Project description:Aging is associated with systemic chronic inflammation (inflammaging) that leads to impaired physiological functions and vulnerability to several diseases. However, underlying alterations in aged immune system resulting in gradual loss of immune fitness4 remain unclear. Using a combination of single-cell RNA/TCR/BCR-sequencing and extensive FACS/CyTOF-based validation, we comprehensively characterize age-associated alterations in immune cells in 4 mouse organs and human blood. We identified both organ-specific and common changes in immune cell populations and their transcriptional programs and found age-associated subpopulation of CD8+ T cells marked with expression of GZMK.
Project description:Acute cognitive impairment (i.e., delirium) is common in elderly emergency department patients and frequently results from infections that are unrelated to the central nervous system. Since activation of the peripheral innate immune system induces brain microglia to produce inflammatory cytokines that are responsible for behavioral deficits, we investigated if aging exacerbated neuroinflammation and sickness behavior after peripheral injection of lipopolysaccharide (LPS). Microarray analysis revealed a transcriptional profile indicating the presence of primed or activated microglia and increased inflammation in the aged brain. Furthermore, aged mice had a unique gene expression profile in the brain after an intraperitoneal injection of LPS, and the LPS-induced elevation in the brain inflammatory cytokines and oxidative stress was both exaggerated and prolonged compared with adults. Aged mice were anorectic longer and lost more weight than adults after peripheral LPS administration. Moreover, reductions in both locomotor and social behavior remained 24 h later in aged mice, when adults had fully recovered, and the exaggerated neuroinflammatory response in aged mice was not reliably paralleled by increased circulating cytokines in the periphery. Taken together these data establish that activation of the peripheral innate immune system leads to exacerbated neuroinflammation in the aged as compared with adult mice. This dysregulated link between the peripheral and central innate immune system is likely to be involved in the severe behavioral deficits that frequently occur in older adults with systemic infections. Experiment Overall Design: In this study, adult and aged mice were injected intraperitoneal with sterile saline or Escherichia coli LPS (0.33 mg/kg, ~10 µg/mouse; serotype 0127:B8, Sigma). This dosage of LPS was used because it induces a mild transient sickness behavior in young adults. Mice were killed 4 h after saline or LPS injection by CO2 asphyxiation. Blood samples were collected and brains were removed, separated in half at the longitudinal fissure, frozen in liquid nitrogen, and stored (-80°C) until assaying. Total RNA was later isolated from some brain samples for microarray analysis (n=3).
Project description:Acute cognitive impairment (i.e., delirium) is common in elderly emergency department patients and frequently results from infections that are unrelated to the central nervous system. Since activation of the peripheral innate immune system induces brain microglia to produce inflammatory cytokines that are responsible for behavioral deficits, we investigated if aging exacerbated neuroinflammation and sickness behavior after peripheral injection of lipopolysaccharide (LPS). Microarray analysis revealed a transcriptional profile indicating the presence of primed or activated microglia and increased inflammation in the aged brain. Furthermore, aged mice had a unique gene expression profile in the brain after an intraperitoneal injection of LPS, and the LPS-induced elevation in the brain inflammatory cytokines and oxidative stress was both exaggerated and prolonged compared with adults. Aged mice were anorectic longer and lost more weight than adults after peripheral LPS administration. Moreover, reductions in both locomotor and social behavior remained 24 h later in aged mice, when adults had fully recovered, and the exaggerated neuroinflammatory response in aged mice was not reliably paralleled by increased circulating cytokines in the periphery. Taken together, these data establish that activation of the peripheral innate immune system leads to exacerbated neuroinflammation in the aged as compared with adult mice. This dysregulated link between the peripheral and central innate immune system is likely to be involved in the severe behavioral deficits that frequently occur in older adults with systemic infections. Keywords: Aging, cytokines, brain, inflammation, behavior
Project description:To study the differential role of central nervous system-associated macrophages (CAMs) in neuroinflammation after stroke between young and aged mice, we FACS sorted CD3-CD11b+CD45+CD206+ CAMs from brains of C57BL/6 mice aged 2 months (young) and 18 months (old)
Project description:Phenotypic and functional changes seen in the aged adaptive immune system are primarily driven by aging of hematopoietic stem cells (HSCs), pharmacological rejuvenated aged HSCs were able to reconstituted a youthful immune system
Project description:Glycyrrhizic acid (GA) has numerous biological activities, but the mechanism by which it regulates the immune system and improves cognition in aged mice remains unclear. In this study, we analyzed single-cell sequencing data of peripheral blood mononuclear cells from young mice, aged mice, and GA-treated aged mice, and found that GA reduced senescence-induced increases in macrophages and neutrophils, and increased numbers of lymphoid lineage subpopulations specifically reduced by senescence. In vitro, GA significantly promoted differentiation of Lin-CD117+ hematopoietic stem cells toward lymphoid lineages, especially CD8+ T cells. Moreover, GA inhibited differentiation of CD4+ T cells and myeloid (CD11b+) cells by binding to the S100 calcium-binding protein 8 (S100A8). Overexpression of S100A8 in Lin- CD117+ hematopoietic stem cells enhanced cognition in aged mice and in immune reconstited severely immunodeficient B-NDG mice. Collectively, our results suggest that GA exerts anti-aging effects by binding to S100A8 to remodel the immune system of aged mice.
Project description:In this study, we performed single-cell RNA sequencing (scRNA-seq) on MAIT cells extracted from the intestines of young and aged mice. For each age group, MAIT cells from five individual mice were pooled before sequencing.