Role of MMP-9 in the breakdown of barrier integrity of the corneal endothelium in response to TNF-α

Pathophysiology of Corneal Endothelial Cell Loss in Dry Eye Disease and Other Inflammatory Ocular Disorders

PURPOSE

Dry eye disease (DED) and other inflammatory ocular disorders have been reported to be associated with decreased corneal endothelial cell density (CECD), however the mechanism of underlying endothelial cell loss remains unknown.

METHODS

We conducted a comprehensive literature search of English-written publications on dry eye disease, corneal endothelial cell loss, Sjögren's syndrome, and Graft Vs Host Disease (GVHD), to review the effects of DED and other inflammatory ocular surface conditions on CECD.

RESULTS

A total of 78 studies were included in our study. Loss of corneal neurotrophic support, cytotoxic stress, and a heightened immune response, all of which may occur secondarily to a common causative agent such as inflammation, are major contributors to reduced CECD.

CONCLUSION

More studies are needed to determine how the interrelated pathways of altered corneal nerve function and upregulated expression of inflammatory activity influence corneal endothelial cell loss.

Role of Oxidative Stress in the Disruption of the Endothelial Apical Junctional Complex During Corneal Cold Storage

Purpose: To characterize the impact of corneal cold storage (CS) on the endothelial apical junctional complex (AJC). Methods: Porcine corneas were held in CS (4°C; 1-7 days) with Cornisol™ preservation medium supplemented with epothilone B (EpoB; microtubule stabilizer; 100 nM), SB-203580 (p38 mitogen-activated protein [MAP] kinase inhibitor; 20 μM), or antioxidants (quercetin, 100 μM; vitamin E, 1 mM; deferoxamine, an iron chelator, 10 mM). After CS termination, the damage to endothelial AJC was characterized by imaging perijunctional actomyosin ring (PAMR) and zonula occludens (ZO-1). The effects of EpoB and SB-203580 were characterized by imaging microtubules. The loss in the barrier function was assessed in cultured cells grown on biotin-coated gelatin by permeability to fluorescein isothiocyanate (FITC)-avidin. The accumulation of reactive oxygen species (ROS), altered mitochondrial membrane potential (MMP), lipid peroxidation, and lactate dehydrogenase (LDH) release were also determined in response to CS. Results: CS led to the loss of microtubules, destruction of PAMR, and breakdown of ZO-1 in the endothelium. The severity of damage increased when CS was prolonged. Although rewarming of the tissue increased the damage, the effect was marginal. CS also induced accumulation of ROS, alteration in MMP, lipid peroxidation, enhanced LDH release, and increased permeability to FITC-avidin. These changes were opposed by EpoB, SB-203580, and antioxidants. Conclusion: Corneal CS destroys AJC of the endothelium, leading to loss of its barrier function. The effects were surmounted by microtubule stabilization, p38 MAP kinase inhibition, and antioxidants. Thus, there is potential for reformulation of the preservation medium to maintain the health of the donor corneal endothelium before transplantation.

Imbalanced IL-37/TNF-α/CTSS signaling disrupts corneal epithelial barrier in a dry eye model in vitro

PURPOSE

To explore novel role and molecular mechanism of a natural anti-inflammatory cytokine interleukin (IL) 37 in preventing corneal epithelial barrier disruption from hyperosmolar stress as can occur in dry eye disease.

METHODS

Primary human corneal epithelial cells (HCECs) were cultured from fresh donor limbal explants. An in vitro dry eye model with hyperosmolar stress was established by switching HCECs from isosmolar (312mOsM) to hyperosmolar medium (350-500 mOsM), and some cells were treated with rhIL-37 or rhTNF-α, for different periods (2-48 h). The expression of cytokines and cathepsin S, and barrier protein integrity were evaluated by RT-qPCR, ELISA, and immunofluorescent staining with confocal microscopy.

RESULTS

The integrity of epithelial barrier was significantly disrupted in HCECs exposed to hyperosmolar medium, as shown by immunofluorescent images of tight junction (TJ, ZO-1, occludin and claudin-1) and adheren junction (E-cadherin) proteins. TNF-α accentuated hyperosmolar-induced disruption of TJ barrier functional integrity whereas exposure to IL-37 blunted or even reversed these changes. Cathepsin S, encoded by CTSS gene, was found to directly disrupt epithelial barrier integrity. Interestingly, CTSS expression was significantly induced by TNF-α and hyperosmolarity, while exogenous rhIL-37 inhibited TNF-α and CTSS expression at mRNA and protein levels following hyperosmolar stress. Furthermore, rhIL-37 restored barrier protein integrity, observed in 2D and 3D confocal immunofluorescent images, in HCECs under hyperosmolar stress.

CONCLUSION

Our findings demonstrate a novel signaling pathway by which anti-inflammatory cytokine IL-37 prevents corneal epithelial barrier disruption under hyperosmotic stress via suppressing TNF-α and CTSS expression. This study provides new insight into mechanisms protecting corneal barrier in dry eye disease.

Research models of sulfur mustard- and nitrogen mustard-induced ocular injuries and potential therapeutics

Sulfur mustard (SM) is a notorious, bifunctional alkylating vesicant that was first used in warfare during World War I in 1917 and since then has been deployed in numerous skirmishes with its most recent documented use being during the Middle Eastern conflicts. Apart from its use in combat and terrorist activities, continual threat of accidental exposure from old stockpiles and improperly discarded munitions is ever present, especially to the innocent and unassuming civilian populations. SM can cause devastating injuries, depending on the dosage of SM exposure, route of exposure, as well as the physiological conditions of the individuals exposed. The most common routes of exposure are ocular, dermal, and exposure to the lungs and respiratory tissues through inhalation. Eyes are the most susceptible organ to SM-induced toxicities owing to their high moisture content and rapidly dividing cells. Additionally, ocular injury causes the most expeditious disablement of individuals even upon whole-body exposures. Therefore, it is imperative to understand the mechanisms underlying SM-induced ocular toxicity and design therapeutic interventions to prevent/mitigate ocular injuries. Ocular SM exposure may cause a wide range of symptoms such as inflammation, lacrimation, itching, dryness, photophobia, edema of the cornea/sclera/retina/iris, conjunctivitis, degradation of the corneal layer, fusion of two or more ocular layers, neovascularization, fibrosis, and temporary or permanent structural damage to one or more ocular layers. These symptoms may lead to vision impairments, resulting in partial or complete blindness that may be permanent. The highly toxic and exceedingly notorious nature of SM makes it a highly regulated chemical, requiring very expensive licensing, security, and safety requirements; thus, the more easily accessible analogue, nitrogen mustard (NM) that mimics SM-induced toxicity and injuries is employed in plethora of studies conducted in different animal models and culture systems. This review provides a comprehensive account of the injuries and symptoms that occur upon ocular SM exposures in human patients as well as studies in animal (in vivo, ex vivo) and cell (in vitro) models of SM and NM ocular exposures. Special emphasis has been laid on highlighting the strengths and lacunae in the research as well as the possible unexplored avenues of mechanisms underlying mustard-induced ocular injury that can be explored in future research endeavors. Furthermore, development of therapeutic interventions and targets of interest in the ocular system exposed to SM and NM, based on studies in human patients as well as in vivo, ex vivo, and in vitro models has been discussed in great depth, providing a valuable knowledge database to delineate pathways associated with vesicant-induced toxicity, and strategies/diagnostic tools against SM-induced toxicity.

Dioscin exhibits protective effects on in vivo and in vitro asthma models via suppressing TGF-β1/Smad2/3 and AKT pathways

Dioscin is a natural product that possesses protective effects on multiple chronic injuries, but its effects on asthma are not fully understood. Herein, we evaluated its effects on asthmatic mice established by ovalbumin (OVA) sensitization and challenges and further explored the mechanism. Inflammatory cells in bronchoalveolar lavage fluids (BALFs) were analyzed using Diff-Quik staining. OVA-specific immunoglobulin E (IgE)/IgG1 in serum and inflammatory cytokines (interleukin 4[IL-4], IL-5, IL-13, and tumor necrosis factor-α) in BALFs and lung tissues were measured using Enzyme-Linked Immunosorbent Assay Kits. Hematoxylin and eosin, periodic acid-Schiff, and immunohistochemistry staining showed histopathological changes in lung tissues. Epithelial-mesenchymal transition (EMT) in human bronchial epithelial (16HBE) cells was assessed by immunofluorescence staining. Hydroxyproline content was used to evaluate collagen deposition. Polymerase chain reaction and Western blot were performed to measure messenger RNA and protein expression. We found that dioscin treatment (particularly at the dose of 80 mg/kg) significantly inhibited pulmonary inflammation in asthmatic mice, as evidenced by the decreased serum OVA-specific IgE/IgG1 and the reduced inflammatory cells and cytokines in BALFs and lung tissues. Moreover, dioscin effectively ameliorated the goblet cell hyperplasia, mucus hypersecretion, collagen deposition, and smooth muscle hyperplasia in the airways of asthmatic mice. Mechanistically, dioscin restrained the activated TGF-β1/Smad2/3 and protein kinase B (AKT) signal pathways in lung tissues and potently reversed the TGF-β1-induced EMT and phosphorylation of Smad2/3 and AKT in 16HBE cells. Collectively, dioscin displayed protective effects on OVA-induced asthmatic mice via adjusting TGF-β1/Smad2/3 and AKT signal pathways, supporting the fact that dioscin could be a candidate for chronic asthma prevention in the future.

The Role of Metalloproteinases and Their Tissue Inhibitors on Ocular Diseases: Focusing on Potential Mechanisms

Eye diseases are associated with visual impairment, reduced quality of life, and may even lead to vision loss. The efficacy of available treatment of eye diseases is not satisfactory. The unique environment of the eye related to anatomical and physiological barriers and constraints limits the bioavailability of existing agents. In turn, complex ethiopathogenesis of ocular disorders that used drugs generally are non-disease specific and do not act causally. Therefore, there is a need for the development of a new therapeutic and preventive approach. It seems that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have a significant role in the development and progression of eye diseases and could be used in the therapy of these disorders as pharmacological targets. MMPs and TIMPs play an important role in the angiogenesis, epithelial-mesenchymal transition, cell invasion, and migration, which occur in ocular diseases. In this review, we aim to describe the participation of MMPs and TIMPs in the eye diseases, such as age-related macular degeneration, cataract, diabetic retinopathy, dry eye syndrome, glaucoma, and ocular cancers, posterior capsule opacification focusing on potential mechanisms.

Oxidative Stress Induces a Breakdown of the Cytoskeleton and Tight Junctions of the Corneal Endothelial Cells

Purpose: To investigate the impact of oxidative stress, which is a hallmark of Fuchs dystrophy, on the barrier function of the corneal endothelial cells. Methods: Experiments were carried out with cultured bovine and porcine corneal endothelial cells. For oxidative stress, cells were supplemented with riboflavin (Rf) and exposed to UV-A (15-30 min) to induce Type-1 photochemical reactions that release H₂O₂. The effect of the stress on the barrier function was assayed by transendothelial electrical resistance (TER) measurement. In addition, the associated changes in the organization of the microtubules, perijunctional actomyosin ring (PAMR), and ZO-1 were evaluated by immunocytochemistry, which was also repeated after direct exposure to H₂O₂ (100 μM, 1 h). Results: Exposure to H₂O₂ led to the disassembly of microtubules and the destruction of PAMR. In parallel, the contiguous locus of ZO-1 was disrupted, marking a loss of barrier integrity. Accordingly, a sustained loss in TER was induced when cells in the Rf-supplemented medium were exposed to UV-A. However, the addition of catalase (7,000 U/mL) to rapidly decompose H₂O₂ limited the loss in TER. Furthermore, the adverse effects on microtubules, PAMR, and ZO-1 were suppressed by including catalase, ascorbic acid (1 mM; 30 min), or pretreatment with p38 MAP kinase inhibitor (SB-203580; 10 μM, 1 h). Conclusions: Acute oxidative stress induces microtubule disassembly by a p38 MAP kinase-dependent mechanism, leading to the destruction of PAMR and loss of barrier function. The response to oxidative stress is reminiscent of the (TNF-α)-induced breakdown of barrier failure in the corneal endothelium.

Nonantimicrobial Actions of Macrolides: Overview and Perspectives for Future Development

Macrolides are among the most widely prescribed broad spectrum antibacterials, particularly for respiratory infections. It is now recognized that these drugs, in particular azithromycin, also exert time-dependent immunomodulatory actions that contribute to their therapeutic benefit in both infectious and other chronic inflammatory diseases. Their increased chronic use in airway inflammation and, more recently, of azithromycin in COVID-19, however, has led to a rise in bacterial resistance. An additional crucial aspect of chronic airway inflammation, such as chronic obstructive pulmonary disease, as well as other inflammatory disorders, is the loss of epithelial barrier protection against pathogens and pollutants. In recent years, azithromycin has been shown with time to enhance the barrier properties of airway epithelial cells, an action that makes an important contribution to its therapeutic efficacy. In this article, we review the background and evidence for various immunomodulatory and time-dependent actions of macrolides on inflammatory processes and on the epithelium and highlight novel nonantibacterial macrolides that are being studied for immunomodulatory and barrier-strengthening properties to circumvent the risk of bacterial resistance that occurs with macrolide antibacterials. We also briefly review the clinical effects of macrolides in respiratory and other inflammatory diseases associated with epithelial injury and propose that the beneficial epithelial effects of nonantibacterial azithromycin derivatives in chronic inflammation, even given prophylactically, are likely to gain increasing attention in the future. SIGNIFICANCE STATEMENT: Based on its immunomodulatory properties and ability to enhance the protective role of the lung epithelium against pathogens, azithromycin has proven superior to other macrolides in treating chronic respiratory inflammation. A nonantibiotic azithromycin derivative is likely to offer prophylactic benefits against inflammation and epithelial damage of differing causes while preserving the use of macrolides as antibiotics.

Protective Effects of Fucoxanthin Dampen Pathogen-Associated Molecular Pattern (PAMP) Lipopolysaccharide-Induced Inflammatory Action and Elevated Intraocular Pressure by Activating Nrf2 Signaling and Generating Reactive Oxygen Species

Inflammation and oxidative stress are closely related processes in the pathogenesis of various ocular diseases. Uveitis is a disorder of the uvea and ocular tissues that causes extreme pain, decreases visual acuity, and can eventually lead to blindness. The pharmacological functions of fucoxanthin, isolated from brown algae, induce a variety of therapeutic effects such as oxidative stress reduction and repression of inflammation reactions. However, the specific anti-inflammatory effects of fucoxanthin on pathogen-associated molecular pattern (PAMP) lipopolysaccharide-induced uveitis have yet to be extensively described. Therefore, the aim of present study was to investigate the anti-inflammatory effects of fucoxanthin on uveitis in rats. The results showed that fucoxanthin effectively enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in ocular tissues. Furthermore, fucoxanthin significantly increased the ocular activities of superoxide dismutase and decreased the levels of malondialdehyde stimulated by PAMP-induced uveitis. Ocular hypertension and the levels of inflammatory cells and proinflammatory cytokine tumor necrosis factor-alpha in the aqueous humor were alleviated with fucoxanthin treatment. Consequently, compared to the observed effects in lipopolysaccharide groups, fucoxanthin treatment significantly preserved iris sphincter innervation and pupillary function. Additionally, PAMP-induced corneal endothelial disruption was significantly inhibited by fucoxanthin treatment. Overall, these findings suggest that fucoxanthin may protect against inflammation from PAMP-induced uveitis by promoting the Nrf2 pathway and inhibiting oxidative stress.

Microtubule Stabilization Protects Hypothermia-Induced Damage to the Cytoskeleton and Barrier Integrity of the Corneal Endothelial Cells

Purpose: To determine the impact of hypothermia on the barrier function of donor corneal endothelium, thereby enhancing the success of corneal transplantation. Methods: Primary cultures of porcine endothelial cells were subjected to hypothermia (15 h; 4°C). The impact on microtubule assembly, peri-junctional actomyosin ring (PAMR), and ZO-1 was assessed by immunocytochemistry with and without pretreatment with a microtubule-stabilizing agent (Epothilone B; EpoB; 100 nM) and a p38 MAP kinase inhibitor (SB-203580; 20 μM). In addition, EpoB-loaded PLGA nanoparticles (ENPs) prepared by nanoprecipitation technique and coated with poly-L-lysine (PLL-ENPs) were administered one-time for sustained intracellular delivery of EpoB. Results: Exposure to hypothermia led to microtubule disassembly concomitant with the destruction of PAMR and the displacement of ZO-1 at the cellular periphery, suggesting a loss in barrier integrity. These adverse effects were attenuated by pretreatment with EpoB or SB-203580. PLL-ENPs possessed a zeta potential of ∼26 mV and a size of ∼110 nm. Drug loading and entrapment efficiency were 5% (w/w) and ∼87%, respectively, and PLL-ENPs showed a biphasic release in vitro: burst phase (1 day), followed by a sustained phase (∼4 weeks). Pretreatment with PLL-ENPs (0.4 mg/mL) for 24 h stabilized the microtubules and opposed the hypothermia-induced damage to PAMR and the redistribution of ZO-1. Conclusions: Hypothermia induces microtubule disassembly via activation of p38 MAP kinase and subsequently breaks down the barrier function of the endothelium. Sustained intracellular delivery of EpoB using nanoparticles has the potential to overcome endothelial barrier failure during prolonged cold storage of donor cornea.

Bioluminescence Imaging of Matrix Metalloproteinases-2 and -9 Activities in Ethanol-injured Cornea of Mice

BACKGROUND/AIM

This study aimed to investigate the usefulness of in vivo bioluminescence imaging (BLI) to examine the role of matrix metalloproteinases (MMP)-2 and MMP-9 activation in the development and healing of ethanol-induced damage in the cornea of mice.

MATERIALS AND METHODS

Mouse corneal injury was induced by topical treatment with 20% ethanol. BLI was obtained from the ocular region of mice intravenously injected with an active-MMP-2/9 probe. In vivo results were validated in primary corneal epithelial cells.

RESULTS

BLI indicated that treatment of the eye with 20% ethanol elevated MMP-2/9 activity, which was inhibited by the application of eye drops (hyaluronic acid and serum). Treatment of corneal epithelial cells with 20% ethanol-increased the activities of MMP-2 and MMP-9, which were also inhibited by eye drops.

CONCLUSION

BLI can be applied in vivo in mice with corneal injury to examine the activity of MMPs and clarify the efficacy of eye drops.

Role of Matrix Metalloproteinase 9 in Ocular Surface Disorders

OBJECTIVES

(1) To explore the role and significance of Matrix Metalloproteinase 9 (MMP-9), a proteolytic enzyme, in various ocular surface diseases of inflammatory, infectious, and traumatic etiology (2), to further elucidate the molecular mechanisms responsible for its overexpression in ocular surface disease states, and (3) to discuss possible targets of therapeutic intervention.

METHODS

A literature review was conducted of primary sources from 1995 onward using search results populated from the US National Library of Medicine search database.

RESULTS

MMP-9 overexpression has been found in in vitro and in vivo models of dry eye disease (DED), corneal ulceration, microbial keratitis, corneal neovascularization, ultraviolet light-induced radiation, and a host of additional surface pathologies. MMP-9 is involved in an intricate signal transduction cascade that includes induction by many proinflammatory molecules including interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-a), nuclear factor kappa light chain enhancer of activated B cells (NF-kB), platelet-activating factor, activator protein 1 (AP-1), and transforming growth factor beta (TGF-B). MMP-9 expression is blunted by a diverse array of molecular factors, such as tissue inhibitors of metalloproteinases, cyclosporine A (CyA), PES_103, epigalloccatechin-3-gallate (EGCG), N-acetylcysteine (NaC), ascorbate, tetracyclines, and corticosteroids. Inhibition of MMP-9 frequently led to improvement of ocular surface disease.

CONCLUSIONS

Novel insights into the mechanistic action of MMP-9 provide potential for new therapeutic modulations of ocular surface diseases mediated by its overexpression.

Effects of ROCK Inhibitors on Apoptosis of Corneal Endothelial Cells in CMV-Positive Posner-Schlossman Syndrome Patients

Purpose

To examine the role of aqueous tumor necrosis factor α (TNF-α)–RhoA–Rho kinase (ROCK) signaling in cytomegalovirus (CMV)-induced apoptosis and the barrier function of cultured human corneal endothelial cells (hCECs) in CMV-positive Posner–Schlossman syndrome (CMV+/PSS) patients.

Methods

Aqueous levels of TNF-α, IL-8, IL-10, and several other cytokines in 19 CMV+/PSS patients and 20 healthy control subjects were quantitated using a multiplex assay. The expression of active RhoA in hCECs post-CMV infection was determined using western blotting (WB). The expression levels of TNF-α and nuclear factor kappa B (NF-κB) in CMV-infected hCECs were examined by immunocytochemistry (ICC) and WB with and without ROCK inhibitors. The apoptotic rate and barrier integrity in CMV-infected hCECs were also examined.

Results

The expression levels of TNF-α, monocyte chemoattractant protein-1 (MCP-1), IL-8, and IL-10 were upregulated in the aqueous humor of CMV+/PSS patients, and among these upregulated cytokines aqueous TNF-α was negatively correlated with the number of corneal endothelial cells. In CMV-infected hCECs, upregulation of TNF-α and NF-κB was determined by WB and ICC. In hCECs, CMV infection induced apoptosis and significantly impaired cell–cell contacts, effects that were attenuated by treatment with a ROCK inhibitor.

Conclusions

Aqueous TNF-α was upregulated in CMV+/PSS patients, which may have triggered corneal endothelial cell loss. Modulation of TNF-α, including its downstream Rho–ROCK signaling, could serve as a novel treatment modality for corneal endothelial cell loss in CMV+/PSS patients.

SIRT1 Activation Using CRISPR/dCas9 Promotes Regeneration of Human Corneal Endothelial Cells through Inhibiting Senescence

Human corneal endothelial cells (hCECs) are restricted in proliferative capacity in vivo. Reduction in the number of hCEC leads to persistent corneal edema requiring corneal transplantation. This study demonstrates the functions of SIRT1 in hCECs and its potential for corneal endothelial regeneration. Cell morphology, cell growth rates and proliferation-associated proteins were compared in normal and senescent hCECs. SIRT1 was activated using the CRISPR/dCas9 activation system (SIRT1a). The plasmids were transfected into CECs of six-week-old Sprague–Dawley rats using electroporation and cryoinjury was performed. Senescent cells were larger, elongated and showed lower proliferation rates and lower SIRT1 levels. SIRT1 activation promoted the wound healing of CECs. In vivo transfection of SIRT1a promoted the regeneration of CECs. The proportion of the S-phase cells was lower in senescent cells and elevated upon SIRT1a activation. SIRT1 regulated cell proliferation, proliferation-associated proteins, mitochondrial membrane potential, and oxidative stress levels. In conclusion, corneal endothelial senescence is related with a decreased SIRT1 level. SIRT1a promotes the regeneration of CECs by inhibiting cytokine-induced cell death and senescence. Gene function activation therapy using SIRT1a may serve as a novel treatment strategy for hCEC diseases.

Mechanisms of Blood-Retinal Barrier Disruption by HIV-1

It has been found that human immunodeficiency virus (HIV)-1 RNA or antigens can be detected in the intraocular tissues of HIV-1 patients even under effective highly active anti-retroviral therapy (HAART). In vivo, blood-retinal barrier (BRB) establishes a critical, physiological guardian against microbial invasion of the eye, but may be compromised in the presence of HIV-1. The envelope glycoprotein gp120 is exposed on the surface of the HIV envelope, essential for virus entry into cells by the attachment to specific cell surface receptors. The BRB disruption by glycoprotein gp120 has been widely recognized, which is toxic to human retinal epithelial cells (RPE) and umbilical vein endothelial cells (HUVEC). The present review elaborates on various mechanisms of BRB disruption induced by HIV gp120, which may represent potential targets for the prevention of ocular HIV complications in the future.

Regulation of matrix metalloproteinases 2 and 9 in corneal neovascularization

Corneal neovascularization (CNV), a pathological process of angiogenesis, can lead to serious consequences in the cornea. CNV is generally proved to associate with inflammation in the cornea closely, which is mainly elicited by the disruption of equilibrium between angiogenic and antiangiogenic factors. Angiogenic factors including vascular endothelial growth factors (VEGFs), basic fibroblast growth factors (bFGFs), and matrix metalloproteinases (MMPs) are vital factors in the formation of CNV. Especially VEGFs are convinced to be the core angiogenic factors in CNV, and MMPs are proved to exert dual effects on the process. Strikingly, matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) are determined to play key roles in the formation of CNV, while the mechanism is still vague. In this review, the latest researches are reviewed to discuss the role of MMP-2 and MMP-9 in CNV, respectively, and some inhibitors of them are presented. We hope to provide a new direction of drug research for CNV.

Pharmacological inhibition of β-catenin prevents EndMT in vitro and vascular remodeling in vivo resulting from endothelial Akt1 suppression

Endothelial to mesenchymal transition (EndMT), where endothelial cells acquire mesenchymal characteristics has been implicated in several cardiopulmonary, vascular and fibrotic diseases. The most commonly studied molecular mechanisms involved in EndMT include TGFβ, Notch, interleukin, and interferon-γ signaling. As of today, the contributions of Akt1, an important mediator of TGFβ signaling and a key regulator of endothelial barrier function to EndMT remains unclear. By using the ShRNA based gene silencing approach and endothelial-specific inducible Akt1 knockdown (ECKO^Akt1) mice, we studied the role of Akt1 in EndMT in vitro and pathological vascular remodeling in vivo. Stable, Akt1 silenced (ShAkt1) human microvascular endothelial cells (HMECs) indicated increased expression of mesenchymal markers such as N-cadherin and α-SMA, phosphorylation of Smad2/3, cellular stress via activation of p38 MAP Kinase and the loss of endothelial nitric oxide synthase (eNOS) accompanied by a change in the morphology of HMECs in vitro and co-localization of endothelial and mesenchymal markers promoting EndMT in vivo. EndMT as a result of Akt1 loss was associated with increased expression of TGFβ2, a potent inducer of EndMT and mesenchymal transcription factors Snail1, and FoxC2. We observed that hypoxia-induced lung vascular remodeling is exacerbated in ECKO^Akt1 mice, which was reversed by pharmacological inhibition of β-catenin. Thus, we provide novel insights into the role of Akt1-mediated β-catenin signaling in EndMT and pathological vascular remodeling, and present β-catenin as a potential target for therapy for various cardiopulmonary diseases involving vascular remodeling.

MMP-9-induced increase in intestinal epithelial tight permeability is mediated by p38 kinase signaling pathway activation of MLCK gene

Matrix metalloproteinase-9 (MMP-9) has been implicated as being an important pathogenic factor in inflammatory bowel disease (IBD). MMP-9 is markedly elevated in intestinal tissue of patients with IBD, and IBD patients have a defective intestinal tight-junction (TJ) barrier manifested by an increase in intestinal permeability. The loss of intestinal epithelial barrier function is an important contributing factor in the development and prolongation of intestinal inflammation; however, the role of MMP-9 in intestinal barrier function remains unclear. The purpose of this study was to investigate the effect of MMP-9 on the intestinal epithelial TJ barrier and to delineate the intracellular mechanisms involved by using in vitro (filter-grown Caco-2 monolayers) and in vivo (mouse small intestine recycling perfusion) systems. MMP-9 caused a time- and dose-dependent increase in Caco-2 TJ permeability. MMP-9 also caused an increase in myosin light-chain kinase (MLCK) gene activity, protein expression, and enzymatic activity. The pharmacological MLCK inhibition and siRNA-induced knockdown of MLCK inhibited the MMP-9-induced increase in Caco-2 TJ permeability. MMP-9 caused a rapid activation of the p38 kinase signaling pathway and inhibition of p38 kinase activity prevented the MMP-9-induced increase in MLCK gene activity and the increase in Caco-2 TJ permeability. MMP-9 also caused an increase in mouse intestinal permeability in vivo, which was accompanied by an increase in MLCK expression. The MMP-9-induced increase in mouse intestinal permeability was inhibited in MLCK-deficient mice. These data show for the first time that the MMP-9-induced increase in intestinal TJ permeability in vitro and in vivo was mediated by the p38 kinase signal transduction pathway upregulation of MLCK gene activity and that therapeutic targeting of these pathways can prevent the MMP-9-induced increase in intestinal TJ permeability. NEW & NOTEWORTHY MMP-9 is highly elevated in patients with IBD. IBD patients have compromised intestinal TJ barrier function manifested by an increase in intestinal permeability and intestinal inflammation. This study shows that MMP-9, at clinically achievable concentrations, causes an increase in intestinal TJ permeability in vitro and in vivo. In addition, a MMP-9-induced increase in intestinal TJ permeability was mediated by an increase in MLCK gene and protein expression via the p38 kinase pathway.

Cytokine Levels in the Aqueous Humor Are Associated With Corneal Thickness in Eyes With Bullous Keratopathy

PURPOSE

We sought to investigate the association between the severity of bullous keratopathy and proinflammatory cytokine levels in the aqueous humor (AqH).

DESIGN

Cross-sectional study.

METHODS

This study included a total of 95 eyes: 62 with bullous keratopathy and 33 that underwent cataract surgery. Central corneal thickness (CCT) and central corneal volume within 4 and 6 mm (CCV_4mm and CCV_6mm, respectively) were determined using anterior segment optical coherence tomography. A total of 95 AqH samples were collected at the beginning of surgery. The levels of cytokines (interleukins [ILs]-1α, -1β, -4, -6, -8, -10, -12p70, -13, -17A, interferon [IFN]-α, IFN-γ, monocyte chemotactic protein [MCP]-1, E-selectin, P-selectin, and soluble intercellular adhesion molecule-1 [sICAM-1]) in the AqH were measured using multiplex beads immunoassay. We evaluated the correlation among AqH cytokine levels, CCT, CCV_4mm, and CCV_6mm in eyes with bullous keratopathy.

RESULTS

The levels of protein, ILs-4, -6, -8, -10, -12p70, and -17A, MCP-1, IFN-γ, E-selectin, P-selectin, and sICAM-1 were significantly higher in eyes with bullous keratopathy compared with those of the normal control subjects (all P < .0025). CCT was significantly correlated with the levels of IL-13 (r = 0.551, P = .0009) and sICAM-1 (r = 0.448, P = .0005). CCV_4mm was significantly correlated with the levels of IL-13 (r = 0.514, P = .0022) and sICAM-1 (r = 0.404, P = .0019). CCV_6mm was significantly correlated with the level of sICAM-1 (r = 0.459, P = .0003).

CONCLUSION

The severity of corneal edema in eyes with bullous keratopathy was associated with the levels of specific cytokines in the AqH.

Adipose stem cells and their paracrine factors are therapeutic for early retinal complications of diabetes in the Ins2Akita mouse

BACKGROUND

Early-stage diabetic retinopathy (DR) is characterized by neurovascular defects. In this study, we hypothesized that human adipose-derived stem cells (ASCs) positive for the pericyte marker CD140b, or their secreted paracrine factors, therapeutically rescue early-stage DR features in an Ins2Akita mouse model.

METHODS

Ins2Akita mice at 24 weeks of age received intravitreal injections of CD140b-positive ASCs (1000 cells/1 μL) or 20× conditioned media from cytokine-primed ASCs (ASC-CM, 1 μL). Age-matched wildtype mice that received saline served as controls. Visual function experiments and histological analyses were performed 3 weeks post intravitreal injection. Biochemical and molecular analyses assessed the ASC-CM composition and its biological effects.

RESULTS

Three weeks post-injection, Ins2Akita mice that received ASCs had ameliorated decreased b-wave amplitudes and vascular leakage but failed to improve visual acuity, whereas Ins2Akita mice that received ASC-CM demonstrated amelioration of all aforementioned visual deficits. The ASC-CM group demonstrated partial amelioration of retinal GFAP immunoreactivity and DR-related gene expression but the ASC group did not. While Ins2Akita mice that received ASCs exhibited occasional (1 in 8) hemorrhagic retinas, mice that received ASC-CM had no adverse complications. In vitro, ASC-CM protected against TNFα-induced retinal endothelial permeability as measured by transendothelial electrical resistance. Biochemical and molecular analyses demonstrated several anti-inflammatory proteins including TSG-6 being highly expressed in cytokine-primed ASC-CM.

CONCLUSIONS

ASCs or their secreted factors mitigate retinal complications of diabetes in the Ins2Akita model. Further investigation is warranted to determine whether ASCs or their secreted factors are safe and effective therapeutic modalities long-term as current locally delivered therapies fail to effectively mitigate the progression of early-stage DR. Nonetheless, our study sheds new light on the therapeutic mechanisms of adult stem cells, with implications for assessing relative risks/benefits of experimental regenerative therapies for vision loss.

The Role of Pneumococcal Virulence Factors in Ocular Infectious Diseases

Streptococcus pneumoniae is a gram-positive, facultatively anaerobic pathogen that can cause severe infections such as pneumonia, meningitis, septicemia, and middle ear infections. It is also one of the top pathogens contributing to bacterial keratitis and conjunctivitis. Though two pneumococcal vaccines exist for the prevention of nonocular diseases, they do little to fully prevent ocular infections. This pathogen has several virulence factors that wreak havoc on the conjunctiva, cornea, and intraocular system. Polysaccharide capsule aids in the evasion of host complement system. Pneumolysin (PLY) is a cholesterol-dependent cytolysin that acts as pore-forming toxin. Neuraminidases assist in adherence and colonization by exposing cell surface receptors to the pneumococcus. Zinc metalloproteinases contribute to evasion of the immune system and disease severity. The main purpose of this review is to consolidate the multiple studies that have been conducted on several pneumococcal virulence factors and the role each plays in conjunctivitis, keratitis, and endophthalmitis.

Essential role of ultraviolet radiation in the decrease of corneal endothelial cell density caused by pterygium

PURPOSE

To investigate the essential role of ultraviolet (UV) radiation in the decrease of corneal endothelial cell density (ECD) caused by pterygium.

METHODS

In this retrospective controlled study, 76 consecutive patients with unilateral primary pterygium were enrolled from January 2016 to August 2016. The Central corneal ECD was measured in both eyes. Divide the subjects into two subgroups according to the UV exposure time, and the difference of corneal ECD between both eyes was analyzed using independent samples t-test. The relationship between the percentage of difference of corneal ECD and the disease duration, the percentage of pterygium to the cornea and the astigmatism value were analyzed.

RESULTS

For subjects with longer UV exposure, the average of ECD in pterygium group and control group were, respectively, 2264.83 ± 349.78 cells/mm² and 2477.16 ± 300.36 cells/mm² (P = 0.004). For subjects with short UV exposure, the average of ECD in pterygium group and control group were, respectively, 2596.46 ± 373.24 cells/mm² and 2690.66 ± 321.34 cells/mm² (P = 0.262). The decrease of corneal ECD was positively correlated with the period of the disease (P = 0.035). There was no statistical correlation between a decrease in the corneal ECD and the percentage of pterygium to cornea (R = -0.055, P = 0.635) and the astigmatism value in the pterygium eye (R = -0.135, P = 0.246).

CONCLUSIONS

UV radiation exposure played a significant role in the effect of pterygium decreasing the corneal ECD.

Critical role of endoplasmic reticulum stress in chronic endothelial activation-induced visual deficits in tie2-tumor necrosis factor mice

Diabetic retinopathy (DR) is the leading cause of vision loss among working-age adults. The interplay between hyperglycemia and endothelial activation in inducing endoplasmic reticulum (ER) stress pathways and visual deficits in DR is not fully understood. To address this, we used a mouse model of chronic vascular activation using endothelial-specific tumor necrosis factor-α (TNF-α)-expressing (tie2-TNF) mice to induce diabetes with streptozotocin. At 4 weeks post streptozotocin, a significant 2-fold to 10-fold increase in retinal neurovascular inflammatory gene transcript response in tie2-TNF mice was further increased in diabetic tie2-TNF mice. A decrease in visual acuity and scotopic b-wave amplitude in tie2-TNF mice was further accentuated in diabetic tie2-TNF mice and these changes correlated with a multi-fold increase in retinal ER stress markers and a reduction in adherens junctions. Cultured retinal endothelial cells showed a significant decrease in trans-endothelial resistance as well as VE-cadherin expression under TNF-α and high glucose stress. These changes were partly rescued by tauroursodeoxycholic acid, a potent ER stress inhibitor. Taken together, constant endothelial activation induced by TNF-α further exacerbated by hyperglycemia results in activation of ER stress and chronic proinflammation in a feed forward loop ultimately resulting in endothelial junction protein alterations leading to visual deficits in the retina. Inhibition of ER stress and endothelial activation may prove to be a novel therapeutic target in DR.

Concentrated Conditioned Media from Adipose Tissue Derived Mesenchymal Stem Cells Mitigates Visual Deficits and Retinal Inflammation Following Mild Traumatic Brain Injury

Blast concussions are a common injury sustained in military combat today. Inflammation due to microglial polarization can drive the development of visual defects following blast injuries. In this study, we assessed whether anti-inflammatory factors released by the mesenchymal stem cells derived from adipose tissue (adipose stem cells, ASC) can limit retinal tissue damage and improve visual function in a mouse model of visual deficits following mild traumatic brain injury. We show that intravitreal injection of 1 μL of ASC concentrated conditioned medium from cells pre-stimulated with inflammatory cytokines (ASC-CCM) mitigates loss of visual acuity and contrast sensitivity four weeks post blast injury. Moreover, blast mice showed increased retinal expression of genes associated with microglial activation and inflammation by molecular analyses, retinal glial fibrillary acidic protein (GFAP) immunoreactivity, and increased loss of ganglion cells. Interestingly, blast mice that received ASC-CCM improved in all parameters above. In vitro, ASC-CCM not only suppressed microglial activation but also protected against Tumor necrosis alpha (TNFα) induced endothelial permeability as measured by transendothelial electrical resistance. Biochemical and molecular analyses demonstrate TSG-6 is highly expressed in ASC-CCM from cells pre-stimulated with TNFα and IFNγ but not from unstimulated cells. Our findings suggest that ASC-CCM mitigates visual deficits of the blast injury through their anti-inflammatory properties on activated pro-inflammatory microglia and endothelial cells. A regenerative therapy for immediate delivery at the time of injury may provide a practical and cost-effective solution against the traumatic effects of blast injuries to the retina.

The role of tight junction proteins in ovarian follicular development and ovarian cancer

Tight junctions (TJ) are protein structures that control the transport of water, ions and macromolecules across cell layers. Functions of the transmembrane TJ protein, occluding (OCLN) and the cytoplasmic TJ proteins, tight junction protein 1 (TJP1; also known as zona occludens protein-1), cingulin (CGN) and claudins (CLDN) are reviewed, and current evidence of their role in the ovarian function is reviewed. Abundance of OCLN, CLDNs and TJP1 mRNA changed during follicular growth. In vitro treatment with various growth factors known to affect ovarian folliculogenesis indicated that CGN, OCLN and TJP1 are hormonally regulated. The summarized studies indicate that expression of TJ proteins (i.e., OCLN, CLDN, TJP1 and CGN) changes with follicle size in a variety of vertebrate species but whether these changes in TJ proteins are increased or decreased depends on species and cell type. Evidence indicates that autocrine, paracrine and endocrine regulators, such as fibroblast growth factor-9, epidermal growth factor, androgens, tumor necrosis factor-α and glucocorticoids may modulate these TJ proteins. Additional evidence presented indicates that TJ proteins may be involved in ovarian cancer development in addition to normal follicular and luteal development. A model is proposed suggesting that hormonal downregulation of TJ proteins during ovarian follicular development could reduce barrier function (i.e., selective permeability of molecules between theca and granulosa cells) and allow for an increase in the volume of follicular fluid as well as allow additional serum factors into the follicle that may directly impact granulosa cell functions.

Basic Components of Vascular Connective Tissue and Extracellular Matrix

Though the composition of the three layers constituting the blood vessel wall varies among the different types of blood vessels, and some layers may even be missing in capillaries, certain basic components, and properties are shared by all blood vessels, though each histologically distinct layer contains a unique complement of extracellular components, growth factors and cytokines, and cell types as well. The structure and composition of vessel layers informs and is informed by the function of the particular blood vessel. The adaptation of the composition and the resulting function of the extracellular matrix (ECM) to changes in circulation/blood flow and a variety of other extravascular stimuli can be characterized as remodeling spearheaded by vascular cells. There is a surprising amount of cell traffic among the three layers. It starts with endothelial cell mediated transmigration of inflammatory cells from the bloodstream into the subendothelium, and then into tissue adjoining the blood vessel. Smooth muscle cells and a variety of adventitial cells reside in tunica media and tunica externa, respectively. The latter cells are a mixture of progenitor/stem cells, fibroblasts, myofibroblasts, pericytes, macrophages, and dendritic cells and respond to endothelial injury by transdifferentiation as they travel into the two inner layers, intima and media for corrective mission in the ECM composition. This chapter addresses the role of various vascular cell types and ECM components synthesized by them in maintenance of normal structure and in their contribution to major pathological processes, such as atherosclerosis, organ fibrosis, and diabetic retinopathy.

Therapeutic potential of AAV-mediated MMP-3 secretion from corneal endothelium in treating glaucoma

Intraocular pressure (IOP) is maintained as a result of the balance between production of aqueous humour (AH) by the ciliary processes and hydrodynamic resistance to its outflow through the conventional outflow pathway comprising the trabecular meshwork (TM) and Schlemm's canal (SC). Elevated IOP, which can be caused by increased resistance to AH outflow, is a major risk factor for open-angle glaucoma. Matrix metalloproteinases (MMPs) contribute to conventional aqueous outflow homeostasis in their capacity to remodel extracellular matrices, which has a direct impact on aqueous outflow resistance and IOP. We observed decreased MMP-3 activity in human glaucomatous AH compared to age-matched normotensive control AH. Treatment with glaucomatous AH resulted in significantly increased transendothelial resistance of SC endothelial and TM cell monolayers and reduced monolayer permeability when compared to control AH, or supplemented treatment with exogenous MMP-3.Intracameral inoculation of AAV-2/9 containing a CMV-driven MMP-3 gene (AAV-MMP-3) into wild type mice resulted in efficient transduction of corneal endothelium and an increase in aqueous concentration and activity of MMP-3. Most importantly, AAV-mediated expression of MMP-3 increased outflow facility and decreased IOP, and controlled expression using an inducible promoter activated by topical administration of doxycycline achieved the same effect. Ultrastructural analysis of MMP-3 treated matrices by transmission electron microscopy revealed remodelling and degradation of core extracellular matrix components. These results indicate that periodic induction, via use of an eye drop, of AAV-mediated secretion of MMP-3 into AH could have therapeutic potential for those cases of glaucoma that are sub-optimally responsive to conventional pressure-reducing medications.

Endothelial Response to Glucocorticoids in Inflammatory Diseases

The endothelium plays a crucial role in inflammation. A balanced control of inflammation requires the action of glucocorticoids (GCs), steroidal hormones with potent cell-specific anti-inflammatory properties. Besides the classic anti-inflammatory effects of GCs on leukocytes, recent studies confirm that endothelial cells also represent an important target for GCs. GCs regulate different aspects of endothelial physiology including expression of adhesion molecules, production of pro-inflammatory cytokines and chemokines, and maintenance of endothelial barrier integrity. However, the regulation of endothelial GC sensitivity remains incompletely understood. In this review, we specifically examine the endothelial response to GCs in various inflammatory diseases ranging from multiple sclerosis, stroke, sepsis, and vasculitis to atherosclerosis. Shedding more light on the cross talk between GCs and endothelium will help to improve existing therapeutic strategies and develop new therapies better tailored to the needs of patients.

Biomechanical relationships between the corneal endothelium and Descemet's membrane

The posterior face of the cornea consists of the corneal endothelium, a monolayer of cuboidal cells that secrete and attach to Descemet's membrane, an exaggerated basement membrane. Dysfunction of the endothelium compromises the barrier and pump functions of this layer that maintain corneal deturgesence. A large number of corneal endothelial dystrophies feature irregularities in Descemet's membrane, suggesting that cells create and respond to the biophysical signals offered by their underlying matrix. This review provides an overview of the bidirectional relationship between Descemet's membrane and the corneal endothelium. Several experimental methods have characterized a richly topographic and compliant biophysical microenvironment presented by the posterior surface of Descemet's membrane, as well as the ultrastructure and composition of the membrane as it builds during a lifetime. We highlight the signaling pathways involved in the mechanotransduction of biophysical cues that influence cell behavior. We present the specific example of Fuchs' corneal endothelial dystrophy as a condition in which a dysregulated Descemet's membrane may influence the progression of disease. Finally, we discuss some disease models and regenerative strategies that may facilitate improved treatments for corneal dystrophies.

Morin Attenuates Ovalbumin-Induced Airway Inflammation by Modulating Oxidative Stress-Responsive MAPK Signaling

Asthma is one of the most common inflammatory diseases characterized by airway hyperresponsiveness, inflammation, and remodeling. Morin, an active ingredient obtained from Moraceae plants, has been demonstrated to have promising anti-inflammatory activities in a range of disorders. However, its impacts on pulmonary diseases, particularly on asthma, have not been clarified. This study was designed to investigate whether morin alleviates airway inflammation in chronic asthma with an emphasis on oxidative stress modulation. In vivo, ovalbumin- (OVA-) sensitized mice were administered with morin or dexamethasone before challenge. Bronchoalveolar lavage fluid (BALF) and lung tissues were obtained to perform cell counts, histological analysis, and enzyme-linked immunosorbent assay. In vitro, human bronchial epithelial cells (BECs) were challenged by tumor necrosis factor alpha (TNF-α). The supernatant was collected for the detection of the proinflammatory proteins, and the cells were collected for reactive oxygen species (ROS)/mitogen-activated protein kinase (MAPK) evaluations. Severe inflammatory responses and remodeling were observed in the airways of the OVA-sensitized mice. Treatment with morin dramatically attenuated the extensive trafficking of inflammatory cells into the BALF and inhibited their infiltration around the respiratory tracts and vessels. Morin administration also significantly suppressed goblet cell hyperplasia and collagen deposition/fibrosis and dose-dependently inhibited the OVA-induced increases in IgE, TNF-α, interleukin- (IL-) 4, IL-13, matrix metalloproteinase-9, and malondialdehyde. In human BECs challenged by TNF-α, the levels of proteins such as eotaxin-1, monocyte chemoattractant protein-1, IL-8 and intercellular adhesion molecule-1, were consistently significantly decreased by morin. Western blotting and the 2',7'-dichlorofluorescein assay revealed that the increases in intracellular ROS and MAPK phosphorylation were abolished by morin, implying that ROS/MAPK signaling contributes to the relief of airway inflammation. Our findings indicate for the first time that morin alleviates airway inflammation in chronic asthma, which probably occurs via the oxidative stress-responsive MAPK pathway, highlighting a novel profile of morin as a potent agent for asthma management.

Therapeutic benefits of young, but not old, adipose-derived mesenchymal stem cells in a chronic mouse model of bleomycin-induced pulmonary fibrosis

The observation that pulmonary inflammatory lesions and bleomycin (BLM)-induced pulmonary fibrosis spontaneously resolve in young mice, whereas remaining irreversible in aged mice suggests that impairment of pulmonary regeneration and repair is associated with aging. Because mesenchymal stem cells (MSCs) may promote repair after injury, we postulated that differences in MSCs from aged mice may underlie postinjury fibrosis in aging. The potential for young-donor MSCs to inhibit BLM-induced pulmonary fibrosis in aged male mice (>22 months) has not been studied. Adipose-derived MSCs (ASCs) from young (4 months) and old (22 months) male mice were infused 1 day after intratracheal BLM administration. At 21-day sacrifice, aged BLM mice demonstrated lung fibrosis by Ashcroft score, collagen content, and α(v)-integrin messenger RNA (mRNA) expression. Lung tissue from aged BLM mice receiving young ASCs exhibited decreased fibrosis, matrix metalloproteinase (MMP)-2 activity, oxidative stress, and markers of apoptosis vs BLM controls. Lung mRNA expression of tumor necrosis factor-alpha was also decreased in aged BLM mice receiving young-donor ASCs vs BLM controls. In contrast, old-donor ASC treatment in aged BLM mice did not reduce fibrosis and related markers. On examination of the cells, young-donor ASCs had decreased mRNA expression of MMP-2, insulin-like growth factor (IGF) receptor, and protein kinase B (AKT) activation compared with old-donor ASCs. These results show that the BLM-induced pulmonary fibrosis in aged mice could be blocked by young-donor ASCs and that the mechanisms involve changes in collagen turnover and markers of inflammation.

Semaphorin7A Promotion of Tumoral Growth and Metastasis in Human Oral Cancer by Regulation of G1 Cell Cycle and Matrix Metalloproteases: Possible Contribution to Tumoral Angiogenesis

Background

Semaphorins (SEMAs) consist of a large family of secreted and membrane-anchored proteins that are important in neuronal pathfinding and axon guidance in selected areas of the developing nervous system. Of them, SEMA7A has been reported to have a chemotactic activity in neurogenesis and to be an immunomodulator; however, little is known about the relevance of SEMA7A in the behaviors of oral squamous cell carcinoma (OSCC).

Methods

We evaluated SEMA7A expression in OSCC-derived cell lines and primary OSCC samples using quantitative reverse transcriptase-polymerase chain reaction, immunoblotting, and semiquantitative immunohistochemistry (sq-IHC). In addition, SEMA7A knockdown cells (shSEMA7A cells) were used for functional experiments, including cellular proliferation, invasiveness, and migration assays. We also analyzed the clinical correlation between SEMA7A status and clinical behaviors in patients with OSCC.

Results

SEMA7A mRNA and protein were up-regulated significantly (P<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. The shSEMA7A cells showed decreased cellular growth by cell-cycle arrest at the G1 phase, resulting from up-regulation of cyclin-dependent kinase inhibitors (p21^Cip1 and p27^Kip1) and down-regulation of cyclins (cyclin D1, cyclin E) and cyclin-dependent kinases (CDK2, CDK4, and CDK6); and decreased invasiveness and migration activities by reduced secretion of matrix metalloproteases (MMPs) (MMP-2, proMMP-2, pro-MMP-9), and expression of membrane type 1- MMP (MT1-MMP). We also found inactivation of the extracellular regulated kinase 1/2 and AKT pathways, an upstream molecule of cell-cycle arrest at the G1 phase, and reduced secretion of MMPs in shSEMA7A cells. sq-IHC showed that SEMA7A expression in the primary OSCCs was significantly (P = 0.001) greater than that in normal counterparts and was correlated with primary tumoral size (P = 0.0254) and regional lymph node metastasis (P = 0.0002).

Conclusion

Our data provide evidence for an essential role of SEMA7A in tumoral growth and metastasis in OSCC and indicated that SEMA7A may play a potential diagnostic/therapeutic target for use in patients with OSCC.

Endothelial to Mesenchymal Transition Contributes to Endothelial Dysfunction in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by lung endothelial cell dysfunction and vascular remodeling. Normally, the endothelium forms an integral cellular barrier to regulate vascular homeostasis. During embryogenesis endothelial cells exhibit substantial plasticity that contribute to cardiac development by undergoing endothelial-to-mesenchymal transition (EndoMT). We determined the presence of EndoMT in the pulmonary vasculature in vivo and the functional effects on pulmonary artery endothelial cells (PAECs) undergoing EndoMT in vitro. Histologic assessment of patients with systemic sclerosis-associated PAH and the hypoxia/SU5416 mouse model identified the presence von Willebrand factor/α-smooth muscle actin-positive endothelial cells in up to 5% of pulmonary vessels. Induced EndoMT in PAECs by inflammatory cytokines IL-1β, tumor necrosis factor α, and transforming growth factor β led to actin cytoskeleton reorganization and the development of a mesenchymal morphology. Induced EndoMT cells exhibited up-regulation of mesenchymal markers, including collagen type I and α-smooth muscle actin, and a reduction in endothelial cell and junctional proteins, including von Willebrand factor, CD31, occludin, and vascular endothelial-cadherin. Induced EndoMT monolayers failed to form viable biological barriers and induced enhanced leak in co-culture with PAECs. Induced EndoMT cells secreted significantly elevated proinflammatory cytokines, including IL-6, IL-8, and tumor necrosis factor α, and supported higher immune transendothelial migration compared with PAECs. These findings suggest that EndoMT may contribute to the development of PAH.

The role of tight junctions in cancer metastasis

Over the last decade, it has become apparent that the tight junction (TJ) is a key component in tumour progression and metastasis. In addition to its role in the control of paracellular diffusion of ions and certain molecules, the TJ has a vital role in maintaining cell to cell adhesion and tissue integrity. Changes in the expression and/or distribution of TJ proteins can result in loss in cohesion of the TJ structure, which in turn results in the ability of cancer cells to become invasive and then ultimately lead to the metastasis of cancer cells. This review will discuss recent insights into how TJ are involved in the process of tumour metastasis.