Novel fatty acyl apoE mimetic peptides have increased potency to reduce plasma cholesterol in mice and macaques

Sterile inflammation induces vasculopathy and chronic lung injury in murine sickle cell disease

Murine sickle cell disease (SCD) results in damage to multiple organs, likely mediated first by vasculopathy. While the mechanisms inducing vascular damage remain to be determined, nitric oxide bioavailability and sterile inflammation are both considered to play major roles in vasculopathy. Here, we investigate the effects of high mobility group box-1 (HMGB1), a pro-inflammatory damage-associated molecular pattern (DAMP) molecule on endothelial-dependent vasodilation and lung morphometrics, a structural index of damage in sickle (SS) mice. SS mice were treated with either phosphate-buffered saline (PBS), hE-HMGB1-BP, an hE dual-domain peptide that binds and removes HMGB1 from the circulation via the liver, 1-[4-(aminocarbonyl)-2-methylphenyl]-5-[4-(1H-imidazol-1-yl)phenyl]-1H-pyrrole-2-propanoic acid (N6022) or N-acetyl-lysyltyrosylcysteine amide (KYC) for three weeks. Human umbilical vein endothelial cells (HUVEC) were treated with recombinant HMGB1 (r-HMGB1), which increases S-nitrosoglutathione reductase (GSNOR) expression by ∼80%, demonstrating a direct effect of HMGB1 to increase GSNOR. Treatment of SS mice with hE-HMGB1-BP reduced plasma HMGB1 in SS mice to control levels and reduced GSNOR expression in facialis arteries isolated from SS mice by ∼20%. These changes were associated with improved endothelial-dependent vasodilation. Treatment of SS mice with N6022 also improved vasodilation in SS mice suggesting that targeting GSNOR also improves vasodilation. SCD decreased protein nitrosothiols (SNOs) and radial alveolar counts (RAC) and increased GSNOR expression and mean linear intercepts (MLI) in lungs from SS mice. The marked changes in pulmonary morphometrics and GSNOR expression throughout the lung parenchyma in SS mice were improved by treating with either hE-HMGB1-BP or KYC. These data demonstrate that murine SCD induces vasculopathy and chronic lung disease by an HMGB1- and GSNOR-dependent mechanism and suggest that HMGB1 and GSNOR might be effective therapeutic targets for reducing vasculopathy and chronic lung disease in humans with SCD.

Alterations of HDL's to piHDL's Proteome in Patients with Chronic Inflammatory Diseases, and HDL-Targeted Therapies

Chronic inflammatory diseases, such as rheumatoid arthritis, steatohepatitis, periodontitis, chronic kidney disease, and others are associated with an increased risk of atherosclerotic cardiovascular disease, which persists even after accounting for traditional cardiac risk factors. The common factor linking these diseases to accelerated atherosclerosis is chronic systemic low-grade inflammation triggering changes in lipoprotein structure and metabolism. HDL, an independent marker of cardiovascular risk, is a lipoprotein particle with numerous important anti-atherogenic properties. Besides the essential role in reverse cholesterol transport, HDL possesses antioxidative, anti-inflammatory, antiapoptotic, and antithrombotic properties. Inflammation and inflammation-associated pathologies can cause modifications in HDL's proteome and lipidome, transforming HDL from atheroprotective into a pro-atherosclerotic lipoprotein. Therefore, a simple increase in HDL concentration in patients with inflammatory diseases has not led to the desired anti-atherogenic outcome. In this review, the functions of individual protein components of HDL, rendering them either anti-inflammatory or pro-inflammatory are described in detail. Alterations of HDL proteome (such as replacing atheroprotective proteins by pro-inflammatory proteins, or posttranslational modifications) in patients with chronic inflammatory diseases and their impact on cardiovascular health are discussed. Finally, molecular, and clinical aspects of HDL-targeted therapies, including those used in therapeutical practice, drugs in clinical trials, and experimental drugs are comprehensively summarised.

Peptides as Therapeutic Agents for Atherosclerosis

More than three decades ago, as a test for the amphipathic helix theory, an 18 amino acid residue peptide and its analogs were designed with no sequence homology to any of the exchangeable apolipoproteins. Based on the apolipoprotein A-I (the major protein component of high density lipoproteins, HDL) mimicking properties, they were termed as ApoA-I mimicking peptides. Several laboratories around the world started studying such de novo-designed peptides for their antiatherogenic properties. The present chapter describes the efforts in bringing these peptides as therapeutic agents for atherosclerosis and several lipid-mediated disorders.

Apolipoprotein E and Atherosclerosis

PURPOSE OF REVIEW

The functions, genetic variations and impact of apolipoprotein E on lipoprotein metabolism in general are placed in the context of clinical practice dealing with moderate dyslipidaemia as well as dysbetalipoproteinemia, a highly atherogenic disorder and lipoprotein glomerulopathy.

RECENT FINDINGS

Additional variants of apolipoprotein E and participation of apolipoprotein E in inflammation are of interest. The mostly favourable effects of apolipoprotein E2 as well as the atherogenic nature of apolipoproteinE4, which has an association with cognitive impairment, are confirmed. The contribution of remnant lipoproteins of triglyceride-rich lipoproteins, of which dysbetalipoproteinemia represents an extreme, is explored in atherosclerosis. Mimetic peptides may present new therapeutic approaches. Apolipoprotein E is an important determinant of the lipid profile and cardiovascular health in the population at large and can precipitate dysbetalipoproteinemia and glomerulopathy. Awareness of apolipoprotein E polymorphisms should improve medical care.

Diet, obesity, and the gut microbiome as determinants modulating metabolic outcomes in a non-human primate model

BACKGROUND

The objective of this study was to increase understanding of the complex interactions between diet, obesity, and the gut microbiome of adult female non-human primates (NHPs). Subjects consumed either a Western (n=15) or Mediterranean (n=14) diet designed to represent human dietary patterns for 31 months. Body composition was determined using CT, fecal samples were collected, and shotgun metagenomic sequencing was performed. Gut microbiome results were grouped by diet and adiposity.

RESULTS

Diet was the main contributor to gut microbiome bacterial diversity. Adiposity within each diet was associated with subtle shifts in the proportional abundance of several taxa. Mediterranean diet-fed NHPs with lower body fat had a greater proportion of Lactobacillus animalis than their higher body fat counterparts. Higher body fat Western diet-fed NHPs had more Ruminococcus champaneliensis and less Bacteroides uniformis than their low body fat counterparts. Western diet-fed NHPs had significantly higher levels of Prevotella copri than Mediterranean diet NHPs. Western diet-fed subjects were stratified by P. copri abundance (P. copriHIGH versus P. copriLOW), which was not associated with adiposity. Overall, Western diet-fed animals in the P. copriHIGH group showed greater proportional abundance of B. ovatus, B. faecis, P. stercorea, P. brevis, and Faecalibacterium prausnitzii than those in the Western P. copriLOW group. Western diet P. copriLOW subjects had a greater proportion of Eubacterium siraeum. E. siraeum negatively correlated with P. copri proportional abundance regardless of dietary consumption. In the Western diet group, Shannon diversity was significantly higher in P. copriLOW when compared to P. copriHIGH subjects. Furthermore, gut E. siraeum abundance positively correlated with HDL plasma cholesterol indicating that those in the P. copriLOW population may represent a more metabolically healthy population. Untargeted metabolomics on urine and plasma from Western diet-fed P. copriHIGH and P. copriLOW subjects suggest early kidney dysfunction in Western diet-fed P. copriHIGH subjects.

CONCLUSIONS

In summary, the data indicate diet to be the major influencer of gut bacterial diversity. However, diet and adiposity must be considered together when analyzing changes in abundance of specific bacterial taxa. Interestingly, P. copri appears to mediate metabolic dysfunction in Western diet-fed NHPs. Video abstract.

Apolipoprotein Mimetic Peptides: An Emerging Therapy against Diabetic Inflammation and Dyslipidemia

Obesity has achieved epidemic status in the United States, resulting in an increase in type 2 diabetes mellitus, dyslipidemia, and cardiovascular disease. Numerous studies have shown that inflammation plays a key role in the development of insulin resistance and diabetic complications. HDL cholesterol levels are inversely associated with coronary heart disease in humans. The beneficial effect of HDL is due, in part, to apolipoproteins A-I and E, which possess anti-inflammatory properties. The functional quality of HDL, however, may be reduced in the context of diabetes. Thus, raising levels of functional HDL is an important target for reducing inflammation and diabetic complications. Apo A-I possesses eight alpha-helical sequences, most of which form class A amphipathic helical structures. Peptides belonging to this class inhibit atherogenesis in several mouse models. Additional peptides based on structural components of apoE have been shown to mediate a rapid clearance of atherogenic lipoproteins in dyslipidemic mice. In this review, we discuss the efficacy of apolipoprotein mimetic peptides in improving lipoprotein function, reducing inflammation, and reversing insulin resistance and cardiometabolic disease processes in diabetic animals.

Apolipoprotein Mimetic Peptides: Potential New Therapies for Cardiovascular Diseases

Since the seminal breakthrough of treating diabetic patients with insulin in the 1920s, there has been great interest in developing other proteins and their peptide mimetics as therapies for a wide variety of other medical disorders. Currently, there are at least 60 different peptides that have been approved for human use and over 150 peptides that are in various stages of clinical development. Peptides mimetic of the major proteins on lipoproteins, namely apolipoproteins, have also been developed first as tools for understanding apolipoprotein structure and more recently as potential therapeutics. In this review, we discuss the biochemistry, peptide mimetics design and clinical trials for peptides based on apoA-I, apoE and apoC-II. We primarily focus on applications of peptide mimetics related to cardiovascular diseases. We conclude with a discussion on the limitations of peptides as therapeutic agents and the challenges that need to be overcome before apolipoprotein mimetic peptides can be developed into new drugs.

Bovine HDL and Dual Domain HDL-Mimetic Peptides Inhibit Tumor Development in Mice

A growing body of literature supports the role of apolipoproteins present in HDL in the treatment of pro-inflammatory diseases including cancer. We examined whether bovine HDL (bHDL) and three dual-domain peptides, namely AEM-28 and its analog AEM-28-2, and HM-10/10, affect tumor growth and development in mouse models of ovarian and colon cancer. We demonstrate that bHDL inhibits mouse colorectal cancer cell line CT26-mediated lung tumor development, and mouse ovarian cancer cell line ID8-mediated tumor burden. We also demonstrate that, although to different degrees, dual-domain peptides inhibit cell viability of mouse and human ovarian and colon cancer cell lines, but not that of normal human colonic epithelial cells or NIH3T3 mouse fibroblasts. Dual-domain peptides administered subcutaneously or in a chow diet decrease CT26 cell-mediated tumor burden, tumor growth, and tumor dissemination in BALB/c mice. Plasma levels of lysophosphatidic acid (LPA) are significantly reduced in mice that received bHDL and the dual-domain peptides, suggesting that reduction by effecting accumulation and/or synthesis of pro-inflammatory lipids may be one of the mechanisms for the inhibition of tumor development by bHDL and the dual-domain peptides. Our studies suggest that therapeutics based on apolipoproteins present in HDL may be novel agents for the treatment of epithelial adenocarcinomas of the ovary and colon.

Identification of a novel cholesterol-lowering dipeptide, phenylalanine-proline (FP), and its down-regulation of intestinal ABCA1 in hypercholesterolemic rats and Caco-2 cells

There has been no report about in vivo active cholesterol-lowering dipeptide in any protein origin, despite their potential health benefits. Cattle heart protein hydrolysate ultra-filtrate (HPHU, molecular weight < ca. 1,000 Da peptide mixture) exhibits cholesterol-lowering activity in hypercholesterolemic rats, but the active peptide in HPHU that lowers serum cholesterol levels and its molecular mechanism are unknown. In this study, we separated and purified HPHU to identify a novel cholesterol-lowering dipeptide (phenylalanine-proline, FP) and characterized the mechanism underlying its effects in vivo and in vitro. We identified FP as an active peptide from HPHU by MALDI-TOF mass spectrometry. FP significantly decreased serum total and non-HDL cholesterol and hepatic cholesterol levels in rats. FP significantly increased serum HDL cholesterol, accompanied by a significant decrease in the atherogenic index. FP also significantly increased fecal cholesterol and acidic steroid excretion. Moreover, FP significantly decreased ATP-binding cassette transporter A1 (ABCA1) expression in the rat jejunum and reduced cholesterol absorption in Caco-2 cells. We found a novel cholesterol-lowering dipeptide FP that could improve cholesterol metabolism via the down-regulation of intestinal ABCA1. The cholesterol-lowering action induced by FP was disappeared in PepT1KO mice. FP-induced cholesterol-lowering action is mediated via PepT1 in mice.

The future of apolipoprotein E mimetic peptides in the prevention of cardiovascular disease

PURPOSE OF REVIEW

This review aims to discuss the recent developments in the area of apolipoprotein E (apoE) mimetics and their therapeutic potential for treating cardiovascular disease, the leading cause of mortality worldwide.

RECENT FINDINGS

Ongoing research efforts target the development of novel therapies that would not only reduce circulating levels of atherogenic lipoproteins, but could also increase high density lipoprotein cholesterol (HDL-C) levels and/or improve HDL function. Among them, synthetic peptides that mimic the structure of natural human apoE, a component of triglyceride-rich lipoproteins and HDL, have been designed and proven to be functionally similar to apoE. In specific, apoE mimetic peptides mediate hepatic clearance of circulating atherogenic lipoproteins, dramatically reduce plasma cholesterol, and lead to attenuation of atherosclerosis development in vivo. These peptides also exhibit pleiotropic antiatherogenic properties, such as macrophage cholesterol efflux capacity, as well as anti-inflammatory and antioxidative functions.

SUMMARY

ApoE mimetics are undergoing preclinical and clinical evaluation with promising results to date that render them attractive candidates in cardiovascular disease prevention and treatment.