Independent and combined effects of dietary iron composition and selected risk factors on the risk of NAFLD in a Chinese population

Ferroptosis in non-alcoholic liver disease: Molecular mechanisms and therapeutic implications

Ferroptosis refers to a novel modality of regulated cell death characterized by excessive iron accumulation and overwhelming lipid peroxidation, which takes an important part in multiple pathological processes associated with cell death. Considering the crucial roles of the liver in iron and lipid metabolism and its predisposition to oxidative insults, more and more studies have been conducted to explore the relationship between ferroptosis and various liver disorders, including non-alcoholic fatty liver disease (NAFLD). With increased morbidity and high mortality rates, NAFLD has currently emerged as a global public health issue. However, the etiology of NAFLD is not fully understood. In recent years, an accumulating body of evidence have suggested that ferroptosis plays a pivotal role in the pathogenesis of NAFLD, but the precise mechanisms underlying how ferroptosis affects NAFLD still remain obscure. Here, we summarize the molecular mechanisms of ferroptosis and its complicated regulation systems, delineate the different effects that ferroptosis exerts in different stages of NAFLD, and discuss some potential effective therapies targeting ferroptosis for NAFLD treatment, which putatively points out a novel direction for NAFLD treatment.

Genetic variants in promoter region of TFR2 is associated with the risk of non-alcoholic fatty liver disease in a Chinese Han population: a case-control study

Background

Iron overload is frequently observed in non-alcoholic fatty liver disease (NAFLD). Transferrin receptor 2 (TFR2) is an important key factor in iron regulation. We aimed to investigate whether TFR2 single nucleotide polymorphisms (SNPs) contribute to susceptibility to NAFLD in a Chinese Han population.

Methods

Five tag SNPs (rs10247962, rs4434553, rs2075672, rs1052897, and rs3757859) in the TFR2 gene were selected and genotyped in a case–control study on participants who visited two affiliated hospitals of Fujian Medical University between June 2011 and August 2017. Propensity score matching and inverse probability of treatment weighting analyses were used to verify the risk associated with TFR2 SNPs.

Results

Logistic regression analyses suggested that subjects with the rs4434553 GA or GG genotype had a lower risk of NAFLD than those carrying the AA genotype (odds ratio = 0.630, 95% confidence interval = 0.504–0.788). Moreover, the rs4434553 GA or GG genotype was negatively correlated with body mass index, hepatic steatosis index, and serum ferritin (b = −0.363, P = 0.008; b = −1.040, P = 0.009; b = −35.258, P = 0.015, respectively), and positively associated with serum hepcidin level (b = 35.308, P < 0.001). Moreover, rs10247962 and rs1052897 had multiplicative interactions with age in relation to the risk of NAFLD (P for interactions, 0.041 and 0.034, respectively). The cumulative effects of the rs10247962, rs1052897, and rs4434553 SNPs were positively associated with the risk of NAFLD (adjusted P_trend = 0.012).

Conclusions

In this Chinese Han population, the rs4434553 polymorphism in TFR2 may be an independent influencing factor associated with the susceptibility to NAFLD. The ageing effect on the development of NAFLD may be inhibited by SNPs rs10247962 and rs1052897.

Mineral metabolism and ferroptosis in non-alcoholic fatty liver diseases

Nonalcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease worldwide. Minerals including iron, copper, zinc, and selenium, fulfil an essential role in various biochemical processes. Moreover, the identification of ferroptosis and cuproptosis further underscores the importance of intracellular mineral homeostasis. However, perturbation of minerals has been frequently reported in patients with NAFLD and related diseases. Interestingly, studies have attempted to establish an association between mineral disorders and NAFLD pathological features, including oxidative stress, mitochondrial dysfunction, inflammatory response, and fibrogenesis. In this review, we aim to provide an overview of the current understanding of mineral metabolism (i.e., absorption, utilization, and transport) and mineral interactions in the pathogenesis of NAFLD. More importantly, this review highlights potential therapeutic strategies, challenges, future directions for targeting mineral metabolism in the treatment of NAFLD.

Paying the Iron Price: Liver Iron Homeostasis and Metabolic Disease

Iron is an essential metal element whose bioavailability is tightly regulated. Under normal conditions, systemic and cellular iron homeostases are synchronized for optimal function, based on the needs of each system. During metabolic dysfunction, this synchrony is lost, and markers of systemic iron homeostasis are no longer coupled to the iron status of key metabolic organs such as the liver and adipose tissue. The effects of dysmetabolic iron overload syndrome in the liver have been tied to hepatic insulin resistance, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. While the existence of a relationship between iron dysregulation and metabolic dysfunction has long been acknowledged, identifying correlative relationships is complicated by the prognostic reliance on systemic measures of iron homeostasis. What is lacking and perhaps more informative is an understanding of how cellular iron homeostasis changes with metabolic dysfunction. This article explores bidirectional relationships between different proteins involved in iron homeostasis and metabolic dysfunction in the liver. © 2022 American Physiological Society. Compr Physiol 12:3641-3663, 2022.

Multi-echo Dixon and breath-hold T2-corrected multi-echo single-voxel MRS for quantifying hepatic iron overload in rabbits

BACKGROUND

Three-dimensional (3D) multi-echo-Dixon (ME-Dixon) and breath-hold T2-corrected multi-echo single-voxel MR spectroscopy (HISTO) can simultaneously quantify liver fat and liver iron. However, their diagnostic efficacy and application scope for quantitative iron in co-existing fatty liver have not been adequately evaluated.

PURPOSE

To evaluate the accuracy of ME-Dixon and HISTO for quantitative analysis of hepatic iron in rabbits with iron deposition and fatty liver using liver-iron concentration (LIC) as a reference standard.

MATERIAL AND METHODS

ME-Dixon, HISTO, and conventional two-dimensional multi-echo gradient echo (GRE) sequences were performed on 42 rabbits. The following parameters were calculated: R2* from ME-Dixon and GRE; proton density fat fraction (PDFF) from the ME-Dixon, HISTO (normal TE range), and HISTO-H (extended TE range); and R2_water from HISTO and HISTO-H. The LIC and liver-fat concentration (LFC) were measured through chemical analysis, and their relationship with the MRI parameters were assessed. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were used to evaluate the diagnostic efficiency.

RESULTS

LIC was significantly correlated with R2_HISTO-H, R2*_Dixon, and R2*_GRE (r = 0.858, 0.910, 0.931, respectively; P < 0.001) and weakly with R2_HISTO (r = 0.424; P = 0.008). A strong correlation was also observed between the LFC and PDFF obtained from HISTO, HISTO-H, and ME-Dixon (r = 0.776, 0.811, 0.888, respectively; P < 0.001). ME-Dixon showed the best performance with moderate iron overload (AUC = 0.983).

CONCLUSION

3D ME-Dixon is useful for quantifying the LIC, especially with co-existing fatty liver. Its diagnostic performance is also superior to that of the HISTO sequence.

Serum ferritin is correlated with non-alcoholic fatty liver disease in middle-aged and older patients with type 2 diabetes

OBJECTIVE

Previous studies have shown the correlations between serum ferritin and non-alcoholic fatty liver disease (NAFLD) or diabetes. However, this relationship remains unclear in patients with type 2 diabetes (T2DM) with NAFLD. Therefore, this study aimed to elaborate the relationship between serum ferritin levels and NAFLD in middle-aged and older patients with T2DM and further explored the biomarkers for NAFLD in T2DM.

METHODS

A total of 805 middle-aged and older patients with T2DM were divided into NAFLD and non-NAFLD groups, and their serum ferritin levels were compared. Next, NAFLD group were divided into five subgroups according to the quintile levels of serum ferritin, and the differences in the constituent ratios of NAFLD were analyzed. A logistic regression analysis was performed to determine the risk factors for NAFLD in patients with T2DM.

RESULTS

The serum ferritin levels were significantly higher in T2DM patients with NAFLD (168.47 (103.78, 248.00) ng/mL) than in the non-NAFLD patients (121.19 (76.97, 208.39) ng/mL). The constituent ratios of NAFLD were significantly higher in the F5 and F4 groups than in the F2 or F1 groups (22.70 and 22.70% vs. 15.90 and 16.90%, respectively; P < 0.05). Binary logistic regression analysis showed that serum ferritin (P = 0.001) was an independent risk factor for NAFLD in patients with T2DM.

CONCLUSIONS

Serum ferritin levels were significantly increased in T2DM with NAFLD, and the constituent ratios of NAFLD increased gradually along with the increased levels of serum ferritin. Thus, serum ferritin is an independent risk factor for NAFLD in patients with T2DM.

Associations between Phase Angle Values Obtained by Bioelectrical Impedance Analysis and Nonalcoholic Fatty Liver Disease in an Overweight Population

OBJECTIVE

There is a limited diagnosis of nonalcoholic fatty liver disease (NAFLD). Thus, the noninvasive assessments are worth exploring. We determined the associations of phase angles (PhAs) obtained from bioelectric impedance analysis (BIA) with the risk of NAFLD in an overweight population.

METHODS

A study involving 953 overweight participants was conducted in Wuhan city, China. The associations between PhAs (right arm, left arm, body trunk, right leg, left leg, and whole body) and the risk of NAFLD were conducted using multivariate logistic regression analyses. The associations of PhAs with the controlled attenuation parameter (CAP), a noninvasive assessment of liver steatosis and fibrosis, were also evaluated by both linear and logistic regression analyses.

RESULTS

The PhA values of the whole body, trunk, and legs were significantly lower (P < 0.05) in the NAFLD group than the non-NAFLD group. After adjustment for BMI, gender, education, income/year, hyperlipidemia, hypertension, diabetes, smoking, passive smoking, and drinking, significant associations of PhA values of the right leg, left leg, and whole body with the risk of NAFLD were observed. In addition, the PhA of the right leg, left leg, and whole body were significantly related to the CAP values. Further stratified analyses indicated that these associations were significant in the participants with BMI <30, but not in the participants with BMI ≥30.

CONCLUSIONS

PhAs might be effective indicators in the management of NAFLD among overweight people.

Association between Different Animal Protein Sources and Liver Status in Obese Subjects with Non-Alcoholic Fatty Liver Disease: Fatty Liver in Obesity (FLiO) Study

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome. Obesity and unhealthy dietary habits are described as risk factors for NAFLD. The aim of this study was to investigate the association between the consumption of different animal protein sources and hepatic status in NAFLD adults. A total of 112 overweight/obese participants with NAFLD from Fatty Liver in Obesity (FLiO) study were evaluated at baseline. Diet, body composition, and biochemical variables were evaluated. Hepatic status was also assessed by Magnetic Resonance Imaging, ultrasonography, and elastography. Red meat consumption showed a positive relationship with liver iron content (r = 0.224; p = 0.021) and ferritin concentration (r = 0.196; p = 0.037). Processed meat consumption exhibited a positive association with liver iron content (r = 0.308; p = 0.001), which was also found in the quantile regression (β = 0.079; p = 0.028). Fish consumption was related with lower concentration of ferritin (r = -0.200; p = 0.034). This association was further evidenced in the regression model (β = -0.720; p = 0.033). These findings suggest that the consumption of different animal protein sources differentially impact on liver status in obese subjects with NAFLD, showing fish consumption as a healthier alternative for towards NAFLD features.