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Adenovirus entry from the apical surface of polarized epithelia is facilitated by the host innate immune response.

Kotha PL, Sharma P, Kolawole AO, Yan R, Alghamri MS, Brockman TL, Gomez-Cambronero J, Excoffon KJ - PLoS Pathog. (2015)

Bottom Line: Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection.We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity.In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection.

View Article: PubMed Central - PubMed

Affiliation: Departments of Biological Sciences, Wright State University, Dayton, Ohio, United States of America.

ABSTRACT
Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection. The primary receptor for most adenoviruses is the coxsackievirus and adenovirus receptor (CAR), a cell-cell adhesion protein normally localized at the basolateral surface of polarized epithelia and involved in neutrophil transepithelial migration. Recently, an alternate isoform of CAR, CAREx8, has been identified at the apical surface of polarized airway epithelia and is implicated in viral infection from the apical surface. We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity. We show that IL-8, a proinflammatory cytokine and a neutrophil chemoattractant, stimulates the protein expression and apical localization of CAREx8 via activation of AKT/S6K and inhibition of GSK3β. Apical CAREx8 tethers infiltrating neutrophils at the apical surface of a polarized epithelium. Moreover, neutrophils present on the apical-epithelial surface enhance adenovirus entry into the epithelium. These findings suggest that adenovirus evolved to co-opt an innate immune response pathway that stimulates the expression of its primary receptor, apical CAREx8, to allow the initial infection the intact epithelium. In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection.

No MeSH data available.


Related in: MedlinePlus

Apical CAREx8 protein expression increases apical adhesion of infiltrating neutrophils.Neutrophil transmigration assays were performed in the basal-to-apical direction in MDCK stable cells exposed to the neutrophil chemoattractive peptide fMLP on the apical surface. A) % neutrophil adhesion and B) % neutrophil transmigration were quantitated by measuring the fluorescence intensity of fluorescently-labeled neutrophils imaged by fluorescence microscopy. Error bars represent the SEM from three independent experiments; *p < 0.05 or **p < 0.01 by one-way ANOVA.
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ppat.1004696.g004: Apical CAREx8 protein expression increases apical adhesion of infiltrating neutrophils.Neutrophil transmigration assays were performed in the basal-to-apical direction in MDCK stable cells exposed to the neutrophil chemoattractive peptide fMLP on the apical surface. A) % neutrophil adhesion and B) % neutrophil transmigration were quantitated by measuring the fluorescence intensity of fluorescently-labeled neutrophils imaged by fluorescence microscopy. Error bars represent the SEM from three independent experiments; *p < 0.05 or **p < 0.01 by one-way ANOVA.

Mentions: Next, we sought to determine the fate of neutrophils that transmigrate from the physiologically relevant basal surface to the apical surface in the presence or absence of DOX-induced CAREx8. To do this, fluorescently-labeled neutrophils were added to the basal surface of epithelia and stimulated to transmigrate to the apical surface by adding the neutrophil chemoattractive bacterial peptide fMLP to the apical surface. Two populations of cells were quantified: 1) neutrophils that transmigrated through but remained adhered to the apical epithelial surface and 2) neutrophils that completely transmigrated through and detached from the epithelium (Fig. 4A, B respectively). DOX-induced MDCK-CAREx8 epithelia retained ∼3 times as many transmigrated neutrophils on the apical surface as compared to uninduced MDCK-CAREx8 epithelia, and MDCK-CAREx7, or-mCherry epithelia regardless of DOX-induction or not (Fig. 4A). In contrast, ∼3 times as many neutrophils transmigrated through induced MDCK-CAREx7 epithelia relative to all other conditions (Fig. 4B). This is consistent with the known role for basolateral CAREx7 in facilitating neutrophil transepithelial migration [19]. These data confirm that CAREx8 is able to enhance the adhesion of transmigrating neutrophils at the apical surface and also indicate that each CAR isoform plays a distinct role in neutrophil recruitment.


Adenovirus entry from the apical surface of polarized epithelia is facilitated by the host innate immune response.

Kotha PL, Sharma P, Kolawole AO, Yan R, Alghamri MS, Brockman TL, Gomez-Cambronero J, Excoffon KJ - PLoS Pathog. (2015)

Apical CAREx8 protein expression increases apical adhesion of infiltrating neutrophils.Neutrophil transmigration assays were performed in the basal-to-apical direction in MDCK stable cells exposed to the neutrophil chemoattractive peptide fMLP on the apical surface. A) % neutrophil adhesion and B) % neutrophil transmigration were quantitated by measuring the fluorescence intensity of fluorescently-labeled neutrophils imaged by fluorescence microscopy. Error bars represent the SEM from three independent experiments; *p < 0.05 or **p < 0.01 by one-way ANOVA.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4358923&req=5

ppat.1004696.g004: Apical CAREx8 protein expression increases apical adhesion of infiltrating neutrophils.Neutrophil transmigration assays were performed in the basal-to-apical direction in MDCK stable cells exposed to the neutrophil chemoattractive peptide fMLP on the apical surface. A) % neutrophil adhesion and B) % neutrophil transmigration were quantitated by measuring the fluorescence intensity of fluorescently-labeled neutrophils imaged by fluorescence microscopy. Error bars represent the SEM from three independent experiments; *p < 0.05 or **p < 0.01 by one-way ANOVA.
Mentions: Next, we sought to determine the fate of neutrophils that transmigrate from the physiologically relevant basal surface to the apical surface in the presence or absence of DOX-induced CAREx8. To do this, fluorescently-labeled neutrophils were added to the basal surface of epithelia and stimulated to transmigrate to the apical surface by adding the neutrophil chemoattractive bacterial peptide fMLP to the apical surface. Two populations of cells were quantified: 1) neutrophils that transmigrated through but remained adhered to the apical epithelial surface and 2) neutrophils that completely transmigrated through and detached from the epithelium (Fig. 4A, B respectively). DOX-induced MDCK-CAREx8 epithelia retained ∼3 times as many transmigrated neutrophils on the apical surface as compared to uninduced MDCK-CAREx8 epithelia, and MDCK-CAREx7, or-mCherry epithelia regardless of DOX-induction or not (Fig. 4A). In contrast, ∼3 times as many neutrophils transmigrated through induced MDCK-CAREx7 epithelia relative to all other conditions (Fig. 4B). This is consistent with the known role for basolateral CAREx7 in facilitating neutrophil transepithelial migration [19]. These data confirm that CAREx8 is able to enhance the adhesion of transmigrating neutrophils at the apical surface and also indicate that each CAR isoform plays a distinct role in neutrophil recruitment.

Bottom Line: Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection.We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity.In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection.

View Article: PubMed Central - PubMed

Affiliation: Departments of Biological Sciences, Wright State University, Dayton, Ohio, United States of America.

ABSTRACT
Prevention of viral-induced respiratory disease begins with an understanding of the factors that increase or decrease susceptibility to viral infection. The primary receptor for most adenoviruses is the coxsackievirus and adenovirus receptor (CAR), a cell-cell adhesion protein normally localized at the basolateral surface of polarized epithelia and involved in neutrophil transepithelial migration. Recently, an alternate isoform of CAR, CAREx8, has been identified at the apical surface of polarized airway epithelia and is implicated in viral infection from the apical surface. We hypothesized that the endogenous role of CAREx8 may be to facilitate host innate immunity. We show that IL-8, a proinflammatory cytokine and a neutrophil chemoattractant, stimulates the protein expression and apical localization of CAREx8 via activation of AKT/S6K and inhibition of GSK3β. Apical CAREx8 tethers infiltrating neutrophils at the apical surface of a polarized epithelium. Moreover, neutrophils present on the apical-epithelial surface enhance adenovirus entry into the epithelium. These findings suggest that adenovirus evolved to co-opt an innate immune response pathway that stimulates the expression of its primary receptor, apical CAREx8, to allow the initial infection the intact epithelium. In addition, CAREx8 is a new target for the development of novel therapeutics for both respiratory inflammatory disease and adenoviral infection.

No MeSH data available.


Related in: MedlinePlus