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Induction of macrophage migration inhibitory factor messenger ribonucleic acid in rat forebrain by reperfusion
T Yoshimoto1, J Nishihira, M Tada
1Department of Neurosurgery, Hokkaido University School of Medicine, Sapporo, Japan.
Objective:
Macrophage migration inhibitory factor (MIF) is a cytokine that has the potential to immobilize and activate monocytes/macrophages. To examine whether MIF may potentially be involved in the pathogenesis of reperfusion injury of the brain, we investigated the expression of MIF in a rat model of reperfusion.
Methods:
A four-vessel occlusion procedure was performed for 30 minutes using male Wistar rats to obtain a moderate reperfusion in the forebrains. Semiquantitatively calibrated reverse-transcription polymerase chain reaction analysis was conducted to examine temporal profiles of messenger ribonucleic acid (mRNA) expression for MIF and macrophage chemoattractant protein 1. MIF protein assays expression was assessed with specific Western blot analysis. For anatomic mapping of MIF, an immunohistochemical study was performed.
Results:
Reverse-transcription polymerase chain reaction demonstrated that the mRNA level of MIF increased depending on the duration of reperfusion (< or = 24 h) subsequent to global ischemia. The macrophage chemoattractant protein 1 mRNA was also observed to increase after reperfusional stress, but its maximum expression was reached earlier (1 h after the stress) than was MIF mRNA. Increase of MIF protein was also shown by Western blot. MIF-positive staining was observed in the neuronal processes (neuropil) in the cortex and basal growth ganglia of a rat forebrain.
Conclusion:
This protein is up-regulated and may modulate immunological reaction in secondary brain damage after ischemia and reperfusion stress.
Insights
Macrophage migration inhibitory factor (MIF) up-regulation in rats suggests its role in brain damage following ischemia and reperfusion. This cytokine may modulate the immune response during secondary brain injury.
Area of Science:
- Neuroscience
- Immunology
- Pathophysiology
Background:
- Macrophage migration inhibitory factor (MIF) is a cytokine involved in monocyte/macrophage immobilization and activation.
- The role of MIF in the pathogenesis of cerebral reperfusion injury remains to be fully elucidated.
Purpose of the Study:
- To investigate the expression of MIF in a rat model of cerebral reperfusion.
- To determine if MIF is involved in the secondary brain damage following ischemia and reperfusion stress.
Main Methods:
- A four-vessel occlusion rat model was used to induce moderate forebrain reperfusion.
- Reverse-transcription polymerase chain reaction (RT-PCR) analyzed messenger ribonucleic acid (mRNA) expression of MIF and macrophage chemoattractant protein 1 (MCP-1).
- Western blot and immunohistochemistry were employed to assess MIF protein levels and localization.
Main Results:
- MIF mRNA levels increased with reperfusion duration up to 24 hours post-ischemia.
- MCP-1 mRNA expression also increased, but peaked earlier than MIF mRNA.
- Western blot confirmed increased MIF protein levels, and immunohistochemistry showed MIF staining in neuronal processes within the cortex and basal ganglia.
Conclusions:
- MIF is upregulated in the brain following ischemia and reperfusion.
- The increased expression suggests MIF may play a role in modulating the immunological response contributing to secondary brain damage.