In Utero Alcohol and Tobacco Exposure, Maternal Depression, And Maternal Obesity Are Associated with Impaired Oligodendrocyte Differentiation in The Developing Brain.

Abstract

Introduction: Fetal alcohol spectrum disorder (FASD) is the leading preventable cause of pediatric cognitive disability and is associated with dysmyelination. We examined possible clinical co-determinants that might interact with EtOH in impairing oligodendrocyte (OL) development. Women who drink, including pregnant women, also disproportionately suffer from depression (mDepression), which we have shown is a risk factor for FASD. Might depression during pregnancy contribute to OL pathology? Maternal obesity (mObesity) also inhibits white matter development in fetal brain. Finally, tobacco exposure inhibits not only OL development, but also the production of structural proteins, such as actin. Our human biobank derived from voluntarily terminated pregnancies allows us to study the effect of EtOH and tobacco exposure, mDepression and mObesity on OL markers.

Methods: Fetal brain tissue (10 - 22 weeks) was collected and EtOH exposure estimated, based on a questionnaire adapted from the NIAAA PASS study. EtOH, tobacco, mObesity, mDepression exposed samples were compared with controls matched for gestational age and fetal gender. RNA expressions of OL markers were assayed by ddPCR. Fetal-brain-derived exosomes (FB-E) were isolated from maternal plasma. Exosomal RNA was studied for MBP, BDNF and actin mRNA expression by qRT-PCR and protein levels were confirmed by ELISA.

Results: Forty-two subjects were used in EtOH, mObesity and mDepression studies, 40 cases were used in EtOH and tobacco studies, and 40 cases were used in OL-E (oligodendrocyte-derived exosomes) studies. Six cases were compared to 6 controls. EtOH exposure, mDepression and mObesity were associated with reduced mRNA expression of myelin basic protein (MBP), a marker for mature OLs: ↓ 1.6-fold with EtOH, ↓ 1.5 mObesity, and ↓ 2.2 mDepression. The combination of EtOH and mObesity was associated with strong reductions in MBP expression (↓ 20.6), as was mDepression plus mObesity (↓ 2.6). No significant effects were observed for the early OL marker Nkx2.2 (↓ 1.06). Olig1 was reduced in single (↓ 1.85 EtOH, ↓ 1.8 mObesity) or combined groups: ↓ 5 EtOH and mDepression, ↓ 6.4 EtOH and mObesity, and ↓ 11.6 mDepression and mObesity. We observed reduced Olig2 (↓1.1 EtOH, ↓ 29 mDepression) in all combined groups. EtOH and mDepression, and obesity were associated with much lower levels of BDNF (↓ 1.7 EtOH, ↓ 99). In FB-E studies, 10 cases (EtOH, Tobacco, or EtOH plus Tobacco) were compared to 10 controls: EtOH exposure, Tobacco exposure and EtOH plus Tobacco exposures were associated with reduced MBP: ↓ 1.8-fold by EtOH, ↓ 2.6 EtOH plus Tobacco, ↓ 1.9 Tobacco. EtOH and Tobacco had strong inhibitory effect also on BDNF (↓2.6), as well as on Actin (↓3.9). Cases with high BMI were associated with a stronger effect on MBP downregulation compared to low BMI.

Conclusions: Single Exposures to EtOH or tobacco, mObesity and mDepression all are associated with delayed OL maturation. When these exposures are combined the effects appear to be synergistic. Our unique biobank can be used to determine the mechanism(s) of specific adverse exposures and may suggest novel therapeutic or prophylactic interventions to lessen the severity of FASD.