Calcaneal ultrasound attenuation and vitamin-D-receptor genotypes in celiac disease

Osteoporosis and Celiac Disease: Updates and Hidden Pitfalls

Celiac disease (CD) is an autoimmune disorder caused by gluten ingestion in genetically predisposed individuals. In addition to the typical gastrointestinal symptoms (e.g., diarrhea, bloating, and chronic abdominal pain), CD may also present with a broad spectrum of manifestations, including low bone mineral density (BMD) and osteoporosis. The etiopathology of bone lesions in CD is multifactorial and other conditions, rather than mineral and vitamin D malabsorption, may affect skeletal health, especially those related to the endocrine system. Here, we describe CD-induced osteoporosis in an attempt to enlighten new and less-known aspects, such as the influence of the intestinal microbiome and sex-related differences on bone health. This review describes the role of CD in the development of skeletal alterations to provide physicians with an updated overview on this debated topic and to improve the management of osteoporosis in CD.

A meta-analysis suggests the association of reduced serum level of vitamin D and T-allele of Fok1 (rs2228570) polymorphism in the vitamin D receptor gene with celiac disease

Purpose

As an immune-modulator, vitamin D is known to regulate immune response and is implicated in disease pathogenesis. Celiac disease (CD) is a systemic autoimmune disease and susceptibility conferred by vitamin D metabolism is under investigation. Studies on the association of vitamin D metabolism and genetic polymorphisms are expected to explain CD pathogenesis. We performed a systematic review-based meta-analysis to investigate the 25(OH)D serum levels and susceptibility conferred by the genetic variants of VDR in CD.

Methods

Systematic review was conducted through a web-based literature search following stringent study inclusion-exclusion criteria. The Newcastle-Ottawa Scale and GRADE tools were used to assess the quality of evidence in studies and the study outcome. Cohen's κ value was estimated to access the reviewer's agreement. RevMan 5.4.1 was used to perform the meta-analyses. Weighted mean difference and Meta p-value was assessed for 25(OH)D serum levels. Meta-odds ratio and Z-test p-value were evaluated to estimate the allelic susceptibility of VDR variants.

Results

A total of 8 out of 12 studies were evaluated for "25(OH)D" serum level, while four studies were found eligible for SNPs (Bsm1, Apa1, Fok1, and Taq1) of VDR. Significantly higher levels [WMD = 5.49, p < 0.00001] of 25(OH)D were observed in healthy controls than in patients with CD. rs2228570-T (Fok1) [Meta-OR = 1.52, p = 0.02] was confirmed to be predisposing allele for CD.

Conclusion

Reduced serum level of 25(OH)D and association of Fok1 T-allele of VDR confirmed in this study plays a critical role in immunomodulation and maintaining barrier integrity, which is majorly implicated in CD.

The Effect of a Gluten-Free Diet on Vitamin D Metabolism in Celiac Disease: The State of the Art

Celiac disease is a chronic autoimmune disorder involving the small intestine, characterized by villous atrophy, crypt hyperplasia and an increase in intraepithelial lymphocytes. Due to both calcium malabsorption and immune activation, a high prevalence of bone mass derangement is evident in this condition, regardless of the presence of overt malabsorption. Alterations of mineral metabolism are also frequently described, and in this review, the modifications of serum levels of vitamin D are analyzed, according to the available literature on this topic. In untreated patients, secondary hyperparathyroidism is responsible for the hyperconversion of 25-vitamin D into 1,25-vitamin D making mandatory the determination of serum levels of both vitamin metabolites to avoid a wrong diagnosis of vitamin D deficit. A gluten-free diet allows for a normalization of bone and mineral metabolism, reverting these abnormalities and raising some doubts on the need for vitamin supplementation in all the patients. Data available do not support this wide indication, and a complete evaluation of bone and mineral metabolism should be performed to select patients who need this therapeutic approach.

Vitamin D status and vitamin D receptor genotypes in celiac disease: a meta-analysis

BACKGROUND

There have been various articles reporting relationship between Vitamin D (VitD) and celiac disease (CeD), but results remain controversial. This study aimed to conduct a meta-analysis to systematically review and quantify the relationship between VitD and CeD. Moreover, difference in Vitamin D Receptor (VDR) genotypes between CeD patients and controls was also analyzed.

METHODS

Articles published until July 20, 2019 in the PubMed, MEDLINE, and EMBASE databases were searched. According to the inclusion and exclusion criteria, relevant statistical data were collated and extracted, which were finally analyzed by STATA15.1.

RESULTS

27 articles and 28 sets of data were included. It showed that average 25(OH)D level in CeD patients was 8.36 nmol/L lower than controls (Weighted Mean Difference (WMD) = -8.36, 95% CI = [-14.63, -2.09] nmol/L). After gluten-free diet treatment, we found that average 25(OH)D level in treated patients was 15.6 nmol/L higher than untreated patients (WMD = 15.6, 95% CI = [5.96, 25.23] nmol/L). In addition, 25(OH)D level in treated patients was close to healthy controls (WMD = -2.82, 95% CI = [-6.45, 0.73] nmol/L). However, genetic polymorphism analysis showed that there is no difference in VDR genotypes between CeD and control.

CONCLUSIONS

CeD had decreased serum 25(OH)D levels, which returned to normal after treatment, suggesting that VitD may play a role in the development of CeD. The directionality of this association cannot be confirmed from cross-sectional studies. Demonstration of a causal role of VitD deficiency in CeD development in future studies could have important therapeutic implications.

Vitamin D

Interest in vitamin D and the VDR gene is increasing as putative roles in human health and evolutionary processes are explored. This review looks beyond the classic biochemistry that links vitamin D to calcium homeostasis; it explores how vitamin D interacts with light in a broader perspective than simple skin photosynthesis. It examines how the vitamin influences circadian rhythm, and how it may have helped drive the evolution of skin pigmentation. To this end, the nutrient–nutrient relationship with folate is also explored. The VDR gene is additionally examined as a factor in the evolutionary selection of skin depigmentation at higher latitudes to allow vitamin D synthesis. Evidence is given to show that VDR polymorphisms exhibit a latitudinal gradient in allele prevalence consistent with such a paradigm. Overall, the review examines new evo-devo ideas that link light-sensitive vitamins to human health/phenotype, both within and across the lifecycle.

Pathologic bone alterations in celiac disease: etiology, epidemiology, and treatment

Low bone mineral density (BMD), osteopenia, and osteoporosis are frequent complications of celiac disease (CD). The etiology of pathologic bone alterations in CD is multifactorial; however, two main mechanisms are involved: intestinal malabsorption and chronic inflammation. A strict gluten-free diet (GFD) is thought to be the only effective treatment for CD; but treating bone complications related to CD remains complex. The objective of this review is to elucidate the bones problems related to CD and to increase awareness of osteoporosis development, considered as a sign of atypical CD presentation. Currently, a question of whether GFD alone is an effective treatment to correct the bone alterations in patients with CD is under debate. This review presents factors contributing to pathologic bone derangement, recent research on the epidemiology of low BMD, osteoporosis, and fractures, and the treatment of bone problems in patients with CD. The roles of calcium and transport mechanisms are additionally presented.

Appropriate nutrient supplementation in celiac disease

Reduced levels of iron, folate, vitamin B12, vitamin D, zinc, and magnesium are common in untreated celiac disease (CD) patients probably due to loss of brush border proteins and enzymes needed for the absorption of these nutrients. In the majority of patients, removal of gluten from the diet leads to histological recovery and normalization of iron, vitamin, and mineral levels. Iron deficiency anemia is the most common extra-intestinal sign of CD and usually resolves with adherence to a gluten-free diet. However, deficiencies of both folate and vitamin B12 may persist in some patients on a gluten-free diet, thus requiring vitamin supplementation to improve subjective health status. Similarly, exclusion of gluten from the diet does not always normalize bone mineral density; in these cases, supplementation of vitamin D and calcium is recommended. Resolution of mucosal inflammation may not be sufficient to abrogate magnesium deficiency. Since gluten-free cereal products have a lower magnesium content as compared with gluten-containing counterparts, a magnesium-enriched diet should be encouraged in CD patients. In this article we discuss the frequency and clinical relevance of nutrient deficiency in CD and whether and when nutrient supplementation is needed.

Bone mineral density directly correlates with duodenal Marsh stage in newly diagnosed adult celiac patients

OBJECTIVES

To estimate the prevalence of low bone mineral density (BMD) in a prospective series of adult celiac patients and to identify nutritional and metabolic factors associated with osteoporosis and osteopenia.

METHODS

Patients over 18 years of age who were consecutively and newly diagnosed with celiac disease (CD) were recruited. A bone density scan with dual-energy X-ray absorptiometry was carried out on the left hip and lumbar spine; nutritional parameters were analyzed and a hormone study conducted in order to exclude secondary low BMD.

RESULTS

40 patients (36 females/4 males) between the ages of 18 and 68 (mean 44.25 years) were recruited. Overall, at the moment of diagnosis 45% of patients exhibited low BMD at both demarcations. Risk of hip fracture was generally low, but ascended to mild in patients with villous atrophy (p = 0.011). Differences in major fracture risk were also observed depending on Marsh stage (p = 0.015). Significant differences were observed in nutritional status between patients with and without duodenal villous atrophy, with body mass index and blood levels of prealbumin, iron, vitamin D and folic acid significantly lower in Marsh III stage patients. No differences were found in blood hormone levels between Marsh stages or BMDs. The degree of bone mass loss in the lumbar spine directly correlated to Marsh stage. In the hip, a parallel association between BMD and Marsh stage was also observed, but did not reach statistical significance.

CONCLUSION

Duodenal villous atrophy, through malabsorption, was the main determinant factor for low BMD in adult-onset CD patients.

Heterogeneity of vitamin D receptor gene association with celiac disease and type 1 diabetes mellitus

OBJECTIVE

Vitamin D has been shown to exert multiple immunomodulatory effects and is known to suppress T-cell activation by binding to the vitamin D receptor (VDR). To determine whether VDR gene polymorphisms are related to the susceptibility to celiac disease, we investigated its implication as a candidate gene in the Basque population. Because celiac disease and type 1 diabetes share common susceptibility loci, we also analyzed families with type 1 diabetes mellitus.

METHODS

A total of 37 families with celiac disease and 64 type 1 diabetic families of Basque origin with at least one affected offspring were genotyped for four VDR restriction-site polymorphisms (Fok I, Bsm I, Apa I and Taq I). The AFBAC approach was used to test for association.

RESULTS

Comparison of VDR genotypes of the patients with those of 88 healthy individuals identified "ff" as a risk genotype for celiac disease [p = 0.01; OR = 3.45 (1.12-10.79)]. On the other hand, a significantly higher frequency of haplotype "fBAt" was observed in the type 1 diabetic group [p(c) = 0.02; OR = 4.4 (1.5-15.3)].

CONCLUSION

Our findings suggest that polymorphisms within the vitamin D receptor gene are markers of susceptibility to or protection from autoimmune diseases, although, at least in the Basque population, association of VDR variants with celiac disease and type 1 diabetes seems to be heterogeneous.

Bone in celiac disease

Chronic inflammation and malabsorption in celiac disease (CD) can cause bone metabolism alterations and bone mineral loss in children and adults. Bone status before and after gluten-free diet, epidemiology of fractures, and possible treatment options for CD-related osteoporosis are presented. Controversial aspects of this complication of CD are discussed. The relationship between bone derangements and celiac disease (CD) was recognized almost 50 years ago, but many questions are still open. We are now aware that osteoporosis is a relatively frequent atypical presentation of CD, especially in adults, and that undiagnosed CD can be the cause of osteoporosis and related fractures. Chronic inflammatory intestinal diseases, including CD, can affect bone and mineral metabolism because of alterations in both systemic and local regulatory factors. The pathogenetic processes are still controversial, but two main mechanisms seem to be involved: intestinal malabsorption and the presence of chronic inflammation. This review analyzes the published data on bone involvement in children, adolescents, and adults either before or after a gluten-free diet. Special attention is paid to the epidemiology of fractures in celiac patients, considering that fractures are a major complication of osteoporosis and an important problem in the management of a chronic disease like CD. The usefulness of screening osteoporotic patients systematically for CD is still an open question, but some rules can be given. Finally, the current treatment options for children and adults are discussed. Recommendations for future clinical research are proposed.

Vitamin D receptor gene polymorphisms are not associated with alopecia areata

BACKGROUND

It has been demonstrated that the vitamin D receptor (VDR) is strongly expressed in key structures of hair follicles, and a lack of VDR leads to alopecia. We investigated whether there was any association between VDR gene polymorphisms (BsmI, ApaI, and TaqI) and alopecia areata (AA).

METHODS

Thirty-two patients with AA and 27 healthy control subjects were genotyped using polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

In the patient group, the B and b allele frequencies were 53.1% and 46.9%, A and a allele frequencies were 70.3% and 29.7%, and T and t allele frequencies were 62.5% and 37.5%, respectively. In the control group, the corresponding values were 51.9% and 48.1%, 63.0% and 37.0%, and 77.8% and 22.2%, respectively. In the patient group, the BB, Bb, and bb genotype frequencies were 25.0%, 56.2%, and 18.8%, AA, Aa, and aa genotype frequencies were 43.8%, 53.1%, and 3.1%, and TT, Tt, and tt genotype frequencies were 37.5%, 50.0%, and 12.5%, respectively. In the control group, the corresponding values were 11.1%, 81.5%, and 7.4%, 29.6%, 66.7%, and 3.7%, and 63.0%, 29.6%, and 7.4%, respectively. None of the allele or genotype frequencies showed statistically significant differences between the patient and control groups.

CONCLUSION

These findings suggest that there is no relationship between VDR gene polymorphisms and AA.

Determinants of fracture risk in osteoporosis

Osteoporosis is a major public health issue, with fragility fractures of the hip, vertebrae, and distal radius considered the most important consequences. These lead to increased morbidity, mortality, hospital care, and dependency. The risk factors for the development of fragility fractures are numerous and involve genetic and environmental influences, as well as an interaction between the two. In this review, the recent literature examining genetic factors, possible candidate genes, the evolving area of intrauterine fetal programming, and anthropometric and environmental factors will be reviewed.

Quantitative phalangeal bone ultrasound is normal after long-term gluten-free diet in young coeliac patients

BACKGROUND AND AIMS

To determine bone mass using quantitative phalangeal bone ultrasound in young coeliac patients after a long-term gluten-free diet.

SUBJECTS

A total of 99 patients with coeliac disease (CD) (52 girls, mean age 15.5 +/- 9.7 years; 47 boys, mean age 14.4 +/- 8.4 years) and 44 healthy subjects matched for age, weight and height (26 girls, mean age 18.4 +/- 9.9 years; 18 boys, mean age 16.3 +/- 11.2 years) were included in the study.

METHODS

Bone status was assessed using an ultrasound device that measures amplitude-dependent speed of sound (Ad-SoS) in metres per second. Measurements were made on the phalanges (II-V) of the non-dominant hand, and an average value was computed. Nutrient intake was assessed using a 7-day record.

RESULTS

Analysis of variance (ANOVA) and the unpaired t-test showed that the intake of phosphates (P < 0.05), proteins, fat and carbohydrates (P < 0.005 in all) was higher in patients than in controls. No significant difference in Ad-SoS was found between patients and controls (95% CI -10.9 to 60.6) in the overall group, in girls or boys, or in patients following a gluten-free diet strictly or partially. In the patients, only age (beta 4.01, 95% CI 1.84-6.16, P < 0.0005) and weight (beta 2.62, 95% CI 1.53-3.70, P < 0.0001) showed a significant positive relation with Ad-SoS.

CONCLUSIONS

In patients with CD, gluten-free diet and increased nutritional intake were accompanied by normal bone mass values as determined by ultrasound on phalanges.

Celiac disease

Celiac disease is more prevalent than it was previously thought to be, and screening of selected population groups may reveal many new cases. Tissue transglutaminase appears to have a significant role in the degradation of gliadin and antigen production. Specific gliadin epitopes have been defined using T-cell responses. Bone disease is a significant problem for patients with celiac disease but management guidelines are being developed. Refractory sprue (nonresponsive celiac disease) appears to be a manifestation of enteropathy-associated T-cell lymphoma in most cases.