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Allergen-induced interleukin-18 promotes experimental eosinophilic oesophagitis in mice.

Dutt P, Shukla JS, Ventateshaiah SU, Mariswamy SJ, Mattner J, Shukla A, Mishra A - Immunol. Cell Biol. (2015)

Bottom Line: Elevated levels of interleukin (IL)-18 have been reported in a number of allergic diseases.We recently reported that IL-18 in the blood and IL-18Rα mRNA in the oesophagus are induced during human eosinophilic oesophagitis (EoE).Intranasal delivery of rIL-18 induced both mast cells and eosinophilic inflammation in the oesophagus in a time- and dose-dependent manner.

View Article: PubMed Central - PubMed

Affiliation: Section of Department of Medicine, Pulmonary Diseases, Tulane Eosinophilic Disorder Center, Tulane University School of Medicine, New Orleans, LA, USA.

ABSTRACT
Elevated levels of interleukin (IL)-18 have been reported in a number of allergic diseases. We recently reported that IL-18 in the blood and IL-18Rα mRNA in the oesophagus are induced during human eosinophilic oesophagitis (EoE). Additionally, we earlier showed that invariant natural killer T (iNKT) cells are critical to EoE pathogenesis; however, the mechanism of iNKT cell activation in EoE is not well understood. Therefore, the current study focused on the hypothesis that allergen-induced IL-18 may have an important role in iNKT cell-mediated EoE pathogenesis. We first validated the human EoE findings of IL-18 in experimental EoE by examining blood levels of IL-18 and oesophageal IL-18Rα mRNA levels in aeroallergen- and food allergen-induced experimental mouse models of EoE. We demonstrate that blood IL-18 protein and oesophageal IL-18Rα mRNA are induced in the mouse model of EoE and that IL-18Rα is expressed by iNKT cells in the oesophagus. Intranasal delivery of rIL-18 induced both mast cells and eosinophilic inflammation in the oesophagus in a time- and dose-dependent manner. To establish the significance of IL-18 in EoE pathogenesis, we examined DOX-inducible rtTA-CC10-IL-18 bitransgenic mice that induce IL-18 protein expression in the oesophagus. Our analysis indicated that induction of IL-18 in these mice resulted in the development of many of the characteristics of EoE, including oesophageal intraepithelial eosinophilia, increased mast cells, oesophageal remodelling and fibrosis. The current study provides evidence that IL-18 may induce iNKT cell activation to release the eosinophil-activating cytokine IL-5, as IL-5-deficient mice and iNKT cell-deficient (CD1d ) mice do not induce EoE in response to intranasal IL-18 challenge. Taken together, these findings provide evidence that allergen-induced IL-18 has a significant role in promoting IL-5- and iNKT-dependent EoE pathogenesis.

No MeSH data available.


Related in: MedlinePlus

IL-18 transgene overexpression promotes EoE in micertTA-CC10-IL-18 bitransgenic mice were exposed to DOX food or normal food (No DOX) and oesophageal IL-18 mRNA expression (A) and IL-18 protein (B) levels were quantitative by RT-PCR and ELISA analysis, respectively. Anti-MBP immunostained esophageal eosinophilia in the lamina propria as will as in the epithelial mucosa (C-F). Intraepithelial eosinophils were detected in the oesophageal of DOX exposed tissue sections (E, F). Representative photomicrographs from 12 mice tissue sections are shown in both low (×100) and high (×400) of original magnification. Quantitation of eosinophils in the esophageal section of DOX and No-DOX exposed rtTA-CC10-IL-18 bitransgenic mice (G). The data show the means ± SD pooled from 3 experiments, (4-mice/group/treatment/experiments; total mice=12/group), p<0.001. EP, Epithelium; LP, Lamina propria; MS, Muscularis Mucosa; LU, Lumen.
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Figure 3: IL-18 transgene overexpression promotes EoE in micertTA-CC10-IL-18 bitransgenic mice were exposed to DOX food or normal food (No DOX) and oesophageal IL-18 mRNA expression (A) and IL-18 protein (B) levels were quantitative by RT-PCR and ELISA analysis, respectively. Anti-MBP immunostained esophageal eosinophilia in the lamina propria as will as in the epithelial mucosa (C-F). Intraepithelial eosinophils were detected in the oesophageal of DOX exposed tissue sections (E, F). Representative photomicrographs from 12 mice tissue sections are shown in both low (×100) and high (×400) of original magnification. Quantitation of eosinophils in the esophageal section of DOX and No-DOX exposed rtTA-CC10-IL-18 bitransgenic mice (G). The data show the means ± SD pooled from 3 experiments, (4-mice/group/treatment/experiments; total mice=12/group), p<0.001. EP, Epithelium; LP, Lamina propria; MS, Muscularis Mucosa; LU, Lumen.

Mentions: To validate that IL-18 overexpression induces eosinophils and mast cells in the oesophagus, we obtained DOX-inducible rtTA-CC10-IL-18 bitransgenic mice from Dr Jack Elias, MD, PhD, Yale University. The DOX-inducible IL-18 transgenic mice showed no significant increase in IL-18 mRNA; however, significantly increased IL-18 protein levels were observed in the oesophagus compared with the no-DOX mice following 3 weeks of exposure (Figure 3 A, B). Notably, the DOX-inducible IL-18 bitransgenic mice are driven by a lung-specific Clara cell promoter (CC-10). The no-DOX and DOX-exposed IL-18 bitransgenic mice were evaluated for EoE pathogenesis. The DOX-treated mice showed most of the EoE characteristics, including eosinophil accumulation in the lamina propria and epithelial mucosa (intraepithelial eosinophilia) along with extracellular eosinophilic granules in the oesophageal mucosa. The no-DOX mice showed few baseline eosinophils and only in the oesophageal lamina propria (Figure 3 C-F, mice = 12/group). The number of eosinophils in the oesophagus of DOX-exposed IL-18 bitransgenic mice was 72.6 ± 8.3/mm2 compared with 4.2 ± 1.1/mm2 (mean ± SD, mice = 12/group, p<0.001) in no-DOX IL-18 bitransgenic mice (Figure 3 G). Interestingly, the IL-18 bitransgenic mice treated with DOX for 3 weeks also developed mast cell inflammation in the oesophagus. Most of the mast cells in DOX-exposed mice were detected in the lamina propria and some in the muscularis mucosa (Figure 4 B and data not shown). No-DOX bitransgenic mice showed a comparatively low number of baseline mast cells in the oesophageal lamina propria (Figure 4 A). The number of mast cells in the oesophagus of DOX-exposed IL-18 bitransgenic mice was 32.4 ÷ 10.3/mm2 compared with 11.6 ± 3.8/mm2 in no-DOX exposed IL-18 bitransgenic mice (Figure 4 C). The data are expressed as the mean ± SD, mice =12/group).


Allergen-induced interleukin-18 promotes experimental eosinophilic oesophagitis in mice.

Dutt P, Shukla JS, Ventateshaiah SU, Mariswamy SJ, Mattner J, Shukla A, Mishra A - Immunol. Cell Biol. (2015)

IL-18 transgene overexpression promotes EoE in micertTA-CC10-IL-18 bitransgenic mice were exposed to DOX food or normal food (No DOX) and oesophageal IL-18 mRNA expression (A) and IL-18 protein (B) levels were quantitative by RT-PCR and ELISA analysis, respectively. Anti-MBP immunostained esophageal eosinophilia in the lamina propria as will as in the epithelial mucosa (C-F). Intraepithelial eosinophils were detected in the oesophageal of DOX exposed tissue sections (E, F). Representative photomicrographs from 12 mice tissue sections are shown in both low (×100) and high (×400) of original magnification. Quantitation of eosinophils in the esophageal section of DOX and No-DOX exposed rtTA-CC10-IL-18 bitransgenic mice (G). The data show the means ± SD pooled from 3 experiments, (4-mice/group/treatment/experiments; total mice=12/group), p<0.001. EP, Epithelium; LP, Lamina propria; MS, Muscularis Mucosa; LU, Lumen.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4581894&req=5

Figure 3: IL-18 transgene overexpression promotes EoE in micertTA-CC10-IL-18 bitransgenic mice were exposed to DOX food or normal food (No DOX) and oesophageal IL-18 mRNA expression (A) and IL-18 protein (B) levels were quantitative by RT-PCR and ELISA analysis, respectively. Anti-MBP immunostained esophageal eosinophilia in the lamina propria as will as in the epithelial mucosa (C-F). Intraepithelial eosinophils were detected in the oesophageal of DOX exposed tissue sections (E, F). Representative photomicrographs from 12 mice tissue sections are shown in both low (×100) and high (×400) of original magnification. Quantitation of eosinophils in the esophageal section of DOX and No-DOX exposed rtTA-CC10-IL-18 bitransgenic mice (G). The data show the means ± SD pooled from 3 experiments, (4-mice/group/treatment/experiments; total mice=12/group), p<0.001. EP, Epithelium; LP, Lamina propria; MS, Muscularis Mucosa; LU, Lumen.
Mentions: To validate that IL-18 overexpression induces eosinophils and mast cells in the oesophagus, we obtained DOX-inducible rtTA-CC10-IL-18 bitransgenic mice from Dr Jack Elias, MD, PhD, Yale University. The DOX-inducible IL-18 transgenic mice showed no significant increase in IL-18 mRNA; however, significantly increased IL-18 protein levels were observed in the oesophagus compared with the no-DOX mice following 3 weeks of exposure (Figure 3 A, B). Notably, the DOX-inducible IL-18 bitransgenic mice are driven by a lung-specific Clara cell promoter (CC-10). The no-DOX and DOX-exposed IL-18 bitransgenic mice were evaluated for EoE pathogenesis. The DOX-treated mice showed most of the EoE characteristics, including eosinophil accumulation in the lamina propria and epithelial mucosa (intraepithelial eosinophilia) along with extracellular eosinophilic granules in the oesophageal mucosa. The no-DOX mice showed few baseline eosinophils and only in the oesophageal lamina propria (Figure 3 C-F, mice = 12/group). The number of eosinophils in the oesophagus of DOX-exposed IL-18 bitransgenic mice was 72.6 ± 8.3/mm2 compared with 4.2 ± 1.1/mm2 (mean ± SD, mice = 12/group, p<0.001) in no-DOX IL-18 bitransgenic mice (Figure 3 G). Interestingly, the IL-18 bitransgenic mice treated with DOX for 3 weeks also developed mast cell inflammation in the oesophagus. Most of the mast cells in DOX-exposed mice were detected in the lamina propria and some in the muscularis mucosa (Figure 4 B and data not shown). No-DOX bitransgenic mice showed a comparatively low number of baseline mast cells in the oesophageal lamina propria (Figure 4 A). The number of mast cells in the oesophagus of DOX-exposed IL-18 bitransgenic mice was 32.4 ÷ 10.3/mm2 compared with 11.6 ± 3.8/mm2 in no-DOX exposed IL-18 bitransgenic mice (Figure 4 C). The data are expressed as the mean ± SD, mice =12/group).

Bottom Line: Elevated levels of interleukin (IL)-18 have been reported in a number of allergic diseases.We recently reported that IL-18 in the blood and IL-18Rα mRNA in the oesophagus are induced during human eosinophilic oesophagitis (EoE).Intranasal delivery of rIL-18 induced both mast cells and eosinophilic inflammation in the oesophagus in a time- and dose-dependent manner.

View Article: PubMed Central - PubMed

Affiliation: Section of Department of Medicine, Pulmonary Diseases, Tulane Eosinophilic Disorder Center, Tulane University School of Medicine, New Orleans, LA, USA.

ABSTRACT
Elevated levels of interleukin (IL)-18 have been reported in a number of allergic diseases. We recently reported that IL-18 in the blood and IL-18Rα mRNA in the oesophagus are induced during human eosinophilic oesophagitis (EoE). Additionally, we earlier showed that invariant natural killer T (iNKT) cells are critical to EoE pathogenesis; however, the mechanism of iNKT cell activation in EoE is not well understood. Therefore, the current study focused on the hypothesis that allergen-induced IL-18 may have an important role in iNKT cell-mediated EoE pathogenesis. We first validated the human EoE findings of IL-18 in experimental EoE by examining blood levels of IL-18 and oesophageal IL-18Rα mRNA levels in aeroallergen- and food allergen-induced experimental mouse models of EoE. We demonstrate that blood IL-18 protein and oesophageal IL-18Rα mRNA are induced in the mouse model of EoE and that IL-18Rα is expressed by iNKT cells in the oesophagus. Intranasal delivery of rIL-18 induced both mast cells and eosinophilic inflammation in the oesophagus in a time- and dose-dependent manner. To establish the significance of IL-18 in EoE pathogenesis, we examined DOX-inducible rtTA-CC10-IL-18 bitransgenic mice that induce IL-18 protein expression in the oesophagus. Our analysis indicated that induction of IL-18 in these mice resulted in the development of many of the characteristics of EoE, including oesophageal intraepithelial eosinophilia, increased mast cells, oesophageal remodelling and fibrosis. The current study provides evidence that IL-18 may induce iNKT cell activation to release the eosinophil-activating cytokine IL-5, as IL-5-deficient mice and iNKT cell-deficient (CD1d ) mice do not induce EoE in response to intranasal IL-18 challenge. Taken together, these findings provide evidence that allergen-induced IL-18 has a significant role in promoting IL-5- and iNKT-dependent EoE pathogenesis.

No MeSH data available.


Related in: MedlinePlus