Local injection of the microRNA-146a recombinant lentiviral vector into the inner ear for immune-mediated inner ear disease in guinea pigs / 医学研究生学报

ABSTRACT

Objective Autoimmune inner ear disease is one of the inner ear diseases that can be effectively treated clinically, and researches on it have significant clinical and practical value.This study explored the immunoregulating and therapeutic effects of the mi-croRNA-146a recombinant lentiviral vector (RLV) on immune-medicated inner ear disease (IMIED) in guinea pigs so as to avoid the adverse reactions of the currently used immunodepressants. Methods IMIED models were established in 30 guinea pigs by immuni-zation with keyhole limpet hemocyanin and divided into three groups microRNA-146a RLV, empty lentiviral vector ( ELV) control, and surgery simulation control, microinjected via the scala tympani with microRNA-146a RLV, ELV, and PBS, respectively.Before and after immunization and at 7 days after microinjection, the auditory function and the level of specific anti-KLH antibodies in the ser-um were measured by auditory brainstem response ( ABR) audiometry and ELISA, respectively.Seven days after microinjection, 3 ani-mals in each group were subjected to HE staining and light microscopy, another 3 to fluoro-autography for realizing the situations of the inner ear transfected by the lentiviral vector, and the other 4 to measurement of the contents of microRNA-146a in the inner ear tissue. Results Compared with the baseline, immunization significantly increased the level of specific anti-KLH antibodies in the serum (0.09 ±0.01 vs 1.90 ±0.74 in the RLV group, 0.11 ±0.02 vs 2.20 ±0.75 in the ELV group, and 0.11 ±0.02 vs 2.10 ±0.64 in the surgery simulation control) as well as the average threshold of the ABRⅢwave (left ear 11.67 ±2.58 vs 61.67 ±5.16 and right ear 12.50 ±2.73 vs 60.00 ±4.47 in the RLV group;left ear 14.16 ±3.76 vs 64.33 ±9.17 and right ear 13.33 ±2.58 vs 60.83 ± 4.92 in the ELV group;left ear 15.83 ±3.76 vs 64.17 ±10.2 and right ear 15.00 ±5.47 vs 62.50 ±9.35 in the surgery simulation control) .The average threshold of the ABRⅢwave was decreased after local injection into the inner ear as compared with that after immunization, with no statistically significant difference between the ELV and surgery simulation control groups.Fluoro-autographic ob-servation showed that the main parts of the inner ear transfected with microRNA-146a recombinant lentiviruses were the spiral limbus, spiral ganglion afferent fibers, basal cells of the spiral ligament, Corti organ, and psalterial cords.The immune inflammatory reaction of the inner ear was significantly reduced in the RLV group as compared with the ELV and surgery simulation control groups, while the content of microRNA-146a in the inner ear tissue was obviously increased in the former group than in the latter two. Conclusion The microRNA-146a recombinant lentiviral vectors are widely distributed and transfected in the inner ear tissue after injected via the scala tympani.Injecting recombinant microRNA-146a lentiviral vectors into the inner ear can significantly reduce pathological damage and auditory dysfunction caused by inner ear immune inflammatory reaction.