Bone microarchitecture and bone mineral density in multiple sclerosis

Short-Term Risk Factors for Bone Loss in Multiple Sclerosis: A Prospective Study and Literature Review

BACKGROUND

Reduced bone mass and increased osteoporosis risk are common in people with multiple sclerosis (pwMS). The aim of the study was to identify risk factors for short-term bone loss in MS.

METHODS

This prospective study included 139 pwMS (ages 18-65). Baseline data included demographics, body-mass index, physical activity, smoking, menopause status, 25-hydroxy vitamin D levels, and history of glucocorticoid use. Bone mineral density (BMD) was measured at baseline and after 2 years using dual-energy X-ray absorptiometry (DXA) for the lumbar spine and hip. Disability worsening was assessed by the Expanded Disability Status Scale (EDSS). Additionally, a literature review was conducted on longitudinal data regarding BMD in MS.

RESULTS

Over the 2-year follow-up period, significant BMD loss was observed in the hip (baseline g/cm2: median 0.898; IQR 0.808-1.014; 2-year follow-up: 0.882; 0.784-1.01; p < 0.001), but not in the lumbar spine. Overall, 101 (73.1%) experienced hip BMD loss, with a median decrease of 3.5%. Patients with disability worsening had an approximately 7-times higher risk of bone loss compared to those without disability worsening (p = 0.013). PwMS with fractures during the follow-up period had significantly lower hip BMD (0.760, 0.546-0.890 vs. 0.909, 0.828-1.015; p = 0.024), a higher EDSS score (4.4, 2.8-5.8 vs. 2.0, 1.0-4.0 vs. p = 0.026), and were older (59, 46-62 vs. 47, 37-54; p = 0.030) compared to those without fractures.

CONCLUSION

Disability worsening was identified as a risk factor for BMD loss. These findings underscore the need for active monitoring of pwMS with disability worsening to prevent bone loss and, thus, to reduce fracture risk.

Bone involvement in the early stages of Parkinson's disease: a case-control study

OBJECTIVE

To evaluate the qualitative and quantitative alterations of bone tissue in patients with early-stage Parkinson's disease (PD) and to measure the associations between bone mineral density (BMD), trabecular bone score (TBS) and physical performance.

METHODS

This case-control study enrolled patients with early-stage PD and age-matched controls. BMDs for the left femoral neck (L-FN) and lumbar spine (LS) were measured. Bone microarchitecture for the LS was determined using TBS. Muscle performance was assessed using the short physical performance battery (SPPB). Patients and controls were stratified in two groups based on the SPPB score: a poor performance group (SPPB score ≤8) and high performance group (SPPB > 8).

RESULTS

This study included 26 patients: 13 in the PD group and 13 age-matched controls. The mean ± SD BMD results in the PD group were: L1-L4 BMD = 0.935 ± 0.183 g/cm2; L-FN BMD = 0.825 ± 0.037 g/cm2; with bone microarchitecture degraded in four patients and partially degraded in three patients. TBS was significantly different in the patients with PD stratified according to SPPB. Among the controls, there was a significant difference in body mass index between the two SPPB groups.

CONCLUSION

TBS might identify bone involvement earlier than BMD in the initial stages of PD.

A systematic review of Mendelian randomization studies on multiple sclerosis

Mendelian randomization (MR) is a powerful approach for assessing the causal effect of putative risk factors on an outcome, using genetic variants as instrumental variables. The methodology and application developed in the framework of MR have been dramatically improved, taking advantage of the many public genome-wide association study (GWAS) data. The availability of summary-level data allowed to perform numerous MR studies especially for complex diseases, pinpointing modifiable exposures causally related to increased or decreased disease risk. Multiple sclerosis (MS) is a complex multifactorial disease whose aetiology involves both genetic and non-genetic risk factors and their interplay. Previous observational studies have revealed associations between candidate modifiable exposures and MS risk; although being prone to confounding, and reverse causation, these studies were unable to draw causal conclusions. MR analysis addresses the limitations of observational studies and allows to establish reliable and accurate causal conclusions. Here, we systematically reviewed the studies evaluating the causal effect, through MR, of genetic and non-genetic exposures on MS risk. Among 107 papers found, only 42 were eligible for final evaluation and qualitative synthesis. We found that, above all, low vitamin D levels and high adult body mass index (BMI) appear to be uncontested risk factors for increased MS risk.

A Mixture of Cervus elaphus sibiricus and Glycine max (L.) Merrill Inhibits Ovariectomy-Induced Bone Loss Via Regulation of Osteogenic Molecules in a Mouse Model

Osteoporosis is a metabolic skeletal disease characterized by lowered bone mineral density and quality, which lead to an increased risk of fracture. The aim of this study was to evaluate the anti-osteoporosis effects of a mixture (called BPX) of Cervus elaphus sibiricus and Glycine max (L.) Merrill and its underlying mechanisms using an ovariectomized (OVX) mouse model. BALB/c female mice (7 weeks old) were ovariectomized. From 12 weeks of ovariectomy, mice were administered BPX (600 mg/kg) mixed in a chow diet for 20 weeks. Changes in bone mineral density (BMD) and bone volume (BV), histological findings, osteogenic markers in serum, and bone formation-related molecules were analyzed. Ovariectomy notably decreased the BMD and BV scores, while these were significantly attenuated by BPX treatment in the whole body, femur, and tibia. These anti-osteoporosis effects of BPX were supported by the histological findings for bone microstructure from H&E staining, increased activity of alkaline phosphatase (ALP), but a lowered activity of tartrate-resistant acid phosphatase (TRAP) in the femur, along with other parameters in the serum, including TRAP, calcium (Ca), osteocalcin (OC), and ALP. These pharmacological actions of BPX were explained by the regulation of key molecules in the bone morphogenetic protein (BMP) and mitogen-activated protein kinase (MAPK) pathways. The present results provide experimental evidence for the clinical relevance and pharmaceutical potential of BPX as a candidate for anti-osteoporosis treatment, especially under postmenopausal conditions.

Mendelian randomization analysis of the causal association of bone mineral density and fracture with multiple sclerosis

Multiple sclerosis (MS) is a neurodegenerative disorder and an autoimmune disease. Until now, observational studies have indicated the association of bone mineral density (BMD) and fracture with the risk of MS. However, these studies indicated inconsistent findings. Until now, genome-wide association studies (GWAS) have been conducted in BMD, fracture, and MS, which provide large-scale datasets to investigate the causal association of BMD and fracture with the risk of MS using the Mendelian randomization (MR) study. Here, we performed an MR study to clarify the causal association between BMD/fracture and the risk of MS using large-scale publicly available GWAS datasets from BMD, fracture, and MS. We first evaluated the bidirectional causal effects of BMD and MS. The main analysis method inverse-variance weighted (IVW) showed no significant causal effect of BMD on the risk of MS (β = 0.058, and p = 1.98E-01), and MS on the risk of BMD (β = −0.001, and p = 7.83E-01). We then evaluated the bidirectional causal effects of fracture and MS. However, we only identified a significant causal effect of fracture on the risk of MS using IVW (β = −0.375, p = 0.002), but no significant causal effect of MS on the risk of the fracture using IVW (β = 0.011, p = 2.39E-01). Therefore, our main analysis method IVW only found a significant causal effect of fracture on MS using the threshold for the statistically significant association p < 0.05/4 = 0.0125. Meanwhile, multivariable MR analyses showed that the causal effect of fracture on MS was independent of smoking, drinking, and obesity, but dependent on BMD. In summary, our MR analysis demonstrates that genetically increased fracture may reduce the risk of MS. Our findings should be further verified and the underlying mechanisms should be further evaluated by future studies.

An antagonistic monoclonal anti-Plexin-B1 antibody exerts therapeutic effects in mouse models of postmenopausal osteoporosis and multiple sclerosis

Osteoporosis and multiple sclerosis are highly prevalent diseases with limited treatment options. In light of these unmet medical needs, novel therapeutic approaches are urgently sought. Previously, the activation of the transmembrane receptor Plexin-B1 by its ligand semaphorin 4D (Sema4D) has been shown to suppress bone formation and promote neuroinflammation in mice. However, it is unclear whether inhibition of this receptor–ligand interaction by an anti–Plexin-B1 antibody could represent a viable strategy against diseases related to these processes. Here, we raised and systematically characterized a monoclonal antibody directed against the extracellular domain of human Plexin-B1, which specifically blocks the binding of Sema4D to Plexin-B1. In vitro, we show that this antibody inhibits the suppressive effects of Sema4D on human osteoblast differentiation and mineralization. To test the therapeutic potential of the antibody in vivo, we generated a humanized mouse line, which expresses transgenic human Plexin-B1 instead of endogenous murine Plexin-B1. Employing these mice, we demonstrate that the anti–Plexin-B1 antibody exhibits beneficial effects in mouse models of postmenopausal osteoporosis and multiple sclerosis in vivo. In summary, our data identify an anti–Plexin-B1 antibody as a potential therapeutic agent for the treatment of osteoporosis and multiple sclerosis.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

The utility and limitations of using trabecular bone score with FRAX

PURPOSE OF REVIEW

Trabecular bone score (TBS) is a texture index derived from the lumbar spine dual-energy X-ray absorptiometry which can assess skeletal quality and provide information about fracture risk independent of bone mineral density (BMD). TBS is useful in assessing osteoporotic fracture risk, with lower TBS values associated with increased fracture risk. In this article, we review the current state of TBS, including its utility and limitations in the assessment and management of osteoporosis, with particular emphasis on the recent literature.

RECENT FINDINGS

Ten-year fracture risk assessment using the FRAX tool can be improved through the use of a TBS adjustment. The use of TBS-adjusted FRAX can change management in a modest but significant number of patients, particularly in those close to an intervention threshold. Change in lumbar spine TBS for patients undergoing antiresorptive treatment is not a useful indicator of antifracture effect.

SUMMARY

Lumbar spine TBS provides information complementary to conventional BMD, and has been shown to be clinically useful for enhancing fracture risk prediction.