SAT-158 Offspring Exposed to Maternal High Fat Diet Exhibits Systemic Inflammation and Pancreatic Islet Dysfunction

Offspring born to overweight mothers are more likely to develop dysregulated immune response1, obesity1 and pancreatic islet dysfunction2. These offspring have increased inflammation at birth3 and at least until childhood4. We hypothesize that heightened inflammation in offspring of overweight mothers increases offspring risks of pancreatic islet dysfunction. We induced maternal overweight by providing 45% high fat diet (HFD) to female mice 2 - 4 weeks before pregnancy until weaning. When compared to controls, P21 weanlings of HFD mothers had impaired glucose tolerance in dose and gender dependent manner [GTT AUC: male 2-week HFD* 30 ± 6% higher; male 4-week HFD* 37± 3% higher: 9-11/group; female 2-week HFD 13 ± 5% higher; female 4-week HFD* 22 ± 3% higher: 3-9/group, *p<0.05 compared to controls]. Glucose intolerance persisted in 8-week-old male from 2-week HFD mothers (p<0.05, n=6-9/group), with decreased pancreatic islets glucose induced calcium response measured using Fura-2AM calcium imaging (F1/F0 Con:2.00 ± 0.06, HFD2W: 1.69±0.12*, HFD4w: 0.71±0.09*, n =3/group). Cytokines production in the serum, macrophage response and metabolic phenotypes of offspring were assessed on postnatal day 21 (P21) and at 8 weeks old. Compared to control pups, weanling of HFD mothers had elevated serum/plasma IL-1b level along with increased polarization of M1 macrophages and decreased M2 macrophages, as well as an increase of IL-1b secretion in LPS-stimulated macrophages. At 8 weeks of age, HFD male offspring had increased activation markers of splenic dendritic cells indicating a development of systemic inflammatory response early in life. Taken together, our findings suggest that mice offspring from HFD mothers have pancreatic dysfunction, and an inflammatory response. This work is funded by the Riley Children’s Foundation. 1. Kelishadi, R., Roufarshbaf, M., Soheili, S., Payghambarzadeh, F. & Masjedi, M. Association of Childhood Obesity and the Immune System: A Systematic Review of Reviews. Child. Obes. Print 13, 332-346 (2017). 2. Graus-Nunes, F. et al. Pregestational maternal obesity impairs endocrine pancreas in male F1 and F2 progeny. Nutrition 31, 380-387 (2015). 3. Dosch, N. C. et al. Maternal Obesity Affects Inflammatory and Iron Indices in Umbilical Cord Blood. J. Pediatr. 172, 20-28 (2016). 4. Leibowitz, K. L. et al. Maternal obesity associated with inflammation in their children. World J. Pediatr. WJP 8, 76-79 (2012)

Adiponectin receptor fragmentation in mouse models of type 1 and type 2 diabetes

The protein hormone adiponectin regulates glucose and fatty acid metabolism by binding to two PAQR-family receptors (AdipoR1 and AdipoR2). Both receptors feature a C-terminal segment which is released by proteolysis to form a freely circulating C-terminal fragment (CTF) found in the plasma of normal individuals but not in some undefined diabetes patients. The AdipoR1-CTF344-376 is a competitive inhibitor of tumor necrosis factor α cleavage enzyme (TACE) but it contains a shorter peptide domain (AdipoR1 CTF351-362) that is a strong non-competitive inhibitor of insulin-degrading enzyme (IDE). The link between adiponectin receptor fragmentation and diabetes pathology is unclear but could lead to new therapeutic strategies. We therefore investigated physiological variations in the concentrations of CTF in non-obese diabetic (NOD/ShiLtJ) mice and C57BL/6 mice with diet-induced obesity (DIO) as models of diabetes types 1 and 2, respectively. We tested for changes in adiponectin receptor signaling, immune responses, disease progression, and the abundance of neutralizing autoantibodies. Finally, we administered exogenous AdipoR1-CTF peptides either containing or lacking the IDE-binding domain. We observed the more pronounced CTF shedding in the TACE-active NOD mice, which represents an inflammatory autoimmune phenotype, but fragmentation was also observed to a lesser extent in the DIO model. Autoantibodies to CTF were detected in both models. Neither exogenous CTF peptide affected IgG-CTF plasma levels, body weight or the conversion of NOD mice to diabetes. The pattern of AdipoR1 fragmentation and autoantibody production under physiological conditions of aging, DIO, and autoimmune diabetes therefore provides insight into the association adiponectin biology and diabetes

12-Lipoxygenase governs the innate immune pathogenesis of islet inflammation and autoimmune diabetes

Macrophages and related myeloid cells are innate immune cells that participate in the early islet inflammation of type 1 diabetes (T1D). The enzyme 12-lipoxygenase (12-LOX) catalyzes the formation of proinflammatory eicosanoids, but its role and mechanisms in myeloid cells in the pathogenesis of islet inflammation have not been elucidated. Leveraging a model of islet inflammation in zebrafish, we show here that macrophages contribute significantly to the loss of β cells and the subsequent development of hyperglycemia. The depletion or inhibition of 12-LOX in this model resulted in reduced macrophage infiltration into islets and the preservation of β cell mass. In NOD mice, the deletion of the gene encoding 12-LOX in the myeloid lineage resulted in reduced insulitis with reductions in proinflammatory macrophages, a suppressed T cell response, preserved β cell mass, and almost complete protection from the development of T1D. 12-LOX depletion caused a defect in myeloid cell migration, a function required for immune surveillance and tissue injury responses. This effect on migration resulted from the loss of the chemokine receptor CXCR3. Transgenic expression of the gene encoding CXCR3 rescued the migratory defect in zebrafish 12-LOX morphants. Taken together, our results reveal a formative role for innate immune cells in the early pathogenesis of T1D and identify 12-LOX as an enzyme required to promote their prodiabetogenic phenotype in the context of autoimmunity