NCMP-13. EXPLORING THE PATHOPHYSIOLOGY OF HYDROCEPHALUS IN CHOROID PLEXUS PAPILLOMA

Abstract BACKGROUND Choroid plexus papilloma (CPP) is a benign intraventricular lesion associated with hydrocephalus and ventricular outflow obstruction. However, the molecular mechanism by which cerebrospinal fluid (CSF) is produced by choroid plexus (CP), or by which CSF production is altered in the setting of CPP to cause hydrocephalus, is unknown. METHODS A PRISMA systematic literature review was conducted to identify gene targets associated with CSF production. Primary tissue samples of CP and CPP from the same patient were obtained, and expression of target genes was assessed using immunohistochemistry and quantified using QuPath software H-scoring. Single-nucleus sequencing of both CP and CPP was also completed, and differential expression of identified target genes was evaluated by calculating log fold change. RESULTS Systematic literature review yielded 25 studies in animal models and 18 unique gene targets. 16 targets were expressed in primary CP and CPP tissue samples upon immunohistochemistry staining. 11 of 18 targets revealed significant differential expression between CP and CPP on single-nucleus sequencing. Genes with notable expression increases in CPP included ion transporters NKCC1 (Na-K-Cl cotransporter) and TRPV4 (non-selective cation channel), as well as carbonic anhydrase II. CONCLUSIONS We present evidence that choroid plexus papilloma has altered expression of genes previously implicated in CSF production. Upregulation of membrane transporters and cytoplasmic enzymes involved in Na+, K+, Cl-, and HCO3- transport may provide a mechanistic explanation for the development of hydrocephalus in CPP. Pharmacologic inhibition of CSF production may offer a route for non-surgical management of CPP, as well as other pathologies causing hydrocephalus.