In a new study, researchers in Germany have discovered why sleep can sometimes be the best medicine.
They find sleep improves the potential ability of some of the body’s immune cells to attach to their targets.
The study was led by researchers at the University of Tübingen. It helps explain how sleep can fight off an infection, whereas other conditions, such as chronic stress, can make the body more susceptible to illness.
T cells are a type of white blood cell that are critical to the body’s immune response.
When T cells recognize a specific target, such as a cell infected with a virus, they activate sticky proteins known as integrins that allow them to attach to their target and, in the case of a virally infected cell, kill it.
While much is known about the signals that activate integrins, signals that might dampen the ability of T cells to attach to their targets are less well understood.
In the study, the team decided to examine the effects of a diverse group of signaling molecules known as Gαs-coupled receptor agonists.
Many of these molecules can suppress the immune system, but whether they inhibit the ability of T cells to activate their integrins and attach to target cells was unknown.
They found that certain Gαs-coupled receptor agonists, including the hormones adrenaline and noradrenaline, the proinflammatory molecules prostaglandin E2 and D2, and the neuromodulator adenosine, prevented T cells from activating their integrins after recognizing their target.
Adrenaline and prostaglandin levels dip while the body is asleep.
The team compared T cells taken from healthy volunteers while they slept or stayed awake all night.
T cells taken from sleeping volunteers showed significantly higher levels of integrin activation than T cells taken from wakeful subjects.
The researchers were able to confirm that the beneficial effect of sleep on T cell integrin activation was due to the decrease in Gαs-coupled receptor activation.
In addition to helping explain the beneficial effects of sleep and the negative effects of conditions such as stress, the study could spur the development of new therapeutic strategies that improve the ability of T cells to attach to their targets.
This could be useful, for example, for cancer immunotherapy, where T cells are prompted to attack and kill tumor cells.
The study is published in the Journal of Experimental Medicine.
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Source: Journal of Experimental Medicine.
