Characterization of cortico-meningeal translocator protein expression in multiple sclerosis.

Compartmentalized meningeal inflammation is thought to represent one of the key players in the pathogenesis of cortical demyelination in multiple sclerosis. PET targeting the 18 kDa mitochondrial translocator protein (TSPO) is a molecular-specific approach to quantifying immune cell-mediated density in the cortico-meningeal tissue compartment in vivo. This study aimed to characterize cortical and meningeal TSPO expression in a heterogeneous cohort of multiple sclerosis cases using in vivo simultaneous MR-PET with 11C-PBR28, a second-generation TSPO radioligand, and ex vivo immunohistochemistry. Forty-nine multiple sclerosis patients (21 with secondary progressive and 28 with relapsing-remitting multiple sclerosis) with mixed or high affinity binding for 11C-PBR28 underwent 90-min 11C-PBR28 simultaneous MR-PET. Tracer binding was measured using 60-90 min normalized standardized uptake value ratios sampled at mid-cortical depth and ∼3 mm above the pial surface. Data in multiple sclerosis patients were compared to 21 age-matched healthy controls. To characterize the nature of 11C-PBR28 PET uptake, the meningeal and cortical lesion cellular expression of TSPO was further described in post-mortem brain tissue from 20 cases with secondary progressive multiple sclerosis and five age-matched healthy donors. Relative to healthy controls, patients with multiple sclerosis exhibited abnormally increased TSPO signal in the cortex and meningeal tissue, diffusively in progressive disease and more localized in relapsing-remitting multiple sclerosis. In multiple sclerosis, increased meningeal TSPO levels were associated with increased Expanded Disability Status Scale scores (P = 0.007, by linear regression). Immunohistochemistry, validated using in situ sequencing analysis, revealed increased TSPO expression in the meninges and adjacent subpial cortical lesions of post-mortem secondary progressive multiple sclerosis cases relative to control tissue. In these cases, increased TSPO expression was related to meningeal inflammation. Translocator protein immunostaining was detected on meningeal MHC-class II+ macrophages and cortical-activated MHC-class II+ TMEM119+ microglia. In vivo arterial blood data and neuropathology showed that endothelial binding did not significantly account for increased TSPO cortico-meningeal expression in multiple sclerosis. Our findings support the use of TSPO-PET in multiple sclerosis for imaging in vivo inflammation in the cortico-meningeal brain tissue compartment and provide in vivo evidence implicating meningeal inflammation in the pathogenesis of the disease.

White matter paramagnetic rim and non-rim lesions share a periventricular gradient in multiple sclerosis: A 7-T imaging study.

BACKGROUND: Paramagnetic rim white matter (WM) lesions (PRL) are thought to be a main driver of non-relapsing multiple sclerosis (MS) progression. It is unknown whether cerebrospinal fluid (CSF)-soluble factors diffusing from the ventricles contribute to PRL formation. OBJECTIVE: To investigate the distribution of PRL and non-rim brain WM lesions as a function of distance from ventricular CSF, their relationship with cortical lesions, the contribution of lesion phenotype, and localization to neurological disability. METHODS: Lesion count and volume of PRL, non-rim WM, leukocortical lesion (LCL), and subpial/intracortical lesions were obtained at 7-T. The brain WM was divided into 1-mm-thick concentric rings radiating from the ventricles to extract PRL and non-rim WM lesion volume from each ring. RESULTS: In total, 61 MS patients with ⩾1 PRL were included in the study. Both PRL and non-rim WM lesion volumes were the highest in the periventricular WM and declined with increasing distance from ventricles. A CSF distance-independent association was found between non-rim WM lesions, PRL, and LCL, but not subpial/intracortical lesions. Periventricular non-rim WM lesion volume was the strongest predictor of neurological disability. CONCLUSIONS: Non-rim and PRL share a gradient of distribution from the ventricles toward the cortex, suggesting that CSF proximity equally impacts the prevalence of both lesion phenotypes.

Evidence of diffuse cerebellar neuroinflammation in multiple sclerosis by 11C-PBR28 MR-PET.

BACKGROUND: Activated microglia, which can be detected in vivo by 11C-PBR28 positron emission tomography (PET), represent a main component of MS pathology in the brain. Their role in the cerebellum is still unexplored, although cerebellar involvement in MS is frequent and accounts for disability progression. OBJECTIVES: We aimed at characterizing cerebellar neuroinflammation in MS patients compared to healthy subjects by combining 11C-PBR28 MRI-Positron Emission Tomography (MR-PET) with 7 Tesla (T) MRI and assessing its relationship with brain neuroinflammation and clinical outcome measures. METHODS: Twenty-eight MS patients and 16 healthy controls underwent 11C-PBR28 MR-PET to measure microglia activation in normal appearing cerebellum and lesions segmented from 7 T scans. Patients were evaluated using the Expanded Disability Status Scale and Symbol Digit Modalities Test. 11C-PBR28 binding was assessed in regions of interest using 60-90 minutes standardized uptake values normalized by a pseudo-reference region in the brain normal appearing white matter. Multilinear regression was used to compare tracer uptake in MS and healthy controls and assess correlations with clinical scores. RESULTS: In all cerebellar regions examined, MS patients showed abnormally increased tracer uptake, which correlated with cognitive and neurological disability. CONCLUSION: Neuroinflammation is widespread in the cerebellum of patients with MS and related to neurological disability and cognitive impairment.

In vivo characterization of microglia and myelin relation in multiple sclerosis by combined 11C-PBR28 PET and synthetic MRI.

BACKGROUND: The in vivo relation between microglia activation and demyelination in multiple sclerosis is still unclear. OBJECTIVE: We combined 11C-PBR28 positron emission tomography and rapid estimation of myelin for diagnostic imaging (REMyDI) to characterize the relation between these pathological processes in a heterogeneous MS cohort. METHODS: 11C-PBR28 standardized uptake values normalized by a pseudo-reference region (SUVR) were used to measure activated microglia. A voxelwise analysis compared 11C-PBR28 SUVR in the white matter of 38 MS patients and 16 matched healthy controls. The relative difference in SUVR served as a threshold to classify patients' lesioned, perilesional and normal-appearing white matter as active or inactive. REMyDI was acquired in 27 MS patients for assessing myelin content in active and inactive white matter and its relationship with SUVR. Finally, we investigated the contribution of radiological metrics to clinical outcomes. RESULTS: 11C-PBR28 SUVR were abnormally higher in several white matter areas in MS. Myelin content was lower in active compared to inactive corresponding white matter regions. An inverse correlation between SUVR and myelin content was found. Radiological metrics correlated with both neurological and cognitive impairment. CONCLUSION: our data suggest an inverse relation of microglia activation and myelination, particularly in perilesional white matter tissue.

Cortical and phase rim lesions on 7 T MRI as markers of multiple sclerosis disease progression.

In multiple sclerosis, individual lesion-type patterns on magnetic resonance imaging might be valuable for predicting clinical outcome and monitoring treatment effects. Neuropathological and imaging studies consistently show that cortical lesions contribute to disease progression. The presence of chronic active white matter lesions harbouring a paramagnetic rim on susceptibility-weighted magnetic resonance imaging has also been associated with an aggressive form of multiple sclerosis. It is, however, still uncertain how these two types of lesions relate to each other, or which one plays a greater role in disability progression. In this prospective, longitudinal study in 100 multiple sclerosis patients (74 relapsing-remitting, 26 secondary progressive), we used ultra-high field 7-T susceptibility imaging to characterize cortical and rim lesion presence and evolution. Clinical evaluations were obtained over a mean period of 3.2 years in 71 patients, 46 of which had a follow-up magnetic resonance imaging. At baseline, cortical and rim lesions were identified in 96% and 63% of patients, respectively. Rim lesion prevalence was similar across disease stages. Patients with rim lesions had higher cortical and overall white matter lesion load than subjects without rim lesions (P = 0.018-0.05). Altogether, cortical lesions increased by both count and volume (P = 0.004) over time, while rim lesions expanded their volume (P = 0.023) whilst lacking new rim lesions; rimless white matter lesions increased their count but decreased their volume (P = 0.016). We used a modern machine learning algorithm based on extreme gradient boosting techniques to assess the cumulative power as well as the individual importance of cortical and rim lesion types in predicting disease stage and disability progression, alongside with more traditional imaging markers. The most influential imaging features that discriminated between multiple sclerosis stages (area under the curve±standard deviation = 0.82 ± 0.08) included, as expected, the normalized white matter and thalamic volume, white matter lesion volume, but also leukocortical lesion volume. Subarachnoid cerebrospinal fluid and leukocortical lesion volumes, along with rim lesion volume were the most important predictors of Expanded Disability Status Scale progression (area under the curve±standard deviation = 0.69 ± 0.12). Taken together, these results indicate that while cortical lesions are extremely frequent in multiple sclerosis, rim lesion development occurs only in a subset of patients. Both, however, persist over time and relate to disease progression. Their combined assessment is needed to improve the ability of identifying multiple sclerosis patients at risk of progressing disease.

The relevance of multiple sclerosis cortical lesions on cortical thinning and their clinical impact as assessed by 7.0-T MRI.

OBJECTIVE: This study aimed to investigate at 7.0-T MRI a) the role of multiple sclerosis (MS) cortical lesions in cortical tissue loss b) their relation to neurological disability. METHODS: In 76 relapsing remitting and 26 secondary progressive MS patients (N = 102) and 56 healthy subjects 7.0-T T2*-weighted images were acquired for lesion segmentation; 3.0-T T1-weighted structural scans for cortical surface reconstruction/cortical thickness estimation. Patients were dichotomized based on the median cortical lesion volume in low and high cortical lesion load groups that differed by age, MS phenotype and degree of neurological disability. Group differences in cortical thickness were tested on reconstructed cortical surface. Patients were evaluated clinically by means of the Expanded Disability Status Scale (EDSS). RESULTS: Cortical lesions were detected in 96% of patients. White matter lesion load was greater in the high than in the low cortical lesion load MS group (p = 0.01). Both MS groups disclosed clusters (prevalently parietal) of cortical thinning relative to healthy subjects, though these regions did not show the highest cortical lesion density, which predominantly involved frontal regions. Cortical thickness decreased on average by 0.37 mm, (p = 0.002) in MS patients for each unit standard deviation change in white matter lesion volume. The odds of having a higher EDSS were associated with cortical lesion volume (1.78, p = 0.01) and disease duration (1.15, p < 0.001). CONCLUSION: Cortical thinning in MS is not directly related to cortical lesion load but rather with white matter lesion volume. Neurological disability in MS is better explained by cortical lesion volume assessment.

Effect on Cognition of Estroprogestins Combined with Interferon Beta in Multiple Sclerosis: Analysis of Secondary Outcomes from a Randomised Controlled Trial.

INTRODUCTION: Cognitive impairment is a disabling symptom in multiple sclerosis (MS). While its management remains challenging, beneficial effects on cognition of interferon beta (IFN-ß) have been reported and a positive effect from estroprogestins has been hypothesised, suggesting that the combination of the two medications in women with MS could offer a promising treatment strategy. OBJECTIVES: We investigated whether a combination of estroprogestins and IFN-ß can improve cognition in women with MS. METHODS: Women with relapsing-remitting (RR) MS were randomly assigned (1:1:1) to receive subcutaneous IFN-ß-1a (Rebif®, Merck Serono, Geneva, Switzerland) 44 mcg three times a week (tiw) (group 1), subcutaneous IFN-ß-1a 44 mcg tiw plus ethinyl estradiol 20 mcg and desogestrel 150 mcg (Mercilon®, MSD Italia SRL, Rome, Italy) (group 2) or subcutaneous IFN-ß-1a 44 mcg tiw plus ethinyl estradiol 40 mcg and desogestrel 125 mcg (Gracial®, Organon Italia S.p.A., Rome, Italy) (group 3) in a randomised controlled trial, for which we report the analysis of secondary outcomes. At baseline and at 24 months, all patients underwent magnetic resonance imaging (MRI) and a comprehensive cognitive assessment, including Rao's Brief Repeatable Battery (RBRB) and questionnaires for depression, fatigue and quality of life. Failure in at least two of the RBRB tests defined 'cognitive impairment'. RESULTS: At baseline, there was no difference in the proportion of cognitively impaired patients. At month 24, the proportion of patients with cognitive impairment was lower in group 3 (34.8%) than in group 1 (47.6%) (p = 0.03). The risk of developing cognitive impairment over 24 months was lower in group 3 (p = 0.02). Mood and fatigue scores were comparable across the groups over time at both time points. However, at month 24, group 3 showed worsening on the sexual function subscale of the 54-item MS quality-of-life questionnaire (p = 0.03). CONCLUSIONS: This study suggests that the combination of high-dose estroprogestins and IFN-ß may have positive effects on cognition. However, the effect of this treatment on sexual function requires caution to be exercised. Protocol Number NCT00151801, registered in ClinicalTrials.gov.

Oral contraceptives combined with interferon ß in multiple sclerosis.

OBJECTIVE: To test the effect of oral contraceptives (OCs) in combination with interferon ß (IFN-ß) on disease activity in patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: One hundred fifty women with RRMS were randomized in a 1:1:1 ratio to receive IFN-ß-1a subcutaneously (SC) only (group 1), IFN-ß-1a SC plus ethinylstradiol 20 µg and desogestrel 150 µg (group 2), or IFN-ß-1a SC plus ethinylestradiol 40 µg and desogestrel 125 µg (group 3). The primary endpoint was the cumulative number of combined unique active (CUA) lesions on brain MRI at week 96. Secondary endpoints included MRI and clinical and safety measures. RESULTS: The estimated number of cumulative CUA lesions at week 96 was 0.98 (95% confidence interval [CI] 0.81-1.14) in group 1, 0.84 (95% CI 0.66-1.02) in group 2, and 0.72 (95% CI 0.53-0.91) in group 3, with a decrease of 14.1% (p = 0.24) and 26.5% (p = 0.04) when comparing group 1 with groups 2 and 3, respectively. The number of patients with no gadolinium-enhancing lesions was greater in group 3 than in group 1 (p = 0.03). No significant differences were detected in other secondary endpoints. IFN-ß or OC discontinuations were equally distributed across groups. CONCLUSIONS: Our results translate the observations derived from experimental models to patients, supporting the anti-inflammatory effects of OCs with high-dose estrogens, and suggest possible directions for future research. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that in women with RRMS, IFN-ß plus ethinylstradiol and desogestrel decreases the cumulative number of active brain MRI lesions compared with IFN-ß alone.