Heme oxygenase-1 induced in muller cells plays a protective role in retinal ischemia-reperfusion injury in rats

Invest Ophthalmol Vis Sci. 2004 Nov;45(11):4226-32. doi: 10.1167/iovs.04-0450.


Purpose: To investigate the protective roles played by heme oxygenase (HO)-1 and -2 in the rat retina after ischemia-reperfusion injury.

Methods: Retinal ischemia was induced in rats by increasing the intraocular pressure to 110 mmHg for 60 minutes. The expression of HO-1 and -2 in the retina was determined by Western blot, real-time polymerase chain reaction (PCR), and immunohistochemistry. To inhibit the upregulation of HO-1, short interfering (si)RNA of HO-1 was injected intravitreally before ischemia and that of green fluorescent protein (GFP) was used as the control. Muller cell damage was assessed by counting the number of S-100-positive cells. The number of macrophages invading the retina was determined by counting the number of ED-1-positive cells.

Results: The expression of HO-1 mRNA and protein was upregulated at 6 hours after reperfusion and peaked at 12 to 24 hours, whereas that of HO-2 was not altered. HO-1 immunoreactivities were detected in Muller cells at 24 hours after reperfusion, and HO-2 immunoreactivities were detected in retinal cells. The HO-1 expression in the retina treated with siRNA of HO-1 was reduced at 12 and 24 hours after reperfusion compared with that injected with siRNA of GFP. The number of S-100-positive cells at 24 hours after reperfusion decreased significantly in retinas treated with HO-1 siRNA (P <0.01). The number of macrophages that had infiltrated the retina was increased in retinas pretreated with the siRNA of HO-1 compared with those treated with siRNA of GFP. On day 14 after reperfusion, HO-1 siRNA-treated retinas showed severe retinal injury and destruction of the retinal architecture.

Conclusions: HO-1 promotes the survival of Muller cells after ischemia-reperfusion injury. Because inhibition of the upregulation of HO-1 resulted in an infiltration of inflammatory cells and destruction of the retina, the authors conclude that HO-1 induced in Muller cells plays a protective role in retinal ischemia-reperfusion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cell Survival
  • Ectodysplasins
  • Heme Oxygenase (Decyclizing) / physiology*
  • Heme Oxygenase-1
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Male
  • Membrane Proteins / metabolism
  • Neuroglia / enzymology*
  • Polymerase Chain Reaction
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Reperfusion Injury / enzymology
  • Reperfusion Injury / prevention & control*
  • Retinal Diseases / enzymology
  • Retinal Diseases / prevention & control*
  • S100 Proteins / metabolism
  • Up-Regulation


  • Ectodysplasins
  • Membrane Proteins
  • RNA, Messenger
  • RNA, Small Interfering
  • S100 Proteins
  • Heme Oxygenase (Decyclizing)
  • Heme Oxygenase-1
  • heme oxygenase-2