title: Senescent CD14+CD16+ monocytes exhibit proinflammatory and proatherosclerotic activity.
abstract: In elderly subjects and in patients with chronic inflammatory diseases, there is an increased subset of monocytes with a CD14(+)CD16(+) phenotype, whose origin and functional relevance has not been well characterized. In this study, we determined whether prolonged survival of human CD14(++)CD16(-) monocytes promotes the emergence of senescent cells, and we analyzed their molecular phenotypic and functional characteristics. We used an in vitro model to prolong the life span of healthy monocytes. We determined cell senescence, intracellular cytokine expression, ability to interact with endothelial cells, and APC activity. CD14(+)CD16(+) monocytes were senescent cells with shortened telomeres (215 ± 37 relative telomere length) versus CD14(++)CD16(-) cells (339 ± 44 relative telomere length; p < 0.05) and increased expression of β-galactosidase (86.4 ± 16.4% versus 10.3 ± 7.5%, respectively; p = 0.002). CD14(+)CD16(+) monocytes exhibited features of activated cells that included expression of CD209, release of cytokines in response to low-intensity stimulus, and increased capacity to sustain lymphocyte proliferation. Finally, compared with CD14(++)CD16(-) cells, CD14(+)CD16(+) monocytes showed elevated expression of chemokine receptors and increased adhesion to endothelial cells (19.6 ± 8.1% versus 5.3 ± 4.1%; p = 0.033). In summary, our data indicated that the senescent CD14(+)CD16(+) monocytes are activated cells, with increased inflammatory activity and ability to interact with endothelial cells. Therefore, accumulation of senescent monocytes may explain, in part, the development of chronic inflammation and atherosclerosis in elderly subjects and in patients with chronic inflammatory diseases.
authors.affiliation: Instituto Maimónides de Investigación Biomédica de Córdoba/Fundación de Investigaciones Biomédicas de Córdoba, Hospital Universitario Reina Sofia, Córdoba, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Merino
authors.forename: Paula
authors.initials: P
authors.lastname: Buendia
authors.forename: Alejandro
authors.initials: A
authors.lastname: Martin-Malo
authors.forename: Pedro
authors.initials: P
authors.lastname: Aljama
authors.forename: Rafael
authors.initials: R
authors.lastname: Ramirez
authors.forename: Julia
authors.initials: J
authors.lastname: Carracedo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000150:complications / Q000276:immunology* / Q000473:pathology*; D015415:Biomarkers / Q000378:metabolism; D002448:Cell Adhesion / Q000276:immunology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000276:immunology*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007249:Inflammation / Q000150:complications / Q000276:immunology / Q000473:pathology; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D017452:Receptors, IgG / Q000096:biosynthesis*
chemical_list: D015415:Biomarkers; D018950:Lipopolysaccharide Receptors; D017452:Receptors, IgG