CD55 expression patterns on intestinal neuronal tissue are divergent from the brain.

Area of Science:

• Neuroscience
• Immunology
• Gastroenterology

Background:

• Enteric plexuses are susceptible to complement-mediated attack.
• Investigating membrane-bound complement regulatory proteins (mCRPs) in enteric plexuses is crucial for understanding their defense mechanisms.
• Comparison of mCRP expression in enteric plexuses versus the central nervous system (CNS) provides insights into differential protection strategies.

Purpose of the Study:

• To determine the expression patterns of mCRPs (CD46, CD55, CD59) in enteric plexuses.
• To investigate the association of mCRP expression with C3 deposition.
• To compare mCRP expression in enteric plexuses with that in the CNS.

Main Methods:

• Immunohistochemistry was used to identify neuronal and glial cells and detect CD46, CD55, CD59, and C3d.
• RNA in situ hybridization (RISH) identified cells expressing CD55 mRNA.
• Phospholipase C treatment assessed CD55 attachment to elastic fibers.

Main Results:

• Enteric plexuses showed high expression of CD55 and CD59, with minimal CD46.
• Enteric neurons expressed CD55, while enteric glial cells did not; CD55 was also found on elastic fibers surrounding Auerbach's plexuses.
• C3d deposition occurred around plexuses, but not within plexus cells, suggesting a protective mechanism.

Conclusions:

• Enteric neurons express CD55, unlike CNS neurons, and enteric glial cells lack CD55 expression.
• CD55, produced by enteric neurons and attached to surrounding elastic fibers, likely protects CD55-negative glial cells from complement-mediated injury.
• This mechanism highlights a unique protective strategy of the enteric nervous system against complement attack.