Early Effects of Single and Low-Frequency Repeated Administration of Teriparatide, hPTH(1-34), on Bone Formation and Resorption in Ovariectomized Rats

Dynamic morphometric changes in the mandibular osteocytic lacunae of ovariectomized rats in response to teriparatide, as revealed by three-dimensional fluorescence analyses: Possible involvement of osteocytic perilacunar remodeling

OBJECTIVES

Teriparatide [TPTD; human parathyroid hormone (hPTH1-34)] is an anti-osteoporotic drug with bone anabolic effects. Clinical and preclinical studies have indicated that TPTD has value in oral and maxillofacial bone therapies, including jawbone regeneration, periodontal tissue repair, and the treatment of medication-related osteonecrosis of the jaw. However, it is unclear whether the craniofacial bones respond to TPTD similarly to the axial and appendicular bones. Recent studies showed that TPTD acts on both osteocytes and osteoblasts. This study aimed to characterize distinct craniofacial bone sites, with a focus on morphometric changes in osteocytic lacunae in ovariectomized rats receiving TPTD.

METHODS

Conventional bone histomorphometric analyses of mandibular and parietal bone sections were conducted. High-resolution confocal imaging-based three-dimensional fluorescence morphometric analyses of osteocytic lacunae in distinct mandibular and parietal bone sites were conducted.

RESULTS

We observed dynamic changes in the morphometric characteristics of osteocytic lacunae specifically in alveolar and other mandibular bone sites upon TPTD administration.

CONCLUSIONS

These findings suggest that osteocytes in mandibular bone (specifically, alveolar bone) have unique functional characteristics of osteocytic perilacunar remodeling.

Effects of Teriparatide Treatment on Bone Mineral Density in Patients With Osteoporosis: A Short-Term Dose-Response Study

INTRODUCTION

Osteoporosis is a chronic bone disease that develops with a decrease in bone mineral density (BMD) along with bone mass. An essential measure in the prevention of osteoporosis is the achievement of normal peak bone mass. Teriparatide (TPTD) functions as an osteoanabolic agent, exerting a dual influence on bone remodeling by modulating both osteogenesis and osteoclastogenesis. Bone mass is determined by dual-energy x-ray absorptiometry (DEXA) quantitative CT scan and has outstanding precision (within 1% to 2%) and has the ability to show the effectiveness of drug intervention.

OBJECTIVE

To assess the effectiveness of TPTD treatment on BMD in osteoporosis patients.

MATERIALS AND METHODS

The study is a retrospective, observational, multi-center study of 378 osteoporosis patients who were treated with 20 µg of subcutaneous TPTD every day for six months. DEXA scores of the hip joints of patients were measured both before and after TPTD treatment.

RESULTS

 The DEXA scores of the total population pre and post-treatment were -2.75+0.58 and -2.15+0.95 respectively, with a p-value of <0.001, which is statistically significant. In women the pre and post-treatment scores were -2.728+0.52 and -2.276+0.49, with a significant p-value of <0.001 whereas in males, the scores were -2.756+0.72 and -2.108+1.29 respectively, with a significant p-value of <0.05.

CONCLUSION

The six-month treatment with TPTD significantly improved DEXA scores in osteoporosis patients. DEXA score's precision and sensitivity in quantifying impact contribute to effective osteoporosis management, guiding treatment strategies for better outcomes in the Indian population. Further research is warranted to see the long-term effect of TPTD.

Efficacy of generic teriparatide and alendronate in Chinese postmenopausal women with osteoporosis: a prospective study

The efficacy of generic teriparatide in improving BMD at lumbar spine in patients with osteoporosis was similar to that of alendronate. It provided a new choice for osteoporosis treatment in Chinese population.

INTRODUCTION

To determine whether the efficacy of generic teriparatide is noninferior to alendronate for Chinese postmenopausal women with osteoporosis.

METHODS

Eligible patients were randomly assigned (2:1) in a 48-week, open-label design to receive 20 µg sc daily teriparatide or 70 mg oral weekly alendronate. Primary outcome was percentage change in BMD at the lumbar spine from baseline to 48 weeks and was assessed for non-inferiority. The same outcome was further assessed for superiority as a secondary endpoint.

RESULTS

Three hundred ninety-one and 196 participants were randomly assigned to the teriparatide or alendronate group, of whom 379 and 194 receiving at least one dose of teriparatide and alendronate treatment were eligible for the efficacy analysis. Teriparatide was non-inferior to alendronate for BMD change at lumbar spine (treatment difference: 0.7%, 95% CI: - 0.3 to 1.7%), which excluded the predefined non-inferiority margin of - 1.5%. However, teriparatide was not statistically superior to alendronate in improving BMD at lumbar spine (P = 0.169). At 48 weeks, changes in BMD at total hip were - 1.0% and 2.2% in teriparatide and alendronate group, respectively (P < 0.001). The incidence of new fracture showed no statistical difference between groups (P = 0.128). Serum P1NP and β-CTX levels significantly increased in the teriparatide group and markedly decreased in alendronate group (all P < 0.001 vs baseline). The adverse events (AEs) and serious AEs were more common in the teriparatide group than in the alendronate group, which were mainly teriparatide-related hypercalcemia, elevated alkaline phosphatase or parathyroid hormone, dizziness, and arthralgia.

CONCLUSIONS

Teriparatide was not inferior to alendronate in increasing BMD at lumbar spine in Chinese postmenopausal women, and they achieved these effects through different mechanisms.

Teriparatide improves pain-related behavior and prevents bone loss in ovariectomized mice

PURPOSE

The aim of this study was to examine the inhibitory effect of teriparatide (TPTD) on pain and on bone loss in ovariectomized (OVX) mice. The mechanism of osteoporotic pain in OVX mice was evaluated through an examination of pain-related behavior as well as immunohistochemical examinations.

METHODS

Eight-week-old female ddY mice were OVX and assigned to one of three groups: (1) OVX mice treated with vehicle (OVX), (2) OVX mice treated with teriparatide (OVX-TPTD), or (3) SHAM-operated mice treated with vehicle (SHAM). Starting immediately after surgery, vehicle or TPTD was injected subcutaneously. After a 4-week treatment, mechanical sensitivity was tested using von Frey filaments. The proximal tibial metaphyses were analyzed three-dimensionally by microcomputed tomography (μCT). Calcitonin gene-related peptide (CGRP) and transient receptor potential channel vanilloid 1 (TRPV1) expressions in L3-5 dorsal root ganglion (DRG) neurons were examined using immunohistochemistry.

RESULTS

Ovariectomy induced bone loss and mechanical hyperalgesia in the hind limbs with upregulation of CGRP and TRPV1 expressions in DRG neurons innervating the hind limbs. Bone loss was prevented more effectively in the OVX-TPTD mice than in the OVX mice. Furthermore, mechanical hyperalgesia and upregulation of CGRP and TRPV1 expressions were significantly lower in the OVX-TPTD mice than in the OVX mice.

CONCLUSION

TPTD treatment prevented ovariectomy-induced bone loss and ovariectomy-induced mechanical hyperalgesia in hind limbs, and it suppressed CGRP and TRPV1 expressions in DRG neurons. These results suggest that TPTD is useful for the treatment of osteoporotic pain in postmenopausal women.

Prevention of bone loss and improvement of pain-related behavior in hind limb-unloaded mice by administration of teriparatide and bisphosphonate

OBJECTIVES

There are few reports on the comparison between teriparatide (PTH) and bisphosphonate (BP) in terms of osteoporosis pain-related behavior and immunohistochemical findings. The aims of this study were to evaluate skeletal pain associated with osteoporosis and to examine the inhibitory effect of PTH and BP on pain and bone loss in hind limb-unloaded (HU) mice. The mechanism of osteoporotic pain in HU mice was evaluated by examining pain-related behavior and immunohistochemical findings. The effects of PTH and alendronate (ALN), a potent osteoclast inhibitor, on these parameters were also assessed.

METHODS

Eight-week-old male ddY mice were tail-suspended for 2 weeks and assigned to four groups: hind limb-loaded (HL) mice with only tail suspension treated with vehicle; HU mice with tail suspension treated with vehicle; HU mice treated with PTH; and HU mice treated with ALN. Starting immediately after reloading, vehicle, PTH, or ALN was injected subcutaneously. After a 2-week treatment, mechanical sensitivity was examined using von Frey filaments. Bilateral hind limbs were removed for micro-computed tomography, immunohistochemical analysis, and messenger RNA (mRNA) expression analysis.

RESULTS

HU mice with tail suspension developed bone loss and mechanical hyperalgesia in the hind limbs. The HU mice showed an increased osteoclasts and sclerostin-positive cells in the hind limb bone. Furthermore, PTH and ALN both prevented HU-induced bone loss and mechanical hyperalgesia in the osteoporotic animal models. Histological examination of the hind limb bone revealed that, similar to ALN, PTH inhibited the osteoclasts and sclerostin-positive cells. The mRNA levels of TNFα and IL-6 tended to decrease with ALN or PTH treatment compared with those without any treatment.

CONCLUSIONS

Treatment with PTH as well as BP prevented bone loss, mechanical hyperalgesia, osteoclast increase, and osteocyte increase. Similar to BP, the inhibitory effect of PTH on osteoclasts might contribute to the improvement of skeletal pain.

Teriparatide relieves ovariectomy-induced hyperalgesia in rats, suggesting the involvement of functional regulation in primary sensory neurons by PTH-mediated signaling

Clinical studies have reported that teriparatide (TPTD), a human parathyroid hormone analog, reduces back pain in osteoporotic patients. However, the mechanistic insights of this pharmacological action remain elusive. This study investigated the antinociceptive effect of TPTD mainly on primary sensory neurons in ovariectomized (OVX) rats. The plantar test showed thermal hyperalgesia in the OVX rats, which was significantly, but not fully, recovered immediately after the initial TPTD administration. The von Frey test also demonstrated reduced withdrawal threshold in the OVX rats. This was partially recovered by TPTD. Consistently, the number and size of spinal microglial cells were significantly increased in the OVX rats, while TPTD treatment significantly reduced the number but not size of these cells. RNA sequencing-based bioinformatics of the dorsal root ganglia (DRG) demonstrated that changes in neuro-protective and inflammatory genes were involved in the pharmacological effect of TPTD. Most neurons in the DRG expressed substantial levels of parathyroid hormone 1 receptor. TPTD treatment of the cultured DRG-derived neuronal cells reduced the cAMP level and augmented the intracellular calcium level as the concentration increased. These findings suggest that TPTD targets neuronal cells as well as bone cells to exert its pharmacological action.

Efficacy and safety of recombinant human parathyroid hormone (1-34) are similar to those of alendronate in the treatment of postmenopausal osteoporosis

The study evaluates efficacy and safety of recombinant human parathyroid hormone (1-34) [rhPTH (1-34)] and alendronate (ALN) in the treatment of postmenopausal osteoporosis.Totally 65 postmenopausal women with osteoporosis were divided into 2 groups. PTH group received daily subcutaneous injection of rhPTH (1-34), and ALN group were treated orally with ALN per week. Bone mineral density (BMD) of lumbar spine (1-4), femoral neck, and total hip, serum levels of calcium, phosphorus, total cholesterol, triglyceride, alkaline phosphatase (ALP), N-terminal propeptide of type I collagen (PINP), and C-telopeptide of type I collagen (CTX) were tested before treatment and at week 24 and 48 after treatment. Serum levels of vascular endothelial growth factor (VEGF) and platelet-derived growth factor-BB (PDGF-BB) were measured before treatment and at week 48 after treatment.The rhPTH (1-34) increased BMD of lumbar spine (1-4), but decreased BMD of femoral neck and total hip at week 48 after treatment. By contrast, ALN enhanced BMD of lumbar spine (1-4) and femoral neck, but reduced BMD of total hip at week 48 after treatment. In PTH group, serum levels of PINP, ALP, and β-CTX were significantly elevated above baseline at week 24 and 48 after treatment. Treatment with ALN decreased levels of PINP, ALP, and β-CTX compared with baseline at week 24 and 48 after treatment. rhPTH (1-34) and ALN significantly decreased levels of PDGF-BB, but not levels of VEGF. rhPTH (1-34) increased levels of calcium, phosphorus and triglyceride, but decreased levels of total cholesterol. ALN increased levels of calcium and triglyceride, but reduced levels of phosphorus and total cholesterol. rhPTH (1-34) and ALN were safe in the treatment of postmenopausal osteoporosis.The study demonstrates that efficacy of rhPTH (1-34) on BMD of lumbar spine (1-4) is similar to that of alendronate in the treatment of postmenopausal osteoporosis. The effect of rhPTH (1-34) on BMD of femoral neck or total hip is weaker than that of ALN. In addition, rhPTH (1-34) increases BMD of lumbar spine (1-4) maybe by raising serum levels of VEGF, but reduces BMD of femoral neck and total hip maybe by decreasing serum levels of PDGF-BB.

Administration frequency as well as dosage of PTH are associated with development of cortical porosity in ovariectomized rats

To investigate whether the administration frequency of parathyroid hormone (PTH) is associated with the development of cortical porosity, this study established 15 dosage regimens of teriparatide [human PTH(1–34), TPTD] with four distinct concentrations and four distinct administration frequencies of TPTD to 16-week-old ovariectomized rats. Our analyses demonstrated that the bone mineral density, mechanical properties, and bone turnover were associated with the total amount of TPTD administered. Our observations further revealed that the cortical porosity was markedly developed as a result of an increased administration frequency with a lower concentration of total TPTD administration in our setting, although the highest concentration also induced cortical porosity. Deconvolution fluorescence tiling imaging on calcein-labeled undecalcified bone sections also demonstrated the development of cortical porosity to be closely associated with the bone site where periosteal bone formation took place. This site-specific cortical porosity involved intracortical bone resorption and an increased number and proximity of osteocytic lacunae, occasionally causing fused lacunae. Taken together, these findings suggested the involvement of local distinctions in the rate of bone growth that may be related to the site-specific mechanical properties in the development of cortical porosity induced by frequent and/or high doses of TPTD.

Osteoporosis: a discussion on the past 5 years

PURPOSE OF THE REVIEW

The purposes of this study are to examine the literature within the past 5 years regarding osteoporosis and offer a discussion on new topics and controversies.

RECENT FINDINGS

Patient compliance with therapy remains an issue. The effectiveness of Vitamin D and calcium are being called into question Atypical femur fractures have been associated with bisphosphonate and denosumab use. Treatment is both surgical and pharmaceutical. A multidisciplinary approach to osteoporotic fractures is important and having some form of fracture liaison service (FLS) improves the efficacy of osteoporotic care and decreases secondary fractures. Screening for osteoporosis remains low. Ultrasound may be cost-effective for diagnosis. Understanding of osteoporosis has come a long way in the medical community, but the translation to the lay community has lagged behind. Patients often take a laissez-faire attitude toward osteoporosis that can affect compliance. Information read by patients often focuses on complications, such as atypical femur fractures and myocardial infarctions. It is essential for providers to be able to discuss these issues with patients. Newer medications and more cost-effective diagnostic tests exist, but availability may be limited. FLS are effective, but the most cost-effective model for therapy still eludes us. Areas for further investigation include FLS models, the effectiveness of vitamin supplementation, and more ubiquitous and cost-effective diagnostic tools.

Synthesis and in vitro bone cell activity of analogues of the cyclohexapeptide dianthin G

The cyclohexapeptide natural product dianthin G promotes osteoblast (bone-forming cell) proliferation in vitro at nanomolar concentrations, and is therefore considered a promising candidate for the treatment of osteoporosis. An N(α)-methyl amide bond scan of dianthin G was performed to probe the effect of modifying amide bonds on osteoblast proliferation. In addition, to provide greater structural diversity, a series of dicarba dianthin G analogues was synthesised using ring closing metathesis. Dianthin G and one novel dicarba analogue increased the number of human osteoblasts and importantly they did not increase osteoclast (bone-resorbing cell) differentiation in bone marrow cells.