Contributions
Abstract: 150
Type: Free Communications
Abstract Category: Pathology and pathogenesis of MS - Pathology
Introduction: Loss of myelin, a lipid-rich spiral wrapping of axons that facilitates rapid saltatory conduction, is a cardinal feature of MS pathology.
Aim: We hypothesized that existing immunohistochemical methods that reflect myelin protein changes under-report the full extent of myelin histopathology in autopsied samples of MS. We posited that lipid abnormalities may represent a substantial, early and widespread component of the pathology.
Method: To test this hypothesis, we utilized spectral confocal microscopy of the lipophilic fluorescent dye Nile Red (NR). This solvatochromic probe changes its emission spectrum as a function of local tissue environment, and is particularly sensitive to lipid alterations.
Results: We report a number of novel tissue defects in MS. In cases of normal appearing white matter (NAWM), unique lipid-rich plaques exhibited distinct spectral signatures, and had varying morphology, including unusual fibril-like structures. Others lacking fibrils clustered around blood vessels. In addition, many lipid-plaques were observed with no correlates by standard immunohistochemistry (MBP, IBA-1), suggesting that NR lipid histochemistry was more sensitive to early pathological changes than conventional protein immunohistochemistry. In long-standing MS cases, we found many still-myelinated axons but with drastically altered biochemical makeup of the sheath. Spectral analysis revealed patchy multi-focal increases in lipid polarity raising the possibility that morphologically intact myelin may still result in conduction failure due to alterations in its electrical properties (e.g. increased capacitance). Furthermore, accumulation in sub-ependymal layers of lipid droplets with various distinct biochemical features was observed in all MS cases (6/6), providing further evidence of lipid breakdown and possible accumulation of lipid debris in these periventricular regions.
Conclusion: Solvatochromic properties of NR coupled with spectral microscopy represent a powerful new tool for detecting very early and subtle myelin damage, likely reflecting lipid biochemical changes. This method appears more sensitive than conventional techniques such as myelin stains and immunohistochemistry, and may report a unique aspect of myelin pathology in MS.
Disclosure: W. Teo: nothing to disclose
A. Luchicchi: nothing to disclose
A.V. Caprariello: nothing to disclose
G.J. Schenk: nothing to disclose
M. Morgan: nothing to disclose
JJG. Geurts: nothing to disclose
P.K. Stys: nothing to disclose
Abstract: 150
Type: Free Communications
Abstract Category: Pathology and pathogenesis of MS - Pathology
Introduction: Loss of myelin, a lipid-rich spiral wrapping of axons that facilitates rapid saltatory conduction, is a cardinal feature of MS pathology.
Aim: We hypothesized that existing immunohistochemical methods that reflect myelin protein changes under-report the full extent of myelin histopathology in autopsied samples of MS. We posited that lipid abnormalities may represent a substantial, early and widespread component of the pathology.
Method: To test this hypothesis, we utilized spectral confocal microscopy of the lipophilic fluorescent dye Nile Red (NR). This solvatochromic probe changes its emission spectrum as a function of local tissue environment, and is particularly sensitive to lipid alterations.
Results: We report a number of novel tissue defects in MS. In cases of normal appearing white matter (NAWM), unique lipid-rich plaques exhibited distinct spectral signatures, and had varying morphology, including unusual fibril-like structures. Others lacking fibrils clustered around blood vessels. In addition, many lipid-plaques were observed with no correlates by standard immunohistochemistry (MBP, IBA-1), suggesting that NR lipid histochemistry was more sensitive to early pathological changes than conventional protein immunohistochemistry. In long-standing MS cases, we found many still-myelinated axons but with drastically altered biochemical makeup of the sheath. Spectral analysis revealed patchy multi-focal increases in lipid polarity raising the possibility that morphologically intact myelin may still result in conduction failure due to alterations in its electrical properties (e.g. increased capacitance). Furthermore, accumulation in sub-ependymal layers of lipid droplets with various distinct biochemical features was observed in all MS cases (6/6), providing further evidence of lipid breakdown and possible accumulation of lipid debris in these periventricular regions.
Conclusion: Solvatochromic properties of NR coupled with spectral microscopy represent a powerful new tool for detecting very early and subtle myelin damage, likely reflecting lipid biochemical changes. This method appears more sensitive than conventional techniques such as myelin stains and immunohistochemistry, and may report a unique aspect of myelin pathology in MS.
Disclosure: W. Teo: nothing to disclose
A. Luchicchi: nothing to disclose
A.V. Caprariello: nothing to disclose
G.J. Schenk: nothing to disclose
M. Morgan: nothing to disclose
JJG. Geurts: nothing to disclose
P.K. Stys: nothing to disclose