TNF-alpha-induced optic nerve degeneration and nuclear factor-kappaB p65

Area of Science:

• Neuroscience
• Ophthalmology
• Immunology

Background:

• Optic nerve axonal degeneration is a significant cause of vision loss.
• Tumor necrosis factor-alpha (TNF-alpha) is implicated in various inflammatory and degenerative conditions.
• The role of specific molecular pathways, such as nuclear factor-kappaB p65 (NF-kappaB p65), in TNF-alpha-induced optic neuropathy requires further elucidation.

Purpose of the Study:

• To establish a rat model of optic nerve axonal degeneration induced by TNF-alpha.
• To investigate the involvement of NF-kappaB p65 in the pathogenesis of this degeneration.

Main Methods:

• Rats received intravitreal injections of TNF-alpha, followed by morphometric and histological analyses at various time points.
• Axonal integrity, retinal ganglion cell counts, and myelin basic protein expression were assessed.
• NF-kappaB p65 levels and localization were determined using Western blot and immunohistochemistry.
• The therapeutic potential of inhibiting NF-kappaB p65 activation was evaluated using antisense oligodeoxynucleotide (AS ODN) and helenalin.

Main Results:

• TNF-alpha injection led to significant axonal loss and degeneration from 2 weeks to 2 months post-injection.
• Retinal ganglion cell loss was observed at a later stage (2 months).
• NF-kappaB p65 expression increased in the optic nerve, co-localizing with microglial markers.
• Inhibition of NF-kappaB p65 significantly protected against TNF-alpha-induced axonal damage.

Conclusions:

• TNF-alpha is a potent inducer of optic nerve axonal degeneration, potentially leading to delayed retinal ganglion cell loss.
• NF-kappaB p65 plays a critical role in mediating TNF-alpha-induced axonal degeneration, possibly involving microglial activation.