Epoxyeicosatrienoic Acids and Fibrosis: Recent Insights for the Novel Therapeutic Strategies

Multi-omics study reveals Shuangshen Pingfei formula regulates EETs metabolic reprogramming to exert its therapeutic effect on pulmonary fibrosis

As a clinical formula derived from Renshen Pingfei San, Shuangshen Pingfei formula (SSPF) has been used to treat pulmonary fibrosis (PF). However, its in-depth mechanism of action remains unknown. In this study, the effect of SSPF was evaluated by applying a rat model of PF caused by intratracheal drip bleomycin. To characterize the molecular changes related to PF and reveal therapeutic targets for SSPF, we performed transcriptomic and metabolomic analyses on rat lung. Finally, western blotting and qPCR experiments were used to validate the multi-omics results. As a result, a significant reduction in inflammation and fibrosis caused by BLM was observed when SSPF was administered. Widespread changes in gene expression and metabolic programming were observed in the lungs of PF rats through RNA-seq and untargeted metabolomic analysis. Combined transcriptomic and metabolomic analyses revealed the involvement of arachidonic acid (AA) metabolism pathways in PF. Further validation of AA metabolite synthase genes and protein levels showed a significant decrease in the levels of epoxyeicosatrienoic acids (EETs) synthases, including Cyp2j2, Cyp2b1, in the PF lungs. SSPF treatment regulated the above changes in gene expression and metabolic programming, particularly the regulation of EETs. This study is the first to investigate the mechanism of action of SSPF in the treatment of PF from the perspective of regulating the synthesis of EETs in AA metabolism.

Isoastragaloside I attenuates cholestatic liver diseases by ameliorating liver injury, regulating bile acid metabolism and restoring intestinal barrier

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestatic liver diseases (CLD) are liver disorders resulting from abnormal bile formation, secretion, and excretion from various causes. Due to the lack of suitable and safe medications, liver transplantation is the ultimate treatment for CLD patients. Isoastragaloside I (IAS I) is one of the main saponin found in Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao or Astragalus membranaceus (Fisch.) Bge, which has been demonstrated to obviously alleviate CLD. Nevertheless, the IAS I's specific anti-CLD mechanism remains undecipherable.

AIM OF THE STUDY

This study's purpose was to elucidate the protective consequence of IAS I on 0.1% 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) diet-induced CLD mice, and to reveal its potential mechanism.

MATERIALS AND METHODS

In this study, mice with CLD that had been fed a 0.1% DDC diet were distributed two doses of IAS I (20 mg/kg, 50 mg/kg). The effects of IAS I on CLD models were investigated by assessing blood biochemistry, liver histology, and Hyp concentrations. We investigated markers of liver fibrosis and ductular reaction using immunohistochemistry, Western blot, and qRT-PCR. Liver inflammation indicators, arachidonic acid (ARA), and ω-3 fatty acid (FA) metabolites were also analyzed. Quantitative determination of 39 bile acids (BAs) in different organs employing UHPLC-Q-Exactive Orbitrap HRMS technology. Additionally, the H&E and Western blot analysis were used to evaluate differences in intestinal barrier function in DDC-induced mice before and after administering IAS I.

RESULTS

After treatment with IAS I, serum biochemical indicators and liver hydroxyproline (Hyp) increased in a dose-dependent manner in CLD mice. The IAS I group showed significant improvement in indicators of liver fibrosis and ductular response, including as α-smooth muscle actin (α-SMA) and cytokeratin 19 (CK19), and transforming growth factor-β (TGF-β)/Smads signaling pathway. And inflammatory factors: F4/80, tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), ARA and ω-3 FA metabolites showed significant improvement following IAS I treatment. Moreover, IAS I significantly ameliorated liver tau-BAs levels, particularly TCA, THCA, THDCA, TCDCA, and TDCA contents, which were associated with enhanced expression of hepatic farnesoid X receptor (FXR), small heterodimer partner (SHP), cholesterol 7α-hydroxylase (Cyp7a1), and bile-salt export pump (BSEP). Furthermore, IAS I significantly improved pathological changes and protein expression related to intestinal barrier function, including zonula occludens protein 1 (ZO-1), Muc2, and Occludin.

CONCLUSIONS

IAS I alleviated cholestatic liver injury, relieved inflammation, improved the altered tau-BAs metabolism and restored intestinal barrier function to protect against DDC-induced cholestatic liver diseases.

Long-chain polyunsaturated fatty acid-containing phosphatidylcholines predict survival rate in patients after heart failure

Background

Heart failure (HF) is becoming an increasingly prevalent issue, particularly among the elderly population. Lipids are closely associated with cardiovascular disease (CVD) pathology. Lipidomics as a comprehensive profiling tool is showing to be promising in the prediction of events and mortality due to CVD as well as identifying novel biomarkers.

Materials and methods

In this study, eicosanoids and lipid profiles were measured in order to predict survival in patients with de novo or acute decompensated HF. Our study included 50 patients (16 females, mean age 73 years and 34 males, mean age 71 years) with de novo or acute decompensated chronic HF with a median follow-up of 7 months. Lipids were semiquantified using targeted lipidomic liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Eicosanoid concentrations were determined using a commercially available sandwich ELISA assay.

Results

From 736 lipids and 3 eicosanoids, 39 significant lipids were selected (by using the Mann-Whitney U test after Benjamini-Hochberg correction) with the highest number of representatives belonging to the polyunsaturated (PUFA) phosphatidylcholines (PC). PC 42:10 (p = 1.44 × 10-4) was found to be the most statistically significantly elevated in the surviving group with receiver operating characteristics of AUC = 0.84 (p = 3.24 × 10-7). A multivariate supervised discriminant analysis based on the aforementioned lipid panel enabled the classification of the groups of surviving and non-surviving patients with 90 % accuracy.

Conclusions

In the present study we describe a trend in PUFA esterified in PC that were systematically increased in surviving patients with HF. This trend in low-abundant and rarely identified PUFA PC (mainly very long chain PUFA containing PC such as PC 42:10 or PC 40:9 containing FA 22:6, FA 20:5 and FA 20:4) suggests candidate biomarkers.

Impact of soluble epoxide hydrolase inhibition on silica-induced pulmonary fibrosis, ectopic lymphoid neogenesis, and autoantibody production in lupus-prone mice

OBJECTIVE

Acute intranasal (IN) instillation of lupus-prone NZBWF1 mice with crystalline silica (cSiO2) triggers robust lung inflammation that drives autoimmunity. Prior studies in other preclinical models show that soluble epoxide hydrolase (sEH) inhibition upregulates pro-resolving lipid metabolites that are protective against pulmonary inflammation. Herein, we assessed in NZBWF1 mice how acute IN cSiO2 exposure with or without the selective sEH inhibitor TPPU influences lipidomic, transcriptomic, proteomic, and histopathological biomarkers of inflammation, fibrosis, and autoimmunity.

METHODS

Female 6-week-old NZBWF1 mice were fed control or TPPU-supplemented diets for 2 weeks then IN instilled with 2.5 mg cSiO2 or saline vehicle. Cohorts were terminated at 7 or 28 days post-cSiO2 instillation (PI) and lungs analyzed for prostaglandins, cytokines/chemokines, gene expression, differential cell counts, histopathology, and autoantibodies.

RESULTS

cSiO2-treatment induced prostaglandins, cytokines/chemokine, proinflammatory gene expression, CD206+ monocytes, Ly6B.2+ neutrophils, CD3+ T cells, CD45R+ B cells, centriacinar inflammation, collagen deposition, ectopic lymphoid structure neogenesis, and autoantibodies. While TPPU effectively inhibited sEH as reflected by skewed lipidomic profile in lung and decreased cSiO2-induced monocytes, neutrophils, and lymphocytes in lung lavage fluid, it did not significantly impact other biomarkers.

DISCUSSION

cSiO2 evoked robust pulmonary inflammation and fibrosis in NZBWF1 mice that was evident at 7 days PI and progressed to ELS development and autoimmunity by 28 days PI. sEH inhibition by TPPU modestly suppressed cSiO2-induced cellularity changes and pulmonary fibrosis. However, TPPU did not affect ELS formation or autoantibody responses, suggesting sEH minimally impacts cSiO2-triggered lung inflammation, fibrosis, and early autoimmunity in our model.

Ginsenoside Rk3 Ameliorates Obesity-Induced Colitis by Modulating Lipid Metabolism in C57BL/6 Mice

Lipid metabolism is closely related to obesity and its complications. Our previous study found that ginsenoside Rk3 (Rk3), a natural bioactive substance derived from ginseng, can effectively alleviate obesity-induced colitis, while its impact on the improvement of the lipid metabolism disorder remains unclear. Here, we demonstrated that Rk3 significantly alleviated inflammation, oxidative stress, and lipid dysregulation in high-fat diet-induced colitis C57BL/6 mice. The potential mechanism by which Rk3 mitigated colon inflammation in the context of obesity may involve the modulation of polyunsaturated fatty acid metabolism with specific attention to n-6 fatty acids, linoleic acid, and arachidonic acid. Rk3 intervention markedly reduced the production of pro-inflammatory factors (PGE2, PGD2, TXB2, HETE, and HODE) by inhibiting cyclooxygenase and lipoxygenase pathways, while enhancing the production of anti-inflammatory factors (EET and diHOME) via cytochrome P450 pathways. Our findings suggest that Rk3 is a potential anti-inflammatory natural drug that can improve obesity-induced intestinal inflammation by regulating lipid metabolism.

DEAD-Box Helicase 17 exacerbates non-alcoholic steatohepatitis via transcriptional repression of cyp2c29, inducing hepatic lipid metabolism disorder and eliciting the activation of M1 macrophages

OBJECTIVE

Our study was to elucidate the role of RNA helicase DEAD-Box Helicase 17 (DDX17) in NAFLD and to explore its underlying mechanisms.

METHODS

We created hepatocyte-specific Ddx17-deficient mice aim to investigate the impact of Ddx17 on NAFLD induced by a high-fat diet (HFD) as well as methionine and choline-deficient l-amino acid diet (MCD) in adult male mice. RNA-seq and lipidomic analyses were conducted to depict the metabolic landscape, and CUT&Tag combined with chromatin immunoprecipitation (ChIP) and luciferase reporter assays were conducted.

RESULTS

In this work, we observed a notable increase in DDX17 expression in the livers of patients with NASH and in murine models of NASH induced by HFD or MCD. After introducing lentiviruses into hepatocyte L02 for DDX17 knockdown or overexpression, we found that lipid accumulation induced by palmitic acid/oleic acid (PAOA) in L02 cells was noticeably weakened by DDX17 knockdown but augmented by DDX17 overexpression. Furthermore, hepatocyte-specific DDX17 knockout significantly alleviated hepatic steatosis, inflammatory response and fibrosis in mice after the administration of MCD and HFD. Mechanistically, our analysis of RNA-seq and CUT&Tag results combined with ChIP and luciferase reporter assays indicated that DDX17 transcriptionally represses Cyp2c29 gene expression by cooperating with CCCTC binding factor (CTCF) and DEAD-Box Helicase 5 (DDX5). Using absolute quantitative lipidomics analysis, we identified a hepatocyte-specific DDX17 deficiency that decreased lipid accumulation and altered lipid composition in the livers of mice after MCD administration. Based on the RNA-seq analysis, our findings suggest that DDX17 could potentially have an impact on the modulation of lipid metabolism and the activation of M1 macrophages in murine NASH models.

CONCLUSION

These results imply that DDX17 is involved in NASH development by promoting lipid accumulation in hepatocytes, inducing the activation of M1 macrophages, subsequent inflammatory responses and fibrosis through the transcriptional repression of Cyp2c29 in mice. Therefore, DDX17 holds promise as a potential drug target for the treatment of NASH.

Epoxyeicosatrienoic acids alleviate alveolar epithelial cell senescence by inhibiting mitophagy through NOX4/Nrf2 pathway

Alveolar epithelial cell (AEC) senescence is considered to be a universal pathological feature of many chronic pulmonary diseases. Our previous study found that epoxyeicosatrienoic acids (EETs), produced from arachidonic acid (ARA) through the cytochrome P450 cyclooxygenase (CYP) pathway, have significant negative regulatory effects on cellular senescence in AECs. However, the exact mechanisms by which EETs alleviate the senescence of AECs still need to be further explored. In the present study, we observed that bleomycin (BLM) induced enhanced mitophagy accompanied by increased mitochondrial ROS (mito-ROS) content in the murine alveolar epithelial cell line MLE12. While EETs reduced BLM-induced mitophagy and mito-ROS content in MLE12 cells, and the mechanism was related to the regulation of NOX4/Nrf2-mediated redox imbalance. Furthermore, we found that inhibition of EETs degradation could significantly inhibit mitophagy and regulate NOX4/Nrf2 balance to exert anti-oxidant effects in D-galactose-induced premature aging mice. Collectively, these findings may provide new ideas for treating age-related pulmonary diseases by targeting EETs to improve mitochondrial dysfunction and reduce oxidative stress.

Dynamic alterations in metabolomics and transcriptomics associated with intestinal fibrosis in a 2,4,6-trinitrobenzene sulfonic acid-induced murine model

BACKGROUND & AIMS

Intestinal fibrosis is a common and severe complication of inflammatory bowel disease without clear pathogenesis. Abnormal expression of host genes and metabolic perturbations might associate with the onset of intestinal fibrosis. In this study, we aimed to investigate the relationship between the development of intestinal fibrosis and the dynamic alterations in both fecal metabolites and host gene expression.

METHODS

We induced intestinal fibrosis in a murine model using 2,4,6-trinitrobenzene sulfonic acid (TNBS). TNBS-treated or control mice were sacrificed after 4 and 6 weeks of intervention; alterations in colonic genes and fecal metabolites were determined by transcriptomics and metabolomics, respectively. Differential, tendency, enrichment, and correlation analyses were performed to assess the relationship between host genes and fecal metabolites.

RESULTS

RNA-sequencing analysis revealed that 679 differential genes with enduring changes were mainly enriched in immune response-related signaling pathways and metabolism-related biological processes. Among them, 15 lipid metabolism-related genes were closely related to the development of intestinal fibrosis. Moreover, the fecal metabolic profile was significantly altered during intestinal fibrosis development, especially the lipid metabolites. Particularly, dynamic perturbations in lipids were strongly associated with alterations in lipid metabolism-related genes expression. Additionally, six dynamically altered metabolites might serve as biomarkers to identify colitis-related intestinal fibrosis in the murine model.

CONCLUSIONS

Intestinal fibrosis in colitis mice might be related to dynamic changes in gene expression and metabolites. These findings could provide new insights into the pathogenesis of intestinal fibrosis.

Is there a role for specialized pro-resolving mediators in pulmonary fibrosis?

Pulmonary fibrotic diseases are characterized by proliferation of lung fibroblasts and myofibroblasts and excessive deposition of extracellular matrix proteins. Depending on the specific form of lung fibrosis, there can be progressive scarring of the lung, leading in some cases to respiratory failure and/or death. Recent and ongoing research has demonstrated that resolution of inflammation is an active process regulated by families of small bioactive lipid mediators termed "specialized pro-resolving mediators." While there are many reports of beneficial effects of SPMs in animal and cell culture models of acute and chronic inflammatory and immune diseases, there have been fewer reports investigating SPMs and fibrosis, especially pulmonary fibrosis. Here, we will review evidence that resolution pathways are impaired in interstitial lung disease, and that SPMs and other similar bioactive lipid mediators can inhibit fibroblast proliferation, myofibroblast differentiation, and accumulation of excess extracellular matrix in cell culture and animal models of pulmonary fibrosis, and we will consider future therapeutic implications of SPMs in fibrosis.

EETs alleviate alveolar epithelial cell senescence by inhibiting endoplasmic reticulum stress through the Trim25/Keap1/Nrf2 axis

Alveolar epithelial cell (AEC) senescence is a key driver of a variety of chronic lung diseases. It remains a challenge how to alleviate AEC senescence and mitigate disease progression. Our study identified a critical role of epoxyeicosatrienoic acids (EETs), downstream metabolites of arachidonic acid (ARA) by cytochrome p450 (CYP), in alleviating AEC senescence. In vitro, we found that 14,15-EET content was significantly decreased in senescent AECs. Exogenous EETs supplementation, overexpression of CYP2J2, or inhibition of EETs degrading enzyme soluble epoxide hydrolase (sEH) to increase EETs alleviated AECs' senescence. Mechanistically, 14,15-EET promoted the expression of Trim25 to ubiquitinate and degrade Keap1 and promoted Nrf2 to enter the nucleus to exert an anti-oxidant effect, thereby inhibiting endoplasmic reticulum stress (ERS) and alleviating AEC senescence. Furthermore, in D-galactose (D-gal)-induced premature aging mouse model, inhibiting the degradation of EETs by Trifluoromethoxyphenyl propionylpiperidin urea (TPPU, an inhibitor of sEH) significantly inhibited the protein expression of p16, p21, and γH2AX. Meanwhile, TPPU reduced the degree of age-related pulmonary fibrosis in mice. Our study has confirmed that EETs are novel anti-senescence substances for AECs, providing new targets for the treatment of chronic lung diseases.

CYP2C19 loss-of-function is associated with increased risk of hypertension in a Hakka population: a case-control study

BACKGROUND

Genetic factors have a certain proportion in the risk factors of hypertension. The purpose was to investigate the relationship of cytochrome P450 2C19 (CYP2C19) polymorphisms with hypertension in Hakka population.

METHODS

The study included 1,872 hypertensive patients and 1,110 controls. The genotypes of CYP2C19 rs4244285 and rs4986893 of all individuals were detected and analyzed.

RESULTS

The genotype and allele distributions of CYP2C19 rs4244285 were significantly different between hypertension group and control group. The CYP2C19 *1/*1 genotype was the most predominant among the subjects (40.8%), followed by the CYP2C19 *1/*2 genotype (40.5%). The percentage of CYP2C19*1, *2, and *3 allele was 64.2%, 30.8%, and 5.0%, respectively. The proportion of intermediate metabolizers (IM) (49.3% vs. 42.9%), poor metabolizers (PM) (14.3% vs. 8.9%) (P < 0.001), and CYP2C19*2 allele (33.8% vs. 25.7%, P < 0.001) in hypertension group was significantly higher than that in control group. Multivariate logistic regression (adjusted for gender, age, smoking, and drinking) indicated that CYP2C19 *1/*2, *1/*3, and *2/*2 genotypes may increase susceptibility to hypertension. And the CYP2C19 IM genotype (IM vs. EM: OR 1.514, 95% CI: 1.291-1.775, P < 0.001), PM genotype (PM vs. EM: OR 2.120, 95% CI: 1.638-2.743, P < 0.001), IM + PM genotypes (IM + PM vs. EM: OR 1.617, 95% CI: 1.390-1.882, P < 0.001) may increase risk of hypertension.

CONCLUSIONS

CYP2C19 loss-of-function (IM, PM genotypes) is independent risk factor for hypertension susceptibility. Specifically, the risk genotypes include CYP2C19 *1/*2, *1/*3, and *2/*2.

Integrated proteomics and metabolomics reveal variations in pulmonary fibrosis development and the potential therapeutic effect of Shuangshen Pingfei formula

ETHNOPHARMACOLOGICAL RELEVANCE

Shuangshen Pingfei formula (SSPF), a Chinese medicine prescription, has been prescribed to alleviate PF. However, little is known about the molecular mechanism underlying PF progression and the regulatory mechanism in SSPF.

AIMS OF THE STUDY

To discriminate the molecular alterations underlying the development of pulmonary fibrosis (PF) and reveal the regulatory mechanism of Shuangshen Pingfei formula (SSPF).

MATERIALS AND METHODS

An integrated analysis of a time-course pathology combined with proteomics and metabolomics was performed to investigate changes in body weight, survival rate, lung coefficient, histopathology, proteins, and metabolites of lung tissues at different time points upon bleomycin (BLM) exposure and SSPF treatment.

RESULTS

The results showed that PF progression was characterized by gradually aggravated fibrosis accompanied by inflammation with extended exposure (7, 14, and 21 days). SSPF significantly attenuated lung fibrosis, as evidenced by increased weight, and reduced lung coefficients and fibrosis scores. Moreover, 368 common differentially expressed proteins (DEPs) were identified, and 102 DEPs were continuously and monotonically upregulated via proteomics among the three BLM treatments. The DEPs were principally involved in extracellular matrix (ECM) remodeling and arginine and proline (AP) metabolic reprogramming. Additionally, metabolomics analyses revealed that BLM exposure mainly affected six metabolism pathways, including 34 differentially regulated metabolites (DRMs). Furthermore, correlation analysis found that several DEPs and DRMs, including L-ornithine, S-adenosyl-L-methionine, ARG, and AOC1, were associated with arginine and proline metabolism, and 8,9-EET, 8,9-DHET, CYP2B, etc., were involved in arachidonic acid (AA) metabolism, suggesting that these two pathways play a critical role in the development of fibrosis. After SSPF treatment, the related protein expression and metabolic disorders were regulated, implying that SSPF provides potential solutions to target these pathways for benefit in the treatment of PF.

CONCLUSION

Our data suggest that ECM remodeling, and metabolic reprogramming of AP and AA are distinctive features of PF development. Simultaneously, we confirmed that SSPF could effectively regulate metabolic disorders, indicating its potential clinical application for PF therapy. Our findings using multiple approaches provide a molecular-scale perspective on the mechanisms of PF progression and the amelioration of SSPF.

Identification of Biomarkers Associated with Heart Failure Caused by Idiopathic Dilated Cardiomyopathy Using WGCNA and Machine Learning Algorithms

Background

The genetic factors and pathogenesis of idiopathic dilated cardiomyopathy-induced heart failure (IDCM-HF) have not been understood thoroughly; there is a lack of specific diagnostic markers and treatment methods for the disease. Hence, we aimed to identify the mechanisms of action at the molecular level and potential molecular markers for this disease.

Methods

Gene expression profiles of IDCM-HF and non-heart failure (NF) specimens were acquired from the database of Gene Expression Omnibus (GEO). We then identified the differentially expressed genes (DEGs) and analyzed their functions and related pathways by using "Metascape". Weighted gene co-expression network analysis (WGCNA) was utilized to search for key module genes. Candidate genes were identified by intersecting the key module genes identified via WGCNA with DEGs and further screened via the support vector machine-recursive feature elimination (SVM-RFE) method and the least absolute shrinkage and selection operator (LASSO) algorithm. At last, the biomarkers were validated and evaluated the diagnostic efficacy by the area under curve (AUC) value and further confirmed the differential expression in the IDCM-HF and NF groups using an external database.

Results

We detected 490 genes exhibiting differential expression between IDCM-HF and NF specimens from the GSE57338 dataset, with most of them being concentrated in the extracellular matrix (ECM) of cells related to biological processes and pathways. After screening, 13 candidate genes were identified. Aquaporin 3 (AQP3) and cytochrome P450 2J2 (CYP2J2) showed high diagnostic efficacy in the GSE57338 and GSE6406 datasets, respectively. In comparison to the NF group, AQP3 was significantly down-regulated in the IDCM-HF group, while CYP2J2 was significantly up-regulated.

Conclusion

As far as we know, this is the first study that combines WGCNA and machine learning algorithms to screen for potential biomarkers of IDCM-HF. Our findings suggest that AQP3 and CYP2J2 could be used as novel diagnostic markers and treatment targets of IDCM-HF.

Depletion of Gut Microbiota Inhibits Hepatic Lipid Accumulation in High-Fat Diet-Fed Mice

Dysregulated lipid metabolism is a key pathology in metabolic diseases and the liver is a critical organ for lipid metabolism. The gut microbiota has been shown to regulate hepatic lipid metabolism in the host. However, the underlying mechanism by which the gut microbiota influences hepatic lipid metabolism has not been elucidated. Here, a gut microbiota depletion mouse model was constructed with an antibiotics cocktail (Abx) to study the mechanism through which intestinal microbiota regulates hepatic lipid metabolism in high-fat diet (HFD)-fed mice. Our results showed that the Abx treatment effectively eradicated the gut microbiota in these mice. Microbiota depletion reduced the body weight and fat deposition both in white adipose tissue and liver. In addition, microbiota depletion reduced serum levels of glucose, total cholesterol (TC), low-density lipoproteins (LDL), insulin, and leptin in HFD-fed mice. Importantly, the depletion of gut microbiota in HFD-fed mice inhibited excessive hepatic lipid accumulation. Mechanistically, RNA-seq results revealed that gut microbiota depletion changed the expression of hepatic genes involved in cholesterol and fatty acid metabolism, such as Cd36, Mogat1, Cyp39a1, Abcc3, and Gpat3. Moreover, gut microbiota depletion reduced the abundance of bacteria associated with abnormal metabolism and inflammation, including Lachnospiraceae, Coriobacteriaceae_UCG-002, Enterorhabdus, Faecalibaculum, and Desulfovibrio. Correlation analysis showed that there was strong association between the altered gut microbiota abundance and the serum cholesterol level. This study indicates that gut microbiota ameliorates HFD-induced hepatic lipid metabolic dysfunction, which might be associated with genes participating in cholesterol and fatty acid metabolism in the liver.

COX-2/sEH Dual Inhibitor Alleviates Hepatocyte Senescence in NAFLD Mice by Restoring Autophagy through Sirt1/PI3K/AKT/mTOR

We previously found that the disorder of soluble epoxide hydrolase (sEH)/cyclooxygenase-2 (COX-2)-mediated arachidonic acid (ARA) metabolism contributes to the pathogenesis of the non-alcoholic fatty liver disease (NAFLD) in mice. However, the exact mechanism has not been elucidated. Accumulating evidence points to the essential role of cellular senescence in NAFLD. Herein, we investigated whether restoring the balance of sEH/COX-2-mediated ARA metabolism attenuated NAFLD via hepatocyte senescence. A promised dual inhibitor of sEH and COX-2, PTUPB, was used in our study to restore the balance of sEH/COX-2-mediated ARA metabolism. In vivo, NAFLD was induced by a high-fat diet (HFD) using C57BL/6J mice. In vitro, mouse hepatocytes (AML12) and mouse hepatic astrocytes (JS1) were used to investigate the effects of PTUPB on palmitic acid (PA)-induced hepatocyte senescence and its mechanism. PTUPB alleviated liver injury, decreased collagen and lipid accumulation, restored glucose tolerance, and reduced hepatic triglyceride levels in HFD-induced NAFLD mice. Importantly, PTUPB significantly reduced the expression of liver senescence-related molecules p16, p53, and p21 in HFD mice. In vitro, the protein levels of γH2AX, p53, p21, COX-2, and sEH were increased in AML12 hepatocytes treated with PA, while Ki67 and PCNA were significantly decreased. PTUPB decreased the lipid content, the number of β-gal positive cells, and the expression of p53, p21, and γH2AX proteins in AML12 cells. Meanwhile, PTUPB reduced the activation of hepatic astrocytes JS1 by slowing the senescence of AML12 cells in a co-culture system. It was further observed that PTUPB enhanced the ratio of autophagy-related protein LC3II/I in AML12 cells, up-regulated the expression of Fundc1 protein, reduced p62 protein, and suppressed hepatocyte senescence. In addition, PTUPB enhanced hepatocyte autophagy by inhibiting the PI3K/AKT/mTOR pathway through Sirt1, contributing to the suppression of senescence. PTUPB inhibits the PI3K/AKT/mTOR pathway through Sirt1, improves autophagy, slows down the senescence of hepatocytes, and alleviates NAFLD.

Changes in Serum Fatty Acid Composition and Metabolome-Microbiome Responses of Heigai Pigs Induced by Dietary N-6/n-3 Polyunsaturated Fatty Acid Ratio

Changing fatty acid composition is a potential nutritional strategy to shape microbial communities in pigs. However, the effect of different n-6/n-3 polyunsaturated fatty acid (PUFA) ratios on serum fatty acid composition, microbiota, and their metabolites in the intestine of pigs remains unclear. Our study investigated the changes in serum fatty acid composition and metabolome–microbiome responses induced by dietary n-6/n-3 PUFA ratio based on a Heigai-pig model. A total of 54 Heigai finishing pigs (body weight: 71.59 ± 2.16 kg) fed with 3 types of diets (n-6/n-3 PUFA ratios are 8:1, 5:1, and 3:1) were randomly divided into 3 treatments with 6 replications (3 pigs per replication) for 75 days. Results showed that dietary n-6/n-3 PUFA ratio significantly affected biochemical immune indexes including glucose (Glu), triglycerides (TG), total cholesterol (TChol), non-esterified fatty acid (NEFA), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and total thyroxine (TT4), and medium- and long-chain fatty acid composition, especially n-3 PUFA and n-6/n-3 PUFA ratio in the serum. However, no significant effects were found in the SCFAs composition and overall composition of the gut microbiota community. In the low dietary n-6/n-3 PUFA ratio group, the relative abundance of Cellulosilyticum, Bacteroides, and Alloprevotella decreased, Slackia and Sporobacter increased. Based on the metabolomic analysis, dietary n-6/n-3 PUFA ratio altered the metabolome profiles in the colon. Moreover, Pearson’s correlation analysis indicated that differential microbial genera and metabolites induced by different n-6/n-3 PUFA ratio had tight correlations and were correlated with the n-6 PUFA and n-3 PUFA content in longissimus dorsi muscle (LDM) and subcutaneous adipose tissue (SAT). Taken together, these results showed that lower dietary n-6/n-3 PUFA ratio improved serum fatty acid composition and metabolome–microbiome responses of Heigai pigs and may provide a new insight into regulating the metabolism of pigs and further better understanding the crosstalk with host and microbes in pigs.

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.