A Cross-sectional Study of KLKB1 and PRCP Polymorphisms in Patient Samples with Cardiovascular Disease

Increased Prolylcarboxypeptidase Expression Can Serve as a Biomarker of Senescence in Culture

Prolylcarboxypeptidase (PRCP, PCP, Lysosomal Pro-X-carboxypeptidase, Angiotensinase C) controls angiotensin- and kinin-induced cell signaling. Elevation of PRCP appears to be activated in chronic inflammatory diseases [cardiovascular disease (CVD), diabetes] in proportion to severity. Vascular endothelial cell senescence and mitochondrial dysfunction have consistently been shown in models of CVD in aging. Cellular senescence, a driver of age-related dysfunction, can differentially alter the expression of lysosomal enzymes due to lysosomal membrane permeability. There is a lack of data demonstrating the effect of age-related dysfunction on the expression and function of PRCP. To explore the changes in PRCP, the PRCP-dependent prekallikrein (PK) pathway was characterized in early- and late-passage human pulmonary artery endothelial cells (HPAECs). Detailed kinetic analysis of cells treated with high molecular weight kininogen (HK), a precursor of bradykinin (BK), and PK revealed a mechanism by which senescent HPAECs activate the generation of kallikrein upon the assembly of the HK-PK complex on HPAECs in parallel with an upregulation of PRCP and endothelial nitric oxide (NO) synthase (eNOS) and NO formation. The NO production and expression of both PRCP and eNOS increased in early-passage HPAECs and decreased in late-passage HPAECs. Low activity of PRCP in late-passage HPAECs was associated with rapid decreased telomerase reverse transcriptase mRNA levels. We also found that, with an increase in the passage number of HPAECs, reduced PRCP altered the respiration rate. These results indicated that aging dysregulates PRCP protein expression, and further studies will shed light into the complexity of the PRCP-dependent signaling pathway in aging.

Circulating prekallikrein levels are correlated with lipid levels in the chinese population: a cross-sectional study

BACKGROUND

Recent evidence has revealed that circulating coagulation factor prekallikrein (PK), an important part of the kallikrein-kinin system, regulates cholesterol metabolism, but the association between serum PK and lipid levels is unclear.

METHODS

This cross-sectional study included 256 subjects (aged from 1 month to 90 years) who underwent physical examinations at the First People's Hospital of Huaihua, China. After overnight fasting, serum was collected for PK and lipid testing. Spearman correlation analysis and multivariable logistic regression analysis were used to analyze the association of PK level with lipid levels and the likelihood risk of hyperlipidemia. The possible threshold value of PK was calculated according to the receiver operating characteristic (ROC) curve.

RESULTS

The median serum PK level was 280.9 µg/mL (IQR 168.0, 377.0), and this level changed with age but not sex. The serum PK level was positively correlated with the serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) levels. A nonlinear relationship was observed between serum PK and high-density lipoprotein cholesterol (HDL-C) levels. The serum PK level was positively correlated with HDL-C when its level was lower than 240 µg/mL and negatively correlated with HDL-C when its level was higher than 240 µg/mL. The regression analysis demonstrated that an elevated serum PK level was significantly associated with the likelihood risk of hypercholesterolemia and hypertriglyceridemia. The ROC curve showed that the possible threshold values of serum PK for hypercholesterolemia and hypertriglyceridemia occurrences were 344.9 µg/mL and 305.7 µg/mL, respectively.

CONCLUSIONS

Elevated serum PK levels were significantly associated with the likelihood of hypercholesterolemia and hypertriglyceridemia, and the possible threshold values of PK levels were 344.9 µg/mL and 305.70 µg/mL, respectively, suggesting that higher PK levels may be a risk factor for cardiovascular diseases.

A modified density gradient proteomic-based method to analyze endolysosomal proteins in cardiac tissue

The importance of lysosomes in cardiac physiology and pathology is well established, and evidence for roles in calcium signaling is emerging. We describe a label-free proteomics method suitable for small cardiac tissue biopsies based on density-separated fractionation, which allows study of endolysosomal (EL) proteins. Density gradient fractions corresponding to tissue lysate; sarcoplasmic reticulum (SR), mitochondria (Mito) (1.3 g/mL); and EL with negligible contamination from SR or Mito (1.04 g/mL) were analyzed using Western blot, enzyme activity assay, and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis (adapted discontinuous Percoll and sucrose differential density gradient). Kyoto Encyclopedia of Genes and Genomes, Reactome, Panther, and Gene Ontology pathway analysis showed good coverage of RAB proteins and lysosomal cathepsins (including cardiac-specific cathepsin D) in the purified EL fraction. Significant EL proteins recovered included catalytic activity proteins. We thus present a comprehensive protocol and data set of guinea pig atrial EL organelle proteomics using techniques also applicable for non-cardiac tissue.

Haplotype-based association study between PRCP gene polymorphisms and essential hypertension in Hani minority group from a remote region of China

Objective:

Prolylcarboxypeptidase (PRCP) is both involved in the Kallikrein-Kinin system (KKS) and renin-angiotensin-aldosterone system (RAAS). This study aimed to determine the genetic impact of PRCP gene polymorphisms on essential hypertension (EH) in an isolated population from a remote region of China.

Methods:

A haplotype-based study was investigated in 346 EH patients and 346 normal subjects and all samples were Hani minority residents in Southwest China. A total of 11 tag single nucleotide polymorphisms (SNPs) in PRCP gene were tested by polymerase chain reaction-restriction fragment length polymorphism method.

Results:

Single site analysis found that PRCP gene 3′UTR SNP rs3750931 was associated with EH. The minor allele G of rs3750931 was more prevalent in the EH patients compared to control subjects after Bonferroni correction (p < 0.05). Moreover, the rs3750931 G allele carriers showed higher average blood pressure (BP) level among the subjects. The H2 (GAGCACTAACA) haplotype without rs3750931 G allele showed the protective effect for EH (OR = 0.68, 95 CI 0.54–0.85, p = 0.001).

Conclusion:

The present study indicated PRCP gene rs3750931 was associated with the risk of EH. This SNP G allele could be considered as one of risk markers for EH in Hani population.

Longitudinal Plasma Kallikrein Levels and Their Association With the Risk of Cardiovascular Disease Outcomes in Type 1 Diabetes in DCCT/EDIC

We determined the relationship between plasma kallikrein and cardiovascular disease (CVD) outcomes as well as major adverse cardiovascular events (MACE) in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort of type 1 diabetes (T1D). Plasma kallikrein levels were measured longitudinally in 693 subjects at DCCT baseline (1983-1989), midpoint (1988-1991), and end (1993) and at EDIC years 4-6 (1997-1999), 8-10 (2001-2003), and 11-13 (2004-2006). Cox proportional hazards regression models assessed the association between plasma kallikrein levels and the risk of CVD. In unadjusted models, higher plasma kallikrein levels were associated with higher risk of any CVD during DCCT/EDIC (hazard ratio [HR] = 1.16 per 20 nmol/L higher levels of plasma kallikrein; P = 0.0177) as well as over the EDIC-only period (HR = 1.22; P = 0.0024). The association between plasma kallikrein levels and the risk of any CVD remained significant during the EDIC follow-up after adjustment for age and mean HbA_1c (HR = 1.20; P = 0.0082) and in the fully adjusted model for other CVD risk factors (HR = 1.17; P = 0.0330). For MACE, higher plasma kallikrein levels were associated with higher risk in the unadjusted (HR = 1.25; P = 0.0145), minimally adjusted (HR = 1.23; P = 0.0417, and fully adjusted (HR = 1.27; P = 0.0328) models for EDIC only. These novel findings indicate that plasma kallikrein level associates with the risk of any CVD and MACE in T1D individuals.

Genetic association study of prolylcarboxypeptidase polymorphisms with susceptibility to essential hypertension in the Yi minority of China: A case-control study based on an isolated population

Objective:

Prolylcarboxypeptidase (PRCP) is a negative regulator of the pressor actions of the renin–angiotensin–aldosterone system. It is also involved in the kallikrein–kinin system. This gene has an important role in blood pressure (BP) regulation.

Methods:

A case–control study was performed for 615 Yi participants (303 cases and 312 controls) from a remote mountainous area in Yunnan Province of China. For the PRCP gene, 11 tag single-nucleotide polymorphisms were genotyped using the polymerase chain reaction-restriction fragment length polymorphism method.

Results:

The PRCP gene rs12290550 was associated with the occurrence of essential hypertension (EH) and BP traits. Logistic regression analysis indicated that the rs12290550 T allele was significantly linked to the risk of EH (odds ratio (OR) = 1.85, 95% confidence interval (CI) 1.44–2.39, p = 0.2 × 10⁻⁵). Under Bonferroni correction, the H7 TAGCACTAACA haplotype containing the risk allele rs12290550 T increased the risk of EH (OR = 4.53, 95% CI 2.29–8.93, p = 0.2×10⁻⁵).

Conclusions:

The findings of this study demonstrate the strong association of the PRCP gene with EH. rs12290550 may be a useful genetic predictor of EH in the Yi minority.

Prolonged activated partial thromboplastin time due to plasma prekallikrein deficiency: a case study and literature review on its clinical significance

: Activated partial thromboplastin time is a test assessing the intrinsic and common pathways of the coagulation cascade. We presented an asymptomatic case with isolated activated partial thromboplastin time prolongation. After excluding coagulation factor deficiency and lupus anticoagulant, the patient was diagnosed with plasma prekallikrein (PPK) deficiency. We reviewed the literature regarding effects of PPK deficiency which could have both antithrombotic and prothrombotic effects. At the moment, research supports that PPK deficiency in healthy adults rarely causes bleeding as it is not a major contributor of hemastasis; whereas in adults with multiple comorbidities or with predominant systemic inflammation, effects of PPK deficiency remain debatable. Further research is needed to clarify impacts of PPK deficiency in clinical settings.

Clinical presentation and genetic profiles of Chinese patients with velocardiofacial syndrome in a large referral centre

Diagnosis and treatment of velocardiofacial syndrome (VCFS) with variable genotypes and phenotypes are considered to be very complicated. Establishing an exact correlation between the phenotypes and genotypes of VCFS is still a challenging. In this paper, 88 Chinese VCFS patients were divided into five groups based on palatal anomalies and one or two of other four common phenotypes, and copy number variations (CNVs) were detected using multiplex ligation-dependent probe amplification (MLPA), array comparative genomic hybridization (aCGH) and quantitative polymerase chain reaction. The findings showed that palatal anomalies and characteristic malformation of face were important indicators for 22q11.2 microdeletion, and there was difference inthe phenotypic spectrum between the duplication and deletion of 22q11.2. MLPA was a highly cost-effective, sensitive and preferred method for patients with 22q11.2 deletion or duplication. Our results also firstly reported that all three patients who simultaneously exhibited palatal anomalies and cognitive disorder, without other phenotypes, have Top3b duplication, which strongly suggested that Top3b may be a pathogenic gene for these patients. Further, the findings showed that patients with palatal anomalies and congenital heart disease or immune deficiency, with or without other uncommon phenotypes, exhibited heterogeneity in CNVs, including 4q34.1-qter, 6q25.3, 4q23, Xp11.4, 13q21.1, 17q23.2, 7p21.3, 2p11.2, 11q24.3 and 16q23.3, and some possible pathogenic genes, including BCOR, PRR20A, TBX2, SMYD1, KLKB1 and TULP4 have been suggested. For these patients, aCGH, whole genomic sequencing,combined with references and phenomics database to find pathogenic gene,may be choices of priority. Taking these findings together, we offered an alternative method for diagnosis of Chinese VCFS patients based on this phenotypic strategy.

Plasma contact factors as therapeutic targets

Direct oral anticoagulants (DOACs) are small molecule inhibitors of the coagulation proteases thrombin and factor Xa that demonstrate comparable efficacy to warfarin for several common indications, while causing less serious bleeding. However, because their targets are required for the normal host-response to bleeding (hemostasis), DOACs are associated with therapy-induced bleeding that limits their use in certain patient populations and clinical situations. The plasma contact factors (factor XII, factor XI, and prekallikrein) initiate blood coagulation in the activated partial thromboplastin time assay. While serving limited roles in hemostasis, pre-clinical and epidemiologic data indicate that these proteins contribute to pathologic coagulation. It is anticipated that drugs targeting the contact factors will reduce risk of thrombosis with minimal impact on hemostasis. Here, we discuss the biochemistry of contact activation, the contributions of contact factors in thrombosis, and novel antithrombotic agents targeting contact factors that are undergoing pre-clinical and early clinical testing.

Plasma Prekallikrein: Its Role in Hereditary Angioedema and Health and Disease

Plasma prekallikrein (PK) has a critical role in acute attacks of hereditary angioedema (HAE). Unlike C1 inhibitor, its levels fall during HAE attacks with resultant cleaved high-molecular-weight kininogen. Cleavage of high-molecular-weight kininogen liberates bradykinin, the major biologic peptide that promotes the edema. How prekallikrein initially becomes activated in acute attacks of HAE is not known. PK itself is negatively associated with cardiovascular disease. High prekallikrein is associated with accelerated vascular disease in diabetes and polymorphisms of prekallikrein that reduce high-molecular-weight kininogen binding are associated with protection from cardiovascular events. Prekallikrein-deficient mice have reduced thrombosis risk and plasma kallikrein (PKa) inhibition is associated with reduced experimental gastroenterocolitis and arthritis in rodents. In sum, prekallikrein and its enzyme PKa are major targets in HAE providing much opportunity to improve the acute and chronic management of HAE. PKa inhibition also may be a target to ameliorate cardiovascular disease, thrombosis risk, and inflammation as in enterocolitis and arthritis.

Antithrombotic potential of the contact activation pathway

PURPOSE OF REVIEW

This report examines the mechanism(s) by which each protein of the contact activation system - factor XII (FXII), high-molecular-weight kininogen, and prekallikrein - influences thrombosis risk.

RECENT FINDINGS

FXII generates thrombin through contact activation via interaction with artificial surfaces as on medical instruments such as indwelling catheters, mechanical valves, stents, and ventricular assist devices. Inhibition of FXIIa-mediated contact activation prevents thrombosis under contact activation circumstances without affecting hemostasis. Current studies suggest that high-molecular-weight kininogen deficiency parallels that of FXII and inhibits contact activation. Prekallikrein inhibition contributes to thrombosis prevention by contact activation inhibition in the nylon monofilament model of transient middle cerebral artery occlusion. However, in arterial thrombosis models where reactive oxygen species are generated, prekallikrein deficiency results in downregulation of vessel wall tissue factor generation with reduced thrombin generation. Exploiting this latter prekallikrein pathway for thrombosis risk reduction provides a general, overall reduced tissue factor, antithrombotic pathway without risk for bleeding.

SUMMARY

These investigations indicate that the proteins of the contact activation and kallikrein/kinin systems influence thrombosis risk by several mechanisms and understanding of these pathway provides insight into several novel targets to prevent thrombosis without increase in bleeding risk.