Inhibition of CTLA-4 accelerates atherosclerosis in hyperlipidemic mice by modulating the Th1/Th2 balance via the NF-κB signaling pathway

Objective: Though an increased risk of atherosclerosis is associated with anti-CTLA-4 antibody therapy, the underlying mechanisms remain unclear.

Methods: C57BL/6 mice were treated with anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody twice a week for 4 weeks, after being injected with AAV8-PCSK9 and fed a Paigen diet (PD). The proportion of aortic plaque and lipid accumulation were assessed using Oil Red O staining, while the morphology of atherosclerotic lesions was analyzed with hematoxylin and eosin staining. Collagen content was evaluated through Picrosirius Red (PSR) staining, while inflammatory cell infiltration was examined with immunofluorescence staining. CD4⁺ T cells secreting IFN-γ and IL-4, which represent Th1 and Th2 cells respectively, were detected by flow cytometry and real-time PCR. Protein levels of p-IκBα, IκBα, p-p65, and p65 were determined by Western blot.

Results: Inhibiting CTLA-4 exacerbated PD-induced plaque progression and promoted CD4⁺ T cell infiltration in the aortic root. The anti-CTLA-4 antibody promoted CD4⁺ T cell differentiation toward the Th1 type, as indicated by an increase in the Th1/Th2 ratio. Compared to the anti-IgG group, treatment with anti-CTLA-4 antibody significantly elevated the protein levels of p-IκBα and p-p65, as well as the mRNA levels of TNF-α, IL-6, ICAM-1, and VCAM-1. Inhibiting the NF-κB signaling pathway attenuated the overall pathological phenotype induced by the anti-CTLA-4 antibody treatment.

Conclusion: Anti-CTLA-4 treatment promotes the progression of atherosclerosis by activating NF-κB signaling and modulating the Th1/Th2 balance. Our results provide a rationale for preventing and/or treating atherosclerosis accelerated by anti-CTLA-4 antibody therapy in cancer patients.