γ-Tocopherol Attenuates Ozone-induced Exacerbation of Allergic Rhinosinusitis in Rats

Compared to healthy subjects, individuals with allergic airway disease (e.g., asthma, allergic rhinitis) have enhanced inflammatory responses to inhaled ozone. We created a rodent model of ozone-enhanced allergic nasal responses in Brown Norway rats to test the therapeutic effects of the dietary supplement g-tocopherol (γT). Ovalbumin (OVA)-sensitized rats were intranasally challenged with 0% or 0.5% OVA (in saline) on Days 1 and 2, and then exposed to 0 or 1 ppm ozone (eight hours/day) on Days 4 and 5. Rats were also given 0 or 100 mg/kg γT (p.o., in corn oil) on days 2 through 5, beginning twelve hours after the last OVA challenge. On Day 6, nasal tissues were collected for histological evaluation and mor-phometric analyses of intraepithelial mucosubstances (IM) and eosinophilic inflammation. Nasal septal tissue was microdissected and analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) for mucin glycoprotein 5AC (MUC5AC) expression levels. Histological analysis revealed mild to moderate eosinophil influx in the mucosa lining the nasal airways and maxillary sinus of OVA-challenged rats (eosinophilic rhinosinusitis). Ozone exposure of allergic rats further increased eosinophils in the maxillary sinus (400%), nasolacrimal duct (250%), and proximal midseptum (150%). Storage of intraepithelial mucosubstances (IM) was not significantly affected by OVA challenge in filtered air-exposed rats, but it was increased by ozone in the septum (45%) and maxillary sinus (55%) of allergic compared to control rats. Treatment with γT attenuated the ozone/ OVA-induced synergistic increases in IM and mucosal eosinophils in both nasal and paranasal airways. γ-Tocopherol also blocked OVA and ozone-induced MUC5AC gene expression. Together, these data describe a unique model of ozone enhancement of allergic rhinosinusitis and the novel therapeutic efficacy of a common supplement, γT, to inhibit ozone exacerbation of allergic airway responses

Vitamin E forms inhibit IL-13/STAT6-induced eotaxin-3 secretion by up-regulation of PAR4, an endogenous inhibitor of atypical PKC in human lung epithelial cells

Eotaxin-3 (CCL-26), a potent chemokine for eosinophil recruitment and contributing significantly to the pathogenesis of asthma, is secreted by lung epithelial cells in response to T helper 2 cytokines including interleukin 13 (IL-13). Here we showed that vitamin E forms, but not their metabolites, differentially inhibited IL-13-stimulated generation of eotaxin-3 in human lung epithelial A549 cells. The relative inhibitory potency was γ-tocotrienol (γ-TE) (IC50 ~15 μM) > γ-tocopherol, δ-tocopherol (IC50 ~25-50 μM) > α-tocopherol. Consistent with suppression of eotaxin, γ-TE treatment impaired IL-13-induced phosphorylation of STAT6, the key transcription factor for activation of eotaxin expression, and consequently blocked IL-13 stimulated DNA-binding activity of STAT6. In search of the upstream target of γTE by using inhibitor and siRNA approaches, we discovered that the atypical protein kinase C (aPKC) signaling, instead of classical PKC, p38 MAPK, JNK or ERK, played a critical role in IL-13-stimulated eotaxin generation and STAT6 activation. While showing no obvious effect on aPKC expression or phosphorylation, γ-TE treatment resulted in increased expression of PAR4, an endogenous negative regulator of aPKCs. Importantly, γ-TE treatment led to enhanced formation of aPKC/PAR4 complex that is known to reduce aPKC activity via protein-protein crosstalk. Our study demonstrated that γ-TE inhibited IL-13/STAT6-activated eotaxin secretion via up-regulation of PAR4 expression and enhancement of aPKC-PAR-4 complex formation. These results support the notion that specific vitamin E forms may be useful anti-asthmatic agents

Ozone enhancement of lower airway allergic inflammation is prevented by γ-tocopherol

Ozone is a commonly encountered environmental oxidant which has been linked to asthma exacerbation in epidemiological studies. Ozone induces airway inflammation and enhances response to inhaled allergen. It has been suggested that antioxidant therapy may minimize the adverse effects of ozone in asthma. We have previously shown that the antioxidant gamma-tocopherol (γT), an isoform of vitamin E, also has anti-inflammatory effects. We employed a Brown Norway rat model of ozone-enhanced allergic responses to test the therapeutic effects of γT on O3-induced airway inflammation. Ovalbumin (OVA) -sensitized rats were intranasally challenged with 0 or 0.5% OVA on Days 1 and 2, and exposed to 0 or 1 ppm ozone (8h/day) on Days 4 and 5. Rats were also given 0 or 100 mg/kg γT on Days 2 through 5. Pulmonary tissue and bronchoalveolar lavage fluid (BALF) were collected on Day 6. OVA challenge caused increased total cells (267% increase) and eosinophils (4000%) in BALF that was unaffected by ozone exposure. Morphometric evaluation of lung tissue revealed increases in intraepithelial mucosubstances (IM) (300%) and subepithelial eosinophils (400%) in main axial airways. Ozone exposure of allergic rats enhanced IM increases in proximal axial airways (200%), induced cys-leukotrienes, MCP-1 and IL-6 production in BALF, and upregulated expression of IL-5 and IL-13 mRNA. γT treatment had no effect on IM increases by allergen, but blocked enhancement by ozone. γT attenuated both OVA- or ozone –stimulated eosinophilic infiltration, and increases of BALF cys-leukotrienes, MCP-1 and IL-6, as well as IL-5 and IL-13 mRNA. These data demonstrate broad anti-inflammatory effects of a γT and suggest it may be an effective therapy of allergic airway inflammation

Protective role of CFTR during fungal infection of cystic fibrosis bronchial epithelial cells with Aspergillus fumigatus

Lung infection with the fungus Aspergillus fumigatus (Af) is a common complication in cystic fibrosis (CF) and is associated with loss of pulmonary function. We established a fungal epithelial co-culture model to examine the impact of Af infection on CF bronchial epithelial barrier function using Af strains 10AF and AF293-GFP, and the CFBE41o- cell line homozygous for the F508del mutation with (CF+CFTR) and without (CF) normal CFTR expression. Following exposure of the epithelial surface to Af conidia, formation of germlings (early stages of fungal growth) was detected after 9-12 hours and hyphae (mature fungal growth) after 12-24 hours. During fungal morphogenesis, bronchial epithelial cells showed signs of damage including rounding, and partial detachment after 24 hours. Fluorescently labeled conidia were internalized after 6 hours and more internalized conidia were observed in CF compared to CF+CFTR cells. Infection of the apical surface with 10AF conidia, germlings, or hyphae was performed to determine growth stage-specific effects on tight junction protein zona occludens protein 1 (ZO-1) expression and transepithelial electrical resistance (TER). In response to infection with conidia or germlings, epithelial barrier function degraded time-dependently (based on ZO-1 immunofluorescence and TER) with a delayed onset in CF+CFTR cell monolayers and required viable fungi and apical application. Infection with hyphae caused an earlier onset and faster rate of decline in TER compared to conidia and germlings. Gliotoxin, a major Af virulence factor, caused a rapid decline in TER and induced a transient chloride secretory response in CF+CFTR but not CF cells. Our findings suggest growth and internalization of Af result in deleterious effects on bronchial epithelial barrier function that occurred more rapidly in the absence of CFTR. Bronchial epithelial barrier breakdown was time-dependent and morphotype-specific and mimicked by acute administration of gliotoxin. Our study also suggests a protective role for CFTR by turning on CFTR-dependent chloride transport in response to gliotoxin, a mechanism that will support mucociliary clearance, and could delay the loss of epithelial integrity during fungal development in vivo

Developmental regulation of DUOX1 expression and function in human fetal lung epithelial cells.

The purpose of this study was to determine the expression and cellular functions of the epithelial NADPH oxidase DUOX1 during alveolar type II cell development. When human fetal lung cells (gestational age 11-22 wk) were cultured to confluency on permeable filters, exposure of cells to a hormone mixture (dexamethasone, 8-Br-cAMP, and IBMX, together referred to as DCI) resulted in differentiation of cells into a mature type II phenotype as assessed by expression of lamellar bodies, surfactant proteins, and transepithelial electrical parameters. After 6 days in culture in presence of DCI, transepithelial resistance (2,616 +/- 529 Omega.cm(2)) and potential (-8.5 +/- 0.6 mV) indicated epithelial polarization. At the same time, treatment with DCI significantly increased the mRNA expression of DUOX1 ( approximately 21-fold), its maturation factor DUOXA1 ( approximately 12-fold), as well as DUOX protein ( approximately 12-fold), which was localized near the apical cell pole in confluent cultures. For comparison, in fetal lung specimens, DUOX protein was not detectable at up to 27 wk of gestational age but was strongly upregulated after 32 wk. Function of DUOX1 was assessed by measuring H(2)O(2) and acid production. Rates of H(2)O(2) production were increased by DCI treatment and blocked by small interfering RNA directed against DUOX1 or by diphenylene iodonium. DCI-treated cultures also showed increased intracellular acid production and acid release into the mucosal medium, and acid production was largely blocked by knockdown of DUOX1 mRNA. These data establish the regulated expression of DUOX1 during alveolar maturation, and indicate DUOX1 in alveolar H(2)O(2) and acid secretion by differentiated type II cells.Journal ArticleResearch Support, N.I.H. ExtramuralResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe