title: Accumulation of murine subretinal macrophages: effects of age, pigmentation and CX3CR1.
abstract: Macrophages or activated microglia in the subretinal space are considered a hallmark of some retinal pathologies. We investigated the effects of age, pigmentation and CX(3)CR1 deficiency on the accumulation of macrophages/activated microglia in the outer retina of young and old Cx(3)cr1(gfp/gfp) (CX(3)CR1-deficient) or Cx(3)cr1(gfp/+) mice on either a pigmented (C57BL/6) or albino (BALB/c) background. Quantitative analysis of immunostained retinal-choroidal whole mounts revealed an increase in subretinal macrophage (SRMΦ) numbers in young Cx(3)cr1(gfp/gfp) mice compared with Cx(3)cr1(gfp/+) mice, however the increase was more marked in albino Cx(3)cr1(gfp/gfp) mice. In aged mice, large numbers of SRMΦ/activated microglia replete with autofluorescent debris were noted in both old pigmented Cx(3)cr1(gfp/gfp) and Cx(3)cr1(gfp/+) mice proving this accumulation was not CX(3)CR1-dependent. While CX(3)CR1 deficiency leads to an early onset of SRMΦ accumulation, our data reveal that this change occurs in both aged Cx(3)cr1(gfp/+) and Cx(3)cr1(gfp/gfp) pigmented mice in the absence of marked retinal degeneration and is likely a normal response to aging.
authors.affiliation: Department of Anatomy and Developmental Biology, Monash University, Faculty of Medicine, Nursing and Health Sciences, Victoria, Australia.
authors.forename: Holly R
authors.initials: HR
authors.lastname: Chinnery
authors.forename: Samuel
authors.initials: S
authors.lastname: McLenachan
authors.forename: Timothy
authors.initials: T
authors.lastname: Humphries
authors.forename: Jelena M
authors.initials: JM
authors.lastname: Kezic
authors.forename: Xiangting
authors.initials: X
authors.lastname: Chen
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Ruitenberg
authors.forename: Paul G
authors.initials: PG
authors.lastname: McMenamin
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D000073883:CX3C Chemokine Receptor 1; D005260:Female; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D017628:Microglia; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D012168:Retinal Pigments / Q000378:metabolism*
chemical_list: D000073883:CX3C Chemokine Receptor 1; C471885:Cx3cr1 protein, mouse; D019707:Receptors, Chemokine; D012168:Retinal Pigments