Pathophysiological implications of actin-free Gc-globulin concentration changes in blood plasma and cerebrospinal fluid collected from patients with Alzheimer's disease and other neurological disorders

Vitamin D binding protein in psychiatric and neurological disorders: Implications for diagnosis and treatment

Vitamin D binding protein (VDBP) serves as a key transporter protein responsible for binding and delivering vitamin D and its metabolites to target organs. VDBP plays a crucial part in the inflammatory reaction following tissue damage and is engaged in actin degradation. Recent research has shed light on its potential role in various diseases, leading to a growing interest in understanding the implications of VDBP in psychiatric and neurological disorders. The purpose of this review was to provide a summary of the existing understanding regarding the involvement of VDBP in neurological and psychiatric disorders. By examining the intricate interplay between VDBP and these disorders, this review contributes to a deeper understanding of underlying mechanisms and potential therapeutic avenues. Insights gained from the study of VDBP could pave the way for novel strategies in the diagnosis, prognosis, and treatment of psychiatric and neurological disorders.

Vitamin D-binding protein in plasma microglia-derived extracellular vesicles as a potential biomarker for major depressive disorder

No well-established biomarkers are available for the clinical diagnosis of major depressive disorder (MDD). Vitamin D-binding protein (VDBP) is altered in plasma and postmortem dorsolateral prefrontal cortex (DLPFC) tissues of MDD patients. Thereby, the role of VDBP as a potential biomarker of MDD diagnosis was further assessed. Total extracellular vesicles (EVs) and brain cell-derived EVs (BCDEVs) were isolated from the plasma of first-episode drug-naïve or drug-free MDD patients and well-matched healthy controls (HCs) in discovery (20 MDD patients and 20 HCs) and validation cohorts (88 MDD patients and 38 HCs). VDBP level in the cerebrospinal fluid (CSF) from chronic glucocorticoid-induced depressed rhesus macaques or prelimbic cortex from lipopolysaccharide (LPS)-induced depressed mice and wild control groups was measured to evaluate its relationship with VDBP in plasma microglia-derived extracellular vesicles (MDEVs). VDBP was significantly decreased in MDD plasma MDEVs compared to HCs, and negatively correlated with HAMD-24 score with the highest diagnostic accuracy among BCDEVs. VDBP in plasma MDEVs was decreased both in depressed rhesus macaques and mice. A positive correlation of VDBP in MDEVs with that in CSF was detected in depressed rhesus macaques. VDBP levels in prelimbic cortex microglia were negatively correlated with those in plasma MDEVs in depressed mice. The main results suggested that VDBP in plasma MDEVs might serve as a prospective candidate biomarker for MDD diagnosis.

Multi-Omics, an Integrated Approach to Identify Novel Blood Biomarkers of Alzheimer's Disease

The metabolomic and proteomic basis of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is poorly understood, and the relationships between systemic abnormalities in metabolism and AD/MCI pathogenesis is unclear. This study compared the metabolomic and proteomic signature of plasma from cognitively normal (CN) and dementia patients diagnosed with MCI or AD, to identify specific cellular pathways and new biomarkers altered with the progression of the disease. We analysed 80 plasma samples from individuals with MCI or AD, as well as age- and gender-matched CN individuals, by utilising mass spectrometry methods and data analyses that included combined pathway analysis and model predictions. Several proteins clearly identified AD from the MCI and CN groups and included plasma actins, mannan-binding lectin serine protease 1, serum amyloid A2, fibronectin and extracellular matrix protein 1 and Keratin 9. The integrated pathway analysis showed various metabolic pathways were affected in AD, such as the arginine, alanine, aspartate, glutamate and pyruvate metabolism pathways. Therefore, our multi-omics approach identified novel plasma biomarkers for the MCI and AD groups, identified changes in metabolic processes, and may form the basis of a biomarker panel for stratifying dementia participants in future clinical trials.

Aberrations of biochemical indicators in amyotrophic lateral sclerosis: a systematic review and meta-analysis

Accumulating evidence has suggested that the pathological changes in amyotrophic lateral sclerosis (ALS) are not only confined to the central nervous system but also occur in the peripheral circulating system. Here, we performed a meta-analysis based on the PubMed, EMBASE, EBSCO, and CNKI databases, to find out biochemical indicators associated with energy metabolism, iron homeostasis, and muscle injury that are altered in ALS patients and their correlations with ALS phenotypes. Forty-six studies covering 17 biochemical indicators, representing 5454 ALS patients and 7986 control subjects, were included in this meta-analysis. Four indicators, including fasting blood glucose level (weighted mean difference [WMD] = 0.13, 95% CI [0.06–0.21], p = 0.001), serum ferritin level (WMD = 63.42, 95% CI [48.12–78.73], p < 0.001), transferrin saturation coefficient level (WMD = 2.79, 95% CI [1.52–4.05], p < 0.001), and creatine kinase level (WMD = 80.29, 95% CI [32.90–127.67], p < 0.001), were significantly higher in the ALS patients, whereas the total iron-binding capacity (WMD = − 2.42, 95% CI [− 3.93, − 0.90], p = 0.002) was significantly lower in ALS patients than in the control subjects. In contrast, the other 12 candidates did not show significant differences between ALS patients and controls. Moreover, pooled hazard ratios (HR) showed significantly reduced survival (HR = 1.38, 95% CI [1.02–1.88], p = 0.039) of ALS patients with elevated serum ferritin levels. These findings suggest that abnormalities in energy metabolism and disruption of iron homeostasis are involved in the pathogenesis of ALS. In addition, the serum ferritin level is negatively associated with the overall survival of ALS patients.

Vitamin D Measurement, the Debates Continue, New Analytes Have Emerged, Developments Have Variable Outcomes

The demand for measurement of vitamin D metabolites for clinical diagnosis and to advance our understanding of the role of vitamin D in human health has significantly increased in the last decade. New developments in technologies employed have enabled the separation and quantification of additional metabolites and interferences. Also, developments of immunoassays have changed the landscape. Programmes and materials for assay standardisation, harmonisation and the expansion of the vitamin D external quality assurance scheme (DEQAS) with the provision of target values as measured by a reference measurement procedure have improved standardisation, quality assurance and comparability of measurements. In this article, we describe developments in the measurement of the commonly analysed vitamin D metabolites in clinical and research practice. We describe current analytical approaches, discuss differences between assays, their origin, and how these may be influenced by physiological and experimental conditions. The value of measuring metabolites beyond 25 hydroxyvitamin D (25(OH)D), the marker of vitamin D status, in routine clinical practice is not yet confirmed. Here we provide an overview of the value and application of the measurement of 1,25 dihydroxyvitamin D, 24,25 dihydroxyvitamin D and free 25OHD in the diagnosis of patients with abnormalities in vitamin D metabolism and for research purposes.

Multiple Sclerosis Patients Show Lower Bioavailable 25(OH)D and 1,25(OH)2D, but No Difference in Ratio of 25(OH)D/24,25(OH)2D and FGF23 Concentrations

Vitamin D (VitD) insufficiency is common in multiple sclerosis (MS). VitD has possible anti-inflammatory effects on the immune system. The ratio between VitD metabolites in MS patients and the severity of the disease are suggested to be related. However, the exact effect of the bone-derived hormone fibroblast-growth-factor-23 (FGF23) and VitD binding protein (VDBP) on this ratio is not fully elucidated yet. Therefore, the aim is to study differences in total, free, and bioavailable VD metabolites and FGF23 between MS patients and healthy controls (HCs). FGF23, vitD (25(OH)D), active vitD (1,25(OH)₂D), inactive 24,25(OH)D, and VDBP were measured in 91 MS patients and 92 HCs. Bioavailable and free concentrations were calculated. No difference in FGF23 (p = 0.65) and 25(OH)D/24.25(OH)₂D ratio (p = 0.21) between MS patients and HCs was observed. Bioavailable 25(OH)D and bioavailable 1.25(OH)₂D were lower (p < 0.01), while VDBP concentrations were higher in MS patients (p = 0.02) compared with HCs, specifically in male MS patients (p = 0.01). In conclusion, FGF23 and 25(OH)D/24.25(OH)₂D did not differ between MS patients and HCs, yet bioavailable VitD concentrations are of potential clinical relevance in MS patients. The possible immunomodulating role of VDBP and gender-related differences in the VD-FGF23 axis in MS need further study.