Investigating hydrocephalus pathophysiology: an analysis of the role of lysophosphatidic acid in TRPV4-mediated electrolyte flux in choroid plexus epithelial cells

Hydrocephalus is a neurological disorder characterized by accumulation of cerebrospinal fluid (CSF) due to excess production, decreased reabsorption, and/or blockage of flow within the ventricles of the brain. The excessive CSF volume causes symptoms such as ventriculomegaly, increased intracranial pressure, and cell damage. CSF is produced by the choroid plexus, which consists of a fenestrated capillary network surrounded by a monolayer of choroid plexus epithelial cells (CPe). CPe are polarized, meaning that distinct ion channels are located on an apical (CSF-facing) or basolateral (blood-facing) side of the cell, and together these secrete approximately 500 ml of CSF daily in an adult human. Previous studies reported that there is a connection between a regulatory channel of CSF production, transient receptor potential vanilloid 4 (TRPV4), a sodium potassium chloride cotransporter (NKCC1), and the inflammatory mediator lysophosphatidic acid (LPA). Toft-Bertelsen et al. suggest that elevated levels of LPA found in the CSF of patients acts as an agonist to TRPV4. Their experiments in rats suggest that activation of TRPV4 leads to secondary activation of the NKCC1 channel via influx of calcium, leading to excessive secretion of CSF (1). In the human choroid plexus papilloma cell line (HIBCPP), our laboratory has failed to find an interaction between TRPV4 mediated ion flux and NKCC1. We hypothesized that if there is a connection between TRPV4 and LPA, the addition of LPA would cause a potentiated response to a TRPV4 agonist. We used in Ussing-style electrophysiological studies to monitor transepithelial electrolyte flux via short-circuit current and change in transepithelial permeability via transepithelial resistance and secretion assays to measure fluid movement across the cells. Live cell imaging with a Keyence microscope was used to visualize changes in cell morphology during treatment. Addition of TRPV4 agonist caused increased transepithelial electrolyte flux, decreased transcellular resistance, increased fluid secretion, and changes in cell morphology (transient swelling). Preincubation of 10 minutes with physiologically relevant concentrations of LPA (40µM) had no effect on baseline ion flux or permeability and failed to alter the TRPV4 agonist-induced change in electrolyte flux or cellular permeability. In addition, LPA did not potentiate the TRPV4 agonist mediated fluid secretion. Conversely, LPA statistically inhibited the increased fluid secretion. Contrary to published studies, these results show that physiologically relevant levels of LPA do not significantly alter TRPV4-mediated stimulation of the electrolyte and fluid flux that is consistent with CSF production. References: 1. Toft-Bertelsen et al. (2022). Fluids Barriers CNS 19, 69. This research was conducted with the support of DoD Congressional Directed Medical Research Program Grants #HT94252310296 and #HT94252310401 (BBY). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.