Vitamin D in the prevention, prediction and treatment of neurodegenerative and neuroinflammatory diseases

Integrating Endocrine, Genomic, and Extra-Skeletal Benefits of Vitamin D into National and Regional Clinical Guidelines

BACKGROUND/OBJECTIVES

Vitamin D is essential for bone health, immune function, and overall well-being. Numerous ecological, observational, and prospective studies, including randomized controlled clinical trials (RCTs), report an inverse association between higher serum 25-hydroxyvitamin D [25(OH)D; calcifediol] levels in various conditions, including cardiovascular disease, metabolic disorders such as diabetes and obesity, susceptibility to infection-related complications, autoimmune diseases, and all-cause mortality.

RESULTS

Vitamin D operates through two distinct systems. The endocrine system comprises the renal tubular cell-derived circulatory calcitriol, which primarily regulates calcium homeostasis and muscular functions. In contrast, intracellularly generated calcitriol in peripheral target cells is responsible for intracrine/paracrine system signaling and calcitriol-vitamin D receptor-mediated genomic effects. Government-appointed committees and health organizations have developed various clinical practice guidelines for vitamin D supplementation and management. However, these guidelines heavily relied on the 2011 Institute of Medicine (IoM) report, which focused solely on the skeletal effects of vitamin D, ignoring other body systems. Thus, they do not represent maintaining good overall health and aspects of disease prevention. Additionally, the IoM report was intended as a public health recommendation for the government and is not a clinical guideline.

DISCUSSION

New country- and regional-specific guidelines must focus on healthy nations through disease prevention and reducing healthcare costs. They should not be restricted to bone effect and must encompass all extra-skeletal benefits. Nevertheless, due to misunderstandings, medical societies and other governments have used faulty IoM report as a foundation for creating vitamin D guidelines. Consequently, they placed disproportionate emphasis on bone health while largely overlooking its benefits for other bodily systems, making current guidelines, including 2024, the Endocrine Society less applicable to the public. As a result, the utility of published guidelines has been significantly reduced for clinical practice and RCTs that designed on bone-centric are generate misleading information and remain suboptimal for public health and disease prevention.

CONCLUSIONS

This review and its recommendations address the gaps in current vitamin D clinical practice guidelines and propose a framework for developing more effective, country and region-specific recommendations that capture the extra-skeletal benefits of vitamin D to prevent multiple diseases and enhance public health.

Associations Between Tinnitus and Systemic Disease in Adolescents: Implications of Vitamin D Deficiency and Anaemia

OBJECTIVES

Tinnitus is one of the irritating symptoms that should be addressed in adolescents. Since tinnitus affects mental health, it is important to treat it. However, identifying the cause of tinnitus is very challenging and the treatment strategies of tinnitus are controversial. The objective of this study was to identify the prevalence of tinnitus in adolescents and systemic diseases as risk factors of adolescent tinnitus to find evidence for new treatment strategies.

MATERIALS AND METHODS

We extracted the subjects and data using the 5th Korea National Health and Nutrition Examination Survey from 2010 to 2012. One thousand five hundred ninety-three adolescents with bilateral normal tympanic membranes and availability of the results of physical, laboratory and audiological examinations, were selected. We evaluated their systemic diseases based on these results and assessed the association of tinnitus with demographic factors, systemic diseases and hearing levels.

RESULTS

The prevalence of tinnitus in Korean adolescents was 21.7%. The hearing level was not associated with tinnitus. Tinnitus was significantly associated with age (p = 0.005), 25(OH)-D level (p = 0.007) and anaemia (p = 0.003). After controlling the other factors, age (p = 0.045), 25(OH)-D level (p = 0.041) and anaemia (p = 0.019) were independently related to tinnitus.

CONCLUSION

Tinnitus in adolescents was significantly associated with age, vitamin D and anaemia. Physicians should consider the higher likelihood of these deficiencies or diseases in adolescent tinnitus patients. Additionally, recognizing these associations may be helpful in developing treatment strategies for adolescent tinnitus.

Is Serum Vitamin D Associated with Depression or Anxiety in Ante- and Postnatal Adult Women? A Systematic Review with Meta-Analysis

BACKGROUND/OBJECTIVES

To collect evidence from studies that explored the associations between serum vitamin D (25[OH]D) concentrations/status and the presence of depressive/anxiety symptoms in the ante- and/or postnatal periods (PROSPERO-CRD42023390895).

METHODS

Studies that assessed serum 25[OH]D concentrations in adult women during the ante/postnatal periods and those that used valid instruments to identify the experience/severity of depressive/anxiety symptoms were included. Independent researchers performed the identification/selection of studies, data extraction, risk of bias (RoB) assessment, and bibliometric analysis steps.

RESULTS

Of the total of 6769 eligible records, 15 cohort studies [high (n = 3), moderate (n = 7), and low (n = 5) RoB], nine cross-sectional studies [moderate (n = 3) and low (n = 6) RoB], and one case-control study [moderate RoB] were included (n = 25). Depression (n = 24) and anxiety (n = 4) symptoms were assessed. A significant difference in antenatal serum 25[OH]D concentrations between the groups of women with and without depression was identified (mean difference: -4.63 ng/mL; 95% confidence interval [95% CI]: -8.88; -0.38). Postnatal serum 25[OH]D concentrations were found to be, on average, -2.36 ng/mL (95% CI: -4.59; -0.14) lower in women with postnatal depression than in those without. Maternal antenatal anxiety was associated with significantly lower concentrations/deficiency of 25[OH]D in only one included study.

CONCLUSIONS

Based on very low/low-quality evidence, it was observed that reduced serum 25[OH]D concentrations in the ante- and postnatal period are associated with the presence of ante- and postnatal depressive symptoms, respectively. Low/deficient antenatal serum 25[OH]D concentrations may not be related to the presence of anxiety symptoms before childbirth. Well-designed longitudinal studies are needed to explore the estimated pooled effect of these associations.

Brain inflammaging in the pathogenesis of late-life depression

Late-life depression (LLD) is a prevalent mental disorder among older adults. Previous studies revealed that many pathologic factors are associated with the onset and development of LLD. However, the precise mechanisms that cause LLD remain elusive. Aging induces chronic inflammatory changes mediated by alterations of immune responses. The chronic systemic inflammation termed "inflammaging" is linked to the etiology of aging-related disorders. Aged microglia induce senescence-associated secretory phenotype (SASP) and transition to M1-phenotype, cause neuroinflammation, and diminish neuroprotective effects. In addition, there is an age-dependent loss of blood-brain barrier (BBB) integrity. As the BBB breakdown can lead to invasion of immune cells into brain parenchyma, peripheral immunosenescence may cause microglial activation and neuroinflammation. Therefore, it is suggested that these mechanisms related to brain inflammaging may be involved in the pathogenesis of LLD. In this review, we described the role of brain inflammaging in LLD. Pharmacologic approaches to prevent brain inflammaging appears to be a promising strategy for treating LLD.

Serum Vitamin D3 as a Potential Biomarker for Neuronal Damage in Smoldering Multiple Sclerosis

Permanent inflammatory demyelinating and neurodegenerative processes lead to neurological disability in patients with multiple sclerosis (MS). The anti-inflammatory properties of vitamin D3 (VitD) are well established, but its role in neurodegeneration is still uncertain. The usefulness of the serum concentration of VitD as a potential biomarker in evaluating brain injury in terms of recently known smoldering MS was under consideration. Methods: We assessed the concentrations of the parameters of brain injury (NF-H, GPAF, S100B, UCHL1) in the cerebrospinal fluid (CSF) of relapsing-remitting (RRMS, n = 123) and progressive MS (PMS, n = 88) patients in the group with normal levels of VitD (VitDn) and in the VitD deficiency group (VitDd). The levels of NF-H and UCHL1 were higher in the group of VitDd compared to VitDn. The higher serum levels of VitD were correlated with lower concentrations of GFAP, NF-H and S100B in the CSF of the whole group of MS patients and in women with MS as opposed to the levels of UCHL1. In men, there were noted negative correlations between the levels of serum VitD and GFAP and NF-H in CSF but not between VitD and S100B and UCHL1. The negative correlations were observed between VitD and the selected parameters of brain injury in MS patients, in women as well as in men. The concentrations of serum VitD together with selected parameters of brain injury in CSF seem to be promising biomarkers of neurodegeneration processes in smoldering MS.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

The neuroprotective effect of vitamin D in Parkinson's disease: association or causation

Parkinson's disease (PD) is a chronic neurodegenerative disease (NDD) due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). PD is characterized by diverse motor symptoms such as rigidity, resting tremors, and bradykinesia, and non-motor symptoms such as cognitive dysfunction and sleep disturbances. Vitamin D (VD), VD receptor (VDR), and VD metabolites are present in the brain and play a role in maintaining the development, differentiation, and functions of the DNs. VDRs exert protective effects against PD neuropathology by modulating functional capacity and DNs neurotransmission in the SN. In virtue of its anti-inflammatory and antioxidant activities, VD could be effective in the prevention and treatment of PD. VD exerts a neuroprotective effect by reducing oxidative stress and mitochondrial dysfunction, and by increasing autophagy and brain-derived neurotrophic factor (BDNF). Low VD serum level is connected with cognitive dysfunction and the development of dementia in PD. The VD-mediated cognitive augmenting effect is interrelated to the safeguarding of synaptic plasticity and modulation of neurotransmitter release. VD deficiency is linked with the severity of olfactory dysfunction which precedes the progression of symptomatic PD. However, the precise role of VD in PD remains unidentified, and there is a conflict about whether treatment with VD can ameliorate PD or not.

Calcitriol attenuates lipopolysaccharide-induced neuroinflammation and depressive-like behaviors by suppressing the P2X7R/NLRP3/caspase-1 pathway

RATIONALE

Microglia-mediated neuroinflammation is a vital hallmark in progression of depression, while calcitriol exerts anti-inflammatory effects in the brain. The activation of the P2X7 receptor has an important link to neuroinflammation. However, it is unclear whether calcitriol treatment exerts anti-inflammatory effects in association with P2X7R activation.

OBJECTIVE

In this study, we assessed the antidepressive and neuroprotective effects of calcitriol on lipopolysaccharide (LPS)-mediated depressive-like behavior, neuroinflammation, and neuronal damage.

METHODS

In in vitro experiments, the BV2 cells were exposed to LPS, and the protective effects of calcitriol were assessed. For in vivo experiment, thirty-two male C57BL/6 mice were divided into four groups of control, calcitriol, LPS and LPS + calcitriol. Calcitriol was administered at 1 µg/kg for 14 days and LPS at 1 mg/kg once every other day for 14 days. The control group mice were given equal volumes of vehicles. All treatments were delivered intraperitoneally.

RESULTS

The in vitro experiments showed calcitriol inhibited the release of inflammatory mediators induced by LPS in BV2 cells. The in vivo experiments revealed that calcitriol alleviated LPS-induced behavioral abnormalities and spatial learning impairments. Moreover, calcitriol treatment reduced the mRNA levels of pro-inflammatory cytokines, while increasing anti-inflammatory cytokine levels in the hippocampus. Our results further revealed that calcitriol administration attenuated LPS-induced microglia activation by suppressing P2X7R/NLRP3/caspase-1 signaling. Moreover, calcitriol inhibited apoptosis of neurons in the hippocampus as evidenced by expression of apoptosis-related proteins and TUNEL assay.

CONCLUSIONS

Collectively, our findings demonstrated that calcitriol exerts antidepressive and neuroprotective effects through the suppression of the P2X7R/NLRP3/caspase-1 pathway both in LPS-induced inflammation models in vitro and in vivo.

The protective role of interaction between vitamin D, sex hormones and calcium in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder that causes disability and paralysis, especially among young adults. Although interactions of several factors, such as viral infections, autoimmunity, genetic and environmental factors, performance a role in the beginning and progression of the disease, the exact cause of MS is unknown to date. Different immune cells such as Th1 and Th17 play an impressive role in the immunopathogenesis of MS, while, regulatory cells such as Th2 and Treg diminish the severity of the illness. Sex hormones have a vital role in many autoimmune disorders, including multiple sclerosis. Testosterone, estrogen and progesterone have various roles in the progress of MS, which higher prevalence of disease in women and more severe in men reveals the importance of sex hormones' role in this disease. Vitamin D after chemical changes in the body, as an active hormone called calcitriol, plays an important role in regulating immune responses and improves MS by modulating the immune system. The optimum level of calcium in the body with vitamin D modulates immune responses and calcium as an essential ion in the body plays a key role in the treatment of autoimmune diseases. The interaction between vitamin D and sex hormones has protective and therapeutic effects against MS and functional synergy between estrogen and calcitriol occurs in disease recovery. Moreover, vitamin D and calcium interact with each other to regulate the immune system and shift them to anti-inflammatory responses.

Effectiveness of Vitamin D on Neurological and Mental Disorders

(1) Background: Mental disorders are conditions that affect a person's cognition, mood, and behaviour, such as depression, anxiety, bipolar disorder, and schizophrenia. In contrast, neurological disorders are diseases of the brain, spinal cord, and nerves. Such disorders include strokes, epilepsy, Alzheimer's, and Parkinson's. Both mental and neurological disorders pose significant global health challenges, impacting hundreds of millions worldwide. Research suggests that certain vitamins, including vitamin D, may influence the incidence and severity of these disorders; (2) Methods: This systematic review examined the potential effects of vitamin D supplementation on various mental and neurological disorders. Evidence was gathered from databases like PubMed, Cochrane, and Google Scholar, including multiple randomized controlled trials comparing vitamin D supplementation to placebo or no treatment for conditions like depression, bipolar disorder, epilepsy, schizophrenia, and neuroinflammation; (3) Results: The findings strongly indicate that vitamin D supplementation may benefit a range of mental health and neurological disorders. The magnitude of the beneficial impact varied by specific disorder, but the overall pattern strongly supports the therapeutic potential of vitamin D on these disorders; (4) Conclusions: This review provides valuable insight into the role vitamin D may play in the management of critical brain-related health issues.

Idiopathic chronic intestinal pseudo-obstruction syndrome is strongly associated with low serum levels of vitamin D

Idiopathic chronic intestinal pseudo-obstruction (CIPO) is associated with intestinal inflammation and malabsorption and may cause serum vitamin D deficiency. We aimed to assess whether there is an association between idiopathic CIPO and serum levels of 25-hydroxy-vitamin D. Consecutive patients with confirmed diagnosis of idiopathic CIPO were prospectively enrolled and matched with healthy controls by gender, age, and BMI. Median serum level of 25-hydroxy-vitamin D of patients with CIPO was compared with that of healthy subjects using the Wilcoxon signed-rank test for matched samples. A total of 35 patients with CIPO and 35 matched healthy subjects were enrolled. All patients with CIPO had a 25-hydroxy-vitamin D deficiency with serum levels <12 ng/ml. The median serum level of vitamin D was significantly lower in patients with CIPO than in healthy controls (5.7 vs. 29.7 ng/ml, P  < 0.0001). Serum level of vitamin D was not associated with gender ( P  = 0.27), age ( P  = 0.22), BMI ( P  = 0.95), high (>10 000 × ml) WBC count ( P  = 0.08), or high (>5 mg/l) C-reactive protein ( P  = 0.87) among patients with CIPO. CIPO seems to be strongly associated with low serum levels of 25-hydroxy-vitamin D.

Associations of vitamin D receptor polymorphisms with risk of Alzheimer's disease, Parkinson's disease, and mild cognitive impairment: a systematic review and meta-analysis

Vitamin D is a lipid soluble steroid hormone, which plays a critical role in the calcium homeostasis, neuronal development, cellular differentiation, and growth by binding to vitamin D receptor (VDR). Associations between VDR gene polymorphism and Alzheimer's disease (AD), Parkinson's disease (PD), and mild cognitive impairment (MCI) risk has been investigated extensively, but the results remain ambiguous. The aim of this study was to comprehensively assess the correlations between four VDR polymorphisms (FokI, BsmI, TaqI, and ApaI) and susceptibility to AD, PD, and MCI. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to determine the relationship of interest. Pooled analyses suggested that the ApaI polymorphism decreased the overall AD risk, and the TaqI increased the overall PD susceptibility. In addition, the BsmI and ApaI polymorphisms were significantly correlated with the overall MCI risk. Stratified analysis by ethnicity further showed that the TaqI and ApaI genotypes reduced the AD predisposition among Caucasians, while the TaqI polymorphism enhanced the PD risk among Asians. Intriguingly, carriers with the BB genotype significantly decreased the MCI risk in Asian descents, and the ApaI variant elevated the predisposition to MCI in Caucasians and Asians. Further studies are need to identify the role of VDR polymorphisms in AD, PD, and MCI susceptibility.

The Non-conventional Effects of Hypovitaminosis D: A Pandemic Even in Sunlight-Rich Countries

The synthesis and absorption of Vitamin D play crucial roles in numerous bodily functions, yet deficiencies persist due to factors like insufficient sunlight exposure and dietary inadequacy. Research underscores the significance of lifestyle elements such as diet, sun exposure, and physical activity in maintaining optimal Vitamin D levels. Strategies aimed at tackling deficiencies emphasize supplementation alongside lifestyle adjustments, especially in regions with abundant sunlight like the Middle East and North Africa (MENA). Despite the abundance of sunshine in the Arab world, there remains a prevalent issue of Vitamin D deficiency. This problem arises from various factors, including cultural practices such as traditional clothing covering most skin areas, which limit sun exposure, and environmental factors like air pollution that reduce UV penetration. Dietary habits and lifestyle choices also contribute to this deficiency. Dealing with the ongoing pandemic requires a focused effort to enhance awareness. While some individuals may recognize common diseases caused by Vitamin D deficiency, such as rickets and osteomalacia, many remain unaware of the broader health risks associated with the condition, including non-skeletal manifestations. Additionally, there is a lack of understanding regarding the numerous hidden benefits of this hormone. Therefore, prioritizing educational initiatives that delve into these aspects is essential to effectively combat the current health crisis. This literature review aims to report both skeletal and extraskeletal consequences of hypovitaminosis and briefly discuss the cause of paradoxical vitamin D deficiency in sunny regions like the MENA. This was done by reviewing pertinent articles published between January 2000 and January 2024, sourced from databases such as PubMed, UpToDate, Scopus, and CINAHL, focusing exclusively on English language literature and using keywords such as "Vitamin D deficiency" and "Extraskeletal manifestations."

'Unpredictable chronic mild stress does not exacerbate memory impairment or altered neuronal and glial plasticity in the hippocampus of middle-aged vitamin D deficient mice'

Vitamin D deficiency is a worldwide health concern, especially in the elderly population. Much remains unknown about the relationship between vitamin D deficiency (VDD), stress-induced cognitive dysfunctions and depressive-like behaviour. In this study, 4-month-old male C57Bl/6J mice were fed with control or vitamin D free diet for 6 months, followed by unpredictable chronic stress (UCMS) for 8 weeks. VDD induced cognitive impairment and reduced grooming behaviour, but did not induce depressive-like behaviour. While UCMS in vitamin D sufficient mice induced expected depressive-like phenotype and impairments in the contextual fear memory, chronic stress did not manifest as an additional risk factor for memory impairments and depressive-like behaviour in VDD mice. In fact, UCMS restored self-care behaviour in VDD mice. At the histopathological level, VDD mice exhibited cell loss in the granule cell layer, reduced survival of newly generated cells, accompanied with an increased number of apoptotic cells and alterations in glial morphology in the hippocampus; however, these effects were not exacerbated by UCMS. Interestingly, UCMS reversed VDD induced loss of microglial cells. Moreover, tyrosine hydroxylase levels decreased in the striatum of VDD mice, but not in stressed VDD mice. These findings indicate that long-term VDD in adulthood impairs cognition but does not augment behavioural response to UCMS in middle-aged mice. While VDD caused cell loss and altered glial response in the DG of the hippocampus, these effects were not exacerbated by UCMS and could contribute to mechanisms regulating altered stress response.

Causal associations between modifiable risk factors and isolated REM sleep behavior disorder: a mendelian randomization study

Objectives

This Mendelian randomization (MR) study identified modifiable risk factors for isolated rapid eye movement sleep behavior disorder (iRBD).

Methods

Genome-wide association study (GWAS) datasets for 29 modifiable risk factors for iRBD in discovery and replication stages were used. GWAS data for iRBD cases were obtained from the International RBD Study Group. The inverse variance weighted (IVW) method was primarily employed to explore causality, with supplementary analyses used to verify the robustness of IVW findings. Co-localization analysis further substantiated causal associations identified via MR. Genetic correlations between mental illness and iRBD were identified using trait covariance, linkage disequilibrium score regression, and co-localization analyses.

Results

Our study revealed causal associations between sun exposure-related factors and iRBD. Utilizing sun protection (odds ratio [OR] = 0.31 [0.14, 0.69], p = 0.004), ease of sunburn (OR = 0.70 [0.57, 0.87], p = 0.001), childhood sunburn occasions (OR = 0.58 [0.39, 0.87], p = 0.008), and phototoxic dermatitis (OR = 0.78 [0.66, 0.92], p = 0.003) decreased iRBD risk. Conversely, a deep skin color increased risk (OR = 1.42 [1.04, 1.93], p = 0.026). Smoking, alcohol consumption, low education levels, and mental illness were not risk factors for iRBD. Anxiety disorders and iRBD were genetically correlated.

Conclusion

Our study does not corroborate previous findings that identified smoking, alcohol use, low education, and mental illness as risk factors for iRBD. Moreover, we found that excessive sun exposure elevates iRBD risk. These findings offer new insights for screening high-risk populations and devising preventive measures.

Adipokines, Vitamin D, and Selected Inflammatory Biomarkers among Parkinson's Disease Patients with and without Dyskinesia: A Preliminary Examination

Parkinson's disease (PD), a widely recognized neurodegenerative disorder, is characterized by a spectrum of symptoms including motor fluctuations and dyskinesia. Neuroinflammation and dysregulation of adipokines are increasingly implicated in the progression of PD. This preliminary study investigated the levels of inflammatory biomarkers and adipokines, namely interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), C-reactive protein (CRP), visfatin, progranulin, and 25(OH)-vitamin D in 52 PD patients, divided equally between those with and without dyskinesia and 26 healthy controls. Significant differences in the levels of IL-6, TNF-α, visfatin, and progranulin were noted between the groups. Patients with dyskinesia exhibited notably higher IL-6 levels compared to controls, and TNF-α was significantly elevated in both PD patient groups relative to the control group. Additionally, visfatin levels were higher in PD patients without dyskinesia as opposed to those with dyskinesia, and progranulin levels were elevated in the non-dyskinetic PD group compared to controls. The findings highlight the potential role of the examined biomarkers in the pathophysiology of PD. Changes in levels of the tested inflammatory biomarkers and adipokines might be associated with Parkinson's disease and its symptoms such as dyskinesia.

Does vitamin D protect or treat Parkinson's disease? A narrative review

Parkinson's disease (PD) is a neurodegenerative brain disease (NBD) developed due to dopaminergic neuron loss in the substantia nigra (SN). Vitamin D (VD), VD receptor (VDR), and VD metabolites are highly expressed in the human brain and play a critical role in maintaining different brain functions. VDRs are highly expressed in the SN that regulates the activity of dopaminergic neurons and synaptic plasticity. VD exerts protective and therapeutic effects against the development of PD by modulating dopaminergic neurons of SN. VD reduces oxidative stress and neuroinflammation in PD because of its anti-inflammatory and antioxidant activities. Different studies revealed the protective effect of VD in the management of PD. However, the potential therapeutic effect of VD in well-established PD remains controversial. Therefore, this review aims to elucidate VD's preventive and therapeutic roles in PD. In conclusion, VD deficiency is associated with increased PD risk, but VD supplementation in well-established PD plays little role.

Dementia, osteoporosis and fragility fractures: Intricate epidemiological relationships, plausible biological connections, and twisted clinical practices

Dementia, osteoporosis, and fragility fractures are chronic diseases, often co-existing in older adults. These conditions pose severe morbidity, long-term disability, and mortality, with relevant socioeconomic implications. While in the research arena, the discussion remains on whether dementia is the cause or the consequence of fragility fractures, healthcare professionals need a better understanding of the interplay between such conditions from epidemiological and physiological standpoints. With this review, we summarized the available literature surrounding the relationship between cognitive impairment, dementia, and both low bone mineral density (BMD) and fragility fractures. Given the strength of the bi-directional associations and their impact on the quality of life, we shed light on the biological connections between brain and bone systems, presenting the main mediators, including gut microbioma, and pathological pathways leading to the dysregulation of bone and brain metabolism. Ultimately, we synthesized the evidence about the impact of available pharmacological treatments for the prevention of fragility fractures on cognitive functions and individuals' outcomes when dementia coexists. Vice versa, the effects of symptomatic treatments for dementia on the risk of falls and fragility fractures are explored. Combining evidence alongside clinical practice, we discuss challenges and opportunities related to the management of older adults affected by cognitive impairment or dementia and at high risk for fragility fracture prevention, which leads to not only an improvement in patient health-related outcomes and survival but also a reduction in healthcare cost and socio-economic burden.

Unprecedented effect of vitamin D3 on T-cell receptor beta subunit and alpha7 nicotinic acetylcholine receptor expression in a 3-nitropropionic acid induced mouse model of Huntington's disease

Introduction

3-NP induction in rodent models has been shown to induce selective neurodegeneration in the striatum followed by the cortex (Brouillet, 2014). However, it remains unclear whether, under such a neurotoxic condition, characterized by neuroinflammation and oxidative stress, the gene expression of the immune resident protein, T-cell receptor beta subunit (TCR-β), α7 nicotinic acetylcholine receptor (α7 nAChRs), the nuclear factor kappa B (NF-κB), inflammatory cytokines (TNF-α and IL-6), and antioxidants (Cat and GpX4) get modulated on Vitamin D3 (VD) supplementation in the central nervous system.

Methods

In the present study, real-time polymerase chain reaction (RT-PCR) was performed to study the expression of respective genes. Male C57BL/6 mice (8-12 weeks) were divided into four groups namely, Group I: Control (saline); Group II: 3-NP induction via i.p (HD); Group III: Vitamin D3 (VD) and Group IV: (HD + VD) (Manjari et al., 2022).

Results

On administration of 500IU/kg/day of VD, HD mice showed a significant reduction in the gene expression of the immune receptor, TCR-β subunit, nuclear factor kappa B (NF-κB), inflammatory cytokines, and key antioxidants, followed by a decrease in the acetylcholinesterase activity.

Conclusion

A novel neuroprotective effect of VD in HD is demonstrated by combating the immune receptor, TCR-β gene expression, antioxidant markers, and inflammatory cytokines. In addition, HD mice on VD administration for 0-15 days showed an enhancement in cholinergic signaling with restoration in α7 nAChRs mRNA and protein expression in the striatum and cortex.

Interplay of Vitamin D, Unfolded Protein Response, and Iron Metabolism in Neuroblastoma Cells: A Therapeutic Approach in Neurodegenerative Conditions

Vitamin D3 (VD) is crucial for various cell functions, including gene regulation, antioxidant defense, and neural health. Neurodegenerative conditions are closely linked to the unfolded protein response (UPR), a mechanism reacting to endoplasmic reticulum (ER) stress. Iron metabolism is intricately associated with UPR and neurodegeneration. This study used SH-SY5Y neuroblastoma cells to investigate the relationship between UPR, iron metabolism, and VD. Different sequences of treatments (pre- and post-treatments) were applied using VD and thapsigargin (Tg), and various methods were used for evaluation, including real-time qPCR, Western blotting, ELISA, and iron content analysis. The findings indicate that VD affects UPR pathways, cytokine release, and iron-related genes, potentially offering anti-inflammatory benefits. It also influences iron transporters and storage proteins, helping to maintain cellular iron balance. Furthermore, pro-inflammatory cytokines like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα) were impacting UPR activation in cells. VD also influenced fractalkine (CX3CL1) gene expression and secretion, suggesting its potential as a therapeutic agent for addressing neuroinflammation and iron dysregulation. This research provides insights into the intricate connections among VD, UPR, and iron metabolism in SH-SY5Y neuroblastoma cells, with implications for future investigations and potential therapeutic approaches in neurodegenerative diseases characterized by UPR dysregulation and iron accumulation.

Vitamin D Insufficiency is Associated with Higher Incidence of Dementia, a Large Community-Based Retrospective Cohort Study

INTRODUCTION

Active metabolite of vitamin D has neuro-immunomodulatory and neuroprotective properties. However, there is still a debate about the potential association between low serum levels of hydroxy-vitamin D and increased risk for dementia.

OBJECTIVES

To determine an association between hypovitaminosis D and dementia for different 25-hydroxyvitamin-D (25(OH)D) serum level cutoffs.

METHODS

Patients were identified utilizing the database of Clalit Health Services (CHS), the largest healthcare provider in Israel. For each subject, all available values of 25(OH)D during the study period, which lasted from 2002 to 2019, were obtained. Rates of dementia were compared across different cutoffs of 25(OH)D levels.

RESULTS

Cohort included 4278 patients, of whom 2454 (57%) were women. The mean age at the beginning of follow-up was 53 (±17). During the 17-year study period, a total of 133 patients (3%) were diagnosed with dementia. In a fully adjusted multivariate analysis, the risk for dementia was almost 2-fold higher in patients with an average of vitamin D insufficiency (<75 nmol/l) measurements (OR = 1.8, 95% C.I. = 1.0-3.2) compared to reference values (≥75 nmol/l). Patients with vitamin D deficiency (<50 nmol/l) demonstrated higher rates of dementia (OR = 2.6, 95% C.I. = 1.4-4.8). In our cohort, patients were diagnosed with dementia at a younger age in the deficiency (77 vs. 81 P-value = 0.05) and the insufficiency groups (77 vs. 81 P-value = 0.05) compared to the reference values (≥75 nmol/l).

CONCLUSION

Insufficient levels of vitamin D are associated with dementia. Dementia is diagnosed at a younger age in patients with insufficient and deficient vitamin D levels.

Impact of 12 Weeks of Vitamin D3 Administration in Parkinson's Patients with Deep Brain Stimulation on Kynurenine Pathway and Inflammatory Status

The current study aimed to investigate whether a 12-week Body Mass Index (BMI)-based (the higher the BMI, the higher the dosage) vitamin D3 administration may affect both the kynurenine pathway (KP) and the inflammatory state in Parkinson's disease (PD) patients with deep brain stimulation (DBS) and may be useful for developing novel therapeutic targets against PD. Patients were randomly assigned to two groups: supplemented with vitamin D3 (VitD, n = 15) and treated with vegetable oil (PL, n = 21). Administration lasted for 12 weeks. The isotope dilution method by LC-MS/MS was applied to measure KP and vitamin D metabolites. Serum concentrations of cytokines such as IL-6 and TNF-α were measured using ELISA kits. After administration, the serum concentration of TNF-α decreased in PD patients with DBS. Moreover, in KP: 3-hydroksykynurenine (3-HK) was increased in the PL group, picolinic acid was decreased in the PL group, and kynurenic acid tended to be higher after administration. Furthermore, a negative correlation between 3-HK and 25(OH)D3 and 24,25(OH)2D3 was noticed. Our preliminary results provide further evidence regarding a key link between the KP substances, inflammation status, and metabolites of vitamin D in PD patients with DBS. These findings may reflect the neuroprotective abilities of vitamin D3 in PD patients with DBS.

Vitamin D deficiency and genetic polymorphisms of vitamin D-associated genes in Parkinson's disease

Parkinson's disease (PD) and vitamin D share a unique link as vitamin D deficiency (VDD) prevails in PD. Thus, an in-depth understanding of vitamin D biology in PD might be crucial for therapeutic strategies emphasising vitamin D. Specifically, explicating the effect of VDD and genetic polymorphisms of vitamin D-associated genes in PD, like VDR (vitamin D receptor) or GC (vitamin D binding protein) may aid the process along with polymorphisms of vitamin D metabolising genes (e.g., CYP2R1 and CYP27A1) in PD. Literature review of single nucleotide polymorphisms (SNPs) related to vitamin D levels [GC (GC1-rs7041 and GC2-rs4588), CYP2R1, CYP24A1 and CYP27B1] and vitamin D function [VDR (FokI - rs2228570 and rs10735810; ApaI - rs7976091, rs7975232BsmI and rs1544410; and TaqI - rs731236)] was conducted to explore their relationship with PD severity globally. VDR-FokI polymorphism was reported to be significantly associated with PD in Hungarian, Chinese and Japanese populations, whereas VDR-ApaI polymorphism was found to affect PD in the Iranian population. However, VDR-TaqI and BsmI polymorphisms had no significant association with PD severity. Conversely, GC1 polymorphisms reportedly affected vitamin D levels without influencing the disease severity. CYP2R1 (excluding rs1993116) was also reportedly linked to clinical manifestations of PD. Genetic polymorphisms might cause VDD despite enough sunlight exposure and vitamin D-rich food intake, enhancing inflammation, there by influencing PD pathophysiology. Knowledge of the polymorphisms associated with VDD appears promising for developing precision vitamin D-dosing therapeutic strategies against PD.

Effect of 12-Week BMI-Based Vitamin D3 Supplementation in Parkinson's Disease with Deep Brain Stimulation on Physical Performance, Inflammation, and Vitamin D Metabolites

Parkinson's disease (PD) is the second most common neurodegenerative disease. To manage motor symptoms not controlled adequately with medication, deep brain stimulation (DBS) is used. PD patients often manifest vitamin D deficiency, which may be connected with a higher risk of falls. We administered a 12-week vitamin D₃ supplementation based on BMI (with higher doses given to patients with higher BMI) to investigate its effects on physical performance and inflammation status in PD patients with DBS. Patients were randomly divided into two groups: treated with vitamin D₃ (VitD, n = 13), and supplemented with vegetable oil as the placebo group (PL, n = 16). Patients underwent functional tests to assess their physical performance three times during this study. The serum 25(OH)D₃ concentration increased to the recommended level of 30 ng/mL in the VitD group, and a significant elevation in vitamin D metabolites in this group was found. We observed significant improvement in the Up and Go and the 6 MWT in the VitD group. In inflammation status, we noticed a trend toward a decrease in the VitD group. To conclude, achieving the optimal serum 25(OH)D₃ concentration is associated with better functional test performance and consequently may have a positive impact on reducing falling risk in PD.

Socioeconomic, Clinical, and Laboratory Parameters Differentiating Pediatric Patients With MOG Antibody-Associated Disease and Multiple Sclerosis

Studies indicate differences in the clinical phenotypes and neuroimaging of children with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) compared to multiple sclerosis; however, there are limited data assessing the socioeconomic and paraclinical differences between these distinct disorders. This retrospective study identified patients aged <18 years at time of diagnosis with MOGAD or multiple sclerosis. Demographics, birth history, socioeconomic factors (insurance type, median income, parental education level), and paraclinical features (clinical manifestations, laboratory evaluation) were recorded for eligible participants. Seventy-eight patients (28 MOGAD, 50 multiple sclerosis) met inclusion criteria. Mothers of MOGAD children were more likely to have attended college compared to the mothers of children with multiple sclerosis (80% vs 49%; P = .02). Though MOGAD patients had greater rates of day care attendance (81% vs 57%), lower rates of birth complications (7% vs 21%), and higher rates of being breastfed (65% vs 46%), these findings did not meet predefined statistical significance. Clinically, children with MOGAD exhibited a lower body mass index percentile at presentation (58th ± 27th percentile vs 83rd ± 20th percentile; P = .0001) and were younger (7.6 ± 4.1 vs 14.8 ± 1.6 years; P < .0001) and more likely to exhibit an infectious prodrome (57% vs 10%; P < .0001). MOGAD patients were less likely to have evidence of remote Epstein-Barr virus infection (29% vs 100%; P < .0001) and less likely to have ≥3 unique oligoclonal bands in the cerebrospinal fluid (5% vs 87%; P < .001). Compared with multiple sclerosis, children with MOGAD exhibit lower body mass index percentiles at presentation, are more likely to have mothers with higher education levels, and are less likely to have had prior Epstein-Barr virus infection. Our data confirm that MOGAD patients are younger, more likely to exhibit infectious prodrome, and are less likely to exhibit intrathecal synthesis of oligoclonal bands. These features provide new insights into the differentiating pathobiology of MOGAD and may be helpful in differentiating these children from multiple sclerosis early in the diagnostic evaluation.

Modifiable contributing factors to COVID-19: A comprehensive review

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. The current study identifies eighty immune system dysfunction-enabling toxic stressors and behaviors (hereafter called modifiable contributing factors (CFs)) that also link directly to COVID-19. Each CF is assigned to one of the five categories in the CF taxonomy shown in Section 3.3.: Lifestyle (e.g., diet, substance abuse); Iatrogenic (e.g., drugs, surgery); Biotoxins (e.g., micro-organisms, mycotoxins); Occupational/Environmental (e.g., heavy metals, pesticides); Psychosocial/Socioeconomic (e.g., chronic stress, lower education). The current study shows how each modifiable factor contributes to decreased immune system capability, increased inflammation and coagulation, and increased neural damage and neurodegeneration. It is unclear how real progress can be made in combatting COVID-19 and other similar diseases caused by viral variants without addressing and eliminating these modifiable CFs.

Vitamin D and neurodegenerative diseases

Neurodegenerative diseases, featured by progressive loss of structure or function of neurons, are considered incurable at present. Movement disorders like tremor and postural instability, cognitive or behavioral disorders such as memory impairment are the most common symptoms of them and the growing patient population of neurodegenerative diseases poses a serious threat to public health and a burden on economic development. Hence, it is vital to prevent the occurrence of the diseases and delay their progress. Vitamin D can be transformed into a hormone in vivo with both genomic and non-genomic actions, exerting diverse physiological effects. Cumulative evidence indicates that vitamin D can ameliorate neurodegeneration by regulating pertinent molecules and signaling pathways including maintaining Ca2+ homeostasis, reducing oxidative stress, inhibiting inflammation, suppressing the formation and aggregation of the pathogenic protein, etc. This review updates discoveries of molecular mechanisms underlying biological functions of vitamin D in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and vascular dementia. Clinical trials investigating the influence of vitamin D supplementation in patients with neurodegenerative diseases are also summarized. The synthesized information will probably provoke an enhanced understanding of the neuroprotective roles of vitamin D in the nervous system and provide therapeutic options for patients with neurodegenerative diseases in the future.

Cholecalciferol (VD3) Attenuates L-DOPA-Induced Dyskinesia in Parkinsonian Mice Via Modulation of Microglia and Oxido-Inflammatory Mechanisms

L-DOPA, the gold standard for managing Parkinson's disease (PD) is fraught by motor fluctuations termed L-Dopa-Induced Dyskinesia (LID). LID has very few therapeutic options. Hence, the need for preclinical screening of new interventions. Cholecalciferol (VD3) treatment reportedly improves motor deficit in experimental Parkinsonism. Therefore, the novel anti-dyskinetic effect of VD3 and its underlying mechanisms in LID was investigated. Dyskinesia was induced by chronic L-DOPA administration in parkinsonian (6-OHDA- lesioned) mice. The experimental groups: Control, Dyskinesia, Dyskinesia/VD3, and Dyskinesia/Amantadine were challenged with L-DOPA to determine the abnormal involuntary movements (AIMs) score during 14 days of VD3 (30 mg/kg) or Amantadine (40 mg/kg) treatment. Behavioral Axial, Limb & Orolingual (ALO) AIMs were scored for 1 min at every 20 mins interval, over a duration of 100 mins on days 1,3,7,11 and 14. Using western blot, striatum was assessed for expression of dopamine metabolic enzymes: Tyrosine Hydroxylase (TH) and Monoamine Oxidase-B (MAO-B); CD11b, BAX, P47phox, and IL-1β. Cholecalciferol significantly attenuated AIMs only on days 11 & 14 with maximal reduction of 32.7%. Expression of TH and MAO-B was not altered in VD3 compared with dyskinetic mice. VD3 significantly inhibited oxidative stress (P47phox), apoptosis (BAX), inflammation (IL-1β) and microglial activation (CD11b). VD3 showed anti-dyskinetic effects behaviorally by attenuating abnormal involuntary movements, modulation of striatal oxidative stress, microglial responses, inflammation, and apoptotic signaling; without affecting dopamine metabolic enzymes. Its use in the management of dyskinesia is promising. More studies are required to further evaluate these findings. Keywords: Cholecalciferol; L-DOPA-Induced Dyskinesia; Parkinson's Disease; Microglial; Oxidative stress; Inflammation.

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Vitamin D3 exerts immunomodulatory and memory improving properties in rats with lipopolysaccharide-induced inflammation

INTRODUCTION

Vitamin D is a fat-soluble secosteroid, its primary function being regulation of calcium-phosphate homeostasis and maintenance of bone integrity and mineralization. Recently, pleotropic effects of this vitamin have been recognized, including an immunomodulatory role and involvement in normal brain development and functioning.

Serum levels of interleukin-6 and Vitamin D at the onset of multiple sclerosis and neuromyelitis optica: A pilot study

BACKGROUND

Interleukin-6 (IL-6) is an important mediator in the acute phase of inflammatory diseases such as neuromyelitis optica (NMO) and multiple sclerosis (MS). The level of IL-6 is higher in cerebrospinal fluid and serum of NMO patients compare to MS. Vitamin D has a regulatory effect on IL-6, so it may have a negative correlation with IL-6 in the acute phase of these diseases. This study was performed to evaluate the serum levels of IL-6 and Vitamin D in NMO and MS patients at the onset of disease to find differences that may help in early diagnosis.

MATERIALS AND METHODS

This case-control study was done on patients with the first episode of optic neuritis, transverse myelitis, and area postrema syndrome who were referred to Kashani MS Center in Isfahan, Iran, between January 2018 and January 2020. The serum levels of Vitamin D and IL-6 were assessed using enzyme-linked immunosorbent assay in blood sample taken at the time of first presentation in patients who had a definitive diagnosis of NMO and MS during subsequent workup.

RESULTS

During a 2-year follow-up, definitive diagnosis of NMO was given in 25 cases, and they were compared with 25 cases that were randomly selected from patients with definite MS. Nineteen patients in the NMO group and 21 patients in the MS group were female. The mean age of patients in the NMO and MS groups was 29.64 ± 1.47 and 30.20 ± 1.42, respectively (P = 0.46). The mean of serum level of Vitamin D was 24.88 ± 15.2 in NMO patients and 21.56 ± 18.7 in MS patients without significant difference (P = 0.48). The mean of IL-6 was 30.1 ± 22.62 in the NMO group and 23.35 ± 18.8 in the MS group without significant difference (P = 0.28). The serum levels of Vitamin D were insufficient in both groups. No correlation between Vitamin D and IL-6 levels was found in our study (P > 0.05).

CONCLUSION

Our results showed that serum IL-6 levels were higher at the onset of NMO disease compared with MS. The serum levels of Vitamin D were low in both groups and there was no association between serum levels of Vitamin D and IL-6 in either group. Future studies with large sample size are needed to confirm these findings.

The Role of Vitamin D in Alzheimer’s Disease: A Transcriptional Regulator of Amyloidopathy and Gliopathy

Alzheimer’s disease (AD) is characterized by amyloid-beta (Aβ) accumulation and cognitive mental decline. Epidemiological studies have suggested an association between low serum vitamin D levels and an increased risk of AD. Vitamin D regulates gene expression via the vitamin D receptor, a nuclear ligand-dependent transcription factor. However, the molecular mechanism underlying the pathogenic and therapeutic effects of vitamin D on AD is not fully understood yet. To better understand how vitamin D regulates the expression of genes related to AD pathology, first, we induced vitamin D deficiency in 5xFAD mice by providing a vitamin-D-deficient diet and observed the changes in the mRNA level of genes related to Aβ processing, which resulted in an increase in the Aβ load in the brain. The vitamin D-deficient diet also suppressed the expression of genes for microglial Aβ phagocytosis. Interestingly, vitamin D deficiency in the early stage of AD resulted in earlier memory impairment. In addition, we administered vitamin D intraperitoneally to 5xFAD mice with a normal diet and found lower Aβ levels with the suppressed expression of genes for Aβ generation and observed improved memory function, which may be potentially associated with reduced MAO-B expression. These findings strongly suggest the role of vitamin D as a crucial disease-modifying factor that may modulate the amyloid pathology with regard to reducing AD symptoms.

Parkinson’s Disease Etiology: Insights and Associations with Phosphate Toxicity

The present paper investigated the association of Parkinson’s disease etiology with phosphate toxicity, a pathophysiological condition in which dysregulated phosphate metabolism causes excessive inorganic phosphate sequestration in body tissue that damages organ systems. Excessive phosphate is proposed to reduce Complex I function of the mitochondrial electron transport chain in Parkinson’s disease and is linked to opening of the mitochondrial permeability transition pore, resulting in increased reactive oxygen species, inflammation, DNA damage, mitochondrial membrane depolarization, and ATP depletion causing cell death. Parkinson’s disease is associated with α-synuclein and Lewy body dementia, a secondary tauopathy related to hyperphosphorylation of tau protein, and tauopathy is among several pathophysiological pathways shared between Parkinson’s disease and diabetes. Excessive phosphate is also associated with ectopic calcification, bone mineral disorders, and low levels of serum vitamin D in patients with Parkinson’s disease. Sarcopenia and cancer in Parkinson’s disease patients are also associated with phosphate toxicity. Additionally, Parkinson’s disease benefits are related to low dietary phosphate intake. More studies are needed to investigate the potential mediating role of phosphate toxicity in the etiology of Parkinson’s disease.

The Multiple Effects of Vitamin D against Chronic Diseases: From Reduction of Lipid Peroxidation to Updated Evidence from Clinical Studies

BACKGROUND

Vitamin D exerts multiple beneficial effects in humans, including neuronal, immune, and bone homeostasis and the regulation of cardiovascular functions. Recent studies correlate vitamin D with cancer cell growth and survival, but meta-analyses on this topic are often not consistent.

METHODS

A systematic search of the PubMed database and the Clinical Trial Register was performed to identify all potentially relevant English-language scientific papers containing original research articles on the effects of vitamin D on human health.

RESULTS

In this review, we analyzed the antioxidant and anti-inflammatory effects of vitamin D against acute and chronic diseases, focusing particularly on cancer, immune-related diseases, cardiomyophaties (including heart failure, cardiac arrhythmias, and atherosclerosis) and infectious diseases.

CONCLUSIONS

Vitamin D significantly reduces the pro-oxidant systemic and tissue biomarkers involved in the development, progression, and recurrence of chronic cardiometabolic disease and cancer. The overall picture of this review provides the basis for new randomized controlled trials of oral vitamin D supplementation in patients with cancer and infectious, neurodegenerative, and cardiovascular diseases aimed at reducing risk factors for disease recurrence and improving quality of life.

The Biological Role of Vitamins in Athletes’ Muscle, Heart and Microbiota

Physical activity, combined with adequate nutrition, is considered a protective factor against cardiovascular disease, musculoskeletal disorders, and intestinal dysbiosis. Achieving optimal performance requires a significantly high energy expenditure, which must be correctly supplied to avoid the occurrence of diseases such as muscle injuries, oxidative stress, and heart pathologies, and a decrease in physical performance during competition. Moreover, in sports activities, the replenishment of water, vitamins, and minerals consumed during training is essential for safeguarding athletes’ health. In this scenario, vitamins play a pivotal role in numerous metabolic reactions and some muscle biochemical adaptation processes induced by sports activity. Vitamins are introduced to the diet because the human body is unable to produce these micronutrients. The aim of this review is to highlight the fundamental role of vitamin supplementation in physical activity. Above all, we focus on the roles of vitamins A, B6, D, E, and K in the prevention and treatment of cardiovascular disorders, muscle injuries, and regulation of the microbiome.

The peculiar role of vitamin D in the pathophysiology of cardiovascular and neurodegenerative diseases

Vitamin D is a hormone with both genomic and non-genomic actions. It exerts its activity by binding vitamin D receptor (VDR), which belongs to the superfamily of nuclear receptors and ligand-activated transcription factors. Since VDR has been found in various tissues, it has been estimated that it regulates approximately 3% of the human genome. Several recent studies have shown pleiotropic effects of vitamin D in various processes such as cellular proliferation, differentiation, DNA repair and apoptosis and its involvement in different pathophysiological conditions as inflammation, diabetes mellitus, and anemia. It has been suggested that vitamin D could play an important role in neurodegenerative and cardiovascular disorders. Moderate to strong associations between lower serum vitamin D concentrations and stroke and cardiovascular events have been identified in different analytic approaches, even after controlling for traditional demographic and lifestyle covariates. The mechanisms behind the associations between vitamin D and cerebrovascular and cardiologic profiles have been widely examined both in animal and human studies. Optimization of vitamin D levels in human subjects may improve insulin sensitivity and beta-cell function and lower levels of inflammatory markers. Moreover, it has been demonstrated that altered gene expression of VDR and 1,25D3-membrane-associated rapid response steroid-binding (1,25D3-MARRS) receptor influences the role of vitamin D within neurons and allows them to be more prone to degeneration. This review summarizes the current understanding of the molecular mechanisms underlying vitamin D signaling and the consequences of vitamin D deficiency in neurodegenerative and cardiovascular disorders.

Impact of ER Stress and ER-Mitochondrial Crosstalk in Huntington's Disease

Accumulation of misfolded proteins is a common phenomenon of several neurodegenerative diseases. The misfolding of proteins due to abnormal polyglutamine (PolyQ) expansions are linked to the development of PolyQ diseases including Huntington's disease (HD). Though the genetic basis of PolyQ repeats in HD remains prominent, the primary molecular basis mediated by PolyQ toxicity remains elusive. Accumulation of misfolded proteins in the ER or disruption of ER homeostasis causes ER stress and activates an evolutionarily conserved pathway called Unfolded protein response (UPR). Protein homeostasis disruption at organelle level involving UPR or ER stress response pathways are found to be linked to HD. Due to dynamic intricate connections between ER and mitochondria, proteins at ER-mitochondria contact sites (mitochondria associated ER membranes or MAMs) play a significant role in HD development. The current review aims at highlighting the most updated information about different UPR pathways and their involvement in HD disease progression. Moreover, the role of MAMs in HD progression has also been discussed. In the end, the review has focused on the therapeutic interventions responsible for ameliorating diseased states via modulating either ER stress response proteins or modulating the expression of ER-mitochondrial contact proteins.

Implications of Vitamins in COVID-19 Prevention and Treatment through Immunomodulatory and Anti-Oxidative Mechanisms

Since the appearance of the coronavirus disease 2019 (COVID-19) and its announcement as a global pandemic, the search for prophylactic and therapeutic options have become a priority for governments and the scientific community. The approval of several vaccines against SARS-CoV-2 is being crucial to overcome this situation, although the victory will not be achieved while the whole population worldwide is not protected against the virus. This is why alternatives should be studied in order to successfully support the immune system before and during a possible infection. An optimal inflammatory and oxidative stress status depends on an adequate diet. Poor levels of several nutrients could be related to an impaired immune response and, therefore, an increased susceptibility to infection and serious outcomes. Vitamins exert a number of anti-microbial, immunomodulatory, anti-inflammatory, and antioxidant activities, which can be of use to fight against this and several other diseases (especially vitamin D and C). Even though they cannot be considered as a definitive therapeutic option, in part owing to the lack of solid conclusions from well-designed clinical trials, currently available evidence from similar respiratory diseases may indicate that it would be rational to deeply explore the use of vitamins during this global pandemic.

The role of Western diets and obesity in peripheral immune cell recruitment and inflammation in the central nervous system

As the prevalence of obesity and chronic disease increases, the role of nutrition is taking center stage as a potential root cause of not just metabolic-related illnesses, but also of disorders of the central nervous system (CNS). Consumption of a modern, westernized diet, such as a high fat diet (HFD) that contains excess saturated fatty acids (SFAs), refined carbohydrates, and ultra-processed ingredients has been shown to induce neuroinflammation in multiple brain regions important for energy homeostasis, cognitive function, and mood regulation in rodents, non-human primates, and humans. This review article summarizes the literature showing Western diets, via SFA increases, can increase the reactivity and alter the function of multiple types of immune cells from both the innate and adaptive branches of the immune system, with a specific focus on microglia, macrophages, dendritic cells, and T-cells. These changes in immune and neuroimmune signaling have important implications for neuroinflammation and brain health and will be an important factor in future psychoneuroimmunology research.

The Role of Vitamins in Neurodegenerative Disease: An Update

Acquiring the recommended daily allowance of vitamins is crucial for maintaining homeostatic balance in humans and other animals. A deficiency in or dysregulation of vitamins adversely affects the neuronal metabolism, which may lead to neurodegenerative diseases. In this article, we discuss how novel vitamin-based approaches aid in attenuating abnormal neuronal functioning in neurodegeneration-based brain diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and Prion disease. Vitamins show their therapeutic activity in Parkinson's disease by antioxidative and anti-inflammatory activity. In addition, different water- and lipid-soluble vitamins have also prevented amyloid beta and tau pathology. On the other hand, some results also show no correlation between vitamin action and the prevention of neurodegenerative diseases. Some vitamins also exhibit toxic activity too. This review discusses both the beneficial and null effects of vitamin supplementation for neurological disorders. The detailed mechanism of action of both water- and lipid-soluble vitamins is addressed in the manuscript. Hormesis is also an essential factor that is very helpful to determine the effective dose of vitamins. PubMed, Google Scholar, Web of Science, and Scopus were employed to conduct the literature search of original articles, review articles, and meta-analyses.

A Specialized Nutritional Formulation Prevents Hippocampal Glial Activation and Memory Impairment Induced by Amyloid-β Oligomers in Mice

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia in the elderly and is characterized by progressive cognitive decline. Considerable evidence supports an important role of amyloid-β oligomers (AβOs) in the pathogenesis of AD, including the induction of aberrant glial activation and memory impairment.

OBJECTIVE

We have investigated the protective actions of a nutritional formulation, denoted AZ formulation, on glial activation and memory deficits induced by intracerebroventricular (i.c.v.) infusion of AβOs in mice.

METHODS

Two-month-old male mice were treated orally with AZ formulation or isocaloric placebo for 30 consecutive days. Microglial and astrocytic activation were analyzed by immunohistochemistry in the hippocampus 10 days after i.c.v. infusion of AβOs (n = 5 mice per experimental condition). Memory loss was assessed by the novel object recognition (NOR) test (n = 6-10 mice per experimental condition).

RESULTS

Oral treatment with the AZ formulation prevented hippocampal microglial and astrocytic activation induced by i.c.v. infusion of AβOs. The AZ formulation further protected mice from AβO-induced memory impairment.

CONCLUSION

Results suggest that administration of the AZ formulation may comprise a promising preventative and non-pharmacological strategy to reduce brain inflammation and attenuate memory impairment in AD.

The Effect of COVID-19 on NF-κB and Neurological Manifestations of Disease

The coronavirus disease that presumably began in 2019 (COVID-19) is a highly infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has resulted in a pandemic. Initially, COVID-19 was thought to only affect respiration. However, accumulating evidence shows a wide range of neurological symptoms are also associated with COVID-19, such as anosmia/ageusia, headaches, seizures, demyelination, mental confusion, delirium, and coma. Neurological symptoms in COVID-19 patients may arise due to a cytokine storm and a heighten state of inflammation. The nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) is a central pathway involved with inflammation and is shown to be elevated in a dose-dependent matter in response to coronaviruses. NF-κB has a role in cytokine storm syndrome, which is associated with greater severity in COVID-19-related symptoms. Therefore, therapeutics that reduce the NF-κB pathway should be considered in the treatment of COVID-19. Neuro-COVID-19 units have been established across the world to examine the neurological symptoms associated with COVID-19. Neuro-COVID-19 is increasingly becoming an accepted term among scientists and clinicians, and interdisciplinary teams should be created to implement strategies for treating the wide range of neurological symptoms observed in COVID-19 patients.

Calcitriol Alleviates MPP+- and MPTP-Induced Parthanatos Through the VDR/PARP1 Pathway in the Model of Parkinson's Disease

The pathogenesis of Parkinson’s disease (PD) is currently unclear. Recent studies have suggested a correlation between vitamin D and PD. Vitamin D and its analogs have protective effects in animal models of PD, but these studies have not clarified the mechanism. Parthanatos is a distinct type of cell death caused by excessive activation of poly (ADP-ribose) polymerase-1 (PARP1), and the activation of PARP1 in PD models suggests that parthanatos may exist in PD pathophysiology. 1,25-Dihydroxyvitamin D3 (calcitriol) is a potential inhibitor of PARP1 in macrophages. This study aimed to investigate whether calcitriol treatment improves PD models and its effects on the parthanatos pathway. A 1-methyl-4-phenylpyridinium (MPP⁺)-induced cell model and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) subacute animal model were selected as the in vitro and in vivo PD models, and calcitriol was applied in these models. Results showed that parthanatos existed in the MPP⁺-induced cell model and pretreatment with calcitriol improved cell viability, reduced the excessive activation of PARP1, and relieved parthanatos. The application of calcitriol in the MPTP subacute animal model also improved behavioral tests, restored the damage to dopamine neurons, and reduced the activation of PARP1-related signaling pathways. To verify whether calcitriol interacts with PARP1 through its vitamin D receptor (VDR), siRNA, and overexpression plasmids were used to downregulate or overexpress VDR. Following the downregulation of VDR, the expression and activation of PARP1 increased and PARP1 was inhibited when VDR was overexpressed. Coimmunoprecipitation verified the combination of VDR and PARP1. In short, calcitriol can substantially improve parthanatos in the MPP⁺-induced cell model and MPTP model, and the protective effect might be partly through the VDR/PARP1 pathway, which provides a new possibility for the treatment of PD.

Pathogenesis of autoimmune demyelination: from multiple sclerosis to neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody-associated disease

Autoimmunity plays a significant role in the pathogenesis of demyelination. Multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein antibody‐associated disease (MOGAD) are now recognised as separate disease entities under the amalgam of human central nervous system demyelinating disorders. While these disorders share inherent similarities, investigations into their distinct clinical presentations and lesion pathologies have aided in differential diagnoses and understanding of disease pathogenesis. An interplay of various genetic and environmental factors contributes to each disease, many of which implicate an autoimmune response. The pivotal role of the adaptive immune system has been highlighted by the diagnostic autoantibodies in NMOSD and MOGAD, and the presence of autoreactive lymphocytes in MS lesions. While a number of autoantigens have been proposed in MS, recent emphasis on the contribution of B cells has shed new light on the well‐established understanding of T cell involvement in pathogenesis. This review aims to synthesise the clinical characteristics and pathological findings, discuss existing and emerging hypotheses regarding the aetiology of demyelination and evaluate recent pathogenicity studies involving T cells, B cells, and autoantibodies and their implications in human demyelination.

Association of Vitamin D Receptor Polymorphisms with Amyloid-β Transporters Expression and Risk of Mild Cognitive Impairment in a Chilean Cohort

Background: Amyloid-β peptide (Aβ) deposition in Alzheimer’s disease (AD) is due to an imbalance in its production/clearance rate. Aβ is transported across the blood-brain barrier by LRP1 and P-gp as efflux transporters and RAGE as influx transporter. Vitamin D deficit and polymorphisms of the vitamin D receptor (VDR) gene are associated with high prevalence of mild cognitive impairment (MCI) and AD. Further, vitamin D promotes the expression of LRP1 and P-gp in AD-animal model brains. Objective: To associate VDR polymorphisms Apa I (rs7975232), Taq I (rs731236), and Fok I (rs2228570) with the risk of developing MCI in a Chilean population, and to evaluate the relationship of these polymorphisms to the expression of VDR and Aβ-transporters in peripheral blood mononuclear cells (PBMCs). Methods: VDR polymorphisms Apa I, Taq I, and Fok I were determined in 128 healthy controls (HC) and 66 MCI patients. mRNA levels of VDR and Aβ-transporters were evaluated in subgroups by qPCR. Results: Alleles A of Apa I and C of Taq I were associated with a lower risk of MCI. HC with the Apa I AA genotype had higher mRNA levels of P-gp and LRP1, while the expression of VDR and RAGE were higher in MCI patients and HC. For Fok I, the TC genotype was associated with lower expression levels of Aβ-transporters in both groups. Conclusion: We propose that the response to vitamin D treatment will depend on VDR polymorphisms, being more efficient in carriers of protective alleles of Apa I polymorphism.

Evaluation of Month of Birth in Neuromyelitis Optica Spectrum Disorders (NMSOD) and Multiple Sclerosis (MS)

INTRODUCTION

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMO) are chronic immune-mediated diseases in the central nervous system (CNS). Environmental factors such as month of birth can be a trigger for these diseases. Therefore, we conducted this study to compare the months of birth in MS and NMOSD patients with the control group.

METHODS

In this cross-sectional study, 2345 patients with MS, 220 NMOSD patients, and 2174 healthy subjects were enrolled. Demographic information such as age, sex, month of birth, and education in three groups was extracted from the database. The associations between month of birth and MS were studied by binary logistic regression with adjusting for the year of birth.

RESULTS

There was a reduced birth rate in September-October in NMOSD (OR = 0.309, 95% CI: 0.150-0.636; p < 0.001) and MS patients (OR = 0.470, 95% CI: 0.374-0.591; p < 0.001) compared to the general population. The birth rate in March-April in MS was higher than the control group (OR = 1.613, 95% CI: 1.324-1.964; p < 0.001). There was no difference in the birth month distribution between the NMOSD and MS patients. No significant difference in MOB among different MS types was found.

CONCLUSION

Our findings showed a decreasing risk of NMOSD and MS in individuals born in the autumn months and an increasing MS risk in spring. More studies are required to elucidate the association between the month of birth and risk of MS and NMOSD and the seasonality factors.