title: Low-intensity far-red light inhibits early lesions that contribute to diabetic retinopathy: in vivo and in vitro.
abstract: OBJECTIVE
  Treatment with light in the far-red to near-infrared region of the spectrum (photobiomodulation [PBM]) has beneficial effects in tissue injury. We investigated the therapeutic efficacy of 670-nm PBM in rodent and cultured cell models of diabetic retinopathy.
  
  
  METHODS
  Studies were conducted in streptozotocin-induced diabetic rats and in cultured retinal cells. Diabetes-induced retinal abnormalities were assessed functionally, biochemically, and histologically in vivo and in vitro.
  
  
  RESULTS
  We observed beneficial effects of PBM on the neural and vascular elements of retina. Daily 670-nm PBM treatment (6 J/cm(2)) resulted in significant inhibition in the diabetes-induced death of retinal ganglion cells, as well as a 50% improvement of the ERG amplitude (photopic b wave responses) (both P < 0.01). To explore the mechanism for these beneficial effects, we examined physiologic and molecular changes related to cell survival, oxidative stress, and inflammation. PBM did not alter cytochrome oxidase activity in the retina or in cultured retinal cells. PBM inhibited diabetes-induced superoxide production and preserved MnSOD expression in vivo. Diabetes significantly increased both leukostasis and expression of ICAM-1, and PBM essentially prevented both of these abnormalities. In cultured retinal cells, 30-mM glucose exposure increased superoxide production, inflammatory biomarker expression, and cell death. PBM inhibited all of these abnormalities.
  
  
  CONCLUSIONS
  PBM ameliorated lesions of diabetic retinopathy in vivo and reduced oxidative stress and cell death in vitro. PBM has been documented to have minimal risk. PBM is noninvasive, inexpensive, and easy to administer. We conclude that PBM is a simple adjunct therapy to attenuate the development of diabetic retinopathy.
authors.affiliation: Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Johnny
authors.initials: J
authors.lastname: Tang
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Du
authors.forename: Chieh Allen
authors.initials: CA
authors.lastname: Lee
authors.forename: Ramaprasad
authors.initials: R
authors.lastname: Talahalli
authors.forename: Janis T
authors.initials: JT
authors.lastname: Eells
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Kern
mesh_terms: D000818:Animals; D002460:Cell Line; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D004195:Disease Models, Animal; D003576:Electron Transport Complex IV / Q000378:metabolism; D004596:Electroretinography; D006801:Humans; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D018921:Leukostasis / Q000473:pathology / Q000532:radiotherapy; D008027:Light; D008297:Male; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology / Q000528:radiation effects; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D010789:Phototherapy / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D011917:Rats, Inbred Lew; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects*; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects; D013481:Superoxides / Q000378:metabolism
chemical_list: D013481:Superoxides; D009569:Nitric Oxide; D003576:Electron Transport Complex IV
keywords: diabetic retinopathy; photobiomodulation; retinal ganglion cells
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