Adipokines are associated with pediatric multiple sclerosis risk and course

Leptin and Leptin Signaling in Multiple Sclerosis: A Narrative Review

Obesity, a pandemic health problem, is now considered as a chronic inflammatory state, related to many autoimmune diseases, such as multiple sclerosis. Thus, adipokines, inflammatory mediators secreted by adipose tissue, play an important role modulating the immune response. In this context, obesity, especially during adolescent age, seems to be a key factor for the development of multiple sclerosis. Leptin, the main pro-inflammatory adipokine secreted by the adipose tissue, has been found increased in patients with multiple sclerosis and is able to regulate the immune system promoting a pro-inflammatory response. Leptin signaling in both innate and adaptative immune cells might have immunomodulatory effects in the context of multiple sclerosis. In this way, leptin has been found to produce a Th1 and Th17 response, increasing M1 macrophages and decreasing regulatory T cells and Th2 response. Moreover, circulating inflammatory adipokines, such as leptin, have been found in people with multiple sclerosis. In the present work, we are reviewing literature to update the body of knowledge regarding the role of obesity and leptin in multiple sclerosis.

Impact of Lifestyle Interventions on Multiple Sclerosis: Focus on Adipose Tissue

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by demyelination in the central nervous system (CNS), affecting individuals globally. The pathological mechanisms underlying MS remain unclear, but current evidence suggests that inflammation and immune dysfunction play a critical role in the pathogenesis of MS disease. Adipose tissue (AT) is a dynamic multifunctional organ involved in various immune diseases, including MS, due to its endocrine function and the secretion of adipokines, which can influence inflammation and immune responses. Physical activity represents an efficacious non-pharmacological strategy for the management of a spectrum of conditions that not only improves inflammatory and immune functions but also directly affects the status and function of AT. Additionally, the exploration of nutritional supplementation represents an important field of MS research aimed at enhancing clinical symptoms and is closely tied to the regulation of metabolic responses, including adipokine secretion. This review, therefore, aims to elucidate the intricate relationship between lifestyle and MS by providing an overview of the latest published data about the involvement of AT and the main adipokines, such as adiponectin, leptin, and tumor necrosis factor α (TNFα) in the pathogenesis of MS. Furthermore, we explore whether physical activity and dietary management could serve as useful strategies to improve the quality of life of MS patients.

Abnormal body mass index is associated with risk of multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

It is widely recognized that obesity is characterized by a chronic low-grade inflammatory condition. In the context of childhood and adolescent obesity, there is also a noteworthy correlation with elevated levels of inflammatory markers. These markers signify a proinflammatory state that may have relevance to the development of MS. We aim to comprehensively explore the relationship between childhood, adolescent, and adulthood obesity and the risk of developing multiple sclerosis (MS).

METHOD

We performed a comprehensive systematic review and meta-analysis of relevant literature through online search in databases like MEDLINE, Scopus, EMBASE, and Web of Science. We included studies that 1) provided information on multiple body mass index (BMI) categories before the onset of MS (Pre-MS BMI) and 2) had a healthy control group.

RESULT

The overall risk ratio (RR) in underweight people is 0.96 (95 % CI: 0.85 to 1.09, I2 = 0 %), indicating no significant impact on MS risk. Individuals who are overweight or obese, on the other hand, were at a higher risk of MS, with RRs of 1.38 (95 % CI: 1.27 to 1.49, I2 = 49 %) and 1.88 (95 % CI: 1.50 to 2.35, I2 = 76 %), respectively. There is a significantly greater risk of MS for people who are obese than for those who are overweight.

CONCLUSION

Overweight and obese individuals are at increased risk for MS, emphasizing the significance of weight status in MS susceptibility. Our findings support the hypothesis that obesity-related mechanisms-such as chronic inflammation, immune responses, and changes in gut microbiota and adipokines-may play a role in this association.

Oral Contraceptives Interact with Adiposity-Associated Markers in Patients with Multiple Sclerosis

Growing evidence suggests the involvement of adipose tissue in modulating the clinical course of relapsing-remitting multiple sclerosis (RRMS). This study aimed to investigate whether the intake of combined oral contraceptives (COCs) affects body weight and leptin and adiponectin (APN) blood levels in these patients. Clinical data from 62 women (M = 33.23 year) were recorded prior to the initiation of disease-modifying therapy. Patients who were taking COCs at the time of experiencing the first symptoms of disease (COC user) were compared with those who never used these formulations or stopped taking them before disease onset (COC non-user). Bivariate Pearson's correlations and hierarchical multiple linear regressions analysis were conducted. Normalized APN levels were lower in the COC-using patients (p = 0.013). Negative correlations between waist circumference and normalized APN (p = 0.001) were observed only in the COC non-user patients. A longer duration of COC intake was associated with increased body mass index and waist circumference (p = 0.003). Normalized APN predicted the MS Severity Score (MSSS) (p = 0.020), but this correlation was lost in the COC user patients. After adjusting for confounders, only age (p = 0.027) and, later, disease onset (p = 0.014) were correlated with the MSSS. Larger and prospective studies are needed to investigate the interactions of sex steroids with adipose metabolism in modulating disease progression.

Impact of endocrine dysregulation on disability and non-motor symptoms in pediatric onset multiple sclerosis

Background

Pediatric onset multiple sclerosis (POMS) commonly occurs at the time of various endocrine changes. Evaluation of the impact of endocrine status on disease severity in POMS has not been previously explored.

Objective

This study sought to evaluate if sex and stress hormones in children with POMS impact motor and non-motor diseases severity.

Methods

A single-center case control study was performed. Individuals with POMS were compared to individuals without neurologic disease. Each individual had three blood draws assessing stress and sex hormones between 07:00 and 09:00. Measures of fatigue (Epworth sleepiness scale), depression (PHQ-9), and quality of life (PedsQL) assessed at each visit.

Results

Forty individuals with POMS and 40 controls were enrolled. Individuals with POMS had lower free testosterone (p = 0.003), cortisol (p < 0.001), and ACTH (p < 0.001) and had higher progesterone (p = 0.025) levels than controls. Relapses and EDSS were not impacted by endocrine variables. The POMS cohort had a significantly higher Epworth score (p < 0.001), PHQ-9 score (p < 0.001), and lower PQL score (p < 0.001) than controls. Non-motor measures were not associated with endocrine status.

Conclusion

Free testosterone, cortisol, ACTH, and progesterone were abnormal in children with POMS although there was no association between endocrine status and markers of disease severity or non-motor symptoms of MS.

Lipocalin-2 promotes adipose-macrophage interactions to shape peripheral and central inflammatory responses in experimental autoimmune encephalomyelitis

OBJECTIVE

Accumulating evidence suggests that dysfunctional adipose tissue (AT) plays a major role in the risk of developing multiple sclerosis (MS), the most common immune-mediated and demyelinating disease of the central nervous system. However, the contribution of adipose tissue to the etiology and progression of MS is still obscure. This study aimed at deciphering the responses of AT in experimental autoimmune encephalomyelitis (EAE), the best characterized animal model of MS.

RESULTS AND METHODS

We observed a significant AT loss in EAE mice at the onset of disease, with a significant infiltration of M1-like macrophages and fibrosis in the AT, resembling a cachectic phenotype. Through an integrative and multilayered approach, we identified lipocalin2 (LCN2) as the key molecule released by dysfunctional adipocytes through redox-dependent mechanism. Adipose-derived LCN2 shapes the pro-inflammatory macrophage phenotype, and the genetic deficiency of LCN2 specifically in AT reduced weight loss as well as inflammatory macrophage infiltration in spinal cord in EAE mice. Mature adipocytes downregulating LCN2 reduced lipolytic response to inflammatory stimuli (e.g. TNFα) through an ATGL-mediated mechanism.

CONCLUSIONS

Overall data highlighted a role LCN2 in exacerbating inflammatory phenotype in EAE model, suggesting a pathogenic role of dysfunctional AT in MS.

Environmental Influences on Risk and Disease Course in Pediatric Multiple Sclerosis

Pediatric multiple sclerosis (MS) accounts for 3%-10% of all patients diagnosed with MS. Complex interplay between environmental factors impacts the risk for MS and may also affect disease course. Many of these environmental factors are shared with adult-onset MS. However, children with MS are in closer temporal proximity to the biological onset of MS and have less confounding environmental exposures than their adult counterparts. Environmental factors that contribute to MS risk include: geographical latitude, viral exposures, obesity, vitamin deficiencies, smoking, air pollution, perinatal factors, gut microbiome, and diet. More recently, research efforts have shifted to studying the impact of these risk determinants on the clinical course of MS. In this article we will examine relevant environmental risk determinants of pediatric MS and review the current knowledge on how these factors may contribute to pediatric MS disease evolution.

Adiponectin Alleviates Cell Injury due to Cerebrospinal Fluid from Multiple Sclerosis Patients by Inhibiting Oxidative Stress and Proinflammatory Response

Multiple sclerosis (MS) is the most common disabling neurological disease characterized by chronic inflammation and neuronal cell viability impairment. Based on previous studies reporting that adiponectin exhibits neuroprotective effects in some models of neurodegenerative diseases, we analyzed the effects of AdipoRon treatment, alone or in combination with the cerebrospinal fluid of patients with MS (MS-CSF), to verify whether this adipokine acts on the basal neuronal cellular processes. To this aim, SH-SY5Y and U-87 cells (models of neuronal and glial cells, respectively) were exposed to MS-CSF alone or in co-treatment with AdipoRon. The cell viability was determined via MTT assay, and the possible underlying mechanisms were investigated via the alterations of oxidative stress and inflammation. MTT assay confirmed that AdipoRon alone did not affect the viability of both cell lines; whereas, when used in combination with MS-CSF, it reduces MS-CSF inhibitory effects on the viability of both SH-SY5Y and U-87 cell lines. In addition, MS-CSF treatment causes an increase in pro-inflammatory cytokines, whereas it determines the reduction in anti-inflammatory IL-10. Interestingly, the co-administration of AdipoRon counteracts the MS-CSF-induced production of pro-inflammatory cytokines, whereas it determines an enhancement of IL-10. In conclusion, our data suggest that AdipoRon counteracts the cytotoxic effects induced by MS-CSF on SH-SY5Y and U-87 cell lines and that one of the potential molecular underlying mechanisms might occur via reduction in oxidative stress and inflammation. Further in vivo and in vitro studies are essential to confirm whether adiponectin could be a neuro-protectant candidate against neuronal cell injury.

Aging in multiple sclerosis: from childhood to old age, etiopathogenesis, and unmet needs: a narrative review

Multiple sclerosis (MS) primarily affects adult females. However, in the last decades, rising incidence and prevalence have been observed for demographic extremes, such as pediatric-onset MS (POMS; occurring before 18 years of age) and late-onset MS (corresponding to an onset above 50 years). These categories show peculiar clinical-pathogenetic characteristics, aging processes and disease courses, therapeutic options, and unmet needs. Nonetheless, several open questions are still pending. POMS patients display an important contribution of multiple genetic and environmental factors such as EBV, while in LOMS, hormonal changes and pollution may represent disease triggers. In both categories, immunosenescence emerges as a pathogenic driver of the disease, particularly for LOMS. In both populations, patient and caregiver engagement are essential from the diagnosis communication to early treatment of disease-modifying therapy (DMTs), which in the elderly population appears more complex and less proven in terms of efficacy and safety. Digital technologies (e.g., exergames and e-training) have recently emerged with promising results, particularly in treating and following motor and cognitive deficits. However, this offer seems more feasible for POMS, being LOMS less familiar with digital technology. In this narrative review, we discuss how the aging process influences the pathogenesis, disease course, and therapeutic options of both POMS and LOMS. Finally, we evaluate the impact of new digital communication tools, which greatly interest the current and future management of POMS and LOMS patients.

Obesity, gut microbiota, and multiple sclerosis: Unraveling the connection

Obesity is associated with chronic mild-grade systemic inflammation and neuroinflammation. Obesity in early childhood and adolescence is also a significant risk factor for multiple sclerosis (MS) development. However, the underlying mechanisms that explain the link between obesity and MS development are not fully explored. An increasing number of studies call attention to the importance of gut microbiota as a leading environmental risk factor mediating inflammatory central nervous system demyelination, particularly in MS. Obesity and high-calorie diet are also associated with disturbances in gut microbiota. Therefore, gut microbiota alteration is a plausible connection between obesity and the increased risk of MS development. A greater understanding of this connection could provide additional therapeutic opportunities, like dietary interventions, microbiota-derived products, and exogenous antibiotics and probiotics. This review summarizes the current evidence regarding the relationships between MS, obesity, and gut microbiota. We discuss gut microbiota as a potential link between obesity and increased risk for MS. Additional experimental studies and controlled clinical trials targeting gut microbiota are warranted to unravel the possible causal relationship between obesity and increased risk of MS.

Multiple sclerosis and obesity: The role of adipokines

Multiple Sclerosis (MS), a chronic inflammatory disease of the central nervous system that leads to demyelination and neurodegeneration has been associated with various environmental and lifestyle factors. Population-based studies have provided evidence showing the prevalence of MS is increasing worldwide. Because a similar trend has been observed for obesity and metabolic syndrome, interest has grown in possible underlying biological mechanisms shared by both conditions. Adipokines, a family of soluble factors produced by adipose tissue that participate in a wide range of biological functions, contribute to a low state of chronic inflammation observed in obesity, and influence immune function, metabolism, and nutritional state. In this review, we aim to describe epidemiological and biological factors common to MS and obesity, as well as provide an update on current knowledge of how different pro- and anti-inflammatory adipokines participate as immune response mediators in MS, as well as in the animal model for MS, namely, experimental autoimmune encephalomyelitis (EAE). Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) leading to demyelination, and neurodegeneration. Although its pathogenesis is not yet fully understood, there is considerable evidence to suggest MS arises from complex interactions between individual genetic susceptibility and external environmental factors. In recent decades, population-based studies have provided evidence indicating the prevalence of MS is increasing worldwide, in parallel with the rise in obesity and metabolic syndrome. This synchronous increment in the incidence of both MS and obesity has led to a search for potential biological mechanisms linking both conditions. Notably, a large number of studies have established significant correlation between obesity and higher prevalence, or worse prognosis, of several immune-mediated conditions. Fat tissue has been found to produce a variety of soluble factors named adipokines. These mediators, secreted by both adipocytes as well as diverse immune cells, participate in a wide range of biological functions, further strengthening the concept of a link between immune function, metabolism, and nutritional state. Because obesity causes overproduction of pro-inflammatory adipokines (namely leptin, resistin and visfatin) and reduction of anti-inflammatory adipokines (adiponectin and apelin), adipose tissue dysregulation would appear to contribute to a state of chronic, low-grade inflammation favoring the development of disease. In this review, we present a summary of current knowledge related to the pathological effects of different adipokines, prevalent in obese MS patients.

Efficacy of diet on fatigue, quality of life and disability status in multiple sclerosis patients: rapid review and meta-analysis of randomized controlled trials

Background

Multiple sclerosis is an inflammatory and neurodegenerative disease. People with multiple sclerosis (pwMS) experience chronic fatigue which is difficult to deal with therapeutically and greatly affects health-related quality of life (QOL).

PwMS are aware of the lack of generalized dietary advice related to their disease, leading to self-experimentation with diet.

It is necessary to provide objective information about dietary interventions for pwMS. We aim to provide an objective synthesis of the evidence for efficacy and safety of specific diets in pwMS through a rapid review and meta-analyses of randomized controlled trials (RCTs), examining symptomatic fatigue (MFIS), QOL, Expanded-Disability-Status-Scale (EDSS), and severe adverse events.

Methods

We have carried out a rapid review (MEDLINE and EMBASE) up to December 2021, with PRISMA methodology, and meta-analyses, of (RCTs). All statistical analyses were performed using the comprehensive meta-analysis (CMA) -RStudio 4.1.3. The analysis used weighted mean differences (WMD) and a 95% confidence interval (CI) using a random-effects model to compare the effects of the dietary intervention with the control.

Results

Eight studies met the inclusion criteria. Of these eight studies, five analyzed EDSS, three MFIS, and three QOL. A total of 515 patients were analyzed. These meta-analyses cumulative evidence support that dietary intervention is associated with a trend of reduction in fatigue (308 patients studied) -the difference between means (SMD) of the control group and intervention group was -2,033, 95%-IC (-3,195, -0,152), a p-value of 0.0341)-, an increase in QOL (77 patients studied), no significant effect on EDSS (337 patients studied), and no severe adverse events.

Conclusions

It is difficult to reach a high level of evidence in dietary studies. Our findings show that dietary intervention is associated with a trend of reduction in fatigue in MS. Taking into account the potential of dietary interventions and the benefit/risk ratio in their favor, neurologists must be aware of the great importance of making interventions on diet in MS if necessary. There are dietary interventions with some evidence of benefit for patients with MS, which could be chosen based on adherence, patient preferences, and individual outcomes. Large prospective clinical trials are needed to shed further light on this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02913-w.

Preventing Multiple Sclerosis: The Pediatric Perspective

Pediatric-onset multiple sclerosis (MS) is a predominantly relapsing-remitting neuroinflammatory disorder characterized by frequent relapses and high magnetic resonance imaging (MRI) lesion burden early in the disease course. Current treatment for pediatric MS relies on early initiation of disease-modifying therapies designed to prevent relapses and slow progression of disability. When considering the concept of MS prevention, one can conceptualize primary prevention (population- or at-risk population interventions that prevent the earliest facet of MS pathobiology and hence reduce disease incidence), or secondary prevention (prevention of disease consequence, such as reducing relapse frequency and lesion accrual, enhancing focal lesion repair, promoting CNS resilience against the more global facets of disease injury, and ultimately, preventing progression of neurological disability). Studying the pediatric MS population provides a unique opportunity to explore early-life exposures that contribute to the development of MS including perinatal and environmental risk determinants. Research is ongoing related to targeting these risk factors for potential MS primary prevention. Here we review these key risk factors, their proposed role in the pathogenesis of MS, and their potential implications for primary MS prevention.

Altered adipokine levels are associated with dimethyl fumarate treatment in multiple sclerosis patients

BACKGROUND

Obesity is linked to increased risk of multiple sclerosis (MS) and worsening disease severity. Recent experimental and clinical data indicates that adipokines are involved in regulating immune response and serve as cross talk between immune and neural system. Dimethyl fumarate (DMF) is an oral MS medication with unknown mechanism of action. It upregulates the nuclear factor E2-related factor 2 (Nrf2) pathway, a pathway for adipocyte differentiation. To determine a possible relationship between treatment with dimethyl fumarate, serum adipokine profiles and treatment response in patients with MS, we conducted an observational cohort study and measured serum adipokine and Vitamin D levels before and after treatment with DMF and examined their association with treatment response.

METHODS

We identified patients enrolled in the Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women's Hospital (CLIMB) study who were treated with dimethyl fumarate and had available serum samples. Longitudinal pre-treatment and on-treatment samples were available in 23 patients. Cross-sectional on-treatment samples were available in 91 patients, who were classified into DMF responders and non-responders based on radiologic and clinical relapse activity or disability progression. We measured serum leptin, adiponectin, resistin, ghrelin, fatty acid binding protein-4 (FABP-4) and-5 (FABP-5), vitamins D2 and D3. Statistical analysis was performed with paired t-tests, Wilcoxon signed-rank and Mann-Whitney U tests.

RESULTS

After treatment with DMF, serum adiponectin levels significantly increased, whereas FABP-4 levels significantly decreased compared to baseline levels, without a statistically significant change in the patients' BMI. Ghrelin levels were insignificantly lower post-treatment. FABP-4 levels were significantly higher in DMF responders compared to non-responders. This effect was sex-specific, with higher FABP4 levels associated with treatment response in males, but not females.

CONCLUSION

DMF treatment is associated with significant changes in serum adipokine levels, primarily adiponectin and FABP-4. Sex may affect the association between FABP-4 and treatment response.

Obesity in Pediatric-Onset Multiple Sclerosis: A French Cohort Study

Objective

To study the link between a high body mass index (BMI) in childhood and the occurrence of pediatric-onset multiple sclerosis (POMS) and to compare, within the MS population, the clinical-radiologic-biological characteristics, according to BMI.

Methods

A case-control study comparing BMI data of 60 patients with POMS (39 girls and 21 boys) at Bicêtre Hospital with that of 113 non-neurologic controls NNCs (68 girls and 45 boys) and 18,614 healthy controls HCs (9,271 girls and 9,343 boys) was performed. Crude BMI (cBMI), residual BMI (rBMI = measured BMI − expected BMI for age), z-score (rBMI/SD), and adult equivalent categories (International Obesity Task Force ≥25 = overweight, ≥30 = obese) were assessed.

Results

In boys, cBMI and rBMI were significantly higher in patients with POMS compared with NNCs (cBMI: +2.9; rBMI: +2.95, p < 0.01) and HCs (cBMI: +2.04, p < 0.01). In girls, cBMI or rBMI did not differ between POMS and NNCs patients (cBMI p = 0.4; rBMI p = 0.44) but with HCs (cBMI +0.99, p < 0.01). CSF inflammatory markers increased with BMI in prepubertal patients (p < 0.01), whereas vitamin D level at diagnosis was lower in boys with higher BMI (p = 0.016). Increased BMI was not associated with clinical and radiologic disease characteristics.

Conclusions

Overweight and obesity are more frequently observed at diagnosis, particularly in boys with POMS compared with non-neurologic controls and French HCs. Moreover, BMI is related to initial inflammation in the CSF in prepubertal patients with POMS suggesting an interaction between excess body fat, sexual hormones, and POMS occurrence.

Obesity and Multiple Sclerosis-A Multifaceted Association

BACKGROUND

Given the common elements in the pathophysiological theories that try to explain the appearance and evolution of obesity and multiple sclerosis, the association between the two pathologies has become an increasingly researched topic in recent years. On the one hand, there is the chronic demyelinating inflammation caused by the autoimmune cascade of multiple sclerosis, while on the other hand, according to the latest research, it has been shown that obesity shares an inflammatory component with most chronic diseases.

METHODS

The authors performed independent research of the available literature in the most important electronic databases (PubMed, Google Scholar, Embase, and Science Direct) in February 2021. After applying the exclusion criteria, the reviewers focused on the most relevant articles published during the last 10 years with respect to epidemiology and pathophysiology.

RESULTS

The data presented are a step forward in trying to elucidate the intricate relationship between obesity and MS, especially the causal relationship between childhood and adolescent obesity and MS, focusing on the epidemiological associations observed in the most relevant observational studies conducted in recent years. In the second part, the authors comment on the latest findings related to the pathophysiological mechanisms that may explain the correlations between obesity and multiple sclerosis, focusing also on the role of adipokines.

CONCLUSIONS

Based on available epidemiological data, obesity in early life appears to be strongly associated with a higher risk of MS development, independent of other risk factors. Although much research has been done on the pathophysiology of obesity, MS, their possible common mechanism, and the role of adipokines, further studies are needed in order to explain what remains unknown. No relevant data were found regarding the association between obesity, disability (high EDSS score), and mortality risk in MS patients. Thus, we consider that this topic should be elucidated in future research.

RIPK1 activation mediates neuroinflammation and disease progression in multiple sclerosis

Receptor interacting protein kinase 1 (RIPK1) mediates cell death and inflammatory signaling and is increased in multiple sclerosis (MS) brain samples. Here, we investigate the role of glial RIPK1 kinase activity in mediating MS pathogenesis. We demonstrate RIPK1 levels correlate with MS disease progression. We find microglia are susceptible to RIPK1-mediated cell death and identify an inflammatory gene signature that may contribute to the neuroinflammatory milieu in MS patients. We uncover a distinct role for RIPK1 in astrocytes in regulating inflammatory signaling in the absence of cell death and confirm RIPK1-kinase-dependent regulation in human glia. Using a murine MS model, we show RIPK1 inhibition attenuates disease progression and suppresses deleterious signaling in astrocytes and microglia. Our results suggest RIPK1 kinase activation in microglia and astrocytes induces a detrimental neuroinflammatory program that contributes to the neurodegenerative environment in progressive MS.

Zelic et al. characterize RIPK1-kinase-dependent regulation of inflammation and cell death in microglia and cell-death-independent inflammatory signaling in astrocytes. They demonstrate detrimental non-cell-autonomous consequences on oligodendrocytes and use animal models and human tissue to establish the involvement of RIPK1 in progressive forms of multiple sclerosis.

Obesity is associated with the Optic Neuritis severity in Male patients with Multiple Sclerosis

BACKGROUND

Obesity is an important modifiable risk factor of MS; a deeper biological understanding of this association is needed.

OBJECTIVE

To evaluate the determinants of acute optic neuritis (AON) severity and recovery in multiple sclerosis (MS).

METHODS

We included 61 patients with MS with recorded AON severity and recovery according to visual acuity outcomes before, at, and, after the relapse. We measured body mass index (BMI) and the serum concentration of estrogen, leptin, testosterone, sex hormone-binding globulin, and vitamin D. We tested the association between BMI and serum hormones and AON severity and recovery with logistic regressions.

RESULTS

In males, moderate/severe AON was associated with higher BMI (31.26 kg/m² vs 25.73 kg/m², logistic regression, p= 0.03), higher serum estrogen levels (32.24 nmol/L vs 23.06 nmol/L, logistic regression, p=0.04), and higher serum leptin levels (12.29 ng/mL vs mild AON: 4.1 ng/mL, logistic regression, p=0.06) than mild AON. These observations were not seen in female patients. We did not find an association with BMI or hormone levels and AON recovery.

CONCLUSION

BMI, serum leptin, and serum estrogen were associated with AON severity in male patients but not in female patients. No association of these factors and AON recovery was observed.

The relative contributions of obesity, vitamin D, leptin, and adiponectin to multiple sclerosis risk: A Mendelian randomization mediation analysis

BACKGROUND

Obesity is associated with increased risk of multiple sclerosis (MS); however, the underlying mechanisms remain unclear.

OBJECTIVE

To determine the extent to which decreased vitamin D bioavailability and altered levels of adiponectin and leptin mediate the association between obesity and MS.

METHODS

We performed Mendelian randomization (MR) analyses to estimate the effects on MS of body mass index (BMI), 25-hydroxyvitamin D (25OHD), adiponectin, and leptin levels in a cohort of 14,802 MS cases and 26,703 controls. We then estimated the proportion of the effect of obesity on MS explained by these potential mediators.

RESULTS

Genetic predisposition to higher BMI was associated with increased MS risk (odds ratio (OR) = 1.33 per standard deviation (SD), 95% confidence interval (CI) = 1.09-1.63), while higher 25OHD levels reduced odds of MS (OR = 0.72 per SD, 95% CI = 0.60-0.87). In contrast, we observed no effect of adiponectin or leptin. In MR mediation analysis, 5.2% of the association between BMI and MS was attributed to obesity lowering 25OHD levels (95% CI = 0.3%-31.0%).

CONCLUSIONS

This study found that a minority of the increased risk of MS conferred by obesity is mediated by lowered vitamin D levels, while leptin and adiponectin had no effect. Consequently, vitamin D supplementation would only modestly reverse the effect of obesity on MS.