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Expression of macrophage migration inhibitory factor in corneal wound healing in rats
A Matsuda1, Y Tagawa, H Matsuda
1Department of Ophthalmology, Hokkaido University School of Medicine, Sapporo, Japan.
Purpose:
The study was conducted to evaluate the expression of macrophage migration inhibitory factor (MIF) during penetrating corneal injury.
Method:
A penetrating linear incision (2 mm) was made in the center of the right cornea with a razor blade. The expression of MIF in the lacerated eye and in the contralateral eye was examined by immunohistochemistry at 3, 6, 24, 48, and 72 hours after injury. Concentrations of MIF in the aqueous humor of the injured and contralateral eyes were also measured by enzyme-linked immunosorbent assay. The expression of MIF messenger RNA (mRNA) in the injured cornea was quantified by reverse transcription-polymerase chain reaction and subsequent Southern blot analysis.
Results:
Positive migration inhibitory factor staining was observed in the basal cells of epithelial and endothelial cells of the normal rat cornea. The positive staining of the central corneal epithelium diminished at 3 hours after injury. At 6 hours after injury, positive MIF staining reappeared on the basal cells of the injured area, whereas the staining of the contralateral eye remained unchanged. Enzyme-linked immunosorbent assay of the aqueous humor revealed that the MIF concentration was elevated in both the injured and the contralateral eyes. The maximum concentration of aqueous MIF was observed at 6 hours after injury in both eyes. Reverse transcription-polymerase chain reaction and Southern blot analysis revealed that MIF-mRNA expression in the injured cornea increased from 6 to 48 hours after injury.
Conclusion:
The results of immunohistochemistry suggest the possibility that MIF is released from the corneal epithelial cells of the injured eye within 3 hours. Conversely, the MIF-mRNA level of the injured cornea is increased from 6 to 48 hours after injury and then diminished. In addition, unilateral corneal injury induces bilateral upregulation of MIF in the aqueous humor.
Insights
Macrophage migration inhibitory factor (MIF) is released from injured corneal cells and upregulated in both eyes after penetrating injury. MIF levels in aqueous humor and corneal mRNA expression increase following corneal damage.
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- Macrophage migration inhibitory factor (MIF) plays a crucial role in immune responses.
- Understanding MIF expression in ocular tissues is vital for comprehending corneal injury mechanisms.
Purpose of the Study:
- To investigate the expression patterns of MIF in the cornea following penetrating injury.
- To analyze MIF levels in the aqueous humor and corneal mRNA expression post-injury.
Main Methods:
- Penetrating corneal incision in rats.
- Immunohistochemistry to detect MIF expression in corneal tissues.
- Enzyme-linked immunosorbent assay (ELISA) for aqueous humor MIF concentration.
- RT-PCR and Southern blot for MIF mRNA quantification.
Main Results:
- MIF staining observed in normal corneal epithelial and endothelial cells.
- Diminished epithelial MIF staining at 3 hours post-injury, with reappearance at 6 hours.
- Elevated MIF concentration in aqueous humor of both injured and contralateral eyes, peaking at 6 hours.
- Increased MIF mRNA expression in the injured cornea from 6 to 48 hours post-injury.
Conclusions:
- MIF may be released from corneal epithelial cells within 3 hours of injury.
- Unilateral corneal injury leads to bilateral upregulation of MIF in the aqueous humor.
- Corneal MIF mRNA levels increase post-injury, suggesting a localized inflammatory response.