Antifibrotic effects of bezafibrate and pioglitazone against thioacetamide-induced liver fibrosis in albino rats

Hepatic antifibrotic effects of Bezafibrate in vitro and in vivo models of liver fibrosis

Bezafibrate (BZF) is a drug that reduces cholesterol and triglyceride levels in the blood. Research indicates that BZF, through activation of PPAR receptors, regulates the expression of genes involved in lipid homeostasis, inflammation, cell differentiation, and proliferation. This study investigated the in vitro and in vivo effects of BZF on activated hepatic stellate cells (HSCs) and on carbon tetrachloride-induced liver fibrosis in mice. After 72 hours of treatment in vitro, BZF decreased cell proliferation, reversed the phenotype, decreased cell contraction, and induced autophagy. In addition, BZF promoted a protective effect on tetrachloride-induced liver fibrosis in mice, through antifibrotic actions. These findings suggest that BZF may have a potential antifibrotic effect, which could emerge as a possible new therapy for the treatment of liver fibrosis.

Bezafibrate reduces the damage, activation and mechanical properties of lung fibroblast cells induced by hydrogen peroxide

In pulmonary fibrosis, the proliferation of fibroblasts and their differentiation into myofibroblasts is often caused by tissue damage, such as oxidative damage caused by reactive oxygen species, which leads to progressive rupture and thus destruction of the alveolar architecture, resulting in cell proliferation and tissue remodeling. Bezafibrate (BZF) is an important member of the peroxisome proliferator-activated receptor (PPARs) family agonists, used in clinical practice as antihyperlipidemic. However, the antifibrotic effects of BZF are still poorly studied. The objective of this study was to evaluate the effects of BZF on pulmonary oxidative damage in lung fibroblast cells. MRC-5 cells were treated with hydrogen peroxide (H2O2) to induce oxidative stress activation and BZF treatment was administered at the same moment as H2O2 induction. The outcomes evaluated were cell proliferation and cell viability; oxidative stress markers such as reactive oxygen species (ROS), catalase (CAT) levels and thiobarbituric acid reactive substances (TBARS); col-1 and α-SMA mRNA expression and cellular elasticity through Young's modulus analysis evaluated by atomic force microscopy (AFM). The H2O2-induced oxidative damage decreased the cell viability and increased ROS levels and decreased CAT activity in MRC-5 cells. The expression of α-SMA and the cell stiffness increased in response to H2O2 treatment. Treatment with BZF decreased the MRC-5 cell proliferation, ROS levels, reestablished CAT levels, decreased the mRNA expression of type I collagen protein (col-1) and α-smooth muscle actin (α-SMA), and cellular elasticity even with H2O2 induction. Our results suggest that BZF has a potential protective effect on H2O2-induced oxidative stress. These results are based on an in vitro experiment, derived from a fetal lung cell line and may emerge as a possible new therapy for the treatment of pulmonary fibrosis.

Pioglitazone attenuates tamoxifen-induced liver damage in rats via modulating Keap1/Nrf2/HO-1 and SIRT1/Notch1 signaling pathways: In-vivo investigations, and molecular docking analysis

BACKGROUND

Tamoxifen (TAM) is a chemotherapeutic drug widely utilized to treat breast cancer. On the other hand, it exerts deleterious cellular effects in clinical applications as an antineoplastic agent, such as liver damage and cirrhosis. TAM-induced hepatic toxicity is mainly attributed to oxidative stress and inflammation. Pioglitazone (PIO), a peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist, is utilized to treat diabetes mellitus type-2. PIO has been reported to exert anti-inflammatory and antioxidant effects in different tissues. This research assessed the impact of PIO against TAM-induced hepatic intoxication.

METHODS

Rats received PIO (10 mg/kg) and TAM (45 mg/kg) orally for 10 days.

RESULTS

TAM increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT), triggered several histopathological alterations, NF-κB p65, increased hepatic oxidative stress, and pro-inflammatory cytokines. PIO protects against TAM-induced liver dysfunction, reduced malondialdehyde (MDA), and pro-inflammatory markers along with improved hepatic antioxidants. Moreover, PIO, increased hepatic Bcl-2 expression while reducing Bax expression and caspase-3 levels. In addition, PIO decreased Keap-1, Notch1, and Hes-1 while upregulated HO-1, Nrf2, and SIRT1. Molecular docking showed the binding affinity of PIO for Keap-1, NF-κB, and SIRT1.

CONCLUSION

PIO mitigated TAM hepatotoxicity by decreasing apoptosis, inflammation, and oxidative stress. The protecting ability of PIO was accompanied by reducing Keap-1 and NF-κB and regulating Keap1/Nrf2/HO-1 and Sirt1/Notch1 signaling. A schematic diagram illustrating the protective effect of PIO against TAM hepatotoxicity. PIO prevented TAM-induced liver injury by regulating Nrf2/HO-1 and SIRT1/Notch1 signaling and mitigating oxidative stress, inflammation, and apoptosis.

Fibroblast Activation Protein Alpha (FAPα) in Fibrosis: Beyond a Perspective Marker for Activated Stromal Cells?

The development of tissue fibrosis is a complex process involving the interaction of multiple cell types, which makes the search for antifibrotic agents rather challenging. So far, myofibroblasts have been considered the key cell type that mediated the development of fibrosis and thus was the main target for therapy. However, current strategies aimed at inhibiting myofibroblast function or eliminating them fail to demonstrate sufficient effectiveness in clinical practice. Therefore, today, there is an unmet need to search for more reliable cellular targets to contribute to fibrosis resolution or the inhibition of its progression. Activated stromal cells, capable of active proliferation and invasive growth into healthy tissue, appear to be such a target population due to their more accessible localization in the tissue and their high susceptibility to various regulatory signals. This subpopulation is marked by fibroblast activation protein alpha (FAPα). For a long time, FAPα was considered exclusively a marker of cancer-associated fibroblasts. However, accumulating data are emerging on the diverse functions of FAPα, which suggests that this protein is not only a marker but also plays an important role in fibrosis development and progression. This review aims to summarize the current data on the expression, regulation, and function of FAPα regarding fibrosis development and identify promising advances in the area.

Hepatoprotective Effects of Biochanin A on Thioacetamide-Induced Liver Cirrhosis in Experimental Rats

The protective effect of biochanin A (BCA) on the histopathology, immunohistochemistry, and biochemistry of thioacetamide (TAA)-induced liver cirrhosis in vivo was investigated. There was a significant reduction in liver weight and hepatocyte propagation, with much lower cell injury in rat groups treated with BCA (25 mg/kg and 50 mg/kg) following a TAA induction. These groups had significantly lower levels of proliferating cell nuclear antigen (PCNA) and α-smooth muscle actin (α-SMA). The liver homogenates showed increased antioxidant enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as decreased malondialdehyde (MDA) levels. The serum biomarkers associated with liver function, namely alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma glutamyl transaminase (GGT), returned to normal levels, comparable to those observed in both the normal control group and the reference control group. Taken together, the normal microanatomy of hepatocytes, the inhibition of PCNA and α-SMA, improved antioxidant enzymes (SOD, CAT, and GPx), and condensed MDA with repairs of liver biomarkers validated BCA's hepatoprotective effect.

Coleus vettiveroides ethanolic root extract protects against thioacetamide-induced acute liver injury in rats

Acute liver injury is caused by various factors, including oxidative stress and inflammation. Coleus vettiveroides, an ayurvedic medicinal plant, is known to possess antioxidant, antibacterial, and antidiabetic properties. In this current study, we investigated the protective effect of C. vettiveroides ethanolic root extract (CVERE) against thioacetamide (TAA)-induced acute liver injury in rats. A single dose of TAA (300 mg/kg, b.w., i.p.) was administered to induce acute liver injury. The treatment groups of rats were concurrently treated with CVERE (125 and 250 mg/kg, b.w., p.o.) and silymarin (100 mg/kg, b.w., p.o.), respectively. After 24 h of the experimental period, TAA-induced liver injury was confirmed by increased activity of serum transaminases and malondialdehyde levels in liver tissue, decreased levels of antioxidants, upregulated expression of the inflammatory marker gene, and altered liver morphology. Whereas CVERE simultaneous treatment inhibited hepatic injury and prevented the elevation of serum aspartate and alanine transaminases, alkaline phosphatase, and lactate dehydrogenase activities. CVERE attenuated TAA-induced oxidative stress by suppressing lipid peroxidation and restoring antioxidants such as superoxide dismutase, catalase, and reduced glutathione. Further, CVERE treatment was found to inhibit nuclear factor κB-mediated inflammatory signaling, as indicated by downregulated pro-inflammatory cytokines including tumor necrosis factor-α and interleukin-1β. Our findings suggest that CVERE prevents TAA-induced acute liver injury by targeting oxidative stress and inflammation.

Molecular mechanisms in thioacetamide-induced acute and chronic liver injury models

Thioacetamide (TAA) undergoes bioactivation in the liver by the CYP450 2E1 enzyme, resulting in the formation of TAA-S-oxide and TAA-S-dioxide. TAA-S-dioxide induces oxidative stress via lipid peroxidation of the hepatocellular membrane. A single TAA dose (50-300 mg/kg) administration initiates hepatocellular necrosis around the pericentral region after its covalent binding to macromolecules in the liver. Intermittent TAA administration (150-300 mg/kg, weekly thrice, for 11-16 weeks) activates transforming growth factor (TGF)-β/smad3 downstream signaling in injured hepatocytes, causing hepatic stellate cells (HSCs) to acquire myofibroblast like phenotype. The activated HSCs synthesize a variety of extracellular matrix, leading to liver fibrosis, cirrhosis, and portal hypertension. The TAA induced liver injury varies depending on the animal model, dosage, frequency, and routes of administration. However, TAA induces hepatotoxicity in a reproducible manner, and it is an ideal model to evaluate the antioxidant, cytoprotective, and antifibrotic compounds in experimental animals.