The Escherichia coli TolC efflux pump protein is immunogenic and elicits protective antibodies.

Antimicrobial resistance is an increasing worldwide public health burden that threatens to make existent antimicrobials obsolete. An important mechanism of antimicrobial resistance is the overexpression of efflux pumps, which reduce the intracellular concentration of antimicrobials. TolC is the outer membrane protein of an efflux pump that has gained attention as a therapeutic target. Little is known about the immune response against TolC. Here we evaluated the immune response against TolC from Escherichia coli. TolC in silico epitope prediction showed several residues that could bind to human antibodies, and we showed that human plasma presented higher titers of anti-TolC IgG and IgA, than IgM. E. coli recombinant TolC protein stimulated macrophages in vitro to produce nitric oxide, as well as IL-6 and TNF-α, assessed by Griess assay and ELISA, respectively. Immunization of mice with TolC intraperitoneally and an in vitro re-stimulation led to increased T cell proliferation and IFNγ production, evaluated by flow cytometry and ELISA, respectively. TolC mouse immunization stimulated anti-TolC IgM and IgG production, with higher levels of IgG1 and IgG2, amongst the IgG subclasses. Anti-TolC murine antibodies could bind to live E. coli and increase bacterial uptake and elimination by macrophages in vitro. Intraperitoneal or intranasal, but not oral, immunizations with inactivated E. coli also led to anti-TolC antibody production. Finally, TolC immunization increased mouse survival rates to antimicrobial-sensitive or resistant E. coli infection. Our results showed that TolC is immunogenic, leading to the production of protective antibodies against E. coli, reinforcing its value as a therapeutic target.

Bacterial efflux pump OMPs as vaccine candidates against Multidrug-Resistant Gram-negative bacteria.

The emergence and propagation of bacteria resistant to antimicrobial drugs is a serious public health threat worldwide. The current antibacterial arsenal is becoming obsolete and the pace of drug development is decreasing, highlighting the importance of investment in alternative approaches to treat or prevent infections caused by antimicrobial-resistant bacteria. A significant mechanism of antimicrobial resistance employed by Gram-negative bacteria is the overexpression of efflux pumps that can extrude several compounds from the bacteria, including antimicrobials. The overexpression of efflux pump proteins has been detected in several multidrug resistant (MDR) Gram-negative bacteria, drawing attention to these proteins as potential targets against these pathogens. This review will focus on the role of outer membrane proteins (OMPs) from efflux pumps as potential vaccine candidates against clinically relevant MDR Gram-negative bacteria, discussing advantages and pitfalls. Additionally, we will explore the relevance of efflux pump OMP diversity and the possible impact of vaccination on microbiota.

MIF is essential to the establishment of house dust mite-induced airway inflammation and tissue remodeling in mice.

Macrophage migration inhibitory factor (MIF) is present in high amounts in the BALF and serum of asthmatic patients, contributing to the pathogenesis of experimental asthma induced by OVA in mice. Whether MIF contributes to the physiopathology on a more complex and relevant asthma model has not been characterized. Mif-deficient (Mif-/- ) or WT mice treated with anti-MIF antibody were challenged multiple times using house dust mite (HDM) extract by the intranasal route. HDM-challenged Mif-/- mice presented decreased airway hyperresponsiveness, lung infiltration of eosinophils, mucus hypersecretion, and subepithelial fibrosis compared to HDM-challenged WT mice. Amounts of IL-4, IL-5, and IL-13 were decreased in the lungs of Mif-/- mice upon HDM challenges, but the increase of CCL11 was preserved, compared to HDM-challenged WT mice. We also observed increased numbers of group 2 innate lymphoid cells and Th2 cells in the BALF and mediastinal LNs (mLN)-induced challenged by HDM of WT mice, but not in HDM-challenged Mif-/- mice. Anti-MIF treatment abrogated the airway infiltration of eosinophils, mucus hypersecretion, and subepithelial fibrosis in the lungs of HDM-challenged mice. In conclusion, MIF ablation prevents the pathologic hallmarks of asthma in HDM-challenged mice, reinforcing the promising target of MIF for asthma therapy.

The Role of MIF on Eosinophil Biology and Eosinophilic Inflammation.

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that participates in innate and adaptive immune responses. MIF contributes to the resistance against infection agents, but also to the cellular and tissue damage in infectious, autoimmune, and allergic diseases. In the past years, several studies demonstrated a critical role for MIF in the pathogenesis of type-2-mediated inflammation, including allergy and helminth infection. Atopic patients have increased MIF amounts in affected tissues, mainly produced by immune cells such as macrophages, Th2 cells, and eosinophils. Increased MIF mRNA and protein are found in activated Th2 cells, while eosinophils stock pre-formed MIF protein and secrete high amounts of MIF upon stimulation. In mouse models of allergic asthma, the lack of MIF causes an almost complete abrogation of the cardinal signs of the disease including mucus secretion, eosinophilic inflammation, and airway hyper-responsiveness. Additionally, blocking the expression of MIF in animal models leads to significant reduction of pathological signs of eosinophilic inflammation such as rhinitis, atopic dermatitis, eosinophilic esophagitis and helminth infection. A number of studies indicate that MIF is important in the effector phase of type-2 immune responses, while its contribution to Th2 differentiation and IgE production is not consensual. MIF has been found to intervene in different aspects of eosinophil physiology including differentiation, survival, activation, and migration. CD4+ T cells and eosinophils express CD74 and CXCR4, receptors able to signal upon MIF binding. Blockage of these receptors with neutralizing antibodies or small molecule antagonists also succeeds in reducing the signals of inflammation in experimental allergic models. Together, these studies demonstrate an important contribution of MIF on eosinophil biology and in the pathogenesis of allergic diseases and helminth infection.

Multiple doses of adipose tissue-derived mesenchymal stromal cells induce immunosuppression in experimental asthma.

In experimental house dust mite (HDM)-induced allergic asthma, therapeutic administration of a single dose of adipose tissue-derived mesenchymal stromal cells (MSCs) ameliorates lung inflammation but is unable to reverse remodeling. We hypothesized that multiple doses of MSCs might exert better therapeutic effects by reducing lung inflammation and remodeling but might also result in immunosuppressive effects in experimental asthma. HDM was administered intranasally in C57BL/6 mice. After the last HDM challenge, mice received two or three doses of MSCs (105 cells per day) or saline intravenously. An additional cohort of mice received dexamethasone as a positive control for immunosuppression. Two and three doses of MSCs reduced lung inflammation, levels of interleukin (IL)-4, IL-13, and eotaxin; total leukocyte, CD4+ T-cell, and eosinophil counts in bronchoalveolar lavage fluid; and total leukocyte counts in bone marrow, spleen, and mediastinal lymph nodes. Two and three doses of MSCs also reduced collagen fiber content and transforming growth factor-ß levels in lung tissue; however, the three-dose regimen was more effective, and reduced these parameters to control levels, while also decreasing α-actin content in lung tissue. Two and three doses of MSCs improved lung mechanics. Dexamethasone, two and three doses of MSCs similarly increased galectin levels, but only the three-dose regimen increased CD39 levels in the thymus. Dexamethasone and the three-dose, but not the two-dose regimen, also increased levels of programmed death receptor-1 and IL-10, while reducing CD4+ CD8low cell percentage in the thymus. In conclusion, multiple doses of MSCs reduced lung inflammation and remodeling while causing immunosuppression in HDM-induced allergic asthma.

Effects of crystalloid, hyper-oncotic albumin, and iso-oncotic albumin on lung and kidney damage in experimental acute lung injury.

BACKGROUND: Conflicting data have reported beneficial effects of crystalloids, hyper-oncotic albumin (20%ALB), and iso-oncotic albumin (5%ALB) in critically ill patients. Although hyper-oncotic albumin may minimize lung injury, recent studies have shown that human albumin may lead to kidney damage proportional to albumin concentration. In this context, we compared the effects of Ringer's lactate (RL), 20%ALB, and 5%ALB, all titrated according to similar hemodynamic goals, on pulmonary function, lung and kidney histology, and molecular biology in experimental acute lung injury (ALI). METHODS: Male Wistar rats received Escherichia coli lipopolysaccharide intratracheally (n = 24) to induce ALI. After 24 h, animals were anesthetized and randomly assigned to receive RL, 20%ALB, or 5%ALB (n = 6/group) to maintain hemodynamic stability (distensibility index of inferior vena cava < 25%, mean arterial pressure > 65 mmHg). Rats were then mechanically ventilated for 6 h. Six animals, which received neither ventilation nor fluids (NV), were used for molecular biology analyses. RESULTS: The total fluid volume infused was higher in RL compared to 5%ALB and 20%ALB (median [interquartile range], 10.8[8.2-33.2] vs. 4.8[3.6-7.7] and 4.3[3.9-6.6] mL, respectively; p = 0.02 and p = 0.003). B-line counts on lung ultrasound (p < 0.0001 and p = 0.0002) and serum lactate levels (p = 0.01 and p = 0.01) were higher in RL than 5%ALB and 20%ALB. Diffuse alveolar damage score was lower in 5%ALB (10.5[8.5-12]) and 20%ALB (10.5[8.5-14]) than RL (16.5[12.5-20.5]) (p < 0.05 and p = 0.03, respectively), while acute kidney injury score was lower in 5%ALB (9.5[6.5-10]) than 20%ALB (18[15-28.5], p = 0.0006) and RL (16 [15-19], p = 0.04). In lung tissue, mRNA expression of interleukin (IL)-6 was higher in RL (59.1[10.4-129.3]) than in 5%ALB (27.0[7.8-49.7], p = 0.04) or 20%ALB (3.7[7.8-49.7], p = 0.03), and IL-6 protein levels were higher in RL than 5%ALB and 20%ALB (p = 0.026 and p = 0.021, respectively). In kidney tissue, mRNA expression and protein levels of kidney injury molecule (KIM)-1 were lower in 5%ALB than RL and 20%ALB, while nephronectin expression increased (p = 0.01 and p = 0.01), respectively. CONCLUSIONS: In a rat model of ALI, both iso-oncotic and hyper-oncotic albumin solutions were associated with less lung injury compared to Ringer's lactate. However, hyper-oncotic albumin resulted in greater kidney damage than iso-oncotic albumin. This experimental study is a step towards future clinical designs.

Glucagon reduces airway hyperreactivity, inflammation, and remodeling induced by ovalbumin.

Glucagon has been shown to be beneficial as a treatment for bronchospasm in asthmatics. Here, we investigate if glucagon would prevent airway hyperreactivity (AHR), lung inflammation, and remodeling in a murine model of asthma. Glucagon (10 and 100 µg/Kg, i.n.) significantly prevented AHR and eosinophilia in BAL and peribronchiolar region induced by ovalbumin (OVA) challenge, while only the dose of 100 µg/Kg of glucagon inhibited subepithelial fibrosis and T lymphocytes accumulation in BAL and lung. The inhibitory action of glucagon occurred in parallel with reduction of OVA-induced generation of IL-4, IL-5, IL-13, TNF-α, eotaxin-1/CCL11, and eotaxin-2/CCL24 but not MDC/CCL22 and TARC/CCL17. The inhibitory effect of glucagon (100 µg/Kg, i.n.) on OVA-induced AHR and collagen deposition was reversed by pre-treatment with indomethacin (10 mg/Kg, i.p.). Glucagon increased intracellular cAMP levels and inhibits anti-CD3 plus anti-CD28-induced proliferation and production of IL-2, IL-4, IL-10, and TNF- α from TCD4+ cells in vitro. These findings suggest that glucagon reduces crucial features of asthma, including AHR, lung inflammation, and remodeling, in a mechanism probably associated with inhibition of eosinophils accumulation and TCD4+ cell proliferation and function. Glucagon should be further investigated as an option for asthma therapy.

Serum from Asthmatic Mice Potentiates the Therapeutic Effects of Mesenchymal Stromal Cells in Experimental Allergic Asthma.

Asthma is a chronic inflammatory disease characterized by airway inflammation and remodeling, which can lead to progressive decline of lung function. Although mesenchymal stromal cells (MSCs) have shown beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been limited. Mounting evidence suggests that prior exposure of MSCs to specific inflammatory stimuli or environments can enhance their immunomodulatory properties. Therefore, we investigated whether stimulating MSCs with bronchoalveolar lavage fluid (BALF) or serum from asthmatic mice could potentiate their therapeutic properties in experimental asthma. In a house dust mite (HDM) extract asthma model in mice, unstimulated, asthmatic BALF-stimulated, or asthmatic serum-stimulated MSCs were administered intratracheally 24 hours after the final HDM challenge. Lung mechanics and histology; BALF protein, cellularity, and biomarker levels; and lymph-node and bone marrow cellularity were assessed. Compared with unstimulated or BALF-stimulated MSCs, serum-stimulated MSCs further reduced BALF levels of interleukin (IL)-4, IL-13, and eotaxin, total and differential cellularity in BALF, bone marrow and lymph nodes, and collagen fiber content, while increasing BALF IL-10 levels and improving lung function. Serum stimulation led to higher MSC apoptosis, expression of various mediators (transforming growth factor-ß, interferon-γ, IL-10, tumor necrosis factor-α-stimulated gene 6 protein, indoleamine 2,3-dioxygenase-1, and IL-1 receptor antagonist), and polarization of macrophages to M2 phenotype. In conclusion, asthmatic serum may be a novel strategy to potentiate therapeutic effects of MSCs in experimental asthma, leading to further reductions in both inflammation and remodeling than can be achieved with unstimulated MSCs. Stem Cells Translational Medicine 2019;8:301&312.

Impact of one versus two doses of mesenchymal stromal cells on lung and cardiovascular repair in experimental emphysema.

BACKGROUND: A single administration of mesenchymal stromal cells (MSCs) has been shown to reduce lung inflammation in experimental elastase-induced emphysema; however, effects were limited in terms of lung-tissue repair and cardiac function improvement. We hypothesized that two doses of MSCs could induce further lung and cardiovascular repair by mitigating inflammation and remodeling in a model of emphysema induced by multiple elastase instillations. We aimed to comparatively investigate the effects of one versus two doses of MSCs, administered 1 week apart, in a murine model of elastase-induced emphysema. METHODS: C57BL/6 mice were randomly divided into control (CTRL) and emphysema (E) groups. Mice in the E group received porcine pancreatic elastase (0.2 IU, 50 µL) intratracheally once weekly for four consecutive weeks; the CTRL animals received sterile saline (50 µL) using the same protocol. Three hours after the last instillation, the E group was further randomized to receive either saline (SAL) or murine MSCs (105 cells) intratracheally, in one or two doses (1 week apart). Fourteen days later, mice were euthanized, and all data analyzed. RESULTS: Both one and two doses of MSCs improved lung mechanics, reducing keratinocyte-derived chemokine and transforming growth factor-ß levels in lung homogenates, total cell and macrophage counts in bronchoalveolar lavage fluid (BALF), and collagen fiber content in airways and blood vessels, as well as increasing vascular endothelial growth factor in lung homogenates and elastic fiber content in lung parenchyma. However, only the two-dose group exhibited reductions in tumor necrosis factor-α in lung tissue, BALF neutrophil and lymphocyte count, thymus weight, and total cellularity, as well as CD8+ cell counts and cervical lymph node CD4+ and CD8+ T cell counts, as well as further increased elastic fiber content in the lung parenchyma and reduced severity of pulmonary arterial hypertension. CONCLUSIONS: Two doses of MSCs enhanced lung repair and improvement in cardiac function, while inducing T cell immunosuppression, mainly of CD8+ cells, in elastase-induced emphysema.

Critical role of CD4+ T cells and IFNγ signaling in antibody-mediated resistance to Zika virus infection.

Protective adaptive immunity to Zika virus (ZIKV) has been mainly attributed to cytotoxic CD8+ T cells and neutralizing antibodies, while the participation of CD4+ T cells in resistance has remained largely uncharacterized. Here, we show a neutralizing antibody response, dependent on CD4+ T cells and IFNγ signaling, which we detected during the first week of infection and is associated with reduced viral load in the brain, prevention of rapid disease onset and survival. We demonstrate participation of these components in the resistance to ZIKV during primary infection and in murine adoptive transfer models of heterologous ZIKV infection in a background of IFNR deficiency. The protective effect of adoptively transferred CD4+ T cells requires IFNγ signaling, CD8+ T cells and B lymphocytes in recipient mice. Together, this indicates the importance of CD4+ T cell responses in future vaccine design for ZIKV.

Recurrent Potent Human Neutralizing Antibodies to Zika Virus in Brazil and Mexico.

Antibodies to Zika virus (ZIKV) can be protective. To examine the antibody response in individuals who develop high titers of anti-ZIKV antibodies, we screened cohorts in Brazil and Mexico for ZIKV envelope domain III (ZEDIII) binding and neutralization. We find that serologic reactivity to dengue 1 virus (DENV1) EDIII before ZIKV exposure is associated with increased ZIKV neutralizing titers after exposure. Antibody cloning shows that donors with high ZIKV neutralizing antibody titers have expanded clones of memory B cells that express the same immunoglobulin VH3-23/VK1-5 genes. These recurring antibodies cross-react with DENV1, but not other flaviviruses, neutralize both DENV1 and ZIKV, and protect mice against ZIKV challenge. Structural analyses reveal the mechanism of recognition of the ZEDIII lateral ridge by VH3-23/VK1-5 antibodies. Serologic testing shows that antibodies to this region correlate with serum neutralizing activity to ZIKV. Thus, high neutralizing responses to ZIKV are associated with pre-existing reactivity to DENV1 in humans.

Bosutinib Therapy Ameliorates Lung Inflammation and Fibrosis in Experimental Silicosis.

Silicosis is an occupational lung disease for which no effective therapy exists. We hypothesized that bosutinib, a tyrosine kinase inhibitor, might ameliorate inflammatory responses, attenuate pulmonary fibrosis, and thus improve lung function in experimental silicosis. For this purpose, we investigated the potential efficacy of bosutinib in the treatment of experimental silicosis induced in C57BL/6 mice by intratracheal administration of silica particles. After 15 days, once disease was established, animals were randomly assigned to receive DMSO or bosutinib (1 mg/kg/dose in 0.1 mL 1% DMSO) by oral gavage, twice daily for 14 days. On day 30, lung mechanics and morphometry, total and differential cell count in alveolar septa and granuloma, levels of interleukin (IL)-1ß, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-4, transforming growth factor (TGF)-ß, and vascular endothelial growth factor in lung homogenate, M1 and M2 macrophages, total leukocytes, and T cells in BALF, lymph nodes, and thymus, and collagen fiber content in alveolar septa and granuloma were analyzed. In a separate in vitro experiment, RAW264.7 macrophages were exposed to silica particles in the presence or absence of bosutinib. After 24 h, gene expressions of arginase-1, IL-10, IL-12, inducible nitric oxide synthase (iNOS), metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1, and caspase-3 were evaluated. In vivo, in silicotic animals, bosutinib, compared to DMSO, decreased: (1) fraction area of collapsed alveoli, (2) size and number of granulomas, and mononuclear cell granuloma infiltration; (3) IL-1ß, TNF-α, IFN-γ, and TGF-ß levels in lung homogenates, (4) collagen fiber content in lung parenchyma, and (5) viscoelastic pressure and static lung elastance. Bosutinib also reduced M1 cell counts while increasing M2 macrophage population in both lung parenchyma and granulomas. Total leukocyte, regulatory T, CD4+, and CD8+ cell counts in the lung-draining lymph nodes also decreased with bosutinib therapy without affecting thymus cellularity. In vitro, bosutinib led to a decrease in IL-12 and iNOS and increase in IL-10, arginase-1, MMP-9, and TIMP-1. In conclusion, in the current model of silicosis, bosutinib therapy yielded beneficial effects on lung inflammation and remodeling, therefore resulting in lung mechanics improvement. Bosutinib may hold promise for silicosis; however, further studies are required.

Bone Marrow, Adipose, and Lung Tissue-Derived Murine Mesenchymal Stromal Cells Release Different Mediators and Differentially Affect Airway and Lung Parenchyma in Experimental Asthma.

Mesenchymal stromal cells (MSCs) from different sources have differential effects on lung injury. To compare the effects of murine MSCs from bone marrow (BM), adipose tissue (AD), and lung tissue (LUNG) on inflammatory and remodeling processes in experimental allergic asthma, female C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) or saline (C). Twenty-four hours after the last challenge, mice received either saline (50 µl, SAL), BM-MSCs, AD-MSCs, or LUNG-MSCs (105 cells per mouse in 50 µl total volume) intratracheally. At 1 week, BM-MSCs produced significantly greater reductions in resistive and viscoelastic pressures, bronchoconstriction index, collagen fiber content in lung parenchyma (but not airways), eosinophil infiltration, and levels of interleukin (IL)-4, IL-13, transforming growth factor (TGF)-ß, and vascular endothelial growth factor (VEGF) in lung homogenates compared to AD-MSCs and LUNG-MSCs. Only BM-MSCs increased IL-10 and interferon (IFN)-γ in lung tissue. In parallel in vitro experiments, BM-MSCs increased M2 macrophage polarization, whereas AD-MSCs and LUNG-MSCs had higher baseline levels of IL-4, insulin-like growth factor (IGF), and VEGF secretion. Exposure of MSCs to serum specimens obtained from asthmatic mice promoted reductions in secretion of these mediators, particularly in BM-MSCs. Intratracheally administered BM-MSCs, AD-MSCs, and LUNG-MSCs were differentially effective at reducing airway inflammation and remodeling and improving lung function in the current model of allergic asthma. In conclusion, intratracheal administration of MSCs from BM, AD, and LUNG were differentially effective at reducing airway inflammation and remodeling and improving lung function comparably reduced inflammation and fibrogenesis in this asthma model. However, altered lung mechanics and lung remodeling responded better to BM-MSCs than to AD-MSCs or LUNG-MSCs. Moreover, each type of MSC was differentially affected in a surrogate in vitro model of the in vivo lung environment. Stem Cells Translational Medicine 2017;6:1557-1567.

JM25-1, a Lidocaine Analog Combining Airway Relaxant and Antiinflammatory Properties: Implications for New Bronchospasm Therapy.

BACKGROUND: Inhaled lidocaine antagonized bronchospasm in animal models and patients, but adverse effects limited its efficacy. This study evaluated the antibronchospasm potential of the analog JM25-1, exploring in vitro mechanisms and translation to an animal model. METHODS: The effectiveness of JM25-1 was assessed in GH3 cells, rat tracheal rings, mouse lymphocytes, and human eosinophil systems in vitro, assessing changes in Na current, contraction, proliferation, and survival, respectively. Lung function and inflammatory changes were studied in ovalbumin-sensitized mice. RESULTS: The efficacy of JM25-1 was higher than lidocaine in inhibiting carbachol-induced and calcium-induced tracheal contractions (maximum effect inhibition at 1 mM [%]: 67 ± 10 [JM25-1] vs. 41 ± 11 [lidocaine] [P < 0.001] for carbachol; 100 ± 3 [JM25-1] vs. 36 ± 26 [lidocaine] [P < 0.001] for Ca; mean ± SD; n = 9 each) but lower in Na current (50% inhibitory concentration = 151.5, n = 8 vs. 0.2 mM; n = 5; P < 0.001). JM25-1 also inhibited eosinophil survival (dead cells [%]: 65 ± 6; n = 4; P < 0.001 at 1 mM) and lymphocyte proliferation (cells in phase S + G2 [%]: 94 ± 10; n = 6; P < 0.001) at 0.6 mM. Aerosolized JM25-1 (1%) decreased lung eosinophil numbers from 13.2 ± 2.4 to 1.7 ± 0.7 × 10/µm (n = 6; P < 0.001) and neutrophils from 1.9 ± 0.4 to 0.2 ± 0.1 × 10/µm (n = 7; P < 0.001). Other parameters, including airway hyperreactivity, cytokines, mucus, and extracellular matrix deposition, were also sensitive to aerosolized JM25-1. CONCLUSION: These findings highlight the potential of JM25-1, emphasizing its putative value in drug development for clinical conditions where there is bronchospasm.

Nebulized lidocaine prevents airway inflammation, peribronchial fibrosis, and mucus production in a murine model of asthma.

BACKGROUND: Evidence suggests that nebulized lidocaine is beneficial in asthma therapy, but to what extent and the mechanisms underlying this effect remain poorly understood. The aim of this study was to assess the impact of lidocaine treatment using a murine model of allergic asthma characterized by expression of pivotal features of the disease: inflammation, mucus production, and lung remodeling. METHODS: A/J mice sensitized with ovalbumin were treated with inhaled lidocaine or vehicle immediately after ovalbumin intranasal challenges. Lung function, total and differential leukocytes in bronchoalveolar lavage fluid, peribronchial eosinophil density, interleukin (IL)-4, IL-5 and eotaxin-1 levels, epithelial mucus, collagen, extracellular-matrix deposition, matrix metalloproteinase-9 activity, and GATA-3 expression were evaluated. Between five and eight animals per group were used. RESULTS: Inhaled lidocaine inhibited ovalbumin-induced airway hyperreactivity to methacholine, and accumulation of lymphocytes, neutrophils, and eosinophils in bronchoalveolar lavage fluid 24 h after the last allergen provocation. Lidocaine administration also prevented other pathophysiological changes triggered by ovalbumin in lung tissue, including peribronchial eosinophil and neutrophil infiltration, subepithelial fibrosis, increased content of collagen and mucus, matrix metalloproteinase-9 activity, and increased levels of IL-4, IL-5, IL-13, and eotaxin-1. Furthermore, inhaled lidocaine inhibited lung tissue GATA-3 expression in ovalbumin-challenged mice. We also demonstrated that lidocaine inhibited the expression of GATA-3 in ovalbumin-stimulated T cells in vitro. CONCLUSIONS: Inhaled lidocaine prevents eosinophilic inflammation, overproduction of mucus, and peribronchial fibrosis in a murine model of asthma, and impaired airway hyperreactivity, possibly by inhibiting allergen-evoked GATA-3 expression and the subsequent up-regulation of proinflammatory cytokines and chemokines.

Two for one: cyclic AMP mediates the anti-inflammatory and anti-spasmodic properties of the non-anesthetic lidocaine analog JMF2-1.

Inhalation of JMF2-1, an analog of lidocaine with reduced anesthetic activity, prevents airway contraction and lung inflammation in experimental asthma models. We sought to test if the JMF2-1 effects are a consequence of increased intracellular cAMP levels in asthma cell targets, such as smooth muscle cells and T cells. Functional effect of JMF2-1 on carbachol-induced contraction of intact or epithelial-denuded rat trachea was assessed in conventional organ baths. cAMP was quantified by radioimmunoassay in cultured guinea pig tracheal smooth muscle cells, as well as lymph node cells from BALB/c mice, exposed to JMF2-1. We found that JMF2-1 (0.1-1mM) concentration-dependently inhibited epithelium-intact tracheal ring contraction induced by carbachol challenge. The antispasmodic effect remained unaltered following epithelium removal or pretreatment with NG-nitro-L-arginine methyl ester (100µM), but it was clearly sensitive to 9-(tetrahydro-2-furyl) adenine (SQ22,536, 100µM), an adenylate cyclase inhibitor. JMF2-1 (300 and 600µM) also dose-dependently increased cAMP intracellular levels of both cultured airway smooth muscle cells and T lymphocytes. This effect was consistently abrogated by SQ22,536 and reproduced by forskolin in both systems. JMF2-1 induced apoptosis of anti-CD3 activated T cells in a mechanism sensitive to zIETD, indicating that JMF2-1 mediates caspase-8-dependent apoptosis. Furthermore, forskolin also inhibited anti-CD3 induced T cell proliferation and survival. Our results suggest that JMF2-1 inhibits respiratory smooth muscle contraction as well as T cell proliferation and survival through enhancement of intracellular cAMP levels. These findings may help to explain the anti-inflammatory and antispasmodic effects of JMF2-1 observed in previous studies.

NFAT1 transcription factor regulates pulmonary allergic inflammation and airway responsiveness.

Allergic asthma is a chronic inflammatory disease of the lung whose incidence and morbidity continues to rise in developed nations. Despite being a hallmark of asthma, the molecular mechanisms that determine airway hyperresponsiveness (AHR) are not completely established. Transcription factors of the NFAT family are involved in the regulation of several asthma-related genes. It has been shown that the absence of NFAT1 leads to an increased pleural eosinophilic allergic response accompanied by an increased production of Th2 cytokines, suggesting a role for NFAT1 in the regulation of allergic diseases. Herein, we analyze NFAT1-/- mice to address the role of NFAT1 in a model of allergic airway inflammation and its influence in AHR. NFAT1-/- mice submitted to airway inflammation display a significant exacerbation of several features of the allergic disease, including lung inflammation, eosinophilia, and serum IgE levels, which were concomitant with elevated Th2 cytokine production. However, in spite of the increased allergic phenotype, NFAT1-/- mice failed to express AHR after methacholine aerosol. Refractoriness of NFAT1-/- mice to methacholine was confirmed in naïve mice, suggesting that this refractoriness occurs in an intrinsic way, independent of the lung inflammation. In addition, NFAT1-/- mice exhibit increased AHR in response to serotonin inhalation, suggesting a specific role for NFAT1 in the methacholine pathway of bronchoconstriction. Taken together, these data add support to the interpretation that NFAT1 acts as a counterregulatory mechanism to suppress allergic inflammation. Moreover, our findings suggest a novel role for NFAT1 protein in airway responsiveness mediated by the cholinergic pathway.