The team has identified a new anatomical path through which the brain and the spleen communicate. The spleen once thought to be an unnecessary bit of tissue, is a manufacturing plant for immune cells, and a site where immune cells and nerves interact.
It defends the body against infection, particularly encapsulated bacteria that circulate through the blood.
Lead researcher Mauricio Rosas-Ballina, MD discovered that macrophages in the spleen were making tumour necrosis factor (TNF), a powerful inflammation-producing molecule.
When they stimulated the vagus nerve, a long nerve that goes from the base of the brain into thoracic and abdominal organs, TNF production in the spleen decreased.
Previous studies have also shown that stimulation of the vagus nerve increases survival in laboratory models of sepsis, a syndrome triggered when the body's immune system wages an attack on the body that is well beyond its normal response to an invader.
While analysing the pathway of the vagus nerve to establish the route it follows to reach the spleen, Rosas-Ballina found that the vagus nerve inherently communicates with the splenic nerve to suppress TNF production by macrophages in the spleen.
He said that results of this study suggest that there may be two separate ways the brain communicates with the spleen to regulate immune function, which pinpoints the way to a possible solution for treating sepsis.
The researchers hope to modulate other immune functions like antibody production through the spleen (via vagus nerve stimulation) as a way to modify the course of infections and possibly some autoimmune disorders.
The findings were published today in the Proceedings of the National Academy of Sciences.