Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork

Hernandez, Humberto; Medina-Ortiz, Wanda E.; Luan, Tomi; Clark, Abbot F.; McDowell, Colleen M

doi:10.1167/iovs.16-21331

Cited by 44 publications

(90 citation statements)

References 59 publications

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“…Therefore, fibronectin may act as a major regulator of Dex-induced ECM accumulation and ER stress induction in TM cells. Consistent with this, a recent study has demonstrated that treatment of primary human TM cells with cellular fibronectin increased expression of other ECM proteins including collagen I and laminin 65 . In the present study, we observed that knockdown of fibronectin reduced Dex-induced ER stress in TM cells.…”

Section: Discussionsupporting

confidence: 63%

Increased synthesis and deposition of extracellular matrix proteins leads to endoplasmic reticulum stress in the trabecular meshwork

Kasetti

Maddineni

Millar

et al. 2017

Sci Rep

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Increased synthesis and deposition of extracellular matrix (ECM) proteins in the trabecular meshwork (TM) is associated with TM dysfunction and intraocular pressure (IOP) elevation in glaucoma. However, it is not understood how ECM accumulation leads to TM dysfunction and IOP elevation. Using a mouse model of glucocorticoid (GC)-induced glaucoma, primary human TM cells and human post-mortem TM tissues, we show that increased ECM accumulation leads to endoplasmic reticulum (ER) stress in the TM. The potent GC, dexamethasone (Dex) increased the secretory protein load of ECM proteins in the ER of TM cells, inducing ER stress. Reduction of fibronectin, a major regulator of ECM structure, prevented ER stress in Dex-treated TM cells. Overexpression of fibronectin via treatment with cellular fibronectin also induced chronic ER stress in primary human TM cells. Primary human TM cells grown on ECM derived from Dex-treated TM cells induced ER stress markers. TM cells were more prone to ER stress from ECM accumulation compared to other ocular cell types. Moreover, increased co-localization of ECM proteins with ER stress markers was observed in human post-mortem glaucomatous TM tissues. These data indicate that ER stress is associated with increased ECM accumulation in mouse and human glaucomatous TM tissues.

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Section: Discussionsupporting

confidence: 63%

Increased synthesis and deposition of extracellular matrix proteins leads to endoplasmic reticulum stress in the trabecular meshwork

Kasetti

Maddineni

Millar

et al. 2017

Sci Rep

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“… 45 We also recently have identified TGFβ2-TLR4 signaling crosstalk as an important regulator of the ECM in the TM and ocular hypertension. 55 Here, we demonstrated that TGFβ2 regulates BAMBI expression in TM cells, knockdown of Bambi induces ECM production in TM cells in vitro and in vivo, and knockdown of Bambi in the mouse TM induces ocular hypertension and outflow resistance.…”

mentioning

confidence: 70%

BMP and Activin Membrane Bound Inhibitor Regulates the Extracellular Matrix in the Trabecular Meshwork

Hernandez

Millar

Curry

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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PurposeThe trabecular meshwork (TM) has an important role in the regulation of aqueous humor outflow and IOP. Regulation of the extracellular matrix (ECM) by TGFβ2 has been studied extensively. Bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI) has been shown to inhibit or modulate TGFβ2 signaling. We investigate the role of TGFβ2 and BAMBI in the regulation of TM ECM and ocular hypertension.MethodsMouse TM (MTM) cells were isolated from B6;129S1-Bambitm1Jian/J flox mice, characterized for TGFβ2 and dexamethasone (DEX)–induced expression of fibronectin, collagen-1, collagen-4, laminin, α-smooth muscle actin, cross-linked actin networks (CLANs) formation, and DEX-induced myocilin (MYOC) expression. MTM cells were transduced with Ad5.GFP to identify transduction efficiency. MTM cells and mouse eyes were transduced with Ad5.Null, Ad5.Cre, Ad5.TGFβ2, or Ad5.TGFβ2 + Ad5.Cre to evaluate the effect on ECM production, IOP, and outflow facility.ResultsMTM cells express TM markers and respond to DEX and TGFβ2. Ad5.GFP at 100 MOI had the highest transduction efficiency. Bambi knockdown by Ad5.Cre and Ad5.TGFβ2 increased fibronectin, collagen-1, and collagen-4 in TM cells in culture and tissue. Ad5.Cre, Ad5.TGFβ2, and Ad5.TGFβ2 + Ad5.Cre each significantly induced ocular hypertension and lowered aqueous humor outflow facility in transduced eyes.ConclusionsWe show for the first time to our knowledge that knockdown of Bambi alters ECM expression in cultured cells and mouse TM, reduces outflow facility, and causes ocular hypertension. These data provide a novel insight into the development of glaucomatous TM damage and identify BAMBI as an important regulator of TM ECM and ocular hypertension.

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“…2E−H). The dose of TGF-β2, although higher than pathological levels observed in POAG, is within the range that upregulates fibrillogenic proteins in vitro in primary human TM cells 5,25,39,40 ( Supplementary Fig. S3).…”

Section: Tgf-β2 Upregulates Hepcidin and Downstream Proteins In The Tmentioning

confidence: 94%

TGFβ2-Hepcidin Feed-Forward Loop in the Trabecular Meshwork Implicates Iron in Glaucomatous Pathology

Ashok

Chaudhary

Kritikos

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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Elevated levels of transforming-growth-factor (TGF)-β2 in the trabecular meshwork (TM) and aqueous humor are associated with primary open-angle glaucoma (POAG). The underlying mechanism includes alteration of extracellular matrix homeostasis through Smad-dependent and independent signaling. Smad4, an essential co-Smad, upregulates hepcidin, the master regulator of iron homeostasis. Here, we explored whether TGF-β2 upregulates hepcidin, implicating iron in the pathogenesis of POAG. METHODS. Primary human TM cells and human and bovine ex vivo anterior segment organ cultures were exposed to bioactive TGF-β2, hepcidin, heparin (a hepcidin antagonist), or N-acetyl carnosine (an antioxidant), and the change in the expression of hepcidin, ferroportin, ferritin, and TGF-β2 was evaluated by semiquantitative RT-PCR, Western blotting, and immunohistochemistry. Increase in reactive oxygen species (ROS) was quantified with dihydroethidium, an ROS-sensitive dye. RESULTS. Primary human TM cells and bovine TM tissue synthesize hepcidin locally, which is upregulated by bioactive TGF-β2. Hepcidin downregulates ferroportin, its downstream target, increasing ferritin and iron-catalyzed ROS. This causes reciprocal upregulation of TGF-β2 at the transcriptional and translational levels. Heparin downregulates hepcidin, and reduces TGF-β2-mediated increase in ferritin and ROS. Notably, both heparin and N-acetyl carnosine reduce TGF-β2-mediated reciprocal upregulation of TGF-β2. CONCLUSIONS. The above observations suggest that TGF-β2 and hepcidin form a selfsustained feed-forward loop through iron-catalyzed ROS. This loop is partially disrupted by a hepcidin antagonist and an anti-oxidant, implicating iron and ROS in TGF-β2mediated POAG. We propose that modification of currently available hepcidin antagonists for ocular use may prove beneficial for the therapeutic management of TGF-β2-associated POAG.

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Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork

Cited by 44 publications

References 59 publications

Increased synthesis and deposition of extracellular matrix proteins leads to endoplasmic reticulum stress in the trabecular meshwork

Increased synthesis and deposition of extracellular matrix proteins leads to endoplasmic reticulum stress in the trabecular meshwork

BMP and Activin Membrane Bound Inhibitor Regulates the Extracellular Matrix in the Trabecular Meshwork

TGFβ2-Hepcidin Feed-Forward Loop in the Trabecular Meshwork Implicates Iron in Glaucomatous Pathology

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