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Thorburn, Alison N.; Hansbro, Philip M.
doi: 10.1165/rcmb.2009-0342trpmid: 20097830
Regulatory T cells (Tregs) play an essential role in maintaining the homeostatic balance of immune responses. Asthma is an inflammatory condition of the airways that is driven by dysregulated immune responses toward normally innocuous antigens. Individuals with asthma have fewer and less functional Tregs, which may lead to uncontrolled effector cell responses and promote proasthmatic responses of T helper type 2, T helper 17, natural killer T, antigen-presenting, and B cells. Tregs have the capacity to either directly or indirectly suppress these responses. Hence, the induced expansion of functional Tregs in predisposed or individuals with asthma is a potential approach for the prevention and treatment of asthma. Infection by a number of micro-organisms has been associated with reduced prevalence of asthma, and many infectious agents have been shown to induce Tregs and reduce allergic airways disease in mouse models. The translation of the regulatory and therapeutic properties of infectious agents for use in asthma requires the identification of key modulatory components and the development and trial of effective immunoregulatory therapies. Further translational and clinical research is required for the induction of Tregs to be harnessed as a therapeutic strategy for asthma.
McGee, Halvor S.; Stallworth, Arthur L.; Agrawal, Tanupriya; Shao, Zhifei; Lorence, Lindsey; Agrawal, Devendra K.
doi: 10.1165/rcmb.2009-0241ocpmid: 19933379
We previously reported that Fms-like tyrosine kinase 3 ligand (Flt3-L) reversed airway hyperresponsiveness (AHR) and airway inflammation, and increased the number of regulatory CD11chighCD8αhighCD11blow dendritic cells and CD4+CD25+ICOS+Foxp3+IL-10+ T-regulatory cells in the lung of allergen-sensitized and -challenged mice. In this study, we evaluated the effect of Flt3-L on Th17 cells and expression of suppressors of cytokine signaling (SOCS) proteins in the lungs of house dust mite (HDM)–sensitized and –challenged mice. BALB/c mice were sensitized and challenged with HDM, and AHR to methacholine was established. Mice were treated with Flt3-L (5 μg, intraperitoneal) daily for 10 days. Levels of IL-4, -5, -6, -8, and -13, and transforming growth factor (TGF)–β in the bronchoalveolar lavage fluid (BALF) were examined by ELISA. Flt3-L treatment reversed existing AHR to methacholine and substantially decreased eosinophils, neutrophils, IL-5, -6, -8, and IL-13, and TGF-β levels in the BALF. HDM-sensitized and -challenged mice showed a significant increase in lung CD4+IL-17+IL-23R+CD25− T cells with high expression of retinoic acid–related orphan receptor (ROR)–γt transcripts. However, administration of Flt3-L substantially decreased the number of lung CD4+IL-17+IL-23R+CD25− T cells, with significantly decreased expression of ROR-γt mRNA in these cells. HDM sensitization caused a significant increase in the expression of SOCS-1, -3, and -5 in the lung. Flt3-L treatment abolished the increase in SOCS-1 and SOCS-3 proteins, whereas SOCS-5 expression was significantly reduced. These data suggest that the therapeutic effect of Flt3-L in reversing the hallmarks of allergic asthma in a mouse model is mediated by decreasing IL-6 and TGF-β levels in the BALF, which, in turn, decrease CD4+IL-17+IL-23R+ROR-γt+CD25− T cells and the expression of SOCS-1 and SOCS-3 in the lung of HDM-sensitized and -challenged mice.
Liu, Po-Len; Tsai, Jong-Rung; Hwang, Jhi-Jhu; Chou, Shah-Hwa; Cheng, Yu-Jen; Lin, Feng-Yen; Chen, Yuh-Lien; Hung, Chun-Ying; Chen, Wen-Chi; Chen, Yung-Hsiang; Chong, Inn-Wen
Oldenburg, Peter J.; Wyatt, Todd A.; Sisson, Joseph H.
doi: 10.1165/rcmb.2009-0252ocpmid: 19933378
Airway smooth muscle cells are the main effector cells involved in airway narrowing and have been used to study the signaling pathways involved in asthma-induced airway constriction. Our previous studies demonstrated that ethanol administration to mice attenuated methacholine-stimulated increases in airway responsiveness. Because ethanol administration attenuates airway responsiveness in mice, we hypothesized that ethanol directly blunts the ability of cultured airway smooth muscle cells to shorten. To test this hypothesis, we measured changes in the size of cultured rat airway smooth muscle (RASM) cells exposed to ethanol (100 mM) after treatment with methacholine. Ethanol markedly attenuated methacholine-stimulated cell shortening (methacholine-stimulated length change = 8.3 ± 1.2% for ethanol versus 43.9 ± 1.5% for control; P < 0.001). Ethanol-induced inhibition of methacholine-stimulated cell shortening was reversible 24 hours after removal of alcohol. To determine if ethanol acts through a cGMP-dependent pathway, incubation with ethanol for as little as 15 minutes produced a doubling of cGMP-dependent protein kinase (PKG) activity. Furthermore, treatment with the PKG antagonist analog Rp-8Br-cGMPS (10 μM) inhibited ethanol-induced kinase activation when compared with control-treated cells. In contrast to the effect of ethanol on PKG, ethanol pretreatment did not activate a cAMP-dependent protein kinase. These data demonstrate that brief ethanol exposure reversibly prevents methacholine-stimulated RASM cell contraction. In addition, it appears that this effect is the result of activation of the cGMP/PKG kinase pathway. These findings implicate a direct effect of ethanol on airway smooth muscle cells as the basis for in vivo ethanol effects.
Ormiston, Mark L.; Deng, Yupu; Stewart, Duncan J.; Courtman, David W.
doi: 10.1165/rcmb.2009-0152ocpmid: 19995942
Direct injection of endothelial progenitor cells (EPCs) into the circulation has shown therapeutic benefit in both experimental models and clinical studies of pulmonary arterial hypertension (PAH). Using the monocrotaline (MCT)-induced rat model of PAH, we investigated the role of innate immunity in the therapeutic activity of two types of putative EPCs derived from human peripheral blood mononuclear cells: an early population of endothelial-like, culture-modified monocytes (E-CMMs) and late-outgrowth EPCs (L-EPCs), which exhibit a strong endothelial phenotype. In the athymic nude rat, E-CMMs prevented MCT-induced increases in right ventricular systolic pressure (P < 0.001) and right ventricular hypertrophy (P < 0.01) when administered 3 days after MCT challenge, whereas L-EPCs were ineffective. However, in both cases, there was a lack of cell persistence within the lungs at 24 hours after injection, likely due to residual natural killer (NK) cell activity in the model. Although ablation of NK and NK-T cells with anti–asialo–GM-1 antiserum enhanced the retention of both E-CMMs and L-EPCs, still no benefit was seen with L-EPCs, and the efficacy of E-CMMs was lost. In vitro characterization revealed that E-CMMs resemble a regulatory subtype of dendritic cells, producing IL-10, but not IL-12, in response to inflammatory stimuli. Coculture studies demonstrated the capacity of E-EPCs to stimulate autologous human and nude rat NK cells in vitro. These data support a novel mode of action for human E-CMMs in the prevention of PAH, whereby they act through an immune-dependent mechanism, potentially involving the stimulation of NK cells.
Albaiceta, Guillermo M.; Gutierrez-Fernández, Ana; García-Prieto, Emilio; Puente, Xose S.; Parra, Diego; Astudillo, Aurora; Campestre, Cristina; Cabrera, Sandra; Gonzalez-Lopez, Adrian; Fueyo, Antonio; Taboada, Francisco; López-Otin, Carlos
Morin, Caroline; Sirois, Marco; Échavé, Vincent; Albadine, Roula; Rousseau, Eric
doi: 10.1165/rcmb.2009-0155ocpmid: 20008283
This study sought to assess putative pathways involved in the anti-inflammatory effects of 17,18-epoxyeicosatetraenoic acid (17,18-EpETE), as measured by a decrease in the contractile reactivity and Ca2+ sensitivity of TNF-α–pretreated human bronchi. Tension measurements performed in the presence of 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), a soluble epoxide hydrolase (sEH)–specific inhibitor, demonstrated that 17,18-EpETE reduced the reactivity of TNF-α–pretreated tissues. The overexpression of sEH detected in patients with asthma and TNF-α–treated bronchi contributed to the maintenance of hyperresponsiveness in our models, which involved intracellular proinflammatory cascades. The inhibition of peroxisome proliferator–activated receptor (PPAR)γ by GW9662 abolished 17,18-EpETE + AUDA–mediated anti-inflammatory effects by inducing IκBα degradation and cytokine synthesis, indicating that PPARγ is a molecular target of epoxy–eicosanoids. Western blot analysis revealed that 17,18-EpETE pretreatment reversed the phosphorylation of p38 mitogen–activated protein kinase (p38-MAPK) induced by TNF-α in human bronchi. The Ca2+ sensitivity of human bronchial explants was also quantified on β-escin permeabilized preparations. The presence of SB203580, a p38-MAPK inhibitor, reversed the effect induced by epoxy–eicosanoid in the presence of AUDA on TNF-α–triggered Ca2+ hypersensitivity by increasing the phosphorylation level of PKC Potentiated Inhibitor Protein-17 (CPI-17) regulatory protein. Moreover, PPARγ ligands, such as rosiglitazone and 17,18-EpETE, decreased the expression of CPI-17, both at the mRNA and protein levels, whereas this effect was countered by GW9662 treatment in TNF-α–treated bronchi. These results demonstrate that 17,18-EpETE is a potent regulator of human lung inflammation and concomitant hyperresponsiveness, and may represent a valuable asset against critical inflammatory bronchial disorder.
Deslee, Gaetan; Adair-Kirk, Tracy L.; Betsuyaku, Tomoko; Woods, Jason C.; Moore, Carla H.; Gierada, David S.; Conradi, Susan H.; Atkinson, Jeffrey J.; Toennies, Holly M.; Battaile, John T.; Kobayashi, Dale K.; Patterson, G. Alexander; Holtzman, Michael J.; Pierce, Richard A.
Nypaver, Christina M.; Thornton, Margaret M.; Yin, Suellen M.; Bracho, David O.; Nelson, Patrick W.; Jones, Alan E.; Bortz, David M.; Younger, John G.
doi: 10.1165/rcmb.2009-0292ocpmid: 20008281
With an in vitro system that used a luminescent strain of Klebsiella pneumoniae to assess bacterial metabolic activity in near-real-time, we investigated the dynamics of complement-mediated attack in healthy individuals and in patients presenting to the emergency department with community-acquired severe sepsis. A novel mathematical/statistical model was developed to simplify light output trajectories over time into two fitted parameters, the rate of complement activation and the delay from activation to the onset of killing. Using Factor B–depleted serum, the alternative pathway was found to be the primary bactericidal effector: In the absence of B, C3 opsonization as measured by flow cytometry did not progress and bacteria proliferated near exponentially. Defects in bacterial killing were easily demonstrable in patients with severe sepsis compared with healthy volunteers. In most patients with sepsis, the rate of activation was higher than in normal subjects but was associated with a prolonged delay between activation and bacterial killing (P < 0.05 for both). Theoretical modeling suggested that this combination of accentuated but delayed function should allow successful bacterial killing but with significantly greater complement activation. The use of luminescent bacteria allowed for the development of a novel and powerful tool for assessing complement immunology for the purposes of mechanistic study and patient evaluation.
Showing 1 to 10 of 14 Articles
High-mobility group box 1 (HMGB1) is a versatile protein with intranuclear and extracellular functions. It is involved in invasion and metastasis in various human malignancies. However, the role of HMGB1 in non–small cell lung cancer (NSCLC) is unclear. We hypothesized that HMGB1 expression is a determinant of cellular invasiveness and metastasis in lung cancer. We examined HMGB1 expression in 48 NSCLC specimens by quantitative real-time PCR. High HMGB1 expression was significantly associated with clinically advanced stages (stage III–IV) (P < 0.05) and was correlated to expression of matrix metalloproteinase-9 (MMP-9) (P < 0.05). Patients with high levels of HMGB1 expression had poorer clinical prognosis. The expression level of MMP-9 and metastatic ability in vitro were significantly higher in an HMGB1-overexpressing human NSCLC cell lines (A549 and H23). The treatment with HMGB1 small interfering RNA reduced MMP-9 expression and the cellular metastatic ability in NSCLC cells. We also demonstrated that phosphoinositide 3-kinase/Akt and NF-κB–related pathways contributed to the HMGB1-induced MMP-9 expression and cellular metastatic ability.
doi: 10.1165/rcmb.2009-0034ocpmid: 19995943
Mechanical ventilation is a life-saving therapy that can also damage the lungs. Ventilator-induced lung injury (VILI) promotes inflammation and up-regulates matrix metalloproteinases (MMPs). Among these enzymes, MMP-8 is involved in the onset of inflammation by processing different immune mediators. To clarify the role of MMP-8 in a model of VILI and their relevance as a therapeutic target, we ventilated wild-type and MMP-8–deficient mice with low or high pressures for 2 hours. There were no significant differences after low-pressure ventilation between wild-type and knockout animals. However, lack of MMP-8 results in better gas exchange, decreased lung edema and permeability, and diminished histological injury after high-pressure ventilation. Mmp8−/− mice had a different immune response to injurious ventilation, with decreased neutrophilic infiltration, lower levels of IFN-γ and chemokines (LPS-induced CXC chemokine, macrophage inflammatory protein–2), and significant increases in anti-inflammatory cytokines (IL-4, IL-10) in lung tissue and bronchoalveolar lavage fluid. There were no differences in MMP-2, MMP-9, or tissue inhibitor of metalloproteinase–1 between wild-type and knockout mice. These results were confirmed by showing a similar protective effect in wild-type mice treated with a selective MMP-8 inhibitor. We conclude that MMP-8 promotes acute inflammation after ventilation with high pressures, and its short-term inhibition could be a therapeutic goal to limit VILI.
doi: 10.1165/rcmb.2009-0221ocpmid: 20008282
Oxidative stress is widely proposed as a pathogenic mechanism for chronic obstructive pulmonary disease (COPD), but the molecular pathway connecting oxidative damage to tissue destruction remains to be fully defined. We suggest that reactive oxygen species (ROS) oxidatively damage nucleic acids, and this effect requires multiple repair mechanisms, particularly base excision pathway components 8-oxoguanine-DNA glycosylase (OGG1), endonuclease III homologue 1 (NTH1), and single-strand–selective monofunctional uracil-DNA glycosylase 1 (SMUG1), as well as the nucleic acid-binding protein, Y-box binding protein 1 (YB1). This study was therefore designed to define the levels of nucleic-acid oxidation and expression of genes involved in the repair of COPD and in corresponding models of this disease. We found significant oxidation of nucleic acids localized to alveolar lung fibroblasts, increased levels of OGG1 mRNA expression, and decreased concentrations of NTH1, SMUG1, and YB1 mRNA in lung samples from subjects with very severe COPD compared with little or no COPD. Mice exposed to cigarette smoke exhibited a time-dependent accumulation of nucleic-acid oxidation in alveolar fibroblasts, which was associated with an increase in OGG1 and YB1 mRNA concentrations. Similarly, human lung fibroblasts exposed to cigarette smoke extract exhibited ROS-dependent nucleic-acid oxidation. The short interfering RNA (siRNA)-dependent knockdown of OGG1 and YB1 expression increased nucleic-acid oxidation at the basal state and after exposure to cigarette smoke. Together, our results demonstrate ROS-dependent, cigarette smoke-induced nucleic-acid oxidation in alveolar fibroblasts, which may play a role in the pathogenesis of emphysema.