Expression of the complement membrane attack complex and its inhibitors in Pick disease brain

Area of Science:

• Neuroscience
• Immunology
• Pathology

Background:

• Pick disease is a neurodegenerative disorder characterized by abnormal tau protein aggregation.
• The complement system, particularly the membrane attack complex (MAC), plays a role in neuroinflammation and neurodegeneration.
• Inhibitors of MAC, such as vitronectin, protectin, and clusterin, modulate complement activity.

Purpose of the Study:

• To investigate the presence and localization of the complement membrane attack complex (MAC) in Pick disease brains.
• To compare the distribution of MAC with its inhibitors: vitronectin, protectin, and clusterin.
• To explore the potential role of clusterin as a marker for neuronal degeneration in Pick disease.

Main Methods:

• Immunohistochemistry was used to detect MAC, vitronectin, protectin, and clusterin in brain tissue samples from patients with Pick disease.
• Specific antibodies were employed to visualize the target proteins within the brain parenchyma.

Main Results:

• Pick bodies showed intense staining for MAC and protectin, and weak staining for vitronectin.
• Clusterin staining was negative in Pick bodies but intensely stained some pyramidal neurons, including ballooned neurons, in affected cortical areas.
• These findings suggest a complement-mediated attack is involved in Pick body formation.

Conclusions:

• Complement-mediated attack is associated with the formation of Pick bodies in Pick disease.
• Clusterin's intense staining of degenerating neurons suggests it may serve as a marker for active neuronal degeneration in this condition.