Allergen-induced resistin-like molecule- promotes esophageal epithelial cell hyperplasia in eosinophilic esophagitis

Eosinophils Restrict Diesel Exhaust Particles Induced Cell Proliferation of Lung Epithelial A549 Cells, Vial Interleukin-13 Mediated Mechanisms: Implications for Tissue Remodelling And Fibrosis

BACKGROUND

Diesel exhaust particulates (DEPs) affect lung physiology and cause serious damage to the lungs. A number of studies demonstrated that, eosinophils play a very important role in the development of tissue remodelling and fibrosis of lungs. However, the exact mechanism of pathogenesis of tissue remodelling and fibrosis is not known.

METHODS

Both in vitro and in vivo models were used in the study. HL-60 and A549 cells were used in the study. Balb/C mice of 8 to 12 weeks old were used for in vivo study. Cell viability by MTT assay, RNA isolation by tri reagent was accomplished. mRNA expression of inflammatory genes were accomplished by real time PCR or qPCR. Immunohistochemistry was done to asses the localization and expressions of proteins. One way ANOVA followed by post hoc test were done for the statistical analysis. Graph-Pad Prism software was used for statistical analysis.

RESULTS

We for the first time demonstrate that, Interleukin-13 plays a very important role in the development of tissue remodelling and fibrosis. We report that, diesel exhaust particles significantly induce eosinophils cell proliferation and interleukin-13 release in in vitro culture conditions. Supernatant collected from DEP-induced eosinophils cells significantly restrict cell proliferation of epithelial cells in response to exposure of diesel exhast particles. Furthermore, purified interleukin-13 decreases the proliferation of A549 cells, highliting the involvement of IL-13 in tissue remodeling. Notably, Etoricoxib (selective COX-2 inhibitor) did not inhibit DEP-triggered release of interleukin-13, suggesting another cell signalling pathway. The in vivo exposer of DEP to the lungs of mice, resulted in high level of eosinophils degranulation as depicted by the EPX-1 immunostaining and altered level of mRNA expressions of inflammatory genes. We also found that, a-SMA, fibroblast specific protein (FSP-1) has been changed in response to DEP in the mice lungs along with the mediators of inflammation.

CONCLUSION

Altogether, we elucidated, the mechanistic role of eosinophils and IL-13 in the DEP-triggered proliferation of lungs cells thus providing an inside in the pathophysiology of tissue remodelling and fibrosis of lungs.

Significance of Interleukin (IL)-15 in IgE associated eosinophilic Esophagitis (EoE)

BACKGROUND AND AIM

IgE-mediated immune responses contribute to the pathogenesis of eosinophilic esophagitis (EoE). Interleukin (IL)-4 is a well-established cytokine involved in B cell activation, immunoglobulin (Ig) E production and isotype class switching. Earlier reports indicated that IL-15, B cells and IgE are induced in EoE pathogenesis. Therefore, we hypothesized that induced IL-15 and IgE may have a significant correlation in promoting EoE pathogenesis.

METHODS

Accordingly, we performed ELISA, qPCR, flowcytometric and immunostaining analyses to examine IgE, B cells, eosinophils and mast cells in the esophagus of IL-15 overexpressed mice following EoE induction.

RESULTS

Herein, we show that IL-15 overexpressed mice indeed have induced baseline IL-4, B cells, eosinophils, mast cells and IgE levels in the blood and esophagus. Further, we observed that IL-15 overexpressed mice show induction of IgE, and accumulation of degranulated eosinophils and mast cells in allergen-induced experimental EoE. Notably, despite induced blood IgE, esophageal eosinophilia is not induced in intestinal fatty acid binding protein IL-15 overexpressed gene (Fabpi-IL-15) mice. Fabpi-IL-15 transgenic mice showed IgE in the blood and intestine and intestinal eosinophilia, but no esophageal eosinophilia at baseline and comparable eosinophils in the esophagus of saline and allergen challenged Fabpi-IL-15 mice. Similarly, allergen challenged IL-15 gene-deficient mice show reduced IgE and esophageal eosinophilia in allergen-induced experimental EoE.

CONCLUSIONS

Taken together, we for the first time provide direct evidence that tissue-specific IL-15 induced IgE mediated responses, not systemic IgE is critical in promoting EoE pathogenesis.