Liver fibrosis is a common pathological process that many chronic liver diseases must undergo to develop into cirrhosis and hepatocellular carcinoma. Liver fibrosis is regulated by a variety of cytokines and signal pathways during its occurrence and development. In recent years, a large number of studies showed that ferroptosis is closely related to liver fibrosis. Compared with normal liver, the levels of irons and lipid peroxidation in the liver with fibrosis are significantly increased. Therefore, ferroptosis may be a potential target for the diagnosis, prevention, and treatment of liver fibrosis. This review summarizes the role of ferroptosis in liver fibrosis, thus to provide new ideas for the treatment of liver fibrosis.

Fibrosis is a common manifestation of organ damage and failure. According to relevant statistics in the United States, deaths caused by fibrotic diseases account for 45% of all deaths in the country. Therefore, fibrotic diseases have received widespread attention worldwide. As a key kinase that regulates energy balance, AMP-activated protein kinase (AMPK), which mainly controls the transformation of cells from anabolic to catabolism, and restores the energy balance by phosphorylating its substrates. Therefore, it has become the core of treatment for diabetes and other metabolic-related diseases. Numerous recent pathological studies have shown that the expression of AMPK in fibrotic tissues is significantly down-regulated compared with normal tissues, and activation of AMPK could improve various fibrotic pathological processes (including autophagy dysfunction, oxidative stress, fibroblast proliferation, epithelial-mesenchymal transition, fibroblast-to-myofibroblast differentiation). Therefore, this review will discuss the structure and function of AMPK and its role in important phenotypes of fibrotic diseases, and provide evidence for AMPK as an important target for prevention and treatment of fibrosis.

Epithelial mesenchymal transition (EMT) is a reprogramming process of epithelial to mesenchymal transition, in which epithelial cells lose polarity and intercellular adhesion and acquire stronger migration and invasion ability similar to mesenchymal cells. EMT is a critical step during the pathogenesis of pulmonary fibrosis. Lung epithelial cells can differentiate into myofibroblasts through EMT, which accelerates the fibrosis process. In recent years, a large number of studies have shown that non-coding RNAs (ncRNAs) are involved in the EMT process of lung epithelial cells, at the same time, some natural medicines were found to prevent and treat pulmonary fibrosis by intervening in ncRNAs related to pulmonary fibrosis. In this review, we summarize the expression change and biological function of vital ncRNAs in EMT progression during pulmonary fibrosis, as well as the research progress of EMT related ncRNA mediated by natural medicines on pulmonary fibrosis, aiming to provide new insights into the research of ncRNAs and the exploration of new pharmacological targets of natural medicine.

We investigated the therapeutic effect and mechanism of isoforskolin on bleomycin-induced pulmonary fibrosis in mice. The animal welfare and experimental process were in accordance with the Regulations of Animal Ethics Committee of Kunming Medical University. Male Kunming mice were randomly divided into five groups: sham operation group (intratracheal instillation of normal saline), bleomycin group (intratracheal instillation of bleomycin 5 mg·kg^-1), positive drug control group (intratracheal instillation of bleomycin 5 mg·kg^-1 + intraperitoneal injection of dexamethasone sodium phosphate 2.5 mg·kg^-1), isoforskolin (2.5 and 10 mg·kg^-1) groups (intratracheal instillation of bleomycin 5 mg·kg^-1 + intragastric administration of isoforskolin 2.5 and 10 mg·kg^-1). The method of drug administration was once a day for 28 days. On the 7^th and 28^th day of the experiment, the mice were killed, and the lung tissue and bronchoalveolar lavage fluid samples were collected. Hematoxylin eosin (H & E) staining and Masson staining were used to detect the pathological changes of lung tissue. The content of hydroxyproline in lung tissue was detected by alkaline hydrolysis method. The levels of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) in bronchoalveolar lavage fluid (BALF) were detected by enzyme linked immunosorbent assay (ELISA). The expressions of transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) in lung tissue were detected by Western blot. The experimental results showed that compared with the bleomycin group, the degree of inflammation and fibrosis in the lung tissue of mice in 10 mg·kg^-1 isoforskolin group was significantly reduced, the content of hydroxyproline in the lung tissue was decreased, the levels of TNF-α and IL-1β in BALF were decreased, and the protein expressions of TGF-β1 and CTGF in the lung tissue were downregulated, the differences were statistically significant (P < 0.05). The results suggest that isoforskolin can inhibit the release of inflammatory cytokines TNF-α and IL-1β, downregulate the protein expression of profibrotic factors TGF-β1 and CTGF, and exert anti pulmonary fibrosis effect through both anti-inflammatory and anti fibrotic effect.

In this study, we investigated the effect and mechanism of glaucocalyxin A on transforming growth factor-β1 (TGF-β1)-induced differentiation of lung fibroblasts by Western blotting, cellular immunofluorescence and collagen gel contraction assays. We monitored the phosphorylation of Smad3, measured extracellular regulated protein kinases (ERK) 1/2 and glycogen synthase kinse3β (Ser9) activity and the level of β-catenin to elucidate the role of glaucocalyxin A. The results show that glaucocalyxin A significantly decreased the expression of α-smooth muscle actin in lung fibroblasts; glaucocalyxin A remarkably reduced the formation of filaments and collagen gel contraction of lung fibroblasts; glaucocalyxin A notably down-regulated the production of fibronectin; glaucocalyxin A did not affect the phosphorylation level of Smad3 and ERK1/2; glaucocalyxin A markedly inhibited the phosphorylation of GSK3β (Ser9) and the levels of β-catenin; a GSK3β (S9A) mutant significantly inhibited lung fibroblast differentiation; and SKL2001, a β-catenin activator, partly reversed the inhibition of lung fibroblast differentiation by glaucocalyxin A. These results suggest that glaucocalyxin A significantly inhibits the differentiation of lung fibroblasts, which is related to the down-regulation of GSK3β/β-catenin signaling.

The mechanism of Platycodon grandiflorum in the treatment of pulmonary fibrosis was examined by integrated pharmacology network with animal experiment validation. Compositions and targets of Platycodon grandiflorum were collected utilizing databases such as TCMSP and Swiss Target Prediction, whereas pulmonary fibrosis targets were obtained using GeneCards, OMIM, Disgenet, and Drugbank databases. These datasets were merged in order to identify prospective Platycodon grandiflorum targets for the treatment of pulmonary fibrosis. The "drug-component-target-disease" network was constructed with Cytoscape software, and the interaction relationship between potential targets was produced; they were coupled with the String platform to create the PPI network while also doing topological analysis. Then, using R software and the Bioconductor biological information software package, we conduct GO and KEGG enrichment analysis to estimate the therapeutic mechanism. A mouse model of pulmonary fibrosis was constructed for pathological staining, ELISA, lung function, qRT-PCR, and Western blot to validate the results of the network pharmacology. There are 289 putative active components of Platycodon grandiflorum, and 1 129 disease targets for pulmonary fibrosis, for a total of 65 drug-compound-disease common targets. The GO enrichment analysis revealed 1 575 items, whereas the KEGG enrichment analysis yielded 146 entries. The phosphatidylinositol 3 kinase-protein kinase B (PI3K-AKT) signaling pathway, the tumor necrosis factor (TNF) signaling system, and the interleukin-17 (IL-17) signaling pathway were enriched. In animal experiments, Platycodon grandiflorum was found to decrease lung inflammation and collagen deposition in mice with pulmonary fibrosis. According to Western blot results, the expression of PI3K-AKT signaling pathway-related proteins p-PI3K and p-AKT was down-regulated in a dose-dependent manner after Platycodon grandiflorum therapy of pulmonary fibrosis mice. When p-AKT was suppressed, P21 expression was reduced, indicating that Platycodon grandiflorum may control the expression of PI3K-AKT pathway-related proteins to alter cell senescence while treating mice with pulmonary fibrosis. This study uses network pharmacology to identify the targets and pathways of Platycodon grandiflorum against pulmonary fibrosis and conducts related animal experimental validation, providing a foundation for an in-depth discussion of the therapeutic mechanism of Platycodon grandiflorum against pulmonary fibrosis.

Chaihu Shugan San (CHSGS), a classic traditional Chinese medicinal formula, has been widely used in clinics for emotional disease. Here the protective effect and possible mechanisms of Chaihu Shugan San in stress-induced liver injury were investigated. The animal experimental protocol has been reviewed and approved by Laboratory Animal Ethics Committee of Jinan University, in compliance with the Institutional Animal Care Guidelines. Mice were administered CHSGS for 7 days and subjected to 18-h acute stress before being killed. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and malondialdehyde (MDA) levels in serum were measured with commercial kits. Histomorphology of the liver was analyzed by hematoxylin-eosin staining and immunohistochemistry. Glutathione (GSH) content, 4-hydroxynonenal (4-HNE), brain and muscle Arnt-like protein-1 (BMAL1) and arachidonate 15-lipoxygenase (ALOX15) protein were detected by LC-MS and Western blot, respectively. The results showed that CHSGS ameliorated acute stress-induced liver damage by reducing ALT and AST levels in serum and inflammatory infiltration in liver tissue. Network pharmacology analysis showed that CHSGS was associated with lipid peroxidation. Further analysis confirmed that MDA and 4-HNE levels declined and GSH level increased in livers of stressed mice after CHSGS administration. CHSGS also lowered BMAL1 expression, a pivotal factor in circadian rhythm, in livers of stressed mice. In conclusion, CHSGS ameliorated stress-induced liver injury by repressing lipid peroxidation and regulating circadian rhythm. Our studies implicate that CHSGS is promising as a therapy for stress-induced liver injury, and lay foundation for designing novel prophylactic and therapeutic strategies for stress-induced liver injury.

Pulmonary fibrosis (PF) is a chronic respiratory inflammation disease that threatens human health. The topical immune microenvironment of lung tissue regulates progression of fibrosis. In this study, the efficacy and molecular mechanism of suplatast tosilate (ST) against PF were observed. ST is a T helper 2 (Th2) cytokine inhibitor for clinical treatment of bronchial asthma. But whether it can be applied to therapy of chronic PF and the biomechanism of ST inhibiting Th2 cytokine release are not clear. Using in vivo and in vitro experiments, we found that ST can significantly suppress the pathogenesis of chronic PF induced by multiple bleomycin injury, improve the lung function, and decrease the deposition of collagen in lung tissue. In addition, ST decreases Th2 cytokine releasing through restraining Th2 cell differentiation in the meantime, but did not influence the T helper 1 (Th1) cell differentiation and Th1 cytokine releasing. Further studies showed that ST inhibits Th2 cell differentiation by down-regulating GATA-binding protein 3 (GATA3) expression and activity through inhibiting the phosphorylation of signal transducer and activator of transcription 5 (STAT5) and mammalian target of rapamycin (mTOR). The excessive expression of GATA3 in lungs can reverse the anti-PF effect of ST. All procedures involving animal treatment were approved according to the Committee on the Ethics of Animal Experiments of the Institute of Materia Medica, Chinese Academy of Medical Sciences. Our research not only clarifies the pharmacological mechanism of ST, but also provides a new selection for clinical anti-PF drug therapy.

Liver fibrosis is a common scarring response to virtually all forms of chronic liver injury and is characterized by excessive accumulation of extracellular matrix. Excessive activation of hepatic stellate cells (HSCs) is a key step in liver fibrogenesis. The withanolide extract of Physalis angulata (WEP) is a physalin-type withanolide enriched partition from Physalis angulata. In this study, liver fibrosis mice models were established by CCl₄ and bile duct ligation (BDL) in vivo. Transforming growth factor-β1 (TGF-β1) was given in vitro to induce activation of human hepatic stellate cells LX-2 and treated with WEP at different concentrations. All animal experiments in this paper have been approved by the Ethics Committee of China Pharmaceutical University. The in vivo results showed that, compared with the CCl₄ or BDL group, WEP could reduce collagen deposition and liver damage, and reduce the levels of aspartate transaminase (AST) and alanine transaminase (ALT) in serum. In vitro, WEP had no significant cytotoxicity to LX-2 cells, but significantly reduced the mRNA and protein expressions of fibrotic markers collagen type Ⅰ α 1 chain (COL1A1) and α-smooth muscle actin (α-SMA) and inhibited the activation of hepatic stellate cells. In addition, WEP inhibited the expression of yes-associated protein (YAP) and the phosphorylation level of Smad family member 2 (Smad2) in vivo and in vitro. In conclusion, WEP can inhibit hepatic stellate cells activation via regulating the YAP and TGF-β-Smad pathways, and shows promising anti-fibrosis activity in vitro and in vivo.

Hepatic fibrosis is a common pathological link of multiple chronic liver diseases, and further causes cirrhosis and even liver cancer. Tibetan medicine possessed significant and unique clinical effects in the prevention and treatment of hepatic fibrosis through unique medication methods such as single prescription, time synergy, and dialectical combination prescription. Pharmacological experimental studies have shown that a variety of Tibetan medicine formulas and herbs have anti-fibrotic effects, and their main pharmacological action mechanism involves inhibiting lipid peroxidation, reducing liver stellate cell activation and proliferation, regulating collagen metabolism, etc. This review summarizes the research progress of the clinical application and pharmacodynamic mechanism of Tibetan medicine in the prevention and treatment of liver fibrosis, aiming to provide a reference for the development of clinical use and innovative drugs discovery of Tibetan medicine against hepatic fibrosis.