Immunity against brain aging
Researchers from Albany Medical College in New York have discovered that type 2 congenital lymphoid cells (ILC2) accumulate in brain tissue with age. They suggested that exposure to them may reduce age-related cognitive decline and help in the fight against neurodegenerative diseases associated with aging in humans.
Immune cells in the brains of young (left) and old (right) mice. The ILC 2 are indicated by white arrows. Other types of immune cells are indicated by blue arrows. Source: article in the Journal of Experimental Medicine.
The ILC2S are found in certain tissues of the body and help to repair them when damaged. For example, it has recently been shown that the ILC 2 in the spinal cord promotes healing after injury. But it was not yet known whether there is ILC2 in other parts of the central nervous system and how they react to aging.
The team examined the brains of young and old mice and found that the ILC2 accumulated with age in the choroid plexus. This structure produces cerebrospinal fluid and is topographically close to the hippocampus, a part of the brain that is involved in learning and memory processes. Older mice had five times more ILC2 in their brains than younger mice. It is important to note that the researchers also found a large amount of ILC2 in the choroid plexus of the brain of elderly people.
The ILC 2s in the brains of old mice were mostly inactive, but the researchers were able to activate them by injecting animals with interleukin 33 (IL-33), which causes cells to synthesize proteins that stimulate the formation and repair of neurons. The researchers found that, unlike the young animals' ILC2, in older mice they were able to live longer, and the introduction of IL-33 more often brought them into an active state.
The researchers injected old mice with IL-33 or pre-activated in the laboratory with ILC 2; in both cases, the animals' performance improved in a series of cognitive tests designed to assess their learning and memory. This means that activated in vitro or in vivo ILC2 can improve the cognitive functions of old mice.
One of the proteins produced by activated ILC2 is the cytokine interleukin 5 (IL-5). The research team found that treating old mice with IL-5 increased the growth of new neurons in the hippocampus and reduced potentially damaging inflammation in the brain. IL-5 treatment also improved the cognitive abilities of older mice in a number of tests.
Thus, this study proved the accumulation of ILC 2 in the choroid plexus of the aging brain and demonstrated that their activation can "rejuvenate" the old brain and reduce age-related cognitive decline. Aging is a major risk factor for various neurocognitive and neurodegenerative diseases, and the activation of ILC2 cells in the aging brain may provide new opportunities to combat these diseases in humans.
Article by I.T.H.Fung et al. Activation of group 2 innate lymphoid cells allows aging-associated cognitive decline is published in the Journal of Experimental Medicine.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on EurekAlert: Activating immune cells could revitalize the aging brain, study suggests.