Journal: Frontiers in Pharmacology
Article Title: Targeting SAA expression via siRNA mitigates preterm birth induced by maternal inflammation
doi: 10.3389/fphar.2026.1749966
Figure Lengend Snippet: Maternal administration of si Saa2 reduces placental SAA2 expression and alleviates abnormal placental histology and fetal brain cortical changes following sub-chronic maternal inflammation. (A) A schematic diagram illustrating the study design for the mouse model of acute intrauterine injection using LPS. (B) A schematic diagram illustrating the study strategy for the mouse model of sub-chronic maternal inflammation using IL-1β intraperitoneal injection. SiRNA was infused using intravenous injections. (C) Placental concentrations of IL-1 β were measured by enzyme linked immunosorbent assay (ELISA). ( n = 4 per group). (D) Representative Western blotting of Saa2 expression in the placenta and statistical analysis normalized to the levels of β-actin as a loading control. PBS+PBS, n = 8; IL-1 β +PBS, n = 19; IL-1 β +si Saa2 , n = 9; PBS+si Saa2 , n = 3. (E) Representative fluorescence immunostaining for Saa2 (red) and DAPI (blue, nucleic staining) in the labyrinth of placentas. n = 3, 5 images per mouse examined. Scale bars, 50 μm. (F) Real-time quantitative polymerase chain reaction (RT‒qPCR) was performed to evaluate the effect of siRNA treatment, n = 6 for each group (G) Hematoxylin and eosin (H&E) staining was performed to compare placental thicknesses at ×5 magnification. The solid arrows crossing the central cut surface of the placentas indicate the location of measurements: fetal segments were identified as a compilation of the junctional zone and labyrinth. Scale bars, 200 μm (H) Statistical analysis shows the results of H&E staining measuring fetal placental length at the thickest location. PBS+PBS, n = 3; IL-1 β +PBS, n = 4; IL-1 β +si Saa2 , n = 3; PBS+si Saa2 , n = 3. (I) Nissl staining was performed to measure cortical thickness (upper red arrows) and ventricle area (lower red panels) in the fetal brain. Scale bars, 200 μm. (J,K) Nissl staining measuring cortical thickness and ventricle area. Quantitative data, with the median indicated by the solid line for each group, represents the average of these measurements from five random brain sections for each litter. PBS+PBS, n = 3; IL-1 β +PBS, n = 6; IL-1 β +si Saa2 , n = 4; PBS+si Saa2 , n = 3 (L) The fetal viability per litter. (M) Preterm birth rates. PBS+PBS, n = 18; IL-1 β +PBS, n = 34; IL-1 β +si Saa2 , n = 30; PBS+si Saa2 , n = 10. (N) Representative images of the placenta and its corresponding fetus between groups. (O,P) Placenta (O) and fetal weights (P) . PBS+PBS, n = 10; IL-1 β +PBS, n = 16; IL-1 β +si Saa2 , n = 8; PBS+si Saa2 , n = 8. IUI: intrauterine injection; IV: intravenous; IP: intraperitoneal. Values are expressed as the mean ± SEM, One-way ANOVA with Bonferroni post hoc tests for multiple comparisons of normally distributed data and Kruskal‒Wallis with Dunn’s multiple comparisons tests for nonparametric data (C,D,F,H,J,K,O,P) . Chi-square test (L,M) , * p < 0.05, ** p < 0.01, *** p < 0.001.
Article Snippet: Cells were cultured with the addition of mouse SAA2 protein (CUSABIO Technology, Houston, TX) at 100–1,000 ng/mL or LPS (1 μg/mL) based on published in vitro studies ( ; ; ) and pilot experiments showing macrophage activation within this range.
Techniques: Expressing, Injection, Enzyme-linked Immunosorbent Assay, Western Blot, Control, Fluorescence, Immunostaining, Staining, Real-time Polymerase Chain Reaction