Yosdel Soto

Induction of Anti-Anti-Idiotype Antibodies Against Sulfated Glycosaminoglycans Reduces Atherosclerosis in Apolipoprotein E–Deficient Mice

Objective—The pathogenesis of atherosclerosis is associated with the early retention of low-density lipoproteins that are trapped in the extracellular matrix of the arterial intima by interaction with glycosaminoglycan side chains of proteoglycans. Mutant mouse/human chimeric antibodies of the murine monoclonal antibody P3, which react with N-glycolyl–containing gangliosides and sulfated glycosaminoglycans, were tested for their potentially antiatherogenic properties through the induction of an idiotypic antibody network that may specifically interfere with the binding of low-density lipoproteins to proteoglycan side chains, low-density lipoprotein modification, and foam cell formation. Methods and Results—Apolipoprotein E–deficient mice fed a high-fat, high-cholesterol diet received 5 to 6 doses of chP3R99 or chP3S98 mutant antibodies, showing high and low reactivity, respectively, against their respective antigens. Both chimeric antibodies elicited an immunodominant anti-idiotypic response in the absence of adjuvant. A striking (40%–43%) reduction (P<0.01) in total lesion areas was observed in 18-week-old mice immunized with chP3R99, but not chP3S98, compared with PBS-treated mice. The antiatherosclerotic effect was associated with increased mice sera reactivity against heparin and sulfated glycosaminoglycans, including chondroitin and dermatan sulfate. In addition, purified IgG from chP3R99-immunized mice blocked the retention of apolipoprotein B–containing lipoproteins within the arterial wall of apolipoprotein E−/− mice. Conclusion—The present study supports use of active immunization and the mounting of an idiotypic antibody network response against glycosaminoglycans as a novel approach to target atherosclerosis.

Antiatherosclerotic Effect of an Antibody That Binds to Extracellular Matrix Glycosaminoglycans

Objective—Subendothelial retention of proatherogenic lipoproteins by proteoglycans is critical in atherosclerosis. The aim of this study was to characterize the recognition and antiatherogenic properties of a chimeric monoclonal antibody (mAb) that reacts with sulfated molecules. Methods and Results—chP3R99 mAb recognized sulfated glycosaminoglycans, mainly chondroitin sulfate (CS), by ELISA. This mAb blocked ≈70% of low-density lipoprotein (LDL)–CS association and ≈80% of LDL oxidation in vitro, and when intravenously injected to Sprague-Dawley rats (n=6, 1 mg/animal), it inhibited LDL (4 mg/kg intraperitoneally, 1 hour later) retention and oxidation in the artery wall. Moreover, subcutaneous immunization of New Zealand White rabbits (n=19) with chP3R99 mAb (100 &mgr;g, 3 doses at weekly intervals) prevented Lipofundin-induced atherosclerosis (2 mL/kg, 8 days) with a 22-fold reduction in the intima-media ratio (P<0.01). Histopathologic and ultrastructural studies showed no intimal alterations or slight thickening, with preserved junctions between endothelial cells and scarce collagen fibers and glycosaminoglycans. In addition, immunization with chP3R99 mAb suppressed macrophage infiltration in aorta and preserved redox status. The atheroprotective effect was associated with the induction of anti-CS antibodies in chP3R99-immunized rabbits, capable of blocking CS-LDL binding and LDL oxidation. Conclusion—These results support the use of anti-sulfated glycosaminoglycan antibody–based immunotherapy as a potential tool to prevent atherosclerosis.

The treatment with an anti-glycosaminoglycan antibody reduces aortic oxidative stress in a rabbit model of atherosclerosis

Abstract Retained low-density lipoproteins (LDL) by arterial glycosaminoglycans (GAG) are more susceptible to reactive oxygen species-mediated oxidation, contributing to oxidative stress and atherosclerosis. Recently, we reported the properties of the chimeric mouse/human monoclonal antibody chP3R99-LALA to bind sulfated GAG, to inhibit LDL-chondroitin sulfate binding, and to avoid LDL oxidation in vitro. Here, we hypothesized that chP3R99-LALA treatment might reduce aortic oxidative stress in a therapeutic setting. Redox biomarkers and serum lipids were determined by spectrophotometric methods. Subcutaneous administration of five doses (100 μg) of chP3R99-LALA, after Lipofundin administration (2 mL/kg/day, i.v.) during 8 days, reduced atherosclerotic lesion development, which was not associated with a serum lipid modulation. In contrast, the treatment with chP3R99-LALA reduced (p < 0.05) malondialdehyde and protein oxidation, induced a restoration of reduced glutathione level, of the superoxide dismutase and catalase activities and of endothelial nitric oxide level. Thus, the antiatherogenic effect of chP3R99-LALA treatment seems to be associated with a reduction of aortic oxidative stress. These results contribute in understanding the molecular mechanisms associated with chP3R99-LALA atheroprotection and support the use of anti-GAG antibody-based immunotherapy as a potential tool to treat the atherosclerosis.

Arresting progressive atherosclerosis by immunization with an anti-glycosaminoglycan monoclonal antibody in apolipoprotein E-deficient mice

Atherogenesis is associated with the early retention of low-density lipoproteins (LDL) in the arterial intima by interaction with glycosaminoglycan (GAG)-side chains of proteoglycans. Retained LDL undergo reactive oxygen species-mediated oxidation. Oxidized LDL trigger oxidative stress (OS) and inflammation, contributing to atherosclerosis development. Recently, we reported the preventive anti-atherogenic properties of the chimeric mouse/human monoclonal antibody (mAb) chP3R99-LALA, which were related to the induction of anti-chondroitin sulfate antibody response able to inhibit chondroitin sulfate dependent LDL-enhanced oxidation. In the present work, we aimed at further investigating the impact of chP3R99-LALA mAb vaccination on progressive atherosclerosis in apolipoprotein E-deficient mice (apoE(-/-)) fed with a high-fat high-cholesterol diet receiving 5 doses (50 µg) of the antibody subcutaneously, when ~5% of the aortic area was covered by lesions. Therapeutic immunization with chP3R99-LALA mAb halted atherosclerotic lesions progression. In addition, aortic OS was modulated, as shown by a significant (p<0.05) reduction of lipid and protein oxidation, preservation of antioxidant enzymes activity and reduced glutathione, together with a decrease of nitric oxide levels. chP3R99-LALA mAb immunization also regulated aortic NF-κB activation, diminishing the proinflammatory IL1-β and TNF-α gene expression as well as the infiltration of macrophages into the arterial wall. The therapeutic immunization of apoE(-/-) with progressive atheromas and persistent hypercholesterolemia using chP3R99-LALA mAb arrested further development of lesions, accompanied by a decrease of aortic OS and NF-κB-regulated pro-inflammatory cytokine gene expression. These results contribute to broaden the potential use of this anti-GAG antibody-based immunotherapy as a novel approach to target atherosclerosis at different phases of progression.

Targeting arterial wall sulfated glycosaminoglycans in rabbit atherosclerosis with a mouse/human chimeric antibody.

The progression of atherosclerosis is favored by increasing amounts of chondroitin sulfate proteoglycans in the artery wall. We previously reported the reactivity of chP3R99 monoclonal antibody (mAb) with sulfated glycosaminoglycans and its association with the anti-atherogenic properties displayed. Now, we evaluated the accumulation of this mAb in atherosclerotic lesions and its potential use as a probe for specific in vivo detection of the disease. Atherosclerosis was induced in NZW rabbits (n = 14) by the administration of Lipofundin 20% using PBS-receiving animals as control (n = 8). Accumulation of chP3R99 mAb in atherosclerotic lesions was assessed either by immunofluorescence detection of human IgG in fresh-frozen sections of aorta, or by immunoscintigraphy followed by biodistribution of the radiotracer upon administration of 99mTc-chP3R99 mAb. Immunofluorescence studies revealed the presence of chP3R99 mAb in atherosclerotic lesions 24 h after intravenous administration, whereas planar images showed an evident accumulation of 99mTc-chP3R99 mAb in atherosclerotic rabbit carotids. Accordingly, 99mTc-chP3R99 mAb uptake by lesioned aortic arch and thoracic segment was increased 5.6-fold over controls and it was 3.9-folds higher in carotids, in agreement with immunoscintigrams. Moreover, the deposition of 99mTc-chP3R99 mAb in the artery wall was associated both with the presence and size of the lesions in the different portions of evaluated arteries and was greater than in non-targeted organs. In conclusion, chP3R99 mAb preferentially accumulates in arterial atherosclerotic lesions supporting the potential use of this anti-glycosaminoglycans antibody for diagnosis and treatment of atherosclerosis.

Dose-Dependent Induction of an Idiotypic Cascade by Anti-Glycosaminoglycan Monoclonal Antibody in apoE−/− Mice: Association with Atheroprotection

Atherosclerosis, the underlying pathology of most cardiovascular diseases, is triggered by the retention of apolipoprotein B (apoB)-containing lipoproteins in the arterial wall through electrostatic interactions with glycosaminoglycan (GAG) side chains of proteoglycans. Previously, we reported the antiatherogenic properties of the chimeric monoclonal antibody (mAb) chP3R99-LALA, which binds sulfated GAGs, inhibits low-density lipoprotein (LDL)–chondroitin sulfate (CS) association, and abrogates LDL oxidation and foam cell formation. In preventive and therapeutic settings, apoE-deficient (apoE−/−) mice immunized with 50 μg of this mAb showed reduced atherosclerotic lesions related with the induction of autologous anti-GAG antibodies. Knowing that age and sex are major non-modifiable risk factors in the development of atherosclerosis, the present study aimed to assess the influence of these variables on the capacity of chP3R99-LALA mAb to generate an anti-CS antibody response. Also, we aimed at defining the impact of the dose of chP3R99-LALA on the anti-CS antibody induction and the atheroprotective effect of this mAb in apoE−/− mice. Neither age nor sex had an impact in the IgG anti-CS antibody response induced by s.c. immunization with this mAb. Moreover, chP3R99-LALA mAb reduced atherosclerotic lesions to a similar extent in both young male and female apoE−/− mice fed a hypercholesterolemic diet and, in middle-aged female apoE−/− mice, with spontaneous lesions. On the other hand, increasing the dose of chP3R99-LALA (200 vs. 50 μg) elicited an anti-idiotype antibody cascade characterized by higher levels of anti-idiotype (Ab2), anti-anti-idiotype (Ab3), and anti-CS antibody responses. Moreover, this dose increment resulted in a striking reduction of aortic atherosclerotic lesions in immunized mice.