Red/NIR LED Therapy for LPS-Induced AOM

In this study, the continuous-wave dual red and NIR LED irradiation system (HK HEALTHCARE CO., LTD., Korea) with wavelengths of 655 nm and 842 nm consisted of a control module and a battery and was connected to an LED light source with a power cable (Supplementary Figure S1). The LED light source unit was composed of an LED light source and an optical fiber. The power intensity of the LED light was 102 W/m². To examine the therapeutic effect of the red/NIR LED on LPS-induced AOM, rats were irradiated with the red/NIR LED through the ear canal for 30 min for 3 days after LPS injection. Optical fiber (diameter = 3 mm) was tightly placed in the external auditory canal cartilaginous portion. The direction of the optical fiber was monitored to always face the tympanic membrane during the irradiation. Since the optical fiber itself might cause otitis externa, the same optical fiber was place into the external auditory canal (under same anesthesia) without turning on the LED light for the control LPS group. The red/NIR LED system for cell experiments consisted of a power connector and a power supply unit, and the upper LED light source was composed of six LEDs. HMEECs and RAW 264.7 cells were irradiated with red and NIR wavelengths of 653 nm and 842 nm, respectively, and an intensity of 49.4 mW/m² for 3 h after LPS stimulation.