Ultrasound-Triggered NPC1L1-Targeting Nanobubbles for Remodeling the Tumor Microenvironment in Pancreatic Cancer Chemoimmunotherapy

Abstract

Abnormal cholesterol metabolism promotes the immunosuppressive microenvironment of pancreatic cancer and affects the long-term efficacy of chemotherapy drugs. Accurate diagnosis and targeted microenvironment-remodeling are challenging during the asymptomatic phase, considerably weakening the antitumor response. To modulate the cholesterol uptake pathway in pancreatic cancer, we developed a seamless diagnostic and chemoimmunotherapy system comprising gemcitabine-loaded nanobubbles with a cholesterol component shell (CHOL@GEM-NBs) fabricated to target the cholesterol transporter Niemann-Pick C1-like 1 (NPC1L1) precisely. The system achieved sufficient permeability to enhance the targeted accumulation of NBs extravasation in tumor blood vessels to locate the tumor region. The CHOL@GEM-NBs exhibited excellent ultrasound molecular imaging performance, with increased contrast intensity and duration time. Moreover, we employed ultrasound-targeted nanobubble destruction (UTND) to facilitate cytotoxicity by enhancing cellular uptake and drug release. This approach reduced NPC1L1 expression and mitigated cholesterol hijacking by tumor cells in the microenvironment. Additionally, ultrasound and cavitation triggered immunogenic cell death to release damage-associated molecular patterns. Essential cholesterol flow restoration and adaptive immunity activation improved the immunosuppressive microenvironment, as evidenced by the increased infiltration of CD8⁺ cytotoxic T lymphocytes, increased cytokine secretion, decreased proportion of regulatory T cells in tumor tissues, and increased proportions of CD45⁺, CD3⁺, and CD8⁺ T cells in the spleen and draining lymph nodes. In conclusion, the combined CHOL@GEM-NBs and UTND strategy can effectively permeate and reshape the immunosuppressive microenvironment, offering a novel integrated approach for the early diagnosis and chemoimmunotherapy of pancreatic cancer.