Prolidase-dependent regulation of collagen biosynthesis

Proline oxidase silencing induces proline-dependent pro-survival pathways in MCF-7 cells

Proline degradation by proline dehydrogenase/proline oxidase (PRODH/POX) contributes to apoptosis or autophagy. The identification of specific pathway of apoptosis/survival regulation is the aim of this study. We generated knocked-down PRODH/POX MCF-7 breast cancer cells (MCF-7^shPRODH/POX). PRODH/POX silencing did not affect cell viability. However, it contributed to decrease in DNA and collagen biosynthesis, increase in prolidase activity and intracellular proline concentration as well as increase in the expression of iNOS, NF-κB, mTOR, HIF-1α, COX-2, AMPK, Atg7 and Beclin-1 in MCF-7^shPRODH/POX cells. In these cells, glycyl-proline (GlyPro, substrate for prolidase) further inhibited DNA and collagen biosynthesis, maintained high prolidase activity, intracellular concentration of proline and up-regulated HIF-1α, AMPK, Atg7 and Beclin-1, compared to GlyPro-treated MCF-7 cells. In MCF-7 cells, GlyPro increased collagen biosynthesis, concentration of proline and expression of caspase-3, cleaved caspases -3 and -9, iNOS, NF-κB, COX-2 and AMPKβ. PRODH/POX knock-down contributed to pro-survival autophagy pathways in MCF-7 cells and GlyPro-derived proline augmented this process. However, GlyPro induced apoptosis in PRODH/POX-expressing MCF-7 cells as detected by up-regulation of active caspases -3 and -9. The data suggest that PRODH/POX silencing induces autophagy in MCF-7 cells and GlyPro-derived proline supports this process.

Dexmedetomidine and Magnesium Sulfate: A Good Combination Treatment for Acute Lung Injury?

Objectives: In this study, we aimed to investigate the therapeutic effects of magnesium sulfate (MgSO₄) and dexmedetomidine (dex) in a model of acute lung injury (ALI). We determined whether concomitant administration decreased the inflammatory effects of hydrochloric acid (HCl)-induced ALI in a synergistic manner. Materials and Methods: In this study, 42 Sprague-Dawley rats were randomized into six groups: Group S (saline), Group SV (saline + mechanical ventilation), Group HCl (HCl), Group Dex (Dex), Group Mag (MgSO₄), and Group DM (Dex + MgSO₄). All groups except Group S were mechanically ventilated prior to HCl-induced ALI. Saline or HCl was administered via tracheostomy. Prior to treatment, HCl was administered to Group HCl, Group Dex, Group Mag, and Group DM to induce ALI. Dex and MgSO₄ were administered intraperitoneally. The rats were monitored for 4 h after treatment to measure oxidative stress parameters in blood, and prolidase enzyme activity. Lung tissue damage were determined via histopathology. Results: A significant increase in heart rate and rapid desaturation was observed in HCl-administered groups. Treatment administration decreased the pulse values. Increased saturation values and decreased oxidative stress indices were observed in groups that were subsequently administered​ Dex and MgSO₄. Serum prolidase activity increased significantly in Group HCl. Severe pathological findings were detected following HCl-induced ALI. Group Mag showed greater improvement in the pathology of HCl-induced ALI than did Group Dex. Administration of both Dex and MgSO₄ did not improve the pathological scores. Conclusions: The antioxidant and anti-inflammatory effects of Dex and MgSO₄ ameliorated the detrimental effects of HCI-induced ALI. However, adverse effects on hemodynamics and lung damage were observed when the two drugs were administered together.

PEPD is a pivotal regulator of p53 tumor suppressor

p53 tumor suppressor responds to various cellular stresses and regulates cell fate. Here, we show that peptidase D (PEPD) binds and suppresses over half of nuclear and cytoplasmic p53 under normal conditions, independent of its enzymatic activity. Eliminating PEPD causes cell death and tumor regression due to p53 activation. PEPD binds to the proline-rich domain in p53, which inhibits phosphorylation of nuclear p53 and MDM2-mediated mitochondrial translocation of nuclear and cytoplasmic p53. However, the PEPD-p53 complex is critical for p53 response to stress, as stress signals doxorubicin and H₂O₂ each must free p53 from PEPD in order to achieve robust p53 activation, which is mediated by reactive oxygen species. Thus, PEPD stores p53 for the stress response, but this also renders cells dependent on PEPD for survival, as it suppresses p53. This finding provides further understanding of p53 regulation and may have significant implications for the treatment of cancer and other diseases.

p53 is a pivotal tumour suppressor that is activated by various cellular stress inducers. Here, the authors show that peptidase D (PEPD) promotes the growth of cancer cells by suppressing p53 and that the complex PEPD-p53 is critical for robust p53 activation in response to stress signals.

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.

Acetylenic derivative of betulin induces apoptosis in endometrial adenocarcinoma cell line

Since betulin (Bet) and its acetylenic derivative, 28-O-propynoylbetulin (proBet) were shown to induce apoptosis in several cancer cell lines, we studied the mechanism of this process in human endometrial adenocarcinoma cells (EA). Previous studies suggested that this group of compounds affect prolidase activity (proline releasing enzyme from imidodipeptides) and collagen biosynthesis (proline utilizing process) providing substrate (proline) for proline oxidase (POX) dependent apoptosis. Here we provide evidence that Bet and proBet exhibit prolidase-inducing activity in EA cell line. However, in contrast to Bet, proBet inhibited collagen biosynthesis, increased intracellular proline concentration and induced apoptosis in EA cells, as detected by caspase-3, and -9 expressions and annexin V staining. Although POX expression was not affected by both compounds, the process of apoptosis was accompanied by increase in cytoplasmic level of proline. The mechanism for proBet-induced prolidase activity was found at the level of β1 integrin signaling. The inhibition of collagen biosynthesis was due to up-regulation of NF-κB p65, an inhibitor of collagen type I gene transcription. Although Bet and proBet induced expression of pro-apoptotic p53 in EA cells, the effect of proBet on the processes was much stronger. In contrast to proBet, Bet strongly induced expression of pro-survival factors, HIF-1α and VEGF. The data suggest that massive production of proline by proBet-dependent activation of prolidase and inhibition of proline utilization for collagen biosynthesis may represent mechanism for POX-dependent apoptosis in EA cells.

Oxidative stress and chronic inflammation in osteoarthritis: can NRF2 counteract these partners in crime?

Osteoarthritis (OA) is an age-related joint degenerative disease associated with pain, joint deformity, and disability. The disease starts with cartilage damage but then progressively involves subchondral bone, causing an imbalance between osteoclast-driven bone resorption and osteoblast-driven remodeling. Here, we summarize the data for the role of oxidative stress and inflammation in OA pathology and discuss how these two processes are integrated during OA progression, as well as their contribution to abnormalities in cartilage/bone metabolism and integrity. At the cellular level, oxidative stress and inflammation are counteracted by transcription factor nuclear factor erythroid p45-related factor 2 (NRF2), and we describe the regulation of NRF2, highlighting its role in OA pathology. We also discuss the beneficial effect of some phytonutrients, including the therapeutic potential of NRF2 activation, in OA.

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.

Collagen-derived proline promotes pancreatic ductal adenocarcinoma cell survival under nutrient limited conditions

Tissue architecture contributes to pancreatic ductal adenocarcinoma (PDAC) phenotypes. Cancer cells within PDAC form gland-like structures embedded in a collagen-rich meshwork where nutrients and oxygen are scarce. Altered metabolism is needed for tumour cells to survive in this environment, but the metabolic modifications that allow PDAC cells to endure these conditions are incompletely understood. Here we demonstrate that collagen serves as a proline reservoir for PDAC cells to use as a nutrient source when other fuels are limited. We show PDAC cells are able to take up collagen fragments, which can promote PDAC cell survival under nutrient limited conditions, and that collagen-derived proline contributes to PDAC cell metabolism. Finally, we show that proline oxidase (PRODH1) is required for PDAC cell proliferation in vitro and in vivo. Collectively, our results indicate that PDAC extracellular matrix represents a nutrient reservoir for tumour cells highlighting the metabolic flexibility of this cancer.

Cancer cells adapt their metabolism to survive limited nutrient availability. Here, the authors show that in conditions of limited glucose or glutamine availability, pancreatic ductal adenocarcinoma cells can use collagen-derived proline to foster the TCA cycle and allow cell survival both in vitro and in vivo.

Exogenous proline stimulates type I collagen and HIF-1α expression and the process is attenuated by glutamine in human skin fibroblasts

Abundance of proline (Pro) in collagen molecule led us to investigate whether Pro supply affects collagen biosynthesis in human skin fibroblasts. Treatment of the cells with milimolar concentrations (5 and 10 mM) of Pro for 24 and 48 h contributed to increase in α₁ subunit of collagen type I (COL1A1) expression in both cells and culture medium. However, the effect was more pronounced in glutamine-free medium. In such condition, Pro induced collagen expression by about twofold in the cells, while in the medium only by about 30% during 24 h incubation, compared to control. In the presence of glutamine (Gln), exogenous Pro stimulated intracellular collagen expression only by about 30% during 24 h of fibroblasts incubation, and it was not accompanied by adequate increase of collagen secretion into medium. Gln alone stimulated the processes by about 2–3 fold during the course of the experiment. Pro-dependent increase in collagen expression in Gln-free medium was accompanied by increase in prolidase activity and expression of pAkt. In both Gln-free medium and Gln-supplemented medium, Pro induced expression of p53 and HIF-1α. The data suggest that availability of Gln, as a substrate for Pro biosynthesis, determine the utilization of exogenous Pro for the collagen biosynthesis.

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.

Potential diagnostic and prognostic significance of plasma prolidase activity in gastric cancer

Aim: Plasma prolidase activities (PPAs) in cases of gastric cancer. Methodology/results: This study was based on a prospective design. 60 patients with gastric cancer (operable cases: 48; inoperable: 12) and 60 healthy controls were included in the study. Prolidase activity was analyzed. The mean PPA levels in the operable, inoperable and control groups were 45.60 ± 4.20, 54.35 ± 4. 9 and 10.92 ± 0.79 U/l, respectively (p < 0.001). PPA decreased significantly after tumor resection. PPA level was significant in differentiating operable cases from inoperable (sensitivity: 91.7%; specificity: 85.2%). Discussion/conclusion: PPA was significantly higher in patients with inoperable gastric cancer than in operable cases and the control group. A strong correlation was found between tumor volume and PPA.

Comparison of protective effect of ascorbic acid on redox and endocannabinoid systems interactions in in vitro cultured human skin fibroblasts exposed to UV radiation and hydrogen peroxide

The mechanisms of biological activity of commonly used natural compounds are constantly examined. Therefore, the aim of this study was to compare ascorbic acid efficacy in counteracting the consequences of UV and hydrogen peroxide treatment on lipid mediators and their regulative action on antioxidant abilities. Skin fibroblasts exposed to UVA and UVB irradiation, treated with hydrogen peroxide and ascorbic acid. The redox system was estimated through reactive oxygen species (ROS) generation (electron spin resonance spectrometer) and antioxidants level/activity (HPLC/spectrometry) which activity was evaluated by the level of phospholipid metabolites: 4-hydroxynonenal, malondialdehyde, 8-isoprostanes and endocannabinoids (GC/LC-MS) in the human skin fibroblasts. Protein and DNA oxidative modifications were also determined (LC). The expression of nuclear factor erythroid 2-related factor 2 (Nrf2), its activators and inhibitors as well as pro/anti-apoptotic proteins and endocannabinoid receptors was examined (Western blot) and collagen metabolism was evaluated by collagen biosynthesis and prolidase activity (spectrometry). UVA and UVB irradiation and hydrogen peroxide treatment enhanced activity of xanthine and NADPH oxidases resulting in ROS generation as well as diminution of antioxidant phospholipid protection (glutathione peroxidase-glutathione-vitamin E), what led to increased lipid peroxidation and decreased endocannabinoids level. Dysregulation of cannabinoid receptors expression and environment of transcription factor Nrf2 caused apoptosis induction. Ascorbic acid partially prevented ROS generation, antioxidant capacity diminution and endocannabinoid systems disturbances but only slightly protected macromolecules such as phospholipid, protein and DNA against oxidative modifications. However, ascorbic acid significantly prevented decrease in collagen type I biosynthesis. Ascorbic acid in similar degree prevents UV (UVA and UVB) and hydrogen peroxide-dependent redox imbalance. However, this antioxidant cannot efficiently protect cellular macromolecules and avert metabolic dysregulation leading to apoptosis.

The Overexpression of NALP3 Inflammasome in Knee Osteoarthritis Is Associated with Synovial Membrane Prolidase and NADPH Oxidase 2

Osteoarthritis is characterized by the presence of proinflammatory cytokines and reactive oxygen species. We aimed to clarify the role of prooxidant enzyme content at the synovial membrane level and how it correlates with the inflammatory process in patients with knee osteoarthritis (KOA). In synovial membranes from KOA patients and control group, we analyzed the protein content of prooxidant enzymes such as Nox2, xanthine oxidase (XO), and prolidase as well as the proinflammatory NALP3. Results show that protein content of prolidase and Nox2 increased 4.8- and 8.4-fold, respectively, and XO showed an increasing trend, while the NALP3 inflammasome increased 5.4-fold with respect to control group. Levels of prolidase and XO had a positive correlation between the levels of NALP3 and Nox2. By principal component analysis the protein expression pattern by study groups was evaluated. Three clusters were identified; protein expression patterns were higher for clusters two (prolidase) and three (XO and Nox2) between KOA patients and controls. Data suggest that prooxidant enzymes increase in synovial membrane of KOA patients and may contribute to the inflammatory state and degradation of the articular cartilage.

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.

Flavivirus Antagonism of Type I Interferon Signaling Reveals Prolidase as a Regulator of IFNAR1 Surface Expression

Type I interferon (IFN-α/β or IFN-I) signals through two receptor subunits, IFNAR1 and IFNAR2, to orchestrate sterile and infectious immunity. Cellular pathways that regulate IFNAR1 are often targeted by viruses to suppress the antiviral effects of IFN-I. Here we report that encephalitic flaviviruses, including tick-borne encephalitis virus and West Nile virus, antagonize IFN-I signaling by inhibiting IFNAR1 surface expression. Loss of IFNAR1 was associated with binding of the viral IFN-I antagonist, NS5, to prolidase (PEPD), a cellular dipeptidase implicated in primary immune deficiencies in humans. Prolidase was required for IFNAR1 maturation and accumulation, activation of IFNβ-stimulated gene induction, and IFN-I-dependent viral control. Human fibroblasts derived from patients with genetic prolidase deficiency exhibited decreased IFNAR1 surface expression and reduced IFNβ-stimulated signaling. Thus, by understanding flavivirus IFN-I antagonism, prolidase is revealed as a central regulator of IFN-I responses.

Draft Genome Sequence of Lactobacillus farciminis NBRC 111452, Isolated from Kôso, a Japanese Sugar-Vegetable Fermented Beverage

Here, we report the draft genome sequence of the Lactobacillus farciminis strain NBRC 111452, isolated from kôso, a Japanese sugar-vegetable fermented beverage. This genome information is of potential use in studies of Lactobacillus farciminis as a probiotic.

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.

The Value of Serum Prolidase Activity in Progression of Microalbuminuria in Patients With Type 2 Diabetes Mellitus

BACKGROUND

Prolidase is a cytosolic exopeptidase that plays a pivotal role in collagen turnover. Diabetic nephropathy (DN) is associated with structural changes in glomerular basement membrane accompanied with increased amounts of collagen. Prolidase is known to be abundant in kidney and collagen accumulation is increased in DN, so we aimed to determine the value of serum prolidase activity (SPA) in predicting the progression of nephropathy in type 2 diabetes mellitus (DM).

METHODS

Thirty type 2 DM patients having microalbuminuria (microalbuminuric group), 30 type 2 DM patients without albuminuria (normoalbuminuric group), and 28 healthy controls (control group) were enrolled. Study groups had similar age, sex distribution, and body mass index (BMI).

RESULTS

Metabolic parameters, SPA and urinary microalbumin were determined. SPA was significantly higher in microalbuminuric group when compared with normoalbuminuric and control groups (P = 0.05 and P < 0.001, respectively). Triglyceride levels were significantly higher and high density lipoprotein cholesterol (HDL-C) levels were significantly lower in microalbuminuric group compared to control group (Both P < 0.05). SPA showed a negative correlation with HDL-C level and a positive correlation with urinary albumin excretion (r = -0.219, P < 0.05 and r = 0.39, P < 0.001 respectively). In regression analysis, albumin excretion was the sole parameter influencing SPA.

CONCLUSION

SPA appears to be higher in type 2 DM patients having microalbuminuria compared to patients without microalbuminuria and healthy controls. The pathophysiological role and the significance of SPA in predicting DN need to be further evaluated.

Hyaluronic acid abrogates ethanol-dependent inhibition of collagen biosynthesis in cultured human fibroblasts

Introduction

The aim of the study was to evaluate the effect of ethanol on collagen biosynthesis in cultured human skin fibroblasts, and the role of hyaluronic acid (HA) in this process. Regarding the mechanism of ethanol action on human skin fibroblasts we investigated: expression of β₁ integrin and insulin-like growth factor 1 receptor (IGF-IR), signaling pathway protein expression: mitogen-activated protein kinases (MAPKs), protein kinase B (Akt), nuclear factor kappa B (NF-κB) transcription factor, cytotoxicity assay and apoptosis, metalloproteinase activity, as well as the influence of HA on these processes.

Materials and methods

Collagen biosynthesis, activity of prolidase, DNA biosynthesis, and cytotoxicity were measured in confluent human skin fibroblast cultures that have been treated with 25, 50, and 100 mM ethanol and with ethanol and 500 µg/mL HA. Western blot analysis and zymography were performed to evaluate expression of collagen type I, β₁ integrin receptor, IGF-IR, NF-κB protein, phospho-Akt protein, kinase MAPK, caspase 9 activity, and matrix metalloproteinases (MMP-9 and MMP-2).

Results

Ethanol in a dose-dependent manner lead to the impairment of collagen biosynthesis in fibroblast cultures through decreasing prolidase activity and expression of β₁ integrin and IGF-IR. This was accompanied by an increased cytotoxicity, apoptosis and lowered expression of the signaling pathway proteins induced by β₁ integrin and IGF-IR, that is, MAPK (ERK_1/2) kinases. The lowered amount of synthesized collagen and prolidase activity disturbance may also be due to the activation of NF-κB transcription factor, which inhibits collagen gene expression. It suggests that the decrease in fibroblast collagen production may be caused by the disturbance in its biosynthesis but not degradation. The application of HA has a protective effect on disturbances caused by the examined substances. It seems that regulatory mechanism of ethanol-induced collagen aberration take place at the level of collagen biosynthesis, since no effect of ethanol and HA was found on process of collagen degradation by MMP-2 and MMP-9.

Conclusion

This study provides evidence that ethanol impairs collagen metabolism in human skin fibroblasts, leading to a significant decrease in the amount of produced protein. This mechanism probably is due to downregulation of prolidase activity, expression of β₁ integrin and IGF-IR receptors, and the signaling pathway proteins induced by these receptors.

Prolidase Enzyme Activity in Conjunctiva and Pterygium Tissues

Background

The aim of this study was to determine prolidase activity in conjunctival tissue and its relationship with pterygium.

Material/Methods

Prolidase activity was measured in 23 pterygium and 25 healthy conjunctival tissues and the 2 groups were compared.

Results

Prolidase enzyme activity could not be measured in either the healthy conjunctival or in pterygium tissues. The mean serum prolidase levels of the control and pterygium groups were 967.46±353.64 and 858.29±301.83, respectively. Statistically, there was no significant difference between the groups with regard to serum prolidase levels (p>0.05).

Conclusions

In conclusion, absence of prolidase activity in pterygium tissue indicates that there is no collagen turnover in this tissue. We may explain this finding with the elastin-rich structure of the conjunctiva.

Evaluation of serum prolidase activity in patients with slow coronary flow

INTRODUCTION

Slow coronary flow (SCF) is described as the slow passage of contrast to distal coronaries despite anatomically normal coronary arteries. It has been shown that increased serum prolidase activity (SPA) correlates with collagen turnover. Increased collagen turnover might be associated with the development of atherosclerotic plaques.

AIM

To investigate the relationship between serum prolidase activity and slow coronary flow.

MATERIAL AND METHODS

This cross-sectional study included 40 SCF patients (mean age: 55.0 ±9.5 years, 20 females) and 40 controls (mean age: 53.9 ±8.2 years, 21 females) with normal coronary anatomy and normal coronary flow. The Thrombolysis in Myocardial Infarction (TIMI) frame-count (TFC) method was used for SCF diagnosis. Serum prolidase activity was measured spectrophotometrically, and the relevant parameters were compared between the groups.

RESULTS

There were no statistically significant differences between the SCF and control groups in terms of basic demographic, clinical, and laboratory data. However, the SPA was significantly higher in the SCF group compared to the control (702.7 ±13.8 and 683.9 ±13.2 respectively, p<0.001). Serum prolidase activity was significantly correlated with the mean TFC (r=0.463, p<0.001). The overall findings of this study support the predictive accuracy of the serum prolidase activity in our cohort, with a statistically significant ROC value of 681.3.

CONCLUSIONS

Our study showed that SPA was increased in SCF patients. The activity of this enzyme was significantly correlated with the mean TFC.

Plasma Prolidase Activity and Oxidative Stress in Patients with Parkinson's Disease

Prolidase deficiency has been related to mental retardation and oxidative stress. The study aimed to observe plasma prolidase activity (PPA), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) in patients with Parkinson's disease (PD). 240 subjects with PD and 150 healthy volunteers were considered as cases and controls, respectively. PPA, TOS, TAS, and OSI were measured spectrophotometrically. PPA and TAS in cases were more significantly decreased than controls (P < 0.01), while TOS and OSI were significantly increased (P < 0.001). In cases, nonsignificant, positive correlation was observed between PPA and TOS and OSI while significant, negative correlation was observed between PPA and TAS (P = 0.047). PPA in cases was nonsignificantly decreased with increased duration of PD (P = 0.747) while TAS was significantly decreased (P < 0.001) and TOS and OSI were significantly increased (P < 0.001). It was observed that higher age groups had decreased PPA, and TAS and increased TOS and OSI compared to lower age groups in cases. In summary, patients with PD have decreased PPA and increased oxidative stress compared to healthy volunteers. PPA was associated with oxidative stress markers in patients with PD. Decreased PPA and TAS and increased TOS and OSI were associated with progression of disease and higher age.

Assessment of the correlation between serum prolidase and alpha-fetoprotein levels in patients with hepatocellular carcinoma

AIM: To determine the predictive value of increased prolidase activity that reflects increased collagen turnover in patients with hepatocellular carcinoma (HCC).

METHODS: Sixty-eight patients with HCC (mean age of 69.1 ± 10.1), 31 cirrhosis patients (mean age of 59.3 ± 6.3) and 33 healthy volunteers (mean age of 51.4 ± 12.6) were enrolled in this study. Univariate and multivariate analysis were used to evaluate the association of serum α-fetoprotein (AFP) values with HCC clinicopathological features, such as tumor size, number and presence of vascular and macrovascular invasion. The patients with HCC were divided into groups according to tumor size, number and presence of vascular invasion (diameters; ≤ 3 cm, 3-5 cm and ≥ 5 cm, number; 1, 2 and ≥ 3, macrovascular invasion; yes/no). Barcelona-clinic liver cancer (BCLC) criteria were used to stage HCC patients. Serum samples for measurement of prolidase and alpha-fetoprotein levels were kept at -80 °C until use. Prolidase levels were measured spectrophotometrically and AFP concentrations were determined by a chemiluminescence immunometric commercial diagnostic assay.

RESULTS: In patients with HCC, prolidase and AFP values were evaluated according to tumor size, number, presence of macrovascular invasion and BCLC staging classification. Prolidase values were significantly higher in patients with HCC compared with controls (P < 0.001). Prolidase levels were significantly associated with tumor size and number (P < 0.001, P = 0.002, respectively). Prolidase levels also differed in patients in terms of BCLC staging classification (P < 0.001). Furthermore the prolidase levels in HCC patients showed a significant difference compared with patients with cirrhosis (P < 0.001). In HCC patients grouped according to tumor size, number and BCLC staging classification, AFP values differed separately (P = 0.032, P = 0.038, P = 0.015, respectively). In patients with HCC, there was a significant correlation (r = 0.616; P < 0.001) between prolidase and AFP values in terms of tumor size, number and BCLC staging classification, whereas the presence of macrovascular invasion did not show a positive association with serum prolidase and AFP levels.

CONCLUSION: Considering the levels of both serum prolidase and AFP could contribute to the early diagnosing of hepatocellular carcinoma.

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.

Enalapril stimulates collagen biosynthesis through prolidase-dependent mechanism in cultured fibroblasts

The mechanism of a lower incidence of dermatological manifestations in patients treated with enalapril compared to patients treated with other ACE-inhibitors, e.g., captopril, is not known. The finding that prolidase plays an important role in collagen biosynthesis and that some angiotensin-converting enzyme inhibitors affect prolidase activity led us to evaluate its effect on collagen biosynthesis in cultured human skin fibroblasts. Since insulin-like growth factor (IGF-I) and transforming growth factor beta 1 (TGF-β1) are the most potent stimulators of both collagen biosynthesis and prolidase activity, and prolidase is regulated by β₁ integrin signaling, the effect of enalapril and enalaprilat on IGF-IR, TGF-β1, and β₁ integrin receptor expressions was evaluated. Cells were treated with milimolar concentrations (0.3 and 0.5 mM) of enalapril and enalaprilat for 24 h. The activity of prolidase was determined by colorimetic assay. Collagen biosynthesis was evaluated by radiometric assay. Expression of signaling proteins was evaluated using Western blot. It was found that enalapril- and enalaprilat-dependent increase in prolidase activity and expression was accompanied by parallel increase in collagen biosynthesis. The exposure of the cells to 0.5 mM enalapril and enalaprilat contributed to increase in IGF-IR and α₂β₁ integrin receptor as well as TGF-β1 and NF-κB p65 expressions. Enalapril- and enalaprilat-dependent increase of collagen biosynthesis in fibroblasts results from increase of prolidase activity and expression, which may undergo through activation of α₂β₁ integrin and IGF-IR signaling as well as upregulation of TGF-β1 and NF-κB p65, the inhibitor of collagen gene expression.

Effect of Nigella sativa Linn oil on tramadol-induced hepato- and nephrotoxicity in adult male albino rats

The present study was carried out to evaluate the role of Nigella sativa Linn (NsL) oil against subacute tramadol-induced hepatotoxicity, nephrotoxicity as well as oxidative stress in adult male albino rats. Sixty adult male albino rats were divided into four groups. Group I: control group; 30 rats equally subdivided into: Ia; −ve control group, Ib; +ve control group received saline, Ic; +ve control group received corn oil. Group II: 10 rats received NsL oil; 1 mg/kg in 1 ml corn oil/day, group III: 10 rats received tramadol; 30 mg/kg/day, group IV: 10 rats received tramadol + NsL oil in the previous doses. Treatments were given by gavage for 30 days. Then rats were sacrificed and specimens from the livers and kidneys were taken for biochemical and histopathological study. Biochemical data showed elevated liver enzymes; alanine transaminase (ALT), aspartate transaminase (AST), gamma glutamyltransferase (GGT), bilirubin as well as urea and creatinine in tramadol group. A significant increase in hepatic and renal malondialdehyde (MDA) and a decrease in glutathione peroxidase (GPx) levels were also noticed. Histological analysis of the liver showed vacuolated hepatocyte cytoplasm indicating hydropic degeneration with binucleated cells, apoptotic nuclei, congested central veins, cellular infiltration and hemorrhage. Kidney sections revealed atrophied glomeruli with collapsed tufts and wide Bowman's space, degenerated tubules, hemorrhage and mononuclear cellular infiltration. There was also an increase in area % of collagen fibers in both organs. Concomitant use of NsL oil with tramadol induced partial improvement in the hepato- and nephrotoxic effects. In conclusion, this study suggested that concomitant use of NsL oil with tramadol proved to be capable of ameliorating tramadol-induced hepato- and nephrotoxicity which might be due to its antioxidant potential.

Lack of prolidase causes a bone phenotype both in human and in mouse

The degradation of the main fibrillar collagens, collagens I and II, is a crucial process for skeletal development. The most abundant dipeptides generated from the catabolism of collagens contain proline and hydroxyproline. In humans, prolidase is the only enzyme able to hydrolyze dipeptides containing these amino acids at their C-terminal end, thus being a key player in collagen synthesis and turnover. Mutations in the prolidase gene cause prolidase deficiency (PD), a rare recessive disorder. Here we describe 12 PD patients, 9 of whom were molecularly characterized in this study. Following a retrospective analysis of all of them a skeletal phenotype associated with short stature, hypertelorism, nose abnormalities, microcephaly, osteopenia and genu valgum, independent of both the type of mutation and the presence of the mutant protein was identified. In order to understand the molecular basis of the bone phenotype associated with PD, we analyzed a recently identified mouse model for the disease, the dark-like (dal) mutant. The dal/dal mice showed a short snout, they were smaller than controls, their femurs were significantly shorter and pQCT and μCT analyses of long bones revealed compromised bone properties at the cortical and at the trabecular level in both male and female animals. The differences were more pronounce at 1 month being the most parameters normalized by 2 months of age. A delay in the formation of the second ossification center was evident at postnatal day 10. Our work reveals that reduced bone growth was due to impaired chondrocyte proliferation and increased apoptosis rate in the proliferative zone associated with reduced hyperthrophic zone height. These data suggest that lack of prolidase, a cytosolic enzyme involved in the final stage of protein catabolism, is required for normal skeletogenesis especially at early age when the requirement for collagen synthesis and degradation is the highest.

Systemic Prolidase Activity and Oxidative Stress in Keratoconus

AIM

Our aim was to evaluate the serum prolidase activity, total antioxidant capacity (TAC) and total oxidant status (TOS) in patients with keratoconus.

MATERIAL AND METHOD

A total 69 keratoconus patients and 72 control subjects with similar age and gender were evaluated within the scope of this study. The keratoconus group was divided into four stages with the modified Krumeich classification. Serum prolidase activity, TAC and TOS were measured and compared between the patient and control groups.

RESULTS

The median serum prolidase enzyme activity value was 528.3 (684.1-416.7) U/L in the keratoconus group and 606.2 (812.9-482.3) U/L in the control group. The difference between the groups was statistically significant (p = 0.027). The median TAC value was 1.24 (1.37-1.05) mmol/L in the keratoconus group and 1.29 (1.38-1.18) mmol/L in the control group. The median TOS value was 2 (4-1) μmol/L in the keratoconus group and 3 (4-2) μmol/L in the control group. There was no statistically significant difference between the two groups in terms of TAC or TOS (p = 0.113 and p = 0.366, respectively). There was a positive correlation between TAC and TOS in keratoconus group but not in the control group (r = 0.670, p = 0.001 and r = 0.141, p = 0.241, respectively). No significant relationship was seen between the keratoconus group stages and serum prolidase activity, TAS or TOS (p = 0.894, p = 0.155 and p = 0.381, respectively).

CONCLUSION

In conclusion, a significant relationship was found between decreased serum prolidase activity and keratoconus but there was no significant relationship between keratoconus and serum TAC or TOS.

The mechanism of oxythiamine-induced collagen biosynthesis in cultured fibroblasts

The oxythiamine (OXY) is antivitamin of thiamine. The finding that OXY increases the cytoplasmic concentration of pyruvate, known to enhance collagen biosynthesis, led us to investigate the mechanism of this antivitamin action on collagen biosynthesis in cultured human skin fibroblasts. Confluent fibroblasts were treated with micromolar concentrations (30–1,000 µM) of OXY for 24 and 48 h. It was found that OXY-dependent increase in collagen biosynthesis was accompanied by parallel increase in prolidase activity and level, compared to untreated cells. Since phosphoenolpyruvate (PEP) is known as an inhibitor of prolidase—the enzyme that plays important role in collagen biosynthesis, the mechanism of pyruvate interconversion was considered as a regulatory switch in collagen biosynthesis. In fact, 3-MPA, specific inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), contributed to up-regulation of prolidase activity, suggesting that down-regulation of PEP formation is an underlying mechanism. Since collagen biosynthesis and prolidase activity are regulated by signal induced by activated α₂β₁ integrin receptor as well as insulin-like growth factor-I receptor (IGF-IR), the expression of these receptors was measured by Western immunoblot analysis. The exposure of the cells to OXY contributed to decrease in IGF-IR, α₂β₁ integrin receptor, pERK1/2, and NF-κB p65 expressions. It was accompanied by increase in total ERK1/2 expression and induction of phosphorylation of Akt protein. The data suggest that OXY-dependent increase of collagen biosynthesis in cultured human skin fibroblasts results from activation of prolidase activity and level, induction in pAkt expression and down-regulation of pERK1/2 and NF-κB p65, the known inhibitor of collagen gene expression.

Serum prolidase activity and oxidant-antioxidant status in children with chronic hepatitis B virus infection

BACKGROUND

Chronic hepatitis B (CHB) is a global health problem that can result in serious complications associated with collagen degradation. Prolidase is a specific imidodipeptidase that plays an important role in the breakdown of collagen. The aim of this study was to investigate prolidase activity and oxidant-antioxidant status in children with CHB.

METHODS

This prospective case control study includes 38 patients with CHB, 31 patients with inactive hepatitis B (IHB), and 29 healthy matched control subjects. Serum prolidase enzyme activity (SPEA), total antioxidant capacity (TAC), total oxidative activity (TOA), and malondialdehyde (MDA) level were measured and oxidative stress index (OSI) was calculated for each group.

RESULTS

Patients with CHB had significantly higher SPEA levels (207.82 ± 186.80 IU/L) than did the controls (58.6 ± 38.1 IU/L) and IHB patients (67.1 ± 39.9) (p < 0.001). CHB patients also had significantly higher TOA (45.0 ± 19.9 vs. 29.4 ± 11.7 (μmolH2O2 Eq./L), p = 0.005), OSI (33.1 ± 21.4 vs. 17.5 ± 10.2, p = 0.002) and MDA (13.4 ± 4.0 vs. 7.8 ± 2.6 μm/L, p < 0.001) values compared with the controls. TOA (32.0 ± 10.0) and OSI (15.4 ± 11.0) values of IHB patients were significantly lower than those of CHB patients (p < 0.05). SPEA had significant correlations with HBV- DNA and ALT values (r =0.514 and r =0.454, p < 0.001).

CONCLUSION

Our results suggest that prolidase activity can be considered as a reliable marker for CHB and increased oxidative stress appears to be related to chronicity of the disease.

Structural basis of substrate selectivity of E. coli prolidase

Prolidases, metalloproteases that catalyze the cleavage of Xaa-Pro dipeptides, are conserved enzymes found in prokaryotes and eukaryotes. In humans, prolidase is crucial for the recycling of collagen. To further characterize the essential elements of this enzyme, we utilized the Escherichia coli prolidase, PepQ, which shares striking similarity with eukaryotic prolidases. Through structural and bioinformatic insights, we have extended previous characterizations of the prolidase active site, uncovering a key component for substrate specificity. Here we report the structure of E. coli PepQ, solved at 2.0 Å resolution. The structure shows an antiparallel, dimeric protein, with each subunit containing N-terminal and C-terminal domains. The C-terminal domain is formed by the pita-bread fold typical for this family of metalloproteases, with two Mg(II) ions coordinated by five amino-acid ligands. Comparison of the E. coli PepQ structure and sequence with homologous structures and sequences from a diversity of organisms reveals distinctions between prolidases from Gram-positive eubacteria and archaea, and those from Gram-negative eubacteria, including the presence of loop regions in the E. coli protein that are conserved in eukaryotes. One such loop contains a completely conserved arginine near the catalytic site. This conserved arginine is predicted by docking simulations to interact with the C-terminus of the substrate dipeptide. Kinetic analysis using both a charge-neutralized substrate and a charge-reversed variant of PepQ support this conclusion, and allow for the designation of a new role for this key region of the enzyme active site.

Influence of caffeine and hyaluronic acid on collagen biosynthesis in human skin fibroblasts

Aim

The aim of this study was to evaluate the effect of caffeine on collagen biosynthesis in human skin fibroblasts and the influence of hyaluronic acid (HA) on this process.

Materials and methods

Collagen, [³H]-thymidine incorporation, and prolidase activity were measured in confluent human skin fibroblast cultures that had been treated with 1, 2, and 5 mM caffeine and with caffeine and 500 μg/mL HA. Western immunoblot analysis was performed to evaluate expression of β₁-integrin receptor, insulin-like growth factor receptor phospho-Akt protein and mitogen-activated protein kinase (phospho-extracellular signal-regulated kinase).

Results

Caffeine inhibited collagen biosynthesis in a dose-dependent manner. The mechanism of this process was found at the level of prolidase activity. Caffeine significantly inhibited the enzyme activity. The addition of HA had no effect on collagen biosynthesis or prolidase activity in fibroblasts incubated with caffeine. Caffeine also had an inhibitory effect on DNA biosynthesis. HA, however, did not have any significant effect on this process. The inhibition of the expression of β₁-integrin and insulin-like growth factor receptor in fibroblasts incubated with the caffeine indicates a possible mechanism of inhibition of collagen biosynthesis.

Conclusion

Caffeine reduces collagen synthesis in human cultured skin fibroblasts. HA did not have any significant protective effect on this process. This is the first study to our knowledge that reports caffeine-induced inhibition of collagen synthesis in human skin fibroblasts.

Serum prolidase activity and oxidative stress in diabetic nephropathy and end stage renal disease: a correlative study with glucose and creatinine

Association of oxidative stress and serum prolidase activity (SPA) has been reported in many chronic diseases. The study was aimed at evaluating the correlation of glucose and creatinine to SPA and oxidative stress in patients with diabetic nephropathy (DN) and end stage renal disease (ESRD) concerned with T2DM. 50 healthy volunteers, 50 patients with T2DM, 86 patients with DN, and 43 patients with ESRD were considered as control-1, control-2, case-1, and case-2, respectively. Blood glucose, creatinine, SPA, total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were measured by colorimetric tests. SPA, TOS, and OSI were significantly increased in case-1 and case-2 than control-1 and control-2, while TAS was significantly decreased (P < 0.001). Blood glucose was linearly correlated to SPA, TOS, TAS, and OSI in control-2, case-1 and case-2 (P < 0.001). Serum creatinine was linearly correlated with SPA, TOS, TAS and OSI in control-2 and case-1 (P < 0.001). In case-2, serum creatinine was significantly correlated with SPA only (P < 0.001). Thus, the study concluded that SPA and oxidative stress significantly correlated with blood glucose and creatinine. SPA, TOS, TAS, and OSI can be used as biomarkers for diagnosis of kidney damage.

Prolidase is required for early trafficking events during influenza A virus entry

Influenza A virus (IAV) entry is a multistep process that requires the interaction of the virus with numerous host factors. In this study, we demonstrate that prolidase (PEPD) is a cellular factor required by IAV for successful entry into target cells. PEPD was selected as a candidate during an entry screen performed on nonvalidated primary hits from previously published genome-wide small interfering RNA (siRNA) screens. siRNA-mediated depletion of PEPD resulted in the decreased growth of IAV during mono- and multicycle growth. This growth defect was independent of cell type or virus strain. Furthermore, IAV restriction was apparent as early as 3 h postinfection, and experiments in the absence of protein biosynthesis revealed that the nuclear import of viral ribonucleoprotein complexes (vRNPs) was already blocked in the absence of PEPD. These results led us to investigate which step during entry was affected. Receptor expression, IAV attachment, or IAV internalization was not dependent on the presence of PEPD. However, when looking at the distribution of incoming IAV particles in PEPD-knockdown cells, we found a localization pattern that differed from that in control cells: IAV mostly localized to the cell periphery, and consequently, viral particles displayed reduced colocalization with early and late endosome markers and fusion between viral and endosomal membranes was strongly reduced. Finally, experiments using a competitive inhibitor of PEPD catalytic activity suggested that the enzymatic function of the dipeptidase is required for its proviral effect on IAV entry. In sum, this study establishes PEPD as a novel entry factor required for early endosomal trafficking of IAV.

IMPORTANCE

Influenza A virus (IAV) continues to be a constant threat to public health. As IAV relies on its host cell for replication, the identification of host factors required by the virus is of importance. First, such studies often reveal novel functions of cellular factors and can extend our knowledge of cellular processes. Second, we can further our understanding of processes that are required for the entry of IAV into target cells. Third, the identification of host factors that contribute to IAV entry will increase the number of potential targets for the development of novel antiviral drugs that are of urgent need. Our study identifies prolidase (PEPD) to be a novel entry factor required by IAV for correct routing within the endosomal compartment following virus internalization. Thereby, we link PEPD, which has been shown to play a role during collagen recycling and growth factor signaling, to early events of viral infection.

Cross-talk between integrin receptor and insulin-like growth factor receptor in regulation of collagen biosynthesis in cultured fibroblasts

PURPOSE

Cellular processes are regulated by signals generated by adhesion receptors and growth factor receptors. IGFbinding protein 1 (IGFBP-1) is a molecule which may affect the both signaling pathways through inactivation of IGF-I (ligand for IGF-IR) and binding to RGD region of integrin receptors. Whether this phenomenon is important in communication between insulin-like growth factor receptor (IGF-IR) and β1-integrin receptor in regulation of prolidase activity and collagen biosynthesis is the aim of this study.

MATERIAL AND METHOD

We studied the effects of IGFBP-1, IGF-I, thrombin (integrin activator), echistatin (disintegrin), phosphatidylinositol 3-kinase inhibitor (LY-294002) and ERK 1/2 inhibitors (PD98059 and UO126) on prolidase activity, collagen biosynthesis and expression of proteins participating in pathways generated by these receptors.

RESULTS

Stimulation of β1-integrin and IGF-I receptors by standard ligands was proved to up-regulate collagen synthesis in cultured fibroblasts. IGFBP-1, similarly as echistatin and studied inhibitors, contributed to down-regulation of ERK1/2, Akt, mTOR expression and up-regulation of NFκB. It was accompanied by parallel decrease in prolidase activity and collagen biosynthesis.

CONCLUSION

The data suggest that "cross talk" between IGF-I receptor and integrin receptor may play important role in regulation of prolidase activity and collagen biosynthesis.

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.

Evaluation of antioxidative/oxidative status and prolidase parameters in cases of inguinal hernia with joint hypermobility syndrome

PURPOSE

Most previous reports have shown that the basic mechanism of inguinal hernia involves insufficient collagen strength and metabolism. The aim of this study was to evaluate whether joint hypermobility is involved in the development of inguinal hernia in children and to investigate oxidative stress parameters and prolidase activity in tissue samples from children with inguinal hernia.

METHODS

This cross-sectional study involving 41 patients (age, 6.36 ± 2.96 years) with inguinal hernia treated in the pediatric surgery department of our institution and 40 age- and sex-matched controls (age, 6.02 ± 3.13 years) was performed from May to December 2011. Joint hypermobility was assessed using the Beighton criteria in all patients. Hernia sacs were analyzed with respect to the total antioxidative/oxidative status and prolidase activity. The patients were divided into two groups (inguinal hernia with and without hypermobility) according to a Beighton score cut-off of ≥6.

RESULTS

A total of 81 subjects aged 3-10 years participated. The ratio of joint hypermobility was significantly higher in patients than in controls (p = 0.01). The prolidase activity, total oxidant status, and oxidative stress index were higher in tissue samples from patients with joint hypermobility (p < 0.001).

CONCLUSIONS

Our results show that joint hypermobility syndrome is associated with inguinal hernia in children and that increased prolidase activity and oxidative stress in tissue samples from patients with joint hypermobility syndrome are related to collagen tissue damage and turnover.

Serum prolidase enzyme activity and oxidative stress levels in patients with acute hemorrhagic stroke

BACKGROUND

It has been indicated that oxidative damage contributes to secondary brain injury in both ischemic and hemorrhagic stroke patients. Collagen is a major component of the extracellular matrix, and prolidase plays a role in collagen synthesis. The aim of this study was to evaluate the serum prolidase activity, nitric oxide (NO) levels, total antioxidant capacity (TAC) and total oxidant status (TOS) in patients with acute hemorrhagic stroke.

METHODS

Twenty-five patients with acute hemorrhagic stroke and 25 controls were enrolled. Serum prolidase activity, catalase activity, NO levels, TAC and TOS were measured spectrophotometrically. Oxidative stress index (OSI) was calculated.

RESULTS

Serum TAC levels and catalase activity were significantly lower in acute hemorrhagic stroke patients than controls (both, p < 0.001), while NO levels, TOS levels, OSI values and prolidase activity were significantly higher (all, p < 0.01). When patients with acute hemorrhagic stroke were divided according to gender, no differences were observed between females and males in respect to serum prolidase enzyme activity, NO levels, TAC levels, TOS levels and OSI values (all, p > 0.05).

CONCLUSIONS

Findings from the study suggest an association between increased oxidative stress levels, decreased antioxidant levels and increased prolidase enzyme activity in patients with acute hemorrhagic stroke compared with controls. More studies are needed to elucidate mechanistic pathways on oxidative stress in patients with acute hemorrhagic stroke.

Serum prolidase enzyme activity and oxidative status in patients with fibromyalgia

OBJECTIVE

This study was performed to investigate serum prolidase enzyme activity and oxidative stress in patients diagnosed with fibromyalgia (FM).

METHODS

The study population consisted of 40 patients with a previous diagnosis of FM and 30 healthy subjects. We measured serum prolidase enzyme activity, total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), and paraoxonase-1 (PON-1) levels.

RESULTS

On average, FM patients were diagnosed within 3.2 years of symptom onset, and patients had a mean of 14 tender points. There were no significant differences between patients and controls in age, body mass index, serum TAS, or PON-1 levels. However, patients with FM demonstrated higher serum prolidase activity, TOS, and OSI than the control group. Serum prolidase activity was positively correlated with serum TOS, OSI, and visual analog scale pain and fatigue scores. No correlation was found between serum prolidase activity and FM duration or the average number of tender points.

DISCUSSION

Our results demonstrate a previously unreported association between serum prolidase enzyme activity and FM. Increased prolidase activity may contribute to the pathogenesis of FM, and measuring serum prolidase enzyme activity may be a useful FM biomarker.

Serum prolidase activity is associated with non-diabetic metabolic syndrome

OBJECTIVE

The aim of this study was to determine the role of serum prolidase activity and the possible association with oxidative stress parameters in non-diabetic metabolic syndrome.

METHODS

30 obese patients without metabolic syndrome (MetS), 34 non-diabetic obese patients with MetS, and 23 volunteer control subjects were enrolled in the study. Fasting plasma glucose (FPG), plasma glucose following 75 g glucose administration, high-density lipoprotein- cholesterol (HDL-C), high-density lipoprotein- cholesterol (LDL-C), total cholesterol, triglyceride (TG), total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), and prolidase activities of all subjects were analyzed.

RESULTS

Prolidase levels was significantly higher in MetS group compared to both obese and control groups (p < 0.001 and p < 0.05 respectively). Prolidase was also higher in the obese group than in the control group (p < 0.05). Prolidase was negatively correlated with TAS and HDL-C (r = -0,362, p < 0.001; r = -0.320, p < 0.01, respectively) and positively correlated with BMI, weight, waist-c, SBP, DBP, TG, TC, LDL-C.

CONCLUSION

Prolidase activity may have a role in the pathogenesis of metabolic syndrome.

Serum prolidase enzyme activity and oxidative status in patients with Behçet's disease

OBJECTIVES

To assess serum prolidase enzyme activity and oxidative stress in patients with Behçet's disease (BD).

METHODS

The study population consisted of BD patients (n = 42) and healthy participants (n = 29). BD patients were classified as active (n = 18) or inactive (n = 24) according to disease activity. Serum prolidase enzyme activity, total antioxidant status (TAS), total oxidative status (TOS), oxidative stress index (OSI), and malondialdehyde (MDA) levels were measured.

RESULTS

In BD patients with active disease, serum prolidase activity was significantly higher compared with the inactive and control participants. Serum prolidase activity was also significantly higher in all BD patients in comparison with controls. Serum prolidase activity was also positively correlated with OSI, C-reactive protein, and active BD. MDA, TOS, and OSI levels were all significantly higher in the BD group when compared with the healthy control participants. Serum TAS levels were significantly lower in BD patients in comparison with healthy controls.

CONCLUSION

High prolidase activity may indicate critical biological activities relevant to pathological events in BD, and this activity may be a biological indicator of disease. Further studies are needed to verify these findings.

Serum prolidase activity, oxidant and antioxidant status in nonulcer dyspepsia and healthy volunteers

Helicobacter pylori (H. pylori) infection is associated with increased oxidative stress and serum prolidase activity (SPA) in many diseases. We aimed to observe SPA and oxidative stress in nonulcer dyspepsia (NUD) infected with and without H. pylori among eastern Indians. 106 patients with H. pylori positive NUD, 82 patients with H. pylori negative NUD, and 50 healthy individuals were selected. SPA, total antioxidant capacity (TAOC), and total oxidant status (TOS) were measured with the use of spectrophotometer and an automated measurement method. SPA, TOS, and oxidative stress index (OSI) were significantly higher in patients with H. pylori positive than H. pylori negative NUD and healthy individuals (all P < 0.0001), whereas TAOC was significantly lower (P < 0.0001). Nonsignificant, increased SPA (P value = 0.6083) and decreased TAOC (P value = 0.1186) were observed in patients with H. pylori negative NUD than healthy individuals, while increased TOS and OSI were significant (P < 0.0001). Weak, nonsignificant correlations were observed between serum prolidase activity and TAOC, TOS, and OSI in H. pylori positive cases. Thus, increased SPA along with increased oxidative stress was observed, which seem to be closely associated with H. pylori infection. SPA and oxidative stress seem to be used as biomarkers for H. pylori infection in NUD.

UVC inhibits collagen biosynthesis through up-regulation of NF-κB p65 signaling in cultured fibroblasts

The effects of UVC on collagen biosynthesis, prolidase activity, expression of α₂β₁ integrin, IGF-I receptor, FAK, MAP-kinases (ERK1 and ERK2) and the transcription factor NF-κB p65 were evaluated in human dermal fibroblasts. Confluent fibroblasts were treated with UVC light at a rates of 30 and 60 J/m(2). It was found that UVC-dependent decrease in collagen biosynthesis was not accompanied by parallel decrease in prolidase activity and expression. Since insulin-like growth factor receptor (IGF-IR) and α₂β₁ integrin signaling are the most potent regulators of collagen biosynthesis, the effect of UVC on IGF-IR and α₂β₁ integrin receptor expressions were evaluated. It was found that the exposure of the cells to UVC contributed to decrease in α₂β₁ integrin receptor and FAK expression and to an increase in IGF-IR and pERK1, pERK2 expressions. It was accompanied by an increase in the expression of NF-κB p65, the known inhibitor of collagen gene expression. The data suggest that UVC-dependent decrease of collagen biosynthesis in cultured human skin fibroblasts results from decrease in α₂β₁ integrin receptor signaling and activation of NF-κB p65, that is responsible for down-regulation of collagen gene expression.

Serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with renal cell carcinoma

OBJECTIVES

Prolidase is a member of the matrix metalloproteinase family. It plays a vital role in collagen turnover, matrix remodeling, and cell growth. Reactive oxygen species (ROS) have been implicated in the pathogenesis of various diseases, including cancers. Oxidative stress can cause tumor angiogenesis and may be carcinogenic. However, the relationship between antioxidant capacity and various cancers has been researched in several clinical trials. In our study, we aimed to identify serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with renal tumors and to evaluate their relationships with each other.

MATERIALS AND METHODS

A total of 37 male patients with renal cell cancer and with a mean age of 56.28 ± 3.1 were included in the study. The control group comprising 36 male patients (mean age 56.31 ± 2.9) was randomly selected among the volunteers. Serum samples for measurement of superoxide dismutase (SOD), glutathione peroxidase (GSHPx), glutathione-S-transferase (GST), malondialdehyde (MDA), glutathione (GSH), and prolidase levels were kept at -20°C until they were used.

RESULTS

Serum prolidase activity and MDA levels were significantly higher in renal cancer patients than in controls (all, p < 0.05), while SOD, GSHPx, and GST levels were significantly lower (p < 0.05).

CONCLUSION

Our results indicate that increased prolidase seems to be related to increased oxidative stress along with decreased antioxidant levels in renal cancer.

A C69-family cysteine dipeptidase from Lactobacillus farciminis JCM1097 possesses strong Gly-Pro hydrolytic activity

Dipeptide Gly-Pro, a hard-to-degrade and collagenous peptide, is thought to be hydrolysed by prolidases that can work on various X-Pro dipeptides. Here, we found an entirely different type of dipeptidase from Lactobacillus farciminis JCM1097 that cleaves Gly-Pro far more efficiently and with higher specificity than prolidases, and then investigated its properties by use of a recombinant enzyme. Although L. farciminis dipeptidase was expressed in the form of an inclusion body in Escherichia coli at 37 °C, it was smoothly over-expressed in a soluble form at a lower temperature. The maximal Gly-Pro hydrolytic activity was attained in E. coli at 30 °C. In contrast to prolidases that are metallopeptidases showing the modest or marginal activity toward Gly-Pro, this L. farciminis dipeptidase belongs to the cysteine peptidase family C69. Lactobacillus farciminis dipeptidase occurs in cytoplasm and utilizes the side chain of an amino-terminal cysteine residue to perform the nucleophilic attack on the target amide bond between Gly-Pro after processing eight amino acid residues at the N-terminus. Furthermore, L. farciminis dipeptidase is potent enough to synthesize Gly-Pro from Gly and Pro by a reverse reaction. These novel properties could be revealed by virtue of the success in preparing recombinant enzymes in higher yield and in a stable form.