Search

The proline-specific enzymes dipeptidyl peptidase 4 (DPP4), prolylcarboxypeptidase (PRCP), fibroblast activation protein α (FAP) and prolyl oligopeptidase (PREP) are known for their involvement in the immune system and blood pressure regulation. Only very limited information is currently available on their enzymatic activity and possible involvement in patients with sepsis and septic-shock. The activity of the enzymes was measured in EDTA-plasma of patients admitted to the intensive care unit (ICU): 40 septic shock patients (sepsis-2) and 22 ICU control patients after major intracranial surgery. These data were used to generate receiver operating characteristic (ROC) curves. A survival analysis (at 90 days) and an association study with other parameters was performed. PRCP (day 1) and PREP (all days) enzymatic activities were higher in septic shock patients compared to controls. In contrast, FAP and DPP4 were lower in these patients on all studied time points. Since large differences were found, ROC curves were generated and these yielded area under the curve (AUC) values for PREP, FAP and DPP4 of 0.88 (CI: 0.80–0.96), 0.94 (CI: 0.89–0.99) and 0.86 (CI: 0.77–0.95), respectively. PRCP had a lower predicting value with an AUC of 0.71 (CI: 0.58–0.83). A nominally significant association was observed between survival and the DPP4 enzymatic activity at day 1 (p

Background Prolyl carboxypeptidase (PRCP) is involved in the regulation of body weight, likely by hydro-lysing alpha-melanocyte-stimulating hormone and apelin in the hypothalamus and in the periphery. A link between PRCP protein concentrations in plasma and metabolic disorders has been reported. In this study, we investigated the distribution of circulating PRCP activity and assessed its relation with body weight and adipose tissue in obese patients and patients who significantly lost weight. Methods PRCP activity was measured using reversed-phase high-performance liquid chromatography in different isolated blood fractions and primary human cells to investigate the distribution of circulating PRCP. PRCP activity was measured in serum of individuals (n = 75) categorized based on their body mass index (BMI < 25.0; 25.0–29.9; 30.0–39.9; 40.0 kg/ m2) and the diagnosis of metabolic syndrome. Differences in serum PRCP activity were determined before and six months after weight loss, either by diet (n = 45) or by bariatric surgery (n = 24). Potential correlations between serum PRCP activity and several metabolic and biochemical parameters were assessed. Additionally, plasma PRCP concentrations were quantified using a sensitive ELISA in the bariatric surgery group. Results White blood cells and plasma contributed the most to circulating PRCP activity. Serum PRCP activity in lean subjects was 0.83 ± 0.04 U/L and increased significantly with a rising BMI (p

Background Dipeptidyl peptidase IV (DPPIV) inhibition may be a promising therapeutic strategy for acute stroke treatment, given its potential to prolong the biological half-life of neuroprotective substrates. A related protease, fibroblast activation protein (FAP), was recently shown to inactivate the same substrates. Therefore, it should also be investigated as a potential target in stroke. Aims To investigate whether stroke severity and outcome correlates with DPPIV and FAP activities and their kinetics shortly after acute ischemic stroke. Methods DPPIV and FAP activities were analyzed in the serum of 50 hyperacute stroke patients at admission, 1 day, 3 days and 7 days after stroke onset and in 50 age-matched healthy controls. This was done as part of the Middelheims Interdisciplinary Stroke Study. Results DPPIV activity tended to increase shortly after stroke compared to the control population. DPPIV and FAP activities steadily decreased in the first week after stroke onset. Higher infarct volumes (≥ 5 ml) and a more severe stroke (NIHSS > 7) at admission were correlated with a stronger decrease in the activities of both enzymes. Moreover, these patients more often developed a progressive stroke, were more often institutionalized. Conclusions Patients with a stronger increase in DPPIV activity at admission and decrease in the activity of both DPPIV and FAP during the first week after stroke onset had a more severe stroke and worse short term outcomes.

Background The proteolytic regulation of peptides involved in feeding behavior is poorly understood. Prolyl carboxypeptidase (PRCP) is particularly known for its role in body weight control by converting the anorexigenic peptide, α-melanocyte-stimulating hormone 1–13 into the inactive form 1–12. The purpose of this study was to characterize purified human PRCP, to investigate its substrate specificity and to discover novel substrates linked to obesity. Pyroglutamated apelin-13, ghrelin, enterostatin and obestatin were investigated since these are feeding-regulating peptides with potential cleaving sites for PRCP. Methods PRCP was purified from human placenta and identified using western blotting and mass spectrometry. The kinetic parameters of purified and commercially available PRCP for known and potential peptide substrates were determined and compared using a RP-HPLC activity assay, isothermal titration calorimetry and mass spectrometry. Results PRCP was purified 575-fold from human placenta and succesfully identified as human lysosomal Pro-X carboxypeptidase. Purified and recombinant PRCP had similar substrate specificity with angiotensin III as the substrate of preference. Pyroglutamated apelin-13 was observed to be a novel substrate for human PRCP in vitro and PRCP-dependent cleavage was shown in a human umbilical vein endothelial cell culture experiment. Other potential substrates e.g. obestatin, ghrelin and enterostatin were not hydrolyzed by PRCP. Conclusion These results show that placenta is a good source of human PRCP and that PRCP removes the C-terminal phenylalanine from pyroglutamated apelin-13. For the first time, PRCP is identified as an apelin-cleaving enzyme. This finding adds evidence to the hypothesis that PRCP plays a role in energy homeostasis.

Aim/Purpose of the Study: Activation of the renin-angiotensin system leading to increased angiotensin-(1–7) (Ang-(1–7)) and decreased angiotensin 2 (Ang 2) levels may be a new therapeutic approach to reduce acute lung injury. Prolylcarboxypeptidase (PRCP) and prolyloligopeptidase (PREP) are capable of hydrolyzing Ang 2 into Ang-(1–7). However, their relation with circulating Ang 2 levels after lung ischemia–reperfusion injury (LIRI) has never been explored. This study determines whether the activity and expression of PRCP and PREP in plasma and lung tissue is related to circulating Ang 2 levels in a murine model of LIRI. Materials and Methods: LIRI in Swiss mice (6 animals per group) was induced by temporary left lung hilar clamping (1 h) followed by 0, 1 or 24 h of reperfusion. Animals in the sham group received thoracotomy only. PRCP activity was measured via RP-HPLC, PREP activity using a fluorogenic substrate and plasma Ang 2 levels via ELISA. Western blotting was used to determine the PRCP and PREP protein expression profiles in left lung tissue. Results: Plasma Ang 2 levels significantly rise after lung ischemia and remain increased after 1 h and 24 h of reperfusion compared to the sham group. While a significant decrease in plasma PREP activity was found after 24 h of reperfusion, a transient increase in plasma PRCP activity was observed after ischemia. However, no correlation with plasma Ang 2 levels could be demonstrated. The activity profiles of PRCP and PREP and the protein expression of PRCP in the lung tissues remained unchanged after LIRI. Conclusions: LIRI causes a dysregulation of circulating Ang 2 levels and plasma PREP activity, although no direct link between both phenomena could be shown. The activity profile of pulmonary PRCP and PREP was not significantly changed after LIRI, which implies a minor role for local PRCP and PREP in the ischemic lung itself.

Prolyl carboxypeptidase (PRCP) is an enzyme associated with cerebrovascular risk factors such as hypertension, diabetes mellitus, obesity and hyperlipidemia. We aim to evaluate the relation between serum PRCP activity and severity, evolution and outcome of acute ischemic stroke. We used a specific RP-HPLC activity assay to measure PRCP activity in serum of 50 stroke patients at admission, and at 24 h, 72 h and 7 days after stroke onset to assess correlations with stroke severity based on the National Institutes of Health Stroke scale score (NIHSS), infarct volume on brain MRI scan, stroke outcome based on the modified Rankin scale (mRS) and mortality at 3 months after stroke. The average PRCP activity in serum decreased significantly the first 24 h after stroke onset and returned to baseline values at day 7. High NIHSS scores and infarct volumes at admission were related with a more pronounced decrease of PRCP in the first 24 h after stroke (ΔPRCP24, r = 0.31, P < 0.05; r = 0.30, P < 0.05). In addition, patients who displayed a more pronounced decrease in PRCP levels during the first 24 h after stroke were more likely to be institutionalized upon discharge (n = 21) (ΔPRCP24 ± SD, 0.05 ± 0.10 U/L vs. 0.17 ± 0.14 U/L, P = 0.001). The decrease in PRCP levels in the first 24 h after stroke onset is associated with stroke severity and an unfavourable short-term stroke outcome.