Altered expression of fatty acid-metabolizing enzymes in aromatase-deficient mice

Leisure-Time Physical Activity, Time Spent Sitting and Risk of Non-alcoholic Fatty Liver Disease: A Cross-Sectional Study in Puglia

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. The increasingly sedentary lifestyle in recent years may have accelerated the development of NAFLD, independent of the level of physical activity.

OBJECTIVE

The purpose of this cross-sectional study was to determine the association between leisure-time physical activity (LTPA) and time spent sitting (TSS) and the likelihood of developing NAFLD in a sample of men and women aged 18-64 years, from southern Italy.

DESIGN

The study is based on two cohort studies, a randomized clinical trial and an observational cost-benefit study.

PARTICIPANTS

A total of 1269 participants (51.5% women) drawn from 3992 eligible subjects were enrolled in this study.

EXPOSURES

Leisure-time physical activity (LTPA) and time spent sitting (TSS) were assessed using the Italian long form of the International Physical Activity Questionnaire (IPAQ-LF), designed for administration to adults aged 18 to 65 years.

MAIN MEASURES

The association of exposures with the probability of belonging to a certain NAFLD degree of severity.

KEY RESULTS

The probability of having mild, moderate, and severe NAFLD tends to decrease with increasing LTPA and decreasing TSS levels. We selected a combination of participants aged 50 years and older stratified by gender. Men had a statistically significant difference in the probability of developing moderate NAFLD if they spent 70 h per week sitting and had low LTPA, while among women there was a statistically significant difference in the probability of developing mild or moderate NAFLD if they had moderate LPTA and spent 35-70 h/week sitting.

CONCLUSIONS

The study thus showed that the amount of LTPA and the amount of TSS are associated with development and progression of NAFLD, but this relationship is not a linear one-especially in women aged ≥ 50 years old.

Age at menopause and risk of metabolic dysfunction-associated fatty liver disease: A 14-year cohort study

BACKGROUNDS & AIMS

Menopause, characterized by a sudden decline in estrogen levels, has significant effects on women's health, especially when it occurs early. This study aimed to investigate the associations between menopausal age and incidence of metabolic dysfunction-associated fatty liver disease (MAFLD) using a large cohort and a long-term follow-up.

METHODS

Menopausal age was categorized into four groups (G1-4 [<40, 40-44, 45-49, and ≥50 years, respectively]). Cox proportional hazards regression analysis was used to assess the risk of developing MAFLD during the follow-up period according to the menopausal age categories.

RESULTS

A total of 1,888 participants were included in the final analysis and followed for a median period of 12.3 years. The unadjusted hazard ratios (95 % CIs) for the incidence of new-onset MAFLD were 1.11 (0.93-1.32), 1.15 (0.90-1.47), and 1.52 (1.12-2.07) in G3, G2, and G1, respectively, compared with that in G4. After adjusting for confounders, the hazard ratio (95 % CIs) for the incidence of new-onset MAFLD was 1.40 (1.00-1.95) in G1 compared with that in G4.

CONCLUSION

The risk of developing MAFLD was higher in women with premature menopause (<40 years) than in those with menopause aged ≥50 years.

New aspects characterizing non-obese NAFLD by the analysis of the intestinal flora and metabolites using a mouse model

Non-alcoholic fatty liver disease (NAFLD) is a major public health problem due to the high incidence affecting approximately one-third of the world's population. NAFLD is usually linked to obesity and excessive weight. A subset of patients with NAFLD expresses normal or low body mass index; thus, the condition is called non-obese NAFLD or lean NAFLD. However, patients and healthcare professionals have little awareness and understanding of NAFLD in non-obese individuals. Furthermore, preclinical results from non-obese animal models with NAFLD are unclear. Gut microbiota and their metabolites in non-obese/lean-NAFLD patients differ from those in obese NAFLD patients. Therefore, we analyzed the biochemical indices, intestinal flora, and intestinal metabolites in a non-obese NAFLD mouse model established using a methionine-choline-deficient (MCD) diet. The significantly lean MCD mice had a remarkable fatty liver with lower serum triglyceride and free fatty acid levels, as well as higher alanine transaminase and aspartate transaminase levels than normal mice. 16S RNA sequencing of fecal DNA showed that the overall richness and diversity of the intestinal flora decreased in MCD mice, whereas the Firmicutes:Bacteroidota ratio was increased. g_Tuzzerella, s_Bifidobacterium pseudolongum, and s_Faecalibaculum rodentium were the predominant species in non-obese NAFLD mice. Fecal metabolomics using liquid chromatography-tandem mass spectrometry revealed the potential biomarkers for the prognosis and diagnosis of non-obese NAFLD, including high levels of tyramine glucuronide, 9,12,13-TriHOME, and pantetheine 4'-phosphate, and low levels of 3-carbamoyl-2-phenylpropionaldehyde, N-succinyl-L,L-2,6-diaminopimelate, 4-methyl-5-thiazoleethanol, homogentisic acid, and estriol. Our findings could be useful to identify and develop drugs to treat non-obese NAFLD and lean NAFLD.

IMPORTANCE

Patients and healthcare professionals have little awareness and understanding of NAFLD in non-obese individuals. In fact, about 40% of people with NAFLD worldwide are non-obese, and nearly one-fifth are lean. Lean NAFLD unfortunately may be unnoticed for years and remains undetected until hepatic damage is advanced and the prognosis is compromised. This study focused on the lean NAFLD, screened therapeutic agents, and biomarkers for the prognosis and diagnosis using MCD-induced male C57BL/6J mice. The metabolites tyramine glucuronide, 9,12,13-TriHOME, and pantetheine 4'-phosphate, together with the predominant flora including g_Tuzzerella, s_Bifidobacterium pseudolongum, and s_Faecalibaculum rodentium, were specific in non-obese NAFLD mice and might be used as targets for non-obese NAFLD drug exploration. This study is particularly significant for non-obese NAFLDs that need to be more actively noticed and vigilant.

Navigating nonalcoholic fatty liver disease (NAFLD): Exploring the roles of estrogens, pharmacological and medical interventions, and life style

The pursuit of studying this subject is driven by the urgency to address the increasing global prevalence of Non-Alcoholic Fatty Liver Disease (NAFLD) and its profound health implications. NAFLD represents a significant public health concern due to its association with metabolic disorders, cardiovascular complications, and the potential progression to more severe conditions like non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Liver estrogen signaling is important for maintaining liver function, and loss of estrogens increases the likelihood of NAFLD in postmenopausal women. Understanding the multifaceted mechanisms underlying NAFLD pathogenesis, its varied treatment strategies, and their effectiveness is crucial for devising comprehensive and targeted interventions. By unraveling the intricate interplay between genetics, lifestyle, hormonal regulation, and gut microbiota, we can unlock insights into risk stratification, early detection, and personalized therapeutic approaches. Furthermore, investigating the emerging pharmaceutical interventions and dietary modifications offers the potential to revolutionize disease management. This review reinforces the role of collaboration in refining NAFLD comprehension, unveiling novel therapeutic pathways, and ultimately improving patient outcomes for this intricate hepatic condition.

Different effects of menopausal hormone therapy on non-alcoholic fatty liver disease based on the route of estrogen administration

The effects of menopausal hormone therapy (MHT) on non-alcoholic fatty liver disease (NAFLD) were compared based on the route of estrogen administration. The study included 368 postmenopausal women who received MHT for 12 months. Patients were divided into transdermal (n = 75) and oral (n = 293) groups based on the estrogen route. Changes in the prevalence of NAFLD were compared between the two groups before and after 12 months of MHT. In addition, differences in the progression of NAFLD after MHT based on the dose of estrogen and type of progestogen were evaluated in the oral group. After MHT, the prevalence of NAFLD decreased from 24 to 17.3% in the transdermal group but increased from 25.3 to 29.4% in the oral group. Little or no change was found in clinical characteristics and laboratory tests in the transdermal group during MHT. However, serum levels of total cholesterol and low-density lipoprotein cholesterol decreased and triglycerides and high-density lipoprotein cholesterol increased significantly in the oral group. Furthermore, changes in the prevalence of NAFLD were not significantly different based on the dose of estrogen or type of progestogen. Our findings indicate that transdermal estrogen can be beneficial in terms of NAFLD progression.

Serum folate associated with nonalcoholic fatty liver disease and advanced hepatic fibrosis

The role played by serum folate in the progression of nonalcoholic fatty liver disease (NAFLD) remains controversial. The purpose of this study was to investigate the association of serum folate with NAFLD and advanced liver fibrosis (AHF). We conducted a cross-sectional study with 5417 participants using 2011-2018 NHANES data. Multiple logistic regression analysis and propensity score matching analysis were used to investigate the association of serum folate with NAFLD and AHF. In the completely adjusted model, participants in the high serum folate group had a 27% (OR 0.73, 95% CI 0.62, 0.87, p = 0.0003) and 53% (OR 0.47, 95% CI 0.35, 0.63, p < 0.0001) lower odds of suffering from NAFLD and AHF, respectively, compared to the low serum folate group. The similar results in propensity score matching further validated the above association. Stratified analysis showed that the negative correlation of serum folate with NAFLD and AHF demonstrated a broad consistency across populations. The results of this study indicate that higher serum folate level was associated with lower odds of NAFLD and AHF among US adults. Further prospective studies are necessary due to the limitations of cross-sectional studies.

Skeletal Muscle Endogenous Estrogen Production Ameliorates the Metabolic Consequences of a High-Fat Diet in Male Mice

AIMS

The role of skeletal muscle estrogen and its ability to mitigate the negative impact of a high-fat diet (HFD) on obesity-associated metabolic impairments is unknown. To address this, we developed a novel mouse model to determine the role of endogenous 17β-estradiol (E2) production in males in skeletal muscle via inducible, skeletal muscle-specific aromatase overexpression (SkM-Arom↑).

METHODS

Male SkM-Arom↑ mice and littermate controls were fed a HFD for 14 weeks prior to induction of SkM-Arom↑ for a period of 6.5 weeks. Glucose tolerance, insulin action, adipose tissue inflammation, and body composition were assessed. Indirect calorimetry and behavioral phenotyping experiments were performed using metabolic cages. Liquid chromatography mass spectrometry was used to determine circulating and tissue (skeletal muscle, hepatic, and adipose) E2 and testosterone concentrations.

RESULTS

SkM-Arom↑ significantly increased E2 in skeletal muscle, circulation, the liver, and adipose tissue. SkM-Arom↑ ameliorated HFD-induced hyperglycemia, hyperinsulinemia, impaired glucose tolerance, adipose tissue inflammation, and reduced hepatic lipid accumulation while eliciting skeletal muscle hypertrophy.

CONCLUSION

Enhanced skeletal muscle aromatase activity in male mice induces weight loss, improves metabolic and inflammatory outcomes and mitigates the negative effects of a HFD. Additionally, our data demonstrate for the first time skeletal muscle E2 has anabolic effects on the musculoskeletal system.

Associations between red blood cell count and metabolic dysfunction-associated fatty liver disease(MAFLD)

BACKGROUND

Some studies found that red blood cell count (RBC) was an unrecognized risk factor for non-alcoholic fatty liver disease (NAFLD). While the epidemiological data underpinning the evidence is very limited. As there are some differences between the latest criteria of metabolic dysfunction-associated fatty liver disease (MAFLD) and NAFLD, itis necessary to evaluate the relationship between RBC and MAFLD.

METHODS

We performed a cross-sectional analysis of the National Health and Nutritional Examination Survey (NHANES)2017-2018 cohort, including 4477 participants. Hepatic steatosis was determined when the value of controlled attenuation parameter (CAP) obtained by Fibroscan was ≥274 dB/m. Multivariate logistic regression analysis was used to estimate the association between RBC and MAFLD. We estimated the adjusted odds ratio (OR) of RBC for MAFLD, and the nonlinear relationship between RBC and MAFLD was further described using smooth curve fittings and threshold-effect analysis.

RESULTS

We found that MAFLD risk was significantly higher according to RBC quartiles. The adjusted odds ratio (OR) and 95% confidence intervals (CIs)for the highest RBC quartile were 1.5(1.0, 2.3) for male and 1.1 (0.8, 1.6) for female, respectively. As for male, a non-linear relationship was discovered between RBCs and MAFLD, with a RBC threshold of 4.2. The effect sizes and confidence intervals on the right side of the inflection point were 1.5 (1.0, 2.0) (P for nonlinearity = 0.027). The sensitivity analysis showed a similar result.

CONCLUSION

We demonstrated that that elevated RBC level is associated with the higher risk of MAFLD in male. The positive relationship was not significant in females after full adjustment. Our finding provided novel evidence indicating that RBCs might be a potential biomarker for MAFLD.

NAFLD improves risk prediction of type 2 diabetes: with effect modification by sex and menopausal status

BACKGROUND AND AIMS

The effects of sex and menopausal status on the association between NAFLD and incident type 2 diabetes (T2D) remain unclear. We investigated the effect modification by sex and menopause in the association between NAFLD and T2D; also, the added predictive ability of NAFLD for the risk of T2D was assessed.

APPROACH AND RESULTS

This cohort study comprised 245,054 adults without diabetes (109,810 premenopausal women; 4958 postmenopausal women; 130,286 men). Cox proportional hazard models were used to estimate hazard ratios (HRs; 95% confidence intervals [CIs]) for incident T2D according to NAFLD status. The incremental predictive role of NAFLD for incident T2D was assessed using the area under the receiver operating characteristic curve, net reclassification improvement, and integrated discrimination improvement. A total of 8381 participants developed T2D (crude incidence rate/10³ person-years: 2.9 premenopausal women; 12.2 postmenopausal women; 9.3 men) during median follow-up of 5.3 years. NAFLD was positively associated with incident T2D in all groups. After adjustment for potential confounders, the multivariable-adjusted HRs (95% CIs) for incident T2D comparing NAFLD to no NAFLD were 4.63 (4.17-5.14), 2.65 (2.02-3.48), and 2.16 (2.04-2.29) in premenopausal women, postmenopausal women, and men, respectively. The risks of T2D increased with NAFLD severity as assessed by serum fibrosis markers, and the highest relative excess risks were observed in premenopausal women. The addition of NAFLD to conventional risk factors improved risk prediction for incident T2D in both sexes, with a greater improvement in women than men.

CONCLUSIONS

NAFLD, including more severe NAFLD, is a stronger risk factor for incident T2D in premenopausal women than in postmenopausal women or men; protection against T2D is lost in premenopausal women with NAFLD.

Non-alcoholic fatty liver disease across endocrinopathies: Interaction with sex hormones

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most frequent chronic liver disease globally. NAFLD is strongly associated with metabolic syndrome and it has been recently suggested that to rename NAFLD as metabolic dysfunction-associated fatty liver disease (MAFLD). NAFLD has been studied in different endocrine axes and accumulating body of clinical and experimental studies have suggested that NAFLD is associated with polycystic ovarian syndrome (PCOS), hypopituitarism, growth hormone deficiency (GHD), hypogonadism and other endocrine disorders. In fact, endocrine dysfunction may be considered as the major contributor for the development, progression, and severity of NAFLD. In the present comprehensive review, we discussed the epidemiological and clinical evidence on the epidemiology, pathophysiology, and management of NAFLD in endocrine disorders, with an emphasis on the effects of sex-specific hormones/conditions as well as molecular basis of NAFLD development in these endocrine diseases.

Beyond the X Factor: Relevance of Sex Hormones in NAFLD Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, being frequently associated with obesity, unbalanced dietary regimens, and reduced physical activity. Despite their greater adiposity and reduced physical activity, women show a lower risk of developing NAFLD in comparison to men, likely a consequence of a sex-specific regulation of liver metabolism. In the liver, sex differences in the uptake, synthesis, oxidation, deposition, and mobilization of lipids, as well as in the regulation of inflammation, are associated with differences in NAFLD prevalence and progression between men and women. Given the major role of sex hormones in driving hepatic sexual dimorphism, this review will focus on the role of sex hormones and their signaling in the regulation of hepatic metabolism and in the molecular mechanisms triggering NAFLD development and progression.

The interplay between metabolic dysregulations and non-alcoholic fatty liver disease in women after menopause

The hypoestrogenic period after menopause and associated metabolic imbalance might facilitate the onset of non-alcoholic fatty liver disease (NAFLD) and its progression. The prevalence of NAFLD increases in patients experiencing premature ovarian insufficiency, as well as surgical or natural menopause. The postmenopausal period is characterized by dyslipidemia and insulin resistance associated with an increased influx of free fatty acids to the liver with consequent steatosis and further progression of NAFLD. More than half of postmenopausal women with diabetes mellitus type 2 suffer from NAFLD. It is suggested that estrogens slow the progression of chronic liver diseases by suppression of inflammation, improvement of mitochondrial function, alleviation of oxidative stress, insulin resistance, and fibrogenesis. The hyperandrogenic state of polycystic ovary syndrome (PCOS) is associated with the development of NAFLD in women of reproductive age, but it is difficult to extend these findings to menopause due to inappropriate diagnosis of PCOS after menopause. Lifestyle intervention, including physical activity and dietary regimens, remains the first-line preventive and therapeutic option for NAFLD. There are contradictory reports on the use of menopausal hormonal therapy (MHT) and NAFLD. It is necessary to investigate the potential effects of estradiol dose, progesterone type, selective estrogen receptor modulators and tissue-selective estrogen complex compounds on NAFLD development and progression in postmenopausal women. The present review aims to explore the pathophysiological and clinical aspects of liver metabolic disturbances in women after menopause, focusing on the possible preventive and therapeutic strategies in NAFLD, including the potential role of MHT.

Fine particulate matter exposure and perturbation of serum metabolome: A longitudinal study in Baoding, China

Metabolomics represents a powerful tool for measuring environmental exposures and biological responses to unveil potential mechanisms. Few studies have investigated the effects of exposure to fine particulate matter (PM_2.5) longitudinally on serum metabolomics in regions with high-level PM_2.5. Therefore, we examined the changes of serum metabolomics corresponding to individual PM_2.5 exposure levels in spring and autumn among 63 healthy college students in Baoding city, Hebei, China. The metabolic profiling was determined by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. The average level of individual PM_2.5 in the spring was 1.82-fold higher than in the autumn (240 μg/m³ vs 132 μg/m³). Males were exposed to a higher level of PM_2.5 than females in the spring. Metabolic profiling was clearly separated by orthogonal partial least square-discriminant analysis in males but not in females. In the analysis of the associations between the metabolome and PM_2.5 of the two seasons, the changes of 14 serum metabolites were significantly associated with PM_2.5 in males. The metabolites related to heme metabolism (bilirubin, biliverdin), energy metabolism and oxidative stress (2-Octenoylcarnitine, N-Heptanoylglycine, and acetylcysteine), phospholipid metabolism (lysophosphatidic acid, phospholipid acid, and lysophosphatidylethanolamine), and tryptophan metabolism (N-Acetylserotonin, indolepyruvate, and melatonin) were decreased in the range of 2.16%-6.80% for each 10 μg/m³ increase of PM_2.5, while thyrotropin-releasing hormone, glutathione, and phosphatidylethanolamine related to energy metabolism and oxidative stress, and phospholipid metabolism were increased in the range of 2.95%-4.90% for each 10 μg/m³ increase of PM_2.5. This longitudinal study suggests that higher PM_2.5 exposure may induce perturbations in serum metabolic signaling related to oxidative stress and inflammation, and males may be more prone to these metabolic perturbations.

Longitudinal associations of total and trunk fat in childhood and adolescence and risk of hepatic steatosis at 24 years

BACKGROUND

The importance of body fat distribution in the development of nonalcoholic fatty liver disease (NAFLD) is unclear.

OBJECTIVE

To examine whether total and truncal fat deposition patterns in childhood/adolescence are associated with NAFLD risk at 24 years.

METHODS

Data were from 1657 participants in the Avon Longitudinal Study of Parents and Children. Transient elastography was used to assess hepatic steatosis (low/moderate/severe) at 24 years and dual-energy X-ray absorptiometry was used to assess total body fat percent (TBF%) and trunk fat percent (TrF%) at 9, 13, 15, 17, and/or 24 years. Linear mixed models were constructed with quadratic age to examine trajectories of TBF% and TrF% by steatosis at 24 years, adjusting for confounders.

RESULTS

In both sexes, TBF% trajectories from 9 to 24 years followed a similar pattern based on steatosis group (P = .83 for boys and P = .14 for girls for age² *steatosis fixed effect). However, at all ages TBF% was higher for moderate/severe vs low steatosis at 24 years (P < .05). In contrast, TrF% trajectories diverged based on steatosis group (P = .001 for boys and P = .0002 for girls for age² *steatosis fixed effect), such that, in both sexes, participants with moderate/severe steatosis at 24 yrs exhibited less decline in TrF% from adolescence to adulthood compared to participants with low steatosis at 24 yrs. Similar to TBF%, TrF% was higher at nearly all ages for moderate/severe vs low steatosis. Results were similar after adjusting for BMI category at each age, except in boys some differences for TrF% were attenuated.

CONCLUSIONS

These findings suggest that sex-specific body fat distribution patterns in childhood/adolescence may help to identify those at risk of developing NAFLD in adulthood.

Effects of Tamoxifen vs. Toremifene on fatty liver development and lipid profiles in breast Cancer

BACKGROUND

Tamoxifen (TAM) and Toremifene (TOR), two kinds of selective estrogen receptor modulators (SERMs), have equal efficacy in breast cancer patients. However, TAM has been proved to affect serum lipid profiles and cause fatty liver disease. The study aimed to compare the effects of TAM and TOR on fatty liver development and lipid profiles.

METHODS

This study performed a retrospective analysis of 308 SERMs-treated early breast cancer patients who were matched 1:1 based on propensity scores. The follow-up period was 3 years. The primary outcomes were fatty liver detected by ultrasonography or computed tomography (CT), variation in fibrosis indexes, and serum lipid profiles change.

RESULTS

The cumulative incidence rate of new-onset fatty liver was higher in the TAM group than in the TOR group (113.2 vs. 67.2 per 1000 person-years, p < 0.001), and more severe fatty livers occurred in the TAM group (25.5 vs. 7.5 per 1000 person-years, p = 0.003). According to the Kaplan-Meier curves, TAM significantly increased the risk of new-onset fatty liver (25.97% vs. 17.53%, p = 0.0243) and the severe fatty liver (5.84% vs. 1.95%, p = 0.0429). TOR decreased the risk of new-onset fatty liver by 45% (hazard ratio = 0.55, p = 0.020) and showed lower fibrotic burden, independent of obesity, lipid, and liver enzyme levels. TOR increased triglycerides less than TAM, and TOR increased high-density lipoprotein cholesterol, while TAM did the opposite. No significant differences in total cholesterol and low-density lipoprotein cholesterol are observed between the two groups.

CONCLUSIONS

TAM treatment is significantly associated with more severe fatty liver disease and liver fibrosis, while TOR is associated with an overall improvement in lipid profiles, which supports continuous monitoring of liver imaging and serum lipid levels during SERM treatment.

Exposure to High-Fat Style Diet Induced Renal and Liver Structural Changes, Lipid Accumulation and Inflammation in Intact and Ovariectomized Female Rats

Purpose

We hypothesized that low estrogen levels aggravate obesity-related complications. Diet-induced obesity can cause distinct pathologies, including impaired glucose tolerance, inflammation, and organ injury that leads to fatty liver and chronic kidney diseases. To test this hypothesis, ovariectomized (OVX) rats were fed a high-fat style diet (HFSD), and we examined structural changes and inflammatory response in the kidney and liver.

Methods

Sprague-Dawley female rats were ovariectomized or sham-operated and divided into four groups: sham-operated rats fed a normal diet (ND); ovariectomized rats fed a normal diet (OVX-ND); sham-operated rats fed a HFSD; ovariectomized rats fed a high-fat style diet (OVX-HFSD). Mean blood pressure and fasting blood glucose were measured on weeks 0 and 10. The rats were sacrificed 10 weeks after initiation of ND or HFSD, the kidney and liver were harvested for histological, immunohistochemical and immunofluorescence studies.

Results

HFSD-fed rats presented a significantly greater adiposity index compared to their ND counterparts. Liver index, fasting blood glucose and mean blood pressure was increased in OVX-HFSD rats compared to HFSD rats at study terminal. Histological and morphometric studies showed focal interstitial mononuclear cell infiltration in the kidney of HFSD rats with mesangial expansion being greater in the OVX-HFSD rats. Both HFSD fed groups showed increased expressions of renal inflammatory markers, namely TNF-alpha, IL-6 and MCP-1, and infiltrating M1 macrophages with some influence of ovarian hormonal status. HFSD-feeding also caused hepatocellular steatosis which was aggravated in ovariectomized rats fed the same diet. Furthermore, hepatocellular ballooning was observed only in the OVX-HFSD rats. Similarly, HFSD-fed rats showed increased expressions of the inflammatory markers and M1 macrophage infiltration in the liver; however, only IL-6 expression was magnified in the OVX-HFSD.

Conclusion

Our data suggest that some of the structural changes and inflammatory response in the kidney and liver of rats fed a HFSD are exacerbated by ovariectomy.

Sex Differences in the Incidence of Obesity-Related Gastrointestinal Cancer

Cancer is the second leading cause of death worldwide, with 9.6 million people estimated to have died of cancer in 2018. Excess body fat deposition is a risk factor for many types of cancer. Men and women exhibit differences in body fat distribution and energy homeostasis regulation. This systematic review aimed to understand why sex disparities in obesity are associated with sex differences in the incidence of gastrointestinal cancers. Cancers of the esophagus, liver, and colon are representative gastrointestinal cancers, and obesity is a convincing risk factor for their development. Numerous epidemiological studies have found sex differences in the incidence of esophageal, liver, and colorectal cancers. We suggest that these sexual disparities are partly explained by the availability of estrogens and other genetic factors regulating inflammation, cell growth, and apoptosis. Sex differences in gut microbiota composition may contribute to differences in the incidence and phenotype of colorectal cancer. To establish successful practices in personalized nutrition and medicine, one should be aware of the sex differences in the pathophysiology and associated mechanisms of cancer development.

NAFLD and NASH in Postmenopausal Women: Implications for Diagnosis and Treatment

Nonalcoholic fatty liver disease (NAFLD) prevalence in women is increasing worldwide. Women of reproductive age have lower rates of NAFLD compared with men; however, this protection is lost following the menopausal transition when NAFLD prevalence in postmenopausal women becomes similar to or surpasses that in age-matched male counterparts. Ongoing epidemiological, clinical, and experimental studies indicate greater NAFLD risk and higher rates of severe hepatic fibrosis in postmenopausal women relative to premenopausal women, and that older women with NAFLD experience greater mortality than men. Investigations involving ovariectomized animal models demonstrate a causal relationship between estrogen deficiency and heightened susceptibility to the development of fatty liver and steatohepatitis, although dietary factors may exacerbate this complex relationship. The accumulated findings suggest that a better understanding of the interplay among menopausal status, metabolic comorbidities, and sex steroids in NAFLD pathogenesis is needed. Further, the mechanisms underlying the difference in NAFLD risk between postmenopausal and premenopausal women remain incompletely understood. The goals of this review are to summarize studies of NAFLD risk in postmenopausal women, discuss results from animal models of estrogen deficiency, and explore the development of NAFD within the context of altered sex hormone profiles resulting from the menopausal transition. Potential implications for the prevention, diagnosis, and treatment of NAFLD in this relatively understudied cohort are also addressed.

Non-alcoholic Fatty Liver Disease as a Canonical Example of Metabolic Inflammatory-Based Liver Disease Showing a Sex-Specific Prevalence: Relevance of Estrogen Signaling

There is extensive evidence supporting the interplay between metabolism and immune response, that have evolved in close relationship, sharing regulatory molecules and signaling systems, to support biological functions. Nowadays, the disruption of this interaction in the context of obesity and overnutrition underlies the increasing incidence of many inflammatory-based metabolic diseases, even in a sex-specific fashion. During evolution, the interplay between metabolism and reproduction has reached a degree of complexity particularly high in female mammals, likely to ensure reproduction only under favorable conditions. Several factors may account for differences in the incidence and progression of inflammatory-based metabolic diseases between females and males, thus contributing to age-related disease development and difference in life expectancy between the two sexes. Among these factors, estrogens, acting mainly through Estrogen Receptors (ERs), have been reported to regulate several metabolic pathways and inflammatory processes particularly in the liver, the metabolic organ showing the highest degree of sexual dimorphism. This review aims to investigate on the interaction between metabolism and inflammation in the liver, focusing on the relevance of estrogen signaling in counteracting the development and progression of non-alcoholic fatty liver disease (NAFLD), a canonical example of metabolic inflammatory-based liver disease showing a sex-specific prevalence. Understanding the role of estrogens/ERs in the regulation of hepatic metabolism and inflammation may provide the basis for the development of sex-specific therapeutic strategies for the management of such an inflammatory-based metabolic disease and its cardio-metabolic consequences.

Menopause and Non-Alcoholic Fatty Liver Disease: A Review Focusing on Therapeutic Perspectives

There is increasing evidence that menopause is associated with the progression and severity of non-alcoholic fatty liver disease (NAFLD). Estrogen deficiency worsens non-alcoholic steatohepatitis (NASH) in mice models with fatty liver. The prevalence of NAFLD seems to be higher in postmenopausal compared with premenopausal women. Although more data are needed, lower serum estradiol levels are associated with NASH in postmenopausal women. Apart from estrogen deficiency, relative androgen excess and decrease in sex hormone-binding protein are observed in postmenopausal women. These hormonal changes seem to interplay with an increase in abdominal adipose mass, also observed in postmenopausal women, and aging, which are both closely related to the severity and progressive forms of NAFLD. NAFLD adds extra morbidity to postmenopausal women, possibly increasing the risk of type 2 diabetes mellitus and cardiovascular disease. Improving parameters of the metabolic syndrome via modifications in diet and physical exercise may reduce the risk of NAFLD and its related morbidity. Limited studies have shown a beneficial effect of hormone replacement therapy (HRT) on NAFLD, although adverse hepatic effects have been attributed to progesterone in one study. Phytoestrogens may be alternatives to HRT, but their long-term efficacy and safety remain to be shown. The aim of this review was to summarize evidence linking menopause with NAFLD with a special focus on potential therapeutic perspectives.

The impact of pre-existed and SERM-induced non-alcoholic fatty liver disease on breast cancer survival: a meta-analysis

Background: Non-alcoholic fatty liver disease (NAFLD) is a common disorder and a frequent side effect of endocrine therapy (ET) for breast cancer treatment. This was the first meta-analysis to investigate the impact of NAFLD on breast cancer survival.

Material and Methods: We searched Pubmed, Embase and Cochrane Central Register of Controlled Trials database for relevant studies that investigated the correlation between NAFLD and breast cancer survival. Fixed- and random-effect meta-analyses were conducted according to the heterogeneity of enrolled studies. Subgroup analyses were performed based on whether NAFLD was induced by ET administration

Results: Eight cohorts from six studies including 3684 breast cancer patients were enrolled. NAFLD was significantly associated with advanced age (p < 0.001), obesity (p < 0.001), lymph node metastases (p = 0.003) and hormone receptor positivity (p < 0.001). NAFLD had no significant impact on disease free survival (DFS) [hazard ratio (HR) 1.07, 95% confidence interval (CI) = 0.64-1.77, p = 0.81] and overall survival (OS) (HR 1.29, 95% CI = 0.68-2.44, p = 0.44). In subgroup analyses, ET-associated NAFLD showed no significant impact on DFS and OS. Nonetheless, non-ET-associated NAFLD had a strong prognostic correlation with poor OS (HR 1.92, 95% CI = 1.09-3.41, p = 0.02).

Conclusion: NAFLD had no significant impact on breast cancer survival. However, non-ET-associated NAFLD implied increasing death risk. Future large-scale studies are warranted to further elucidate the correlation between NAFLD and breast cancer prognosis.

Changes in nucleus accumbens gene expression accompany sex-specific suppression of spontaneous physical activity in aromatase knockout mice

Aromatase catalyzes conversion of testosterone to estradiol and is expressed in a variety of tissues, including the brain. Suppression of aromatase adversely affects metabolism and physical activity behavior, but mechanisms remain uncertain. The hypothesis tested herein was that whole body aromatase deletion would cause gene expression changes in the nucleus accumbens (NAc), a brain regulating motivated behaviors such as physical activity, which is suppressed with loss of estradiol. Metabolic and behavioral assessments were performed in male and female wild-type (WT) and aromatase knockout (ArKO) mice. NAc-specific differentially expressed genes (DEGs) were identified with RNAseq, and associations between the measured phenotypic traits were determined. Female ArKO mice had greater percent body fat, reduced spontaneous physical activity (SPA), consumed less energy, and had lower relative resting energy expenditure (REE) than WT females. Such differences were not observed in ArKO males. However, in both sexes, a top DEG was Pts, a gene encoding an enzyme necessary for catecholamine (e.g., dopamine) biosynthesis. In comparing male and female WT mice, top DEGs were related to sexual development/fertility, immune regulation, obesity, dopamine signaling, and circadian regulation. SPA correlated strongly with Per3, a gene regulating circadian function, thermoregulation, and metabolism (r = -0.64, P = .002), which also correlated with adiposity (r = 0.54, P = .01). In conclusion, aromatase ablation leads to gene expression changes in NAc, which may in turn result in reduced SPA and related metabolic abnormalities. These findings may have significance to post-menopausal women and those treated with an aromatase inhibitor.

In vitro and in vivo approaches for identifying the role of aryl hydrocarbon receptor in the development of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic hepatic disease associated with the excessive accumulation of lipids in the liver. Premenopausal women are protected from the liver metabolic complications of obesity compared with body mass index (BMI)-matched men. This protection may be related to estrogen's ability to limit liver fat accumulation. Aryl hydrocarbon receptor (AhR), a novel regulator of NAFLD, may be an important target for regulating estrogen homeostasis. In present study, we used benzo[a]pyrene (BaP), a classic and potent ligand of AhR, to activate AhR pathway causes overexpression of the estrogen-metabolizing enzyme cytochrome P450 1A1 (CYP1A1) and affects the expression of important genes involved in hepatic lipid regulation. BaP induces CYP1A1 expression through AhR signaling and inhibits the protective effect of 17β-estradiol (E2) on hepatic steatosis, characterized by triglyceride accumulation, and markers of liver damage are significantly elevated. The expression of adipogenic genes involved in the hepatic lipid metabolism of sterol regulatory element-binding protein-1c (SREBP-1c) was increased compared with that in the control group. Furthermore, the mRNA and protein levels of peroxisome proliferator-activated receptor alpha (PPARα), which is involved in fatty acid oxidation, were significantly reduced. Taken together, our results revealed that the steatotic effect of AhR is likely due to overexpression of the E2 metabolic enzyme CYP1A1, which affects the estrogen signaling pathway, leading to the suppression of fatty acid oxidation, inhibition of the hepatic export of triglycerides, and an increase in peripheral fat mobilization. The results from this study may help establish AhR as a novel therapeutic and preventive target for fatty liver disease.

Potential Therapeutic Application of Estrogen in Gender Disparity of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) caused by fat accumulation in the liver is globally the most common cause of chronic liver disease. Simple steatosis can progress to nonalcoholic steatohepatitis (NASH), a more severe form of NAFLD. The most potent driver for NASH is hepatocyte death induced by lipotoxicity, which triggers inflammation and fibrosis, leading to cirrhosis and/or liver cancer. Despite the significant burden of NAFLD, there is no therapy for NAFLD/NASH. Accumulating evidence indicates gender-related NAFLD progression. A higher incidence of NAFLD is found in men and postmenopausal women than premenopausal women, and the experimental results, showing protective actions of estradiol in liver diseases, suggest that estrogen, as the main female hormone, is associated with the progression of NAFLD/NASH. However, the mechanism explaining the functions of estrogen in NAFLD remains unclear because of the lack of reliable animal models for NASH, the imbalance between the sexes in animal experiments, and subsequent insufficient results. Herein, we reviewed the pathogenesis of NAFLD/NASH focused on gender and proposed a feasible association of estradiol with NAFLD/NASH based on the findings reported thus far. This review would help to expand our knowledge of the gender differences in NAFLD and for developing gender-based treatment strategies for NAFLD/NASH.

Reproductive Endocrinology of Nonalcoholic Fatty Liver Disease

The liver and the reproductive system interact in a multifaceted bidirectional fashion. Sex steroid signaling influences hepatic endobiotic and xenobiotic metabolism and contributes to the pathogenesis of functional and structural disorders of the liver. In turn, liver function affects the reproductive axis via modulating sex steroid metabolism and transport to tissues via sex hormone-binding globulin (SHBG). The liver senses the body's metabolic status and adapts its energy homeostasis in a sex-dependent fashion, a dimorphism signaled by the sex steroid milieu and possibly related to the metabolic costs of reproduction. Sex steroids impact the pathogenesis of nonalcoholic fatty liver disease, including development of hepatic steatosis, fibrosis, and carcinogenesis. Preclinical studies in male rodents demonstrate that androgens protect against hepatic steatosis and insulin resistance both via androgen receptor signaling and, following aromatization to estradiol, estrogen receptor signaling, through regulating genes involved in hepatic lipogenesis and glucose metabolism. In female rodents in contrast to males, androgens promote hepatic steatosis and dysglycemia, whereas estradiol is similarly protective against liver disease. In men, hepatic steatosis is associated with modest reductions in circulating testosterone, in part consequent to a reduction in circulating SHBG. Testosterone treatment has not been demonstrated to improve hepatic steatosis in randomized controlled clinical trials. Consistent with sex-dimorphic preclinical findings, androgens promote hepatic steatosis and dysglycemia in women, whereas endogenous estradiol appears protective in both men and women. In both sexes, androgens promote hepatic fibrosis and the development of hepatocellular carcinoma, whereas estradiol is protective.

Intracrine Regulation of Estrogen and Other Sex Steroid Levels in Endometrium and Non-gynecological Tissues; Pathology, Physiology, and Drug Discovery

Our understanding of the intracrine (or local) regulation of estrogen and other steroid synthesis and degradation expanded in the last decades, also thanks to recent technological advances in chromatography mass-spectrometry. Estrogen responsive tissues and organs are not passive receivers of the pool of steroids present in the blood but they can actively modify the intra-tissue steroid concentrations. This allows fine-tuning the exposure of responsive tissues and organs to estrogens and other steroids in order to best respond to the physiological needs of each specific organ. Deviations in such intracrine control can lead to unbalanced steroid hormone exposure and disturbances. Through a systematic bibliographic search on the expression of the intracrine enzymes in various tissues, this review gives an up-to-date view of the intracrine estrogen metabolisms, and to a lesser extent that of progestogens and androgens, in the lower female genital tract, including the physiological control of endometrial functions, receptivity, menopausal status and related pathological conditions. An overview of the intracrine regulation in extra gynecological tissues such as the lungs, gastrointestinal tract, brain, colon and bone is given. Current therapeutic approaches aimed at interfering with these metabolisms and future perspectives are discussed.

Lack of 17β-estradiol reduces sensitivity to insulin in the liver and muscle of male mice

The importance of estrogens for glucose homeostasis has been demonstrated by clinical, pharmacological, and experimental studies. Male mice lacking the aromatase gene (ArKO mice), which encodes an enzyme involved in estrogen synthesis, develop glucose- and insulin-intolerance. However, it remains unclear whether insulin signaling is actually impaired in the liver and muscle of ArKO mice. We examined the effects of estrogen-deficiency on insulin signaling by quantifying phosphorylation levels of protein kinase B (Akt) in the liver and muscle and by examining the expression levels of insulin-target genes in the liver. Insulin administration enhanced phosphorylation levels of Akt in the liver and muscle of wild-type (WT) mice, ArKO mice, and ArKO mice supplemented with 17β-estradiol (E2), but insulin was less effective in ArKO mice. Gene expression analysis revealed that alterations induced by insulin in WT liver were also observed in ArKO liver, but the degree of altered expression in a subset of genes was smaller in ArKO mice than in WT mice. E2 supplementation improved the insulin responses of some genes in ArKO mice. Thus, these findings suggest that insulin signaling in the liver and muscle of ArKO mice is less efficient than in WT mice, which contributes to whole-body glucose intolerance in ArKO mice.

Association of serum ferritin levels with non-alcoholic fatty liver disease in postmenopausal women

OBJECTIVE

This study aimed to investigate the association between serum ferritin levels and the presence of non-alcoholic fatty liver disease (NAFLD) in postmenopausal women.

METHODS

Two hundred and forty-one postmenopausal women who participated in a heath examination program were enrolled in the present study. Serum ferritin tertiles were categorized as follows: T1, ≤46.4 ng/ml; T2, 46.5-76.1 ng/ml; and T3, ≥76.2 ng/ml. The odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD were calculated after adjusting for confounding variables across serum ferritin tertiles using multiple logistic regression analysis.

RESULTS

The overall prevalence of NAFLD was 41.4% and was significantly increased in accordance with the serum ferritin tertiles as follows: 30.0% for T1, 40.7% for T2, and 54.3% for T3, respectively. As compared with the lowest tertile, the OR (95% CI) for NAFLD in the highest tertile was 2.69 (1.16-5.28) after adjusting for age, body mass index, regular exercise, mean arterial pressure, fasting plasma glucose, triglyceride, high-density lipoprotein cholesterol, alanine aminotransferase, and leukocyte count.

CONCLUSION

The serum ferritin level was positively and independently associated with NAFLD in postmenopausal women and could be a useful additional measure in assessing the risk of NAFLD in postmenopausal women.

Effects of high fructose intake on liver injury progression in high fat diet induced fatty liver disease in ovariectomized female mice

Epidemiology shows that the morbidity of nonalcoholic fatty liver disease (NAFLD) is increased in postmenopausal women and chronic high fructose intake induces NAFLD progression. To analyze the effects of high fructose intake on estrogen deficiency, we evaluated liver disease progression using ovariectomized mice fed with a high fat diet (HFD) for 12 weeks. Hepatic steatosis developed in all HFD groups. Fructose intake significantly increased the liver weight and serum alanine aminotransferase, which was not exacerbated by ovariectomy alone. Ovariectomy enhanced the hepatic inflammatory activity shown by tumor necrosis factor α upregulation in the groups with or without fructose intake. Both fructose intake and ovariectomy increased the hepatocytes with ballooning degeneration and hepatic macrophage infiltration and activated hepatic stellate cells. Coexistence of fructose intake and ovariectomy markedly enhanced liver cell destruction, macrophage accumulation, and progression of fibrosis. Liver damage was ameliorated by 17β-estradiol supplementation. These findings suggest that high fructose intake enhanced the progression of NAFLD in ovariectomized female mice.

Honokiol Improves Liver Steatosis in Ovariectomized Mice

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease, and is associated with the development of metabolic syndrome. Postmenopausal women with estrogen deficiency are at a higher risk of progression to NAFLD. Estrogen has a protective effect against the progression of the disease. Currently, there are no safe and effective treatments for these liver diseases in postmenopausal women. Honokiol (Ho), a bioactive natural product derived from Magnolia spp, has anti-inflammatory, anti-angiogenic, and anti-oxidative properties. In our study, we investigated the beneficial effects of Ho on NAFLD in ovariectomized (OVX) mice. We divided the mice into four groups, as follows: SHAM, OVX, OVX+β-estradiol (0.4 mg/kg of bodyweight), and OVX+Ho (50 mg/kg of diet). Mice were fed diets with/without Ho for 12 weeks. The bodyweight, epidermal fat, and weights of liver tissue were lower in the OVX group than in the other groups. Ho improved hepatic steatosis and reduced proinflammatory cytokine levels. Moreover, Ho markedly downregulated plasma lipid levels. Our results indicate that Ho ameliorated OVX-induced fatty liver and inflammation, as well as associated lipid metabolism. These findings suggest that Ho may be hepatoprotective against NAFLD in postmenopausal women.

Cognitive Effects of Aromatase and Possible Role in Memory Disorders

Diverse cognitive functions in many vertebrate species are influenced by local conversion of androgens to 17β-estradiol (E2) by aromatase. This enzyme is highly expressed in various brain regions across species, with some inter-species variation in terms of regional brain expression. Since women with breast cancer and men and women with other disorders are often treated with aromatase inhibitors (AI), these populations might be especially vulnerable to cognitive deficits due to low neuroE2 synthesis, i.e., synthesis of E2 directly within the brain. Animal models have been useful in deciphering aromatase effects on cognitive functions. Consequences of AI administration at various life cycle stages have been assessed on auditory, song processing, and spatial memory in birds and various aspects of cognition in rodent models. Additionally, cognitive deficits have been described in aromatase knockout (ArKO) mice that systemically lack this gene throughout their lifespan. This review will consider evidence to date that AI treatment in male and female rodent models, birds, and humans results in cognitive impairments. How brain aromatase regulates cognitive function throughout the lifespan, and gaps in current knowledge will be considered, along with future directions to better define how aromatase might guide learning and memory from early development through the geriatric period. Better understanding the importance of E2 synthesis on neurobehavioral responses at various ages will likely aid in the discovery of therapeutic strategies to prevent potential cognitive deficits, including Alzheimer's Disease, in individuals treated with AI or those possessing CYP19 gene polymorphisms, as well as cognitive effects of normal aging that may be related to changes in brain aromatase activity.

Sexual dimorphism in the glucose homeostasis phenotype of the Aromatase Knockout (ArKO) mice

We investigated the effects of estrogens on glucose homeostasis using the Aromatase Knockout (ArKO) mouse, which is unable to convert androgens into estrogens. The ArKO mouse is a model of total estrogen ablation which develops symptoms of metabolic syndrome. To determine the development and progression of whole body state of insulin resistance of ArKO mice, comprehensive whole body tolerance tests were performed on WT, ArKO and estrogen administrated mice at 3 and 12 months of age. The absence of estrogens in the male ArKO mice leads to hepatic insulin resistance, glucose and pyruvate intolerance from 3 to 12 months with consistent improvement upon estrogen treatment. Estrogen absence in the female ArKO mice leads to glucose intolerance without pyruvate intolerance or insulin resistance. The replacement of estrogens in the female WT and ArKO mice exhibited both insulin sensitizing and resistance effects depending on age and dosage. In conclusion, this study presents information on the sexually dimorphic roles of estrogens on glucose homeostasis regulation.

NAFLD as a Sexual Dimorphic Disease: Role of Gender and Reproductive Status in the Development and Progression of Nonalcoholic Fatty Liver Disease and Inherent Cardiovascular Risk

Nonalcoholic fatty liver disease (NAFLD) spans steatosis through nonalcoholic steatohepatis, cirrhosis, and hepatocellular carcinoma (HCC) associated with striking systemic features and excess cardiovascular and liver-related mortality. The pathogenesis of NAFLD is complex and multifactorial. Endocrine derangements are closely linked with dysmetabolic traits. For example, in animal and human studies, female sex is protected from dysmetabolism thanks to young individuals’ ability to partition fatty acids towards ketone body production rather than very low density lipoprotein (VLDL)-triacylglycerol, and to sex-specific browning of white adipose tissue. Ovarian senescence facilitates both the development of massive hepatic steatosis and the fibrotic progression of liver disease in an experimental overfed zebrafish model. Consistently, estrogen deficiency, by potentiating hepatic inflammatory changes, hastens the progression of disease in a dietary model of nonalcoholic steatohepatitis (NASH) developing in ovariectomized mice fed a high-fat diet. In humans, NAFLD more often affects men; and premenopausal women are equally protected from developing NAFLD as they are from cardiovascular disease. It would be expected that early menarche, definitely associated with estrogen activation, would produce protection against the risk of NAFLD. Nevertheless, it has been suggested that early menarche may confer an increased risk of NAFLD in adulthood, excess adiposity being the primary culprit of this association. Fertile age may be associated with more severe hepatocyte injury and inflammation, but also with a decreased risk of liver fibrosis compared to men and postmenopausal status. Later in life, ovarian senescence is strongly associated with severe steatosis and fibrosing NASH, which may occur in postmenopausal women. Estrogen deficiency is deemed to be responsible for these findings via the development of postmenopausal metabolic syndrome. Estrogen supplementation may at least theoretically protect from NAFLD development and progression, as suggested by some studies exploring the effect of hormonal replacement therapy on postmenopausal women, but the variable impact of different sex hormones in NAFLD (i.e., the pro-inflammatory effect of progesterone) should be carefully considered.

[Drug-induced Nonalcoholic Steatohepatitis]

Nonalcoholic steatohepatitis (NASH) is a chronic progressive liver disease characterized by intense liver steatosis accompanied by hepatocyte destruction, inflammation and fibrous, despite little or no history of alcoholic consumption. There are also cases of drug-induced secondary steatohepatitis. Drug-induced steatohepatitis is a relatively rare type of drug-induced liver disease, but close attention to the possible onset of steatohepatitis is needed when drugs with the potential to induce fatty liver are prescribed for long term use. Estrogen is a factor indispensable to smooth fatty acid β-oxidation in hepatocytes. However, treatment with Tamoxifen markedly suppresses fatty acid β-oxidation in the liver. As free fatty acids are toxic, their accumulation results in the activation of alternative fatty acid oxidation pathways mediated by CYP2E1 in cytosol and lipid peroxidases in peroxisomes in hepatocytes. CYP2E1 enhances lipid peroxidation and dicarboxylic acid synthesis via the activation of fatty acid ω-oxidation that injures mitochondria and results in the emergence of ballooned hepatocytes. In such cases, the attenuation of alternative fatty acid oxidation pathways could have some beneficial effects on mitochondrial injury, since fibrates (PPAR-α ligands) are potent enough to stimulate neutral fat consumption through the activation of peroxisomal fatty acid β-oxidation. Fortunately, fibrates attenuate serum estrogen levels by affecting estrogen receptor expression, so the co-administration of fibrates with Tamoxifen is expected to exert higher efficacy in breast cancer patients with Tamoxifen-induced hepatic steatosis.

Associations between hemoglobin concentrations and the development of incidental metabolic syndrome or nonalcoholic fatty liver disease

AIMS

Hemoglobin (Hb) is known to be associated with both nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS). We evaluated the relationship between serum Hb levels and the development of MS or NAFLD.

METHODS

A retrospective cohort study was conducted. We recruited participants who underwent abdominal ultrasonography and blood samplings in both 2005 and 2010.

RESULTS

Graded independent relationships were observed between higher Hb levels and the incidence of MS and NAFLD. After adjusting for age, body mass index, and fasting glucose, high-density lipoprotein cholesterol and triglyceride levels, the risk of developing MS was significantly higher according to the Hb quartiles in men (P for trend=0.027). The adjusted odds ratio (OR) and 95% confidence intervals (CIs) for the highest Hb quartile was 1.81 (1.06-3.10) for women and 1.43 (1.00-2.05) for men. The risk of developing NAFLD was also significantly higher according to the Hb quartiles in men (P for trend=0.03). The adjusted OR and 95% CI for the highest Hb quartile was 1.18 (0.73-1.91) in women and 1.76 (1.16-2.66) in men.

CONCLUSIONS

The risk of developing either MS or NAFLD was significantly associated with serum Hb levels in men. These findings have implications in the clinical availability of serum Hb as a predictor of MS and NAFLD.

Nonnuclear Estrogen Receptor Activation Improves Hepatic Steatosis in Female Mice

Estrogens have the potential to afford atheroprotection, to prevent excess adiposity and its metabolic complications including insulin resistance, and to lessen hepatic steatosis. Cellular responses to estrogens occur through gene regulation by nuclear estrogen receptors (ERs), and through signal initiation by plasma membrane-associated ER. Leveraging the potentially favorable cardiometabolic actions of estrogens has been challenging, because their reproductive tract and cancer-promoting effects adversely impact the risk to benefit ratio of the therapy. In previous works, we discovered that an estrogen dendrimer conjugate (EDC) comprised of ethinyl-estradiol (E₂) molecules linked to a poly(amido)amine dendrimer selectively activates nonnuclear ER, and in mice, EDC does not invoke a uterotrophic response or support ER-positive breast cancer growth. In the present investigation, we employed EDC to determine how selective nonnuclear ER activation impacts atherosclerosis, adiposity, glucose homeostasis, and hepatic steatosis in female mice. In contrast to E₂, EDC did not blunt atherosclerosis in hypercholesterolemic apoE^-/- mice. Also in contrast to E₂, EDC did not prevent the increase in adiposity caused by Western diet feeding in wild-type mice, and it did not affect Western diet-induced glucose intolerance. However, E₂ and EDC had comparable favorable effect on diet-induced hepatic steatosis, and this was related to down-regulation of fatty acid and triglyceride synthesis genes in the liver. Predictably, only E₂ caused a uterotrophic response. Thus, although nonnuclear ER activation does not prevent atherosclerosis or diet-induced obesity or glucose intolerance, it may provide a potential new strategy to combat hepatic steatosis without impacting the female reproductive tract or increasing cancer risk.

GLUT2 proteins and PPARγ transcripts levels are increased in liver of ovariectomized rats: reversal effects of resistance training

[Purpose]

This study investigated the effects of ovariectomy (Ovx) and 12 weeks of resistance training (RT) on gene expression of GLUT2, the main glucose transporter in the liver, and on PPARγ, a transcription factor known to target GLUT2 expression.

[Methods]

Forty Holtzman rats were divided into 5 groups: Sham-sedentary (Sed), Sham- RT, Ovx-Sed, Ovx-RT, and Ovx-Sed with hormone replacement (E2). The RT protocol consisted of sessions held every 72 h for 12 weeks, during which the animals performed 4 to 9 vertical climbs (1.1 m) at 2 min intervals with progressively heavier weights (30 g after the fourth climb) tied to the tail. The E2 silastic capsule was inserted into the rats’ backs 48 hours before the first RT session.

[Results]

In addition to liver fat, GLUT2 protein levels and PPARγ transcripts were increased (P < 0.05) in Ovx compared to Sham-Sed animals, suggesting increased hepatic glucose uptake under estrogen deficient conditions. RT and E2 in Ovx rats decreased liver fat accumulation as well as GLUT2 and PPARγ gene expression to the level of Sham-Sed animals.

[Conclusion]

The results of this study suggest that liver GLUT2 as well as PPARγ expression in Ovx rats are accompanied by increased fat accumulation and glucose uptake, thus providing a substrate for increased de novo lipogenesis. RT appears to be an appropriate exercise model to circumvent these effects.

Western-style diet, sex steroids and metabolism

The evolutionary transition from hunting to farming was associated with introduction of carbohydrate-rich diets. Today, the increased consumption of simple sugars and high-fat food brought about by Western-style diet and physical inactivity are leading causes of the growing obesity epidemic in the Western society. The extension of human lifespan far beyond reproductive age increased the burden of metabolic disorders associated with overnutrition and age-related hypogonadism. Sex steroids are essential regulators of both reproductive function and energy metabolism, whereas their imbalance causes infertility, obesity, glucose intolerance, dyslipidemia, and increased appetite. Clinical and translational studies suggest that dietary restriction and weight control can improve metabolic and reproductive outcomes of sex hormone-related pathologies, including testosterone deficiency in men and natural menopause and hyperandrogenemia in women. Minimizing metabolic and reproductive decline through rationally designed diet and exercise can help extend human reproductive age and promote healthy aging. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Patatin-like phospholipase domain-containing protein 3 is involved in hepatic fatty acid and triglyceride metabolism through X-box binding protein 1 and modulation of endoplasmic reticulum stress in mice

AIM

Non-alcoholic steatohepatitis (NASH) is the major cause of chronic liver disease worldwide. Endoplasmic reticulum (ER) stress is considered to be an important pathological characteristic in NASH. A sequence variation (I148M) in the patatin-like phospholipase domain-containing protein 3/adiponutrin (PNPLA3) gene is known to be associated with the development of NASH. However, PNPLA3 deficiency has been considered to not be associated with fatty liver disease. To clarify, therefore, the role of PNPLA3 in liver, we established PNPLA3 knockout (KO) mice and investigated the phenotypes and involved factors under ER stress.

METHODS

ER stress was induced by i.p. injection with tunicamycin or with saline at 0 and 24 h in KO and C57BL/6 (wild-type [WT]) mice. At 48 h after the starting of treatment, blood and liver samples were studied.

RESULTS

Hepatic steatosis and triglyceride content were remarkably increased in WT mice than in KO mice under ER stress. The hepatic palmitate/oleate ratio was significantly higher originally in KO mice than in WT mice. Moreover, the expression of stearoyl-coenzyme A desaturase-1 (SCD1) in KO mice under ER stress was decreased further than that in WT mice. Expression of ER stress markers X-box binding protein 1 (XBP1) and ERdj4 was increased in WT mice but not in KO mice under ER stress.

CONCLUSION

We first demonstrated the hepatic phenotype of PNPLA3 deficiency under ER stress. Our observations would indicate that PNPLA3 has an important role in hepatic fatty acid metabolism and triglyceride accumulation through XBP1 under ER stress.

Potential serum biomarkers from a metabolomics study of autism

BACKGROUND

Early detection and diagnosis are very important for autism. Current diagnosis of autism relies mainly on some observational questionnaires and interview tools that may involve a great variability. We performed a metabolomics analysis of serum to identify potential biomarkers for the early diagnosis and clinical evaluation of autism.

METHODS

We analyzed a discovery cohort of patients with autism and participants without autism in the Chinese Han population using ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF MS/MS) to detect metabolic changes in serum associated with autism. The potential metabolite candidates for biomarkers were individually validated in an additional independent cohort of cases and controls. We built a multiple logistic regression model to evaluate the validated biomarkers.

RESULTS

We included 73 patients and 63 controls in the discovery cohort and 100 cases and 100 controls in the validation cohort. Metabolomic analysis of serum in the discovery stage identified 17 metabolites, 11 of which were validated in an independent cohort. A multiple logistic regression model built on the 11 validated metabolites fit well in both cohorts. The model consistently showed that autism was associated with 2 particular metabolites: sphingosine 1-phosphate and docosahexaenoic acid.

LIMITATIONS

While autism is diagnosed predominantly in boys, we were unable to perform the analysis by sex owing to difficulty recruiting enough female patients. Other limitations include the need to perform test-retest assessment within the same individual and the relatively small sample size.

CONCLUSION

Two metabolites have potential as biomarkers for the clinical diagnosis and evaluation of autism.

Liver lipid metabolism is altered by increased circulating estrogen to androgen ratio in male mouse

Estrogens are suggested to lower the risk of developing metabolic syndrome in both sexes. In this study, we investigated how the increased circulating estrogen-to-androgen ratio (E/A) alters liver lipid metabolism in males. The cytochrome P450 aromatase (P450arom) is an enzyme converting androgens to estrogens. Male mice overexpressing human aromatase enzyme (AROM+ mice), and thus have high circulating E/A, were used as a model in this study. Proteomics and gene expression analyses indicated an increase in the peroxisomal β-oxidation in the liver of AROM+ mice as compared with their wild type littermates. Correspondingly, metabolomic analysis revealed a decrease in the amount of phosphatidylcholines with long-chain fatty acids in the plasma. With interest we noted that the expression of Cyp4a12a enzyme, which specifically metabolizes arachidonic acid (AA) to 20-hydroxy AA, was dramatically decreased in the AROM+ liver. As a consequence, increased amounts of phospholipids having AA as a fatty acid tail were detected in the plasma of the AROM+ mice. Overall, these observations demonstrate that high circulating E/A in males is linked to indicators of higher peroxisomal β-oxidation and lower AA metabolism in the liver. Furthermore, the plasma phospholipid profile reflects the changes in the liver lipid metabolism.

Upregulation of miR-125b by estrogen protects against non-alcoholic fatty liver in female mice

BACKGROUND & AIMS

Due to the protective effect of estrogen against hepatic fat accumulation, the prevalence of non-alcoholic fatty liver disease (NAFLD) in premenopausal women is lower than that in men at the same age and in postmenopausal women. Our study was to further elucidate an underlying mechanism by which estrogen prevents NAFLD from miRNA perspective in female mice.

METHODS

miRNA expression was evaluated by TaqMan miRNA assay. Luciferase and ChIP assay were done to validate regulation of miR-125b by estrogen via estrogen receptor alpha (ERα). Nile red and Oil red O staining were used to check lipid content. Overexpressing or inhibiting the physiological role of miR-125b in the liver of mice through injecting adenovirus were used to identify the function of miR-125b in vivo.

RESULTS

miR-125b expression was activated by estrogen via ERα in vitro and in vivo. miR-125b inhibited lipid accumulation both in HepG2 cells and primary mouse hepatocytes. Consistently, ovariectomized or liver-specific ERα knockdown mice treated with miR-125b overexpressing adenoviruses were resistant to hepatic steatosis induced by high-fat diet, due to decreased fatty acid uptake and synthesis and decreased triglyceride synthesis. Conversely, inhibiting the physiological role of miR-125b with a sponge decoy slightly promoted liver steatosis with a high-fat diet. Notably, we provided evidence showing that fatty acid synthase was a functional target of miR-125b.

CONCLUSION

Our findings identify a novel mechanism by which estrogen protects against hepatic steatosis in female mice via upregulating miR-125b expression.

Prevention of hyperphagia prevents ovariectomy-induced triacylglycerol accumulation in liver, but not plasma

Menopause is associated with higher plasma and liver triacylglycerol (TAG) and increased risk for cardiovascular disease. Lowering TAG in menopause may be beneficial; however, the mechanism underlying menopause-induced TAG accumulation is not clear. Ovariectomy is a model for menopause and is associated with metabolic alterations and hyperphagia. This study investigated the role of hyperphagia in ovariectomy-induced increases in blood and tissue TAG, as well as differences in lipid metabolism enzymes and resting metabolic measures. It was hypothesized that prevention of hyperphagia would restore blood and tissue TAG, enzyme expression, and metabolic measures to eugonadal levels. Ovariectomized rats were fed ad libitum (OVX + AL) or pair-fed (OVX + PF) relative to sham-operated rats (SHAM) to prevent hyperphagia. OVX + AL had higher TAG concentrations in liver and plasma than SHAM (60% and 50%, respectively), and prevention of hyperphagia in OVX + PF normalized TAG concentrations to SHAM levels in liver, but not plasma. OVX + AL also had 141% higher hepatic stearoyl-CoA desaturase 1 which was almost completely normalized to SHAM levels by pair-feeding, suggesting normalization of hepatic lipid storage. In contrast, skeletal muscle carnitine palmitoyl transferase 1 was 40% lower in OVX + AL than SHAM and was intermediate in OVX + PF, suggesting lower muscle fatty acid oxidation that may underlie the higher plasma TAG in OVX. No differences were seen in energy expenditure, VO2, or VCO2. Overall, this study indicates that prevention of hyperphagia resulting from ovarian hormone withdrawal normalizes hepatic TAG to eugonadal levels but has no effect on ovariectomy-induced increases in plasma TAG.

The influence of metabolic factors for nonalcoholic Fatty liver disease in women

Background/Aims. Women after menopause have increased insulin resistance and visceral fat, which may increase the prevalence of nonalcoholic fatty liver disease (NAFLD). However, the pathogenesis of NAFLD in women has not been clearly defined. In this study, we aimed to determine the risk factors for NAFLD in women. Methods. A retrospective cohort study was conducted. Women who underwent abdominal ultrasonography and blood sampling for routine health check-ups were recruited. Results. Among 1,423 subjects, 695 women (48.9%) were in a menopausal state. The prevalence of NAFLD was higher in postmenopausal women than in premenopausal women (27.2% versus 14.4%, P < 0.001). In premenopausal women, low HDL-cholesterol, central obesity, and homeostasis model assessment-estimated insulin resistance showed a significant association with the increased risk of NAFLD in multivariate analysis. In postmenopausal women, the presence of diabetes, triglyceridemia, and central obesity showed a significant association with the risk of NAFLD. The presence of menopause and hormone replacement therapy in postmenopausal women were not risk factors for NAFLD. Conclusions. Our findings showed different metabolic factors for NAFLD in pre- and postmenopausal women. However, the key issues are the same: central obesity and insulin resistance. These results reemphasize the importance of metabolic factors irrespective of menopausal status in the pathogenesis of NAFLD in women.

Aromatase deficiency in a Chinese adult man caused by novel compound heterozygous CYP19A1 mutations: effects of estrogen replacement therapy on the bone, lipid, liver and glucose metabolism

OBJECTIVES

Aromatase deficiency is a rare disorder resulting in estrogen insufficiency in humans. It has been reported in remarkably few men with loss-of-function mutations in the CYP19A1 gene encoding the aromatase, a cytochrome P450 enzyme that plays a crucial role in the biosynthesis of estrogens from androgens. We investigated a non-consanguineous family including an adult man with clinical features of aromatase deficiency, and studied the effects of estrogen replacement in the man.

METHODS

We investigated the clinical and biochemical phenotype, performed CYP19A1 mutational analysis in the family and 50 unrelated persons, studied the effects of CYP19A1 mutations on aromatase protein structure, functionally characterized the mutations by cell-based aromatase activity assays, and studied the effects of estrogen replacement on the bone, lipid, liver and glucose metabolism.

RESULTS

The man with clinical features of aromatase deficiency had novel compound heterozygous CYP19A1 mutations (Y81C and L451P) that were not found in 50 unrelated persons. Three-dimensional modeling predicted that Y81C and L451P mutants disrupted protein structure. Functional studies on the basis of in vitro expression showed that Y81C and L45P mutants significantly decreased the aromatase activity and catalytic efficiency. Estrogen replacement in the man increased bone mineral density, accelerated bone maturation, improved lipid profile and liver steatosis, and improved glucose levels but not insulin resistance.

CONCLUSIONS

We have identified two novel CYP19A1 missense mutations in an aromatase-deficient man. Estrogen replacement in the man shows great impact on recovering the impairments in the bone, lipid, liver and glucose metabolism, but fails to improve insulin resistance.

Sex Hormones and Their Receptors Regulate Liver Energy Homeostasis

The liver is one of the most essential organs involved in the regulation of energy homeostasis. Hepatic steatosis, a major manifestation of metabolic syndrome, is associated with imbalance between lipid formation and breakdown, glucose production and catabolism, and cholesterol synthesis and secretion. Epidemiological studies show sex difference in the prevalence in fatty liver disease and suggest that sex hormones may play vital roles in regulating hepatic steatosis. In this review, we summarize current literature and discuss the role of estrogens and androgens and the mechanisms through which estrogen receptors and androgen receptors regulate lipid and glucose metabolism in the liver. In females, estradiol regulates liver metabolism via estrogen receptors by decreasing lipogenesis, gluconeogenesis, and fatty acid uptake, while enhancing lipolysis, cholesterol secretion, and glucose catabolism. In males, testosterone works via androgen receptors to increase insulin receptor expression and glycogen synthesis, decrease glucose uptake and lipogenesis, and promote cholesterol storage in the liver. These recent integrated concepts suggest that sex hormone receptors could be potential promising targets for the prevention of hepatic steatosis.

Estrogen signaling in metabolic inflammation

There is extensive evidence supporting the interference of inflammatory activation with metabolism. Obesity, mainly visceral obesity, is associated with a low-grade inflammatory state, triggered by metabolic surplus where specialized metabolic cells such as adipocytes activate cellular stress initiating and sustaining the inflammatory program. The increasing prevalence of obesity, resulting in increased cardiometabolic risk and precipitating illness such as cardiovascular disease, type 2 diabetes, fatty liver, cirrhosis, and certain types of cancer, constitutes a good example of this association. The metabolic actions of estrogens have been studied extensively and there is also accumulating evidence that estrogens influence immune processes. However, the connection between these two fields of estrogen actions has been underacknowledged since little attention has been drawn towards the possible action of estrogens on the modulation of metabolism through their anti-inflammatory properties. In the present paper, we summarize knowledge on the modification inflammatory processes by estrogens with impact on metabolism and highlight major research questions on the field. Understanding the regulation of metabolic inflammation by estrogens may provide the basis for the development of therapeutic strategies to the management of metabolic dysfunctions.