Abstract
Purpose :
Although the ECM in TM cells is known to be important in IOP regulation, the molecular mechanisms involved in generating a glaucomatous environment in the TM remain largely unknown. Recently we identified a molecular pathway, TGFβ2-TLR4 signaling crosstalk, as an important regulator of glaucomatous damage in the TM which contributes to ECM deposition and fibrosis. Here we characterized a novel molecular target, A20 (also known as TNFAIP3), within this pathway which may help to block pathological TGFβ2-TLR4 signaling, ultimately leading to new treatments to prevent the development and progression of glaucoma.
Methods :
A20 distribution within the outflow pathway was determined by probing cross sections of human donor eyes. For culture studies, primary human trabecular meshwork cells were grown to confluence, switched to serum free media, and then treated for 48hrs with TGFβ2 (5 ng/mL), TLR4 inhibitor (TAK-242, 15 μM), TGFβ2 and TLR4 inhibitor, or PBS as a control. Lysates were collected and immunoblotted for A20 expression.
Results :
A20, an endogenous regulator of TLR4 signaling, is expressed in the human TM (n=5 human donor eyes). A20 positive labeling was evident throughout the TM layers. Immunoblotting of cell lysates from treated primary TM cell strains showed that TGFβ2 decreases A20 expression (p=0.01), but TLR4 inhibition had no effect on A20 expression in these experimental conditions (n=3 primary cell strains).
Conclusions :
This ongoing study reports the distribution and expression of A20 in human TM tissue and primary cells as it relates to the TGFβ2-TLR4 crosstalk pathway. TGFβ2-TLR4 crosstalk may be an important mechanistic pathway in the development of glaucomatous TM damage and identifying endogenous regulators of this pathogenetic pathway such as A20 may provide novel therapeutic targets.
This is a 2020 ARVO Annual Meeting abstract.