The Role of Bevacizumab in the Growth of Fibroblasts and Modulation of Fibrosis Post Filtering Surgery

Abstract

Purpose: : To explore the influence of Bevacizumab (anti-VEGFA, Avastin) on the cell growth and the RNA expressions of inflammatory cytokines, VEGF, VEGFR of rat conjunctival fibroblasts; and to explore its influence on the morphology of filtering bleb, and on the expressions of inflammatory factors and angiogenic factors.

Methods: : Rats' conjunctiva fibroblasts were cultured and identified using indirect IFA method. VEGF₁₆₄, Flt-1, Flk1, TGFβ1, TGFβ2 were identified using RT-PCR. Different concentrations of Bevacizumab were added for observation the effect to the cell growth, using MTT. RNA expressions of above five cytokines were observed under 2.5mg/ml Bevacizumab intervention, using Realtime PCR. Filtering surgery model was made and standardized from S-D rats. Morphological changes with time was observed both in Bevacizumab subconjunctival injection group and control groups. RNA expression changes of the five cytokines were observed at different time points, using Realtime PCR. Total protein of each cytokine was simultaneously extracted and analyzed during RNA extraction process, using WB method.

Results: : Cultured fibroblasts were Vimentin-FITC stained positive and Keratin-FITC stained negative. Sequencing results of RT-PCR products were consistent with mRNA sequence of the five cytokines respectively. Fibroblasts died within 24hrs under intervention of 12.5mg/ml Bevacizumab, and cell growth was suppressed under 2.5mg/ml Bevacizumab. The mRNA expressions of VEGF₁₆₄ and TGFβ2 were more suppressed compared to other cytokines, under 2.5mg/ml Bevacizumab. No flattened bleb and more functional blebs were observed in Bevacizumab subconjunctival injection group, compared to control groups (K-W H test, P=0.032). Less cases of hyphema (P=0.002) and less cases of iris reaction (P=0.000) were observed in Bevacizumab group. The expressions of five genes decreased in Bevacizumab group, among which expressions of VEGF₁₆₄ and TGFβ2 were continuously lower at each observing time points, compared to those in control groups respectively (P<0.05). Expression of TGFβ2 was most enriched and the variation was most remarkable among all five genes. Proteins of VEGFA, TGFβ1 and TGFβ2 from Bevacizumab group were all weaker at most observing times.

Conclusions: : Bevacizumab could suppress the growth of fibroblasts and remarkably inhibit expressions of angiogenic factor and inflammatory factors both in fibroblasts and in filtering bleb, and consequently maintain the function of filtering bleb. The mechanism of inhibitory effect on fibrosis may be both through angiogenic pathway and non-angiogenic pathway.

Keywords: proliferation • vascular endothelial growth factor • wound healing