Prolidase could be considered a sign of inflammation associated with cigarette smoking

Objectives

Smoking causes inflammation, thickening, and narrowing of the airways. This inflammatory process is a reaction to free radicals and oxidants. Smoking affects collagen metabolism and tissue remodeling. Prolidase enzyme hydrolyzes iminodipeptides with hydroxyproline and C terminal proline. It plays a crucial role in the metabolism of collagen and the remodeling of the matrix. The present study aims to reveal the association of prolidase with inflammation caused by smoking and to compare serum prolidase levels with oxidative-antioxidative status in healthy individuals.

Methods

A total of 76 participants (38 smokers and 38 nonsmokers) were involved in the present study. Serum cotinine levels were measured to show the exposure to nicotine in tobacco smoke by using the competitive inhibition enzyme immunoassay method. Serum prolidase, total oxidant status (TOS), and total antioxidant status (TAS) were determined by the enzyme-linked immunosorbent (ELISA) method, respectively. The correlation between smoking, serum prolidase levels, TOS, and TAS was investigated.

Results

TAS and serum prolidase levels of smokers were considerably lower than those in non-smokers (p < 0.001, p = 0.012 respectively). However, no differences were observed in TOS between the two groups. There was no statistically significant correlation between serum prolidase levels, TAS, and TOS. Moreover, no relationship was observed between respiratory function parameters and serum prolidase levels.

Conclusion

To the best of our knowledge, the present study is the first study to demonstrate the role of prolidase in smoking-related inflammation. The results achieved in the present study suggest that smoking creates an imbalance in the oxidant-antioxidant activity. Smoking decreases prolidase levels, leading to decreased collagen turnover. Chronic pulmonary disease might be related to this decrease in collagen turnover.

KLF6 activates Sp1-mediated prolidase transcription during TGF-β1 signaling

Prolidase (PEPD) is the only hydrolase that cleaves the dipeptides containing C-terminal proline or hydroxyproline-the rate-limiting step in collagen biosynthesis. However, the molecular regulation of prolidase expression remains largely unknown. In this study, we have identified overlapping binding sites for the transcription factors Krüppel-like factor 6 (KLF6) and Specificity protein 1 (Sp1) in the PEPD promoter and demonstrate that KLF6/Sp1 transcriptionally regulate prolidase expression. By cloning the PEPD promoter into a luciferase reporter and through site-directed deletion, we pinpointed the minimal sequences required for KLF6 and Sp1-mediated PEPD promoter-driven transcription. Interestingly, Sp1 inhibition abrogated KLF6-mediated PEPD promoter activity, suggesting that Sp1 is required for the basal expression of prolidase. We further studied the regulation of PEPD by KLF6 and Sp1 during transforming growth factor β1 (TGF-β1) signaling, since both KLF6 and Sp1 are key players in TGF-β1 mediated collagen biosynthesis. Mouse and human fibroblasts exposed to TGF-β1 resulted in the induction of PEPD transcription and prolidase expression. Inhibition of TGF-β1 signaling abrogated PEPD promoter-driven transcriptional activity of KLF6 and Sp1. Knock-down of KLF6 as well as Sp1 inhibition also reduced prolidase expression. Chromatin immunoprecipitation assay supported direct binding of KLF6 and Sp1 to the PEPD promoter and this binding was enriched by TGF-β1 treatment. Finally, immunofluorescence studies showed that KLF6 co-operates with Sp1 in the nucleus to activate prolidase expression and enhance collagen biosynthesis. Collectively, our results identify functional elements of the PEPD promoter for KLF6 and Sp1-mediated transcriptional activation and describe the molecular mechanism of prolidase expression.

Proline Metabolism in WHO G4 Gliomas Is Altered as Compared to Unaffected Brain Tissue

Proline metabolism has been identified as a significant player in several neoplasms, but knowledge of its role in gliomas is limited despite it providing a promising line of pursuit. Data on proline metabolism in the brain are somewhat historical. This study aims to investigate alterations of proline metabolism in gliomas of WHO grade 4 (GG4) in the context of the brain. A total of 20 pairs of samples were studied, consisting of excised tumor and unaffected brain tissue, obtained when partial brain resection was required to reach deep-seated lesions. Levels of proline oxidase/proline dehydrogenase (POX/PRODH), Δ1-pyrroline-5-carboxylate reductases (PYCR1/2/3), prolidase (PEPD), and metalloproteinases (MMP-2, MMP-9) were assessed, along with the concentration of proline and proline-related metabolites. In comparison to normal brain tissue, POX/PRODH expression in GG4 was found to be suppressed, while PYCR1 expression and activity of PEPD, MMP-2, and -9 were upregulated. The GG4 proline concentration was 358% higher. Hence, rewiring of the proline metabolism in GG4 was confirmed for the first time, with a low-POX/PRODH/high-PYCR profile. High PEPD and MMPs activity is in keeping with GG4-increased collagen turnover and local aggressiveness. Further studies on the mechanisms of the interplay between altered proline metabolism and the GG4 microenvironment are warranted.

Prolidase-proline oxidase axis is engaged in apoptosis induction by birch buds flavonol santin in endometrial adenocarcinoma cell line

Cancer of the corpus uteri and cervix uteri, collectively ranks second among new cancer cases in women after breast cancer. Therefore, investigation of new anticancer agents and identifying new molecular targets presents a challenge to improve effectiveness of chemotherapy. In this study, antiproliferative activity of flavonoids derived from the buds of silver birch and downy birch was evaluated in endometrial cancer Ishikawa cells and cervical cancer HeLa cells. It was found that flavanol santin reduced viability of both cell lines better than other flavonoids, including apigenin and luteolin. Moreover, this activity was slightly higher than that induced by the chemotherapy drug, cisplatin. Santin promoted intrinsic and extrinsic apoptosis pathways in cancer cells, but it had low toxicity in normal fibroblasts. The mechanisms of impairing cancer cell viability included induction of oxidative proline catabolism, however in different ways in the cell lines used. In HeLa cells, increase of proline oxidation was due to activation of p53 leading to proline oxidase upregulation. In contrast, in Ishikawa cells, having basal proline oxidase level significantly higher than HeLa cells, santin treatment decreased its expression. Nevertheless, proline oxidation was induced in these cells since santin increased expression and activity of prolidase, an enzyme providing proline from protein degradation. In both cell lines, proline oxidation was associated with generation of reactive oxygen species leading to reduction in cell viability. Our findings reveal the involvement of proline oxidase in induction of apoptosis by santin and identify a role of prolidase in proline oxidase-dependent apoptosis.

Recombinant Human Prolidase (rhPEPD) Induces Wound Healing in Experimental Model of Inflammation through Activation of EGFR Signalling in Fibroblasts

The potential of recombinant human prolidase (rhPEPD) to induce wound healing in an experimental model of IL-1β-induced inflammation in human fibroblasts was studied. It was found that rhPEPD significantly increased cell proliferation and viability, as well as the expression of the epidermal growth factor receptor (EGFR) and downstream signaling proteins, such as phosphorylated PI3K, AKT, and mTOR, in the studied model. Moreover, rhPEPD upregulated the expression of the β1 integrin receptor and its downstream signaling proteins, such as p-FAK, Grb2 and p-ERK 1/2. The inhibition of EGFR signaling by gefitinib abolished rhPEPD-dependent functions in an experimental model of inflammation. Subsequent studies showed that rhPEPD augmented collagen biosynthesis in IL-1β-treated fibroblasts as well as in a wound healing model (wound closure/scratch test). Although IL-1β treatment of fibroblasts increased cell migration, rhPEPD significantly enhanced this process. This effect was accompanied by an increase in the activity of MMP-2 and MMP-9, suggesting extracellular matrix (ECM) remodeling during the inflammatory process. The data suggest that rhPEPD may play an important role in EGFR-dependent cell growth in an experimental model of inflammation in human fibroblasts, and this knowledge may be useful for further approaches to the treatment of abnormalities of wound healing and other skin diseases.

A Facile Method to Determine Prolidase Activity Using a Peptide-Specific Fluorometric Reaction

Prolidase is the only enzyme capable of cleaving imidodipeptides containing C-terminal proline (Pro) or hydroxyproline and plays a crucial role in several physiological processes such as wound healing and cell proliferation. Here, we developed a new method to determine prolidase activity. This method is based on a novel fluorescence (FL) reaction selective for N-terminal glycine (Gly)-containing peptides using 3,4-dihydroxyphenylacetic acid (3,4-DHPAA). The 3,4-DHPAA can selectively react with Gly-Pro, the substrate for prolidase, and the prolidase activity is measured by monitoring the decrease in FL intensities. The prolidase activities in fibroblasts and HeLa cells were successfully measured by the proposed method. Compared with classical Chinard's method, our method does not require any caustic acids, pre-incubation to activate the enzyme, and heating for reaction with the detection reagent. The proposed method enables facile and specific measurement for biogenic prolidase activity.

Proline Metabolism in Malignant Gliomas: A Systematic Literature Review

Simple Summary

Studies of various types of cancers have found proline metabolism to be a key player in tumor development, involved in basic metabolic pathways, regulating cell proliferation, survival, and signaling. Here, we systematically searched the literature to find data on proline metabolism in malignant glial tumors. Despite limited availability, existing studies have found several ways in which proline metabolism may affect the development of gliomas, involving the maintenance of redox balance, providing essential glutamate, and affecting major signaling pathways. Metabolomic profiling has revealed the importance of proline as a link to basic cell metabolic cycles and shown it to be correlated with overall survival. Emerging knowledge on the role of proline in general oncology encourages further studies on malignant gliomas.

Abstract

Background: Proline has attracted growing interest because of its diverse influence on tumor metabolism and the discovery of the regulatory mechanisms that appear to be involved. In contrast to general oncology, data on proline metabolism in central nervous system malignancies are limited. Materials and Methods: We performed a systematic literature review of the MEDLINE and EMBASE databases according to PRISMA guidelines, searching for articles concerning proline metabolism in malignant glial tumors. From 815 search results, we identified 14 studies pertaining to this topic. Results: The role of the proline cycle in maintaining redox balance in IDH-mutated gliomas has been convincingly demonstrated. Proline is involved in restoring levels of glutamate, the main glial excitatory neurotransmitter. Proline oxidase influences two major signaling pathways: p53 and NF- κB. In metabolomics studies, the metabolism of proline and its link to the urea cycle was found to be a prognostic factor for survival and a marker of malignancy. Data on the prolidase concentration in the serum of glioblastoma patients are contradictory. Conclusions: Despite a paucity of studies in the literature, the available data are interesting enough to encourage further research, especially in terms of extrapolating what we have learned of proline functions from other neoplasms to malignant gliomas.

Prolidase expression in knee osteoarthritis and healthy controls: Observational study

Prolidase enzyme activity is important for collagen resynthesis. In late stages of osteoarthritis (OA) its activity is decreased.To evaluate prolidase expression in knees of patients undergoing total arthroplasty for OA, and compare with young people undergoing knee arthroscopy due to traumatic injuries.In this cross-sectional study we included 20 patients with OA grade IV who underwent total knee arthroplasty and 20 controls of young patients who underwent arthroscopy for another reason besides OA. All participants were evaluated by knee ultrasound before the procedure. During the procedure, synovial tissue biopsies were taken and analyzed by immunofluorescence to search inflammation. Measures of central tendency, dispersion measures and position measures were used for the case of quantitative variables. Student t test or Mann-Whitney U test, and the logistic regression of Cox, was used.Prolidase expression in the synovial biopsy was significantly lower in the OA group than in the controls (0.017 ± 0.009 vs 0.062 ± 0.094, P < .05). Power Doppler (PD) signal was present in the synovitis of all knee recesses of the OA group in grayscale and in 17 (85%) of knees. The mean of the micro-vessel count in patients with OA was significantly higher vs controls (11 + 5.3 vs 4 + 2.1, P = .001). The neovascularization correlated significantly with the presence of PD signal in patients with OA (1.16, 95% CI, 1.02-1.34, P = .02).The prolidase expression in the synovial membrane evaluated by immunofluorescence, in patients with late stages of knee OA, is low, which may be interpreted as an evidence of decreased collagen resynthesis.

Role of prolidase activity and oxidative stress biomarkers in unexplained infertility

OBJECTIVE

Our aim was to explore the significance of serum prolidase enzyme activity and oxidative stress in women with unexplained infertility (UEI).

METHODS

In this case-control study (n = 160; 86 cases; 74 controls) prolidase enzyme activity and total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), and vitamin E were measured in plasma using enzyme-linked immunosorbent assays.

RESULTS

Prolidase enzyme activity and TAS levels were particularly higher in the patient group (P = 0.013, P = 0.001, respectively). Decreased OSI levels were detected in the patient group (P = 0.001). There was a positive relationship of prolidase with vitamin E in both patient and control groups (r = 0.892, P = 0.001, and r = 0.659, P = 0.001, respectively). A positive, but weak, relationship was identified between prolidase activity and TOS levels and also between vitamin E and TOS levels in the UEI group (r = 0.265, P = 0.049, and r = 0.288, P = 0.014, respectively). No association was found between prolidase and TOS levels or between vitamin E and TOS levels in the control group (r = 0.0097, P = 0.527, and r = 0.085, P = 0.610, respectively).

CONCLUSION

Our results showed an association between serum prolidase activity and oxidative stress in UEI patients. Further studies including greater groups are required to show the role of reactive oxygen species in UEI.

Platelet-Rich Plasma Promotes the Proliferation of Human Keratinocytes via a Progression of the Cell Cycle. A Role of Prolidase

Although the role of platelet-rich plasma (PRP) in tissue regeneration has been confirmed in many studies, the mechanism of this process is still not fully understood. Human keratinocytes (HaCaT) cells were used as an experimental model for studies on the effects of PRP on cell proliferation, migration, collagen biosynthesis, prolidase activity, and its expression and anabolic signaling. The activation of epidermal growth factor receptor (EGFR), β₁-integrin, and insulin-like growth factor-1 receptor (IGF-1R) by PRP were investigated by western blot and immunocytochemistry. It has been found that PRP induced keratinocytes migration and proliferation through activation of cell cycle progression and EGFR downstream signaling. Similar biological effects were achieved by an addition to the culture medium of prolidase (PEPD), a ligand of EGFR (PRP is a rich source of PEPD–2 ng/mL). PRP-dependent stimulation of collagen biosynthesis was accompanied by an increase in the expression of NF-κβ, IGF-1R-downstream signaling proteins, and PEPD activity. The data suggest that PRP activates a complex of growth factors and adhesion receptors that stimulate cell proliferation, migration, and collagen biosynthesis. PRP induces PEPD-dependent human keratinocyte proliferation through activation of the EGFR receptor. Our study provides a novel mechanism of PRP-dependent wound healing.

Extracellular Prolidase (PEPD) Induces Anabolic Processes through EGFR, β1-integrin, and IGF-1R Signaling Pathways in an Experimental Model of Wounded Fibroblasts

The role of prolidase (PEPD) as a ligand of the epidermal growth factor receptor (EGFR) was studied in an experimental model of wound healing in cultured fibroblasts. The cells were treated with PEPD (1-100 nM) and analysis of cell viability, proliferation, migration, collagen biosynthesis, PEPD activity, and the expressions of EGFR, insulin-like growth factor 1 (IGF-1), and β₁-integrin receptor including downstream signaling proteins were performed. It has been found that PEPD stimulated proliferation and migration of fibroblasts via activation of the EGFR-downstream PI3K/Akt/mTOR signaling pathway. Simultaneously, PEPD stimulated the expression of β₁-integrin and IGF-1 receptors and proteins downstream to these receptors such as FAK, Grb2, and ERK1/2. Collagen biosynthesis was increased in control and "wounded" fibroblasts under PEPD treatment. The data suggest that PEPD-induced EGFR signaling may serve as a new attempt to therapy wound healing.

PROLIDASE: A Review from Discovery to its Role in Health and Disease

Prolidase (peptidase D), encoded by the PEPD gene, is a ubiquitously expressed cytosolic metalloproteinase, the only enzyme capable of cleaving imidodipeptides containing C-terminal proline or hydroxyproline. Prolidase catalyzes the rate-limiting step during collagen recycling and is essential in protein metabolism, collagen turnover, and matrix remodeling. Prolidase, therefore plays a crucial role in several physiological processes such as wound healing, inflammation, angiogenesis, cell proliferation, and carcinogenesis. Accordingly, mutations leading to loss of prolidase catalytic activity result in prolidase deficiency a rare autosomal recessive metabolic disorder characterized by defective wound healing. In addition, alterations in prolidase enzyme activity have been documented in numerous pathological conditions, making prolidase a useful biochemical marker to measure disease severity. Furthermore, recent studies underscore the importance of a non-enzymatic role of prolidase in cell regulation and infectious disease. This review aims to provide comprehensive information on prolidase, from its discovery to its role in health and disease, while addressing the current knowledge gaps.

Prolidase Stimulates Proliferation and Migration through Activation of the PI3K/Akt/mTOR Signaling Pathway in Human Keratinocytes

Recent reports have indicated prolidase (PEPD) as a ligand of the epidermal growth factor receptor (EGFR). Since this receptor is involved in the promotion of cell proliferation, growth, and migration, we aimed to investigate whether prolidase may participate in wound healing in vitro. All experiments were performed in prolidase-treated human keratinocytes assessing cell vitality, proliferation, and migration. The expression of downstream signaling proteins induced by EGFR, insulin-like growth factor 1 (IGF-1), transforming growth factor β₁ (TGF-β₁), and β₁-integrin receptors were evaluated by Western immunoblotting and immunocytochemical staining. To determine collagen biosynthesis and prolidase activity radiometric and colorimetric methods were used, respectively. Proline content was determined by applying the liquid chromatography coupled with mass spectrometry. We found that prolidase promoted the proliferation and migration of keratinocytes through stimulation of EGFR-downstream signaling pathways in which the PI3K/Akt/mTOR axis was involved. Moreover, PEPD upregulated the expression of β₁-integrin and IGF-1 receptors and their downstream proteins. Proline concentration and collagen biosynthesis were increased in HaCaT cells under prolidase treatment. Since extracellular prolidase as a ligand of EGFR induced cell growth, migration, and collagen biosynthesis in keratinocytes, it may represent a potential therapeutic approach for the treatment of skin wounds.

Current Understanding of the Emerging Role of Prolidase in Cellular Metabolism

Prolidase [EC 3.4.13.9], known as PEPD, cleaves di- and tripeptides containing carboxyl-terminal proline or hydroxyproline. For decades, prolidase has been thoroughly investigated, and several mechanisms regulating its activity are known, including the activation of the β₁-integrin receptor, insulin-like growth factor 1 receptor (IGF-1) receptor, and transforming growth factor (TGF)-β₁ receptor. This process may result in increased availability of proline in the mitochondrial proline cycle, thus making proline serve as a substrate for the resynthesis of collagen, an intracellular signaling molecule. However, as a ligand, PEPD can bind directly to the epidermal growth factor receptor (EGFR, epidermal growth factor receptor 2 (HER2)) and regulate cellular metabolism. Recent reports have indicated that PEPD protects p53 from uncontrolled p53 subcellular activation and its translocation between cellular compartments. PEPD also participates in the maturation of the interferon α/β receptor by regulating its expression. In addition to the biological effects, prolidase demonstrates clinical significance reflected in the disease known as prolidase deficiency. It is also known that prolidase activity is affected in collagen metabolism disorders, metabolic, and oncological conditions. In this article, we review the latest knowledge about prolidase and highlight its biological function, and thus provide an in-depth understanding of prolidase as a dipeptidase and protein regulating the function of key biomolecules in cellular metabolism.

Is there a correlation between obstructive sleep-apnea syndrome severity and prolidase activity as an oxidative stress marker?

Objective

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent breathing disorder in sleep. The aim of this study was to evaluate the relationship between OSAS and prolidase activity, the oxidative stress index (OSI), total antioxidative capacity (TAC), total oxidative capacity (TOC) and the carotid intima media thickness (CIMT).

Method

: After night polysomnography, 74 people were diagnosed with OSAS and simple snoring. Plasma prolidase activities, TAC and TOC were measured in blood samples taken in the morning after the sleep study. The patients' bilateral common carotid arteries were scanned.

Results

In total, 56 patients were in OSAS group [13 subjects 23.2% mild, 19 subjects 33.9% moderate, 24 subjects 42.8% severe] and 18 in simple snoring control group. The mean Prolidase, TOC, TAC and OSI levels were 744.7 ± 156.8, 59.2 ± 19.2, 2.12 ± 0.41, 3.12 ± 1.03, in the mild OSAS group, 761.6 ± 114.4, 57.9 ± 18.3, 2.03 ± 0.37, 3.15 ± 0.8, in the moderate OSAS group, 754.08 ± 133.9, 51.15 ± 12.1, 1.97 ± 0.27, 2.8 ± 0.82, in the severe OSAS group, and 711.9 ± 139, 52.3 ± 15.1, 1.83 ± 0.32, 3.06 ± 0.92 in the control group, respectively. Mean CIMT measurements were 0.71(±0,13) in the OSAS group and 0.76(±0.07) in the control group.

Conclusion

There was no difference between the control and OSAS groups in terms of the parameters studied. Further studies should be undertaken in order to clarify the relation.

Serum prolidase activity, total oxidant/antioxidant, and nitric oxide levels in patients with esophageal squamous cell carcinoma

Background

This study aims to assess the prolidase activity, nitric oxide levels, and oxidative status in patients with esophageal squamous cell carcinoma.

Methods

The study included 30 patients with esophageal squamous cell carcinoma (11 males, 19 females; mean age 61±3 years; range, 28 to 77 years) and 30 healthy controls (10 males, 20 females; mean age 58±5 years; range, 31 to 73 years). Serum prolidase activity, total antioxidant capacity, total oxidant status, and nitric oxide levels were measured. In addition, the oxidative stress index was calculated.

Results

Prominently elevated serum prolidase activity, oxidative stress index values, total oxidant status, and nitric oxide levels were detected in the patient group (p<0.05). Lower total antioxidant capacity levels were observed in the patient group (p<0.05).

Conclusion

Increased oxidant status with increased nitric oxide levels and prolidase activity were found in esophageal squamous cell carcinoma patients. Impairment of antioxidant mechanism with increased prolidase activity and nitric oxide levels may have a crucial role in the etiopathogenesis of esophageal squamous cell carcinoma.

Structures and activities of widely conserved small prokaryotic aminopeptidases-P clarify classification of M24B peptidases

M24B peptidases cleaving Xaa-Pro bond in dipeptides are prolidases whereas those cleaving this bond in longer peptides are aminopeptidases-P. Bacteria have small aminopeptidases-P (36-39 kDa), which are diverged from canonical aminopeptidase-P of Escherichia coli (50 kDa). Structure-function studies of small aminopeptidases-P are lacking. We report crystal structures of small aminopeptidases-P from E. coli and Deinococcus radiodurans, and report substrate-specificities of these proteins and their ortholog from Mycobacterium tuberculosis. These are aminopeptidases-P, structurally close to small prolidases except for absence of dipeptide-selectivity loop. We noticed absence of this loop and conserved arginine in canonical archaeal prolidase (Maher et al., Biochemistry. 43, 2004, 2771-2783) and questioned its classification. Our enzymatic assays show that this enzyme is an aminopeptidase-P. Further, our mutagenesis studies illuminate importance of DXRY sequence motif in bacterial small aminopeptidases-P and suggest common evolutionary origin with human XPNPEP1/XPNPEP2. Our analyses reveal sequence/structural features distinguishing small aminopeptidases-P from other M24B peptidases.

Dual inhibition of ErbB1 and ErbB2 in cancer by recombinant human prolidase mutant hPEPD-G278D

ErbB1 and ErbB2 are oncogenic cell surface receptor tyrosine kinases, linked to many forms of human cancer, and are major cancer therapeutic targets. Many lines of evidence indicate that targeting ErbB1 and ErbB2 is an important cancer therapeutic approach. We recently found that a recombinant enzymatically-inactive mutant of human prolidase, i.e., hPEPD-G278D, is an inhibitory ligand of ErbB2 and strongly inhibits ErbB2-overexpressing cells in vitro and in vivo. hPEPD-G278D also binds to ErbB1. Here, we show that hPEPD-G278D binds to ErbB1 with high affinity, initially activating ErbB1 but later silencing it, and that deletion of subdomain 2 in ErbB1 extracellular domain abolishes the binding. The proliferation of ErbB1-overexpressing cells is strongly inhibited by hPEPD-G278D, regardless of ErbB2 expression or cell type, whereas cells lacking ErbB1 and ErbB2 are insensitive to it. In contrast, EGF, another ErbB1 ligand, either stimulates or mildly inhibits cell proliferation. Moreover, hPEPD-G278D treatment of mice bearing ErbB1-overexpressing tumors leads to tumor regression, which is accompanied by down regulation and decreased phosphorylation of ErbB1 and ErbB2 as well as decreased phosphorylation of downstream signaling molecules and activation of apoptosis in the tumor tissues. We conclude that hPEPD-G278D is a dual inhibitor of ErbB1 and ErbB2 and selectively targets cancer cells overexpressing ErbB1 and/or ErbB2. Moreover, our finding that both receptors are silenced in cancer cells by hPEPD-G278D highlights an unusual consequence of ligand-receptor interaction.

A plasma proteolysis pathway comprising blood coagulation proteases

Coagulation factors are essential for hemostasis. Here, we show that these factors also team up to degrade plasma proteins that are unrelated to hemostasis. Prolidase, SRC and amyloid β1-42 (Aβ1-42) are used as probes. Each probe, upon entering the blood circulation, binds and activates factor XII (FXII), triggering the intrinsic and common coagulation cascades, which in turn activate factor VII, a component of the extrinsic coagulation cascade. Activated factor VII (FVIIa) rapidly degrades the circulating probes. Therefore, FXII and FVIIa serve as the sensor/initiator and executioner, respectively, for the proteolysis pathway. Moreover, activation of this pathway by one probe leads to the degradation of all three probes. Significant activation of this pathway follows tissue injury and may also occur in other disorders, e.g., Alzheimer's disease, of which Aβ1-42 is a key driver. However, enoxaparin, a clinically used anticoagulant, inhibits the proteolysis pathway and elevates plasma levels of the probes. Enoxaparin may also mitigate potential impact of activators of the proteolysis pathway on coagulation. Our results suggest that the proteolysis pathway is important for maintaining low levels of various plasma proteins. Our finding that enoxaparin inhibits this pathway provides a means to control it. Inhibition of this pathway may facilitate the development of disease biomarkers and protein therapeutics, e.g., plasma Aβ1-42 as a biomarker of Alzheimer's disease or recombinant human prolidase as an antitumor agent.

Oxidative Stress And Prolidase Enzyme Activity In The Pathogenesis Of Primary Varicose Veins

Objectives Vascular endothelial dysfunction leads to the emerging of free oxygen radicals, deficiency of antioxidant system, forming of oxidative stress, inflammatory processes and release of proinflammatory cytokines. These things play big role in the development of primary varicose veins. Prolidase has been reported as an indicator of oxidative stress in diabetes, diabetic neuropathy, non-ulcerous dyspepsia, osteoporosis, polycystic over syndrome and many other diseases. The aim of this study is to evaluate the oxidative stress at venous insufficiency and to provide preliminary knowledge about the role of prolidase enzyme in varicose vein formation. Methods Ninety patients aged between 22 and 80 (47.35 ± 17.69) were included in the study and divided into 3 groups. Group1(n:30)(Serum control group): Patients without venous insufficiency. Group 2(n:30)(Tissue control group(healthy vein group): Patients underwent coronary artery bypass surgery (the remaining portion of great saphenous vein used as coronary artery bypass graft used as normal tissue) . Group 3(n:30)(Varicose vein group): Patients underwent varicose vein surgery (varicose vein and serum of these patients were used for study). Total Oxidant Status (TOS), Total Antioxidant Status (TAS), Oxidative Stress Index (OSI) and Prolidase enzyme levels were detected in tissue and serum samples. Results No significant changes were detected between three groups' serum samples in oxidative stress parameters and in the prolidase enzyme activity. The tissue TOS and OSI were higher in varicose vein group according to normal vein group and this was found statistically significant. And TAC levels in varicose vein group were significantly lower than normal vein group. Prolidase enzyme activity in varicose vein group was found higher according to normal vein group. Conclusion Oxidative stress plays a role at the development of primary varicose veins at biochemical level. Prolidase enzyme related with oxidative stress may play an important role in the pathogenesis of primary varicose veins.

Prolidase is a critical enzyme for complete gliadin digestion in Tenebrio molitor larvae

Prolidase is a proline-specific metallopeptidase that cleaves imidodipeptides with C-terminal Pro residue. Prolidase was purified and characterized from the Tenebrio molitor larval midgut. The enzyme was localized in the soluble fraction of posterior midgut tissues, corresponding to a predicted cytoplasmic localization of prolidase according to the structure of the mRNA transcript. Expression of genes encoding prolidase and the major digestive proline-specific peptidase (PSP)-dipeptidyl peptidase 4-were similar. The pH optimum of T. molitor prolidase was 7.5, and the enzyme was inhibited by Z-Pro, indicating that it belongs to type I prolidases. In mammals, prolidase is particularly important in the catabolism of a proline-rich protein-collagen. We propose that T. molitor larval prolidase is a critical enzyme for the final stages of digestion of dietary proline-rich gliadins, providing hydrolysis of imidodipeptides in the cytoplasm of midgut epithelial cells. We propose that the products of hydrolysis are absorbed from the luminal contents by peptide transporters, which we have annotated in the T. molitor larval gut transcriptome. The origin of prolidase substrates in the insect midgut is discussed in the context of overall success of grain feeding insects.

Circulating Prolidase Activity in Patients with Myocardial Infarction

Background

Collagen is a major determinant of atherosclerotic plaque stability. Thus, identification of differences in enzymes that regulate collagen integrity could be useful for predicting susceptibility to atherothrombosis or for diagnosing plaque rupture. In this study, we sought to determine whether prolidase, the rate-limiting enzyme of collagen turnover, differs in human subjects with acute myocardial infarction (MI) versus those with stable coronary artery disease (CAD).

Methods

We measured serum prolidase activity in 15 patients with stable CAD and 49 patients with acute MI, of which a subset had clearly defined thrombotic MI (n = 22) or non-thrombotic MI (n = 12). Prolidase activity was compared across study time points (at cardiac catheterization, T0; 6 h after presentation, T6; and at a quiescent follow-up, Tf/u) in acute MI and stable CAD subjects. We performed subgroup analyses to evaluate prolidase activity in subjects presenting with acute thrombotic versus non-thrombotic MI.

Results

Although prolidase activity was lower at T0 and T6 versus the quiescent phase in acute MI and stable CAD subjects (p < 0.0001), it was not significantly different between acute MI and stable CAD subjects at any time point (T0, T6, and Tf/u) or between thrombotic and non-thrombotic MI groups. Preliminary data from stratified analyses of a small number of diabetic subjects (n = 8) suggested lower prolidase activity in diabetic acute MI subjects compared with non-diabetic acute MI subjects (p = 0.02).

Conclusion

Circulating prolidase is not significantly different between patients with acute MI and stable CAD or between patients with thrombotic and non-thrombotic MI. Further studies are required to determine if diabetes significantly affects prolidase activity and how this might relate to the risk of MI.

Methylparaben-induced decrease in collagen production and viability of cultured human dermal fibroblasts

Parabens owing to their many advantageous properties are widely applied in cosmetics, food products and pharmaceuticals. However, recent research results have shown that they possess the ability to accumulate in the human body and exert many adverse effects. In this study, the impact of methylparaben (MP) as the most frequently used preservative in cosmetics, on human dermal fibroblasts and collagen production was evaluated. In cells treated with 0.01, 0.03 and 0.05% MP a dose-dependent decrease in collagen biosynthesis was revealed, which was positively correlated with the activity of prolidase responsible for the recovery of proline. Consequently, the concentration of total collagen secreted into the medium was markedly diminished. A similar reduction in expression of the major skin collagen type I at both the protein and mRNA level as well as collagen type III and VI at the mRNA level was also detected. The decrease in the collagen level may result not only from the reduced synthesis but also increased degradation owing to MP-induced activation of pro-MMP-2 (72 kDa). The increase in activity of MMP-2 (66 kDa) was accompanied by a reduction in the inhibitory activity of TIMP-2. In addition, an inhibitory effect of MP on cell survival and proliferation was revealed in this study. The increased expression and nuclear translocation of caspase-3 as well as increased Bax and decreased Bcl-2 expression may suggest MP-induced cell apoptosis. In summary, we have provided new data on the adverse effects of methylparaben on human dermal fibroblasts and the main structural protein of the skin. Further studies on the mechanisms responsible for its action are in progress. Copyright © 2017 John Wiley & Sons, Ltd.

Prolidase

Prolidase (EC.3.4.13.9) or proline dipeptidase, is one of the unique enzyme capable of degrading dipeptides, in which a proline or hydroxyproline residue is located at the C-terminal position. Prolidase has a unique function in all cell types; therefore, the mechanisms and parameters involved in prolidase activity regulation are of special interest. Could prolidase be a good biomarker in different physiologic and pathologic conditions? This is an important question. There is no consensus on the answer to this question. It is of great importance during collagen turnover, inflammation, tissue fibrosis and skeletal abnormalities.Prolidase itself without other biochemical markers may not provide information to clinicians about disease activity. So, I think it should be evaluated together with other serum biochemical markers.This review will serve to discuss many in vivo functions of prolidase, as well as level prolidase activity in diagnosis and monitoring of treatment in the various diseases (Ref. 50).

Prolidase-proline dehydrogenase/proline oxidase-collagen biosynthesis axis as a potential interface of apoptosis/autophagy

Prolidase is a cytosolic imidodipeptidase that specifically splits imidodipeptides with C-terminal proline or hydroxyproline. The enzyme plays an important role in the recycling of proline from imidodipeptides for resynthesis of collagen and other proline-containing proteins. The mechanism of prolidase-dependent regulation of collagen biosynthesis was found at both transcriptional and post-transcriptional level. The increase in the enzyme activity is due to its phosphorylation on serine/threonine residues. Prolidase-dependent transcriptional regulation of collagen biosynthesis was found at the level of NF-κB, known inhibitor of type I collagen gene expression. Proline dehydrogenase/proline oxidase (PRODH/POX) is flavin-dependent enzyme associated with the inner mitochondrial membrane. The enzyme catalyzes conversion of proline into Δ(1) -pyrroline-5-carboxylate (P5C), during which reactive oxygen species (ROS) are produced, inducing intrinsic and extrinsic apoptotic pathways. Alternatively, under low glucose stress, PRODH/POX activation produces ATP for energy supply and survival. Of special interest is that PRODH/POX gene is induced by P53 and peroxisome proliferator-activated gamma receptor (PPARγ). Among down-regulators of PRODH/POX is an oncogenic transcription factor c-MYC and miR-23b*. On the other hand, PRODH/POX suppresses HIF-1α transcriptional activity, the MAPK pathway, cyclooxygenase-2, epidermal growth factor receptor and Wnt/b-catenin signaling. PRODH/POX expression is often down-regulated in various tumors, limiting mitochondrial proline utilization to P5C. It is accompanied by increased cytoplasmic level of proline. Proline availability for PRODH/POX-dependent ATP or ROS generation depends on activity of prolidase and utilization of proline in process of collagen biosynthesis. Therefore, Prolidase-PRODH/POX-Collagen Biosynthesis axis may represent potential interface that regulate apoptosis and survival. © 2016 BioFactors, 42(4):341-348, 2016.

Evaluation of prolidase activity and oxidative stress in patients with oral lichen planus and oral lichenoid contact reactions

OBJECTIVE

The aim of this study was to evaluate prolidase activity and oxidative stress in patients with oral lichen planus (OLP) and oral lichenoid contact reactions (OLCR) using serum and salivary samples and to compare these biomarkers with each other as well as with a group of healthy subjects in order to be able to opine their role in the estimation of OLP and OLCR.

PATIENTS AND METHODS

Eighteen recently diagnosed patients with OLP, 32 patients with OLCR and 18 healthy controls with matched periodontal status were recruited to the study. Prolidase activity, lipid peroxidation product malondialdehyde (MDA), sialic acid (SA), and advanced oxidation protein products (AOPPs) levels in both serum and saliva were determined. Additionally, salivary flow rate and its buffering capacity were estimated. Statistical analyses were performed using the chi-square test, t-test, Mann-Whitney U-test, and Spearman's rho correlation coefficient.

RESULTS

No statistically significant differences were observed between the study groups and the control group regarding to the basic characteristics and the periodontal status (P > 0.05). There were no statistically significant differences between OLP and OLCR groups regarding to the distribution of lesions' type, severity, and location (P > 0.05). No significant differences were found between the two study groups with regard to Prolidase activity, MDA, SA, and AOPPs (P ˃ 0.05), whereas statistically significant differences were found between the two study groups and the control group with regard to all evaluated parameters except of serum prolidase (P ˂ 0.01). Moderate correlation was found between salivary MDA and the OLP/OLCR lesion severity, whereas a weak correlation was observed between serum SA and the OLP/OLCR lesion severity (P ˂ 0.05).

CONCLUSIONS

The findings of this study suggest an increased prolidase activity and oxidative stress and imbalance in the antioxidant defense system in biological fluids of patients with OLP and OLCR when compared with the healthy subjects. Both OLP and OLCR patients revealed almost similar prolidase activity and oxidative stress levels although these two conditions have different etiopathogenesis.

Structure of recombinant prolidase from Thermococcus sibiricus in space group P21221

The crystal structure of recombinant prolidase from Thermococcus sibiricus was determined by X-ray diffraction at a resolution of 2.6 Å and was found to contain a tetramer in the asymmetric unit. A protein crystal grown in microgravity using the counter-diffusion method was used for X-ray studies. The crystal belonged to space group P21221, with unit-cell parameters a = 97.60, b = 123.72, c = 136.52 Å, α = β = γ = 90°. The structure was refined to an Rcryst of 22.1% and an Rfree of 29.6%. The structure revealed flexible folding of the N-terminal domain of the protein as well as high variability in the positions of the bound metal ions. The coordinates of the resulting model were deposited in the Protein Data Bank as entry 4rgz.

Prolidase-dependent mechanism of (Z)-8,9-epoxyheptadeca-1,11,14-triene-induced inhibition of collagen biosynthesis in cultured human skin fibroblasts

The effects of polyolefinic compound from roots of Cirsium palustre, (Z)-8,9-epoxyheptadeca-1,11,14-triene (EHT) on collagen biosynthesis, prolidase activity, expression of insulin-like growth factor receptor (IGF-IR), β1 integrin, MAP kinases (pERK1/2), the transcription factors such as nuclear factor kappa B (NF-κB) and hypoxia-inducible factor-1α (HIF-1α) were evaluated in human dermal fibroblasts treated with micromolar concentrations (40-200 μM) for 24 h. It was found that EHT-dependent inhibition of collagen biosynthesis was accompanied by parallel inhibition in prolidase activity. Since IGF-I is the most potent regulator of both processes and prolidase is regulated by β1 integrin signalling, the effect of EHT on IGF-IR and β1 integrin receptor expressions were evaluated. Exposure of the cells to EHT contributed to distinct increase in IGF-IR and slight increase in β1 integrin receptor expressions. It was accompanied by decrease in expression of pERK1/2, HIF-1α and NF-κB. EHT-dependent inhibition of collagen biosynthesis results from inhibition of prolidase activity, the enzyme involved in collagen biosynthesis.

Inhibition of ERBB2-overexpressing Tumors by Recombinant Human Prolidase and Its Enzymatically Inactive Mutant

ERBB2 is an oncogenic receptor tyrosine kinase overexpressed in a subset of human breast cancer and other cancers. We recently found that human prolidase (PEPD), a dipeptidase, is a high affinity ERBB2 ligand and cross-links two ERBB2 monomers. Here, we show that recombinant human PEPD (rhPEPD) strongly inhibits ERBB2-overexpressing tumors in mice, whereas it does not impact tumors without ERBB2 overexpression. rhPEPD causes ERBB2 depletion, disrupts oncogenic signaling orchestrated by ERBB2 homodimers and heterodimers, and induces apoptosis. The impact of enzymatically-inactive mutant rhPEPD^G278D on ERBB2 is indistinguishable from that of rhPEPD, but rhPEPD^G278D is superior to rhPEPD for tumor inhibition. The enzymatic function of rhPEPD stimulates HIF-1α and other pro-survival factors in tumors, which likely attenuates its antitumor activity. rhPEPD^G278D is also attractive in that it may not interfere with the physiologic function of endogenous PEPD in normal cells. Collectively, we have identified a human protein as an inhibitory ERBB2 ligand that inhibits ERBB2-overexpressing tumors in vivo. Several anti-ERBB2 agents are on the market but are hampered by drug resistance and high drug cost. rhPEPD^G278D may synergize with these agents and may also be highly cost-effective, since it targets ERBB2 with a different mechanism and can be produced in bacteria.

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Human prolidase (rhPEPD) inhibits the growth of ErbB2-overexpressing tumors.

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rhPEPD disrupts the signaling complexes assembled by ErbB2 homo- and hetero-dimers.

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Enzymatically-inactive rhPEPD^G278D is superior to rhPEPD for tumor inhibition.

Prolidase activity in chronic plaque psoriasis patients

INTRODUCTION

Psoriasis is a chronic, inflammatory, T-cell-mediated and hyperproliferative skin disease characterized by erythematous, squamous, sharply circumscribed and infiltrated plaques. The metabolisms of the collagen proteins undergo considerable changes due to the acceleration of their turnovers as a result of increased prolidase activity in psoriasis patients.

AIM

To determine the level of prolidase activity in psoriasis patients and evaluate its relationship with the oxidative system.

MATERIAL AND METHODS

The serum prolidase enzyme activity, total antioxidant levels and total oxidant levels of 40 psoriasis patients and a control group including 47 healthy individuals were analyzed by using their serum samples, and their oxidative stress indices were calculated.

RESULTS

The prolidase levels (p < 0.01), total oxidant levels (p < 0.01) and oxidative stress index levels (p < 0.001) of the patient group were higher than the corresponding parameters in the control group. The total antioxidant level was low (p < 0.01). Although a positive correlation was found between the prolidase and total antioxidant levels and the total oxidant level, no correlation was found between prolidase and the oxidative stress index.

CONCLUSIONS

It has been determined that the activity of the prolidase enzyme increases due to the increased collage turnover in psoriasis patients. Increased serum oxidant levels and oxidative stress indices values may play a role in the pathogenesis of psoriasis.

Crystallization and preliminary X-ray diffraction analysis of Xaa-Pro dipeptidase from Xanthomonas campestris

Xaa-Pro dipeptidase (XPD; prolidase; EC 3.4.13.9) specifically hydrolyzes dipeptides with a prolyl residue at the carboxy-terminus. Xanthomonas spp. possess two different isoforms of XPD (48 and 43 kDa) which share ∼24% sequence identity. The XPD of 43 kDa in size (XPD43) from Xanthomonas spp. is unusual as it lacks the strictly conserved tyrosine residue (equivalent to Tyr387 in Escherichia coli aminopeptidase P) that is suggested to be important in the proton-shuttle transfer required for catalysis in the M24B (MEROPS) family. Here, the crystallization and preliminary X-ray analysis of XPD43 from X. campestris (GenBank accession No. NP_637763) are reported. Recombinant XPD43 was crystallized using the microbatch-under-oil technique. Diffraction data were collected on the recently commissioned protein crystallography beamline (PX-BL21) at the Indian synchrotron (Indus-2, 2.5 GeV) to 1.83 Å resolution with 100% completeness. The crystal belonged to space group P212121, with unit-cell parameters a = 84.32, b = 105.51, c = 111.35 Å. Two monomers are expected to be present in the asymmetric unit of the crystal, corresponding to a solvent content of 58%. Structural analysis of XPD43 will provide new insights into the role of the conserved residues in catalysis in the M24B family.

Evaluation of the utility of serum prolidase as a marker for liver fibrosis

BACKGROUND

Liver dysfunction is common and often unrecognized. Liver biopsy is the gold standard in the assessment of liver fibrosis, but has disadvantages. We assessed the diagnostic accuracy of serum prolidase enzyme activity (SPA) in predicting the presence and degree of liver fibrosis, as compared with liver biopsy. Further, we evaluated the effect of hemolysis on measured SPA levels.

METHODS

We undertook a prospective case control study. Thirty eight outpatients without apparent liver illness and 20 patients with liver pathology scheduled to undergo liver biopsy had their SPA levels measured.

RESULTS

Patients undergoing liver biopsy had higher SPA levels (361 (268) IU/l [median (interquartile range)]) compared with controls (169 (160) (P < 0.001)). A SPA cutoff value of 200 IU/l yielded a sensitivity of 89%, specificity of 59%, an odds ratio of 11.5, negative predictive value of 92%, and a positive predictive value of 50%. Hemolysis causes an apparent increase in SPA levels.

CONCLUSION

Higher SPA levels in patients undergoing liver biopsies compared with controls may reflect the presence of liver fibrosis. SPA levels could not be used to stage the degree of fibrosis. SPA measurement may be useful in the diagnostic workup of suspected liver disease.

Does prolidase indicate worsening of hepatitis B infection?

BACKGROUND

Hepatitis B infection is a health problem that affects more than 400 million people all over the world. We aimed to evaluate the usability of prolidase enzyme that plays an important role in collagen synthesis. Prolidase levels increase in hepatic damage, which can be used as diagnostic parameters in the progressions to chronic hepatitis B (CHB) infection by evaluating it in different clinical forms of hepatitis B infection.

METHODS

A total of 69 patients who presented to our clinic with chronic hepatitis B (CHB) infection, 72 patients with inactive hepatitis B infection (IHB), and 45 healthy volunteers were included into this study. Alanine transaminase (ALT), Aspartate aminotransferase (AST) and prolidase levels of patients were measured. Hepatic biopsy was performed in patients with CHB infection. Prolidase levels were evaluated in three different groups, and its correlations with fibrosis were investigated.

RESULTS

Prolidase was different between all groups (P < 0.001). Prolidase level was found to be higher in CHB and IHB compared to the control group. There was no correlation between this enzyme, fibrosis, and histological activity index.

CONCLUSION

In this present study, it is shown that prolidase levels increase in hepatitis B infection. It may be used as a biochemical marker in the chronic hepatitis B.

Serum prolidase activity in benign joint hypermobility syndrome

BACKGROUND

Moderate joint laxity is widespread in many joints of the body, and this condition is considered to be caused by an abnormality in the collagen structure. This study was carried out to determine the serum prolidase activity in female patients with benign joint hypermobility syndrome (BJHS), and to evaluate its correlation with their clinical features.

METHODS

A total of 45 patients with BJHS and 40 healthy controls were included in the study. All of the patients with BJHS met the Beighton diagnostic criteria. All the patients and the control group underwent a comprehensive examination of the locomotor system and took the New York Posture Rating Test. The examination and test results were recorded. Serum prolidase activity was measured in both the groups.

RESULTS

Prolidase activity was significantly lower in patients with BJHS (479.52 ± 126.50) compared to the healthy controls (555.97 ± 128.77) (p = 0.007). We found no correlation between serum prolidase activity and Beighton scores or New York rating test scores. On the other hand, mean prolidase activity was significantly lower in patients with pes planus or hyperlordosis compared to those without (p = 0.05, p = 0.03, respectively). We did not find such a correlation with the other clinical features.

CONCLUSIONS

Significantly lower prolidase activity in patients with BJHS suggests that prolidase may affect the collagen metabolism and cause hyperlaxity.

Prolidase activity in patients with coronary artery aneurysm

Decreased collagen biosynthesis and increased collagenolysis may induce aneurysmal progress in arterial walls. Prolidase plays a role in collagen synthesis. In this study, we sought to evaluate whether there is a correlation between nonatherosclerotic coronary artery aneurysms (CAAs) and prolidase activity. A total of 174 CAAs were diagnosed in 144 (2.1%) patients among 6845 coronary angiographies performed between 2009 and 2012. In all, 23 (15.9%) patients had nonatherosclerotic aneurysms. Prolidase activity was compared to the results of 19 healthy volunteers with normal coronary arteries. Demographic parameters were similar between the groups. Mean prolidase activity was 241.6 ± 54.4 mU/mL in the coronary aneurysm group and 730.3 ± 243.1 mU/mL in the control group (P < .001). The incidence of CAAs ranges between 0.3% and 5.3% in the general population. Decreased prolidase activity may reduce collagen biosynthesis that may contribute to aneurysm formation.

Prolidase, matrix metalloproteinases 1 and 13 activity, oxidative-antioxidative status as a marker of preterm premature rupture of membranes and chorioamnionitis in maternal vaginal washing fluids

OBJECTIVE

Etiology of premature preterm rupture of membranes (PPROM) is not yet completely known and chorioamnionitis is one of the most important complications of its. We aimed to evaluate whether prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in vaginal washing fluid (VWF) were associated with etiology of PPROM and whether these markers could be used to predict chorioamnionitis in PPROM.

STUDY DESIGN

This prospective case control study enrolled fifty pregnant women with PPROM and 50 healthy pregnant women. The VWF samples were taken at the time of admission in the PPROM group and patients were followed for chorioamnionitis. Prolidase, matrix metalloproteinases, oxidative-antioxidative status, and inflammation markers in VWF were assayed.

RESULTS

VWF levels of prolidase, matrix metalloproteinases 1-13 (p< 0.001), oxidative stress parameters, total oxidative stress (TOS) (p < 0.001) and oxidative stress index (OSI) (p = 0.002), and hs-CRP (p = 0.045) were significantly higher in the PPROM group than in the controls. Antioxidative status parameters, levels of paroxanase (PON-1) (p < 0.001) and total antioxidant capacity (TAC) (p < 0.001), were significantly lower in the PPROM group than in the controls. Mean VWF levels of prolidase (p < 0.001), metalloproteinases (p<0.05), and oxidative-antioxidative status parameters (p<0.05) were significantly different in women with versus women without chorioamnionitis in the PPROM group. Prolidase, MMP-13, TOS, TAC, and PON-1 were found as important predictors for chorioamnionitis in the PPROM group by the multivariate logistic regression analysis. When the ROC curve analysis for prolidase, MMP-13, TOS, TAC, and PON-1 were performed, all of them were statistically significant for area under the curve (areas under the curve were 0.94, 0.90, 0.80, 0.25, and 0.19, respectively).

CONCLUSIONS

This study showed that collagen turnover mediators, especially prolidase, and increased oxidative stress are significantly associated with PPROM. Also, chorioamnionitis can be predicted with prolidase, MMP-13, TOS, TAC, and PON-1 in PPROM patients.

Maternal plasma prolidase, matrix metalloproteinases 1 and 13, and oxidative stress levels in pregnancies complicated by preterm premature rupture of the membranes and chorioamnionitis

OBJECTIVE

This study aimed to investigate the role of various biochemical markers in preterm premature rupture of membranes (PPROM) and in prediction of chorioamnionitis in patients with PPROM.

MATERIAL AND METHODS

This case-control study included a total of 100 pregnant women at 26-34 gestational weeks. Of these women, 50 were healthy and 50 had PPROM. The biochemical markers in the maternal plasma including prolidase, matrix metalloproteinase (MMP) 1 and 13, total oxidative status (TOS), total antioxidant capacity (TAC), glutathione peroxidase (GPx), catalase (CAT), paraoxonase-1 (PON-1), tumor necrosis factor alpha (TNF-α), and high sensitive C-reactive protein (hs-CRP) were assayed. These levels were compared between the PPROM and control groups and between women with or without chorioamnionitis in the PPROM group.

RESULTS

Compared to the control group, the levels of prolidase, MMP-13, and TOS were significantly higher (p values <0.001, 0.020, and 0.035, respectively) and those of TAC and PON-1 were significantly lower in the maternal plasma of the PPROM group (p values=0.012 and <0.001, respectively). The plasma prolidase and TOS levels were significantly higher (p values=0.033 and 0.005, respectively) and the plasma TAC and PON-1 levels were significantly lower in women with chorioamnionitis as compared with the corresponding values in women without chorioamnionitis in the PPROM group (p values =0.041 and 0.048, respectively). The multivariate logistic regression analysis observed that prolidase, TAC, and PON-1 were important markers for the presence of PPROM and prolidase and TOS were important markers for predicting chorioamnionitis.

CONCLUSION

This study suggested that maternal plasma prolidase, TAC, and PON-1 may be useful for the diagnosis of PPROM, and prolidase and TOS may be used to predict chorioamnionitis in patients with PPROM.

Acute effect of phosphodiesterase type 5 inhibitor on serum oxidative status and prolidase activities in men with erectile dysfunction

OBJECTIVES

To investigate the acute effect of phosphodiesterase type 5 (PDE5) inhibitor on erectile dysfunction by evaluating serum oxidative status and prolidase activity.

METHODS

Serum samples of 36 patients with erectile dysfunction and 30 control cases were analyzed for total antioxidant status, total oxidant status, and prolidase activity, before and after the administration of tadalafil citrate.

RESULTS

Before and after tadalafil citrate administration, serum total antioxidant status, total oxidant status, and prolidase were 1.1+0.0 vs. 1.6 + 0.0 umol H₂O₂ Eq/L, 10.3+1.1 vs. 6.9 + 1.2 umol H₂O₂ Eq/L, and 236.4+19.5 vs. 228.2 + 19.2 U/L, respectively (p < 0.0001 for all).

CONCLUSIONS

Evaluation of serum oxidative status and prolidase activity confirmed the beneficial acute effects of PDE5 inhibitor in patients with erectile dysfunction.

Collagen metabolism disturbances are accompanied by an increase in prolidase activity in lung carcinoma planoepitheliale

One of the consequences of neoplastic transformation is deregulation of tissue collagen metabolism. Although metalloproteinases initiate the breakdown of collagen in lung carcinoma, the final step of collagen degradation is mediated by prolidase (E.C.3.4.13.9). We investigated whether prolidase activity could reflect disturbances of collagen metabolism in human lung carcinoma planoepitheliale (Ca pl.). Ten human lung Ca pl. and 10 samples of normal lung parenchyma were compared with respect to prolidase activity and expression (western immunoblot), the content of collagen and collagen degradation products (free and bound hydroxyproline determination), beta1 integrin subunit expression (western immunoblot) and collagenolytic activity (zymography). An increase in collagen content (66%, P < 0.05), free proline pool (50%, P < 0.05) and collagenolytic activity was accompanied by a significant increase in the prolidase activity (106%, P < 0.05) and its expression in Ca pl. No differences were found between Ca pl. and the control lung tissue with respect to beta1 integrin expression. Prolidase activity may reflect disturbances in tissue collagen metabolism in lung Ca pl. and it may, therefore, serve as a sensitive marker of the disease.