[Expression of CD11b in the retinal microglia in chronic hypertension rat].

Objective: To study the expression of CD11b in the retinal microglia in laser induced ocular hypertension (OHT) SD rat.

Methods: It was an experimental study. OHT was induced by the coagulation of trabecular meshwork using 532-laser in sixty SD rats. Intraocular pressure (IOP) was measured by Tonopen-XL, the expression of CD11b in retinal microglia detected by immunohistochemistry, and retinal ganglion cells (RGCs) were labeled with Dextran Tetramethyl Rhodamine (DTR) and counted by Image-Pro Plus Version 6.0 image analysis software at 2 weeks, 1, 2, 3, 4, 5, and 6 months, respectively. All the numerical data were statistically analyzed by SPSS 13.0 software.

Results: Although the IOP of experimental groups are still the similar level at 2w after coagulation (t = 1.124, P = 0.287), Compared to control eyes, IOP in lasered eyes was significantly (t = 2.487, P = 0.036) increased at 1 month, lasting for 3 months and returned to normal from 5 to 6 months (t = 1.103, P = 0.290). The expression of CD11b in the retinal microglia in the lasered eyes was significantly more intensive than that in control eyes at 1 month (t = 3.333, P = 0.008) and faded after 5 months, a similar pattern to IOP response, that two group data shows significant dependability (r = 0.891, P = 0.014). The number of RGC was significantly reduced from 1 month to 6 months (t = 3.316, P = 0.009), the velocity of reducing seems dependability to the advancing of IOP (r = 0.757, P = 0.021).

Conclusions: The expression of CD11b in retinal microglia is fluctuated with chronic OHT pattern and RGCs injury level indicating that the injury antigens by microglia are presented in the retina with the increase of IOP and activate the immunologic process leading to glaucomatous RGCs damage. It suggests that it is important to effectively control the IOP in order to reduce the risk of immune induced retinal damage by microglia.