Expression patterns of STAT3, ERK and estrogen-receptor α are associated with development and histologic severity of hepatic steatosis: a retrospective study

Rucker L, Johnson J, Ghosh S. Transcriptomics of MASLD Pathobiology in African American Patients in the Washington DC Area †

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is becoming the most common chronic liver disease worldwide and is of concern among African Americans (AA) in the United States. This pilot study evaluated the differential gene expressions and identified the signature genes in the disease pathways of AA individuals with MASLD. Blood samples were obtained from MASLD patients (n = 23) and non-MASLD controls (n = 24) along with their sociodemographic and medical details. Whole-blood transcriptomic analysis was carried out using Affymetrix Clarion-S Assay. A validation study was performed utilizing TaqMan Arrays coupled with Ingenuity Pathway Analysis (IPA) to identify the major disease pathways. Out of 21,448 genes in total, 535 genes (2.5%) were significantly (p < 0.05) and differentially expressed when we compared the cases and controls. A significant overlap in the predominant differentially expressed genes and pathways identified in previous studies using hepatic tissue was observed. Of note, TGFB1 and E2F1 genes were upregulated, and HMBS was downregulated significantly. Hepatic fibrosis signaling is the top canonical pathway, and its corresponding biofunction contributes to the development of hepatocellular carcinoma. The findings address the knowledge gaps regarding how signature genes and functional pathways can be detected in blood samples ('liquid biopsy') in AA MASLD patients, demonstrating the potential of the blood samples as an alternative non-invasive source of material for future studies.

Sex differences in chronic liver disease and benign liver lesions

The epidemiology, natural history, and therapeutic responses of chronic liver diseases and liver lesions often vary by sex. In this review, we summarize available clinical and translational data on these aspects of the most common liver conditions encountered in clinical practice, including the potential contributions of sex hormones to the underlying pathophysiology of observed differences. We also highlight areas of notable knowledge gaps and discuss sex disparities in access to liver transplant and potential strategies to address these barriers. Given established sex differences in immune response, drug metabolism, and response to liver-related therapies, emerging clinical trials and epidemiological studies should prioritize dedicated analyses by sex to inform sex-specific approaches to liver-related care.

Integrated omics analysis for characterization of the contribution of high fructose corn syrup to non-alcoholic fatty liver disease in obesity

BACKGROUND

High-Fructose Corn Syrup (HFCS), a sweetener rich in glucose and fructose, is nowadays widely used in beverages and processed foods; its consumption has been correlated to the emergence and progression of Non-Alcoholic Fatty Liver Disease (NAFLD). Nevertheless, the molecular mechanisms by which HFCS impacts hepatic metabolism remain scarce, especially in the context of obesity. Besides, the majority of current studies focuses either on the detrimental role of fructose in hepatic steatosis or compare separately the additive impact of fructose versus glucose in high fat diet-induced NAFLD.

AIM

By engaging combined omics approaches, we sought to characterize the role of HFCS in obesity-associated NAFLD and reveal molecular processes, which mediate the exaggeration of steatosis under these conditions.

METHODS

Herein, C57BL/6 mice were fed a normal-fat-diet (ND), a high-fat-diet (HFD) or a HFD supplemented with HFCS (HFD-HFCS) and upon examination of their metabolic and NAFLD phenotype, proteomic, lipidomic and metabolomic analyses were conducted to identify HFCS-related molecular alterations of the hepatic metabolic landscape in obesity.

RESULTS

Although HFD and HFD-HFCS mice displayed comparable obesity, HFD-HFCS mice showed aggravation of hepatic steatosis, as analysis of the lipid droplet area in liver sections revealed (12,15 % of total section area in HFD vs 22,35 % in HFD-HFCS), increased NAFLD activity score (3,29 in HFD vs 4,86 in HFD-HFCS) and deteriorated hepatic insulin resistance, as compared to the HFD mice. Besides, the hepatic proteome of HFD-HFCS mice was characterized by a marked upregulation of 5 core proteins implicated in de novo lipogenesis (DNL), while an increased phosphatidyl-cholines(PC)/phosphatidyl-ethanolamines(PE) ratio (2.01 in HFD vs 3.04 in HFD-HFCS) was observed in the livers of HFD-HFCS versus HFD mice. Integrated analysis of the omics datasets indicated that Tricarboxylic Acid (TCA) cycle overactivation is likely contributing towards the intensification of steatosis during HFD-HFCS-induced NAFLD.

CONCLUSION

Our results imply that HFCS significantly contributes to steatosis aggravation during obesity-related NAFLD, likely deriving from DNL upregulation, accompanied by TCA cycle overactivation and deteriorated hepatic insulin resistance.

Spatial molecular and cellular determinants of STAT3 activation in liver fibrosis progression in non-alcoholic fatty liver disease

Background & Aims

The prevalence of non-alcoholic fatty liver disease (NAFLD) and its severe form, non-alcoholic steatohepatitis (NASH), is increasing. Individuals with NASH often develop liver fibrosis and advanced liver fibrosis is the main determinant of mortality in individuals with NASH. We and others have reported that STAT3 contributes to liver fibrosis and hepatocellular carcinoma in mice.

Methods

Here, we explored whether STAT3 activation in hepatocyte and non-hepatocyte areas, measured by phospho-STAT3 (pSTAT3), is associated with liver fibrosis progression in 133 patients with NAFLD. We further characterized the molecular and cellular determinants of STAT3 activation by integrating spatial distribution and transcriptomic changes in fibrotic NAFLD livers.Results: pSTAT3 scores in non-hepatocyte areas progressively increased with fibrosis severity (r = 0.53, p <0.001). Correlation analyses between pSTAT3 scores and expression of 1,540 immune- and cancer-associated genes revealed a large effect of STAT3 activation on gene expression changes in non-hepatocyte areas and confirmed a major role for STAT3 activation in fibrogenesis. Digital spatial transcriptomic profiling was also performed on 13 regions selected in hepatocyte and non-hepatocyte areas from four NAFLD liver biopsies with advanced fibrosis, using a customized panel of markers including pSTAT3, PanCK+CK8/18, and CD45. The regions were further segmented based on positive or negative pSTAT3 staining. Cell deconvolution analysis revealed that activated STAT3 was enriched in hepatic progenitor cells (HPCs) and sinusoidal endothelial cells. Regression of liver fibrosis upon STAT3 inhibition in mice with NASH resulted in a reduction of HPCs, demonstrating a direct role for STAT3 in HPC expansion.

Conclusion

Increased understanding of the spatial dependence of STAT3 signaling in NASH and liver fibrosis progression could lead to novel targeted treatment approaches.

Impact and implications

Advanced liver fibrosis is the main determinant of mortality in patients with NASH. This study showed using liver biopsies from 133 patients with NAFLD, that STAT3 activation in non-hepatocyte areas is strongly associated with fibrosis severity, inflammation, and progression to NASH. STAT3 activation was enriched in hepatic progenitor cells (HPCs) and sinusoidal endothelial cells (SECs), as determined by innovative technologies interrogating the spatial distribution of pSTAT3. Finally, STAT3 inhibition in mice resulted in reduced liver fibrosis and depletion of HPCs, suggesting that STAT3 activation in HPCs contributes to their expansion and fibrogenesis in NAFLD.

The research development of STAT3 in hepatic ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a common complication of surgery, which can cause rapid deterioration of the liver function, increase the risk of graft rejection, and seriously affect the prognosis of patients. The signal transducer and activator of transcription 3 (STAT3) protein has been implicated in pathogenesis of IRI. STAT3 influences the mitochondria through multiple pathways and is also involved in apoptosis and other forms of programmed cell death. STAT3 is associated with Janus kinase (JAK), phosphoinositide-3 kinase (PI3K), and heme oxygenase-1 (HO-1) in liver IRI. The STAT3 pathway plays a dual role in IRI as it can also regulate lipid metabolism which may have potential for treating IRI fatty liver. In this review, we summarize research on the function of STAT3 in liver IRI to provide references for its application in the clinic.

Overexpression of estrogen receptor β inhibits cellular functions of human hepatic stellate cells and promotes the anti-fibrosis effect of calycosin via inhibiting STAT3 phosphorylation

BACKGROUND

Estrogen receptor β (ERβ) is the major ER subtype in hepatic stellate cells (HSCs). Previously we reported phytoestrogen calycosin suppressed liver fibrosis progression and inhibited HSC-T6 cell functions, suggesting the effects may be related to ERβ. Here, we explore the effect of overexpressed ERβ on human HSCs and the role of ERβ in pharmacological action of calycosin.

METHODS

LX-2 cells were transfected with lentivirus to overexpress ERβ. In the presence or absence of overexpressed ERβ, the effects of ERβ and calycosin on proliferation, migration, activation, collagen production and degradation of TGF-β1-induced LX-2 cells and the role of ERβ in the inhibition effect of calycosin were investigated. LX-2 cells overexpressed with ERβ or treated with ER non-selective antagonist ICI182,780 were used to investigate the regulation of ERβ on JAK2/STAT3 signaling pathway. CCK-8 method was used to screen effective doses of calycosin and investigate cell proliferation. The cell migration was detected by transwell chamber assay. The expression of α-SMA was detected by immunofluorescence and western blot. The protein expressions of Col-I, MMP1, TIMP1, JAK2, p-JAK2, STAT3 and p-STAT3 were detected by western blot.

RESULTS

ERβ overexpressed lentivirus was successfully transfected into LX-2 cells with high efficiency. Overexpressed ERβ or calycosin alone inhibited the TGF-β1-induced LX-2 cell proliferation and migration, downregulated the protein expressions of α-SMA, Col-I, TIMP-1, p-STAT3 and upregulated MMP-1. Both overexpressed ERβ and calycosin had no significant effect on JAK2, p-JAK2 and STAT3 expressions. ERβ overexpression further enhanced the above effects of calycosin. However, after the cells were treated with ICI182,780, downregulation of STAT3 phosphorylation induced by calycosin was reversed.

CONCLUSIONS

ERβ mediated the inhibition of major functions of LX-2 cell possibly by inhibiting the phosphorylation of STAT3, and was an important pathway through which calycosin exerted anti-liver fibrosis effect.

ERK1/2-RSK2 Signaling in Regulation of ERα-Mediated Responses

Signaling via extracellular regulated kinase 1/2 (ERK1/2) and p90 ribosomal S6 kinase (RSK), a downstream effector, mediates numerous processes. For example, ERK1/2-RSK signaling is essential for estrogen homeostasis in the mammary gland and uterus to maintain physiological responsiveness. This review will focus on the coordination of ERK1/2-RSK2 and estrogen signaling through estrogen receptor alpha (ERα). The interrelationship and the feedback mechanisms between these pathways occurs at the level of transcription, translation, and posttranslational modification. Identifying how ERK1/2-RSK2 and estrogen signaling cooperate in homeostasis and disease may lead to novel therapeutic approaches in estrogen-dependent disorders.

Asiatic acid alleviates liver fibrosis via multiple signaling pathways based on integrated network pharmacology and lipidomics

Liver fibrosis is characterized by the abnormal deposition of the extracellular matrix with a severe inflammatory response and/or metabolic disorder. Asiatic acid (AA), a natural compound derived from Centella asiatica, exhibited potent anti-fibrosis effects. This investigation first confirmed the anti-fibrosis effects of AA in TGF-β-LX-2 cells and CCl₄-induced liver fibrosis mice, and then sought to elucidate a novel mechanism of action by integrating network pharmacology and lipidomics. Network pharmacology was used to find potential targets of AA, while lipidomics was used to identify differential metabolites between fibrosis and recovered cohorts. AA could suppress hepatic stellate cell activation in vitro and improve liver fibrosis in vivo. Network pharmacology unveiled the genes involved in pathways in cancer, peroxisome proliferators-activated receptors signaling pathway, and arachidonic acid metabolism pathway. Furthermore, five key genes were found in the both human and mouse databases, indicating that arachidonic acid metabolism was important. Changes in lyso-phosphocholine (22:5), prostaglandin F2α, and other related lipid metabolites also suggested the involvement of arachidonic acid metabolism the anti-fibrotic effect. In summary, our integrated strategies demonstrated that AA targeted multiple targets and impeded the progression of liver fibrosis by ameliorating arachidonic acid metabolism.

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.

Epidemiology of non-alcoholic fatty liver disease and hepatocellular carcinoma

The prevalence of hepatocellular carcinoma (HCC) is increasing worldwide, whereas that of most other cancers is decreasing. Non-alcoholic fatty liver disease (NAFLD), which has increased with the epidemics of obesity and type 2 diabetes, increases the risk of HCC. Interestingly, NAFLD-associated HCC can develop in patients with or without cirrhosis. A lack of awareness about NAFLD-related HCC has led to delays in diagnosis. Therefore, a large number of patients with HCC are diagnosed with advanced-stage HCC with low 5-year survival. In this context, increasing awareness of NAFLD and NAFLD-related HCC may lead to earlier diagnosis and more effective interventions.

Oestrogen promotes lipids transportation through oestrogen receptor α in hepatic steatosis of geese in vitro

Evidence has shown that oestrogen suppresses lipids deposition in the liver of mammals. However, the molecular mechanism of oestrogen action in hepatic steatosis of geese liver has yet to be determined. This study aimed to investigate the effect of oestrogen on lipid homeostasis at different states of geese hepatocytes in vitro. The results showed that an in vitro model of hepatic steatosis was induced by 1.5 mM sodium oleate via detecting the viability of hepatocytes and content of lipids. When the normal hepatocytes were administrated with different concentrations of oestrogen (E₂ ), the expression levels of diacylglycerol acyltransferase 2 (DGAT2), microsomal triglyceride transfer protein (MTTP) and oestrogen receptors (ERs, alpha and beta) were up-regulated only at high concentrations of E₂ , whereas the lipid content was not a significant difference. In goose hepatocytes of hepatic steatosis, however, the expression levels of MTTP, apolipoprotein B (apoB) and ERα/β significantly increased at 10^-7 or 10^-6  M E₂ . Meanwhile, the lipids content significantly increased at 10^-9 and 10^-8  M E₂ and decreased at 80 µM E₂ . Further heatmap analysis showed that ERα was clustered with apoB and MTTP in either normal hepatocytes or that of hepatic steatosis. Taken together, E₂  might bind to ERα to up-regulate the expression levels of apoB and MTTP, promoting the transportation of lipids and alleviating lipids overload in hepatic steatosis of geese in vitro.

Common Transcriptional Program of Liver Fibrosis in Mouse Genetic Models and Humans

Multifactorial metabolic diseases, such as non-alcoholic fatty liver disease, are a major burden to modern societies, and frequently present with no clearly defined molecular biomarkers. Herein we used system medicine approaches to decipher signatures of liver fibrosis in mouse models with malfunction in genes from unrelated biological pathways: cholesterol synthesis-Cyp51, notch signaling-Rbpj, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling-Ikbkg, and unknown lysosomal pathway-Glmp. Enrichment analyses of Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome and TRANScription FACtor (TRANSFAC) databases complemented with genome-scale metabolic modeling revealed fibrotic signatures highly similar to liver pathologies in humans. The diverse genetic models of liver fibrosis exposed a common transcriptional program with activated estrogen receptor alpha (ERα) signaling, and a network of interactions between regulators of lipid metabolism and transcription factors from cancer pathways and the immune system. The novel hallmarks of fibrosis are downregulated lipid pathways, including fatty acid, bile acid, and steroid hormone metabolism. Moreover, distinct metabolic subtypes of liver fibrosis were proposed, supported by unique enrichment of transcription factors based on the type of insult, disease stage, or potentially, also sex. The discovered novel features of multifactorial liver fibrotic pathologies could aid also in improved stratification of other fibrosis related pathologies.

Renalase Attenuates Mouse Fatty Liver Ischemia/Reperfusion Injury through Mitigating Oxidative Stress and Mitochondrial Damage via Activating SIRT1

Liver ischemia/reperfusion (IR) injury is a severe complication of liver surgery. Moreover, nonalcoholic fatty liver disease (NAFLD) patients are particularly vulnerable to IR injury, with higher rates of postoperative morbidity and mortality after liver surgeries. Our previous study found that renalase (RNLS) was highly sensitive and responsive to oxidative stress, which may be a promising biomarker for the evaluation of the severity of liver IR injury. However, the role of RNLS in liver IR injury remains unclear. In the present study, we intensively explored the role and mechanism of RNLS in fatty liver IR injury in vivo and in vitro. C57BL/6 mice were divided into 2 groups feeding with high-fat diet (HFD) and control diet (CD), respectively. After 20 weeks' feeding, they were suffered from portal triad blockage and reflow to induce liver IR injury. Additionally, oleic acid (OA) and tert-butyl hydroperoxide (t-BHP) were used in vitro to induce steatotic hepatocytes and to simulate ROS burst and mimic cellular oxidative stress following portal triad blockage and reflow, respectively. Our data showed that RNLS was downregulated in fatty livers, and RNLS administration effectively attenuated IR injury by reducing ROS production and improving mitochondrial function through activating SIRT1. Additionally, the downregulation of RNLS in the fatty liver was mediated by a decrease of signal transduction and activator of transcription 3 (STAT3) expression under HFD conditions. These findings make RNLS a promising therapeutic strategy for the attenuation of liver IR injury.

A Panel of Protein Kinase Chemosensors Distinguishes Different Types of Fatty Liver Disease

The worldwide incidence of fatty liver disease continues to rise, which may account for concurrent increases in the frequencies of more aggressive liver ailments. Given the existence of histologically identical fatty liver disease subtypes, there is a critical need for the identification of methods that can classify disease and potentially predict progression. Herein, we show that a panel of protein kinase chemosensors can distinguish fatty liver disease subtypes. These direct activity measurements highlight distinct differences between histologically identical fatty liver diseases arising from diets rich in fat versus alcohol and identify a previously unreported decrease in p38α activity associated with a high-fat diet. In addition, we have profiled kinase activities in both benign (diet-induced) and progressive (STAM) disease models. These experiments provide temporal insights into kinase activity during disease development and progression. Altogether, this work provides the basis for the future development of clinical diagnostics and potential treatment strategies.

Cellular senescence: Molecular mechanisms and pathogenicity

Cellular senescence is the arrest of normal cell division. Oncogenic genes and oxidative stress, which cause genomic DNA damage and generation of reactive oxygen species, lead to cellular senescence. The senescence-associated secretory phenotype is a distinct feature of senescence. Senescence is normally involved in the embryonic development. Senescent cells can communicate with immune cells to invoke an immune response. Senescence emerges during the aging process in several tissues and organs. In fact, increasing evidence shows that cellular senescence is implicated in aging-related diseases, such as nonalcoholic fatty liver disease, obesity and diabetes, pulmonary hypertension, and tumorigenesis. Cellular senescence can also be induced by microbial infection. During cellular senescence, several signaling pathways, including those of p53, nuclear factor-κB (NF-κB), mammalian target of rapamycin, and transforming growth factor-beta, play important roles. Accumulation of senescent cells can trigger chronic inflammation, which may contribute to the pathological changes in the elderly. Given the variety of deleterious effects caused by cellular senescence in humans, strategies have been proposed to control senescence. In this review, we will focus on recent studies to provide a brief introduction to cellular senescence, including associated signaling pathways and pathology.