VCAM-1 upregulation via PKCdelta-p38 kinase-linked cascade mediates the TNF-alpha-induced leukocyte adhesion and emigration in the lung airway epithelium

The 12-Membered TNFR1 Peptide, as Well as the 16-Membered and 6-Membered TNF Peptides, Regulate TNFR1-Dependent Cytotoxic Activity of TNF

Understanding the exact mechanisms of the activation of proinflammatory immune response receptors is very important for the targeted regulation of their functioning. In this work, we were able to identify the sites of the molecules in the proinflammatory cytokine TNF (tumor necrosis factor) and its TNFR1 (tumor necrosis factor receptor 1), which are necessary for the two-stage cytotoxic signal transduction required for tumor cell killing. A 12-membered TNFR1 peptide was identified and synthesized, interacting with the ligands of this receptor protein's TNF and Tag7 and blocking their binding to the receptor. Two TNF cytokine peptides interacting with different sites of TNFR1 receptors were identified and synthesized. It has been demonstrated that the long 16-membered TNF peptide interferes with the binding of TNFR1 ligands to this receptor, and the short 6-membered peptide interacts with the receptor site necessary for the transmission of a cytotoxic signal into the cell after the ligands' interaction with the binding site. This study may help in the development of therapeutic approaches to regulate the activity of the cytokine TNF.

Lung pathology of natural Babesia rossi infection in dogs

A proportion of Babesia rossi infections in dogs are classified as complicated and one of the most lethal complications is acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Most dogs that die succumb within 24 hours of presentation. The pulmonary pathology caused by B. rossi in dogs has not been described. The aim of this study was to provide a thorough macroscopic, histological and immunohistochemical description of the lung changes seen in dogs naturally infected with B. rossi that succumbed to the infection. Death was invariably accompanied by alveolar oedema. Histopathology showed acute interstitial pneumonia characterised by alveolar oedema and haemorrhages, with increased numbers of mononuclear leucocytes in alveolar walls and lumens. Intra-alveolar polymerised fibrin aggregates were observed in just over half the infected cases. Immunohistochemistry showed increased numbers of MAC387- and CD204-reactive monocyte-macrophages in alveolar walls and lumens, and increased CD3-reactive T-lymphocytes in alveolar walls, compared with controls. These histological features overlap to some extent (but far from perfectly) with the histological pattern of lung injury referred to as the exudative stage of diffuse alveolar damage (DAD) as is quite commonly reported in ALI/ARDS.

Deficiency of sphingomyelin synthase 2 prolongs survival by the inhibition of lymphoma infiltration through ICAM-1 reduction

The tumor microenvironment (TME) formation involving host cells and cancer cells through cell adhesion molecules (CAMs) is essential for the multiple steps of cancer metastasis and growth. Sphingomyelin synthase 2 (SMS2) is involved in inflammatory diseases such as obesity and diabetes mellitus by regulation of the SM/ceramide balance. However, the involvement of SMS2 in TME formation and metastasis is largely unknown. Here, we report that SMS2-deficient (SMS2-KO) mice show suppressed the EL4 cell infiltration to liver and prolonged survival time. ICAM-1 was identified as a candidate for the inhibition of TME formation in immortalized mouse embryonic fibroblasts (tMEFs) from mRNA array analysis for CAMs. Reduced SM/ceramide balance in SMS2-KO tMEFs suppressed the attachment of EL4 cells through transcriptional reduction of ICAM-1 by the inhibition of NF-κB activation. TNF-α-induced NF-κB activation and subsequent induction of ICAM-1 were suppressed in SMS2-KO tMEFs but restored by SMS2 re-introduction. In the EL4 cell infiltration mouse model, EL4 injection increased ICAM-1 expression in WT liver but not in SMS2-KO mouse liver. Therefore, inhibition of SMS2 may be a therapeutic target to suppress the infiltration of malignant lymphoma.

PKCδ inhibition as a novel medical countermeasure for radiation-induced vascular damage

In the event of a radiologic catastrophe, endothelial cell and neutrophil dysfunction play important roles in tissue injury. Clinically available therapeutics for radiation-induced vascular injury are largely supportive. PKCδ was identified as a critical regulator of the inflammatory response, and its inhibition was shown to protect critical organs during sepsis. We used a novel biomimetic microfluidic assay (bMFA) to interrogate the role of PKCδ in radiation-induced neutrophil-endothelial cell interaction and endothelial cell function. HUVECs formed a complete lumen in bMFA and were treated with 0.5, 2, or 5 Gy ionizing radiation (IR). At 24 h post-IR, the cells were treated with a PKCδ inhibitor for an additional 24 h. Under physiologic shear flow, the role of PKCδ on endothelium function and neutrophil adherence/migration was determined. PKCδ inhibition dramatically attenuated IR-induced endothelium permeability increase and significantly decreased neutrophil migration across IR-treated endothelial cells. Moreover, neutrophil adhesion to irradiated endothelial cells was significantly decreased after PKCδ inhibition in a flow-dependent manner. PKCδ inhibition downregulated IR-induced P-selectin, intercellular adhesion molecule 1, and VCAM-1 but not E-selectin overexpression. PKCδ is an important regulator of neutrophil-endothelial cell interaction post-IR, and its inhibition can serve as a potential radiation medical countermeasure.-Soroush, F., Tang, Y., Zaidi, H. M., Sheffield, J. B., Kilpatrick, L. E., Kiani, M. F. PKCδ inhibition as a novel medical countermeasure for radiation-induced vascular damage.

The Growth Inhibitory Potential and Antimetastatic Effect of Camel Urine on Breast Cancer Cells In Vitro and In Vivo

Although it may sound unpleasant, camel urine has been consumed extensively for years in the Middle East as it is believed to be able to treat a wide range of diseases such as fever, cold, or even cancer. People usually take it by mixing small drops with camel milk or take it directly. The project aims to study the effects of camel urine in inhibiting the growth potential and metastatic ability of 4T1 cancer cell line in vitro and in vivo. Based on the MTT result, the cytotoxicity of camel urine against 4T1 cell was established, and it was dose-dependent. Additionally, the antimetastatic potential of camel urine was tested by running several assays such as scratch assay, migration and invasion assay, and mouse aortic ring assay with promising results in the ability of camel urine to inhibit metastatic process of the 4T1 cells. In order to fully establish camel urine's potential, an in vivo study was carried out by treating mice inoculated with 4T1 cells with 2 different doses of camel urine. By the end of the treatment period, the tumor in both treated groups had reduced in size as compared to the control group. Additional assays such as the TUNEL assay, immunophenotyping, cytokine level detection assay, clonogenic assay, and proteome profiler demonstrated the capability of camel urine to reduce and inhibit the metastatic potential of 4T1 cells in vivo. To sum up, further study of anticancer properties of camel urine is justified, as evidenced through the in vitro and in vivo studies carried out. Better results were obtained at higher concentration of camel urine used in vivo. Apart from that, this project has laid out the mechanisms employed by the substance to inhibit the growth and the metastatic process of the 4T1 cell.

Sphingosine 1-Phosphate-Induced ICAM-1 Expression via NADPH Oxidase/ROS-Dependent NF-κB Cascade on Human Pulmonary Alveolar Epithelial Cells

The intercellular adhesion molecule-1 (ICAM-1) expression is frequently correlated with the lung inflammation. In lung injury, sphingosine-1-phosphate (S1P, bioactive sphingolipid metabolite), participate gene regulation of adhesion molecule in inflammation progression and aggravate tissue damage. To investigate the transduction mechanisms of the S1P in pulmonary epithelium, we demonstrated that exposure of HPAEpiCs (human pulmonary alveolar epithelial cells) to S1P significantly induces ICAM-1 expression leading to increase monocyte adhesion on the surface of HPAEpiCs. These phenomena were effectively attenuated by pretreatments with series of inhibitors such as Rottlerin (PKCδ), PF431396 (PYK2), diphenyleneiodonium chloride (DPI), apocynin (NADPH oxidase), Edaravone (ROS), and Bay11-7082 (NF-κB). Consistently, knockdown with siRNA transfection of PKCδ, PYK2, p47^phox, and p65 exhibited the same results. Pretreatment with both Gq-coupled receptor antagonist (GPA2A) and Gi/o-coupled receptor antagonist (GPA2) also blocked the upregulation of ICAM-1 protein and mRNA induced by S1P. We observed that S1P induced PYK2 activation via a Gq-coupled receptor/PKCδ-dependent pathway. In addition, S1P induced NADPH oxidase activation and intracellular ROS generation, which were also reduced by Rottlerin or PF431396. We demonstrated that S1P induced NF-κB p65 phosphorylation and nuclear translocation in HPAEpiCs. Activated NF-κB was blocked by Rottlerin, PF431396, APO, DPI, or Edaravone. Besides, the results of monocyte adhesion assay indicated that S1P-induced ICAM-1 expression on HPAEpiCs can enhance the monocyte attachments. In the S1P-treated mice, we found that the levels of ICAM-1 protein and mRNA in the lung fractions, the pulmonary hematoma and leukocyte count in bronchoalveolar lavage fluid were enhanced through a PKCδ/PYK2/NADPH oxidase/ROS/NF-κB signaling pathway. We concluded that S1P-accelerated lung damage is due to the ICAM-1 induction associated with leukocyte recruitment.

Endothelial LSP1 Modulates Extravascular Neutrophil Chemotaxis by Regulating Nonhematopoietic Vascular PECAM-1 Expression

During inflammation, leukocyte-endothelial cell interactions generate molecular signals that regulate cell functions. The Ca(2+)- and F-actin-binding leukocyte-specific protein 1 (LSP1) expressed in leukocytes and nonhematopoietic endothelial cells is pivotal in regulating microvascular permeability and leukocyte recruitment. However, cell-specific function of LSP1 during leukocyte recruitment remains elusive. Using intravital microscopy of cremasteric microvasculature of chimeric LSP1-deficient mice, we show that not neutrophil but endothelial LSP1 regulates neutrophil transendothelial migration and extravascular directionality without affecting the speed of neutrophil migration in tissue in response to CXCL2 chemokine gradient. The expression of PECAM-1-sensitive α6β1 integrins on the surface of transmigrated neutrophils was blunted in mice deficient in endothelial LSP1. Functional blocking studies in vivo and in vitro elucidated that α6β1 integrins orchestrated extravascular directionality but not the speed of neutrophil migration. In LSP1-deficient mice, PECAM-1 expression was reduced in endothelial cells, but not in neutrophils. Similarly, LSP1-targeted small interfering RNA silencing in murine endothelial cells mitigated mRNA and protein expression of PECAM-1, but not ICAM-1 or VCAM-1. Overexpression of LSP1 in endothelial cells upregulated PECAM-1 expression. Furthermore, the expression of transcription factor GATA-2 that regulates endothelial PECAM-1 expression was blunted in LSP1-deficient or LSP1-silenced endothelial cells. The present study unravels endothelial LSP1 as a novel cell-specific regulator of integrin α6β1-dependent neutrophil extravascular chemotactic function in vivo, effective through GATA-2-dependent transcriptional regulation of endothelial PECAM-1 expression.

PKCδ-iPLA2-PGE2-PPARγ signaling cascade mediates TNF-α induced Claudin 1 expression in human lung carcinoma cells

Claudin 1 (CLDN1) is a critical component of tight junction adhesion complexes that maintains the structural integrity of epithelial cell layers. Dysregulation of CLDN1 is associated with the growth and metastasis of human lung adenocarcinoma. TNF-α treatment was previously shown to increase expression of CLDN1 that mediated lung cancer cell morphology changes and migration. This study aimed to elucidate the molecular mechanisms involved in TNF-α induced CLDN1 expression in human lung carcinoma A549 cells. Chemical inhibition or siRNA downregulation of Src, PI3K, Akt, MAPKs, NFκB, caspase and PKC demonstrated that PKC, specifically PKCδ, is required for TNF-α induced CLDN1 expression. Further investigation of the PKC pathway revealed that CLDN1 expression is enhanced by the downstream molecules iPLA2, PGE2, 15-keto PGE2 and PPARγ. Conversely, inhibition of these molecules decreased CLDN1 expression. Additionally, a wound-healing assay demonstrated that TNF-α stimulation, PKC activation, prostaglandin treatment or PPARγ activation enhanced cell migration. In conclusion, TNF-α induced CLDN1 expression is regulated by the PKCδ-iPLA2-PGE2-PPARγ signaling cascade in human lung carcinoma A549 cells.

Serum adhesion molecules as outcome predictors in adult severe sepsis patients requiring mechanical ventilation in the emergency department

BACKGROUND AND AIM

Serum adhesion molecules play a pivotal role in the pathogenesis of sepsis syndrome. This study aimed to evaluate the prognostic value of serum adhesion molecules in patients with severe sepsis and mechanical ventilation (MV) at the emergency department.

METHODS

Eighty-seven consecutive patients with severe sepsis, including 35 with MV, were evaluated. Serum samples were collected for analysis of serum adhesion molecules. The patients' clinical and laboratory data on admission were also recorded.

RESULTS

The maximum 24-h APACHE II and 24-h SOFA scores were significantly higher in the severe sepsis patients requiring MV than in patients without MV (p=0.02 and p<0.001). Mortality rate was significantly higher in severe sepsis patients requiring MV than in patients without MV (40% [14/35] vs. 9.6% [5/52], p=0.001). Both VCAM-1 level (p=0.03) and lactate concentration (p=0.04) on admission had significant differences between survivors and non-survivors in patients requiring MV. In the logistic regression model, only VCAM-1 level (p=0.049) was independently predictive of mortality. By correlation analysis, lactate concentration significantly correlated with the mean VCAM-1 level on admission (γ=0.484, p=0.004). The area under the ROC curve for VCAM-1 level was 0.747 (p=0.02, 95% CI: 0.576-0.918). The cut-off value of VCAM-1 level for predicting hospital mortality in severe sepsis patients receiving MV was 1870ng/mL, with 77% sensitivity and 71% specificity; then the likelihood ratio equals 2.7.

CONCLUSIONS

In this study, VCAM-1 level is a more powerful outcome predictor of hospital mortality in severe sepsis patients requiring MV than lactate concentration and other conventional parameters on admission. This suggests that increased plasma VCAM-1 concentration may be useful in identifying who are at risk of hospital mortality among severely septic patients requiring MV.

PKCδ regulates force signaling during VEGF/CXCL4 induced dissociation of endothelial tubes

Wound healing requires the vasculature to re-establish itself from the severed ends; endothelial cells within capillaries must detach from neighboring cells before they can migrate into the nascent wound bed to initiate angiogenesis. The dissociation of these endothelial capillaries is driven partially by platelets' release of growth factors and cytokines, particularly the chemokine CXCL4/platelet factor-4 (PF4) that increases cell-cell de-adherence. As this retraction is partly mediated by increased transcellular contractility, the protein kinase c-δ/myosin light chain-2 (PKCδ/MLC-2) signaling axis becomes a candidate mechanism to drive endothelial dissociation. We hypothesize that PKCδ activation induces contractility through MLC-2 to promote dissociation of endothelial cords after exposure to platelet-released CXCL4 and VEGF. To investigate this mechanism of contractility, endothelial cells were allowed to form cords following CXCL4 addition to perpetuate cord dissociation. In this study, CXCL4-induced dissociation was reduced by a VEGFR inhibitor (sunitinib malate) and/or PKCδ inhibition. During combined CXCL4+VEGF treatment, increased contractility mediated by MLC-2 that is dependent on PKCδ regulation. As cellular force is transmitted to focal adhesions, zyxin, a focal adhesion protein that is mechano-responsive, was upregulated after PKCδ inhibition. This study suggests that growth factor regulation of PKCδ may be involved in CXCL4-mediated dissociation of endothelial cords.

Protein kinase C and acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a major public health problem and a leading source of morbidity in intensive care units. Lung tissue in patients with ARDS is characterized by inflammation, with exuberant neutrophil infiltration, activation, and degranulation that is thought to initiate tissue injury through the release of proteases and oxygen radicals. Treatment of ARDS is supportive primarily because the underlying pathophysiology is poorly understood. This gap in knowledge must be addressed to identify urgently needed therapies. Recent research efforts in anti-inflammatory drug development have focused on identifying common control points in multiple signaling pathways. The protein kinase C (PKC) serine-threonine kinases are master regulators of proinflammatory signaling hubs, making them attractive therapeutic targets. Pharmacological inhibition of broad-spectrum PKC activity and, more importantly, of specific PKC isoforms (as well as deletion of PKCs in mice) exerts protective effects in various experimental models of lung injury. Furthermore, PKC isoforms have been implicated in inflammatory processes that may be involved in the pathophysiologic changes that result in ARDS, including activation of innate immune and endothelial cells, neutrophil trafficking to the lung, regulation of alveolar epithelial barrier functions, and control of neutrophil proinflammatory and prosurvival signaling. This review focuses on the mechanistic involvement of PKC isoforms in the pathogenesis of ARDS and highlights the potential of developing new therapeutic paradigms based on the selective inhibition (or activation) of specific PKC isoforms.

Pulmonary endothelial protein kinase C-delta (PKCδ) regulates neutrophil migration in acute lung inflammation

Excessive neutrophil migration across the pulmonary endothelium into the lung and release of oxidants and proteases are key elements in pathogenesis of acute lung injury. Previously, we identified protein kinase C-delta (PKCδ) as an important regulator of proinflammatory signaling in human neutrophils and demonstrated that intratracheal instillation of a TAT-conjugated PKCδ inhibitory peptide (PKCδ-TAT) is lung protective in a rat model of sepsis-induced indirect pulmonary injury (cecal ligation and puncture). In the present study, intratracheal instillation of this PKCδ inhibitor resulted in peptide distribution throughout the lung parenchyma and pulmonary endothelium and decreased neutrophil influx, with concomitant attenuation of sepsis-induced endothelial ICAM-1 and VCAM-1 expression in this model. To further delineate the role of PKCδ in regulating neutrophil migration, we used an in vitro transmigration model with human pulmonary microvascular endothelial cells (PMVECs). Consistent with in vivo findings, inhibition of PMVEC PKCδ decreased IL-1β-mediated neutrophil transmigration. PKCδ regulation was stimulus-dependent; PKCδ was required for transmigration mediated by IL-1β and fMLP (integrin-dependent), but not IL-8 (integrin-independent). PKCδ was essential for IL-1β-mediated neutrophil adherence and NF-κB-dependent expression of ICAM-1 and VCAM-1. In PMVECs, IL-1β-mediated production of ROS and activation of redox-sensitive NF-κB were PKCδ dependent, suggesting an upstream signaling role. Thus, PKCδ has an important role in regulating neutrophil-endothelial cell interactions and recruitment to the inflamed lung.

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid suppresses UV-induced IL-6 synthesis in keratinocytes, exerting an anti-inflammatory activity

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is an enzymatic product of prostaglandin H₂ (PGH₂) derived from cyclooxygenase (COX)-mediated arachidonic acid metabolism. Despite the high level of 12-HHT present in tissues and bodily fluids, its precise function remains largely unknown. In this study, we found that 12-HHT treatment in HaCaT cells remarkably down-regulated the ultraviolet B (UVB) irradiation-induced synthesis of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cutaneous inflammation. In an approach to identify the down-stream signaling mechanism by which 12-HHT down-regulates UVB-induced IL-6 synthesis in keratinocytes, we observed that 12-HHT inhibits the UVB-stimulated activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB). In addition, we found that 12-HHT markedly up-regulates MAPK phosphatase-1 (MKP-1), a critical negative regulator of p38 MAPK. When MKP-1 was suppressed by siRNA knock-down, the 12-HHT-mediated inhibitory effects on the UVB-stimulated activation of p38 MAPK and NF-κB, as well as the production of IL-6, were attenuated in HaCaT cells. Taken together, our results suggest that 12-HHT exerts anti-inflammatory effect via up-regulation of MKP-1, which negatively regulates p38 MAPK and NF-κB, thus attenuating IL-6 production in UVB-irradiated HaCaT cells. Considering the critical role of IL-6 in cutaneous inflammation, our findings provide the basis for the application of 12-HHT as a potential anti-inflammatory therapeutic agent in UV-induced skin diseases.

The protein kinase C inhibitor AEB071 (sotrastaurin) modulates migration and superoxide anion production by human neutrophils in vitro

We examined the effect of the protein kinase C-selective inhibitor AEB071 (sotrastaurin) on neutrophil functions in vitro. Pre-incubation with AEB071 at concentrations similar to those reached during in vivo therapy significantly reduced cell capacity to migrate toward three different chemo-attractants and to produce superoxide anions (O₂⁻) in response to phorbol myristate acetate (PMA) or to N-formyl-methionyl-leucyl-phenylalanine (fMLP). AEB071 also significantly inhibited the O₂⁻ overproduction induced by fMLP in neutrophils primed with tumor necrosis factor alpha (TNF-α) or granulocyte/macrophage-colony stimulating factor (GM-CSF). This inhibition was not linked to fMLP-receptor down-regulation since the drug had no effect on either fMLP-receptors or fMLP-induced CD11b membrane expression. When the activity of AEB071 was compared to that of the conventional protein kinase C (PKC) inhibitor Gö6850 (which, like sotrastaurin, inhibits classical and novel PKC isoforms), Gö6976 (an inhibitor of α and α PKC isoforms) and rottlerin (a prevailing δ PKC isoform inhibitor), AEB071 at an equimolar concentration of 3 μM (close to the maximum drug concentration reached in patients treated with AEB071) caused significantly more inhibition on both chemotactic response and superoxide production. These in vitro findings suggest that neutrophils may offer a cellular target for AEB071 activity in vivo.

BLT2 up-regulates interleukin-8 production and promotes the invasiveness of breast cancer cells

BACKGROUND

The elevated production of interleukin (IL)-8 is critically associated with invasiveness and metastatic potential in breast cancer cells. However, the intracellular signaling pathway responsible for up-regulation of IL-8 production in breast cancer cells has remained unclear.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we report that the expression of BLT2 is markedly up-regulated in the highly aggressive human breast cancer cell lines MDA-MB-231 and MDA-MB-435 compared with MCF-10A immortalized human mammary epithelial cells, as determined by RT-PCR, real-time PCR and FACS analysis. Blockade of BLT2 with BLT2 siRNA knockdown or BLT2 inhibitor treatment downregulated IL-8 production and thereby diminished the invasiveness of aggressive breast cancer cells, analyzed by Matrigel invasion chamber assays. We further characterized the downstream signaling mechanism by which BLT2 stimulates IL-8 production and identified critical mediatory roles for the generation of reactive oxygen species (ROS) and the consequent activation of the transcription factor NF-κB. Moreover, blockade of BLT2 suppressed the formation of metastatic lung nodules by MDA-MB-231 cells in both experimental and orthotopic metastasis models.

CONCLUSIONS/SIGNIFICANCE

Taken together, our study demonstrates that a BLT2-ROS-NF-κB pathway up-regulates IL-8 production in MDA-MB-231 and MDA-MB-435 cells, thereby contributing to the invasiveness of these aggressive breast cancer cells. Our findings provide insight into the molecular mechanism of invasiveness in breast cancer.

An extract of Crataegus pinnatifida fruit attenuates airway inflammation by modulation of matrix metalloproteinase-9 in ovalbumin induced asthma

BACKGROUND

Crataegus pinnatifida (Chinese hawthorn) has long been used as a herbal medicine in Asia and Europe. It has been used for the treatment of various cardiovascular diseases such as myocardial weakness, tachycardia, hypertension and arteriosclerosis. In this study, we investigated the anti-inflammatory effects of Crataegus pinnatifida ethanolic extracts (CPEE) on Th2-type cytokines, eosinophil infiltration, expression of matrix metalloproteinase (MMP)-9, and other factors, using an ovalbumin (OVA)-induced murine asthma model.

METHODS/PRINCIPAL FINDING

Airways of OVA-sensitized mice exposed to OVA challenge developed eosinophilia, mucus hypersecretion and increased cytokine levels. CPEE was applied 1 h prior to OVA challenge. Mice were administered CPEE orally at doses of 100 and 200 mg/kg once daily on days 18-23. Bronchoalveolar lavage fluid (BALF) was collected 48 h after the final OVA challenge. Levels of interleukin (IL)-4 and IL-5 in BALF were measured using enzyme-linked immunosorbent (ELISA) assays. Lung tissue sections 4 µm in thickness were stained with Mayer's hematoxylin and eosin for assessment of cell infiltration and mucus production with PAS staining, in conjunction with ELISA, and Western blot analyses for the expression of MMP-9, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 protein expression. CPEE significantly decreased the Th2 cytokines including IL-4 and IL-5 levels, reduced the number of inflammatory cells in BALF and airway hyperresponsiveness, suppressed the infiltration of eosinophil-rich inflammatory cells and mucus hypersecretion and reduced the expression of ICAM-1, VCAM-1 and MMP-9 and the activity of MMP-9 in lung tissue of OVA-challenged mice.

CONCLUSIONS

These results showed that CPEE can protect against allergic airway inflammation and can act as an MMP-9 modulator to induce a reduction in ICAM-1 and VCAM-1 expression. In conclusion, we strongly suggest the feasibility of CPEE as a therapeutic drug for allergic asthma.

Leukotriene B4 receptor-2 promotes invasiveness and metastasis of ovarian cancer cells through signal transducer and activator of transcription 3 (STAT3)-dependent up-regulation of matrix metalloproteinase 2

Ovarian cancer is the most lethal gynecologic malignancy in women. Despite the fact that the metastatic spread is associated with the majority of deaths from ovarian cancer, the molecular mechanisms regulating the invasive and metastatic phenotypes of ovarian cancer are poorly understood. In this study, we demonstrated that BLT2, a low affinity leukotriene B(4) receptor, is highly expressed in OVCAR-3 and SKOV-3 human ovarian cancer cells, and that this receptor plays a key role in the invasiveness and metastasis of these cells through activation of STAT3 and consequent up-regulation of matrix metalloproteinase 2 (MMP2). In addition, our results suggest that activation of NAD(P)H oxidase-4 (NOX4) and subsequent reactive oxygen species (ROS) generation lie downstream of BLT2, mediating the stimulation of STAT3-MMP2 cascade in this process. For example, knockdown of BLT2 or NOX4 using each specific siRNA suppressed STAT3 stimulation and MMP2 expression. Similarly, inhibition of STAT3 suppressed the expression of MMP2, thus leading to attenuated invasiveness of these ovarian cancer cells. Finally, the metastasis of SKOV-3 cells in nude mice was markedly suppressed by pharmacological inhibition of BLT2. Together, our results implicate a BLT2-NOX4-ROS-STAT3-MMP2 cascade in the invasiveness and metastasis of ovarian cancer cells.

Andrographolide inhibits ICAM-1 expression and NF-κB activation in TNF-α-treated EA.hy926 cells

Several lines of evidence indicate that inflammation and endothelial cell dysfunction are important initiating events in atherosclerosis. Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine, induces the expression of cell adhesion molecules and results in monocyte adherence and atheromatous plaque formation. Andrographolide (AP) is a major bioactive diterpene lactone in Andrographis paniculata that has anti-inflammatory activity. A previous study demonstrated the role of heme oxygenase 1 (HO-1) in the inhibition of TNF-α-induced ICAM-1 expression by AP. The present study investigated the effect of AP on the IKK/NF-κB signaling pathway, which mediates TNF-α-induced ICAM-1 expression in EA.hy926 cells. Similar to the previous study, AP inhibited TNF-α-induced ICAM-1 mRNA and protein levels, its expression on the cell surface, and subsequent adhesion of HL-60 cells to EA.hy926 cells. AP inhibited TNF-α-induced κB inhibitor (IκB) kinase (IKK) and IκBα activation, p65 nuclear translocation, NF-κB and DNA binding activity, and promoter activity of ICAM-1. Although AP increased the intracellular cAMP concentration and induced the phosphorylation of cAMP response element-binding protein (CREB), knocking down CREB protein expression by transfecting the cells with CREB-specific small interfering RNA did not relieve the inhibition of ICAM-1 expression by AP. Taken together, these results suggest that AP down-regulates TNF-α-induced ICAM-1 expression at least in part via attenuation of activation of NF-κB in EA.hy926 cells rather than through activation of CREB. The results suggest that AP may have potential as a cardiovascular-protective agent.

Low-dose UVB irradiation stimulates matrix metalloproteinase-1 expression via a BLT2-linked pathway in HaCaT cells

Skin exposure to low-dose ultraviolet B (UVB) light up-regulates the expression of matrix metalloproteinase-1 (MMP-1), thus contributing to premature skin aging (photo-aging). Although cyclooxygenase-2 (COX- 2) and its product, prostaglandin E(2) (PGE((2))), have been associated with UVB-induced signaling to MMP expression, very little are known about the roles of lipoxygenases and their products, especially leukotriene B((4)) (LTB((4))) and 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), in MMP-1 expression in skin keratinocytes. In the present study, we demonstrate that BLT2, a cell surface receptor for LTB((4)) and 12(S)-HETE, plays a critical role in UVB-mediated MMP-1 upregulation in human HaCaT keratinocytes. Moreover, our results demonstrated that BLT2-mediated MMP-1 upregulation occurs through a signaling pathway dependent on reactive oxygen species (ROS) production and the subsequent stimulation of ERK. Blockage of BLT2 via siRNA knockdown or with the BLT2-antagonist LY255283 completely abolished the up-regulated expression of MMP-1 induced by low-dose UVB irradiation. Finally, when HaCaT cells were transiently transfected with a BLT2 expression plasmid, MMP-1 expression was significantly enhanced, along with ERK phosphorylation, suggesting that BLT2 overexpression alone is sufficient for MMP-1 up-regulation. Together, our results suggest that the BLT2-ROS- ERK-linked cascade is a novel signaling mechanism for MMP-1 upregulation in low-dose UVB- irradiated keratinocytes and thus potentially contributes to photo-aging.

Involvement of Na(+), K (+)-ATPase and its inhibitors in HuR-mediated cytokine mRNA stabilization in lung epithelial cells

Increasing evidence demonstrates that Na(+), K(+)-ATPase plays an important role in pulmonary inflammation, but the mechanism remains largely unknown. In this study, we used cardiotonic steroids as Na(+), K(+)-ATPase inhibitors to explore the possible involvement of Na(+), K(+)-ATPase in pulmonary epithelial inflammation. The results demonstrated that mice after ouabain inhalation developed cyclooxygenase-2-dependent acute lung inflammation. The in vitro experiments further confirmed that Na(+), K(+)-ATPase inhibitors significantly stimulated cyclooxygenase-2 expression in lung epithelial cells of human or murine origin, the process of which was participated by multiple cis-elements and trans-acting factors. Most importantly, we first described here that Na(+), K(+)-ATPase inhibitors could evoke a significant Hu antigen R nuclear export in lung epithelial cells, which stabilized cyclooxygenase-2 mRNA by binding with a proximal AU-rich element within its 3'-untranslated region. In conclusion, HuR-mediated mRNA stabilization opens new avenues in understanding the importance of Na(+), K(+)-ATPase, as well as its inhibitors in inflammation.

Protection against sepsis-induced lung injury by selective inhibition of protein kinase C-δ (δ-PKC)

Inflammation and proinflammatory mediators are activators of δ-PKC. In vitro, δ-PKC regulates proinflammatory signaling in neutrophils and endothelial and epithelial cells, cells that can contribute to lung tissue damage associated with inflammation. In this study, a specific δ-PKC TAT peptide inhibitor was used to test the hypothesis that inhibition of δ-PKC would attenuate lung injury in an animal model of ARDS. Experimental ARDS was induced in rats via 2CLP, a model of polymicrobial sepsis. Following 2CLP surgery, the δ-PKC TAT inhibitory peptide (2CLP+δ-PKC TAT in PBS) or PBS (2CLP+PBS) was administered intratracheally. Controls consisted of SO, where animals underwent a laparotomy without 2CLP. Twenty-four hours after SO or 2CLP, blood, BALF, and lung tissue were collected. 2CLP induced δ-PKC phosphorylation in the lung within 24 h. Treatment with the δ-PKC TAT inhibitory peptide significantly decreased pulmonary δ-PKC phosphorylation, indicating effective inhibition of δ-PKC activation. Plasma and BALF levels of the chemokines CINC-1 and MIP-2 were elevated in 2CLP + PBS rats as compared with SO rats. Treatment with δ-PKC TAT reduced 2CLP-induced elevations in chemokine levels in BALF and plasma, suggesting that δ-PKC modulated chemokine expression. Most importantly, intratracheal administration of δ-PKC TAT peptide significantly attenuated inflammatory cell infiltration, disruption of lung architecture, and pulmonary edema associated with 2CLP. Thus, δ-PKC is an important regulator of proinflammatory events in the lung. Targeted inhibition of δ-PKC exerted a lung-protective effect 24 h after 2CLP.

Proinflammatory cytokine IL-1beta stimulates IL-8 synthesis in mast cells via a leukotriene B4 receptor 2-linked pathway, contributing to angiogenesis

Recent studies have suggested that mast cells have critical roles in angiogenesis. However, the detailed mechanism by which mast cells contribute to angiogenesis is not yet clearly understood, especially in response to proinflammatory cytokines. In this study, we showed that the proinflammatory cytokine IL-1beta induces the synthesis of IL-8, a potent angiogenic factor, in human mast cells via the leukotriene B(4) receptor (BLT)2. We also characterized the BLT2 downstream signaling pathway and determined that BLT2-mediated IL-8 synthesis involves the upregulation of Nox1, a member of the NADPH oxidase family, Nox1-dependent reactive oxygen species generation and the subsequent activation of the redox-sensitive transcription factor NF-kappaB. For instance, knockdown of BLT2 and Nox1 with specific small interfering RNA, treatment with a specific BLT2 antagonist, LY255283, or treatment with a potential Nox inhibitor, diphenylene iodonium, suppressed IL-1beta-induced IL-8 synthesis. We found that the conditioned media collected from IL-1beta-treated human mast cell line HMC-1 had significantly enhanced angiogenic activity that could be dramatically attenuated by either small interfering RNA knockdown of BLT2 or treatment with neutralizing Ab to IL-8. Finally, the experiments were repeated using human primary cord blood-derived mast cells, and the results were clearly reproduced. Taken together, our results suggest that BLT2-Nox1-reactive oxygen species-dependent pathway plays a role in promoting the secretion of IL-8 from human mast cells in response to the proinflammatory cytokine IL-1beta, thus contributing to angiogenesis.

Delayed activation of extracellular-signal-regulated kinase 1/2 is involved in genistein- and equol-induced cell proliferation and estrogen-receptor-alpha-mediated transcription in MCF-7 breast cancer cells

The aim of this study was to determine whether the extracellular-signal-regulated kinase 1/2 (ERK1/2) pathway is involved in genistein- and equol-induced cell proliferation and estrogen receptor (ER) alpha transactivation. For MCF-7 human breast cells, low concentrations of genistein and equol enhanced proliferation and induced MCF-7 cells to enter the S-phase. Genistein- and equol-induced cell proliferation and S-phase entry were blocked by the ERalpha antagonists 4-hydroxytamoxifen and ICI 182,780 and by the mitogen-activated protein kinase 1/2 inhibitor U0126. These data indicated that ERalpha and mitogen-activated protein extracellular kinase/ERK signaling were required for the effects of genistein/equol on cell growth and cell cycle progression. Genistein and equol induced delayed and prolonged activation of ERK1/2. Inhibition of ERK1/2 phosphorylation by U0126 led to complete suppression of genistein- and equol-induced estrogen response element reporter activity and to suppression of the estrogen-responsive gene pS2. The anti-estrogen ICI had no effect on genistein- and equol-induced ERK1/2 phosphorylation. These results suggest that activation of ERK1/2 lies upstream of ER-mediated transcription, and that ERK1/2 activation is necessary for the transactivation of ERalpha. In conclusion, genistein and equol elicit a delayed activation of ERK1/2, and this activation appears to be involved in the proliferation of breast cancer cells and estrogen-dependent transcriptional activation.

NF-kappaB, but not p38 MAP kinase, is required for TNF-alpha-induced expression of cell adhesion molecules in endothelial cells

In response to inflammation stimuli, tumor necrosis factor-alpha (TNF-alpha) induces expression of cell adhesion molecules (CAMs) in endothelial cells (ECs). Studies have suggested that the nuclear factor-kappaB (NF-kappaB) and the p38 MAP kinase (p38) signaling pathways play central roles in this process, but conflicting results have been reported. The objective of this study is to determine the relative contributions of the two pathways to the effect of TNF-alpha. Our initial data indicated that blockade of p38 activity by chemical inhibitor SB203580 (SB) at 10 microM moderately inhibited TNF-alpha-induced expression of three types of CAMs; ICAM-1, VCAM-1 and E-selectin, indicating that p38 may be involved in the process. However, subsequent analysis revealed that neither 1 microM SB that could completely inhibit p38 nor specific knockdown of p38alpha and p38beta with small interference RNA (siRNA) had an apparent effect, indicating that p38 activity is not essential for TNF-alpha-induced CAMs. The most definitive evidence to support this conclusion was from the experiments using cells differentiated from p38alpha knockout embryonic stem cells. We could show that deletion of p38alpha gene did not affect TNF-alpha-induced ICAM-1 and VCAM-1 expression when compared with wild-type cells. We further demonstrated that inhibition of NF-kappaB completely blocked TNF-alpha-induced expression of ICAM-1, VCAM-1 and E-selectin. Taken together, our results clearly demonstrate that NF-kappaB, but not p38, is critical for TNF-alpha-induced CAM expression. The inhibition of SB at 10 microM on TNF-alpha-induced ICAM-1, VCAM-1 and E-selectin is likely due to the nonspecific effect of SB.

TNF-alpha-induced up-regulation of intercellular adhesion molecule-1 is regulated by a Rac-ROS-dependent cascade in human airway epithelial cells

Up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the lung airway epithelium is associated with the epithelium-leukocyte interaction, critical for the pathogenesis of various lung airway inflammatory diseases such as asthma. However, little is known about how ICAM-1 is up-regulated in human airway epithelial cells. In this study, we show that tumor TNF-alpha induces monocyte adhesion to A549 human lung airway epithelium and also up-regulation of ICAM-1 expression. These effects were significantly diminished by pre-treatment with diphenyliodonium (DPI), an inhibitor of NADPH oxidase-like flavoenzyme. In addition, the level of reactive oxygen species (ROS) was increased in response to TNF-alpha in A549 cells, suggesting a potential role of ROS in the TNF-alpha-induced signaling to ICAM-1 expression and monocyte adhesion to airway epithelium. Further, we found out that expression of RacN17, a dominant negative mutant of Rac1, suppressed TNF-alpha-induced ROS generation, ICAM-1 expression, and monocyte adhesion to airway epithelium. These findings suggest that Rac1 lies upstream of ROS generation in the TNF-alpha-induced signaling to ICAM-1 expression in airway epithelium. Finally, pretreatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kappaB, reduced TNF-alpha-induced ICAM-1 expression and both DPI and RacN17 significantly diminished NF-kappaB activation in response to TNF-alpha. Together, we propose that Rac1-ROS-linked cascade mediate TNF-alpha-induced ICAM-1 up-regulation in the airway epithelium via NF-kappaB-dependent manner.

Regulation of neutral sphingomyelinase-2 (nSMase2) by tumor necrosis factor-alpha involves protein kinase C-delta in lung epithelial cells

Neutral sphingomyelinases (N-SMases) are major candidates for stress-induced ceramide production, but there is still limited knowledge of the regulatory mechanisms of the cloned N-SMase enzyme-nSMase2. We have reported that p38 mitogen-activated protein kinase (MAPK) was upstream of nSMase2 in tumor necrosis-alpha (TNF-alpha)-stimulated A549 cells ( J Biol Chem 282: 1384-1396, 2007 ). Here, we report a role for protein kinase C (PKC) in mediating TNF-induced translocation of nSMase2 from the Golgi to the plasma membrane (PM). Pharmacological inhibition of PKCs prevented TNF-stimulated nSMase2 translocation to the PM in A549 cells. Using phorbol 12-myristate 13-acetate (PMA) as a tool to dissect PKC responses, we found that PMA induced nSMase2 translocation to the PM in a time- and dose-dependent manner. Pharmacological inhibitors and specific siRNA implicated the novel PKCs, specifically PKC-delta, in both TNF and PMA-stimulated nSMase2 translocation. However, PMA did not increase in vitro N-SMase activity and PKC-delta did not regulate TNF-induced N-SMase activity. Furthermore, PKC-delta and nSMase2 did not coimmunoprecipitate, suggesting that other signaling proteins may be involved. PMA-stimulated nSMase2 translocation was independent of p38 MAPK, and neither PKC inhibitors nor small interfering RNA had significant effects on TNF-stimulated p38 MAPK activation, indicating that PKC-delta does not act through p38 MAPK in regulating nSMase2. Finally, down-regulation of PKC-delta inhibited induction of vascular cell and intercellular adhesion molecules, previously identified as downstream of nSMase2 in A549 cells. Taken together, these data implicate PKC-delta as a regulator of nSMase2 and, for the first time, identify nSMase2 as a point of cross-talk between the PKC and sphingolipid pathways.

Hyperosmolarity-induced dilation and epithelial bioelectric responses of guinea pig trachea in vitro: role of kinase signaling

Exercise-induced airway obstruction is thought to involve evaporative water loss and hyperosmolarity of the airway surface liquid. Hyperosmolar challenge of the epithelium of isolated, perfused guinea pig trachea rapidly alters transepithelial potential difference (V(t)), and it elicits smooth muscle relaxation mediated by epithelium-derived relaxing factor (EpDRF). In many cell types, protein kinases mediate responses to hyperosmolarity and regulatory volume increase. In this study, inhibitors were used to investigate the involvement of kinases and phosphatases in bioelectric responses of epithelium to hyperosmolarity and their possible relationship to EpDRF-mediated relaxation. After contraction of the perfused trachea with extraluminal methacholine, D-mannitol applied intraluminally (< or = 80 mosM) increased V(t) and elicited dilation of the smooth muscle with a similar concentration-dependence; higher concentrations decreased V(t). In tracheas exposed to 30 mosM D-mannitol (approximately EC(50)), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) and SKF 86002 [6-(4-fluorophenyl)-2,3-dihydro-5-(4-pyridyl)imidazo[2,1-b]thiazole] (p38 inhibitors) potentiated the dilation, whereas SP 600125 [anthra[1,9-cd]pyrazol-6(2H)-one-1,9-pyrazoloanthrone] and dicumarol [c-Jun NH(2)-terminal kinase (JNK) inhibitors], chelerythrine [nonselective protein kinase C (PKC) inhibitor], and NaAsO(2) (mitogen-activated protein kinase stress inducer) and Na(3)VO(4) (protein tyrosine phosphatase inhibitor) inhibited the hyperpolarization. Large increases in the phosphorylation of p38 and JNK occurred at concentrations higher than those needed to elicit functional responses. The phosphatidylinositol 3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002) and Na(3)VO(4) did not affect the V(t) responses, but they inhibited methacholine-induced constriction; SP 600125 and dicumarol potentiated, and chelerythrine inhibited, methacholine-induced epithelial hyperpolarization. These results suggest that JNK, PKC, and phosphatase(s) are involved in hyperosmolarity-induced hyperpolarization of the tracheal epithelium but that p38 is involved in EpDRF-mediated relaxation.

Protein kinase C delta regulates airway mucin secretion via phosphorylation of MARCKS protein

Mucin hypersecretion is a major pathological feature of many respiratory diseases, yet cellular mechanisms regulating secretion of mucin have not been fully elucidated. Previously, we reported that mucin hypersecretion induced by human neutrophil elastase involves activation of protein kinase C (PKC), specifically the delta-isoform (PKC delta). Here, we further investigated the role of PKC delta in mucin hypersecretion using both primary human bronchial epithelial cells and the human bronchial epithelial 1 cell line as in vitro model systems. Phorbol-12-myristate-13-acetate (PMA)-induced mucin hypersecretion was significantly attenuated by rottlerin, a PKC delta-selective inhibitor. Rottlerin also reduced PMA- or human neutrophil elastase-induced phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) protein in these cells. Both secretion and MARCKS phosphorylation were significantly enhanced by the PKC delta activator bryostatin 1. A dominant-negative PKC delta construct (pEGFP-N1/PKC delta K376R) transfected into human bronchial epithelial 1 cells significantly attenuated both PMA-induced mucin secretion and phosphorylation of MARCKS, whereas transfection of a wild-type construct increased PKC delta and enhanced mucin secretion and MARCKS phosphorylation. Similar transfections of a dominant-negative or wild-type PKC epsilon construct did not affect either mucin secretion or MARCKS phosphorylation. The results suggest that PKC delta plays an important role in mucin secretion by airway epithelium via regulation of MARCKS phosphorylation.

Protein kinase C delta is essential for optimal macrophage-mediated phagosomal containment of Listeria monocytogenes

Activation of macrophages and subsequent "killing" effector functions against infectious pathogens are essential for the establishment of protective immunity. NF-IL6 is a transcription factor downstream of IFN-gamma and TNF in the macrophage activation pathway required for bacterial killing. Comparison of microarray expression profiles of Listeria monocytogenes (LM)-infected macrophages from WT and NF-IL6-deficient mice enabled us to identify candidate genes downstream of NF-IL6 involved in the unknown pathways of LM killing independent of reactive oxygen intermediates and reactive nitrogen intermediates. One differentially expressed gene, PKCdelta, had higher mRNA levels in the LM-infected NF-IL6-deficient macrophages as compared with WT. To define the role of PKCdelta during listeriosis, we infected PKCdelta-deficient mice with LM. PKCdelta-deficient mice were highly susceptible to LM infection with increased bacterial burden and enhanced histopathology despite enhanced NF-IL6 mRNA expression. Subsequent studies in PKCdelta-deficient macrophages demonstrated that, despite elevated levels of proinflammatory cytokines and NO production, increased escape of LM from the phagosome into the cytoplasm and uncontrolled bacterial growth occurred. Taken together these data identified PKCdelta as a critical factor for confinement of LM within macrophage phagosomes.

Alpha-4/beta-1 and alpha-L/beta-2 integrins mediate cytokine induced lung leukocyte-epithelial adhesion and injury

BACKGROUND AND PURPOSE

Injury to the alveolar epithelium is a critical feature of acute lung injury (ALI). Using a cytokine model of ALI we demonstrated previously that newly recruited mononuclear phagocytes (MNP) contributed to lung inflammation and injury. We hypothesized that cytokines delivered into the alveolar airspace would have multiple effects on the lung that may contribute to lung injury.

EXPERIMENTAL APPROACH

Intratracheal cytokine insufflation and leukocyte adoptive transfer in vivo were combined with in vitro analyses of lung epithelial cell-MNP adhesion and injury. Lung inflammatory injury was assessed by histology, leukocyte infiltration, and release of LDH and RAGE.

KEY RESULTS

Cytokine insufflation was associated with apparent MNP-epithelial adhesion, up-regulation of alveolar ICAM-1 and VCAM-1, and the release of LDH and RAGE into the bronchoalveolar lavage. Insufflation of small molecule integrin antagonists suppressed adhesion of MNP and modulated release of LDH and RAGE. Adoptive transfer of MNP purified from cytokine insufflated lungs into leukopenic rats demonstrated the requirement of MNP for release of LDH that was not induced by cytokine alone. Corroboration that disrupting the ICAM/LFA1 interaction or the VCAM/VLA4 interaction blocked MNP-epithelial cell interaction and injury was obtained in vitro using both blocking monoclonal antibodies and the small molecule integrin antagonists, BIO5192 and XVA143.

CONCLUSIONS AND IMPLICATIONS

MNP recruited following cytokine insufflation contributed to lung injury. Further, integrin antagonists reduced alveolar epithelial cell injury induced during lung inflammation. Intratracheal delivery of small molecule antagonsists of leukocyte-epithelial adhesion that prevent lung injury may have significant clinical utility.

P2Y2 nucleotide receptor activation up-regulates vascular cell adhesion molecule-1 [corrected] expression and enhances lymphocyte adherence to a human submandibular gland cell line

Sjögren's syndrome (SS) is a chronic inflammatory autoimmune disease that causes salivary and lacrimal gland tissue destruction resulting in impaired secretory function. Although lymphocytic infiltration of salivary epithelium is associated with SS, the mechanisms involved have not been adequately elucidated. Our previous studies have shown that the G protein-coupled P2Y2 nucleotide receptor (P2Y2R) is up-regulated in response to damage or stress of salivary gland epithelium, and in salivary glands of the NOD.B10 mouse model of SS-like autoimmune exocrinopathy. Additionally, we have shown that P2Y2R activation up-regulates vascular cell adhesion molecule-1 (VCAM-1) expression in endothelial cells leading to the binding of monocytes. The present study demonstrates that activation of the P2Y2R in dispersed cell aggregates from rat submandibular gland (SMG) and in human submandibular gland ductal cells (HSG) up-regulates the expression of VCAM-1. Furthermore, P2Y2R activation mediated the up-regulation of VCAM-1 expression in HSG cells leading to increased adherence of lymphocytic cells. Inhibitors of EGFR phosphorylation and metalloprotease activity abolished P2Y2R-mediated VCAM-1 expression and decreased lymphocyte binding to HSG cells. Moreover, silencing of EGFR expression abolished UTP-induced VCAM-1 up-regulation in HSG cells. These results suggest that P2Y2R activation in salivary gland cells increases the EGFR-dependent expression of VCAM-1 and the binding of lymphocytes, a pathway relevant to inflammation associated with SS.

Dehydroepiandrosterone administration modulates endothelial and neutrophil adhesion molecule expression in vitro

Introduction

The steroid hormone dehydroepiandrosterone (DHEA) exerts protecting effects in the treatment of traumatic and septic complications in several animal models. This effect goes along with reduced amounts of infiltrating immune cells in organs such as lung and liver. However, the underlying mechanisms of DHEA action are still not known. Adhesion molecules are important for the extravasation of neutrophils into organs where they may exhibit detrimental effects. Therefore, we investigated the in vitro effect of DHEA on the expression pattern of adhesion molecules of human endothelial cells and neutrophils.

Methods

Endothelial cells derived from human umbilical cord were subjected to an lipopolysaccharide (LPS) challenge. DHEA was administered in two different concentrations, 10^-5 M and 10^-8 M, as a single stimulus or in combination with LPS challenge. After two, four and 24 hours, fluorescence activated cell sorter (FACS) analysis for vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin was performed. Neutrophils were freshly isolated from blood of 10 male healthy volunteers, stimulated the same way as endothelial cells and analyzed for surface expression of L-selectin, CD11b and CD18.

Results

In the present study, we were able to demonstrate effects of DHEA on the expression of every adhesion molecule investigated. DHEA exhibits opposite effects to those seen upon LPS exposure. Furthermore, these effects are both time and concentration dependent as most DHEA specific effects could be detected in the physiological concentration of 10^-8 M.

Conclusion

Thus, we conclude that one mechanism by which DHEA may exert its protection in animal models is via the differential regulation of adhesion molecule expression.

Sarcoptes scabiei (Acari: Sarcoptidae) mite extract modulates expression of cytokines and adhesion molecules by human dermal microvascular endothelial cells

The inflammatory and immune responses seen with the worldwide disease scabies, caused by the mite Sarcoptes scabiei (De Geer) (Acari: Sarcoptidae), are complex. Clinical symptoms are delayed for weeks in patients when they are infested with scabies for the first time. This study was undertaken to elucidate the role of the human dermal microvascular endothelial cell (HMVEC-D) in modulating the inflammatory and immune responses in the skin to S. scabiei. Extracts of S. scabiei were incubated with HMVEC-D and the expression of adhesion molecules and chemokine receptors on the cells and the secretion of selected cytokines were determined by enzyme-linked immunosorbent assay. S. scabiei extract was found to inhibit HMVEC-D expression of E-selectin and vascular cell adhesion molecule-1, although not intercellular adhesion molecule-1. The secretion of interleukin-8 also was inhibited by S. scabiei extract. S. scabiei extract increased expression of the chemokine receptor CXCR-1 and both down-regulated and up-regulated expression of CXCR-2, depending on the concentration tested. These findings help explain the delayed inflammatory reaction to infestation with S. scabiei.

Contribution of high-mobility group box-1 to the development of ventilator-induced lung injury

RATIONALE

Proinflammatory cytokines play an important role in ventilator-induced lung injury (VILI). High-mobility group box-1 (HMGB1) is a macrophage-derived proinflammatory cytokine that can cause lung injury.

OBJECTIVES

This study tested the hypothesis that HMGB1 is released in intact lungs ventilated with large Vt. A second objective was to identify the source of HMGB1. A third objective was to examine the effects of blocking HMGB1 on the subsequent development of VILI.

METHODS

Bronchoalveolar lavage fluid (BALF) and lung tissues were obtained from rabbits mechanically ventilated for 4 h with a small (8 ml/kg) versus a large (30 ml/kg) Vt. BALF was also obtained from rabbits with intratracheal instillation of anti-HMGB1 antibody before the initiation of large Vt ventilation.

MEASUREMENTS AND MAIN RESULTS

The concentrations of HMGB1 in BALF were fivefold higher in the large than in the small Vt group. Immunohistochemistry and immunofluorescence studies revealed expression of HMGB1 in the cytoplasm of macrophages and neutrophils in lungs ventilated with large Vt. Blocking HMGB1 improved oxygenation, limited microvascular permeability and neutrophil influx into the alveolar lumen, and decreased concentrations of tumor necrosis factor-alpha in BALF.

CONCLUSIONS

These observations suggest that HMGB1 could be one of the deteriorating factors in the development of VILI.

Hypoxia-induced mitogenic factor promotes vascular adhesion molecule-1 expression via the PI-3K/Akt-NF-kappaB signaling pathway

Hypoxia-induced mitogenic factor (HIMF), also known as FIZZ1 (found in inflammatory zone 1), is an important player in lung inflammation. However, the effects of HIMF on cell adhesion molecules involved in lung inflammation remain largely unknown. In the present work, we tested whether HIMF modulates vascular adhesion molecule (VCAM)-1 expression, and dissected the possible signaling pathways that link HIMF to VCAM-1 upregulation. Recombinant HIMF protein, instilled intratracheally into adult mouse lungs, results in a significant increase of VCAM-1 production in vascular endothelial, alveolar type II, and airway epithelial cells. In cultured mouse endothelial SVEC 4-10 and lung epithelial MLE-12 cells, we demonstrated that HIMF induces VCAM-1 expression via the phosphatidylinositol-3 kinase (PI-3K)/Akt-nuclear factor (NF)-kappaB signaling pathway. Knockdown of HIMF expression by small interference RNA attenuated LPS-induced VCAM-1 expression in vitro. We showed that HIMF induced phosphorylation of the IkappaB kinase signalsome and, subsequently, IkappaBalpha, leading to activation of NF-kappaB. Meanwhile, VCAM-1 production was correspondingly upregulated. Blocking NF-kappaB signaling pathway by expression of dominant-negative mutants of IkappaB kinase and IkappaBalpha suppressed HIMF-induced VCAM-1 upregulation. HIMF also strongly induced phosphorylation of Akt. A dominant-negative mutant of PI-3K, Deltap85, as well as PI-3K inhibitor, LY294002, also blocked HIMF-induced NF-kappaB activation and attenuated VCAM-1 production. Furthermore, LY294002 pretreatment abolished HIMF-enhanced mononuclear cells adhesion to endothelial and epithelial cells. Our findings connect HIMF to signaling pathways that regulate inflammation, and thus reveal the critical roles that HIMF plays in lung inflammation.

Neutrophil elastase induces IL-8 gene transcription and protein release through p38/NF-{kappa}B activation via EGFR transactivation in a lung epithelial cell line

In this study, we investigated the regulation and mechanism of IL-8 expression by A549 human lung carcinoma cells treated with neutrophil elastase (NE). NE-treated cells exhibited significantly higher IL-8 protein levels in culture media compared with cells treated with vehicle alone. Blocking of gene transcription with actinomycin D suggested that NE stimulated IL-8 synthesis via increased mRNA expression, which was verified by real-time RT-PCR. NE activated the IL-8 promoter but did not alter the stability of its mRNA, confirming that the protease induced IL-8 synthesis through increased gene transcription. The results from the use of chemical inhibitors and mutant gene constructs against various signal transduction components seem to suggest the linear signaling pathway involving the activation of PKC-delta --> dual oxidase 1 --> reactive oxygen species --> TNF-alpha-converting enzyme --> EGF receptor --> p38 --> NF-kappaB for NE-activated IL-8 gene expression. A NF-kappaB potential binding site, located between nucleotides -82 and -69 of the IL-8 promoter, was identified as necessary for NE-induced IL-8 transcription. We conclude that NE increases IL-8 transcription through p38/NF-kappaB activation via EGFR transactivation.

Cellular and molecular mechanisms of tissue protection by lipophilic calcium channel blockers

Long-acting third-generation dihydropyridine calcium channel blockers (CCBs) improve endothelial dysfunction and prevent cardiovascular events in humans, but their cellular and molecular mechanisms of tissue protection are not elucidated in detail. We assessed organ (renal) protection by the highly lipophilic CCB lercanidipine in a double-transgenic rat (dTGR) model with overexpression of human renin and angiotensinogen genes. We randomly treated dTGR with lercanidipine (2.5 mg/kg/day; n=20) or vehicle (n=20) for 3 wk. Furthermore, we explored the influence of lercanidipine on protein kinase C (PKC) signaling in vivo and in vitro using endothelial and vascular smooth muscle cell cultures. Cumulative mortality was 60% in untreated dTGR, whereas none of the lercanidipine-treated animals died (P<0.001). We found significantly less albuminuria and improved renal function in lercanidipine-treated dTGR (both P<0.05). Lercanidipine treatment also significantly (P<0.05) reduced blood levels of the endogenous NOS inhibitor asymmetric dimethylarginine. On histological examination, we observed significantly less tissue inflammation and fibrosis in lercanidipine-treated animals (both P<0.05). Lercanidipine significantly inhibited angiotensin (ANG) I-mediated PKC-alpha and -delta activation in vivo and in vitro, partly due to reduced intracellular calcium flux. As a result, lercanidipine improved endothelial cell permeability in vitro. Lercanidipine prevents tissue injury and improves survival in a model of progressive organ damage. These effects may result, at least in part, from inhibition of tissue inflammation as well as improved NO bioavailability. Modulation of PKC activity may be an important underlying intracellular mechanism.

Effects of thalidomide on the expression of adhesion molecules in rat liver cirrhosis

This study was to evaluate the effects of thalidomide on expression of adhesion molecules in liver cirrhosis. The cirrhosis was induced in Wistar rats by intraperitoneal injection of CCl(4), and thalidomide (10 mg/kg/day or 100 mg/kg/day) was given by intragastric administration for 8 weeks. Liver histopathology and immunohistochemistry were significantly improved and the expressions of ICAM-1, VCAM-1, E-selectin, and TNF-alpha mRNA and protein were decreased significantly in rats treated with a high dose of thalidomide. Close positive correlation was observed in the expression of the TNF-alpha mRNA and that of ICAM-1, VCAM-1, and E-selectin mRNA, respectively. These results indicate that thalidomide exerts its effect on the downregulation of adhesion molecules via TNF-alpha signaling pathway to inhibit liver fibrosis.

Estrogen signaling multiple pathways to impact gene transcription

Steroid hormones exert profound effects on cell growth, development, differentiation, and homeostasis. Their effects are mediated through specific intracellular steroid receptors that act via multiple mechanisms. Among others, the action mechanism starting upon 17beta-estradiol (E2) binds to its receptors (ER) is considered a paradigmatic example of how steroid hormones function. Ligand-activated ER dimerizes and translocates in the nucleus where it recognizes specific hormone response elements located in or near promoter DNA regions of target genes. Behind the classical genomic mechanism shared with other steroid hormones, E2 also modulates gene expression by a second indirect mechanism that involves the interaction of ER with other transcription factors which, in turn, bind their cognate DNA elements. In this case, ER modulates the activities of transcription factors such as the activator protein (AP)-1, nuclear factor-kappaB (NF-kappaB) and stimulating protein-1 (Sp-1), by stabilizing DNA-protein complexes and/or recruiting co-activators. In addition, E2 binding to ER may also exert rapid actions that start with the activation of a variety of signal transduction pathways (e.g. ERK/MAPK, p38/MAPK, PI3K/AKT, PLC/PKC). The debate about the contribution of different ER-mediated signaling pathways to coordinate the expression of specific sets of genes is still open. This review will focus on the recent knowledge about the mechanism by which ERs regulate the expression of target genes and the emerging field of integration of membrane and nuclear receptor signaling, giving examples of the ways by which the genomic and non-genomic actions of ERs on target genes converge.