OR21-04 Developmental Programming: Origin of MASLD in a Sheep Model of Polycystic Ovary Syndrome and Impact of Postnatal Obesity on its Severity

Abstract Disclosure: K.M. Halloran: None. J. Sustaita: None. R. Cardoso: None. V. Padmanabhan: None. ​Metabolic dysfunction is associated with insulin resistance and a hyper-inflammatory/oxidative state which is worsened by obesity. This can lead to metabolic dysfunction-associated steatotic liver disease (MASLD). The trajectory of MASLD may be established early in life, and animal models provide a means to study the developmental origins of this disease. Prenatal testosterone (T) treated sheep from gestational days (GD) 30-90 manifest insulin resistance, a hyper-inflammatory/oxidative state, and hepatic lipid and collagen accumulation, like MASLD, in normal weight adults. While postnatal obesity could further exacerbate this phenotype, the severity of the phenotype in the GD 30-90 model will likely mask effects of postnatal obesity. Prenatal T from GD 60-90 results in a mild metabolic phenotype, allowing assessment of amplifying effects of postnatal obesity on the prenatally programmed phenotype. We hypothesized that prenatal T treatment from GD 60-90 causes liver disease that is worsened by obesity in adults. Pregnant sheep received twice weekly im injections of either T propionate (100 mg) in corn oil or vehicle control (C) from GD 60-90 (term ∼147 days). At 5 months of age, female offspring from C and T groups were fed a maintenance (M) diet, while another T offspring group were overfed (O). Ewes (n=6/group) were euthanized and liver collected at ∼3 years of age. Frozen liver was assayed for total collagen and triglyceride content, and paraffin embedded liver was sectioned and stained for collagen using picrosirius red and neutral lipid droplets using oil red O. Plasma was assayed for proinflammatory cytokines and total oxidant and antioxidant status. Data were analyzed with ANOVA and Tukey post hoc tests, and Cohens D effect size (d≥0.8 represents large effect size). In plasma, there were greater levels of oxidants in TM (P=0.036) and TO (P=0.008) compared to C, with no differences in antioxidant status between TM and TO. IL17a was higher in TO vs C (P=0.012) and TM (P=0.021) ewes. Similarly, IP10 was higher in TO vs C (d=0.95) and TM (d=0.95) ewes. Greater neutral lipid droplet accumulation was evident in TO vs C (P=0.048) and TM (P=0.009), but triglyceride content unaffected by treatment. Both TM (d=0.84) and TO (P=0.03) had greater collagen staining area vs C livers, while the total collagen content was greater in TO vs TM livers (P=0.049). Collectively, greater levels of oxidants in T treated ewes and greater levels of pro-inflammatory cytokines IL17A and IP10 in obese T ewes, combined with increased lipid and collagen content liver of obese ewes, are consistent with the hyper-inflammatory, oxidative state of MASLD that is worsened by obesity. This provides foundational evidence for the developmental origin of metabolic disease. Future investigation of effects on the transcriptomic level in liver would reveal regulatory mechanisms that contribute to MASLD. Funding P30DK089503, R01HD099096 Presentation: Saturday, July 12, 2025