Ponsioen Theodorus Leonardus, van Luyn Marja Johanna Adriana, van der Worp Roelofje Jacoba, Nolte Ilja Maria, Hooymans Johanna Martina Maria, Los Leonoor Inge
Department of Ophthalmology, University of Groningen, University Medical Center Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands.
Graefes Arch Clin Exp Ophthalmol. 2007 Jan;245(1):82-92. doi: 10.1007/s00417-006-0314-6. Epub 2006 Apr 6.
This study is a first step to investigate phagocytosis of collagens by human retinal Müller cells, since Müller cells could be involved in remodelling of the vitreous and vitreoretinal interface in the human eye.
Müller cells in culture were exposed to 2.0 microm fluorescent latex beads coated with BSA and human types I, II, and IV collagen and to non-coated beads for 2, 12, 24, and 48 h. To influence phagocytosis, cytochalasin B and anti-integrin subunits (alpha1, alpha2, and beta1) were added to the cells. Phagocytosis was evaluated by flow cytometry, transmission electron microscopy (TEM) and confocal microscopy.
Müller cells preferred to phagocytose beads coated with type II collagen compared with type IV collagen-, BSA- and non-coated beads. Phagocytosis of type I collagen-coated beads was intermediate. TEM and confocal microscopic evaluation confirmed phagocytosis of the beads. No significant differences were observed in phagocytosis of type II collagen-coated beads in the case of addition of cytochalasin B and anti-integrin subunits. Immunohistochemical analyses revealed that Müller cells were positive, under all tested circumstances, for vimentin and CRALBP. Less than 5% of the cells tested were GFAP positive.
Our observations demonstrate that human Müller cells in culture prefer to phagocytose type II collagen. In contrast, the phagocytosis of type IV collagen is comparable with the control coatings. We speculate that the relatively limited collagen phagocytosis by Müller cells supports a possible role for Müller cells in the slow process of vitreoretinal remodelling in adult human eyes.
本研究是调查人视网膜Müller细胞对胶原蛋白吞噬作用的第一步，因为Müller细胞可能参与人眼玻璃体和玻璃体视网膜界面的重塑。
将培养的Müller细胞暴露于包被有牛血清白蛋白（BSA）、人I型、II型和IV型胶原蛋白的2.0微米荧光乳胶珠以及未包被的珠子中，作用2、12、24和48小时。为影响吞噬作用，向细胞中加入细胞松弛素B和抗整合素亚基（α1、α2和β1）。通过流式细胞术、透射电子显微镜（TEM）和共聚焦显微镜评估吞噬作用。
与IV型胶原蛋白包被的珠子、BSA包被的珠子和未包被的珠子相比，Müller细胞更倾向于吞噬II型胶原蛋白包被的珠子。I型胶原蛋白包被的珠子的吞噬作用处于中间水平。TEM和共聚焦显微镜评估证实了珠子的吞噬作用。在加入细胞松弛素B和抗整合素亚基的情况下，II型胶原蛋白包被的珠子的吞噬作用未观察到显著差异。免疫组织化学分析显示，在所有测试情况下，Müller细胞波形蛋白和CRALBP呈阳性。测试的细胞中不到5%的GFAP呈阳性。
我们的观察结果表明，培养的人Müller细胞更倾向于吞噬II型胶原蛋白。相比之下，IV型胶原蛋白的吞噬作用与对照包被相当。我们推测，Müller细胞相对有限的胶原蛋白吞噬作用支持其在成人眼玻璃体视网膜重塑缓慢过程中可能发挥的作用。
