Sleep May Strengthen Long-term Immune System Memories

Over a century ago, scientists demonstrated that sleep supports the retention of memories of facts and events. Later studies have shown that slow-wave sleep, often referred to as deep sleep, is important for transforming fragile, recently formed memories into stable, long-term memories.

Now researchers propose that deep sleep may also strengthen immunological memories of previously encountered pathogens.

“While it has been known for a long time that sleep supports long-term memory formation in the psychological domain, the idea that long-term memory formation is a function of sleep effective in all organismic systems is in our view entirely new,” says senior author Jan Born of the University of Tuebingen. “We consider our approach toward a unifying concept of biological long-term memory formation, in which sleep plays a critical role, a new development in sleep research and memory research.”

The immune system “remembers” an encounter with a bacteria or virus by collecting fragments from the bug to create memory T cells, which last for months or years and help the body recognize a previous infection and quickly respond.

Gist Information

These memory T cells appear to abstract “gist information” about the pathogens, as only T cells that store information about the tiniest fragments ever elicit a response. The selection of gist information allows memory T cells to detect new pathogens that are similar, but not identical, to previously encountered bacteria or viruses.

Studies in humans have shown that long-term increases in memory T cells are associated with deep slow-wave sleep on the nights after vaccination.

Taken together, the findings support the view that slow-wave sleep contributes to the formation of long-term memories of abstract, generalized information, which leads to adaptive behavioral and immunological responses.

The obvious implication is that sleep deprivation could put your body at risk.

“If we didn’t sleep, then the immune system might focus on the wrong parts of the pathogen,” Born says. “For example, many viruses can easily mutate some parts of their proteins to escape from immune responses. If too few antigen-recognizing cells [the cells that present the fragments to T cells] are available, then they might all be needed to fight off the pathogen.

In addition to this, there is evidence that the hormones released during sleep benefit the crosstalk between antigen-presenting and antigen-recognizing cells, and some of these important hormones could be lacking without sleep.”

Born says that future research should examine what information is selected during sleep for storage in long-term memory, and how this selection is achieved.

In the end, this research could have important clinical implications.

“In order to design effective vaccines against HIV, malaria, and tuberculosis, which are based on immunological memory, the correct memory model must be available,” Born says. “It is our hope that by comparing the concepts of neuronal and immunological memory, a model of immunological memory can be developed which integrates the available experimental data and serves as a helpful basis for vaccine development.”

Article originally appeared on sciencebeta.com

Ease Sore Muscles and Improve Blood Flow with Massage

Massage therapy can help ease sore muscles and improve blood flow for people who are active as well as for those who do not exercise, a small study finds.

Those effects can last for more than 72 hours, researchers found. People with poor circulation or limited ability to move are among those who could benefit most from massage therapy, they noted.

“Our study validates the value of massage in exercise and injury, which has been previously recognized but based on minimal data,” Nina Cherie Franklin, study first author and a postdoctoral fellow in physical therapy at the University of Illinois at Chicago, said in a university news release. “It also suggests the value of massage outside of the context of exercise.”

In the study, the researchers asked 36 healthy but inactive young adults to use a leg press machine until their legs became sore. Half of the participants were given a Swedish leg massage after they exercised. All of the participants rated their muscle soreness on a scale from one to 10. A third comparison group did not exercise, but got a massage.

Although both exercise groups were sore right after their workout, the people who got the massage said they had no soreness 90 minutes later. In contrast, those in the group that didn’t receive a massage said they were sore 24 hours after they exercised.

Because muscle injury from exercise has been shown to reduce blood flow, researchers say, they also measured the participants’ “brachial artery flow mediated dilation” in their arms. This standard measure of general vascular health was taken 90 minutes as well as one, two and three days after exercise.

The people who got a massage after they exercised had improved blood flow at every testing interval and the benefits of the massage didn’t dissipate until after 72 hours had passed, researchers found. People who did not receive a massage after exercise had reduced blood flow after 90 minutes and returned to normal levels at 72 hours.

“We believe that massage is really changing physiology in a positive way,” Franklin said. “This is not just blood flow speeds — this is actually a vascular response.”

And massage doesn’t just help people who exercise, the researchers also found.

“The big surprise was the massage-only control group, who showed virtually identical levels of improvement in circulation as the exercise and massage group,” study principal investigator Shane Phillips, an associate professor of physical therapy at UIC, said in the news release. “The circulatory response was sustained for a number of days, which suggests that massage may be protective.”

The study found that participants’ blood flow was changed far away from the sore muscles. Researchers concluded that massage benefits are systemic and not confined to one specific area of the body.

While the study found an association between massage and improved circulation, it did not establish a cause-and-effect relationship.

The study was recently published online ahead of publication in the Archives of Physical Medicine and Rehabilitation.