The protective effect of Moringa oleifera plant extract against glutamate-induced DNA damage and reduced cell viability in a primary retinal ganglion cell line

Targeting cGAS-STING signaling protects retinal ganglion cells from DNA damage-induced cell loss and promotes visual recovery in glaucoma

BACKGROUND

Glaucoma is an optic neurodegenerative disease. Retinal ganglion cells (RGCs) are the fundamental neurons in the trabecular meshwork, and their loss is the main pathological reason for glaucoma. The present study was to investigate mechanisms that regulate RGCs survival.

METHODS

A mouse model of glaucoma was established by injecting hypertonic saline into the limbal veins. RGCs apoptosis was detected by using flow cytometry. Protein expressions in RGCs in response to DNA damage inducer cisplatin treatment were detected by immunofluorescence and western blot. The expressions of inflammatory cytokines were determined using ELISA and real-time PCR.

RESULTS

In the hypertonic saline-injected mice, we found visual function was impaired followed by the increased expression of γH2AX and activation of cGAS-STING signaling. We found that DNA damage inducer cisplatin treatment incurred significant DNA damage, cell apoptosis, and inflammatory response. Mechanistically, cisplatin treatment triggered activation of the cGAS-STING signaling by disrupting mitochondrial function. Suppression of cGAS-STING ameliorated inflammation and protected visual function in glaucoma mice.

CONCLUSIONS

The data demonstrated that cGAS-STING signaling is activated in the damaged retinal ganglion cells, which is associated with increased inflammatory responses, DNA damage, and mitochondrial dysfunction. Targeting the cGAS-STING signaling pathway represents a potential way to alleviate glaucoma-related visual function.

Moringa oleifera Lam.: a comprehensive review on active components, health benefits and application

Moringa oleifera Lam. is an edible therapeutic plant that is native to India and widely cultivated in tropical countries. In this paper, the current application of M. oleifera was discussed by summarizing its medicinal parts, active components and potential mechanism. The emerging products of various formats such as drug preparation and product application reported in the last years were also clarified. Based on literature reports, the unique components and biological activities of M. oleifera need to be further studied. In the future, a variety of new technologies should be applied to the development of M. oleifera products, to enrich the varieties of dosage forms, improve the bitter taste masking technology, and make it better for use in the fields of food and medicine.

Parkin Prevents Glutamate Excitotoxicity Through Inhibiting NLRP3 Inflammasome in Retinal Ganglion Cells

Glutamate excitotoxicity is one of the important pathophysiological culprits in retinal ganglion cells (RGCs) damage after acute optic nerve injury such as traumatic optic neuropathies and glaucoma. It is necessary to elucidate the mechanism of glutamate injury to RGCs in order to find the relevant neuroprotector. In this study, it was observed that the expression of Parkin increased and peaked at 24 h after glutamate injury to RGCs. Moreover, upregulating Parkin attenuated glutamate induced apoptosis, mitochondrial dysfunction and oxidative stress. And, it was found that Parkin could exert neuroprotective effects on RGCs by inhibiting nucleotide-binding domain leucine-rich repeat containing family pyrin domain containing 3 (NLRP3) inflammasome. Moreover, the genetic and pharmacological downregulation of NLRP3 improved survival of RGCs against glutamate excitotoxicity. In the end, knockdown of Parkin exacerbated glutamate induced RGCs damage via triggering NLRP3 inflammasome activation. Taken together, these results shed light on the promising molecular targets for the prevention and treatment of acute optic nerve injury.