Dataset Information

Tissue-specific pathways and networks underlying sexual dimorphism in non-alcoholic fatty liver disease.

ABSTRACT:

Background

Non-alcoholic fatty liver disease (NAFLD) encompasses benign steatosis and more severe conditions such as non-alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. This chronic liver disease has a poorly understood etiology and demonstrates sexual dimorphisms. We aim to examine the molecular mechanisms underlying sexual dimorphisms in NAFLD pathogenesis through a comprehensive multi-omics study. We integrated genomics (DNA variations), transcriptomics of liver and adipose tissue, and phenotypic data of NAFLD derived from female mice of ~?100 strains included in the hybrid mouse diversity panel (HMDP) and compared the NAFLD molecular pathways and gene networks between sexes.

Results

We identified both shared and sex-specific biological processes for NAFLD. Adaptive immunity, branched chain amino acid metabolism, oxidative phosphorylation, and cell cycle/apoptosis were shared between sexes. Among the sex-specific pathways were vitamins and cofactors metabolism and ion channel transport for females, and phospholipid, lysophospholipid, and phosphatidylinositol metabolism and insulin signaling for males. Additionally, numerous lipid and insulin-related pathways and inflammatory processes in the adipose and liver tissue appeared to show more prominent association with NAFLD in male HMDP. Using data-driven network modeling, we identified plausible sex-specific and tissue-specific regulatory genes as well as those that are shared between sexes. These key regulators orchestrate the NAFLD pathways in a sex- and tissue-specific manner. Gonadectomy experiments support that sex hormones may partially underlie the sexually dimorphic genes and pathways involved in NAFLD.

Conclusions

Our multi-omics integrative study reveals sex- and tissue-specific genes, processes, and networks underlying sexual dimorphism in NAFLD and may facilitate sex-specific precision medicine.

SUBMITTER: Kurt Z

PROVIDER: S-EPMC6196429 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Publications

Tissue-specific pathways and networks underlying sexual dimorphism in non-alcoholic fatty liver disease.

Kurt Zeyneb Z Barrere-Cain Rio R LaGuardia Jonnby J Mehrabian Margarete M Pan Calvin C Hui Simon T ST Norheim Frode F Zhou Zhiqiang Z Hasin Yehudit Y Lusis Aldons J AJ Yang Xia X

Biology of sex differences 20181022 1

<h4>Background</h4>Non-alcoholic fatty liver disease (NAFLD) encompasses benign steatosis and more severe conditions such as non-alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. This chronic liver disease has a poorly understood etiology and demonstrates sexual dimorphisms. We aim to examine the molecular mechanisms underlying sexual dimorphisms in NAFLD pathogenesis through a comprehensive multi-omics study. We integrated genomics (DNA variations), transcriptomics of liver and adi ...[more]

PMID: 30343673

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Project description:Introduction: At the molecular level, cellular aging involves changes in multiple gene pathways, which can produce many aging phenotypes. In the liver, senescence changes lead to impaired hepatic function. We hypothesized that the natural hepatic aging process is driven by sex-dependent mechanisms. Purpose: We studied our well-established model of aging in which we have previously determined aging of metabolism, reproduction and endocrine systems. We performed liver transcriptomics (RNA-seq) on male and female rats at 110 and 650 days (d) fed with normal rat chow to determine changes key signaling pathways related to senescence processes. Methods: To identify the functional F1 liver changes due to natural aging processes, we evaluated the differentially expressed genes (DEGs) between 650d and 110d in males and females, with separate pairwise comparisons due to the marked differences. Genes were filtered based on ?1.4 fold change (FC) and nominal P value <0.05 (Studentｴs t-test). Results: We found that the natural liver aging process shows sex-differences. RNA-seq revealed more male (3,967) than female (283) differentially expressed genes (DEG) and pathways over the 110d to 650d period studied. Cell cycle pathway signaling in males was accompanied by decreased protein and gene expression of key genes (CDK2, CDK4, Cycd and PCNA) and an increase of p57 at 650d vs. 110d. In females, protein and gene expression of cell growth regulators such as p15 and p21, that inhibit cell cycle G1 progression were increased. Moreover, additionally the cell senescence pathway showed sexual dimorphism in liver gene regulation. Conclusions: Our results demonstrate how the natural aging process affects the liver transcriptome signature in a sex-dependent manner, specifically in cell cycle and cell senescence pathways, pathways that contribute in a major fashion to the development of aging-induced liver diseases. Understanding cellular senescence pathways involved in the natural aging process will aid evaluation of mechanisms associated with altered aging and frailty trajectories.

Project description:Purpose: To conduct a transcriptomic study of gene oscillations in mouse liver by RNA sequencing of total RNA samples from 6 different time points across the day. Specific interest is to see whether sex is a factor in large scale gene oscillations under ad-libitum control conditions and in response to caloric restriction diet, since caloric restriction was previously reported to affect gene oscillation Methods: Total RNA was isolated from 20 mg mouse liver tissue using mini spin column QIAGEN RNeasy Mini Kit (Ref #74104, Lot#163035346, Hilden, Germany) according to the manufacturer’s protocol. Sample purity was checked on Nano Drop 2000 (Thermo Fisher Scientific, Waltham, MA, USA) with 260/280 ratio ≥ 2.0 and 260/230 ratio ≥ 2.0 for every sample. Each sample used for the analysis had RNA integrity number > 7. The RNA sequencing was performed by Novogene Corporation Inc (Sacramento, CA, USA). After sample quality control, non-directional – polyA enrichment library was prepared using NEBNext Ultra™ II RNA Library Prep Kit for Illumina, and 50M reads (150bp, paired end) per sample were generated on Illumina NovaSeq 6000 platform. RNA-seq reads were mapped to the mouse protein coding genes (Ensembl: Mus_musculus; GRCm38) using Bowtie allowing up to 2-mismatches. The gene expected read counts and Transcripts Per Million (TPM) were estimated by RSEM (v1.2.3). The TPMs were further normalized by EBSeq R package to correct potential batch effect. Results: We have performed RNA sequencing analysis of mouse livers on Ad-libitum and timed Caloric Restriction diet across 6 time points in 24h. The results of subsequent compareRhythms analysis (R package) revealed that circadian rhythms in total RNA liver transcriptome are different between sexes of mice in both the number of oscillating genes and phase under ad-libitum diet. Caloric restriction increased the number of oscillating genes in both sexes and resulted in a larger overlap of rhythmic transcriptome between sexes, but did not eliminate the difference completely. The response of transcriptome to caloric restriction in terms of gain or loss of rhythm in gene expression profiles was also different between sexes. Additionally, we have shown that the lack of data stratification by sex might result in the failure to detect rhythmic changes in expression of some genes. Conclusions: Our study represents the first systematic analysis of the effect of sex on circadian rhythms of liver transcriptome under ad libitum and caloric restriction diets. We have shown that sex based differences exist in rhythmic transcriptome, as well as in the response of rhythmic transcriptome to diet. We are providing the data useful for both circadian and metabolic researchers and point out the gene candidates which may not be identified as rhythmic, if the data is not stratified by sex. With the help of GO analysis we have concluded that sex also influences the preference towards different processes to be regulated in rhythmic manner on transcriptional level - fatty acid metabolism and protein transport in males vs nucleic acid metabolism and RNA processing in females on ad-libitum diet. On calorie-restricted diet nucleic acid metabolism and RNA processing were enriched in males vs protein transport and signal transduction in females on calorie-restricted diet. These findings highlight a complex interaction of sex and diet in their effect on circadian rhythms in liver gene expression. All of the data from sequenced RNA samples from MALE liver were previously uploaded with the GSE211975 dataset. The current dataset only contains RNA-seq samples from FEMALE liver.

Project description:Background & aims: The accumulation of adipose tissue macrophages (ATMs) in obesity has been associated with hepatic injury. However, the contribution of ATMs to hepatic fibrosis in non-alcoholic fatty liver disease (NAFLD) remains to be elucidated. Herein, we investigate the relationship between ATMs and liver fibrosis in patients with patients with NAFLD and evaluate the impact of modulation of ATMs over hepatic fibrosis in an experimental non-alcoholic steatohepatitis (NASH) model.MethodsAdipose tissue and liver biopsies from 42 patients with NAFLD with different fibrosis stages were collected. ATMs were characterised by immunohistochemistry and flow cytometry and the correlation between ATMs and liver fibrosis stages was assessed. Selective modulation of the ATM phenotype was achieved by i.p. administration of dextran coupled with dexamethasone in diet-induced obesity and NASH murine models. Chronic administration effects were evaluated by histology and gene expression analysis in adipose tissue and liver samples. In vitro crosstalk between human ATMs and hepatic stellate cells (HSCs) and liver spheroids was performed.ResultsPatients with NAFLD presented an increased accumulation of pro-inflammatory ATMs that correlated with hepatic fibrosis. Long-term modulation of ATMs significantly reduced pro-inflammatory phenotype and ameliorated adipose tissue inflammation. Moreover, ATMs modulation was associated with an improvement in steatosis and hepatic inflammation and significantly reduced fibrosis progression in an experimental NASH model. In vitro, the reduction of the pro-inflammatory phenotype of human ATMs with dextran-dexamethasone treatment reduced the secretion of inflammatory chemokines and directly attenuated the pro-fibrogenic response in HSCs and liver spheroids.ConclusionsPro-inflammatory ATMs increase in parallel with fibrosis degree in patients with NAFLD and their modulation in an experimental NASH model improves liver fibrosis, uncovering the potential of ATMs as a therapeutic target to mitigate liver fibrosis in NAFLD.Impact and implicationsWe report that human adipose tissue pro-inflammatory macrophages correlate with hepatic fibrosis in non-alcoholic fatty liver disease (NAFLD). Furthermore, the modulation of adipose tissue macrophages (ATMs) by dextran-nanocarrier conjugated with dexamethasone shifts the pro-inflammatory phenotype of ATMs to an anti-inflammatory phenotype in an experimental murine model of non-alcoholic steatohepatitis. This shift ameliorates adipose tissue inflammation, hepatic inflammation, and fibrosis. Our results highlight the relevance of adipose tissue in NAFLD pathophysiology and unveil ATMs as a potential target for NAFLD.

Dataset Information

Tissue-specific pathways and networks underlying sexual dimorphism in non-alcoholic fatty liver disease.

Background

Results

Conclusions

Publications

Tissue-specific pathways and networks underlying sexual dimorphism in non-alcoholic fatty liver disease.

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