B Cells Play a Surprising Role in Bone Marrow Output
New research in Nature Immunology has found that B cells play a surprising role in increasing or decreasing the bone marrow’s output of white blood cells. The findings may lead to new treatments for conditions that arise when white blood cell production goes out of balance.
Professor Matthias Nahrendorf, senior author of the study, explained that the nervous system plays a role in controlling blood cell production through neurotransmitters. “This is for instance important in people exposed to stress, where stress hormones — part of the ‘fight-or-flight’ response controlled by the sympathetic nervous system — may increase bone marrow activity and cardiovascular inflammation in response to the neurotransmitter noradrenaline,” he said. The parasympathetic nerves on the other hand, slow down responses and bring about a state of calm to the body, mainly through the neurotransmitter acetylcholine.
Because acetylcholine can have a protective effect against inflammation and heart disease, the researchers studied this neurotransmitter in the bone marrow. “When we looked into how acetylcholine acts on the production of blood cells, we found that it does the expected — it reduces white blood cells, as opposed to noradrenaline, which increases them,” said Prof Nahrendorf. “What was unexpected though was the source of the neurotransmitter acetylcholine.”
In the bone marrow, the typical nerve fibres that are known to release acetylcholine were not found. Instead, it was the antibody-producing B cells supplied the acetylcholine in the bone marrow. “Thus, B cells counter inflammation — even in the heart and the arteries — via dampening white blood cell production in the bone marrow. Surprisingly, they use a neurotransmitter to do so,” said Prof Nahrendorf.
Tapping into this process may help investigators develop strategies to block inflammation in cardiovascular conditions such as atherosclerosis. “Ultimately this may lead to new therapeutics that combat myocardial infarction, stroke, and heart failure,” said Prof Nahrendorf.
Source: Massachusetts General Hospital
