Eye / Vision
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/30436
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Browsing Eye / Vision by Author "Kasetti, Ramesh"
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Item Glucocorticoid-induced ocular hypertension alters synaptic plasticity and neurotransmission during the progression of glaucomatous neurodegeneration(2021) Maddineni, Prabhavathi; Kasetti, Ramesh; Zode, GulabPurpose: Elevated intraocular pressure (IOP) is the major risk factor for Primary Open Angle Glaucoma (POAG). The neurodegeneration in POAG extends beyond the eye into the visual centers of the brain (VCB). Unfortunately, the underlying mechanisms responsible for IOP-induced neurodegeneration still remain unclear. We have developed a glucocorticoid (GC)-induced mouse model of glaucoma and determined the role of GC-induced ocular hypertension (OHT) on synaptic dysfunction, and how alterations in synaptic plasticity in VCB contribute to neurodegeneration. Methods: C57BL/6J mice were injected with either Dexamethasone (Dex) or Vehicle (Veh) via periocular-route, once a week for 10-weeks. IOP was measured every week and the electrical response of VCB was measured by VEP. Expression of synaptic markers in VCB were assessed by immunostaining. Results: Dex-induced OHT led to glaucomatous neurodegeneration in 10-weeks Dex treated mice compared to Veh mice. We observed RGC hyper excitability during the early stages of axonal damage with significantly increased VEP amplitudes with decreased latencies in 5-weeks Dex treated mice (32µV;73ms) compared to Veh mice (26µV;79ms). Interestingly, we observed complete collapse of neuronal excitability, with decreased VEP amplitudes and increased latencies in 10-weeks Dex treated mice (12µV;132ms) due to chronic OHT. Also, we observed an altered synaptic plasticity with decreased expression of both pre and post synaptic markers in the VCB of the 10-weeks Dex treated mouse. Conclusion: These data highlights that GC-induced OHT alters neurotransmission and axonal synaptic plasticity in VCB during the progression of glaucomatous neurodegeneration.Item TGFβ2 induces Chronic Endoplasmic Reticulum Stress in Trabecular Meshwork cells(2021) Patil, Shruti; Kasetti, Ramesh; Maddineni, Prabhavathi; Zode, GulabPurpose:TGFβ2 induced extracellular matrix(ECM)accumulation is known to be associated with glaucomatous trabecular meshwork(TM)damage and IOP elevation. Previously, we have demonstrated that abnormal ECM accumulation leads to endoplasmic reticulum(ER)stress in TM. Here, we investigated whether TGFβ2 induces ER stress in TM cells and whether chronic ER stress plays a pathological role in dysfunction of TM cells. Methods:Primary human TM cells were treated with vehicle or recombinant TGFβ2(5ng/mL) to determine its effect on chronic ER stress markers(GRP78,ATF4 and CHOP)and ECM proteins(Fibronectin and Collagen-I/IV). Chronic ER stress-induced ATF4/CHOP were genetically knocked-down using targeted CRISPR/Cas9 expression plasmids, or by transducing with ad5-ATF4deltaRK that inhibits endogenous ATF4 activity. The effect on IOP of intravitreal gene delivery of active-TGFβ2 viral-vector in Chop-/- and C57BL/6J mice was evaluated. Pharmacological inhibition of ER stress using ATF4/CHOP inhibitor ISRIB and chemical chaperon sodium4phenylbutyrate(PBA) was also determined on TGFβ2-treated TM cells. Results:Westernblot and immunostaining demonstrated that TGFβ2 induced chronic ER stress markers along with increased levels of ECM proteins, suggesting TGFβ2-induced ECM deposition is associated with ER stress. Knockdown of key transcriptional factors, ATF4/CHOP, and ISRIB treatment prevented TGFβ2-induced ECM expression and reduced ER stress in TM cells. Moreover, activeTGFβ2 viral delivery caused no IOP elevation in Chop-/-mice compared to control C57BL/6J mice. Treatment of TM cells with PBA also inhibited TGFβ2-induced fibronectin deposition via induced expression and activation of MMP2/9. Conclusion:This study indicates that TGFβ2 induces chronic ER stress, which is associated with increased ECM accumulation.