Relationship of Circulating Soluble Urokinase Plasminogen Activator Receptor (suPAR) Levels to Disease Control in Asthma and Asthmatic Pregnancy

Asthma has a high burden of morbidity if not controlled and may frequently complicate pregnancy, posing a risk for pregnancy outcomes. Elevated plasma level of the inflammatory biomarker soluble urokinase plasminogen activator receptor (suPAR) is related to a worse prognosis in many conditions such as infectious, autoimmune, or pregnancy-related diseases; however the value of suPAR in asthma and asthmatic pregnancy is unknown. The present study aimed to investigate the suPAR, CRP and IL-6 levels in asthma (asthmatic non-pregnant, ANP; N = 38; female N = 27) and asthmatic pregnancy (AP; N = 15), compared to healthy non-pregnant controls (HNP; N = 29; female N = 19) and to healthy pregnant women (HP; N = 58). The relationship between suPAR levels and asthma control was also evaluated. The diagnostic efficacy of suPAR in asthma control was analyzed using ROC analysis. IL-6 and CRP levels were comparable in all study groups. Circulating suPAR levels were lower in HP and AP than in HNP and ANP subjects, respectively (2.01 [1.81-2.38] and 2.39 [2.07-2.69] vs. 2.60 [1.82-3.49] and 2.84 [2.33-3.72] ng/mL, respectively, p = 0.0001). suPAR and airway resistance correlated in ANP (r = 0.47, p = 0.004). ROC analysis of suPAR values in ANP patients with PEF above and below 80% yielded an AUC of 0.75 (95% CI: 0.57-0.92, p = 0.023) and with ACT total score above and below 20 an AUC of 0.80 (95% CI: 0.64-0.95, p = 0.006). The cut-off value of suPAR to discriminate between controlled and not controlled AP and ANP was 4.04 ng/mL. In conclusion, suPAR may help the objective assessment of asthma control, since it correlates with airway resistance and has good sensitivity in the detection of impaired asthma control. Decrease in circulating suPAR levels detected both in healthy and asthmatic pregnant women presumably represents pregnancy induced immune tolerance

Cleavage of the urokinase receptor (uPAR) on oral cancer cells : regulation by transforming growth factor - beta 1 (TGF-beta 1) and potential effects on migration and invasion

Background: Urokinase plasminogen activator (uPA) receptor (uPAR) is up-regulated at the invasive tumour front of human oral squamous cell carcinoma (OSCC), indicating a role for uPAR in tumour progression. We previously observed elevated expression of uPAR at the tumour-stroma interface in a mouse model for OSCC, which was associated with increased proteolytic activity. The tumour microenvironment regulated uPAR expression, as well as its glycosylation and cleavage. Both full-length- and cleaved uPAR (uPAR (II-III)) are involved in highly regulated processes such as cell signalling, proliferation, migration, stem cell mobilization and invasion. The aim of the current study was to analyse tumour associated factors and their effect on uPAR cleavage, and the potential implications for cell proliferation, migration and invasion. Methods: Mouse uPAR was stably overexpressed in the mouse OSCC cell line AT84. The ratio of full-length versus cleaved uPAR as analysed by Western blotting and its regulation was assessed by addition of different protease inhibitors and transforming growth factor - beta 1 (TGF-beta 1). The role of uPAR cleavage in cell proliferation and migration was analysed using real- time cell analysis and invasion was assessed using the myoma invasion model. Results: We found that when uPAR was overexpressed a proportion of the receptor was cleaved, thus the cells presented both full-length uPAR and uPAR (II-III). Cleavage was mainly performed by serine proteases and urokinase plasminogen activator (uPA) in particular. When the OSCC cells were stimulated with TGF-beta 1, the production of the uPA inhibitor PAI-1 was increased, resulting in a reduction of uPAR cleavage. By inhibiting cleavage of uPAR, cell migration was reduced, and by inhibiting uPA activity, invasion was reduced. We could also show that medium containing soluble uPAR (suPAR), and cleaved soluble uPAR (suPAR (II-III)), induced migration in OSCC cells with low endogenous levels of uPAR. Conclusions: These results show that soluble factors in the tumour microenvironment, such as TGF-beta 1, PAI-1 and uPA, can influence the ratio of full length and uPAR (II-III) and thereby potentially effect cell migration and invasion. Resolving how uPAR cleavage is controlled is therefore vital for understanding how OSCC progresses and potentially provides new targets for therapy.Peer reviewe

Preoperative plasma soluble urokinase plasminogen activator receptor as a prognostic marker in rectal cancer patients. An EORTC-receptor and Biomarker Group collaboration

Background and aims: Since approximately 30% of patients with Dukes' stage B colorectal cancer will experience disease recurrence within five years of primary treatment, current staging of patients with early colorectal cancer apparently fails to adequately predict patient outcome. It has previously been shown that the preoperative plasma concentration of soluble urokinase plasminogen activator receptor (suPAR) is associated with the survival of patients with early colorectal cancer. In this study we sought to confirm the independent prognostic value of suPAR in rectal cancer. Methods: suPAR was retrospectively determined by two different versions of a suPAR ELISA in preoperatively collected plasma samples from a Swedish (n=354) and a Danish (n=255) cohort of rectal cancer patients. Results: In both cohorts the suPAR concentration was significantly higher in Dukes' stage D patients than in Dukes' stage A-C patients (p < 0.0001). Among Dukes' stage A-C patients, no differences in median suPAR values were seen. In univariate analysis, continuous suPAR was found to be associated with survival (p < 0.0001 in both cohorts). Of particular interest was that similar results were obtained for Dukes' stage A and B patients when analyzed separately. In multivariate analysis, continuous suPAR was found in both cohorts to be independent of Dukes' stage. Conclusions: This study confirms that the preoperative concentration of plasma suPAR contains independent prognostic information on patients with rectal cancer. This result was independent of the two different versions of an in-house suPAR ELISA used to perform the analyses. The next step. in the evaluation of suPAR as a prognostic parameter in rectal cancer will be to launch an appropriately dimensioned prospective study where the benefit of applying preoperative plasma suPAR measurement to clinical decision-making regarding adjuvant therapy is assessed