title: Chemokine-mediated inflammation in the degenerating retina is coordinated by Müller cells, activated microglia, and retinal pigment epithelium.
abstract: BACKGROUND
  Monocyte infiltration is involved in the pathogenesis of many retinal degenerative conditions. This process traditionally depends on local expression of chemokines, though the roles of many of these in the degenerating retina are unclear. Here, we investigate expression and in situ localization of the broad chemokine response in a light-induced model of retinal degeneration.
  
  
  METHODS
  Sprague-Dawley (SD) rats were exposed to 1,000 lux light damage (LD) for up to 24 hrs. At time points during (1 to 24 hrs) and following (3 and 7 days) exposure, animals were euthanized and retinas processed. Microarray analysis assessed differential expression of chemokines. Some genes were further investigated using polymerase chain reaction (PCR) and in situ hybridization and contrasted with photoreceptor apoptosis using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Recruitment of retinal CD45 (+) leukocytes was determined via fluorescence activated cell sorting (FACS), and expression of chemokine receptors determined using PCR.
  
  
  RESULTS
  Exposure to 24 hrs of LD resulted in differential expression of chemokines including Ccl3, Ccl4, Ccl7, Cxcl1, and Cxcl10. Their upregulation correlated strongly with peak photoreceptor death, at 24 hrs exposure. In situ hybridization revealed that the modulated chemokines were expressed by a combination of Müller cells, activated microglia, and retinal pigment epithelium (RPE). This preceded large increases in the number of CD45(+) cells at 3- and 7-days post exposure, which expressed a corresponding repertoire of chemokine receptors.
  
  
  CONCLUSIONS
  Our data indicate that retinal degeneration induces upregulation of a broad chemokine response whose expression is coordinated by Müller cells, microglia, and RPE. The findings inform our understanding of the processes govern the trafficking of leukocytes, which are contributors in the pathology of retinal degenerations.
authors.affiliation: John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia. matt.rutar@anu.edu.au.|ANU Medical School, The Australian National University, 54 Mills Road, Canberra, ACT 2601, Australia. matt.rutar@anu.edu.au.
authors.forename: Matt
authors.initials: M
authors.lastname: Rutar
authors.affiliation: John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia. riccardo.natoli@anu.edu.au.|ANU Medical School, The Australian National University, 54 Mills Road, Canberra, ACT 2601, Australia. riccardo.natoli@anu.edu.au.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Natoli
authors.affiliation: John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia. u4957724@anu.edu.au.
authors.forename: R X
authors.initials: RX
authors.lastname: Chia
authors.affiliation: John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia. jan.provis@anu.edu.au.|ANU Medical School, The Australian National University, 54 Mills Road, Canberra, ACT 2601, Australia. jan.provis@anu.edu.au.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Valter
authors.affiliation: John Curtin School of Medical Research, The Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia. krisztina.valter-kocsi@anu.edu.au.|ANU Medical School, The Australian National University, 54 Mills Road, Canberra, ACT 2601, Australia. krisztina.valter-kocsi@anu.edu.au.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Provis
mesh_terms: D000818:Animals; D016923:Cell Death; D018925:Chemokines / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D063928:Ependymoglial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000528:radiation effects; D007249:Inflammation / Q000209:etiology*; D008027:Light / Q000009:adverse effects; D046228:Microarray Analysis; D017628:Microglia / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000473:pathology; D012162:Retinal Degeneration / Q000150:complications* / Q000209:etiology / Q000473:pathology*; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D018925:Chemokines; D012333:RNA, Messenger