Enzymes of Fibrosis in Chronic Liver Disease

Unlocking the Potential of Collagenases: Structures, Functions, and Emerging Therapeutic Horizons

Collagenases, a class of enzymes that are specifically responsible for collagen degradation, have garnered substantial attention because of their pivotal roles in tissue repair, remodeling, and medical interventions. This comprehensive review investigates the diversity, structures, and mechanisms of collagenases and highlights their therapeutic potential. First, it provides an overview of the biochemical properties of collagen and highlights its importance in extracellular matrix function. Subsequently, it meticulously analyzes the sources of collagenases and their applications in tissue engineering and food processing. Notably, this review emphasizes the predominant role played by microbial collagenases in commercial settings while discussing their production and screening methods. Furthermore, this study elucidates the methodology employed for determining collagenase activity and underscores the importance of an accurate evaluation for both research purposes and clinical applications. Finally, this review highlights the future research prospects for collagenases, with a particular focus on promoting wound healing and treating scar tissue formation and fibrotic diseases.

27-Hydroxycholesterol induces liver fibrosis via down-regulation of trimethylation of histone H3 at lysine 27 by activating oxidative stress; effect of nutrient interventions

BACKGROUND

Chronic liver injury caused by activation of hepatic stellate cells (HSCs) is a key event in the development of liver fibrosis (LF). A high-cholesterol diet can prompt accumulation of free cholesterol in HSCs, which promotes HSC activation and progression of LF.

OBJECTIVE

27-Hydroxycholesterol (27HC) is the most abundant cholesterol metabolite. Here, we investigated whether the HSC activation and LF induced by high cholesterol is caused by its metabolite 27HC, and whether TGFβ classical signaling were involved in these processes.

METHODS

In vitro, LX2 and HSC-T6 cells were used to explore the effects of 27HC on activation of HSCs, while LSECs were used to observe the effects of 27HC on capillarization. In vivo, zebrafish were used to assess the effect of 27HC on LF.

RESULTS

The cholesterol metabolite 27HC promoted the proliferation of HSCs and up-regulated expression of COL-1 and α-SMA as well as CTGF and TIMP1. Also, 27HC up-regulated expression of Smad2/3 and phosphorylated Smad2/3 in HSCs. Furthermore, 27HC-induced up-regulation of COL-1, α-SMA, CTGF, and TIMP1 protein levels was inhibited by Smad2/3 knockout. In addition, 27HC down-regulated H3K27me3 by inhibition of EZH2 and promotion of UTX and JMJD3 expression via the TGFβ signaling, thereby inducing activation of HSCs. Notably, 27HC significantly aggravated the pathological damage induced by DEN, and induced deposition of collagen fibers in zebrafish liver. Folic acid (FA) and resveratrol (RES) both reduced 27HC-induced production of reactive oxygen species (ROS) and inhibited the effects of TGFβ signaling on EZH2, UTX, and JMJD3, thereby increasing H3K27me3, and finally jointly inhibiting LF.

CONCLUSION

Cholesterol is metabolized to 27HC, which mediates activation of HSCs and onset of LF. Reduced expression of H3k27me3 by TGFβ signaling is crucial to 27HC-induced LF. FA and RES ameliorated activation of HSCs and LF by reducing 27HC-induced production of ROS and regulating of H3K27me3.

Extracellular matrix turnover: phytochemicals target and modulate the dual role of matrix metalloproteinases (MMPs) in liver fibrosis

Extracellular matrix (ECM) resolution by matrix metalloproteinases (MMPs) is a well-documented mechanism. MMPs play a dual and complex role in modulating ECM degradation at different stages of liver fibrosis, depending on the timing and levels of their expression. Increased MMP-1 combats disease progression by cleaving the fibrillar ECM. Activated hepatic stellate cells (HSCs) increase expression of MMP-2, -9, and -13 in different chemicals-induced animal models, which may alleviate or worsen disease progression based on animal models and the stage of liver fibrosis. In the early stage, elevated expression of certain MMPs may damage surrounding tissue and activate HSCs, promoting fibrosis progression. At the later stage, downregulation of MMPs can facilitate ECM accumulation and disease progression. A number of phytochemicals modulate MMP activity and ECM turnover, alleviating disease progression. However, the effects of phytochemicals on the expression of different MMPs are variable and may depend on the disease models and stage, and the dosage, timing and duration of phytochemicals used in each study. Here, we review the most recent advances in the role of MMPs in the effects of phytochemicals on liver fibrogenesis, which indicates that further studies are warranted to confirm and define the potential clinical efficacy of these phytochemicals.

Targeting collagen homeostasis for the treatment of liver fibrosis: Opportunities and challenges

Liver fibrosis is an excessive production, aberrant deposition, and deficit degradation of extracellular matrix (ECM). Patients with unresolved fibrosis ultimately undergo end-stage liver diseases. To date, the effective and safe strategy to cease fibrosis progression remains an unmet clinical need. Since collagens are the most abundant ECM protein which play an essential role in fibrogenesis, the suitable regulation of collagen homeostasis could be an effective strategy for the treatment of liver fibrosis. Therefore, this review provides a brief overview on the dysregulation of ECM homeostasis, focusing on collagens, in the pathogenesis of liver fibrosis. Most importantly, promising therapeutic mechanisms related to biosynthesis, deposition and extracellular interactions, and degradation of collagens, together with preclinical and clinical antifibrotic evidence of drugs affecting each target are orderly criticized. In addition, challenges for targeting collagen homeostasis in the treatment of liver fibrosis are discussed.

Mechanism-based target therapy in primary biliary cholangitis: opportunities before liver cirrhosis?

Primary biliary cholangitis (PBC) is an immune-mediated liver disease characterized by cholestasis, biliary injuries, liver fibrosis, and chronic non-suppurative cholangitis. The pathogenesis of PBC is multifactorial and involves immune dysregulation, abnormal bile metabolism, and progressive fibrosis, ultimately leading to cirrhosis and liver failure. Ursodeoxycholic acid (UDCA) and obeticholic acid (OCA) are currently used as first- and second-line treatments, respectively. However, many patients do not respond adequately to UDCA, and the long-term effects of these drugs are limited. Recent research has advanced our understanding the mechanisms of pathogenesis in PBC and greatly facilitated development of novel drugs to target mechanistic checkpoints. Animal studies and clinical trials of pipeline drugs have yielded promising results in slowing disease progression. Targeting immune mediated pathogenesis and anti-inflammatory therapies are focused on the early stage, while anti-cholestatic and anti-fibrotic therapies are emphasized in the late stage of disease, which is characterized by fibrosis and cirrhosis development. Nonetheless, it is worth noting that currently, there exists a dearth of therapeutic options that can effectively impede the progression of the disease to its terminal stages. Hence, there is an urgent need for further research aimed at investigating the underlying pathophysiology mechanisms with potential therapeutic effects. This review highlights our current knowledge of the underlying immunological and cellular mechanisms of pathogenesis in PBC. Further, we also address current mechanism-based target therapies for PBC and potential therapeutic strategies to improve the efficacy of existing treatments.

Transcriptomic profiling identifies differentially expressed genes and related pathways associated with wound healing and cuproptosis-related genes in Ganxi goats

Introduction

Wound healing is very important for the maintenance of immune barrier integrity, which has attracted wide attention in past 10 years. However, no studies on the regulation of cuproptosis in wound healing have been reported.

Methods

In this study, the skin injury model was constructed in Gnxi goats, and the function, regulatory network and hub genes of the skin before and after the injury were comprehensively analyzed by transcriptomics.

Results

The results showed that there were 1,438 differentially expressed genes (DEGs), genes up-regulated by 545 and genes down-regulated by 893, which were detected by comparing day 0 and day 5 posttraumatic skin. Based on GO-KEGG analysis, DEGs that were up-regulated tended to be enriched in lysosome, phagosome, and leukocyte transendothelial migration pathways, while down-regulated DEGs were significantly enriched in adrenergic signaling in cardiomyocytes and calcium signaling pathway. There were 166 overlapped genes (DE-CUGs) between DEGs and cuproptosis-related genes, with 72 up-regulated DE-CUGs and 94 down-regulated DE-CUGs. GOKEGG analysis showed that up-regulated DE-CUGs were significantly enriched in ferroptosis, leukocyte transendothelial migration and lysosome pathways, while down-regulated DE-CUGs were significantly enriched in Apelin signaling pathway and tyrosine metabolism pathways. By constructing and analyzing of protein-protein interaction (PPI) networks of DEGs and DE-CUGs, 10 hub DEGs (ENSCHIG00000020079, PLK1, AURKA, ASPM, CENPE, KIF20A, CCNB2, KIF2C, PRC1 and KIF4A) and 10 hub DE-CUGs (MMP2, TIMP1, MMP9, MMP14, TIMP3, MMP1, EDN1, GCAT, SARDH, and DCT) were obtained, respectively.

Discussion

This study revealed the hub genes and important wound healing pathways in Ganxi goats, and identified the correlation between wound healing and cuproptosis for the first time, and found that MMP2, TIMP1, MMP9, and EDN1 were the core genes associated. This study enriched the transcriptome data of wound healing in Ganxi goats and expanded the research direction of cuproptosis.

literammp-9 mRNA Expression and Bridging Fibrosis Progression in Toxic Liver Injury

Developing liver disease treatments, in which fibrosis is a key pathogenetic link, still remains an urgent problem in hepatology. In the present study, the level of mmp-9 mRNA expression and the number of FAP+, α-SMA+, CD45+ cells were analyzed at nine time points of fibrosis and cirrhosis. It was found that in the case of liver fibrosis, the choice of the optimal reference gene depended on the stage of fibrogenesis. When studying the specific stages rather than the entire process in a long-term experiment, it was shown that choosing an optimal reference gene has to be done additionally. In this case, the mmp-9 mRNA expression level should be considered as a marker of liver fibrosis initiation and development but not as that of cirrhosis progression. In the liver, two morphologically heterogeneous populations of myofibroblasts were simultaneously identified as able to synthesize various types of immunohistochemical markers. It was found that the FAP+ cells were the main contributor to the development of portal fibrosis and the initial stages of bridging fibrosis. In the selected experimental model, fibrosis initiation and the development stages preceding parenchyma restructuring were accompanied by a low level of inflammation.