Objective To investigate the protective effects of riluzole, a sustained activator of K2P subfamily member TRAAK potassium channel, in human retinal pigment epithelium (hRPE) cells with oxidative induce by tert-butyl hydroperoxide (t-BHP) in vitro, and to evaluate the possible involvement of K2P in the cytoprotective function of retina degeneration diseases. Methods The third to fifth passage of the primary cultured hRPE cells were used in the following experiments．hRPE cells were divided into seven groups: normal control group.t-BHP (300 mu;mol/L) group.t-BHP with riluzole (2, 5, 10, 20 mu;mol/L) group and riluzole (10 mu;mol/L) group. The apoptosis was measured by the 3(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, annexinV/PI double staining flow cytometry. Changes of cells and nuclei morphology were observed under a phase contrast microscope and a fluorescence microscope after 4prime;, 6-diamidino-2-phenylindole (DAPI) staining. Immunofluorescence 1abelling was carried out to analysis the expression of TRAAK. Results After 24 hours incubation with 300 mu;mol/L t-BHP, the cells viability decreased to (58.7plusmn;12.2)% as compared to the normal control groups. The cell viability of t-BHP with riluzole group at different concentrations was higher than the t-BHP group, while 10 mu;mol/L riluzole showed maximally protective effect on hRPE death induced by t-BHP（t=4.84.P＜0.05）. Riluzole remarkably decreased pyknotic nucleus and cell swelling when compared with t-BHP group. Morphology of cells was fusiform with the uniform elliptic nuclei in normal and riluzole group. The Results of annexinV/PI double staining flow cytometry showed that ratio of normal cells were （97.6plusmn;1.3）%, （70.3plusmn;7.0）%, （86.9plusmn;5.2）%, （93.9plusmn;1.5）% in normal group.t-BHP group.t-BHP with riluzole group and riluzole group respectively. The ratio significant decreased in t-BHP group when it was compared with the other groups (t=7.53, 4.59, 6.49, respectively.P＜0.05). By contrast with normal group and riluzole group, the ratio of normal cells in t-BHP with riluzole group had no statistical significance（t=2.94, 1.91, respectively.P＞0.05）. Riluzole (10 mu;mol/L) also significantly decreased the ratio of early stage apoptotic cells from (25.50plusmn;8.02)% to (1.20plusmn;0.72)% in t-BHP injured groups （t=7.13，P＜0.05）. The ratio of early stage apoptotic cells significant decreased in t-BHP group when it was compared with the normal group and riluzole group （t=7.07, 5.94, respectively.P＜0.05）. By comparison with normal group and riluzole group, there are no statistical significance in t-BHP with riluzole group（t=0.06, 1.18, respectively.P＞0.05）. The mean gray values of TRAAK expression were 0.040plusmn;0.003, 0.041plusmn;0.001, 0.049plusmn;0.001, 0.055plusmn;0.001 in normal group.t-BHP group.t-BHP with riluzole group and riluzole group respectively. TRAAK density was significantly higher in t-BHP with riluzole group and riluzole group（t=7.40, 12.70, respectively.P＜0.05）. Conclusions Riluzole can protect hRPE cells against oxidative injury-induced cell death at early apoptosis stage. The mechanism may relate to that riluzole can promote the expression of K2P TRAAK potassium channel.
ObjectiveTo observe the changes of macular morphology and blood flow after minimally invasive vitrectomy (PPV) in patients with severe non-proliferative diabetic retinopathy (sNPDR). MethodsA prospective clinical study. From January 2020 to April 2021, 17 consecutive sNPDR patients with 17 eyes who were diagnosed and received PPV treatment at the Zhongshan Ophthalmic Center of Sun Yat-sen University were included in the study. There were 12 males with 12 eyes and 5 females with 5 eyes; the average age was 55 years old; the average duration of diabetes was 11 years; the average glycosylated hemoglobin was 7.9%. Before the operation and 1, 3, and 6 months after the operation, all the affected eyes underwent best corrected visual acuity (BCVA), standard 7-field fundus color photography, and optical coherence tomography angiography (OCTA). An OCTA instrument was used to scan the macular area of the affected eye with in the range of 3 mm×3 mm to measure the central subfoveal thickness (CST), the thickness of the ganglion cell complex (GCC) in the macular area, the thickness of the retinal nerve fiber layer (RNFL), and the superficial capillary plexus (SCP) vessel density and perfusion density in the macular area, macular avascular zone (FAZ) area, a-circularity index (AI). Before the operation and 6 months after the operation, the least significant difference test was used for the pairwise comparison. ResultsBefore the operation, 1, 3, and 6 months after the operation, the FAZ area of the macular area were 0.34±0.14, 0.35±0.10, 0.37±0.10, 0.36±0.13 mm2, respectively; AI were 0.52±0.13, 0.54±0.11, 0.57±0.10, 0.60±0.11; CST was 282.6±66.7, 290.4±70.9, 287.2±67.5, 273.2±49.6 μm; GCC thickness were 77.1±15.5, 74.3±13.9, 72.6±16.2, 78.5±18.3 μm; the thickness of RNFL was 97.9±13.8, 101.3±14.6, 97.7±12.0, 96.1±11.4 μm, respectively. The overall blood flow density of SCP in the macula were (16.79±1.43)%, (16.71±1.82)%, (17.30±2.25)%, (17.35±1.22)%; the overall perfusion density were 0.32±0.02, 0.32±0.03, 0.33±0.03, 0.33±0.02, respectively. After the operation, the CST increased first and then decreased; the thickness of RNFL increased 1 month after the operation, and then gradually decreased. Comparison of the parameters before and 6 months after the operation showed that the AI improved, and the difference was statistically significant (P=0.049); the difference in FAZ area and the thickness of CST, GCC, and RNFL was not statistically significant (P=0.600, 0.694, 0.802, 0.712); There was no statistically significant difference in the retina SCP blood flow density and perfusion density in the macular area (P=0.347, 0.361). ConclusionCompared with before surgery, there is no significant change in macular structure and blood flow density in sNPDR patients within 6 months after minimally invasive PPV.