- 作者：Zhonglin Liu ; Leonie wyffels ; Christy Barber ; Li Wan ; Hua Xu ; Mizhou M. Hui ; Lars R. Furenlid ; James M. Woolfenden
- 关键词：99mTc ; Cytokines ; Interleukin-1 ; Tumor necrosis factor ; Inflammation ; Imaging
- 刊名：Nuclear Medicine and Biology
- 出版年：2012
- 出版时间：October, 2012
- 年：2012
- 卷：39
- 期：7
- 页码：905-915
- 全文大小：1152 K
Introduction
TNFR2-Fc and IL-1ra-Fc are recombinant cytokine ligands that target TNF and IL-1. TNFR2-Fc-IL-1ra, a dual-domain agent that incorporates both ligands, allows bifunctional binding of IL-1 receptors and TNF. This study was designed to characterize 99mTc-labeled forms of these ligands, 99mTc-IL-1ra-Fc (IF), 99mTc-TNFR2-Fc (TF), and 99mTc-TNFR2-Fc-IL-1ra (TFI), for inflammation imaging.Methods
The cytokine ligands were labeled with 99mTc by a direct approach via 2-iminothiolane (2-IT) reduction at various 2-IT/protein molar ratios. In vivo inflammation targeting studies were carried out in a mouse ear edema model created by topical application of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on the right ear of ICR mice.
Results
Radiolabeling yields increased with increasing amounts of 2-IT. When the 2-IT/protein ratio reached 1000, the radiolabeling yield was greater than 90 % without significant colloid production. TPA-treated ears showed high radioligand uptake, which was clearly detected by SPECT and autoradiographic imaging. The activities ( % ID/g) in the inflamed and control ears at 3 h after injection were 2.76 ¡À 0.20 vs. 0.69 ¡À 0.12 for IF, 5.86 ¡À 0.40 vs. 2.86 ¡À 0.61 for TF, and 7.61 ¡À 0.86 vs. 1.99 ¡À 0.31 for TFI (P < 0.05 vs. controls). TFI showed significantly higher uptake in the inflamed ears compared to TF and IF (P < 0.05). Blocking study results indicated specificity of radioligand binding with decreased radioactive uptake in the inflamed ears. Western blotting and ELISA analysis further confirmed a high expression of IL-1¦Â and TNF-¦Á in the inflamed ears.
Conclusions
99mTc-labeled cytokine ligands are a promising approach for detecting and understanding the inflammatory process. TFI may be more useful than the single-domain ligands for noninvasive detection of inflammatory sites.