Fingolimod suppresses bone resorption in female patients with multiple sclerosis

Bone loss and fracture in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

People with multiple sclerosis (PwMS) exhibit reduced bone mineral density (BMD) across several anatomical regions. Studies have indicated that PwMS are at a heightened risk of fractures due to decreased BMD and increased prevalence of osteopenia and osteoporosis. This study aimed to investigate the prevalence and risk of osteopenia, osteoporosis, and fracture among PwMS.

METHODS

Relevant studies were identified through comprehensive searches of databases (PubMed/MEDLINE, Scopus, Embase, and Web of Science) from January 1, 2000, to January 21, 2024. R software version 4.4.0 and random-effects models were employed to estimate the pooled prevalence, odds ratio (OR), and risk ratio (RR) of osteopenia, osteoporosis, and fracture among PwMS, along with their respective 95 % confidence intervals (CIs).

RESULTS

From a total of 2039 articles, 51 studies with 1,503,785 PwMS met our inclusion criteria. The pooled prevalence of osteopenia, osteoporosis, and overall fracture among PwMS was 41.41 % (95 % CI: 36.14% to 46.69 %, I2=97 %), 14.21 % (95 % CI: 10.75 % to 17.68 %, I2=99 %), and 12.84 % (95 % CI: 8.49 % to 17.19 %, I2 = 100 %), respectively. The likelihood of osteopenia (OR=2.02, 95 % CI: 1.46 to 2.8, p-value<0.01, I2=17 %) and osteoporosis (OR=1.71, 95 % CI: 1.27 to 2.31, p-value<0.01, I2=74 %), as well as the probability of overall fracture (RR=1.86, 95 % CI: 1.61 to 2.14, p-value<0.01, I2=74 %) were significantly higher in PwMS than healthy controls (HCs).

CONCLUSION

PwMS were at a substantially increased risk of developing osteopenia (2-fold), osteoporosis (1.7-fold), and overall fractures (1.9-fold). Well-designed studies are needed to explore these associations further.

Screening for osteoporosis in people with MS: A new risk score

BACKGROUND

Due to the demographic development and improved treatment options, the role of comorbidities is of increasing importance in the medical care of people with MS (pwMS). A higher risk of osteoporosis is well known in chronic autoimmune diseases, and is also described in MS. While there are several screening guidelines in the elderly or in patients with rheumatoid arthritis, there are no generally accepted recommendations when to perform bone mineral testing in pwMS under the age of 65 years. We aimed to determine risk factors of osteoporosis in pwMS and to develop a risk score which can be applied in daily clinical routine.

METHODS

Densitometry (hip and lumbar spine) was performed in 159 pwMS aged ≤65 years and in 81 age- and sex-matched healthy controls (HC). Osteoporosis was defined according to WHO criteria as a bone density 2.5 standard deviation or more below the mean of young adults. Risk factors were identified by logistic regression analysis.

RESULTS

Osteoporosis occurred more frequently in postmenopausal pwMS and male pwMS as compared to HC. Besides age, sex, menopausal status in females, body-mass-index and smoking, a higher degree of disability - as assessed by the Expanded Disability Status Scale - was identified as MS specific risk factor for osteoporosis, whereas the cumulative glucocorticoid dose was not associated with osteoporosis risk. Based on these risk factors, we developed an MS-specific risk score which allows to estimate the individual probability of osteoporosis.

CONCLUSION

This risk score enables individual screening recommendation for pwMS and, subsequently, early prevention of osteoporosis which probably should result in reduction of fractures and morbidity.

The role of sphingosine-1-phosphate in bone remodeling and osteoporosis

Osteoporosis is a systemic bone disease that affects more than 200 million people worldwide and is caused by the disruption of the equilibrium between osteoclastic bone resorption and osteoblastic bone formation. Sphingosine-1-phosphate (S1P) is a natural, bioactive sphingolipid that has been shown to play a major role in cardiovascular and immunological pathologies by regulating biological and cellular processes, including migration, differentiation, proliferation and survival. Recent studies also suggest a central role for S1P in bone diseases, including osteoporosis; however, the effects of S1P, particularly in bone metabolism, remain to be further elucidated. In this review, we summarize the available literature on the role of S1P in bone metabolism with a focus on osteoporosis. On the cellular level, S1P acts as an osteoclast-osteoblast coupling factor to promote osteoblast proliferation and bone formation. Moreover, the recruitment of osteoclast precursors to resorption sites is regulated by the interplay of S1P gradients and S1P receptor expression. From a clinical perspective, increasing evidence suggests that systemically elevated S1P blood levels may serve as an independent risk factor for osteoporosis-related fractures. Taken together, S1P signaling is a potential therapeutic target and may serve as a novel biomarker in patients with systemic bone disease.

Hdac3 regulates bone modeling by suppressing osteoclast responsiveness to RANKL

Hdac3 is a lysine deacetylase that removes acetyl groups from histones and additional proteins. Although Hdac3 functions within mesenchymal lineage skeletal cells are defined, little is known about Hdac3 activities in bone-resorbing osteoclasts. In this study we conditionally deleted Hdac3 within Ctsk-expressing cells and examined the effects on bone modeling and osteoclast differentiation in mice. Hdac3 deficiency reduced femur and tibia periosteal circumference and increased cortical periosteal osteoclast number. Trabecular bone was likewise reduced and was accompanied by increased osteoclast number per trabecular bone surface. We previously showed that Hdac3 deacetylates the p65 subunit of the NF-κB transcriptional complex to decrease DNA-binding and transcriptional activity. Hdac3-deficient osteoclasts demonstrate increased K310 NF-κB acetylation and NF-κB transcriptional activity. Hdac3-deficient osteoclast lineage cells were hyper-responsive to RANKL and showed elevated ex vivo osteoclast number and size and enhanced bone resorption in pit formation assays. Osteoclast-directed Hdac3 deficiency decreased cortical and trabecular bone mass parameters, suggesting that Hdac3 regulates coupling of bone resorption and bone formation. We surveyed a panel of osteoclast-derived coupling factors and found that Hdac3 suppression diminished sphingosine-1-phosphate production. Osteoclast-derived sphingosine-1-phosphate acts in paracrine to promote bone mineralization. Mineralization of WT bone marrow stromal cells cultured with conditioned medium from Hdac3-deficient osteoclasts was markedly reduced. Expression of alkaline phosphatase, type 1a1 collagen, and osteocalcin was also suppressed, but no change in Runx2 expression was observed. Our results demonstrate that Hdac3 controls bone modeling by suppressing osteoclast lineage cell responsiveness to RANKL and coupling to bone formation.

Sphingosine-1-phosphate (S1P) receptors: Promising drug targets for treating bone-related diseases

Sphingosine-1-phosphate (S1P) is a natural bioactive lipid molecule and a common first or second messenger in the cardiovascular and immune systems. By binding with its receptors, S1P can serve as mediator of signalling during cell migration, differentiation, proliferation and apoptosis. Although the predominant role of S1P in bone regeneration has been noted in many studies, this role is not as well-known as its roles in the cardiovascular and immune systems. In this review, we summarize previous research on the role of S1P receptors (S1PRs) in osteoblasts and osteoclasts. In addition, S1P is regarded as a bridge between bone resorption and formation, which brings hope to patients with bone-related diseases. Finally, we discuss S1P and its receptors as therapeutic targets for treating osteoporosis, inflammatory osteolysis and bone metastasis based on the biological effects of S1P in osteoclastic/osteoblastic cells, immune cells and tumour cells.

The role of sphingosine 1-phosphate metabolism in bone and joint pathologies and ectopic calcification

Sphingolipids display important functions in various pathologies such as cancer, obesity, diabetes, cardiovascular or neurodegenerative diseases. Sphingosine, sphingosine 1-phosphate (S1P), and ceramide are the central molecules of sphingolipid metabolism. Sphingosine kinases 1 and 2 (SK1 and SK2) catalyze the conversion of the sphingolipid metabolite sphingosine into S1P. The balance between the levels of S1P and its metabolic precursors ceramide and sphingosine has been considered as a switch that could determine whether a cell proliferates or dies. This balance, also called « sphingolipid rheostat », is mainly under the control of SKs. Several studies have recently pointed out the contribution of SK/S1P metabolic pathway in skeletal development, mineralization and bone homeostasis. Indeed, SK/S1P metabolism participates in different diseases including rheumatoid arthritis, spondyloarthritis, osteoarthritis, osteoporosis, cancer-derived bone metastasis or calcification disorders as vascular calcification. In this review, we will summarize the most important data regarding the implication of SK/S1P axis in bone and joint diseases and ectopic calcification, and discuss the therapeutic potential of targeting SK/S1P metabolism for the treatment of these pathologies.

Intravital multiphoton microscopy as a novel tool in the field of immunopharmacology

Intravital microscopy with multiphoton excitation is a recently developed optical imaging technique for deep tissue imaging without fixation or sectioning, which permits examination of fundamental concepts regarding the dynamic nature of cells under physiological and pathological conditions in living animals. This novel technique also offers exciting opportunities for pharmacological research by providing new platforms for the study of cellular dynamics in response to drugs in vivo. Moreover, fluorescent chemical probes for functional or molecular analysis in single cells in vivo play important roles in pharmacology. For example, we have recently revealed the pharmacodynamic actions of different biological agents for the treatment of rheumatoid arthritis (RA) in vivo by directly visualizing drug-induced cellular behaviors and functions of osteoclasts on bone surfaces. This review focuses on the principles and advantages of intravital imaging for the dissection of pharmacological mechanisms, and discusses how such imaging can contribute to the drug development process, introducing recent trials that evaluated the in vivo pharmacological effects of various agents.