Publications -- Abe Clark
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/31655
This collection is limited to articles published under the terms of a creative commons license or other open access publishing agreement since 2016. It is not intended as a complete list of the author's works.
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Browsing Publications -- Abe Clark by Subject "Aqueous Humor / metabolism"
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Item Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork(ARVO Journals, 2022-03) Hernandez, Humberto; Medina-Ortiz, Wanda E.; Luan, Tomi; Clark, Abbot F.; McDowell, Colleen M.Purpose: The trabecular meshwork (TM) is involved in the outflow of aqueous humor and intraocular pressure (IOP) regulation. Regulation of the extracellular matrix (ECM) by TGFbeta2 signaling pathways in the TM has been extensively studied. Recent evidence has implicated toll-like receptor 4 (TLR4) in the regulation of ECM and fibrogenesis in liver, kidney, lung, and skin. Here, we investigated the role of TGFbeta2-TLR4 signaling crosstalk in the regulation of the ECM in the TM and ocular hypertension. Methods: Cross sections of human donor eyes, primary human TM cells in culture, and dissected mouse TM rings were used to determine Tlr4 expression in the TM. Trabecular meshwork cells in culture were treated with TGFbeta2 (5 ng/mL), TLR4 inhibitor (TAK-242, 15 muM), and a TLR4 ligand (cellular fibronectin isoform [cFN]-EDA). A/J (n = 13), AKR/J (n = 7), BALBc/J (n = 8), C3H/HeJ (n = 20), and C3H/HeOuJ (n = 10) mice were injected intravitreally with adenovirus 5 (Ad5).hTGFbeta2c226s/c228s in one eye, with the uninjected contralateral eye serving as a control. Conscious IOP measurements were taken using a TonoLab rebound tonometer. Results: Toll-like receptor 4 is expressed in the human and mouse TM. Inhibition of TLR4 signaling in the presence of TGFbeta2 decreases fibronectin expression. Activation of TLR4 by cFN-EDA in the presence of TGFbeta2 further increases fibronectin, laminin, and collagen-1 expression, and TLR4 signaling inhibition blocks this effect. Ad5.hTGFbeta2c226s/c228s induces ocular hypertension in wild-type mice but has no effect in Tlr4 mutant (C3H/HeJ) mice. Conclusions: These studies identify TGFbeta2-TLR4 crosstalk as a novel pathway involved in ECM regulation in the TM and ocular hypertension. These data further explain the complex mechanisms involved in the development of glaucomatous TM damage.Item TGFbeta2 Induces the Formation of Cross-Linked Actin Networks (CLANs) in Human Trabecular Meshwork Cells Through the Smad and Non-Smad Dependent Pathways(ARVO Journals, 2017-02) Montecchi-Palmer, Michela; Bermudez, Jaclyn Y.; Webber, Hannah C.; Patel, Gaurang C.; Clark, Abbot F.; Mao, WeimingPurpose: Increased intraocular pressure results from increased aqueous humor (AH) outflow resistance at the trabecular meshwork (TM) due to pathologic changes including the formation of cross-linked actin networks (CLANs). Transforming growth factor beta2 (TGFbeta2) is elevated in the AH and TM of primary open angle glaucoma (POAG) patients and induces POAG-associated TM changes, including CLANs. We determined the role of individual TGFbeta2 signaling pathways in CLAN formation. Methods: Cultured nonglaucomatous human TM (NTM) cells were treated with control or TGFbeta2, with or without the inhibitors of TGFbeta receptor, Smad3, c-Jun N-terminal kinases (JNK), extracellular signal regulated kinase (ERK), P38, or Rho-associated protein kinase (ROCK). NTM cells were cotreated with TGFbeta2 plus inhibitors for 10 days or pretreated with TGFbeta2 for 10 days followed by 1-hour inhibitor treatment. NTM cells were immunostained with phalloidin-Alexa-488 and 4',6-diamidino-2-phenylindole (DAPI). Data were analyzed using 1-way ANOVA and Dunnett's post hoc test. Results: TGFbeta2 significantly induced CLAN formation (n = 6 to 12, P < 0.05), which was completely inhibited by TGFbeta receptor, Smad3, and ERK inhibitors, as well as completely or partially inhibited by JNK, P38, and ROCK inhibitors, depending on cell strains. One-hour exposure to ROCK inhibitor completely resolved formed CLANs (P < 0.05), whereas TGFbeta receptor, Smad3 inhibitor, and ERK inhibitors resulted in partial or complete resolution. The JNK and P38 inhibitors showed partial or no resolution. Among these inhibitors, the ROCK inhibitor was the most disruptive to the actin stress fibers, whereas ERK inhibition showed the least disruption. Conclusions: TGFbeta2-induced CLANs in NTM cells were prevented and resolved using various pathway inhibitors. Apart from CLAN inhibition, some of these inhibitors also had different effects on actin stress fibers.