Abstract 761: Oral Anti-CD3 Antibody Treatment Induces CD4+LAP+ Regulatory T Cells and Ameliorates the Development of Atherosclerosis in Mice
Background: Accumulating evidence suggests that several subsets of regulatory T cells (Tregs) which actively mediate immunologic tolerance play crucial roles in atherogenesis. Recently, orally administered anti-CD3 antibody has been described as an inducer of novel Tregs expressing latency-associated peptide (LAP) on their surface which effectively prevent systemic autoimmunity. This study was undertaken to investigate if oral anti-CD3 antibody treatment would inhibit atherosclerosis in mice.
Methods and Results: Six-week-old apolipoprotein E-deficient mice on a standard diet were orally given anti-CD3 antibody (5μg/day) (n=11) or control IgG (n=7) on 5 consecutive days and atherosclerosis was assessed at 16 weeks old. Oral administration of anti-CD3 antibody significantly reduced atherosclerotic lesion formation (aortic sinus mean plaque area: 0.58±0.07×105 vs. 1.19±0.23×105 μm2, p=0.007) compared to controls. Notably, along with this reduction, we detected decreased macrophage content by 34% (p<0.01) and CD3+ T cell content by 29% (p< 0.05), as well as a marked decrease in IFN-γ mRNA levels by 80% (p<0.05) in atherosclerotic lesions of anti-CD3-treated mice. Flow cytometric analysis revealed that anti-CD3 therapy induced a marked increase in CD4+LAP+ T cells in spleens by 48% (p<0.05) or in mesenteric lymph nodes by 39% (p<0.05) compared with control animals, but did not change the number of naturally occurring CD4+CD25+Foxp3+ Tregs. This induction was associated with increased production of the anti-inflammatory cytokines such as TGF-β (449.0±80.5 vs. 221.8±35.3 pg/ml, p<0.05) or interleukin-10 (p<0.05) and with decreased cell proliferation (p<0.01) in spleen lymphocytes from anti-CD3-treated mice upon polyclonal stimulation compared to controls. Intriguingly, at 16 weeks old, we found TGF-β secretion in spleens of anti-CD3-treated mice still increased (370.2±46.4 pg/ml, p<0.05), suggesting the long-term protective effect.
Conclusions: Our findings indicate the atheroprotective role of oral anti-CD3-antibody treatment via increasing CD4+LAP+ Tregs which mediate inflammatory processes by producing active TGF-β. Induction of CD4+LAP+ Tregs could be a novel and possible strategy to suppress atherosclerosis.