Modeling the simultaneous dynamics of proteins in blood plasma and the cerebrospinal fluid in human in vivo

The analysis of protein dynamics or turnover in patients has the potential to reveal altered protein recycling such as in Alzheimer disease, and to provide informative data regarding drug efficacy, or certain biological processes. The observed protein dynamics in a solid tissue or a fluid is the net result of protein synthesis and degradation, but also transport across biological compartments. We report a first model to simultaneously model protein dynamics observed in blood plasma and the cerebrospinal fluid (CSF) taking into account transport. We applied this model to 65 proteins of a single individual displaying similar or very different dynamics in plasma and CSF. The model structure indicates an active control at the blood-CSF barrier. This type of model has the potential to reveal altered transport or barriers resulting from disease in future studies.