Double-Stranded RNA Interacts With Toll-Like Receptor 3 in Driving the Acute Inflammatory Response Following Lung Contusion.

OBJECTIVES: Lung contusion is a major risk factor for the development of acute respiratory distress syndrome. We set to determine the role of toll-like receptor 3 and the binding of double-stranded RNA in the pathogenesis of sterile injury following lung contusion. DESIGN: Toll-like receptor 3 expression was analyzed in postmortem lung samples from patients with lung contusion. Unilateral lung contusion was induced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-ß (-/-), and wild-type mice. Subsequently, lung injury and inflammation were evaluated. Apoptotic indices, phagocytic activity, and phenotypic characterization of the macrophages were determined. Double-stranded RNA in bronchoalveolar lavage and serum samples following lung contusion was measured. A toll-like receptor 3/double-stranded RNA ligand inhibitor was injected into wild-type mice prior to lung contusion. MEASUREMENTS AND MAIN RESULTS: Toll-like receptor 3 expression was higher in patients and wild-type mice with lung contusion. The degree of lung injury, inflammation, and macrophage apoptosis was reduced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-ß (-/-), and wild-type mice with toll-like receptor 3 antibody neutralization. Alveolar macrophages from toll-like receptor 3 (-/-) mice had a lower early apoptotic index, a predominant M2 phenotype and increased surface translocation of toll-like receptor 3 from the endosome to the surface. When compared with viral activation pathways, lung injury in lung contusion demonstrated increased p38 mitogen-activated protein kinases, extracellular signal-regulated kinase 1/2 phosphorylation with inflammasome activation without a corresponding increase in nuclear factor-κB or type-1 interferon production. Additionally, pretreatment with toll-like receptor 3/double-stranded RNA ligand inhibitor led to a reduction in injury, inflammation, and macrophage apoptosis. CONCLUSIONS: We conclude that the interaction of double-stranded RNA from injured cells with toll-like receptor 3 drives the acute inflammatory response following lung contusion.

Activation of hypoxia-inducible factor-1α in type 2 alveolar epithelial cell is a major driver of acute inflammation following lung contusion.

OBJECTIVE: Lung contusion is a major risk factor for the development of acute respiratory distress syndrome. Hypoxia-inducible factor-1α is the primary transcription factor that is responsible for regulating the cellular response to changes in oxygen tension. We set to determine if hypoxia-inducible factor-1α plays a role in the pathogenesis of acute inflammatory response and injury in lung contusion. DESIGN: Nonlethal closed-chest unilateral lung contusion was induced in a hypoxia reporter mouse model and type 2 cell-specific hypoxia-inducible factor-1α conditional knockout mice. The mice were killed at 5-, 24-, 48-, and 72-hour time points, and the extent of systemic and tissue hypoxia was assessed. In addition, injury and inflammation were assessed by measuring bronchoalveolar lavage cells (flow cytometry and cytospin), albumin (permeability injury), and cytokines (inflammation). Isolated type 2 cells from the hypoxia-inducible factor-1α conditional knockout mice were isolated and evaluated for proinflammatory cytokines following lung contusion. Finally, the role of nuclear factor-κB and interleukin-1ß as intermediates in this interaction was studied. RESULTS: Lung contusion induced profound global hypoxia rapidly. Increased expression of hypoxia-inducible factor-1α from lung samples was observed as early as 60 minutes, following the insult. The extent of lung injury following lung contusion was significantly reduced in conditional knockout mice at all the time points, when compared with the wild-type littermate mice. Release of proinflammatory cytokines, such as interleukin-1ß, interleukin-6, macrophage inflammatory protein-2, and keratinocyte chemoattractant, was significantly lower in conditional knockout mice. These actions are in part mediated through nuclear factor-κB. Hypoxia-inducible factor-1α in lung epithelial cells was shown to regulate interleukin-1ß promoter activity. CONCLUSION: Activation of hypoxia-inducible factor-1α in type 2 cell is a major driver of acute inflammation following lung contusion.

The protective role of MnTBAP in oxidant-mediated injury and inflammation in a rat model of lung contusion.

BACKGROUND: Lung contusion (LC) is a unique direct and focal insult that is considered a major risk factor for the initiation of acute lung injury and acute respiratory distress syndrome. We have shown recently that consumption of nitric oxide (due to excess superoxide) resulting in peroxynitrite formation leads to decreased vascular reactivity after LC. In this study, we set out to determine whether the superoxide scavenger Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) plays a protective role in alleviating acute inflammatory response and injury in LC. METHODS: Nonlethal, closed-chest, bilateral LC was induced in a rodent model. Administration of the superoxide dismutase mimetic MnTBAP concurrently in LC in rats was performed, and bronchoalveolar lavage (BAL) and lung samples were analyzed for degree of injury and inflammation at 5 and 24 h after the insult. The extent of injury was assessed by the measurement of cells and albumin with cytokine levels in the BAL and lungs. Lung samples were subjected to H&E and superoxide staining with dihydro-ethidium. Protein-bound dityrosine and nitrotyrosine levels were quantified in lung tissue by tandem mass spectrometry. RESULTS: The degrees of lung injury after LC as determined by BAL albumin levels were significantly decreased in the MnTBAP-administered rats at all the time points when compared to the corresponding controls. The release of proinflammatory cytokines and BAL neutrophils was significantly less in the rats administered MnTBAP after LC. Administration of MnTBAP decreased tissue damage and decreased necrosis and neutrophil-rich exudate at the 24-h time point. Staining for superoxide anions showed significantly greater intensity in the lung samples from the LC group compared to the LC+ MnTBAP group. High-performance liquid chromatography/tandem mass spectrometry revealed that MnTBAP treatment significantly attenuated dityrosine and nitrotyrosine levels, consistent with decreased oxidant injury. CONCLUSION: Superoxide dismutase mimetic-MnTBAP reduced permeability and oxidative injury in LC and may have a therapeutic role in diminishing inflammation in LC.

Role of the CCL21 and CCR7 pathways in rheumatoid arthritis angiogenesis.

OBJECTIVE: To determine the role of CCL21 and its receptor CCR7 in the pathogenesis of rheumatoid arthritis (RA). METHODS: Histologic studies were performed to compare the expression of CCR7 and CCL21 in RA synovial tissue. Next, the role of CCL21 and/or CCR7 in angiogenesis was examined using in vitro chemotaxis, tube formation, and in vivo Matrigel plug assays. Finally, the mechanism by which CCL21 mediates angiogenesis was determined by Western blot analysis and endothelial cell chemotaxis and tube formation assays. RESULTS: CCL21, but not CCL19, at concentrations present in the RA joint, induced human microvascular endothelial cell (HMVEC) migration that was mediated through CCR7 ligation. Suppression of the phosphatidylinositol 3-kinase pathway markedly reduced CCL21-induced HMVEC chemotaxis and tube formation; however, suppression of the ERK and JNK pathways had no effect on these processes. Neutralization of either CCL21 in RA synovial fluid or CCR7 in HMVECs significantly reduced the induction of HMVEC migration and/or tube formation by RA synovial fluid. We further demonstrated that CCL21 is angiogenic, by showing its ability to promote blood vessel growth in Matrigel plugs in vivo at concentrations that are present in RA joints. CONCLUSION: Angiogenesis is dependent on endothelial cell activation, migration, and proliferation, and inhibition of angiogenesis may provide a novel therapeutic approach in RA. This study identified a novel function of CCL21 as a mediator of RA angiogenesis, supporting CCL21/CCR7 as a therapeutic target in RA.

Characterization of interleukin-7 and interleukin-7 receptor in the pathogenesis of rheumatoid arthritis.

OBJECTIVE: To characterize the expression of interleukin-7 (IL-7) and IL-7 receptor (IL-7R) in rheumatoid arthritis (RA) synovial tissue and to examine their regulation and pathogenic role in macrophages, endothelial cells, and synovial tissue fibroblasts in RA. METHODS: Expression of IL-7 and IL-7R in RA and normal synovial tissue was demonstrated by immunohistochemistry. Expression and regulation of IL-7 and IL-7R in RA peripheral blood in vitro-differentiated macrophages, RA synovial tissue fibroblasts, and human microvascular endothelial cells (HMVECs) were determined by real-time reverse transcription-polymerase chain reaction and/or flow cytometry. Enzyme-linked immunosorbent assay was used to examine production of proangiogenic factors by IL-7-activated macrophages, RA fibroblasts, and endothelial cells. RESULTS: IL-7 and IL-7R were coexpressed on RA synovial tissue lining and sublining macrophages and endothelial cells. Expression of IL-7 and its receptor was significantly elevated in RA synovial fluid and peripheral blood macrophages as well as RA fibroblasts, compared to normal cells. Toll-like receptor 4 ligation (with lipopolysaccharide) and tumor necrosis factor α (TNFα) stimulation modulated expression of IL-7 and IL-7R on RA macrophages and HMVECs. However, in RA fibroblasts, lipopolysaccharide and TNFα activation increased expression of IL-7R only. IL-7 also mediated RA pathogenesis by inducing production of potent proangiogenic factors from macrophages and endothelial cells. CONCLUSION: We have identified, for the first time, regulators of IL-7 and IL-7R expression in RA fibroblasts, RA peripheral blood in vitro-differentiated macrophages, and endothelial cells. Our results document a novel role of IL-7 in RA angiogenesis.

Histopathologic and immunohistochemical characterization of rash to human epidermal growth factor receptor 1 (HER1) and HER1/2 inhibitors in cancer patients.

PURPOSE: Human epidermal growth factor receptor (HER) 1 and HER 1/2 inhibitors have shown benefit against a wide range of solid tumors. However, their use is associated with rash in 40% to 90% of patients, which impacts quality of life and interrupts antineoplastic therapy. The pathologic characteristics of affected skin remain unclear, precluding development of rational therapies. The aim of this study was to evaluate differences in histologic and immunohistochemical alterations in rash caused by lapatinib, a dual HER1/2 inhibitor (HER1/2i), and the single HER1 inhibitors (HER1i) cetuximab, erlotinib, and panitumumab. EXPERIMENTAL DESIGN: For each of the four drugs, skin biopsies were collected and analyzed from 8 patients with rash (n = 32). Blinded independent histologic analysis and automated measurement of 17 skin biomarkers involved in proliferation, differentiation, and inflammation were conducted. RESULTS: Increased expression of pAKT and decreased dermal K16 and p27 for HER1/2i when compared with each of the HER1i were observed. In addition, decreased epidermal atrophy and follicular neutrophilic infiltrate were evidenced in the skin of patients on HER1/2i when compared with HER1i. CONCLUSIONS: We found a lower inhibition of epidermal kinetics and decreased inflammation in HER1/2i-induced rash. These findings underscore differences in skin toxicity as related to specificity of HER blockade, concordant with clinical tolerability and decreased severity of skin toxicity seen with the HER1/2i lapatinib compared with the HER1 inhibitors cetuximab, erlotinib, and panitumumab.

Inhibition of choroidal neovascularization by a peptide inhibitor of the urokinase plasminogen activator and receptor system in a mouse model.

OBJECTIVES: To determine the role played by the urokinase plasminogen activator (uPA) and urokinase plasminogen activator receptor (uPAR) system in choroidal neovascularization (CNV) and whether inhibition of this system can suppress the extent of CNV in an animal model. METHODS: Choroidal neovascularization was induced in mice by laser photocoagulation using the slitlamp delivery system. Reverse transcriptase-polymerase chain reaction and immunocytochemical analysis were performed on the retina choroids of these animals to examine the expression of uPAR. For 2 weeks following laser treatment, animals were injected intraperitoneally with a novel peptide inhibitor of the uPA-uPAR system (100 mg/kg twice a day every day, every other day, and once a week). Control laser-treated animals receive an intraperitoneal injection of phosphate-buffered saline every day. Following treatment, animals were perfused with fluorescein-labeled dextran, eyes were removed, and the areas of new vessels were examined in the retina-choroid whole mounts by fluorescence microscopy and quantitated using image analysis software. RESULTS: In this study, uPAR was found to be up-regulated in the choroidal tissues of mice with laser-induced CNV. The uPAR was localized to the endothelial cells of the fibrovascular tissue within the CNV complex. Systemic administration of the peptide inhibitor of the uPA-uPAR system resulted in a significant reduction of CNV (up to 94%). The response was found to be frequency-of-dose dependent. No toxic effects or tissue destruction was noted following the peptide treatment. CONCLUSIONS: Our results strongly suggest that up-regulation of the uPA-uPAR system is an important step during CNV, and significant inhibition of CNV was seen when cell surface-associated uPA-uPAR activity was prevented with the peptide inhibitor. Clinical Relevance Inhibition of the protease system (uPA-uPAR) may prove to be a potential novel antiangiogenic therapy for CNV as seen in age-related macular degeneration.

Angiopoietin/Tek interactions regulate mmp-9 expression and retinal neovascularization.

The objective of the study was to determine the role of the angiopoietins in the regulation of gelatinase expression during angiogenesis, and whether inhibition of the angiopoietin/Tek interaction in vivo can suppress the extent of retinal neovascularization. Retinal microvascular endothelial cells were treated with angiopoietins and examined for the production of gelatinases. The effects of inhibiting angiopoietin binding to the Tie-2 receptor was studied in newborn mice with experimentally induced retinal neovascularization. Animals were treated with an ip injection of the Tie-2 antagonist, muTek delta Fc, while oxygen-exposed mice treated with similar concentrations of murine IgG were used as controls. The effect of muTek delta Fc on the gelatinase expression in the retina was examined by real-time RT-PCR analysis. The stimulation of cultured retinal endothelial cells with Ang-1 and -2 resulted in the increased expression of matrix metalloproteinase (MMP)-9. Ang-2 expression was up-regulated in experimental animals during the period of angiogenesis and was the greatest on Day 17 (the time of maximal angiogenic response). Histologic analysis of mice treated with the Tie-2 antagonist, muTek delta Fc, showed significant (87%; p = 0.001) inhibition of retinal neovascularization, and the response was dose-dependent. In vitro binding data support the fact that both Ang-1 and Ang-2 bind with high avidity to muTek delta Fc. The RT-PCR analysis of the retinas of the Tek-treated animals showed a similar (80%; p = 0.001) inhibition of the MMP-9 expression, which correlated with the decrease in angiogenesis. The up-regulation of gelatinases in microvascular endothelial cells by Ang-2 may be an important early response during the development of retinal neovascularization. Inhibition of the binding activity of the angiopoietins in vivo suppressed retinal neovascularization concomitant with a reduction in the expression of MMP-9.

The urokinase/urokinase receptor system in retinal neovascularization: inhibition by A6 suggests a new therapeutic target.

PURPOSE: The objective of the study was to determine the role of urokinase (uPA) and the urokinase receptor (uPAR) in retinal angiogenesis, and whether loss of uPAR or the inhibition of uPA/uPAR interactions could suppress the extent of retinal neovascularization in an animal model of ischemic retinopathy. METHODS: Retinal neovascularization was induced by exposing newborn mice to 75% oxygen on postnatal day 7 for 5 days, followed by exposure to room air on days 12 to 17. The expression of uPAR in the retina was investigated by RT-PCR and immunohistochemistry. The role of uPAR in ischemic retinopathy was investigated by quantitating the extent of retinal neovascularization in the uPAR(-/-) mouse. The effects of inhibiting the uPA/uPAR interaction on the development of retinal neovascularization were studied in this animal model with a uPA-derived peptide, A6. Animals were treated with an intraperitoneal injection of A6 at a dose of 5, 10, or 100 mg/kg once a day on days 12 to 16. Control animals included oxygen-exposed mice treated with similar amounts of PBS only on days 12 to 16. The effect of A6 on the expression of uPAR in the retina was examined by real-time RT-PCR. RESULTS: The expression of uPAR mRNA was upregulated in experimental animals during the period of angiogenesis and was localized to endothelial cells in the superficial layers of the retina. The uPAR(-/-) mouse demonstrated normal retinal vascular development; however, the absence of functional uPAR resulted in a significant reduction in the extent of retinal neovascularization. Histologic analysis of mice treated with A6 peptide showed significant inhibition of retinal neovascularization, and the response was dose dependent. The RT-PCR analysis of the retinas of the A6-treated animals showed a greater than twofold decrease in uPAR expression. CONCLUSIONS: Expression of the urokinase receptor uPAR is essential to the development of retinal neovascularization. Inhibition of the activity of uPAR suppresses retinal neovascularization, possibly through a reduction in cell-associated proteolytic activity, cell signaling, or cell-matrix adhesion necessary for cell migration during angiogenesis. The uPA/uPAR interaction may be an important therapeutic target in the management of proliferative retinopathies.