Chorioamnionitis Induces a Specific Signature of Placental ABC Transporters Associated with an Increase of miR-331-5p in the Human Preterm Placenta.

BACKGROUND/AIMS: The ATP-binding cassette (ABC) transporters mediate drug biodisposition and immunological responses in the placental barrier. In vitro infective challenges alter expression of specific placental ABC transporters. We hypothesized that chorioamnionitis induces a distinct pattern of ABC transporter expression. METHODS: Gene expression of 50 ABC transporters was assessed using TaqMan® Human ABC Transporter Array, in preterm human placentas without (PTD; n=6) or with histological chorioamnionitis (PTDC; n=6). Validation was performed using qPCR, immunohistochemistry and Western blot. MicroRNAs known to regulate P-glycoprotein (P-gp) were examined by qPCR. RESULTS: Up-regulation of ABCB9, ABCC2 and ABCF2 mRNA was detected in chorioamnionitis (p<0.05), whereas placental ABCB1 (P-gp; p=0.051) and ABCG2 (breast cancer resistance protein-BCRP) mRNA levels (p=0.055) approached near significant up-regulation. In most cases, the magnitude of the effect significantly correlated to the severity of inflammation. Upon validation, increased placental ABCB1 and ABCG2 mRNA levels (p<0.05) were observed. At the level of immunohistochemistry, while BCRP was increased (p<0.05), P-gp staining intensity was significantly decreased (p<0.05) in PTDC. miR-331-5p, involved in P-gp suppression, was upregulated in PTDC (p<0.01) and correlated to the grade of chorioamnionitis (p<0.01). CONCLUSIONS: Alterations in the expression of ABC transporters will likely lead to modified transport of clinically relevant compounds at the inflamed placenta. A better understanding of the potential role of these transporters in the events surrounding PTD may also enable new strategies to be developed for prevention and treatment of PTD.

The Impact of a Non-Functional Thyroid Receptor Beta upon Triiodotironine-Induced Cardiac Hypertrophy in Mice.

BACKGROUND/AIMS: Thyroid hormone (TH) signalling is critical for heart function. The heart expresses thyroid hormone receptors (THRs); THRα1 and THRß1. We aimed to investigate the regulation mechanisms of the THRß isoform, its association with gene expression changes and implications for cardiac function. METHODS: The experiments were performed using adult male mice expressing TRßΔ337T, which contains the Δ337T mutation of the human THRB gene and impairs ligand binding. Cardiac function and RNA expression were studied after hypo-or hyperthyroidism inductions. T3-induced cardiac hypertrophy was not observed in TRßΔ337T mice, showing the fundamental role of THRß in cardiac hypertrophy. RESULTS: We identified a group of independently regulated THRß genes, which includes Adrb2, Myh7 and Hcn2 that were normally regulated by T3 in the TRßΔ337T group. However, Adrb1, Myh6 and Atp2a2 were regulated via THRß. The TRßΔ337T mice exhibited a contractile deficit, decreased ejection fraction and stroke volume, as assessed by echocardiography. In our model, miR-208a and miR-199a may contribute to THRß-mediated cardiac hypertrophy, as indicated by the absence of T3-regulated ventricular expression in TRßΔ337T mice. CONCLUSION: THRß has important role in the regulation of specific mRNA and miRNA in T3-induced cardiac hypertrophic growth and in the alteration of heart functions.