without proteinuria (2380 pg/ml [2116-2571] versus 3125 pg/ml [2516-4198], respectively; P<0.001). This trend was not seen among male participants; suPAR levels in all female participants were lower than in male participants (P=0.03). Thirty-four patients studied were kidney transplant recipients; transplant status was not associated with suPAR levels in patients with FSGS or non-FSGS diagnoses, independent of proteinuria, race, or sex (P>0.05).

CONCLUSIONS

On the basis of these results, circulating suPAR is unlikely the leading cause for childhood idiopathic FSGS.