Catharanthine tartrate ameliorates osteoclastogenesis by destabilizing HIF-1α

AUTHORS

Luqiong Cai, Chenxin Yu, Binli Zhao, Qihang Wu, Haibo Liang, Meng Zhou, Jiansen Miao, Jiangtao Luo, Jiake Xu, Haiming Jin, Youjin Pan

ABSTRACT

With the aging population, postmenopausal osteoporosis (PMOP), clinically manifested by reduced bone density, weakened skeletal strength, and compromised skeletal microstructure, has become the most prevalent type. The decline in estrogen levels fosters oxidative stress and osteoclastogenesis, which significantly enhance the activity of osteoclasts. Current treatments prefer to adopt relevant strategies to inactivate osteoclasts but come with unavoidable side effects. In our study, Catharanthine Tartrate (CAT), a derivative of the alkaloid catharanthine found in Catharanthus roseus, promised to be an effective therapy for PMOP. CAT inhibited RANKL-induced osteoclast differentiation and bone resorption in vitro. Moreover, CAT inhibited osteoclast activity by enhancing the ubiquitination-mediated proteasomal degradation of HIF-1α, which reduced oxidative stress and subsequently suppressed osteoclast activity. The inhibitory effects of CAT on osteoclast function and oxidative stress were reversed by DMOG, a known inhibitor of HIF-1α degradation. Next, an in vivo mouse experiment using the Ovariectomized (OVX) model to induce osteoporosis indicated that CAT enhanced bone mass density, bone structure, and bone remodeling. Our findings revealed that CAT inhibits PMOP through facilitating HIF-1α ubiquitination and degradation, suggesting a promising therapeutic approach for this disorder.

Dimeric R25CPTH(1–34) activates the parathyroid hormone-1 receptor in vitro and stimulates bone formation in osteoporotic female mice

AUTHORS

Minsoo Noh, Xiangguo Che, Xian Jin, Dong-Kyo Lee, Hyun-Ju Kim, Doo Ri Park, Soo Young Lee, Hunsang Lee, Thomas J Gardella, Je-Yong Choi, Sihoon Lee

ABSTRACT

Osteoporosis, characterized by reduced bone density and strength, increases fracture risk, pain, and limits mobility. Established therapies of parathyroid hormone (PTH) analogs effectively promote bone formation and reduce fractures in severe osteoporosis, but their use is limited by potential adverse effects. In the pursuit of safer osteoporosis treatments, we investigated R25CPTH, a PTH variant wherein the native arginine at position 25 is substituted by cysteine. These studies were prompted by our finding of high bone mineral density in a hypoparathyroidism patient with the R25C homozygous mutation, and we explored its effects on PTH type-1 receptor (PTH1R) signaling in cells and bone metabolism in mice. Our findings indicate that R25CPTH(1–84) forms dimers both intracellularly and extracellularly, and the synthetic dimeric peptide, R25CPTH(1–34), exhibits altered activity in PTH1R-mediated cyclic AMP (cAMP) response. Upon a single injection in mice, dimeric R25CPTH(1–34) induced acute calcemic and phosphaturic responses comparable to PTH(1–34). Furthermore, repeated daily injections increased calvarial bone thickness in intact mice and improved trabecular and cortical bone parameters in ovariectomized (OVX) mice, akin to PTH(1–34). The overall results reveal a capacity of a dimeric PTH peptide ligand to activate the PTH1R in vitro and in vivo as PTH, suggesting a potential path of therapeutic PTH analog development.

Aflatoxin B1 contamination reduces the saponins content and anti-osteoporosis efficacy of the traditional medicine Radix Dipsaci

AUTHORS

Shuqin Lu, Qingsong Yuan, Lulu Wang, Dapeng Su, Min Hu, Lanping Guo, Chuanzhi Kang, Tao Zhou, Jinqiang Zhang

ABSTRACT

Ethnopharmacological relevance

The Radix Dipsaci, a traditional Chinese medicine with a history spanning over 2000 years in China, is widely recognized for its hepatorenal tonic properties, musculoskeletal fortifying effects, fracture healing capabilities, and its frequent application in the treatment of osteoporosis. Like many traditional Chinese herbal medicines, preparations from Radix Dipsaci are at risk of contamination by harmful mycotoxins such as aflatoxin B1.

Aims of the study

This study aims to evaluate the impact of aflatoxin B1 contamination on Radix Dipsaci in terms of changes in quality, efficacy of anti-osteoporosis and hepatorenal toxicity.

Materials and methods

The contamination rates and levels of major mycotoxins were determined in 45 batches of Radix Dipsaci samples using UPLC-MS/MS analysis. The total saponin content and the levels of akebia saponin D in Radix Dipsaci and its decoctions were evaluated through high-performance liquid chromatography (HPLC) analysis. Differences in secondary metabolites between samples without any mycotoxin contamination (N-RD) and those contaminated solely by aflatoxin B1 (AFB1-RD) were compared using metabolomics sequencing and analysis. The anti-osteoporotic efficacy of Radix Dipsaci contaminated with aflatoxin B1 was assessed in a murine model of retinoic acid-induced osteoporosis by quantifying bone mineral content and bone mineral density using dual-energy X-ray absorptiometry. Additionally, the hepatorenal toxicity of Radix Dipsaci contaminated with aflatoxin B1 was evaluated using hematoxylin-eosin staining and enzyme-linked immunosorbent assay (ELISA).

Results

The results indicated that aflatoxin B1 (AFB1) was the most frequently detected mycotoxin, found in 37.7% of the Radix Dipsaci samples. AFB1 contamination significantly altered the secondary metabolites of Radix Dipsaci. Specifically, there was a notable decrease in the levels of total saponins and akebia saponin D in the AFB1-contaminated samples, which exhibited a negative correlation with the levels of AFB1 contamination. However, the administration of a water decoction from AFB1-contaminated Radix Dipsaci did not result in significant improvements in bone mineral density, bone mineral salt content, the trabecular number, trabecular area, proportion of trabecular bone volume/tissue volume and trabecular separation in an osteoporosis mouse model. Additionally, we observed that approximately 16.04% of AFB1 could migrate from the raw herbs into the decoction, leading to hepatocyte and kidney cell damage, as well as increased levels of the oxidative stress molecule malondialdehyde and pro-inflammatory cytokines in the liver and kidney tissues of the osteoporosis model mice.

Conclusion

In summary, Radix Dipsaci is highly susceptible to mycotoxin contamination, particularly aflatoxin B1. The contamination of Radix Dipsaci with AFB1 not only impacts their saponin content and anti-osteoporosis effect but also induces hepatotoxicity and nephrotoxicity.

Estrogen deficiency induces changes in bone matrix bound water that do not closely correspond with bone turnover

AUTHORS

Corinne E. Metzger, Peter Olayooye, Landon Y. Tak, Oli Culpepper, Alec N. LaPlant, Peter Jalaie, Pearl-Marie Andoh, Wikum Bandara, Olivia N. Reul, Andrew A. Tomaschke, Rachel K. Surowiec

ABSTRACT

Postmenopausal osteoporosis, marked by estrogen deficiency, is a major contributor to osteoporotic fractures, yet early prediction of fractures in this population remains challenging. Our goal was to explore the temporal changes in bone-specific inflammation, oxidative stress, bone turnover, and bone-matrix water, and their relationship with estrogen deficiency-induced modifications in bone structure and mechanical properties. Additionally, we sought to determine if emerging clinically translatable imaging techniques could capture early bone modifications prior to standard clinical imaging.

Two-month-old female Sprague Dawley rats (n = 48) underwent ovariectomy (OVX, n = 24) or sham operations (n = 24). A subgroup of n = 8 rats per group was sacrificed at 2-, 5-, and 10-weeks post-surgery to assess the temporal relationships of inflammation, oxidative stress, bone turnover, bone matrix water, mechanics, and imaging outcomes.

OVX rats exhibited higher body weight compared to sham rats at all time points. By 5-weeks, OVX animals showed elevated markers of inflammation and oxidative stress in cortical bone, which persisted throughout the study, while cortical bone formation rate did not differ from sham until 10-weeks. DXA outcomes did not reveal differences between OVX and sham at any time point. Bound water, assessed using ultrashort echo time magnetic resonance imaging (UTE MRI), was lower in OVX at the earliest time point (2-weeks) and reduced again at 10-weeks with no difference at 5-weeks.

These data demonstrate that bound water assessment using novel UTE MRI technology was lower at the earliest time point following OVX. However, no temporal relationship with bone turnover, inflammation, or oxidative stress was observed at the time points assessed in this study. These findings underscore both the increased need to understand bone hydration changes and highlight the usefulness of UTE MRI for non-invasive bone hydration measurements.

Apoptotic Vesicles Derived from Dental Pulp Stem Cells Promote Bone Formation through the ERK1/2 Signaling Pathway

AUTHORS

Kunkun Yang, Yuan Zhu, Yuzi Shao, Yuhe Jiang, Lei Zhu, Yaoshan Liu, Ping Zhang, Yunsong Liu, Xiao Zhang, Yongsheng Zhou

ABSTRACT

Osteoporosis is a common degenerative bone disease. The treatment of osteoporosis remains a clinical challenge in light of the increasing aging population. Human dental pulp stem cells (DPSCs), a type of mesenchymal stem cells (MSCs), are easy to obtain and have a high proliferation ability, playing an important role in the treatment of osteoporosis. However, MSCs undergo apoptosis within a short time when used in vivo; therefore, apoptotic vesicles (apoVs) have attracted increasing attention. Currently, the osteogenic effect of DPSC-derived apoVs is unknown; therefore, this study aimed to determine the role of DPSC-derived apoVs and their potential mechanisms in bone regeneration. We found that MSCs could take up DPSC-derived apoVs, which then promoted MSC osteogenesis in vitro. Moreover, apoVs could increase the trabecular bone count and bone mineral density in the mouse osteoporosis model and could promote bone formation in rat cranial defects in vivo. Mechanistically, apoVs promoted MSC osteogenesis by activating the extracellular regulated kinase (ERK)1/2 signaling pathway. Consequently, we propose a novel therapy comprising DPSC-derived apoVs, representing a promising approach to treat bone loss and bone defects.

Differences in bone histomorphometry between White postmenopausal women with and without atypical femoral fracture after long-term bisphosphonate therapy

AUTHORS

Shijing Qiu, Ruban Dhaliwal, George Divine, Elizabeth Warner, Sudhaker D Rao

ABSTRACT

Bone histomorphometric endpoints in transilial biopsies may be associated with an increased risk of atypical femoral fracture (AFF) in patients with osteoporosis who take antiresorptives, including bisphosphonates (BPs). One way to test this hypothesis is to evaluate bone histomorphometric endpoints in age-, gender-, and treatment time-matched patients who either had AFF or did not have AFF. In this study, we performed transiliac bone biopsies in 52 White postmenopausal women with (n = 20) and without (n = 32) AFFs, all of whom had been treated for osteoporosis continuously with alendronate for 4–17 yr. Despite the matched range of treatment duration (4–17 yr), AFF patients received alendronate for significantly longer time (10.7 yr) than non-AFF patients (8.0 yr) (P = .014). Bone histomorphometric endpoints reflecting microstructure and turnover were assessed in cancellous, intracortical, and endocortical envelopes from transilial biopsy specimens obtained from BP-treated patients 3–6 mo after AFF and from non-AFF patients with similar age-, gender-, and range of BP treatment duration. However, in both cancellous and intracortical envelopes, AFF patients had significantly lower wall thickness (W.Th) and higher osteoclast surface (Oc.S/BS) than non-AFF patients. In addition, AFF patients had significantly higher eroded surface (ES/BS) only in the intracortical envelope. None of the dynamic variables related to bone formation and turnover differed significantly between the groups. In conclusion, in the ilium of BP-treated patients with osteoporosis, AFF patients have lower thickness of superficial bone (lower W.Th) of the cancellous and cortical envelopes than non-AFF patients. AFF and non-AFF patients have a similar bone turnover rate in the ilium. Furthermore, in this population, as in previous work, AFF is more likely to occur in BP-treated patients with longer treatment duration.