The effects of doxorubicin on blood-brain barrier integrity in hCMEC/D3.

Current chemotherapy regimens have significantly improved overall survival for children with cancer. However, these treatments are associated with detrimental side effects like chemotherapy-induced cognitive impairment (CICI), or "chemobrain." Measurable deficits in cognitive function persist years after treatment. Specifically, doxorubicin (DOXO), a commonly used chemotherapeutic agent in curative regimens for children with cancer, plays a pivotal role in the development of CICI, even though it doesn't cross the blood-brain barrier (BBB). Using a juvenile rat model, we found that DOXO compromises the BBB integrity. To further address the poorly understood mechanism of DOXO-related CICI, we utilized human cerebral microvascular endothelial cells (hCMEC/D3) to study the changes induced by DOXO in BBB integrity. RNA sequencing after DOXO exposure demonstrated changes in inflammatory pathways that may play a critical role in BBB integrity. Upon DOXO treatment, there was an increase in the secretion of proinflammatory cytokines including interleukin-6 (IL-6), regulated on activation, normal T cell expressed and secreted (RANTES) and granulocyte-macrophage colony stimulating factor (GM-CSF). DOXO induced the activation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases (ERK1/2), and cAMP response element binding protein (CREB). Using xCELLigence Real Time Cell Analysis, we found that DOXO doesn't immediately compromise the barrier in hCMEC/D3. Additionally, we found that DOXO treatment significantly decreases maximal respiration and the spare respiratory capacity in hCMEC/D3 cells, indicating mitochondrial bioenergetic defects. Our findings provide critical insights on how DOXO impacts the BBB and builds a foundation for developing preventative measures that may improve the quality of life for patients.