PPAR- and LXR-dependent pathways controlling lipid metabolism and the development of atherosclerosis

In vitro screening of understudied PFAS with a focus on lipid metabolism disruption

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used in many industrial applications. Exposure to PFAS is associated with several health risks, including a decrease in infant birth weight, hepatoxicity, disruption of lipid metabolism, and decreased immune response. We used the in vitro cell models to screen six less studied PFAS [perfluorooctane sulfonamide (PFOSA), perfluoropentanoic acid (PFPeA), perfluoropropionic acid (PFPrA), 6:2 fluorotelomer alcohol (6:2 FTOH), 6:2 fluorotelomer sulfonic acid (6:2 FTSA), and 8:2 fluorotelomer sulfonic acid (8:2 FTSA)] for their capacity to activate nuclear receptors and to cause differential expression of genes involved in lipid metabolism. Cytotoxicity assays were run in parallel to exclude that observed differential gene expression was due to cytotoxicity. Based on the cytotoxicity assays and gene expression studies, PFOSA was shown to be more potent than other tested PFAS. PFOSA decreased the gene expression of crucial genes involved in bile acid synthesis and detoxification, cholesterol synthesis, bile acid and cholesterol transport, and lipid metabolism regulation. Except for 6:2 FTOH and 8:2 FTSA, all tested PFAS downregulated PPARA gene expression. The reporter gene assay also showed that 8:2 FTSA transactivated the farnesoid X receptor (FXR). Based on this study, PFOSA, 6:2 FTSA, and 8:2 FTSA were prioritized for further studies to confirm and understand their possible effects on hepatic lipid metabolism.

Higher expression of TSR2 aggravating hypertension via the PPAR signaling pathway

Hypertension is a complex disease with unknown causes. Therefore, it's crucial to deeply study its molecular mechanism. The hypertension dataset was obtained from Gene Expression Omnibus data base (GEO), and miRNA regulating central hub genes was screened via weighted gene co-expression network (DEGs) and gene set enrichment (GSEA). Cell experiments validated TSR2's role and the PPAR signaling pathway through western blotting. 500 DEGs were identified for hypertension, mainly enriched in actin cross-linking, insulin signaling, PPAR signaling, and protein localization. Eight hub genes (SEC61G, SRP14, Liy AR, NIP7, SDAD1, POLR1D, DYNLL2, TSR2) were identified. Four hub genes (LYAR, SDAD1, POLR1D, TSR2) exhibited high expression levels in the hypertensive tissue samples, while showing low expression levels in the normal tissue samples. This led us to speculate that they may have relevant regulatory effects on hypertension. When TSR2 was knocked down in the hypertension peripheral blood mononuclear cells (PBMC) model, the critical proteins in the PPAR signaling pathway (FABP, PPAR, PLTP, ME1, SCD1, CYP27, FABP1, OLR1, CPT-1, PGAR, CAP, ADIPO, MMP1, UCP1, ILK, PDK1 UBC AQP7) were downregulated. This also occurred in the hypertension peripheral blood mononuclear cells (PBMC) + TSR2_ OV model. TSR2 is highly expressed in individuals with hypertension and may play a significant role in the development of hypertension through the PPAR signaling pathway. TSR2 could serve as a molecular target for the early diagnosis and precise treatment of hypertension, providing a valuable direction for the mechanism research of this condition.

Flavonoids from mulberry leaves inhibit fat production and improve fatty acid distribution in adipose tissue in finishing pigs

This study evaluated the effects of flavonoids from mulberry leaves (FML) on plasma biochemical indices, serum activities of lipid metabolism-related enzymes, fat morphology, fatty acid composition, and lipid metabolism in different adipose tissues of finishing pigs. We used 120 Chinese hybrid barrows of Berkshire and Bama mini-pigs with an average initial body weight of 45.11 ± 4.23 kg. The pigs were randomly assigned to five treatment groups and fed a control diet based on corn, soybean meal, and wheat bran or a control diet supplemented with 0.02%, 0.04%, 0.08%, or 0.16% FML. Each experimental group had six replicates (pens), with four pigs per pen. After a 7-d adaptation period, the feeding trial was conducted for 58 d. Blood and adipose tissue samples were collected from 30 pigs (one pig per pen) at the end of the test. The results showed that FML supplementation significantly decreased the feed intake to body gain ratio, the plasma concentrations of total cholesterol and free fatty acids, and the serum activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (linear or quadratic effects, P < 0.05), and decreased the plasma triglyceride concentration (quadratic, P = 0.07). Increasing FML supplementation increased the average daily gain and serum activities of lipoprotein lipase (linear and quadratic effects, P < 0.05) and adipose triglyceride lipase (linear, P < 0.05). Dietary FML supplementation decreased the adipocyte area in the dorsal subcutaneous adipose (DSA) tissue of finishing pigs (linear, P = 0.05) and increased the adipocyte area in the visceral adipose tissue (quadratic, P < 0.01). Increasing FML supplementation decreased the C20:1 content in DSA, abdominal subcutaneous adipose, and visceral adipose tissues of finishing pigs (P < 0.05) and increased the C18:3n3 and n-3 PUFA contents (P < 0.05). The lipid metabolism genes were regulated by the PPARγ-LXRα-ABCA1 signaling pathway, and their expressions differed in different adipose tissues. These findings suggest that FML improved growth performance, regulated lipid metabolism, inhibited fat production, and improved fatty acid distribution in the adipose tissue of finishing pigs, thereby improving pig fat's nutritional quality and health value.

Coculturing liver cancer cells and monocytes in spheroids conditions monocytes to adopt tumor-associated macrophage phenotypes that favor tumor growth via cholesterol metabolism

Tumor-infiltrating immune cells and their crosstalk with cancer cells in the tumor microenvironment (TME) play a crucial role in shaping tumor progression and response to therapy. We utilized 3-dimensional liver cancer spheroids incorporating human primary monocytes to investigate the crosstalk between tumor-associated macrophages (TAMs) and Hepatocellular carcinoma (HCC) cells, HepG2 and PLC/PRF/5. Using multiplexed gene expression panels, the critical pathways involved in shaping primary human monocytes to adopt TAMs phenotypes were identified. The specific inhibitor for an identified pathway was used to explore its involvement in polarization of TAMs. In the cocultured spheroids comprising the human HCC cell lines, the infiltrating monocytes resembled protumor M2-like macrophage phenotypes. Gene expression panels of the infiltrating monocytes demonstrated that the upregulated genes were enriched in the cholesterol metabolism pathway. Cholesterol metabolism-related genes were upregulated together with the nuclear receptors, PPARG and LXR. When lysosomal acid lipase (LAL), the key enzyme necessary for the hydrolysis of lipoprotein, was inhibited, infiltrating monocytes in 3-dimensional spheroid coculture showed significantly decreased M2 marker and lipid uptake receptor expression as well as increased cellular lipid content, which indicated that cholesterol metabolism was important for conditioning the TAMs. Moreover, LAL inhibition reduced the spheroid growth and invasiveness of HCC cell lines. Small interfering RNA-mediated LAL silencing in monocytes yielded similar results upon spheroid coculture. These data indicated that liver cancer cells and infiltrating monocytes participate in crosstalk via cholesterol metabolism to condition monocytes toward TAMs, which favors tumor growth and survival, thereby promoting liver cancer progression.

HDL as a Treatment Target: Should We Abandon This Idea?

PURPOSE OF REVIEW

High-density lipoproteins (HDL) have long been regarded as an antiatherogenic lipoprotein species by virtue of their role in reverse cholesterol transport (RCT), as well as their established anti-inflammatory and antioxidant properties. For decades, HDL have been an extremely appealing therapeutic target to combat atherosclerotic cardiovascular diseases (ASCVD).

RECENT FINDINGS

Unfortunately, neither increasing HDL with drugs nor direct infusions of reconstituted HDL have convincedly proven to be positive strategies for cardiovascular health, raising the question of whether we should abandon the idea of considering HDL as a treatment target. The results of two large clinical trials, one testing the latest CETP inhibitor Obicetrapib and the other testing the infusion of patients post-acute coronary events with reconstituted HDL, are still awaited. If they prove negative, these trials will seal the fate of HDL as a direct therapeutic target. However, using HDL as a therapeutic agent still holds promise if we manage to optimize their beneficial properties for not only ASCVD but also outside the cardiovascular field.

The knockout of cytoglobin 1 in zebrafish (Danio rerio) alters lipid metabolism, iron homeostasis and oxidative stress response

Cytoglobin (Cygb) is an evolutionary ancient heme protein with yet unclear physiological function(s). Mammalian Cygb is ubiquitously expressed in all tissues and is proposed to be involved in reactive oxygen species (ROS) detoxification, nitric oxide (NO) metabolism and lipid-based signaling processes. Loss-of-function studies in mouse associate Cygb with apoptosis, inflammation, fibrosis, cardiovascular dysfunction or oncogenesis. In zebrafish (Danio rerio), two cygb genes exist, cytoglobin 1 (cygb1) and cytoglobin 2 (cygb2). Both have different coordination states and distinct expression sites within zebrafish tissues. The biological roles of the cygb paralogs are largely uncharacterized. We used a CRISPR/Cas9 genome editing approach and generated a knockout of the penta-coordinated cygb1 for in vivo analysis. Adult male cygb1 knockouts develop phenotypic abnormalities, including weight loss. To identify the molecular mechanisms underlying the occurrence of these phenotypes and differentiate between function and effect of the knockout we compared the transcriptomes of cygb1 knockout at different ages to age-matched wild-type zebrafish. We found that immune regulatory and cell cycle regulatory transcripts (e.g. tp53) were up-regulated in the cygb1 knockout liver. Additionally, the expression of transcripts involved in lipid metabolism and transport, the antioxidative defense and iron homeostasis was affected in the cygb1 knockout. Cygb1 may function as an anti-inflammatory and cytoprotective factor in zebrafish liver, and may be involved in lipid-, iron-, and ROS-dependent signaling.

Calprotectin blockade inhibits long-term vascular pathology following peritoneal dialysis-associated bacterial infection

Bacterial infections and the concurrent inflammation have been associated with increased long-term cardiovascular (CV) risk. In patients receiving peritoneal dialysis (PD), bacterial peritonitis is a common occurrence, and each episode further increases late CV mortality risk. However, the underlying mechanism(s) remains to be elucidated before safe and efficient anti-inflammatory interventions can be developed. Damage-Associated Molecular Patterns (DAMPs) have been shown to contribute to the acute inflammatory response to infections, but a potential role for DAMPs in mediating long-term vascular inflammation and CV risk following infection resolution in PD, has not been investigated. We found that bacterial peritonitis in mice that resolved within 24h led to CV disease-promoting systemic and vascular immune-mediated inflammatory responses that were maintained up to 28 days. These included higher blood proportions of inflammatory leukocytes displaying increased adhesion molecule expression, higher plasma cytokines levels, and increased aortic inflammatory and atherosclerosis-associated gene expression. These effects were also observed in infected nephropathic mice and amplified in mice routinely exposed to PD fluids. A peritonitis episode resulted in elevated plasma levels of the DAMP Calprotectin, both in PD patients and mice, here the increase was maintained up to 28 days. In vitro, the ability of culture supernatants from infected cells to promote key inflammatory and atherosclerosis-associated cellular responses, such as monocyte chemotaxis, and foam cell formation, was Calprotectin-dependent. In vivo, Calprotectin blockade robustly inhibited the short and long-term peripheral and vascular consequences of peritonitis, thereby demonstrating that targeting of the DAMP Calprotectin is a promising therapeutic strategy to reduce the long-lasting vascular inflammatory aftermath of an infection, notably PD-associated peritonitis, ultimately lowering CV risk.

Microbial oil, alone or paired with β-glucans, can control hypercholesterolemia in a zebrafish model

Dyslipidemia is often associated with unhealthy dietary habits, and many mammalian studies have explored the mode of action of certain bioactive compounds such as β-glucans and n-3 PUFAs to understand their potential to normalize the lipid metabolism. There are only a few investigations that adopted omic approaches to unveil their combined effect on hypercholesterolemia. Zebrafish (Danio rerio) was used as a model organism to reveal the efficacy of Schizochytrium oil and β-glucans (from Euglena gracilis and Phaeodactylum tricornutum) against cholesterol-rich diet induced dyslipidemia. One of the folowing four diets was fed to a particular group of fish: a control high-cholesterol diet, a Schizochytrium oil diet or one of the two diets containing the oil and β-glucan. The plasma HDL, expression of hepatic genes linked to, among others, ferric ion binding and plasma phosphatidylcholines were higher and plasma cholesterol esters and triacylglycerols were lower in the microbial oil-fed fish compared to the fish fed high cholesterol diet. While the fish fed a mix of microbial oil and Euglena β-glucan had lower plasma triacylglycerols and expression of hepatic genes linked to PPAR signaling pathway and enriched biosynthesis of plasma unsaturated fatty acids, the fish fed microbial oil-Phaeodactylum β-glucan combination had lower abundance of triacylglycerols rich in saturated and mono-unsaturated fatty acids and cholesterol esters in the plasma.

Fatty acid synthesis and oxidation regulate human endoderm differentiation by mediating SMAD3 nuclear localization via acetylation

Metabolic remodeling is one of the earliest events that occur during cell differentiation. Here, we define fatty acid metabolism as a key player in definitive endoderm differentiation from human embryonic stem cells. Fatty acid β-oxidation is enhanced while lipogenesis is decreased, and this is due to the phosphorylation of lipogenic enzyme acetyl-CoA carboxylase by AMPK. More importantly, inhibition of fatty acid synthesis by either its inhibitors or AMPK agonist significantly promotes human endoderm differentiation, while blockade of fatty acid oxidation impairs differentiation. Mechanistically, reduced de novo fatty acid synthesis and enhanced fatty acid β-oxidation both contribute to the accumulation of intracellular acetyl-CoA, which guarantees the acetylation of SMAD3 and further causes nuclear localization to promote endoderm differentiation. Thus, our current study identifies a fatty acid synthesis/oxidation shift during early differentiation and presents an instructive role for fatty acid metabolism in regulating human endoderm differentiation.

Hyocholic acid retards renal fibrosis by regulating lipid metabolism and inflammatory response in a sheep model

The kidneys are vital organs that regulate metabolic homeostasis in the body, filter waste products from the blood, and remove extrahepatic bile acids. We previously found that the dietary supplementation of hyocholic acid alleviated the sheep body lipid deposition and decreased kidney weight. This study evaluated hyocholic acid's (HCA) roles and mechanisms on lipid metabolism and anti-inflammatory function in the kidney under a high-energy diet. Histomicrograph showing the apparent improvement by HCA by attenuating structural damage. The HCA treatment reduced the renal accumulation of cholesterol. Bile acid receptors such as LXR and FXR were activated at the protein level. HCA significantly altered several genes related to immune response (NF-κB, IL-6, and MCP1) and fibrosis (TGF-β, Col1α1, and α-SMA). These significant changes correlated with renal lipid accumulation. The KEGG pathways including non-alcoholic fatty liver disease, insulin resistance, TNF signaling pathway, and Th17 cell differentiation were enriched and NF-κB, IL-6, and TGF-β were identified as the core interconnected genes. This study revealed that HCA plays an efficient role in alleviating kidney lipids accumulation and inflammatory response through crucial genes such as FXR, LXR, HMGCR, NF-κB, IL-6, MCP1, and TGF-β, and expand our understanding of HCA's role in kidney function. In conclusion, HCA mitigated kidney fibrosis, lipid metabolism disorders and immune responses induced by a high-energy diet by regulating a potential LXR/SREBP2/TGF-β-NF-κB signaling pathway.

The role of peroxisome proliferator-activated receptor γ in lipid metabolism and inflammation in atherosclerosis

Cardiovascular disease events are the result of functional and structural abnormalities in the arteries and heart. Atherosclerosis is the main cause and pathological basis of cardiovascular diseases. Atherosclerosis is a multifactorial disease associated with dyslipidemia, inflammation, and oxidative stress, among which dyslipidemia and chronic inflammation occur in all processes. Under the influence of lipoproteins, the arterial intima causes inflammation, necrosis, fibrosis, and calcification, leading to plaque formation in specific parts of the artery, which further develops into plaque rupture and secondary thrombosis. Foam cell formation from macrophages is an early event in the development of atherosclerosis. Lipid uptake causes a vascular inflammatory response, and persistent inflammatory infiltration in the lesion area further promotes the development of the disease. Inhibition of macrophage differentiation into foam cell and reduction of the level of proinflammatory factors in macrophages can effectively alleviate the occurrence and development of atherosclerosis. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor that plays an important antiatherosclerotic role by regulating triglyceride metabolism, lipid uptake, cholesterol efflux, macrophage polarity, and inhibiting inflammatory signaling pathways. In addition, PPARγ shifts its binding to ligands and co-activators or co-repressors of transcription of target genes through posttranslational modification, thereby affecting the regulation of its downstream target genes. Many ligand agonists have also been developed targeting PPARγ. In this review, we summarized the role of PPARγ in lipid metabolism and inflammation in development of atherosclerosis, the posttranslational regulatory mechanism of PPARγ, and further discusses the value of PPARγ as an antiatherosclerosis target.

Phytochemical Characterization and In Vitro Anti-Inflammatory Evaluation in RAW 264.7 Cells of Jatropha cordata Bark Extracts

The inflammatory process, although beneficial, can produce tissue damage and systemic damage when uncontrolled. Effective therapeutic alternatives with little or no side effects are of great therapeutic interest. This study aimed to determine the phytochemical composition of bark extracts from J. cordata, an endemic plant from México, and evaluate their in vitro anti-inflammatory activity. Hexane, ethyl acetate, and methanol extracts were characterized by qualitative phytochemical tests, and their bioactive groups were identified by ¹H NMR and gas chromatography coupled to mass spectrometry (GC-MS). The extract's anti-inflammatory activity was evaluated as nitric oxide (NO) production and their cytotoxicity by an MTS cell proliferation assay in lipopolysaccharide (LPS)-activated RAW 264.7 cells at concentrations of 1-100 μg/mL. The hexane extract contained fatty acids, fatty esters, phytosterols, alkanes, vitamin E, and terpenoids; the ethyl acetate extract showed fatty acids, fatty esters, aromatic aldehyde, phytosterols, vitamin E, and terpenoids, while the methanolic extract showed fatty esters, fatty acid, aromatics aldehydes, and alcohol. The ethyl acetate extract showed the highest inhibition of NO production, followed by the methanolic extract and the hexane extract, without affecting the viability of RAW 264.7 macrophage cells. The results suggest that J. cordata extracts are a potential source of bioactive compounds with anti-inflammatory potential.

Butyrate Lowers Cellular Cholesterol through HDAC Inhibition and Impaired SREBP-2 Signalling

In animal studies, HDAC inhibitors such as butyrate have been reported to reduce plasma cholesterol, while conferring protection from diabetes, but studies on the underlying mechanisms are lacking. This study compares the influence of butyrate and other HDAC inhibitors to that of statins on cholesterol metabolism in multiple cell lines, but primarily in HepG2 hepatic cells due to the importance of the liver in cholesterol metabolism. Sodium butyrate reduced HepG2 cholesterol content, as did sodium valproate and the potent HDAC inhibitor trichostatin A, suggesting HDAC inhibition as the exacting mechanism. In contrast to statins, which increase SREBP-2 regulated processes, HDAC inhibition downregulated SREBP-2 targets such as HMGCR and the LDL receptor. Moreover, in contrast to statin treatment, butyrate did not increase cholesterol uptake by HepG2 cells, consistent with its failure to increase LDL receptor expression. Sodium butyrate also reduced ABCA1 and SRB1 protein expression in HepG2 cells, but these effects were not consistent across all cell types. Overall, the underlying mechanism of cell cholesterol lowering by sodium butyrate and HDAC inhibition is consistent with impaired SREBP-2 signalling, and calls into question the possible use of butyrate for lowering of serum LDL cholesterol in humans.

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.

Cyclic Phthalate Esters as Liver X Receptor Antagonists with Anti-hepatitis C Virus and Anti-severe Acute Respiratory Syndrome Coronavirus 2 Properties

The liver X receptor is a nuclear hormone receptor that regulates lipid metabolism. Previously, we had demonstrated the antiviral properties of a liver X receptor antagonist associated with the hepatitis C virus and severe acute respiratory syndrome coronavirus 2. In this study, we screened a chemical library and identified two potential liver X receptor antagonists. Spectroscopic analysis revealed that the structures of both antagonists (compounds 1 and 2) were cyclic dimer and trimer of esters, respectively, that consisted of phthalate and 1,6-hexane diol. This study is the first to report the structure of the cyclic trimer of phthalate ester. Further experiments revealed that the compounds were impurities of solvents used for purification, although their source could not be traced. Both phthalate esters exhibited anti-hepatitis C virus activity, whereas the cyclic dimer showed anti-severe acute respiratory syndrome coronavirus 2 activity. Cyclic phthalate derivatives may constitute a novel class of liver X receptor antagonists and broad-spectrum antivirals.

Single-cell transcriptomics reveal cellular diversity of aortic valve and the immunomodulation by PPARγ during hyperlipidemia

Valvular inflammation triggered by hyperlipidemia has been considered as an important initial process of aortic valve disease; however, cellular and molecular evidence remains unclear. Here, we assess the relationship between plasma lipids and valvular inflammation, and identify association of low-density lipoprotein with increased valvular lipid and macrophage accumulation. Single-cell RNA sequencing analysis reveals the cellular heterogeneity of leukocytes, valvular interstitial cells, and valvular endothelial cells, and their phenotypic changes during hyperlipidemia leading to recruitment of monocyte-derived MHC-II^hi macrophages. Interestingly, we find activated PPARγ pathway in Cd36⁺ valvular endothelial cells increased in hyperlipidemic mice, and the conservation of PPARγ activation in non-calcified human aortic valves. While the PPARγ inhibition promotes inflammation, PPARγ activation using pioglitazone reduces valvular inflammation in hyperlipidemic mice. These results show that low-density lipoprotein is the main lipoprotein accumulated in the aortic valve during hyperlipidemia, leading to early-stage aortic valve disease, and PPARγ activation protects the aortic valve against inflammation.

Identifying the mechanisms underlying the early inflammatory phase of aortic valve disease is crucial for disease prevention. Here the authors perform single-cell RNA sequencing to show the immunomodulatory role of PPARγ in valvular endothelial cells during hyperlipidemia.

The add-on effects of Danhong injection among patients with ischemic stroke receiving Western medicines: A systematic review and meta-analysis

Background: Danhong injection is widely used for treating ischemic stroke in China. However, its effects on ischemic stroke patients when given along with Western medicines (i.e., the add-on effect) were not well-established.

Methods: We searched PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and three Chinese databases from inception to 20 July 2020 to identify randomized controlled trials (RCTs) that assessed the effects of Danhong injection as add-on therapy in patients with ischemic stroke. Pairs of trained reviewers independently screened for eligible studies, assessed risk of bias, and extracted the data. The outcomes were the National Institutes of Health Stroke Scale Score (NIHSS), Barthel index, activities of daily living (ADL), total cholesterol, and homocysteine (Hcy).

Results: Sixty-seven RCTs of 6594 patients with varying risk of bias were included. Compared with Western medicine alone, the addition of Danhong injection to Western medicine significantly lowered the NIHSS score (45 RCTs with 4565 patients; MD −4.21, 95% CI −4.96 to −3.46), total cholesterol (10 trials with 1019 patients; MD −1.14 mmol/L, 95% CI −1.57 to −0.72), and Hcy (four trials with 392 patients; MD −3.54 μmol/L, 95% CI −4.38 to −2.07). The addition of Danhong also increased the Barthel index (14 trials with 1270 patients; MD 8.71, 95% CI 3.68–13.74) and ADL (12 trials with 1114 patients; MD 14.48, 95% CI 9.04–19.92) scores. Subgroup analyses showed differential effects in the average cerebral blood flow rate by mean age of patients (<60 years: MD 0.74 cm/s, 95% CI 0.29–1.19; ≥60 years: MD 4.09 cm/s, 95% CI 2.02–6.16; interaction p = 0.002) and the NIHSS score by type of baseline Western medicines (interaction p < 0.00001).

Conclusion: The addition of Danhong injection to Western medicine may improve neurological function, self-care ability, and blood lipid level of ischemic stroke patients. However, given most included trials with unclear risk of bias, current evidence is not definitive, and more carefully designed and conducted trials are warranted to confirm our findings.

Systematic Review Registration: [https://www.crd.york.ac.uk/PROSPERO/], identifier [CRD42022298628].

A multiomics disease progression signature of low-risk ccRCC

Clear cell renal cell carcinoma (ccRCC) is the most common renal cancer. Identification of ccRCC likely to progress, despite an apparent low risk at the time of surgery, represents a key clinical issue. From a cohort of adult ccRCC patients (n = 443), we selected low-risk tumors progressing within a 5-years average follow-up (progressors: P, n = 8) and non-progressing (NP) tumors (n = 16). Transcriptome sequencing, miRNA sequencing and proteomics were performed on tissues obtained at surgery. We identified 151 proteins, 1167 mRNAs and 63 miRNAs differentially expressed in P compared to NP low-risk tumors. Pathway analysis demonstrated overrepresentation of proteins related to “LXR/RXR and FXR/RXR Activation”, “Acute Phase Response Signaling” in NP compared to P samples. Integrating mRNA, miRNA and proteomic data, we developed a 10-component classifier including two proteins, three genes and five miRNAs, effectively differentiating P and NP ccRCC and capturing underlying biological differences, potentially useful to identify “low-risk” patients requiring closer surveillance and treatment adjustments. Key results were validated by immunohistochemistry, qPCR and data from publicly available databases. Our work suggests that LXR, FXR and macrophage activation pathways could be critically involved in the inhibition of the progression of low-risk ccRCC. Furthermore, a 10-component classifier could support an early identification of apparently low-risk ccRCC patients.

Three polymethoxyflavones from the peel of Citrus reticulata “Chachi” inhibits oxidized low-density lipoprotein-induced macrophage-derived foam cell formation

Foam cell formation is the hallmark of the development and progression of atherosclerosis. The aim of this study was to investigate the regulatory effects of three polymethoxyflavones (PMFs), namely, tangeretin (TAN), 5,6,7,3′,4′,5′-hexamethoxyflavone (HxMF), and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HpMF) on macrophage-derived foam cell formation and to further explore the molecular mechanisms. The RAW264.7 macrophage-derived foam cell model was successfully induced by oxidized low-density lipoprotein (ox-LDL) (80 μg/ml). It showed that TAN, HxMF, and HpMF alleviated ox-LDL-induced NO release while also inhibiting the expression of IL-1β, IL-6, and TNF-α in RAW264.7 cells. Uptake of excess ox-LDL was inhibited by TAN, HxMF, and HpMF, resulting in the reduction of its foam cell formation. Moreover, TAN, HxMF, and HpMF promoted HDL-mediated cholesterol efflux. Western blot experiment showed that TAN, HxMF, and HpMF inhibited the expression of scavenger receptor class A type I (SRA1) and cluster of differentiation 36 (CD36), while upregulating peroxisome proliferator-activated receptor γ (PPARγ), liver X receptor α (LXRα), phospholipid ATP-binding cassette transporter G1 (ABCG1), and scavenger receptor class B type I (SRB1) expression. Together, our findings suggested that PMFs inhibited foam cell formation might inhibit lipid uptake via downregulating SRA1/CD36 expression and promote cholesterol efflux from foam cells via upregulating PPARγ/LXRα/ABCG1/SRB1 expression. This antiatherosclerotic activity is expected to provide new insights into the development of healthcare uses for PMFs.

Xiaoyao San attenuates hepatic steatosis through estrogen receptor α pathway in ovariectomized ApoE-/- mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyao San (XYS) is a famous prescription in traditional Chinese medicine, which is used in the treatment of "liver depression and spleen deficiency" syndrome. It is often used clinically to treat chronic hepatitis, liver cirrhosis, various symptoms of postmenopausal women, especially mental disorders and digestive system diseases. However, the effect of XYS on hepatic steatosis in postmenopausal women remains unclear. In this research, we investigated the effects of XYS on hepatic steatosis in ovariectomized (OVX) apolipoprotein E knockout (ApoE-/-) mice, as well as the molecular mechanisms in vitro and in vivo.

MATERIALS AND METHODS

Fifty female ApoE-/- mice were divided into 5 groups: control group (Sham), model group (OVX), OVX + β-estradiol (E2, 0.4 mg/kg) group, OVX + XYS (13.0 g/kg) group, and OVX + XYS (6.5 g/kg) group. The control group received a standard diet, while the other groups received a high-fat diet (HFD). The hepatic pathologies of the mice were examined with Oil red O staining and HE staining after 12 week treatment. Blood and liver variables were determined enzymatically. Transmission electron microscopy was used to examine the ultrastructure of hepatocytes. The expression of estrogen receptor α (ERα) and lipid metabolism genes was analyzed by real-time PCR and/or Western blot. In in vitro studies, we investigated the effect of XYS-medicated serum on the expression and activity of ERα in L02 cells by immunofluorescence and luciferase reporter assays, and examined the protection of XYS-medicated serum against free fatty acid (FFA)-induced steatosis of L02 cells. Intracellular lipid accumulation were measured by Oil red O staining and Nile red staining assay. Finally, the influence of ICI 182,780, a specific antagonist of ERα, on the protective effect of XYS-medicated serum on FFA-induced steatosis of L02 cells was investigated.

RESULTS

Treatment of Ovx/ApoE-/- mice with XYS significantly decreased HFD-induced increases in hepatic steatosis and triglyceride (TG) content, accompanied by inhibition of liver X receptor α (LXRα), sterol regulatory element binding protein (SREBP)-1c and its target lipogenic genes transcription. Similarly, XYS-medicated serum reduced the size and number of lipid droplets and the cellular TG content in FFA-induced L02 cells. In addition, XYS significantly increased the ERα expression in hepatocytes in vivo and in vitro and enhanced the transcriptional activity of ERα promoter in L02 cells. And these effects could be partly reversed by the antiestrogen ICI 182,780.

CONCLUSIONS

These findings suggest that XYS has an estrogen-like effect and inhibits steatosis in postmenopausal animal models by reducing the expression of genes related to TG synthesis through ERα pathway.

Deletion of prominin-1 in mice results in disrupted photoreceptor outer segment protein homeostasis

AIM

To illustrate the underlying mechanism how prominin-1 (also known as Prom1) mutation contribute to progressive photoreceptor degeneration.

METHODS

A CRISPR-mediated Prom1 knockout (Prom1-KO) mice model in the C57BL/6 was generated and the photoreceptor degeneration phenotypes by means of structural and functional tests were demonstrated. Immunohistochemistry and immunoblot analysis were performed to reveal the localization and quantity of related outer segment (OS) proteins.

RESULTS

The Prom1-KO mice developed the photoreceptor degeneration phenotype including the decreased outer nuclear layer (ONL) thickness and compromised electroretinogram amplitude. Immunohistochemistry analysis revealed impaired trafficking of photoreceptor OS proteins. Immunoblot data demonstrated decreased photoreceptor OS proteins.

CONCLUSION

Prom1 deprivation causes progressive photoreceptor degeneration. Prom1 is essential for maintaining normal trafficking and normal quantity of photoreceptor OS proteins. The new light is shed on the pathogenic mechanism underlying photoreceptor degeneration caused by Prom1 mutation.

Transcriptional landscape in rat intestines under hypobaric hypoxia

Oxygen metabolism is closely related to the intestinal homeostasis environment, and the occurrence of many intestinal diseases is as a result of the destruction of oxygen gradients. The hypobaric hypoxic environment of the plateau can cause dysfunction of the intestine for humans, such as inflammation. The compensatory response of the small intestine cells to the harsh environment definitely changes their gene expression. How the small intestine cells response the hypobaric hypoxic environment is still unclear. We studied the rat small intestine under hypobaric hypoxic conditions to explore the transcriptional changes in rats under acute/chronic hypobaric hypoxic conditions. We randomly divided rats into three groups: normal control group (S), acute hypobaric hypoxia group, exposing to hypobaric hypoxic condition for 2 weeks (W2S) and chronic hypobaric hypoxia group, exposing to hypobaric hypoxic condition for 4 weeks (W4S). The RNA sequencing was performed on the small intestine tissues of the three groups of rats. The results of principal component analysis showed that the W4S and W2S groups were quite different from the control group. We identified a total of 636 differentially expressed genes, such as ATP binding cassette, Ace2 and Fabp. KEGG pathway analysis identified several metabolic and digestive pathways, such as PPAR signaling pathway, glycerolipid metabolism, fat metabolism, mineral absorption and vitamin metabolism. Cogena analysis found that up-regulation of digestive and metabolic functions began from the second week of high altitude exposure. Our study highlights the critical role of metabolic and digestive pathways of the intestine in response to the hypobaric hypoxic environment, provides new aspects for the molecular effects of hypobaric hypoxic environment on intestine, and raises further questions about between the lipid metabolism disorders and inflammation.

Early Transcriptional Liver Signatures in Experimental Visceral Leishmaniasis

Transcriptional analysis of complex biological scenarios has been used extensively, even though sometimes the results of such analysis may prove imprecise or difficult to interpret due to an overwhelming amount of information. In this study, a large-scale real-time qPCR experiment was coupled to multivariate statistical analysis in order to describe the main immunological events underlying the early L. infantum infection in livers of BALB/c mice. High-throughput qPCR was used to evaluate the expression of 223 genes related to immunological response and metabolism 1, 3, 5, and 10 days post infection. This integrative analysis showed strikingly different gene signatures at 1 and 10 days post infection, revealing the progression of infection in the experimental model based on the upregulation of particular immunological response patterns and mediators. The gene signature 1 day post infection was not only characterized by the upregulation of mediators involved in interferon signaling and cell chemotaxis, but also the upregulation of some inhibitory markers. In contrast, at 10 days post infection, the upregulation of many inflammatory and Th1 markers characterized a more defined gene signature with the upregulation of mediators in the IL-12 signaling pathway. Our results reveal a significant connection between the expression of innate immune response and metabolic and inhibitory markers in early L. infantum infection of the liver.

Bitter receptor TAS2R138 facilitates lipid droplet degradation in neutrophils during Pseudomonas aeruginosa infection

Bitter receptors function primarily in sensing taste, but may also have other functions, such as detecting pathogenic organisms due to their agile response to foreign objects. The mouse taste receptor type-2 member 138 (TAS2R138) is a member of the G-protein-coupled bitter receptor family, which is not only found in the tongue and nasal cavity, but also widely distributed in other organs, such as the respiratory tract, gut, and lungs. Despite its diverse functions, the role of TAS2R138 in host defense against bacterial infection is largely unknown. Here, we show that TAS2R138 facilitates the degradation of lipid droplets (LDs) in neutrophils during Pseudomonas aeruginosa infection through competitive binding with PPARG (peroxisome proliferator-activated receptor gamma) antagonist: N-(3-oxododecanoyl)-L-homoserine lactone (AHL-12), which coincidently is a virulence-bound signal produced by this bacterium (P. aeruginosa). The released PPARG then migrates from nuclei to the cytoplasm to accelerate the degradation of LDs by binding PLIN2 (perilipin-2). Subsequently, the TAS2R138-AHL-12 complex targets LDs to augment their degradation, and thereby facilitating the clearance of AHL-12 in neutrophils to maintain homeostasis in the local environment. These findings reveal a crucial role for TAS2R138 in neutrophil-mediated host immunity against P. aeruginosa infection.

Systemic PFOS and PFOA exposure and disturbed lipid homeostasis in humans: what do we know and what not?

Associations between per- and polyfluoroalkyl substances (PFASs) and increased blood lipids have been repeatedly observed in humans, but a causal relation has been debated. Rodent studies show reverse effects, i.e. decreased blood cholesterol and triglycerides, occurring however at PFAS serum levels at least 100-fold higher than those in humans. This paper aims to present the main issues regarding the modulation of lipid homeostasis by the two most common PFASs, PFOS and PFOA, with emphasis on the underlying mechanisms relevant for humans. Overall, the apparent contrast between human and animal data may be an artifact of dose, with different molecular pathways coming into play upon exposure to PFASs at very low versus high levels. Altogether, the interpretation of existing rodent data on PFOS/PFOA-induced lipid perturbations with respect to the human situation is complex. From a mechanistic perspective, research on human liver cells shows that PFOS/PFOA activate the PPARα pathway, whereas studies on the involvement of other nuclear receptors, like PXR, are less conclusive. Other data indicate that suppression of the nuclear receptor HNF4α signaling pathway, as well as perturbations of bile acid metabolism and transport might be important cellular events that require further investigation. Future studies with human-relevant test systems would help to obtain more insight into the mechanistic pathways pertinent for humans. These studies shall be designed with a careful consideration of appropriate dosing and toxicokinetics, so as to enable biologically plausible quantitative extrapolations. Such research will increase the understanding of possible perturbed lipid homeostasis related to PFOS/ PFOA exposure and the potential implications for human health.

Encapsulation of LXR ligand by D-Nap-GFFY hydrogel enhances anti-tumorigenic actions of LXR and removes LXR-induced lipogenesis

Background and purpose: Activation of liver X receptor (LXR) by its ligand T0901317 (T317) enhances interferon-γ (IFNγ) production to inhibit tumor growth. However, induction of severe hypertriglyceridemia and fatty liver by T317 limits its application. The naphthylacetic acid modified D-enantiomeric-glycine-phenylalanine-phenylalanine-tyrosine (D-Nap-GFFY) can form a nanofiber hydrogel which is selectively taken up by antigen-presenting cells (APCs). In this study, we determined if D-Nap-GFFY-encapsulated T317 (D-Nap-GFFY-T317) can potently inhibit tumor growth while having no adverse lipogenic effects on the liver. Methods: We prepared D-Nap-GFFY-T317 nanofiber hydrogel and subcutaneously injected it into IFNγ deficient (IFNγ^-/-) and wild-type (WT) mice with lung carcinoma, either inoculated LLC1 cells or urethane-induced carcinoma. Mice received oral T317 administration were used for comparison. Effects of treatment on tumor growth, lipogenesis and involved mechanisms were investigated. Results: Compared with T317 oral administration, injection of D-Nap-GFFY-T317 more potently inhibited LLC1 tumor growth in mice. The inhibition was dependent on LXR-activated IFNγ expression in APCs. D-Nap-GFFY-T317 increased M1 while reducing M2 type macrophages in tumors. Associated with activation of IFNγ expression, D-Nap-GFFY-T317 enhanced dendritic cell maturation and infiltration into tumors, increased CD3⁺/CD8⁺ cells in tumors, and inhibited tumor angiogenesis. Similarly, D-Nap-GFFY-T317 more potently inhibited growth of urethane-induced lung carcinomas than T317 oral administration. In these two tumor models, T317 oral administration, but not D-Nap-GFFY-T317 injection, activated hepatic lipogenesis and induced fatty liver. Conclusion: Our study demonstrates that D-Nap-GFFY-T317 inhibits lung tumor growth without adverse effects on the liver, indicating the hydrogel-encapsulated LXR ligand might be a novel therapy for tumor treatment.

Low Molecular Weight Fucoidan Can Inhibit the Fibrosis of Diabetic Kidneys by Regulating the Kidney Lipid Metabolism

In this study, a diabetic kidney disease model was established by placing the test rats on a high-sugar/high-fat diet combined with streptozotocin induction. Histopathological examination (H&E, Masson, and PASM stain) showed pathological changes in the diabetic rat kidneys, in addition to fibrotic symptoms and collagen deposition. Immunohistochemistry and western blot analyses indicated that the diabetic condition significantly increased the expressions of fibrotic markers including collagen, α-SMA, and fibronectin. The levels of cholesterol, triglyceride, and low-density lipoprotein were also increased in diabetic kidney disease (DKD) rat blood, while the level of high-density lipoprotein was decreased. The results of Oil red O staining experiments indicated that the kidneys of diabetic rats exhibited appreciable fat deposition, with high contents of triglyceride and cholesterol. To inhibit fibrosis and reduce fat deposition, low molecular weight fucoidan (LMWF) may be used. Based on PCR and western blot analyses, LMWF can regulate the expression levels of important lipid metabolism regulators, thereby impeding the development of kidney fibrosis. Through the vitro model, it also be indicated that LMWF could inhibit fibrosis process through regulating lipid metabolism which induced by palmitic acid.

Walnut Consumption Induces Tissue-Specific Omega-6/Omega-3 Decrease in High-Fructose-Fed Wistar Rats

Increased dietary, blood, and tissue n-6/n-3 fatty acid ratios are associated with obesity and metabolic syndrome. Due to Westernized dietary patterns, the increasing n-6/n-3 ratio is of growing concern worldwide, and dietary strategies aimed at its lowering are of public health importance. Walnuts are rich in dietary fats, and their consumption promotes cardiometabolic health. This study aimed to examine the effect of 6-week walnut consumption on tissue-specific n-6/n-3 ratio and fatty acid metabolic conversion in fructose-fed rats with a cluster of metabolic disorders. Male Wistar rats were fed a standard diet with or without 10% fructose in drinking water for 9 weeks. Diets of half of the animals were then supplemented with walnuts (2.4 g/day) for 6 weeks, upon which fatty acid profiles were determined in plasma, liver, adipose tissue, and kidney total lipids. Results showed that walnuts induced significant decreases in the n-6/n-3 content of total lipid pool in plasma and examined tissues, irrespective of metabolic burden. Walnut intervention decreased plasma and liver palmitoleic/palmitic, arachidonic/linoleic, and docosahexaenoic/α-linolenic acid ratios. It also modulated individual fatty acid levels by reducing arachidonic and palmitic acid and increasing α-linolenic, eicosapentaenoic, and docosapentaenoic acid in plasma and most tissues. Our study demonstrated that 6-week consumption of walnuts favorably modulated n-6/n-3 plasma and tissue ratio in male Wistar rats regardless of high-fructose feeding, underscoring the promising potential of walnuts in both prevention and treatment of the metabolic syndrome.

Current understanding of periodontal disease pathogenesis and targets for host-modulation therapy

Recent advances indicate that periodontitis is driven by reciprocally reinforced interactions between a dysbiotic microbiome and dysregulated inflammation. Inflammation is not only a consequence of dysbiosis but, via mediating tissue dysfunction and damage, fuels further growth of selectively dysbiotic communities of bacteria (inflammophiles), thereby generating a self-sustained feed-forward loop that perpetuates the disease. These considerations provide a strong rationale for developing adjunctive host-modulation therapies for the treatment of periodontitis. Such host-modulation approaches aim to inhibit harmful inflammation and promote its resolution or to interfere directly with downstream effectors of connective tissue and bone destruction. This paper reviews diverse strategies targeted to modulate the host periodontal response and discusses their mechanisms of action, perceived safety, and potential for clinical application.

Brothers in Arms: ABCA1- and ABCG1-Mediated Cholesterol Efflux as Promising Targets in Cardiovascular Disease Treatment

Atherosclerosis is a leading cause of cardiovascular disease worldwide, and hypercholesterolemia is a major risk factor. Preventive treatments mainly focus on the effective reduction of low-density lipoprotein cholesterol, but their therapeutic value is limited by the inability to completely normalize atherosclerotic risk, probably due to the disease complexity and multifactorial pathogenesis. Consequently, high-density lipoprotein cholesterol gained much interest, as it appeared to be cardioprotective due to its major role in reverse cholesterol transport (RCT). RCT facilitates removal of cholesterol from peripheral tissues, including atherosclerotic plaques, and its subsequent hepatic clearance into bile. Therefore, RCT is expected to limit plaque formation and progression. Cellular cholesterol efflux is initiated and propagated by the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Their expression and function are expected to be rate-limiting for cholesterol efflux, which makes them interesting targets to stimulate RCT and lower atherosclerotic risk. This systematic review discusses the molecular mechanisms relevant for RCT and ABCA1 and ABCG1 function, followed by a critical overview of potential pharmacological strategies with small molecules to enhance cellular cholesterol efflux and RCT. These strategies include regulation of ABCA1 and ABCG1 expression, degradation, and mRNA stability. Various small molecules have been demonstrated to increase RCT, but the underlying mechanisms are often not completely understood and are rather unspecific, potentially causing adverse effects. Better understanding of these mechanisms could enable the development of safer drugs to increase RCT and provide more insight into its relation with atherosclerotic risk. SIGNIFICANCE STATEMENT: Hypercholesterolemia is an important risk factor of atherosclerosis, which is a leading pathological mechanism underlying cardiovascular disease. Cholesterol is removed from atherosclerotic plaques and subsequently cleared by the liver into bile. This transport is mediated by high-density lipoprotein particles, to which cholesterol is transferred via ATP-binding cassette transporters ABCA1 and ABCG1. Small-molecule pharmacological strategies stimulating these transporters may provide promising options for cardiovascular disease treatment.

Sea buckthorn (Hippophae rhamnoides L.) oil enhances proliferation, adipocytes differentiation and insulin sensitivity in 3T3-L1 cells

The objective of this study is to investigate the effects of sea buckthorn oil (SBO) on proliferation, adipogenic differentiation and insulin sensitivity of 3T3-L1 cells. Results showed that SBO increased cell proliferation ability, accompanied by up-regulated proliferating cell nuclear antigen content (p < 0.05) and p38 activity (p < 0.05). SBO also promoted adipogenesis and enhanced adipogenic transcriptional factors expression. Mitochondrial biogenesis related gene expressions were elevated in SBO treated cells (p < 0.05). Of note, SBO also increased glucose uptake and glucose transporter 4 abundance (p < 0.05). Cells treated with SBO exhibited greater phosphorylated insulin receptor substrate 1 (p < 0.05), phosphorylated-Akt (p < 0.05) and phosphorylated AMP-activated protein kinase (p < 0.01) contents. When taken together, these results suggest that SBO promotes 3T3-L1 cells proliferation, adipogenesis and insulin sensitivity.

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorononanoic acid (PFNA) increase triglyceride levels and decrease cholesterogenic gene expression in human HepaRG liver cells

Per- and polyfluoroalkyl substances (PFASs) are omnipresent in the environment, food chain, and humans. Epidemiological studies have shown a positive association between serum levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), and increased serum cholesterol and, in some cases, also triglyceride levels. However, causality has been questioned, as animal studies, as well as a human trial, showed a decrease in serum cholesterol and no effects or a decrease in plasma triglycerides. To obtain more insight into the effects of PFASs on these processes, the present study investigated the effects of PFOA, PFOS, and perfluorononanoic acid (PFNA) on intracellular triglyceride and cholesterol levels in human HepaRG liver cells. DNA microarray analyses were performed to provide insight into underlying mechanisms. All PFASs induced an increase in cellular triglyceride levels, but had no effect on cholesterol levels. Gene set enrichment analysis (GSEA) of the microarray data indicated that gene sets related to cholesterol biosynthesis were repressed by PFOA, PFOS, and PFNA. Other gene sets commonly affected by all PFAS were related to PERK/ATF4 signaling (induced), tRNA amino-acylation (induced), amino acid transport (induced), and glycolysis/gluconeogenesis (repressed). Moreover, numerous target genes of peroxisome proliferator-activated receptor α (PPARα) were found to be upregulated. Altogether, the present study shows that PFOA, PFOS, and PFNA increase triglyceride levels and inhibit cholesterogenic gene expression in HepaRG cells. In addition, the present study indicates that PFASs induce endoplasmic reticulum stress, which may be an important mechanism underlying some of the toxic effects of these chemicals.

Intermittent hypoxia modulates redox homeostasis, lipid metabolism associated inflammatory processes and redox post-translational modifications: Benefits at high altitude

Intermittent hypoxia, initially associated with adverse effects of sleep apnea, has now metamorphosed into a module for improved sports performance. The regimen followed for improved sports performance is milder intermittent hypoxic training (IHT) as compared to chronic and severe intermittent hypoxia observed in sleep apnea. Although several studies have indicated the mechanism and enough data on physiological parameters altered by IH is available, proteome perturbations remain largely unknown. Altitude induced hypobaric hypoxia is known to require acclimatization as it causes systemic redox stress and inflammation in humans. In the present study, a short IHT regimen consisting of previously reported physiologically beneficial FIO2 levels of 13.5% and 12% was administered to human subjects. These subjects were then airlifted to altitude of 3500 m and their plasma proteome along with associated redox parameters were analyzed on days 4 and 7 of high altitude stay. We observed that redox stress and associated post-translational modifications, perturbed lipid metabolism and inflammatory signaling were induced by IHT exposure at Baseline. However, this caused activation of antioxidants, energy homeostasis mechanisms and anti-inflammatory responses during subsequent high-altitude exposure. Thus, we propose IHT as a beneficial non-pharmacological intervention that benefits individuals venturing to high altitude areas.

Intracellular and Intercellular Aspects of Macrophage Immunometabolism in Atherosclerosis

Macrophage immunometabolism, the changes in intracellular metabolic pathways that alter the function of these highly plastic cells, has been the subject of intense interest in the past few years, in part because macrophage immunometabolism plays important roles in atherosclerosis and other inflammatory diseases. In this review article, part of the Compendium on Atherosclerosis, we introduce the concepts of (1) intracellular immunometabolism-the canonical pathways of intrinsic cell activation leading to changes in intracellular metabolism, which in turn alter cellular function; and (2) intercellular immunometabolism-conditions in which intermediates of cellular metabolism are transferred from one cell to another, thereby altering the function of the recipient cell. The recent discovery that the metabolite cargo of dead and dying cells ingested through efferocytosis by macrophages can alter metabolic pathways and downstream function of the efferocyte is markedly changing the way we think about macrophage immunometabolism. Metabolic transitions of macrophages contribute to their functions in all stages of atherosclerosis, from lesion initiation to formation of advanced lesions characterized by necrotic cores, to lesion regression following aggressive lipid lowering. This review article discusses recent advances in our understanding of these different aspects of macrophage immunometabolism in atherosclerosis. With the increasing understanding of the roles of macrophage immunometabolism in atherosclerosis, new exciting concepts and potential targets for intervention are emerging.

n-3 PUFA reduction caused by fabp2 deletion interferes with triacylglycerol metabolism and cholesterolhomeostasis in fish

Fatty acid-binding protein 2 (Fabp2), which is involved in the transport of long-chain fatty acids, is widely studied in mammals. Nevertheless, the role of this protein in teleost fish is mostly unknown. Here, we produced a fabp2^-/- zebrafish (KO) animal model. Compared with wild-type zebrafish (WT), KO had a markedly decreased content of intestinal n-3 poly-unsaturated fatty acids (n-3 PUFAs) and increased levels of intestinal, hepatic, and serum triacylglycerols (TAG). The intestinal transcriptome analysis of KO and WT revealed an obviously disrupted TAG metabolism and up-regulated bile secretion in KO. Expression levels of the genes related to fatty acid transport and cholesterol (CL) absorption in the intestine of KO were significantly lower than those of WT, while the expression levels of genes related to intestinal TAG synthesis and hepatic CL synthesis were in the opposite direction. To confirm these findings, we further established fabp2 transgenic zebrafish (TG). Compared with WT, TG had a markedly increased content of intestinal n-3 PUFAs, a significantly decreased level of hepatic TAG, and significantly higher expression of genes related to fatty acid transport and CL absorption in the intestine. In conclusion, this study suggests that teleost fish fabp2 could promote intestinal n-3 PUFA absorption to mediate TAG synthesis and CL homeostasis, by regulating the genes involved in lipid metabolism.

Targeting PPAR ligands as possible approaches for metabolic reprogramming of T cells in cancer immunotherapy

Despite the prominent progress in understanding cancer immunosurveillance mechanisms, there are some types of problems which have been identified to hinder effective and successful immunotherapy of cancers. Such problems have been ascribed to the tumor abilities in the creation of a tolerant milieu that can impair immune responses against cancer cells. In the present study, we represent possible approaches for metabolic reprogramming of T cells in cancer immunotherapy to overcome tumor metabolic impositions on immune responses against cancer cells. Metabolic suppression of effector immune cells in tumor milieu is one of the important strategies recruited by tumor cells to escape from immunogenic cell death. We have investigated the metabolic reprogramming of T cells as a method and a possible new target for cancer immunotherapy. Synergic effects of PPAR ligands in immunotherapy of cancers on the metabolic reprogramming of T cells have been noticed by several studies as a new target of cancer immunotherapy. The current wealth of data like this promises a future scenario which the consideration of metabolic restriction in the tumor microenvironment and administration of therapeutic agents such as PPAR ligands to overcome metabolic restrictions on T cells (refreshing their functionality) may be effective and enhance the accountability and efficacy of cancer immunotherapy.

Action of low doses of Aspirin in Inflammation and Oxidative Stress induced by aβ1-42 on Astrocytes in primary culture

Aspirin has been used as anti-inflammatory and anti-aggregate for decades but the precise mechanism(s) of action after the presence of the toxic peptide Aβ_1-42 in cultured astrocytes remains poorly resolved. Here we use low-doses of aspirin (10^-7 M) in astrocytes in primary culture in presence or absence of Aβ_1-42 toxic peptide. We noted an increase of cell viability and proliferation with or without Aβ_1-42 peptide presence in aspirin treated cells. In addition, a decrease in apoptosis, determined by Caspase 3 activity and the expression of Cyt c and Smac/Diablo, were detected. Also, aspirin diminished necrosis process (LDH levels), pro-inflammatory mediators (IL-β and TNF-α) and NF-ᴋB protein expression, increasing anti-inflammatory PPAR-γ protein expression, preventing Aβ_1-42 toxic effects. Aspirin inhibited COX-2 and iNOS without changes in COX-1 expression, increasing anti-oxidant protein (Cu/Zn-SOD and Mn-SOD) expression in presence or absence of Aβ_1-42. Taken together, our results show that aspirin, at low doses increases cell viability by decreasing inflammation and oxidative stress, preventing the deleterious effects of the Aβ_1-42 peptide on astrocytes in primary culture. The use of low doses of aspirin may be more suitable for Alzheimer's disease.

Stigmasterol stimulates transintestinal cholesterol excretion independent of liver X receptor activation in the small intestine

Despite advances in healthcare, cardiovascular disease (CVD) remains the leading cause of death in the United States. Elevated levels of plasma cholesterol are highly predictive of CVD and stroke and are the principal driver of atherosclerosis. Unfortunately, current cholesterol lowering agents, such as statins, are not known to reverse atherosclerotic disease once it has been established. In preclinical models, agonists of nuclear receptor, LXR, have been shown to reduce and reverse atherosclerosis. Phytosterols are bioactive non-cholesterol sterols that act as LXR agonists and regulate cholesterol metabolism and transport. We hypothesized that stigmasterol would act as an LXR agonist and alter intestinal cholesterol secretion to promote cholesterol elimination. Mice were fed a control diet, or a diet supplemented with stigmasterol (0.3% w/w) or T0901317 (0.015% w/w), a known LXR agonist. In this experiment we analyzed the sterol content of bile, intestinal perfusate, plasma, and feces. Additionally, the liver and small intestine were analyzed for relative levels of transcripts known to be regulated by LXR. We observed that T0901317 robustly promoted cholesterol elimination and acted as a strong LXR agonist. Stigmasterol promoted transintestinal cholesterol secretion through an LXR-independent pathway.

Current Challenges in Understanding the Cellular and Molecular Mechanisms in Niemann-Pick Disease Type C1

Rare diseases are a heterogeneous group of very different clinical syndromes. Their most common causes are defects in the hereditary material, and they can therefore be passed on to descendants. Rare diseases become manifest in almost all organs and often have a systemic expressivity, i.e., they affect several organs simultaneously. An effective causal therapy is often not available and can only be developed when the underlying causes of the disease are understood. In this review, we focus on Niemann–Pick disease type C1 (NPC1), which is a rare lipid-storage disorder. Lipids, in particular phospholipids, are a major component of the cell membrane and play important roles in cellular functions, such as extracellular receptor signaling, intracellular second messengers and cellular pressure regulation. An excessive storage of fats, as seen in NPC1, can cause permanent damage to cells and tissues in the brain and peripheral nervous system, but also in other parts of the body. Here, we summarize the impact of NPC1 pathology on several organ systems, as revealed in experimental animal models and humans, and give an overview of current available treatment options.

A Functional Virgin Olive Oil Enriched with Olive Oil and Thyme Phenolic Compounds Improves the Expression of Cholesterol Efflux-Related Genes: A Randomized, Crossover, Controlled Trial

The consumption of antioxidant-rich foods such as virgin olive oil (VOO) promotes high-density lipoprotein (HDL) anti-atherogenic capacities. Intake of functional VOOs (enriched with olive/thyme phenolic compounds (PCs)) also improves HDL functions, but the gene expression changes behind these benefits are not fully understood. Our aim was to determine whether these functional VOOs could enhance the expression of cholesterol efflux-related genes. In a randomized, double-blind, crossover, controlled trial, 22 hypercholesterolemic subjects ingested for three weeks 25 mL/day of: (1) a functional VOO enriched with olive oil PCs (500 mg/kg); (2) a functional VOO enriched with olive oil (250 mg/kg) and thyme PCs (250 mg/kg; FVOOT), and; (3) a natural VOO (olive oil PCs: 80 mg/kg, control intervention). We assessed whether these interventions improved the expression of cholesterol efflux-related genes in peripheral blood mononuclear cells by quantitative reverse-transcription polymerase chain reactions. The FVOOT intervention upregulated the expression of CYP27A1 (p = 0.041 and p = 0.053, versus baseline and the control intervention, respectively), CAV1 (p = 0.070, versus the control intervention), and LXRβ, RXRα, and PPARβ/δ (p = 0.005, p = 0.005, and p = 0.038, respectively, relative to the baseline). The consumption of a functional VOO enriched with olive oil and thyme PCs enhanced the expression of key cholesterol efflux regulators, such as CYP27A1 and nuclear receptor-related genes.

Coffee prevents fatty liver disease induced by a high-fat diet by modulating pathways of the gut-liver axis

Coffee consumption is inversely associated with the risk of non-alcoholic fatty liver disease (NAFLD). A gap in the literature still exists concerning the intestinal mechanisms that are involved in the protective effect of coffee consumption towards NAFLD. In this study, twenty-four C57BL/6J mice were divided into three groups each receiving a standard diet, a high-fat diet (HFD) or an HFD plus decaffeinated coffee (HFD+COFFEE) for 12 weeks. Coffee supplementation reduced HFD-induced liver macrovesicular steatosis (P < 0·01) and serum cholesterol (P < 0·001), alanine aminotransferase and glucose (P < 0·05). Accordingly, liver PPAR- α (P < 0·05) and acyl-CoA oxidase-1 (P < 0·05) as well as duodenal ATP-binding cassette (ABC) subfamily A1 (ABCA1) and subfamily G1 (ABCG1) (P < 0·05) mRNA expressions increased with coffee consumption. Compared with HFD animals, HFD+COFFEE mice had more undigested lipids in the caecal content and higher free fatty acid receptor-1 mRNA expression in the duodenum and colon. Furthermore, they showed an up-regulation of duodenal and colonic zonulin-1 (P < 0·05), duodenal claudin (P < 0·05) and duodenal peptide YY (P < 0·05) mRNA as well as a higher abundance of Alcaligenaceae in the faeces (P < 0·05). HFD+COFFEE mice had an energy intake comparable with HFD-fed mice but starting from the eighth intervention week they gained significantly less weight over time. Data altogether showed that coffee supplementation prevented HFD-induced NAFLD in mice by reducing hepatic fat deposition and metabolic derangement through modification of pathways underpinning liver fat oxidation, intestinal cholesterol efflux, energy metabolism and gut permeability. The hepatic and metabolic benefits induced by coffee were accompanied by changes in the gut microbiota.

The Antagonist Effect of Arachidonic Acid on GLUT4 Gene Expression by Nuclear Receptor Type II Regulation

OBJECTIVES

Obesity is a complex disease that has a strong association with diet and lifestyle. Dietary factors can influence the expression of key genes connected to insulin resistance, lipid metabolism, and adipose tissue composition. In this study, our objective was to determine gene expression and fatty acid (FA) profiles in visceral adipose tissue (VAT) from lean and morbidly obese individuals. We also aimed to study the agonist effect of dietary factors on glucose metabolism.

DESIGN AND METHODS

Lean and low and high insulin resistance morbidly obese subjects (LIR-MO and HIR-MO) were included in this study. The gene expression of liver X receptor type alpha (LXR-α) and glucose transporter type 4 (GLUT4) and the FA profiles in VAT were determined. Additionally, the in vivo and in vitro agonist effects of oleic acid (OA), linoleic acid (LA), and arachidonic acid (AA) by peroxisome proliferator-activated receptor type gamma 2 (PPAR-γ2) on the activity of GLUT4 were studied.

RESULTS

Our results showed a dysregulation of GLUT4 and LXR-α in VAT of morbidly obese subjects. In addition, a specific FA profile for morbidly obese individuals was found. Finally, AA was an PPAR-γ2 agonist that activates the expression of GLUT4.

CONCLUSIONS

Our study suggests a dysregulation of LXR-α and GLUT4 expression in VAT of morbidly obese individuals. FA profiles in VAT could elucidate their possible role in lipolysis and adipogenesis. Finally, AA binds to PPAR-γ2 to activate the expression of GLUT4 in the HepG2 cell line, showing an alternative insulin-independent activation of GLUT4.

Suppression of abdominal fat and anti-hyperlipidemic potential of Emblica officinalis: Upregulation of PPARs and identification of active moiety

Since ancient time, Emblica officinalis (E. officinalis) is being used for the management of various ailments. Phytochemical analysis proves that fruit juice of E. officinalis contains high amount gallic acid, which could be responsible for medicinal potentials. Hence in this study, gallic acid and fruit juice of E. officinalis were evaluated for anti-hyperlipidemic potential in various experimental animal models. Experimentally, hyperlipidemia was induced through administration of poloxamer-407, tyloxapol and high-fat-diet supplement in rats. Treatment with gallic acid as well as fruit juice of E. officinalis decreased plasma cholesterol and reduced oil infiltration in liver and aorta. Mechanistically, E. officinalis increased peroxisome proliferator-activated receptors-α (PPARα) expression and increased activity of lipid oxidation through carnitine palmitoyl transferase (CPT) along with decreased activity of hepatic lipogenic enzymes i.e. glucose-6-phosphate dehydrogenase (G6PD), fatty acid synthase (FAS) and malic enzyme (ME). Additionally, E. officinalis increased cholesterol uptake through increased LDL-receptor expressions on hepatocytes and decreased LDL-receptor degradation due to decreased proprotein convertase subtilisin/kexin type 9 (PCSK9) expression. Simultaneously, E. officinalis showed ability to restore glucose homeostasis through increased Glut4 and PPARγ protein expression in adipose tissue. These findings exposed central role of gallic acid in E. officinalis arbitrated anti-hyperlipidemic action through upregulation of PPARs, Glut4 and lipogenic enzymes, and decreased expression of PCSK9 and lipogenic enzymes. Findings from this experiment demonstrated that E. officinalis is a potential therapy for management of hyperlipidemia and gallic acid could be a potential lead candidate.

PPAR𝛾 Gene and Atherosclerosis: Genetic Polymorphisms, Epigenetics and Therapeutic Implications

Atherosclerosis is the leading cause of mortality and morbidity in the developed world. It is characterized by the formation of a plaque in the walls of middle and large arteries leading to macrovascular complications. Several risk factors are included, with diabetes being one of the most important for the onset and development of atherosclerosis. Due to an increase in the prevalence of diabetes in the world, the incidence of diabetic complications (microvascular and macrovascular) is increasing. Peroxisome proliferator-activated receptor γ (PPARγ) plays a important role in atherosclerotic processes. Peroxisome proliferator activated receptor γ belongs to the superfamily of nuclear receptors, has a great presence in fat tissue, macrophages, and regulates gene expression and most of the processes that lead to the onset and development of atherosclerosis. In this review, we discuss the basic patho-physiological mechanisms of atherosclerosis in type 2 diabetes mellitus (T2DM). Furthermore, we discuss the impact of PPARγ polymorphisms, and the epigenetic mechanisms affecting the onset of atherosclerosis, i.e, DNA methylation and demethylation, histone acetylation and deacetylation, and RNA-based mechanisms. Moreover, we add therapeutic possibilities for acting on epigenetic mechanisms in order to prevent the onset and progression of atherosclerosis.

Proteo-metabolomics reveals compensation between ischemic and non-injured contralateral kidneys after reperfusion

Ischaemia and reperfusion injury (IRI) is the leading cause of acute kidney injury (AKI), which contributes to high morbidity and mortality rates in a wide range of injuries as well as the development of chronic kidney disease. The cellular and molecular responses of the kidney to IRI are complex and not fully understood. Here, we used an integrated proteomic and metabolomic approach to investigate the effects of IRI on protein abundance and metabolite levels. Rat kidneys were subjected to 45 min of warm ischaemia followed by 4 h and 24 h reperfusion, with contralateral and separate healthy kidneys serving as controls. Kidney tissue proteomics after IRI revealed elevated proteins belonging to the acute phase response, coagulation and complement pathways, and fatty acid (FA) signalling. Metabolic changes were already evident after 4 h reperfusion and showed increased level of glycolysis, lipids and FAs, whilst mitochondrial function and ATP production was impaired after 24 h. This deficit was partially compensated for by the contralateral kidney. Such a metabolic balance counteracts for the developing energy deficit due to reduced mitochondrial function in the injured kidney.