Impact of insulin resistance and metabolic syndrome on disability in patients with multiple sclerosis

Role of liver X receptor in multiple sclerosis: A long furtive life behind a barrier

Liver X receptors (LXRs) are nuclear receptors that function as transcription factors regulating cholesterol metabolism and are implicated in multiple sclerosis (MS) pathogenesis. This mini-review aims to elucidate the potential role of LXRs in MS neuropathology. MS is the most prevalent inflammatory and demyelinating disease of the central nervous system (CNS), impacting both the brain and spinal cord. Furthermore, alterations in brain cholesterol metabolism in MS can modify the functional activity and immune response of LXRs, which are implicated in MS neuropathology. Dysregulation of LXRs and cholesterol homeostasis is associated with the pathogenesis of MS. LXRs play a critical role in regulating the myelination of nerve sheaths, and defects in LXR function may contribute to the progression of MS. LXRs have immunomodulatory effects, including inhibition of the proliferation of lymphocytes, preventing contact of self-antigens to T cells, and regulating the apoptotic process of T cells. LXRs regulate the activity of microglia, which have pro-inflammatory and anti-inflammatory properties involved in immune regulation and clearance of debris as well as the remyelination process. LXRs regulate the functional activity of glial cells and prevent glial cell-mediated neurodegeneration. LXRs have an important role in the regulation of neuroinflammation during MS neuropathology. LXRs may prevent the progression of neuroinflammation in MS by inhibiting the NF-κB and NLRP3 inflammasome signaling pathways. In conclusion, LXRs play a crucial role in MS neuropathology by mitigating neuroinflammation. These findings proposed that LXR agonists, through modulation of cholesterol homeostasis and inflammatory response, could be effective in the management of MS.

Association between insulin resistance and multiple sclerosis: a systematic review and meta-analysis

There is increasing evidence of metabolic perturbations in multiple sclerosis (MS) patients, and insulin is an important parameter that has controversial effects on neurological disease. Therefore, this systematic review and meta-analysis study aimed to explore the association between insulin resistance (IR) and MS as well as insulin levels and MS. Three electronic databases, including Medline, Scopus, and the Web of Science, were examined up to 26 May 2023 for observational studies. Two independent reviewers assessed the studies according to a pre-specified protocol. Random-effects model using a Restricted-maximum Likelihood (REML) estimator was used to meta-analyze the association between IR [assessed by Homeostatic Model Assessment (HOMA-IR)], insulin and MS. Eighteen datasets from 2012 to 2022 were included in this meta-analysis. The standardized mean difference (SMD) for comparison IR and insulin between MS and healthy control group as outcomes 1 and 2 were 0.78 and 0.72 respectively. Furthermore, for outcome 1, we observed a greater effect size in studies that recruited different types of MS (Mix) (SMD: 1.09) than in those that included only relapsing-remitting MS (RRMS) (SMD: 0.59). The meta-analysis revealed a significant association between IR, insulin and MS, with stronger associations in studies that recruited mixed patients. However, high heterogeneity has been observed in the present study. Therefore, more studies are needed to confirm the association between these parameters and MS.

Potential molecular mechanism of exercise reversing insulin resistance and improving neurodegenerative diseases

Neurodegenerative diseases are debilitating nervous system disorders attributed to various conditions such as body aging, gene mutations, genetic factors, and immune system disorders. Prominent neurodegenerative diseases include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. Insulin resistance refers to the inability of the peripheral and central tissues of the body to respond to insulin and effectively regulate blood sugar levels. Insulin resistance has been observed in various neurodegenerative diseases and has been suggested to induce the occurrence, development, and exacerbation of neurodegenerative diseases. Furthermore, an increasing number of studies have suggested that reversing insulin resistance may be a critical intervention for the treatment of neurodegenerative diseases. Among the numerous measures available to improve insulin sensitivity, exercise is a widely accepted strategy due to its convenience, affordability, and significant impact on increasing insulin sensitivity. This review examines the association between neurodegenerative diseases and insulin resistance and highlights the molecular mechanisms by which exercise can reverse insulin resistance under these conditions. The focus was on regulating insulin resistance through exercise and providing practical ideas and suggestions for future research focused on exercise-induced insulin sensitivity in the context of neurodegenerative diseases.

Higher Dietary Acid Load Might Be a Potent Derivative Factor for Multiple Sclerosis: The Results from a Case-Control Study

This study aimed to investigate the association between dietary acid load (DAL) and multiple sclerosis (MS), through the potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. In a hospital-based case-control study of 109 patients with MS and 130 healthy individuals, a validated 168-item semi-quantitative food frequency questionnaire and a logistic regression model were used to evaluate the association between the DAL and MS. After adjusting for age (years), gender (male/female), body mass index (Kg/m2), and total calories (Kcal), the MS odds were 92% lower for those in the highest tertile of total plant-based protein (OR: 0.08, 95%CI: 0.03, 0.23; p-value < 0.001) and about four times higher for those in the highest tertile of the PRAL (OR: 4.16, 95%CI: 1.94, 8.91; p-value < 0.001) and NEAP scores (OR: 3.57, 95%CI: 1.69, 7.53; p-value < 0.001), compared to those in the lowest tertile. After further adjusting for sodium, saturated fatty acid, and fiber intake, the results remained significant for total plant-based protein intake (OR: 0.07, 95%CI: 0.01, 0.38; p-value = 0.002). In conclusion, a higher NEAP or PRAL score may be associated with increased odds of MS, while a higher intake of plant-based protein instead of animal-based protein may be protective.

Insulin resistance is associated with cognitive dysfunction in multiple sclerosis patients: A cross-sectional study

Multiple sclerosis (MS) is a progressive inflammatory neurodegenerative disease of the nervous system accompanied by demyelination. MS-associated cognitive impairments mainly involve recent memory, information processing speed, stable memory, and executive function. Moreover, MS is associated with impaired glucose and insulin metabolism, which can exacerbate cognitive decline. The present study aimed to compare the cognitive status of MS patients with and without insulin resistance. In this cross-sectional study, 74 relapsing-remitting multiple sclerosis diagnosed patients were enrolled. Indicators of insulin resistance, including fasting blood glucose, insulin level, and homeostatic model assessment of insulin resistance (HOMA-IR) index, were measured. They were then divided into two groups based on the results of the HOMA-IR index. Cognition status was evaluated by the minimal assessment of cognitive function in multiple sclerosis battery. The prevalence of insulin resistance was 37.8%, and the prevalence of cognitive decline was estimated to be 67.56%. Mean scores of the California verbal learning test (CVLT), CVLT delayed free recall, controlled oral word association test, and judgment of line orientation tests were significantly lower in MS patients with insulin resistance than without. In addition, a negative correlation was demonstrated between the results of the CVLT, CVLT delayed free recall, controlled oral word association test, judgment of line orientation tests, brief visuospatial memory test, and Delis-Kaplan executive function system sorting tests and fasting insulin levels. Greater verbal memory and spatial comprehension impairments were observed in MS patients with insulin resistance.

Long-term dietary acid load is associated with depression in multiple sclerosis, but less evidence was found with fatigue and anxiety

BACKGROUND

Diet-dependent acid-base load has been associated with worsening in mental health, but to date no study has examined this in people with multiple sclerosis (PwMS). We examined the association between potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores and depression, anxiety, and fatigue in PwMS.

METHODS

Participants with a first clinical diagnosis of CNS demyelination were followed prospectively as part of the AusLong Study (aged 18-59 years at cohort entry). At baseline, 5- and 10-year reviews, PRAL and NEAP scores were calculated using dietary intake in the preceding 12 months calculated from a food frequency questionnaire. At 5- and 10-year reviews, the Hospital Anxiety and Depression Scale was used to assess depression and anxiety, and the Fatigue Severity Scale assessed fatigue.

RESULTS

Higher PRAL and NEAP scores were associated with increased subsequent absolute value and change in HADS depression scores over five years' follow-up (e.g., highest vs lowest PRAL quartile, 5-year change in HADS-D score: β=+3.01, 95%CI= 1.54, 4.48, p<0.001). The level of depression at the 10-year review was determined by both the baseline dietary acid scores and baseline-5-year changes in dietary acid scores (e.g., PRAL change from baseline to 5-year review, 10-year review HADS-D score: β=+0.09, 95%CI= 0.03, 0.15, p<0.001, NEAP change from baseline to 5-year review, 10-year review HADS-D score: β=+0.07, 95%CI= 0.01, 0.14, p=0.03). Some associations were observed with anxiety and fatigue but were much weaker and less consistent.

CONCLUSION

Our findings indicate that a higher dietary acid load potentially has a long-term influence on the level of depression in PwMS. The evidence is less convincing for anxiety and fatigue.

Crosstalk between neurological, cardiovascular, and lifestyle disorders: insulin and lipoproteins in the lead role

Insulin resistance and impaired lipoprotein metabolism contribute to a plethora of metabolic and cardiovascular disorders. These alterations have been extensively linked with poor lifestyle choices, such as consumption of a high-fat diet, smoking, stress, and a redundant lifestyle. Moreover, these are also known to increase the co-morbidity of diseases like Type 2 diabetes mellitus and atherosclerosis. Under normal physiological conditions, insulin and lipoproteins exert a neuroprotective role in the central nervous system. However, the tripping of balance between the periphery and center may alter the normal functioning of the brain and lead to neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, depression, and multiple sclerosis. These neurological disorders are further characterized by certain behavioral and molecular changes that show consistent overlap with alteration in insulin and lipoprotein signaling pathways. Therefore, targeting these two mechanisms not only reveals a way to manage the co-morbidities associated with the circle of the metabolic, central nervous system, and cardiovascular disorders but also exclusively work as a disease-modifying therapy for neurological disorders. In this review, we summarize the role of insulin resistance and lipoproteins in the progression of various neurological conditions and discuss the therapeutic options currently in the clinical pipeline targeting these two mechanisms; in addition, challenges faced in designing these therapeutic approaches have also been touched upon briefly.

Ketogenic and Modified Mediterranean Diet as a Tool to Counteract Neuroinflammation in Multiple Sclerosis: Nutritional Suggestions

Ketogenic Diet is a nutritional pattern often used as dietotherapy in inflammatory diseases, including neurological disorders. Applied on epileptic children since 1920, in recent years it has been taken into account again as a tool to both reduce inflammatory burdens and ameliorate the nutritional status of patients affected by different pathologies. Multiple sclerosis (MS) is considered an immune-mediated neuro-inflammatory disease and diet is a possible factor in its pathogenesis. The aim of this work is to investigate the main potential targets of MS-related impairments, in particular the cognitive deficits, focusing on the alteration of biomarkers such as the Brain Derived-Neurotrophic Factor and the Tryptophan/Kynurenine ratio that could play a role on neuroprotection and thus on MS progression. Furthermore, we here propose nutritional suggestions which are useful in the development of a ketogenic diet protocol that takes advantage of the anti-inflammatory properties of low-carbohydrate foods from the Mediterranean diet to be applied to subjects with MS. In conclusion, this approach will allow one to develop the ketogenic diet combined with a modified Mediterranean diet as a possible tool to improve neuroinflammation in multiple sclerosis.

Vascular dysfunction and dyslipidemia in multiple sclerosis: are they correlated with disease duration and disability status?

BACKGROUND

There is strong evidence that vascular dysfunction is considered one of the possible causes of morbidity and mortality in patients suffering from multiple sclerosis (MS). This work aimed at assessing the arterial function and serum lipids in MS patients and correlating them with clinical and radiological findings.

RESULTS

This case-control study included 50 patients with MS and 50 age- and sex-matched controls. The arterial function was significantly reduced in MS patients, confirmed by significantly higher pulse wave velocity (PWV) and augmentation index (AIX), while the carotid IMT did not show significant difference between the two groups with no plaques in any of our patients. A significant positive correlation was found between PWV and both disease duration and disability. MS patients had significantly higher serum levels of T-cholesterol and triglycerides, and significantly lower serum levels of HDL-cholesterol, compared to controls. No significant correlation was found between serum lipids and either disease duration or disability.

CONCLUSIONS

There was a significant impairment in arterial function (assessed by the brachial cuff-based method via Mobil-O-Graph device) in MS patients compared to controls. Such impairment was significantly correlated with both disease duration and disability. MS patients had also significantly higher levels of T-cholesterol and triglycerides, compared to controls with no significant correlation between serum lipids and either disease duration or disability.

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.

The possible role of Interleukin-6 as a regulator of insulin sensitivity in patients with neuromyelitis optica spectrum disorder

Background

Neuromyelitis optica spectrum disorder (NMOSD) is associated with inflammatory mediators that may also trigger downstream signaling pathways leading to reduce insulin sensitivity.

Methods

We aimed to determine the risk association of hyperinsulinemia in NMOSD patients with seropositive AQP4-IgG and the serum levels of interleukin (IL)-6 and IL-17A compared with the control group.

Serum levels of metabolic (Insulin, Fasting Blood Sugar (FBS), lipid profile) and inflammatory (IL-6 and IL-17) markers were assessed in 56 NMOSD patients and 100 controls.

Results

Hyperinsulinemia was more prevalent in NMOSD patients independent of age, sex and body mass index (BMI) (48.2% vs. 26%, p = 0.005) compared to control group. After adjusting age, sex and BMI, there was significant association between lower insulin sensitivity (IS) and NMOSD risk (95% CI: Beta = 0.73, 0.62 to 0.86, p = 0.0001).

Circulating levels of IL-6 and IL-17 were higher in NMOSD patients, and only IL-6 had an effect modifier for the association between lower insulin sensitivity and NMOSD risk.

Conclusions

Our data suggests that inflammatory pathogenesis of NMOSD leads to hyperinsulinemia and increases the risk of insulin resistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02198-5.

Could the performance of oral glucose tolerance test contribute to the brain health-focused care in multiple sclerosis?

BACKGROUND

It has not been clarified yet if persons with multiple sclerosis (MS) are at increased risk to develop glucose metabolism dysregulation. The aims of the present study were to evaluate glucose metabolism characteristics in persons with MS and to compare it to the healthy individuals; to examine the association of glucose metabolism with the level of disability and its progression.

METHODS

The study enrolled 78 patients with MS and 26, comparable for age, gender and body mass index (BMI), healthy controls (HC). Disability and its progression were evaluated by the Expanded Disability Status Scale (EDSS) score, progression index (PI) and multiple sclerosis severity score (MSSS). All participants performed an oral glucose tolerance test (OGTT). Insulin and lipid parameters were analyzed.

RESULTS

Fasting glucose concentrations (5.3±0.7 in MS patients vs. 4.5±0.9 mmol/L in HC, p=0.001) and 2 hour post-load glucose concentrations were statistically significantly higher in MS patients compared with controls. Glucose levels at all different time points during OGTT, baseline insulin, Homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol and LDL were statistically significantly (p<0.05) associated with MS, in univariable logistic regression analysis. Glucose level at 120' was independently associated with MS (OR=3.937, 95% CI 1.178-13.159, p=0.026), in the multivariable model. The prevalence of IR was 64.1% in the MS group compared to 30.8% in the control group (p=0.008), based on HOMA-IR. EDSS and Multiple sclerosis severity score (MSSS) were associated with glucose levels at different time points (p<0.05). According to the ROC analysis, best cut-off value for HOMA-IR is 2.3, providing both sensitivity and specificity of 66.7% in discriminating persons with MS and HC.

CONCLUSION

Our results demonstrate the presence of higher prevalence of IR in MS patients compared to healthy individuals, and strong association between impaired glucose metabolism and disability. Finally, it has to be emphasized that further studies are warranted to confirm our findings implicating that MS patients have significantly higher risk of impaired glucose metabolism, which could suggest the potential importance of the performance of OGTT in patients with this disorder.

Metabolic syndrome components and disease disability in egyptian multiple sclerosis patients

BACKGROUND

There is limited and inconsistent data on metabolic syndrome (MetS) in multiple sclerosis (MS) patients. The aim of this study was to estimate the frequency of MetS and its components in MS patients and to evaluate their association with disease disability in Egyptian MS patients.

METHODS

A cross-section study was carried out on 60 patients (19 males and 41 females) with relapsing remitting MS. All patients were subjected to full general and neurological examination, laboratory and radiological investigations. Assessment of disease disability was performed using Expanded Disability Status Scale (EDSS) and MetS was diagnosed according to National Cholesterol Education Program Adult Treatment Panel Ш (NCEP-ATP III).

RESULTS

The frequency of MetS in MS patients was 36.7%. Our findings show that 53.3% of MS patients had abdominal obesity, 21.7% had hypertension, 38.3% had diabetes mellitus, 43.3% had elevated triglycerides level and 56.7% had dyslipidemia. Linear regression analysis revealed that body mass index (BMI), dyslipidemia, current medication and disease duration were significantly associated with disease disability.

CONCLUSION

High frequency of MetS and its component was observed in MS patients. Disease duration and current medication as well as some MetS component such as BMI, dyslipidemia, were significantly associated with disability in MS patients.