Intrauterine inflammation (IUI) is a major contributor to preterm labor and fetal inflammation leading to injury responses in fetal organs such as the brain, lung and the GI tract. Although inflammation is known to be the proximate cause of preterm labor and fetal complications in IUI, no anti-inflammatory therapies are currently available, partly because the mechanism/s of inflammation are not well understood. New therapeutic targets are urgently needed to stem the tide and costly sequelae of IUI and preterm labor. We investigated these mechanisms in a preterm gestation Rhesus macaque model of IUI induced by intra-amniotic injection of LPS, and by using tissues from women delivering preterm infants. Our key findings supporting this application are: (i) Neutrophils infiltrating the chorio-decidua during IUI are activated with prolonged survival and a contributor to the inflammation at the maternal-fetal interface; (ii) The anti-apoptosis mediator, Bfl1 (also known as Bcl-2A1 in mice), is up-regulated specifically in the chorio-decidua neutrophils during IUI; (iii) Bfl1 increases survival of activated neutrophils. In this multi-PI application, we will test the hypothesis that Bfl1 promotes neutrophil survival and exacerbates inflammatory responses in the chorio-decidua. Our approach is to develop a high-affinity Bfl1 inhibitor as a potential novel therapy for IUI. A compelling rationale for focusing on Bfl1 is that it's up-regulation is specific to activated hematopoietic cells and these activated cells are uniquely susceptible to Bfl1 inhibition. This property of Bfl1 overcomes a major hurdle in anti-inflammatory therapy of undesired deleterious effects on basal immune function. Our study will build on proof-of-concept pre-clinical studies from other labs demonstrating efficacy of anti-Bfl1 directed therapies targeting activated basophil- mediated anaphylaxis or triggering apoptosis in resistant cancer cells.
In Aim 1, we will exploit our expertise in drug-design by using in silico, biochemical, and crystallographic approaches to find compounds with high affinity for Bfl1 but not other Bcl-2 members. After screening primary compounds for efficacy in mouse cells, a key feature in our approach is the use of counter-screening secondary assays. Here, we will screen the lead compounds for lack of biologic effects in mouse cells devoid of Bax/Bak, the downstream executioners of the Bcl-2A1 (Bfl1) regulated apoptotic pathway. This will minimize any pro-apoptotic compounds with off-target effects.
In Aim 2, the efficacy of the lead compounds will be tested in activated chorio-decidua cells from women with histologic chorioamnionitis, and the efficacy will be compared against siRNA-mediated blockade. Completion of these studies will provide novel clinical candidate compounds that can be tested in pre-clinical in vivo studies using mouse and non-human primate models that our group already has. A distinctive feature of our application is the collaborative multi-disciplinary team with expertise in clinical-translational perinatal inflammation, Bcl-2 immunology, medicinal chemistry, and rational drug-design. !

Public Health Relevance

to Public health: Intrauterine inflammation is an important cause of preterm labor and injury to the brain, lung and GI tract of the unborn fetus and thus constitutes a major public health problem in this population. New therapies are desperately needed because the current therapies are inadequate in treating the disease. This grant will develop novel chemical inhibitors of Bfl-1 (Bcl-2A1), a mediator of prolonged neutrophil survival that exacerbates intrauterine inflammation.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Exploratory/Developmental Grants (R21)
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Special Emphasis Panel (ZRG1)
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Ren, Zhaoxia
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Cincinnati Children's Hospital Medical Center
United States
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Herr, Andrew B (2018) Evolution of an allosteric ""off switch"" in apoptotic caspases. J Biol Chem 293:5462-5463