Eunice Kennedy Shriver National Institute of Child Health & Human Development P50HD071836 and Oregon National Primate Center Grant P51 OD011092. The authors have no competing conflict of interests to disclose.

Background Inflammation and insulin resistance (IR) are associated processes that potentiate risk for cardiovascular disease in obesity. The temporal relation between IR and inflammation is not completely characterized. We hypothesized that endothelial cell adhesion molecule (ECAM) expression in large arteries is an early event that coincides with diet-induced obesity and IR in primates. Methods and Results Ten adult male rhesus macaques were studied at baseline and every 4-6 months on high-fat diet (HFD) for 2 years. Truncal fat, carotid intima-media thickness (IMT), plasma inflammatory biomarkers, and carotid P-selectin and VCAM-1 expression by contrast-enhanced ultrasound molecular imaging were assessed. Intravenous glucose tolerance test (IVGTT) was performed at baseline, 4 and 18 months. HFD produced a rapid increase (p<0.01) in weight, truncal fat, and degree of IR indicated by the insulin area-under-the-curve and glucose disappearance rate on IVGTT; all of which worsened minimally thereafter. Molecular imaging detected a progressive increase in ECAM expression over time (5-7-fold greater than control agent signal at 2 yrs, p<0.01). Changes in IMT were not detected until 2 years and, while there was a trend toward an increase in plasma markers of inflammation (MCP-1, CRP), the pattern of increase varied considerably over time. Conclusions In primates with diet-induced obesity, endothelial inflammatory activation is an early event that occurs coincident with the development of IR and long before any measurable change carotid IMT. Endothelial activation is more related to the duration rather than severity of IR and is not mirrored by changes in plasma biomarkers.

Graphical Abstract Highlights d The gut peptide PYY 3-36 reduces food intake but causes severe GI intolerability d Like in humans, shorter-acting PYY analogs cause emesis in obese rhesus macaques d mAb-cycPYY is a stable, NPY2R-selective analog with a slow infusion profile d This results in a markedly improved efficacy/emesis therapeutic window in rhesus SUMMARYThe gut hormone PYY 3-36 reduces food intake in humans and exhibits at least additive efficacy in combination with GLP-1. However, the utility of PYY analogs as anti-obesity agents has been severely limited by emesis and rapid proteolysis, a profile similarly observed with native PYY 3-36 in obese rhesus macaques. Here, we found that antibody conjugation of a cyclized PYY 3-36 analog achieved high NPY2R selectivity, unprecedented in vivo stability, and gradual infusion-like exposure. These properties permitted profound reduction of food intake when administered to macaques for 23 days without a single emetic event in any animal. Co-administration with the GLP-1 receptor agonist liraglutide for an additional 5 days further reduced food intake with only one animal experiencing a single bout of emesis. This antibody-conjugated PYY analog therefore may enable the long-sought potential of GLP-1/PYY-based combination treatment to achieve robust, well-tolerated weight reduction in obese patients.