Extracellular Matrix Metabolism and Fibrotic Disease

Transcriptional regulation of alcohol induced liver fibrosis in a translational porcine hepatocellular carcinoma model

Hepatocellular carcinoma (HCC) is the 5th most common and 2nd deadliest cancer worldwide. HCC risk factors include alcohol induced liver cirrhosis, which prompts hepatic inflammation, cell necrosis, and fibrosis deposition. As 25% of HCC cases are associated with alcohol induced liver disease, understanding the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic responses are critical. This study utilized the Oncopig Cancer Model-a transgenic pig model that recapitulates human HCC through induced expression of KRAS^G12D and TP53^R167H driver mutations-to investigate the molecular mechanisms underlying alcohol induced liver disease. Oncopigs (n = 5) underwent fibrosis induction via infusion of ethanol and ethiodized oil (1:3 v/v dosed at 0.75 mL/kg) into the hepatic arterial circulation. Eight-weeks post induction, liver tissue samples from fibrotic and age-matched control (n = 5) Oncopigs were collected for histological evaluation and transcriptional profiling. Increased hepatic inflammation and fibrosis was observed in fibrotic Oncopigs via pathological assessment. Transcriptional profiling (RNA-seq) resulted in the identification of 4387 differentially expressed genes between Oncopig fibrotic and control livers. GO term enrichment analysis identified pathway alterations associated with cirrhosis progression in humans, including cell proliferation, angiogenesis, extracellular matrix deposition, and oxidation-reduction. Key alterations include activation of hepatic stellate cells, increased matrix metalloproteinase production, and altered expression of ABC and SLC transporter genes involved in transport of anticancer drugs.These results demonstrate Oncopig liver fibrosis recapitulates transcriptional hallmarks of human cirrhosis, making the Oncopig an ideal model for studying the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic response.

Linking LOXL2 to Cardiac Interstitial Fibrosis

Cardiovascular diseases (CVDs) are the leading causes of death worldwide. CVD pathophysiology is often characterized by increased stiffening of the heart muscle due to fibrosis, thus resulting in diminished cardiac function. Fibrosis can be caused by increased oxidative stress and inflammation, which is strongly linked to lifestyle and environmental factors such as diet, smoking, hyperglycemia, and hypertension. These factors can affect gene expression through epigenetic modifications. Lysyl oxidase like 2 (LOXL2) is responsible for collagen and elastin cross-linking in the heart, and its dysregulation has been pathologically associated with increased fibrosis. Additionally, studies have shown that, LOXL2 expression can be regulated by DNA methylation and histone modification. However, there is a paucity of data on LOXL2 regulation and its role in CVD. As such, this review aims to gain insight into the mechanisms by which LOXL2 is regulated in physiological conditions, as well as determine the downstream effectors responsible for CVD development.

Tormentic acid inhibits hepatic stellate cells activation via blocking PI3K/Akt/mTOR and NF-κB signalling pathways

The present study was to investigate the inhibitory effect and underlying mechanism of Tormentic acid (TA) on hepatic stellate cells (HSCs). HSC-T6 cells were stimulated with Platelet-derived growth factor-BB (PDGF-BB) and TA, and then cell proliferation, apoptosis, inflammatory factor, and collagen-related indicators were detected. In order to elucidate the potential mechanism, the PI3K/Akt/mTOR and NF-κB signalling pathways were also detected. The results showed that TA treatment markedly inhibited PDGF-BB-stimulated HSC-T6 cell activation, as evidenced by the inhibition of cell proliferation, migration and colony formation, as well as the decreased expression of TGF-β and α-SMA. TA treatment caused a significant increase in the activity of lactate dehydrogenase and significantly promoted cell apoptosis. TA treatment significantly reduced aspartate aminotransferase, alanine aminotransferase and total bilirubin activity. Importantly, TA inhibited the expression of collagen type I and III, alleviating the excessive deposition of extracellular matrix (ECM). Further experiments showed that TA administration significantly inhibited the phosphorylation of PI3K, Akt, FAK and mTOR and the protein expression of P70S6K, indicating the inhibition of the PI3K/Akt/mTOR pathway. Moreover, treatment with TA markedly decreased the phosphorylation of IκBα, NF-κB p65 and IKKα/β, thereby blocking the NF-κB signal transduction. In summary, this study demonstrates that TA significantly inhibits HSC activation and promotes cell apoptosis via the inhibition of the PI3K/Akt/mTOR and NF-κB signalling pathways. SIGNIFICANCE OF THE STUDY: Tormentic acid (TA) could inhibit HSC activation and alleviate collagen-based ECM deposition, suggesting that TA exerted anti-hepatic fibrosis. Further mechanism research revealed that the inhibition of TA on HSC activation might be through blocking the PI3K/Akt/mTOR and NF-κB signalling pathways. These findings provided a new cue to understand the protective effect of TA against liver fibrosis, which may provide a potential nature medicine for the treatment of liver fibrosis.