Pathophysiology of Liver Fibrosis

2015 ◽  
Vol 33 (4) ◽  
pp. 492-497 ◽  
Author(s):  
Massimo Pinzani
Keyword(s):  
Wound Healing ◽  
Liver Fibrosis ◽  
Tissue Damage ◽  
Molecular Mechanisms ◽  
Epigenetic Modification ◽  
Relative Concentration ◽  
Portal Tract ◽  
Drug Induced ◽  
Chronic Activation

Progressive accumulation of fibrillar extracellular matrix (ECM) in the liver is the consequence of reiterated liver tissue damage due to infective (mostly hepatitis B and C viruses), toxic/drug-induced, metabolic and autoimmune causes, and the relative chronic activation of the wound-healing reaction. The process may result in clinically evident liver cirrhosis and hepatic failure. Although cirrhosis is the common result of progressive fibrogenesis, there are distinct patterns of fibrotic development related to the underlying disorders causing the fibrosis. These different patterns of fibrogenic evolution are related to different factors and particularly: (1) the topographic localization of tissue damage, (2) the relative concentration of profibrogenic factors and (3) the prevalent profibrogenic mechanism(s). The mechanisms responsible for the fibrogenic evolution of chronic liver diseases can be summarized in three main groups: chronic activation of the wound-healing reaction, oxidative stress-related molecular mechanisms, and the derangement of the so-called ‘epithelial-mesenchymal' interaction leading to the generation of reactive cholangiocytes and peribiliary fibrosis. Most of the knowledge on the cell and molecular biology of hepatic fibrosis derives from in vitro studies employing culture of activated hepatic stellate cells isolated from rat, mouse or human liver. It is now evident that other ECM-producing cells, i.e. fibroblasts and myofibroblasts of the portal tract and circulating ‘fibrocytes', are likely to contribute to liver fibrosis. More recently, the attention is progressively shifting to the profibrotic microenvironment of the liver with increasing interest for the role of immune cells and specific subsets of macrophages regulating the progression or the regression of fibrosis, the role of intestinal microbiota and the influence of tissue stiffness. Other major areas of development include the role of tissue hypoxia and the establishment of an anaerobic proinflammatory environment and the influence of epigenetic modification in conditioning the progression of fibrosis.

scholarly journals The roles and mechanisms of hypoxia in liver fibrosis

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Jingyao Cai ◽  
Min Hu ◽  
Zhiyang Chen ◽  
Zeng Ling
Keyword(s):  
Quality Of Life ◽  
Liver Fibrosis ◽  
Theoretical Basis ◽  
Liver Diseases ◽  
Molecular Mechanisms ◽  
Clinical Intervention ◽  
Chronic Liver Injury ◽  
Key Factor

AbstractLiver fibrosis occurs in response to any etiology of chronic liver injury. Lack of appropriate clinical intervention will lead to liver cirrhosis or hepatocellular carcinoma (HCC), seriously affecting the quality of life of patients, but the current clinical treatments of liver fibrosis have not been developed yet. Recent studies have shown that hypoxia is a key factor promoting the progression of liver fibrosis. Hypoxia can cause liver fibrosis. Liver fibrosis can, in turn, profoundly further deepen the degree of hypoxia. Therefore, exploring the role of hypoxia in liver fibrosis will help to further understand the process of liver fibrosis, and provide the theoretical basis for its diagnosis and treatment, which is of great significance to avoid further deterioration of liver diseases and protect the life and health of patients. This review highlights the recent advances in cellular and molecular mechanisms of hypoxia in developments of liver fibrosis.

scholarly journals Circadian Rhythms, the Mesolimbic Dopaminergic Circuit, and Drug Addiction

2007 ◽  
Vol 7 ◽  
pp. 194-202 ◽  
Author(s):  
Colleen A. McClung
Keyword(s):  
Circadian Rhythms ◽  
Drug Addiction ◽  
Molecular Mechanisms ◽  
Dopaminergic System ◽  
Treatment Options ◽  
Drug Induced ◽  
Circadian Genes ◽  
Dopaminergic Transmission ◽  
Central Pacemaker

Drug addiction is a devastating disease that affects millions of individuals worldwide. Through better understanding of the genetic variations that create a vulnerability for addiction and the molecular mechanisms that underlie the progression of addiction, better treatment options can be created for those that suffer from this condition. Recent studies point to a link between abnormal or disrupted circadian rhythms and the development of addiction. In addition, studies suggest a role for specific genes that make up the molecular clock in the regulation of drug sensitivity, sensitization, and reward. The influence of circadian genes and rhythms on drug-induced behaviors may be mediated through the mesolimbic dopaminergic system. This system has long been implicated in the development of addiction, and recent evidence supports a regulatory role for the brain's central pacemaker and circadian gene expression in the regulation of dopaminergic transmission. This review highlights the association between circadian genes and drug addiction, and the possible role of the mesolimbic dopaminergic system in this association.

scholarly journals The Art of Mesenchymal Stem Cells in Liver Fibrosis Management

2021 ◽  
Vol 3 (2) ◽  
pp. 15-24
Author(s):  
Farid Amansyah ◽  
Dito Anurogo
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Liver Fibrosis ◽  
Liver Injury ◽  
Tissue Damage ◽  
Fundamental Concept ◽  
Scientific Review ◽  
Safety And Efficacy ◽  
Experimental Animals

Liver fibrogenesisis chronic tissue damage characterized by an extracellular ac-cumulation of fibrillar matrix associated with continuous degradation and remod-elling. This scientific review describes current concepts on the pathophysiology of liver fibrosis, inflammation asa fundamental concept of liver fibrosis, mechanistic concepts of liver fibrosis, the role of mesenchymal stem cells (MSC) in liver injury, the functional effects of MSC secretome, the advantages of secretome ther-apy, and the latest research developments on MSC. The role of MSCs has been proven in many liver fibrosis studies involving experimental animals. However, it still requires further research for safety and efficacy aspects.

scholarly journals Role of Main RNA Methylation in Hepatocellular Carcinoma: N6-Methyladenosine, 5-Methylcytosine, and N1-Methyladenosine

2021 ◽  
Vol 9 ◽  
Author(s):  
Yating Xu ◽  
Menggang Zhang ◽  
Qiyao Zhang ◽  
Xiao Yu ◽  
Zongzong Sun ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cellular Differentiation ◽  
Molecular Mechanisms ◽  
Gene Sequence ◽  
Epigenetic Modification ◽  
Biological Processes ◽  
Biological Functions ◽  
Rna Detection ◽  
Rna Methylation

RNA methylation is considered a significant epigenetic modification, a process that does not alter gene sequence but may play a necessary role in multiple biological processes, such as gene expression, genome editing, and cellular differentiation. With advances in RNA detection, various forms of RNA methylation can be found, including N6-methyladenosine (m6A), N1-methyladenosine (m1A), and 5-methylcytosine (m5C). Emerging reports confirm that dysregulation of RNA methylation gives rise to a variety of human diseases, particularly hepatocellular carcinoma. We will summarize essential regulators of RNA methylation and biological functions of these modifications in coding and noncoding RNAs. In conclusion, we highlight complex molecular mechanisms of m6A, m5C, and m1A associated with hepatocellular carcinoma and hope this review might provide therapeutic potent of RNA methylation to clinical research.

Role of Epithelial-to-Mesenchymal Transition in Inflammatory Bowel Disease

2018 ◽  
Vol 13 (5) ◽  
pp. 659-668 ◽  
Author(s):  
Sara Lovisa ◽  
Giannicola Genovese ◽  
Silvio Danese
Keyword(s):  
Inflammatory Bowel Disease ◽  
Wound Healing ◽  
Bowel Disease ◽  
Molecular Mechanisms ◽  
Epithelial To Mesenchymal Transition ◽  
Clinical Manifestations ◽  
Mesenchymal Transition ◽  
Intestinal Fibrosis ◽  
Inflammatory Bowel

Abstract Intestinal fibrosis is an inevitable complication in patients with inflammatory bowel disease [IBD], occurring in its two major clinical manifestations: ulcerative colitis and Crohn’s disease. Fibrosis represents the final outcome of the host reaction to persistent inflammation, which triggers a prolonged wound healing response resulting in the excessive deposition of extracellular matrix, eventually leading to intestinal dysfunction. The process of epithelial-to-mesenchymal transition [EMT] represents an embryonic program relaunched during wound healing, fibrosis and cancer. Here we discuss the initial observations and the most recent findings highlighting the role of EMT in IBD-associated intestinal fibrosis and fistulae formation. In addition, we briefly review knowledge on the cognate process of endothelial-to-mesenchymal transition [EndMT]. Understanding EMT functionality and the molecular mechanisms underlying the activation of this mesenchymal programme will permit designing new therapeutic strategies to halt the fibrogenic response in the intestine.

scholarly journals The Mouse Xist Gene: a Model for Studying the Gametic Imprinting Phenomenon

1996 ◽  
Vol 45 (1-2) ◽  
pp. 199-204 ◽  
Author(s):  
M. Zuccotti ◽  
M. Monk
Keyword(s):  
Molecular Mechanisms ◽  
Epigenetic Modification ◽  
Somatic Tissue ◽  
Paternal Allele ◽  
The Status ◽  
Intron Region ◽  
Exon 11 ◽  
Region 10 ◽  
Gametic Imprinting

In mammals, normal embryonic development requires differential genomic imprinting of male and female gametes [1, 2]. Many investigations have been directed towards the understanding of the molecular mechanisms of imprinting and the timing of establishment of the imprint during gametogenesis and its erasure during development.Methylation is the focus of many of these studies as it has been known for some time that this epigenetic modification of the DNA correlates with the status of gene activity. So far, five imprinted genes, expressed from only one of the parental alleles, have been found to be differentially methylated in somatic tissue: mouse Igf2 [3] and Xist [4] and human SNRPN [5, 6] expressed from the paternal allele; mouse Igf2r [7] and H19 [8, 9] expressed from the maternal allele. However, so far, a gametic methylation imprint has been detected for only two of these genes: in an intron region of mouse Igf2r [7], and in the promoter region [10] and the first exon [11] of the Xist (X-inactivation-specific transcript [12, 13] gene.The data accumulated for the Xist gene, during different phases of gametogenesis and development, provides the most comprehensive story about the role of methylation as a primary gametic imprint, and on the timing of its establishment during gametogenesis and erasure during development. Methylation studies have now been performed during oogenesis and spermatogenesis [Norris et al., 1994; 11] and in mature gametes and during early stages of development [10, 11]. In addition, expression of the gene has been described during gametogenesis [14-16] and throughout early development [4-17].

Molecular Understanding of the Cardiomodulation in Myocardial Infarction and the Mechanism of Vitamin E Protections

2019 ◽  
Vol 19 (17) ◽  
pp. 1407-1426 ◽  
Author(s):  
Khairul Anwar Zarkasi ◽  
Tan Jen-Kit ◽  
Zakiah Jubri
Keyword(s):  
Myocardial Infarction ◽  
Vitamin E ◽  
Tissue Damage ◽  
Molecular Mechanisms ◽  
Cardiac Tissue ◽  
Ppar Γ ◽  
Intracellular Signalling Pathways ◽  
Survival Pathways ◽  
Cause Of Deaths

: Myocardial infarction is a major cause of deaths globally. Modulation of several molecular mechanisms occurs during the initial stages of myocardial ischemia prior to permanent cardiac tissue damage, which involves both pathogenic as well as survival pathways in the cardiomyocyte. Currently, there is increasing evidence regarding the cardioprotective role of vitamin E in alleviating the disease. This fat-soluble vitamin does not only act as a powerful antioxidant; but it also has the ability to regulate several intracellular signalling pathways including HIF-1, PPAR-γ, Nrf-2, and NF-κB that influence the expression of a number of genes and their protein products. Essentially, it inhibits the molecular progression of tissue damage and preserves myocardial tissue viability. This review aims to summarize the molecular understanding of the cardiomodulation in myocardial infarction as well as the mechanism of vitamin E protection.

scholarly journals Role of MexZ and PA5471 in transcriptional regulation of mexXY in Pseudomonas aeruginosa

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3312-3321 ◽  
Author(s):  
Masaki Yamamoto ◽  
Atsuhisa Ueda ◽  
Makoto Kudo ◽  
Yasuhiro Matsuo ◽  
Jun Fukushima ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Transcriptional Regulation ◽  
Molecular Mechanisms ◽  
Efflux Pump ◽  
Mobility Shift ◽  
Drug Induced ◽  
Drug Efflux Pump ◽  
Mobility Shift Assay

MexXY, a drug efflux pump in Pseudomonas aeruginosa, confers resistance to aminoglycoside antibiotics. We recently reported that MexZ binds to the promoter region of the mexXY operon. Electrophoretic mobility shift assay (EMSA) using recombinant MexZ and oligonucleotide probes prepared from the intergenic region between mexZ and mexX revealed that MexZ binds to a 20 bp palindromic sequence. Culture of P. aeruginosa in the presence of tetracycline induced higher levels of MexX and MexZ, as measured by immunoblotting and EMSA, than in the absence of antibiotics. When MexZ was expressed by a mexZ expression plasmid, the plasmid-borne MexZ repressed drug-induced MexX production, further confirming that MexZ acts as a repressor of the mexXY operon. PA5471 protein has been reported to be essential for drug-induced MexXY production. Similarly to that report, we observed that plasmid-borne PA5471 induced both MexX and MexZ production in PAO1 cells. Interestingly, interaction between MexZ and PA5471 was observed in a yeast two-hybrid assay. Furthermore, EMSA and in vitro transcription assays revealed that interaction between PA5471 and MexZ reduced MexZ DNA-binding ability, leading to mexXY transcription. These findings contribute to the understanding of the molecular mechanisms underlying the transcriptional regulation of mexZ and mexXY by drug-induced PA5471 expression.

scholarly journals CD8+ tissue-resident memory T cells promote liver fibrosis resolution by inducing apoptosis of hepatic stellate cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuzo Koda ◽  
Toshiaki Teratani ◽  
Po-Sung Chu ◽  
Yuya Hagihara ◽  
Yohei Mikami ◽  
...  
Keyword(s):  
Liver Fibrosis ◽  
Hepatic Stellate Cells ◽  
Molecular Mechanisms ◽  
Stellate Cells ◽  
Dependent Manner ◽  
Resolution Model ◽  
Cell Transcriptome ◽  
Single Cell Transcriptome ◽  
Resident Memory T Cells

AbstractNon-alcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease that can progress to liver fibrosis. Recent clinical advance suggests a reversibility of liver fibrosis, but the cellular and molecular mechanisms underlying NASH resolution remain unclarified. Here, using a murine diet-induced NASH and the subsequent resolution model, we demonstrate direct roles of CD8+ tissue-resident memory CD8+ T (CD8+ Trm) cells in resolving liver fibrosis. Single-cell transcriptome analysis and FACS analysis revealed CD69+CD103−CD8+ Trm cell enrichment in NASH resolution livers. The reduction of liver CD8+ Trm cells, maintained by tissue IL-15, significantly delayed fibrosis resolution, while adoptive transfer of these cells protected mice from fibrosis progression. During resolution, CD8+ Trm cells attracted hepatic stellate cells (HSCs) in a CCR5-dependent manner, and predisposed activated HSCs to FasL-Fas-mediated apoptosis. Histological assessment of patients with NASH revealed CD69+CD8+ Trm abundance in fibrotic areas, further supporting their roles in humans. These results highlight the undefined role of liver CD8+ Trm in fibrosis resolution.

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