Peptide GC31 inhibits chemokines and ICAM-1 expression in corneal fibroblasts exposed to LPS or poly(I:C) by blocking the NF-κB and MAPK pathways

Rose Bengal Photodynamic Therapy (RB-PDT) Modulates the Inflammatory Response in LPS-Stimulated Human Corneal Fibroblasts By Influencing NF-κB and p38 MAPK Signaling Pathways

PURPOSE

To investigate the effect of rose bengal photodynamic therapy on lipopolysaccharide-induced inflammation in human corneal fibroblasts. Furthermore, to analyze potential involvement of the mitogen-activated protein kinase and nuclear factor kappa B signaling pathways in this process.

METHODS

Human corneal fibroblast cultures underwent 0-2.0 µg/mL lipopolysaccharide treatment, and 24 h later rose bengal photodynamic therapy (0.001% RB, 565 nm wavelength illumination, 0.17 J/cm2 fluence). Interleukin-6, interleukin-8, intercellular adhesion molecule-1, interferon regulatory factor-3, interferon α2, and interferon β1 gene expressions were determined by quantitative PCR. Interleukin-6, interleukin-8, and C-C motif chemokine ligand-4 concentrations in the cell culture supernatant were measured by enzyme-linked immunosorbent assays and intercellular adhesion molecule-1 protein level in human corneal fibroblasts by western blot. In addition, the nuclear factor kappa B and mitogen-activated protein kinase signaling pathways were investigated by quantitative PCR and phosphorylation of nuclear factor kappa B p65 and p38 mitogen-activated protein kinase by western blot.

RESULTS

Rose bengal photodynamic therapy in 2.0 µg/mL lipopolysaccharide-stimulated human corneal fibroblasts triggered interleukin-6 and interleukin-8 mRNA (p < .0001) and interleukin-6 protein increase (p < .0001), and downregulated intercellular adhesion molecule-1 expression (p < .001). C-C motif chemokine ligand-4, interferon regulatory factor-3, interferon α2, and interferon β1 expressions remained unchanged (p ≥ .2). Rose bengal photodynamic therapy increased IκB kinase subunit beta, nuclear factor kappa B p65, extracellular signal-regulated kinases-2, c-Jun amino terminal kinase, and p38 transcription (p ≤ .01), and triggered nuclear factor kappa B p65 and p38 mitogen-activated protein kinase phosphorylation (p ≤ .04) in lipopolysaccharide treated human corneal fibroblasts.

CONCLUSION

Rose bengal photodynamic therapy of lipopolysaccharide-stimulated human corneal fibroblasts can modify the inflammatory response by inducing interleukin-6 and interleukin-8 expression, and decreasing intercellular adhesion molecule-1 production. C-C motif chemokine ligand-4, interferon regulatory factor-3, and interferon α and β expressions are not affected by rose bengal photodynamic therapy in these cells. The underlying mechanisms may be associated with nuclear factor kappa B and p38 mitogen-activated protein kinase pathway activation.

Thrombomodulin: a multifunctional receptor modulating the endothelial quiescence

Thrombomodulin (TM) is a type 1 receptor best known for its function as an anticoagulant cofactor for thrombin activation of protein C on the surface of vascular endothelial cells. In addition to its anticoagulant cofactor function, TM also regulates fibrinolysis, complement, and inflammatory pathways. TM is a multidomain receptor protein with a lectin-like domain at its N-terminus that has been shown to exhibit direct anti-inflammatory functions. This domain is followed by 6 epidermal growth factor-like domains that support the interaction of TM with thrombin. The interaction inhibits the procoagulant function of thrombin and enables the protease to regulate the anticoagulant and fibrinolytic pathways by activating protein C and thrombin-activatable fibrinolysis inhibitor. TM has a Thr/Ser-rich region immediately above the membrane surface that harbors chondroitin sulfate glycosaminoglycans, and this region is followed by a single-spanning transmembrane and a C-terminal cytoplasmic domain. The structure and physiological function of the extracellular domains of TM have been extensively studied, and numerous excellent review articles have been published. However, the physiological function of the cytoplasmic domain of TM has remained poorly understood. Recent data from our laboratory suggest that intracellular signaling by the cytoplasmic domain of TM plays key roles in maintaining quiescence by modulating phosphatase and tensin homolog signaling in endothelial cells. This article briefly reviews the structure and function of extracellular domains of TM and focuses on the mechanism and possible physiological importance of the cytoplasmic domain of TM in modulating phosphatase and tensin homolog signaling in endothelial cells.

CXCL16 exacerbates Pseudomonas aeruginosa keratitis by promoting neutrophil activation

Pseudomonas aeruginosa (PA) keratitis is a major cause of blindness characterized by corneal inflammation. In a murine model of PA keratitis, we assessed the detrimental effects of CXC chemokine ligand 16 (CXCL16). Quantitative PCR (qPCR), western blotting (WB) and immunofluorescence were used to measure the expression and localization of CXCL16 and its receptor, CXC chemokine receptor 6 (CXCR6). Clinical scores, plate counting, and hematoxylin-eosin staining were used to assess infection severity and its exacerbation by CXCL16. Immunofluorescence, myeloperoxidase assays, and flow cytometry were used to detect neutrophil activity and colocalization with CXCR6. WB and immunofluorescence were used to measure levels of reactive oxygen species (ROS) and matrix metalloproteinases (MMPs). These methods also were used to measure the activation of downstream NF-κB signaling and its positive feedback on CXCL16 expression. ELISA, flow cytometry, and qPCR were used to measure the expression of CXCL2 and T helper 17 (Th17) cell-related genes. CXCL16 and CXCR6 expression was increased in infected corneas. Topical application of CXCL16 exacerbated keratitis by increasing corneal bacterial load and promoting neutrophil infiltration, whereas neutralizing antibody against CXCL16 had the opposite effect. CXCL16 also increased ROS and MMP levels. This neutrophil activation may be caused by its positive feedback with the NF-κB pathway and the upregulation of CXCL2 and Th17 cell related-genes. These data suggest that CXCL16 is an attractive therapeutic target for PA keratitis.

Establishment and application of a high-throughput screening model for cell adhesion inhibitors

The cell adhesion between leukocytes and endothelial cells plays an important balanced role in the pathophysiological function, while excessive adhesion caused by etiological agents is associated with the occurrence and development of many acute and chronic diseases. Cell adhesion inhibitors have been shown to have a potential therapeutic effect on these diseases, therefore, efficient and specific inhibitors against cell adhesion are highly desirable. Here, using lipopolysaccharide-induced human umbilical vein endothelial cells (HUVECs) and calcein-AM-labeled human monocytic cell THP-1, we established a high-throughput screening model for cell adhesion inhibitors with excellent model evaluation parameters. Using the drug repurposing strategy, we screened out lifitegrast, a potent cell adhesion inhibitor, which inhibited cell adhesion between HUVEC and THP-1 cells by directly interrupting the adhesion interaction between HUVEC and THP-1 cells and showed a strong therapeutic effect on the mouse acute liver injury induced by poly (I:C)/D-GalN. Therefore, the screening model is suitable for screening and validating cell adhesion inhibitors, which will promote the research and development of inhibitors for the treatment of diseases caused by excessive cell adhesion.

Quercetin exerts anti-inflammatory effects via inhibiting tumor necrosis factor-α-induced matrix metalloproteinase-9 expression in normal human gastric epithelial cells

BACKGROUND

Gastric injury is the most common digestive system disease worldwide and involves inflammation, which can lead to gastric ulcer or gastric cancer (GC). Matrix metallopeptidase-9 [MMP-9 (gelatinase-B)] plays an important role in inflammation and GC progression. Quercetin and quercetin-rich diets represent potential food supplements and a source of medications for treating gastric injury given their anti-inflammatory activities. However, the effects and mechanisms of action of quercetin on human chronic gastritis and whether quercetin can relieve symptoms remain unclear.

AIM

To assess whether tumor necrosis factor-α (TNF-α)-induced MMP-9 expression mediates the anti-inflammatory effects of quercetin in normal human gastric mucosal epithelial cells.

METHODS

The normal human gastric mucosa epithelial cell line GES-1 was used to establish a normal human gastric epithelial cell model of TNF-α-induced MMP-9 protein overexpression to evaluate the anti-inflammatory effects of quercetin. The cell counting Kit-8 assay was used to evaluate the effects of varying quercetin doses on cell viability in the normal GES-1 cell line. Cell migration was measured using Transwell assay. The expression of proto-oncogene tyrosine-protein kinase Src (c-Src), phospho (p)-c-Src, extracellular-signal-regulated kinase 2 (ERK2), p-ERK1/2, c-Fos, p-c-Fos, nuclear factor kappa B (NF-κB/p65), and p-p65 and the effects of their inhibitors were examined using Western blot analysis and measurement of luciferase activity. p65 expression was detected by immunofluorescence. MMP-9 mRNA and protein levels were measured by quantitative reverse transcription polymerase chain reaction (qRT–PCR) and gelatin zymography, respectively.

RESULTS

qRT-PCR and gelatin zymography showed that TNF-α induced MMP-9 mRNA and protein expression in a dose- and time-dependent manner. These effects were reduced by the pretreatment of GES-1 cells with quercetin or a TNF-α antagonist (TNFR inhibitor) in a dose- and time-dependent manner. Quercetin and TNF-α antagonists decreased the TNF-α-induced phosphorylation of c-Src, ERK1/2, c-Fos, and p65 in a dose- and time-dependent manner. Quercetin, TNF-α antagonist, PP1, U0126, and tanshinone IIA (TSIIA) reduced TNF-α-induced c-Fos phosphorylation and AP-1–Luciferase (Luc) activity in a dose- and time-dependent manner. Pretreatment with quercetin, TNF-α antagonist, PP1, U0126, or Bay 11-7082 reduced TNF-α-induced p65 phosphorylation and translocation and p65–Luc activity in a dose- and time-dependent manner. TNF-α significantly increased GES-1 cell migration, and these results were reduced by pretreatment with quercetin or a TNF-α antagonist.

CONCLUSION

Quercetin significantly downregulates TNF-α-induced MMP-9 expression in GES-1 cells via the TNFR-c-Src–ERK1/2 and c-Fos or NF-κB pathways.

Inhibition of Gap Junction-Mediated Intercellular Communication by Poly(I:C) in Cultured Human Corneal Fibroblasts

PURPOSE/AIM

Corneal stromal fibroblasts are connected to each other via gap junctions, which contribute to maintenance of corneal homeostasis. Viral infection of the corneal stroma can result in inflammation and scarring. The effects of polyinosinic-polycytidylic acid [poly(I:C)], an analog of viral double-stranded RNA, on gap junctional intercellular communication (GJIC) in cultured human corneal fibroblasts (HCFs) were examined.

MATERIALS AND METHODS

Cultured HCFs were exposed to poly(I:C) in the absence or presence of inhibitors of mitogen-activated protein kinase (MAPK) signaling or the antioxidant N-acetyl-L-cysteine (NAC). Expression of the gap junction protein connexin 43 (Cx43) was examined by immunoblot and immunofluorescence analyses. The level of Cx43 mRNA or microRNA-21 or -130a was determined by quantitative reverse transcription-polymerase chain reaction analysis. GJIC was measured with a dye coupling assay. The amount of malondialdehyde and the activity of superoxide dismutase (SOD) were measured with assay kits.

RESULTS

Exposure of HCFs to poly(I:C) resulted in down-regulation of Cx43 expression and GJIC activity as well as in up-regulation of microRNA-21 expression. Poly(I:C) increased the amount of malondialdehyde and reduced the activity of SOD in the cells, and these effects were prevented by NAC. The inhibitory effects of poly(I:C) on both Cx43 expression and GJIC activity were attenuated by NAC and by c-Jun NH₂-terminal kinase (JNK) inhibitor II.

CONCLUSIONS

Poly(I:C) inhibited Cx43 expression and GJIC in cultured HCFs, possibly as a result of the associated up-regulation of microRNA-21. Poly(I:C) also increased oxidative stress in these cells, and such stress together with signaling by the MAPK JNK was implicated in the effects of poly(I:C) on Cx43 expression and GJIC activity. Down-regulation of GJIC activity among corneal fibroblasts by double-stranded RNA may thus contribute to the disruption of stromal homeostasis during viral infection of the cornea.

Cyclosporine A eyedrops with self-nanoemulsifying drug delivery systems have improved physicochemical properties and efficacy against dry eye disease in a murine dry eye model

PURPOSE

We aimed to compare the physicochemical properties and in vivo efficacy of commercially available nanoemulsion cyclosporine A (CsA) eyedrops in benzalkonium chloride (BAC)-induced dry eye disease (DED).

METHODS

Particle size analysis was performed on conventional 0.05% CsA (Restasis, C-CsA) and two new types of 0.05% CsA eyedrops based on a self-nanoemulsifying drug delivery system (SNEDDS, SNEDDS-N and -T). Turbidometry, pH measurements and instability indices of each CsA solution were measured. DED was induced with BAC, and animals were treated with vehicle or CsA preparations. Tear volume and fluorescein staining scores were evaluated on days 7 and 14. Eyes were enucleated and subjected to IHC, TUNEL staining, periodic acid-Schiff (PAS) staining, real-time PCR and western blotting.

RESULTS

Both SNEDDSs had lower and more uniform particle size distribution than C-CsA, and a similar optical density to phosphate-buffered saline and stable pH, in contrast to the high turbidity and unstable pH of C-CsA. Aqueous tear volume and fluorescein staining scores were improved in C-CsA- and SNEDDS-treated mice. Numbers of PAS-positive goblet cells and levels of inflammatory mediators were decreased by both C-CsA and SNEDDS, although SNEDDS resolved inflammation more effectively than C-CsA.

CONCLUSIONS

Cyclosporine A eyedrops with SNEDDS have improved physicochemical properties and treatment efficacy in BAC-induced DED.

Prevention of early liver metastasis after pancreatectomy by perioperative administration of a nuclear factor-κB inhibitor in mice

BACKGROUND

Liver metastasis is a common problem after pancreatectomy for pancreatic cancer. In pancreatic cancer cells, nuclear factor-κB is activated constitutively. Nuclear factor-κB activates matrix metalloproteinase-2/9, which plays an important role in cancer metastasis. Because the serine protease inhibitor FUT-175 suppresses nuclear factor-κB, we hypothesized that perioperative treatment with FUT-175 for pancreatic cancer may help to prevent liver metastasis.

METHODS

We compared in vitro cell viability, cell invasiveness, nuclear factor-κB signaling, and the expression levels of matrix metalloproteinase signals between the control group (C group) and the FUT-175 group (F group) using the murine pancreatic cancer cells PAN02. In addition, we evaluated the in vivo effect of pretreatment with FUT-175 using an established model of liver metastasis in mice. Metastatic liver lesions were assessed with magnetic resonance imaging. Liver recurrence and overall survival were evaluated. Also, the antimetastatic effect of systemic administration of FUT-175 was examined.

RESULTS

FUT-175 did not suppress the cell viability of PAN02 cells at or after 24 hours of treatment (P > .05); however, cell invasion was suppressed in the F group compared with the C group (P < .05). The levels of nuclear factor-κB activation, membrane type-1 (MT-1) matrix metalloproteinase (MMP)/matrix metalloproteinase-14 (MMP-14), and matrix metalloproteinase-2/9 (MMP-2/9) were lower in the F group compared with the C group. In vivo, both disease-free and overall survivals were prolonged in the F group compared with the C group. Systemic administration was also effective in suppressing the number of metastases.

CONCLUSION

Perioperative treatment with FUT-175 may help to prevent early liver metastasis after pancreatectomy for pancreatic cancer.

Inhibition of Poly(I:C)-Induced Inflammation by Salvianolic Acid A in Skin Keratinocytes

Background

Skin keratinocytes participate actively in inducing immune responses when external pathogens are introduced, thereby contributing to elimination of pathogens. However, in condition where the excessive inflammation is occurred, chronic skin disease such as psoriasis can be provoked.

Objective

We tried to screen the putative therapeutics for inflammatory skin disease, and found that salvianolic acid A (SAA) has an inhibitory effect on keratinocyte inflammatory reaction. The aim of this study is to demonstrate the effects of SAA in poly(I:C)-induced inflammatory reaction in skin keratinocytes.

Methods

We pre-treated keratinocytes with SAA then stimulated with poly(I:C). Inflammatory reaction of keratinocytes was verified using real-time polymerase chain reaction, enzyme-linked immunosorbent assay and Western blot.

Results

When skin keratinocytes were pre-treated with SAA, it significantly inhibited poly (I:C)-induced expression of inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, and CCL20. SAA inhibited poly(I:C)-induced activation of nuclear factor-κB signaling. And SAA also inhibited inflammasome activation, evidenced by decrease of IL-1β secretion. Finally, SAA markedly inhibited poly(I:C)-induced NLRP3 expression.

Conclusion

These results demonstrate that SAA has an inhibitory effect on poly(I:C)-induced inflammatory reaction of keratinocytes, suggesting that SAA can be developed for the treatment of inflammatory skin diseases such as psoriasis.

Thrombomodulin Regulation of Mitogen-Activated Protein Kinases

The multifaceted role of mitogen-activated protein kinases (MAPKs) in modulating signal transduction pathways in inflammatory conditions such as infection, cardiovascular disease, and cancer has been well established. Recently, coagulation factors have also emerged as key players in regulating intracellular signaling pathways during inflammation. Among coagulation factors, thrombomodulin, as a high affinity receptor for thrombin on vascular endothelial cells, has been discovered to be a potent anti-inflammatory and anti-tumorigenic signaling molecule. The protective signaling function of thrombomodulin is separate from its well-recognized role in the clotting cascade, which is to function as an anti-coagulant receptor in order to switch the specificity of thrombin from a procoagulant to an anti-coagulant protease. The underlying protective signaling mechanism of thrombomodulin remains largely unknown, though a few published reports link the receptor to the regulation of MAPKs under different (patho)physiological conditions. The goal of this review is to summarize what is known about the regulatory relationship between thrombomodulin and MAPKs.

Anti-inflammatory property of quercetin through downregulation of ICAM-1 and MMP-9 in TNF-α-activated retinal pigment epithelial cells

Quercetin is a flavonoid polyphenolic compound present in fruits and vegetables that has proven anti-inflammatory activity. The goal of the present investigation was to investigate the effects of quercetin on tumor necrosis factor-α (TNF-α)-induced inflammatory responses via the expression of ICAM-1 and MMP-9 in human retinal pigment epithelial cells (ARPE-19 cells). Real-time PCR, gelatin zymography, and Western blot analysis showed that TNF-α induced the expression of ICAM-1 and MMP-9 protein and mRNA in a time-dependent manner. These effects were attenuated by pretreatment of ARPE-19 cells with quercetin. Quercetin inhibited the TNF-α-induced phosphorylation of PKCδ, JNK1/2, ERK1/2. Quercetin, rottlerin, SP600125 and U0126 attenuated TNF-α-stimulated c-Jun phosphorylation and AP-1-Luc activity. Pretreatment with quercetin, rottlerin, SP600125, or Bay 11-7082 attenuated TNF-α-induced NF-κB (p65) phosphorylation, translocation and RelA/p65-Luc activity. TNF-α significantly increased MMP-9 promoter activity and THP-1 cell adherence, and these effects were attenuated by pretreatment with quercetin, rottlerin, SP600125, U0126, tanshinone IIA or Bay 11-7082. These results suggest that quercetin attenuates TNF-α-induced ICAM-1 and MMP-9 expression in ARPE-19 cells via the MEK1/2-ERK1/2 and PKCδ-JNK1/2-c-Jun or NF-κB pathways.

Carbon monoxide releasing molecule-2 attenuates Pseudomonas aeruginosa-induced ROS-dependent ICAM-1 expression in human pulmonary alveolar epithelial cells

Pseudomonas aeruginosa (P. aeruginosa) infection in the lung is common in patients with cystic fibrosis (CF). Intercellular adhesion molecule-1 (ICAM-1) is known to play a key role in lung inflammation. Acute inflammation and its timely resolution are important to ensure bacterial clearance and limit tissue damage. Carbon monoxide (CO) has been shown to exert anti-inflammatory effects in various tissues and organ systems. Here, we explored the protective effects and mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on P. aeruginosa-induced inflammatory responses in human pulmonary alveolar epithelial cells (HPAEpiCs). We showed that P. aeruginosa induced prostaglandin E₂ (PGE₂)/interleukin-6 (IL-6)/ICAM-1 expression and monocyte adherence to HPAEpiCs. Moreover, P. aeruginosa-induced inflammatory responses were inhibited by transfection with siRNA of Toll-like receptor 4 (TLR4), PKCα, p47^phox, JNK2, p42, p50, or p65. P. aeruginosa also induced PKCα, JNK, ERK1/2, and NF-κB activation. We further demonstrated that P. aeruginosa increased intracellular ROS generation via NADPH oxidase activation. On the other hand, P. aeruginosa-induced inflammation was inhibited by pretreatment with CORM-2. Preincubation with CORM-2 had no effects on TLR4 mRNA levels in response to P. aeruginosa. However, CORM-2 inhibits P. aeruginosa-induced inflammation by decreasing intracellular ROS generation. P. aeruginosa-induced PKCα, JNK, ERK1/2, and NF-κB activation was inhibited by CORM-2. Finally, we showed that P. aeruginosa induced levels of the biomarkers of inflammation in respiratory diseases, which were inhibited by pretreatment with CORM-2. Taken together, these data suggest that CORM-2 inhibits P. aeruginosa-induced PGE₂/IL-6/ICAM-1 expression and lung inflammatory responses by reducing the ROS generation and the inflammatory pathways.

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CORM-2 inhibits P. aeruginosa-induced PGE₂/IL-6/ICAM-1 expression.

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CORM-2 reduced PKCα phosphorylation in response to P. aeruginosa.

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We provide molecular mechanisms for antibacterial effects of CORM-2.

The cytomegalovirus protein US31 induces inflammation through mono-macrophages in systemic lupus erythematosus by promoting NF-κB2 activation

It has been hypothesized that human cytomegalovirus (HCMV) infection, especially in monocyte and CD34 (+) myeloid cells, acts as a important regulator of immune system to promote inflammation in multiple autoimmune diseases. The aim of this study was to elucidate the HCMV gene expression profiles in the peripheral blood mononuclear cells (PBMCs) of SLE patients and demonstrate the effect and mechanism of viral gene associated with SLE in mono-macrophages functions. Using two RNA-Seq techniques in combination with RT-PCR, 11 viral genes mainly associated with latent HCMV infection were identified in the PBMCs of SLE patients. Among these viral genes, US31 with previously unknown function was highly expressed in the PBMCs of SLE patients compared to healthy controls. Analysis of function indicated that US31 expression could induce inflammation in monocyte and macrophage and stimulate macrophage differentiation toward an M1 macrophage phenotype. Screening via protein chips in combination with bioinformatic analysis and consequent detection of mono-macrophages function indicates that the direct interaction between US31 and NF-κB2 contributed the NF-kB2 activation. Consequent analysis indicated US31 directly interacted with NF-κB2, contribute to the polyubiquitination of the phosphorylated p100 and consequent activation of NF-κB2. Taken together, our data uncovered a previously unknown role of the HCMV protein US31 in inducing NF-κB-mediated mono-macrophage inflammation in the pathogenesis and development of SLE. Our findings provide a foundation for the continued investigation of novel therapeutic targets for SLE patients.