Ketogenic diet time-dependently prevents NAFLD through upregulating the expression of antioxidant protein metallothionein-2.

BACKGROUND & AIMS: The past few decades have witnessed a rapid growth in the prevalence of nonalcoholic fatty liver disease (NAFLD). While the ketogenic diet (KD) is considered for managing NAFLD, the safety and efficacy of the KD on NAFLD has been a controversial topic. Here, we aimed to investigate the effect of KD of different durations on metabolic endpoints in mice with NAFLD and explore the underlying mechanisms. METHODS: NAFLD mice were fed with KD for 1, 2, 4 and 6 weeks, respectively. The blood biochemical indexes (blood lipids, AST, ALT and etc.) and liver fat were measured. The LC-MS/MS based proteomic analysis was performed on liver tissues. Metallothionein-2 (MT2) was knocked down with adeno-associated virus (AAV) or small interfering RNA (siRNA) in NAFLD mice and AML-12 cells, respectively. H&E, BODIPY and ROS staining were performed to examine lipid deposition and oxidative stress. Furthermore, MT2 protein levels, nucleus/cytoplasm distribution and DNA binding activity of peroxisome proliferators-activated receptors α (PPARα) were evaluated. RESULTS: KD feeding for 2 weeks showed the best improvement on NAFLD phenotype. Proteomic analysis revealed that MT2 was a key candidate for different metabolic endpoints of NAFLD affected by different durations of KD feeding. MT2 knockdown in NAFLD mice blocked the effects of 2 weeks of KD feeding on HFD-induced steatosis. In mouse primary hepatocytes and AML-12 cells, MT2 protein levels were induced by ß-hydroxybutyric acid (ß-OHB). MT2 Knockdown blunted the effects of ß-OHB on alleviating PA-induced lipid deposition. Mechanistically, 2 weeks of KD or ß-OHB treatment reduced oxidative stress and upregulated the protein levels of MT2 in nucleus, which subsequently increased its DNA binding activity and PPARα protein expression. CONCLUSIONS: Collectively, these findings indicated that KD feeding prevented NAFLD in a time dependent manner and MT2 is a potential target contributing to KD improvement on steatosis.

Proteomics reveals MRPL4 as a high-risk factor and a potential diagnostic biomarker for prostate cancer.

Through digital rectal examinations (DRE) and routine prostate-specific antigen (PSA) screening, early prostate cancer (PC) treatment has become possible. However, PC is a complex and heterogeneous disease. In vivo, cancer cells can invade adjacent tissues and metastasize to other tissues resulting in hard cures. Therefore, the key to improving PC patients' survival time is preventing cancer cells' metastasis. We used mass spectrometry to profile primary PC in patients with versus without metastatic PC. We named these two groups of PC patients as high-risk primary PC (n = 11) and low-risk primary PC (n = 7), respectively. At the same time, patients with benign prostatic hyperplasia (BPH, n = 6) were used as controls to explore the possible factors driving PC metastasis. Based on comprehensive mass spectrometry analysis and biological validation, we found significant upregulation of MRPL4 expression in high-risk primary PC relative to low-risk primary PC and BPH. Further, through research of the extensive clinical cohort data in the database, we discovered that MRPL4 could be a high-risk factor for PC and serve as a potential diagnostic biomarker. The MRPL4 might be used as an auxiliary indicator for clinical status/stage of primary PC to predict patient survival time.

Lipidomics analysis of human follicular fluid form normal-weight patients with polycystic ovary syndrome: a pilot study.

BACKGROUND: The polycystic ovary syndrome (PCOS) is the most common endocrine associated with insulin resistance, even in the absence of overweight. The global lipid profile of the follicular fluid in PCOS with normal weight as yet has not been investigated. The objection of this pilot study was to explore the changes of lipids in the follicular fluid of PCOS with normal weight. METHODS: Follicular fluid samples were collected from patients who underwent IVF, including normal-weight women without PCOS (control group, n = 10) and normal-weight women with PCOS (PCOS group, n = 8). A lipidomic analysis was performed by high performance liquid chromatography/ mass spectrometry (HPLC-MS). Multidimensional statistical analysis was performed to disclose the global differences between the two groups. Further, differential lipid analysis between the two groups was performed by Fold Change Analysis (FC Analysis) and T-test to screen potential markers. RESULTS: All 812 species of 32 subclasses of lipids were identified by lipidomics analysis. 108 kinds of lipids were considered as the potential candidate differential metabolites with the score of variable importance in the project (VIP) more than 1 by the orthogonal partial least squares discriminant analysis. 32 lipids were significantly different between the PCOS group and the control group simultaneously with FC > 1.5 or FC < 0.67, p-value < 0.05 and VIP value > 1. These differential species of lipid belong to lipid subclasses including triglycerides (TG), phosphatidylethanolamines (PE) and phosphatidylinositols (PI). CONCLUSION: The identified differential lipids in the follicular fluid may be considered as candidate biomarkers as well as therapeutic targets of PCOS with normal-weight.

Proteomics reveals the potential mechanism of Mrps35 controlling Listeria monocytogenes intracellular proliferation in macrophages.

Macrophages are sentinels in the organism which can resist and destroy various bacteria through direct phagocytosis. Here, we reported that expression level of mitochondrial ribosomal protein S35 (Mrps35) continued to decrease over infection time after Listeria monocytogenes (L. monocytogenes) infected macrophages. Our results indicated that knockdown Mrps35 increased the load of L. monocytogenes in macrophages. This result supported that Mrps35 played the crucial roles in L. monocytogenes infection. Moreover, we performed the comprehensive proteomics to analyze the differentially expressed protein of wild type and Mrps35 Knockdown Raw264.7 cells by L. monocytogenes infection over 6 h. Based on the results of mass spectrometry, we presented a wide variety of hypotheses about the mechanism of Mrps35 controlling the L. monocytogenes intracellular proliferation. Among them, experiments confirmed that Mrps35 and 60S ribosomal protein L22-like 1 (Rpl22l1) were a functional correlation or potentially a compensatory mechanism during L. monocytogenes infection. This study provided new insights into understanding that L. monocytogenes infection changed the basic synthesis or metabolism-related proteins of host cells.

MiR-26a targets EphA2 to resist intracellular Listeria monocytogenes in macrophages.

At infection sites, macrophages are sentinels that resist and destroy various pathogens, through direct phagocytosis. In macrophages, microRNAs play a variety of crucial roles, the most striking of which is the regulation of the ability of the host cell to resist infection. However, the underlying mechanisms associated with the anti-infection effects mediated by microRNAs remain largely unknown. Here, we demonstrated that miR-26a is downregulated during infection by Listeria monocytogenes (Lm). In miR-26a overexpressing mice, the Lm bacterial burden of liver and spleen decreased significantly within 72 h of infection, compared with that in control mice. Subsequently, RNA sequencing (RNA-seq) data suggested that miR-26a may attenuate the survival of Lm by targeting the Ephrin receptor tyrosine kinase A2 (EphA2). The knockdown of EphA2 in RAW264.7 macrophage cells resulted in decreased intracellular Lm burden. Taken together, these findings validate EphA2 as a target of miR-26a and provide a mechanism through which Lm may survive within macrophages by altering host miRNA expression.

Proteomic analysis of murine macrophages mitochondria and lysosomes reveal Cathepsin D as a potential broad-spectrum antimicrobial protein.

Bacterial resistance to antibiotics has become increasingly widespread, posing a serious threat to human life and health. Macrophages in the host's natural immune system can directly destroy most of bacteria. Therefore, exploring the function of macrophages' mitochondria and lysosomes in killing bacteria might help us overcome the problem of bacterial resistance. We used mass spectrometry to analyze the dynamic expression landscape of mitochondrial and lysosomal proteins in macrophages upon infection with Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. We discovered that Cathepsin D (Ctsd) is up-regulated at the protein level during infection by all five bacteria. Ctsd inhibitor and knockout experiments confirmed that Ctsd is a potential broad-spectrum antibacterial protein. Ctsd should be investigated further as a potential drug target for new antibacterial treatments.

Identification of key differentially expressed genes associated with non­small cell lung cancer by bioinformatics analyses.

Increasing evidence has indicated that the abnormal expressions of certain genes serve important roles in tumorigenesis, progression and metastasis. The aim of the present study was to explore the key differentially expressed genes (DEGs) between non­small cell lung cancer (NSCLC) and matched normal lung tissues by analyzing 4 different mRNA microarray datasets downloaded from the Gene Expression Omnibus (GEO) database. In improving the reliability of the bioinformatics analysis, the DEGs in each dataset that met the cut­off criteria (adjust P­value <0.05 and |log2fold­change (FC)|>1) were intersected with each other, from which 195 were identified (consisting of 57 upregulated and 138 downregulated DEGs). The GO analysis results revealed that the upregulated DEGs were significantly enriched in various biological processes (BP), including cell cycle, mitosis and cell proliferation while the downregulated DEGs were significantly enriched in angiogenesis and response to drug and cell adhesion. The hub genes, including CCNB1, CCNA2, CEP55, PBK and HMMR, were identified based on the protein­protein interaction (PPI) network. The Kaplan­Meier survival analysis indicated that the high expression level of each of these hub genes correlates with poorer overall survival in all patients with NSCLC, which indicates that they may serve important roles in the progression of NSCLC. In conclusion, the DEGs and hub genes identified in the present study may contribute to the comprehensive understanding of the molecular mechanisms of NSCLC and may be used as diagnostic and prognostic biomarkers as well as molecular targets for the treatment of NSCLC.

Melatonin alleviates cadmium-induced liver injury by inhibiting the TXNIP-NLRP3 inflammasome.

Cadmium (Cd) is a persistent environmental and occupational contaminant that accumulates in the liver and induces oxidative stress and inflammation. Melatonin possesses potent hepatoprotective properties against the development and progression of acute and chronic liver injury. Nevertheless, the molecular mechanism underlying the protective effects of melatonin against Cd-induced hepatotoxicity remains obscure. In this study, we aimed to investigate the effects of melatonin on Cd-induced liver inflammation and hepatocyte death. Male C57BL/6 mice were intraperitoneally injected with melatonin (10 mg/kg) once a day for 3 days before exposure to CdCl2 (2.0 mg/kg). We found that Cd induced hepatocellular damage and inflammatory infiltration as well as increased serum ALT/AST enzymes. In addition, we showed that Cd triggered an inflammatory cell death, which is mediated by the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome. Moreover, melatonin treatment significantly alleviated Cd-induced liver injury by decreasing serum ALT/AST levels, suppressing pro-inflammatory cytokine production, inhibiting NLRP3 inflammasome activation, ameliorating oxidative stress, and attenuating hepatocyte death. Most importantly, melatonin markedly abrogated Cd-induced TXNIP overexpression and decreased the interaction between TXNIP and NLRP3 in vivo and in vitro. However, treatment with siRNA targeting TXNIP blocked the protective effects of melatonin in Cd-treated primary hepatocytes. Collectively, our results suggest that melatonin confers protection against Cd-induced liver inflammation and hepatocyte death via inhibition of the TXNIP-NLRP3 inflammasome pathway.

Abnormal response to the anorexic effect of GHS-R inhibitors and exenatide in male Snord116 deletion mouse model for Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a genetic disease characterized by persistent hunger and hyperphagia. The lack of the Snord116 small nucleolar RNA cluster has been identified as the major contributor to PWS symptoms. The Snord116 deletion (Snord116del) mouse model manifested a subset of PWS symptoms including hyperphagia and hyperghrelinemia. In this study, male Snord116del mice were characterized and tested for their acute and chronic responses to anorexic substances related to the ghrelin pathway. In comparison with their wild-type littermates, the food intake rate of Snord116del mice was 14% higher when fed ad libitum, and 32% to 49% higher within 12 hours after fasting. Fasted Snord116del mice were less sensitive to the acute anorexic effect of competitive antagonist [d-Lys(3)]-GHRP6, YIL-781, and reverse agonist [d-Arg(1),d-Phe(5),d-Trp(7,9),Leu(11)]-substance P (SPA) of ghrelin receptor GHS-R. All 3 GHS-R inhibitors failed to inhibit chronic food intake of either Snord116del or wild-type mice due to rapid adaptation. Although fasted Snord116del mice had normal sensitivity to the acute anorexic effect of glucagon-like peptide 1 receptor agonist exenatide, those fed ad libitum required a higher dose and more frequent delivery to achieve ∼15% suppression of long-term food intake in comparison with wild-type mice. Ghrelin, however, is unlikely to be essential for the anorexic effect of exenatide in fed mice, as shown by the fact that exenatide did not reduce ghrelin levels in fed mice and food intake of ghrelin(-/-) mice fed ad libitum could be suppressed by exenatide. In conclusion, this study suggests that GHS-R may not be an effective therapeutic target, and in contrast, exenatide may produce anorexic effect in PWS individuals.