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An acute phase response (APR) is frequently observed in patients treated with intravenous (i.v.) zoledronate (ZOL). We aimed to define clinical and laboratory parameters that may predict ZOL-induced APR in women with low bone mass. Fifty-one postmenopausal women with low bone mass were given a single i.v. infusion of ZOL 5mg. APR was clinically defined by the visual analog pain scale (VAS) for the musculoskeletal symptoms and body temperature. White blood cell count (WBC), leucocyte subpopulations, C-reactive protein (CRP), parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D], interleukins (IL)-1b and -6, tumor necrosis factor (TNF)α and interferon (IFN)γ were measured before and 48 h following the infusion. Subsequently, patients were divided into those experiencing APR (APR+) or not (APR-). WBC, granulocytes, CRP, IL-1b and IL-6 were significantly increased, whereas lymphocytes, eosinophils, calcium, phosphate and 25(OH)D decreased 48h after ZOL infusion. Twenty-eight of the 51 patients (54.9%) experienced an APR. APR+ patients were younger and had higher baseline lymphocytes compared to APR- patients. There was no difference (p=0.405) in the development of APR between treatment-naive patients (19/32, 59.4%) and patients previously treated with another oral nitrogen-containing bisphosphonate (9/19, 47.4%). In conclusion, our data suggest that pre-treatment higher lymphocyte number increases the risk of APR while previous treatment with another nitrogen-containing bisphosphonate does not significantly reduce the risk. Serum 25(OH)D concentrations decrease significantly after the infusion, possibly as part of the inflammatory response to ZOL.

The evaluation of circulating semaphorin-4D (sema4D) and plexin-B1 in postmenopausal women with low bone mass and the effect of antiresorptive or osteoanabolic treatment.Serum samples were obtained from postmenopausal women with low bone mass at baseline and 3 months after zoledronic acid infusion (n = 30), denosumab injection (n = 30) or teriparatide initiation (n = 28) and from controls matched for age, age at menopause and body mass index (n = 30) at the same time points.Circulating sema4D and plexin-B1.Circulating sema4D increased following denosumab (p = 0.026), whereas decreased following teriparatide (p = 0.013). Sema4D/plexin-B1 ratio increased following denosumab (p = 0.004). At baseline, sema4D and plexin-B1 levels were higher in patients pre-treated with bisphosphonates compared to naïve ones (p0.001 and p = 0.001, respectively). In bivariate correlations sema4D was inversely correlated with serum carboxyterminal telopeptide of type 1 collagen (rs -0.282, p = 0.002), intact parathyroid hormone (rs -0.388, p0.001) and 25(OH)D (rs -0.316, p0.001), whereas there was a trend towards correlation with lumbar spine bone mineral density (rs -0.191, p = 0.053).Sema4D levels are independently associated with previous bisphosphonate treatment, intact parathyroid hormone and 25(OH)D levels. Denosumab and teriparatide seem to exert an opposite effect on circulating sema4D levels. Further studies are needed to evaluate whether sema4D mediates the coupling effect that occurs following both antiresorptive and osteoanabolic treatment.

In vitro data suggest that myokine irisin may affect bone metabolism by promoting osteoblast differentiation while inhibiting osteoclast differentiation. In this study, circulating irisin levels were associated with previous osteoporotic fractures but not with bone mass and were not affected by denosumab or teriparatide treatment for 3 months. This study aimed to evaluate predictors of circulating irisin in postmenopausal women with low bone mass and to assess a potential effect of denosumab or teriparatide treatment for 3 months. Serum samples for irisin measurement were obtained from (a) postmenopausal women with low bone mass (lumbar spinal [LS] or femoral neck [FN] bone mineral density [BMD] T-score ≤−2.0) and their age-matched controls at baseline and 3 months after denosumab (Dmab) injection (Dmab group, n = 50; Dmab control group, n = 25) and (b) women with more severe disease (LS or FN BMD T-score ≤−2.8) and their age-matched controls at the above-mentioned time points after teriparatide (TPTD) initiation (TPTD group, n = 25; TPTD control group, n = 25). At baseline, irisin levels were inversely correlated with age (partial coefficient (r p ) = −0.24; p = 0.009), parathyroid hormone (PTH) (r p = −0.30; p = 0.001), and creatinine (r p = −0.23; p = 0.016) in univariate analysis, and were lower in women with (n = 26; 41.6 ± 2.7 ng/dL) than without previous osteoporotic fracture(s) (n = 99; 51.0 ± 1.6 ng/dL; p = 0.007). In multiple linear regression, previous osteoporotic fracture(s) and PTH were independently negatively associated with irisin [p = 0.04, CI −16.1 to −0.4 and p = 0.002, CI −0.3 to −0.07, respectively], but only the association with PTH remained after controlling for creatinine levels. Serum irisin levels were not different between women with or without low bone mass and were not affected by either Dmab or TPTD treatment for 3 months. Circulating irisin levels were associated with previous osteoporotic fracture(s); whether this association is independent or is due to confounding by lower muscle mass, potentially reflected by lower creatinine levels, remains to be fully clarified.

Periostin is a secreted extracellular matrix protein preferentially expressed in bone by osteocytes and periosteal osteoblasts. Reduced periostin expression may affect osteoblast differentiation and collagen type I synthesis and predispose to osteoporosis and increased fracture risk. We aimed to evaluate circulating periostin levels in postmenopausal women with low bone mass, their possible correlations with clinical and laboratory parameters, as well as the 3-month effect of zoledronic acid. Serum samples for periostin, 25-hydroxyvitamin D, parathyroid hormone (PTH), C-terminal telopeptide of type I collagen (CTx), and total alkaline phosphatase (tALP) were obtained from 46 postmenopausal women with low bone mass at baseline and 3 months after zoledronic acid infusion and from 30 age-matched, postmenopausal controls with normal bone mass at baseline. There was no difference in periostin levels between women with normal and low bone mass (250±15 vs. 272±14 ng/ml, respectively; p=0.279). Periostin remained essentially unchanged after zoledronic acid infusion (262±18 ng/ml; p=0.130). Serum periostin levels at baseline were not affected by previous bisphosphonate treatment, and were correlated only to tALP (rs=0.351; p=0.018). In multiple linear regression analysis, tALP (B=3.17; 95% CI=0.59–5.79; p=0.018) was associated with serum periostin levels at baseline, independently from previous anti-osteoporotic treatment, age, body mass index, and 25-hydroxyvitamin D. In conclusion, serum periostin levels do not differ between postmenopausal women with normal and low bone mass and are not affected by zoledronic acid treatment. Women with higher tALP have independently higher periostin levels.

Activin-A is expressed in bone and seems to regulate osteoclastogenesis. In this study, serum activin-A was increased in postmenopausal women with low bone mass and was positively correlated to age and negatively to lumbar spinal bone mineral density (BMD). Serum activin-A levels did not change 3 months after zoledronic acid infusion.The aims of the study were to evaluate prospectively the circulating activin-A levels in postmenopausal women with low bone mass and explore possible correlations with clinical and laboratory data, as well as the 3-month effect of zoledronic acid infusion.Postmenopausal women with low bone mass assigned to receive zoledronic acid infusion (Patients, n = 47) and age-matched, postmenopausal women with normal bone mass (Controls, n = 27) were recruited on an outpatient basis. Main outcome measurement was serum activin-A levels.Serum activin-A was higher in patients at baseline compared to controls (p 0.001) and activin-A in the serum of patients and controls was positively correlated with age (Spearman's coefficient of correlation [rs] = 0.325; p = 0.005) and negatively with lumbar spinal (LS) BMD (rs = -0.425; p 0.001). In multiple linear regression analysis, only age (B = 8.93; 95 % CI = 4.39-13.46; p 0.001) was associated with serum activin-A levels at baseline, independent from group (patients or controls), previous anti-osteoporotic treatment, LS BMD and follicle-stimulating hormone. Circulating activin-A levels were not affected 3 months after zoledronic acid infusion.Serum activin-A is increased in postmenopausal women with low bone mass compared with postmenopausal women with normal bone mass and is positively correlated to age and negatively to LS BMD.