HDAC8 Inhibition Reduces Lesional Iba-1+ Cell Infiltration after Spinal Cord Injury without Effects on Functional...

Area of Science:

• Neuroscience
• Immunology
• Pharmacology

Background:

• Pan-histone deacetylase (HDAC) inhibition via valproic acid (VPA) shows promise for spinal cord injury (SCI) recovery, but presents side effects.
• HDAC8 specifically modulates macrophage (Mφ) inflammatory responses, making it a potential therapeutic target for SCI.

Purpose of the Study:

• To investigate if specific HDAC8 inhibition improves functional recovery after SCI by reducing pro-inflammatory Mφ.
• To compare the effects of HDAC8 inhibition with pan-HDAC inhibition (VPA) in different SCI models.

Main Methods:

• Utilized PCI-34051 for specific HDAC8 inhibition in a T-cut hemisection SCI model.
• Assessed Mφ infiltration via histological analysis and functional recovery using the Basso Mouse Scale.
• Attempted to replicate VPA's effects in a contusion SCI model.

Main Results:

• Specific HDAC8 inhibition reduced perilesional Mφ numbers but failed to improve functional recovery.
• Valproic acid (VPA) did not yield the previously reported functional recovery improvements in this hemisection SCI model.
• Discrepancies in outcomes may be attributed to the presence of spared fibers in different SCI models.

Conclusions:

• Targeted HDAC8 inhibition alone is insufficient to promote functional recovery post-SCI, despite reducing inflammation.
• The efficacy of HDAC inhibitors in SCI may be model-dependent, influenced by factors like spared white matter tracts.
• Further research is needed to elucidate the complex role of HDACs in SCI pathophysiology and therapeutic strategies.