Pierre Camateros

Secretory Leukocyte Protease Inhibitor Plays an Important Role in the Regulation of Allergic Asthma in Mice

Secretory leukocyte protease inhibitor (SLPI) is an anti-inflammatory protein that is observed at high levels in asthma patients. Resiquimod, a TLR7/8 ligand, is protective against acute and chronic asthma, and it increases SLPI expression of macrophages in vitro. However, the protective role played by SLPI and the interactions between the SLPI and resiquimod pathways in the immune response occurring in allergic asthma have not been fully elucidated. To evaluate the role of SLPI in the development of asthma phenotypes and the effect of resiquimod treatment on SLPI, we assessed airway resistance and inflammatory parameters in the lungs of OVA-induced asthmatic SLPI transgenic and knockout mice and in mice treated with resiquimod. Compared with wild-type mice, allergic SLPI transgenic mice showed a decrease in lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), and plasma IgE levels (p < 0.001). Allergic SLPI knockout mice displayed phenotype changes significantly more severe compared with wild-type mice. These phenotypes included lung resistance (p < 0.001), airway eosinophilia (p < 0.001), goblet cell hyperplasia (p < 0.001), cytokine levels in the lungs (p < 0.05), and plasma IgE levels (p < 0.001). Treatment of asthmatic transgenic mice with resiquimod increased the expression of SLPI and decreased inflammation in the lungs; resiquimod treatment was still effective in asthmatic SLPI knockout mice. Taken together, our study showed that the expression of SLPI protects against allergic asthma phenotypes, and treatment by resiquimod is independent of SLPI expression, displayed through the use of transgenic and knockout SLPI mice.

Polymorphisms in TOLL-Like Receptor Genes and their Roles in Allergic Asthma and Atopy

Allergic asthma is a chronic inflammatory disease of the lung airways cause by genetic and environmental factors. Two quantifiable phenotypes of this disease are airway hyperresponsiveness and atopy. TOLL-like receptors (TLRs) are a family of intracellular and cell surface receptors that can respond to pathogen associated molecular patterns involved in the pathogenesis of asthma. Macrophages, one of the main immune cells involved in asthma, express a variety of TLRs, including TLR 2, 4, 5, 6, 7, 8 and 9. This review focuses on polymorphisms found in TLR genes expressed in macrophages, and their role in asthma. Human studies have detected polymorphisms in TLR genes associated with asthma phenotypes, and studies using murine models have shown that some receptors and their agonistic or antagonistic ligands are capable of modulating the cytokine profile in asthmatics in a protective manner. Therefore, certain receptors and their ligands are being explored as potential immunotherapies for asthma. Recently, several patents have been filed protecting inventions for treating asthma through the use of TLRs and their ligands.

Protein tyrosine phosphatases regulate asthma development in a murine asthma model.

Allergic asthma is a chronic inflammatory disease characterized by Th2-type inflammation. Although the cellular interactions are now well studied, the intracellular signaling involved in asthma development is still a developing field. Protein tyrosine kinases are one focus of such research and their inhibition shows improvement of asthmatic features. Interestingly, very little attention was given to protein tyrosine phosphatases (PTPs), the counterparts to protein tyrosine kinases, in the development of asthma. Previous studies from our laboratory showed that pharmacological inhibition of PTPs induced a transient Th1 response in the spleen. Therefore, we hypothesized that modulation of PTPs could influence asthma development. To assess PTP functions, we used the PTP inhibitor bis-peroxovanadium bpV(phen) in a murine model of asthma during either allergen sensitization or challenge. Inhibition of PTPs during allergen sensitization resulted in the reduction of key features of allergic asthma: serum IgE levels, lung tissue inflammation, eosinophilia, and airway hyperresponsiveness. Of utmost interest, PTP inhibition at allergen challenge resulted in a very similar improvement of asthmatic features. Of further importance, we observed that bpV(phen) treatment modulated cytokine expression in the spleen and, more specifically, favored Th1 cytokines while inhibiting Th2 cytokines. Collectively, we show for the first time that intact activity of PTPs is required for a complete induction of asthma in a mouse model. This clearly suggests that PTPs have a pivotal regulatory role in the development of asthmatic diseases, which opens the possibility of new therapeutic avenues.

Toll-Like Receptor 7/8 Ligand, S28463, Suppresses Ascaris suum–induced Allergic Asthma in Nonhuman Primates

&NA; S28463 (S28), a ligand for Toll‐like receptor 7/8, has been shown to have antiinflammatory properties in rodent models of allergic asthma. The principle goal of this study was to assess whether these antiinflammatory effects can also be observed in a nonhuman primate (NHP) model of allergic asthma. NHPs were sensitized then challenged with natural allergen, Ascaris suum extract. The animals were treated with S28 orally before each allergen challenge. The protective effect of S28 in NHPs was assessed by measuring various asthma‐related phenotypes. We also characterized the metabolomic and proteomic signatures of the lung environment and plasma to identify markers associated with the disease and treatment. Our data demonstrate that clinically relevant parameters, such as wheal and flare response, blood IgE levels, recruitment of white blood cells to the bronchoalveolar space, and lung responsiveness, are decreased in the S28‐treated allergic NHPs compared with nontreated allergic NHPs. Furthermore, we also identified markers that can distinguish allergic from nonallergic or allergic and drug‐treated NHPs, such as metabolites, phosphocreatine and glutathione, in the plasma and BAL fluid, respectively; and inflammatory cytokines, IL‐5 and IL‐13, in the bronchoalveolar lavage fluid. Our preclinical study demonstrates that S28 has potential as a treatment for allergic asthma in primate species closely related to humans. Combined with our previous findings, we demonstrate that S28 is effective in different models of asthma and in different species, and has the antiinflammatory properties clinically relevant for the treatment of allergic asthma.

Mapping of a Chromosome 12 Region Associated with Airway Hyperresponsiveness in a Recombinant Congenic Mouse Strain and Selection of Potential Candidate Genes by Expression and Sequence Variation Analyses

In a previous study we determined that BcA86 mice, a strain belonging to a panel of AcB/BcA recombinant congenic strains, have an airway responsiveness phenotype resembling mice from the airway hyperresponsive A/J strain. The majority of the BcA86 genome is however from the hyporesponsive C57BL/6J strain. The aim of this study was to identify candidate regions and genes associated with airway hyperresponsiveness (AHR) by quantitative trait locus (QTL) analysis using the BcA86 strain. Airway responsiveness of 205 F2 mice generated from backcrossing BcA86 strain to C57BL/6J strain was measured and used for QTL analysis to identify genomic regions in linkage with AHR. Consomic mice for the QTL containing chromosomes were phenotyped to study the contribution of each chromosome to lung responsiveness. Candidate genes within the QTL were selected based on expression differences in mRNA from whole lungs, and the presence of coding non-synonymous mutations that were predicted to have a functional effect by amino acid substitution prediction tools. One QTL for AHR was identified on Chromosome 12 with its 95% confidence interval ranging from 54.6 to 82.6 Mbp and a maximum LOD score of 5.11 (p = 3.68×10−3). We confirmed that the genotype of mouse Chromosome 12 is an important determinant of lung responsiveness using a Chromosome 12 substitution strain. Mice with an A/J Chromosome 12 on a C57BL/6J background have an AHR phenotype similar to hyperresponsive strains A/J and BcA86. Within the QTL, genes with deleterious coding variants, such as Foxa1, and genes with expression differences, such as Mettl21d and Snapc1, were selected as possible candidates for the AHR phenotype. Overall, through QTL analysis of a recombinant congenic strain, microarray analysis and coding variant analysis we identified Chromosome 12 and three potential candidate genes to be in linkage with airway responsiveness.

Mouse Chromosome 4 Is Associated with the Baseline and Allergic IgE Phenotypes

Regulation of IgE concentration in the blood is a complex trait, with high concentrations associated with parasitic infections as well as allergic diseases. A/J strain mice have significantly higher plasma concentrations of IgE, both at baseline and after ovalbumin antigen exposure, when compared to C57BL/6J strain mice. Our objective was to determine the genomic regions associated with this difference in phenotype. To achieve this, we used a panel of recombinant congenic strains (RCS) derived from A/J and C57BL/6J strains. We measured IgE in the RCS panel at baseline and following allergen exposure. Using marker by marker analysis of the RCS genotype and phenotype data, we identified multiple regions associated with the IgE phenotype. A single region was identified to be associated with baseline IgE level, while multiple regions wereassociated with the phenotype after allergen exposure. The most significant region was found on Chromosome 4, from 81.46 to 86.17 Mbp. Chromosome 4 substitution strain mice had significantly higher concentration of IgE than their background parental strain mice, C57BL/6J. Our data presents multiple candidate regions associated with plasma IgE concentration at baseline and following allergen exposure, with the most significant one located on Chromosome 4.

Immunoregulatory role of secretory leukocyte protease inhibitor in allergic asthma

Results Allergic SLPI transgenic mice showed a significant decrease in airway resistance compared to wild-type mice (6.3 ± 1.1 vs. 8.0 ± 2.1 cm H20 × s/ml, p < 0.001), the same effect was observed with inflammatory cell infiltration, eosinophil percentage (24 ± 1.1% vs. 29 ± 2.3%, p < 0.001), goblet cells (6 ± 1.4 vs. 36 ± 4.0%, p < 0.001) in the lungs and IgE levels (2014.1 ± 309.2 vs. 4173.2 ± 685.6 ng/ml, p < 0.001) in plasma. Allergic SLPI knock-out mice displayed significantly higher values compared to wild-type mice. They include lung resistance (8.6 ± 2.7 vs. 6.6 ± 0.5 cm H20*s/ml, p < 0.001), inflammatory cell influx, eosinophils (36.0 ± 2.7 vs. 29.0 ± 1.5%, p < 0.001), goblet cells (40 ± 4.1 vs. 30 ± 1.4%, p < 0.001), cytokine levels in the lungs (p < 0.05) and plasma IgE levels (3598 ± 204.7 vs. 2763 ± 220.3 ng/ml, p < 0.001). Expression of SLPI decreased inflammation in the lungs, plasma IgE levels, and lung resistance, whereas the ablation of SLPI has the opposite effect. Treatment with resiquimod improved airway resistance and inflammation of the lungs in SLPI knockout and wild type, demonstrating that its effect is independent of the expression of SLPI. Conclusions SLPI plays an immunoregulatory role in the respiratory tract by reducing the inflammatory process and by improving lung physiology in a murine model of acute allergic asthma.

Mapping of novel chromosomal regions associated with atopy

Background A panel of recombinant congenic strains (RCS) of mice can be used to study an array of disease related phenotypes [1]. We have used a panel of 33 AcB/BcA RCS, derived from parental strains A/J and C57BL/6J (Figure 1), to study phenotypes of allergic asthma that are difficult to segregate in the human population, such as airway hyperresponsiveness [2]. Each recombinant strain is fully inbred and contains approximately 12.5% of the genome from one parental strain on the background of the other parental strain. Here we present our findings for mapping chromosomal regions associated with atopy, another phenotype of allergic asthma.