PET Tracers for Imaging ROS Activity

点击翻译按钮获取中文摘要

TR&D 3 Project Summary Reactive oxygen species (ROS) regulate critical physiological functions. However, the imbalance in production/mitigation of ROS also mediates pathogenesis of numerous diseases ranging from cardiovascular sciences to oncology clinic. Through the current funding cycle of TR&D3 program, we have identified a lead PET tracer (described herein as {68Ga}Galuminox) for imaging systemic inflammation and demonstrate its ability to monitor LPS-induced inflammation within lungs (acute lung injury model), monitor β3 integrin-mediated chemoresistance in breast cancer bone metastases, and kidney injury in nephrotic syndrome model. Importantly, Galuminox provides a sensitive readout of mitochondrial ROS (mROS) in human cells. Combined data indicate make {68Ga}Galuminox a worthy candidate of its advancement for regulatory approvals to evaluate safety through human dosimetry studies. Given its desirable trait to serve as a redox sensitive reporter probe, Galuminox also provides a template scaffold for generation and validation of copper-64 or fluorine-18 counterparts (with shorter positron range) as alternative PET tracers. Unfortunately, Galuminox analogues would not penetrate blood brain barrier (BBB) thus limiting their utility for assessing ROS mediated systemic inflammation. To achieve functional imaging of mROS within the brain, we have rationally designed small heterocyclic molecule ({18F}SLN128). Like Galuminox, SLN-128 is a highly fluorescent probe thus allowing opportunities for dual optical-PET readout for its biochemical validations. Compared with Galuminox which detects superoxide and hydrogen peroxide, SLN128 detects superoxide and hydroxyl radical. Given that both radiotracers have two different PET radionuclides and offer different detection capabilities, we anticipate that both PET molecular imaging probes could provide complementary information of oxidative imbalance mediating pathogenesis of both non-CNS and CNS diseases. Specific aims of TRD3 renewal are: Aim 1: Evaluate safety of {68Ga}Galuminox through human dosimetry studies following regulatory approvals. Aim 1.1: Evaluate the performance of {68Ga}Galuminox for imaging inflammation using rodent models of ischemic- and bacterial exotoxin-induced acute lung injury as well as other models of oxidative stress acute respiratory distress syndrome (ADRS), cystathionine γ-lyase (CSE) -mediated ischemic vascular remodeling, and meningeal ROS in MS through the Collaborative Projects. Aim1.2: To compensate for higher positron range of gallium-68 in Galuminox and allow options for delayed imaging in gastrointestinal tract, we propose to synthesize, biochemically characterize Cu-64 and F-18 counterparts of Galuminox and evaluate their pharmacokinetic profiles in diseased rodent models. Aim 1.3: As an exploratory aim, we also propose to design and develop small organic heterocyclic molecules for assessment of mROS prevalent in pathogenesis of neurodegenerative diseases. These products and those developed in the current grant cycle will be provided to our Service Projects as well.