Expressions of complement factors C1q and C3 in retina with negative lens-defocused myopia in guinea pigs

Background High myopia is seriously harmful to visual function.To explore the mechanism of high myopia is significant for the prevention and treatment.Complement proteins C1q and C3 have emerged as critical mediators of synaptic refinement and plasticity, however, their effects in retina on myopia remain elusive. Objective This study was to investigate the expressions of complement factors C1q and C3 in the retina with negative lens-defocused myopia in guinea pigs. Methods The use and care of animals complied with the application of Peking Union Medical College Hospital Iaboratory Animal Welfare Ethics Committee.Twelve 3-day-old pigmented guinea pigs were assigned randomly to the lens-defocused group and the normal control group.The left eyes were covered by -10 D PMMA lens for 4 weeks as the defocused eye group, and the right eyes were covered using 0 D PMMA lens in the same way as the fellow control eye group.The right eyes of the normal guinea pigs were used as the normal control eye group.The refractive diopter of guinea pigs was examined by retinoscopy.The animals were sacrificed at the fourth week and the expressions of complement C1q and C3 in the retinas of guinea pigs were detected by Western blot. Results The diptors were (-1.21±0.71)D, (+ 2.46±0.75)D and (+ 1.75±0.50)D in the defocused eye group, normal eye group and the fellow eye group at the fourth week, showing a significant difference among the groups (F=51.55, P=0.69), and diopters were insignificantly different between the normal eye group and fellow eye group(q=2.62, P=0.08). However, the diopters of the defocused eye group were significantly higher than those of the fellow eye group (q=10.92, P<0.01). The expressions of C1q and C3 proteins in the retinas were significantly different among the defocused eye group, fellow eye group and normal eye group (C1q: F=8.810, P=0.003; C3: F=14.490, P<0.001), and expression levels of C1q and C3 proteins in the defocused eye group were significant higher than those of the fellow eye group (C1q: q=4.14, P=0.01; C3: q=4.71, P=0.005); while no significant differences were found between the fellow eye group and the normal eye group(C1q: q=1.61, P=0.27; C3: q=2.82, P=0.070). Conclusions The expression levels of C1q and C3 up-regulate in the retinas with lens-defocused myopic animal model.Excessive complement activation in retinas may be involved in the development of myopia. Key words: Complement system proteins; Retina; Myopia/physiopathology; Refraction, ocular; Guinea pigs, newborn; Disease model, animal; Defocus