BDNF as a potential mediator between childhood BPA exposure and behavioral function in adolescent boys from the INMA-Granada cohort

This research would not have been achieved without the selfless col-laboration of the INMA-Granada boys and families who took part in the study. Vicente Mustieles, Alicia Olivas-Martinez and Shereen Cynthia D'Cruz were under contract within the HBM4EU project. Additionally, we acknowledge the Biomedical Research Networking Center-CIBER de Epidemiologia y Salud Publica (CIBERESP) , and the Instituto de Salud Carlos III (ISCIII) (FIS-PI16/01820, FIS-PI16/01858, FIS-PI17/01526, and FIS-PI20/01568) . The authors also thank the ISCIII and "Fondo Europeo de Desarrollo Regional" (ISCIII/FEDER) for the Miguel Servet Type I Program granted to C. Freire (grant no. MS16/00085) , the Sara Borrell postdoctoral research contract granted to F. Vela-Soria (grant no. CD17/00212) , and the Spanish Ministry of Education for the predoctoral fellowships (FPU) granted to A. Rodriguez-Carrillo (FPU 16/03011) and to I. Reina-Perez (FPU 17/01848) . Dr. JP Arrebola is under contract within the Ramon y Cajal Program (RYC-2016-20155, from Ministerio de Economia, Industria y Competitividad, Spain) . The authors also ac-knowledge the contribution of the Pediatric Unit of San Cecilio University Hospital of Granada (recruitment and clinical evaluation) , Marina Molina (field work and biospecimen processing) , Raquel Quesada and Beatriz Suarez (chemical exposure data) and Mario Murcia (data curation) , as well as the Human Genotyping Laboratory at the Spanish National Cancer Research Centre, CeGen-PRB3, which is sup-ported by grant no. PT17/0019, of the PE I + D + i 2013-2016, funded by Instituto de Salud Carlos III (ISCIII) and ERDF. This article will be part of the doctoral thesis developed by Andrea Rodriguez-Carrillo in the context of the "Clinical Medicine and Public Health Program" of the University of Granada (Spain) .
This study was supported in part by the European Union's Horizon 2020 research and innovation program HBM4EU [Grant Agreement No. 733032], Biomedical Research Networking Center-CIBER de Epidemiología y Salud Pública (CIBERESP), and the Instituto de Salud Carlos III (ISCIII) [Grant no. CP16/00085 and FIS-PI17/01526]. The funders had no role in the study design, data collection or analysis, decision to publish, or preparation of the manuscript. Funding for open access charge: Universidad de Granada / CBUA.
Background: Bisphenol A (BPA) exposure has been linked to altered behavior in children. Within the European Human Biomonitoring Initiative (HBM4EU), an adverse outcome pathway (AOP) network was constructed supporting the mechanistic link between BPA exposure and brain-derived neurotrophic factor (BDNF). Objective: To test this toxicologically-based hypothesis in the prospective INMA-Granada birth cohort (Spain). Methods: BPA concentrations were quantified by LC-MS/MS in spot urine samples from boys aged 9-11 years, normalized by creatinine and log-2 transformed. At adolescence (15-17 years), blood and urine specimens were collected, and serum and urinary BDNF protein levels were measured using immunoassays. DNA methylation levels at 6 CpGs in Exon IV of the BDNF gene were also assessed in peripheral blood using bisulfite-pyrosequencing. Adolescent's behavior was parent-rated using the Child Behavior Checklist (CBCL/6-18) in 148 boys. Adjusted linear regression and mediation models were fit. Results: Childhood urinary BPA concentrations were longitudinally and positively associated with thought problems (beta = 0.76; 95% CI: 0.02, 1.49) and somatic complaints (beta = 0.80; 95% CI: -0.16, 1.75) at adolescence. BPA concentrations were positively associated with BDNF DNA methylation at CpG6 (beta = 0.21; 95% CI: 0.06, 0.36) and mean CpG methylation (beta = 0.10; 95% CI: 0.01, 0.18), but not with total serum or urinary BDNF protein levels. When independent variables were categorized in tertiles, positive dose-response associations were observed between BPA-thought problems (p-trend = 0.08), BPA-CpG6 (p-trend
Instituto de Salud Carlos III
"Fondo Europeo de Desarrollo Regional" (ISCIII/FEDER) MS16/00085
Sara Borrell postdoctoral research contract grant CD17/00212
Spanish Government FPU 16/03011- FPU 17/01848
Ramon y Cajal Program (Ministerio de Economia, Industria y Competitividad, Spain) RYC-2016-20155
Human Genotyping Laboratory at the Spanish National Cancer Research Centre, CeGen-PRB3 PT17/0019
Instituto de Salud Carlos III European Commission
European Commission