A Functional Chemiluminescent Probe for in Vivo Imaging of Natural Killer Cell Activity Against Tumours

Area of Science:

• Immunology
• Biotechnology
• Medical Imaging

Background:

• Natural killer (NK) cells are crucial for cancer immunotherapy due to their cytotoxic capabilities against malignant cells.
• Current methods for validating NK cell anti-tumour activity in vivo are limited, hindering the advancement of adoptive NK cell therapies.
• Accurate assessment of NK cell function in live subjects is essential for optimizing treatment strategies.

Purpose of the Study:

• To develop and validate a novel chemiluminescent probe for in situ imaging of granzyme B-mediated NK cell killing activity.
• To assess the probe's selectivity and sensitivity compared to existing imaging agents.
• To demonstrate the probe's utility for in vivo imaging of NK cell activity in relevant preclinical cancer models.

Main Methods:

• Design and optimization of a granzyme B-specific chemiluminescent probe utilizing an activatable phenoxydioxetane reporter.
• Evaluation of probe selectivity against various proteases and comparison of signal-to-noise ratios with commercial fluorophores.
• In vivo imaging studies in mouse models to detect NK cell activity against tumors.

Main Results:

• The developed probe exhibits high specificity for active granzyme B, with minimal cross-reactivity with other proteases.
• The chemiluminescent probe provides superior signal-to-noise ratios compared to conventional fluorescent reporters.
• Successful in vivo imaging of NK cell-mediated killing activity within live tumors in mouse models was achieved.

Conclusions:

• The novel chemiluminescent probe enables direct, real-time visualization of granzyme B-dependent NK cell cytotoxicity in vivo.
• This represents the first chemiluminescent imaging tool for assessing NK cell activity in live tumors.
• The probe is a valuable tool for validating NK cell-based immunotherapies and advancing cancer treatment research.