Effect of Selective Retina Therapy (SRT) on the Inflammatory Microenvironment of the Subretinal Space

Abstract

To investigate the effect of Selective Retina Therapy (SRT) on inflammatory key factors such as complement factor-C3 (CC3), tumor growth factor-beta2 (TGF-β2), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). Porcine RPE-Bruch's membrane-choroid explants were irradiated with two SRT laser systems, SRTYLF and SRTYAG (Nd : YLF laser, wave length 527 nm, pulse duration 1.7 µs and Nd : YAG laser, wave length 532 nm, pulse duration 2.4 - 3 µs). Laser irradiation was performed on a spot size of 200 × 200 µm, 30 pulses, with a repetition rate of 100 Hz, and a radiant exposure of 140 (threshold RPE death) and 180 mJ/cm2 per pulse (above threshold RPE death). Explants were cultivated in modified Ussing chambers and culture viability was assessed by calcein-AM cell staining. Secretion of inflammatory factors was analyzed by ELISA. Protein expression of tissue explants was assessed by Western blot. Regeneration of RPE was observed after 4 days. One day after SRT with 140 mJ/cm2 per pulse the secretion of basal CC3 decreased in ELISA. Following 180 mJ/cm2 radiant exposure, the level of IFN-γ decreased at day 4. SRT does not induce the release of the pro-inflammatory factors analyzed in this in-vitro study.