Bisphosphonates Related Ocular Side Effects: A Case Series and Review of Literature

Micheliolide prevents estrogen deficiency-induced bone loss via inhibiting osteoclast bone resorption

Osteoporosis is one of the major health problems characterized by decreased bone density and increased risk of fractures. Nowadays, the treating strategies against osteoporosis are efficient, but still have some drawbacks. Micheliolide, a guaianolide sesquiterpene lactone isolated from Michelia compressa and Michelia champac, has been reported to have anti-inflammatory effects. Here, our data suggest that Micheliolide could protect mice from ovariectomy induced bone loss. According to the Micro-CT scan and histomorphometry quantification data, Micheliolide treatment inhibits excessive osteoclast bone resorption without affecting bone formation in estrogen deficiency mice. Consistently, our data suggest that Micheliolide could inhibit osteoclastogenesis in vitro. Additionally, we confirmed that Micheliolide inhibits osteoclasts formation via inhibiting P38 MAPK signaling pathway, and P79350 (a P38 agonist) could rescue this effect. In summary, our data suggest that Micheliolide could ameliorate estrogen deficiency-induced bone loss via attenuating osteoclastogenesis. Hence, Micheliolide could be used as a novel anti-resorptive agent against osteoporosis.

The Mechanotransduction Signaling Pathways in the Regulation of Osteogenesis

Bones are constantly exposed to mechanical forces from both muscles and Earth's gravity to maintain bone homeostasis by stimulating bone formation. Mechanotransduction transforms external mechanical signals such as force, fluid flow shear, and gravity into intracellular responses to achieve force adaptation. However, the underlying molecular mechanisms on the conversion from mechanical signals into bone formation has not been completely defined yet. In the present review, we provide a comprehensive and systematic description of the mechanotransduction signaling pathways induced by mechanical stimuli during osteogenesis and address the different layers of interconnections between different signaling pathways. Further exploration of mechanotransduction would benefit patients with osteoporosis, including the aging population and postmenopausal women.

Ocular Side Effects of Bisphosphonates: A Review of Literature

In rare cases, bisphosphonates are well established to cause ocular inflammation, presenting as uveitis, episcleritis, scleritis, orbital inflammation, and/or conjunctivitis. Some reports of bisphosphonate-associated neuro-ophthalmic complications also exist. We identified 101 reports in the literature relating to bisphosphonate-associated ocular complications. In a great majority of cases, symptoms resolve after discontinuation of the drug and anti-inflammatory treatment. Many cases recur if rechallenged with the same bisphosphonate. First-generation nonamino bisphosphonates, including clodronate and etidronate, are not associated with ocular inflammation. Only 2nd- and 3rd-generation amino bisphosphonates, including pamidronate, alendronate, risedronate, ibandronate, and zoledronate are associated with these complications. The mechanism of bisphosphonate-induced ocular inflammation may be related to activation of γ/δ T cells or M1 macrophages. Intravenous forms, such as pamidronate and zoledronate, tend to have higher rates and faster onset of ocular inflammation, generally presenting within days of infusion. In oral bisphosphonates, such as alendronate and risedronate, these complications present with more sporadic timing. Rates of complications are also higher when bisphosphonates are used for malignancy, as doses tend to be higher compared with doses for osteoporosis.

Astragaloside positively regulated osteogenic differentiation of pre-osteoblast MC3T3-E1 through PI3K/Akt signaling pathway

BACKGROUND

Osteoporosis is a widespread chronic disease characterized by low bone density. There is currently no gold standard treatment for osteoporosis. The aim of this study was to explore the role and mechanism of Astragaloside on osteogenic differentiation of MC3T3-E1 cells.

METHODS

MC3T3-E1 cells were divided into control and different dose of Astragaloside (10, 20, 40, 50, and 60 μg/ml). Then, ALP and ARS staining were performed to identify the effects of Astragaloside for early and late osteogenic capacity of MC3T3-E1 cells, respectively. Real-time PCR and western blot were performed to assess the ALP, OCN, and OSX expression. PI3K/Akt signaling pathway molecules were then assessed by Western blot. Finally, PI3K inhibitor, LY294002, was implemented to assess the mechanism of Astragaloside in promoting osteogenic differentiation of MC3T3-E1 cells.

RESULTS

Astragaloside significantly increased the cell viability than the control group. Moreover, Astragaloside enhanced the ALP activity and calcium deposition than the control groups. Compared with the control group, Astragaloside increased the ALP, OCN, and OSX expression in a dose-response manner. Western blot assay further confirmed the real-time PCR results. Astragaloside could significantly increase the p-PI3K and p-Akt expression than the control group. LY294002 partially reversed the promotion effects of Astragaloside on osteogenic differentiation of MC3T3-E1 cells. LY294002 partially reversed the promotion effects of Astragaloside on ALP, OCN, and OSX of MC3T3-E1 cells.

CONCLUSION

The present study suggested that Astragaloside promoted osteogenic differentiation of MC3T3-E1 cells through regulating PI3K/Akt signaling pathway.