M. Pedrazzoni

Bisphosphonates stimulate formation of osteoblast precursors and mineralized nodules in murine and human bone marrow cultures in vitro and promote early osteoblastogenesis in young and aged mice in vivo

Recent in vitro findings suggest that bisphosphonates, potent inhibitors of osteoclastic bone resorption, may also have a direct action on osteoblasts. The purpose of this study was to search for potential effects of etidronate and alendronate on the formation of early and late osteoblastic cell precursors by measuring the number of colony-forming units for fibroblasts (CFU-F) and colony-forming units for osteoblasts (CFU-OB) in murine and human bone marrow cultures. In murine marrow cultures, etidronate (10(-5) to 10(-9) mol/L) significantly stimulated the formation of CFU-F with a maximal effect at 10(-5) mol/L (mean increase over control values+/-SD: 106+/-17%;p < 0.001), whereas alendronate had a biphasic effect, being stimulatory at concentrations below 10(-7) mol/L (78+/-5%; p < 0.001), and inhibitory at higher doses. The formation of CFU-OB was also inhibited by both bisphosphonates at the highest concentrations (10(-5) mol/L and 10(-6) mol/L), but it was significantly stimulated at lower concentrations (from 10(-7) to 10(-9) mol/L for etidronate and 10(-7) to 10(-10) mol/I, for alendronate; p < 0.001). In human bone marrow cultures, alendronate (10(-8) to 10-(12) mol/L) increased CFU-F formation with a maximal effect at 10(-10) mol/L (161+/-12 %; p < 0.01). CFU-OB formation, observed only in the presence of dexamethasone (10(-8) mol/L), was markedly stimulated by alendronate at the above concentrations with a maximal increase at 10(-10) mol/L (133+/-34%; p < 0.001). The in vivo short-term effects of bisphosphonates on the formation of early osteoblast precursors were also studied in bone marrow cultures from young female mice treated with weekly subcutaneous injections of etidronate (0.3, 3, and 30 mg/kg) or alendronate (0.3, 3, and 30 microg/kg) and from aging female mice treated with the two lowest doses of both drugs. After 1 month of treatment, etidronate (0.3 and 3 mg/kg) and alendronate (0.3 and 3 microg/kg) significantly increased the number of CFU-F colonies in the bone marrow from young and old animals, whereas the highest dose of both drugs had no effect in young mice. Our results, together with previously reported observations of bone-forming effects in osteoporosis, suggest that bisphosphonates may have, in vivo, a potentially relevant influence on cells of the osteoblastic lineage, distinct from their inhibitory action on osteoclasts.

Massive Load of Functional Effector CD4+ and CD8+ T Cells against Cytomegalovirus in Very Old Subjects

A progressive, systemic, and low-grade proinflammatory status is one of the major characteristics of immunosenescence. Emerging data suggest a possible contribution of CMV, known to chronically infect a large proportion of humans, lifelong from newborns to centenarians. To test this hypothesis, we evaluated functional T cell responses to two CMV immunogenic proteins, pp65 and IE-1, in 65 chronically infected subjects aged 25–100 years. PBMC were stimulated with mixtures of peptides spanning the entire sequence of both proteins, and Ag specificity and magnitude of intracellular IFN-γ- and TNF-α-positive cells were then analyzed within both CD4+ and CD8+ T cells. Results indicate that pp65 and, to a lesser extent, IE-1 constitute major Ags against which aged people target functionally efficient T cell effector responses with massive production of Th1 cytokines and exhibition of CD107a degranulation marker. As a result, the production of IFN-γ induced in T cells by both Ags was seven to eight times greater in very old than in young subjects. The comparative analysis of pp65-specific responses in these very long-term carriers revealed a reciprocal relationship between CD4+ and CD8+ producing IFN-γ in the same individuals. These results indicate that CMV represents an important pathogen responsible for a strong immune activation in human aging. Such a remarkable burden of effector CD4+ and CD8+ T cells may be necessary to protect the elderly from CMV endogenous reactivation, but can turn detrimental by giving a substantial contribution to the proinflammatory status that accompanies the main age-related diseases.

Fat-free mass and fat mass reference values by dual-energy X-ray absorptiometry (DEXA) in a 20–80 year-old Italian population

BACKGROUND & AIMS To establish reference values for limb composition, fat-free mass (FFM) and fat mass (FM) in Italian adults for gender-specific age brackets 20-80 years old and to assess age-related regional changes in body composition. METHODS A multicenter, retrospective study was conducted on 1571 healthy subjects, 1240 women and 331 men. Regional FFM and FM were measured by dual-energy X-ray absorptiometry. FM was expressed as % of limb weight. RESULTS FFM in men diminished with age in both arms and legs, with reference ranges (25th -75th percentile) of 3.8-4.6 kg and 10.4-12.2 kg, respectively for 20-29 year-olds, and 3.1-3.9 kg and 8.2-10.4 kg for 70-79 year-olds. Womens arm FFM remained stable with aging (reference values 1.7-2.2 kg), decreasing in their legs (6.2-7.2 kg for 20-29 year-olds, 5.5-6.5 kg for 70-79 year-olds). Limb FM% increased with age in both genders: the reference values were 9-15% (arms) and 12-21% (legs) for 20-29 year-old men, and 19-26% and 19-29%, respectively, for 70-79 year-olds; for womens arms, they were 25-36% for 20-29 year-olds and 36-48% for 70-79 year-olds, while their leg FM remained the same with aging, i.e. 32-40%. CONCLUSIONS These data complete the published reference values for whole body composition, enabling physiological or pathological changes in limb composition to be identified in Caucasian populations living in the Mediterranean area.

Marked increase with age of type 1 cytokines within memory and effector/cytotoxic CD8+ T cells in humans: a contribution to understand the relationship between inflammation and immunosenescence.

The ageing process is characterized by a progressive exhaustion of the naïve T cell reservoir that is accompanied by a compensatory expansion of effector/cytotoxic CD8+CD28- T cells. However, the origin and function of this subpopulation is not completely clarified. In this study, we examined the intracellular cytokine profile in purified CD8+ T cells obtained from 29 healthy subjects of different ages. Type 1 (IFN-gamma IL-2 and TNF-alpha) and type 2 (IL-4, IL-6 and IL-10) cytokines were determined in three CD8+ T subsets, i.e. CD95-CD28+ (naïve), CD95+CD28- (effector/cytotoxic), and CD95+CD28+ (memory). As a general trend, we observed, in aged subjects, an increase of type 1 and type 2 intracellular cytokines within the three CD8+ subsets. In particular, we showed that type 1 cytokine-positive cells significantly increased, with age, among all the CD8+ subsets, while a marked increase of type 2 producing cells was observed only in memory CD8+ T cells. These profound changes are compatible with inflame-aging, an hypothesis which suggest that immunosenescence is mainly driven by a chronic antigenic load which not only induces an enormous expansion of CD28- T cells, but also increases their functional activity, exemplified by an high frequency of cells positive for pro-inflammatory cytokines.

Serum interleukin-6, soluble interleukin-6 receptor and soluble gp130 exhibit different patterns of age- and menopause-related changes.

Growing evidence suggests that interleukin-6 (IL-6) may play a pathogenetic role in postmenopausal bone loss and in other age-related pathological conditions. In this study, we have examined the age-related changes in the serum levels of IL-6 and the soluble receptors that modulate its biological activity--soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130)--in 220 women (from 25 to 104yr old), including 22 centenarians. Serum IL-6 rose exponentially with age (r=0.74, p<0.0001). The median level of IL-6 increased almost ten-fold with age, from 1.16pg/ml in premenopausal women to 10.27pg/ml in centenarians. Serum sIL-6R and sgp130 showed an increase until the seventh decade and a progressive decrease in older ages (r=0.39, p<0.0001 and r=0.26, p=0.008, respectively). IL-6, sIL-6R and sgp130 were significantly higher in women within 10yr of menopause as compared to premenopausal subjects (1.51 vs. 1.16pg/ml, p=0.012; 41.9 vs. 35.7ng/ml, p=0.002; and 253.4 vs. 230.7ng/ml, p=0.008, respectively). In postmenopausal women, a negative correlation was found between sIL-6R and the lumbar bone mineral density (BMD) (r=-0.28, p=0.002) even after adjusting for age and weight. Furthermore, sIL-6R levels were higher in osteoporotic compared to normal women (47.9 vs. 39.5ng/ml, p=0.001). In conclusion, our results show that the serum levels of IL-6, sIL-6R and sgp130 exhibit different patterns of age- and menopause-related changes, and that the biological activity of IL-6 may be increased with age with potential implications in the age-related diseases such as osteoporosis.

Intermittent treatment with intravenous 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP) in the therapy of postmenopausal osteoporosis

Since data on the efficacy of 4-amino-2-hydroxybutylidene-1,1-bisphosphonate (AHBuBP) in the therapy of osteoporosis are not yet available, we have examined in an open, randomized study, the effects of an intravenous intermittent treatment with this drug on the vertebral and radial bone mass in postmenopausal osteoporosis. Forty postmenopausal osteoporotic women were randomly assigned to one of two groups, one treated with AHBuBP (5 mg/day on two consecutive days every 3 months for one year; n = 20), the other with oral calcium (n = 20). The bone mineral density (BMD) of the spine increased significantly in women receiving AHBuBP, whereas it tended to decrease in patients given calcium. The differences in the vertebral BMD changes between groups was highly significant (P less than 0.01). Radial BMD tended to increase in patients treated with AHBuBP, and to decrease in patients receiving calcium. The difference in the linear trends was statistically significant (P less than 0.05). The side effects of AHBuBP (a transient acute phase reaction in 3 out of 20 subjects) were slight and well-tolerated. A good effect of AHBuBP was observed also on back pain (P less than 0.05). We conclude that intermittent treatment with AHBuBP is capable of increasing spinal BMD and conserving radial BMD in postmenopausal osteoporosis and may represent a convenient therapeutic choice in this condition.

Intense Antiextracellular Adaptive Immune Response to Human Cytomegalovirus in Very Old Subjects with Impaired Health and Cognitive and Functional Status

Human aging is characterized by expanded and altered adaptive immune responses to human CMV (HCMV). It is unclear whether this expansion has its origins in age-related homeostatic disturbances or viral reactivation, whether anti-CMV immune surveillance may still be effective, and what are the consequences of this expanded immune response for health and longevity. We conducted an observational cross-sectional study in groups of HCMV-seropositive subjects aged ≥65 y of variable health status to compare the intensity of Ab responses against HCMV with those against EBV and with CD4+ and CD8+ T cell proinflammatory effector responses directed to HCMV-derived pp65 and immediate-early protein 1 synthetic peptides. Ab responses to HCMV, but not to EBV, and anti-HCMV CD4+, but not CD8+, T cell responses were more intense in elderly subjects aged ≥85 y in poor health and were inversely correlated with markers of functional activity and cognitive function. Therefore, humoral and CD4+ T cell anti-HCMV responses were specifically intensified in advanced aging associated with comorbidity and cognitive and functional impairments. Such a distinctive pattern of adaptive immunity indicates that immune responses targeting the extracellular phase of HCMV are increased in these elderly subjects and could represent an indirect effect of localized and undetectable HCMV reactivation. This study demonstrates that the oldest subjects in poor health with physical and mental impairment express intense functional immune responses to extracellular HCMV and suggests that they may be at risk for direct pathogenic effects by HCMV reactivation as well as indirect pathogenic effects linked to proinflammatory anti-HCMV effector responses.

Osteocalcin levels in diabetic subjects

SummaryBecause a series of reports suggests the existence of altered bone and mineral metabolism in diabetes mellitus, we studied 106 diabetic subjects (42 insulin-dependent (IDD) and 64 noninsulin dependent (NIDD)) to determine whether a difference in bone turnover (evaluated by serum osteocalcin (OC)) could be found in comparison with normal controls. OC levels in diabetic subjects were lower than the age- and sex-specific predicted values. The reduction was especially evident in male and female NIDD (Z-score: −1.12±0.92, t=8.4,P<0.001 and −0.84±0.86, t=4.0,P<0.01, respectively) and male IDD (Z-score: −0.90±0.86, t=4.5,P<0.01). The mean Z-score for female IDD, albeit negative (−0.31±0.79; t=1.6; 0.2>P>0.1), was not significantly different from normal. Total serum calcium (Ca) and calcitonin (CT) showed an apposite pattern, being higher in all the diabetic subgroups (with the exception of Ca in female IDD), whereas parathyroid hormone (PTH) was lower than expected in each diabetic subset. By multiple regression analysis, the reduction of OC was related to PTH and CT levels and to the type of treatment. Subjects controlled with diet showed differences of greater magnitude from the expected normal values than those treated with oral hypoglycemic agents or insulin (Z-score: −1.28±1.05 vs. −0.85±0.90 and −0.63±0.97, respectively;P=0.05). However, the variance explained by these three factors was small, suggesting that other variables (possibly α,25(OH)2D) exerted important influences on OC levels.

Human myeloma cells express the bone regulating gene Runx2/Cbfa1 and produce osteopontin that is involved in angiogenesis in multiple myeloma patients

Osteopontin (OPN) is a multifunctional bone matrix glycoprotein that is involved in angiogenesis, cell survival and tumor progression. In this study we show that human myeloma cells directly produce OPN and express its major regulating gene Runx2/Cbfa1. The activity of Runx2/Cbfa1 protein in human myeloma cells has also been demonstrated. Moreover, using small interfering RNA (siRNA) to silent Runx2 in myeloma cells, we suppressed OPN mRNA and protein expression. OPN production in myeloma cells was stimulated by growth factors as IL-6 and IFG-1 and in turn OPN stimulated myeloma cell proliferation. In an ‘in vitro’ angiogenesis system we showed that OPN production by myeloma cells is critical for the proangiogenic effect of myeloma cells. The expression of OPN by purified bone marrow (BM) CD138+ cells has also been investigated in 60 newly diagnosed multiple myeloma (MM) patients, finding that 40% of MM patients tested expressed OPN. Higher OPN levels have been detected in the BM plasma of MM patients positive for OPN as compared to controls. Moreover, significantly higher BM angiogenesis has been observed in MM patients positive for OPN as compared to those negative. Our data highlight that human myeloma cells with active Runx2/Cbfa1 protein directly produce OPN that is involved in the pathophysiology of MM-induced angiogenesis.

ACUTE EFFECTS OF BISPHOSPHONATES ON NEW AND TRADITIONAL MARKERS OF BONE RESORPTION

Bisphosphonates are known to be potent inhibitors of osteoclast activity and their only clinically relevant effect in the short-term is the selective inhibition of bone resorption. The purpose of this study was to compare the response to the intravenous administration of two bisphosphonates, clodronate and alendronate, of several biochemical markers of bone resorption, including tartrate-resistant acid phosphatase (TRAP) and cross-linked carboxyterminal telopeptide of collagen I (ICTP) in serum and hydroxyproline (OHP), free pyridinium cross-links (Pyr), and crosslinked N-telopeptides of collagen I (NTx) in urine. The study was carried out on 11 osteoporotic and 12 Pagetic subjects of both sexes, treated with clodronate (600 mg/day for 2 days) or alendronate (5 mg/day for 2 days), and monitored for 28 days after bisphosphonate administration. All the urinary markers of bone resorption showed a prompt decline after bisphosphonates, with maximum reductions after 7–14 days: Pyr decreased by 43%±9% and 42%±22% (mean ± SD), respectively in osteoporotic and pagetic subjects, OHP by 51%±14% and 51%±20%, and NTx by 55%±15% and 65%±26%. In the osteoporotic group, the urinary markers began to increase again at 30 days, though still remaining well below the basal level, whereas in the pagetic group, the excretion of all markers remained depressed until the end of the observation period. The reduction of NTx was significantly greater than that of Pyr and OHP in pagetic patients (P<0.05) and tended to be greater than that of Pyr in osteoporotic patients (p=0.07). Serum levels of TRAP decreased slightly, with a maximum reduction after 7 days of 16%±22% and 21%±11% in osteoporotic and pagetic subjects, respectively. Serum ICTP levels showed a slow and limited decrease, with minimal values after 14 days in pagetic subjects (-9%±21%; p=NS) and 30 days in osteoporotic patients (13%±4%; P<0.05). The cumulative changes of all urinary markers, expressed as area under the curve, were significantly greater than those observed for serum markers (P<0.01). In conclusion, these results indicate that the new markers of bone resorption differ in their capacity to reflect the acute inhibition of bone resorption following the I.V. administration of bisphosphonates. The use of bisphosphonates may be a useful means to test new markers of bone resorption.