Cysteinyl leukotriene receptor antagonist MK-571 alters bronchoalveolar lavage fluid proteome in a mouse asthma model

Charcot-Leyden crystals and other protein crystals driving type 2 immunity and allergy

Protein crystals derived from innate immune cells have been synonymous with a Type-2 immune response in both mouse and man for over 150 years. Eosinophilic Galectin-10 (Charcot-Leyden) crystals in humans, and Ym1/Ym2 crystals in mice are frequently found in the context of parasitic infections, but also in diseases such as asthma and chronic rhinosinusitis. Despite their notable presence, these crystals are often overlooked as trivial markers of Type-2 inflammation. Here, we discuss the source, context, and role of protein crystallization. We focus on similarities observed between Galectin-10 and Ym1/2 crystals in driving immune responses; the subsequent benefit to the host during worm infection, and conversely the detrimental exacerbation of inflammation and mucus production during asthma.

The mechanisms of detoxification of As(III), dimethylarsinic acid (DMA) and As(V) in the microalga Chlorella vulgaris

The response of Chlorella vulgaris when challenged by As(III), As(V) and dimethylarsinic acid (DMA) was assessed through experiments on adsorption, efflux and speciation of arsenic (reduction, oxidation, methylation and chelation with glutathione/phytochelatin [GSH/PC]). Our study indicates that at high concentrations of phosphate (1.62mM of HPO4(2-)), upon exposure to As(V), cells are able to shift towards methylation of As(V) rather than PC formation. Treatment with As(V) caused a moderate decrease in intracellular pH and a strong increase in the concentration of free thiols (GSH). Passive surface adsorption was found to be negligible for living cells exposed to DMA and As(V). However, adsorption of As(III) was observed to be an active process in C. vulgaris, because it did not show saturation at any of the exposure periods. Chelation of As(III) with GS/PC and to a lesser extent hGS/hPC is a major detoxification mechanism employed by C. vulgaris cells when exposed to As(III). The increase of bound As-GS/PC complexes was found to be strongly related to an increase in concentration of As(III) in media. C. vulgaris cells did not produce any As-GS/PC complex when exposed to As(V). This may indicate that a reduction step is needed for As(V) complexation with GSH/PC. C. vulgaris cells formed DMAS(V)-GS upon exposure to DMA independent of the exposure period. As(III) triggers the formation of arsenic complexes with PC and homophytochelatins (hPC) and their compartmentalisation to vacuoles. A conceptual model was devised to explain the mechanisms involving ABCC1/2 transport. The potential of C. vulgaris to bio-remediate arsenic from water appeared to be highly selective and effective without the potential hazard of reducing As(V) to As(III), which is more toxic to humans.

Invariant Natural Killer T Cells Play a Role in Chemotaxis, Complement Activation and Mucus Production in a Mouse Model of Airway Hyperreactivity and Inflammation

CD1d-restricted invariant natural killer T (iNKT) cells play a critical role in the induction of airway hyperreactivity (AHR). After intranasal alpha-galactosylceramide (α-GalCer) administration, bronchoalveolar lavage fluid (BALF) proteins from mouse lung were resolved by two-dimensional differential gel electrophoresis (2D-DIGE), and identified by tandem mass spectroscopy. A lack of iNKT cells prevented the development of airway responses including AHR, neutrophilia and the production of the proinflammatory cytokines in lungs. Differentially abundant proteins in the BALF proteome of α-GalCer-treated wild type mice included lungkine (CXCL15), pulmonary surfactant-associated protein D (SFTPD), calcium-activated chloride channel regulator 1 (CLCA1), fragments of complement 3, chitinase 3-like proteins 1 (CH3LI) and 3 (CH3L3) and neutrophil gelatinase-associated lipocalin (NGAL). These proteins may contribute to iNKT regulated AHR via several mechanisms: altering leukocyte chemotaxis, increasing airway mucus production and possibly via complement activation.

Overexpression of cyclic adenosine monophosphate effluent protein MRP4 induces an altered response to β-adrenergic stimulation in the senescent rat heart

BACKGROUND

In the senescent heart, the positive inotropic response to β-adrenoceptor stimulation is reduced, partly by dysregulation of β1- and β3-adrenoceptors. The multidrug resistance protein 4 (MRP4) takes part in the control of intracellular cyclic adenosine monophosphate concentration by controlling its efflux but the role of MRP4 in the β-adrenergic dysfunction of the senescent heart remains unknown.

METHODS

The β-adrenergic responses to isoproterenol were investigated in vivo (stress echocardiography) and in vitro (isolated cardiomyocyte by Ionoptix with sarcomere shortening and calcium transient) in young (3 months old) and senescent (24 months old) rats pretreated or not with MK571, a specific MRP4 inhibitor. MRP4 was quantified in left ventricular homogenates by Western blotting. Data are mean ± SD expressed as percent of baseline value.

RESULTS

The positive inotropic effect of isoproterenol was reduced in senescent rats in vivo (left ventricular shortening fraction 120 ± 16% vs. 158 ± 20%, P < 0.001, n = 16 rats) and in vitro (sarcomere shortening 129 ± 37% vs. 148 ± 35%, P = 0.004, n = 41 or 43 cells) as compared to young rats. MRP4 expression increased 3.6-fold in senescent compared to young rat myocardium (P = 0.012, n = 8 rats per group). In senescent rats, inhibition of MRP4 by MK571 restored the positive inotropic effect of isoproterenol in vivo (143 ± 11%, n = 8 rats). In vitro in senescent cardiomyocytes pretreated with MK571, both sarcomere shortening (161 ± 45% vs. 129 ± 37%, P = 0.007, n = 41 cells per group) and calcium transient amplitude (132 ± 25% vs. 113 ± 27%, P = 0.007) increased significantly.

CONCLUSION

MRP4 overexpression contributes to the reduction of the positive inotropic response to β-adrenoceptor stimulation in the senescent heart.

Neutralization of leukotriene C4 and D4 activity by monoclonal and single-chain antibodies

BACKGROUND

Cysteinyl leukotrienes (LTs) are key mediators in inflammation. To explore the structure of the antigen-recognition site of a monoclonal antibody against LTC4 (mAbLTC), we previously isolated full-length cDNAs for heavy and light chains of the antibody and prepared a single-chain antibody comprising variable regions of these two chains (scFvLTC).

METHODS

We examined whether mAbLTC and scFvLTC neutralized the biological activities of LTC4 and LTD4 by competing their binding to their receptors.

RESULTS

mAbLTC and scFvLTC inhibited their binding of LTC4 or LTD4 to CysLT1 receptor (CysLT1R) and CysLT2 receptor (CysLT2R) overexpressed in Chinese hamster ovary cells. The induction by LTD4 of monocyte chemoattractant protein-1 and interleukin-8 mRNAs in human monocytic leukemia THP-1 cells expressing CysLT1R was dose-dependently suppressed not only by mAbLTC but also by scFvLTC. LTC4- and LTD4-induced aggregation of mouse platelets expressing CysLT2R was dose-dependently suppressed by either mAbLTC or scFvLTC. Administration of mAbLTC reduced pulmonary eosinophil infiltration and goblet cell hyperplasia observed in a murine model of asthma. Furthermore, mAbLTC bound to CysLT2R antagonists but not to CysLT1R antagonists.

CONCLUSIONS

These results indicate that mAbLTC and scFvLTC neutralize the biological activities of LTs by competing their binding to CysLT1R and CysLT2R. Furthermore, the binding of cysteinyl LT receptor antagonists to mAbLTC suggests the structural resemblance of the LT-recognition site of the antibody to that of these receptors.

GENERAL SIGNIFICANCE

mAbLTC can be used in the treatment of inflammatory diseases such as asthma.

Proteomics in detection and monitoring of asthma and smoking-related lung diseases

Asthma, chronic obstructive pulmonary disease (COPD) and lung cancer cause extensive mortality and morbidity worldwide. However, the current state-of-the-art diagnosis and management schemes of these diseases are suboptimal as the incidence of asthma has risen by 250% over the last two decades and the 5-year mortality rate of lung cancer remains at 88%. Proteomic analysis is at the frontier of medical research and demonstrates tremendous potential in the early detection, diagnosis and staging, as well as providing novel therapeutic targets for improved management of smoking-related lung diseases. Advances in analytical tools, such as 2D gel electrophoresis, mass spectrometry, protein arrays and improved bioinformatics, allow sensitive and specific biomarker/protein profile discoveries and the infusion of new knowledge towards the molecular basis of lung diseases and their progression. Significant hurdles still stand between these laboratory findings and their applications in clinical practice. One of the challenges is the difficulty in the selection of samples that provide scope into the specific disease entity. Induced sputum, bronchoalveolar lavage, exhaled breath and exhaled breath condensate are methods of sampling airway and lung fluids that can serve as a window to assess the microenvironment of the lungs. With better study design standardization and the implementation of novel technologies to reach the optimal research standard, there is enough reason be optimistic about the future of proteomic research and its clinical implications.

Proteomics methods and applications for the practicing clinician

OBJECTIVE

To describe clinical proteomics from discovery techniques and their limitations, to applications in allergy, asthma, and immunology, and finally to how proteomics can be integrated into clinical practice.

DATA SOURCES

Despite many inherent challenges, proteomics-based methods have become a powerful and popular means of profiling clinical samples for the purpose of biomarker discovery. Although several strategies exist, clinical proteomics for the purpose of biomarker discovery generally focuses on 1 of 3 basic workflows: (1) 2-dimensional gel electrophoresis to quantitate relative protein levels followed by mass spectrometry (MS) to identify proteins of interest, (2) non-gel-based methods that rely on liquid chromatography MS (LCMS) for both quantitation and identification of proteins, and (3) protein profiling methods that do not directly result in the identification of proteins but rather generate "fingerprints" that are compared among individuals or samples.

STUDY SELECTION

Regardless of the strategy being pursued, a few general experimental steps are followed that will be expounded on in the text. These proteomics techniques have been applied to discover new biomarkers in biofluids and tissues from individuals with a variety of conditions, including allergy, asthma, atopic dermatitis, inflammatory diseases, chronic obstructive pulmonary disease, and other lung diseases.

RESULTS

After biomarker discovery, LCMS-based proteomics offers several advantages over traditional antibody-based clinical assays, including greater specificity, cost- and time-effectiveness, and the potential to multiplex up to hundreds of peptides in a single assay.

CONCLUSION

With many guidelines now in place and model studies on which to design future experiments, there is reason to be optimistic that candidate protein biomarkers will be discovered using proteomics and translated into clinical assays.

Study of a BALB/c Mouse Model for Allergic Asthma

Allergic asthma is a worldwide public health problem and a major socioeconomic burden disease. It is a chronic inflammatory disease marked by airway eosinophilia and goblet cell hyperplasia with mucus hypersecretion. Mouse models have proven as a valuable tool for studying human asthma. In the present report we describe a comparison of mouse asthma models. The experiments were designed as follows: Group I was injected with ovalbumin (OVA, i.p.) on day 1 and challenged with 1% OVA (aerosol exposure) on days 14~21. Group II was injected on day 1, 14 and aerosol-immunized on days 14~21. Group III was injected on day 1, 14 and immunized by 1% OVA aerosol on days 18~21. We assessed asthma induction by determining the total number of white blood cells (WBC) and eosinophils as well as by measuring cytokine levels in bronchoalveolar lavage fluid (BALF). In addition, we evaluated the histopathological changes of the lungs and determined the concentration of immunoglobulin E (IgE) in serum. Total WBC, eosinophils, Th2 cytokines (IL-4, IL-13) and IgE were significantly increased in group I relative to the other groups. Moreover, histopathological studies show that group I mice show an increase in the infiltration of inflammatory cell-in peribronchial and perivascular areas as well as an overall increase in the number of mucus-containing goblet cells relative to other groups. These data suggest that group I can be a useful model for the study of human asthma pathobiology and the evaluation of existing and novel therapeutic agents.

Staphylococcus aureus elicits marked alterations in the airway proteome during early pneumonia

Pneumonia caused by Staphylococcus aureus is a growing concern in the health care community. We hypothesized that characterization of the early innate immune response to bacteria in the lungs would provide insight into the mechanisms used by the host to protect itself from infection. An adult mouse model of Staphylococcus aureus pneumonia was utilized to define the early events in the innate immune response and to assess the changes in the airway proteome during the first 6 h of pneumonia. S. aureus actively replicated in the lungs of mice inoculated intranasally under anesthesia to cause significant morbidity and mortality. By 6 h postinoculation, the release of proinflammatory cytokines caused effective recruitment of neutrophils to the airway. Neutrophil influx, loss of alveolar architecture, and consolidated pneumonia were observed histologically 6 h postinoculation. Bronchoalveolar lavage fluids from mice inoculated with phosphate-buffered saline (PBS) or S. aureus were depleted of overabundant proteins and subjected to strong cation exchange fractionation followed by liquid chromatography and tandem mass spectrometry to identify the proteins present in the airway. No significant changes in response to PBS inoculation or 30 min following S. aureus inoculation were observed. However, a dramatic increase in extracellular proteins was observed 6 h postinoculation with S. aureus, with the increase dominated by inflammatory and coagulation proteins. The data presented here provide a comprehensive evaluation of the rapid and vigorous innate immune response mounted in the host airway during the earliest stages of S. aureus pneumonia.

Effects of the immunomodulatory agent Cordyceps militaris on airway inflammation in a mouse asthma model

BACKGROUND

Cordyceps militaris is a well-known fungus with immunomodulatory activity. It is generally used in traditional Chinese medicine to treat hemoptysis, bronchial or lung inflammation, and urogenital disorders. The purpose of our study was to evaluate the effect of cultivated C. militaris on airway inflammation in a mouse asthma model.

METHODS

BALB/c mice were sensitized with intraperitoneal ovalbumin (OVA) on Days 0 and 14, and were then given intranasal OVA on Day 14 and Days 25-27. Randomized treatment groups of sensitized mice were administered C. militaris, prednisolone, montelukast, or placebo by gavage from Days 15-27. Airway hyperreactivity to aerosolized methacholine was determined. Bronchoalveolar lavage fluid and serum were analyzed to assess airway inflammation.

RESULTS

OVA-sensitized mice developed a significant airway inflammatory response that was inhibited by prednisolone and montelukast, whilst C. militaris reduced airway inflammation less effectively. Airway hyperresponsiveness to methacholine was observed in OVA-sensitized mice and was reversed by both prednisolone and montelukast. C. militaris initially reversed airway hyperreactivity, but this effect disappeared at higher methacholine doses.

CONCLUSION

C. militaris can modulate airway inflammation in asthma, but it is less effective than prednisolone or montelukast. These results demonstrate that C. militaris is unable to adequately block the potent mediators of asthmatic airway inflammation.

Expanding roles for leukotrienes in airway inflammation

Leukotrienes (LTs) are lipid mediators derived from the 5-lipoxygenase pathway of arachidonic acid metabolism. Cysteinyl (cys) LTs C(4), D(4), and E(4) are long known to contribute to airway contractile responses via ligation of the cysLT1 receptor, and cysLT1 antagonists are beneficial in some patients with asthma. Research advances over the past several years suggest that cysLT1 also mediates the ability of cysLTs to modulate inflammation, immune responses, and airway remodeling. Although less is known about an additional receptor, cysLT2, emerging evidence indicates that it likely also contributes to cysLT actions promoting inflammation, vascular permeability, and perhaps fibrosis. LTB(4), best known as a neutrophil chemoattractant, is now recognized to exert other important effects contributing to inflammatory and immune responses. These recent data highlight a growing appreciation for LTs as pleiotropic effectors, which are integral components in the network of molecules that mediate the expression of asthma.