Asthma Phenotype In Mice Research Articles

Shikonin alleviates asthma phenotypes in mice via an airway epithelial STAT3-dependent mechanism.

Asthma is an inflammatory disease where the balance between Th1/Th2 and Th17/Treg plays a crucial role in its pathogenesis. Shikonin is used to treat a variety of autoimmune diseases due to its good anti-inflammatory activity. However, the effect and mechanism of shikonin on asthma remain unknown. Mice were sensitized with ovalbumin (OVA)/house dust mite (HDM) and treated with shikonin. Lung inflammation was assessed histologically and via flow cytometry. Bronchoalveolar lavage fluid (BALF) was analyzed for cell counts and cytokines. Shikonin's impact on p-STAT3 was studied in vivo and in vitro. Shikonin inhibited OVA or HDM-induced inflammation and airway hyperresponsiveness. Upon treatment, a restoration of the Th1/Th2 and Th17/Treg balance was observed, evidenced by a reduction in IL-4 and IL-17A levels in BALF, alongside an elevation in interferon-gamma and IL-10. Furthermore, shikonin impeded the infiltration of eosinophils, neutrophils, macrophages, and lymphocytes into lung tissue. The observed decrease in STAT3 phosphorylation and diminished nuclear translocation of p-STAT3 confirmed that shikonin promotes the balance of Th1/Th2 and Th17/Treg by regulating airway epithelial STAT3. Shikonin mitigates asthma symptoms through a STAT3-dependent mechanism, indicating its potential as an anti-asthmatic therapeutic agent.

Attenuated asthma phenotype in mice with a fetal-like antigen receptor repertoire

We hypothesized that the scarcity of N-nucleotides might contribute to the inability of the neonate to mount a robust allergic immune response. To test this, we used terminal deoxyribunucleotidyl Transferase deficient (TdT−/−) mice, which express “fetal-like” T cell receptor and immunoglobulin repertoires with largely germline-encoded CDR3 regions. Intraperitoneal sensitization was followed by aerosol provocation with either PBS or the allergen OVA in both TdT−/− mice and wild-type mice to develop allergic respiratory inflammation. The effects of this procedure were investigated by lung function test, immunological analysis of serum and brochoalveolar lavage. The local TH2 cytokine milieu was significantly attenuated in TdT−/− mice. Within this group, the induction of total IgE levels was also significantly reduced after sensitization. TdT−/− mice showed a tendency toward reduced eosinophilic inflow into the bronchial tubes, which was associated with the elimination of respiratory hyperreactivity. In conclusion, in a murine model of allergic airway inflammation, the expression of fetal-like antigen receptors was associated with potent indications of a reduced ability to mount an asthma phenotype. This underlines the importance of somatically-generated antigen-receptor repertoire diversity in type one allergic immune responses and suggests that the fetus may be protected from allergic responses, at least in part, by controlling N addition.

Contributions of direct versus indirect mechanisms for regulatory dendritic cell suppression of asthmatic allergen-specific IgG1 antibody responses.

IL-10-differentiated dendritic cells (DC10) can reverse the asthma phenotype in mice, but how they suppress the asthmatic B cell response is unclear. Herein we assessed the mechanism(s) by which DC10 and DC10-induced Treg affect IgG1 production in asthma. We observed a rapid decline in lung-resident OVA-specific IgG1-secreting B cells on cessation of airway allergen challenge, and intraperitoneal DC10 therapy did not amplify that (p>0.05). It did however increase the loss of IgG1-B cells from the bone marrow (by 45+/-7.2%; p≤0.01) and spleen (by 65+/-17.8%; p≤0.05) over 2 wk. Delivery of OVA-loaded DC10 directly into the airways of asthmatic mice decreased the lung IgG1 B cell response assessed 2 dy later by 33+/-9.7% (p≤0.01), while their co-culture with asthmatic lung cell suspensions reduced the numbers of IgG1-secreting cells by 56.5+/-9.7% (p≤0.01). This effect was dependent on the DC10 carrying intact allergen on their cell surface; DC10 that had phagocytosed and fully processed their allergen were unable to suppress B cell responses, although they did suppress asthmatic Th2 cell responses. We had shown that therapeutic delivery of DC10-induced Treg can effectively suppress asthmatic T and B cell (IgE and IgG1) responses; herein CD4+ cells or Treg from the lungs of DC10-treated OVA-asthmatic mice suppressed in vitro B cell IgG1 production by 52.2+/-8.7% (p≤0.001) or 44.6+/-12.2% (p≤0.05), respectively, but delivery of DC10-induced Treg directly into the airways of asthmatic mice had no discernible impact over 2 dy on the numbers of lung IgG1-secreting cells (p≥0.05). In summary, DC10 treatment down-regulates OVA-specific B cell responses of asthmatic mice. While DC10 that carry intact allergen on their cell surface can dampen this response, DC10-induced Treg are critical for full realization of this outcome. This suggests that infectious tolerance is an essential element in regulatory DC control of the B cell response in allergic asthma.

β2-Adrenoceptor signaling in airway epithelial cells promotes eosinophilic inflammation, mucous metaplasia, and airway contractility

The mostly widely used bronchodilators in asthma therapy are β2-adrenoreceptor (β2AR) agonists, but their chronic use causes paradoxical adverse effects. We have previously determined that β2AR activation is required for expression of the asthma phenotype in mice, but the cell types involved are unknown. We now demonstrate that β2AR signaling in the airway epithelium is sufficient to mediate key features of the asthmatic responses to IL-13 in murine models. Our data show that inhibition of β2AR signaling with an aerosolized antagonist attenuates airway hyperresponsiveness (AHR), eosinophilic inflammation, and mucus-production responses to IL-13, whereas treatment with an aerosolized agonist worsens these phenotypes, suggesting that β2AR signaling on resident lung cells modulates the asthma phenotype. Labeling with a fluorescent β2AR ligand shows the receptors are highly expressed in airway epithelium. In β2AR-/- mice, transgenic expression of β2ARs only in airway epithelium is sufficient to rescue IL-13-induced AHR, inflammation, and mucus production, and transgenic overexpression in WT mice exacerbates these phenotypes. Knockout of β-arrestin-2 (βarr-2-/-) attenuates the asthma phenotype as in β2AR-/- mice. In contrast to eosinophilic inflammation, neutrophilic inflammation was not promoted by β2AR signaling. Together, these results suggest β2ARs on airway epithelial cells promote the asthma phenotype and that the proinflammatory pathway downstream of the β2AR involves βarr-2. These results identify β2AR signaling in the airway epithelium as capable of controlling integrated responses to IL-13 and affecting the function of other cell types such as airway smooth muscle cells.

Defining the Cell Type through Which the Asthma-Associated Intercellular Junction Protein Alpha-T-Catenin Drives Asthma Phenotypes in Mice

Defining the Cell Type through Which the Asthma-Associated Intercellular Junction Protein Alpha-T-Catenin Drives Asthma Phenotypes in Mice

Correction: Gene Silencing of SOCS3 by siRNA Intranasal Delivery Inhibits Asthma Phenotype in Mice

Correction: Gene Silencing of SOCS3 by siRNA Intranasal Delivery Inhibits Asthma Phenotype in Mice

Gene Silencing of SOCS3 by siRNA Intranasal Delivery Inhibits Asthma Phenotype in Mice

Suppresors of cytokine signaling (SOCS) proteins regulate cytokine responses and control immune balance. Several studies have confirmed that SOCS3 is increased in asthmatic patients, and SOCS3 expression is correlated with disease severity. The objective of this study was to evaluate if delivering of SOCS3 short interfering RNA (siRNA) intranasally in lungs could be a good therapeutic approach in an asthma chronic mouse model. Our results showed that intranasal treatment with SOCS3-siRNA led to an improvement in the eosinophil count and the normalization of hyperresponsiveness to methacholine. Concomitantly, this treatment resulted in an improvement in mucus secretion, a reduction in lung collagen, which are prominent features of airway remodeling. The mechanism implies JAK/STAT and RhoA/Rho-kinase signaling pathway, because we found a decreasing in STAT3 phosphorylation status and down regulation of RhoA/Rho-kinase protein expression. These results might lead to a new therapy for the treatment of chronic asthma.

Regulatory dendritic cell expression of MHCII and IL‐10 are jointly requisite for induction of tolerance in a murine model of OVA‐asthma

Allergen-presenting dendritic cells differentiated with IL-10 (DC10) reverse the asthma phenotype in mice by converting their Th2 cells to regulatory T cells (Tregs). DC10 express elevated levels of IL-10, but substantially reduced levels of MHCII and costimulatory molecules, so the relationships between these factors with each other and tolerogenicity have not been clearly elucidated. We assessed the roles of these inputs in DC10 reversal of OVA-associated asthma-like disease by treating affected mice with OVA-pulsed DC10 generated from wild-type or IL-10-sufficient MHCII(-/-) or CD80/CD86(-/-) mice, or with MHCII-intact IL-10-silenced DC10. IL-10 silencing did not discernibly affect the cells' immunobiology (e.g., costimulatory molecules, chemokines), but it eliminated IL-10 secretion and the cell's abilities to induce tolerance, as determined by assessments of airway hyper-responsiveness, eosinophilia, and Th2 responses to recall OVA challenge. MHCII(-/-) DC10 expressed normal levels of IL-10, but, nevertheless, were unable to induce allergen tolerance in asthma phenotype mice, while tolerance induced by CD80/CD86(-/-) DC10 was attenuated but not eliminated. We also assessed the induction of multiple Treg cell markers (e.g., ICOS, PD-1, GITR) on pulmonary CD25(+) Foxp3(+) cells in the treated mice. Wild-type DC10 treatments upregulated expression of each marker, while neither IL-10-silenced nor MHCII(-/-) DC10 did so, and the CD80/86(-/-) DC10 induced an intermediate Treg cell activation phenotype. Both IL-10 and MCHII expression by DC10 are requisite, but not sufficient for tolerance induction, suggesting that DC10 and Th2 effector T cells must be brought together in a cognate fashion in order for their IL-10 to induce tolerance.

Substance P antagonist improves both obesity and asthma in a mouse model

Evidence suggests a causal relationship between obesity and asthma; however, the underlying mechanisms remain unknown. Substance P (SP), involved in neurogenic inflammation by acting through its receptor NK1-R, seems to participate in obese-asthma phenotype in mice. To evaluate the effect of a selective substance P receptor antagonist on a mouse model of diet-induced obesity and asthma. Diet-induced obese Balb/c mice were sensitized and challenged with ovalbumin (OVA) and treated with a selective NK1-R antagonist or placebo. Serum glucose, insulin, IL-6, resistin, and OVA-specific IgE levels were quantified. A score for peribronchial inflammation in lung histology was used. Cells were counted in bronchoalveolar lavage fluid. Adipocyte sizes were measured. Ovalbumin-obese mice treated with NK1-R antagonist had lower weight (P=0.0002), reduced daily food intake (P=0.0021), reduced daily energy intake (P=0.0021), reduced surface adipocyte areas (P<0.0001), lower serum glucose (P=0.04), lower serum insulin (P=0.03), lower serum IL-(P=0.0022), lower serum resistin (P=0.0043), lower serum OVA-specific IgE (P=0.035), and lower peribronchial inflammation score (P<0.0001) than nontreated OVA-obese mice. We observed an interaction between obesity, allergen sensitization, and treatment with NK1-R antagonist for metabolic and systemic biomarkers, and for allergen sensitization and bronchial inflammation, showing a synergy between these variables. In an experimental model of obesity and asthma in mice, NK1-R blockade improved metabolic and systemic biomarkers, as well as allergen sensitization and bronchial inflammation. These positive effects support a common pathway in the obese-asthma phenotype and highlight SP as a target with potential clinical interest in the obese-asthma epidemics.

Induction of Prolonged Asthma Tolerance by IL-10–Differentiated Dendritic Cells: Differential Impact on Airway Hyperresponsiveness and the Th2 Immunoinflammatory Response

IL-10-differentiated dendritic cells (DC10s) can prevent allergen sensitization and reverse the asthma phenotype in mice with established disease. However, little is known about the time-frames over which this tolerance is effective. We report that at 2 wk after i.p. or transtracheal delivery of 1 × 10(6) OVA-, but not house dust mite- presenting, DC10s to OVA-asthmatic mice, significant diminution of airway hyperresponsiveness (AHR) was first apparent, whereas AHR was abrogated between 3 and 10 wk posttreatment. At 13 wk, AHR returned to pretreatment levels but could again be reversed by DC10 retreatment. The impact of a single DC10 treatment on airway eosinophil and Th2 cytokine responses to recall OVA challenge, and on OVA-specific IgE/IgG1 responses, was substantial at 3 wk posttreatment, but progressively increased thereafter, such that at 8 mo, airway eosinophil and Th2 responses to recall allergen challenge remained ∼85-95% suppressed relative to saline-treated asthmatic mice. Four biweekly DC10 treatments, whether transtracheal or i.p., reduced all asthma parameters to near background by 8 wk, whereas s.c. DC10 treatments did not affect AHR but did reduce the airway Th2 responses (i.v. DC10 had no discernible effects). Repeated challenge of the DC10-treated mice with aerosolized OVA (100 μg/ml) did not reverse tolerance, but treatment with the indoleamine-2,3-dioxygenase antagonist 1-methyltryptophan or neutralizing anti-IL-10R from days 12 to 21 after DC10 therapy partially reversed tolerance (Th2 cytokine responses, but not AHR). These findings indicate that DC10-induced Th2 tolerance in asthmatic animals is long lived, but that DC10s employ distinct mechanisms to affect AHR versus Th2 immunoinflammatory parameters.

Next stop for HDL: the lung

Next stop for <scp>HDL</scp>: the lung

Essential Role of B7-H1 in Double-Stranded RNA–Induced Augmentation of an Asthma Phenotype in Mice

Clinical and epidemiological studies have shown the contribution of viral infection to the development of allergic asthma. Many RNA viruses, pathogenic for the respiratory tract, generate double-stranded (ds)RNA during their replication. Typical innate immune responses triggered by dsRNA involve the endosomal and cytoplasmic pathways. The former is mediated by Toll/IL-1R domain-containing adaptor inducing IFN-β (TRIF), and the latter by IFN-β promoter stimulator 1 (IPS-1). We explored the effect of polyinocinic polycytidilic acid, a synthetic dsRNA, on the development of an asthma phenotype in mice. Administration of dsRNA during ovalbumin sensitization augmented airway eosinophilia and airway hyperresponsiveness after an antigen challenge, which was associated with enhanced induction of IL-13-producing CD8(+) T cells. The augmentation was induced in IPS-1-deficient mice but not in TRIF-deficient mice. The interactions between dendritic cells (DCs) and T cells are regulated by B7-family costimulatory molecules, including B7-H1 (also known as PD-L1), a putative ligand for programmed death-1 (PD-1). Treatment of bone marrow-derived DCs with dsRNA enhanced B7-H1 expression in a TRIF-dependent manner. Additionally, dsRNA increased B7-H1 expression on DCs in the draining lymph nodes of ovalbumin-sensitized mice. The augmentation of the asthma phenotype was prevented by the treatment of mice with anti-B7-H1 mAb but not with anti-PD-1 mAb. The augmentation was not induced in B7-H1-deficient mice. These results suggest that dsRNA-triggered activation of the innate immune system in sensitization leads to augmentation of the asthma phenotype via IL-13 mainly from CD8(+) T cells. B7-H1 plays a crucial role in the process without requiring interaction with PD-1.

Therapeutic induction of tolerance by IL-10-differentiated dendritic cells in a mouse model of house dust mite-asthma*

It has been reported that retrovirally transduced IL-10-expressing dendritic cells can reverse the asthma phenotype in mice, but that i.v. delivery of dendritic cells differentiated with IL-10 alone (DC10) does not. We report herein DC10 can be highly effective therapeutically in experimental asthma. BALB/c mice were sensitized by airway exposure to house dust mite (HDM) without use of adjuvants, then treated with 10⁶ allergen-presenting DC10. We assessed the airway hyperresponsiveness (AHR) to methacholine, circulating levels of IgE and IgG1, and airway recall responses to HDM allergen, including eosinophilia and Th2 cytokines. We also asked whether the DC10 treatments induced tolerance through activation of pulmonary regulatory T cell activities. In vitro, cognate-, but not irrelevant-, allergen-presenting DC10 productively engaged pulmonary Th2-phenotype CD4(+) cells magnetically sorted from HDM-asthmatic mice in Forster (or fluorescence) resonance energy transfer assays. In vivo, treatment of HDM-asthmatic mice with HDM, but not ovalbumin-presenting DC10 abrogated AHR within 4 weeks, and significantly reduced airway eosinophilia, IL-4, IL-5, and IL-13 responses, and circulating HDM-specific IgE and IgG1 levels (each, P ≤ 0.01 versus control mice). CD4(+) CD25(+) Foxp3(+) cells from the lungs of the DC10-treated mice, but not those from asthmatic animals, up-regulated expression of the activated regulatory T cell markers CTLA4 and LAG3, and passive transfer of pulmonary CD4(+) T cells from these mice induced allergen tolerance in HDM-asthmatic recipients. These findings indicate that allergen-presenting DC10 treatments up-regulate T cell regulatory activities and thereby induce allergen-specific tolerance in a relevant model of human asthma.

Effect of Supplemental Folic Acid in Pregnancy on Childhood Asthma: A Prospective Birth Cohort Study

This study aimed to investigate the effect of the timing, dose, and source of folate during pregnancy on childhood asthma by using data from an Australian prospective birth cohort study (n = 557) from 1998 to 2005. At 3.5 years and 5.5 years, 490 and 423 mothers and children participated in the study, respectively. Maternal folate intake from diet and supplements was assessed by food frequency questionnaire in early (<16 weeks) and late (30-34 weeks) pregnancy. The primary outcome was physician-diagnosed asthma, obtained by maternal-completed questionnaire. Asthma was reported in 11.6% of children at 3.5 years (n = 57) and in 11.8% of children at 5.5 years (n = 50). Folic acid taken in supplement form in late pregnancy was associated with an increased risk of childhood asthma at 3.5 years (relative risk (RR) = 1.26, 95% confidence interval (CI): 1.08, 1.43) and with persistent asthma (RR = 1.32, 95% CI: 1.03, 1.69). The effect sizes did not change with adjustment for potential confounders. The association was similar at 5.5 years but did not reach statistical significance (RR = 1.17, 95% CI: 0.96, 1.42) in univariable models. These findings on childhood asthma support previous observations that supplementation with folate in pregnancy leads to an allergic asthma phenotype in mice via epigenetic mechanisms and is associated with poorer respiratory outcomes in young children.

Animal models of asthma

Studies in animal models form the basis for much of our current understanding of the pathophysiology of asthma, and are central to the preclinical development of drug therapies. No animal model completely recapitulates all features of the human disease, however. Research has focused primarily on ways to generate allergic inflammation by sensitizing and challenging animals with a variety of foreign proteins, leading to an increased understanding of the immunological factors that mediate the inflammatory response and its physiological expression in the form of airways hyperresponsiveness. Animal models of exaggerated airway narrowing are also lending support to the notion that asthma may represent an abnormality of the airway smooth muscle. The mouse is now the species of choice for asthma research involving animals. This presents practical challenges for physiological study because the mouse is so small, but modern imaging methodologies, coupled with the forced oscillation technique for measuring lung mechanics, have allowed the asthma phenotype in mice to be precisely characterized.

B7-DC induced by IL-13 works as a feedback regulator in the effector phase of allergic asthma

B7-DC is a costimulatory molecule belonging to the B7 family. We previously found that treatment with anti-B7-DC mAb during the effector phase enhances asthma phenotypes in mice. We investigated the mechanisms of B7-DC induction and how B7-DC regulates asthma phenotypes. In allergen-challenged IFN-γ-deficient mice, anti-B7-DC mAb failed to enhance the asthma phenotypes although the induction of B7-DC on dendritic cells of the mice was comparable with that on dendritic cells of wild-type mice. B7-DC on dendritic cells was up-regulated by IL-13 in vitro. The induction of B7-DC on dendritic cells after allergen challenge was attenuated by blockade of IL-13 in vivo. The asthma phenotypes were enhanced in B7-DC-deficient mice, more than in wild-type mice. The enhancement was concurrent with the down-regulation of IFN-γ and up-regulation of IL-13. These results suggest that B7-DC induced by IL-13 works as a feedback regulator by up-regulating IFN-γ production during the effector phase of allergic asthma.