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An Optic Nerve Crush Injury Murine Model to Study Retinal Ganglion Cell Survival
Published on: April 25, 2011
Toll-like receptor-4 knockout mice are more resistant to optic nerve crush damage than wild-type mice
Dana Morzaev1,2, James D Nicholson1,2, Tomm Caspi2
1The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Petach Tikva, Israel.
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.
Conclusion:
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.
Insights
Reduced inflammation after optic nerve crush (ONC) injury in toll-like receptor-4 knockout mice improved retinal ganglion cell (RGC) survival. This suggests inflammation significantly impacts ONC injury outcomes.
Area of Science:
- Neuroscience
- Immunology
- Ophthalmology
Background:
- Optic nerve crush (ONC) injury triggers an inflammatory response.
- Toll-like receptor-4 (TLR4) is implicated in inflammatory pathways.
- Investigating TLR4's role in ONC-induced inflammation and retinal ganglion cell (RGC) loss is crucial.
Purpose of the Study:
- To compare the inflammatory response and RGC survival after ONC in TLR4 knockout (TLR4-/-) mice versus wild-type (WT) mice.
- To analyze the expression of key inflammatory and RGC markers post-injury.
Main Methods:
- ONC was performed on TLR4-/- and C57BL6 WT mice.
- Histological analysis of retina and optic nerve at 1, 3, and 21 days post-injury.
- Real-time quantitative PCR was used to assess expression of CD45, TNF-α, GFAP, THY-1, and Brn3b.
Main Results:
- TLR4-/- mice showed significantly less RGC loss (25.5%) compared to WT mice (38%).
- Higher expression of RGC markers (Thy-1, Brn3b) was observed in TLR4-/- mice.
- Both groups exhibited inflammatory cell infiltration; however, temporal expression patterns of TNF-α, CD45, and GFAP differed between TLR4-/- and WT mice.
Conclusions:
- Inflammation plays a critical role in the pathophysiology of ONC injury.
- Reduced inflammation, as seen in TLR4-/- mice, is associated with better RGC preservation.
- Alternative inflammatory pathways may contribute to RGC death following ONC.
