Xanthine oxidase mediates the vascular dysfunction with direct and in-utero electronic cigarette exposure

ABSTRACT
The adult prevalence of Electronic cigarettes (Ecigs) is ~5%, with young adults having the highest prevalence,
and 56% of the young adults were never smokers, which includes women of reproductive age. The novelty and
customizability of Ecigs, combined with messaging the Ecigs are ‘safer’ than cigarettes, drives much of the
appeal and interest for youth in using Ecigs. Yet, a growing number of studies are showing that Ecig usage has
negative vascular actions and that these outcomes are not different than smoking traditional cigarettes. Another
area of significant concern relates to maternal vaping during pregnancy. Female smokers are more inclined to
experiment with Ecigs compared to males with 5-16% of women using Ecigs during pregnancy. However,
emerging pre-clinical data shows that perinatal exposure from vaping dams results in adverse health outcomes
in progeny. We have shown that Ecig exposure during this “sensitive” developmental window induces a lasting
impact (into adult life) on the vascular health of offspring. Previous studies have shown that environmental
exposures in animal models and humans adversely affect cognitive function. This has led the NIH to prioritize
studies that examine the basic mechanisms of Ecigs on health outcomes. This proposal leverages our prior work,
which establishes a robust and reliable pre-clinical phenotype, to better understand the dose and potential
molecular mechanisms underpinning vascular dysfunction with direct and in utero Ecig exposures. Xanthine
oxidoreductase (XOR) is a significant source of oxidants (hydrogen peroxide, superoxide) that are implicated in
the pathogenesis of vascular diseases. We have evidence to support that XOR is a key mediator of this vascular
dysfunction with both direct Ecig exposure (F0) and in utero Ecig exposure (the F1 offspring). Our central
hypothesis is that (direct and/or and in-utero) Ecig exposure elevates hepatic XOR, which is released into the
circulation causing cerebrovascular and aortic dysfunction via the direct actions of XOR-oxidants on the
endothelium. As such, Ecig exposure accelerates vascular-associated diseases and cognitive decline (i.e.,
VCID). We have a unique exposure system that measures real-time (puff-by-puff) Ecig dose exposure in a
controlled environment, allowing us to examine high-fidelity dose-related exposure-induced effects on our animal
models. Aim 1a will establish a dose-related Ecig exposure in the development of Ecig-mediated vascular
dysfunction and XOR activity. In Aim 1b, we use our liver (hepatocyte)-and endothelial-specific XOR conditional
KO mouse to manipulate the XOR pathway during direct Ecig exposure (F0 generation) and to examine vascular
and cognitive function. In Aim 2, we will determine the long-term vascular, neurobiological, and behavioral
consequences and role of XOR with in-utero (F1 generation) Ecig exposures. Complementary experiments will
also examine the interaction of VCID, by manipulating the XOR pathway (using febuxostat) and determining if
we can delay the pathological progression of VCID. The studies will fill gaps identified by the NIH regarding the
need for understanding the basic mechanisms of Ecigs on health outcomes.

Grant Number: 1R56ES035719-01A1
NIH Institute/Center: NIH
Principal Investigator: Paul Chantler