Tryptase compromises corneal epithelial barrier function

Tryptase and Exogenous Trypsin: Mechanisms and Ophthalmic Applications

Ocular injuries caused by inflammation, surgery or accidents are subject to a physiological healing process that ultimately restores the structure and function of the damaged tissue. Tryptase and trypsin are essential component of this process and they play a role in promoting and reducing the inflammatory response of tissues, respectively. Following injury, tryptase is endogenously produced by mast cells and can exacerbate the inflammatory response both by stimulating neutrophil secretion, and through its agonist action on proteinase-activated receptor 2 (PAR2). In contrast, exogenously introduced trypsin promotes wound healing by attenuating inflammatory responses, reducing oedema and protecting against infection. Thus, trypsin may help resolve ocular inflammatory symptoms and promote faster recovery from acute tissue injury associated with ophthalmic diseases. This article describes the roles of tryptase and exogenous trypsin in affected tissues after onset of ocular injury, and the clinical applications of trypsin injection.

Proteases and Their Potential Role as Biomarkers and Drug Targets in Dry Eye Disease and Ocular Surface Dysfunction

Dry eye disease (DED) is a multifactorial disorder that leads to ocular discomfort, visual disturbance, and tear film instability. DED is accompanied by an increase in tear osmolarity and ocular surface inflammation. The diagnosis and treatment of DED still present significant challenges. Therefore, novel biomarkers and treatments are of great interest. Proteases are present in different tissues on the ocular surface. In a healthy eye, proteases are highly regulated. However, dysregulation occurs in various pathologies, including DED. With this review, we provide an overview of the implications of different families of proteases in the development and severity of DED, along with studies involving protease inhibitors as potential therapeutic tools. Even though further research is needed, this review aims to give suggestions for identifying novel biomarkers and developing new protease inhibitors.

Mast cell tryptase enhances wound healing by promoting migration in human bronchial epithelial cells

Epithelial damage and increase of intraepithelial mast cells (MC) are characteristics of asthma. The role of MC mediator tryptase and the protease-activated receptor-2 (PAR2) on epithelial wound healing is not fully investigated. Stimulation of bronchial epithelial cells (BECs) with tryptase promoted gap closure, migration and cellular speed compared to controls. Stimulated BECs had higher expression of migration marker CD151 compared to controls. Proliferation marker KI67 was upregulated in tryptase-stimulated BECs compared to controls. Treatment with PAR2 antagonist I-191 reduced gap closure, migration and cell speed compared to BECs stimulated with tryptase. We found that tryptase enhances epithelial wound healing by increased migration and proliferation, which is in part regulated via PAR2. Our data suggest that tryptase might be beneficial in tissue repair under baseline conditions. However, in a pathological context such as asthma with increased numbers of activated MCs, it might lead to epithelial remodeling and loss of function.

Mast Cell Proteases Tryptase and Chymase Induce Migratory and Morphological Alterations in Bronchial Epithelial Cells

Chronic respiratory diseases are often characterized by impaired epithelial function and remodeling. Mast cells (MCs) are known to home into the epithelium in respiratory diseases, but the MC-epithelial interactions remain less understood. Therefore, this study aimed to investigate the effect of MC proteases on bronchial epithelial morphology and function. Bronchial epithelial cells were stimulated with MC tryptase and/or chymase. Morphology and epithelial function were performed using cell tracking analysis and holographic live-cell imaging. Samples were also analyzed for motility-associated gene expression. Immunocytochemistry was performed to compare cytoskeletal arrangement. Stimulated cells showed strong alterations on gene, protein and functional levels in several parameters important for maintaining epithelial function. The most significant increases were found in cell motility, cellular speed and cell elongation compared to non-stimulated cells. Also, cell morphology was significantly altered in chymase treated compared to non-stimulated cells. In the current study, we show that MC proteases can induce cell migration and morphological and proliferative alterations in epithelial cells. Thus, our data imply that MC release of proteases may play a critical role in airway epithelial remodeling and disruption of epithelial function.

A novel serine protease inhibitor as potential treatment for dry eye syndrome and ocular inflammation

Dry eye syndrome (DES), a multifactorial disorder which leads to ocular discomfort, visual disturbance and tear film instability, has a rising prevalence and limited treatment options. In this study, a newly developed trypsin-like serine protease inhibitor (UAMC-00050) in a tear drop formulation was evaluated to treat ocular inflammation. A surgical animal model of dry eye was employed to investigate the potential of UAMC-00050 on dry eye pathology. Animals treated with UAMC-00050 displayed a significant reduction in ocular surface damage after evaluation with sodium fluorescein, compared to untreated, vehicle treated and cyclosporine-treated animals. The concentrations of IL-1α and TNF-α were also significantly reduced in tear fluid from UAMC-00050-treated rats. Additionally, inflammatory cell infiltration in the palpebral conjunctiva (CD3 and CD45), was substantially reduced. An accumulation of pro-MMP-9 and a decrease in active MMP-9 were found in tear fluid from animals treated with UAMC-00050, suggesting that trypsin-like serine proteases play a role in activating MMP-9 in ocular inflammation in this animal model. Comparative qRT-PCR analyses on ocular tissue indicated the upregulation of tryptase, urokinase plasminogen activator receptor (uPAR) and protease-activated receptor 2 (PAR2). The developed UAMC-00050 formulation was stable up to 6 months at room temperature in the absence of light, non-irritating and sterile with compatible pH and osmolarity. These results provide a proof-of-concept for the in vivo modifying potential of UAMC-00050 on dry eye pathology and suggest a central role of trypsin-like serine proteases and PAR2 in dry eye derived ocular inflammation.

The emerging role of mast cell proteases in asthma

It is now well established that mast cells (MCs) play a crucial role in asthma. This is supported by multiple lines of evidence, including both clinical studies and studies on MC-deficient mice. However, there is still only limited knowledge of the exact effector mechanism(s) by which MCs influence asthma pathology. MCs contain large amounts of secretory granules, which are filled with a variety of bioactive compounds including histamine, cytokines, lysosomal hydrolases, serglycin proteoglycans and a number of MC-restricted proteases. When MCs are activated, e.g. in response to IgE receptor cross-linking, the contents of their granules are released to the exterior and can cause a massive inflammatory reaction. The MC-restricted proteases include tryptases, chymases and carboxypeptidase A3, and these are expressed and stored at remarkably high levels. There is now emerging evidence supporting a prominent role of these enzymes in the pathology of asthma. Interestingly, however, the role of the MC-restricted proteases is multifaceted, encompassing both protective and detrimental activities. Here, the current knowledge of how the MC-restricted proteases impact on asthma is reviewed.

Proteinase-activated receptor-2 enhances Bcl2-like protein-12 expression in lung cancer cells to suppress p53 expression

INTRODUCTION

The pathogenesis of lung cancer is unclear. Less expression of p53 or p53 mutation was identified in lung cancer cells, which plays a role in the development of lung cancer. Recent reports indicate that Bcl2-like protein-12 (Bcl2L12) can inhibit the expression of p53. Lung cancer cells express proteinase-activated receptor-2 (PAR2). This study tests the hypothesis that activation of PAR2 inhibits the expression of p53 in lung cancer cells.

MATERIAL AND METHODS

Lung cancer cells were collected from patients with non-small cell lung cancer (NSCLC). The cells were exposed to active peptides or trypsin in the culture for 48 h. The expression of p53 was assessed by RT-qPCR and Western blotting.

RESULTS

We observed that lung cancer cells express Bcl2L12. Activation of PAR2 increases expression of Bcl2L12 in lung cancer cells. Bcl2L12 mediates PAR2-suppressed p53 expression in lung cancer cells. IgE-activated mast cell suppression of p53 expression in lung cancer cells can be prevented by knocking down Bcl2L12. The Bcl2L12 bound Mdm2, the transcription factor of p53, to prevent the Mdm2 from binding to the promoter of p53 and thus inhibited p53 expression in lung cancer cells. PAR2 could attenuate lung cancer cell apoptosis via inducing Bcl2L12.

CONCLUSIONS

Lung cancer cells express Bcl2L12, which mediates the effects of activation of PAR2 on suppressing the expression of p53 in lung cancer cells, implying that Bcl2L12 may be a novel therapeutic target for the treatment of lung cancer.

Pyroptosis engagement and bladder urothelial cell-derived exosomes recruit mast cells and induce barrier dysfunction of bladder urothelium after uropathogenic E. coli infection

The specific regulatory mechanism of bladder urothelial barrier dysfunction after infection with uropathogenic Escherichia coli (UPEC) is still unclear. The cross talk between bladder urothelial cells and mast cells may play an important role during UPEC infection. In this study, the pyroptosis of urothelial cells was investigated after UPEC infection both in vivo and in vitro. The levels of IL-1β and IL-18 in exosomes derived from bladder urothelial cells after UPEC infection were detected. The role of these processes in the recruitment and activation of mast cells was measured. The mechanism of mast cell-induced disruption of bladder epithelial barrier function was also assessed. We found that UPEC infection induced pyroptosis of bladder urothelial cells and led to the release of IL-1β and IL-18 in the form of exosomes, which promoted the migration of mast cells. Tryptase secreted by mast cells aggravated the damage to the barrier function of the bladder urothelium by acting on protease-activated receptor 2 (PAR2). Inhibition of pyroptosis or the tryptase-PAR2 axis reduced the disruption of bladder urothelial barrier function and decreased the bacterial burden. The present study supports a novel mechanism by which pyroptosis-dependent release of exosomes from bladder urothelial cells activates mast cells and regulates bladder urothelial barrier function during UPEC infection.

MMP-9 Downregulation with Lipid Nanoparticles for Inhibiting Corneal Neovascularization by Gene Silencing

Gene silencing targeting proangiogenic factors have been shown to be a useful strategy in the treatment of corneal neovascularization (CNV). Among interference RNA (RNAi) molecules, short-hairpin RNA (shRNA) is a plasmid-coded RNA able to down-regulate the expression of the desired gene. It is continuously produced in the host cell, inducing a durable gene silencing effect. The aim of this work was to develop a solid lipid nanoparticle (SLN)-based shRNA delivery system to downregulate metalloproteinase 9 (MMP-9), a proangiogenic factor, in corneal cells for the treatment of CNV associated with inflammation. The nanovectors were prepared using a solvent emulsification-evaporation technique, and after physicochemical evaluation, they were evaluated in different culture cell models. Transfection efficacy, cell internalization, cell viability, the effect on MMP-9 expression, and cell migration were evaluated in human corneal epithelial cells (HCE-2). The inhibition of tube formation using human umbilical vein endothelial cells (HUVEC) was also assayed. The non-viral vectors based on SLN were able to downregulate the MMP-9 expression in HCE-2 cells via gene silencing, and, consequently, to inhibit cell migration and tube formation. These results demonstrate the potential of lipid nanoparticles as gene delivery systems for the treatment of CNV-associated inflammation by RNAi technology.

Targeting corneal inflammation by gene therapy: Emerging strategies for keratitis

Inflammation is the underlying process of several diseases within the eye, specifically in the cornea. Current treatment options for corneal inflammation or keratitis, and related neovascularization, are restricted by limited efficacy, adverse effects, and short duration of action. Gene therapy has shown great potential for the treatment of diseases affecting the ocular surface, and major efforts are being targeted to inflammatory mediators and neovascularization, in order to develop potential treatments for corneal inflammation. Gene therapy to treat ocular disorders is still starting, and current therapies are primarily experimental, with most human clinical trials still in research state, although some of them have already shown encouraging results. In this review, we focus on the progress and challenges of gene therapy to treat corneal inflammation. After introducing the inflammation process, we present the main nucleic acid delivery systems, including viral and non-viral vectors, and the most studied strategies to address the therapy: control of neovascularization and regulation of pro- and anti-inflammatory cytokines.

LRF inhibits p53 expression in colon cancer cells via modulating DAP5 activity

The p53 protein plays a critical role in suppression of tumour growth; its regulation is not fully understood. Leukaemia/lymphoma-related factor (LRF) promotes tumour cell growth. This study tests a hypothesis that LRF inhibits p53 expression in colon cancer cells. In this study, human colon cancer cell lines, LIM1215 and HCT116 cells, were used. The expression of LRF and p53 in the cells was analysed by quantitative reverse transcription polymerase chain reaction and Western blotting. We observed that the expression of protease-activated receptor 2 (PAR2) was detected in both LIM1215 and HCT116 human colon cancer cells. Activation of PAR2 increased the expression of LRF and inhibited the p53 expression in the cancer cells. We also detected a complex of LRF and DAP5, one of the p53 gene transcription factors. The interaction of LRF and DAP5 resulted in the repression of p53 expression in the colon cancer cells. In conclusion, PAR2 activation increases the expression of LRF in colon cancer cells, which interacts with DAP5 to repress the p53 expression. Leukaemia/lymphoma-related factor may be a novel target in the treatment of colon cancer.

Proteinase-Activated Receptor-2 Modulates Ve-Cadherin Expression to Affect Human Vascular Endothelial Barrier Function

Published data indicate that the protease-activated receptor (PAR) 2 is involved in the pathogenesis of some cardiovascular diseases; the underlying mechanism is to be further investigated. Ve-cadherin is a critical molecule in maintaining the endothelial barrier integrity. This study aims to investigate the role of PAR2 activation in compromising the cardiac endothelial barrier function. In this study, human umbilical vein endothelial cells (Huvec cells) were cultured into monolayers using as an in vitro model of barrier function. The transepithelial electric resistance (TER) and permeability to dextran were assessed as indicators of barrier function. The expression of Ve-cadherin in Huvec cells was assessed by real-time RT-PCR, Western blotting, and chromatin immunoprecipitation. The results showed that exposure to tryptase in the culture, the barrier function of the Huvec monolayers, was markedly compromised; the levels of Ve-cadherin, one of the tight junction proteins, were suppressed as well. This was mimicked by exposing Huvec monolayers to the active PAR2 peptides (PAR2AP). After exposing to PAR2AP, the levels of histone deacetylase (HDAC)11 were increased in the Huvec cells. HDAC11 formed a complex with the transcription factor of Ve-cadherin to attenuate the Erg gene transcription activities and suppressed the expression of Ve-cadherin. In conclusion, activation of PAR2 compromises the vascular endothelial barrier function by suppressing the expression of Ve-cadherin. J. Cell. Biochem. 118: 4587-4593, 2017. © 2017 Wiley Periodicals, Inc.

Abnormal interactions between perifollicular mast cells and CD8+ T-cells may contribute to the pathogenesis of alopecia areata

Alopecia areata (AA) is a CD8+ T-cell dependent autoimmune disease of the hair follicle (HF) in which the collapse of HF immune privilege (IP) plays a key role. Mast cells (MCs) are crucial immunomodulatory cells implicated in the regulation of T cell-dependent immunity, IP, and hair growth. Therefore, we explored the role of MCs in AA pathogenesis, focusing on MC interactions with CD8+ T-cells in vivo, in both human and mouse skin with AA lesions. Quantitative (immuno-)histomorphometry revealed that the number, degranulation and proliferation of perifollicular MCs are significantly increased in human AA lesions compared to healthy or non-lesional control skin, most prominently in subacute AA. In AA patients, perifollicular MCs showed decreased TGFβ1 and IL-10 but increased tryptase immunoreactivity, suggesting that MCs switch from an immuno-inhibitory to a pro-inflammatory phenotype. This concept was supported by a decreased number of IL-10+ and PD-L1+ MCs, while OX40L+, CD30L+, 4–1BBL+ or ICAM-1+ MCs were increased in AA. Lesional AA-HFs also displayed significantly more peri- and intrafollicular- CD8+ T-cells as well as more physical MC/CD8+ T-cell contacts than healthy or non-lesional human control skin. During the interaction with CD8+ T-cells, AA MCs prominently expressed MHC class I and OX40L, and sometimes 4–1BBL or ICAM-1, suggesting that MC may present autoantigens to CD8+ T-cells and/or co-stimulatory signals. Abnormal MC numbers, activities, and interactions with CD8+ T-cells were also seen in the grafted C3H/HeJ mouse model of AA and in a new humanized mouse model for AA. These phenomenological in vivo data suggest the novel AA pathobiology concept that perifollicular MCs are skewed towards pro-inflammatory activities that facilitate cross-talk with CD8+ T-cells in this disease, thus contributing to triggering HF-IP collapse in AA. If confirmed, MCs and their CD8+ T-cell interactions could become a promising new therapeutic target in the future management of AA.