Effect of Nitric Oxide on the Expression of Matrix Metalloproteinase and Its Association with Migration of Cultured Trabecular Meshwork Cells

Long non-coding RNA SNHG11 regulates the Wnt/β-catenin signaling pathway through rho/ROCK in trabecular meshwork cells

Trabecular meshwork (TM) cell dysfunction is the leading cause of elevated intraocular pressure (IOP) and glaucoma. The long non-coding RNA (lncRNA) small nucleolar RNA host gene 11 (SNHG11) is associated with cell proliferation and apoptosis, but its biological functions and role in glaucoma pathogenesis remain unclear. In the present study, we investigated the role of SNHG11 in TM cells using immortalized human TM and glaucomatous human TM (GTM₃ ) cells and an acute ocular hypertension mouse model. SNHG11 expression was depleted using siRNA targeting SNHG11. Transwell assays, quantitative real-time PCR analysis (qRT-PCR), western blotting, and CCK-8 assay were used to evaluate cell migration, apoptosis, autophagy, and proliferation. Wnt/β-catenin pathway activity was inferred from qRT-PCR, western blotting, immunofluorescence, and luciferase reporter and TOPFlash reporter assays. The expression of Rho kinases (ROCKs) was detected using qRT-PCR and western blotting. SNHG11 was downregulated in GTM₃ cells and mice with acute ocular hypertension. In TM cells, SNHG11 knockdown inhibited cell proliferation and migration, activated autophagy, and apoptosis, repressing the Wnt/β-catenin signaling pathway, and activated Rho/ROCK. Wnt/β-catenin signaling pathway activity increased in TM cells treated with ROCK inhibitor. SNHG11 regulated Wnt/β-catenin signaling through Rho/ROCK by increasing GSK-3β expression and β-catenin phosphorylation at Ser33/37/Thr41 while decreasing β-catenin phosphorylation at Ser675. We demonstrate that the lncRNA SNHG11 regulates Wnt/β-catenin signaling through Rho/ROCK via β-catenin phosphorylation at Ser675 or GSK-3β-mediated phosphorylation at Ser33/37/Thr41, affecting cell proliferation, migration, apoptosis, and autophagy. Through its effects on Wnt/β-catenin signaling, SNHG11 is implicated in glaucoma pathogenesis and is a potential therapeutic target.

Cell senescence alters responses of porcine trabecular meshwork cells to shear stress

Mechanical microenvironment and cellular senescence of trabecular meshwork cells (TMCs) are suspected to play a vital role in primary open-angle glaucoma pathogenesis. However, central questions remain about the effect of shear stress on TMCs and how aging affects this process. We have investigated the effect of shear stress on the biomechanical properties and extracellular matrix regulation of normal and senescent TMCs. We found a more significant promotion of Fctin formation, a more obvious realignment of F-actin fibers, and a more remarkable increase in the stiffness of normal cells in response to the shear stress, in comparison with that of senescent cells. Further, as compared to normal cells, senescent cells show a reduced extracellular matrix turnover after shear stress stimulation, which might be attributed to the different phosphorylation levels of the extracellular signal-regulated kinase. Our results suggest that TMCs are able to sense and respond to the shear stress and cellular senescence undermines the mechanobiological response, which may lead to progressive failure of cellular TM function with age.

Effect and Mechanism of Phosphodiesterase Inhibitors on Trabecular Outflow

PURPOSE

Phosphodiesterase (PDE) inhibitors increase matrix metalloproteinase (MMP) production by inhibiting re-uptake of adenosine and may potentiate nitric oxide (NO) activity. This study was performed to investigate the effects and mechanisms of PDE inhibitors on trabecular outflow in cultured human trabecular meshwork cells (HTMCs).

METHODS

Primary HTMC cultures were exposed to 0, 20, and 50 μM dipyridamole (DPD) or theophylline (TPN). Permeability through the HTMC monolayer was assessed using carboxyfluorescein. The production of NO was assessed using the Griess assay and MMP-2 levels were measured via Western blotting.

RESULTS

DPD significantly increased permeability accompanied with increased nitrite concentration and MMP-2 levels (all p < 0.05). TPN increased nitrite but did not affect permeability or MMP-2 levels significantly (p > 0.05). When treated with DPD and TPN together, both permeability and nitrite production were increased; however, MMP-2 levels showed no difference compared to DPD exposure alone (p > 0.05).

CONCLUSIONS

DPD increased trabecular permeability accompanied with increased nitrite production and MMP-2 levels. PDE inhibitors may increase trabecular outflow by increasing MMP-2 levels and by potentiating NO activity through cyclic GMP in HTMC.

Salidroside mitigates hydrogen peroxide-induced injury by enhancement of microRNA-27a in human trabecular meshwork cells

Salidroside (Sal) exerted widely pharmacological effects in multitudinous diseases had been certified. The actual study clarified the protective activity of Sal in H₂O₂-injured human trabecular meshwork (HTM) cells. HTM cells were disposed with H₂O₂ to construct an oxidative damage model in vitro. Then, Sal was utilized to administrate HTM cells, and cell viability, apoptosis, apoptosis-interrelated proteins and ROS production were appraised using CCK-8, flow cytometry, western blot and DCFH-DA staining. MiR-27a inhibitor and its control were transfected into HTM cells, and the influences of miR-27a inhibition in HTM cells stimulated with H₂O₂ and Sal were detected. PI3K/AKT and Wnt/β-catenin pathways were ultimately investigated to uncover the underlying mechanism. We found that H₂O₂ evoked HTM cells oxidative damage, as evidenced by repressing cell viability, inducing apoptosis, activating cleaved-caspase-3/-9 expression and increasing ROS production. Sal significantly lightened H₂O₂-evoked oxidative damage in HTM cells. Additionally, miR-27a was up-regulated by Sal, and miR-27a suppression significantly reversed the protective effect of Sal on H₂O₂-injured HTM cells. Finally, Sal activated PI3K/AKT and Wnt/β-catenin pathways through enhancement of miR-27a in H₂O₂-injured HTM cells. In conclusion, these discoveries suggested that Sal could protect HTM cells against H₂O₂-evoked oxidative damage by activating PI3K/AKT and Wnt/β-catenin pathways through enhancement of miR-27a. Highlights H₂O₂ evokes HTM cells oxidative damage; Sal relieves H₂O₂-induced oxidative damage in HTM cells; Sal enhances miR-27a expression in H₂O₂-injured HTM cells; Repressed miR-27a reverses the protective impacts of Sal on H₂O₂-injured HTM cells; Sal activates PI3K/AKT and Wnt/β-catenin pathways by increasing miR-27a.

Interleukin-27 augments the inhibitory effects of sorafenib on bladder cancer cells

Both sorafenib and interleukin-27 (IL-27) are antineoplastic drugs. This study aimed to investigate the synergistic effect of these two drugs on bladder cancer cells. HTB-9 and T24 cells were stimulated with IL-27 (50 ng/mL), sorafenib (2 μM) or the synergistic action of these two drugs. The cells without treatment acted as control. Cell proliferation, apoptosis and invasion were measured by bromodeoxyuridine assay, flow cytometry and modified Boyden chamber, respectively. Simultaneously, both modified Boyden chamber and scratch assay were used to assess cell migration. Finally, the phosphorylation levels of key kinases in the Akt/mechanistic target of rapamycin (mTOR)/mitogen-activated protein kinase (MAPK) pathway, and expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 were detected by western blot analysis. Stimulation with IL-27 or sorafenib repressed proliferation, migration and invasion but promoted apoptosis, and the effects were all enhanced by the combination of these two drugs in HTB-9 cells. The effect of the combined treatment on bladder cancer cells was verified in T24 cells. Additionally, the phosphorylation levels of AKT, mTOR and MAPK as well as the expression levels of MMP-2 and MMP-9 were all decreased by a single treatment of IL-27 or sorafenib, and further decreased by the combined treatment of these two drugs. The combination of IL-27 and sorafenib inhibited proliferation, migration and invasion and promoted apoptosis of bladder cancer cells compared with mono-drug treatment. Additionally, the AKT/mTOR/MAPK pathway might be implicated in the functional effects by down-regulations of MMP-2 and MMP-9.

The protective role of nitric oxide-dependent innate immunosuppression in the early stage of cartilage damage in rats: Role of nitric oxide in cartilage damage

Objectives

Osteoarthritis (OA) is the most common form of arthritis, affecting approximately 15% of the human population. Recently, increased concentration of nitric oxide in serum and synovial fluid in patients with OA has been observed. However, the exact role of nitric oxide in the initiation of OA has not been elucidated. The aim of the present study was to investigate the role of nitric oxide in innate immune regulation during OA initiation in rats.

Methods

Rat OA was induced by performing meniscectomy surgery while cartilage samples were collected 0, 7, and 14 days after surgery. Cartilage cytokine levels were determined by using enzyme-linked immunosorbent assay, while other proteins were assessed by using Western blot

Results

In the time course of the study, nitric oxide was increased seven and 14 days after OA induction. Pro-inflammatory cytokines including tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were decreased. L-NG-Nitroarginine methyl ester (L-NAME, a non-specific nitric oxide synthase inhibitor) significantly decreased cartilage nitric oxide and blocked immune suppression. Further, L-NAME decreased Matrix metalloproteinase (MMPs) and increased tissue inhibitor of metalloproteinase (TIMP) expression in meniscectomised rats.

Conclusion

Nitric oxide-dependent innate immune suppression protects cartilage from damage in the early stages of OA initiation in rats.

Cite this article: C-C. Hsu, C-L. Lin, I-M. Jou, P-H. Wang, J-S. Lee. The protective role of nitric oxide-dependent innate immunosuppression in the early stage of cartilage damage in rats: Role of nitric oxide in ca rtilage da mage. Bone Joint Res 2017;6:253–258. DOI: 10.1302/2046-3758.64.BJJ-2016-0161.R1.