Can we predict benign multiple sclerosis? Results of a 20-year long-term follow-up study

Deciphering the shift from benign to active relapsing-remitting multiple sclerosis: Insights into T regulatory cell dysfunction and apoptosis regulation

BACKGROUND

Relapsing-remitting multiple sclerosis (RRMS), a common demyelinating disease among young adults, follows a benign course in 10-15% of cases, where patients experience minimal neurological disability for a decade following disease onset. However, there is potential for these benign cases to transition into a clinically active, relapsing state.

OBJECTIVE

To elucidate the biological mechanisms underlying the transition from benign to active RRMS using gene expression analysis.

METHODS

We employed complementary-DNA microarrays to examine peripheral-blood gene expression patterns in patients with benign MS, defined as having a disease duration exceeding 10 years and an Expanded Disability Status Scale (EDSS) score of ≤3.0. We compared the gene expression pattern between patients who switched to active disease (Switching BMS) with those who maintained a benign state (Permanent-BMS) during an additional 5-year follow-up.

RESULTS

We identified two primary mechanisms linked to the transition from benign MS to clinically active disease. The first involves the suppression of regulatory T cell activity, and the second pertains to the dysfunction of nuclear receptor 4 A family-dependent apoptosis. These mechanisms collectively contribute to an augmented autoimmune response and increased disease activity.

CONCLUSIONS

The intricate gene regulatory networks that operate in switching-BMS are related to suppression of immune tolerance and aberrant apoptosis. These findings may lead to new therapeutic targets to prevent the escalation to active disease.

Cerebrospinal fluid camk2a levels at baseline predict long-term progression in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) remains a highly unpredictable disease. Many hope that fluid biomarkers may contribute to better stratification of disease, aiding the personalisation of treatment decisions, ultimately improving patient outcomes.

OBJECTIVE

The objective of this study was to evaluate the predictive value of CSF brain-specific proteins from early in the disease course of MS on long term clinical outcomes.

METHODS

In this study, 34 MS patients had their CSF collected and stored within 5 years of disease onset and were then followed clinically for at least 15 years. CSF concentrations of 64 brain-specific proteins were analyzed in the 34 patient CSF, as well as 19 age and sex-matched controls, using a targeted liquid-chromatography tandem mass spectrometry approach.

RESULTS

We identified six CSF brain-specific proteins that significantly differentiated MS from controls (p < 0.05) and nine proteins that could predict disease course over the next decade. CAMK2A emerged as a biomarker candidate that could discriminate between MS and controls and could predict long-term disease progression.

CONCLUSION

Targeted approaches to identify and quantify biomarkers associated with MS in the CSF may inform on long term MS outcomes. CAMK2A may be one of several candidates, warranting further exploration.

Early miR-320b and miR-25-3p miRNA levels correlate with multiple sclerosis severity at 10 years: a cohort study

BACKGROUND

Multiple sclerosis (MS) is a chronic demyelinating autoimmune disorder which may cause long-term disability. MicroRNA (miRNA) are stable, non-coding molecules that have been identified in our Comprehensive Longitudinal Investigation of Multiple Sclerosis at the Brigham and Women's Hospital (CLIMB)-cohort, as well as other international cohorts, as potential disease biomarkers in MS. However, few studies have evaluated the association of miRNA expression early in the MS disease course with long-term outcomes. Therefore, we aimed to evaluate the potential role of three candidate serum miRNAs previously correlated with MS disability in patients with MS, miR-320b, miR-25-3p and miRNA 486-5p, as early biomarkers of MS disability at 10-year follow-up.

MAIN BODY

We included 144 patients with serum obtained within three years of MS onset. miRNA expression was measured by RNA extraction followed by RT-PCR. Demographic, clinical, brain MRI and other biomarkers were collected. The primary outcome was the association between early miRNA expression and retaining benign MS, defined as EDSS ≤ 2 at 10-year follow-up. Among the 144 patients, 104 were benign and 40 were not benign at 10-year follow-up. 89 (62%) were women, with mean age at onset 37.7 (SD: 9.6) years. Patients who retained benign MS had lower values of miR-25-3p (p = 0.047) and higher miR-320b (p = 0.025) values. Development of SPMS was associated with higher miR-320b (p = 0.002) levels. Brain parenchymal fraction at year 10 was negatively correlated with miR-25-3p (p = 0.0004) and positively correlated with miR-320b (p = 0.006). No association was found between miR-486-5p and any outcome, and 10-year T2-lesion volume was not associated with any miRNA.

CONCLUSIONS

Our results show that miR-320b and miR-25-3p expression are early biomarkers associated with MS severity and brain atrophy. This study provides class III evidence of that miR-320b and miR-25-3p are associated with long-term MS disability which may be a potential tool to risk-stratify patients with MS for early treatment decisions.

Neuromyelitis optica spectrum disorders with a benign course. Analysis of 544 patients

BACKGROUND

Neuromyelitis optica spectrum disorders (NMOSD) most commonly cause severe disability which is related to disease attacks. However, some patients retain good neurological function for a long time after disease onset.

OBJECTIVES

To determine the frequency, demographic and the clinical features of good outcome NMOSD, and analyze their predictive factors.

METHODS

We selected patients who met the 2015 International Panel for NMOSD diagnostic criteria from seven MS Centers. Assessed data included age at disease onset, sex, race, number of attacks within the first and three years from onset, annualized relapsing rate (ARR), total number of attacks, aquaporin-IgG serum status, presence of cerebrospinal fluid (CSF)-specific oligoclonal bands (OCB) and the Expanded Disability Status Scale (EDSS) score at the last follow-up visit. NMOSD was classified as non-benign if patients developed sustained EDSS score >3.0 during the disease course, or benign if patients had EDSS score ≤3.0 after ≥15 years from disease onset. Patients with EDSS <3.0 and disease duration shorter than 15 years were not qualified for classification. We compared the demographic and clinical characteristics of benign and non-benign NMOSD. Logistic regression analysis identified predictive factors of outcome.

RESULTS

There were 16 patients with benign NMOSD (3% of the entire cohort; 4.2% of those qualified for classification; and 4.1% of those who tested positive for aquaporin 4-IgG), and 362 (67.7%) with non-benign NMOSD, whereas 157 (29.3%) did not qualify for classification. All patients with benign NMOSD were female, 75% were Caucasian, 75% tested positive for AQP4-IgG, and 28.6% had CSF-specific OCB. Regression analysis showed that female sex, pediatric onset, and optic neuritis, area postrema syndrome, and brainstem symptoms at disease onset, as well as fewer relapses in the first year and three years from onset, and CSF-specific OCB were more commonly found in benign NMOSD, but the difference did not reach statistical significance. Conversely, non-Caucasian race (OR: 0.29, 95% CI: 0.07-0.99; p = 0.038), myelitis at disease presentation (OR: 0.07, 95% CI: 0.01-0.52; p <0.001), and high ARR (OR: 0.07, 95% CI: 0.01-0.67; p = 0.011) were negative risk factors for benign NMOSD.

CONCLUSION

Benign NMOSD is very rare and occurs more frequently in Caucasians, patients with low ARR, and those who do not have myelitis at disease onset.

Longitudinal Optical Coherence Tomography Measurement of Retinal Ganglion Cell and Nerve Fiber Layer to Assess Benign Course in Multiple Sclerosis

A benign form of multiple sclerosis (BMS) is not easily diagnosed, but changes of the retinal ganglion cell layer-inner plexiform layer (GCL-IPL) and retinal nerve fiber layer (RNFL) may be sensitive to the disease. The aim of this study was to use optical coherence tomography (OCT) to investigate longitudinal changes of GCL-IPL and RNFL in BMS. Eighteen patients with BMS and 22 healthy control (HC) subjects were included, with a mean follow-up period of 32.1 months in BMS and 34.3 months in HC. Mean disease duration in BMS was 23.3 years, with 14 patients left untreated. Unilateral optic neuritis (ON) was found in eight patients. Non-ON eyes showed thinner GCL-IPL layer in the BMS group relative to HC (p < 0.001). The thinning rate of GCL-IPL in non-ON BMS, however, was −0.19 ± 0.15 µm/year vs. 0 ± 0.11 µm/year for HC (p = 0.573, age-adjusted). Thinning rate of RNFL in non-ON BMS was −0.2 ± 0.27 µm/year vs. −0.05 ± 0.3 µm/year for HC (p = 0.454, age adjusted). Conclusions: Thinning rate of the GCL-IPL and RNFL in BMS is similar to the healthy population but differs from the thinning rate in relapsing-remitting MS, presenting a non-invasive OCT-based criterion for assessing a benign course in multiple sclerosis.

Potential biological contributers to the sex difference in multiple sclerosis progression

Multiple sclerosis (MS) is an immune-mediated disease that targets the myelin sheath of central nervous system (CNS) neurons leading to axon injury, neuronal death, and neurological progression. Though women are more highly susceptible to developing MS, men that develop this disease exhibit greater cognitive impairment and accumulate disability more rapidly than women. Magnetic resonance imaging and pathology studies have revealed that the greater neurological progression seen in males correlates with chronic immune activation and increased iron accumulation at the rims of chronic white matter lesions as well as more intensive whole brain and grey matter atrophy and axon loss. Studies in humans and in animal models of MS suggest that male aged microglia do not have a higher propensity for inflammation, but may become more re-active at the rim of white matter lesions as a result of the presence of pro-inflammatory T cells, greater astrocyte activation or iron release from oligodendrocytes in the males. There is also evidence that remyelination is more efficient in aged female than aged male rodents and that male neurons are more susceptible to oxidative and nitrosative stress. Both sex chromosome complement and sex hormones contribute to these sex differences in biology.

Neurofilament light chain as a biomarker for diagnosis of multiple sclerosis

The treatments for multiple sclerosis (MS) have improved over the past 25 years, but now the main question for physicians is deciding who should receive treatment, for how long, and when to switch to other options. These decisions are typically based on treatment tolerance and a reasonable expectation of long-term efficacy. A significant unmet need is the lack of accurate laboratory measurements for diagnosis, and monitoring of treatment response, including deterioration and disease progression. There are few validated biomarkers for MS, and in practice, physicians employ two biomarkers discovered fifty years ago for MS diagnosis, often in combination with MRI scans. These biomarkers are intrathecal IgG and oligoclonal bands in the CSF (cerebrospinal fluid). Neurofilament light chain (NfL) is a relatively new biomarker for MS diagnosis and follow up. Neurofilaments are neuron-specific cytoskeleton proteins that can be measured in various body compartments. NfL is a new biomarker for MS that can be measured in serum samples, but this still needs further study to specify the laboratory cut-off values in clinical practice. In the present review we discuss the evidence for NfL as a reliable biomarker for the early detection and management of MS. Moreover, we highlight the correlation between MRI and NfL, and ask whether they can be combined.

Serum GFAP and NfL levels in benign relapsing-remitting multiple sclerosis

OBJECTIVE

We aimed to investigate serum glial fibrillary acidic protein (GFAP) and serum neurofilament light chain (NfL) levels as potential discriminative biomarkers between benign relapsing-remitting multiple sclerosis (BRRMS) and aggressive relapsing-remitting MS (ARRMS).

METHODS

Serum GFAP and NfL levels were analyzed in patients with BRRMS (n = 34), ARRMS (n = 29), and healthy controls (n = 14) by using Single Molecule Array (Simoa). Patients with ARRMS had been treated with highly effective disease-modifying treatments (DMT) (fingolimod or natalizumab).

RESULTS

Serum GFAP levels in both BRRMS (median 210.19 pg/ml, IQR 163.69-287.19) and in ARRMS (median 188.60 pg/ml, IQR39.23-244.93) were significantly higher (p = 0.035 and p = 0.034, respectively) compared to healthy controls (median 117.93 pg/ml, IQR 60.28-183.83). Serum GFAP levels did not differ between BRRMS and ARRMS. There were no statistical differences in NfL levels between BRRMS, ARRMS and healthy controls. GFAP level was significantly higher (p = 0.04) in BRRMS without DMT (median 216.04 pg/ml, IQR 188.60-274.79) than in those BRRMS patients who had used DMT (median 196.26 pg/ml, IQR 133.33-325.54).

CONCLUSIONS

We found elevated levels of serum GFAP in both BRRMS and ARRMS compared to healthy controls, reflecting astrocytic activation. Serum NfL did not differ between BRRMS and ARRMS, probably due to the stable inflammatory phase of the disease and effective DMT use in ARRMS. Single serum NfL and GFAP measurements cannot separate a patient with BRRMS from effectively treated ARRMS after a long history of the disease, thus consecutive samples are needed in the follow-up.

Serum Neurofilament Light Chain Measurement in MS: Hurdles to Clinical Translation

Measurement of serum neurofilament light chain concentration (sNfL) promises to become a convenient, cost effective and meaningful adjunct for multiple sclerosis (MS) prognostication as well as monitoring disease activity in response to treatment. Despite the remarkable progress and an ever-increasing literature supporting the potential role of sNfL in MS over the last 5 years, a number of hurdles remain before this test can be integrated into routine clinical practice. In this review we highlight these hurdles, broadly classified by concerns relating to clinical validity and analytical validity. After setting out an aspirational roadmap as to how many of these issues can be overcome, we conclude by sharing our vision of the current and future role of sNfL assays in MS clinical practice.

Serum neurofilament light in MS: The first true blood-based biomarker?

A simple blood-derived biomarker is desirable in the routine management of multiple sclerosis (MS) patients and serum neurofilament light chain (sNfL) is the most promising candidate. Although its utility was first shown in cerebrospinal fluid (CSF), technological advancements have enabled reliable detection in serum and less frequently plasma, obviating the need for repeated lumbar punctures. In this review, after defining the knowledge gap in MS management that many hope sNfL could fill, we summarize salient studies demonstrating associations of sNfL levels with outcomes of interest. We group these outcomes into inflammatory activity, progression, treatment response, and prediction/prognosis. Where possible we focus on data from real-world perspective observational cohorts. While acknowledging the limitations of sNfL and highlighting key areas for ongoing work, we conclude with our opinion of the role for sNfL as an objective, convenient, and cost-effective adjunct to clinical assessment. Paving the way for other promising biomarkers both blood-derived and otherwise, sNfL is an incremental step toward precision medicine for MS patients.

Impaired consolidation of visuomotor adaptation in patients with multiple sclerosis

BACKGROUND

Apart from inflammation and neurodegeneration, the individual clinical course of multiple sclerosis (MS) might be determined by differential adaptive capacities of the central nervous system. It has been postulated that the retention of adaptive training effects may be impaired in persons with MS (PwMS).

OBJECTIVE

To investigate motor adaptation and consolidation capacities of people with MS in a visual motor adaptation task (VAT).

METHODS

A total of 23 PwMS (Expanded Disability Status Scale (EDSS) score < 6) and 20 matched healthy controls were recruited. All participants completed three sessions of a VAT where a clockwise rotation angle of 30° was introduced as perturbation during the active learning part of the paradigm. The training session (T₀ ) was repeated after 24 h (T₁ ) and 72 h (T₂ ). Directional errors and parameters of adaptation and retention were evaluated.

RESULTS

PwMS showed similar adaptation and online learning abilities as controls. However, the retention ratio was significantly lower in patients compared to controls at T1 (p = 0.036) and T2 (p = 0.039). There was no significant correlation between the overall adaptation or retention ratio and the EDSS score, respectively.

CONCLUSION

Our findings indicate intact adaptation, but limited consolidation, in patients with mild-to-moderate MS. Future studies are needed to define the neurobiological substrates of this plasticity and the extent to which it can influence clinical outcomes.

Serum neurofilament light chain predicts long term clinical outcomes in multiple sclerosis

Serum neurofilament light chain (NfL) is emerging as an important biomarker in multiple sclerosis (MS). Our objective was to evaluate the prognostic value of serum NfL levels obtained close to the time of MS onset with long-term clinical outcomes. In this prospective cohort study, we identified patients with serum collected within 5 years of first MS symptom onset (baseline) with more than 15 years of routine clinical follow-up. Levels of serum NfL were quantified in patients and matched controls using digital immunoassay (SiMoA HD-1 Analyzer, Quanterix). Sixty-seven patients had a median follow-up of 18.9 years (range 15.0–27.0). The median serum NfL level in patient baseline samples was 10.1 pg/mL, 38.5% higher than median levels in 37 controls (7.26 pg/mL, p = 0.004). Baseline NfL level was most helpful as a sensitive predictive marker to rule out progression; patients with levels less 7.62 pg/mL were 4.3 times less likely to develop an EDSS score of ≥ 4 (p = 0.001) and 7.1 times less likely to develop progressive MS (p = 0.054). Patients with the highest NfL levels (3rd-tertile, > 13.2 pg/mL) progressed most rapidly with an EDSS annual rate of 0.16 (p = 0.004), remaining significant after adjustment for sex, age, and disease-modifying treatment (p = 0.022). This study demonstrates that baseline sNfL is associated with long term clinical disease progression. sNfL may be a sensitive marker of subsequent poor clinical outcomes.

Multiple Sclerosis Severity Score: Concept and applications

Severity score represents disease duration-adjusted mean rank of disability in multiple sclerosis (MS) patients from the reference population. This measure allows one to compare the relative rates of disease progression among patients, patient subgroups, and across epochs, which opens up new question of what accounts for the observed differences in severity, and can be used to assess correlation between disease severity and clinical, radiologic, immunologic, genetic, and environmental variables of interest. Severity score can also prove useful for developing prognostic tools in MS. This article discusses the diverse applications of severity score concept in MS research, and (re)introduces Herbert's proposal of severity-based MS classification in the context of variability of MS severity.

Precision medicine in the multiple sclerosis clinic: Selecting the right patient for the right treatment

Multiple sclerosis (MS) is a chronic, inflammatory disease of the central nervous system (CNS), affecting patients of all ages, causing neurologic disability if inadequately treated. Some patients have a relatively benign disease course without significant disability after decades, while a more aggressive course ensues in others and disability progression occurs after only several years. Certain risk factors confer a higher chance of a patient having aggressive MS. Currently over 15 disease-modifying treatments (DMTs) are approved for MS with different efficacy and safety profiles. Deciding which DMT to use in a specific patient requires a careful analysis of a patient’s disease course for high-risk factors for early progression, consideration of the efficacy and safety profile for potential therapy, as well as understanding of a patient’s lifestyle and expectations. The integration of these factors is the art of precision medicine, a necessary practice in the treatment of patients with MS.

Functional connectivity impairment of postcentral gyrus in relapsing-remitting multiple sclerosis with somatosensory disorder

PURPOSE

To characterize the spatial patterns of functional connectivity(FC) changes of whole brain in RRMS with somatosensory disorder(RRMS-SS) and to investigate the correlation between abnormal FC and clinical scores.

METHODS

Twenty-six RRMS-SS patients and 23 healthy controls(HC) underwent resting-state functional magnetic resonance imaging(RS-fMRI) scanning. The clinical scores were collected including Expanded Disability Status Scores(EDSS), Disease Duration and Somatosensory Evaluation by the Fugl-Meyer sensory score(FMSS). With the voxel-wise methods, RS-fMRI data were analyzed using REST software, to assess the FC of the postcentral gyrus(PoCG). Correlation between clinical variables and the strength of FC was analyzed.

RESULTS

Compared with HC, the left postcentral-based FC showed decreased FC of the right cerebellum_8, lingual lobe and Rolandic operculum gyrus, and increased FC of the left middle frontal lobe. The right postcentral-based FC revealed decreased FC with the right Heschl's gyrus lobule, and increased FC with bilateral middle frontal lobe (p <  0.001, AlphaSim corrected). Correlation analysis revealed that the FC of altered brain regions was associated with FMSS, EDSS and disease duration.

CONCLUSION

The functional connectivity of PoCG at RS-fMRI has multi-network changes in patients with RRMS-SS. This suggests a complex pattern of abnormal connections between the somatosensory network regions and the whole brain. Moreover, the correlation between the FC and the FMSS, such as the left middle frontal lobe and the right PoCG, indicate that these two brain regions play an important role in RRMS-SS.

How common is truly benign MS in a UK population?

OBJECTIVES

The prevalence and definition of benign multiple sclerosis (BMS) remain controversial. Most definitions are based on the Expanded Disability Status Scale (EDSS), not encompassing the wider impact of disease. The explanation for favourable outcomes remains unclear. We aim to provide a detailed characterisation of patients with low EDSS scores at long disease durations.

METHODS

We screened a population-based registry containing 3062 people with MS to identify individuals with unlimited walking ability at disease durations >15 years. A representative cohort underwent detailed clinical assessment and classified as having BMS according to EDSS score <3, no significant fatigue, mood disturbance, cognitive impairment or disrupted employment, and had not received a disease-modifying therapy. We determined patient-reported perceptions of MS status and made comparisons with EDSS-based definitions.

RESULTS

Of 1049 patients with disease duration of >15 years, 200 (19.1%) had most recent EDSS score <4.0. Detailed contemporary clinical assessment of a representative sample of 60 of these patients revealed 48 (80%) had an EDSS score of <4.0, 35 (58%) <3.0 and 16 (27%) <2.0. Only nine (15%) fulfilled our criteria for BMS; impaired cognition (57%) and effects on employment (52%) the most common causes for exclusion. Meanwhile, 33/60 (69%) patients considered their disease benign. Population frequency for BMS was estimated at 2.9% (95% CI 2.0 to 4.1).

CONCLUSIONS

Comprehensive assessment reveals a small minority of people with MS who appear genuinely benign after 15 years. Study of such individuals may uncover insights about disease pathogenesis. However, discrepancy between patient perception and clinician perception of BMS undermines use of the term 'benign' in clinical settings.

Serum neurofilament light chain is a biomarker of acute and chronic neuronal damage in early multiple sclerosis

BACKGROUND

Monitoring neuronal injury remains one key challenge in early relapsing-remitting multiple sclerosis (RRMS) patients. Upon axonal damage, neurofilament - a major component of the neuro-axonal cytoskeleton - is released into the cerebrospinal fluid (CSF) and subsequently peripheral blood.

OBJECTIVE

To investigate the relevance of serum neurofilament light chain (sNfL) for acute and chronic axonal damage in early RRMS.

METHODS

sNfL levels were determined in 74 patients (63 therapy-naive) with recently diagnosed clinically isolated syndrome (CIS) or RRMS using Single Molecule Array technology. Standardized 3 T magnetic resonance imaging (MRI) was performed at baseline and 1-3 consecutive follow-ups (42 patients; range: 6-37 months).

RESULTS

Baseline sNfL correlated significantly with T2 lesion volume ( r = 0.555, p < 0.0001). There was no correlation between baseline sNfL and age, Expanded Disability Status Scale (EDSS) score or other calculated MRI measures. However, T2 lesion volume increased ( r = 0.67, p < 0.0001) and brain parenchymal volume decreased more rapidly in patients with higher baseline sNfL ( r = -0.623, p = 0.0004). Gd-enhancing lesions correlated positively with sNfL levels. Initiation of disease-modifying treatment led to a significant decrease in sNfL levels.

CONCLUSION

sNfL indicates acute inflammation as demonstrated by correlation with Gd+ lesions. It is a promising biomarker for neuro-axonal damage in early multiple sclerosis (MS) patients, since higher baseline sNfL levels predicted future brain atrophy within 2 years.

Natural history of benign multiple sclerosis: Clinical and HLA correlates in a Western Australian cohort

BACKGROUND

Benign multiple sclerosis (BMS) is a controversial term that has been used for MS patients with minimal disability decades after disease onset. Herein, we evaluated disease status after 20 years in a Western Australian cohort defined as BMS based on an Expanded Disability Status Scale (EDSS) score ≤ 3.0 at 10 years from onset.

METHODS

MS patients with an EDSS score ≤ 3.0 at 10 years from onset and minimum of 20 years follow up were included in the study. The 20-year EDSS score was considered the primary outcome. Associations with demographic and clinical characteristics and HLA-DRB1 genotype were investigated.

RESULTS

Among 120 patients with a benign course at 10 years, 78 (65%) remained benign at the 20-year follow up, but patients with an EDSS ≥ 2.5 were more likely to go on to develop more severe disability in the next decade. When considering factors associated with an increase in EDSS score ≤ 1 from 10 to 20 years, indicating limited progression, apart from the EDSS score at 10 years, poly-symptomatic presentation (p = 0.004) and cerebellar/brainstem mono-symptomatic presentation (p = 0.016) were independently associated with more rapid progression compared with other mono-symptomatic presentations. Carriage of the high risk HLA-DRB1*1501 allele was marginally associated with slower progression.

CONCLUSIONS

In this geographically isolated MS cohort of predominantly Anglo-Celtic origin clinical progression in the benign MS group was similar to that in other published series from Western countries. These results are in keeping with the view that patients labeled as benign MS are part of a heterogeneous continuum of disease progression and do not possess unique clinical characteristics. Possible genetic determinants of a benign course warrant further investigation.

Cardiac repolarization evolves differently during the course of benign and disabling multiple sclerosis

BACKGROUND

Cardiac repolarization is modulated by the autonomic nervous system. Even though multiple sclerosis associates with prolonged cardiac repolarization the physiology responsible for the phenomenon remains unknown.

OBJECTIVE

To study in longitudinal setting whether the patients with confirmed benign and disabling outcome of relapsing-remitting multiple sclerosis (RRMS) differ in regard to changes of cardiac repolarization.

METHODS

Total of 43 patients, 26% with benign (EDSS ≤2 at least 10y after onset symptom) and 74% with disabling (EDSS >2 at least 10y after onset symptom) RRMS, having 12-lead electrocardiogram (ECG) recorded at the time of onset symptom (ECG1) and for follow-up (ECG2), were studied. Heart rate (HR) corrected QT intervals (QTc) reflecting cardiac repolarization were assessed.

RESULTS

The time interval between ECG1 and ECG2 showed no statistical difference between benign (7.8 ± 4.8y) and disabling (10.2 ± 5.6y; p = .211) RRMS. Patients with benign and disabling RRMS showed similar values of HR (66±9 bpm vs 73 ± 15 bpm; p=.146) and QTc (403 ± 13 ms vs 408 ± 19 ms; p = .450) at the time of ECG1. However, at the time of ECG2, HR was higher (79 ± 14 bpm vs 65 ± 10 bpm; p = .004) and QTc was longer (420 ± 24 ms vs 400 ± 15 ms; p = .012) in patients with disabling than benign RRMS. Correspondingly, HR increased (p = .063) and QTc prolonged (p = .014) during the disease course only in patients with disabling RRMS.

CONCLUSIONS

Deterioration of cardiac autonomic regulation during the disease course associates with disabling but not with benign RRMS. Our findings suggest that assessment of cardiac autonomic regulation should be included in the evaluation of RRMS disease course. In addition, patients with disabling RRMS might be prone to unfavorable cardiovascular outcome also due to deterioration of autonomic nervous system.

Combination of cuprizone and experimental autoimmune encephalomyelitis to study inflammatory brain lesion formation and progression

Brain-intrinsic degenerative cascades are a proposed factor driving inflammatory lesion formation in multiple sclerosis (MS) patients. We recently described a model combining noninflammatory cytodegeneration (via cuprizone) with the classic active experimental autoimmune encephalomyelitis (Cup/EAE model), which exhibits inflammatory forebrain lesions. Here, we describe the histopathological characteristics and progression of these Cup/EAE lesions. We show that inflammatory lesions develop at various topographical sites in the forebrain, including white matter tracts and cortical and subcortical grey matter areas. The lesions are characterized by focal demyelination, discontinuation of the perivascular glia limitans, focal axonal damage, and neutrophil granulocyte extravasation. Transgenic mice with enhanced green fluorescent protein-expressing microglia and red fluorescent protein-expressing monocytes reveal that both myeloid cell populations contribute to forebrain inflammatory infiltrates. EAE-triggered inflammatory cerebellar lesions were augmented in mice pre-intoxicated with cuprizone. Gene expression studies suggest roles of the chemokines Cxcl10, Ccl2, and Ccl3 in inflammatory lesion formation. Finally, follow-up experiments in Cup/EAE mice with chronic disease revealed that forebrain, but not spinal cord, lesions undergo spontaneous reorganization and repair. This study underpins the significance of brain-intrinsic degenerative cascades for immune cell recruitment and, in consequence, MS lesion formation.