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Expression of surfactant protein D in airways of asthmatics and interleukin-13 modulation of surfactant protein D in human models of airway epithelium.

Xu J, Singhera GK, Dorscheid DR - Respir. Res. (2015)

Bottom Line: Treatment with IL-13 decreased SP-D expression in both ALI cultures (fraction of epithelium 0.21 ± 0.06 vs. 0.62 ± 0.04, p = 0.0005) and monolayer cultures (protein expression fold change 0.62 ± 0.05) of non-asthmatic AEC; however, IL-13 had no significant effect on SP-D expression in monolayer cultures of asthmatic AEC.Experiments with non-asthmatic monolayer cultures indicate IL-13 exert its effect on SP-D through the IL-13 receptor alpha1 and transcription factor STAT6.SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Surfactant protein D (SP-D), a pattern recognition molecule, has been shown to play roles in host defense such as opsonisation, aggregation of pathogens, and modulation of the inflammatory response. In light of infection-induced exacerbations and damage to the airway epithelium from inflammation, these functions of SP-D make it relevant in the development and pathogenesis of asthma.

Methods: Expression of SP-D was examined in human airway sections and primary airway epithelial cells (AEC) grown in air-liquid interface (ALI) cultures and comparisons were made between those from asthmatic and non-asthmatic donors. ALI cultures of AEC from non-asthmatic donors were examined for SP-D, Mucin 5AC, and cytokeratin-5 expression at different stages of differentiation. Interleukin-13 (IL-13) treatment of airway epithelium and its effect on SP-D expression was studied using ALI and monolayer cultures of primary AEC from non-asthmatic and asthmatic donors.

Results: Airway epithelium of asthmatics, compared to that of non-asthmatics, expressed increased levels of SP-D as demonstrated in airway tissue sections (fraction of epithelium 0.66 ± 0.026 vs. 0.50 ± 0.043, p = 0.004) and ALI cultures (fraction of epithelium 0.50 ± 0.08 vs. 0.25 ± 0.07). SP-D expression decreased as ALI cultures differentiated from 7 days to 21 days (fraction of epithelium 0.62 ± 0.04 to 0.23 ± 0.03, p = 0.004). Treatment with IL-13 decreased SP-D expression in both ALI cultures (fraction of epithelium 0.21 ± 0.06 vs. 0.62 ± 0.04, p = 0.0005) and monolayer cultures (protein expression fold change 0.62 ± 0.05) of non-asthmatic AEC; however, IL-13 had no significant effect on SP-D expression in monolayer cultures of asthmatic AEC. Experiments with non-asthmatic monolayer cultures indicate IL-13 exert its effect on SP-D through the IL-13 receptor alpha1 and transcription factor STAT6.

Conclusions: SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics. This can have implications on the increased susceptibility to infections and altered inflammatory response in asthmatic patients. Future functional studies on the role of SP-D in asthma can provide better insight into defects in the structure and regulation of SP-D.

No MeSH data available.


Related in: MedlinePlus

Surfactant protein D (SP-D) expression in non-asthmatic ALI cultures treated with IL-13. SP-D expression was examined in IL-13-treated (10 ng/ml, 14-day duration) ALI sections grown from matched non-asthmatic donors via immunohistochemistry, where pink was indicative of positivity [A]. Fraction of total epithelial area positive was quantified using colour segmentation in ImagePro Plus. Expression of SP-D in the airway epithelia decreased significantly in the cultures treated with IL-13 (n = 4, t-test p = 0.0005) [B]. SP-D protein expression in ALI cultures treated with IL-13 for 24 hours, 7 days, and 14 days were detected by Western blotting, quantified by densitometry, and normalized to untreated control to obtain fold changes. All three durations resulted in reductions of SP-D expression (n = 6, one-way ANOVA p = 0.02) [C].
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Fig4: Surfactant protein D (SP-D) expression in non-asthmatic ALI cultures treated with IL-13. SP-D expression was examined in IL-13-treated (10 ng/ml, 14-day duration) ALI sections grown from matched non-asthmatic donors via immunohistochemistry, where pink was indicative of positivity [A]. Fraction of total epithelial area positive was quantified using colour segmentation in ImagePro Plus. Expression of SP-D in the airway epithelia decreased significantly in the cultures treated with IL-13 (n = 4, t-test p = 0.0005) [B]. SP-D protein expression in ALI cultures treated with IL-13 for 24 hours, 7 days, and 14 days were detected by Western blotting, quantified by densitometry, and normalized to untreated control to obtain fold changes. All three durations resulted in reductions of SP-D expression (n = 6, one-way ANOVA p = 0.02) [C].

Mentions: Two-week IL-13 treatment of ALI cultures grown from non-asthmatic AEC induced characteristic changes including altered epithelial thickness and cell type distribution (Figure 4A). With respect to SP-D expression, IL-13 induced a significant reduction in the fraction of epithelium that stained positive for SP-D (0.21 ± 0.06) compared to untreated (0.62 ± 0.04) as shown by immunohistochemistry (n = 4, p = 0.0005, Figure 4B). In a time-course experiment, IL-13 treatment of ALI cultures resulted in a fold reduction in SP-D protein expression relative to untreated cultures as demonstrated by Western blotting (0.65 ± 0.15 at 24 hours, 0.47 ± 0.10 at 7 days, 0.32 ± 0.06 at 14 days; n = 4-6, Figure 4C). A significant reduction was also found in SP-D protein expression at day 14 compared to day 7 (p < 0.05). Due to concurrent changes in cell growth, cell type, and epithelial structure, it is unclear whether this reduction is a direct effect of IL-13 or an indirect consequence of IL-13-induced changes in differentiation.Figure 4


Expression of surfactant protein D in airways of asthmatics and interleukin-13 modulation of surfactant protein D in human models of airway epithelium.

Xu J, Singhera GK, Dorscheid DR - Respir. Res. (2015)

Surfactant protein D (SP-D) expression in non-asthmatic ALI cultures treated with IL-13. SP-D expression was examined in IL-13-treated (10 ng/ml, 14-day duration) ALI sections grown from matched non-asthmatic donors via immunohistochemistry, where pink was indicative of positivity [A]. Fraction of total epithelial area positive was quantified using colour segmentation in ImagePro Plus. Expression of SP-D in the airway epithelia decreased significantly in the cultures treated with IL-13 (n = 4, t-test p = 0.0005) [B]. SP-D protein expression in ALI cultures treated with IL-13 for 24 hours, 7 days, and 14 days were detected by Western blotting, quantified by densitometry, and normalized to untreated control to obtain fold changes. All three durations resulted in reductions of SP-D expression (n = 6, one-way ANOVA p = 0.02) [C].
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4352233&req=5

Fig4: Surfactant protein D (SP-D) expression in non-asthmatic ALI cultures treated with IL-13. SP-D expression was examined in IL-13-treated (10 ng/ml, 14-day duration) ALI sections grown from matched non-asthmatic donors via immunohistochemistry, where pink was indicative of positivity [A]. Fraction of total epithelial area positive was quantified using colour segmentation in ImagePro Plus. Expression of SP-D in the airway epithelia decreased significantly in the cultures treated with IL-13 (n = 4, t-test p = 0.0005) [B]. SP-D protein expression in ALI cultures treated with IL-13 for 24 hours, 7 days, and 14 days were detected by Western blotting, quantified by densitometry, and normalized to untreated control to obtain fold changes. All three durations resulted in reductions of SP-D expression (n = 6, one-way ANOVA p = 0.02) [C].
Mentions: Two-week IL-13 treatment of ALI cultures grown from non-asthmatic AEC induced characteristic changes including altered epithelial thickness and cell type distribution (Figure 4A). With respect to SP-D expression, IL-13 induced a significant reduction in the fraction of epithelium that stained positive for SP-D (0.21 ± 0.06) compared to untreated (0.62 ± 0.04) as shown by immunohistochemistry (n = 4, p = 0.0005, Figure 4B). In a time-course experiment, IL-13 treatment of ALI cultures resulted in a fold reduction in SP-D protein expression relative to untreated cultures as demonstrated by Western blotting (0.65 ± 0.15 at 24 hours, 0.47 ± 0.10 at 7 days, 0.32 ± 0.06 at 14 days; n = 4-6, Figure 4C). A significant reduction was also found in SP-D protein expression at day 14 compared to day 7 (p < 0.05). Due to concurrent changes in cell growth, cell type, and epithelial structure, it is unclear whether this reduction is a direct effect of IL-13 or an indirect consequence of IL-13-induced changes in differentiation.Figure 4

Bottom Line: Treatment with IL-13 decreased SP-D expression in both ALI cultures (fraction of epithelium 0.21 ± 0.06 vs. 0.62 ± 0.04, p = 0.0005) and monolayer cultures (protein expression fold change 0.62 ± 0.05) of non-asthmatic AEC; however, IL-13 had no significant effect on SP-D expression in monolayer cultures of asthmatic AEC.Experiments with non-asthmatic monolayer cultures indicate IL-13 exert its effect on SP-D through the IL-13 receptor alpha1 and transcription factor STAT6.SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Surfactant protein D (SP-D), a pattern recognition molecule, has been shown to play roles in host defense such as opsonisation, aggregation of pathogens, and modulation of the inflammatory response. In light of infection-induced exacerbations and damage to the airway epithelium from inflammation, these functions of SP-D make it relevant in the development and pathogenesis of asthma.

Methods: Expression of SP-D was examined in human airway sections and primary airway epithelial cells (AEC) grown in air-liquid interface (ALI) cultures and comparisons were made between those from asthmatic and non-asthmatic donors. ALI cultures of AEC from non-asthmatic donors were examined for SP-D, Mucin 5AC, and cytokeratin-5 expression at different stages of differentiation. Interleukin-13 (IL-13) treatment of airway epithelium and its effect on SP-D expression was studied using ALI and monolayer cultures of primary AEC from non-asthmatic and asthmatic donors.

Results: Airway epithelium of asthmatics, compared to that of non-asthmatics, expressed increased levels of SP-D as demonstrated in airway tissue sections (fraction of epithelium 0.66 ± 0.026 vs. 0.50 ± 0.043, p = 0.004) and ALI cultures (fraction of epithelium 0.50 ± 0.08 vs. 0.25 ± 0.07). SP-D expression decreased as ALI cultures differentiated from 7 days to 21 days (fraction of epithelium 0.62 ± 0.04 to 0.23 ± 0.03, p = 0.004). Treatment with IL-13 decreased SP-D expression in both ALI cultures (fraction of epithelium 0.21 ± 0.06 vs. 0.62 ± 0.04, p = 0.0005) and monolayer cultures (protein expression fold change 0.62 ± 0.05) of non-asthmatic AEC; however, IL-13 had no significant effect on SP-D expression in monolayer cultures of asthmatic AEC. Experiments with non-asthmatic monolayer cultures indicate IL-13 exert its effect on SP-D through the IL-13 receptor alpha1 and transcription factor STAT6.

Conclusions: SP-D is expressed differently in airways of asthmatics relative to that of non-asthmatics. This can have implications on the increased susceptibility to infections and altered inflammatory response in asthmatic patients. Future functional studies on the role of SP-D in asthma can provide better insight into defects in the structure and regulation of SP-D.

No MeSH data available.


Related in: MedlinePlus