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Review
. 2023 Jul;18(7):1397-1403.
doi: 10.4103/1673-5374.360345.

Bystanders or not? Microglia and lymphocytes in aging and stroke

Justin N Nguyen  1 , Anjali Chauhan  2
Affiliations
Review

Bystanders or not? Microglia and lymphocytes in aging and stroke

Justin N Nguyen et al. Neural Regen Res. 2023 Jul.

Abstract

As the average age of the world population increases, more people will face debilitating aging-associated conditions, including dementia and stroke. Not only does the incidence of these conditions increase with age, but the recovery afterward is often worse in older patients. Researchers and health professionals must unveil and understand the factors behind age-associated diseases to develop a therapy for older patients. Aging causes profound changes in the immune system including the activation of microglia in the brain. Activated microglia promote T lymphocyte transmigration leading to an increase in neuroinflammation, white matter damage, and cognitive impairment in both older humans and rodents. The presence of T and B lymphocytes is observed in the aged brain and correlates with worse stroke outcomes. Preclinical strategies in stroke target either microglia or the lymphocytes or the communications between them to promote functional recovery in aged subjects. In this review, we examine the role of the microglia and T and B lymphocytes in aging and how they contribute to cognitive impairment. Additionally, we provide an important update on the contribution of these cells and their interactions in preclinical aged stroke.

Keywords: B lymphocytes; T lymphocytes; age; brain; central nervous system; cognition; inflammation; microglia; middle cerebral artery occlusion; neuroinflammation; stroke; white matter injury.

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Conflict of interest statement

None

Figures

Figure 1
Figure 1
Microglia become dysregulated with aging. Aged microglia are robust producers of pro-inflammatory cytokines, and generate reactive oxygen species (ROS), and inflammatory signaling pathways are activated. Accumulation of myelin debris, lipofuscin, and lipid droplets is observed in aged microglia. PGE2: Prostaglandin E2.
Figure 2
Figure 2
The presence of T and B lymphocytes in the healthy brain and after stroke. T and B lymphocytes are present in white matter, subventricular zone, meninges, and CP in the human brain with aging (A). After the stroke, the lymphocytes transmigrate to the injured parenchyma from CP, meninges, sinus, and leaky blood brain barrier (BBB; B). BBB breakdown, and migration of immune cells after stroke (C). CP: Choroid plexus; CSF: cerebrospinal fluid; ICAM-1: intercellular adhesion molecule-1; VCAM-1: vascular cell adhesion molecule-1.
See this image and copyright information in PMC

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