SAP deficiency mitigated atherosclerotic lesions in ApoE−/− mice

Serum amyloid P component: Structure, biological activity, and application in diagnosis and treatment of immune-associated diseases

Serum amyloid P component (SAP) is a member the innate immune humoral arm and participated in various processes, including the innate immune responses, tissue remodeling, and the pathogenesis of inflammatory diseases. Remarkably, SAP is a highly versatile immunomodulatory factor that can serve as a drug target for treating amyloid diseases and reduce inflammation, fibrosis degree, and respiratory disease. In this review, we focus on the biological activities of SAP and its application in different systemic immune-associated diseases. First, we reviewed the regulatory effects of SAP on innate immune cells and possible mechanisms. Second, we emphasized SAP as a diagnostic marker and therapeutic target for immune-associated diseases, including the neuropsychiatric disorders. Third, we presented several recommendations for regulating SAP in immune cell function and potential areas for future research. Some authorities consider SAP to be a pattern recognition molecule that plays multiple roles in the innate immune system and inflammation. Developing therapeutics that target SAP or its associated signaling pathways may be a promising strategy for treating immune-associated diseases.

Label-free quantitative proteomic analysis of serum exosomes in mice with thoracic aortic aneurysm

OBJECTIVE

Thoracic aortic aneurysm (TAA) is a cardiovascular disease with high morbidity and mortality. However, the causes and mechanisms of TAA are not fully understood. Serum exosomes from mice with TAA were used to explore the markers associated with this disease.

METHODS

C57BL/6 mice were divided into three groups and given ordinary drinking water, ordinary drinking water plus a saline osmotic pump, or drinking water containing β-aminopropionitrile (BAPN) (1 g/kg/d) plus an angiotensin II (Ang II) (1 μg/kg/min) osmotic pump. Haematoxylin and eosin staining of thoracic aortic tissues was performed. The basic characteristics of exosomes were analysed. Differentially expressed proteins (DEPs) were identified by LC‒MS/MS. Protein‒protein networks and enrichment analysis were used to explore possible molecular mechanisms.

RESULTS

The present study elucidated the protein expression profile of serum exosomes in mice with TAA induced by BAPN combined with Ang II. In this work, the expression of a total of 196 proteins was significantly dysregulated in serum exosomes of mice with TAA, with 122 proteins significantly upregulated and 74 proteins markedly downregulated. Notably, Haptoglobin (Hp) and Serum amyloid p-component (Sap) identified based on the PPI network were significantly upregulated and have been strongly linked to cardiovascular disease. Interestingly, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the upregulated and downregulated proteins were involved in the complement and coagulation cascade pathways.

CONCLUSIONS

This study showed that the identified DEPs have potential as biomarkers for the diagnosis of TAA and provided a more comprehensive understanding of the pathophysiological mechanisms of TAA.

Diaporisoindole B Reduces Lipid Accumulation in THP-1 Macrophage Cells via MAPKs and PPARγ-LXRα Pathways and Promotes the Reverse Cholesterol Transport by Upregulating SR-B1 and LDLR in HepG2 Cells

Diaporisoindole B (DPB), an isoprenylisoindole alkaloid isolated from the mangrove endophytic fungus Diaporthe sp. SYSU-HQ3, has been proved to have a good anti-inflammatory activity in macrophage cells. In this study, we found that DPB was able to reduce lipid accumulation in THP-1 macrophage-derived foam cells. DPB could inhibit the lipid influx-related gene CD36 and increase the expression of lipid efflux-related genes ATP binding cassette transporter A1 (ABCA1), ATP binding cassette transporter G1 (ABCG1), and scavenger receptor B1 (SR-B1). Moreover, DPB elevated low-density lipoprotein receptor (LDLR) protein expression in HepG2 cells, which can increase the transport of LDL. Meanwhile, DPB could downregulate the expression levels of proteins related to cholesterol and fatty acid synthesis. Further study showed that DPB could activate peroxisome proliferator-activated receptor gamma (PPARγ) and inhibit mitogen-activated protein kinase (MAPK) phosphorylation. Taken together, our findings demonstrated that DPB could reduce lipid accumulation in THP-1 macrophage cells by reducing the intake of lipids and promoting the efflux of lipids and also could promote the reverse cholesterol transport (RCT) mechanism by upregulating SR-B1 and LDLR in HepG2 cells.

1H-NMR-Based Metabonomics Study to Reveal the Progressive Metabolism Regulation of SAP Deficiency on ApoE-/- Mice

Atherosclerosis is the most common disease of the vascular system and the metabolic disorder is one of its important molecular mechanisms. SAP protein is found to be highly expressed in atherosclerotic blood vessels. Our previous study found that SAP deficiency can significantly inhibit the development of atherosclerosis. However, the regulatory effect of SAP deficiency on AS metabolism is unknown. Based on ¹H-NMR metabonomics, this study investigated the serum metabolic changes in ApoE^-/-;SAP^-/- mice compared with ApoE^-/- mice during the whole progression of atherosclerosis. The results showed that acetate, pyruvate, choline and VLDL + LDL were statistically regulated to the normal levels as in C57 mice by SAP deficiency in ApoE^-/-;SAP^-/- mice at 8 w (without obvious plaques). With the appearance and aggravation of atherosclerotic plaques (8 + 4 w and 8 + 8 w), the four metabolites of acetate, pyruvate, choline and VLDL + LDL were continuously regulated, which were denoted as the metabolic regulatory markers of SAP deficiency. We also found that the changes in these four metabolites had nothing to do with high-fat diet. Therefore, it was revealed that SAP deficiency regulated the metabolic disorders in ApoE^-/- prior to the appearance of obvious atherosclerotic plaques, which is one of the important mechanisms leading to the inhibition of atherosclerosis, providing a new basis for the application of SAP in atherosclerosis.

Empagliflozin inhibits macrophage inflammation through AMPK signaling pathway and plays an anti-atherosclerosis role

OBJECTIVE

In recent years, some authoritative clinical studies have found that SGLT2 inhibitor can reduce cardiovascular risk in patients with diabetes, which may imply that SGLT2 inhibitor can play a role beyond lowering blood glucose. In this study, we explored the effect of empagliflozin on vascular atherosclerosis after removing the effect of diabetes.

METHODS

The interaction between SGLT2 inhibitor and the AMPK(Adenosine 5'-monophosphate-activated protein kinase) signal pathway to attenuate atherosclerosis was studied in both spontaneously atherosclerotic mice in vivo and oxidized low-density lipoprotein(ox-LDL) induced macrophage inflammation model in vitro. In vivo experiment the aorta tree and aortic valve area were stained with oil red, and the level of inflammatory factors in the diseased tissue was evaluated by immunohistochemistry. Meanwhile, serum was collected to detect the levels of inflammatory factors. In vitro experiment, the RAW264.7 cell line was selected and ox-LDL was used to induce the release of proinflammatory factors, and different doses of empagliflozin were added. The phagocytosis of macrophages to ox-LDL density lipoprotein, and the expression of inflammatory factors at the protein and RNA levels were measured.

RESULTS

Empagliflozin reduced the area of atherosclerotic plaque and macrophage infiltration in atherosclerotic plaques, decreased the expression of inflammatory factors in local plaque tissues and serum of APOE^-/- mice fed with high-fat diet. Empagliflozin can improve the protein expression level of p-AMPK affected by ox-LDL in cell and reduce the gene expression level of inflammatory factors and protein expression level of NF-κB, thus playing an anti-atherosclerosis role.

CONCLUSIONS

Empagliflozin improves energy metabolism and reduces the expression of inflammatory factors by activating AMPK. As empagliflozin inhibits atherosclerosis progression, it may be of use in prevention of cardiovascular diseases.

Guang Chen Pi (the pericarp of Citrus reticulata Blanco's cultivars 'Chachi') inhibits macrophage-derived foam cell formation

ETHNOPHARMACOLOGICAL RELEVANCE

The dried pericarp of Citrus reticulata Blanco (CP) occupies an important position in the history of clinical applications of traditional Chinese medicine (TCM). In traditional use, CP is used to treat diseases related to the digestive, respiratory, and cardiovascular systems, as well as to regulate Qi and promote blood circulation throughout the body. In China, a special cultivar of CP named Guang Chen Pi (GCP) which is collected exclusively from Citrus reticulata Blanco's cultivars 'Chachi', is considered to be the best CP with high medicinal and dietary value. Modern pharmacology shows that CP has high effect on regulating metabolic disorders and cardiovascular systems diseases. Atherosclerosis (AS) is not only an inflammatory disease but also cardiovascular lipid metabolism disorder. Foam cells formation is the hallmark of AS. Several reports indicated that CP can mitigate the development of AS, but involved signaling pathway and its role in foam cell formation is unclear. Since the main components of GCP has protective effects in cardiovascular diseases, we evaluated its effect of inhibiting foam cell formation to support the traditional usage of GCP.

AIM OF THE STUDY

The objective of this study aims to investigate the effects of GCP on suppressing RAW264.7 foam cell formation and anti-inflammatory in vitro.

MATERIALS AND METHODS

To evaluate the anti-foam cell formation and anti-inflammatory activity of GCP, oxidized low-density lipoprotein (ox-LDL) induced RAW264.7 macrophages model was involved. Meantime, foam cell developing status was also closely monitored. RT-qPCR and Western blot were then applied to further investigate receptors in associated signaling pathways.

RESULTS

GCP shown inhibitory effect on macrophage-derived foam cell formation in Oil Red O staining analysis, which was further confirmed by flow cytometry of Dil-ox-LDL staining and TG and TC analysis. The HDL-mediated cholesterol efflux was also promoted by GCP. Mechanistic studies showed that GCP significantly down-regulate SRA1 and CD36 protein expression, while significantly increasing the expression of PPARγ, LXRα, SRB1 and ABCG1. Also, GCP reduced ox-LDL-induced inflammatory factors level, and inhibited phosphorylation of p38 MAPK, ERK1/2, JNK1/2, NF-κB p65 and IKKα/β.

CONCLUSIONS

GCP exhibited anti-atherogenic ability by interfering RAW264.7 foam cell formation, through inhibiting lipid uptake and promoting HDL-mediated cholesterol. PPARγ-LXRα-ABCG1/SRB1 pathway and its anti-inflammatory effect may involve. This proposed anti-foam cell formation activity is expected to provide new insight on comprehensive utilization of GCP.

Targeted therapy of atherosclerosis by pH-sensitive hyaluronic acid nanoparticles co-delivering all-trans retinal and rapamycin

Atherosclerosis, the leading cause of death in the elderly worldwide, is typically characterized by elevated reactive oxygen species (ROS) levels and a chronic inflammatory state at the arterial plaques. Herein, pH-sensitive nanoparticles (HR_RAP NPs) co-delivering all-trans retinal (ATR), an antioxidant linked to hyaluronic acid (HA) through a pH-sensitive hydrazone bond, and rapamycin (RAP), an anti-atherosclerotic drug loaded into the nanoparticle core, are developed for targeted combination therapy of atherosclerosis. In this way, HR_RAP NPs might simultaneously reduce ROS levels via ATR antioxidant activity and reduce inflammation via the anti-inflammatory effect of RAP. In response to mildly acidic conditions mimicking the lesional inflammation in vitro, HR_RAP NPs dissociated and both ATR and RAP were effectively released. The developed HR_RAP NPs effectively inhibited pro-inflammatory macrophage proliferation, and displayed dose- and time-dependent specific internalization by different cellular models of atherosclerosis. Also, HR_RAP NP combination therapy showed an efficient synergetic anti-atherosclerotic effect in vitro by effectively inhibiting the inflammatory response and oxidative stress in inflammatory cells. More importantly, HR NPs specifically accumulated in the atherosclerotic plaques of apolipoprotein E-deficient (ApoE^-/-) mice, by active interaction with HA receptors overexpressed by different cells of the plaque. The treatment with HR_RAP NPs remarkably inhibited the progression of atherosclerosis in ApoE^-/- mice which resulted in stable plaques with considerably smaller necrotic cores, lower matrix metalloproteinase-9, and decreased proliferation of macrophages and smooth muscle cells (SMCs). Furthermore, HR_RAP NPs attenuated RAP adverse effects and exhibited a good safety profile after long-term treatment in mice. Consequently, the developed pH-sensitive HR_RAP NP represent a promising nanoplatform for atherosclerosis combination therapy.

Brahma-Related Gene 1 Deficiency in Endothelial Cells Ameliorates Vascular Inflammatory Responses in Mice

Endothelial dysfunction plays an important role in promoting the progression of disease genesis such as atherosclerosis and abdominal aortic aneurysm (AAA). The physiological unbalance of endothelial cells is a major pathological basis. In this present study, we investigated Brahma-related gene 1 (BRG1), a chromatin remodeling protein, was in mouse models of diabetic atherosclerosis and AAA, focusing on its role in endothelial dysfunction. We report that compared with their wild-type (WT, ApoE^–/–; BRG1^fl/fl) littermates, endothelium conditional BRG1 knockout mice (CKO, ApoE^–/–; BRG1^fl/fl; CDH5-cre) exhibited an alleviated phenotype of diabetic atherosclerosis. Immunohistochemically staining and real-time PCR analysis demonstrated fewer macrophages recruitment with a reduction of vascular inflammatory in CKO mice compared with WT mice. Further research in the Ang-II induced AAA model revealed that BRG1 deficiency had the protective effects on endothelium conditional BRG1 deletion, evidenced by the downregulation of pro-inflammatory mediators [interleukin (IL)-1β and IL-6, not tumor necrosis factor-α (TNF-α)] in the vessels of CKO mice compared with WT mice. In Ea.hy926 cell lines, anti-BRG1 small interfering RNA and PFI-3 treatment obviously alleviated tumor necrosis factor-α-induced IL-6 and CCL2 expression, and further research demonstrated that the BRG1 inhibition in endothelial cells not only decreased c-Fos expression but also blocked the c-Fos translocation into nuclei. In conclusion, our results suggest that endothelial BRG1 deficiency may protect the mice from diabetic atherosclerosis and AAA via inhibiting inflammatory response in vessels.

Vitamin D Correction Down-Regulates Serum Amyloid P Component Levels in Vitamin D Deficient Arab Adults: A Single-Arm Trial

Vitamin D (VD) has been observed to have anti-inflammatory properties. However, the effects of VD supplementation on the serum amyloid P component (SAP) has not been established. This study aimed to investigate the effect of VD supplementation on serum SAP levels in Arab adults. A total of 155 VD-deficient adult Saudis (56 males and 99 females) were recruited in this non-randomized, 6-month, single-arm trial. The intervention was as follows; cholecalciferol 50,000 international units (IU) every week for the first 2 months, followed by 50,000 twice a month for the next two months, and for the last two months, 1000 IU daily. Serum 25(OH)D, SAP, C-reactive protein (CRP), lipid profile, and glucose were assessed at baseline and post-intervention. At post-intervention, VD levels were significantly increased, while SAP levels significantly decreased in all study participants. Remarkably, this reduction in SAP was more significant in males than females after stratification. SAP was inversely correlated with VD overall (r = −0.17, p < 0.05), and only in males (r = −0.27, p < 0.05) after stratification according to sex after 6 months of VD supplementation. Such a relationship was not observed at baseline. VD supplementation can favorably modulate serum SAP concentrations in Arab adults, particularly in males.

Endothelial Cells: From Dysfunction Mechanism to Pharmacological Effect in Cardiovascular Disease

Endothelial cells (ECs) are the innermost layer of blood vessels that play important roles in homeostasis and vascular function. However, recent evidence suggests that the onset of inflammation and the production of reactive oxygen species impair the function of ECs and are a main factor in the development of cardiovascular disease (CVD). In this study, we investigated the effects of inflammatory markers, oxidative stress, and treatment on ECs in CVD patients. This review article is based on the material obtained from PubMed up to 2018. The key search terms used were "Cardiovascular Disease," "Endothelial Cell Dysfunction," "Inflammation," "Treatment," and "Oxidative Stress." The generation of reactive oxygen species (ROS) as well as reduced nitric oxide (NO) production by ECs impairs the function of blood vessels. Therefore, treatment of CVD patients leads to the expression of transcription factors activating anti-oxidant mechanisms and NO production. In contrast, NO production by inflammatory agents can cause ECs repair due to differentiation of endothelial progenitor cells (EPCs). Therefore, identifying the molecular pathways leading to the differentiation of EPCs through mediation of factors induced by inflammatory factors can be effective in regenerative medicine for ECs repair.

Protective Effects of Chinese Traditional Medicine Longhu Rendan against Atherosclerosis via Negative Regulation of LOX-1

Longhu Rendan (LHRD), a Chinese traditional compound medicine, has a remarkable treatment effect on motion sickness for about half a century. However, the role of LHRD in atherosclerosis treatment is still unclear. In this study, LHRD treatment significantly diminished total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels in apolipoprotein E gene-knockout (ApoE^−/−) mice fed with high fat and high cholesterol diet (western diet). Besides, LHRD treatment significantly reduced atherosclerotic lesion and plaques formation in both aortic roots and aortic trees. Furthermore, immunofluorescence staining in aortic roots demonstrated that LHRD treatment inhibited lectin-like oxidized low-density-lipoprotein receptor-1 (LOX-1) expression in atherosclerotic plaques. These results indicated that LHRD ameliorated atherosclerosis via reducing serum levels of TC, TG, and LDL-C as well as LOX-1 expression, subsequently attenuating atherosclerotic lesion and lipid deposition. In conclusion, LHRD could significantly attenuate experimental atherosclerosis and might be a novel potential drug for the prevention and treatment of atherosclerosis.

Phytosterols and Omega 3 Supplementation Exert Novel Regulatory Effects on Metabolic and Inflammatory Pathways: A Proteomic Study

Cardiovascular disease (CVD) remains one of the major causes of death and disability worldwide. In addition to drug treatment, nutritional interventions or supplementations are becoming a health strategy for CVD prevention. Phytosterols (PhyS) are natural components that have been shown to reduce cholesterol levels; while poly-unsaturated fatty acids (PUFA), mainly omega-3 (ω3) fatty acids, have shown to reduce triglyceride levels. Here we aimed to investigate whether the proteins in the main lipoproteins (low density lipoproteins (LDL) and high density lipoproteins (HDL)) as well as proteins in the lipid free plasma fraction (LPDP) were regulated by the intake of PhyS-milk or ω3-milk, in overweight healthy volunteers by a proteomic based systems biology approach. The study was a longitudinal crossover trial, including thirty-two healthy volunteers with body mass index (BMI) 25–35 kg/m² (Clinical Trial: ISRCTN78753338). Basal samples before any intervention and after 4 weeks of intake of PhyS or ω3-milk were analyzed. Proteomic profiling by two dimensional electrophoresis (2-DE) followed by mass spectrometry-(MALDI/TOF), ELISA, Western blot, conventional biochemical analysis, and in-silico bioinformatics were performed. The intake of PhyS-milk did not induce changes in the lipid associated plasma protein fraction, whereas ω3-milk significantly increased apolipoprotein (Apo)- E LDL content (p = 0.043) and induced a coordinated increase in several HDL-associated proteins, Apo A–I, lecitin cholesterol acyltransferase (LCAT), paraoxonase-1 (PON-1), Apo D, and Apo L1 (p < 0.05 for all). Interestingly, PhyS-milk intake induced a reduction in inflammatory molecules not seen after ω3-milk intake. Serum amyloid P component (SAP) was reduced in the LPDP protein fraction (p = 0.001) of subjects taking PhyS-milk and C-C motif chemokine 2 (CCL2)expression detected by reverse transcription polymerase chain reaction (RT-PCR) analysis in white blood cells was significantly reduced (p = 0.013). No changes were observed in the lipid-free plasma proteome with ω3-milk. Our study provides novel results and highlights that the PhyS-milk induces attenuation of the pro-inflammatory pathways, whereas ω3-milk induces improvement in lipid metabolic pathways.