Attenuation of early atherosclerotic lesions by immunotolerance with β2 glycoprotein I and the immunomodulatory effectors interleukin 2 and 10 in a murine model Joaquin De Haro, MD, Leticia Esparza, MD, Silvia Bleda, MD, Cesar Varela, MD, Carolina Sanchez, PhD, Francisco Acin, MD, PhD Journal of Vascular Surgery Volume 62, Issue 6, Pages 1625-1631 (December 2015) DOI: 10.1016/j.jvs.2014.05.096 Copyright © 2015 Society for Vascular Surgery Terms and Conditions
Fig 1 Thoracic aorta thickening was significantly inhibited in all groups immunized with β2-glycoprotein I (β2-GPI) compared with the control group. Eight-week-old low-density lipoprotein-receptor deficient (LDLR−/−) mice were treated with a high-fat diet for 1 week before inoculation and then continued on the diet for 8 weeks. To quantify thoracic aorta thickening, tissue segments were harvested after in vitro perfusion fixation with 4% formaldehyde, fixed overnight, and embedded in paraffin. Sequential cross-sections were made throughout the embedded aorta samples. For each animal, six representative sections per vessel segment were used after being stained with hematoxylin and eosin. Aorta thickening was defined as the area between the lumen and adventitia, and determined by subtracting the luminal area from the total vessel wall area. Namely, the thickness of the aortic wall of the control group was significantly higher compared with the groups that were immunized with β2-GPI, β2-GPI plus interleukin (IL)-2, β2-GPI plus IL-10, and β2-GPI plus IL-2 plus IL-10 (0.43 ± 0.002 vs 0.29 ± 0.002 mm2; P = .001). A, Thoracic aorta thickening was increased in the control group, which received phoshpate-buffered saline (PBS) inoculation, compared with the immunized groups, in which mice received one intravenous injection with β2-GPI (5 μg) loaded with or without IL-2 (1 μg) or IL-10 (5 μg), or both. Bar graphs show mean ± standard error of the mean (error bars). *P = .001 immunized experimental groups vs control (n = 24 for each experimental group) by Wilcoxon test. B and C, a, control; b, immunized, hematoxylin and eosin stain. The arrows in C mean internal and xternal diameter of the aorta. Journal of Vascular Surgery 2015 62, 1625-1631DOI: (10.1016/j.jvs.2014.05.096) Copyright © 2015 Society for Vascular Surgery Terms and Conditions
Fig 2 The atheroprotective effect of immunization with β2-glycoprotein I (β2-GPI) was enhanced by a single-dose injection of interleukin (IL)-2 or IL-10, or both. The inoculation with β2-GPI plus IL-2 and with β2-GPI plus IL-10 produced no differences in the aorta thickening among the groups. No differences were found when the group that received β2-GPI plus IL-2 plus IL10 was compared with the groups injected with β2-GPI and the two cytokines separately. Thoracic aorta thickening is shown in groups immunized with β2-GPI only (β2-GPI), β2-GPI associated with IL-2 (β2-GPI+IL-2), along with IL-10 (β2-GPI+Il-10), and with IL-2 and IL-10 (β2-GPI +IL-2+IL-10). The mice received one intravenous injection with β2-GPI (5 μg) loaded with or without IL-2 (1 μg) or IL-10 (5 μg), or both, and were fed a cholesterol-rich high-saturated-fat diet for 8 weeks. Bar graphs show mean ± standard error of the mean (error bars). *P = .001 β2-GPI vs β2-GPI+IL-2; β2-GPI vs β2-GPI+IL-10. †P = .62 β2-GPI+IL-2 vs β2-GPI+IL-10 vs β2-GPI+IL-2+IL-10 (n = 6 for each experimental group) by analysis of variance and the Tukey honest significant difference multiple comparison test. Journal of Vascular Surgery 2015 62, 1625-1631DOI: (10.1016/j.jvs.2014.05.096) Copyright © 2015 Society for Vascular Surgery Terms and Conditions
Fig 3 β2-glycoprotein I (β2-GPI) immunotolerance and the immunomodulatory effectors interleukin (IL)-2 and IL-10 attenuates atherosclerotic lesions in low-density lipoprotein receptor-deficient (LDLR−/−) mice. Aortic root lesions were assessed by measurement of the lumen diameter divided by the total vessel diameter, constituting the ratio lumen/total cross-sectional area, as an objective estimate of the size of the fatty streaks. The ratio lumen/total vessel sectional area of the aorta was significantly increased in the immunized groups compared with the control group (0.85 ± 0.05 vs 0.79 ± 0.04, respectively; P < .001). Bar graphs show lumen/total vessel area ratio of the control group, which received phosphate-buffered saline (PBS) inoculation, and immunized groups that received one intravenous injection with β2-GPI (5 μg) loaded with or without IL-2 (1 μg) or IL-10 (5 μg), or both, and were fed a cholesterol-rich high-saturated-fat diet for 8 weeks. Bar graphs show mean ± standard error of the mean (error bars). *P = .001 immunized experimental groups vs control (n = 24 for each experimental group) by Student t-test. Journal of Vascular Surgery 2015 62, 1625-1631DOI: (10.1016/j.jvs.2014.05.096) Copyright © 2015 Society for Vascular Surgery Terms and Conditions
Fig 4 Atherosclerotic lesion attenuation by immunization with β2-glycoprotein I (β2-GPI) was enhanced by immunomodulation by a single-dose injection of interleukine (IL)-2 or IL-10, or both, in low-density lipoprotein receptor-deficient (LDLR−/−) mice. The inoculation with β2-GPI plus IL-2 (β2-GPI+IL-2), β2-GPI plus IL-10 (β2-GPI+IL-10), and β2-GPI plus IL-2 plus IL-10 (β2-GPI+IL-2+IL-10) produced no differences in the assessment of atherosclerotic lesions when the groups were compared. Lesion size in the aortic root was assessed by measurement of the lumen diameter divided by the total vessel diameter, constituting the ratio lumen/total cross sectional area, as an objective estimate of the size of the fatty streaks. The lumen/total vessel ratio is shown for the β2-GPI, β2-GPI+IL-2, β2-GPI+Il-10, and β2-GPI +IL-2+IL-10 groups. The mice received one intravenous injection with β2-GPI (5 μg) loaded with or without IL-2 (1 μg) or IL-10 (5 μg), or both, and were fed a cholesterol-rich high-saturated-fat diet for 8 weeks. Bar graphs show mean ± standard error of the mean (error bars). *P < .001 β2-GPI vs β2-GPI+IL-2; β2-GPI vs β2-GPI+IL-10. †P = .39 β2-GPI+IL-2 vs β2-GPI+IL-10 vs β2-GPI+IL-2+IL-10 (n = 6 for each experimental group) by analysis of variance and the Tukey multiple comparison test. Journal of Vascular Surgery 2015 62, 1625-1631DOI: (10.1016/j.jvs.2014.05.096) Copyright © 2015 Society for Vascular Surgery Terms and Conditions