AQP1 Overexpression in the CSF of Obstructive Hydrocephalus and Inversion of Its Polarity in the Choroid Plexus of a Chiari Malformation Type II Case

The choroid plexus (ChP) is involved in the production of cerebrospinal fluid (CSF) and is intimately related to CSF physiopathology. Aquaporin-1 (AQP1) is the water channel directly implicated in CSF production and a potential therapeutic target in the management of CSF circulation disorders. Pathologies that present ventriculomegaly are associated with defective CSF turnover and AQPs are involved in both the production and reabsorption of CSF. This work examines the levels of AQP1 and its dynamics in ventriculomegaly conditions such as congenital hydrocephalus (communicating and obstructive) or type II lissencephaly versus control. We specifically address the expression of AQP1 in the CSF of 16 term-pregnancy infants where it was found to be significantly increased in obstructive cases when compared with communicating hydrocephalus or control patients. We also defined histologically the expression of AQP1 in the ChP from 6 nonsurvival preterm-pregnancy infants ranging ages between 20 and 25 gestational weeks in which AQP1 was mainly expressed at the apical pole of the ChP epithelium (ChPE) in control and lissencephalic patients. AQP1 expression from the Chiari malformation case showed an inverted polarity being expressed in the basal pole of the ChPE colocalizing with the glucose transporter 1 where this transporter is naturally located.