Complement activation via alternative pathway is critical in the development of laser-induced choroidal...

Area of Science:

• Immunology
• Ophthalmology
• Complement System Biology

Background:

• Choroidal neovascularization (CNV) is a major cause of vision loss.
• The role of the complement system in CNV pathogenesis is not fully understood.
• Investigating complement pathways may reveal novel therapeutic targets for CNV.

Purpose of the Study:

• To elucidate the involvement of classical, lectin, and alternative complement pathways in laser-induced CNV.
• To determine if targeting specific complement pathways can inhibit CNV development.

Main Methods:

• Utilized a mouse model of laser-induced CNV.
• Employed small interfering RNAs (siRNA) to inhibit C1q (classical pathway) and factor B (alternative pathway).
• Studied C4(-/-) and C5(-/-) mice to assess complement pathway contributions.
• Quantified CNV development and measured levels of angiogenic factors and complement components.

Main Results:

• Inhibition of C1q or absence of C4 did not affect CNV development.
• CNV was significantly inhibited in C5(-/-) mice and mice treated with factor B siRNA.
• Factor B siRNA treatment reduced membrane attack complex and key angiogenic factors (VEGF, TGF-beta2).
• Factor B levels increased post-laser injury, while factor H levels decreased.

Conclusions:

• Activation of the factor B-dependent alternative complement pathway is essential for CNV development.
• The classical and lectin pathways do not play a significant role in this CNV model.
• Targeting the alternative pathway, specifically factor B, represents a promising therapeutic strategy for inhibiting CNV.