Heterozygous Eif4nif1 Stop Gain Mice Replicate the Primary Ovarian Insufficiency Phenotype in Women.

We created the c.1286C>G stop-gain mutation found in a family with primary ovarian insufficiency (POI) at age 30 years. The Eif4enif1 C57/Bl6 transgenic mouse model contained a floxed exon 10-19 cassette with a conditional knock-in cassette containing the c.1286C>G stop-gain mutation in exon 10. The hybrid offspring of CMV- Cre mice with Eif4enif1 WT/flx mice were designated Eif4enif1 WT/ Δ for simplicity. A subset of female heterozygotes ( Eif4enif1 WT/ Δ ) had no litters. In those with litters, the final litter was earlier (5.4±2.6 vs. 10.5±0.7 months; p=0.02). Heterozygous breeding pair ( Eif4enif1 WT/ Δ x Eif4enif1 WT/ Δ ) litter size was 60% of WT litter size (3.9±2.0 vs. 6.5±3.0 pups/litter; p <0.001). The genotypes were 35% Eif4enif1 WT/flx and 65% Eif4enif1 WT/ Δ , with no homozygotes. Homozygote embryos did not develop beyond the 4-8 cell stage. The number of follicles in ovaries from Eif4enif1 WT/ Δ mice was lower starting at the primordial (499±290 vs. 1445±381) and primary follicle stage (1069±346 vs. 1450±193) on day 10 (p<0.05). The preantral follicle number was lower starting on day 21 (213±86 vs. 522±227; p<0.01). Examination of ribosome protected mRNAs (RPR) demonstrated altered mRNA expression. The Eif4enif1 stop-gain mice replicate the POI phenotype in women. The unique mouse model provides a platform to study regulation of protein translation across oocyte and embryo development in mammals.

Impact of Maternal Exercise on Mice Offspring Development, Pulmonary Hypertension, and Vascular Remodeling in Chronic Hypoxia.

PURPOSE: Chronic, high-altitude hypoxic exposure increases the risk of high-altitude pulmonary hypertension (PH). Emerging evidence shows maternal exercise may improve offspring resistance to disease throughout life. The purpose of this study is to determine if maternal exercise mitigates chronic hypoxic-induced changes in the offspring indicative of high-altitude pulmonary hypertension development. METHODS: Female adult C57BL/6 J mice were randomly allocated to nonexercise or exercise conditions. Exercise consisted of voluntary running wheel exercise for four weeks during the perinatal period. Three days after birth, the pups remained at low altitude (normoxia) or were exposed to hypobaric hypoxia of 450 mmHg to simulate ~4500 m altitude exposure until 8 weeks of age. The study consisted of 4 groups: Hypoxia + Nonexercise pregnancy, Hypoxia + Exercise, or the respective, normoxia conditions (Normoxia + Nonexercise or Normoxia + Exercise). Offspring body size, motor function, right ventricular systolic pressure (RVSP), and cardiopulmonary morphology were assessed after 8 weeks in normoxia or hypoxia. RESULTS: Both hypoxic groups had smaller body sizes, reduced motor function, increased hematocrit, RVSP, muscularization in medium-sized pulmonary arteries, as well as right ventricular hypertrophy and contractility compared to the normoxic groups ( p < 0.05). CONCLUSIONS: Chronic hypoxia simulating 4500 m attenuated growth, lowered motor function, and elicited PH development. Voluntary maternal exercise did not significantly decrease RVSP in the offspring, which aligned with a lack of effect to attenuate abnormal body size and cardiopulmonary development due to chronic hypoxia. These findings are preliminary in nature and more powered studies through larger group sizes are required to generalize the results to the population.

Chronic hypoxia disrupts T regulatory cell phenotype contributing to the emergence of exTreg-TH17 cells.

The imbalance between pro-inflammatory T helper 17 (TH17) cells and anti-inflammatory regulatory T cells (Tregs) has been implicated in multiple inflammatory and autoimmune conditions, but the effects of chronic hypoxia (CH) on this balance have yet to be explored. CH-exposed mice have an increased prevalence of TH17 cells in the lungs with no change in Tregs. This imbalance is significant because it precedes the development of pulmonary hypertension (PH), and TH17 cells are a major contributor to CH-induced PH. While Tregs have been shown to attenuate or prevent the development of certain types of PH through activation and adoptive transfer experiments, why Tregs remain unable to prevent disease progression naturally, specifically in CH-induced PH, remains unclear. Our study aimed to test the hypothesis that increased TH17 cells observed following CH are caused by decreased circulating levels of Tregs and switching of Tregs to exTreg-TH17 cells, following CH. We compared gene expression profiles of Tregs from normoxia or 5-day CH splenocytes harvested from Foxp3tm9(EGFP/cre/ERT2)Ayr/J x Ai14-tdTomato mice, which allowed for Treg lineage tracing through the presence or absence of EGFP and/or tdTomato expression. We found Tregs in CH exposed mice contained gene profiles consistent with decreased suppressive ability. We determined cell prevalence and expression of CD25 and OX40, proteins critical for Treg function, in splenocytes from Foxp3tm9(EGFP/cre/ERT2)Ayr/J x Ai14-tdTomato mice under the same conditions. We found TH17 cells to be increased and Tregs to be decreased, following CH, with protein expression of CD25 and OX40 in Tregs matching the gene expression data. Finally, using the lineage tracing ability of this mouse model, we were able to demonstrate the emergence of exTreg-TH17 cells, following CH. These findings suggest that CH causes a decrease in Treg suppressive capacity, and exTregs respond to CH by transitioning to TH17 cells, both of which tilt the Treg-TH17 cell balance toward TH17 cells, creating a pro-inflammatory environment.