FIGURE 4. Intra-amniotic administration of IL-22 shortens gestational length and causes neonatal death in mice.

(A) In the absence of microbial invasion of the amniotic cavity, increased IL-22 could lead to fetal injury. (B) Mice received an ultrasound-guided intra-amniotic injection of recombinant mouse (rm)IL-22 on 16.5 days post coitum (dpc) and were monitored until delivery. Color Doppler was used to identify the injection jet sign to confirm successful intra-amniotic injection. (C) Gestational length (dpc) of mice that received an intra-amniotic injection of rmIL-22 at 1.2 (pink; n = 8), 70 (dark pink; n = 6), or 612 (red; n =8) pg/amniotic sac or PBS (blue; n = 8) as vehicle control. (D) Kaplan-Meier survival curves representing survival at weeks 1, 2, and 3 of neonates born to mice that received intra-amniotic injection of rmIL-22 at 1.2 (pink; n =42), 70 (dark pink; n = 60), or 612 (red; n = 59) pg/amniotic sac or PBS (blue; n = 54). P-values were determined using the Mantel-Cox test. (E) Representative images of neonates born to mice that received intra-amniotic injection of PBS (top row) or rmIL-22 (612 pg/amniotic sac) (bottom row). (F-H) Weights at weeks 1, 2, and 3 of neonates born to mice that received intra-amniotic injection of rmIL-22 at 1.2 (pink; n = 5 litters), 70 (dark pink; n = 8 litters), or 612 (red; n = 5 litters) pg/amniotic sac or PBS (blue; n = 7 litters). Each dot corresponds to the mean weight of a litter of pups. Data are shown as scatter plots with means.