Using Host Responses to Neurocysticercosis to Develop Novel, Brain-imaging Free Diagnostics: a US-India Partnership
Neurocysticercosis (NCC) is a parasitic infection of the brain that accounts for 34% of active epilepsy cases in Vellore district, India. New methods for diagnosing NCC are badly needed because the cost of diagnostic imaging is beyond the means of most patients, and 34% of NCC patients are missed by the gold standard for antibody detection. Our National Institute of Neurological Disease and Stroke (R21NS077466) and Indian Ministry of Science and Technology (BT/MB/BRCP/06/2011)-funded pilot study used mRNA arrays of blood monocytes followed by qPCR confirmation to identify differentially expressed genes in patients with NCC- associated seizures / epilepsy (referred to as epilepsy) compared to controls with and without epilepsy. This approach identified 15 genes of interest showing highest expression levels in patients with NCC-associated epilepsy, followed by patients with resolved NCC and finally by those with idiopathic epilepsy. Expression levels of some genes differed among NCC patients with different types of brain lesions with expression decreasing as lesions resolved. In addition, sera from the same patients were analyzed by electrospray ionization mass spectrometry (ESI-MS) to identify mass/charge peaks that could discriminate between NCC patients and controls. Notably, ESI-MS also distinguished NCC from idiopathic seizures / epilepsy, and both ESI-MS and gene expression studies identified overexpression of RAP1A at the protein levels and mRNA levels, respectively, in NCC patients. These results are extremely promising for developing novel diagnostic tools. Our central hypothesis is that NCC-associated epilepsy can be diagnosed by peripheral biomarkers and will be tested with two research specific aims. Specific Aim 1 will establish the relevance of preliminarily identified candidate genes to NCC. In a first sub-aim, we will assess in-vitro relationships between exposure to T. solium metacestodes' antigens and expression of candidate genes in patient monocytes and in monocyte- like cell lines. The second sub-aim will measure candidate gene expression in monocytes prospectively in NCC patients during therapy and as their lesions change, and will be compared with expression levels of the same genes in whole blood. Specific Aim 2 will identify the proteins/peptides causing differentially expressed mass peaks in serum of patients with NCC-associated seizures and confirm their specificity to NCC. Tandem MS/MS will be used to identify proteins linked to ESI-MS mass peaks that discriminate between NCC-associated seizures and other group of patients. Capacity Building Aim 1 will train one junior faculty member and one research fellow in the use of mass spectrometry as a diagnostic tool. Capacity Building Aim 2 will train laboratory personnel at all levels in cellular and molecular techniques used to study host responses to infection. Successful completion of these aims will identify candidate biomarkers of NCC-associated seizures for field testing and determine their ability to predict different types of NCC-related lesions. Local expertise will be developed in India to conduct these studies and pursue novel insights into the biology of NCC.