Immune cells can regulate blood pressure

Researchers at Karolinska Institutet and the Feinstein Institute for Medical Research have discovered that the human immune system has a hitherto unknown role – blood pressure regulation. Collaborating with colleagues from Canada, they have found that a special kind of immune cell called acetylcholine-producing lymphocytes can regulate blood pressure in laboratory mice. The study, which is published in Nature Biotechnology, could open the way for new forms of treatment for hypertension.

High blood pressure, or hypertension, is a crucial risk factor for premature death around the world. Despite this, hypertension often has indeterminable causes, although it has long been known that the neurotransmitter acetylcholine plays an important part in that it causes blood vessels to relax and regulates blood pressure by influencing the production of nitric oxide. By studying laboratory mice lacking a certain kind of immune cell called acetylcholine-producing lymphocytes, a research group at Karolinska Institutet and their colleagues at the Feinstein Institute for Medical Research in New York and the University Health Network in Toronto have discovered that these immune cells have a previously unknown function: to reduce the blood pressure.

“These lymphocytes produce acetylcholine that can be delivered to target cells lacking direct contact with nerves,” says lead author Peder Olofsson, researcher at KI’s Department of Medicine in Solna. “It therefore seems that they can transmit signals for regulating the immune system and blood pressure. This is a new piece of the puzzle in our understanding of blood circulation.”

Detailed knowledge

The discovery is of significance to the understanding of how blood pressure is regulated: “If we’re to develop effective and safe therapies for hypertension, we need more detailed knowledge about its underlying biological mechanisms,” he says.

The researchers now hope to find out if acetylcholine-producing lymphocytes play the same key part in regulating blood pressure in humans as well. If this is the case, the next question is whether the immune cells can be made to produce more of this important neurotransmitter so that hypertension can be effectively regulated. These new findings on how this specific immune cell is involved in the regulation of high blood pressure can open the way for new diagnostic and therapeutic methods for hypertension. Since lymphocytes are regulated by the nerve system, the researchers believe that it could one day be possible to control the activity of the immune system through implants that stimulate neuronal signals electronically.

This work was supported by among others National Instiutes of Health; Canadian Institutes for Health Research; Knut and Alice Wallenberg Foundation; The Swedish Heart-Lung Foundation, and The Swedish Society of Medicine.

Publication

”Blood pressure regulation by CD4+ lymphocytes expressing choline acetyltransferase”
Peder S Olofsson, Benjamin E Steinberg, Roozbeh Sobbi, Maureen A Cox, Mohamed N Ahmed, Michaela Oswald, Ferenc Szekeres, William M Hanes, Andrea Introini, Shu Fang Liu, Nichol E Holodick, Thomas L Rothstein, Cecilia Lövdahl, Sangeeta S Chavan, Huan Yang, Valentin A Pavlov, Kristina Broliden, Ulf Andersson, Betty Diamond, Edmund J Miller, Anders Arner, Peter K Gregersen, Peter H Backx, Tak W Mak & Kevin J Tracey, Nature Biotechnology, online 12 September 2016, doi:10.1038/nbt.3663