BODIPY-Based NO Probe for Macrophage-Targeted Immunotherapy Response Monitoring

Abstract

Precise and rapid detection of immune responses is critical for timely therapeutic regimen adjustment. Immunomodulation of tumor-associated macrophages (TAMs) from a protumorigenic phenotype (M2) to an antitumorigenic phenotype (M1) is crucial in macrophage-targeted immunotherapy. Herein, we developed a boron dipyrromethene (BODIPY)-based fluorescence probe BDP3 to detect the immune responses after immunotherapy by monitoring the nitric oxide (NO) released by M1 TAMs. With an aromatic primary monoamine structure and a p-methoxyanilin electron donor in the meso-position, BDP3 not only specifically activates stable and sensitive fluorescence by NO via a photoinduced electron transfer (PET) process but also achieves a long emission wavelength for efficient in vitro and in vivo imaging. Such NO-induced fluorescence signals of BDP3 are validated to correlate well with the phenotypes of TAMs detected in macrophage cell lines and tumor tissues. The distinct sensing effects toward two types of clinically used immunotherapeutic drugs further confirm the ability of BDP3 for specific monitoring of the M1/M2 switch in response to the macrophage-targeted immunotherapy. By virtue of good biocompatibility and appropriate tumor retention time, BDP3 could be a potential fluorescent probe for noninvasive evaluation of the immunotherapeutic efficacy of macrophage-targeted immunotherapy in living animals.

A Mitochondria-Targeted Nitric Oxide Probe for Multimodality Imaging of Macrophage Immune Responses

“…Activation of the macrophage colony-stimulating factor 1 receptor (CSF1R) is the driving signal for M2 polarization. The literature has proved that blocking by SF1/CSF1R can reduce the number of TAMs, reprogram the remaining TAMs, and deflect the polarization of macrophages. − On the contrary, a particular concentration of clodronate liposomes (CL) induces macrophages to enter the apoptosis process, thus achieving the function of eliminating macrophages. − With the support of the above experiments, the multitarget CSF-1R Kit (c-Kit), and FLT3 receptor tyrosine kinase inhibitor Pexidartinib (PLX3397), which has a good M2–M1 transformation effect, was used as immunomodulators, with LPS as a positive control pro-inflammatory factor to verify Ir-ImNO in vivo to monitor the immune response status of macrophages. − Moreover, the hemolysis effect of Ir-ImNO was characterized before further animal experiments. As shown in Figure S23, although the concentration of Ir-ImNO is up to 30 μM, there is no significant hemolysis, proving that Ir-ImNO has good biocompatibility and can be used for in vivo applications.…”

Recent Advances in the Development of Non‐Invasive Imaging Probes for Cancer Immunotherapy

“…[164][165] Recently, fluorescent NO probes have been developed to detect the immune response of the tumor-associated macrophage-targeted ITP agents. [166] Despite multiple reports on the OI probes with promising preclinical results, translation to the clinical settings faces some major hurdles including issues with light scattering, tissue penetration, and image contrast. Therefore, the generation of a new chemical toolbox combined with advanced engineering technologies and instrumentation can help advance these platforms through the clinic.…”

“…For example, secretion of nitrogen oxide (NO) is considered to be a hallmark of tumor‐inhibiting M1‐polarized macrophages [164–165] . Recently, fluorescent NO probes have been developed to detect the immune response of the tumor‐associated macrophage‐targeted ITP agents [166] …”

Organic fluorophore-based fluorescent probes for abnormal immune response diagnosis and treatment evaluation

“…In 2020 and 2023, Ashish Kulkarni and Gao et al designed probes NO-NR and BDP3 for monitoring NO in M1 based on different fluorescent organic structures. 77,78 A hydrophobic amphiphile, iCSF1R, occupies the spaces between the lipid bilayer along with the NO imaging probe (DAF-2-DA), thereby constituting an immunotheranostic system, iCSF1R-NO-NR. The most significant enhancement of the fluorescence signal was observed in the iCSF1R-NO-NR group in a mouse 4T1 breast cancer model.…”