August 21, 2007 -- An abnormal immune system can mistake body tissue for a foreign invader and attack it, causing inflammation. Researchers are learning how similar dynamics occur in the brain. Agricultural Research Service ( ARS ) scientists have found that blueberry extracts helped quell the inflammation that was produced when the brain's immune cells responded to oxidative stress, based on a cell-culture study.

Lead author, molecular biologist Francis Lau, and neuroscientist James Joseph conducted the study at the USDA's Jean Mayer Human Nutrition Research Center on Aging at Tufts University in Boston, Mass. Joseph leads the HNRCA 's Neuroscience Laboratory . ARS is USDA's chief scientific research agency. The study was published in the Journal of Neuroscience Research.

Inflammation is thought to be stoked by the overactivation of the brain's immune cells, called microglia. While seeking to protect and repair injured brain tissue, microglia produce and send out chemical stress signals—some of which are called cytokines—to other cells. Those signals begin a cascade of reactions, including the activation of genes that express proteins and other stress chemicals to help clear away cellular debris.

Microglia can become chronically overactivated, for example, in response to accumulation of brain plaques, which in turn is thought to trigger inflammation.

Lau used a rodent microglial cell line as a model to study toxin-induced microglial activation. He exposed groups of those test cells to various levels of blueberry extracts. He then challenged the cells with oxidative stress by exposing them to the toxin that triggers the secretion of inflammatory chemicals.

Neuroinflammation has been linked to the expression of genes that spew, among others, two inflammatory enzymes, iNOS and COX-2, and two cytokines, IL-1â and TNF-á. Lau used a detection method to find and measure the expression of genes that produced iNOS and COX-2 in the stress-induced cell cultures. He found that the blueberry treatment significantly reduced that expression.

The blueberry extract also markedly lessened secretion of the two inflammatory cytokines.

Read more about this research in the August issue of Agricultural Research magazine.

Originally published on ars.usda.gov