Ceacam1 deletion causes vascular alterations in large vessels

Abstract

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) promotes hepatic insulin clearance and endothelial survival. However, its role in the morphology of macrovessels remains unknown. Mice lacking Ceacam1 (Cc1-/-) exhibit hyperinsulinemia, which causes insulin resistance and fatty liver. With increasing evidence of an association among hyperinsulinemia, fatty liver disease, and atherosclerosis, we investigated whether Cc1-/- exhibited vascular lesions in atherogenic-prone aortae. Histological analysis revealed impaired endothelial integrity with restricted fat deposition and aortic plaque-like lesions in Cc1-/- aortae, likely owing to their limited lipidemia. Immunohistochemical analysis indicated macrophage deposition, and in vitro studies showed increased leukocyte adhesion to aortic wall, mediated in part by elevation in vascular cell adhesion molecule 1 levels. Basal aortic eNOS protein and NO content were reduced, in parallel with reduced Akt/eNOS and Akt/Foxo1 phosphorylation. Ligand-induced vasorelaxation was compromised in aortic rings. Increased NADPH oxidase activity and plasma 8-isoprostane levels revealed oxidative stress and lipid peroxidation in Cc1-/- aortae. siRNA-mediated CEACAM1 knockdown in bovine aortic endothelial cells adversely affected insulin's stimulation of IRS-1/PI 3-kinase/Akt/eNOS activation by increasing IRS-1 binding to SHP2 phosphatase. This demonstrates that CEACAM1 regulates both endothelial cell autonomous and nonautonomous mechanisms involved in vascular morphology and NO production in aortae. Systemic factors such as hyperinsulinemia could contribute to the pathogenesis of these vascular abnormalities. Cc1-/- mice provide a first in vivo demonstration of distinct CEACAM1-dependent hepatic insulin clearance linking hepatic to macrovascular abnormalities.

Liver-specific reconstitution of CEACAM1 reverses the metabolic abnormalities caused by its global deletion in male mice

“…Cells were lysed in 1% Triton-X and subjected (30 μg proteins) to immunoprecipitation at 4°C with streptavidin (Pierce). Immunoprecipitates were centrifuged and analysed by 7% SDS-PAGE and immunoblotting with 1:1000 of insulin receptor alpha (IRα) antibody (N-20; Santa Cruz, Dallas, TX, USA) or a custom-made Ab3759 polyclonal antibody against purified mouse CEACAM1, as titrated [12, 19], followed by horseradish peroxidase-conjugated mouse anti-rabbit IgG antibody (Jackson Immunoresearch, West Grove, PA, USA) and subjected to enhanced chemiluminescence (ECL; Amersham Pharmacia, Sunnyvale, CA, USA).…”

Endothelial barrier function is differentially regulated by CEACAM1‐mediated signaling

“…Cc1 2/2 mice (7,9), CEACAM1 endo+ mice (10), Cc1 2/2/ER mice and their wild-type (WT) littermates (C57BL/6J; The Jackson Laboratory, Bar Harbor, ME, USA), and ApoE 2/2 (B6.129P2-Apoe tm1Unc /J) mice were housed in pathogen-free conditions on a 12:12-h dark-light cycle and fed standard chow ad libitum. Cc1 2/2/ER mice were generated by cross-breeding Cc1 2/2 mice with CEACAM1 endo+ mice (endothelium-specific CEACAM1 overexpression).…”

“…En face staining for eNOS of the aortic endothelium was conducted as previously described (7). In brief, aortic fragments were fixed (4% PFA, 2 h), incubated with goat anti-eNOS antibody (1:100; 4°C, overnight) and subsequently treated with fluorescence-labeled donkey anti-goat antibody.…”

“…Najjar et al (7) reported endothelial dysfunction and the formation of plaque-like lesions in the aortae of CEACAM1-knockout (Cc1 2/2 ) mice, providing the first hint that endothelial integrity in adult vessels depends on CEACAM1. Even after establishment of atherosclerotic plaques, endothelial integrity is of great importance because plaque stability that is clinically relevant essentially depends on luminal covering of plaques by endothelial cells (ECs) (8).…”

CEACAM1 loss links inflammation to insulin resistance in obesity and non-alcoholic steatohepatitis (NASH)

“…Histological examination of liver section revealed that both of Ceacam1 mutants develop microsteatosis on a regular chow diet [249,250]. They also develop a pro-inflammatory state, marked by elevated tissue-associated macrophages, TNFα and IFNγ levels in liver, adipose tissue and aortae [251]. The population of hepatic CD4 + T cell was basally higher than wild type in Cc1 −/− [250], but not in L-SACC1 mice with functional inactivation of Ceacam1 in hepatocytes [249].…”