Vitamin D: Nutrient, Hormone, and Immunomodulator.

The classical functions of vitamin D are to regulate calcium-phosphorus homeostasis and control bone metabolism. However, vitamin D deficiency has been reported in several chronic conditions associated with increased inflammation and deregulation of the immune system, such as diabetes, asthma, and rheumatoid arthritis. These observations, together with experimental studies, suggest a critical role for vitamin D in the modulation of immune function. This leads to the hypothesis of a disease-specific alteration of vitamin D metabolism and reinforces the role of vitamin D in maintaining a healthy immune system. Two key observations validate this important non-classical action of vitamin D: first, vitamin D receptor (VDR) is expressed by the majority of immune cells, including B and T lymphocytes, monocytes, macrophages, and dendritic cells; second, there is an active vitamin D metabolism by immune cells that is able to locally convert 25(OH)D3 into 1,25(OH)2D3, its active form. Vitamin D and VDR signaling together have a suppressive role on autoimmunity and an anti-inflammatory effect, promoting dendritic cell and regulatory T-cell differentiation and reducing T helper Th 17 cell response and inflammatory cytokines secretion. This review summarizes experimental data and clinical observations on the potential immunomodulating properties of vitamin D.

Effect of intermittent PTH treatment on plasma glucose in osteoporosis: A randomized trial.

We investigated the effect of bone turnover on glucose homeostasis, fat distribution and adipokine production during anabolic treatment with PTH. This is a parallel, randomized controlled, open label, trial. The randomization was done by computer generated tables to allocate treatments. Forty-six postmenopausal osteoporotic non-diabetic women were assigned to treatment with calcium and colecalcipherol with (24) or without (22) PTH 1-84. Patients were recalled after 3, 6, 12 and 18 months of treatment and markers of bone turnover, glucose metabolism, adipokine secretion and fat distribution were analyzed. Markers of bone turnover and adipokines were measured by ELISA. Glucose metabolism was evaluated by an oral glucose load test and insulin resistance and secretion were calculated. Fat and lean mass were evaluated by anthropometric measures. The effect of treatment on measured variables was analyzed by repeated measure test, and its effect on glucose was also evaluated by mediation analysis after correction for possible confounders. Twenty patients in the calcium and vitamin D groups and 19 in the group treated with PTH 1-84 completed the study. There were no significance adverse events. Treatment with PTH increases osteocalcin, both total (OC) and undercarboxylated (uOC), and decreases blood glucose, without influence on insulin secretion, resistance and pancreatic ß cell function. Treatment with PTH does not influence fat distribution and adipokine production. The results of the mediation analyses suggest a total effect of PTH on blood glucose, moderately mediated by OC and to a less extent by uOC. Here we suggest that treatment with PTH influences glucose metabolism partially through its effect on bone turnover, without influence on insulin secretion, resistance, pancreatic ß cell function and fat mass.

Impact of a phone follow-up program on persistence with teriparatide or PTH(1-84) treatment.

A follow-up program to help patients suffering from severe osteoporosis during their therapy with teriparatide or PTH(1-84) has been designed and performed. The objective of this study was to evaluate the 18-month persistence on these therapies in patients participating in the program. We enrolled 382 patients who started teriparatide or PTH(1-84) following this program and compared them with a historical cohort of 398 patients treated with the same therapies but who did not participate in any follow-up program. At the beginning of the therapy, nurses trained patients on self-injection. Patients received one phone call per week during the first month, then one phone call per month and per 3 months during the following 5 and 12 months, respectively. In every call, nurses helped patients to resolve any possible issues and collected adverse event information. The persistence rate of the group following the program was 85.6%, 8.2% higher than that of the group not following any program (77.4%). The log-rank test on persistence rates on therapy in patients enrolled and not enrolled in the program was performed; the difference was statistically significant (P = 0.006). Discontinuation in the follow-up program group occurred mainly at early stages of the treatment due to adverse events. Our results show that patients suffering from severe osteoporosis treated with teriparatide or PTH(1-84) and enrolled in a follow-up program have higher persistence rates than patients not following the program.

Role of iron metabolism and oxidative damage in postmenopausal bone loss.

It has been suggested that iron-deficient rats have lower bone mass than iron-replete animals, but a clear association between bone and iron repletion has not been demonstrated in humans. A growing body of evidences also suggests a relation between lipid oxidation and bone metabolism and between iron metabolism and LDL oxidation. Iron availability to cells also depends on haptoglobin (Hp) phenotypes. Hp has also important antioxidant properties according to its phenotype, hence we evaluate whether Hp phenotype could influence bone density, iron metabolism and lipid oxidation. This cross-sectional study enrolled 455 postmenopausal women affected by osteoporosis (260) or not (195). Bone mineral density, markers of bone and iron metabolism, levels of oxidized LDL (oxLDL) and Hp phenotype were measured in all the subjects. Hp 1.1 and 2.2 frequency was higher and Hp 2.1 was lower in the patients with fragility fractures (80) compared with the controls. We therefore evaluate different Hp phenotypes as risk or protective factors against fragility fracture: Hp 2.1 is a protective factor against fracture while 1.1 is an important and 2.2 a moderate risk factor for fragility fractures. Lower serum iron was associated with elevated transferrin in patients with Hp 1.1; moreover patients had relative iron deficiency compared with the controls and fractured patients had higher level of oxLDL. We found that both iron metabolism and oxLDL varies according to Hp phenotypes and are predictive of bone density. Our data indicate that Hp 2.1 is a protective factor for fragility fractures, depending on its role on iron metabolism and its antioxidant properties.

Estrogen deficiency increases osteoclastogenesis up-regulating T cells activity: a key mechanism in osteoporosis.

Compelling evidences suggest that increased production of osteoclastogenic cytokines by activated T cells plays a relevant role in the bone loss induced by estrogen deficiency in the mouse. However, little information is available on the role of T cells in post-menopausal bone loss in humans. To investigate this issue we have assessed the production of cytokines involved in osteoclastogenesis (RANKL, TNFalpha and OPG), in vitro osteoclast (OC) formation in pre and post-menopausal women, the latter with or without osteoporosis. We evaluated also OC precursors in peripheral blood and the ability of peripheral blood mononuclear cells to produce TNFalpha in both basal and stimulated condition by flow cytometry in these subjects. Our data demonstrate that estrogen deficiency enhances the production of the pro-osteoclastogenetic cytokines TNFalpha and RANKL and increases the number of circulating OC precursors. Furthermore, we show that T cells and monocytes from women with osteoporosis exhibit a higher production of TNFalpha than those from the other two groups. Our findings suggest that estrogen deficiency stimulates OC formation both by increasing the production of TNFalpha and RANKL and increasing the number of OC precursors. Women with post-menopausal osteoporosis have a higher T cell activity than healthy post-menopausal subjects; T cells thus contribute to the bone loss induced by estrogen deficiency in humans as they do in the mouse.

Risedronate reduces osteoclast precursors and cytokine production in postmenopausal osteoporotic women.

UNLABELLED: This paper studies the effect of oral risedronate on osteoclast precursors, osteoclast formation, and cytokine production in 25 osteoporotic women. Risedronate is effective in reducing the number of osteoclast precursors, their formation, vitality, and activity and the level of RANKL and TNF-alpha in cultures. INTRODUCTION: Bisphosphonates inhibit bone resorption by acting against osteoclasts. Some in vitro studies suggest that they induce osteoclast apoptosis; others suggest that they exert an effect on the production of pro-osteoclastogenic cytokines. The effect of risedronate on osteoclastogenesis by peripheral blood mononuclear cells (PBMCs) in postmenopausal osteoporosis has not been previously studied. This paper examined the influence of risedronate on the formation of osteoclast precursors and cytokine production within the compass of osteoclastogenesis in osteoporosis. MATERIALS AND METHODS: This study was conducted on 38 osteoporotic women; 25 patients were treated with risedronate 5 mg/d, whereas 13 were treated with calcium 1 g/d and vitamin D 800 UI/d. The following parameters were assessed: changes in bone turnover, circulating osteoclast precursors, formation of osteoclasts in PBMC cultures, their activity and vitality, and variations in the production of pro-osteoclastogenic cytokines before and after therapy. RESULTS: After 3 mo of risedronate, there was a significant reduction in the number and degree of differentiation of osteoclast precursors, osteoclast formation, vitality and activity, and in the level of RANKL and TNF in cultures and of TNF and osteoprotegerin (OPG) in serum, whereas in the group treated with calcium and vitamin D, there were no significant changes. CONCLUSIONS: Our data show that risedronate is effective in lowering the number of circulating osteoclast precursors, their formation, vitality, and activity in cultures, and in reducing the level of pro-osteoclastogenic cytokines in culture supernatants and in serum.

Preoperative localization of parathyroid adenoma with sonography and 99mTc-sestamibi scintigraphy in primary hyperparathyroidism.

PURPOSE: To evaluate the sensitivity, specificity, and usefulness of dual-phase 99mTc-Sestamibi scintigraphy (SS) and sonography (US) of the neck, alone and in combination, as noninvasive adenoma localizing procedures in patients with primary hyperparathyroidism prior to parathyroidectomy. METHODS: We retrospectively analyzed the charts of 79 patients with parathyroid (PT) adenomas and confirmed diagnosis of hyperparathyroidism who were evaluated with SS and US prior to successful parathyroidectomy. RESULTS: Ninety-three adenomas were removed during bilateral neck exploration. SS alone showed a sensitivity of 76% and a specificity of 79% compared with 89% and 75%, respectively, for US performed after SS on the same day. Combination of the 2 procedures yielded a sensitivity of 89% and a specificity of 90%, with 22% discordant results. The differences in sensitivity and specificity between the 2 techniques alone or in combination were not statistically significant. CONCLUSIONS: No benefit was gained from using both SS and US for the preoperative localization of PT adenomas in patients with primary hyperparathyroidism. Each technique can be negatively affected by thyroid enlargement and nodularity. US, when performed by a skilled operator, is a reliable tool for PT adenoma localization. If the US findings are inconclusive, SS should be used.

Prevalence of Paget's disease of bone in Italy.

UNLABELLED: We examined the prevalence of PDB in Italy from radiological, scintigraphic, and biochemical surveys in two Italian towns. Prevalence rates varied from 0.7% to 2.4%, were higher in males than in females, and slightly differed between the two towns. Unlike previous studies in populations of British descent, no secular trend for a decreasing prevalence emerged. INTRODUCTION: Clinical, radiological, and necropsy data from different countries suggested pronounced geographical variations in the prevalence of Paget's disease of bone (PDB). Despite the impact of the disease on the population, there are limited data on the prevalence of PDB in Italy. MATERIALS AND METHODS: The objective of this study was to estimate the prevalence of PDB in the district of Siena (Central Italy) and Turin (Northern Italy) from radiological, biochemical, and scintigraphic surveys. We examined a sample of 1778 consecutive pelvic radiographs performed between 1999 and 2000 at the Hospital Radiology Unit in Siena and 6609 pelvic radiographs performed in 1986-1987, 1992-1993, and 1999-2002 from the Radiology Department of Molinette Hospital in Turin. In Siena, 7906 consecutive (99m)TC-MDP bone scans performed over a 4-year period (January 2000 to May 2004) were also screened for the presence of PDB, and the prevalence of elevated alkaline phosphatase (ALP) levels (>300 UI/liter) was estimated from 7449 computerized medical records over a 3-year period (January 2000 to February 2003). The finding of PDB on the pelvic radiograph and bone scan was based on standardized radiological criteria. RESULTS: At the end of the radiological surveys, 16/1778 pelvic PDB cases (8 males and 8 females) were observed in Siena and 41/6609 (27 males and 14 females) in Turin. The crude prevalence of the disease was 0.89% in Siena and 0.62% in Turin. Given that pelvic involvement is commonly described in 60-90% of PDB patients, the estimated overall prevalence of PDB ranged from 1.0% to 1.5% in Siena and from 0.7% to 1.0% in Turin. No decrease in the prevalence of PDB was evident after comparison of prevalence rates from different periods. Biochemical analyses showed 296/7449 subjects with elevated ALP levels and normal liver enzymes, 87 of whom had confirmed diagnosis of PDB. The estimated prevalence of biochemical PDB was 1.5%. The scintigraphic survey showed a PDB prevalence of 194/7906 (2.4%), which was significantly higher than the radiological and biochemical estimates. CONCLUSIONS: Our surveys suggest that PDB in Italy has an estimated prevalence of at least 1%, comparable with that observed in United States and other European countries, but lower than that described in Britain and New Zealand. No secular trend for a decreasing prevalence of PDB was observed.

Spontaneous osteoclast formation from peripheral blood mononuclear cells in postmenopausal osteoporosis.

Osteoclasts are cells involved in bone reabsorbing and hence in postmenopausal bone loss. There is no evidence of increased in vitro spontaneous osteoclast formation in postmenopausal osteoporosis. The aim of our study was to evaluate spontaneous osteoclastogenesis in osteoporosis. Bone mineral density, markers of bone turnover, and cultures of peripheral blood mononuclear cells (PBMC) on dentine slices with or without the addition of 1,25-OH vitamin D3 ([10(-8) M]) were obtained from 18 osteoporotic women and 15 controls. To verify cytokine production by PBMC cultures, supernatants were collected on days 3 and 6 and tested for TNF-alpha and RANKL. The data obtained were compared between patients and controls by one-way ANOVA and correlated by Pearson's coefficient. We found a significant increase in osteoclast formation and bone reabsorbing activity in patients with respect to controls; in addition, the production of TNF-alpha and RANKL is significantly higher in patients. Furthermore, osteoclast number is inversely correlated with bone mineral density and directly with RANKL in culture supernatants. Our data demonstrated an increased spontaneous osteoclastogenesis in women affected by postmenopausal osteoporosis: this increase may be explained by the higher production of TNF-alpha and RANKL by PBMC cultures of osteoporotic patients.