Liver fibrosis in fish research: From an immunological perspective

Metal concentrations, oxidative status and histopathological evaluation of fish species from Doce River, Brazil, after the Fundao dam collapse

Eight years after the tailings dam collapse in Mariana, MG, Brazil, several aspects of this massive disaster are yet to be elucidated. Our goal was to investigate the impact of the mud flow on 16 fish species collected across 15 points from the Doce River, addressing 12 metal concentrations, tissue oxidative status (antioxidant enzymes and stress biomarkers), and histopathological analyses. The species Trachelyopterus striatulus, Prochilodus vimboides, Loricariichthys castaneus, Lophiosilurus alexandri, Hypostomus affinis, Hoplias intermedius were shown to be the most affected regarding the gills tissue integrity; Hypostomus affinis, Oligosarcus acutirostris, Lophiosilurus alexandri, Pygocentrus nattereri, Hoplosternum littorale, and Loricariichthys castaneus showed the highest levels of liver health. Overall, H. affinis was the most affected species, showing high levels of oxidative and histopathological damage, associated with high arsenic (As) and mercury (Hg) concentrations. In fish sampled from impacted regions, As and Hg exhibited higher concentrations compared to fish from unaffected sites, surpassing all the other analyzed metals. These high metal concentrations might be associated to the tailings dam failure, and As and Hg concentrations were positively correlated with alterations in oxidative stress biomarkers and histopathologies. Our results may be used as baseline for monitoring the environmental challenges that the Doce River fish species are facing at the moment.

Incorporating Lycium barbarum residue in diet boosts survival, growth, and liver health in juvenile grass carp (Ctenopharyngodon idellus)

This research elucidates the potential of Lycium barbarum residue (LBR), a by-product rich in bioactive substances, as a dietary supplement in aquaculture, especially for herbivorous fish like grass carp. In a detailed 120-day feeding trial, the impacts of varying LBR levels on juvenile grass carp were assessed, focusing on growth performance, survival rate, biochemical markers, and liver health. The study identified a 6% inclusion rate of LBR as optimal for enhancing survival and growth while mitigating hepatic lipid accumulation. Composition analysis of this diet revealed high concentrations of polysaccharides and flavonoids. Notably, the intake of LBR was found to enhance the antioxidant and immune-related enzymatic activities in the liver. Furthermore, it contributed to a reduction in hepatic fat deposition by decreasing the levels of triglycerides (TG) and total cholesterol (T-CHO) both in the liver and serum. Transcriptomic analysis of the liver highlighted LBR's substantial influence on lipid metabolism pathways, including the PPAR signaling pathway, primary bile acid biosynthesis, cholesterol metabolism, bile secretion, fat digestion and absorption, fatty acid degradation and fatty acid biosynthesis. Further, the expression level of genes pinpointed significant downregulation of fasn and dgat2, alongside upregulation of genes like pparda, cpt1b, cpt1ab and abca1b, in response to LBR supplementation. Overall, the findings present LBR as a promising enhancer of growth and survival in grass carp, with significant benefits in promoting fat metabolism and liver health, offering valuable insights for aquacultural nutrition strategies.

Inhibitory Effects of Jiuzao Polysaccharides on Alcoholic Fatty Liver Formation in Zebrafish Larvae and Their Regulatory Impact on Intestinal Microbiota

The liver is critical in alcohol metabolism, and excessive consumption heightens the risk of hepatic damage, potentially escalating to hepatitis and cirrhosis. Jiuzao, a by-product of Baijiu production, contains a rich concentration of naturally active polysaccharides known for their antioxidative properties. This study investigated the influence of Laowuzeng Jiuzao polysaccharide (LJP) on the development of ethanol-induced alcoholic fatty liver. Zebrafish larvae served as the model organisms for examining the LJPs hepatic impact via liver phenotypic and biochemical assays. Additionally, this study evaluated the LJPs effects on gene expression associated with alcoholic fatty liver and the composition of the intestinal microbiota through transcriptomic and 16 S rRNA gene sequencing analyses, respectively. Our findings revealed that LJP markedly mitigated morphological liver damage and reduced oxidative stress and lipid peroxidation in larvae. Transcriptome data indicated that LJP ameliorated hepatic fat accumulation and liver injury by enhancing gene expression involved in alcohol and lipid metabolism. Furthermore, LJP modulated the development of alcoholic fatty liver by altering the prevalence of intestinal Actinobacteriota and Firmicutes, specifically augmenting Acinetobacter while diminishing Chryseobacterium levels. Ultimately, LJP mitigated alcohol-induced hepatic injury by modulating gene expression related to ethanol metabolism, lipid metabolism, and inflammation and by orchestrating alterations in the intestinal microbiota.