Analysis of distribution and localization of proteins of the reelin signalling pathway in mesial temporal lobe epilepsy

Abstract

Introduction

Granule cell dispersion (GCD) is pathognomonic of hippocampal sclerosis seen in the mesial temporal lobe epilepsy (MTLE). Current animal studies indicate deficiency of Reelin is associated with abnormal granule cell migration leading to GCD. The present study aimed to evaluate complete Reelin signalling pathway to assess whether Reelin deficiency is related to MTLE.

Materials and Methods

Hippocampal sclerosis was confirmed by H and E stain. To explore the amount and cellular location of the Reelin cascade molecules, the hippocampal tissues from MTLE surgery and controls (n = 15 each) were studied using Immuno-histochemistry (IHC). Additionally, confocal imaging was used to validate the IHC findings by co-localization of different proteins. Quantification of IHC images was performed using histo-score and confocal images by Image J software.

Results

Immune expression of active Reelin was significantly reduced in patients. Reelin receptors were deranged, apolipoprotein E receptor 2 was increased while very low-density lipoprotein receptor was reduced. Disabled-1, a downstream molecule was significantly reduced in MTLE. Its ultimate target, cofilin was thus disinhibited and expressed more in MTLE. Reelin cleaving protease, matrix metalloprotease-9 (MMP-9) and MMP-9 inhibitor, tissue inhibitor of matrix protease-1, showed reduced expression in extracellular matrix. Semi-quantification of immunohistochemistry was done using Histo (H) score. H score of Reelin in diseased patients was 15 against 125 for control patients. These results were validated by confocal fluorescence microscopy.

Conclusions

Reelin signalling cascade was deranged in chronic MTLE. Pharmacological manipulation of Reelin cascade can be done at various levels and it may provide novel treatment options for MTLE.

Keywords:

• ApoER2
• Cofilin
• Dab1
• MMP-9
• Reelin
• TIMP-1
• VLDLR

Acknowledgements

The authors would like to acknowledge the significant contributions of Dr. Ruchi, Ms. Shivani and Ms. Jyoti for their assistance in the methodology part.

Ethics approval

The project was approved by the Institute Ethical Committee. The experiments comply with the current laws of the country in which they were performed.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Availability of data and material

The information regarding the resources, reagents and data availability that support the findings of this study should be directed to the corresponding author and will be considered upon reasonable request.

Additional information

Funding

This work was supported by the Intramural grant under Institute Research Scheme, by Postgraduate Institute of Medical Education and Research Chandigarh, India.