Parkinson's disease and osteoporosis: basic and clinical implications

Antioxidant, Osteogenic, and Neuroprotective Effects of Homotaurine in Aging and Parkinson's Disease Models

Aging is associated with the accumulation of cellular damage due to oxidative stress and chronic low-grade inflammation, collectively referred to as "inflammaging". This contributes to the functional decline in various tissues, including the brain and skeletal system, which closely interplay. Mesenchymal stem cells (MSCs), known for their regenerative potential and ability to modulate inflammation, offer a promising therapeutic approach to counteract aging-related declines. In this study, we investigated the effects of homotaurine (a small molecule with neuroprotective properties) on MSCs and its effects on osteogenesis. We found that homotaurine treatment significantly reduced reactive oxygen species (ROS) levels, improved MSC viability, and modulated key stress response pathways, including the sestrin 1 and p21 proteins. Furthermore, homotaurine promoted osteogenesis and angiogenesis in zebrafish models by enhancing the expression of critical osteogenesis-associated genes, such as those coding for β-catenin and Runt-related transcription factor 2 (Runx2), and increasing the levels of the kinase insert domain receptor-like angiogenesis marker in aged zebrafish. In Parkinson's disease models using patient-specific midbrain organoids with the leucine-rich repeat kinase 2 G2019S mutation, homotaurine treatment enhanced β-catenin expression and reduced ROS levels, highlighting its potential to counteract the oxidative stress and dysfunctional signaling pathways associated with neurodegeneration. Our findings suggest that homotaurine not only offers neuroprotective benefits but also holds promise as a dual-target therapeutic strategy for enhancing both neuronal and bone homeostasis in aging and neurodegenerative diseases.

Analysis of Preventive Effect of Bisphosphonate for Osteoporotic Fracture in Patients with Alzheimer's Disease and Patient Mortality

Background: Alzheimer's disease (AD) is the most common neurodegenerative disease in the older adult population and is often associated with reduced physical activity. Reduced activity and mechanical loading subsequently reduce bone mineral density and increase risk of osteoporosis. Bisphosphonates (BPs) offer preventative effects on osteoporotic fractures in the general population, but their effects on patients with AD are less known. This study aimed to assess the impact of BPs on osteoporotic fractures and survival in patients with AD. Methods: In this nationwide retrospective cohort study, 43,469 patients from the Korea National Health Insurance Service database between 2004 and 2018 were included. All patients were diagnosed with AD and subsequently diagnosed with osteoporosis. Continuous use of BPs was defined as having prescriptions for BP medications one year after the diagnosis of osteoporosis. Propensity score matching paired 12,519 BP users with 12,518 non-users for post-fracture survival analysis. Results: Continuous use of BPs showed a significant preventative effect on the Cox regression model [hazard ratio (HR), 0.890-0.895; p < 0.001] but not on the logistic regression model. The occurrence of osteoporotic fractures in the hip or spine significantly increased the risk of death [hip, HR, 2.036; 95% confidence interval (CI), 1.789-2.316; p < 0.001; spine, HR, 1.465; CI, 1.305-1.644; p < 0.001]. Conclusions: Continuous use of BPs was associated with reduced occurrence of osteoporotic fractures in patients with AD. Patients with AD showed significantly higher mortality rates after the occurrence of osteoporotic fractures. Further studies with detailed patient characteristics and compliance are warranted.

Unraveling the Bone-Brain Axis: A New Frontier in Parkinson's Disease Research

Parkinson's disease (PD), as a widespread neurodegenerative disorder, significantly impacts patients' quality of life. Its primary symptoms include motor disturbances, tremor, muscle stiffness, and balance disorders. In recent years, with the advancement of research, the concept of the bone-brain axis has gradually become a focal point in the field of PD research. The bone-brain axis refers to the interactions and connections between the skeletal system and the central nervous system (CNS), playing a crucial role in the pathogenesis and pathological processes of PD. The purpose of this review is to comprehensively and deeply explore the bone-brain axis in PD, covering various aspects such as the complex relationship between bone metabolism and PD, the key roles of neurotransmitters and hormones in the bone-brain axis, the role of inflammation and immunity, microRNA (miRNA) functional regulation, and potential therapeutic strategies. Through a comprehensive analysis and in-depth discussion of numerous research findings, this review aims to provide a solid theoretical foundation for a deeper understanding of the pathogenesis of PD and to offer strong support for the development of new treatment methods.

Causal effects of Parkinson's disease on the risk of osteoporosis: A two-sample Mendelian randomization study

Employing a two-sample Mendelian randomization (MR) analysis, we aimed to investigate the potential causal effect of Parkinson disease (PD) on osteoporosis. We conducted an in-depth MR analysis by leveraging extensive genome-wide association study datasets from the International Parkinson Disease Genomics Consortium and the Genetic Factors for Osteoporosis Consortium. We meticulously selected instrumental variables based on strict criteria, including significance thresholds, linkage disequilibrium, and the exclusion of confounding single-nucleotide polymorphisms. Our investigation utilized diverse MR methods, including inverse variance weighted, MR Egger regression, weighted median, and MR-PRESSO, to robustly evaluate the causal relationship. Our comprehensive analysis revealed noteworthy associations between PD and distinct measures of bone mineral density (BMD) (forearm BMD, femoral neck BMD, lumbar spine BMD). Specifically, the inverse variance weighted method underscored potential significant relationships between PD and forearm BMD (P = .037; odds ratio [OR], 1.04; 95% confidence interval [CI], 1.00-1.09), femoral neck BMD (P = .034; OR, 1.02; 95% CI, 1.00-1.05), and lumbar spine BMD (P = .043; OR, 1.03; 95% CI, 1.00-1.06). The consistency of results across various methods and sensitivity analyses indicated both robustness and minimal pleiotropy concerns. Through a two-sample MR approach, this study establishes a plausible causal relationship between PD and decreased BMD. The outcomes underscore the urgency of targeted interventions to mitigate bone loss and manage osteoporosis in individuals with PD.

The Brain-Gut-Bone Axis in Neurodegenerative Diseases: Insights, Challenges, and Future Prospects

Neurodegenerative diseases are global health challenges characterized by the progressive degeneration of nerve cells, leading to cognitive and motor impairments. The brain-gut-bone axis, a complex network that modulates multiple physiological systems, has gained increasing attention owing to its profound effects on the occurrence and development of neurodegenerative diseases. No comprehensive review has been conducted to clarify the triangular relationship involving the brain-gut-bone axis and its potential for innovative therapies for neurodegenerative disorders. In light of this, a new perspective is aimed to propose on the interplay between the brain, gut, and bone systems, highlighting the potential of their dynamic communication in neurodegenerative diseases, as they modulate multiple physiological systems, including the nervous, immune, endocrine, and metabolic systems. Therapeutic strategies for maintaining the balance of the axis, including brain health regulation, intestinal microbiota regulation, and improving skeletal health, are also explored. The intricate physiological interactions within the brain-gut-bone axis pose a challenge in the development of effective treatments that can comprehensively target this system. Furthermore, the safety of these treatments requires further evaluation. This review offers a novel insights and strategies for the prevention and treatment of neurodegenerative diseases, which have important implications for clinical practice and patient well-being.

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.

Hyperglycemic microenvironment compromises the homeostasis of communication between the bone-brain axis by the epigenetic repression of the osteocalcin receptor, Gpr158 in the hippocampus

Diabetes mellitus (DM) is a chronic metabolic disease, mainly characterized by increased blood glucose and insulin dysfunction. In response to the persistent systemic hyperglycemic state, numerous metabolic and physiological complications have already been well characterized. However, its relationship to bone fragility, cognitive deficits and increased risk of dementia still needs to be better understood. The impact of chronic hyperglycemia on bone physiology and architecture was assessed in a model of chronic hyperglycemia induced by a single intraperitoneal administration of streptozotocin (STZ; 55 mg/kg) in Wistar rats. In addition, the bone-to-brain communication was investigated by analyzing the gene expression and methylation status of genes that encode the main osteokines released by the bone [Fgf23 (fibroblast growth factor 23), Bglap (bone gamma-carboxyglutamate protein) and Lcn2 (lipocalin 2) and their receptors in both, the bone and the brain [Fgfr1 (fibroblast growth factor receptor 1), Gpr6A (G-protein coupled receptor family C group 6 member A), Gpr158 (G protein-coupled receptor 158) and Slc22a17 (Solute carrier family 22 member 17)]. It was observed that chronic hyperglycemia negatively impacted on bone biology and compromised the balance of the bone-brain endocrine axis. Ultrastructural disorganization was accompanied by global DNA hypomethylation and changes in gene expression of DNA-modifying enzymes that were accompanied by changes in the methylation status of the osteokine promoter region Bglap and Lcn2 (lipocalin 2) in the femur. Additionally, the chronic hyperglycemic state was accompanied by modulation of gene expression of the osteokines Fgf23 (fibroblast growth factor 23), Bglap (bone gamma-carboxyglutamate protein) and Lcn2 (lipocalin 2) in the different brain regions. However, transcriptional regulation mediated by DNA methylation was observed only for the osteokine receptors, Fgfr1(fibroblast growth factor receptor 1) in the striatum and Gpr158 (G protein-coupled receptor 158) in the hippocampus. This is a pioneer study demonstrating that the chronic hyperglycemic state compromises the crosstalk between bone tissue and the brain, mainly affecting the hippocampus, through transcriptional silencing of the Bglap receptor by hypermethylation of Gpr158 gene.

Total knee arthroplasty in patients with Parkinson's disease: A systematic review and meta-analysis protocol

BACKGROUND

Parkinson's disease (PD) patients have been shown to have various musculoskeletal problems, the postoperative outcomes of total knee arthroplasty procedure might be less predictable if performed on a patient who has PD. We conducted a protocol for systematic review and meta-analysis to evaluate the functional outcomes, activity levels, mortalities, implant survival rates, and complications of total knee arthroplasty in patients with PD.

METHODS

This study follows the guideline of the preferred reporting items for systematic reviews and meta-analyses protocols and has been registered on the International Prospective Register of Systematic Reviews with CRD42022375885. Two independent reviewers will search for databases including PubMed, Embase, Cochrane Library website, ClinicalTrials.gov databases, Chinese National Knowledge Infrastructure Database, Wanfang database, and VIP database using the search strategies recommended by the Cochrane Back Review Group. The RevMan 5.3 software (Cochrane Collaboration, Oxford, UK) will be used to conduct the meta-analyses.

RESULTS

The results of this systematic review will be published in a peer-reviewed journal.

CONCLUSION

This study may provide evidence for the clinical application of total knee arthroplasty in patients with PD.

Height and nigral neuron density in Parkinson's disease

Background

The dopaminergic system modulates growth hormone secretion and previous results have suggested a link between short stature and an increased risk of Parkinson’s disease (PD).

Methods

In 36 Lewy body spectrum disease (LBD) cases (PD = 22) and 19 controls, nigral TH-positive neuron densities were measured postmortem from midbrain sections and corrected with the Abercrombie method. Body measurements were collected from autopsies or patient records. Our aim was to investigate the possible relationship between height and the density of neurons in the substantia nigra pars compacta (SNc).

Results

SNc neuron density (n/mm²) had an inverse association with height, (R² = 0.317, p < 0.0001) in patients. The association was not explained by weight, age, sex, brain weight, medication, or disease motor severity. The association was also separately observed in patients with PD (n = 22), but not in subjects who died without diagnosed neurological diseases.

Conclusions

Individual adult height may be connected to nigral neuron numbers in patients with LBDs, including PD.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Linking COVID-19 and Parkinson's disease: Targeting the role of Vitamin-D

COVID-19 pandemic has a major effect on world health, particularly on individuals suffering from severe diseases or old aged persons. Various case studies revealed that COVID-19 might increase the progression of Parkinson's disease (PD). Coxsackievirus, dengue virus Epstein-Barr virus, hepatitis C virus, Japanese encephalitis, Western equine encephalomyelitis virus, West Nile virus, and human immunodeficiency virus have all been linked to the development of transient or permanent parkinsonism, owing to the induction of neuroinflammation/hypoxic brain injury with structural/functional damage within the basal ganglia. Coronavirus mainly infects the alveolar cells and may lead to acute respiratory distress syndrome. SARS-CoV-2 invades cells via the ACE2 receptor, which is widely expressed in the central nervous system, where the virus may precipitate or accelerate dementia. SARS-CoV-2 could enter the central nervous system directly by the olfactory/vagus nerves or through the bloodstream. Here, we talked about the importance of this viral infection in terms of the CNS as well as its implications for people with Parkinson's disease; anosmia & olfaction-related impairments in COVID-19 & PD patients. And, also discussed the role of vitamin D to sustain the progression of Parkinson's disease and the COVID-19; regular vitamin D3 consumption of 2000-5000 IU/day may reduce the risk and severity of COVID-19 in parkinsonian patients.