Two novel angiotensin I-converting enzyme inhibitory peptides from garlic protein: In silico screening, stability, antihypertensive effects in vivo and underlying mechanisms

This study aimed to screen novel angiotensin I-converting enzyme (ACE) inhibitory peptides from garlic proteins and to explore their underlying antihypertensive mechanisms in vivo. After simulated hydrolysis and in silico screening, two novel peptides (MGR and HDCF) were obtained with the highest ACE inhibitory activity (IC50 of 4.50 μM and 26.38 μM) and acted as competitive inhibitors. They interacted with key residues in the ACE receptor mainly through hydrogen bonding and exhibited excellent stability against high temperature, extreme pH, and gastrointestinal digestion. In spontaneously hypertensive rats, MGR and HDCF effectively lowered blood pressure after single or continuous treatments. This was mainly achieved by balancing the renin-angiotensin system, improving renal and cardiac impairment, and regulating endothelial dysfunction. These findings suggested that garlic proteins were potentially suitable materials to prepare ACE inhibitory peptides and provided two promising candidates for ACE inhibition as functional food ingredients.

Morphological Assessment and Biomarkers of Low-Grade, Chronic Intestinal Inflammation in Production Animals

Simple Summary

Production animals are continuously exposed to environmental and dietary factors that might induce a state of low-grade, chronic intestinal inflammation. This condition compromises the productive performance and well-fare of these animals, requiring studies to understand what causes it and to develop control strategies. An intestinal inflammatory process is generally associated with alterations in the structure and functionality of its wall, resulting in the release of cellular components into the blood and/or feces. These components can act as biomarkers, i.e., they are measured to identify and quantify an inflammatory process without requiring invasive methods. In this review we discuss the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the identification of biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

Abstract

The complex interaction between the intestinal mucosa, the gut microbiota, and the diet balances the host physiological homeostasis and is fundamental for the maximal genetic potential of production animals. However, factors such as chemical and physical characteristics of the diet and/or environmental stressors can continuously affect this balance, potentially inducing a state of chronic low-grade inflammation in the gut, where inflammatory parameters are present and demanding energy, but not in enough intensity to provoke clinical manifestations. It’s vital to expand the understanding of inflammation dynamics and of how they compromise the function activity and microscopic morphology of the intestinal mucosa. These morphometric alterations are associated with the release of structural and functional cellular components into the feces and the blood stream creating measurable biomarkers to track this condition. Moreover, the identification of novel, immunometabolic biomarkers can provide dynamic and predictors of low-grade chronic inflammation, but also provide indicators of successful nutritional or feed additive intervention strategies. The objective of this paper is to review the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

Positive Effect of a Pea-Clam Two-Peptide Composite on Hypertension and Organ Protection in Spontaneously Hypertensive Rats

In the present study, we prepared pea peptides with high angiotensin-converting enzyme (ACE) inhibitory activity in vitro using an enzymatic hydrolysis of pea protein and compounded them with clam peptides to obtain a pea-clam double peptide. The effects of the two-peptide composite and pea peptides on hypertension and the damage-repair of corresponding organs were studied in spontaneously hypertensive rats (SHRs). We found that both pea peptides and the two-peptide composite significantly reduced the blood pressure upon a single or long-term intragastric administration, with the two-peptide composite being more effective. Mechanistically, we found that the two-peptide composite could regulate the renal renin-angiotensin system (RAS), rebalance gut microbial dysbiosis, decrease renal and myocardial fibrosis, and improve renal and cardiac function and vascular remodeling. Additionally, hippocampal lesions caused by hypertension were also eliminated after two-peptide composite administration. Our research provides a scientific basis for the use of this two-peptide composite as a safe antihypertension ingredient in functional foods.

Association of IL-6 promoter polymorphism hotspots (- 174G/C and - 572G/C) with cardiovascular disease risk factors

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death globally, despite the recent advancements in clinical research. Early diagnosis of CVD and prevention of future complications are important for the management of CVD. In the present study, we determined the genotypic linkage of interleukin-6 (IL-6) promoters with the clinical, biochemical, and inflammatory markers of CVD in the Saudi population.

MATERIALS AND METHODS

The study consisted of 89 patients (male and female) with CVD who were admitted at the King Abdulaziz university hospital, Jeddah, Saudi Arabia. The biochemical parameters were evaluated using an automated chemistry analyzer, and inflammatory markers were measured using specific enzyme-linked immunosorbent assay (ELISA) kits. For genotypic analysis, Sanger sequencing was performed. We observed a statistically significant association (p < 0.05) between GG (66.29%), GC (30.34%), and CC (3.37%) genotypes at the - 174G/C (rs1800795) hotspot and neopterin levels. However, the genotypes at the - 572G/C (rs1800796) hotspot did not show any association with age, gender, obesity, diabetes, hypertension, dyslipidemia, smoking, and coronary artery status. In addition, no significant association was observed with biochemical and inflammatory markers, namely fasting blood sugar, glycated hemoglobin A1c, creatinine, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, IL-6, and C-reactive protein. The comparison between different possible genotypic groups and CVD risk factors showed a statistically significant (p < 0.05) association between the male gender and HDL with GG, rs1800795 group vs. GC, rs1800796 group. Similarly, neopterin level was also found to be significantly (p < 0.05) associated with the genotypes GC, rs1800795, and GG, rs1800796. Additionally, the male gender (p < 0.01), age (p < 0.05), serum creatinine (p < 0.001), and neopterin (p < 0.05) were found to be significantly associated with GG, rs1800795 + GG, rs1800796, GC, rs1800795 + GC, and rs1800796 GC.

CONCLUSION

The direct association of neopterin level with IL-6 promoter polymorphism at - 174G/C (rs1800795) hotspot indicated the role of inflammation in CVD pathogenesis in the Saudi population.

The Predictive Value of Carotid Ultrasonography With Cardiovascular Risk Factors-A "SPIDER" Promoting Atherosclerosis

Insufficient recommendations do not support the clinical use of carotid ultrasonography for further risk stratification in moderate-to-high risk patients with cardiovascular disease (CVD). A literature review was performed to assess six aspects of the research progress and limitations of carotid ultrasonography and carotid atherosclerosis-related risk factors: (1) structures of the carotid intima and media; (2) plaques; (3) inflammation; (4) dynamics of carotid blood flow; (5) early detection and intervention; and (6) risk factors for CVD. Although carotid intima-media thickness and carotid plaques are well-acknowledged independent predictors of CVD risk, normative and cut-off values are difficult to define due to the heterogeneous measurements reported in previous studies. Plaque properties, including location, number, density, and size, become more important risk predictors for cardiovascular disease, but a better approach for clinical use needs to be further established. Three-dimensional ultrasound and contrast-enhanced ultrasound are promising for promoting risk stratification with more details on plaque morphology. Moreover, inflammatory diseases and biomarkers should be evaluated for a full assessment of the inflammatory burden for atherosclerosis. Carotid flow velocity is not only an indicator for stenosis but also a potential risk predictor. Carotid atherosclerosis should be detected and treated early, and additional clinical trials are needed to determine the efficacy of these measures in reducing CVD risk. Cardiovascular risk factors tend to affect carotid plaques, and early treat-to-target therapy might yield clinical benefits. Based on the aforementioned six aspects, we consider that these six important factors act like a “SPIDER” spinning the web of atherosclerosis; a timely comprehensive assessment and intervention may halt the progression to CVD. Carotid ultrasound results should be combined with other atherosclerotic factors, and a comprehensive risk assessment may help to guide cardiovascular prevention decisions.

Genotyping of interleukins-18 promoters and their correlation with coronary artery stenosis in Saudi population

BACKGROUND

Complex coronary atherosclerotic lesions often lead to coronary occlusion, clinically represented as a single-vessel disease (SVD) and multivessel disease (MVD). These occlusions could hinder the blood flow in coronary arteries that affects appropriate management of the CVD. The current study intended to genotype interleukin (IL)-18 promoter's hotspots (rs187238, rs1946518, and rs1946519) and their possible association with coronary artery stenosis.

MATERIAL AND METHODS

The IL-18 promoter genotyping was performed by the Sanger method along with the examination of biochemical parameters in 125 study subjects categorized into three groups, viz. controls, SVD and MVD.

RESULTS

The current study observed a significant association of diabetes, hypertension, and dyslipidemia between the studied group's viz. healthy controls, SVD, and MVD. Fasting blood sugar and glycosylated hemoglobin (HBA1C) were also significantly enhanced from 4.82 vs. 8.01 and 4.33 vs. 8.27, in SVD, and MVD respectively. Despite the visible differences in the pattern of genotypic and allelic expressions, the current study did not show any statistically significant correlation with IL-18 promoter polymorphism at its hotspots with controls, SVD, and MVD subjects. The only exception of the above results was the distribution of allelic frequency at the rs1946519 hotspot, where a significant change (P < 0.05) was observed.

CONCLUSION

This study is of additional value to our previous reports, revealing the pattern of genotypes and allelic frequency of IL-18 promoters in a small cohort of Saudi ethnicity. Further investigations on larger sample size are recommended to envisage the presence of functional mutations in the IL-18 gene that could establish or rule out the possible association of IL-18 polymorphism with SVD and MVD.

Identification of novel cardiovascular disease associated metabolites using untargeted metabolomics

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality around the world. Early diagnosis of CVD could provide the opportunity for sensible management and better clinical outcome along with the prevention of further progression of the disease. In the current study, we used an untargeted metabolomic approach to identify possible metabolite(s) that associate well with the CVD and could serve either as therapeutic target or disease-associated metabolite. We identified 26 rationally adjusted unique metabolites that were differentially present in the serum of CVD patients compared with healthy individuals, among them 15 were found to be statistically significant. Out of these metabolites, we identified some novel metabolites like UDP-l-rhamnose and N1-acetylspermidine that have not been reported to be linked with CVD directly. Further, we also found that some metabolites like ethanolamide, solanidine, dimethylarginine, N-acetyl-l-tyrosine, can act as a discriminator of CVD. Metabolites integrating pathway enrichment analysis showed enrichment of various important metabolic pathways like histidine metabolism, methyl histidine metabolism, carnitine synthesis, along with arginine and proline metabolism in CVD patients. Our study provides a great opportunity to understand the pathophysiological role and impact of the identified unique metabolites and can be extrapolated as specific CVD specific metabolites.

Identification and Antihypertension Study of Novel Angiotensin I-Converting Enzyme Inhibitory Peptides from the Skirt of Chlamys farreri Fermented with Bacillus natto

The aim of this study was to isolate the angiotensin I-converting enzyme (ACE) inhibitory peptides from the skirt of Chlamys farreri fermented with Bacillus natto and to explore the antihypertension effect through in vivo studies. ACE inhibitory peptides were purified from the fermentation mixture by ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography sequentially. The amino acids' sequence of the five novel ACE inhibitory peptides were identified by liquid chromatography-tandem mass spectrometry. Animal experiments demonstrated that the novel ACE inhibitory peptides significantly reduced the blood pressure in spontaneously hypertensive rats after a single or long-time treatment. Potential mechanisms were explored, and the results indicated that the novel peptides could regulate the renal renin-angiotensin system, improve vascular remodeling, inhibit myocardial fibrosis, and rebalance the gut microbial dysbiosis. Our results suggest that the fermentation products of the Chlamys farreri skirt by B. natto are potential sources of active peptides processing antihypertension activities.

Neopterin derivatives - a novel therapeutic target rather than biomarker for atherosclerosis and related diseases

This review provides an updated overview of the emerging roles of neopterin derivatives in atherosclerosis. Neopterin, a metabolite of guanosine triphosphate, is produced by interferon-γ-activated macrophages and is expressed at high levels in atheromatous plaques within the human carotid and coronary arteries as well as in the aorta. Plasma concentrations of neopterin are higher in patients with carotid, cerebral, and coronary artery diseases as well as aortic aneurysm. The concentration of neopterin is positively correlated with the severity of coronary artery disease. However, a prospective cohort study showed that neopterin contributes to protection against plaque formation in carotid arteries in patients with atherosclerosis. Moreover, using both in vitro and in vivo experiments, a recent study has shown the atheroprotective effects of neopterin. Neopterin suppresses the expression of monocyte chemotactic protein-1, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 in endothelial cells, and thereby suppresses the adhesion of monocytes to endothelial cells. It also suppresses the inflammatory phenotype of monocyte-derived macrophages. In addition, neopterin suppresses oxidized low-density lipoprotein-induced foam cell formation in macrophages and the migration and proliferation of vascular smooth muscle cells. Neopterin injection into apolipoprotein E-deficient (Apoe^-/-) mice suppresses the development of atherosclerotic lesions. A neopterin derivative tetrahydroneopterin (BH4), also known as a cofactor for nitric oxide (NO) synthases, suppresses atherosclerosis and vascular injury-induced neointimal hyperplasia in Apoe^-/- mice. BH4 administration improves endothelial dysfunction in patients with coronary artery disease. These findings suggest that neopterin production may increase to counteract the progression of atherosclerosis, as neopterin contributes to atheroprotection. Otherwise, the increased neopterin levels in atherosclerosis may reflect a compensatory mechanism associated with inducible NO synthase upregulation in macrophages to supply BH4 for high output NO production caused by decreased endothelial NO synthase in atherosclerosis. Therefore, neopterin derivatives are a novel therapeutic target for atherosclerosis and related diseases.

Role of neopterin as a biochemical marker for peripheral neuropathy in pediatric patients with type 1 diabetes: Relation to nerve conduction studies. Int Immunopharmacol. 2018;59:68-75. [PMID: 29627577 DOI: 10.1016/j.intimp.2018.03.026]

BACKGROUND

Neopterin, a marker of inflammation and cellular immune response, is elevated in conditions of T-cell or macrophages activation. Diabetic peripheral neuropathy (DPN) is associated with inflammatory/immune processes and therefore, we hypothesized that neopterin could be used as a marker of neuropathy in type 1 diabetes mellitus (T1DM).

AIM

To measure neopterin levels in children and adolescents with T1DM and assess its possible relation to DPN and nerve conduction studies (NCS).

METHODS

Sixty patients aged ≤18 years and >5 years disease duration were subjected to neurological assessment by neuropathy disability score (NDS) and NCS for median, ulnar, posterior tibial and common peroneal nerves. Mean fasting blood glucose, lipid profile, HbA1c, high sensitivity C-reactive protein (hs-CRP) and serum neopterin levels were assessed. Patients were compared with 30 age- and sex-matched healthy controls.

RESULTS

The frequency of DPN according to NDS was 40 (66.7%) patients out of 60 while NCS confirmed that only 30 of those 40 patients had this complication (i.e. 50% out of the total studied patients). Neopterin levels were significantly higher in patients with DPN than those without (median [IQR], 53.5 [35-60] nmol/L versus 17 [13-32] nmol/L) and healthy controls (5.0 [3.2-7.0] nmol/L) (p < 0.001). Significant positive correlations were found between neopterin levels and HbA1c (r = 0.560, p = 0.005), serum creatinine (r = 0.376, p = 0.003), total cholesterol (r = 0.405, p = 0.026) and hs-CRP (r = 0.425, p = 0.012) among patients with DPN. Neopterin levels were positively correlated to motor latency of tibial and common peroneal nerves as well as motor and sensory latencies of median and ulnar nerves. Logistic regression analysis revealed that neopterin was a significant independent variable related to DPN (Odds ratio, 2.976). Neopterin cutoff value 32 nmol/L could differentiate patients with and without DPN with 100% sensitivity and 96.7% specificity.

CONCLUSIONS

Neopterin could be used as an early reliable serum biomarker for DPN in pediatric patients with T1DM.

The Relationship Between Serum Zinc Levels, Cardiac Markers and the Risk of Acute Myocardial Infarction by Zinc Quartiles

BACKGROUND

Zinc is one of the most important microelements in the body and zinc homeostasis plays a critical role in maintaining cellular structure and function. Zinc dyshomeostasis can lead to many diseases, such as cardiovascular disease. Our aim was to investigate whether there is a relationship between zinc and cardiac markers, and the risk of acute myocardial infarction (AMI) by zinc quartiles.

METHODS

We enrolled a total of 529 patients and measured their serum zinc levels and cardiac markers. We performed further studies after dividing subjects into four groups according to their concentrations of zinc by quartile to clarify the relationship between zinc levels and risk of increased acute myocardial infarction prevalence rate.

RESULTS

We observed that there was a significant inverse linear relationship between zinc and Lg(creatine kinase) (p=0.011), Lg(creatine kinase-MB) (p=0.002) and Lg(cardiac troponin T) (p=0.045). In addition, the acute myocardial infarction prevalence rates were 28.8%, 24.8%, 20.5%, and 18.2% by patients with zinc quartiles, respectively. Multivariate logistic regression analysis showed that the odds ratio between the lowest and highest zinc quartile groups was 1.92 (1.019-3.604) (p<0.05).

CONCLUSIONS

The present study revealed a relationship between serum zinc levels in that zinc levels were significantly inversely correlated with serum creatine kinase (CK), creatine kinase-MB (CKMB) and cardiac troponin T (cTnT) levels. Furthermore, we found that the prevalence rate of acute myocardial infarction decreased with increasing zinc quartiles.

Assessment of genetic diversity in IL-6 and RANTES promoters and their level in Saudi coronary artery disease patients

BACKGROUND

The present study consisted of a total of 200 subjects (100 confirmed coronary artery disease (CAD) patients), both men and women, and 100 healthy control individuals.

METHODS

Serum concentration of IL-6 and RANTES were measured by enzyme-linked immunosorbent assay kit. For SNPs analysis, sanger method of DNA sequencing was followed.

RESULTS

We observed variable numbers of SNP sites at -174 G/C, -572 G/C, and -597 G/A in IL-6 and -28 C/G and -109 C/T in RANTES promoters in CAD patients compared with control individuals. However, the observed changes in the number of SNPs were found to be non-significant compared with control individuals. The IL-6 level was found to be significantly (P<.001) elevated in CAD patients compared with control. Moreover, RANTES serum level did not show any significant change in CAD patients.

CONCLUSION

Based on our result, it is quite clear that inflammation has a role in the pathogenesis of CAD but does not lead to significant changes at the genetic level in our population. As far as our knowledge goes, this is the first report that shows the genetic diversity in IL-6 and RANTES promoters and their respective levels in Saudi CAD patients.

Neopterin acts as an endogenous cognitive enhancer

Neopterin is found at increased levels in biological fluids from individuals with inflammatory disorders. The biological role of this pteridine remains undefined; however, due to its capacity to increase hemeoxygenase-1 content, it has been proposed as a protective agent during cellular stress. Therefore, we investigated the effects of neopterin on motor, emotional and memory functions. To address this question, neopterin (0.4 and/or 4pmol) was injected intracerebroventricularly before or after the training sessions of step-down inhibitory avoidance and fear conditioning tasks, respectively. Memory-related behaviors were assessed in Swiss and C57BL/6 mice, as well as in Wistar rats. Moreover, the putative effects of neopterin on motor and anxiety-related parameters were addressed in the open field and elevated plus-maze tasks. The effects of neopterin on cognitive performance were also investigated after intraperitoneal lipopolysaccharide (LPS) administration (0.33mg/kg) in interleukin-10 knockout mice (IL-10(-/-)). It was consistently observed across rodent species that neopterin facilitated aversive memory acquisition by increasing the latency to step-down in the inhibitory avoidance task. This effect was related to a reduced threshold to generate the hippocampal long-term potentiation (LTP) process, and reduced IL-6 brain levels after the LPS challenge. However, neopterin administration after acquisition did not alter the consolidation of fear memories, neither motor nor anxiety-related parameters. Altogether, neopterin facilitated cognitive processes, probably by inducing an antioxidant/anti-inflammatory state, and by facilitating LTP generation. To our knowledge, this is the first evidence showing the cognitive enhancer property of neopterin.