Transcorneal Electrical Stimulation Inhibits Retinal Microglial Activation and Enhances Retinal Ganglion Cell Survival After Acute Ocular Hypertensive Injury - PubMed (original) (raw)

Transcorneal Electrical Stimulation Inhibits Retinal Microglial Activation and Enhances Retinal Ganglion Cell Survival After Acute Ocular Hypertensive Injury

Lin Fu et al. Transl Vis Sci Technol. 2018.

Abstract

Purpose: To investigate the effect of transcorneal electrical stimulation (TcES) on retinal ganglion cell (RGC) function and survival after acute ocular hypertension-related retinal injury in gerbil eyes.

Methods: Gerbil eyes were subjected to acute ocular hypertensive injury (80 mm Hg for 60 minutes). In the treatment group, TcES was applied to the surgical eye immediately and then twice weekly for a total of 1 month. In the control group, sham TcES was given to the surgical eye at the same time points. Retinal function was assessed and compared between groups using flash electroretinography. For histological analysis, the number of RGC and microglial cells were counted by immunofluorescence staining after the gerbils were sacrificed on day 7 and day 28. Real-time polymerase chain reaction and western blot analysis were conducted to compare expression of interleukin (IL)-10, IL-6, COX-2, tumor necrosis factor (TNF)-α, and NF-κB phosphorylation among groups.

Results: TcES-treated eyes had significantly higher RGC survival at 1 month compared to controls. This was associated with RGC function. Furthermore, TcES-treated eyes were shown to have increased IL-10 expression, with a corresponding reduction in IL-6 and COX-2 expression as well as reduction in NF-κB phosphorylation. This was associated with a suppression in microglial cell activation in TcES-treated eyes.

Conclusions: Early treatment with TcES in gerbils protected the RGC from secondary damage and preserved retinal function in acute ocular hypertensive injury through modulation of the microglial-cell activated local inflammatory response.

Translational relevance: Our study strengthens the argument for translating TcES as a viable treatment in acute glaucoma.

Keywords: acute ocular hypertensive injury; anti-inflammatory; neuroprotection; transcorneal electrical stimulation.

PubMed Disclaimer

Figures

Figure 1

Figure 1

Setting of AOH induction. (a) Anterior chamber infusion of BSS through a needle to the gerbil's eye. (b) Intraocular view of the infusion under microscope. (c) The BSS was hanged at a height of 2.6 m to the gerbil's eye.

Figure 2

Figure 2

IOP readings during AOH. There were no significant differences (P > 0.05) of the IOP readings between the TcES group and sham group at the beginning or the end of the surgery. ns, no significance.

Figure 3

Figure 3

Retinal function reduced after AOH but was improved by TcES. (a), (e) Representative ERG responses at 1 week and 1 month. (b), (c), (d), (f), (g), (h) Averaged amplitudes of 1 week and 1 month a-wave, b-wave, and PhNR. ****P < 0.0001, ***P < 0.001, **P < 0.01, *P < 0.05. n, number of retinas in each group; ns, no significance.

Figure 4

Figure 4

Protection of RGCs by TcES. (a–c) Brn-3a stained RGCs in retinal flat mount of normal, sham, and TcES group at 1 week. (e–g) Brn-3a stained RGCs in retinal flat mount of normal, sham, and TcES group at 1 month. (d, h) Mean density of the RGCs in the retina flat mount of 1 week and 1 month results. Scale bar: 40 μm. ****P < 0.0001. n, number of retinas in each group; ns, no significance.

Figure 5

Figure 5

TcES suppressed the inflammatory factors. (a, b) Western blot results of NF-κB phosphorylation level. (c–e) Western blot results of IL-6, COX-2, and IL-10 protein level. ***P < 0.001, **P < 0.01, *P < 0.05. n, number of retinas in each group; ns, no significance.

Figure 6

Figure 6

Downregulation of mRNA expression level in inflammatory genes by TcES. (a–c) mRNA expression in TNF-α, IL-6, and IL-10 genes. **P < 0.01, *P < 0.05. n, number of retinas in each group; ns, no significance.

Figure 7

Figure 7

TcES inhibited the activation of microglial cells in RGC layer. (a–c) Fluorescent images of Iba-1 stained microglial cells in retinal whole mounts. (d, e) Quantification of microglia density at 1 week and 1 month after AOH. Scale bar: 50 μm. ****P < 0.0001; ***P < 0.001, *P < 0.05. n, number of retinas in each group; ns, no significance.

Similar articles

Cited by

References

    1. Quek DT, Koh VT, Tan GS, Perera SA, Wong TT, Aung T. . Blindness and long-term progression of visual field defects in chinese patients with primary angle-closure glaucoma. . 2011; 152: 463– 469. - PubMed
    1. Tan AM, Loon SC, Chew PT. . Outcomes following acute primary angle closure in an Asian population. . 2009; 37: 467– 472. - PubMed
    1. Qu J, Wang D, Grosskreutz CL. . Mechanisms of retinal ganglion cell injury and defense in glaucoma. . 2010; 91: 48– 53. - PMC - PubMed
    1. Li HY, Ruan YW, Ren CR, Cui Q, So KF. . Mechanisms of secondary degeneration after partial optic nerve transection. . 2014; 9: 565– 574. - PMC - PubMed
    1. Yang X, Hondur G, Tezel G. . Antioxidant treatment limits neuroinflammation in experimental glaucoma. . 2016; 57: 2344– 2354. - PMC - PubMed

LinkOut - more resources