Carme Costa

Mapping of aggrecan, hyaluronic acid, heparan sulphate proteoglycans and aquaporin 4 in the central nervous system of the mouse

The extracellular matrix (ECM) of the central nervous system (CNS) is found dispersed in the neuropil or forming aggregates around the neurons called perineuronal nets (PNNs). The ECM mainly contains chondroitin sulphate proteoglycans (CSPG), hyaluronic acid (HA) and tenascin-R. Heparan sulphate proteoglycans (HSPG) can also be secreted in the ECM or be part of the cell membrane. The ECM has a heterogeneous distribution which has been linked to several functions, such as specific regional maintenance of hydrodynamic properties in the CNS, in which aquaporins (AQP) play an important role. AQP are a family of membrane proteins which acts as a water channel and AQP4 is the most abundant isoform in the brain. Nevertheless the importance of these proteins, their distribution and correlation in the whole CNS of mice is only partially known. In the present study, the histochemical and immunohistochemical distribution of PNNs, using Wisteria floribunda agglutinin (WFA), aggrecan, HA, HSPGs and AQP4 is described, and their perineuronal and neuropil staining has been semi-quantitatively evaluated in the whole CNS of mice. The results showed that the aggrecan, HA and HSPGs perineuronal distribution coincided partially and this could be related to ECM functional properties. AQP4 showed a heterogeneous distribution throughout the CNS. In some areas, an inverse correlation between AQP4 and ECM components has been observed, suggesting a complementary role for both in the maintenance of water homeostasis. A common location for AQP4 and HSPGs has also been observed in CNS neuropil.

Chitinase 3-like 1: prognostic biomarker in clinically isolated syndromes.

Chitinase 3-like 1 (CHI3L1) has been proposed as a biomarker associated with the conversion to clinically definite multiple sclerosis in patients with clinically isolated syndromes, based on the finding of increased cerebrospinal fluid CHI3L1 levels in clinically isolated syndrome patients who later converted to multiple sclerosis compared to those who remained as clinically isolated syndrome. Here, we aimed to validate CHI3L1 as a prognostic biomarker in a large cohort of patients with clinically isolated syndrome. This is a longitudinal cohort study of clinically isolated syndrome patients with clinical, magnetic resonance imaging, and cerebrospinal fluid data prospectively acquired. A total of 813 cerebrospinal fluid samples from patients with clinically isolated syndrome were recruited from 15 European multiple sclerosis centres. Cerebrospinal fluid CHI3L1 levels were measured by enzyme-linked immunosorbent assay. Multivariable Cox regression models were used to investigate the association between cerebrospinal fluid CHI3L1 levels and time to conversion to multiple sclerosis and time to reach Expanded Disability Status Scale 3.0. CHI3L1 levels were higher in patients who converted to clinically definite multiple sclerosis compared to patients who continued as clinically isolated syndrome (P = 8.1 × 10(-11)). In the Cox regression analysis, CHI3L1 levels were a risk factor for conversion to multiple sclerosis (hazard ratio = 1.7; P = 1.1 × 10(-5) using Poser criteria; hazard ratio = 1.6; P = 3.7 × 10(-6) for McDonald criteria) independent of other covariates such as brain magnetic resonance imaging abnormalities and presence of cerebrospinal fluid oligoclonal bands, and were the only significant independent risk factor associated with the development of disability (hazard ratio = 3.8; P = 2.5 × 10(-8)). High CHI3L1 levels were associated with shorter time to multiple sclerosis (P = 3.2 × 10(-9) using Poser criteria; P = 5.6 × 10(-11) for McDonald criteria) and more rapid development of disability (P = 1.8 × 10(-10)). These findings validate cerebrospinal fluid CHI3L1 as a biomarker associated with the conversion to multiple sclerosis and development of disability and reinforce the prognostic role of CHI3L1 in patients with clinically isolated syndrome. We propose that determining cerebrospinal fluid chitinase 3-like 1 levels at the time of a clinically isolated syndrome event will help identify those patients with worse disease prognosis.

Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica

Objective Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (AQP4-Ab) assays in neuromyelitis optica spectrum disorders (NMOSD). Methods Coded samples from patients with neuromyelitis optica (NMO) or NMOSD (101) and controls (92) were tested at 15 European diagnostic centres using 21 assays including live (n=3) or fixed cell-based assays (n=10), flow cytometry (n=4), immunohistochemistry (n=3) and ELISA (n=1). Results Results of tests on 92 controls identified 12assays as highly specific (0–1 false-positive results). 32 samples from 50 (64%) NMO sera and 34 from 51 (67%) NMOSD sera were positive on at least two of the 12 highly specific assays, leaving 35 patients with seronegative NMO/spectrum disorder (SD). On the basis of a combination of clinical phenotype and the highly specific assays, 66 AQP4-Ab seropositive samples were used to establish the sensitivities (51.5–100%) of all 21 assays. The specificities (85.8–100%) were based on 92 control samples and 35 seronegative NMO/SD patient samples. Conclusions The cell-based assays were most sensitive and specific overall, but immunohistochemistry or flow cytometry could be equally accurate in specialist centres. Since patients with AQP4-Ab negative NMO/SD require different management, the use of both appropriate control samples and defined seronegative NMOSD samples is essential to evaluate these assays in a clinically meaningful way. The process described here can be applied to the evaluation of other antibody assays in the newly evolving field of autoimmune neurology.

Implication of the toll-like receptor 4 pathway in the response to interferon-β in multiple sclerosis

Interferon‐beta (IFNβ) has demonstrated beneficial effects reducing disease activity in multiple sclerosis (MS) patients, but a relatively large proportion of patients do not respond to treatment. Here we aimed to investigate the roles of the Toll‐like receptor 4 (TLR4) and the type I IFN pathways in the response to IFNβ in MS patients.

Treatment with MOG-DNA vaccines induces CD4+CD25+FoxP3+ regulatory T cells and up-regulates genes with neuroprotective functions in experimental autoimmune encephalomyelitis

BackgroundDNA vaccines represent promising therapeutic strategies in autoimmune disorders such as multiple sclerosis (MS). However, the precise mechanisms by which DNA vaccines induce immune regulation remain largely unknown. Here, we aimed to expand previous knowledge existing on the mechanisms of action of DNA vaccines in the animal model of MS, experimental autoimmune encephalomyelitis (EAE), by treating EAE mice with a DNA vaccine encoding the myelin oligodendrocyte glycoprotein (MOG), and exploring the therapeutic effects on the disease-induced inflammatory and neurodegenerative changes.MethodsEAE was induced in C57BL6/J mice by immunization with MOG35-55 peptide. Mice were intramuscularly treated with a MOG-DNA vaccine or vehicle in prophylactic and therapeutic approaches. Histological studies were performed in central nervous system (CNS) tissue. Cytokine production and regulatory T cell (Treg) quantification were achieved by flow cytometry. Gene expression patterns were determined using microarrays, and the main findings were validated by real-time PCR.ResultsMOG-DNA treatment reduced the clinical and histopathological signs of EAE when administered in both prophylactic and therapeutic settings. Suppression of clinical EAE was associated with dampening of antigen (Ag)-specific proinflammatory Th1 and Th17 immune responses and, interestingly, expansion of Treg in the periphery and upregulation in the CNS of genes encoding neurotrophic factors and proteins involved in remyelination.ConclusionsThese results suggest for the first time that the beneficial effects of DNA vaccines in EAE are not limited to anti-inflammatory mechanisms, and DNA vaccines may also exert positive effects through hitherto unknown neuroprotective mechanisms.

Hsp70 regulates immune response in experimental autoimmune encephalomyelitis

Heat shock protein (Hsp)70 is one of the most important stress-inducible proteins. Intracellular Hsp70 not only mediates chaperone-cytoprotective functions but can also block multiple steps in the apoptosis pathway. In addition, Hsp70 is actively released into the extracellular milieu, thereby promoting innate and adaptive immune responses. Thus, Hsp70 may be a critical molecule in multiple sclerosis (MS) pathogenesis and a potential target in this disease due to its immunological and cytoprotective functions. To investigate the role of Hsp70 in MS pathogenesis, we examined its immune and cytoprotective roles using both in vitro and in vivo experimental procedures. We found that Hsp70.1-deficient mice were more resistant to developing experimental autoimmune encephalomyelitis (EAE) compared with their wild-type (WT) littermates, suggesting that Hsp70.1 plays a critical role in promoting an effective myelin oligodendrocyte glycoprotein (MOG)-specific T cell response. Conversely, Hsp70.1-deficient mice that developed EAE showed an increased level of autoreactive T cells to achieve the same production of cytokines compared with the WT mice. Although a neuroprotective role of HSP70 has been suggested, Hsp70.1-deficient mice that developed EAE did not exhibit increased demyelination compared with the control mice. Accordingly, Hsp70 deficiency did not influence the vulnerability to apoptosis of oligodendrocyte precursor cells (OPCs) in culture. Thus, the immunological role of Hsp70 may be relevant in EAE, and specific therapies down-regulating Hsp70 expression may be a promising approach to reduce the early autoimmune response in MS patients.

Inhibition of delta-like ligand 4 decreases Th1/Th17 response in a mouse model of multiple sclerosis

Notch is a family of receptors involved in the differentiation of several tissues, including the central nervous system and the immune system. One of the Notch ligands, delta-like 4 (Dll4), has been implicated in the differentiation of Th1 cells and the development of Th17 responses, which are involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis. Our results show that a single administration of an anti-Dll4 antibody is not enough to avoid the development of EAE or to ameliorate the already established clinical signs, despite the treatment reduces the proliferative T cell responses and decreases Th1/Th17 immune responses.

Value of NMO-IgG determination at the time of presentation as CIS

Background: Despite the availability of diagnostic criteria, an overlap between neuromyelitis optica (NMO) and multiple sclerosis (MS) exists, particularly in the early stage of the disease. Objective: To study the value of NMO–immunoglobulin G (IgG) determination in Caucasian patients with a first demyelinating episode who develop a relapsing form of optic neuritis or myelitis. Methods: This study was based on a prospectively acquired cohort of patients regarded as having a clinically isolated syndrome (CIS) at the time of presentation. From this cohort, 2 different groups were selected: group 1 (NMO phenotype), consisting of a first attack involving the optic nerve or the spinal cord, and at least a second event affecting either topography, and group 2 (negative control group), consisting of a first attack involving the brainstem or the cerebral hemispheres and at least 1 relapse in any topography. Group 3 was composed of patients with NMO according to the 2006 revised diagnostic criteria. Serum NMO-IgG was determined by indirect immunofluorescence. Results: A total of 3.1 of the group 1 patients were positive for NMO-IgG in comparison to 3.9% of group 2 and 44.5% of group 3, NMO. One of the positive patients in group 1 evolved to NMO. Conclusions: NMO-IgG determination is crucial in detecting patients who will develop NMO; however, its value as a routine test in cases presenting with symptoms of the type seen in MS is low, and should only be performed in those patients in which the initial diagnosis is not clear.

Aquaporin 1 and aquaporin 4 overexpression in bovine spongiform encephalopathy in a transgenic murine model and in cattle field cases.

Aquaporins (AQP) are a family of transmembrane proteins that act as water selective channels. AQP1 and AQP4 are widely expressed in the central nervous system where they play several roles. Overexpression of AQP has been reported in some human and animal transmissible spongiform encephalopathies, but information is scanty about their distribution in the central nervous system in bovine spongiform encephalopathy (BSE). Double immunohistochemistry for AQP1, AQP4 and GFAP was developed in a transgenic mouse line overexpressing the bovine cellular prion protein (BoTg110), intracerebrally infected with cattle BSE. Western blot for AQP1 and AQP4, and immunohistochemistry for both AQP and GFAP were carried out in cases of BSE-diagnosed cattle as part of surveillance plan in Catalonia (Spain). A marked increase in AQP1 and AQP4 was observed in mice at the terminal stage of the disease, when they had a wide range of clinical signs, whereas no increase could be observed in the early stage before the onset of the clinical signs. In cattle which did not show evidence of clinical signs, both AQP already showed a great increase. The AQP overexpression correlated with GFAP-immunoreactive astrocytes and PrPres deposition in both cases. The results of this study suggest that AQP overexpression in glial cells could lead to an imbalance in water and ion homeostasis which could contribute to triggering the typical histopathological changes of BSE.

Adult onset leukodystrophy with neuroaxonal spheroids and demyelinating plaque-like lesions

Adult onset leukodystrophy with neuroaxonal spheroids is an uncommon cause of dementia. Both hereditary (autosomal dominant) and sporadic cases have been described. A 41‐year‐old African woman presented with inappropriate behavior and personality change consistent with frontal lobe dysfunction. MRI demonstrated diffuse frontoparietal white matter signal abnormality and volume loss, as well as focal enhancing white matter lesions, while CT scan showed white matter calcifications. She had been gradually deteriorating over the last 5 years, diagnosed as having progressive demyelinating illness. She died of recurrent chest infections. There was no familial history. The brain showed prominent symmetrical white matter changes with greyish discolorization mainly affecting the frontal and parietal lobes, with less involvement of the temporal lobe and only mildly affecting the occipital white matter. Histology revealed deep white matter atrophy with many neuroaxonal spheroids labelled by neurofilament and β‐amyloid precursor protein. In addition, scattered inactive demyelinating plaque‐like lesions were found in the periventricular areas, brainstem and the cervical spinal cord. This case had typical features of an adult onset leukodystrophy with neuroaxonal spheroids. However, we also demonstrated demyelinating plaque‐like lesions, which has not been previously described. The possibility of a demyelinating origin contributing to the changes may be considered in the pathogenesis of this condition.