Effect of Collagen Tripeptide on Atherosclerosis in Healthy Humans

Effects of SGLT2 Inhibitors and DPP-4 Inhibitors on Advanced Glycation End Products

Clinical trials have revealed that sodium glucose cotransporter 2 (SGLT2) inhibitors suppress the onset of heart failure and cardiovascular death in diabetic patients. On the other hand, few reports have been published concerning such effects of dipeptidyl peptidase-4 (DPP-4) inhibitors. We undertook the present study to evaluate the effects of SGLT2 inhibitors and DPP-4 inhibitors on the advanced glycation end products (AGEs), well known as a risk factor for the development of cardiovascular disorders.Type 2 diabetes mellitus were divided into two groups and treated with either SGLT2 inhibitors or DPP-4 inhibitors for 3 months. Before and after the 3-month treatment period with each drug, the AGEs and diabetes-related parameters were measured. Methylglyoxal-derived hydroimidazolone-1 (MG-H1) was measured as one of the AGEs.In the SGLT2 inhibitor group, both the blood HbA1c and MG-H1 levels decreased significantly after the 3-month treatment period. In the DPP-4 inhibitor group, only the blood HbA1c level decreased significantly, with no significant change of the blood MG-H1 level.SGLT2 inhibitor reduced both the blood levels of HbA1c and AGEs (MG-H1). Considering that the blood levels of AGEs are associated with the risk of heart failure and cardiovascular disorders, the results of the present study suggest that the effect of SGLT2 inhibitors in suppressing cardiovascular death might be mediated by the reduction in the blood levels of AGEs induced by this class of drugs. DPP-4 inhibitors showed no significant effects on the blood levels of AGEs.

Plasma type I collagen α1 chain in relation to coronary artery disease: findings from a prospective population-based cohort and an acute myocardial infarction prospective cohort in Sweden

OBJECTIVES

To investigate the association between type I collagen α1 chain (COL1α1) levels and coronary artery disease (CAD) by using absolute quantification in plasma. Also, to investigate the correlates of COL1α1 to clinical characteristics and circulating markers of collagen metabolism.

DESIGN

Life conditions, Stress and Health (LSH) study: prospective cohort study, here with a nested case-control design.Assessing Platelet Activity in Coronary Heart Disease (APACHE) study: prospective cohort study.

SETTING

LSH: primary care setting, southeast Sweden.APACHE: cardiology department, university hospital, southeast Sweden.

PARTICIPANTS

LSH: 1007 randomly recruited individuals aged 45-69 (50% women). Exclusion criteria was serious disease. After 13 years of follow-up, 86 cases with primary endpoint were identified and sex-matched/age-matched to 184 controls.

APACHE

125 patients with myocardial infarction (MI), 73 with ST-elevation MI and 52 with non-ST-elevation MI.

EXCLUSION CRITERIA

Intervention study participation, warfarin treatment and short life expectancy.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome was the association between baseline COL1α1 and first-time major event of CAD, defined as fatal/non-fatal MI or coronary revascularisation after 13 years. Secondary outcomes were the association between the collagen biomarkers PRO-C1 (N-terminal pro-peptide of type I collagen)/C1M (matrix metalloproteinase-mediated degradation of type I collagen) and CAD; temporal change of COL1α1 after acute MI up to 6 months and lastly, correlates between COL1α1 and patient characteristics along with circulating markers of collagen metabolism.

RESULTS

COL1α1 levels were associated with CAD, both unadjusted (HR=0.69, 95% CI=0.56 to 0.87) and adjusted (HR=0.55, 95% CI=0.41 to 0.75). PRO-C1 was associated with CAD, unadjusted (HR=0.62, 95% CI=0.47 to 0.82) and adjusted (HR=0.61, 95% CI=0.43 to 0.86), while C1M was not. In patients with MI, COL1α1 remained unchanged up to 6 months. COL1α1 was correlated to PRO-C1, but not to C1M.

CONCLUSIONS

Plasma COL1α1 was independently and inversely associated with CAD. Furthermore, COL1α1 appeared to reflect collagen synthesis but not degradation. Future studies are needed to confirm whether COL1α1 is a clinically useful biomarker of CAD.

Ingestion of a collagen peptide containing high concentrations of prolyl-hydroxyproline and hydroxyprolyl-glycine reduces advanced glycation end products levels in the skin and subcutaneous blood vessel walls: a randomized, double-blind, placebo-controlled study

In this randomized, double-blind, placebo-controlled study, we investigated the effects of collagen peptides (CP) containing high concentrations of prolyl-hydroxyproline and hydroxyprolyl-glycine on advanced glycation end products (AGEs) levels in the skin and subcutaneous blood vessel walls. A total of 31 individuals aged 47-87 years were randomly assigned to receive either 5 g/day of fish-derived CP or a placebo for 12 weeks. Body and blood compositions and AGEs levels were measured at the beginning and end of the study. No adverse events were observed, and both groups' blood and body compositions did not change significantly. However, the CP group had significantly lower AGEs levels and a slightly lower insulin resistance index (homeostasis model assessment ratio [HOMA-R]) than the placebo group. In addition, the percentage changes in AGEs and HOMA-R levels were positively and strongly correlated in both groups. These findings suggest that fish-derived CP may be effective in reducing AGEs levels and improving insulin resistance.

Recovery of Bioactive Compounds from Marine Organisms: Focus on the Future Perspectives for Pharmacological, Biomedical and Regenerative Medicine Applications of Marine Collagen

Marine environments cover more than 70% of the Earth's surface and are among the richest and most complex ecosystems. In terms of biodiversity, the ocean represents an important source, still not widely exploited, of bioactive products derived from species of bacteria, plants, and animals. However, global warming, in combination with multiple anthropogenic practices, represents a serious environmental problem that has led to an increase in gelatinous zooplankton, a phenomenon referred to as jellyfish bloom. In recent years, the idea of "sustainable development" has emerged as one of the essential elements of green-economy initiatives; therefore, the marine environment has been re-evaluated and considered an important biological resource. Several bioactive compounds of marine origin are being studied, and among these, marine collagen represents one of the most attractive bio-resources, given its use in various disciplines, such as clinical applications, cosmetics, the food sector, and many other industrial applications. This review aims to provide a current overview of marine collagen applications in the pharmacological and biomedical fields, regenerative medicine, and cell therapy.

Effects of Toxic AGEs (TAGE) on Human Health

The habitual and excessive consumption of sugar (i.e., sucrose and high-fructose corn syrup, HFCS) is associated with the onset and progression of lifestyle-related diseases (LSRD). Advanced glycation end-products (AGEs) have recently been the focus of research on the factors contributing to LSRD. Approaches that inhibit the effects of AGEs may be used to prevent and/or treat LSRD; however, since the structures of AGEs vary depending on the type of reducing sugars or carbonyl compounds to which they respond, difficulties are associated with verifying that AGEs are an etiological factor. Cytotoxic AGEs derived from glyceraldehyde, a triose intermediate in the metabolism of glucose and fructose, have been implicated in LSRD and are called toxic AGEs (TAGE). A dietary imbalance (the habitual and excessive intake of sucrose, HFCS, or dietary AGEs) promotes the generation/accumulation of TAGE in vivo. Elevated circulating levels of TAGE have been detected in non-diabetics and diabetics, indicating a strong relationship between the generation/accumulation of TAGE in vivo and the onset and progression of LSRD. We herein outline current findings on “TAGE as a new target” for human health.

Protective Effects of Collagen Tripeptides in Human Aortic Endothelial Cells by Restoring ROS-Induced Transcriptional Repression

Collagen tripeptide (CTP) is defined as a functional food material derived from collagenase digests of type I collagen and contains a high concentration of tripeptides with a Gly-X-Y sequence. CTP has several biological effects, including the acceleration of fracture healing, ameliorating osteoarthritis, and improving dryness and photoaging of the skin. Recently, an antiatherosclerotic effect of CTP has been reported, although its molecular mechanism is yet to be determined. In this study, we examined the effects of CTP on primary cultured human aortic endothelial cells (HAECs) under oxidative stress, because oxidative endothelial dysfunction is a trigger of atherosclerosis. DNA microarray and RT-qPCR analyses showed that CTP treatment recovered the downregulated expression of several genes, including the interleukin-3 receptor subunit alpha (IL3RA), which were suppressed by reactive oxygen species (ROS) treatment in HAECs. Furthermore, IL3RA knockdown significantly decreased the viability of HAECs compared with control cells. RT-qPCR analysis also showed that solute carrier 15 family peptide transporters, which are involved in CTP absorption into cells, were expressed in HAECs at levels more than comparable to those of a CTP-responsive human osteoblastic cell line. These results indicated that CTP exerts a protective effect for HAECs, at least in part, by regulating the recovery of ROS-induced transcriptional repression.

Intracellular Toxic AGEs (TAGE) Triggers Numerous Types of Cell Damage

The habitual intake of large amounts of sugar, which has been implicated in the onset/progression of lifestyle-related diseases (LSRD), induces the excessive production of glyceraldehyde (GA), an intermediate of sugar metabolism, in neuronal cells, hepatocytes, and cardiomyocytes. Reactions between GA and intracellular proteins produce toxic advanced glycation end-products (toxic AGEs, TAGE), the accumulation of which contributes to various diseases, such as Alzheimer’s disease, non-alcoholic steatohepatitis, and cardiovascular disease. The cellular leakage of TAGE affects the surrounding cells via the receptor for AGEs (RAGE), thereby promoting the onset/progression of LSRD. We demonstrated that the intracellular accumulation of TAGE triggered numerous cellular disorders, and also that TAGE leaked into the extracellular space, thereby increasing extracellular TAGE levels in circulating fluids. Intracellular signaling and the production of reactive oxygen species are affected by extracellular TAGE and RAGE interactions, which, in turn, facilitate the intracellular generation of TAGE, all of which may contribute to the pathological changes observed in LSRD. In this review, we discuss the relationships between intracellular TAGE levels and numerous types of cell damage. The novel concept of the “TAGE theory” is expected to open new perspectives for research into LSRD.

Toxic AGEs (TAGE) theory: a new concept for preventing the development of diseases related to lifestyle

BACKGROUND

The habitual excessive intake of sugar (i.e., sucrose and high-fructose corn syrup), which has been implicated in the onset of diabetes mellitus, induces excessive production of glyceraldehyde, a metabolite produced during glucose and fructose metabolism, in hepatocytes, neuronal cells, and cardiomyocytes.

MAIN TEXT

Toxic advanced glycation end-products (toxic AGEs, TAGE) are formed from reactions between glyceraldehyde and intracellular proteins, and their accumulation contributes to various cellular disorders. TAGE leakage from cells affects the surrounding cells and increases serum TAGE levels, promoting the onset and/or development of lifestyle-related diseases (LSRD). Therefore, serum TAGE levels have potential as a novel biomarker for predicting the onset and/or progression of LSRD, and minimizing the effects of TAGE might help to prevent the onset and/or progression of LSRD. Serum TAGE levels are closely related to LSRD associated with the excessive ingestion of sugar and/or dietary AGEs.

CONCLUSIONS

The TAGE theory is also expected to open new perspectives for research into numerous other diseases.

A randomised controlled trial of innovative specialised meat product for patients with cardiovascular and metabolic disorders

Cardiovascular diseases remain one of the leading causes of death globally. A lot of dietary patterns for CVD prevention have been proposed, but special attention is paid to functional foods. Bioactive proteins and peptides from animal sources are also considered tools for the prevention of CVDs. Here, 40 overweight or obese adult men and women aged between 61 and 66 years, with a body-mass index between 28 and 61 kg.m-2, were enrolled into a randomised controlled trial of new meat products for specialised nutrition. Participants in the control group (n = 20) consumed a standard hyponatric low-calorie diet for 28-30 days (10 days inpatient and 18-20 days outpatient), and in the experimental group – a low-calorie diet and 100g developed meat product (ratio of the porcine aorta to hearts 1:3) per day. Total cholesterol, triglyceride, cholesterol low-density lipoprotein, and cholesterol high-density lipoprotein levels were measured in the serum; from this, the atherogenic index was calculated. The positive effect of developed meat products on the serum lipid profile of patients during the trial was mild but noticeable. A significant reduction in cholesterol levels was noticed in the experimental group, by 18.2% and 14.0% after 7 – 10 and 28 – 30 days, respectively, while the cholesterol level in the control group returned to its original level after 28 – 30 days of dieting. The difference between the control and experimental groups was not significant, while data in the percentiles were. Therefore, it is more preferable to use a developed product as a component in diet therapy for hyperlipidaemic humans for over 28 – 30 days. Pronounced effects of the product could be linked to the unique proteome and peptidome of heart and aorta tissues based on organ-specific gene expression and the presence of tissue-specific substances.

A novel di-peptide Met-Glu from collagen hydrolysates inhibits platelet aggregation and thrombus formation via regulation of Gq-mediated signaling

Increasing evidence has shown that collagen peptides had various biological activities. In this study, a novel antiplatelet peptide Met-Glu (ME) was separated and identified from silver carp skin by YMC ODS-A C18 separation and ESI-MS/MS analysis. Peptide ME inhibited platelet aggregation and secretion of platelet granules induced by ADP, thrombin and collagen, and significantly attenuated ferric chloride-induced thrombus formation in rats. It did not prolong the bleeding time in mice even at the dose of 300 μmol/kg body weight that showed potent anti-thrombosis effects. Additionally, peptide ME targeted at Gq-protein to downregulate the phosphorylation of PLCβ, an important upstream effector of PI3K/Akt and Erk/MAPK signaling to inhibit intracellular calcium ion mobilization. These results suggest that peptide ME inhibited thrombosis in vivo and inhibited Gq-mediated signaling in platelets, indicating the possibility that ME could potentially be developed as a novel therapeutic agent in the prevention and treatment of thrombotic diseases. PRACTICAL APPLICATIONS: Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity worldwide. The proximal cause of CVDs is intravascular thrombosis formation, which mostly results from platelet activation, aggregation, and granules secretion. Traditional drugs in the prevention of thrombotic disease, such as aspirin and clopidogrel, are still limited for their side effects, especially bleeding complications. Collagen is a natural source for bioactive peptides and our previous study has shown that collagen peptides could inhibit platelet aggregation in vitro. Understanding the mechanism of collagen peptides on regulation of platelet activation and their in vivo anti-thrombosis activities were important for the development of novel-specific medical food in the prevention of thrombotic diseases.

Developing Regenerative Treatments for Developmental Defects, Injuries, and Diseases Using Extracellular Matrix Collagen-Targeting Peptides

Collagen is the most widespread extracellular matrix (ECM) protein in the body and is important in maintaining the functionality of organs and tissues. Studies have explored interventions using collagen-targeting tissue engineered techniques, using collagen hybridizing or collagen binding peptides, to target or treat dysregulated or injured collagen in developmental defects, injuries, and diseases. Researchers have used collagen-targeting peptides to deliver growth factors, drugs, and genetic materials, to develop bioactive surfaces, and to detect the distribution and status of collagen. All of these approaches have been used for various regenerative medicine applications, including neovascularization, wound healing, and tissue regeneration. In this review, we describe in depth the collagen-targeting approaches for regenerative therapeutics and compare the benefits of using the different molecules for various present and future applications.

Evidence for Toxic Advanced Glycation End-Products Generated in the Normal Rat Liver

Glucose/fructose in beverages/foods containing high-fructose corn syrup (HFCS) are metabolized to glyceraldehyde (GA) in the liver. We previously reported that GA-derived advanced glycation end-products (toxic AGEs, TAGE) are generated and may induce the onset/progression of non-alcoholic fatty liver disease (NAFLD). We revealed that the generation of TAGE in the liver and serum TAGE levels were higher in NAFLD patients than in healthy humans. Although we propose the intracellular generation of TAGE in the normal liver, there is currently no evidence to support this, and the levels of TAGE produced have not yet been measured. In the present study, male Wister/ST rats that drank normal water or 10% HFCS 55 (HFCS beverage) were maintained for 13 weeks, and serum TAGE levels and intracellular TAGE levels in the liver were analyzed. Rats in the HFCS group drank 127.4 mL of the HFCS beverage each day. Serum TAGE levels and intracellular TAGE levels in the liver both increased in the HFCS group. A positive correlation was observed between intracellular TAGE levels in the liver and serum TAGE levels. On the other hand, in male Wister/ST rats that drank Lactobacillus beverage for 12 weeks-a commercial drink that contains glucose, fructose, and sucrose- no increases were observed in intracellular TAGE or serum TAGE levels. Intracellular TAGE were generated in the normal rat liver, and their production was promoted by HFCS, which may increase the risk of NAFLD.

Intracellular toxic advanced glycation end-products in cardiomyocytes may cause cardiovascular disease

Cardiovascular disease (CVD) is a lifestyle-related disease (LSRD) and one of the largest public health issues. Risk factors for CVD correlate with an excessive intake of glucose and/or fructose, which has been shown to induce the production of advanced glycation end-products (AGEs). We previously identified AGEs derived from glyceraldehyde and named them toxic AGEs (TAGE) due to their cytotoxicities and relationship with LSRD. We also reported that extracellular TAGE in the vascular system may promote CVD and that serum TAGE levels are associated with risk factors for CVD. The mechanisms responsible for the onset and/or progression of CVD by extracellular TAGE or the above risk factors involve vascular disorders. In the present study, we revealed that rat primary cultured cardiomyocytes generated intracellular TAGE, which decreased beating rates and induced cell death. LC3-II/LC3-I, a factor of autophagy, also decreased. Although intracellular TAGE may be targets of degradation as cytotoxic proteins via autophagy, they may inhibit autophagy. Furthermore, the mechanisms by which intracellular TAGE decrease beating rates and induce cell death may involve the suppression of autophagy. The present results suggest that intracellular TAGE are generated in cardiomyocytes and directly damage them, resulting in CVD.

A double-blind, placebo-controlled, randomised clinical study of the effect of pork collagen peptide supplementation on atherosclerosis in healthy older individuals

We examined whether baPWV could be affected by pork collagen peptide (CP) ingestion. Seventy subjects were randomized into two groups (2.5 g/day CP and 2.5 g/day placebo). A significant reduction in baPWV was observed in the CP group compared to the placebo group. This study demonstrated that pork CP may contribute to the prevention of atherosclerosis in elderly.