scholarly journals Liver Fibrosis: Underlying Mechanisms and Innovative Therapeutic Approach. A Review Article

2021 ◽  
Vol 14 (4) ◽  
pp. 1841-1862
Author(s):  
Sally A El Awdan ◽  
Gihan F. Asaad

Liver fibrosis is considered: “a pathological repairing process in liver injuries leading to extracellular cell matrix (ECM) accumulation evidencing chronic liver diseases”. Chronic viral hepatitis, alcohol consumption, autoimmune diseases as well as non-alcoholic steatohepatitis are from the main causes of liver fibrosis (Lee et al., 2015; Mieli-Vergani et al., 2018). Hepatic stellate cells (HSCs) exist in the sinus space next to the hepatic epithelial cells as well as endothelial cells (Yin et al., 2013). Normally, HSCs are quiescent and mainly participate in fat storage and in the metabolism of vitamin A. HSCs are produced during liver injury and then transformed into myofibroblasts. The activated HSCs resulted in a sequence of events considered as marks fibrosis. The activation of HSCs mostly express alpha smooth muscle actin (α-SMA). Moreover, ECM is synthesized and secreted by HSCs that affects markedly the structure and function of the liver tissue leading to fibrosis (Tsuchida et al., 2017; Han et al., 2020). Hence, activated HSCs are attracting attention as potential targets in liver fibrosis. Many signaling molecules are involved in HSCs activation first and foremost, platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-β) (Tsuchida et al., 2017; Wang et al., 2020c) as interfering the PDGF or TGF-β signaling pathways is a growing field for liver fibrosis treatment.

Author(s):  
Qiao You Lau ◽  
Fuad Gandhi Torizal ◽  
Marie Shinohara ◽  
Yasuyuki Sakai

During chronic liver injury, inflammation leads to the development of liver fibrosis— particularly due to the activation of hepatic stellate cells (HSCs). However, the involvement of inflammatory cytokines in HSC activation is unclear. Many existing in vitro liver models do not include these non-parenchymal cells (NPCs), and hence, do not represent the physiological relevance found in vivo. Herein, we demonstrated the hierarchical coculture of primary rat hepatocytes with NPCs such as the human-derived HSC line (LX-2) and the human-derived liver sinusoidal endothelial cell line (TMNK-1). The coculture tissue had higher albumin production and hepatic cytochrome P450 3A4 activity compared to the monoculture. We then further studied the effects of stimulation by both oxygen tension and key pro-fibrogenic cytokines, such as the transforming growth factor beta (TGF-β), on HSC activation. Gene expression analysis revealed that lower oxygen tension and TGF-β1 stimulation enhanced collagen type I, III, and IV, alpha-smooth muscle actin, platelet-derived growth factor, and matrix metallopeptidase expression from LX-2 cells in the hierarchical coculture after fibrogenesis induction. This hierarchical in vitro cocultured liver tissue could, therefore, provide an improved platform as a disease model for elucidating the interactions of various liver cell types and biochemical signals in liver fibrosis studies.


Author(s):  
Yedan Liu ◽  
Huawei Zhang ◽  
Shaoxun Wang ◽  
Ya Guo ◽  
Xing Fang ◽  
...  

Diabetes mellitus (DM) is one of the primary pathological factors that contributes to aging-related cognitive impairments, but the underlying mechanisms remain unclear. We recently reported that old DM rats exhibited impaired myogenic responses of the cerebral arteries and arterioles, poor cerebral blood flow autoregulation, enhanced blood-brain barrier (BBB) leakage, and cognitive impairments. These changes were associated with diminished vascular smooth muscle cell contractile capability linked to elevated reactive oxygen species (ROS) and reduced ATP production. The present study, using a non-obese T2DN DM rat, isolated parenchymal arterioles (PAs), and cultured cerebral microvascular pericytes, examined whether cerebrovascular pericyte in DM is damaged and whether pericyte dysfunction may play a role in the regulation of cerebral hemodynamics and BBB integrity. We found that ROS and mitochondrial superoxide production were elevated in PAs isolated from old DM rats and in high glucose (HG)-treated alpha-smooth muscle actin positive pericytes. HG-treated pericytes displayed decreased contractile capability in association with diminished mitochondrial respiration and ATP production. Additionally, the expression of advanced glycation end products, transforming growth factor-beta, vascular endothelial growth factor, and fibronectin were enhanced, but claudin 5 and integrin β1 was reduced in the brain of old DM rats and HG-treated pericytes. Further, endothelial tight junction and pericyte coverage on microvessels were reduced in the cortex of old DM rats. These results demonstrate our previous findings that the impaired cerebral hemodynamics and BBB leakage and cognitive impairments in the same old DM model are associated with hyperglycemia-induced cerebrovascular pericyte dysfunction.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Farouk K. El-Baz ◽  
Abeer Salama ◽  
Sami I. Ali ◽  
Rania Elgohary

Hepatic fibrosis is a consequence of chronic liver diseases. Metalloproteinase and its inhibitor have crucial roles in the resolution of liver fibrosis. The current relevant study is aimed to evaluate the therapeutic effect of Haematococcus pluvialis (H. pluvialis) extract, astaxanthin-rich fraction, astaxanthin ester-rich fraction, and β-carotene-rich fraction as well as their mechanisms of action in curing hepatic fibrosis induced by thioacetamide (TAA). Liver fibrosis was induced using TAA (intraperitoneal injection, two times a week for 6 weeks), in a rat model and H. pluvialis extract (200 mg/kg), and other fractions (30 mg/kg) were orally administered daily for 4 weeks after the last TAA injection. Based on HPLC analysis, H. pluvialis extract contains β-carotene (12.95 mg/g, extract) and free astaxanthin (10.85 mg/g, extract), while HPLC/ESI-MS analysis revealed that H. pluvialis extract contains 28 carotenoid compounds including three isomers of free astaxanthin, α or β-carotene, lutein, 14 astaxanthin mono-esters, 5 astaxanthin di-esters, and other carotenoids. H. pluvialis and its fractions reduced liver enzymes, nitric oxide, collagen 1, alpha-smooth muscle actin, and transforming growth factor-beta as well as elevated catalase antioxidant activity compared to the TAA group. Also, H. pluvialis extract and its fractions exceedingly controlled the balance between metalloproteinase and its inhibitor, activated Kupffer cells proliferation, and suppressed liver apoptosis, necrobiosis, and fibrosis. These findings conclude that H. pluvialis extract and its fractions have an antifibrotic effect against TAA-induced liver fibrosis by regulating the oxidative stress and proinflammatory mediators, suppressing multiple profibrogenic factors, and modulating the metalloproteinase and its inhibitor pathway, recommending H. pluvialis extract and its fractions for the development of new effective medicine for treating hepatic fibrosis disorders.


1995 ◽  
Vol 5 (8) ◽  
pp. 1610-1617
Author(s):  
C W Yang ◽  
M Hattori ◽  
H Vlassara ◽  
C J He ◽  
M A Carome ◽  
...  

Nonobese diabetic (NOD) mice spontaneously develop immune-mediated insulin-dependent diabetes mellitus and nephropathy, providing an opportunity to study the early molecular events in a model of diabetic glomerulosclerosis. The expression of several genes coding for growth factors and extracellular matrix was examined in microdissected glomeruli, by the use of reverse transcription-competitive polymerase chain reaction, in diabetic NOD mice (mean duration of diabetes, 28.5 +/- 7 days) and age-matched nondiabetic NOD mice with normal glucose tolerance. The levels of mRNA coding for transforming growth factor-beta 1, tenascin, and laminin B1 increased 1.9-, 2.0-, and 1.7-fold, respectively, whereas platelet-derived growth factor (PDGF)-B, alpha 1(IV) collagen, 72-kd collagenase, alpha-smooth muscle actin, and beta-actin mRNA remained stable in the diabetic mice. The kidney advanced glycosylation end-products levels increased 2.1-fold in the diabetic mice, and the diabetic glomeruli showed an accumulation of tenascin and laminin but not of type IV collagen by immunofluorescence microscopy. There was no increase in cell number per glomerulus after the onset of diabetes, a finding consistent with stable PDGF-B and alpha-smooth muscle actin mRNA levels. These findings provide evidence that increased glomerular transforming growth factor-beta 1, but not PDGF-B, mRNA is associated with the up-regulation of tenascin and laminin expression after advanced glycosylation endproduct accumulation, early after the onset of diabetes.


2019 ◽  
Vol 39 (4) ◽  
pp. 440-450 ◽  
Author(s):  
WH El-Maadawy ◽  
OA Hammam ◽  
SH Seif el-Din ◽  
NM El-Lakkany

Autophagy and apoptosis are important players in the progression of hepatic fibrosis via activation of hepatic stellate cells (HSCs). Despite the recently depicted antifibrotic effects of alpha-lipoic acid (ALA), however, its modulatory effects on HSCs autophagy remain unverified. Our study aimed to elucidate the underlying antifibrotic mechanisms through which ALA mediates HSC autophagy and apoptosis. Liver fibrosis was induced via thioacetamide (TAA) intoxication in rats; TAA-intoxicated rats were treated with either silymarin or ALA. Effect of ALA on biochemical parameters and immunohistopathological examinations was measured and compared to silymarin. ALA restored normal hepatic architecture (S1 vs. S4), liver functions, hepatic glutathione, and transforming growth factor-β1 levels. ALA ameliorated hepatic levels of malondialdehyde, platelet-derived growth factor, tissue inhibitor metalloproteinases-1, hydroxyproline, and expression of alpha-smooth muscle actin. Moreover, ALA significantly reduced messenger RNA expression of LC3-II genes and triggered caspase-3 expression. Interestingly, ALA exhibited superior activities over silymarin regarding suppression of proliferation, activation and autophagy of HSCs, collagen deposition, and induction of HSCs apoptosis. In conclusion, treatment of TAA-intoxicated rats with ALA inhibited autophagy and induced apoptotic clearance of activated HSCs. Accordingly, this study provides mechanistic insights into the possible applicability of ALA in the treatment of hepatic fibrosis.


2017 ◽  
Vol 45 (05) ◽  
pp. 1061-1074 ◽  
Author(s):  
Jiamei Chen ◽  
Xuewei Li ◽  
Yonghong Hu ◽  
Wei Liu ◽  
Qun Zhou ◽  
...  

Gypenosides (GPs), the predominant components of Gynostemma pentaphyllum, exert antifibrotic effects; however, the mechanisms underlying their ability to ameliorate liver fibrosis are unclear. Liver fibrosis was induced in C57BL/6 mice via subcutaneous injection of 10% carbon tetrachloride (CCl[Formula: see text] three times a week for two weeks. Then, CCl4 was administered in conjunction with intragastric GPs for another three weeks. For in vitro analyses, WB-F344, hepatatic progenitor cells (HPCs) were treated with transforming growth factor beta 1 (TGF-[Formula: see text]1) with or without GPs for 48[Formula: see text]h. The results showed that alanine aminotransferase (ALT) and aspartate transaminase (AST) activity, deposition of collagen, hydroxyproline content, and expression of alpha-smooth muscle actin ([Formula: see text]-SMA) and collagen type I (Col I) were significantly decreased after treatment with GPs ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]). In the 5M CCl4 group, the expression of HPC markers, Sox9 and cytokeratin 19 (CK19), was significantly increased compared with the normal or GPs-treated group ([Formula: see text], [Formula: see text]). Immunostaining showed that the number of Sox9 and [Formula: see text]-SMA double-positive cells was higher in the 5M CCl4 group than in the normal group, but the addition of GPs caused this cell number to decrease. In WB-F344 cells, the expression of [Formula: see text]-SMA and Col I was significantly increased after treatment with TGF-[Formula: see text], whereas in the GPs treatment group, expression was markedly decreased ([Formula: see text]). The levels of TGF-[Formula: see text] and TGF-[Formula: see text]R1 were markedly reduced after GPs treatment both in vivo and in vitro. In conclusion, GPs ameliorated CCl4-induced liver fibrosis via the inhibition of TGF-[Formula: see text] signaling, consequently inhibiting the differentiation of HPCs into myofibroblasts.


Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1628
Author(s):  
Kaj E. C. Blokland ◽  
Habibie Habibie ◽  
Theo Borghuis ◽  
Greta J. Teitsma ◽  
Michael Schuliga ◽  
...  

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease with poor survival. Age is a major risk factor, and both alveolar epithelial cells and lung fibroblasts in this disease exhibit features of cellular senescence, a hallmark of ageing. Accumulation of fibrotic extracellular matrix (ECM) is a core feature of IPF and is likely to affect cell function. We hypothesize that aberrant ECM deposition augments fibroblast senescence, creating a perpetuating cycle favouring disease progression. In this study, primary lung fibroblasts were cultured on control and IPF-derived ECM from fibroblasts pretreated with or without profibrotic and prosenescent stimuli, and markers of senescence, fibrosis-associated gene expression and secretion of cytokines were measured. Untreated ECM derived from control or IPF fibroblasts had no effect on the main marker of senescence p16Ink4a and p21Waf1/Cip1. However, the expression of alpha smooth muscle actin (ACTA2) and proteoglycan decorin (DCN) increased in response to IPF-derived ECM. Production of the proinflammatory cytokines C-X-C Motif Chemokine Ligand 8 (CXCL8) by lung fibroblasts was upregulated in response to senescent and profibrotic-derived ECM. Finally, the profibrotic cytokines transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) were upregulated in response to both senescent- and profibrotic-derived ECM. In summary, ECM deposited by IPF fibroblasts does not induce cellular senescence, while there is upregulation of proinflammatory and profibrotic cytokines and differentiation into a myofibroblast phenotype in response to senescent- and profibrotic-derived ECM, which may contribute to progression of fibrosis in IPF.


2016 ◽  
Vol 94 (7) ◽  
pp. 779-787 ◽  
Author(s):  
Hazem Abd-Elgawad ◽  
Nashwa Abu-Elsaad ◽  
Amr El-Karef ◽  
Tarek Ibrahim

Piceatannol is a polyphenolic analog of resveratrol that selectively inhibits the non-receptor tyrosine kinase-Syk. This study investigates the potential ability of piceatannol to attenuate liver fibrosis and protect hepatocytes from injury. Thioacetamide was injected in adult male mice (100 mg/kg, i.p., 3 times/week) for 8 weeks. Piceatannol (1 or 5 mg/kg per day) was administered by oral gavage during the last 4 weeks. Liver function biomarkers, tissue malondialdehyde (MDA), cytokeratin-18 (CK18), hepatocyte growth factor (HGF), and interleukin-10 (IL-10) were measured. Necroinflammation, fibrosis, expression of transforming growth factor (TGF)-β1, and α-smooth muscle actin (SMA) were scored by histopathological examination and immunohistochemistry. Obtained results showed ability of piceatannol (1 mg/kg) to restore liver function and reduce inflammation. It significantly (p < 0.001) reduced MDA, CK18, TGF-β1, and α-SMA expression, and increased HGF and IL-10. It can be concluded that piceatannol at low dose can inhibit TGF-β1 induced hepatocytes apoptosis and exerts an anti-inflammatory effect attenuating fibrosis progression.


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