Altered hippocampal expression and function of cytosolic phospholipase A2 (cPLA2) in temporal lobe epilepsy (TLE)

ABSTRACT

Objectives

Temporal lobe epilepsy (TLE) is the most common form of drug-resistant epilepsy. Blood–brain barrier (BBB) leakage occurs during epileptogenesis and several pieces of evidence suggest that this might contribute to the progression of epilepsy. Seizures trigger a pathway involving glutamate signalling through cytosolic phospholipase A2 (cPLA2). This pathway leads to BBB leakage and induces the expression of drug efflux transporters, leading to drug resistance. Therefore, this study aims to determine the mRNA and protein levels of cPLA2, along with its functional activity, in the hippocampus of pilocarpine model of TLE as well as in the surgically resected hippocampal samples of patients with TLE.

Methods

mRNA levels and protein levels of cPLA2 were evaluated by real-time PCR and western blot analysis respectively in animal model of TLE as well as surgically resected hippocampal tissue specimens of TLE. cPLA2 functional activity was measured spectrophotometrically.

Results

Significant up-regulation of cPLA2 mRNA was observed in the hippocampal samples obtained from TLE rats (p < 0.05) and-TLE patients (p < 0.01). Increased protein expression of cPLA2 was also demonstrated in the hippocampal samples of TLE rats (p < 0.01) as well as TLE patients (p < 0.01). Similarly, functional activity of cPLA2 was found to be up-regulated in the hippocampus of pilocarpine model of TLE rats (p < 0.01) as well as in the TLE patients (p < 0.01).

Discussion

These findings suggest that alterations in cPLA2 expression and activity level in the hippocampus could potentially be a part of dynamic changes associated with TLE.

KEYWORDS:

• cPLA2
• TLE
• BBB damage
• drug-resistance

Acknowledgments

The authors are indebted to all the patients and their families for participating in this study.

Authors contribution

A.B., J.B., A.B.D., P.S.C., and M.T. contributed to the conception and design of the study. A.B., A.S., V.D., J. B., A.B.D. and R.D. contributed to the acquisition and analysis of data. A.B., A.S., J.B., A.B.D., M.S.C., P.S.C. and M.T. contributed to drafting the text and preparing the figures. All authors have read and approved the final version of the manuscript.

Disclosure statement

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

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.

Ethics statement

The study was approved by the Institute Human ethics committee (IEC), All India Institute of Medical Sciences (AIIMS), New Delhi, India and Institute Animal Ethics Committee, AIIMS, New Delhi (File No. 137/IAEC-1/2019). All protocols and experiments were conducted in strict compliance according to the ethical principles and guidelines provided by the National Institutes of Health Guide for Care and Use of Laboratory Animals. The study was conducted in accordance with the Declaration of Helsinki. Written and informed consent was obtained for all the participants.

Additional information

Funding

This work is funded by Grant No. BT/PR20392/MED/122/26/2016 and MEG resource facility grant [BT/MED/122/SP24580/2018] by Department of Biotechnology (DBT), Ministry of Science & Technology, Govt. of India.

Notes on contributors

Jyotirmoy Banerjee

Dr Jyotirmoy Banerjee has done his doctoral studies at Department of Biophysics, University of Delhi South Campus, New Delhi and post-doctoral work at School of Medicine University of Maryland, Baltimore, USA in a National Institute of Health (NIH) funded project. Dr Banerjee is currently appointed as Associate Professor at Department of Biophysics, AIIMS, New Delhi and also in-charge of the Prof. P N Tandon Epilepsy Neurobiology Lab at Centre of Excellence for Epilepsy, AIIMS, New Delhi. Dr Banerjee has established a one of its kind cellular electrophysiology facility at AIIMS, New Delhi, where synaptic transmission can be measured from single neurons in resected brain specimens obtained from patients with drug-resistant epilepsy (DRE). The major emphasis of his current research is directed towards identifying aberrant epileptogenic networks in DRE and its correlation with cellular electrophysiological findings. The ongoing translational research at Dr. Banerjee's lab is of immense importance for the understanding of this distributed network disorder and creating better paradigms for effective treatment of DRE. Dr Banerjee has published more than 50 research articles in peer-reviewed journals.