San Diego

Investigating How Bacteria Cross the Blood-Brain Barrier




​The blood-brain barrier is a thin network of blood vessels with cells that border one another very closely, forming protein junctions too tight for bacteria and viruses to slip through. When the barrier is breached, though, the result can be bacterial meningitis, a frequently deadly disease caused when the brain becomes dangerously inflamed.

Using animal cell cultures, Dr. Kelly Doran and her student, Brandon Kim, are investigating how one type of bacteria, group B streptococcus, permeates the brain's defenses.

The cells of the blood-brain barrier fire off a protective molecular signal as receptors along the blood side of the barrier detect the Group B strep bacteria. But exposure to the bacteria also induces a gene to produce a transcription factor protein that contributes to the breakdown of the barrier's tight junctions. The cells in turn destroy the integrity of the barrier, permitting bacteria to enter the brain.

A better understanding of this process could allow scientists to develop therapeutics that temporarily control this reaction, thus preventing the self-destruction of the blood-brain barrier. Additionally, this knowledge might allow researchers to harness the process to design drugs that tell the blood-brain barrier to let them through so they can fight some brain diseases.​

The research is funded by the National Institute of Neurological Disorders and Stroke.