Quercetin Attenuates Atherosclerosis via Modulating Apelin Signaling Pathway Based on Plasma Metabolomics

OBJECTIVE

To interpret the pharmacology of quercetin in treatment of atherosclerosis (AS).

METHODS

Fourteen apolipoprotein E-deficient (ApoE-/-) mice were divided into 2 groups by a random number table: an AS model (ApoE-/-) group and a quercetin treatment group (7 in each). Seven age-matched C57 mice were used as controls (n=7). Quercetin [20 mg/(kg·d)] was administered to the quercetin group intragastrically for 8 weeks for pharmacodynamic evaluation. Besides morphological observation, the distribution of CD11b, F4/80, sirtuin 1 (Sirt1) and P21 was assayed by immunohistochemistry and immunofluorescence to evaluate macrophage infiltration and tissue senescence. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MSC/MS) was performed to study the pharmacology of quercetin against AS. Then, simultaneous administration of an apelin receptor antagonist (ML221) with quercetin was conducted to verify the possible targets of quercetin. Key proteins in apelin signaling pathway, such as angiotensin domain type 1 receptor-associated proteins (APJ), AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), tissue plasminogen activator (TPA), uncoupling protein 1 (UCP1) and angiotensin II receptor 1 (AT1R), were assayed by Western blot.

RESULTS

Quercetin administration decreased lipid deposition in arterial lumen and improved the morphology of ApoE-/- aortas in vivo. Quercetin decreased the densities of CD11b, F4/80 and P21 in the aorta and increased the level of serum apelin and the densities of APJ and Sirt1 in the aorta in ApoE-/- mice (all P<0.05). Plasma metabolite profiling identified 118 differential metabolites and showed that quercetin affected mainly glycerophospholipids and fatty acyls. Bioinformatics analysis suggested that the apelin signaling pathway was one of the main pathways. Quercetin treatment increased the protein expressions of APJ, AMPK, PGC-1α, TPA and UCP1, while decreased the AT1R level (all P<0.05). After the apelin pathway was blocked by ML221, the effect of quercetin was abated significantly, confirming that quercetin attenuated AS by modulating the apelin signaling pathway (all P<0.05).

CONCLUSION

Quercetin alleviated AS lesions by up-regulation the apelin signaling pathway.

An Insight Into Intestinal Microbiota of Spontaneously Hypertensive Rats After Valsartan Administration

It has been proven a close relationship between intestinal microbiota and hypertension. Valsartan is a widely used ARB antihypertensive drug; so far, the effect of valsartan on intestinal microbiota remains largely unexplored. Herein, we evaluated the composition, structure and metabolites of intestinal microbiota of spontaneously hypertensive rats (SHRs) after valsartan administration. In the present study, valsartan administration decreased intestinal microbiota diversity, altered gut microbiota composition, leading to 192 unique OTUs deficiency (vs WKY rats) and 10 unique OTUs deficiency (vs SHRs) and did not prove impaired intestinal mucosal barriers. Valsartan decreased the production of isobutyric acid and isovaleric acid in SCFAs. Our findings revealed valsartan administration induced far-reaching and robust changes to the intestinal microbiota of SHRs and provided a better understanding of the relationship between efficacy of valsartan and gastrointestinal tract reaction.

[Effect of benzo(a)pyrene on dopaminergic neurons and α-synuclein in brain and its mechanism involved]

OBJECTIVE

To analyze the effect of benzopyrene on the decrease of dopaminergic neurons, and the increase and aggregation of α-synuclein, which are the pathological features of Parkinson's disease, and to explore its possible mechanisms.

METHODS

Eight-month-old transgenic mice with human SNCA gene were randomly divided into a BaP-exposed group and a control group. BaP and solvent corn oil were injected intraperitoneally to BaP-exposed group and control group respectively, once a day for 60 days. The motor dysfunction of mice was tested by rotarod test. The effects of BaP on the decrease of dopaminergic neurons and increase and aggregation of α-synuclein were observed by immunohistochemistry and Western blot experiments respectively, and the expression of related mRNA was detected by quantitative real-time PCR (qRT-PCR). Twenty genes were tested in the study, mainly related to neurotransmitter transporter (2 genes), neurotransmitter receptor function (10 genes), cellular autophagy (5 genes), and α-synuclein aggregation and degradation (3 genes).

RESULTS

After BaP exposure, the movement time of the mice in the rotarod test was significantly reduced (P<0.05). The substantia nigra dopami-nergic neurons in the mice were significantly reduced, which was 62% of the control group (P<0.05), and the expression of α-synuclein in the midbrain increased, which was 1.36 times that of the control group (P<0.05). After BaP exposure, mRNA expressions of 14 genes in the midbrain of the mice were significantly down-regulated (P<0.05). Alpha-synuclein degradation and cell autophagy (5 genes), neuron transporters (2 genes), and neurotransmitter receptor functions (5 genes) were involved. The expression of one gene, Synphilin-1, was significantly up-regulated (P<0.01), which was related to α-synuclein aggregation.

CONCLUSION

BaP exposure not only inhibited function of neurotransmitter receptor and dopamine transporter, but also interfered cell autophagy, thereby hindering the degradation of α-synuclein, which could lead to decrease of dopaminergic neurons in substantia nigra and increase and aggregation of α-synuclein in midbrain, as the significant pathology of Parkinson's disease. Therefore, BaP exposure may increase the risk of Parkinson's disease.

MicroRNA-217 ameliorates inflammatory damage of endothelial cells induced by oxidized LDL by targeting EGR1

Oxidized low-density lipoprotein (ox-LDL) modulates gene transcription and expression and induces the development of endothelium inflammation and endothelial dysfunction, in which microRNAs (miRNAs) play a crucial role. However, the mechanism of ox-LDL in inflammatory damage of endothelial cells still remains elusive. Herein, we focused on the effect of hsa-miR-217-5p (miR-217) on endothelial dysfunction induced by ox-LDL by targeting early growth response protein-1 (EGR1). In the present study, 31 upregulated miRNAs and 59 downregulated miRNAs (Fold Change > 2, P value < 0.05) were identified after 6 h of 80 μg/mL ox-LDL exposure in human aortic endothelial cells (HAECs) by small RNA sequencing, including miR-217 that was significantly decreased (FC = 0.2787, P value = 5.22E-16). MiR-217 knockdown inhibited cell proliferation and increased level of IL-6, IL-1β, ICAM-1 and TNF-α, while overexpression of miR-217 relieved the growth inhibition induced by ox-LDL and demonstrated anti-inflammatory effect in HAECs. EGR1 was predicted as a potential candidate target gene of miR-217 by TargetScan. The subsequent dual-luciferase reporter assay confirmed the direct binding of miR-217 to 3'UTR of EGR1. And EGR1 expression was negatively correlated with the level of miRNA-217 in HAECs after exposure to ox-LDL. Overexpression of EGR1 recapitulated the effects of miR-217 knockdown on cell proliferation inhibition and inflammation in HAECs, while knockdown EGR1 relieved the proliferative inhibition and demonstrated anti-inflammatory effect in ox-LDL-induced HAECs. The present study confirmed miR-217 ameliorates inflammatory damage of endothelial cells induced by oxidized LDL by targeting EGR1.

Quantitative proteomics reveals mitochondrial respiratory chain as a dominant target for carbon ion radiation: Delayed reactive oxygen species generation caused DNA damage

Heavy ion radiotherapy has shown great promise for cancer therapy. Understanding the cellular response mechanism to heavy ion radiation is required to explore measures of overcoming devastating side effects. Here, we performed a quantitative proteomic analysis to investigate the mechanism of carbon ion irradiation on human AHH-1 lymphoblastoid cells. We identified 4602 proteins and quantified 4569 proteins showing high coverage in the mitochondria. Data are available via ProteomeXchange with identifier PXD008351. After stringent filtering, 290 proteins were found to be significantly up-regulated and 16 proteins were down-regulated. Functional analysis revealed that these up-regulated proteins were enriched in the process of DNA damage repair, mitochondrial ribosome, and particularly mitochondrial respiratory chain, accounting for approximately 50% of the accumulated proteins. Bioinformatics and functional analysis demonstrated that these up-regulated mitochondrial respiratory chain proteins enhanced ATP production and simultaneously reactive oxygen species release. More importantly, increased reactive oxygen species led to secondary organelle injury and lagged DNA double-strand breaks. Consistently, the expression of antioxidant enzymes was up-regulated for free radical scavenging. The mechanism of lagged secondary injury originated from disturbances in the mitochondrial respiratory chain. Our results provided a novel target for cell self-repair against heavy ion radiation-induced cellular damage.

[Effects of benzo(a)pyrene on expressions of insulin-degrading enzyme and neprilysin in neuroglia cells]

OBJECTIVE

To investigate effects of benzo(a)pyrene (BaP) on expressions of insulin-degrading enzyme (IDE) and neprilysin (NEP) which have the ability to degrade β-amyloid (Aβ) in neuroglia cells.

METHODS

Primary mix-neuroglia cells were cultured from newborn SD rats. After exposure to BaP, Aβ_1-42 oligomer or Aβ_1-42 fiber individually or jointly for 24 h, the cell survival rate was measured by cell counting kit-8 (CCK-8). Afterwards, the primary mix-neuroglia cells were divided randomly into six groups: Control group, BaP group (2.00 μmol/L), Aβ_1-42 oligomer group (20.00 mg/L), BaP plus Aβ_1-42 oligomer group, Aβ_1-42 fiber group (20.00 mg/L) and BaP plus Aβ_1-42 fiber group, of which BaP was pretreated for 12 h followed by cotreatment with different aggregated Aβ_1-42. The expressions of IDE and NEP were measured by quantitative real-time polymerase chain reaction (qRT-PCR) for mRNA level and Western blotting for protein level.

RESULTS

The cell survival rate showed no significant differences after treatment with BaP (≤20.00 μmol/L), Aβ_1-42 oligomer (20.00, 40.00 mg/L), Aβ_1-42 fiber (20.00, 40.00 mg/L) or cotreatment with BaP and Aβ_1-42 oligomer or BaP and Aβ_1-42 fiber. Compared with the control group, expressions of IDE and NEP in BaP-treated alone group had no obvious change; however, exposure to Aβ_1-42 oligomer alone significantly increased the mRNA and protein level of IDE (P<0.05), and the BaP pretreatment could significantly inhibit the up-regulated expressions of IDE by Aβ_1-42 oligomer (P<0.05); on the other hand, exposure either to Aβ_1-42 fiber alone or under the BaP pretreatment did not change the mRNA and protein level of IDE and NEP obviously.

CONCLUSION

On the premise of no significant change of cell survival rate, BaP pretreatment inhibited the up-regulated expressions of IDE in primary mixed neuroglia cells under cotreatment with Aβ oligomer, indicating that BaP may disturb degradation of Aβ oligomer and cause deposition of β-amyloid and further induce cognitive decline and acceleration of Alzheimer.

Integrated analysis of long noncoding RNA and mRNA profiling ox-LDL-induced endothelial dysfunction after atorvastatin administration

BACKGROUND

Long noncoding RNAs (lncRNAs) play a key role in the development of endothelial dysfunction. However, few lncRNAs associated with endothelial dysfunction after atorvastatin administration have been reported.

METHODS

In the present study, differentially expressed (DE) genes in ox-LDL versus control and ox-LDL + atorvastatin versus control were detected. Bioinformatics analysis and integrated analysis of mRNAs and lncRNAs were conducted to study the mechanisms of endothelial dysfunction after atorvastatin administration and to explore the regulation functions of lncRNAs.

RESULTS

Here, 532 DE mRNAs and 532 DE lncRNAs were identified (among them, 195 mRNAs and 298 lncRNAs were upregulated, 337 mRNAs and 234 lncRNAs were downregulated) after ox-LDL treatment for 24 hours (fold change ≥2.0, P < .05). After ox-LDL treatment following atorvastatin administration, 750 DE mRNAs and 502 DE lncRNAs were identified (among them, 149 mRNAs and 218 lncRNAs were upregulated and 601 mRNAs and 284 lncRNAs were downregulated). After atorvastatin administration, 167 lncRNAs and 262 mRNAs were still DE. Q-PCR validated the results of microarrays.

CONCLUSION

Chronic inflammatory response, nitric oxide biosynthetic process, microtubule cytoskeleton, cell proliferation and cell migration are regulated by lncRNAs, which also participated in the mainly molecular function and biological processes underlying endothelial dysfunction. Atorvastatin partly improved endothelial dysfunction, but the aspects beyond recovery were mainly concentrated in cell cycle, mitosis, and metabolism. Further exploration is required to explicit the mechanism by which lncRNAs participate in endothelial dysfunction.

Deep Coverage Proteomics Identifies More Low-Abundance Missing Proteins in Human Testis Tissue with Q-Exactive HF Mass Spectrometer

Since 2012, missing proteins (MPs) investigation has been one of the critical missions of Chromosome-Centric Human Proteome Project (C-HPP) through various biochemical strategies. On the basis of our previous testis MPs study, faster scanning and higher resolution mass-spectrometry-based proteomics might be conducive to MPs exploration, especially for low-abundance proteins. In this study, Q-Exactive HF (HF) was used to survey proteins from the same testis tissues separated by two separating methods (tricine- and glycine-SDS-PAGE), as previously described. A total of 8526 proteins were identified, of which more low-abundance proteins were uniquely detected in HF data but not in our previous LTQ Orbitrap Velos (Velos) reanalysis data. Further transcriptomics analysis showed that these uniquely identified proteins by HF also had lower expression at the mRNA level. Of the 81 total identified MPs, 74 and 39 proteins were listed as MPs in HF and Velos data sets, respectively. Among the above MPs, 47 proteins (43 neXtProt PE2 and 4 PE3) were ranked as confirmed MPs after verifying with the stringent spectra match and isobaric and single amino acid variants filtering. Functional investigation of these 47 MPs revealed that 11 MPs were testis-specific proteins and 7 MPs were involved in spermatogenesis process. Therefore, we concluded that higher scanning speed and resolution of HF might be factors for improving the low-abundance MP identification in future C-HPP studies. All mass-spectrometry data from this study have been deposited in the ProteomeXchange with identifier PXD004092.

Paralytic shellfish poisoning in southern China

The rapidly expanding mariculture and commercial region along the southern coast of China has experienced sporadic outbreaks of paralytic shellfish poisoning for nearly 30 years, yet virtually nothing is known of the nature of that toxicity or of the causative organisms. This study presents the first direct comparisons of the high performance liquid chromatography toxin composition profiles of shellfish implicated in paralytic shellfish poisoning outbreaks in Daya Bay with Alexandrium tamarense cultures established from those waters. The three cultures that were analyzed produced an unusually high proportion of the low potency N-sulfocarbamoyl toxins C1 and C2 (nearly 90% of the total), and only trace quantities of the other saxitoxin derivatives. Total toxicity was thus very low with mild acid extraction, ranging between 7.2 and 12.7 fmole cell-1, or 0.7-0.9 pg saxitoxin equiv. cell-1. Following acid hydrolysis using the standard AOAC extraction method, the dominant toxins in the cultures were gonyautoxins 2 and 3 and decarbamoyl gonyautoxins 2 and 3. Total potency increased fourfold to 2.6-3.4 pg saxitoxin equiv. cell-1 following acid hydrolysis. These cultures are thus at the low end of the range of toxicities recorded for members of the A. tamarense species complex. Two scallop samples and one mussel sample collected from Daya Bay during paralytic shellfish poisoning episodes in 1990 and 1991 were also analyzed following the AOAC extraction procedure. The toxin profiles were similar for the three shellfish samples, in that the same suite of toxins were present in each, but the relative proportion of those toxins varied. The dominant toxins were gonyautoxins 2 and 3 and toxins C1-C4. Total toxicity was 336 and 654 micrograms saxitoxin per 100 g meat for the scallop samples, and 723 for the mussels. Toxins C3,4 were present in the shellfish at up to 22 mole%, but were not detected in cultures, even when mild acid was used for extraction. Despite the otherwise similar nature of the culture versus the shellfish toxin signatures, the presence of C3,4 indicates that another strain or species of Alexandrium, or possibly a paralytic shellfish poisoning-producing species of another genus was responsible for the 1990 and 1991 paralytic shellfish poisoning outbreaks in Daya Bay. Since the cultures analyzed were of low intrinsic toxicity, A. tamarense may be more widespread along the south coast of China than is suggested by the sporadic pattern of past paralytic shellfish poisoning outbreaks. Blooms with high cell density are required to generate sufficient toxin to be dangerous. The alarming increase in algal blooms in Chinese waters due to persistent and growing pollution may make these low toxicity populations more problematic in the future.