Does the kinin system mediate in cardiovascular abnormalities? An overview

Des-Arg(9) bradykinin as a causal metabolite for autism spectrum disorder

BACKGROUND

Early diagnosis and therapeutic interventions can greatly enhance the developmental trajectory of children with autism spectrum disorder (ASD). However, the etiology of ASD is not completely understood. The presence of confounding factors from environment and genetics has increased the difficulty of the identification of diagnostic biomarkers for ASD.

AIM

To estimate and interpret the causal relationship between ASD and metabolite profile, taking into consideration both genetic and environmental influences.

METHODS

A two-sample Mendelian randomization (MR) analysis was conducted using summarized data from large-scale genome-wide association studies (GWAS) including a metabolite GWAS dataset covering 453 metabolites from 7824 European and an ASD GWAS dataset comprising 18381 ASD cases and 27969 healthy controls. Metabolites in plasma were set as exposures with ASD as the main outcome. The causal relationships were estimated using the inverse variant weight (IVW) algorithm. We also performed leave-one-out sensitivity tests to validate the robustness of the results. Based on the drafted metabolites, enrichment analysis was conducted to interpret the association via constructing a protein-protein interaction network with multi-scale evidence from databases including Infinome, SwissTargetPrediction, STRING, and Metascape.

RESULTS

Des-Arg(9)-bradykinin was identified as a causal metabolite that increases the risk of ASD (β = 0.262, SE = 0.064, PIVW = 4.64 × 10-5). The association was robust, with no significant heterogeneity among instrument variables (PMR Egger = 0.663, PIVW = 0.906) and no evidence of pleiotropy (P = 0.949). Neuroinflammation and the response to stimulus were suggested as potential biological processes mediating the association between Des-Arg(9) bradykinin and ASD.

CONCLUSION

Through the application of MR, this study provides practical insights into the potential causal association between plasma metabolites and ASD. These findings offer perspectives for the discovery of diagnostic or predictive biomarkers to support clinical practice in treating ASD.

Human plasma kallikrein: roles in coagulation, fibrinolysis, inflammation pathways, and beyond

Human plasma kallikrein (PKa) is obtained by activating its precursor, prekallikrein (PK), historically named the Fletcher factor. Human PKa and tissue kallikreins are serine proteases from the same family, having high- and low-molecular weight kininogens (HKs and LKs) as substrates, releasing bradykinin (Bk) and Lys-bradykinin (Lys-Bk), respectively. This review presents a brief history of human PKa with details and recent observations of its evolution among the vertebrate coagulation proteins, including the relations with Factor XI. We explored the role of Factor XII in activating the plasma kallikrein-kinin system (KKS), the mechanism of activity and control in the KKS, and the function of HK on contact activation proteins on cell membranes. The role of human PKa in cell biology regarding the contact system and KSS, particularly the endothelial cells, and neutrophils, in inflammatory processes and infectious diseases, was also approached. We examined the natural plasma protein inhibitors, including a detailed survey of human PKa inhibitors' development and their potential market.

Effects of bradykinin preconditioning in an experimental intestinal ischemia reperfusion model on rats

PURPOSE

To investigate the effects of bradykinin on reperfusion injury in an experimental intestinal ischemia reperfusion model.

METHODS

We used 32 Wistar-Albino rats. We composed 4 groups each containing 8 rats. Rats in sham group were sacrified at 100 minutes observation after laparotomy. Thirty minutes reperfusion was performed following 50 minutes ischaemia in control group after observing 20 minutes. Ischaemic preconditioning was performed in one group of the study. We performed the other study group pharmacologic preconditioning by infusional administration of 10 μg/kg/minute bradykinin intravenously. We sacrified all of the rats by taking blood samples to evaluate the lactate and lactate dehydrogenase (LDH) after resection of jejunum for detecting tissue myeloperoxidase (MPO) activity.

RESULTS

Lactate and LDH levels were significantly higher in control and study groups than the sham group (P<0.001). There is no difference between the study groups statistically. (P>0.05). The results were the same for MPO levels. Although definitive cell damage was determinated in the control group by hystopatological evaluation, the damage in the study groups observed was lower in different levels. However, there was no significant difference between the study groups statistically (P>0.05).

CONCLUSION

Either ischeamic preconditioning or pharmacologic preconditioning made by bradykinin reduced the ischemia reperfusion injury at jejunum.

Transcriptome and analysis on the complement and coagulation cascades pathway of large yellow croaker (Larimichthys crocea) to ciliate ectoparasite Cryptocaryon irritans infection

Large yellow croaker (Larimichthys crocea) is one of the most valuable marine fish in southern China. Given to the rapid development of aquaculture industry, the L. crocea was subjected to ciliate ectoparasite Cryptocaryon irritans. It therefore is indispensable and urgent to understand the mechanism of L. crocea host defense against C. irritans infection. In the present study, the extensively analysis at the transcriptome level for Cryptocaryoniasis in L. crocea was carried out. These results showed that 15,826,911, 16,462,921, and 15,625,433 paired-end clean reads were obtained from three cDNA libraries (A: 0 theronts/fish, B: 12,000 theronts/fish, and C: 24,000 theronts/fish) of the L. crocea immune-related tissues by Illumina paired-end sequencing technology. Totally, 30,509 unique transcript fragments (unigenes) were assembled, with an average length of 1715 bp. In B/A, C/A, and C/B pairwise comparison, 972, 900, and 1126 genes showed differential expression respectively. Differently expressed immune-related genes (DEIGs) were scrutinized, in B/A pairwise comparison, 48 genes showed differential expression, including 26 up-regulated genes and 22 down-regulated genes in B; in C/A pairwise comparison, there were 39 DEIGs, including 7 up-regulated genes and 32 down-regulated genes in C; in C/B pairwise comparison, 40 genes showed differential expression, including 11 up-regulated genes and 29 down-regulated genes in C. There were 16 DEIGs enriched KEGG pathways, in which the complement and coagulation cascades pathway was the top most DEIGs enriched pathway (B:A = 42; C:A = 28; C:B = 42). The coagulation and fibrinolytic system was in a highly active state after infected by C. irritans with non-lethal concentration; the alternative complement pathway may play an important role in the early stages of C. irritans infection. These results demonstrated that low-concentration infection can significantly induce the immunological response in fishes, however, when fishes were in fatal conditions, the immunity was suppressed.

A capillary electrophoresis method for genotyping the 9-bp exon 1 insertion/deletion in BDKRB2

AIM

To develop and apply a novel genotyping method for the 9-bp exon 1 insertion/deletion polymorphism in BDKRB2.

MATERIALS & METHODS

DNA from 718 patients with heart failure was extracted using standard methods and a region containing exon 1 of BDKRB2 was amplified with PCR. The PCR product was separated using the Qiagen QIAxcel® capillary electrophoresis system. The bp size of the PCR product was calculated and the genotypes determined using Qiagen BioCalculator® software.

RESULTS

Capillary electrophoresis accurately genotyped samples with >99% call rate and 700 s run time per row of a 96-well plate (i.e., less than 1 min per sample). The frequency of the deletion was 49% in the Caucasian patients (n = 441) and 45% in the African-American (n = 277).

CONCLUSION

Capillary electrophoresis is a rapid, accurate and sensitive method for genotyping the 9-bp exon 1 insertion/deletion polymorphism in BDKRB2.

Changes in kidney function following heart failure treatment: focus on renin-angiotensin system blockade

This article begins with a brief overview of the therapeutic agents used in the treatment of heart failure, with a special emphasis on pharmacologic agents that block the renin-angiotensin system (RAS). The discussion then builds upon the basic pathophysiology concepts introduced earlier in this issue to explain how therapies commonly used in heart failure affect kidney function. Against this background, a few of the common clinical dilemmas that clinicians often encounter when treating patients with agents that block the RAS system are discussed.

The Tissue Kallikrein Family of Serine Proteases: Functional Roles in Human Disease and Potential as Clinical Biomarkers

Prostate specific antigen (PSA) or human kallikrein 3 (hK3) has long been an effective biomarker for prostate cancer. Now, other members of the tissue kallikrein (KLK) gene family are fast becoming of clinical interest due to their potential as prognostic biomarkers. particularly for hormone dependent cancers. The tissue kallikreins are serine proteases that are encoded by highly conserved multi-gene family clusters in rodents and humans. The rat and mouse loci contain 10 and 25 functional genes, respectively, while the human locus at 19q 13.4 contains 15 genes. The structural organization and size of these genes are similar across species; all genes have 5 coding exons that encode a prepro-enzyme. Although the physiological activators of these zymogens have not been described, in vitro biochemical studies show that some kallikreins can auto-activate and others can activate each other, suggesting that the kallikreins may participate in an enzymatic cascade similar to that of the coagulation cascade. These genes are expressed, to varying degrees, in a wide range of tissues suggesting a functional involvement in a diverse range of physiological and pathophysiological processes. These include roles in normal skin desquamation and psoriatic lesions, tooth development, neural plasticity, and Alzheimer's disease (AD). Of particular interest is the expression of many kallikreins in prostate, ovarian, and breast cancers where they are emerging as useful prognostic indicators of disease progression.

Kallikrein activates prothrombin

Kallikrein is a multitalented enzyme in hemostasis and inflammation. Normally, kallikrein is formed in intrinsic hemostasis and activates factor XII. A total of 10 microL of 0 to 100 microg/mL human plasma kallikrein in 6% human albumin-PBS were incubated with 90 microL 111.1 microg/mL prothrombin in 6% human albumin in absence and presence of 23 mM Ca(++). After 0 to 64 minutes (37 degrees C), 100 microL of 2.5 M arginine, pH 9, were added. Fifty microliters of 0.72 mM HD-CHG-Ala-Arg-pNA in 1.36 M arginine were added and increase in absorbance at 405 nm was determined. Within 8 minutes (37 degrees C), 1 microg/mL kallikrein, ie, 2.5% of the normal plasmatic prekallikrein concentration, generates approximately 3 mIU/mL thrombin in absence and 27 mIU/mL thrombin in presence of Ca(++). Kallikrein can directly activate prothrombin; there is a shortcut in the intrinsic hemostasis system that generates catalytic amounts of thrombin without following the known intrinsic clotting pathway.

Combining neuroendocrine inhibitors in heart failure: reflections on safety and efficacy

Neuroendocrine activation in heart failure has become the major target of pharmacotherapy for this growing epidemic. Agents targeting the renin-angiotensin-aldosterone and sympathetic nervous systems have shown cardiovascular and survival benefits in clinical trials. Beta-blockers and angiotensin-converting enzyme (ACE) inhibitors remain the mainstream initial therapy. The benefits of aldosterone antagonists have been demonstrated in advanced heart failure (spironolactone) and after myocardial infarction complicated by left ventricular dysfunction and heart failure (eplerenone). Emerging clinical evidence demonstrated that angiotensin receptor blockers may be a reasonable alternative to ACE inhibitors in patients with heart failure (candesartan) and following myocardial infarction complicated by heart failure or left ventricular dysfunction (valsartan). Angiotensin receptor blockers (candesartan) also provided incremental benefits when added to ACE inhibitors in chronic heart failure. Thus, combining neuroendocrine inhibitors in heart failure appears both biologically plausible and evidence-based. However, this approach raised concerns about side effects, such as hypotension, renal insufficiency, hyperkalemia, and others. Close follow-up and implementation of evidence-based medicine (ie, using agents and doses proven beneficial in clinical trials) should therefore be undertaken when combining neuroendocrine inhibitors.

The kallikrein-kinin system: from mediator of inflammation to modulator of cardioprotection

Kinin is an important mediator of hyperalgesia, inflammatory conditions and asthma. It causes pain, inflammation, increased vascular permeability and vasodilatation. Several kinin antagonists have been developed with the aim of treating these pathologies. Kinin B2 receptor agonists and kallikrein may have clinical utility in the treatment of hypertension, left ventricular hypertrophy, ischemic heart disease, congestive heart failure and diabetes. However, there is a need to know whether there is a safe therapeutic window between potential cardio-protective and pro-inflammatory effects following administration of kinin B2 receptor agonists.

The Bradykinin Type 2 Receptor BE1 Polymorphism and Ethnicity Influence Systolic Blood Pressure and Vascular Resistance

We examined the effect of -58 C/T and BE1 +9/-9 polymorphisms in the bradykinin B2 receptor gene on forearm vascular resistance (FVR) before and during intrabrachial artery infusion of the B2 receptor-, endothelium-dependent agonist bradykinin and the endothelium-independent agonist sodium nitroprusside in 228 normotensive subjects. In 166 white Americans, systolic blood pressure (SBP) and pulse pressure were highest in the BE1 +9/+9 group (118+/-2 and 51+/-2 mm Hg, respectively; P<0.05 versus -9/-9 for either), intermediate in the +9/-9 group (114+/-1 and 49+/-1 mm Hg, P<0.05 versus -9/-9 for pulse pressure), and lowest in the -9/-9 group (110+/-2 and 44+/-2 mm Hg). In 62 black Americans, FVR was 25% higher in the BE1 +9/+9 group compared with the BE1 +9/-9 and -9/-9 groups at baseline (P=0.038) or during bradykinin (P=0.03). Increased SBP or vascular resistance may contribute to increased left ventricular mass reported previously in individuals with the BE1+9/+9 genotype.