Aruna K. Behera

Intranasal gene transfer by chitosan-DNA nanospheres protects BALB/c mice against acute respiratory syncytial virus infection

Respiratory syncytial virus (RSV) infection is often associated in infancy with life-threatening bronchiolitis, which is also a major risk factor for the development of asthma. At present, no effective prophylaxis is available against RSV infection. Herein, we describe an effective prophylactic intranasal gene transfer strategy utilizing chitosan-DNA nanospheres (IGT), containing a cocktail of plasmid DNAs encoding all RSV antigens, except L. A single administration of IGT (25 microg/mouse) induces expression of the mRNA and proteins of all antigens in the lung and results in a significant reduction of viral titers and viral antigen load after acute RSV infection of these mice. IGT-administered mice show no significant change in airway reactivity to methacholine and no apparent pulmonary inflammation. Furthermore, IGT results in significant induction of RSV-specific IgG antibodies, nasal IgA antibodies, cytotoxic T lymphocytes, and interferon-gamma production in the lung and splenocytes compared with controls. Together, these results demonstrate the potential of IGT against acute RSV infection.

Recurrent Respiratory Syncytial Virus Infections in Allergen-Sensitized Mice Lead to Persistent Airway Inflammation and Hyperresponsiveness

Respiratory syncytial virus (RSV) infection is considered a risk factor for bronchial asthma; however, the synergy between allergen sensitization and RSV infection in the development of pulmonary inflammation and asthma has been controversial. In this study the effects of primary and recurrent RSV infection on allergic asthma were examined in a group of control, RSV-infected, Dermatophagoides farinae (Df) allergen-sensitized, and Df allergen-sensitized plus RSV-infected BALB/c mice. Primary RSV infection in Df-sensitized mice transiently increases airway responsiveness, which is accompanied by increases in eosinophilic infiltration, the expression of ICAM-1, and macrophage inflammatory protein-1α (MIP-1α) in the lung tissue. A secondary RSV infection persistently enhances airway responsiveness in Df-sensitized mice, with a concomitant increase in MIP-1α and RSV Ag load in lung tissues. Bulk cultures of thoracic lymph node mononuclear cells demonstrate that acute RSV infection augments both Th1- and Th2-like cytokines, whereas secondary and tertiary infections shift the cytokine profile in favor of the Th2-like cytokine response in Df-sensitized mice. The elevated total serum IgE level in the Df-sensitized mice persists following only RSV reinfection. Thus, recurrent RSV infections in Df-sensitized mice augment the synthesis of Th2-like cytokines, total serum IgE Abs, and MIP-1α, which are responsible for persistent airway inflammation and hyperresponsiveness, both of which are characteristics of asthma.

Chitosan IFN-γ-pDNA Nanoparticle (CIN) Therapy for Allergic Asthma

BackgroundAllergic subjects produce relatively low amounts of IFN-γ, a pleiotropic Th-1 cytokine that downregulates Th2-associated airway inflammation and hyperresponsiveness (AHR), the hallmarks of allergic asthma. Adenovirus-mediated IFN-γ gene transfer reduces AHR, Th2 cytokine levels and lung inflammation in mice, but its use would be limited by the frequency of gene delivery required; therefore, we tested chitosan/IFN-γ pDNA nanoparticles (CIN) for in situ production of IFN-γ and its in vivo effects.MethodsCIN were administered to OVA-sensitized mice to investigate the possibility of using gene transfer to modulate ovalbumin (OVA)-induced inflammation and AHR.ResultsMice treated with CIN exhibit significantly lower AHR to methacholine challenge and less lung histopathology. Production of IFN-γ is increased after CIN treatment while the Th2-cytokines, IL-4 and IL-5, and OVA-specific serum IgE are reduced compared to control mice. AHR and eosinophilia are also significantly reduced by CIN therapy administered therapeutically in mice with established asthma. CIN was found to inhibit epithelial inflammation within 6 hours of delivery by inducing apoptosis of goblet cells. Experiments performed on STAT4-defective mice do not show reduction in AHR with CIN treatment, thus implicating STAT4 signaling in the mechanism of CIN action.ConclusionThese results demonstrate that mucosal CIN therapy can effectively reduce established allergen-induced airway inflammation and AHR.

Intranasal IFN-γ gene transfer protects BALB/c mice against respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a major respiratory pathogen in infants, young children and the elderly and causes severe bronchiolitis and asthma. In an effort to develop a preventive IFN-γ therapy against RSV infection, an intranasal gene transfer strategy was utilized. Intranasal administration of a plasmid expressing the IFN-γ cDNA (pIFN-γ) resulted in the expression of IFN-γ in murine lungs and decreased RSV replication. The mice administered with pIFN-γ and then infected with RSV exhibited a significant decrease in broncho-alveolar lavage lymphocyte and neutrophil counts. A significant reduction in epithelial cell damage, infiltration of mononuclear cells in the peribronchiolar and perivascular regions, and thickening of the septa was observed in the lungs of mice treated with pIFN-γ when compared to controls. These results suggest that intranasal IFN-γ gene transfer results in decreased RSV replication and pulmonary inflammation and may be useful against RSV infection.

Adenovirus-Mediated Interferon γ Gene Therapy for Allergic Asthma: Involvement of Interleukin 12 and STAT4 Signaling

Allergic asthma is associated with airway inflammation and hyperresponsiveness caused by the dysregulated production of cytokines secreted by allergen-specific helper T type 2 (Th2) cells. Allergic subjects produce relatively low amounts of interferon gamma (IFN-gamma), a pleiotropic Th1 cytokine that downregulates Th2-associated responses. In this study, we examined the possibility of modulating ovalbumin (OVA)-induced inflammation and airway hyperreactivity (AHR) by recombinant adenovirus-mediated IFN-gamma (Ad-IFN-gamma) gene transfer. OVA-sensitized mice treated with Ad-IFN-gamma exhibit significantly lower levels of Th2 cytokines interleukin 4 (IL-4) and IL-5, OVA-specific serum IgE, lung eosinophilia, and AHR in response to methacholine challenge compared with control mice. The lung sections of the treated mice show less epithelial damage, mucous plugging, and eosinophil infiltration than controls. In contrast, Ad-IFN-gamma-treated mice express significantly higher levels of IFN-gamma and IL-12 when compared with controls. Moreover, administration of Ad-IFN-gamma to mice with established AHR significantly reduced AHR, Th2 cytokines, and lung inflammation. The IFN-gamma effects were dependent on IL-12 and STAT4 (signal transducer and activator of transcription 4), as mice treated with antibodies to IL-12 and STAT4 deficient mice show attenuated Ad-IFN-gamma responses. Thus, these results demonstrate that mucosal Ad-IFN-gamma gene transfer can effectively attenuate established allergen-induced airway inflammation and AHR, predominantly through an IL-12- and STAT4-dependent mechanism.

Respiratory syncytial virus infection activates STAT signaling in human epithelial cells.

Acute respiratory syncytial virus (RSV) infection causes airway inflammation and exacerbates asthma, but the mechanism of inflammation is poorly understood. The role of the STAT-signaling pathway in RSV infection in epithelial cells was examined in this study. DNA microarray analyses of RSV-infected human alveolar type II (A549) epithelial cells identified several genes whose expression was altered from -5.5 to +56.4-fold. Four of the highly expressed genes contained STAT-binding elements. In A549 and normal human bronchial epithelial cells (NHBE), RSV induced phosphorylation and nuclear translocation of STAT-1alpha that was abrogated when RSV attachment was blocked. Treatment with a JAK-2 inhibitor or transfection with dominant-negative STAT-1alpha blocked STAT-1alpha activation and RSV infection. RSV also activated STAT-3 and IL-6 specific antibodies blocked this activation. Thus, activation of the STAT-1alpha and STAT-3 pathways play a role in RSV infection.

ERK-1/2 activity is required for efficient RSV infection

Respiratory syncytial virus (RSV) infection up‐regulates the expression of genes encoding proinflammatory mediators in bronchial epithelial cells. However, the specific signaling events immediately following RSV exposure are poorly understood. Herein, we report that RSV attachment to A549 cells activates both ERK‐1 and ERK‐2 pathways within 5 min. Inhibition of ERK pathways significantly decreases RSV infection of these cells compared to controls. These results demonstrate that the activation of the ERK‐1/2 is required in RSV‐induced early gene expression.

An immunocompromised BALB/c mouse model for respiratory syncytial virus infection

BackgroundRespiratory syncytial virus (RSV) infection causes bronchiolitis in infants and children, which can be fatal, especially in immunocompromised patients. The BALB/c mouse, currently used as a model for studying RSV immunopathology, is semi-permissive to the virus. A mouse model that more closely mimics human RSV infection is needed. Since immunocompromised conditions increase risk of RSV infection, the possibility of enhancing RSV infection in the BALB/c mouse by pretreatment with cyclophosphamide was examined in this study. BALB/c mice were treated with cyclophosphamide (CYP) and five days later, they were infected with RSV intranasally. Pulmonary RSV titers, inflammation and airway hyperresponsiveness were measured five days after infection.ResultsCYP-treated mice show higher RSV titers in their lungs of than the untreated mice. Also, a decreased percentage of macrophages and an increased number of lymphocytes and neutrophils were present in the BAL of CYP-treated mice compared to controls. The CYP-treated group also exhibited augmented bronchoalveolar and interstitial pulmonary inflammation. The increased RSV infection in CYP-treated mice was accompanied by elevated expression of IL-10, IL-12 and IFN-γ mRNAs and proteins compared to controls. Examination of CYP-treated mice before RSV infection showed that CYP treatment significantly decreased both IFN-γ and IL-12 expression.ConclusionsThese results demonstrate that CYP-treated BALB/c mice provide a better model for studying RSV immunopathology and that decreased production of IL-12 and IFN-γ are important determinants of susceptibility to RSV infection.

Differential cytokine mRNA expression in Dermatophagoides farinae allergen-sensitized and respiratory syncytial virus-infected mice.

The interaction between mite allergen sensitization and respiratory syncytial virus (RSV) infection at the level of cytokine mRNA expression was examined in a murine model in the present study. Primary RSV infection enhances expression of inflammatory cytokines such as IL-6, IFN-gamma, and eotaxin in the lung and upregulates the expression of Th2-like cytokines IL-10 and IL-13 in the spleen in BALB/c mice. Mite antigen-sensitized and RSV-infected (ASRSV) mice show enhanced (P < 0.05) total serum IgE compared to antigen-sensitized mice. However, the levels of viral mRNA in the lung tissues are comparable between RSV-infected and ASRSV mice. It is concluded that compartmentalization of cytokine expression following RSV infection plays a role in the augmentation of Th2-like and IgE antibody response to RSV.

Chitosan Interferon-γ Nanogene Therapy for Lung Disease: Modulation of T-Cell and Dendritic Cell Immune Responses

The use of chitosan nanoparticles as carriers for expression plasmids represents a major improvement in gene expression technology. We demonstrated previously that treatment with chitosan interferon-γ (IFN-γ) plasmid deoxyribonucleic acid (DNA) nanoparticles (chitosan interferon-γ nanogene [CIN]) led to in situ production of IFN-γ and a reduction in inflammation and airway reactivity in mice, but the mechanism underlying the immunomodulatory effects of CIN remains unclear. In this report, the effect of CIN treatment on the immune responses of CD8+ T cells and dendritic cells was examined in a BALB/c mouse model of ovalbumin (OVA)-induced allergic asthma. OT1 mice (OVA-T cell receptor [TCR] transgenic) were also used to test the effects of CIN on OVA-specific CD8+ T cells. CIN treatment caused a reduction in IFN-γ production in a subpopulation of OVA-specific CD8+ T cells cultured in vitro in the presence of OVA. CIN also reduced apoptosis of the CD8+ T cells. Examination of dendritic cells from lung and lymph nodes indicated that CIN treatment decreased their antigen-presenting activity, as evident from the reduction in CD80 and CD86 expression. Furthermore, CIN treatment significantly decreased the number of CD11c+b+ dendritic cells in lymph nodes, suggesting that endogenous IFN-γ expression may immunomodulate dendritic cell migration and activation. CIN therapy results in a reduction in proinflammatory CD8+ T cells and decreases the number and antigen-presenting activity of dendritic cells.