Understanding ischemia in children with tuberculous meningitis (iThemba)

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PROJECT SUMMARY Background: One million children develop tuberculosis (TB) each year and a quarter of these die. TB meningitis (TBM) is the most severe form of TB disease and even if diagnosed and treated, 20% die and over 50% of survivors are left with permanent neurological disability. Much of the morbidity and mortality associated with TBM is due to infarction caused by large and small vessel inflammation and thrombosis. Despite this, our understanding of the pathogenesis of infarction in TBM is limited, especially in children. We hypothesize that imbalance of the endothelial and plasma pro- and anti-thrombotic mechanisms, inflammatory pathways and vascular proliferative processes underlies cerebral infarction in TBM. Our group has an extensive track record of clinical research into children with TBM and the research team consists of world leaders in the fields of clinical epidemiology, proteomics, transcriptomics, bioinformatics, neurosciences, and radiology. Methods: We will recruit 80 children with probable or confirmed TBM over 30 months and obtain samples of blood and cerebrospinal fluid (CSF). All children will undergo MRI and FDG PET/CT at baseline and at 2 weeks they will have repeat MRI with further blood and CSF samples collected. MRI will then be carried out at 24 weeks will neurodevelopmental assessment at 48 weeks. The neuroimaging will quantify differences between children with and without infarction and relate imaging to clinical presentation and outcome. It will also identify penumbral regions indicating future infarct development/evolution. We will enrich the laboratory analyses with samples from 50 children with probable or confirmed TBM, recruited between 2016 and 2020. RNA sequencing of blood and CSF will be used to identify differentially expressed genes and identify implicated biological pathways between children with and without infarction and between samples taken at baseline and at 2 weeks. Targeted immunoassays and discovery mass spectrometry will be performed on plasma and CSF to determine differences in protein abundance, with a focus on proteins involved in coagulation and endothelial function. Finally, we will integrate the transcriptomics, proteomics and radiomics to generate a comprehensive understanding of the pathogenesis of infarction in children with TBM. We aim to group children into several biological/anatomical phenotypes, each of which may benefit from a different therapeutic approach. We will then explore, using computer simulation, the impact of therapeutic interventions on biological pathways in each phenotype. We anticipate that this work could pave the way for the development of point-of-care tests that could stratify therapy at the time of diagnosis. Impact: A more comprehensive understanding of the pathophysiology of infarction in children with TBM would permit targeted host-directed therapies, with the potential to moderate or eliminate the consequences of this devastating condition.