MCD Diet Rat Model Induces Alterations in Zinc and Iron during NAFLD Progression from Steatosis to Steatohepatitis

Association between serum trace element, mineral, and amino acid levels with non-alcoholic fatty liver disease (NAFLD) in adult women

The objective of the present study is assessment of serum trace element and amino acid levels in non-alcoholic fatty liver disease (NAFLD) patients with subsequent evaluation of its independent associations with markers of liver injury and metabolic risk.

MATERIALS AND METHODS

140 women aged 20-90 years old with diagnosed NAFLD and 140 healthy women with a respective age range were enrolled in the current study. Analysis of serum and hair levels of trace elements and minerals was performed with inductively-coupled plasma mass-spectrometry (ICP-MS). Serum amino acid concentrations were evaluated by high-pressure liquid chromatography (HPLC) with UV-detection. In addition, routine biochemical parameters including liver damage markers, alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT), were assessed spectrophotometrically.

RESULTS

The findings demonstrated that patients with NAFLD were characterized by higher ALT, GGT, lactate dehydrogenase (LDH) and cholinesterase (CE) activity, as well as increased levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and uric acid. NAFLD patients were characterized by reduced serum and hair Co, Se, and Zn levels, as well as hair Cu content and serum Mn concentrations in comparison to controls. Circulating Ala, Cit, Glu, Gly, Ile, Leu, Phe, and Tyr levels in NAFLD patients exceeded those in the control group. Multiple linear regression demonstrated that serum and hair trace element levels were significantly associated with circulating amino acid levels after adjustment for age, BMI, and metabolic parameters including liver damage markers.

CONCLUSION

It is proposed that altered trace element handling may contribute to NAFLD pathogenesis through modulation of amino acid metabolism.

Recent Updates on the Therapeutic Prospects of Reversion-Inducing Cysteine-Rich Protein with Kazal Motifs (RECK) in Liver Injuries

The reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a membrane-anchored glycoprotein, negatively regulates various membrane proteins involved in the tissue governing extracellular matrix (ECM) remodeling such as metalloproteases (MMPs) and the sheddases ADAM10 and ADAM17. The significance of the present review is to summarize the current understanding of the pathophysiological role of RECK, a newly discovered signaling pathway associated with different liver injuries. Specifically, this review analyzes published data on the downregulation of RECK expression in hepatic ischemia/reperfusion (I/R) injury, liver-related cancers, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), as well as in the progression of nonalcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis (NASH). In addition, this review discusses the regulation of RECK by inducers, such as FXR agonists. The RECK protein has also been suggested as a potential diagnostic and prognostic marker for liver injury or as a biomarker with predictive value for drug treatment efficacy.

Deconvolution of the fluorescence spectra measured through a needle probe to assess the functional state of the liver

OBJECTIVES

Currently, one of the most pressing issues for surgeons in the treatment of obstructive jaundice is the ability to assess the functional state of the liver and to detect and determine the degree of liver failure in a timely manner with simple and objective techniques. In this regard, the use of fluorescence spectroscopy method can be considered as one of the ways to improve the informativity of existing diagnostic algorithms in clinical practice and to introduce new diagnostic tools. Thus, the aim of the work was to study in vivo the functional state of liver parenchyma by the method of fluorescence spectroscopy implemented through a needle probe and assess the contribution of the main tissue fluorophores to reveal new diagnostic criteria.

MATERIALS AND METHODS

We compared data from 20 patients diagnosed with obstructive jaundice and 11 patients without this syndrome. Measurements were performed using a fluorescence spectroscopy method at excitation wavelengths of 365 and 450 nm. Data were collected using a 1 mm fiber optic needle probe. The analysis was based on the comparison of the results of deconvolution with the combinations of Gaussian curves reflecting the contribution of the pure fluorophores in the liver tissues.

RESULTS

The results showed a statistically significant increase in the contribution of curves reflecting NAD(P)H fluorescence, bilirubin, and flavins in the group of patients with obstructive jaundice. This and the calculated redox ratio values indicated that the energy metabolism of the hepatocytes may have shifted to glycolysis due to hypoxia. An increase in vitamin A fluorescence was also observed. It may also serve as a marker of liver damage, indicating impaired vitamin A mobilization from the liver due to cholestasis.

CONCLUSIONS

The results obtained reflect changes associated with shifts in the content of the main fluorophores characterizing hepatocyte dysfunction caused by accumulation of bilirubin and bile acids and after disturbance of oxygen utilization. The contributions of NAD(P)H, flavins, and bilirubin as well as vitamin A can be used for further studies as promising diagnostic and prognostic markers for the course of liver failure. Further work will include collecting fluorescence spectroscopy data in patients with different clinical effects of obstructive jaundice on postoperative clinical outcome after biliary decompression.

Icariin Supplementation Suppresses the Markers of Ferroptosis and Attenuates the Progression of Nonalcoholic Steatohepatitis in Mice Fed a Methionine Choline-Deficient Diet

Icariin, a flavonoid abundant in the herb Epimedium, exhibits anti-ferroptotic activity. However, its impact on nonalcoholic steatohepatitis (NASH) development remains unclear. This study aimed to investigate the potential role of icariin in mitigating methionine choline-deficient (MCD) diet-induced NASH in C57BL/6J mice. The results showed that icariin treatment significantly reduced serum alanine aminotrasferase and aspartate aminotransferase activities while improving steatosis, inflammation, ballooning, and fibrosis in the liver tissues of mice fed the MCD diet. These improvements were accompanied by a substantial reduction in the hepatic iron contents and levels of malondialdehyde and 4-hydroxynonenal, as well as an increase in the activities of catalase and superoxide dismutase. Notably, icariin treatment suppressed the hepatic protein levels of ferroptosis markers such as acyl-CoA synthetase long-chain family member 4 and arachidonate 12-lipoxygenase, which were induced by the MCD diet. Furthermore, transmission electron microscopy confirmed the restoration of morphological changes in the mitochondria, a hallmark characteristic of ferroptosis, by icariin. Additionally, icariin treatment significantly increased the protein levels of Nrf2, a cystine/glutamate transporter (xCT), and glutathione peroxidase 4 (GPX4). In conclusion, our study suggests that icariin has the potential to attenuate NASH, possibly by suppressing ferroptosis via the Nrf2-xCT/GPX4 pathway.

MCD Diet Modulates HuR and Oxidative Stress-Related HuR Targets in Rats

The endogenous antioxidant defense plays a big part in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), a common metabolic disorder that can lead to serious complications such as cirrhosis and cancer. HuR, an RNA-binding protein of the ELAV family, controls, among others, the stability of MnSOD and HO-1 mRNA. These two enzymes protect the liver cells from oxidative damage caused by excessive fat accumulation. Our aim was to investigate the expression of HuR and its targets in a methionine-choline deficient (MCD) model of NAFLD. To this aim, we fed male Wistar rats with an MCD diet for 3 and 6 weeks to induce NAFLD; then, we evaluated the expression of HuR, MnSOD, and HO-1. The MCD diet induced fat accumulation, hepatic injury, oxidative stress, and mitochondrial dysfunction. A HuR downregulation was also observed in association with a reduced expression of MnSOD and HO-1. Moreover, the changes in the expression of HuR and its targets were significantly correlated with oxidative stress and mitochondrial injury. Since HuR plays a protective role against oxidative stress, targeting this protein could be a therapeutic strategy to both prevent and counteract NAFLD.

Characterization of Spontaneous Melanization by Fluorescence Spectroscopy: A Basis for Analytical Application to Biological Substrates

Melanin is present in various biological substrates where it may participate in several processes, from innate immunity to the still-unsolved opposite roles in antioxidant protection, including photoprotection and the related ability to interact with light. Melanin–light interaction has also been an important source of inspiration for the development of innovative bioengineering applications. These are based on melanin’s light-energy-absorption ability of its chemically and structurally complex components and precursors, and on the improvement in analytical and diagnostic procedures in biomedicine. In this regard, here, we characterized the fluorescence spectral properties of melanin and of its precursor L-tyrosine in an aqueous solution during spontaneous melanization. Besides the confirmation of the typical fluorescence-emission signature of melanin and L-tyrosine, we provide additional insights on both emission and excitation spectra recorded during melanization. On these bases, we performed a subsequent characterization on the aqueous extracts from two different melanin-containing biological substrates, namely hairs from a domestic black cat and eggs from the Asian tiger mosquito. The results from the mild extraction procedure, purposely applied to obtain only the soluble components, combined with fluorescence spectral analysis are expected to promote further investigation of the melanization processes, particularly in insects.