Complement factors C1q, C3 and C5b-9 in the posterior sclera of guinea pigs with negative lens-defocused myopia

· AIM: To investigate the expression of complement factors in the posterior scleral fibroblasts of guinea pigs with negative lens-defocused myopia.· METHODS: Eighteen guinea pigs were assigned randomly to two groups: the negative lens-defocused group(NLD group, n =9) and the normal control without treatment group(NC group, n =9). The effect of myopic induction was compared in three subgroups: eyes treated with a-10.00 D negative lens in the NLD group(NL group), eyes treated with a plano(0 D) lens in the NLD group(PL group), and untreated right eyes in the NC group(NC group). The following analyses were conducted at four weeks: examination of the refractive error via retinoscopy, assessment of complement C5b-9expression in the posterior scleral fibroblasts using immunohistochemistry, and measurements of complement C1 q and C3 protein levels in the posterior sclera by Western blot.·RESULTS: After an induction period of four weeks, a significant myopic shift was detected in the eyes of the NL group, relative to that of the PL and NC groups(P 【0.05). Data analysis showed a significant increase in the percentage of C5b-9 immunopositive fibroblasts in the posterior sclera of the NL group eyes, compared to the PL group(q =11.50, P 【0.001). Significantly higher levels of C1q(q =4.94, P =0.01) and C3(q =4.07, P =0.03)protein were detected in the posterior sclera of NL group eyes, compared to the PL group. There were no significant difference between the PL and NC groups for C5b-9(q =2.44, P =0.10), C1q(q =1.55, P =0.53) and C3(q =0.98, P =0.77) in the posterior sclera.·CONCLUSION: The data from present study provide evidence of the up-regulation of C5b-9, C1 q and C3 in the posterior scleral fibroblasts in a NLD myopic animal model. The results suggest that the complement system may be involved in the development of myopia.