Genetic association of vitamin D receptor polymorphisms with primary biliary cirrhosis and autoimmune hepatitis

The associated ion between the VDR gene polymorphisms and susceptibility to hepatocellular carcinoma and the clinicopathological features in subjects infected with HBV

Aim. To evaluate the possible association between the vitamin D receptor (VDR), single-nucleotide polymorphisms (SNPs), and hepatocellular carcinoma (HCC) in patients with chronic hepatitis B virus (HBV) infection. Method. 968 chronic HBV infection patients were enrolled, of which 436 patients were diagnosed HCC patients, and 532 were non-HCC patients. The clinicopathological characteristics of HCC were evaluated. The genotypes of VDR gene at FokI, BsmI, ApaI, and TaqI were determined. Results. The genotype frequencies of VDR FokI C>T polymorphism were significantly different between HCC and non-HCC groups. HCC patients had a higher prevalence of FokI TT genotype than non-HCC subjects. With FokI CC as reference, the TT carriage had a significantly higher risk for development of HCC after adjustments with age, sex, HBV infection time, α-fetoprotein, smoking status, and alcohol intake. In addition, we also found that the TT genotype carriage of FokI polymorphisms were associated with advanced tumor stage, presence of cirrhosis, and lymph node metastasis. The SNP at BsmI, ApaI, and TaqI did not show positive association with the risk and clinicopathological features of HCC. Conclusion. The FokI C>T polymorphisms may be used as a molecular marker to predict the risk and to evaluate the disease severity of HCC in those infected with HBV.

Vitamin D in chronic liver disease

Chronic liver disease (CLD) and several related extrahepatic manifestations such as hepatic osteodystrophy are associated with deficiency of vitamin D, which has therefore been suggested as therapeutic target. Vitamin D undergoes hepatic 25-hydroxylation, rendering the liver critical to the metabolic activation of this vitamin. Vitamin D deficiency is highly prevalent in CLD patients, and vitamin D levels are inversely related to the severity of CLD. Declining levels of carrier proteins such as albumin and vitamin D-binding protein might also be critical in CLD. Intervention studies report improvements of CLD following supplementation, and benefits to health outcomes in particular with respect to hepatitis C virus infection have recently been documented.

CONTENT

We discuss vitamin D sources, functions and metabolism with a focus on the inherent complications of analytical measurements, such as the interference of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D C-3 epimers. Global discrepancies in the definition of optimal serum 25-hydroxyvitamin D levels are covered, and the prevalence of vitamin D deficiency in CLD is reviewed. We also address the functional mechanisms underlying this deficiency, and refer to associations between genetic variation in vitamin D metabolism and CLD. Lastly, we consider the health implications of a vitamin D deficiency in CLD and consider therapeutic options.

SUMMARY

Herein, we focus on the epidemiological and functional relationships between vitamin D deficiency and CLD, followed by a discussion of the potential implications for therapeutic interventions.

Vitamin D - effects on skeletal and extraskeletal health and the need for supplementation

Vitamin D, the sunshine vitamin, has received a lot of attention recently as a result of a meteoric rise in the number of publications showing that vitamin D plays a crucial role in a plethora of physiological functions and associating vitamin D deficiency with many acute and chronic illnesses including disorders of calcium metabolism, autoimmune diseases, some cancers, type 2 diabetes mellitus, cardiovascular disease and infectious diseases. Vitamin D deficiency is now recognized as a global pandemic. The major cause for vitamin D deficiency is the lack of appreciation that sun exposure has been and continues to be the major source of vitamin D for children and adults of all ages. Vitamin D plays a crucial role in the development and maintenance of a healthy skeleton throughout life. There remains some controversy regarding what blood level of 25-hydroxyvitamin D should be attained for both bone health and reducing risk for vitamin D deficiency associated acute and chronic diseases and how much vitamin D should be supplemented.

Protective role of the vitamin D receptor

Vitamin D receptor (VDR) is found in most tissues, not just those participating in the classic actions of vitamin D such as bone, gut, and kidney. The nonclassic actions are therefore potential targets for the active metabolite of vitamin D, 1,25(OH)₂D₃. This review is intended to highlight the actions of VDR in role of protection. Medline is searched for articles describing actions of VDR on secondary hyperparathyroidism, diabetic nephropathy, hypertension and atherosclerosis. VDR exerts its protective activities through the following mechanisms: inhibition of renin-angiotensin system (RAS); regulation of proliferation and differentiation; reduction of proteinuria; anti-inflammation and anti-fibrosis. The nonclassic actions of VDR provide a number of potential new clinical applications for 1,25(OH)₂D₃ and its analogs. We believe 1,25(OH)₂D₃/VDR can be of particular value in the prevention of kidney-related diseases.

D-livering the message: the importance of vitamin D status in chronic liver disease

Vitamin D is synthesized predominantly in the liver and functions as an important secosteroid hormone with pleiotropic effects. While its key regulatory role in calcium and bone homeostasis is well established, recently there is increasing recognition that vitamin D also regulates cell proliferation and differentiation, and has immunomodulatory, anti-inflammatory and anti-fibrotic properties. These non-skeletal effects are relevant in the pathogenesis and treatment of many causes of chronic liver disease. Vitamin D deficiency is frequently present in chronic liver disease and may predict non-response to antiviral therapy in chronic hepatitis C. Small studies suggest that vitamin D supplementation improves sustained viral response rates, while 1α-hydroxylase polymorphisms and vitamin D-binding protein are also implicated in therapeutic outcomes. Vitamin D deficiency also closely relates to the severity of non-alcoholic fatty liver disease (NAFLD) and is implicated in the pathogenesis of insulin resistance, a key factor in the development of NAFLD. In preclinical studies, phototherapy and vitamin D supplementation ameliorate NAFLD histopathology, while vitamin D is a powerful anti-fibrotic against thioacetamide liver injury. In liver transplant recipients severe vitamin D deficiency predicts, and vitamin D supplementation prevents, acute cellular rejection. The role of vitamin D in the activation and regulation of both innate and adaptive immune systems may explain its importance in the above liver diseases. Further prospective studies are therefore warranted to investigate the therapeutic impact of vitamin D supplementation in chronic liver disease.

Diagnosis, pathogenesis, and treatment of autoimmune hepatitis after liver transplantation

Autoimmune hepatitis can recur or appear de novo after liver transplantation, and it can result in hepatic fibrosis, graft loss, and re-transplantation. The goals of this review are to describe the prevalence, manifestations, putative pathogenic mechanisms, outcomes, and management of these occurrences. Autoimmune hepatitis recurs in 8-12 % of transplanted patients at 1 year and 36-68 % at 5 years. Recurrence may be asymptomatic and detected only by surveillance liver test abnormalities or protocol liver tissue examination. Autoantibodies that characterized the original disease, hypergammaglobulinemia, increased serum immunoglobulin G level, and histological findings of interface hepatitis, lymphoplasmacytic infiltration, perivenular hepatocyte necrosis, pseudo-rosetting, and acidophil bodies typify recurrence. Premature corticosteroid withdrawal and pre-transplant severity of the original disease are possible risk factors. De novo autoimmune hepatitis occurs in 1-7 % of patients 0.1-9 years after transplantation, especially in children. The appearance of autoantibodies may herald its emergence, and antibodies to glutathione-S-transferase T1 have been predictive of the disease. Recurrent disease may reflect recruitment of residual memory T lymphocytes and host-specific genetic predispositions, whereas de novo disease may reflect an allo-antigenic immune response and molecular mimicries that override self-tolerance. Treatment should be appropriate for autoimmune hepatitis and not based on anti-rejection drugs. Corticosteroid therapy alone or combined with azathioprine is the essential treatment. The substitution of mycophenolate mofetil for azathioprine and switch of the calcineurin inhibitor or its replacement with rapamycin have also been used for refractory disease. Re-transplantation has been necessary in 8-23 %.

Vitamin D receptor gene polymorphism and its association with 1,25-dihydroxyvitamin D₃ in patients with Graves disease in an Egyptian population: a pilot study

OBJECTIVE

To study the association of vitamin D receptor (VDR) gene polymorphisms (BsmI, ApaI, and TaqI) with susceptibility to Graves disease (GD) in Egyptian patients and their correlation with serum levels of 1,25-dihydroxyvitamin D₃ [1,25(OH)2D3].

METHODS

The current study consisted of 90 patients with GD (65 women and 25 men), with ages ranging from 25 to 55 years. A control group of 55 healthy euthyroid subjects (40 women and 15 men) with matched ages were included in the study. Genotyping was performed by restriction fragment length polymorphism analysis. Serum levels of 1,25(OH)2D3 were measured with use of radioimmunoassay in the patients and the control subjects.

RESULTS

The distribution of genotype frequencies differed significantly between patients with GD and control subjects (BsmI: χ² = 10.627, P = .004; ApaI: χ² = 12.581, P = .001; TaqI: χ² = 9.591, P = .008). We found overexpression of the VDR BsmI "bb" (odds ratio, 2.360; 95% confidence interval [CI], 1.11 to 4.996), ApaI "aa" (odds ratio, 2.785; 95% CI, 1.116 to 6.933), and TaqI "TT" (odds ratio, 3.047; 95% CI, 1.478 to 6.283) genotypes in patients with GD in comparison with control subjects. In contrast, no correlation was observed with respect to the 1,25(OH)2D3 levels with BsmI, ApaI, and TaqI genotypes (P>.05) on the analysis of variance test.

CONCLUSION

These data suggested that BsmI, ApaI, and TaqI polymorphisms in the VDR gene were associated with susceptibility to GD, whereas BsmI, ApaI, and TaqI polymorphisms were not associated with serum levels of 1,25(OH)2D3.

The role of vitamin D in children with recurrent tonsillopharyngitis

Background

The exact etiology of recurrent tonsillopharyngitis in children is not clear. Recurrent tonsillitis in children has multifactorial etiology like most of the diseases in childhood. In this study, our aim was to determine the potential role of vitamin D in recurrent tonsillitis by measuring serum 25-OH vitamin D levels and determining the vitamin D receptor polymorphism among children with recurrent tonsillitis.

Methods

Eighty-four children with recurrent tonsillitis and seventy-one healthy children aging between 2 and 10 years were enrolled in this study. Serum 25-OH vitamin D level was measured with ELISA and vitamin D receptor gene polymorphism (Apa1, Taq 1, Fok1) was determined by PCR. Serum 25-OH vitamin D level below 50 nmol/L was accepted as deficiency. The vitamin D receptor gene polymorphism in each group was compared.

Results

The mean age was 5.6 ± 2.4 and 6.1 ± 2.7 years in study and control group, respectively. The average serum 25-OH vitamin D level was 142.7 ± 68.1 nmol/L in study group and 192.3 ± 56.1 nmol/L in control group. There was significant difference between the groups (p < 0.01). In study group, 4.7% (n = 4) of children had serum 25 OH vitamin D levels below 50 nmol/L. None of the children in control group had serum 25-OH vitamin D level below 50 nmol/L. There was no significant differences in vitamin D receptor gene polymorphisms between groups.

Conclusion

Serum 25-OH vitamin D levels in recurrent tonsillitis group were lower than those in healthy children. But, there was no difference in the incidence of vitamin D receptor gene polymorphism between the two groups.

Vitamin d receptor polymorphisms predispose to primary biliary cirrhosis and severity of the disease in polish population

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver condition characterized by the immune-mediated damage of the intrahepatic bile ducts. Polymorphisms of vitamin D receptor (VDR) are considered to contribute to its pathogenesis however their incidence varies in different populations and their potential association with the course of the disease has not been studied. In this paper we investigated the incidence and correlation of three VDR polymorphisms (BsmI, ApaI or TaqI) with various clinical, biochemical, and serological factors in a homogenous group of 143 Caucasian patients with PBC. Control group comprises 306 DNA samples from umbilical cord blood of healthy newborn children. When compared to controls, we observed a significant dominance of the b allele in the BsmI (OR = 1.69 [1.27-2.24]; P = 0.0003) and t allele in the TaqI (OR = 0.62 [0.47-0.82], P = 0.0001) in patients with PBC. Moreover the BsmI and TaqI polymorphisms were associated with the presence of advanced fibrosis/liver cirrhosis at the diagnosis of PBC. Pairwise linkage disequilibrium (LD) calculations proved that the analyzed SNPs are within an LD block (100% of LDs were D'>0.9). Our study showed, for the first time, that the analyzed polymorphisms of VRD may exert an effect on a natural history of PBC.

Genetic variations in bile acid homeostasis are not overrepresented in alcoholic cirrhosis compared to patients with heavy alcohol abuse and absent liver disease

Increased serum bile salt levels have been associated to a single-nucleotide polymorphism in the bile salt export pump (BSEP; ABCB11) in several acquired cholestatic liver diseases but there is little evidence in alcoholic liver disease (ALD). Furthermore, a crosstalk between vitamin D and bile acid synthesis has recently been discovered. Whether this crosstalk has an influence on the course of ALD is unclear to date. Our aim was to analyse the role of genetic polymorphisms in BSEP and the vitamin D receptor gene (NR1I1) on the emergence of cirrhosis in patients with ALD. Therefore, 511 alcoholic patients (131 with cirrhosis and 380 without cirrhosis) underwent ABCB11 genotyping (rs2287622). Of these, 321 (131 with cirrhosis and 190 without cirrhosis) were also tested for NR1I1 polymorphisms (bat-haplotype: BsmI rs1544410, ApaI rs7975232 and TaqI rs731236). Frequencies of ABCB11 and NR1I1 genotypes and haplotypes were compared between alcoholic patients with and without cirrhosis and correlated to serum bile salt, bilirubin and aspartate aminotransferase levels in those with cirrhosis. Frequencies of ABCB11 and NR1I1 genotypes and haplotypes did not differ between the two subgroups and no significant association between genotypes/haplotypes and liver function tests could be determined for neither polymorphism. We conclude that ABCB11 and NR1I1 polymorphisms are obviously not associated with development of cirrhosis in patients with ALD.

Combined effect of 25-OH vitamin D plasma levels and genetic vitamin D receptor (NR 1I1) variants on fibrosis progression rate in HCV patients

BACKGROUND

Decreased vitamin D levels have been described in various forms of chronic liver disease and associated with advanced fibrosis. Whether this association is a cause or consequence of advanced fibrosis remains unclear to date.

AIMS

To analyse combined effects of 25-OH vitamin D plasma levels and vitamin D receptor gene (VDR; NR1I1) polymorphisms on fibrosis progression rate in HCV patients.

METHODS

251 HCV patients underwent VDR genotyping (bat-haplotype: BsmI rs1544410 C, ApaI rs7975232 A and TaqI rs731236 A). Plasma 25-OH vitamin D levels were quantified in a subgroup of 97 patients without advanced fibrosis. The VDR haplotype and genotypes as well as plasma 25-OH vitamin D levels were associated with fibrosis progression.

RESULTS

The bAt[CCA]-haplotype was significantly associated with fibrosis progression >0.101 U/year (P = 0.007; OR = 2.02) and with cirrhosis (P = 0.022; OR = 1.84). Forty-five percent of bAt[CCA]-haplotype patients were rapid fibrosers, 21.1% were cirrhotic. Likewise, ApaI rs7975232 CC genotype was significantly associated with fibrosis progression and cirrhosis. Lower plasma 25-OH vitamin D levels were significantly associated with fibrosis progression >0.101 U/year in F0-2 patients (P = 0.013). Combined analysis of both variables revealed a highly significant additive effect on fibrosis progression with 45.5% rapid fibrosers for bAt[CCA]-haplotype and 25-OH vitamin D < 20 μg/L compared with only 9.1% for the most favourable combination (P = 0.006). In multivariate analysis, the bAt-haplotype was an independent risk factor for fibrosis progression (P = 0.001; OR = 2.83).

CONCLUSION

Low 25-OH vitamin D plasma levels and the unfavourable VDR bAt[CCA]-haplotype are associated with rapid fibrosis progression in chronic HCV patients. In combination, both variables exert significant additive effects on fibrosis progression.

Association of polymorphisms in non-classic MHC genes with susceptibility to autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis is a chronic, generally progressive inflammatory disorder of the liver, of which the cause is unclear. It was demonstrated that genetic factors are involved in its pathogenesis. Previous studies showed that human leukocyte antigen in the major histocompatibility complex (MHC) is associated with susceptibility to autoimmune hepatitis. Current genome scanning studies suggest that genes outside the MHC also play a critical role in autoimmune disorders. This article focuses on our current understanding of the polymorphisms of these genes and their roles in the pathogenesis of autoimmune hepatitis.

DATA SOURCES

Studies were identified by searching MEDLINE and PubMed for articles using the keywords autoimmune hepatitis, polymorphism, CTLA-4, Fas, TNF-alpha, TGF-beta1, TBX21 and VDR up to May 2011. Additional papers were identified by a manual search of the references from key articles.

RESULTS

According to the case-control studies on genetic polymorphisms, at least six genes (CTLA-4, Fas, TNF-alpha, TGF-beta1, TBX21 and VDR) are involved in autoimmune hepatitis besides HLA. So far, there has been no agreement about gene susceptibility and the actual clinical significance of these genes is still controversial.

CONCLUSION

Studies on gene polymorphisms outside the MHC and knowledge of genetic predispositions for autoimmune hepatitis may not only elucidate pathogenic mechanisms, but also provide new targets for therapy in the future.

Analysis of vitamin D receptor gene (VDR) polymorphisms in Turner syndrome patients

Individuals with Turner syndrome (TS) have increased risk for autoimmune diseases, especially thyroid abnormalities. The function of the vitamin D receptor (VDR) gene is influenced by several genetic polymorphisms which are associated with a susceptibility to a range of autoimmune diseases. Thus, we have hypothesized a possible relationship between thyroid abnormalities and VDR polymorphisms (ApaI/G1025-49T, TaqI/T1056C, FokI/T2C and BsmI G1024 + 283A) in TS patients. A case-control study was performed comprising 101 Brazilian women with TS and a control group consisting of 133 healthy fertile women without a history of autoimmune diseases. In TS group, 21.8% had Hashimoto's thyroiditis. Detection of VDR polymorphisms was performed using TaqMan system by real-time PCR. The χ(2) was used to compare allele and genotype frequencies between groups. Combined genotypes of VDR gene polymorphisms were assessed by the haplotype analysis. A p value <0.05 was considered statistically significant. Relatively similar VDR polymorphisms genotype and allelic frequencies in cases and controls were found, even when only considering the patients with thyroid abnormalities. Haplotype analysis showed that none of the VDR haplotypes were associated to thyroid diseases in TS patients. In conclusion, the results showed no association between VDR gene polymorphisms and thyroid abnormalities in Brazilian TS patients tested.

Epidemiology and treatment of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic inflammatory disease of the liver that occurs worldwide with a low and probably underestimated prevalence. Although it typically affects young and middle-aged women, it can occur in both sexes and across all age groups. AIH runs a fluctuating course, but can present as severe and even fulminant hepatic failure or at a stage of advanced fibrosis or cirrhosis. Prognosis of severe AIH is poor if untreated. The pathogenesis is complex, combining environmental factors (external chemical or infectious triggers) and host genetic susceptibility. The diagnosis is based, after exclusion of other etiologies of chronic liver disease, on a combination of different elements, including the presence of elevated transaminases, elevated immunoglobulin G (IgG) levels, the presence and pattern of typical autoantibodies, and a liver biopsy showing interface hepatitis and other characteristic features. No single test can be used to make the diagnosis. Response to treatment can also help to establish the diagnosis. Simplified criteria can be used to make a bedside diagnosis with relatively high accuracy. Treatment consists of corticosteroids or other immunosuppressive regimens according to the severity of the disease, the response to the treatment, and the tolerance to therapy, with liver transplantation as an ultimate remedy in treatment-resistant cases with liver decompensation.

Nuclear receptor variants in liver disease

This review aims to provide a snapshot of the actual state of knowledge on genetic variants of nuclear receptors (NR) involved in regulating important aspects of liver metabolism. It recapitulates recent evidence for the application of NR in genetic diagnosis of monogenic ("Mendelian") liver disease and their use in clinical diagnosis. Genetic analysis of multifactorial liver diseases such as viral hepatitis or fatty liver disease identifies key players in disease predisposition and progression. Evidence from these analyses points towards a role of NR polymorphisms in common diseases, linking regulatory networks to complex and variable phenotypes. The new insights into NR variants also offer perspectives and cautionary advice for their use as handles towards diagnosis and treatment.

Nuclear receptor variants in liver disease

This review aims to provide a snapshot of the actual state of knowledge on genetic variants of nuclear receptors (NR) involved in regulating important aspects of liver metabolism. It recapitulates recent evidence for the application of NR in genetic diagnosis of monogenic (“Mendelian”) liver disease and their use in clinical diagnosis. Genetic analysis of multifactorial liver diseases such as viral hepatitis or fatty liver disease identifies key players in disease predisposition and progression. Evidence from these analyses points towards a role of NR polymorphisms in common diseases, linking regulatory networks to complex and variable phenotypes. The new insights into NR variants also offer perspectives and cautionary advice for their use as handles towards diagnosis and treatment.

Pathogenesis of autoimmune hepatitis

The mechanisms underlying the pathogenesis of autoimmune hepatitis are not fully understood, though there is growing evidence that genetic predisposition, molecular mimicry and/or impairment of regulatory T-cells are involved in the initiation and perpetuation of the autoimmune liver attack. The histological picture of interface hepatitis, characterized by a dense portal mononuclear cell infiltrate, was the first to suggest an autoaggressive cellular immune attack in the pathogenesis of this condition. Liver damage is likely to be orchestrated by CD4(pos) T-cells recognizing an autoantigenic liver peptide. For autoimmunity to arise, the peptide must be presented by antigen-presenting cells to naïve CD4(pos) T-helper (Th0) cells. Once activated, Th0-cells can differentiate into Th1-, Th2-, or Th17-cells, initiating a cascade of immune reactions that are determined by the cytokines they produce. Autoantigen recognition and the above effector mechanisms are opposed by regulatory T-cells, a cell subset numerically and functionally impaired in autoimmune hepatitis.

Genetic variants in fibrinolytic system-related genes in infertile women with and without endometriosis

AIMS

The aim of this study was to evaluate urokinase-type plasminogen activator gene (uPA) and thrombin-activatable fibrinolysis inhibitor gene (TAFI) genotypes in a group of infertile women with and/or without endometriosis and controls.

METHODS

A case-control study comprising 180 infertile women with endometriosis, 68 women with idiopathic infertility, and 152 fertile women as controls was carried out. Detection of uPA (C422T/rs2227564) and TAFI (G438A/rs2146881) polymorphisms was performed by TaqMan polymerase chain reaction. The results were statistically analyzed and a p-value of <0.05 was considered significant.

RESULTS

We found no association among both uPA or TAFI polymorphisms and endometriosis-related infertility (p=0.920 and p=0.356, respectively) or idiopathic infertility (p=0.502 and p=0.392, respectively) comparing to controls, even considering minimal/mild and moderate/severe endometriosis separately. Both uPA and TAFI polymorphisms were in Hardy-Weinberg equilibrium for all studied groups. The combinatory analysis of both uPA and TAFI polymorphisms to endometriosis-related infertility, idiopathic infertility, and control group showed no statistical difference to any combination.

CONCLUSION

The data suggest that, in the Brazilian population, genetic variations in both uPA and TAFI were not relevant to endometriosis and/or infertility.

Polymorphisms of estrogen receptors alpha and beta in idiopathic, infertile Brazilian men: a case-control study

Estrogen plays an important role in the human reproductive system and its action is mediated mainly by two specific receptors: α (ERα) and β (ERβ). There are polymorphic variants in both ER genes, and studies showed their association with reproductive outcomes. We aimed to determine the distribution of ERα and ERβ gene polymorphisms in idiopathic, infertile Brazilian patients in a case-control study comprising 187 idiopathic, infertile Brazilian men with nonobstructive azoospermia (NOA, n = 78) or severe oligozoospermia (SO, n = 109) and 216 fertile men. Detection of ERα (PvuII and XbaI) and ERβ (AluI and RsaI) gene polymorphisms were performed using TaqMan PCR. The results were analyzed statically, and a P-value < 0.05 was considered significant. Single-marker analysis revealed that neither PvuII nor XbaI polymorphisms of the ERα gene were associated either with NOA group (P = 0.662 and P = 0.527, respectively) or SO group (P = 0.777 and P = 1.0, respectively). Regarding ERβ polymorphisms, no statistical difference was observed between the AluI polymorphism and NOA group compared to controls (P = 1.0) or between SO group and controls (P = 0.423). We found similar results with the RsaI polymorphism. Statistical analysis did not reveal a difference between NOA (P = 0.740) and SO (P = 0.920) groups compared to controls. Combined genotypes of ERα and ERβ polymorphisms did not identify a haplotype associated with idiopathic infertility. Thus, in the Brazilian population, genetic variations in both estrogen receptors alpha (PvuII and XbaI) and beta (AluI and RsaI) were not relevant to idiopathic infertility.

Oral vitamin D replacement is effective in chronic liver disease

BACKGROUND & AIMS

End-stage chronic liver disease is associated with vitamin D deficiency but the prevalence across a broad-spectrum of liver disease is unknown. This study prospectively examines prevalence of vitamin D deficiency and response to replacement in chronic liver disease.

METHODS

One hundred and fifty-eight outpatients with chronic liver disease were enrolled. Serum 25-hydroxyvitamin D (25[OH]D) levels were classified as: severely deficient less than 25 nmol/l, deficient 25-54 nmol/l or replete greater than 54 nmol/l. Sixty-five of 158 (41%) had cirrhosis.

RESULTS

25[OH]D was suboptimal in 101/158 (64%), including severe deficiency in 24 patients (15%). Vitamin D deficiency occurred in liver disease of all aetiologies, including patients with only mild liver disease. 25[OH]D increased by 60.0% (19.11 ± 13.20 nmol/l) in patients with deficiency after vitamin D replacement and decreased by 25.2% (-18.33 ± 12.02 nmol/l) in non-treated initially replete patients over a median of 4 months.

CONCLUSIONS

Vitamin D deficiency improves with oral vitamin D supplementation and levels fall without supplementation. Chronic liver disease patients are at very high risk of vitamin D deficiency regardless of etiology or severity.

Drug-induced autoimmune-like hepatitis

The clinical phenotype of classical autoimmune hepatitis can be mimicked by idiosyncratic drug-induced liver injury, and differentiation can be difficult. The goals of this review are to enumerate the major agents of drug-induced autoimmune-like hepatitis, describe the clinical findings and risk factors associated with it, detail the clinical tools by which to assess causality, discuss putative pathogenic mechanisms, and describe treatment and outcome. The frequency of drug-induced autoimmune-like hepatitis among patients with classical features of autoimmune hepatitis is 9%. Minocycline and nitrofurantoin are implicated in 90% of cases. Female predominance, acute onset, and absence of cirrhosis at presentation are important clinical manifestations. Genetic factors affecting phase I and phase II transformations of the drug, polymorphisms that protect against cellular oxidative stress, and human leukocyte antigens that modulate the immune response may be important pathogenic components. Clinical judgment is the mainstay of diagnosis as structured diagnostic methods for drug-induced liver injury are imperfect. The covalent binding of a reactive drug metabolite to a hepatocyte surface protein (commonly a phase I or phase II enzyme), formation of a neoantigen, activation of CD8 T lymphocytes with nonselective antigen receptors, and deficient immune regulatory mechanisms are the main bases for a transient loss of self-tolerance. Discontinuation of the offending drug is the essential treatment. Spontaneous improvement usually ensues within 1 month. Corticosteroid therapy is warranted for symptomatic severe disease, and it is almost invariably effective. Relapse after corticosteroid withdrawal probably does not occur, and its absence distinguishes drug-induced disease from classical autoimmune hepatitis.

Nuclear receptors as new perspective for the management of liver diseases

Nuclear receptors (NRs) are ligand-activated transcription factors that act as sensors for a broad range of natural and synthetic ligands and regulate several key hepatic functions including bile acid homeostasis, bile secretion, lipid and glucose metabolism, as well as drug deposition. Moreover, NRs control hepatic inflammation, regeneration, fibrosis, and tumor formation. Therefore, NRs are key for understanding the pathogenesis and pathophysiology of a wide range of hepatic disorders. Finally, targeting NRs and their alterations offers exciting new perspectives for the treatment of liver diseases.

Vitamin D and the vitamin D receptor in liver pathophysiology

Vitamin D through the vitamin D nuclear receptor (VDR) plays a key role in mineral ion homeostasis. The liver is central in vitamin D synthesis, however the direct involvement of the vitamin D-VDR axis on the liver remains to be evaluated. In this review, we will describe vitamin D metabolism and the mechanisms of homeostatic control. We will also address the associations between the vitamin D-VDR axis and pathological liver entities, such as non-alcoholic fatty liver disease, autoimmune liver disease, viral hepatitis and liver cancer. The link between liver diseases and the vitamin D-VDR axis will be discussed in light of evidences arising from in vitro and in vivo studies. Finally, we will consider the therapeutic potential of the vitamin D-VDR axis in liver diseases.

Genetic background of autoimmune hepatitis in Japan

Autoimmune hepatitis (AIH) is an organ-specific autoimmune disease characterized by chronic inflammation of the liver. Several studies from ethnically different countries have clarified that the genetic predisposition to type 1 AIH is linked mainly to human leukocyte antigen (HLA)-class II genes. Recently, molecular analysis using polymerase chain reaction (PCR)-based DNA typing has revealed that susceptibility to type 1 AIH is primarily associated with the HLA class II DRB1 locus, which encodes a polymorphic β chain of the HLA-DR antigen. However, additional susceptibility genes (either HLA or non-HLA) and/or environmental factors may also contribute to the development of type 1 AIH; in Japanese type 1 AIH patients, although the most influential gene in disease susceptibility is HLA-DRB1*04:05, several other genes have been identified as being involved in AIH pathogenesis or resistance and are the currently the focus of single nucleotide polymorphism analysis.

Does vitamin D affect risk of developing autoimmune disease?: a systematic review

OBJECTIVES

We evaluated the epidemiologic evidence that vitamin D may be related to human autoimmune disease risk.

METHODS

PubMed, limited to English from inception through April 2010, was searched using keywords: "vitamin D," "autoimmune," and autoimmune disease names. We summarized in vitro, animal, and genetic association studies of vitamin D in autoimmune disease pathogenesis. We sorted epidemiologic studies by design and disease and performed a systematic review of (a) cross-sectional data concerning vitamin D level and autoimmune disease; (b) interventional data on vitamin D supplementation in autoimmune diseases; and (c) prospective data linking vitamin D level or intake to autoimmune disease risk.

RESULTS

Vitamin D has effects on innate and acquired immune systems, and vitamin D receptor polymorphisms have been associated with various autoimmune diseases. In experimental animal models, vitamin D supplementation can prevent or forestall autoimmune disease. Of 1446 studies identified and screened, 76 studies examined vitamin D levels in autoimmune disease patients, particularly with active disease, and compared with controls. Nineteen observational or interventional studies assessed the effect of vitamin D supplementation as therapy for various autoimmune diseases (excluding psoriasis and vitiligo) with a range of study approaches and results. The few prospective human studies performed conflict as to whether vitamin D level or intake is associated with autoimmune disease risk. No interventional trials have investigated whether vitamin D affects human autoimmune disease risk.

CONCLUSIONS

Cross-sectional data point to a potential role of vitamin D in autoimmune disease prevention, but prospective interventional evidence in humans is still lacking.

Skeletal integrity and visceral transplantation

Despite continuous improvement in long-term survival, there is no knowledge about risk of bone health impairment and management strategies before and after intestinal transplantation. Therefore, 147 adults were retrospectively studied via chart review; 70 long-term survivors, 53 candidates and 24 recipients with longitudinal follow-up. Evaluation process included measurement of bone mineral density (BMD) and allied biochemical markers. Both long-term survivors and candidates showed low bone mass with lower (p < 0.05) z-scores at hip, femoral neck and spine. Vitamin D deficiency and secondary hyperparathyroidism were observed in both groups. Prevalence of osteoporosis was 44% among long-term survivors and 36% in candidates with age, BMD, duration of parenteral nutrition, type of immunosuppression and rejection being significant risk factors. Fragility fractures occurred at a higher (p = 0.02) rate among long-term survivors (20%) compared to candidates (6%). The longitudinal study documented acceleration (p = 0.025) of bone loss after transplantation with a decline of 13.4% (femoral neck), 12.7% (hip) and 2.1% (spine). Alendronate reduced (p < 0.05) but did not prevent bone loss. In conclusion, intestinal transplant recipients are at risk of osteoporosis secondary to bone loss before and after transplantation. Accordingly, current management includes comprehensive preventive measures with prompt therapeutic intervention utilizing intravenous bisphosphonates or subcutaneous human PTH.

Autoimmune hepatitis

Autoimmune hepatitis is a chronic inflammatory disease of the liver with a dismal prognosis when left untreated. Key for the improvement of prognosis is a timely diagnosis before cirrhosis has developed. This is reached by the exclusion of other causes of hepatitis, elevated immunoglobulin G, autoantibody profile and histological assessment. Treatment achieves remission rates in 80% of individuals and consists of immunosuppression with corticosteroids and azathioprine. A recent randomised controlled multicenter trial has added budesonide to the effective treatment options in non-cirrhotic patients and leads to a reduction of unwanted steroid side effects. Autoimmune hepatitis is an autoimmune disease of unknown aetiology. Association studies of major histocompatibility complex and other genes demonstrate an influence of immunogenetics. However, apart from the autoimmune polyglandular syndrome type 1, in which 10% of patients suffer from an autoantibody-positive autoimmune hepatitis linked to mutations of the autoimmune regulator gene, there is no clear evidence for a hereditary aetiology of this disease.

Emerging opportunities for site-specific molecular and cellular interventions in autoimmune hepatitis

Current corticosteroid-based treatments of autoimmune hepatitis frequently have incomplete or unsatisfactory outcomes, side effects, and excessive immune suppression. The goal of this review is to describe the advances in developing animal models of autoimmune hepatitis and in treating diverse immune-mediated diseases that make pursuit of site-specific molecular and cellular inventions in autoimmune hepatitis feasible. Prime source and review articles in English were selected by a Medline search through October 2009. A murine model infected with an adenovirus expressing human CYP2D6 is a resource for evaluating new therapies because of its histological and serological features, persistence, and progressive hepatic fibrosis. Synthetic analog peptides that block autoantigen expression, a dimeric recombinant human fusion protein of cytotoxic T lymphocyte antigen-4, monoclonal antibodies against tumor necrosis factor-alpha, recombinant interleukin 10, tolerization techniques for disease-triggering autoantigens, T regulatory cell transfer, vaccination against antigen-specific cytotoxic CD8+ T cells, and gene silencing methods using small inhibitory RNAs are feasible interventions to explore. Treatments directed at dampening immunocyte activation with soluble cytotoxic T lymphocyte antigen-4, inhibiting immunocyte differentiation with recombinant interleukin 10, and improving immunosuppressive activity with regulatory T cell modulation have the most immediate promise. Progress in the development of an animal model of autoimmune hepatitis and experiences in other immune-mediated diseases justify the evaluation of site-specific molecular and cellular interventions in this disease.

Update on the genetics and genomics of PBC

Despite recent progress, the pathogenic mechanisms governing PBC development, treatment response and outcome remain unknown. This deficiency is in large part due to the complex nature of PBC, wherein various environmental factors may be capable of prompting disease, but only in the context of underlying genetic susceptibility. Identification of genomic loci containing these heritable risk factors has been slowed by the rarity and late onset of PBC, which has made difficult the collection of sufficient numbers of patients and family members for meaningful genetic analyses. Advancements in our ability to catalog the genetic variation in large numbers of individuals at a genome-wide scale, coupled with unprecedented efforts to recruit PBC patients for genetic study, positions us to generate data that could fundamentally change our understanding of PBC and lead to clinical innovation. Indeed, the first genome-wide association study for PBC has been published, in which multiple genes involved with IL12 signaling, a pathway that is being targeted in treatment of other inflammatory conditions, were implicated in disease. However, this study was relatively small in the genome-wide milieu and a significantly expanded effort will be necessary to truly elucidate the genetic architecture of PBC. Moving ahead, cooperation between the groups collecting biospecimens and generating genome-wide data from large numbers of patients with PBC will be essential, not only to increase power for fine mapping and future studies of rare variants and epistasis; but to streamline efforts to perform functional validation of novel discoveries. Here we provide a brief update of the current state of genetics in PBC to form a basis for understanding the considerable progress that is likely to be made in the coming years.

Advances in the diagnosis, pathogenesis, and management of autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterized by chronic inflammation of the liver, interface hepatitis (based on histologic examination), hypergammaglobulinemia, and production of autoantibodies. Many clinical and basic science studies have provided important insights into the pathogenesis and treatment of AIH. Transgenic mice that express human antigens and develop autoantibodies, liver-infiltrating CD4(+) T cells, liver inflammation, and fibrosis have been developed as models of AIH. AIH has been associated with autoantibodies against members of the cytochrome P450 superfamily of enzymes, transfer RNA selenocysteine synthase, formiminotransferase cyclodeaminase, and the uridine diphosphate glucuronosyltransferases, whereas alleles such as DRB1*0301 and DRB1*0401 are genetic risk factors in white North American and northern European populations. Deficiencies in the number and function of CD4(+)CD25(+) (regulatory) T cells disrupt immune homeostasis and might be corrected as a therapeutic strategy. Treatment can be improved by continuing corticosteroid therapy until normal liver test results and normal liver tissue are within normal limits, instituting ancillary therapies to prevent drug-related side effects, identifying problematic patients early, and providing long-term maintenance therapy after patients experience a first relapse. Calcineurin inhibitors and mycophenolate mofetil are potential salvage therapies, and reagents such as recombinant interleukin-10, abatacept, and CD3-specific antibodies are feasible as therapeutics. Liver transplantation is an effective salvage therapy, even in the elderly, and AIH must be considered in all patients with graft dysfunction after liver transplantation. Identification of the key defects in immune homeostasis and antigen targets will direct new therapies.

Vitamin D receptor gene polymorphisms and hepatocellular carcinoma in alcoholic cirrhosis

AIM: To assess the relationship between vitamin D receptor (VDR) gene polymorphisms and the presence of hepatocellular carcinoma (HCC).

METHODS: Two-hundred forty patients who underwent liver transplantation were studied. The etiologies of liver disease were hepatitis C (100 patients), hepatitis B (37) and alcoholic liver disease (103). A group of 236 healthy subjects served as controls. HCC in the explanted liver was detected in 80 patients. The following single nucleotide gene polymorphisms of the VDR were investigated by polymerase chain reaction and restriction fragment length polymorphism: FokI C>T (F/f), BsmI A>G (B/b), ApaI T>G (A/a) and TaqI T>C (T/t) (BAT).

RESULTS: The frequencies of genotypes in patients without and with HCC were for FokI F/F = 69, F/f = 73, f/f = 18 and F/F = 36, F/f = 36, f/f = 8; BsmI b/b = 45, B/b = 87, B/B = 28 and b/b = 33, B/b = 35, B/B = 12; for ApaI A/A = 53, A/a = 85, a/a = 22 and A/A = 27, A/a = 38, a/a = 15; for TaqI T/T = 44, T/t = 88, t/t = 28 and T/T = 32, T/t = 38, t/t = 10. Carriage of the b/b genotype of BsmI and the T/T genotype of TaqI was significantly associated with HCC (45/160 vs 33/80, P < 0.05 and 44/160 vs 32/80, P < 0.05, respectively). The absence of the A-T-C protective allele of BAT was significantly associated with the presence of HCC (46/80 vs 68/160, P < 0.05). A strong association was observed between carriage of the BAT A-T-C and G-T-T haplotypes and HCC only in alcoholic liver disease (7/46 vs 12/36 vs 11/21, P < 0.002, respectively).

CONCLUSION: VDR genetic polymorphisms are significantly associated with the occurrence of HCC in patients with liver cirrhosis. This relationship is more specific for patients with an alcoholic etiology.

The new therapeutic frontier--nuclear receptors and the liver

A joint EASL/AASLD Monothematic Conference on 'Nuclear Receptors and Liver Disease' was held from February 27th to March 1st, 2009, in Vienna, Austria, to discuss the latest advances at the forefront of basic and clinical nuclear receptor research and its potential implications for liver diseases. This article reports the highlights of the conference and summarizes the main conclusions emphasizing the relevance for clinical and experimental hepatology. The confluence of nuclear receptors as central transcriptional regulators, acting as sensors and adaptors to many of the small molecules present in the intracellular milieu of all the cells of the liver, provides a current framework to address a broader physiological understanding of the liver. The next stage will be the design and testing of safe and effective therapeutics.

Genomic variants associated with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune hepatobiliary disease characterized by immune-mediated injury of small and medium-sized bile ducts, eventually leading to liver cirrhosis. Several studies have addressed PBC immunopathology, and the data support an immune activation leading to autoantibodies and autoreactive T cells acting against the lipoylated 2-oxoacid dehydrogenase complexes. The causes of the disease remain unknown, but environmental factors and genetic susceptibility both contribute to its onset. Over the past two decades several association studies have addressed the role of genetic polymorphisms in PBC pathogenesis and have reported multiple associations. However, only a few studies had sufficient statistical power, and in most cases results were not independently validated. A genome-wide association study has recently been reported, but this too awaits independent confirmation. The aim of this present work is to critically review the numerous studies dedicated to revealing genetic associations in PBC, and to predict the potential for future studies based on these data.

Current understanding of osteoporosis associated with liver disease

Osteoporosis is a common complication of many types of liver disease. Research into the pathogenesis of osteoporosis has revealed that the mechanisms of bone loss differ between different types of liver disease. This Review summarizes our current understanding of osteoporosis associated with liver disease and the new advances that have been made in this field. The different mechanisms by which cholestatic and parenchymal liver disease can lead to reduced bone mass, the prevalence of osteopenia and osteoporosis in patients with early and advanced liver disease, and the influence of osteoporotic fractures on patient survival are discussed along with the advances in our understanding of the molecular pathways associated with bone loss. The role of the CSF1-RANKL system and that of the liver molecule, oncofetal fibronectin, a protein that has traditionally been viewed as an extracellular matrix protein are also discussed. The potential impact that these advances may have for the treatment of osteoporosis associated with liver disease is also reviewed.

Vitamin D receptor polymorphisms are associated with increased susceptibility to primary biliary cirrhosis in Japanese and Italian populations

BACKGROUND/AIMS

Vitamin D receptor (VDR) agonists have recently been identified as potent immunomodulators capable of inhibiting Th1-mediated immune response, leading us to consider the hypothesis that functional VDR polymorphisms might contribute to enhanced risk for developing primary biliary cirrhosis (PBC), a Th1-mediated autoimmune disease. In the current study, we aimed at elucidating the genetic association of VDR polymorphisms with susceptibility to PBC in Japanese and Italian populations.

METHODS

We enrolled 334 PBC patients (195 Japanese and 139 Italians), as well as 334 age- and sex-matched controls (179 Japanese and 156 Italians). VDR genotyping was performed by PCR-RFLP, using BsmI, ApaI and TaqI endonucleases.

RESULTS

The genotype BB of BsmI polymorphism was significantly associated with PBC (OR = 1.80 [95% CI; 1.19-2.73], p = 0.005). The association of the genotype BB was observed in Japanese (OR = 13.77, p = 0.001), and Italians (OR = 1.83, p = 0.019), respectively, although not significant in Italians after Bonferroni correction. The frequency of the B allele at the BsmI polymorphism was significantly higher in PBC patients (OR = 1.27 [95% CI; 1.02-1.59], p = 0.040).

CONCLUSIONS

The genotype 'BB' as well as 'B' allele at BsmI polymorphism of the VDR gene contribute to the risk of PBC development.

Bile salts control the antimicrobial peptide cathelicidin through nuclear receptors in the human biliary epithelium

BACKGROUNDS & AIMS

Under normal conditions, the biliary tract is a microbial-free environment. The absence of microorganisms has been attributed to various defense mechanisms that include the physicochemical and signaling actions of bile salts. Here, we hypothesized that bile salts may stimulate the expression of a major antimicrobial peptide, cathelicidin, through nuclear receptors in the biliary epithelium.

METHODS

The expression of cathelicidin was analyzed in human liver samples by immunostaining and reverse-transcription quantitative polymerase chain reaction. The regulation of cathelicidin expression by the endogenous bile salt, chenodeoxycholic acid, and by the therapeutic bile salt, ursodeoxycholic acid (UDCA), was assessed in human biliary epithelial cells in which endogenous nuclear receptor expression was blunted by siRNA or dominant-negative strategies.

RESULTS

In the human liver, biliary epithelial cells show intense immunoreactivity for cathelicidin and for the vitamin D receptor. In cultured biliary epithelial cells, chenodeoxycholic acid and UDCA induce cathelicidin expression through 2 different nuclear receptors: the farnesoid X receptor and the vitamin D receptor, respectively. Importantly, vitamin D further increases the induction of cathelicidin expression by both bile salts. In a prototypical inflammatory biliary disease (ie, primary biliary cirrhosis), we document that hepatic expressions of the vitamin D receptor and of cathelicidin significantly increased with UDCA therapy.

CONCLUSIONS

Our results indicate that bile salts may contribute to biliary tract sterility by controlling epithelial cell innate immunity. They further suggest that in inflammatory biliary diseases, which involve bacterial factors, a strategy systematically combining UDCA with vitamin D would increase therapeutic efficacy.

Influence of genes, sex, age and environment on the onset of autoimmune hepatitis

The pathogenesis of autoimmune hepatitis (AIH) is complex. However, it is believed that a susceptible individual, owing to his genetic background, sex and age, can develop the disease following exposure to an environmental trigger. Autoimmune hepatitis does not follow a Mendelian pattern of inheritance; hence no single causative genetic locus has been identified. However, several genes, inside and outside the HLA locus, have been linked to an increased susceptibility to AIH. Epidemiological evidence also suggests that the sex and age of the patient plays a role in AIH pathogenesis as the disease onset occurs mainly in the two first decades of life and a higher disease incidence is observed in females. No environmental trigger has been identified, but several have been proposed, mainly viruses and xenobiotics. This article aims at reviewing the current knowledge on susceptibility factors leading to AIH and putative triggers, emphasizing fundamental mechanisms responsible for the break of liver immunological tolerance.

Pathogenic role of environmental toxins in immune-mediated liver diseases

Immune-mediated liver diseases contribute significantly to morbidity and mortality due to liver failure and the need for liver transplantation. The pathogenesis of the immune-mediated chronic liver diseases, primary sclerosing cholangitis, autoimmune hepatitis, and primary biliary cirrhosis, is poorly understood. Genetic susceptibility factors may play a role, but increasing attention is being given to the association between environmental factors and these diseases. The existence of such a relationship is supported by epidemiologic surveys, animal models, and geographic clustering analyses. Unearthing the cause of this association may provide insight into the pathogenesis of immune-mediated chronic liver diseases and autoimmunity.

Duplication of MER115 on chromosome 4 in patients with primary biliary cirrhosis

BACKGROUND

Primary biliary cirrhosis (PBC) is a complex disease with genetic and environmental influences. The disease is more prevalent in families with PBC and candidate gene case-control studies have linked PBC with DRB1(*)08 human leucocyte antigen class II alleles.

AIMS

The goal of this study was to characterize a MER115 intergenic region on chromosome 4 as a putative genetic variant associated with PBC.

METHODS/RESULTS

This region was incidentally identified during investigations to discover candidate microbial agents using representational difference analysis (RDA) with liver samples from patients with PBC and primary sclerosing cholangitis (PSC). blast search analysis of all the RDA products from the PBC liver revealed genomic sequences, whereas Escherichia coli, mycoplasma and hepatitis B virus DNA were found in the PSC liver. We identified one of the PBC RDA products as an ancestral repeat, referred to as MER115. Southern blot analysis with the PBC product uncovered a restriction fragment length polymorphism in PBC patients' liver. Southern blot hybridization signal showed increased signal intensity in PBC vs. control patients' DNA (P<0.005) and slot blot hybridization studies confirmed a copy number variation of the MER115 in hepatic DNA of PBC vs. control patients (P=0.02).

CONCLUSIONS

Further comparative genetic studies will be required to determine the extent of genomic duplication associated with MER115 and provide data on the possible copy number variants of genes close to this intergenic region in patients with PBC.

Mechanism of vitamin D receptor inhibition of cholesterol 7alpha-hydroxylase gene transcription in human hepatocytes

Lithocholic acid (LCA) is a potent endogenous vitamin D receptor (VDR) ligand. In cholestasis, LCA levels increase in the liver and intestine. The objective of this study is to test the hypothesis that VDR plays a role in inhibiting cholesterol 7alpha-hydroxylase (CYP7A1) gene expression and bile acid synthesis in human hepatocytes. Immunoblot analysis has detected VDR proteins in the nucleus of the human hepatoma cell line HepG2 and human primary hepatocytes. 1alpha, 25-Dihydroxy-vitamin D(3) or LCA acetate-activated VDR inhibited CYP7A1 mRNA expression and bile acid synthesis, whereas small interfering RNA to VDR completely abrogated VDR inhibition of CYP7A1 mRNA expression in HepG2 cells. Electrophoretic mobility shift assay and mutagenesis analyses have identified the negative VDR response elements that bind VDR/retinoid X receptor alpha in the human CYP7A1 promoter. Mammalian two-hybrid, coimmunoprecipitation, glutathione S-transferase pull-down, and chromatin immunoprecipitation assays show that ligand-activated VDR specifically interacts with hepatocyte nuclear factor 4alpha (HNF4alpha) to block HNF4alpha interaction with coactivators or to compete with HNF4alpha for coactivators or to compete for binding to CYP7A1 chromatin, which results in the inhibition of CYP7A1 gene transcription. This study shows that VDR is expressed in human hepatocytes and may play a critical role in the inhibition of bile acid synthesis, thus protecting liver cells during cholestasis.

Relationship between vitamin D receptor gene polymorphisms and alcoholic liver disease

AIM: To investigate the relationship between vitamin D receptor gene polymorphism and susceptibility to alcoholic liver disease (ALD).

METHODS: The Semi-nested PCR-restriction fragment length polymorphism (semi-nested PCR-RFLP) technology was used to analyze 50 ALD patients and 72 healthy controls. Comparison was made between the two groups in genotype frequencies, allele frequencies, and finally a correlation analysis was performed.

RESULTS: We found three genotypes in the case group and control group, that is, BB, Bb and bb. The bb genotype frequency and b allele frequency were significantly higher in case group than in control group (χ² = 7.16, P = 0.028, OR = 2.698, 95% CI: 1.167-6.235; χ² = 11.64, P = 0.001, OR = 3.071, 95% CI: 1.583-3.958). Multi-factor unconditional Logistic regression analysis showed cases carrying bb genotype were more likely to develop into the ALD, indicating that bb genotype might be a genetic risk factor in ALD (OR = 2.272, OR 95% CI: 0.971-5.318).

CONCLUSION: The vitamin D receptor gene BsmⅠ site polymorphism is strongly associated with the ALD, and bb genotype may be a risk factor for development ALD.

Association of vitamin D receptor gene polymorphisms in Iranian patients with inflammatory bowel disease

BACKGROUND AND AIMS

The vitamin D receptor (VDR) gene maps to a region on chromosome 12 shown to be linked to inflammatory bowel disease (IBD). Many studies have recognized the relation of VDR gene polymorphisms with inflammatory and autoimmune disorders. Determining the frequency of these polymorphisms and their possible relation with IBD can improve understandings about the genetic background of these diseases. The objective of this study was to assess the association of VDR gene polymorphisms (Apa I, Taq I, Bsm I, Fok I) with IBD in Iran.

METHODS

In this case control designed study 150 patients with ulcerative colitis, 80 patients with Crohn's disease and 150 Age and Sex matched healthy controls from Iranian origin were enrolled. These patients were referred to a tertiary center during a two-year period (2004-2006). Assessment of VDR gene polymorphisms was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The genotype-phenotype association for these polymorphisms was analyzed.

RESULTS

Only the frequency of the Fok I polymorphism was significantly higher in ulcerative colitis and Crohn's groups. The frequency of the polymorphic allele f was higher in ulcerative colitis and Crohn's patients comparing with controls (P = 0.011 and P < 0.001, respectively). The f/f genotype was also significantly more frequent (P < 0.001), while the F/F genotype was less presented in Crohn's patients compared to controls (P < 0.001). No genotype-phenotype association was observed with any mutations.

CONCLUSIONS

This study suggests a probable association of the Fok I polymorphism in VDR receptor gene and Crohn's susceptibility in Iranian population.

Osteoporosis in primary biliary cirrhosis: pathogenesis and treatment

Osteoporosis, characterized by loss of bone strength leading to fragility fractures, is a common event in patients who have primary biliary cirrhosis. Although its pathogenesis is not well known, it results mainly from low bone formation. There is no specific treatment, but bisphosphonates, especially alendronate, effectively increases bone mass and prevents bone loss. Despite these favorable effects on bone mass, no clear effects on decreasing the fracture rate are demonstrated, probably because of the low number of patients included in the trials. The potential usefulness of new agents requires further evaluation.

Genetic factors affecting the occurrence, clinical phenotype, and outcome of autoimmune hepatitis

Autoimmune hepatitis is a polygenic disorder of unknown cause in which the genetic risk factors that affect occurrence, clinical phenotype, severity, and outcome still are being clarified. The susceptibility alleles in white North American and northern European patients reside on the DRB1 gene, and they are DRB1*0301 and DRB1*0401. These alleles encode a 6 amino acid sequence at positions 67-72 in the DRbeta polypeptide chain of the class II molecules of the major histocompatibility complex. This sequence is associated with susceptibility, and lysine at position DRbeta71 is the key determinant. Molecular mimicry between foreign and self-antigens may explain the loss of self-tolerance and the occurrence of concurrent immune diseases in anatomically distant organs. Disease severity is associated with the number of alleles encoding lysine at DRbeta71 (gene dose) and the number of polymorphisms, including those of the tumor necrosis factor-alpha gene, cytotoxic T lymphocyte antigen-4 gene, and tumor necrosis factor-receptor superfamily gene, that can modify the immune response. Individuals in different geographic regions may have different susceptibility alleles that reflect indigenous triggering antigens, and these may provide clues to the etiologic agent. Knowledge of the genetic predispositions for autoimmune hepatitis may elucidate pathogenic mechanisms, identify etiologic agents, characterize susceptible populations, foresee outcomes, and target new therapies. These lessons may be applicable to autoimmune disease in general.

Vitamin D status in gastrointestinal and liver disease

PURPOSE OF REVIEW

The purpose of this review is to report on the vitamin D status and its relationship with bone health in individuals with gastrointestinal and liver disorders. In addition, recommendations regarding replacement and maintenance of optimal vitamin D stores, as well as the state of knowledge regarding its effect on the disease through its actions on the immune system, will be reviewed.

RECENT FINDINGS

The scientific community has revised upward the serum levels of vitamin D considered optimal, and doses of vitamin D much larger than those currently recommended may be needed to maintain these levels, especially in individuals with gastrointestinal and liver disorders. The relationship between vitamin D and bone health in this population is controversial. The role of vitamin D in the regulation of the immune system continues to be elucidated.

SUMMARY

Hypovitaminosis D is prevalent among individuals with gastrointestinal and liver disease. Although replacement and supplementation guidelines have not been well defined, practitioners should aim for a serum 25-hydroxyvitamin D level of at least 32 ng/ml. The contribution of vitamin D to the bone health of these individuals and its role in altering disease course through its actions on the immune system remain to be elucidated.