Multiple Sclerosis Pathology

Systemic exposure to a single dose of ferucarbotran aggravates neuroinflammation in a murine model of experimental autoimmune encephalomyelitis

Background

Medicinal preparations of iron oxide nanoparticles (IONPs) have been used as MRI contrast agents for the diagnosis of hepatic tumors and the assessment of neuroinflammation and blood–brain barrier integrity. However, it remains mostly unclear whether exposure to IONPs affects neuroinflammation under disease conditions. The present study aims to investigate the impact of IONPs on autoimmune-mediated neuroinflammation using a murine model of experimental autoimmune encephalomyelitis (EAE) that mimics human multiple sclerosis.

Methods

Mice were either left untreated or immunized with myelin oligodendrocyte glyco-protein on day 0 followed by two injections of pertussis toxin for EAE induction. The EAE mice were intravenously administered with a single dose of the carboxydextran-coated IONPs, ferucarbotran (20 mg Fe/kg) and/or saline (as vehicle) on day 18. Symptoms of EAE were daily monitored until the mice were killed on day 30. Tissue sections of the brain and spinal cord were prepared for histopathological examinations. Iron deposition, neuron demyelination and inflammatory cell infiltration were examined using histochemical staining. The infiltration of microglial and T cells, and cytokine expression were examined by immunohistochemical staining and/or reverse transcription polymerase chain reaction (RT-PCR).

Results

Iron deposition was detected in both the brain and spinal cord of EAE mice 3 days post-ferucarbotran treatment. The clinical and pathological scores of EAE, percentage of myelin loss and infiltration of inflammatory cells into the spinal cord were significantly deteriorated in EAE mice treated with ferucarbotran. Furthermore, ferucarbotran treatment increased the number of CD3⁺, Iba-1⁺, IL-6⁺, Iba-1⁺TNF-α⁺ and CD3⁺IFN-γ⁺ cells in the spinal cord of EAE mice.

Conclusion

A single exposure to ferucarbotran exacerbated neuroinflammation and disease severity of EAE, which might be attributed to the enhanced activation of microglia and T cells. These results demonstrated that the pro-inflammatory effect of ferucarbotran on the central nervous system is closely associated with the deterioration of autoimmunity.

Social Mind and Long-Lasting Disease: Focus on Affective and Cognitive Theory of Mind in Multiple Sclerosis

The role of social cognition, including theory of mind (ToM), in affecting quality of life (QoL) along the course of diseases has been reported. This is a considerable aspect in chronic pathologies, such as multiple sclerosis (MS), in which supporting and maintaining QoL is of crucial importance. We aimed to investigate the relation between ToM, clinical variables and neuropsychological profile in a cohort of adults with long lasting disease, such as different clinical MS phenotypes (Relapsing Remitting -RR- versus Progressive -Pr). In particular, our study focuses on (1) how (affective and cognitive) ToM impairment occurs in different phenotypes, (2) whether MS ToM impairment is secondary to or independent from cognitive deficit and (3) whether ToM deficit impacts QoL. 42 adults with MS (18 M: 24 F, 52.38 ± 10.31 mean age, 21.24 ± 10.94 mean disease duration, 26 RR and 16 Pr) and 26 matched healthy controls (HC) (7 M: 19 F, 51.35 ± 12.42 mean age) were screened with a neuropsychological and ToM battery, assessing both affective and cognitive components. We found statistically significant groups differences in cognitive but not affective ToM, with a lower performance in PrMS than those with a RRMS disease course. Also, significant predictive effects of neuropsychological tests on ToM were identified in MS group. Finally, MS people with different level of affective ToM differed significantly in QoL. ToM deficit in moderately disabled people with MS involves cognitive but not affective ToM components with implications on QoL. It also appears to be related to cognitive performance. As neurological and neurocognitive profiles influence mentalizing in MS, ToM evaluation should be considered for inclusion in clinical screening.

Polarized microglia do not influence oligodendrocyte lineage cells via astrocytes

Microglia can adopt different activation patterns, ranging from a pro-inflammatory M1- to an anti-inflammatory M2-like phenotype in which they play crucial roles in various neuroinflammatory diseases. M2-like microglia are described to drive remyelination, whereas detrimental effects have been attributed to M1-like microglia. How polarized microglia might act on oligodendrocyte lineage cells indirectly by influencing astrocytes has not been studied in detail. In this study, conditioned media from polarized murine microglia were used to treat astrocytes and astrocytic gene expression was analyzed by microarray for genes known to influence oligodendrocyte lineage cells. Supernatants of astrocytes previously stimulated with soluble effectors from polarized microglia were used to investigate effects on oligodendrocyte precursor cells (OPC). Growth factors known to induce OPC proliferation, differentiation, and survival were upregulated in astrocytes treated with supernatants from M1-like microglia while M0- and M2-like microglia only had negligible effects on the expression of these factors in astrocytes. Despite the upregulation of these factors in M1 stimulated astrocytes there were no significant effects on OPC in vitro. All astrocyte supernatants induced proliferation of A2B5⁺ OPC and inhibited differentiation of OPC into mature oligodendrocytes. A trend toward enhanced migration of OPC was induced by M1 stimulated astrocytes. Our data suggest that M1-like microglia may potentially influence OPC and remyelination indirectly via astrocytes by inducing the expression of respective growth factors, however, this has no significant effect in addition to the already strong effects of unstimulated astrocytes on OPC. Nevertheless, the observed effect may be of relevance in other pathophysiological scenarios.

A GMCSF-Neuroantigen Tolerogenic Vaccine Elicits Systemic Lymphocytosis of CD4+ CD25high FOXP3+ Regulatory T Cells in Myelin-Specific TCR Transgenic Mice Contingent Upon Low-Efficiency T Cell Antigen Receptor Recognition

Previous studies showed that single-chain fusion proteins comprised of GM-CSF and major encephalitogenic peptides of myelin, when injected subcutaneously in saline, were potent tolerogenic vaccines that suppressed experimental autoimmune encephalomyelitis (EAE) in rats and mice. These tolerogenic vaccines exhibited dominant suppressive activity in inflammatory environments even when emulsified in Complete Freund's Adjuvant (CFA). The current study provides evidence that the mechanism of tolerance was dependent upon vaccine-induced regulatory CD25⁺ T cells (Tregs), because treatment of mice with the Treg-depleting anti-CD25 mAb PC61 reversed tolerance. To assess tolerogenic mechanisms, we focused on 2D2-FIG mice, which have a transgenic T cell repertoire that recognizes myelin oligodendrocyte glycoprotein peptide MOG35-55 as a low-affinity ligand and the neurofilament medium peptide NFM13-37 as a high-affinity ligand. Notably, a single subcutaneous vaccination of GMCSF-MOG in saline elicited a major population of FOXP3⁺ Tregs that appeared within 3 days, was sustained over several weeks, expressed canonical Treg markers, and was present systemically at high frequencies in the blood, spleen, and lymph nodes. Subcutaneous and intravenous injections of GMCSF-MOG were equally effective for induction of FOXP3⁺ Tregs. Repeated booster vaccinations with GMCSF-MOG elicited FOXP3 expression in over 40% of all circulating T cells. Covalent linkage of GM-CSF with MOG35-55 was required for Treg induction whereas vaccination with GM-CSF and MOG35-55 as separate molecules lacked Treg-inductive activity. GMCSF-MOG elicited high levels of Tregs even when administered in immunogenic adjuvants such as CFA or Alum. Conversely, incorporation of GM-CSF and MOG35-55 as separate molecules in CFA did not support Treg induction. The ability of the vaccine to induce Tregs was dependent upon the efficiency of T cell antigen recognition, because vaccination of 2D2-FIG or OTII-FIG mice with the high-affinity ligands GMCSF-NFM or GMCSF-OVA (Ovalbumin323-339), respectively, did not elicit Tregs. Comparison of 2D2-FIG and 2D2-FIG-Rag1 ^-/- strains revealed that GMCSF-MOG may predominantly drive Treg expansion because the kinetics of vaccine-induced Treg emergence was a function of pre-existing Treg levels. In conclusion, these findings indicate that the antigenic domain of the GMCSF-NAg tolerogenic vaccine is critical in setting the balance between regulatory and conventional T cell responses in both quiescent and inflammatory environments.

Structural connectivity in multiple sclerosis and modeling of disconnection

BACKGROUND

Multiple sclerosis (MS) is characterized by focal white matter damage, and when the brain is modeled as a network, lesions can be treated as disconnection events.

OBJECTIVE

To evaluate whether modeling disconnection caused by lesions helps explain motor and cognitive impairment in MS.

METHODS

Pathways connecting 116 cortical regions were reconstructed with magnetic resonance imaging (MRI) tractography from diffusion tensors averaged across healthy controls (HCs); maps of pathways were applied to 227 relapse-onset MS patients and 50 HCs to derive structural connectivity. Then, the likelihood of individual connections passing through lesions was used to model disconnection. Patients were grouped according to clinical phenotype (113 relapsing-remitting multiple sclerosis (RRMS), 69 secondary progressive multiple sclerosis (SPMS), 45 benign MS), and then network metrics were compared between groups (analysis of variance (ANOVA)) and correlated with motor and cognitive scores (linear regression).

RESULTS

Global metrics differentiated RRMS from SPMS and benign MS patients, but not benign from SPMS patients. Nodal connectivity strength replicated global results. After disconnection, few nodes were significantly different between benign MS and RRMS patients. Correlations revealed nodes pertinent to motor and cognitive dysfunctions; these became slightly stronger after disconnection.

CONCLUSION

Connectivity did not change greatly after modeled disconnection, suggesting that the brain network is robust against damage caused by MS lesions.

The relationship between corticospinal tract integrity and lower-extremity strength is attenuated when controlling for age and sex in multiple sclerosis

Muscle weakness, particularly in the lower-extremities, is common in multiple sclerosis (MS) and seemingly results from damage along white matter pathways in the central nervous system including the corticospinal tract (CST). This study examined CST structural integrity indicated by diffusion tensor imaging (DTI) related metrics (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD], and axial diffusivity [AD]) as correlates of knee flexor (KF) and knee extensor (KE) muscle strength in MS. We included 36 persons with MS who underwent MRI and measurements of peak KE and KF strength using an isokinetic dynamometer. We examined associations using bivariate Spearman (rs) and partial Spearman correlation (prs) analyses controlling for age and sex. Peak KF strength was significantly associated with FA (rs = 0.42) and RD (rs = -0.36) and peak KE strength was significantly associated with MD (rs = -0.47) and RD (rs = -0.36). The correlations were attenuated after controlling for age and sex, but the relationship between KF strength and FA demonstrated a trend towards significance (prs = 0.33, p = 0.056). We provide evidence that the anatomical integrity of the CST may be associated with lower-extremity strength in MS. The attenuated correlations when controlling for age and sex suggest these factors, rather than MS per se, may be important contributors toward an association between CST DTI-metrics and KF and KE strength. Future rehabilitation trials of resistance training should consider including CST integrity as an outcome and/or predictor of strength adaptations.

Peak width of skeletonized mean diffusivity (PSMD) as marker of widespread white matter tissue damage in multiple sclerosis

BACKGROUND

Peak width of skeletonized mean diffusivity (PSMD) is a novel and fully automated, MRI biomarker, which has shown clinical relevance in cerebral small vessel diseases (SVD). We aimed here to assess PSMD levels across the brain of patients with multiple sclerosis (MS), in comparison to normal controls (NC) and patients with CADASIL, a genetically defined form of severe SVD.

METHODS

We assessed PSMD in relapsing-remitting (RR) MS patients (n = 47) in comparison to age-matched CADASIL patients (n = 25) and NC (n = 28). Diffusion Tensor Imaging data were acquired on 1.5T MR clinical scanner to automatically compute PSMD through "skeletonization" of WM tracts and diffusion histograms.

RESULTS

RRMS had lower WM lesion volume (LV) than CADASIL (8.6 ± 8.2 vs 24.4 ± 17.4 cm³, p < 0.001). After correction for LV, PSMD values in MS were higher than in CADASIL patients (adjusted mean values: 4.5 vs 3.9 × 10^-4 mm²/s, p = 0.03) and in both patient groups were higher than in NC (2.8 ± 0.3 × 10^-4 mm²/s, p < 0.001). PSMD values correlated with LV in both patient groups (r = 0.8, p < 0.001 in MS; r = 0.6, p = 0.002 in CADASIL).

CONCLUSIONS

In both patient groups, PSMD was higher than in NC and closely correlated with LV, suggesting sensitivity in assessing brain tissue damage in these disorders. In MS patients, PSMD levels were higher than in CADASIL patients, despite the lower LV. This might be related to more severe normal-appearing WM abnormalities occurring in the MS brains. This novel, fully automated, MRI metric may represent a useful marker for a robust quantification of the diffuse WM tissue damage in MS.

Multiple sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system in young adults. This disorder is a heterogeneous, multifactorial, immune-mediated disease that is influenced by both genetic and environmental factors. In most patients, reversible episodes of neurological dysfunction lasting several days or weeks characterize the initial stages of the disease (that is, clinically isolated syndrome and relapsing-remitting MS). Over time, irreversible clinical and cognitive deficits develop. A minority of patients have a progressive disease course from the onset. The pathological hallmark of MS is the formation of demyelinating lesions in the brain and spinal cord, which can be associated with neuro-axonal damage. Focal lesions are thought to be caused by the infiltration of immune cells, including T cells, B cells and myeloid cells, into the central nervous system parenchyma, with associated injury. MS is associated with a substantial burden on society owing to the high cost of the available treatments and poorer employment prospects and job retention for patients and their caregivers.

Early P2X7R-dependent activation of microglia during the asymptomatic phase of autoimmune encephalomyelitis

Microglia-mediated neuroinflammation accompanies many central nervous system (CNS) diseases, including multiple sclerosis (MS), and is strongly dependent on the purinergic P2X7 receptor. The nature of the inflammatory response in MS is studied for decades indicating, that proinflammatory microgliosis is involved in advanced stages of MS and is associated with active tissue damage and neurological dysfunctions. Evidence on the role of microgliosis in initial stages of the disease is scarce. Thus, in the present study, we investigated the time course of microglial activation in rat brain subjected to experimental autoimmune encephalomyelitis (EAE) which is the animal model of MS. We show that activation of microglia occurs in brains of immunized rats at a very early stage of EAE, well before the development of neurological symptoms of the disease. Enhanced immunoreactivity of microglia/macrophage-specific protein Iba-1, together with morphological features of microgliosis, was identified beginning at day 4 post immunization. Concomitantly, microglial expression of P2X7R was also examined. Moreover, our results reveal that administration of Brilliant Blue G, an antagonist of P2X7R, delays the onset of the disease and partially inhibits development of neurological symptoms in EAE rats. Blockage of P2X7R significantly reduces activation of microglia as confirmed by decreased Iba-1 immunoreactivity and suppresses neuroinflammation in EAE rat brains, as indicated by decreased protein levels of investigated proinflammatory cytokines: IL-1β, IL-6 and TNF-α. Our results indicate that microglia are involved in inducing neuroinflammation at a very early stage of MS/EAE via a P2X7R-dependent mechanism.

Olfactory Dysfunction in CNS Neuroimmunological Disorders: a Review

Olfactory dysfunction is deeply associated with quality of human life in the aging population. Olfactory dysfunction is an occasional presymptomatic sign of neuroimmunological multiple sclerosis, neuromyelitis optica, and systemic lupus erythematosus. Olfaction is initially processed by olfactory receptor cells that capture odor molecules, and the signals are transmitted to the glomeruli in the olfactory bulbs via olfactory nerves and processed in the primary olfactory cortex in the brain. Damage to either the olfactory receptor cells or the olfactory bulb and primary olfactory cortex may influence olfactory functioning. A close link between neuroimmunological disorders and olfactory dysfunction has been reported in patients and animal models. This review summarizes the literature data concerning olfactory dysfunction in autoimmune diseases including multiple sclerosis, neuromyelitis optica, and systemic lupus erythematosus; animal models thereof; and inflammation in the olfactory bulb.

Adenosine Promotes the Recovery of Mice from the Cuprizone-Induced Behavioral and Morphological Changes while Effecting on Microglia and Inflammatory Cytokines in the Brain

Recent studies have shown that multiple sclerosis (MS) and schizophrenia share similarities in some respects, including white matter damage and neuroinflammation. On the other hand, adenosine was reported to promote oligodendrocyte precursor maturation and remyelinating while influencing microglia activation. The aim of the present study was to examine possible beneficial effects of adenosine on the recovery of cuprizone (CPZ)-exposed mouse which has been used as an animal model of MS and schizophrenia as the CPZ-exposed mouse presents demyelination, oligodendrocyte loss, microglia accumulation, as well as behavioral changes. As reported previously, C57BL/6 mice, after fed CPZ for 5 weeks, showed salient demyelination and oligodendrocyte loss in the cerebral cortex (CTX) and hippocampus, in addition to displaying anxiety-like behavior, spatial working memory deficit, and social interaction impairment. Administration of adenosine for 7 days during the recovery period after CPZ withdrawal promoted the behavioral recovery of CPZ-exposed mice and accelerated the remyelinating process in the brains of mice after CPZ withdrawal in a dose-dependent manner. In addition, the effective dose (10 mg/kg) of adenosine inhibited microglia activation and suppressed abnormal elevation of the pro-inflammatory cytokines IL-1β and TNF-α in CTX and hippocampus, but increased levels of the anti-inflammatory cytokines IL-4 or IL-10 in the same brain regions during the remyelinating process. These results provided an evidence-based rationale for the application of adenosine or its analogues as add-on therapy for schizophrenia.

Development and validation of a multidimensional health literacy questionnaire for multiple sclerosis patients

BACKGROUND

Assessment of health literacy among patients with multiple sclerosis can be used in education planning, disease management, compliance, and quality of life. In addition, health literacy can be assessed using a standard questionnaire based on the social and cultural context more accurately. This study aimed to develop and validate a questionnaire for the assessment of health literacy in patients with multiple sclerosis.

METHODS

This is an exploratory sequential mixed method research which was conducted in three sections. In the first section, the concept of health literacy among patients with MS was analyzed using the hybrid concept analysis in the theoretical work, field work, and final analysis stages in order to extract features of the concept. In the second section, an initial pool of items of the questionnaire was designed based on the extracted features from the concept, reviewed texts, and related questionnaires. In the third section, psychometric properties of the questionnaire were evaluated including validity (face, content and construct) and reliability (internal consistency and stability).

RESULTS

Totally, 68 items were included in the initial pool, which shrank to 22 items in the final questionnaire after reviewing the psychometric features. Factor analyses led to the extraction of four factors including appraisal of health information, ability to search health information, knowledge of caring for the disease, and successful practices in health conditions. Internal consistency of the questionnaire was also confirmed by Cronbach's alpha coefficient of 0.94, and its stability was calculated and confirmed by the inter-class coefficient of correlation of 0.96.

CONCLUSION

The developed 22-item-questionnaire is valid and reliable for assessment of levels of health literacy in Iranian patients with MS.

Inorganic mercury in human astrocytes, oligodendrocytes, corticomotoneurons and the locus ceruleus: implications for multiple sclerosis, neurodegenerative disorders and gliomas

Neurotoxic metals have been implicated in the pathogenesis of multiple sclerosis, neurodegenerative disorders and brain tumours but studies of the location of heavy metals in human brains are rare. In a man who injected himself with metallic mercury the cellular location of mercury in his brain was studied after 5 months of continuous exposure to inorganic mercury arising from metallic mercury deposits in his organs. Paraffin sections from the primary motor and sensory cortices and the locus ceruleus in the pons were stained with autometallography to detect inorganic mercury and combined with glial fibrillary acidic protein immunohistochemistry to identify astrocytes. Inorganic mercury was found in grey matter subpial, interlaminar, protoplasmic and varicose astrocytes, white matter fibrous astrocytes, grey but not white matter oligodendrocytes, corticomotoneurons and some locus ceruleus neurons. In summary, inorganic mercury is taken up by five types of human brain astrocytes, as well as by cortical oligodendrocytes, corticomotoneurons and locus ceruleus neurons. Mercury can induce oxidative stress, stimulate autoimmunity and damage DNA, mitochondria and lipid membranes, so its location in these CNS cells suggests it could play a role in the pathogenesis of multiple sclerosis, neurodegenerative conditions such as Alzheimer's disease and amyotrophic lateral sclerosis, and glial tumours.

Reassessing B cell contributions in multiple sclerosis

There is growing recognition that B cell contributions to normal immune responses extend well beyond their potential to become antibody-producing cells, including roles at the innate-adaptive interface and their potential to modulate the responses of other immune cells such as T cells and myeloid cells. These B cell functions can have both pathogenic and protective effects in the context of central nervous system (CNS) inflammation. Here, we review recent advances in the field of multiple sclerosis (MS), which has traditionally been viewed as primarily a T cell-mediated disease, and we consider antibody-dependent and, particularly, emerging antibody-independent functions of B cells that may be relevant in both the peripheral and CNS disease compartments.

Multiple sclerosis and mixed microbial infections. Direct identification of fungi and bacteria in nervous tissue

Multiple sclerosis (MS) is the prototypical inflammatory disease of the central nervous system (CNS), leading to multifocal demyelination and neurodegeneration. The etiology of this incurable disease is unknown and remains a matter of intensive research. The possibility that microbial infections, such as viruses or bacteria, can trigger an autoimmune reaction in CNS tissue has been suggested. However, the recent demonstration that bacteria are present in CNS tissue points to a direct involvement of microbial infections in the etiology of MS. In the present study, we provide the first evidence of fungal infection in CNS tissue of MS patients, and demonstrate that fungal DNA from different species can be detected in the CNS. We used, nested PCR assays together with next-generation sequencing to identify the fungal species in the nervous tissue of 10 patients with MS. Strikingly, Trichosporon mucoides was found in the majority of MS patients, and particularly high levels of this fungus were found in two patients. Importantly, T. mucoides was not detected in the CNS of control subjects. We were also able to visualize fungal structures in CNS tissue sections by immunohistochemistry using specific antifungal antibodies, which also revealed the accumulation of a number of microbial cells in microfoci. Again, microbial structures were not observed in CNS sections from controls. In addition to fungi, neural tissue from MS patients was also positive for bacteria. In conclusion, our present observations point to the novel concept that MS could be caused by polymicrobial infections. Thus, mycosis of the CNS may be accompanied by opportunistic bacterial infection, promoting neuroinflammation and directly causing focal lesions, followed by demyelination and axonal injury.

Human Microglial Cells Undergo Proapoptotic Induction and Inflammatory Activation upon in vitro Exposure to a Naturally Occurring Level of Aflatoxin B1

OBJECTIVE

Knowledge regarding interactions of AFB1 with the human nervous system and how a naturally occurring level of AFB1 could potentially induce neuroimmune dysregulation is very limited. To assess the cellular effects of AFB1 on the human brain, we used the human microglia cell line CHME5 as a model to pinpoint its potential in vivo translation.

METHODS

We used the CHME5 cell line culture system, multiplex qPCR, (chemi)bioluminescence, Luminex ELISA, and flow cytometry assays to evaluate the toxic effects of a naturally occurring level of AFB1 on human microglia.

RESULTS

A low concentration of AFB1 upregulates the mRNA expression of many proinflammatory molecules, such as TLRs, MyD88, NFκB, and CxCr4, induces intracellular ATP depletion, and increases caspase-3/7 activity at different time points following exposure to the toxin. Furthermore, AFB1-exposed microglia secreted significantly higher levels of IFN-γ and GM-CSF after treatment. We also observed a slight increase in the percentage of apoptotic microglia (annexin V+/PI-) at 48 h posttreatment.

CONCLUSION

Our work confirmed that the environmentally relevant level of AFB1 could cause an inflammatory reaction in human microglial cells that is potentially harmful or toxic to the homeostasis of the human central nervous system and might increase susceptibility to neurodegenerative diseases.