Abstract
Purpose :
Approved effective therapy is still lacking in acute glaucoma. PANoptosis, which is consist of three key modes of programmed cell death—pyroptosis, apoptosis, and necroptosis, may contribute to acute ocular hypertension (AOH)-induced retinal ganglion cell (RGC) death. Previous study has demonstrated that melatonin exerted neuroprotective effects in many retinal degenerative diseases. This study aimed to explore the role of melatonin in PANoptosis after AOH injury, and its underlying mechanisms.
Methods :
A murine AOH model was used in this study. Melatonin or the equal volume of saline containing 0.5% ethanol were administered by daily intraperitoneal injection to AOH mice. Hematoxylin & eosin staining, and optical coherence tomography were used to observe the changes of retinal structure. Electroretinogram was used to detect changes in visual function. TUNEL assay and PI assay were used to detect the apoptotic and necrotic cells. Immunofluorescence, western blot and real-time PCR were performed to evaluate the localization and quantitative changes of protein.
Results :
Melatonin treatment attenuated the losses of ganglion cell complex thickness, retinal nerve fiber layer thicknesses (both p<0.05) and RGCs (p<0.001). Meanwhile, melatonin improved the amplitudes of a-wave, b-wave, and oscillatory potentials in the electroretinogram (p<0.0001, 0.01, 0.05, respectively). Additionally, melatonin remarkably reduced high IOP-induced RGCs apoptosis by decreasing the number of TUNEL-positive cells and inhibiting the upregulation of cleaved caspase-3, Bax, cleaved caspase-8, p-Bad and downregulation of Bcl-2 induced by AOH injury (p<0.05). Moreover, melatonin attenuated high IOP-induced necroptosis in RGCs and microglia, as demonstrated by a diminishing expression of MLKL, RIP1, and RIP3, along with a decline of PI-, RIP3- and p-RIP3-positive cells in RGCs and microglia of melatonin-treated mice (p<0.05). Furthermore, melatonin reduced expression of NLRP3, ASC, cleaved caspase-1, GSDMD, and cleaved GSDMD, and decreased the positive cells of Iba-1, and IL-1β in microglia of melatonin-treated mice (p<0.05), which means attenuated high IOP-induced pyroptosis and retinal inflammation in microglia.
Conclusions :
Collectively, melatonin ameliorated retinal morphology and prevented retinal dysfunction after AOH and exerts neuroprotective effects via inhibition of PANoptosis in AOH retinas.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.