Serum prolidase activity in patients with hypertension and its relation with left ventricular hypertrophy

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.

Next-generation sequencing of prolidase gene identifies novel and common variants associated with low prolidase in coronary artery ectasia

BACKGROUND

Decreased collagen biosynthesis and increased collagenolysis can cause ectasia progression in the arterial walls. Prolidase is a key enzyme in collagen synthesis; a decrease in prolidase activity or level may decrease collagen biosynthesis, which may contribute to ectasia formation. Considering that, the variations in PEPD gene encoding prolidase enzyme were evaluated by analyzing next-generation sequencing (NGS) for the first time together with known risk factors in coronary artery ectasia (CAE) patients.

METHODS

Molecular analysis of the PEPD gene was performed on genomic DNA by NGS in 76 CAE patients and 76 controls. The serum levels of prolidase were measured by the sandwich-ELISA technique.

RESULTS

Serum prolidase levels were significantly lower in CAE group compared to control group, and it was significantly lower in males than females in both groups (p < 0.001). On the other hand, elevated prolidase levels were observed in CAE patients in the presence of diabetes (p < 0.001), hypertension (p < 0.05) and hyperlipidemia (p < 0.05). Logistic regression analysis demonstrated that the low prolidase level (p < 0.001), hypertension (p < 0.02) and hyperlipidemia (p < 0.012) were significantly associated with increased CAE risk. We identified four missense mutations in the PEPD gene, namely G296S, T266A, P365L and S134C (novel) that could be associated with CAE. The pathogenicity of these mutations was predicted to be "damaging" for G296S, S134C and P365L, but "benign" for T266A. We also identified a novel 5'UTR variation (Chr19:34012748 G>A) in one patient who had a low prolidase level. In addition, rs17570 and rs1061338 common variations of the PEPD gene were associated with low prolidase levels in CAE patients, while rs17569 variation was associated with high prolidase levels in both CAE and controls (p < 0.05).

CONCLUSIONS

Our findings indicate that the low serum prolidase levels observed in CAE patients is significantly associated with PEPD gene variations. It was concluded that low serum prolidase level and associated PEPD mutations may be potential biomarkers for the diagnosis of CAE.

THE RELATIONSHIP BETWEEN OXIDATIVE STRESS AND SERUM PROLIDASE ACTIVITY IN PATIENTS WITH DIABETIC NEPHROPATHY, RETINOPATHY AND NEUROPATHY

Amaç: Diyabetin mikrovasküler komplikasyonlarında oksidatif stresin belirteçlerini incelemek, prolidazın oksidatif stres göstergeleriyle ilişkisini incelemek, prolidazın prediktif değer olarak kullanılabilirliliğini araştırmaktır. Gereç ve Yöntemler: Çalışmaya 112 tip 2 Diyabetes Mellitusu (DM) olan hasta ve 44 sağlıklı kontrol birey alındı. Hastaların ayrıntılı anamnezleri alınıp fizik muayeneleri yapıldı. Açlık plazma glukozu (APG), hemoglobin A1c (HbA1C), kreatinin, spot idrarda mikrototal protein düzeyleri bakıldı. Göz dibi muayenesi ile diyabetik retinopati varlığı araştırıldı. Nöropati varlığı açısından nörolojik muayeneleri yapıldı. Ayrıca tüm hastaların sabah alınan kan örneğinde oksidatif stress için katalaz (CAT), superoksit dismutaz(SOD), glutatyon peroksidaz (GPx), malondialdehit (MDA), nitrik oksit(NO), serum prolidaz aktivitesi ölçümü yapıldı. Bulgular: Tip 2 DM olan hastaların 80’inde (%71,42) komplikasyon mevcut iken 41’inde (%28,58) komplikasyon yoktu. Açlık plazma glukozu diyabetik komplikasyonu olan grupta diğer gruplara anlamlı olarak yüksekti (p

The effects of oral steroid therapy on prolidase enzyme activity in patients with nasal polyps

Objective

To compare prolidase enzyme activity (PEA) in serum and polyp specimens of patients with nasal polyps obtained before and after the oral steroid therapy.

Materials and methods

Thirty three patients with nasal polyps (39 ± 13 years) received 1 mg/kg of oral steroids. Serum samples were collected from each patient, but nasal polyp specimens could be obtained only from 23 patients (38 ± 13 years) before and after the oral steroid therapy. PEA was measured by ELISA method.

Results

Serum PEA values were 210 (176–242) U/L and 184 (147–217) U/L before and after the oral steroid therapy, respectively (p = 0.015). Polyp tissue PEA was 1337 (738–2130) U/g and 871 (590–1663) U/g before and after the oral steroid therapy, respectively (p = 0.429).

Conclusion

In patients with nasal polyps, significantly lower serum PEA after the oral steroid therapy may be a consequence of the role of prolidase enzyme in inflammatory processes which are important for the development of nasal polyps. More comprehensive studies with larger sample sizes are needed to elucidate the role of PEA in the pathogenesis of nasal polyps.

The Serum Prolidase Enzyme Activity as a Biomarker for Evaluation of the Subclinical Vascular Damage in Children with Epilepsy

Backgroud:

Epilepsy is a chronic medical condition requiring long term or even lifelong therapy. Various researches have shown that epilepsy patients have vascular risk factors such as abnormal lipids, insulin, elevated oxidative stress, chronic inflammation, and subclinical atherosclerosis.

Objectives:

The purpose of the present study was to determine serum prolidase enzyme activity as a biomarker in children taking antiepileptic drug treatment through comparison with control cases.

Materials and Methods:

The present study group consists of 61 children (20 females, 41 males) with epilepsy and a control group was formed of 32 healthy individuals (14 females, 18 males). Aspectrophotometric method was used to measure serum prolidase enzyme activity.

Results:

The epilepsy group demonstrated statistically significantly higher prolidase enzyme activity values when compared with the control group (P = 0.003). It was measured that the serum TOS and OSI values were significantly elevated in patients with epilepsy compared to controls (P < 0.001). However, serum TAS values were significantly lower in the epilepsy group than in the control group (P = 0.032).

Conclusions:

These results supported that epileptic patients taking the antiepileptic treatment had increased serum prolidase enzyme activity, suggesting that it may show an increased risk of subclinical vascular damage related to both chronic inflammation and fibrotic process associated with degenerated collagen turnover. Therefore, serum prolidase enzyme activity could be considered a useful biomarker for evaluation of the subclinical vascular damage in children with epilepsy on some antiepileptic drugs.

Serum prolidase activity in patients with cardiac syndrome X

OBJECTIVE:

Although the underlying mechanism is not yet fully understood, Cardiac Syndrome X (CSX) is defined as microvascular dysfunction. Prolidase plays a role in collagen synthesis. Increased serum prolidase activity (SPA) has been shown to correlate with collagen turnover. Augmented collagen turn-over may be associated with vascular fibrosis and microvascular dysfunction. In this study, we assessed whether there was a correlation between CXS and prolidase activity.

METHODS:

This case-control study included 45 consecutive CSX patients (mean age 50.7±6.5 years, 27 women) and 40 healthy controls (mean age 51.2±6.5 years, 25 women). Prolidase activity was determined with the Human Xaa-Pro Dipeptidase/Prolidase enzyme-linked immunosorbent assay kit (Cusabio Biotech Co. Ltd, China).

RESULTS:

Mean prolidase activity was 898.8±639.1 mU/mL in the CSX group and 434.1±289.8 mU/mL in the control group (p<0.001). In ROC analysis, it was found that the SPA value above 350 mU/mL sympathizes with the diagnosis of CSX.

CONCLUSION:

Increased SPA in CXS patients may play an essential role in the pathophysiology of CSX, leading to augmented oxidative stress and vascular fibrosis, endothelial dysfunction, and increased microvascular resistance.

Prolidase - A protein with many faces

Prolidase is a metal-dependent peptidase specialized in the cleavage of dipeptides containing proline or hydroxyproline on their C-termini. Prolidase homologues are found in all kingdoms of life. The importance of prolidase in human health is underlined by a rare hereditary syndrome referred to as Prolidase Deficiency. A growing number of studies highlight the importance of prolidase in various other human conditions, including cancer. Some recent studies link prolidase's activity-independent regulatory role to tumorigenesis. Furthermore, the enzyme or engineered variants have some applications in biotechnology. In this short review, we aim to highlight different aspects of the protein the importance of which is increasingly recognized over the last years.

Relationship between renal tubulointerstitial fibrosis and serum prolidase enzyme activity

Objectives

The severity of interstitial fibrosis/tubular atrophy (IFTA) is the most important determinant of the irreversible progression of chronic kidney disease (CKD). Prolidase is the key enzyme in collagen turnover and is associated with an extracellular matrix increase. We aimed to evaluate the relationship between the presence and degree of IFTA and serum prolidase enzyme activity (SPEA) in patients undergoing a renal biopsy.

Methods

This cross-sectional study included 56 patients who underwent a renal biopsy (30 males; mean age 45.3 ± 16.8 years) and also 54 healthy volunteers (21 males; mean age 42.7 ± 8.2 years). IFTA scoring was performed on the basis of percentage of IFTA presence in renal biopsy tissues (1=<10%; 2=10–24%; 3=25–50%; 4=>50%). SPEA was measured by spectrophotometric method.

Results

The proteinuria and SPEA levels of the patients were significantly higher than the controls (p<0.001 and p<0.001, respectively). SPEA decreased significantly when the IFTA score increased (p<0.002). In the correlation analysis, the IFTA score was negatively correlated with SPEA (rs=−0.461, p<0.001), and positively correlated with proteinuria (rs=0.274, p=0.041).

Conclusion

These findings suggest that increased collagen turnover decreases over time concerning the progression of renal fibrosis. Monitoring of SPEA level may useful as a biomarker for early determination of CKD progression and severity.

Proline-dependent regulation of collagen metabolism

This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for collagen biosynthesis Pro is required to form collagen molecule. The question raised in this review is whether the Pro for collagen biosynthesis is synthesized "de novo", comes directly from degraded proteins or it is converted from other amino acids. Recent data provided evidence that extracellular Pro (added to culture medium) had significant, but relatively little impact on collagen biosynthesis in fibroblasts (the main collagen synthesized cells) cultured in the presence of glutamine (Gln). However, extracellular Pro drastically increased collagen biosynthesis in the cells cultured in Gln-free medium. It suggests that Pro availability determines the rate of collagen biosynthesis and demand for Pro in fibroblasts is predominantly met by conversion from Gln. The potential mechanism of this process as well as possible implication of this knowledge in pharmacotherapy of connective tissue diseases is discussed in this review.

The Relationship Between Prolidase Activity and Atrial Electromechanical Changes in Patients with Paroxysmal Atrial Fibrillation

Background:

Tissue fibrosis increases in the structure of the atrial tissue of atrial fibrillation patients. Prolidase enzyme regulates collagen synthesis. There may be an association between electrocardiography (ECG) findings and prolidase activity.

Objective:

This study investigated the association between atrial conduction time and prolidase activity, a collagen synthesis enzyme, and P-wave dispersion (PWD) in patients with Paroxysmal Atrial Fibrillation (PAF).

Methods:

Exclusion criteria included the age of <18 years, heart failure, diabetes, hypertension, hyperlipidemia, malignancy, cerebrovascular disease, chronic respiratory distress, osteoporosis, rheumatoid arthritis, renal disease, cirrhosis, and other types of arrhythmia. Patients diagnosed with PAF within 48 hours were considered to have a definite diagnosis. PWD was calculated using a 12-lead ECG, and inter- and intraatrial electromechanical delay (EMD) was assessed using tissue Doppler imaging and conventional echocardiography. Serum prolidase levels were measured in both groups.

Results:

A total of 43 patients with PAF (20 female, 23 male; mean age, 46.8 ± 5.7 years) and 42 healthy volunteers (21 female, 21 male; mean age, 43.9 ± 5.1 years) were included in the study.

:

Inter- and intraatrial EMD, PWD, minimum P-wave (Pmin), and maximum P-wave (Pmax) measurements were significantly higher (39.7 ± 2.7, 35.7 ± 2.3, p < 0.001; 13.2 ± 2.6, 8.5 ± 1.9, p < 0.001; 47.1 ± 11, 24.1 ± 7.1, p < 0.001; 69.8 ± 8.8, 66.7 ± 10.2, p < 0.130; 114.8 ± 13, 93.6 ± 8.6, p < 0.001, respectively) and serum prolidase levels were significantly lower in patients with PAF compared to healthy controls (3.96 ± 1.2, 8.5 ± 3.56, p < 0.001). In patients with PAF, correlation analysis showed a negative correlation between prolidase levels and intra- and interatrial EMD, PWD, and Pmax (r = -0.41, p < 0.05; r = -0.54, p < 0.05; r = -0.62, p < 0.05; r = -0.49, p < 0.05, respectively). Interatrial EMD showed a significant positive correlation with intraatrial EMD, Pmax, and PWD in patients with PAF (r = 0.90, p < 0.05; r = 0.574, p < 0.05; r = 0.43, p < 0.05, respectively). Additionally, the level of high-sensitivity C-reactive protein (hs-CRP) was significantly higher in patients with PAF (6.6 ± 8, 1.8 ± 1.6, p < 0.001).

Conclusion:

The decreased plasma prolidase activity in patients with PAF may explain the irregularity of the collagen metabolism of different extracellular components and may indicate the onset of atrial remodeling. Changes in PWD, interatrial EMD, and serum prolidase level may predict PAF before diagnosis.

Serum Prolidase Enzyme Activity Level: Not a Predictive Biomarker for Epilepsy

Objective

Oxidative stress (OS) and inflammation are considered responsible for the pathogenesis of epilepsy. Prolidase has an extremely important role in proline recycling for collagen synthesis. Higher than normal proline levels have been shown to increase OS. Furthermore, prolidase activity is associated with inflammation during fibrotic process. No study has yet investigated the relationship between epilepsy and prolidase enzyme activity (PEA). In this study, we aimed to contribute to the existing literature by assessing postictal PEA levels, which are correlated with inflammation and OS, to determine whether PEA levels may be used as a biomarker for epilepsy.

Materials and Methods

This study included patients with epilepsy who presented to the emergency department within first 6 h of a seizure.

Results

The epileptic group included 27 patients (16 males, 11 females) and the control group included 31 healthy individuals (11 males, 20 females). The mean age of the epilepsy (n=27) and healthy control group (n=31) was 43.1±20.2 and 51.9±21 years, respectively. Serum PEA levels were 1171.90±343.3 in the epileptic group and 1137.1±295.6 in the control group. There were no significant differences between two groups (p>0.05).

Conclusion

Our study results suggest that although PEA is an enzyme associated with OS and inflammation, it is still not an ideal biomarker for epileptic patients. This study is important because it investigated PEA in patients with idiopathic epilepsy for the first time.

Evaluation of Prolidase Activity, Oxidative Stress, and Antioxidant Enzyme Levels in Testicular and Penile Tissues after Human Chorionic Gonadotropin Treatment in Rats by Predicting Infertility and Erectile Dysfunction

OBJECTIVES

Prolidase plays a vital role in collagen turnover, matrix remodeling, and cell growth. We aimed to evaluate the association between treatment with chorionic gonadotropin and infertility and erectile dysfunction by investigating tissue prolidase activity, oxidative stress, and levels of antioxidant enzymes.

MATERIALS AND METHODS

The 16 male Wistar albino rats used in this study were randomly divided into 2 groups: rats treated with human chorionic gonadotropin (hCG) and control rats (n = 8 in each group). The rats in the hCG group were subcutaneously injected with 50 IU hCG daily for 15 days, while the rats in the control group were subcutaneously injected isotonic saline. All of the rats were sacrificed by a lethal overdose of sodium pentobarbital at the first month after hCG administration. Prolidase activity and levels of malonyl aldehyde, glutathione reductase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were estimated in the testicular and penile tissue. The testicles and penis were transversely dissected and placed in formalin.

RESULTS

Levels of prolidase and malonyl aldehyde in the testicular and penile tissues were significantly higher in the hCG group than in the control group (p < 0.001), while levels of glutathione reductase, SOD, GSH-Px, and CAT were significantly lower in the hCG group than in the control group (p < 0.001).

CONCLUSIONS

In this study, we observed that treatment with hCG increased prolidase activity and oxidative stress and decreased the antioxidant capacity of penile and testicular tissues; therefore, this may affect fertility and erectile function.

Association of serum prolidase activity in patients with isolated coronary artery ectasia

Objective:

Coronary artery ectasia (CAE) is defined as an angiographic enlargement of a portion of the coronary artery between 1.5 and 2 times the diameter of the adjacent normal coronary artery. It has been demonstrated that increased serum prolidase activity (SPA) is associated with increased collagen turnover. We aimed to analyze the relationship between CAE and serum SPA levels.

Methods:

This study used a prospective case protocol design. A total of 40 consecutive patients with isolated right CAE and normal coronary arteries (23 men, 17 women; mean age, 62.4±10.8 years) were evaluated. The control group included the same number of consecutive patients with angiographically normal coronary arteries (20 men, 20 women; mean age, 63.8±11.1 years). Clinical characteristics, laboratory results, cardiovascular risk factors, and medication use were recorded. SPA was measured using a spectrophotometer. Student’s t-test, Mann–Whitney U test, chi-square test, Pearson’s and Spearman’s correlations, logistic regression analysis, and ROC curve analysis were used for statistical analysis.

Results:

SPA was significantly higher in the CAE group compared with the control group (1635.2±492.0 U/L and 986.2±422.3 U/L, respectively; p<0.001). The relationship of SPA with CAE proved to be significant (r=0.512; p<0.001). SPA also served as an independent predictor of CAE (OR=1.003; 95% CI, 1.001–1.005; p=0.002). The SPA value of 1170 U/L was predictive of CAE, with a sensitivity of 85% and specificity of 60% (AUC=0.854; 95% CI, 0.763–0.944; p<0.001).

Conclusion:

The activity of this enzyme was significantly correlated with CAE.

Serum prolidase enzyme activity in obese subjects and its relationship with oxidative stress markers

BACKGROUND

The relationship between increased serum enzyme activity of prolidase and increased rate of collagen turnover in the arterial wall has been asserted in previous studies. Collagen reflects much of the strength to the connective tissue involved in the arterial wall. Atherosclerosis is very common vessel disease and oxidative stress plays a pivotal role in the etiopathogenesis. Our objective was to examine the serum enzyme activity of prolidase and its possible relationships with oxidative stress parameters in obese subjects.

METHODS

Our present study was conducted 27 obese subjects and 26 age-matched healthy control subjects. The serum enzyme activity of prolidase in all study population was evaluated spectrophotometrically. Oxidative stress levels in obese subjects were analyzed with total antioxidant capacity (TAC) and total oxidant status (TOS) as well as oxidative stress index (OSI).

RESULTS

Obese subjects have higher serum TOS and OSI indicators as well as prolidase activity than those in control subjects (for all; p<0.001). Moreover, obese subjects have lower levels of TAC than in those in healthy subjects (p<0.001). In the Pearson's correlation analysis, enzyme activity of prolidase was positively related with TOS (p<0.001, r=0.529) and OSI (p<0.001, r=0.519) as well as BMI (p<0.001, r=0.692) and inversely related with TAC (p<0.05, r=-0.405) in obese subjects.

CONCLUSIONS

Increased serum prolidase activity and decreased antioxidant levels are likely to be a results of increased of oxidative stress levels in obese subjects. The significantly correlation between increased oxidative stress and increased prolidase activity may play a pivotal role in etiopathogenesis of atherosclerotic cardiovascular diseases in obese subjects.

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.

Oxidative status and prolidase activities in generalized anxiety disorder

OBJECTIVE

Prolidase (Pro), an intracellular enzyme necessary for collagen turnover, matrix remodelling and cell growth has been shown to be related to Oxidative Stress (OS). To our knowledge, serum Pro activity in generalized anxiety disorder (GAD) has not been documented yet. In this study, we aimed to evaluate OS and its relation with Pro activity in patients diagnosed with GAD.

METHOD

Thirty untreated GAD patients and 30 healthy controls were included in the study. Blood samples were collected from all subjects to quantify total oxidant status (TOS), total antioxidant status (TAS) and Pro activity. Oxidative stress index (OSI), the ratio of TOS to TAS, is calculated to evaluate the balance between antioxidants and oxidants. Hamilton Anxiety Rating Scale (HARS) was used to determine the anxiety levels of all subjects.

RESULTS

GAD group demonstrated statistically significantly higher TOS, OSI and Pro levels, when compared with the control group (t=2.947, p=0.005; t=2.874, p=0.006; and t=9.396, p<0.001 respectively). HARS scores were found to be positively correlated with TOS, OSI and Pro levels (p=0.008, r=0.338; p=0.008, r=0.339; and p<0.001, r=0.751 respectively).

CONCLUSION

The degree of severity of OS is correlated with the levels of Pro. Thus, Pro might be the target enzyme, promising to be a marker for the follow-up of GAD patients. To the best of our knowledge, this study is the first to report a significant relation between Pro activity and GAD.

Gingival crevicular fluid levels of prolidase and alkaline phosphatase in periodontitis

Background/Aim: The purpose of this study was to investigate gingival crevicular fluid (GCF) alkaline phosphatase (ALP) and prolidase levels in subjects with different periodontal status. Material and Methods: Fifteen periodontitis, fifteen gingivitis and fifteen healthy subject were included. GCF samples were collected from participants. Probing depth, clinical attachment level, gingival index was recorded. ALP and prolidase levels were determined in GCF by spectrophotometrically. Results: Higher values of ALP were found in periodontitis compared with gingivitis and healthy control (p<0.001). The values of prolidase were lower in periodontitis than healthy control (p<0.05). A statistically significant positive correlation was found between clinical parameters and ALP levels (p<0.001). There is no significant correlation between clinical parameters and prolidase levels (p>0.05). Additionally, no significant correlation was detected between ALP and prolidase (r= -0.309, p>0.05). Conclusion: Our preliminary data suggest that low prolidase level in periodontitis was not associated with ALP and clinical parameters, which represent periodontal destruction and inflammation.

Is there any role of prolidase enzyme activity in the etiology of preeclampsia?

OBJECTIVE

To evaluate a relationship between preeclampsia and prolidase enzyme activity.

METHODS

A prospective cohort study of 41 pregnant women diagnosed with preeclampsia and 31 healthy pregnant women as control group was selected at Harran University Hospital Department of Obstetrics and Gynecology. The prolidase enzyme activity was analyzed in maternal and umbilical cord plasma, amniotic fluid and placental and umbilical cord tissues by Chinard method in addition to maternal serum levels of lactate dehydrogenase (LDH), serum glutamate pyruvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT).

RESULTS

A significant relationship was found between plasma prolidase activity (635 ± 83 U/L) (p  = 0.007), umbilical cord plasma prolidase activity (610 ± 90 U/L) (p = 0.013), amniotic fluid prolidase activity (558 ± 100 U/L) (p  = 0.001), umbilical cord tissue prolidase activity (4248 ± 1675 U/gr protein) (p  = 0.013) and placental tissue prolidase activity (2116 ± 601 U/gr protein) (p  = 0.001) in preeclamptic group when compared to healthy pregnant women.

CONCLUSION

There is a strong correlation between prolidase enzyme activity and preeclampsia. Prolidase enzyme activity may play a role in preeclampsia.

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.

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.

Serum prolidase enzyme activity and oxidative stress levels in patients with diabetic neuropathy

Previous studies have suggested that prolidase and nitric oxide (NO) regulate many processes, such as collagen synthesis and matrix remodeling. Oxidative stress plays an important role in the development of microvascular complications in diabetic patients. Data on serum prolidase activity in patients with diabetes mellitus or diabetic neuropathy (DN) are limited and conflicting. The aim of this study was to measure serum prolidase activity, NO, total antioxidant status (TAS), and malondialdehyde (MDA) levels in patients with DN. Forty-five patients with DN and 40 healthy controls were enrolled. Serum prolidase activity, TAS, MDA, and NO levels were determined. Serum MDA and NO levels were significantly higher in DN patients than controls (p = 0.002, p = 0.001, respectively), while prolidase activity and TAS levels were lower (p = 0.003, p = 0.001, respectively). Prolidase activity was negatively correlated with NO and MDA (r = -0.911, p < 0.001; r = -0.905, p < 0.001, respectively), while positively correlated with TAS (r = 0.981, p < 0.001) in DN patients. The current study is the first showing the decreased serum prolidase enzyme activity. Our results suggest that decreased collagen turnover may occur in DN patients, who have increased oxidative stress and increased NO levels. Decreased prolidase activity seems to be associated with increased NO levels and oxidative stress along with decreased antioxidant levels in DN. Therefore, decreased prolidase activity may play a role in pathogenesis of DN. Prospective clinical studies are necessary to confirm these findings.

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.

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.

Increased prolidase activity and oxidative stress in PCOS

AIM

Matrix metalloproteinases (MMPs) have been considered to have a role in various pathological processes, including inflammatory response, cardiovascular disease and recently also in ovarian dysfunction. Since prolidase could be accepted as a matrix metalloproteinase, on the biochemical level, we aimed to evaluate serum prolidase activity and oxidative-antioxidative status in patients with polycystic ovary syndrome (PCOS) and healthy individuals.

MATERIALS AND METHODS

Thirty-three PCOS patients and 28 healthy nonhyperandrogenic women were studied. Levels of prolidase activity, total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T) and prolactin (PRL) were calculated.

RESULTS

Levels of prolidase activities, total oxidant status, oxidative stress index, LH, PRL, and T were significantly higher in PCOS group than in the control group. Total antioxidant status levels were lower in PCOS group than healthy group, but it was not statistically significant. There was no significant difference between PCOS and control groups in term of FSH.

CONCLUSION

Women with PCOS have increased serum prolidase activity and oxidative stress. It might be hypothesized that elevated serum prolidase activity and oxidative stress may be associated with increased cardiovascular risk in PCOS and/or menstrual irregularities associated with this syndrome.

Prolidase could act as a diagnosis and treatment mediator in lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with unknown etiology and pathogenesis. With high mortality risks, most of the IPF cases emerged after a damage of alveolar epithelium, where this situation stimulates the over expression of matrix components. Inflammatory process observed as a reaction to emerged damage. Prolidase as an iminodipeptidase significantly increased during the development of fibrosis. The aim of this study is to measure prolidase activity as a marker of treatment and diagnosis in an experimental lung fibrosis animal model. Thirty male Wistar rats randomly divided into three experimental groups, with ten rats in each group. Group 1, control group; group 2, bleomycin (BLM)-induced lung fibrosis group, and group 3, BLM-induced lung fibrosis treated with palosuran (urotensin-II receptor antagonist). For histopathology, the middle lobes of right lungs were embedded in paraffin, followed by fixation in 10 % buffered formalin, and evaluation of IPF was performed using the Ashcroft scoring method. Prolidase activity was determined by a photometric method based on the measurement of proline levels produced by prolidase. The fibrosis scores and the prolidase activity were significantly enhanced by BLM stimulation. The BLM + palosuran treatment decreased prolidase activity in group 3. There was a positive correlation between prolidase activity and fibrosis scores. Palosuran seems to be effective in the treatment of lung fibrosis, and prolidase activity can be used for the diagnosis and/or for management of the treatment. However, further clinical and experimental studies with animals and/or patients are needed to verify these conclusions.

Prolidase function in proline metabolism and its medical and biotechnological applications

Prolidase is a multifunctional enzyme that possesses the unique ability to degrade imidodipeptides in which a proline or hydroxyproline residue is located at the C-terminal end. Prolidases have been isolated from archaea and bacteria, where they are thought to participate in proline recycling. In mammalian species, prolidases are found in the cytoplasm and function primarily to liberate proline in the final stage of protein catabolism, particularly during the biosynthesis and degradation of collagen. Collagen comprises nearly one-third of the total protein in the body, and it is essential in maintaining tissue structure and integrity. Prolidase deficiency (PD), a rare autosomal recessive disorder in which mutations in the PEPD gene affect prolidase functionality, tends to have serious and sometimes life-threatening clinical symptoms. Recombinant prolidases have many applications and have been investigated not only as a possible treatment for PD, but also as a part of anti-cancer strategies, a component of biodecontamination cocktails and in the dairy industry. This review will serve to discuss the many in vivo functions of procaryotic and eucaryotic prolidases, as well as the most recent advances in therapeutic and biotechnological application of prolidases.

Serum prolidase activity in patients with pulmonary tuberculosis

AIM

To investigate serum prolidase activity (SPA) in patients with pulmonary tuberculosis (PTB).

MATERIAL AND METHODS

Twenty-nine PTB patients and 32 controls were included in the study. PTB patients (cavitary and non-cavitary) and controls were compared in terms of mean SPA. Correlations were evaluated between SPA and acute phase reactants.

RESULTS

Mean SPA was significantly higher in PTB patients than in the control group. Mean SPA was significantly higher in patients with cavitary TB than non-cavitary TB. Mean SPA in patients with mild PTB was lower than patients with moderate and severe disease. We found significant correlations between SPA and CRP, ESR, albumin, platelet counts, HDL-cholesterol and LDH activity.

CONCLUSION

This study has shown that PTB patients have higher SPA than controls. The increase in SPA might be related to tissue destruction, increased immunoglobulin, complement levels and increased fibroblastic activity; all of which are involved in the natural history of PTB.

Prolidase activity dysregulation and its correlation with oxidative-antioxidative status in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a consequence of an underlying chronic inflammatory disorder of the airways that is usually progressive and causes dysregulation in the metabolism of collagen. Prolidase has an important role in the recycling of proline for collagen synthesis and cell growth.

OBJECTIVE

We measured and compared prolidase activity in healthy individuals with COPD patients to find out that whether its activity might reflect disturbances of collagen metabolism in the patients. We also investigated oxidative-antioxidative status and its relationship with prolidase activity in this disease.

METHODS

Thirty voluntary patients with COPD and 30 healthy control subjects with similar age range and sex were included into the study. Plasma prolidase activities, total antioxidant capacity (TAC) and lipid peroxidation (LPO) levels were measured in the patient and control groups.

RESULTS

Plasma prolidase activity and TAC levels were significantly lower, and LPO levels were significantly higher in the patients than those in the control subjects (P<0.05, P<0.001, and P<0.001, respectively). Significant correlations were detected between plasma prolidase activity and TAC and LPO levels in the patients group (r=0.679, P<0.001; r=-426, P<0.05, respectively).

CONCLUSIONS

The results suggest that oxidative-antioxidative balance and collagen turnover are altered by the development of COPD in human lungs, and prolidase activity may reflect disturbances of collagen metabolism in this pulmonary disease. Monitoring of plasma prolidase activity and oxidative-antioxidative balance may be useful in evaluating fibrotic processes and oxidative damage in the chronic inflammatory lung disease in human.

Serum prolidase activity in idiopathic and ischemic cardiomyopathy patients

Idiopathic and ischemic dilated cardiomyopathies (DCM) are the most common types of DCM, and both exhibit the same histopathological feature of fibrosis. Prolidase is an enzyme that serves a rate-limiting function in collagen turnover. Several studies have shown increased prolidase activity in fibrosis, though controversy persists. In this study, we measured prolidase enzyme activity in patients with idiopathic or ischemic DCM and in healthy controls, making this, to our knowledge, the first study to do so. What we found is that serumprolidase activity was significantly lower in both DCM groups relative to healthy volunteers and lower in ischemic DCM than idiopathic. These intriguing results could be attributed either to decreased collagen turnover in the heart tissues in which DCM develops, a result of diminished functional heart tissue, or to decreased physical activity levels among DCM patients stemming from their heart failure. Either way, further studies are needed to verify and clarify our results.

Dilatation of the ascending aorta is associated with low serum prolidase activity

The pathogenesis of ascending aortic aneurysm (AAA) involves many factors; elastin degradation could lead to initial dilation, and changes in the collagen structure predispose the aneurysm to rupture. Prolidase is an enzyme that catalyzes the final step of collagen breakdown by liberating free proline for collagen recycling. The enzyme activity may be a step-limiting factor in the regulation of collagen biosynthesis. Consequently, in this study we sought to determine serum prolidase activity in AAAs. Eighty consecutive patients with the diagnosis of hypertension or chest pain, referred for echocardiographic examination in the outpatient cardiology clinic, were included in the study. The subjects were grouped into three categories according to the aortic diameter; control group without aortic dilatation (<or= 3.7 cm, n = 20), medium (3.8-4.3 cm, n = 36), and large (>or= 4.4 cm, n = 24) group. We assessed the association of serum prolidase activity with the presence and severity of AAAs, clinical characteristics and laboratory parameters. Serum prolidase activity was significantly higher in the patients without aortic dilatation (1386.3 +/- 320.5 U/L) compared to medium group (1212.0 +/- 282.5 U/L) and large group (1072.2 +/- 192.3 U/L): control group vs. medium group (P = 0.023) and control group vs. large group (P < 0.001). Ascending aortic diameter was inversely correlated with serum prolidase activity and in multivariate analysis, serum prolidase activity was the only independent predictor of aortic dilatation (beta = -0.44, P = 0.006). In conclusion, the presence of AAAs is associated with low serum prolidase activity.

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.

Prognostic significance of adipocytokines and extracellular matrix activity in heart failure patients with high B-type natriuretic peptide

OBJECTIVES

To perform risk stratification by serum adipocytokines and serum markers of extracellular matrix in heart failure patients with high b-type natriuretic peptide (BNP).

METHODS

Patients with heart failure were enrolled in this study. Serum adipocytokines and serum markers of extracellular matrix were analyzed.

RESULTS

In total, 131 patients were enrolled and followed-up for 240+/-174 days. Mortality was significantly associated with adiponectin, resistin, type III amioterminal propeptide of procollagen (PIIINP), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase 1 (TIMP-1), and serum creatinine. Heart failure-related admission was significantly associated with apelin, and PIIINP. Cox regression analysis identified that mortality and heart failure-related admissions were significantly associated with MMP-2 (P=0.008) and PIIINP (P=0.011), respectively.

CONCLUSIONS

Serum markers of extracellular matrix rather than adipocytokines may warrant further risk stratification for impacting the prognosis of patients with heart failure with high BNP.

The association of serum prolidase activity with the presence and severity of coronary artery disease

OBJECTIVES

Prolidase is a cytosolic exopeptidase that cleaves iminodipeptides with carboxy-terminal proline or hydroxyproline and plays major role in collagen turnover. Collagen is the essential content in atherosclerotic plaque playing a key role in the stability/instability of and progression of coronary artery disease (CAD). Consequently, in this study we sought to determine serum prolidase activity and markers of oxidative stress such as lipid hydroperoxide and total free sulfhydryl in CAD.

DESIGN AND METHODS

We have evaluated 199 patients with CAD and 122 control cases with clinical, electrocardiographic, and laboratory investigation. We have measured serum prolidase activity and serum total free sulfhydryl levels spectrophotometrically. Serum lipid hydroperoxide levels were determined with ferrous ion oxidation-xylenol orange method. We assessed the association of serum prolidase activity with the presence and severity of CAD and clinical characteristics, and laboratory parameters.

RESULTS

Serum prolidase activity (52.5+/-5.6 vs. 46.7+/-5.1 U/l, respectively, P<0.001) and serum lipid hydroperoxide levels were significantly increased in patients with CAD compared with control cases whereas, serum total free sulfhydryl levels were significantly decreased in patients with CAD compared with control cases. Serum prolidase activity and total free sulfhydryl levels were independent predictors of the presence of CAD [(chi=75.532, ss=0.212, P=0.003) and (chi=25.969, ss=-30.486, P=0.019), respectively] and Gensini score [(beta=0.276, P<0.001) and (beta=-0.274, P<0.001), respectively]. Independent predictors of serum prolidase activity were serum high-density lipoprotein cholesterol (beta=-0.138, P=0.023) and urea levels (beta=0.146, P=0.036), and Gensini score (beta=0.317, P<0.001).

CONCLUSION

Findings of this study have shown that serum prolidase activity is significantly associated with the presence and severity of CAD, and elevated serum prolidase activity might be an independent predictor of coronary atherosclerosis.

Association of prolidase activity, oxidative parameters, and presence of atrial fibrillation in patients with mitral stenosis

BACKGROUND

Mitral stenosis (MS) is a common cause of atrial fibrillation (AF). Oxidative stress and inflammation factors were shown to be involved in atrial remodeling. The study aim was to compare the oxidative parameters and prolidase activity in severe MS patients with and without AF.

METHODS

The study population was comprised of 33 patients with MS and sinus rhythm (group I), 27 patients with MS and AF (group II), and 25 healthy controls (group III). Plasma prolidase activity, total antioxidant capacity (TAC), total oxidative status (TOS), and oxidative stress index (OSI) were determined. Additionally, we measured tissue TOS and TAC in patients with mitral valve replacement.

RESULTS

TAC and OSI were higher, but TOS and prolidase were lower in patients with MS than control (all p <0.001). These parameters were similar in group I and group II (ANOVA p >0.05). Tissue TAC was significantly lower in group II than group I (0.015 +/- 0.01 vs. 0.026 +/- 0.01 mmol Trolox equiv/L, p = 0.014), tissue TOS was similar between groups I and II (0.24 +/- 0.06 vs. 0.22 +/- 0.05 mmol Trolox equiv/L, p = 0.161). Presence of AF was correlated with systolic blood pressure, left atrial diameter, plasma TAC, tissue TAC, plasma TOS, plasma OSI, and plasma prolidase activity. Tissue TAC level (beta = -0.435, p = 0.006) and left atrial diameter (beta = 0.460, p = 0.003) were independently related with presence of AF in patients with MS.

CONCLUSIONS

This study suggested that the presence of AF in patients with severe MS may be associated with the plasma prolidase activity, tissue and plasma oxidative parameters.