The dual role of tumor necrosis factor-alpha in the pathophysiology of spinal cord injury

Recent studies have demonstrated that tumor necrosis factor-alpha (TNF-α) is one of the most important mediators in spinal cord injury (SCI). However, the role of TNF-α in this process is still under debate due to conflicting evidence. Here, we utilized TNF-α transgenic (tg) rats and wild-type (wt) littermates to further investigate the role of TNF-α in SCI. We observed that, in the acute phase post-SCI (≤3 days), TNF-α tg rats showed higher expression of TNF-α protein and more apoptotic cells in the spinal cord than wt rats, while in the chronic period (≥7 days), TNF-α tg rats exhibited persistent baseline level of TNF-α protein, better tissue healing, and more activated astrocytes in the border of the lesion than wt rats. These data further demonstrate that TNF-α plays a dual role in SCI and its role probably depends on when it is released after SCI and on which cellular population it acts on.