Objective: To investigate the effects of exposure to diethyl phthalate(DEHP) during pregnancy and lactation in respiratory allergy of offspring Wistar rats.
Methods: To establish the maternal DEHP exposure model: 36 healthy 2-month-old female Wistar rats were divided into three different dose groups. From GD0, each group of pregnant mice were given different concentrations of DEHP(0, 30, 300 mg/(kg·d)) until to the newborn weaning(PND21). After birth, one of offspring was selected from each cage in different dose groups. At PND21 and PND28 the offspring were sensitized by intraperitoneal injection(i. p. ) OVA and continuous nasal sensitization at PND32, PND33, PND34. Bronchoalveolar lavage fluid(BALF) and lung tissue were collected at PND35 with non-sensitized groups. ELISA detected the secretion of Th2 cytokine interleukin(IL)-4, IL-5 and IL-13 in BALF, and the pathological changes of allergic inflammation in lung tissues were observed by HE and PAS staining. Expression of epithelium-derived factor IL-33 detected by immunohistochemistry.
Results: In BALF, compared with the control group, the total number of inflammatory cells and eosinophils in the DEHP0+OVA group increased to(131. 500±25. 548)×10~4, (32. 000±10. 079)×10~4(P<0. 05); The total number of inflammatory cells and eosinophils in the DEHP30+OVA group increased to(156. 167±17. 994)×10~4, (16. 331±6. 667)×10~4(P<0. 05); and the total number of inflammatory cells and eosinophils in the DEHP300+OVA group increased to(172. 167±19. 994)×10~4, (55. 000±17. 018)×10~4(P<0. 05). After adding different doses of DEHP and OVA, compared with the control group, The expression levels of IL-4, IL-5, IL-13 in DEHP0+OVA group increased to(38. 401±6. 594) pg/mL(P>0. 05), (30. 026±2. 756) pg/mL(P<0. 05), (13. 806±4. 355) pg/mL(P<0. 05); The expression levels of IL-4, IL-5 and IL-13 in DEHP30+OVA group increased to(57. 733±7. 293) pg/mL(P<0. 05) and(31. 544±1. 043) pg/mL(P>0. 05), (18. 068±1. 497) pg/mL(P<0. 05); The expression levels of IL-4, IL-5 and IL-13 in DEHP300+OVA group increased to(54. 943±6. 049) pg/mL(P>0. 05) and(32. 377±3. 739)pg/mL(P>0. 05), (20. 168±0. 939) pg/mL(P<0. 05), respectively. The tissue section of all the DEHP+saline groups could be observed that no obvious allergic inflammatory reaction, meanwhile all the DEHP+OVA groups had a relatively obvious allergic reaction and were severe with the increase of DEHP dose. Immunohistochemistry showed no significant increase in the expression of IL-33 in the DEHP+saline groups, while the expression of IL-33 in the DEHP+OVA groups increased with a certain dose response.
Conclusion: Exposure to DEHP during pregnancy and lactation will aggravate the sensitization reaction of offspring, the possible mechanism that DEHP increase the Th2 type of immune response may be the overexpression of IL-33 in the epithelial cells.
Keywords: IL-33; OVA; Th2 cytokines; diethyl phthalate; pulmonary tissue; sensitization.