Inhibitory effect of heparin-derived oligosaccharides on secretion of interleukin-4 and interleukin-5 from human peripheral blood T lymphocytes

AIM: To investigate the inhibitory effect of heparin-derived oligosaccharides (Oligs) on secretion of interleukin-4 (IL-4) and interleukin-5 (IL-5) from human peripheral blood T lymphocytes (PBTLs).METHODS: Oligs were prepared by three different heparin depolymerization methods and separated by gel filtration chromatography. PBTLs from ten adult patients with allergic eosinophilic gastroenteritis were treated with phytahematoagglutinin (PHA) and Oligs. The supernatants from the cell culture of PBTLs were harvested and subjected to the determination of IL-4 and IL-5 contents by ELISA method.RESULTS: At the concentration of 5μg/mL, Oligs with different Mr had different effects on the secretion of IL-4 and IL-5. The tetrasaccharide with Mr of 1 142, produced by depolymerizing heparin with hydrogen peroxide, had the strongest inhibitory effect on the secretion of IL-4. It decreased the IL-4 content from 375.6±39.2 ng/L (PHA group) to 12.5±5.7 ng/L (P<0.01). The hexasaccharide with Mr of I 806, produced by depolymerizing heparin with βelimination method, had the strongest inhibitory effect on the secretion of IL-5. It decreased the IL-5 content from 289.2±33.4 ng/L (PHA group) to 22.0±5.2 ng/L (P<0.01).CONCLUSION: The inhibitory activity of Oligs on the secretion of IL-4 and IL-5 from human PBTLs closely depends on their molecular structure, and there may be an essential structure to act as an inhibitor. The most effective inhibitors of IL-4 and IL-5 secretion are tetrasaccharides and hexasaccharides, respectively.

Coactivator CBP/p300 increased the activity of C/EBP-mediated human interleukin-5 gene promoter

Interleukin-5 (IL-5),expressed primarily by type-2 T heler (Th2) cell,plays an essential role in the devel-opment of allergic diseases, such as allergic asthma. Histone acetyltransferase CBP/p300 remodels chromatin by acety-lating histones, resulting in open structure of chromatin and active transcription. Adenovirus protein E1A inhibits the activity of CBP/p300. In this study,we analysed the effects of E1A on IL-5 gene promoter/luciferase reporter activity. The results showed that E1A protein inhibited the activity of PMA/ionomycin-stimulated IL-5 gene promoter/luiferase reporter construct. In contrast, overexpression of the CBP/p300-binding defective E1A △2-36 protein did not inhibit IL-5 gene promoter activity. These data demonstrated for the first time that transcriptional coactivator CBP/p300 was involved in the activation of IL-5 gene promoter. E1A protein can modulate CBP/p300 function to activate the transcription of IL-5 gene promoter/luciferase reporter plasmid. Furthermore, in collaboration with transcription factor C/EBP, CBP/p300 activated IL-5 gene pro-moter/luciferase reporter expression. This study provides further insight into the mechanisms of transcriptional regu-lation of IL-5 gene.