NMDA-induced interleukin-1beta expression is mediated by nuclear factor-kappa B p65 in the retina

Transcription factors of the nuclear factor-kappa B (NF-kappaB) p65/RelA may be involved in neuronal cell death. We examined the involvement of NF-kappaB p65 in N-methyl-D-aspartate (NMDA)-induced upregulation of interleukin (IL)-1beta, a proinflammatory cytokine, and subsequent neurotoxicity in the rat retina. Immunohistochemistry showed that IL-1beta is localized not only in glial cells, but also in neurons, especially retinal ganglion cells (RGCs) after intravitreal injection of NMDA. Semi-quantitative real-time PCR showed that NMDA induces an increase in IL-1beta mRNA levels. Preinjection of NF-kappaB p65 antisense oligodeoxynucleotide (AS ODN) ameliorated the NMDA-induced increase in IL-1beta mRNA expression. Western blot analysis showed elevated levels of retinal IL-1beta protein 12 h after intravitreal NMDA injection and this elevation was significantly inhibited by NF-kappaB p65 AS ODN. Neurotracer labeling showed that the inhibition of NF-kappaB p65 by AS ODN or siRNA exerted a protective effect against NMDA-induced RGC loss. IL-1beta siRNA also had a protective effect on RGC number in NMDA-treated eyes. Penetration of AS ODN and siRNA to cells in the RGC layer and inner nuclear layer was confirmed after labeling with rhodamine or Cy3. These results suggest that NF-kappaB p65 may participate in the induction of IL-1beta expression in NMDA-induced retinal neuronal cell death and that the inhibition of NF-kappaB p65 and IL-1beta with the use of AS ODN or siRNA may be a viable neuroprotective strategy for RGC survival.