c-Myc Drives inflammation of the maternal-fetal interface, and neonatal lung remodeling induced by intra-amniotic inflammation

Background: Intra-amniotic inflammation (IAI) is associated with increased risk of preterm birth and bronchopulmonary dysplasia (BPD), but the mechanisms by which IAI leads to preterm birth and BPD are poorly understood, and there are no effective therapies for preterm birth and BPD. The transcription factor c-Myc regulates various biological processes like cell growth, apoptosis, and inflammation. We hypothesized that c-Myc modulates inflammation at the maternal-fetal interface, and neonatal lung remodeling. The objectives of our study were 1) to determine the kinetics of c-Myc in the placenta, fetal membranes and neonatal lungs exposed to IAI, and 2) to determine the role of c-Myc in modulating inflammation at the maternal-fetal interface, and neonatal lung remodeling induced by IAI. Methods: Pregnant Sprague-Dawley rats were randomized into three groups: 1) Intra-amniotic saline injections only (control), 2) Intra-amniotic lipopolysaccharide (LPS) injections only, and 3) Intra-amniotic LPS injections with c-Myc inhibitor 10058-F4. c-Myc expression, markers of inflammation, angiogenesis, immunohistochemistry, and transcriptomic analyses were performed on placenta and fetal membranes, and neonatal lungs to determine kinetics of c-Myc expression in response to IAI, and effects of prenatal systemic c-Myc inhibition on lung remodeling at postnatal day 14. Results: c-Myc was upregulated in the placenta, fetal membranes, and neonatal lungs exposed to IAI. IAI caused neutrophil infiltration and neutrophil extracellular trap (NET) formation in the placenta and fetal membranes, and neonatal lung remodeling with pulmonary hypertension consistent with a BPD phenotype. Prenatal inhibition of c-Myc with 10058-F4 in IAI decreased neutrophil infiltration and NET formation, and improved neonatal lung remodeling induced by LPS, with improved alveolarization, increased angiogenesis, and decreased pulmonary vascular remodeling. Discussion: In a rat model of IAI, c-Myc regulates neutrophil recruitment and NET formation in the placenta and fetal membranes. c-Myc also participates in neonatal lung remodeling induced by IAI. Further studies are needed to investigate c-Myc as a potential therapeutic target for IAI and IAI-associated BPD.

Comparative histopathology of Biomphalaria glabrata, B. tenagophila and B. straminea with variable degrees of resistance to Schistosoma mansoni miracidia

A comparative histopathological study of three snails species--Biomphalaria glabrata, B. tenagophila and B. straminea--which had been infected with Schistosoma mansoni miracidia revealed similar qualitative features; consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. However, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different histopathological pictures were observed in different snail species. While B. glabrata exhibited frequent focal (granulomatous) proliferation of amebocytes in several organs, B. tenagophila and B. straminea only rarely showed such reactive changes, suggesting that the mechanism of resistance to miracidial infection probably follows different pathways in the snail species studied.

Induction of ovulation in rabbits by pure urinary luteinizing hormone

In 18-week-old nulliparous rabbit does, ovulation was induced with 50 IU of pure urinary luteinizing hormone (LH; LH group), or 50 IU of human chorionic gonadotrophin (HCG; HCG group), in order to determine the effect of these treatments on 17 beta-oestradiol and progesterone concentrations, and on oocyte and embryo quality. Luteinizing follicles, recovered oocytes, progesterone concentration and grade 5 embryos were significantly reduced when pure urinary LH was used. Statistically significant correlations were found: (i) between oestradiol concentration and number of degenerated oocytes in both groups (positive); (ii) between oestradiol concentration and grade 1 and 2 embryos (negative), and grade 5 embryos (positive) in the HCG group; (iii) between progesterone concentration and metaphase II oocytes (negative), and between progesterone and grade 5 embryos (positive), in the HCG group; and (iv) between progesterone and oestradiol concentrations (negative) in the LH group. It seems that the oestradiol to progesterone ratio improves during the early luteal phase when ovulation is induced with LH, and that oestradiol and progesterone concentrations could play a role in determining oocyte and embryo quality.