The hepatic expression of vitamin D receptor is inversely associated with the severity of liver damage in genotype 1 chronic hepatitis C patients

Calcitriol ameliorates the progression of hepatic fibrosis through autophagy-related gene 16-like 1-mediated autophagy

BACKGROUND

Calcitriol has the potential to counteract fibrotic diseases beyond its classical action of maintaining calcium and bone metabolism; however, its functional mechanism remains unknown. Autophagy-related gene 16-like 1 (Atg16l1) is one of the genes related to autophagy and is involved in protecting against fibrotic diseases. The present study aimed to explore the contribution of autophagy to the inhibition of calcitriol-induced hepatic fibrosis, as well as its potential molecular mechanism.

METHODS

Carbon tetrachloride (Ccl4)-treated mice were established as hepatic fibrosis models and received calcitriol treatment for 6 weeks. Quantification of Sirius red staining and measurement of key fibrotic markers (collagen-1 and α-SMA) was performed to detect hepatic fibrosis. Chloroquine (CQ) treatment was used to observe autophagic flux, and 3-methyladenine (3-MA) was used to inhibit autophagy. Furthermore, the effects of calcitriol on transforming growth factor β1 (TGFβ1)-stimulated primary hepatic stellate cells (HSCs) were detected. Downregulation of Atg16l1 or vitamin D receptor (VDR) in LX-2 cells was used to explore the mechanism of action of calcitriol in fibrosis and autophagy. Additionally, the electrophoretic mobility shift assay (EMSA) was used to investigate the interactions between VDR and ATG16L1.

RESULTS

Calcitriol increased the expression of VDR and ATG16L1, enhanced autophagy and attenuated hepatic fibrosis. 3-MA treatment and VDR silencing abolished the protective effects of calcitriol against fibrosis. Calcitriol-induced anti-fibrosis effects were blocked by ATG16L1 suppression. Furthermore, VDR bound to the ATG16L1 promoter and downregulation of VDR decreased the expression of ATG16L1 in LX-2 cells.

CONCLUSION

Calcitriol mitigates hepatic fibrosis partly through ATG16L1-mediated autophagy.

Hepatic vitamin D receptor expression is negatively associated with liver inflammation and fibrosis in patients with chronic HBV infection

The vitamin D receptor (VDR) is a nuclear transcription factor that acts as the main transducer in response to vitamin D (VD), regulating about 3% of the gene expression in the human genome. This study investigated the expression of VDR in the liver of patients with chronic hepatitis B virus (HBV) infection and determined its correlation with liver inflammation and fibrosis. We evaluated the effects of HBV infection on the expression of VDR in vivo and in vitro and further investigate the potential mechanism. Subsequently, the associations between hepatic VDR expression with liver inflammation and fibrosis were statistically analyzed. Results showed that hepatic VDR expression was significantly decreased in patients with chronic HBV infection as compared to healthy individuals. Similarly, in vitro experiments further confirmed that HBV infection could inhibit the expression of VDR in hepatocytes. Mechanistically, HBV was able to directly induce the expression of miR-125a which inhibited the mRNA and protein levels of VDR. Statistical analysis showed that hepatic VDR expression was significantly negatively correlated with liver inflammation and fibrosis in patients. We conclude that inhibition of hepatic vitamin D receptor expression by HBV/miR-125a is negatively associated with liver inflammation and fibrosis in patients with chronic HBV infection.

The Influence of Single Nucleotide Polymorphisms on Vitamin D Receptor Protein Levels and Function in Chronic Liver Disease

Single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) gene have been associated with chronic liver disease. We investigated the role of VDR SNPs on VDR protein levels and function in patients with chronic liver disease. VDR expression levels were determined in peripheral T lymphocytes (CD3+VDR+), monocytes (CD14+VDR+), and plasma from patients (n = 66) and healthy controls (n = 38). Genotyping of SNPs and the determination of expression of VDR/vitamin D-related genes were performed by using qPCR. The effect of FokI SNP on vitamin D-binding to VDR was investigated by molecular dynamics simulations. CD14+VDR+ cells were correlated with the MELD score. The ApaI SNP was associated with decreased CD3+VDR+ levels in cirrhotic patients and with higher liver stiffness in HCV patients. The BsmI and TaqI SNPs were associated with increased VDR plasma concentrations in cirrhotic patients and decreased CD14+VDR+ levels in HCV patients. The FokI SNP was associated with increased CD3+VDR+ levels in cirrhotic patients and controls. VDR polymorphisms were significantly related to the expression of genes critical for normal hepatocyte function and immune homeostasis. VDR expression levels were related to the clinical severity of liver disease. VDR SNPs may be related to the progression of chronic liver disease by affecting VDR expression levels.

Calcipotriol attenuates liver fibrosis through the inhibition of vitamin D receptor-mediated NF-κB signaling pathway

Liver fibrosis is an inevitable stage in the development of chronic liver disease to cirrhosis. Nonetheless, the interventional treatment and achieving control over the disease at this stage can substantially reduce the incidence of liver cirrhosis. To demonstrate these aspects, liver pathological sections of 18 patients with chronic liver disease are collected for research according to the degree of fibrosis. Further, the expressions of related proteins in each group are studied by the Western blot method. The cell proliferation and apoptosis are detected by CKK-8 and flow cytometry analyses. Further, a rat model with carbon tetrachloride (CCl₄)-induced liver fibrosis is employed to verify the effect and mechanism of VDR on the process of liver fibrosis in vivo. The expression of VDR in liver tissues of patients with liver fibrosis is negatively correlated with α-smooth muscle actin (α-SMA), Col-1, and liver fibrosis stages. Moreover, the tumor necrosis factor (TNF)-α stimulation could increase the proliferation of LX-2, up-regulate the expression of α-SMA, Col-1, NF-κB, p-IκBα, p-IKKβ, p-p65m, and some fibrosis factors, as well as down-regulate the expressions of VDR and matrix metalloproteinase-1 (MMP-1). Considering the protective actions of VDR, calcipotriol, a VDR agonist, effectively reduced the degree of liver fibrosis in a rat model of liver fibrosis by inhibiting the deposition of extracellular (ECM) and activation of hepatic stellate cells (HSCs), which is negatively correlated with the degree of liver fibrosis. Together, these shreds of evidence demonstrated that the calcipotriol showed great potential in effectively attenuating liver fibrosis.

Inverse Association between Serum 25-hydroxyvitamin D Levels and Risk of Suspected Non-Alcoholic Fatty Liver Disease in Obese Population

BACKGROUND

Worldwide, vitamin D deficiency is a public health issue and the prevalence of obesity and non-alcoholic fatty liver disease (NAFLD) are rapidly increasing. There are a limited number of studies assessing the association between serum levels of 25-hydroxyvitamin D (25(OH)D) and NAFLD risk in obese population.

OBJECTIVE

We evaluated the associations between serum 25(OH)D levels and risk of suspected NAFLD after stratification by obesity using data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2014.

METHODS

This study included 25,755 subjects without significant alcohol consumption for the serum alanine aminotransferase (ALT) and hepatic steatosis index (HSI) analyses (8922 subjects for the serum gamma-glutamyl transferase (GGT) and fatty liver index (FLI) analyses), based on a cross-sectional study design. Serum 25(OH)D levels were measured using a Gamma counter with radioimmunoassay. A survey logistic regression model was applied to estimate ORs and 95% CIs. Restricted cubic smoothing splines were applied to evaluate nonlinear associations.

RESULTS

The risk of suspected NAFLD was reduced per unit of natural log-transformed serum 25(OH)D concentration in obese individuals (OR [95% (CI)]; for ALT, 0.80 [0.67, 0.96]; for GGT, 0.70 [0.49, 0.99; for FLI, 0.68 [0.47, 1.01]; for HSI, 0.70 [0.56, 0.87]). The ORs [95% CI] of suspected NAFLD changed across the quartiles: for serum ALT, from 1.02 [0.85, 1.23] to 0.72 [0.59, 0.87]; for serum GGT, from 0.79 [0.56, 1.13] to 0.64 [0.44, 0.92]; for FLI, from 0.98 [0.67, 1.44] to 0.70 [0.48, 1.02]; and for HSI, from 0.91 [0.73, 1.14] to 0.65 [0.52, 0.81] with dose-response relationships (all p for trend < 0.01).

CONCLUSIONS

This study suggests that vitamin D sufficiency for public health should be emphasized in order to prevent adverse health effects in obese populations.

Cholangiopathy aggravation is caused by VDR ablation and alleviated by VDR-independent vitamin D signaling in ABCB4 knockout mice

BACKGROUND & AIMS

Cholangiopathies are chronic liver diseases in which damaged cholangiocytes trigger a proinflammatory and profibrotic reaction. The nuclear vitamin D receptor (VDR) is highly expressed in cholangiocytes and exerts immune-regulatory functions in these cells. In the present study, we examined the protective function of VDR and other vitamin D signaling pathways in chronic cholangiopathy and cholangiocytes.

METHODS

Vdr was invalidated in Abcb4 knockout mice, a widely used animal model of chronic cholangiopathy. The impact of vitamin D signaling on cholangiopathy features was examined in vivo and in cholangiocytes (primary and cell lines).

RESULTS

Cholangiopathy features (i.e, cholestasis, ductular reaction and fibrosis) were aggravated in Vdr;Abcb4 double knockout mice compared to the Abcb4 simple knockout, and associated with an overexpression of proinflammatory factors. The proinflammatory phenotype of cholangiocytes was also exacerbated following VDR silencing in vitro. The expression of proinflammatory factors and the severity of cholangiopathy were reduced in the double knockout mice treated with the vitamin D analog calcipotriol or with vitamin D. In vitro, the inflammatory response to TNFα was significantly reduced by calcipotriol in biliary cells silenced for VDR, and this effect was abolished by co-silencing the plasma membrane receptor of vitamin D, protein disulfide-isomerase A3 (PDIA3).

CONCLUSIONS

Our results demonstrate an anti-inflammatory role of VDR signaling in cholangiocytes and cholangiopathy. They also provide evidence for PDIA3-mediated anti-inflammatory effects of vitamin D and vitamin D analog in these settings.

Is vitamin D receptor a druggable target for non-alcoholic steatohepatitis?

Nonalcoholic steatohepatitis (NASH) is a progressed stage of non-alcoholic fatty liver disease, and available therapeutic strategies for NASH are limited. Vitamin D receptor (VDR) is proposed as a druggable target for NASH due to the discovery of vitamin D deficiency in NASH patients. To date, vitamin D supplementation has not consistently conferred expected therapeutic benefits, raising the question of whether VDR can serve as a proper drug target for NASH. It is known that VDR can interact with other ligands such as bile acids in addition to vitamin D, and its expression can be induced by fatty acids, and insulin. It has also been shown that while activation of VDR in hepatic macrophages and hepatic stellate cells resulted in attenuation of hepatic inflammation and fibrosis, activation of VDR in hepatocytes could accelerate lipid accumulation. Thus, the multiplicity of VDR ligands, together with the cell type-specificity of VDR activation, must be taken into consideration in assessing the validity of VDR being a potential druggable target for NASH treatment. To this end, we have evaluated the relationship between VDR activation and various contributing factors, such as gut microbiota, bile acid, fatty acids, and insulin, in addition to vitamin D, with an expectation that a potential drug might be identified that can elicit VDR activation in a tissue- and/or cell type-specific manner and therefore achieving therapeutic benefits in NASH.

Relationship between hepatic and systemic angiopoietin-like 3, hepatic Vitamin D receptor expression and NAFLD in obesity

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and an independent risk factor for cardiovascular mortality. Angiopoietin-like proteins (ANGPTLs) are targets for vitamin D receptor (VDR)-mediated gene transcription and this axis may promote NAFLD. ANGPTL3 is a hepatokine which inhibits lipoprotein lipase and its experimentally induced inactivation reduces hepatosteatosis. Little is known on ANGPTL3 in human NAFLD and no data exist on its relationship with hepatic VDR/VD-related genes. The aim of this research was to investigate hepatic ANGPTLs and VDR/VD-related gene expression in human obesity in relation to NAFLD.

METHODS

We conducted a cross-sectional investigation on forty obese subjects with/without NAFLD. We evaluated hepatic ANGPTL3, ANGPTL4, ANGPTL8, LPL, VDR, CYP27A1 and CYP2R1 mRNA expression in liver biopsies by RT-PCR; VDR expression was further investigated by immunohistochemistry; circulating ANGPTL3 was measured by Milliplex assay.

RESULTS

Compared to non-NAFLD, NAFLD individuals had significantly higher hepatic VDR, ANGPTL3 and LPL expression. ANGPTL3 correlated with steatosis grade, LPL, VDR, CYP27A1 and CYP2R1 expression. Plasma ANGPTL3 concentrations were positively associated with clinical/histological markers of NAFLD/NASH and with hepatic ANGPTL3 expression. Greater hepatic VDR expression was the main determinant of hepatic ANGPTL3 after adjusting for multiple confounders.

CONCLUSIONS

Hepatic ANGPTL3 expression correlates with greater VDR expression, presence and severity of NAFLD and translates in increased circulating ANGPTL3, likely as a result of its modulation by up-regulated hepatic VDR in NAFLD. This study provides novel insights to potential mechanisms underlying ANGPTLs-mediated ectopic fat accumulation and NAFLD development in obesity.

Correlation of vitamin D with inflammatory factors, oxidative stress and T cell subsets in patients with autoimmune hepatitis

Correlation of vitamin D with inflammatory factors, oxidative stress and T cell subsets in patients with autoimmune hepatitis were investigated. Patients with liver diseases (n=635) treated in The Sixth People's Hospital of Qingdao City from March 2015 to January 2018 were selected, among which 80 cases diagnosed with autoimmune hepatitis were included into observation group, and 80 healthy cases were included into control group. Patients with autoimmune hepatitis were further divided into normal 25-hydroxyvitamin D [25-(OH) D] group (n=40) and abnormal 25-(OH) D group (n=40) according to the level of 25-(OH) D, and divided into normal liver function group (n=40) and abnormal liver function group (n=40). 25-(OH) D, liver function, inflammatory factors, oxidative stress level and T cell subsets were compared. In the observation group, levels of 25-(OH) D, superoxide dismutase (SOD), total antioxidant capacity, and T cell subsets were lower than those in the control group (P<0.05), while levels of total bilirubin (TBIL), indirect BIL (IBIL), direct BIL (DBIL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), inflammatory factors and malondialdehyde (MDA) were higher than those in the control group (P<0.05). In the normal 25-(OH) D group, levels of inflammatory factors and oxidative stress factor were lower than those in the abnormal 25-(OH) D group (P<0.05), while the SOD level, total antioxidant capacity and T cell subset counts were higher than those in the abnormal 25-(OH) D group (P<0.05). Moreover, the 25-(OH) D level in patients with autoimmune hepatitis was negatively correlated with hs-CRP, tumor necrosis factor-α (TNF-α), ALT and MDA, but positively correlated with CD3⁺ and CD4⁺ counts, SOD and total antioxidant capacity. Patients with autoimmune hepatitis, especially those with decreased level of vitamin D, are more prone to enhanced inflammatory and stress responses, decreased levels of T cell subsets and decline in immunity.

Overview of studies of the vitamin D/vitamin D receptor system in the development of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. NAFLD is known to be associated with obesity, type 2 diabetes, metabolic syndrome and increased cardiovascular events: for these reasons, it is becoming a global public health problem and represents an important challenge in terms of prevention and treatment. The mechanisms behind the pathogenesis of NAFLD are multiple and have not yet been completely unraveled; consequently, at moment there are not effective treatments. In the past few years a large body of evidence has been assembled that attributes an important role in hepatic aberrant fat accumulation, inflammation and fibrosis, to the vitamin D/vitamin D receptor (VD/VDR) axis, showing a strong association between hypovitaminosis D and the diagnosis of NAFLD. However, the data currently available, including clinical trials with VD supplementation, still provides a contrasting picture. The purpose of this editorial is to provide an overview of recent advances in the pathogenesis of NAFLD in relation to VD/VDR. Based on recent data from literature, we focused in particular on the hypothesis that VDR itself, independently from its traditional ligand VD, may have a crucial function in promoting hepatic fat accumulation. This might also offer new possibilities for future innovative therapeutic approaches in the management of NAFLD.

Evolving Role of Vitamin D in Immune-Mediated Disease and Its Implications in Autoimmune Hepatitis

Vitamin D has immunomodulatory, anti-inflammatory, antioxidant, and anti-fibrotic actions that may impact on the occurrence and outcome of immune-mediated disease. The goals of this review are to describe the nature of these expanded roles, examine the implications of vitamin D deficiency in autoimmune hepatitis, and identify opportunities for future investigation. Abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Vitamin D receptors are expressed on the principal cell populations involved in the innate and adaptive immune responses. Macrophages and dendritic cells can produce 1,25-dihydroxyvitamin D within the microenvironment. This active form of vitamin D can inhibit immune cell proliferation, promote an anti-inflammatory cytokine profile, expand regulatory T cells, enhance glucocorticoid actions, increase glutathione production, and inhibit hepatic stellate cells. Vitamin D deficiency has been commonly present in patients with immune-mediated liver and non-liver diseases, and it has been associated with histological severity, advanced hepatic fibrosis, and non-response to conventional glucocorticoid therapy in autoimmune hepatitis. Vitamin D analogues with high potency, low calcemic effects, and independence from hepatic hydroxylation are possible interventions. In conclusion, vitamin D has properties that could ameliorate immune-mediated disease, and vitamin D deficiency has been a common finding in immune-mediated liver and non-liver diseases, including autoimmune hepatitis. Loss of vitamin D-dependent homeostatic mechanisms may promote disease progression. Vitamin D analogues that are independent of hepatic hydroxylation constitute an investigational opportunity to supplement current management of autoimmune hepatitis.

Vitamin D deficiency in hepatitis C virus infection: what is old? what is new?

In the past few years, a growing body of clinical evidence has highlighted the risk of vitamin D deficiency in patients with chronic hepatitis C and that vitamin D levels are associated with the course of hepatitis C virus (HCV) infection, adverse effects, and treatment response to peginterferon/ribavirin. Recently, studies have found that vitamin D status is related to drug resistance and increased risk of infection in patients with liver cirrhosis. Vitamin D-related gene polymorphisms have been found to explain the interactions between vitamin D deficiency and HCV infection, offering a new perspective toward understanding the current problems such as the development of insulin resistance and racial differences in sustained virological response. Studies have been conducted to determine whether vitamin D supplementation as an adjuvant yields a better result compared with traditional HCV treatment. Here, we provide a brief review of the past and present knowledge of vitamin D in HCV infection.

Autophagy, apoptosis, vitamin D, and vitamin D receptor in hepatocellular carcinoma associated with hepatitis C virus

The aims of this study were to investigate the interplay between autophagy and apoptosis and to investigate the association between both of autophagy and apoptosis and vitamin D and its receptor in hepatitis C virus (HCV) viral infection and its implication in the progression into hepatocellular carcinoma (HCC).A cross-sectional study where serum levels of microtubule-associated protein 1A/1B-light chain 3 (LC3); marker of autophagy, caspase-3; marker of apoptosis, vitamin D3 and vitamin D receptor (VDR) were measured in healthy subjects as well as HCV and HCV-HCC patients using enzyme-linked immunosorbent assay technique.Collectively, the liver profile revealed hepatic dysfunctions in HCV patients with or without HCC. A significant reduction in the serum concentration levels LC3 and caspase-3 were observed referring to the down regulation of autophagy and host-mediated apoptosis in HCV patients with or without HCC. Deficiency of vitamin D and decreased levels of its receptor were observed in HCV and HCV-HCC patients.The perturbation in vitamin D/VDR axis, which modulates both of autophagy and apoptosis in HCV infection, may point out to its involvement and implication in the pathogenesis of HCV infection and the development of HCV-related HCC. Therefore, supplementation with vitamin D may not be the only solution to restore the vital biological functions of vitamin D but VDR-targeted therapy may be of great importance in this respect.

Current therapies in alleviating liver disorders and cancers with a special focus on the potential of vitamin D

Background

Liver dysfunction is a topic of global concern with many advancing therapies being researched. Though vitamin D takes a center place, other therapies especially nutritional are also gaining ground. Vitamin D has gone beyond its role in skeletal disorders by showcasing its associations in other metabolic dysfunctions too.

Result

Epidemiological evidences show a correlation between the status of vitamin D and different forms of cancer. Vitamin D receptors and alterations in gene expression appear decisive in the development of chronic liver disorders. Nutritional status therefore plays a significant role in avoiding the complications related to liver dysfunctions, making it mandatory in maintaining vitamin D sufficiency in the body. Therapies with omega-3 fatty acids, antioxidants, amino acids, steroids also render benefits which could be further explored. Recent research on the progression of certain forms of liver cancer using vitamin D analogs like Seocalcitol EB 1089 has shown good promise.

Conclusion

The anti-inflammatory and immuno- regulatory properties of vitamin D makes its analogs, suitable candidates of better choice for the prevention and treatment of liver disorders and cancer.

Evaluation of genetic effect of NOS3 and G×E interaction on the variability of serum bilirubin in a Han Chinese population

Bilirubin was shown to be related to the generation and functional exertion of endothelial nitric oxide synthase (eNOS) whilst the genetic effect of NOS3 on bilirubin variability was rarely reported. Herein we assessed the associations of three single nucleotide polymorphisms (SNPs) of NOS3 (rs4496877, rs1808593, and rs3918186) with bilirubin elevation in 2077 adults. The results showed that rs1808593 was significantly associated with bilirubin elevation, and odds ratios (ORs) of dominant model for the elevation of total bilirubin (TBIL), direct bilirubin (DBIL), and indirect bilirubin (IDBIL) were 0.837, 0.821 and 0.754, respectively (P < 0.05 for all). Stratification analysis indicated that rs3918186 was significantly associated with the elevation of TBIL and IDBIL in the males, and ORs of dominant model were 1.505 and 1.440 with P < 0.05 for all. In the smoking group, significant associations of rs4496877, rs1808593, and rs3918186 with TBIL elevation were observed, and ORs of dominant model were 1.739, 0.758 and 1.626 (P < 0.05 for all). rs4496877 and rs3918186 were both associated with TBIL elevation in the drinking group, and ORs were 1.557 and 1.769 with P < 0.05 for all. In the ≥55 year-old group, rs4496877 and rs1808593 were significantly associated with DBIL and IDBIL elevations, and ORs were 1.340 and 0.790 (P < 0.05). Meanwhile, rs4496877, rs1808593, rs3918186, smoking, and drinking were shown to have a notable interaction effects on the TBIL elevation. Our findings supported that NOS3 harbors the genetic susceptibility to the bilirubin elevation. Age, gender, smoking, and drinking could be involved in the genetic modification of NOS3 on the bilirubin variability.

Oxidative Stress as a Critical Factor in Nonalcoholic Fatty Liver Disease Pathogenesis

SIGNIFICANCE

Nonalcoholic fatty liver disease (NAFLD), characterized by liver triacylglycerol build-up, has been growing in the global world in concert with the raised prevalence of cardiometabolic disorders, including obesity, diabetes, and hyperlipemia. Redox imbalance has been suggested to be highly relevant to NAFLD pathogenesis. Recent Advances: As a major health problem, NAFLD progresses to the more severe nonalcoholic steatohepatitis (NASH) condition and predisposes susceptible individuals to liver and cardiovascular disease. Although NAFLD represents the predominant cause of chronic liver disorders, the mechanisms of its development and progression remain incompletely understood, even if various scientific groups ascribed them to the occurrence of insulin resistance, dyslipidemia, inflammation, and apoptosis. Nevertheless, oxidative stress (OxS) more and more appears as the most important pathological event during NAFLD development and the hallmark between simple steatosis and NASH manifestation.

CRITICAL ISSUES

The purpose of this article is to summarize recent developments in the understanding of NAFLD, essentially focusing on OxS as a major pathogenetic mechanism. Various attempts to translate reactive oxygen species (ROS) scavenging by antioxidants into experimental and clinical studies have yielded mostly encouraging results.

FUTURE DIRECTIONS

Although augmented concentrations of ROS and faulty antioxidant defense have been associated to NAFLD and related complications, mechanisms of action and proofs of principle should be highlighted to support the causative role of OxS and to translate its concept into the clinic. Antioxid. Redox Signal. 26, 519-541.

Influence of vitamin D on liver fibrosis in chronic hepatitis C: A systematic review and meta-analysis of the pooled clinical trials data

AIM

To investigate the relationship between vitamin D and liver fibrosis in hepatitis C-monoinfected or hepatitis C virus (HCV)-human immunodeficiency virus (HIV) co-infected patients.

METHODS

Pertinent studies were located by a library literature search in PubMed/Embase/Cochrane/Scopus/LILACS by two individual reviewers. Inclusion criteria: (1) studies with patients with HCV or co-infected HCV/HIV; (2) studies with patients ≥ 18 years old; (3) studies that evaluated liver fibrosis stage, only based on liver biopsy; and (4) studies that reported serum or plasma 25(OH)D levels. Studies that included pediatric patients, other etiologies of liver disease, or did not use liver biopsy for fibrosis evaluation, or studies with inadequate data were excluded. Estimated measures of association reported in the literature, as well as corresponding measures of uncertainty, were recorded and corresponding odds ratios with 95%CI were included in a meta-analysis.

RESULTS

The pooled data of this systematic review showed that 9 of the 12 studies correlated advanced liver disease defined as a Metavir value of F3/4 with 25(OH) D level insufficiency. The meta-analysis indicated a significant association across studies.

CONCLUSION

Low vitamin D status is common in chronic Hepatitis C patients and is associated with advanced liver fibrosis.

Vitamin D Receptor Down-Regulation Is Associated With Severity of Albuminuria in Type 2 Diabetes Patients

CONTEXT

Inflammation plays an important role in albuminuria in type 2 diabetes mellitus (T2DM). The vitamin D receptor (VDR) has potent anti-inflammatory activities.

OBJECTIVE

To investigate the correlation between VDR expression and albuminuria in T2DM.

DESIGN/SETTING/PATIENTS

Renal biopsies from T2DM patients with albuminuria (n = 8) and nondiabetic subjects (n = 4) were compared for VDR expression by immunohistochemistry. Recruited T2DM patients (n = 242; estimated glomerular filtration rate > 60 mL/min/1.73 m²) were divided into three groups based on urinary albumin-to-creatinine ratio (uACR): normal albuminuria (uACR < 30 mg/g; n = 85), microalbuminuria (30 mg/g ≤ uACR < 300 mg/g; n = 84), and macroalbuminuria (uACR ≥ 300 mg/g; n = 73), with healthy individuals (n = 72) as controls. Peripheral blood mononuclear cells (PBMCs) from these subjects were analyzed for VDR mRNA (n = 314), TNF-α mRNA (n = 314), microRNA (miR)-346 (n = 120; 30 for each group), and VDR protein (n = 80; 20 for each group). PBMCs from randomly selected subjects (n = 6 for each group) were cultured ex vivo to evaluate the effect of TNF-α on miR-346 and VDR, and miR-346-mediated VDR suppression was further explored in HK2 cells.

RESULTS

VDR expression was down-regulated in PBMCs and renal tubular epithelial cells from T2DM patients with albuminuria. VDR mRNA and protein levels were both negatively correlated with uACR, and VDR mRNA was inversely correlated with TNF-α and miR-346 in PBMCs from T2DM patients. TNF-α reduced VDR while inducing miR-346 in cultured PBMCs. TNF-α suppressed VDR by up-regulating miR-346 in HK2 cells.

CONCLUSIONS

VDR down-regulation in PBMCs is independently associated with the severity of albuminuria in T2DM. TNF-α suppression of VDR in PBMCs and HK2 cells is mediated by miR-346.

Liganded Vitamin D Receptor Through Its Interacting Repressor Inhibits the Expression of Type I Collagen α1

Hepatic fibrosis is a reversible process involving plenty of transcription factors and pathways. Vitamin D receptor (VDR) as a member of ligand-induced transcription factors can interact with 9-cis retinoid X receptor (RXR) and VDR-interacting repressor (VDIR) to mediate transactivation or transrepression in the absence or in the presence of VDR ligand to regulate the expression of VDR target genes. The active form of vitamin D [1α,25(OH)2D3] can downregulate the expression of type I collagen both α1 and α2 (COLIα1 and COLIα2) in hepatic stellate cells (HSC-T6) in a time-dependent fashion, which provides a new direction for hepatic fibrosis therapy. As one of VDR target genes, rat COLIα1 gene contains 1αnVDRE (E-box1 and E-box2) in its promoter, and unliganded VDR/RXR may bind to 1αnVDRE through VDIR to mediate transactivation, whereas liganded VDR/RXR may bind to 1αnVDRE through VDIR for transrepression. The results suggested a sort of relying on each other relationship between VDR/RXR and VDIR in regulating the expression of COLIα1 gene in HSC-T6 cells, which established VDR as a potential target for blocking and even reversing hepatic fibrosis.

Osteoporosis across chronic liver disease

Osteoporosis is a complication of chronic liver disease, with impact on morbidity, quality of life, and survival. The progress of medicine and the new therapies stretched the disease's natural history and improved the survival of patients with liver disease. So, it is fundamental to make better the quality of life and to prevent complications. Metabolic bone disorders are common complications of chronic liver disease (CLD). Patients with CLD have an increased risk of bone fractures, with significant impact on morbidity, quality of life, and even on survival. Bone diseases, including osteomalacia, osteoporosis, and osteopenia, are frequently observed in many types of liver disease. The pathogenesis of damage and the mechanisms of bone loss are different in relation to the specific liver disease. The relevance of these conditions induced many authors to create a new nosographic entity known as "hepatic osteodystrophy", although this term is rarely used anymore and it is now commonly referred to as osteopenia or osteoporosis associated with chronic liver disease. This review is based on the personal experiences of the authors and upon research done of the available literature on this subject matter. The authors searched the PubMed database for publications containing the term "liver disease" in combination with "bone disease", "hepatic osteodistrophy", "osteoporosis", "osteopenia", "osteomalacia", and "fractures". They selected publications from the past 10 years but did not exclude older seminal publications, especially for colestatic liver diseases. This review of literature shows that osteoporosis crosses all CLD. It is important to underline that the progress of medicine and the new therapies stretched the disease's natural history and improved the survival of patients with CLD. It is fundamental to make better the quality of life and it is mandatory to prevent complications and in particular the osteoporotic ones, especially fractures.

L-cysteine supplementation upregulates glutathione (GSH) and vitamin D binding protein (VDBP) in hepatocytes cultured in high glucose and in vivo in liver, and increases blood levels of GSH, VDBP, and 25-hydroxy-vitamin D in Zucker diabetic fatty rats

Scope

Vitamin D binding protein (VDBP) status has an effect on and can potentially improve the status of 25(OH) vitamin D and increase the metabolic actions of 25(OH) vitamin D under physiological and pathological conditions. Diabetes is associated with lower levels of glutathione (GSH) and 25(OH) vitamin D. This study examined the hypothesis that upregulation of GSH will also upregulate blood levels of VDBP and 25(OH) vitamin D in type 2 diabetic rats.

Methods and results

L‐cysteine (LC) supplementation was used to upregulate GSH status in a FL83B hepatocyte cell culture model and in vivo using Zucker diabetic fatty (ZDF) rats. Results show that LC supplementation upregulates both protein and mRNA expression of VDBP and vitamin D receptor (VDR) and GSH status in hepatocytes exposed to high glucose, and that GSH deficiency, induced by glutamate cysteine ligase knockdown, resulted in the downregulation of GSH, VDBP, and VDR and an increase in oxidative stress levels in hepatocytes. In vivo, LC supplementation increased GSH and protein and mRNA expression of VDBP and vitamin D 25‐hydroxylase (CYP2R1) in the liver, and simultaneously resulted in elevated blood levels of LC and GSH, as well as increases in VDBP and 25(OH) vitamin D levels, and decreased inflammatory biomarkers in ZDF rats compared with those in placebo‐supplemented ZDF rats consuming a similar diet.

Conclusion

LC supplementation may provide a novel approach by which to raise blood levels of VDBP and 25(OH) vitamin D in type 2 diabetes.

Vitamin D and Osteoporosis in HIV/HCV Coinfected Patients: A Literature Review

Vitamin D deficiency further increases the risk of osteoporosis in HIV-positive patients coinfected with hepatitis C virus (HCV); however, it is still unclear whether HCV-related increased fracture risk is a function of the severity of liver disease. The aim of this review was to identify studies on associative vitamin D deficiency patterns in high-risk populations such as HIV/HCV coinfected patients. We did this by searching MEDLINE and EMBASE databases, from inception to August 2014, and included bibliographies. The final 12 articles selected are homogeneous in terms of age but heterogeneous in terms of sample size, participant recruitment, and data source. Most of the HIV/HCV coinfected patients have less than adequate levels of vitamin D. After reviewing the selected articles, we concluded that vitamin D deficiency should be regarded as a continuum and that the lower limit of the ideal range is debatable. We found that vitamin D deficiency might influence liver disease progression in HIV/HCV coinfected patients. Methodological issues in evaluating vitamin D supplementation as a relatively inexpensive therapeutic option are discussed, as well as the need for future research, above all on its role in reducing the risk of HCV-related fracture by modifying liver fibrosis progression.