Endothelin-1 Dependent Pathways in Toll-llike Receptor 4 Mediated Preterm Birth
Sandra E. Reznik and Ralph Stephani, College of Pharmacy and Health Sciences, Department of Pharmaceutical Sciences; Graduate Students: Nicole S. Olgun and Vibhuti Vyas
Defined as any birth occurring prior to 37 weeks’ gestation, preterm birth (PTB) accounts for approximately 13% of all live births in the United States and is a leading cause of infant mortality. The single most common cause of spontaneous preterm birth is intrauterine infection (40%). Endothelin-1 (ET-1) is a potent vasoconstrictor peptide which is upregulated by inflammatory cytokines in the presence of infection, and is capable of causing an increase in myometrial tone, ultimately leading to premature delivery. Previously, we have shown that our novel series of 1-3-6-trisubstituted-2-carboxy-quinol-4-ones act as highly selective Endothelin-A receptor antagonists (ET A-RAs). In particular, HJP-272 binds to the ET A receptor with an IC 50 value of 70.1nM We have also shown that in the animal model, HJP-286, the n-propyl analogue, and HJP-272 successfully shut down PTB at doses in which we see no toxicity in the mother. Currently, we aim to elucidate the pathway by which these compounds act on the uterus, ultimately leading to the prevention of PTB. In order to simulate infection, animals were injected intraperitoneally with lipopolysaccharide (LPS), a major component of the outer wall of Gram-negative bacteria, and were then injected with either an ET A-RA , or phosphate buffered saline ten hours later. Toll-like receptor 4 (TLR4) is a transmembrane protein capable of recognizing and responding to gram-negative bacteria, initiating the innate immune system in the host against non-self. Using qRT-PCR and examining a panel of 84 genes associated with infection and TLR4-mediated inflammation, we are able to identify the pathways affected by our novel compounds at the level of gene transcription. It is our hope that these compounds may one day affect the way pregnant women presenting with PTB are treated, as there is currently no FDA approved therapy for this very important clinical disorder.