Distinguishing patients with idiopathic epilepsy from solitary cysticercus granuloma epilepsy and biochemical phenotype assessment using a serum biomolecule profiling platform.

Jay S Hanas,James Randolph Sanders Hocker,Vasudevan Prabhakaran,Douglas A Drevets,Anna Oommen,Hélène Carabin,Vedantam Rajshekhar,Betcy Evangeline

doi:10.1371/journal.pone.0237064

Abstract

A major source of epilepsy is Neurocysticercosis (NCC), caused by Taenia solium infection. Solitary cysticercus granuloma (SCG), a sub-group of NCC induced epilepsy, is the most common form of NCC in India. Current diagnostic criteria for SCG epilepsy require brain imaging which may not be available in communities where the disease is endemic. Identification of serum changes and potential biomolecules that could distinguish SCG epilepsy from idiopathic generalized epilepsy (IE), without the initial need for imaging, could assist in disease identification, understanding, and treatment. The objective here was to investigate, using mass spectrometry (MS), sera biomolecule differences between patients with SCG epilepsy or IE to help distinguish these disorders based on physiological differences, to understand underlying phenotypes and mechanisms, and to lay ground work for future therapeutic and biomarker analyses. Sera were obtained from patients with SCG or IE (N = 29 each group). Serum mass peak profiling was performed with electrospray ionization (ESI) MS, and mass peak area means in the two groups were compared using leave one [serum sample] out cross validation (LOOCV). Serum LOOCV analysis identified significant differences between SCG and IE patient groups (p = 10−20), which became non-significant (p = 0.074) when the samples were randomly allocated to the groups and reanalyzed. Tandem MS/MS peptide analysis of serum mass peaks from SCG or IE patients was performed to help identify potential peptide/protein biochemical and phenotypic changes involving these two forms of epilepsy. Bioinformatic analysis of these peptide/protein changes suggested neurological, inflammatory, seizure, blood brain barrier, cognition, ion channel, cell death, and behavior related biochemical systems were being altered in these disease states. This study provides groundwork for aiding in distinguishing SCG and IE patients in minimally invasive, lower-cost manners, for improving understanding of underlying epilepsy mechanisms, and for further identifying discriminatory biomarkers and potential therapeutic targets.

Highlights

Epilepsy is the most common neurological disorder affecting approximately 1% of the world’s population [1, 2]
A hypothesis in the present study is that solitary cysticercus granuloma (SCG) and idiopathic generalized epilepsy (IE) will elicit disease-specific and systemic host responses reflected in the peripheral blood that can be measured and distinguished by serum mass peak profiling using electro-spray ionization mass spectrometry (ESI-MS)
The results show a clear demarcation between SCG patients and IE patients in the % of SCG leave one [serum sample] out cross validation (LOOCV) classified patient serum mass peaks

Summary

Introduction

Epilepsy is the most common neurological disorder affecting approximately 1% of the world’s population [1, 2]. In India, solitary cysticercus granuloma (SCG), a single stable or degenerating intraparenchymal cysticercus cyst [7,8,9,10], is the most common form of NCC This contrasts with other endemic regions where multiple NCC cysts (MNCC) in the brain are more common [3, 7]. Previous work suggests mass spectrometry (MS) analysis of peripheral blood could aid in NCC diagnosis [13] This is important because current serological tests are unreliable in diagnosing NCC and sub-groups like SCG in the absence of brain imaging. A hypothesis in the present study is that SCG and IE will elicit disease-specific and systemic host responses reflected in the peripheral blood that can be measured and distinguished by serum mass peak profiling using electro-spray ionization mass spectrometry (ESI-MS). Biochemical phenotypes and cellular pathways possibly at play in these disorders, as reflected from the tandem MS/MS structural analysis of peptides and proteins in sera, were examined to help understand underlying mechanisms and provide physiological basis for the SCG versus IE patient discriminations

Materials and methods

Results

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