Influence of the vitamin D receptor gene polymorphism on bone loss in men after liver transplantation

Do Vitamin D receptor gene polymorphisms affect bone mass density in men?: A meta-analysis of observational studies

The signs of aging in humans can often be detected through a decrease in bone mass density (BMD). The decrease in BMD as a risk of osteoporosis is often only seen in women, but not in men, even though men also have a risk of osteoporosis which can affect their well-being. We conducted study searches through databases such as PubMed, EBSCO, ProQuest, Willey Online, Science Direct, and SAGE. We performed analysis on four types of Vitamin D receptor polymorphisms: BsmI, ApaI, FokI, and TaqI from 14 potential studies involving men. We found that several genetic analysis models of BsmI and FokI significantly affected BMD in men: BB vs bb in whole body BMD (SMD = 0.43, 95% CI = [0.12-0.75], p = 0.0008, BB vs Bb in whole body BMD (SMD = -1.38, 95% CI = [-1.87 to 0.88], p < 0.00001), and FF+Ff vs ff spine BMD (SMD = 0.59, 95% CI = 0.13-1.05], p = 0.001), even after adjusting for comorbidities as confounding variables. The present meta-analysis showed that BsmI and FokI polymorphisms of the VDR gene were correlated with decreased BMD in men which may contribute to the aging process and well-being.

Prospective study of bone mineral density and metabolism in patients with chronic hepatitis C during pegylated interferon alpha and ribavirin therapy

The importance of osteoporosis as a complication of end-stage liver disease is well known. However, significant osteopenia may occur in earlier stages of chronic hepatitis C (CHC). Furthermore, antiviral therapy may influence bone metabolism. Thirty patients with CHC genotype 1 infection and without established cirrhosis were treated with peginterferon-alfa and ribavirin. Dual-energy x-ray absorptiometry was performed at baseline, after 48 weeks of therapy, and by the end of a 24-week follow-up period. Bone mineral density (BMD), T-scores, and Z-scores were assessed. Serum C-terminal propeptide of type I collagen (CICP) and osteocalcin levels were measured. Thirteen patients had osteopenia (43%) and osteoporosis was present in four patients (13%). Antiviral therapy led to significant on-treatment increases of lumbar spine and hip BMD (P < or = 0.05) as well as T-scores (P < or = 0.05) and Z-scores (P < or = 0.01) irrespective of subsequent treatment response. Further analyses showed that in patients with sustained virological response (n = 19) most parameters remained highly above baseline values by the end of the 24-week follow-up period, while patients with virological relapse (n = 11) had decreases of BMD, T-scores and Z-scores thereafter that did not differ from baseline. Serum CICP and osteocalcin levels decreased during therapy. Osteocalcin levels remained below baseline in sustained responder, but showed an increase in relapsers by the end of the 24-week follow-up (P < or = 0.05). Osteopenia is detectable in a substantial proportion of CHC patients without established cirrhosis. Antiviral therapy leads to an on-treatment increase of BMD, which may last in those patients who achieve a sustained virological response.

Bone mineral density before and after OLT: long-term follow-up and predictive factors

Fracturing after liver transplantation (OLT) occurs due to the combination of preexisting low bone mineral density (BMD) and early posttransplant bone loss, the risk factors for which are poorly defined. The prevalence and predictive factors for hepatic osteopenia and osteoporosis, posttransplant bone loss, and subsequent bone gain were studied by the long-term posttransplant follow-up of 360 consecutive adult patients with end-stage primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Only 20% of patients with advanced PBC or PSC have normal bone mass. Risk factors for low spinal BMD are low body mass index, older age, postmenopausal status, muscle wasting, high alkaline phosphatase and low serum albumin. A high rate of spinal bone loss occurred in the first 4 posttransplant months (annual rate of 16%) especially in those with younger age, PSC, higher pretransplant bone density, no inflammatory bowel disease, shorter duration of liver disease, current smoking, and ongoing cholestasis at 4 months. Factors favoring spinal bone gain from 4 to 24 months after transplantation were lower baseline and/or 4-month bone density, premenopausal status, lower cumulative glucocorticoids, no ongoing cholestasis, and higher levels of vitamin D and parathyroid hormone. Bone mass therefore improves most in patients with lowest pretransplant BMD who undergo successful transplantation with normal hepatic function and improved gonadal and nutritional status. Patients transplanted most recently have improved bone mass before OLT, and although bone loss still occurs early after OLT, these patients also have a greater recovery in BMD over the years following OLT.

Evaluation and management of osteoporosis in liver disease

This article discusses the clinical importance of hepatic osteopenia, the identification of risk factors for the individual patient, and the selection of patients, timing, and methods for diagnostic screening. General supportive measures to maximize bone health should be used in all patients at risk. In addition, for the patient with established osteoporosis, specific therapeutic measures may be justified, despite the lack of adequate randomized trials of these agents in patients with hepatic osteopenia.

Treatment with intermittent calcitriol and calcium reduces bone loss after renal transplantation

BACKGROUND

Bone loss occurs during the first 6 months after renal transplantation (RT), and corticosteroid therapy plays an important role. Although calcium plus vitamin D administration prevents corticosteroid-induced osteoporosis, its use in RT recipients is limited by the risk of hypercalcemia.

METHODS

This double-blind, randomized, and controlled prospective intervention trial examined the effect of intermittent calcitriol (0.5 microg/48 h) during the first 3 months after RT, plus oral calcium supplementation (0.5 g/day) during 1 year with calcium supplementation alone. The primary outcome measure was the change in bone mineral density (BMD) at 3 and 12 months after RT; we also explored whether the effect of calcitriol on BMD was different among vitamin D receptor (VDR) genotypes (BsmI). Forty-five recipients were randomized to calcitriol therapy (CT) and 41 were randomized to placebo (PL).

RESULTS

Both groups had a similar degree of pre-existing hyperparathyroidism (197 +/- 229 vs. 191 +/- 183 pg/mL), but a more pronounced decrease of parathyroid hormone (PTH) levels after RT was observed in CT patients (at 3 months: 61.4 +/- 42.2 vs. 85.7 +/- 53.1 pg/mL, P= 0.02; at 12 months: 67.3 +/- 33.7 vs. 82.6 +/- 37 pg/mL; P= 0.08). CT patients preserved their BMD at the total hip significantly better than those on PL (3 months: 0.04 +/- 3.3 vs. -1.93 +/- 3.2%, P= 0.01; 12 months: 0.32 +/- 4.8 vs. -2.17 +/- 4.4%, P= 0.03); significant differences were noted at the intertrochanter, trochanter, and Ward's triangle. Differences did not reach significance at the femoral neck. Two CT patients (4.4%) and 4 PL patients (9.8%) developed a hypercalcemic episode during the first 3 months after RT. The effect of CT on BMD at 3 months was more prominent in recipients with the at-risk allele of the VDR gene (P= 0.03).

CONCLUSION

Therapy with low-dose calcium supplements during 1 year, plus intermittent calcitriol for 3 months after RT, is safe, decreases PTH levels more rapidly, and prevents bone loss at the proximal femur; a more pronounced effect is seen in recipients with at least one at-risk allele of the VDR genotype.

Osseous complications of pediatric transplantation

Adult stature and peak bone mass are achieved through childhood growth and development. Multiple factors impair this process in children undergoing solid organ transplantation, including chronic illness, pretransplant osteodystrophy, use of medications with negative impact on bone, and post-transplant renal dysfunction. While growth delay and short stature remain common, the most severe forms of transplant-related bone disease, fracture and avascular necrosis, appear to have become less common in the pediatric age group. Osteopenia is very prevalent in adult transplant recipients and probably also in pediatrics, but its occurrence and sequelae are difficult to study in these groups due to methodological shortfalls of planar densitometry related to short stature and altered patterns of growth and development. Although the effect on lifetime peak bone mass is not clear, data from adult populations suggest an elevated long-term risk of bone disease in children receiving transplants. Optimal management of pretransplantation osteodystrophy, attention to post-transplant renal insufficiency among both renal and non-renal transplant patients, reduction of steroid dose in select patients, and supplementation with calcium plus vitamin D during expected periods of maximal bone loss may improve bone health. Careful research is required to determine the role of bisphosphonate therapy in pediatric transplantation.

Allele-frequency determination of BsmI and FokI polymorphisms of the VDR gene by quantitative real-time PCR (QRT-PCR) in pooled genomic DNA samples

The vdr gene is a candidate for osteoporosis susceptibility, with conflicting results in association studies. We have designed and optimized an individual allele-specific and DNA pooling PCR-based methodology to quantitate BsmI and FokI polymorphisms of the vdr gene and studied single-nucleotide polymorphisms (SNPs) from pooled DNA samples. The allele frequency in DNA pooling experiments has been analyzed by kinetic PCR: quantitative real-time PCR (QRT-PCR). A Spanish cohort of 225 healthy postmenopausal women was studied. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DEXA) and quantitative ultrasound calcaneous densitometry. Allele-specific PCR amplification of BsmI and FokI genes showed full concordance with the PCR-RFLP approach. The prevalence of the three BsmI VDR genotypes was 19.1, 44.9 and 36.0% for BB, Bb and bb, respectively. In the case of the FokI locus, the prevalence of genotypes was 40.4, 48.0 and 11.6% for FF, Ff and ff, respectively. No positive correlation was found between polymorphism and BMD. The DNA pooling procedure was validated. No differences were found in allele frequencies and T-score data obtained using the high throughput DNA pooling approach, as compared to known individual frequencies. In our hands, this is a very useful approach to study quantitative (thus polygenic) traits like osteoporosis susceptibility.

Metabolic bone disease in patients with liver disease

The coexistence of liver disease and osteopenic bone disease has been recognized for many years and is now the subject of increasing attention. Osteoporosis has been characterized well in patients with cholestatic liver disease, but new research suggests that osteopenia and osteoporosis may also be prevalent in patients with other chronic liver diseases. Although the precise mechanism of bone loss remains unclear, advances in treatment and prevention are bringing heightened awareness to this common problem.

Vitamin D receptor gene polymorphism associates with graft-versus-host disease and survival in HLA-matched sibling allogeneic bone marrow transplantation

We investigated the role of polymorphism of the vitamin D receptor (VDR) gene in HLA-matched sibling BMT for polymorphisms previously associated with human disease pathology. In intron 8 of the VDR gene, the B and A alleles of the BsmI and ApaI RFLPs were found to associate with reduced aGVHD when present in the patient's genotype. Logistic regression analysis demonstrated that patient VDR genotype, along with previously identified IL-10(-1064) and IFN-gamma genotype to be risk factors for severe acute GVHD. The A allele also associates with increased likelihood of death when present in the donor genotype (AA vs Aa or aa, hazard ratio 2.03, P = 0.0232). In patients who received increased prophylaxis with multi-agent therapy, patients whose graft was from a donor with an AA genotype had a substantially worse survival than patients whose graft was from a donor with a non-AA genotype (hazard ratio 12.93, P < 0.0001). Analysis of VDR genotype in prospective BMT recipients could indicate patients at risk of severe aGVHD. Analysis of VDR genotype in prospective BMT donors may identify individuals who have greater transplant-related mortality, and also allow appropriately restricted use of increased immunosuppressive prophylaxis.

Risk factors for development of de novo neoplasia after liver transplantation

Liver transplant recipients are at greater risk for de novo neoplasia, especially lymphoma and nonmelanoma skin cancer; however, risk factors for this complication have not been well studied. Clinical and pathological records of 137 consecutive liver transplant recipients who had survived for at least 1 year were reviewed to register de novo neoplasia. Ten variables were analyzed for their association with the development of de novo malignancies by means of a log-rank test and stepwise selection in a multivariate analysis using the Cox proportional hazard model. Thirty de novo neoplasias appeared in 22 of 137 transplant recipients between 12 and 104 months after orthotopic liver transplantation (OLT; median follow-up, 69 months): 14 patients had 21 skin cancers, 6 patients had solid-organ cancer, and 3 patients developed a lymphoproliferative disease. Probabilities of de novo neoplasia were 13% at 5 years post-OLT and 26% at 8 years post-OLT. The only associated risk factor for any neoplasia was age. Age and hepatocarcinoma were independent risk factors associated with skin cancer. That hepatocarcinoma in the explanted liver is an independent risk factor for skin cancer suggests there is individual susceptibility to both neoplasias.

Cholestatic syndromes

New insights into the regulation of hepatobiliary transport proteins have provided the basis for a better understanding of the pathogenesis of cholestatic liver diseases. Mutations of transporter genes can cause hereditary cholestatic syndromes, the study of which has shed much light on the basic mechanisms of bile secretion and cholestasis. Important new studies have been published about the pathogenesis, clinical features, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, and drug-induced cholestasis.

Nutritional and metabolic issues in cirrhosis and liver transplantation

In the last year some relevant papers on nutrition and metabolism in chronic liver disease and transplantation have been published. Studies investigating the reliability of predicting energy expenditure in cirrhosis, and some relevant contributions to the understanding of metabolic consequences of liver transplantation, deserve particular mention. These include the first direct evidence that liver transplantation corrects the insulin resistance present in cirrhosis, as well as studies on the role of genetic polymorphism of the vitamin D receptor gene in bone loss after transplantation. Other papers have dealt with body composition, polyunsaturated fatty acid and antioxidant status in cirrhosis. However, relevant contributions in the field of nutritional support in cirrhosis are surprisingly lacking.