Microglial process convergence onto injured axonal swellings, a human postmortem brain tissue study

Area of Science:

• Neuroscience
• Neuropathology
• Traumatic Brain Injury Research

Background:

• Traumatic brain injury (TBI) impacts millions globally, often resulting in mild injuries with diffuse pathologies.
• Diffuse axonal injury (DAI) and microglial activation are key pathological hallmarks of TBI.
• Human neuroinflammation and microglia-injured axon interactions post-TBI remain less understood compared to animal models.

Purpose of the Study:

• To quantitatively measure microglial process convergence (MPC) in human postmortem brain tissue.
• To validate previous findings of MPC in micropigs in the context of human DAI.
• To investigate the occurrence of MPC on injured axonal swellings and intact myelinated fibers in human TBI cases.

Main Methods:

• Utilized multiplex immunofluorescent histochemistry on human postmortem brain tissue.
• Examined cases with confirmed diffuse axonal injury (DAI) and control brain tissue.
• Quantitatively assessed microglial process convergence (MPC) onto injured axonal swellings and intact fibers.

Main Results:

• Observed an increase in microglial process convergence (MPC) onto injured axonal swellings in human TBI cases.
• Findings are consistent with previous studies in micropigs, suggesting conserved biological mechanisms.
• MPC was investigated in relation to both DAI and intact myelinated fibers.

Conclusions:

• Microglial process convergence (MPC) is a measurable phenomenon in the human brain following traumatic brain injury (TBI).
• MPC on injured axons in humans validates prior findings in micropigs.
• MPC represents a clinically relevant pathological feature of TBI warranting further investigation.