Toll-like receptor-4 knockout mice are more resistant to optic nerve crush damage than wild-type mice.
BACKGROUND
This study aims to investigate the role of the inflammatory response following optic nerve crush (ONC) in knockout mice for the toll-like receptor-4 gene (TLR4-/-) compared to wild-type (WT) mice.


METHODS
ONC was induced in TLR4-/- and C57BL6 WT mice. Histological sections of the retina and optic nerve were analysed on days 1, 3 or 21 after injury. Molecular analysis with real-time quantitative polymerase chain reaction was used to study the expression of CD45, tumour necrosis-alpha (TNF-α) and glial fibrillary acidic protein, as well as retinal ganglion cell (RGC) markers THY-1 and Brn3b.


RESULTS
There was a 25.5% and 38% loss in the RGC layer of the ONC-injured eyes of the TLR4-/- and the WT mice, respectively (with 27% and 9% of the remaining cells positive for Brn3a, respectively). Mean levels of Thy-1 and Brn3b were higher in the TLR4-/- mice. CD45 and Iba1 staining revealed infiltration of inflammatory cells into the injured nerve and retina in both groups. Molecular analysis of the optic nerve on day 1 showed increased TNF-α expression and reduced CD45 and GFAP expression; on day 3, CD45 reverted to baseline but GFAP remained low; on day 21, all 3 markers were at baseline in the TLR4-/- group and decreased in the WT group.


CONCLUSIONS
Inflammation plays a major role in the response to ONC injury. Reduced levels of inflammation are associated with improved RGC preservation. The increase in TNF-α and reduction in CD45 in both TLR4-/- and WT mice may indicate the presence of an alternative pathway for induction of RGC death.
The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.|Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Dana
D
Morzaev
The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.|Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
James D
JD
Nicholson
Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Tomm
T
Caspi
The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.|Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Shirel
S
Weiss
Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.|Laboratory of Cardiac Research, Felsenstein Medical Research Center, Petach Tikva, Israel.
Edith
E
Hochhauser
The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.|Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.|Department of Ophthalmology, Pediatric Unit, Schneider Children's Medical Center of Israel, Petach Tikva, Israel.
Nitza
N
Goldenberg-Cohen
D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D005904:Glial Fibrillary Acidic Protein; D018398:Homeodomain Proteins / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009409:Nerve Crush; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D020221:Optic Nerve Injuries / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology; D018800:Thy-1 Antigens / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D050820:Transcription Factor Brn-3B / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; C085559:Pou4f2 protein, mouse; D012333:RNA, Messenger; D018800:Thy-1 Antigens; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D050820:Transcription Factor Brn-3B; D014409:Tumor Necrosis Factor-alpha; C528900:glial fibrillary astrocytic protein, mouse; D017493:Leukocyte Common Antigens; C516770:Ptprc protein, mouse
TLR-4 knockout mouse; ischemic retina; neuroprotection; optic nerve crush model