Strand Berit L, Ryan Liv, Veld Peter In't, Kulseng Bård, Rokstad Anne Mari, Skjåk-Bræk Gudmund, Espevik Terje
Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway.
Department of Cancer Research and Molecular Biology, Norwegian University of Science and Technology, Trondheim, Norway.
Cell Transplant. 2001 Apr;10(3):263-275. doi: 10.3727/000000001783986800.
Alginate - poly-l-lysine (PLL) microcapsules can be used for transplantation of insulin-producing cells for treatment of type I diabetes. In this work we wanted to study the inflammatory reactions against implanted microcapsules due to PLL. We have seen that by reducing the PLL layer, less overgrowth of the capsule is obtained. By incubating different cell types with PLL and afterwards measuring cell viability with MTT, we found massive cell death at concentrations of PLL higher than 10 μg/ml. Staining with annexin V and propidium iodide showed that PLL induced necrosis but not apoptosis. The proinflammatory cytokine, tumor necrosis factor (TNF), was detected in supernatants from monocytes stimulated with PLL. The TNF response was partly inhibited with antibodies against CD14, which is a well-known receptor for lipopolysaccharide (LPS). Bactericidal permeability increasing protein (BPI) and a lipid A analogue (B-975), which both inhibit LPS, did not inhibit PLL from stimulating monocytes to TNF production. This indicates that PLL and LPS bind to different sites on monocytes, but because they both are inhibited by a p38 MAP kinase inhibitor, they seem to have a common element in the signal transducing pathway. These results suggest that PLL may provoke inflammatory responses either directly or indirectly through its necrosis-inducing abilities. By combining soluble PLL and alginate both the toxic and TNF-inducing effects of PLL were reduced. The implications of these data are to use alginate microcapsules with low amounts of PLL for transplantation purposes.
海藻酸盐-聚-L-赖氨酸（PLL）微胶囊可用于移植产生胰岛素的细胞以治疗I型糖尿病。在这项工作中，我们想要研究由于PLL导致的针对植入微胶囊的炎症反应。我们已经发现，通过减少PLL层，可以减少胶囊的过度生长。通过用PLL孵育不同的细胞类型，然后用MTT测量细胞活力，我们发现在PLL浓度高于10μg/ml时会出现大量细胞死亡。用膜联蛋白V和碘化丙啶染色表明，PLL诱导坏死而非凋亡。在用PLL刺激的单核细胞的上清液中检测到促炎细胞因子肿瘤坏死因子（TNF）。用抗CD14抗体部分抑制了TNF反应，CD14是脂多糖（LPS）的一种众所周知的受体。杀菌通透性增加蛋白（BPI）和一种脂质A类似物（B-975）都抑制LPS，但它们都不能抑制PLL刺激单核细胞产生TNF。这表明PLL和LPS结合到单核细胞上的不同位点，但由于它们都被p38丝裂原活化蛋白激酶抑制剂抑制，它们似乎在信号转导途径中有一个共同的元件。这些结果表明，PLL可能通过其诱导坏死的能力直接或间接引发炎症反应。通过将可溶性PLL与海藻酸盐结合，PLL的毒性和TNF诱导作用都降低了。这些数据的意义在于使用含有少量PLL的海藻酸盐微胶囊用于移植目的。
