An Antioxidant Sesquiterpene Inhibits Osteoclastogenesis Via Blocking IPMK/TRAF6 and Counteracts OVX-Induced Osteoporosis in Mice

Excessive bone resorption induced by increased osteoclast activity in postmenopausal women often causes osteoporosis. Although the pharmacological treatment of osteoporosis has been extensively developed, a safer and more effective treatment is still needed. Here, we found that curcumenol (CUL), an antioxidant sesquiterpene isolated from Curcuma zedoaria, impaired receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in vitro, whereas the osteoblastogenesis of MC3T3-E1 cells was not affected. We further demonstrated that CUL treatment during RANKL-induced osteoclastogenesis promotes proteasomal degradation of TRAF6 by increasing its K48-linked polyubiquitination, leading to suppression of mitogen-activated protein kinases (MAPKs) and NF-κB pathways and the production of reactive oxygen species (ROS). We also showed that inositol polyphosphate multikinase (IPMK) binds with TRAF6 to reduce its K48-linked polyubiquitination under RANKL stimulation. Concurrently, IPMK deficiency inhibits osteoclast differentiation. The binding between IPMK and TRAF6 blocked by CUL treatment was found in our study. Finally, we confirmed that CUL treatment prevented ovariectomy (OVX)-induced bone loss in mice. In summary, our study demonstrates that CUL could impair the stability of TRAF6 enhanced by IPMK and suppress excessive osteoclast activity in estrogen-deficient mice to treat osteoporosis. © 2021 American Society for Bone and Mineral Research (ASBMR).

HX-1171, a Novel Nrf2 Activator, Induces NQO1 and HMOX1 Expression

HX-1171 (1-O-hexyl-2,3,5-trimethylhydroquinone) is a novel synthesized vitamin E derivative, which reportedly has positive effects on various diseases and conditions, such as liver fibrosis, hepatic cirrhosis, and cancer. In this study, we analyzed the transcriptional activity induced by HX-1171. Results from reverse transcription polymerase chain reaction and promoter assays reveal that HX-1171 increased the expression of NQO1 and HMOX1, encoding antioxidant-related enzymes, in A549 human lung epithelial cells. The activity of nuclear factor-E2-related factor (Nrf2), a key transcriptional factor for antioxidative enzymes, was examined in HX-1171-treated cells. Confocal microscopy and Western blotting showed that HX-1171 effectively induced the nuclear translocation and transcriptional activity of Nrf2. We conclude that HX-1171, a novel Nrf2 activator, may be a promising therapeutic agent for oxidative stress-induced diseases. J. Cell. Biochem. 118: 3372-3380, 2017. © 2017 Wiley Periodicals, Inc.

A phenolic acid phenethyl urea derivative protects against irradiation-induced osteoblast damage by modulating intracellular redox state

Because irradiation may cause osteoradionecrosis, antioxidant supplementation is often used to suppress irradiation-mediated injury. This study examined whether a synthetic phenethyl urea compound, (E)-1-(3,4-dihydroxyphenethyl)-3-(3,4-dihydroxystyryl)urea (DPDS-U), prevents irradiation-mediated cellular damage in MC3T3-E1 osteoblastic cells. A relatively high dose of irradiation (>4 Gy) decreased cell viability and proliferation and induced DNA damage and cell cycle arrest at the G(2)/M phase with the attendant increase of cyclin B1. Irradiation with 8 Gy induced intracellular reactive oxygen species (ROS) production and lipid peroxidation, and reduced glutathione content and superoxide dismutase activity in the cells. These events were significantly suppressed by treatment with 200 µM DPDS-U or 5 mM N-acetyl cysteine (NAC). DPDS-U or irradiation alone significantly increased heme oxygenase-1 (HO-1) expression and nuclear factor E2 p45-related factor-2 (Nrf2) nuclear translocation. Interestingly, pretreatment with DPDS-U facilitated irradiation-induced activation of the Nrf2/HO-1 pathway. The potential of DPDS-U to mediate HO-1 induction and protect against irradiation-mediated cellular damage was almost completely attenuated by transient transfection with Nrf2-specific siRNA or treatment with a pharmacological HO-1 inhibitor, zinc protoporphyrin IX. Additional experiments revealed that DPDS-U induced a radioprotective mechanism that differs from that induced by NAC through activation of Nrf2/HO-1 signaling. Collectively, our data suggest that DPDS-U-induced radioprotection is due to its dual function as an antioxidant to remove directly excessive intracellular ROS and as a prooxidant to stimulate intracellular redox-sensitive survival signal.

Prevention of nephrotoxicity induced by cyclosporine-A: role of antioxidants

Cyclosporine A (CsA) is a powerful immunosuppressive drug used to prevent allograft rejection after organ transplantation as well as in human and veterinary medicine. Unfortunately, its use is hampered by its nephrotoxic effects. The mechanisms of CsA-induced hypertension and nephrotoxicity are not clear, but several studies suggest the possible involvement of free radicals. In this review we have summarized the effect of some antioxidants that we have used in the recent years, in combination with CsA, to better understand the exact mechanism of action of CsA and to try to open new perspectives in the treatment of CsA nephrotoxicity.

Low levels of serum uric Acid increase the risk of low bone mineral density in young male patients with ankylosing spondylitis

OBJECTIVE

Uric acid (UA) has antiosteoporotic effects in postmenopausal women. This study investigated the association between serum UA levels and bone mineral density (BMD) in young male patients with ankylosing spondylitis (AS).

METHODS

One hundred fifty patients who fulfilled the modified New York criteria for the classification of AS were analyzed. All patients were male and under 50 years of age. BMD, serum UA concentrations, clinical variables, and radiographic progression were assessed. The associations between UA and BMD at the lumbar spine and hip were evaluated using multiple linear regression analysis. Multivariate logistic regression analyses were performed to identify risk factors associated with low BMD.

RESULTS

Mean serum UA concentration in the 150 patients with AS was 5.5 ± 1.3 mg/dl. BMD at the lumbar spine, but not at the total hip and femoral neck, increased with increasing serum UA tertiles (p = 0.033). The significant positive association between serum UA and BMD at the lumbar spine remained after adjustment for confounding factors (β = 0.185, p = 0.014, adjusted R(2) = 0.310). Multiple logistic regression analyses showed that lower UA concentrations (OR 4.02, 95% CI 1.34-12.3) and body mass index and increased erythrocyte sedimentation rate were independently associated with the risk of low BMD.

CONCLUSION

Lower serum UA levels are associated with lower BMD in young male patients with AS. UA may be a novel predictive marker or therapeutic target in patients with AS.

Relation between oxidative stress and climacteric symptoms in early postmenopausal women

OBJECTIVES

To evaluate the relation between climacteric symptoms or other risk factors for cardiovascular disease and oxidative status of postmenopausal women.

METHODS

Cross-sectional investigation performed at the outpatient service for the menopause at the University Hospital, on 50 apparently healthy women in physiological postmenopause. The whole-blood free oxygen radical test (FORT), free oxygen radical defence (FORD), age, months since menopause, weight, body mass index, waist circumference, waist-to-hip ratio, estradiol, lipids, glucose, insulin, insulin resistance (glucose/insulin and HOMA-IR), and fibrinogen were evaluated. The Greene Climacteric Scale with its subscales was used to evaluate climacteric symptoms. The pulsatility index, an index of downstream blood flow resistance, was determined for both the internal carotid artery and the brachial artery.

RESULTS

The waist-to-hip ratio (r = 0.540; p = 0.0001), estradiol (r = 0.548; p = 0.0004) and waist circumference (r = 0.345; p = 0.02) were independently related to blood FORT. The score in the Greene vasomotor subscale was the only parameter independently related to blood FORD (r = 0.554; p = 0.0001). FORT was not related to the artery pulsatility index, while FORD was negatively related to the pulsatility index of both the internal carotid (r = 0.549; p = 0.0001) and the brachial (r = 0.484; p = 0.0001) arteries.

DISCUSSION

In postmenopausal women, abdominal adiposity and hypoestrogenism increase oxidative stress. Climacteric symptoms, particularly vasomotor symptoms, markedly reduce antioxidant defences. Lower antioxidant defences are associated with higher resistance to blood flow in the great arteries. In women early after the menopause, visceral fat, hypoestrogenism and climacteric symptoms may increase the risk for cardiovascular disease.