Patrizia D'Amelio

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.

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‐α and RANKL. The data obtained were compared between patients and controls by one‐way ANOVA and correlated by Pearsons 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‐α 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‐α and RANKL by PBMC cultures of osteoporotic patients.

Risedronate reduces osteoclast precursors and cytokine production in postmenopausal osteoporotic women

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‐α in cultures.

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.

Bone Mineral Density and Singh Index Predict Bone Mechanical Properties of Human Femur

The aim of our study was to assess the predictive value of the Singh index (SI), which estimates bone architecture, and bone density (BMD) when dealing with the mechanical competence of bone and to analze possible differences in bone properties between gender in humans. The relationship between SI, BMD, and mechanical competence was analyzed in 106 bone cylinders from 37 human femoral heads obtained during hip-joint replacement surgery for low energy fracture or for osteoarthritis. Bones from osteoporotic patients are less dense and more brittle compared with bones from osteoarthritic patients, as expected. Among osteoporotic patients female bones were more brittle than those from males, although BMD was similar. In osteoarthritic patients there were no significant differences among sexes. Bone mechanical competence varies according to BMD and to SI categories. Thus, our study suggests that bone strength is predicted by both BMD and bone architecture.

The use of raloxifene in osteoporosis treatment.

Introduction: Osteoporosis is a common disease characterized by the occurrence of fragility fractures. Major osteoporotic fractures are associated with decreased quality of life and high costs. Areas covered: This review summarizes clinical data on raloxifene (RLX), a second generation selective estrogen-receptor modulator (SERM), currently approved for the treatment of postmenopausal osteoporosis. RLX has estrogen effects on bone and lipid profile, whereas it has anti-estrogen effects on uterus and breast cells. Its main side effects are hot flushes and venous thromboembolism. Literature searches were conducted to retrieve articles reporting RLX clinical trial data. For comparison of safety and efficacy, post-marketing studies on RLX were included. Expert opinion: RLX is effective in reducing vertebral fracture risk in osteoporotic women, it is safe and its ability to prevent breast cancer has to be considered in the analyses of cost/effect and of the ideal candidate to this treatment. RLX has to be avoided in patients with previous history of venous thromboembolism.

The immune system and postmenopausal osteoporosis

In the last decay investigators have paid attention to the relation between immune system, estrogen deficiency and bone loss; some of the pathways have been clarified whereas others remain an unexplained challenge. This review summarizes the evidence that links immune cells, estrogen loss, and osteoclast formation and activity.

Analysis of vitamin D receptor expression and clinical correlations in patients with ovarian cancer

OBJECTIVE Although the antiproliferative and differentiating properties of vitamin D have been demonstrated, its effects on cancer cells are variable. Little is known about vitamin D receptor (VDR) levels in patients with ovarian cancer. In this population we sought to determine correlations between VDR expression, clinical parameters and treatment outcome. METHODS We analyzed VDR content in platelets of healthy women and of a cohort of patients with ovarian tumors and we evaluated possible correlations with clinical parameters, tumor characterization (stage, histology, nuclear grading, ascites), response to therapy and survival. Moreover receptor expression was evaluated immunohistochemically on tissue samples. RESULTS VDR levels were markedly lower in healthy women when compared with the pathological group. In the latter a significant increase in receptor expression was observed in malignancies compared with benign cases. No correlation existed between VDR expression and clinicopathological parameters, although we observed an advantage on survival if patients had a higher level of VDR expression in platelets. A cytoplasmic localization of the protein was observed by immunohistochemistry in ovarian cancer cells. CONCLUSIONS Vitamin D receptor status measured in platelets differs significantly between healthy and pathological groups, increasing with malignancy, and there is a trend towards longer overall survival for tumors showing higher VDR levels. These data suggest that platelet VDR content could be used as a pathological marker. The meaning of this increased VDR expression in platelets needs further investigation and it is possibly linked to an inflammatory response.

Densitometric study of developing femur.

Abstract. The purpose of this work was to extend to long bones the study on the ossification of human fetal skeleton in relation to conceptual age by a quantitative methodological approach. Postero-anterior scans were performed on 29 dried fetal femora (from 11.5 weeks of conceptual age to term) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). BMD was calculated on a rectangular area corresponding to the total length and minimum width of the shaft. This area was divided into five equal sections along its longitudinal axis in order to estimate the rate of ossification from a spatio-temporal point of view. Our data show that BMC has a high correlation with conceptual age during the whole prenatal life, increasing in the third trimester (r ≥ 0.96). During development, BMD is progressively less correlated with conceptual age (r = 0.95 in the first half of development, r = 0.68 in the second half), particularly according to a bidirectional gradient from the middle to the proximal and distal ends of the shaft. Our findings confirm the data obtained in our previous studies on the ossification of fetal human spines, and suggest an individual variability in bone density at term of development and particularly at the level of spongiosa, viz. in the areas mostly involved in architectural changes during the morphogenesis of the long bones.

Male Osteoporosis in the Elderly.

Osteoporosis is now recognized as an important public health problem in elderly men as fragility fractures are complicated by increased morbidity, mortality, and social costs. This review comprises an overview of recent findings in pathophysiology, diagnosis, and treatment of male osteoporosis, with particular regard to the old population.