Vitamin D inhibits proliferation and profibrotic marker expression in hepatic stellate cells and decreases thioacetamide-induced liver fibrosis in rats.
ABSTRACT Hepatic stellate cells (HSCs) are key participants in liver fibrosis development. 1,25(OH)(2)D(3), the active form of vitamin D, has antiproliferative properties and antifibrotic potential, as well as a role in extracellular matrix and matrix metalloproteinase (MMP) regulation in renal and lung fibrosis. Little is known about the role of 1,25(OH)(2)D(3) in liver and its involvement in liver fibrosis. Therefore, we investigated the antiproliferative and antifibrotic effects of 1,25(OH)(2)D(3) in primary cultured HSCs and in a rat model of liver fibrosis induced by thioacetamide (TAA).
Primary HSCs were isolated from rats' livers and treated with 1,25(OH)(2)D(3). Proliferation was examined by bromodeoxyuridine. Vitamin D receptor (VDR) expression and several fibrotic markers were detected by western blot analysis and real-time PCR. Collagen Iα1 and MMP-9 promoter activity were measured by luciferase assay. MMP-9 enzymatic activity was investigated by zymography. VDR silencing was performed by sh-RNA. An in vivo study was performed on TAA-induced liver fibrosis model in rats treated with or without 1,25(OH)(2)D(3). The fibrotic score and collagen deposition were determined by Masson and by Sirius red staining.
While VDR was highly expressed in quiescent HSCs, its expression decreased up to 40% during activation. Addition of 1,25(OH)(2)D(3) to activated HSCs stimulated VDR expression. 1,25(OH)(2)D(3) suppressed HSC proliferation and cyclin D1 expression by ~50% and tissue inhibitor of metalloproteinase 1 (TIMP-1) by 60% and led to a 40% downregulation of collagen Iα1 expression. Moreover, 1,25(OH)(2)D(3) increased MMP-9 activity by 30%. Silencing VDR by sh-RNA demonstrated that suppression of cyclin D1 and collagen Iα1 protein expression was VDR dependent. Treatment with 1,25(OH)(2)D(3) significantly reduced extracellular matrix deposition and lowered the fibrotic score in TAA-induced liver fibrosis.
1,25(OH)(2)D(3) has antiproliferative and antifibrotic effects on liver fibrosis in in vitro and in vivo models and may be considered as having potential therapeutic value.
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ABSTRACT: This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4α, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4α), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.Archives of Toxicology 08/2013; · 5.22 Impact Factor
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ABSTRACT: Autoimmune hepatitis is an inflammation of the liver characterized by the presence of peri-portal hepatitis, hypergammaglobulinemia, and the serum autoantibodies. The disease is classified into 2 distinct types according to the nature of auto-antibodies. Disturbances of the calcium-parathyroid hormone-vitamin D axis are frequently associated with chronic liver disease. Patients with AIH have a high prevalence of vitamin D deficiency. Genetic studies have provided the opportunity to determine which proteins link vitamin D to AIH pathology, namely, the major histocompatibility complex class II molecules, vitamin D receptors, toll-like receptors, cytotoxic T lymphocyte antigen-4, cytochrome P450 CYP2D6, regulatory T cells (Tregs) and the forkhead/winged helix transcription factor 3. Vitamin D also exerts its effect on AIH through non-genomic factors, namely, mitogen-activated protein kinase signaling pathways, γδT cells, interferon-gamma nitric oxide synthase, and reactive oxygen stress. In conclusion, vitamin D may have a beneficial role in AIH and improves liver function in concanavalin A-induced mouse AIH. Calcitriol is best used for AIH because it is the active form of a vitamin D3 metabolite and its receptors are present in sinusoidal endothelial cells, Kupffer cells, stellate cells of normal livers, and the biliary cell line.Journal of Clinical Medicine Research 12/2013; 5(6):407-415.
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ABSTRACT: Epidemiological and clinical studies have indicated that low vitamin D activity is not only associated with an increased cancer risk and a more aggressive tumor growth, but also connected with an aggravated liver damage caused by chronic inflammation. Meanwhile, increasing evidence has demonstrated that 1,25(OH)2D3 (the most biologically active metabolite of vitamin D) can inhibit inflammatory response in some chronic inflammatory associated cancer, which is considered to have the anti-tumor potency. However, the interaction between 1,25(OH)2D3 and inflammation during hepatocellular carcinoma (HCC) initiation and progression is not yet clear. Here, we report an anti-tumorigenesis effect of 1,25(OH)2D3 via decreasing inflammatory cytokine secretion in HCC and hypothesize the possible underlying mechanism. Firstly, we show that the enhanced tumor growth is associated with elevated inflammatory cytokine IL-6 and TNF-α in 1α(OH)ase gene-knockout mice. Secondly, 1,25(OH)2D3 can inhibit vitamin D receptor (VDR) shRNA interfered tumor cell growth through decreasing inflammatory cytokine secretion in vitro and in vivo. Finally, using p27kip1 gene knock-out mouse model, we demonstrate that the effect of 1,25(OH)2D3 in inhibiting immune cell related inflammatory cytokine secretion, exerts in a p27kip1 gene dependent way. Collectively, 1,25(OH)2D3 inhibits HCC development through up-regulating the expression of p27kip1 in immune cell and reducing inflammatory cytokine production.Current Medicinal Chemistry 08/2013; · 4.07 Impact Factor