Di-(2-ethylhexyl) phthalate aggravates fine particulate matter-induced asthma in weanling mice due to T follicular helper cell-dependent response

• Published in: Toxicology (Amsterdam) 2023-01, Vol.484, p.153406, Article 153406
• Main Authors: Han, Yu, Yu, Xiangjun, Lu, Ying, Shen, Yi, Wang, Xiaoying, Wei, Haiyan, Ni, Kaihua, Qu, Jianhua, Chen, Gang
• Format: Article
• Language: English
• Subjects: Adjuvants, Immunologic - pharmacology; Allergens - toxicity; Allergic asthma; Animals; Asthma - chemically induced; Asthma - metabolism; Cytokine secretion; Di-(2-ethylhexyl) phthalate (DEHP); Diethylhexyl Phthalate - toxicity; Differentiation regulation; Female; Fine particulate matter; Immunoglobulin E; Interleukin-13 - metabolism; Interleukin-13 - toxicity; Interleukin-4 - metabolism; Interleukin-4 - pharmacology; Male; Mice; Mice, Inbred C57BL; Particulate Matter - toxicity; T follicular helper cell (Tfh); T Follicular Helper Cells - metabolism; T-Lymphocytes, Helper-Inducer
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/j.tox.2022.153406

Environmental pollutants fine particulate matter and di-(2-ethylhexyl) phthalate (DEHP) are believed to be the risk factors for childhood asthma. Allergic asthma is basically an immediate hypersensitivity mediated by IgE, the product of humoral immune response. T follicular helper cells (Tfh) have been newly identified as the crucial T helper cells for supporting B cells to produce immunoglobulins in humoral immunity. Tfh cells are therefore potentially to serve as the diagnostic marker and therapeutic target of immune diseases. In this study, we examined the joint effects of fine particulate matter and DEHP on the initiation and progression of asthma and explored the fundamental role of Tfh cells during the process. Weanling C57BL/6 mice (both sexes) were concurrently exposed to DEHP (intragastric administration at 300 μg/kg) and fine atmospheric particulate matter (mean particle diameter < 4 µm, PM4) (oropharyngeal instillation at 2 mg/kg) once every three days for 30 days (10 times). We found that DEHP displayed adjuvant effects to potentiate PM4 allergen-induced expansion of Tfh and plasma cells, production of serum IgE and IgG1, and occurrence of airway hyper-responsiveness and inflammation. Then PM4 and DEHP co-exposure was performed to Cd4 knock-out mice reconstituted with normal wild-type adoptive Tfh cells or non-Tfh cells. The results of immune adoptive transfusion indicated that the joint immunotoxic effects of PM4 and DEHP were dependent on Tfh cells. We further proved that DEHP could adjuvantly boost PM4-induced expression of BCL-6 and c-MAF and secretion of IL-13 and IL-4 in Tfh cells. In conclusion, these data suggest that DEHP metabolites act in an adjuvant-like manner to aggravate PM4 allergen-induced asthma based on anaphylactic IgE response, resulting from excessive IL-13 and IL-4 synthesized by abnormally differentiated Tfh cells. [Display omitted] •DEHP acts in an adjuvant-like manner to aggravate PM4 allergen-induced asthma.•DEHP acts as an adjuvant to enhance PM4 allergen-induced humoral immune response.•The joint immunotoxic effects of DEHP and PM4 are dependent on Tfh cells.•DEHP has potentiation effects to promote PM4-induced BCL-6 and c-MAF expression.•DEHP has potentiation effects to aggrandize PM4-induced IL-13 and IL-4 synthesis.