Biology subjects

Srinivasarao, M.

Publications and source records attributed to Srinivasarao, M..

4 recordsLinked to original sources

bioRxiv2025

Targeting Macrophage Folate Receptor-β for Diagnosis and Treatment of Autoimmune Myocarditis

We investigated folate receptor-{beta} (FR-{beta}) expressed on activated macrophages as a therapeutic and imaging target in autoimmune myocarditis (AIM). Treatment with a folate-aminopterin conjugate (EC2319) targeting FR-{beta}-positive macrophages significantly reduced macrophage infiltration compared to saline (5.23 {+/-} 2.84% vs. 1.24 {+/-} 0.66%, P < 0.001) in rat experimental AIM. After immunization, FR-{beta} targeting positron emission tomography (PET) tracer [18F]FOL detected myocardial inflammatory lesions and revealed reduction in inflammation following EC2319 treatment relative to saline or tumor necrosis factor-alpha inhibitor Etanercept [standardized uptake value (SUV) 1.07 {+/-} 0.22 vs. 2.38 {+/-} 0.90 vs. 2.59 {+/-} 0.56, P < 0.001]. [18F]FOL PET signal correlated with myocardial CD68-positive macrophage content (r = 0.720, P < 0.001). These findings demonstrate that EC2319 attenuates myocardial inflammation in AIM and underscore the pathogenic role of FR-{beta}-positive macrophages. [18F]FOL PET provides a noninvasive means of detecting myocardial inflammatory activity and therapeutic response. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/686077v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@18e9296org.highwire.dtl.DTLVardef@139b8b3org.highwire.dtl.DTLVardef@8d1a74org.highwire.dtl.DTLVardef@1c3f06d_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

Preclinical assessment of Fibroblast Activation Protein-specific MRI as an alternative to PSMA for image-guided focal therapy of prostate cancer

Accurate and precise delineation of gross tumour volumes remains a barrier to radiotherapy dose escalation and boost dosing in the treatment of solid tumours, such as prostate cancer. Magnetic resonance imaging of tumour molecular targets has the power to enable focal dose boosting, particularly when combined with technological advances such as MRI-LINAC. Fibroblast activation protein (FAP) is a transmembrane protein overexpressed in stromal components of >90% of epithelial carcinomas. Herein we compare targeted MRI of gold standard PSMA with FAP in the delineation of orthotopic tumours in a mouse model of prostate cancer. Control (no ligand), FAP and PSMA-targeting iron oxide nanoparticles were prepared with modification of an MRI agent (FerroTrace). Mice with orthotopic LNCaP tumours underwent T2-weighted 3D MRI 24 hours after intravenous injection of contrast agents. FAP and PSMA nanoparticles produced contrast enhancement on MRI when compared to control nanoparticles, which was most pronounced on the tumour periphery. FAP-targeted MRI increased the proportion of tumour contrast enhancing black pixels by 13.37% when compared to PSMA. Furthermore, analysis of changes in R2 values between healthy prostates and LNCaP tumours indicated an increase in contrast enhancing pixels in the tumour border of 15%, when targeting FAP, in contrast to PSMA This study demonstrates preclinical feasibility of PSMA and FAP-targeted MRI which can enable targeted image-guided focal therapy of localized prostate cancer.

bioengineering↗

bioRxiv2020

Radiosynthesis and Preclinical Evaluation of Ga-NOTA-Folate for PET Imaging of Folate Receptor β Positive Macrophages

Folate receptor {beta} (FR-{beta}) is one of the markers expressed on macrophages and a promising target for imaging of inflammation. Here, we report the radiosynthesis and preclinical evaluation of [68Ga]Ga-NOTA-folate (68Ga-FOL). First, we determined the affinity of 68Ga-FOL using human FR-{beta} expressing cells. Then, we studied atherosclerotic mice with 68Ga-FOL and 18F-FDG PET/CT. After sacrifice, the tissues excised were measured with a {gamma}-counter for ex vivo biodistribution. Further, the tracer distribution and co-localization with macrophages in aorta cryosections were studied using autoradiography, hematoxylin-eosin staining and immunostaining with anti-Mac-3 antibody. Specificity of 68Ga-FOL was assessed in a blocking study with excess of folate glucosamine. As a last step, human radiation doses were extrapolated from rat PET data. We were able to produce 68Ga-FOL at high radioactivity concentration, with high molar activity and radiochemical purity. The cell binding studies showed high (5.1 {+/-} 1.1 nM) affinity of 68Ga-FOL to FR-{beta}. The myocardial uptake of 68Ga-FOL (SUV 0.43 {+/-} 0.06) was 20-folds lower compared to 18F-FDG (SUV 10.6 {+/-} 1.8, P = 0.001). The autoradiography and immunohistochemistry of aorta revealed that 68Ga-FOL radioactivity co-localized with Mac-3-positive macrophage-rich atherosclerotic plaques. The plaque-to-healthy vessel wall ratio of 68Ga-FOL (2.44 {+/-} 0.15) was significantly higher than that of 18F-FDG (1.93 {+/-} 0.22, P = 0.005). Blocking studies verified 68Ga-FOL specificity to FR. As estimated from rat data the human effective dose was 0.0105 mSv/MBq. The organ with highest absorbed dose was kidney (0.1420 mSv/MBq). In conclusion, 68Ga-FOL is a promising new FR-{beta}-targeted tracer for imaging macrophage-associated inflammation. TABLE OF CONTENT/ABSTRACT GRAPHIC O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

biochemistry↗

bioRxiv2020

Fluorescence Labeling of Circulating Tumor Cells with Folate Receptor Targeted Molecular Probes for Diffuse In Vivo Flow Cytometry

PurposeWe recently developed a new instrument called diffuse in vivo flow cytometry (DiFC) for enumeration of rare fluorescently-labeled circulating tumor cells (CTCs) in small animals without drawing blood samples. Until now, we have used cell lines that express fluorescent proteins, or were pre-labeled with a fluorescent dye ex-vivo. In this work, we investigated the use of two folate receptor (FR)-targeted fluorescence molecular probes for in vivo labeling of FR+ CTCs for DiFC. MethodsWe used EC-17 and Cy5-PEG-FR fluorescent probes. We studied the affinity of these probes for L1210A and KB cancer cells, both of which over-express FR. We tested the labeling specificity in cells in culture in vitro, in whole blood, and in mice in vivo. We also studied detectability of labeled cells with DiFC. ResultsBoth EC-17 and Cy5-PEG-FR probes had high affinity for FR+ CTCs in cell culture in vitro. However, only EC-17 had sufficient specificity for CTCs in whole blood. EC-17 labeled CTCs were also readily detectable in circulation in mice with DiFC. ConclusionsThis work demonstrates the feasibility of labeling CTCs for DiFC with a cell surface receptor targeted probe, greatly expanding the utility of the method for pre-clinical animal models. Because DiFC uses diffuse light, this method could be also used to enumerate CTCs in larger animal models and potentially even in humans.

bioengineering↗