A role for vessel-associated extracellular matrix proteins in multiple sclerosis pathology

Multiple sclerosis (MS) is unsurpassed for its clinical and pathological hetherogeneity, but the biological determinants of this variability are unknown. HLA-DRB1*15, the main genetic risk factor for MS, influences the severity and distribution of MS pathology. This study set out to unravel the molecular determinants of the heterogeneity of MS pathology in relation to HLA-DRB1*15 status. Shotgun proteomics from a discovery cohort of MS spinal cord samples segregated by HLA-DRB*15 status revealed overexpression of the extracellular matrix (ECM) proteins, biglycan, decorin, and prolargin in HLA-DRB*15-positive cases, adding to established literature on a role of ECM proteins in MS pathology that has heretofore lacked systematic pathological validation. These findings informed a neuropathological characterisation of these proteins in a large autopsy cohort of 41 MS cases (18 HLA-DRB1*15-positive and 23 HLA-DRB1*15-negative), and seven non-neurological controls on motor cortical, cervical and lumbar spinal cord tissue. Biglycan and decorin demonstrate a striking perivascular expression pattern in controls that is reduced in MS (-36.5%, p = 0.036 and - 24.7%, p = 0.039; respectively) in lesional and non-lesional areas. A concomitant increase in diffuse parenchymal accumulation of biglycan and decorin is seen in MS (p = 0.015 and p = 0.001, respectively), particularly in HLA-DRB1*15-positive cases (p = 0.007 and p = 0.046, respectively). Prolargin shows a faint parenchymal pattern in controls that is markedly increased in MS cases where a perivascular deposition pattern is observed (motor cortex +97.5%, p = 0.001; cervical cord +49.1%, p = 0.016). Our findings point to ECM proteins and the vascular interface playing a central role in MS pathology within and outside the plaque area. As ECM proteins are known potent pro-inflammatory molecules, their parenchymal accumulation may contribute to disease severity. This study brings to light novel factors that may contribute to the heterogeneity of the topographical variation of MS pathology.

A potential protective role of the nuclear receptor-related factor 1 (Nurr1) in multiple sclerosis motor cortex: a neuropathological study

Cerebral cortical inflammation and neurodegeneration are hallmark pathological features of multiple sclerosis that contribute to irreversible neurological disability. While the reason for nerve cell death is unknown, the pathogenic inflammatory role of infiltrating lymphocytes is likely an important contributor. The nuclear receptor-related factor 1 counteracts inflammation in animal models of multiple sclerosis, and protects against neuronal loss in other neurodegenerative disorders, but its expression in post-mortem multiple sclerosis tissue is not known. This study aims to investigate the nuclear receptor-related factor 1 expression in multiple sclerosis motor cortex and evaluate its relationship with motor cortical pathology. To accomplish this, an autopsy cohort of pathologically confirmed multiple sclerosis (n = 46) and control (n = 11) cases was used, where the nuclear receptor-related factor 1 expression was related to neuronal and lymphocytic densities. Motor cortical nuclear receptor-related factor 1 was overexpressed in multiple sclerosis compared to control cases. Increased nuclear receptor-related factor 1 expression positively associated with neuronal densities, especially when present in nucleus of neurons, and associated with decreased CD8 + cytotoxic lymphocyte density. Our findings expand the current knowledge on nuclear receptor-related factor 1 in neurological diseases, and support the hypothesis that nuclear receptor-related factor 1 may play a dual neuroprotective role in multiple sclerosis by influencing inflammatory and neurodegenerative processes. Future studies elucidating the influence of nuclear receptor-related factor 1 on these processes in multiple sclerosis may cast light onto novel targets that may be modulated to alter clinical outcome.

The influence of HLA-DRB1*15 on the relationship between microglia and neurons in multiple sclerosis normal appearing cortical grey matter

Cortical tissue injury is common in multiple sclerosis (MS) and associates with disability progression. We have previously shown that HLA‐DRB1*15 genotype status associates with the extent of cortical inflammatory pathology. In the current study, we sought to examine the influence of HLA‐DRB1*15 on relationships between inflammation and neurodegeneration in MS. Human post‐mortem MS cases (n = 47) and controls (n = 10) were used. Adjacent sections of motor cortex were stained for microglia (Iba1+, CD68+, TMEM119+), lymphocytes (CD3+, CD8+), GFAP+ astrocytes, and neurons (NeuN+). A subset of MS cases (n = 20) and controls (n = 7) were double‐labeled for neurofilament and glutamic acid decarboxylase 65/67 (GAD+) to assess the extent of the inhibitory synaptic loss. In MS cases, microglial protein expression positively correlated with neuron density (Iba1+: r = 0.548, p < 0.001, CD68+: r = 0.498, p = 0.001, TMEM119+ r = 0.437, p = 0.003). This finding was restricted to MS cases not carrying HLA‐DRB1*15. Evidence of a 14% reduction in inhibitory synapses in MS was detected (MS: 0.299 ± 0.006 synapses/μm² neuronal membrane versus control: 0.348 ± 0.009 synapses/μm² neuronal membrane, p = 0.005). Neurons expressing inhibitory synapses were 24% smaller in MS cases compared to the control (MS: 403 ± 15 μm² versus control: 531 ± 29 μm², p = 0.001), a finding driven by HLA‐DRB1*15+ cases (15+: 376 ± 21 μm² vs. 15−: 432 ± 22 μm², p = 0.018). Taken together, our results demonstrate that HLA‐DRB1*15 modulates the relationship between microglial inflammation, inhibitory synapses, and neuronal density in the MS cortex.

Fibrin(ogen) and neurodegeneration in the progressive multiple sclerosis cortex

OBJECTIVE

Neuronal loss, a key substrate of irreversible disability in multiple sclerosis (MS), is a recognized feature of MS cortical pathology of which the cause remains unknown. Fibrin(ogen) deposition is neurotoxic in animal models of MS, but has not been evaluated in human progressive MS cortex. The aim of this study was to investigate the extent and distribution of fibrin(ogen) in progressive MS cortex and elucidate its relationship with neurodegeneration.

METHODS

A postmortem cohort of pathologically confirmed MS (n = 47) and control (n = 10) cases was used. The extent and distribution of fibrin(ogen) was assessed and related to measures of demyelination, inflammation, and neuronal density. In a subset of cases (MS, n = 20; control, n = 10), expression of plasminogen activator inhibitor 1 (PAI-1), a key enzyme in the fibrinolytic cascade, was assessed and related to the extent of fibrin(ogen).

RESULTS

Motor cortical fibrin(ogen) deposition was significantly over-represented in MS compared to control cases in all compartments studied (ie, extracellular [p = 0.001], cell body [p = 0.003], and neuritic/glial-processes [p = 0.004]). MS cases with high levels of extracellular fibrin(ogen) had significantly upregulated PAI-1 expression in all cortical layers assessed (p < 0.05) and reduced neuronal density (p = 0.017), including in the functionally-relevant layer 5 (p = 0.001).

INTERPRETATION

For the first time, we provide unequivocal evidence that fibrin(ogen) is extensively deposited in progressive MS motor cortex, where regulation of fibrinolysis appears perturbed. Progressive MS cases with severe fibrin(ogen) deposition have significantly reduced neuronal density. Future studies are needed to elucidate the provenance and putative neurotoxicity of fibrin(ogen), and its potential impact on clinical disability. Ann Neurol 2017;82:259-270.

Neurite dispersion: a new marker of multiple sclerosis spinal cord pathology?

Objective

Conventional magnetic resonance imaging (MRI) of the multiple sclerosis spinal cord is limited by low specificity regarding the underlying pathological processes, and new MRI metrics assessing microscopic damage are required. We aim to show for the first time that neurite orientation dispersion (i.e., variability in axon/dendrite orientations) is a new biomarker that uncovers previously undetected layers of complexity of multiple sclerosis spinal cord pathology. Also, we validate against histology a clinically viable MRI technique for dispersion measurement (neurite orientation dispersion and density imaging,NODDI), to demonstrate the strong potential of the new marker.

Methods

We related quantitative metrics from histology and MRI in four post mortem spinal cord specimens (two controls; two progressive multiple sclerosis cases). The samples were scanned at high field, obtaining maps of neurite density and orientation dispersion from NODDI and routine diffusion tensor imaging (DTI) indices. Histological procedures provided markers of astrocyte, microglia, myelin and neurofilament density, as well as neurite dispersion.

Results

We report from both NODDI and histology a trend toward lower neurite dispersion in demyelinated lesions, indicative of reduced neurite architecture complexity. Also, we provide unequivocal evidence that NODDI‐derived dispersion matches its histological counterpart (P < 0.001), while DTI metrics are less specific and influenced by several biophysical substrates.

Interpretation

Neurite orientation dispersion detects a previously undescribed and potentially relevant layer of microstructural complexity of multiple sclerosis spinal cord pathology. Clinically feasible techniques such as NODDI may play a key role in clinical trial and practice settings, as they provide histologically meaningful dispersion indices.

A framework for optimal whole-sample histological quantification of neurite orientation dispersion in the human spinal cord

BACKGROUND

The complexity of fibre distributions in tissues is an important microstructural feature, now measurable in vivo by magnetic resonance imaging (MRI) through orientation dispersion (OD) indices. OD metrics have gained popularity for the characterisation of neurite morphology, but they still lack systematic validation. This paper demonstrates a framework for whole-sample histological quantification of OD in spinal cord specimens, potentially useful for validating MRI-derived OD estimates.

NEW METHOD

Our methodological framework is based on (i) sagittal sectioning; (ii) Palmgren's silver staining; (iii) structure tensor (ST) analysis; (iv) directional statistics. Novel elements are the data-driven optimisation of the spatial scale of ST analysis, and a new multivariate, weighted directional statistical approach for anisotropy-informed quantification of OD.

RESULTS

Palmgren's silver staining of sagittal spinal cord sections provides robust visualisation of neuronal elements, enabling OD quantification. The choice of spatial scale of ST analysis influences OD values, and weighted directional statistics provide OD maps with high contrast-to-noise. Segmentation of neurites prior to OD quantification is recommended.

COMPARISON WITH EXISTING METHODS

Our framework can potentially provide OD even in demyelinating diseases, where myelin-based histology is not suitable. As compared to conventional univariate approaches, our multivariate weighted directional statistics improve the contrast-to-noise of OD maps and more accurately describe the distribution of ST metrics.

CONCLUSIONS

Our framework enables practical whole-specimen characterisation of OD in the spinal cord. We recommend tuning the scale of ST analysis for optimal OD quantification, as well as neurite segmentation and weighted directional statistics, of which examples are provided herein.

Loss of galectin-3 decreases the number of immune cells in the subventricular zone and restores proliferation in a viral model of multiple sclerosis

Multiple sclerosis (MS) frequently starts near the lateral ventricles, which are lined by subventricular zone (SVZ) progenitor cells that can migrate to lesions and contribute to repair. Because MS-induced inflammation may decrease SVZ proliferation and thus limit repair, we studied the role of galectin-3 (Gal-3), a proinflammatory protein. Gal-3 expression was increased in periventricular regions of human MS in post-mortem brain samples and was also upregulated in periventricular regions in a murine MS model, Theiler's murine encephalomyelitis virus (TMEV) infection. Whereas TMEV increased SVZ chemokine (CCL2, CCL5, CCL, and CXCL10) expression in wild type (WT) mice, this was inhibited in Gal-3(-/-) mice. Though numerous CD45+ immune cells entered the SVZ of WT mice after TMEV infection, their numbers were significantly diminished in Gal-3(-/-) mice. TMEV also reduced neuroblast and proliferative SVZ cell numbers in WT mice but this was restored in Gal-3(-/-) mice and was correlated with increased numbers of doublecortin+ neuroblasts in the corpus callosum. In summary, our data showed that loss of Gal-3 blocked chemokine increases after TMEV, reduced immune cell migration into the SVZ, reestablished SVZ proliferation and increased the number of progenitors in the corpus callosum. These results suggest Gal-3 plays a central role in modulating the SVZ neurogenic niche's response to this model of MS.

Cognitive impairment in multiple sclerosis: clinical, radiologic and pathologic insights

Cognitive impairment is a common and debilitating feature of multiple sclerosis (MS) that has only recent gained considerable attention. Clinical neuropsychological studies have made apparent the multifaceted nature of cognitive troubles often encountered in MS and continue to broaden our understanding of its complexity. Radiographic studies have started to decipher the neuroanatomic substrate of MS-related cognitive impairment and have shed light onto its pathogenesis. Where radiographic studies have been limited by inadequate resolution or non-specificity, pathological studies have come to the fore. This review aims to provide an overview of the nature of cognitive impairment typically seen in MS and to explore the literature on imaging and pathological studies relevant to its evolution. In particular, the relative contributions of gray (i.e., cerebral cortex, hippocampus, thalamus and basal ganglia) and white matter to MS-related cognitive impairment will be discussed and the importance of interconnectivity between structures highlighted. The pressing need for longitudinal studies combining standardized neuropsychometric, paraclinical and radiographic outcomes obtained during life with post-mortem tissue analysis after death is presented.

Olfactory Pathology in Central Nervous System Demyelinating Diseases

Olfactory dysfunction is common in multiple sclerosis (MS). Olfactory bulb and tract pathology in MS and other demyelinating diseases remain unexplored. A human autopsy cohort of pathologically confirmed cases encompassing the spectrum of demyelinating disease (MS; n = 17), neuromyelitis optica [(NMO); n = 3] and acute disseminated encephalomyelitis [(ADEM); n = 7] was compared to neuroinflammatory [herpes simplex virus encephalitis (HSE); n = 3], neurodegenerative [Alzheimer's disease (AD); n = 4] and non-neurologic (n = 8) controls. For each case, olfactory bulbs and/or tracts were stained for myelin, axons and inflammation. Inferior frontal cortex and hippocampus were stained for myelin in a subset of MS and ADEM cases. Olfactory bulb/tract demyelination was frequent in all demyelinating diseases [MS 12/17 (70.6%); ADEM 3/7 (42.9%); NMO 2/3 (66.7%)] but was absent in HSE, AD and non-neurologic controls. Inflammation was greater in the demyelinating diseases compared to non-neurologic controls. Olfactory bulb/tract axonal loss was most severe in MS where it correlated significantly with the extent of demyelination (r = 0.610, P = 0.009) and parenchymal inflammation (r = 0.681, P = 0.003). The extent of olfactory bulb/tract demyelination correlated with that found in the adjacent inferior frontal cortex but not hippocampus. We provide unequivocal evidence that olfactory bulb/tract demyelination is frequent, can occur early and is highly inflammatory, and is specific to demyelinating disease.

A rapid and selective method for determining potential nitrosating agents in cosmetic products by chemiluminescence detection of nitric oxide

A method was developed for rapid and selective determination of potential nitrosating agents at the part-per-billion level in cosmetic products. These compounds are chemically reduced to nitric oxide, which is determined by its chemiluminescent reaction with ozone. Suspended materials and colors in cosmetic products do not interfere. Hence their removal before analysis is not required. A detection limit of 33 ppb, calculated as nitrite, was obtained. No false-positive interferences were observed from antifoaming agents, several N-nitroso compounds, and nitrate up to 20 ppm. Among cosmetic products surveyed, potential nitrosating agents were found at levels ranging from 113 to 5021 ppb. No consistent relationship was found between levels of potential nitrosating agents and N-nitrosamines in the same products. However, the highest levels of nitrosating agents were most often associated with the highest levels of N-nitrosamines known to be present in the products.

Determination of 2-ethylhexyl 4-(N-methyl-N-nitrosamino) benzoate in commercial sunscreens and cosmetic products

An analytical method has been developed for determination of 2-ethylhexyl 4-(N-methyl-N-nitrosamino) benzoate (NMPABAO), a nitrosamine contaminant in sunscreen products containing 2-ethylhexyl 4-(N,N-dimethylamino) benzoate (Padimate O). The method involves extraction of NMPABAO by column chromatography followed by liquid chromatographic separation and analysis wit a nitric oxide detector. To confirm the presence of NMPABAO in sunscreen products, the N-nitrosamine was synthesized and its structure was determined by infrared spectrophotometry, nuclear magnetic resonance spectrometry, and mass spectrometry (MS). For method validation, recovery studies were performed on a commercial suntan lotion, cream, and gel. Recoveries of NMPABAO added to representative test samples averaged 83%. The method has an estimated detection limit of 30 ppb. The method was used to analyze 25 commercial cosmetic and sunscreen products containing Padimate O. Eleven products contained NMPABAO at levels ranging from 160 to 21000 ppb. NMPABAO presence in 4 products was confirmed by MS at levels > or = 4000 ppb. The highest levels of NMPABAO were associated with products that contained the nitrite-releasing preservative 2-bromo-2-nitro-1,3-propanediol.

Determination of musk ambrette in fragrance products by capillary gas chromatography with electron capture detection: interlaboratory study

A gas chromatographic method that uses an internal standard additions techniques is described for the determination of musck ambrette (MA) in fragrance products. A solution containing the product and a known amount of an internal standard, musk tibetene (MT), is injected directly into a gas chromatograph equipped with an electron capture detector. The chromatographic separation of the components on a wide-bore fused silica capillary column is recorded and a response constant is calculated from MA and MT peak heights. A similar response constant is also calculated for a standard solution containing known concentrations of MA and MT. The MA content of the fragrance product is then calculated. Average recoveries of MA from fragrance products ranged from 97.6 to 102.3%. The method was also evaluated collaboratively by 6 laboratories. In this study, the reproducibility relative standard deviation for MA in 6 fragrance test samples ranged from 2.78 to 22.87%.

Fluorometric determination of benzylideneacetone in fragrance products by liquid chromatography with post-column derivatization

A method is described for the liquid chromatographic (LC)-fluorometric determination of benzylideneacetone in fragrance products. Benzylideneacetone is first separated from other fragrance ingredients by LC and then reacted post-column with a methanolic solution of isonicotinic acid hydrazide and aluminum nitrate. The reactants are maintained at 65 degrees C for about 1.5 min to quantitatively form the fluorescent isonicotinoyl hydrazone derivative of benzylideneacetone. The aluminum ion forms a complex with the hydrazone to enhance the fluorescence of the derivative. The amount of benzylideneacetone is determined by measuring the intensity of the fluorescence emitted by the hydrazone derivative and comparing that value with those obtained for derivatized standards. Recovery studies were conducted by spiking commercial fragrances with benzylideneacetone at concentrations of 0.01, 0.05, and 0.1% (w/v). Recoveries ranged from 98 to 104% with a mean recovery of 100.2% and a standard deviation of 2.4%.

Liquid chromatographic separation and fluorometric determination of cis- and trans-isoeugenol in perfumes, colognes, and toilet waters

A liquid chromatographic (LC)-fluorometric method is described for the determination of cis- and trans-isoeugenol (2-methoxy-4-propenylphenol) in perfumes, colognes, and toilet waters. A test portion of the product is added to diethyl ether, and the isoeugenol isomers are extracted with sodium hydroxide solution. The basic extract is then acidified, and the isoeugenol isomers are extracted with isooctane. Aliquots of the isooctane extract are analyzed by using a silver ion cation exchange LC column interfaced to a spectrophotofluorometer. Each isomer in the product is determined by comparing its fluorescence emission intensity with that of an external standard consisting of a mixture of both isomers in which the relative concentration of each has been determined. Average recoveries from various commercial fragrances fortified with a mixture of cis- and trans-isoeugenol with total isoeugenol content of 0.1, 0.5, and 4.0 mg/mL ranged from 87 to 105% for the trans-isomer (SD = 4.6%) and from 83 to 113% for the cis-isomer (SD = 6.7%). The limit of determination is approximately 0.002 mg/mL.

Liquid chromatographic-fluorometric determination of cinnamyl alcohol in perfumes, colognes, and toilet waters

A liquid chromatographic (LC) method is described for the determination of cinnamyl alcohol (3-phenyl-2-propen-1-ol) in fragrance compositions. The fragrance product is partially cleaned up by diluting the fragrance with a 95% ethanol-water mixture and passing it through a short column containing RP-8 packing. An aliquot of the effluent is then analyzed by LC using an RP-18 column interfaced to a spectrophotofluorometer equipped with double monochromators. The fluorescence emission intensity of the eluted cinnamyl alcohol is measured and compared with that of a standard to calculate the amount of cinnamyl alcohol present. Recoveries from fragrance products fortified with cinnamyl alcohol at levels ranging from 0.0020 to 0.060 mg/mL ranged from 85 to 105% with a mean of 94%. The lowest level of determination was 0.0005 mg/mL.

Determination of cinnamyl anthranilate in perfume, cologne, and toilet water by liquid chromatography with fluorescence detection

A liquid chromatographic method with fluorescence detection was developed for the determination of cinnamyl anthranilate in perfumes and other fragrance compositions. The method was evaluated by conducting recovery studies of 10 different commercial fragrance compositions to which cinnamyl anthranilate had been added at levels of 0.1, 0.5, and 1.0 mg/mL. Recoveries ranged from 91 to 103% with a mean of 97% and a standard deviation of +/- 3.3%.

Screening cosmetic products for N-nitroso compounds by chemiluminescent determination of nitric oxide

Cosmetic products were screened for total N-nitroso compounds by chemiluminescent measurement of nitric oxide liberated by the reductive cleavage of the N-nitroso group. The cosmetic was first partitioned between methylene chloride and water to separate polar and nonpolar N-nitroso compounds. Each extract was then examined for the presence of N-nitroso compounds by adding the cleavage reagent and sweeping the nitric oxide formed into a chemiluminescent analyzer. Although the method is not intended to be quantitative, recovery studies were conducted to determine measurable levels. Recovery studies of polar N-nitroso compounds were conducted by adding N-nitrosodiethanolamine (NDELA) to a cream, a shampoo, and a lotion at 3 levels, i.e., 80, 320, and 960 ppb, and then determining NDELA by the method. Recoveries ranged from 48 to 83% (mean 68%; SD = 11.9). For recoveries of nonpolar N-nitroso compounds, 100, 200, and 500 ppb of N-nitrosomethyltetradecylamine were added to the 3 cosmetic products. Recoveries ranged from 58 to 70% (mean 63%; SD = 5.3).

High-performance liquid chromatographic-fluorometric determination of cinnamaldehyde in perfume, cologne and toilet water

A high-performance liquid chromatographic (HPLC)-fluorometric method is described for the determination of trans-cinnamaldehyde in fragrances. The fragrance is added to isooctane and extracted with an aqueous solution of the sodium salt of 6-aminocaproic acid to isolate the aldehyde fraction. After dilution with water, an aliquot of the extract is added to a solution of 1,2-diaminonaphthalene monosulfate in dilute formic acid. The fluorescent derivative of cinnamaldehyde, 2-styrylnaphth[1,2-d]imidazole, is prepared by incubating and then cooling the solution and adding pyridine. Aliquots of the fluorophore solution are analyzed on a reversed-phase C18 HPLC column by using a buffered tetrahydrofuran-water eluent. Cinnamaldehyde is quantitated by comparing fluorescence emission intensity with that of a standard. Recoveries from samples of various commercial fragrances, spiked with cinnamaldehyde at the 0.01, 0.05 and 0.1% levels, ranged from 94 to 112% with a mean of 103% and a standard deviation of 5.3. The limit of detection is approximately 1 ng.

High pressure liquid chromatographic-thermal energy determination of N-nitrosodiethanolamine in cosmetics

Methods for the determination and confirmation of N-nitrosodiethanolamine (NDELA) in cosmetic products were developed. The NDELA fraction was isolated from a cosmetic product by a series of solvent extractions which were designed to concentrate the NDELA and remove ingredients deleterious to the analytical system. The isolated fraction was then analyzed for NDELA using a high pressure liquid chromatograph (HPLC) interfaced with a thermal energy analyzer (TEA). The compound was measured by comparison of detector response with those of known standards. NDELA was verified by gas chromatography-mass spectrometry of the silyl derivative after preliminary cleanup of the sample by gradient elution HPLC on a Partisil 10 PAC column. The limit of detection of NDELA by TEA is 2-3 ng, which corresponds to 20-30 ppb in the cosmetic product. Analysis of an emulsion cream and a hair grooming gel spiked at 3 and 4 ng concentration levels, respectively, yielded recoveries ranging from 71 to 103% (average 88%).

Anthelmintic activity of diuredosan in dogs experimentally infected with Ancylostoma caninum and Trichuris vulpis

The efficacy of diuredosan was determined in dogs experimentally infected with Ancylostoma caninum and Trichuris vulpis. Diuredosan at dosages of 25, 50, and 100 mg/kg was 99% effective against A caninum. Efficacies against T vulpis were 88, 85, and 94% at dosages of 25, 50, and 100 mg/kg, respectively.