In utero nicotine exposure affects lung growth and differentiation by altering specific physiologic molecular signaling pathways that are necessary for fetal lung development, resulting in the offspring's predisposition to childhood asthma. We now have preliminary evidence that these alterations in the structure and function of the lung caused by nicotine exposure during pregnancy can be passed from one generation to the next, i.e., from generation 1 (G1) to G2 and G3, etc. We have previously shown that nicotine alters the normal differentiation of the mesenchymal cells in the developing fetal lung by stimulating the Wnt pathway, causing the myogenic phenotype, consistent with asthma in the offspring. Moreover, we have found that peroxisome proliferator- activated receptor gamma (PPAR?) agonists can inhibit or reverse this effect of nicotine. Armed with this knowledge of nicotine's effect on asthma in G1 offspring, we will now determine its transgenerational effect and whether this effect is determined by nicotine-induced epigenetic changes in the gonads.
In Specific Aim 1 A, we will determine the transgenerational development of asthma in G2 and G3 offspring of G1 rat offspring exposed to nicotine in utero in a gender-specific manner. We will determine if the transgenerational increase in the risk of asthma following in utero nicotine exposure is greater in G2 males than in females.
In Specific Aim 1 B, we will determine whether exposure of G2 offspring to nicotine in utero further exacerbates the transgenerational asthma risk in G3.
In Specific Aim 2, we will elucidate the effects of nicotine on epigenetic mechanisms in the lung and gonads as the putative basis for the transgenerational effect of nicotine on asthma.
In Specific Aim 2 A, we will determine the epigenetic effects of nicotine on the methylation and acetylation of DNA in the G1 offspring lungs and gonads.
In Specific Aim 2 B, we will determine if the PPAR? agonist rosiglitazone will inhibit 1) the epigenetic changes in the lung and gonads, and thus 2) prevent the transgenerational effect of nicotine on asthma. The concept put forward in this proposal is totally novel and innovative, and it addresses the fundamental mechanism (s) explaining the detrimental effects of maternal smoking not only on the exposed offspring, but also on the many generations that follow. Using this comprehensive cell-molecular-epigenetic approach to understand the transgenerational effects of smoking on the prevalence of asthma will lead to effective and targeted interventions and prevention of this disease, which at present is a major public health challenge.
Childhood asthma is a major public health problem worldwide with maternal smoking during pregnancy as a significant contributor to this ever growing epidemic. In addition, there is emerging evidence for transgenerational transmission of asthma risk following exposure to maternal smoke during pregnancy. The studies proposed in this application aim to examine the molecular basis underlying the increased transgenerational asthma risk following in utero exposure to maternal smoke and are likely to provide pivotal molecular data that can have significant impact on understanding the pathogenesis of, and devising new treatments for, childhood asthma.
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