[Modulation of expression of platelet-derived growth factor by nuclear transcription factor-kappaB in rats retina]

To determine whether nuclear transcription factor-kappaB (NF-kappaB) could modulate the expression of platelet-derived growth factor (PDGF) in rat retina induced by interleukin-1beta (IL-1beta) and studied the mechanism of inflammation-associated retinal diseases such as intraocular inflammation and proliferative vitreoretinopathy (PVR).

One hundred and twenty eight Sprague-Dawley rats were divided into A, B, C and D groups, the right eyes were served as experimental eyes, and the left eyes as normal controls. Animals received 2 intravitreal injections at 1 hour interval, which included BSS and BSS (group A); BSS and IL-1beta (group B); pyrrolidine dithiocarbamate (PDTC) and BSS (group C); PDTC and IL-1beta (group D). PDTC was one of special inhibitors of NF-kappaB activation. The Rat eyes were examined by slit-lamp before intravitreal injection, 4 and 24 hours after the injection. Degree of intraocular inflammation was graded using a scoring system. Rats were sacrificed 4 and 24 hours after the injection, the expressions of NF-kappaB and PDGF were detected by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR).

Four hours after the injection, eyes in group B, as compared with group D, showed more severe intraocular inflammatory signs such as photophobia, iris hyperemia, miosis, large amount of fibrin exudates and posterior synechia of iris. Histopathologic examination showed numerous inflammatory cells within the retinal parenchyma, vitreous and ciliary body. Positive cells of NF-kappaB and PDGF in group D, which could be observed within inner nuclear layer and ganglion cell layer, were obviously less than that in group B. The expression of PDGF mRNA was less in group D compared with group B (P < 0.05), however the expression of PDGF-A mRNA was significantly higher than PDGF-B in group B and group D (P < 0.05). Twenty four hours after the injection, intraocular inflammation alleviated gradually, the expression of PDGF and NF-kappaB decreased obviously.

These results suggest that NF-kappaB modulates the expression of PDGF in rat retina induced by IL-1beta. Upregulation of PDGF may play an important role in the occurrence of intraocular inflammation and the different isoform of PDGF may have different impact on various ocular diseases.