核因子κB对大鼠视网膜血小板源性生长因子调控的研究

Modulation of expression of platelet-derived growth factor by nuclear transcription factor-κB in rats retina

目的探讨核因子κB（NF—κB）是否参与调控白细胞介素1β（IL-1β）诱导大鼠视网膜组织中血小板源性生长因子A（PDGF—A）、PDGF—B的表达。方法128只SD大鼠随机分成4组，右眼为实验眼，左眼为正常对照眼。间隔1h行两次玻璃体腔注射，先后两次注射情况分别为：A组BSS＋BSS，B组BSS＋IL-1β，C组吡咯烷二硫氨基甲酸盐（PDTC）＋BSS，D组PDTC＋IL-1β。其中，PDTC为NF—κB的特异性抑制剂。注射后4和24h分别通过裂隙灯显微镜检查对大鼠眼内炎性反应进行临床观察、评分，并用组织病理学、免疫组织化学方法及RT-PCR方法检测视网膜组织中NF-κB、PDGF—A、PDGF—B的表达及其变化情况。结果B组即注射IL-1β组，产生明显的眼内炎性反应，注射后4h左右达高峰，而D组即PDTC预处理组，炎性反应明显减轻；D组中炎性细胞的表达以及NF-κB的活化均明显低于B组，PDGF—A、PDGF-B蛋白及mRNA的表达也显著低于B组（P＜0．05）；B组及D组内PDGF—A的表达显著高于PDGF—B（P＜0．05）。结论NF—κB参与调控IL-1β诱导大鼠视网膜组织PDGF—A、PDGF—B的表达，PDGF—A、PDGF—B不同异构体在眼内炎性反应中表达不同。

Objective To determine whether nuclear transcription factor-κB （NF-κB） could modulate the expression of platelet-derived growth factor （PDGF） in rat retina induced by interleukin-1β （IL-1β） and studied the mechanism of inflammation-asseciated retinal diseases such as intraocular inflammation and proliferative vitreoretinopathy （PVR）. Methods 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-1β （group B） ; pyrrolidine dithiocarbamate （PDTC） and BSS （group C） ; PDTC and IL-1β （group D）. PDTC was one of special inhibitors of NF-κB 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 sacrifited 4 and 24 hours after the injection, the expressions of NF-κB and PDGF were detected by immunohistochemistry and reverse transcriptase polymerase chain reaction （RT-PCR）. Results 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-κB 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-κB decreased obviously. Conclusions These results suggest that NF-κB modulates the expression of PDGF in rat retina induced by IL-1β. 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.