NASH is characterized by the accumulation of modified lipoproteins and elevated oxidative stress levels, leading to the accumulation of ROS. Inflammatory cytokines, adiponectin, leptin, and endotoxins all contribute to NASH by directly or indirectly causing undesirable outcomes such as inflammation, cholesterol accumulation, and endothelial dysfunction in local tissues and organs. Cells experience oxidative stress when ROS production exceeds the capacity of their natural antioxidant defences. UA, as an antioxidant, is a formidable weapon in the fight against the overproduction of ROS mounted by cells [22, 23].
The results of functional analyses demonstrated that the DEGs found in the FFA and CTR groups in the current study were enriched in the mitochondria, endoplasmic reticulum stress, and NADPH oxidase-related pathways. Inflammation and immunological dysfunction in the liver would result from hepatocyte damage and death caused by lipotoxicity, oxidative stress, mitochondrial malfunction, and endoplasmic reticulum stress. Several studies have indicated that mitochondrial repair is an effective treatment for fatty liver disease caused by metabolic dysfunction [24, 25]. A lot of research has been conducted on endoplasmic reticulum stress [26, 27], yet there is still a need for further exploration of certain novel aspects. Here, we found that changes in fatty acid and steroid metabolic processes were substantially linked with gene expression presentation between the two groups. we observed that alterations in insulin sensitivity, as well as changes in the expression and activity of key enzymes involved in lipid metabolism, contributed to a result of increased ROS formation. Previous research has confirmed that the interaction between redox signalling and innate immune signalling generates a complex network that modulates inflammatory responses, which is essential for maintaining cellular homeostasis [28]. We speculate that these pathways appeared to be strongly associated with NASH development and future research is warranted to assess the other pathways related to NASH.
The impact of UA on obesity [29], energy expenditure [30], hepatic steatosis [11], skeletal muscle mass loss, and physical fitness [31], indicates that supplementation with UA may be an adjunctive therapy for the prevention and treatment of obesity-mediated and muscle mass-mediated metabolic consequences. Our study indicated that differences in gene expression between the FFA and FUA groups were also strongly correlated with variations in metabolic pathways and PPAR signalling pathways. This finding suggests that UA is involved in cellular homeostasis and may relieve oxidative stress caused by an imbalance between the synthesis of antioxidants and free radicals. Considering our research, intragastric administration of UA may significantly modulate oxidative stress injury and inflammation to provide dual protective activities against metabolic dysfunction. Alterations in metabolic pathways, such as lipid metabolism, energy metabolism, and amino acid metabolism, may help explain how UA successfully delivers the therapeutic impact of NASH therapy. Here, we demonstrated that UA might inhibit or normalize the transformation of certain metabolic pathways to varying degrees.
Next in our study, WGCNA in 12 specimens produced 10 modules, the bright green and magenta modules being most strongly linked with weight. The result showed that the two modules contained two KEGG pathways, fatty acid metabolism and negative control of hydrolyse metabolism. According to pathway analysis, cytokines and inflammatory response were elevated. Numerous variables are now recognised to contribute to the development of NASH. The findings of this study revealed that UA had strong hepatic protective efficacy and excellent stability for treating alcohol-mediated oxidative stress damage in hepatocytes. The NASH-associated genes were identified using integrative genomic analysis. In addition to the well-known fatty acid metabolism [32], glucose and lipid metabolism [33] and PPAR signalling pathways [34], bioinformatics results revealed that a balance between boosting and reducing oxidative stress might be involved in the therapeutic effects of UA on NASH. This conclusion was consistent with Wang’s findings [35]. Additionally, the mechanism by which UA protected oxidative stress damage was related to its ability to modulate the expression of genes in the hydrolysed metabolism pathway, which in turn inhibited the creation of ROS. These findings suggested that UA supplementation might reduce the harm caused by oxidative stress caused by HFD and serve as a protective measure against HFD-mediated hepatocyte damage.
Multiple studies have revealed genes that may be related to the development and prognosis of NASH in recent years [36, 37]. In our study, three candidate genes are singled out.Akr1a1, a new mammalian S-nitroso-glutathione reductase (GSNO), is associated with chronic hepatitis and hepatocellular carcinoma [38]. It is primarily responsible for NADPH-dependent GSNO reductase activity in the liver [39]. Akr1a1 may catalyze the reduction of several aromatic and medium-chain aliphatic aldehydes to their respective alcohols [40]. Based on our findings, Akr1a1 plays an essential role in hepatic metabolism. The target gene Ndufb9, an accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (complex I) in the intervention oxidative phosphorylation signalling pathway, improves NSAH energy metabolism. Our results were consistent with Shenglong Zhu’s finding that Ndufb9 unveils the NDUFB9-SCD1 pathway and highlighted the potentially important role of Complex I in adipogenesis [41]. Ndufb9 is upregulated during adipogenesis and UA probably improves energy metabolism by intervening with the target gene Ndufb9. Chchd2 is a member of the mitochondrial CHCH domain protein family to maintain the stability of oxidative phosphorylation (OXPHOS) to monitor mitochondrial function [42]. Purandare’s teamwork indicated that the knockout of Chchd2 increases ROS levels within the cell field [43], which showed the relevance of Chchd2 as an important function of maintaining hepatocytes in their normal biological conditions and Chchd2, together with Bcl-xL and cytochrome C, is an apoptotic inhibitor. Regarding the pathological process of NASH and previous assumptions [44], extreme mitochondrial dysfunction and hepatocyte apoptosis are a hallmark of most hepatic diseases [45]. Chchd2 might slow the process of maintaining metabolic homeostasis. This research has significantly contributed to the clinical treatment of NASH.
ceRNAs play a major role in the control of post-transcriptional gene expression in physiological and pathological contexts [46].In addition, miRNAs have been revealed to have an important role in liver disorders [12, 47]. A regulatory network may also be involved in NASH [48, 49]. A network of miRNA-mRNA interactions linked with UA-NASH was developed in this research. We found various miRNAs closely related to the physiological and pathological processes between NASH and UA treatment and predicted the potential functions of related pathways and the targets of miRNAs. The ceRNA regulatory network also indicated major pathways and critical genes that may be modified after UA therapy. To better understand, a ceRNA network was successfully constructed based on RNAseq data. The association between the ceRNA network and pathological features was assessed, which revealed that this axis might be the potential for the treatment of UA with NASH in future.
In this study, we used RNA sequencing data from our own model mice, which we split into four groups of three biological replicates each. We used the WGCNA, which is an effective method for elucidating the molecular processes underlying metabolic diseases, to identify the hub gene in the modules connected to the clinical characteristics of NASH and then built the ceRNA network associated with the disorder. Using in vitro and in vivo models, we confirmed the expression of three genes and provided preliminary proof that the treatment of NASH by UA might well be linked to the mitigation of oxidative stress. However, the liver samples in our experiment were limited, and if the liver tissues were polluted, WGCNA findings might be inaccurate. The results from this study must be confirmed in larger sample-size investigations and still have to be confirmed by cellular and animal studies. There is a pressing need to conduct further trials on several facets. Also, the predicted ceRNA network is partly based on the public database, and the existence of a regulatory relationship in NASH needs further confirmation. Therefore, to confirm and improve the basis of this investigation, we will enlarge our sample size, and collect liver samples, blood samples, and clinical data from patients in subsequent trials. More research is required to evaluate the precise regulatory mechanisms of these genes and pathways.