posted on 2020-03-31, 19:45authored byShasha He, Jingchao Li, Yan Lyu, Jiaguo Huang, Kanyi Pu
Real-time
imaging of immunoactivation is imperative for cancer
immunotherapy and drug discovery; however, most existing imaging agents
possess “always-on” signals and thus have poor signal
correlation with immune responses. Herein, renal-clearable near-infrared
(NIR) fluorescent macromolecular reporters are synthesized to specifically
detect an immunoactivation-related biomarker (granzyme B) for real-time
evaluation of cancer immunotherapy. Composed of a peptide-caged NIR
signaling moiety linked with a hydrophilic poly(ethylene glycol) (PEG)
passivation chain, the reporters not only specifically activate their
fluorescence by granzyme B but also passively target the tumor of
living mice after systemic administration. Such granzyme B induced in vivo signals of the reporters are validated to correlate
well with the populations of cytotoxic T lymphocytes (CD8+) and T helper (CD4+) cells detected in tumor tissues.
By virtue of their ideal renal clearance efficiency (60% injected
doses at 24 h postinjection), the reporters can be used for optical
urinalysis of immunoactivation simply by detecting the status of excreted
reporters. This study thus proposes a molecular optical imaging approach
for noninvasive evaluation of cancer immunotherapeutic efficacy in
living animals.