In vivo imaging of cannabinoid type 2 receptors, functional and structural alterations in mouse model of cerebral ischemia by PET and MRI

Background and purpose: Brain ischemia is one of the most important pathologies of the central nervous system. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and follow alterations of receptor expression and metabolism in ischemic stroke. The aim of this study was to assess the cannabinoid type 2 receptors (CB2R) levels in transient middle cerebral artery occlusion (tMCAO) mouse models at subacute stage using positron emission tomography (PET) with our novel tracer [18F]RoSMA-18-d6, and structural imaging by magnetic resonance imaging (MRI). Methods: Our recently developed CB2R PET tracer [18F]RoSMA-18-d6 was used for imaging the neuroinflammation at 24 h after reperfusion in tMCAO mice. The RNA expression levels of CB2R and other inflammatory markers were analyzed by quantitative real-time polymerase chain reaction using brain tissues from tMCAO (1 h occlusion) and sham-operated mice. [18F]fluorodeoxyglucose (FDG) was included for evaluation of the cerebral metabolic rate of glucose (CMRglc). In addition, diffusion-weighted imaging an T2- weighted imaging were performed for anatomical reference and for delineating the lesion in tMCAO mice. Results: mRNA expressions of inflammatory markers TNF-a, Iba1, MMP9 and GFAP, CNR2 were increased at 24 h after reperfusion in the ipsilateral compared to contralateral hemisphere of tMCAO mice, while mRNA expression of the neuronal marker MAP-2 was markedly reduced. Reduced [18F]FDG uptake was observed in the ischemic striatum of tMCAO mouse brain at 24 h after reperfusion. Although higher activity of [18F]RoSMA-18-d6 in ex-vivo biodistribution studies and higher standard uptake value ratio (SUVR) were detected in the ischemic ipsilateral compared to contralateral striatum in tMCAO mice, the in-vivo specificity of [18F]RoSMA-18-d6 was confirmed only in the CB2R-rich spleen. Conclusions: This study revealed an increased [18F]RoSMA-18-d6 measure of CB2R and a reduced [18F]FDG measure of CMRglc in ischemic striatum of tMCAO mice at subacute stage. [18F]RoSMA-18-d6 might be a promising PET tracer for detecting CB2R alterations in animal models of neuroinflammation without neuronal loss.

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In vivo Imaging of Cannabinoid Type 2 Receptors: Functional and Structural Alterations in Mouse Model of Cerebral Ischemia by PET and MRI

Molecular Imaging and Biology ◽

10.1007/s11307-021-01655-4 ◽

2021 ◽

Author(s):

Ruiqing Ni ◽

Adrienne Müller Herde ◽

Ahmed Haider ◽

Claudia Keller ◽

Georgios Louloudis ◽

...

Keyword(s):

Inflammatory Markers ◽

Temporal Dynamics ◽

Ex Vivo ◽

Receptor Expression ◽

Neuronal Marker ◽

Subacute Stage ◽

Pet Tracer ◽

Biodistribution Studies

Abstract Purpose Stroke is one of the most prevalent vascular diseases. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and follow alterations of receptor expression and metabolism in ischemic stroke. The aim of this study was to assess the cannabinoid type 2 receptor (CB2R) levels in transient middle cerebral artery occlusion (tMCAO) mouse models at subacute stage using positron emission tomography (PET) with our novel tracer [18F]RoSMA-18-d6 and structural imaging by magnetic resonance imaging (MRI). Procedures Our recently developed CB2R PET tracer [18F]RoSMA-18-d6 was used for imaging neuroinflammation at 24 h after reperfusion in tMCAO mice. The RNA expression levels of CB2R and other inflammatory markers were analyzed by quantitative real-time polymerase chain reaction using brain tissues from tMCAO (1 h occlusion) and sham-operated mice. [18F]fluorodeoxyglucose (FDG) was included for evaluation of the cerebral metabolic rate of glucose (CMRglc). In addition, diffusion-weighted imaging and T2-weighted imaging were performed for anatomical reference and delineating the lesion in tMCAO mice. Results mRNA expressions of inflammatory markers TNF-α, Iba1, MMP9 and GFAP, CNR2 were increased to 1.3–2.5 fold at 24 h after reperfusion in the ipsilateral compared to contralateral hemisphere of tMCAO mice, while mRNA expression of the neuronal marker MAP-2 was markedly reduced to ca. 50 %. Reduced [18F]FDG uptake was observed in the ischemic striatum of tMCAO mouse brain at 24 h after reperfusion. Although higher activity of [18F]RoSMA-18-d6 in ex vivo biodistribution studies and higher standard uptake value ratio (SUVR) were detected in the ischemic ipsilateral compared to contralateral striatum in tMCAO mice, the in vivo specificity of [18F]RoSMA-18-d6 was confirmed only in the CB2R-rich spleen. Conclusions This study revealed an increased [18F]RoSMA-18-d6 measure of CB2R and a reduced [18F]FDG measure of CMRglc in the ischemic striatum of tMCAO mice at subacute stage. [18F]RoSMA-18-d6 might be a promising PET tracer for detecting CB2R alterations in animal models of neuroinflammation without neuronal loss.

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In Vivo Imaging of Cannabinoid Type 2 Receptors, Functional and Structural Alterations in Mouse Model of Cerebral Ischemia by PET and MRI

10.21203/rs.3.rs-508089/v1 ◽

2021 ◽

Author(s):

Ruiqing Ni ◽

Adrienne Müller Herde ◽

Ahmed Haider ◽

Claudia Keller ◽

Georgios Louloudis ◽

...

Keyword(s):

Inflammatory Markers ◽

Temporal Dynamics ◽

Ex Vivo ◽

Receptor Expression ◽

Neuronal Marker ◽

Subacute Stage ◽

Pet Tracer ◽

Biodistribution Studies

Abstract Background and purposeBrain ischemia is one of the most important pathologies of the central nervous system. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and follow alterations of receptor expression and metabolism in ischemic stroke. The aim of this study was to assess the cannabinoid type 2 receptors (CB2R) levels in transient middle cerebral artery occlusion (tMCAO) mouse models at subacute stage using positron emission tomography (PET) with our novel tracer [18F]RoSMA-18-d6, and structural imaging by magnetic resonance imaging (MRI). MethodsOur recently developed CB2R PET tracer [18F]RoSMA-18-d6 was used for imaging the neuroinflammation at 24 h after reperfusion in tMCAO mice. The RNA expression levels of CB2R and other inflammatory markers were analyzed by quantitative real-time polymerase chain reaction using brain tissues from tMCAO (1 h occlusion) and sham-operated mice. [18F]fluorodeoxyglucose (FDG) was included for evaluation of the cerebral metabolic rate of glucose (CMRglc). In addition, diffusion-weighted imaging and T2-weighted imaging were performed for anatomical reference and delineating the lesion in tMCAO mice. ResultsmRNA expressions of inflammatory markers TNF-a, Iba1, MMP9 and GFAP, CNR2 were increased at 24 h after reperfusion in the ipsilateral compared to contralateral hemisphere of tMCAO mice, while mRNA expression of the neuronal marker MAP-2 was markedly reduced. Reduced [18F]FDG uptake was observed in the ischemic striatum of tMCAO mouse brain at 24 h after reperfusion. Although higher activity of [18F]RoSMA-18-d6 in ex-vivo biodistribution studies and higher standard uptake value ratio (SUVR) were detected in the ischemic ipsilateral compared to contralateral striatum in tMCAO mice, the in-vivo specificity of [18F]RoSMA-18-d6 was confirmed only in the CB2R-rich spleen. ConclusionsThis study revealed an increased [18F]RoSMA-18-d6 measure of CB2R and a reduced [18F]FDG measure of CMRglc in ischemic striatum of tMCAO mice at subacute stage. [18F]RoSMA-18-d6 might be a promising PET tracer for detecting CB2R alterations in animal models of neuroinflammation without neuronal loss.

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PET imaging of cannabinoid type 2 receptors with [11C]A-836339 did not evidence changes following neuroinflammation in rats

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x16685105 ◽

2017 ◽

Vol 37 (3) ◽

pp. 1163-1178 ◽

Cited By ~ 14

Author(s):

Geraldine Pottier ◽

Vanessa Gómez-Vallejo ◽

Daniel Padro ◽

Raphaël Boisgard ◽

Frédéric Dollé ◽

...

Keyword(s):

Cerebral Ischemia ◽

Pet Imaging ◽

Receptor Expression ◽

Brain Inflammation ◽

Cb2 Receptor ◽

Future Studies ◽

Positron Emission

Cannabinoid type 2 receptors (CB2R) have emerged as promising targets for the diagnosis and therapy of brain pathologies. However, no suitable radiotracers for accurate CB2R mapping have been found to date, limiting the investigation of the CB2 receptor expression using positron emission tomography (PET) imaging. In this work, we report the evaluation of the in vivo expression of CB2R with [11C]A-836339 PET after cerebral ischemia and in two rat models of neuroinflammation, first by intrastriatal LPS and then by AMPA injection. PET images and in vitro autoradiography showed a lack of specific [11C]A-836339 uptake in these animal models demonstrating the limitation of this radiotracer to image CB2 receptor under neuroinflammatory conditions. Further, using immunohistochemistry, the CB2 receptor displayed a modest expression increase after cerebral ischemia, LPS and AMPA models. Finally, [18F]DPA-714-PET and immunohistochemistry demonstrated decreased neuroinflammation by a selective CB2R agonist, JWH133. Taken together, these findings suggest that [11C]A-836339 is not a suitable radiotracer to monitor in vivo CB2R expression by using PET imaging. Future studies will have to investigate alternative radiotracers that could provide an accurate binding to CB2 receptors following brain inflammation.

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Upregulation of angiotensin II type 2 receptor expression in estrogen-induced pituitary hyperplasia

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00477.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. E786-E794 ◽

Cited By ~ 10

Author(s):

Cecilia Suarez ◽

Graciela Díaz-Torga ◽

Arturo González-Iglesias ◽

Carolina Cristina ◽

Damasia Becu-Villalobos

Keyword(s):

Angiotensin Ii ◽

Receptor Expression ◽

Receptor Subtype ◽

At2 Receptor ◽

Ang Ii ◽

Pituitary Hyperplasia ◽

Releasing Effect ◽

At2 Receptors

Recent evidence shows that reexpression and upregulation of angiotensin II (ANG II) type 2 (AT2) receptor in adult tissues occur during pathological conditions such as tissue hyperplasia, inflammation, and remodeling. In particular, expression of functional AT2 receptors in the pituitary and their physiological significance and regulation have not been described. In this study, we demonstrate that chronic in vivo estrogen treatment, which induces pituitary hyperplasia, enhances local AT2 expression (measured by Western blot and RT-PCR) concomitantly with downregulation of ANG II type 1 (AT1) receptors. In vivo progesterone treatment of estrogen-induced pituitary hyperplasia did not modify either the ANG II receptor subtype expression pattern or octapeptide-induced and AT1-mediated calcium signaling. Nevertheless, an unexpected potentiation of the ANG II prolactin-releasing effect was observed in this group, and this response was sensitive to both AT1 and AT2 receptor antagonists. These data are the first to document that ANG II can act at the pituitary level through the AT2 receptor subtype and that estrogens display a differential regulation of AT1 and AT2 receptors at this level.

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P04.26 In vitro and in vivo evaluation of the LAT1 PET tracer 2-[18F]FELP in comparison to [18F]FET and [18F]FDG

Neuro-Oncology ◽

10.1093/neuonc/nox036.166 ◽

2017 ◽

Vol 19 (suppl_3) ◽

pp. iii46-iii46 ◽

Cited By ~ 1

Author(s):

J. Verhoeven ◽

J. Bolcaen ◽

K. Kersemans ◽

V. De Meulenaere ◽

K. Deblaere ◽

...

Keyword(s):

In Vivo Evaluation ◽

Pet Tracer ◽

18F Fdg

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Detection of Canonical Hedgehog Signaling in Breast Cancer by 131-Iodine-Labeled Derivatives of the Sonic Hedgehog Protein

Journal of Biomedicine and Biotechnology ◽

10.1155/2012/639562 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 8

Author(s):

Jennifer Sims-Mourtada ◽

David Yang ◽

Izabela Tworowska ◽

Richard Larson ◽

Daniel Smith ◽

...

Keyword(s):

Receptor Binding ◽

Hedgehog Signaling ◽

Receptor Expression ◽

Biodistribution Studies ◽

Pathway Activation ◽

Signaling Inhibitors ◽

Gastrointestinal Tissue ◽

Hh Signaling ◽

Significant Uptake

Activation of hedgehog (HH) pathway signaling is observed in many tumors. Due to a feedback loop, the HH receptor Patched (PTCH-1) is overexpressed in tumors with activated HH signaling. Therefore, we sought to radiolabel the PTCH-1 ligand sonic (SHH) for detection of cancer cells with canonical HH activity. Receptor binding of131I-SHH was increased in cell lines with high HH pathway activation. Our findings also show that PTCH-1 receptor expression is decreased upon treatment with HH signaling inhibitors, and receptor binding of131I-SHH is significantly decreased following treatment with cyclopamine.In vivoimaging and biodistribution studies revealed significant accumulation of131I-SHH within tumor tissue as compared to normal organs. Tumor-to-muscle ratios were approximately 8 : 1 at 5 hours, while tumor to blood and tumor to bone were 2 : 1 and 5 : 1, respectively. Significant uptake was also observed in liver and gastrointestinal tissue. These studies show that131I-SHH is capable ofin vivodetection of breast tumors with high HH signaling. We further demonstrate that the hedgehog receptor PTCH-1 is downregulated upon treatment with hedgehog inhibitors. Our data suggests that radiolabeled SHH derivatives may provide a method to determine response to SHH-targeted therapies.

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Development and validation of an immuno-PET tracer for patient stratification and therapy monitoring of antibody-drug conjugate therapy.

Journal of Clinical Oncology ◽

10.1200/jco.2013.31.15_suppl.11006 ◽

2013 ◽

Vol 31 (15_suppl) ◽

pp. 11006-11006

Author(s):

Ohad Ilovich ◽

Arutselvan Natarajan ◽

Ataya Sathirachinda ◽

Richard Kimura ◽

Ananth Srinivasan ◽

...

Keyword(s):

Therapy Monitoring ◽

Small Animal Pet ◽

Patient Stratification ◽

Phase I Clinical Trials ◽

Serum Stability ◽

Pet Tracer ◽

Biodistribution Studies ◽

Companion Diagnostic ◽

Antibody Drug

11006 Background: SAR566658 is an antibody-drug immunoconjugate consisting of a humanized monoclonal antibody (huDS6) against the tumor-associated MUC1-sialoglycotope, CA6, conjugated to a cytotoxic maytansinoid (DM4). SAR566658 is currently undergoing phase I clinical trials in patients with CA6-positive solid tumors. A companion diagnostic based on huDS6 may facilitate patient stratification and early evaluation of therapeutic efficacy. The present study describes the development and preclinical evaluation of three novel Copper-64 (t½= 12.7h) labeled antibody fragments (two Fabs and a diabody) derived from the huDS6 antibody. One fragment was chosen based on imaging figures of merit for further specificity evaluations. Methods: The affinity of all fragments and their DOTA conjugates to CA6 was validated using flow cytometry. The DOTA conjugates were labeled with Copper-64 and evaluated in human serum stability studies, in vivo small animal PET imaging and 24-hour biodistribution studies in nude mice bearing either CA6 positive (WISH) or CA6 negative (A2780) subcutaneous tumors. The specificity of the lead tracer was evaluated in vivo via blocking studies and isotype controls. Results: All fragments and their DOTA conjugates had high affinity (Kd = 4-20 nM) for WISH cells. 64Cu-DOTA-B-Fab gave superior results in radio-synthesis (RCY - 60%, SA - 55 GBq/µmole, >99% purity), serum stability (94±5%, n=3) and biodistribution profile. Its two isotype controls gave statistically significant (P<0.05) uptake values in WISH but not A2780 tumors (see table). Blocking with B-Fab or huDS6 prior to tracer administration afforded a 23% (p<0.05, n=8) and 26% (p<0.05, n=7) decrease in WISH tumor uptake, respectively. Conclusions: These preclinical studies suggest that 64Cu-DOTA-B-Fab may be a suitable companion diagnostic for SAR566658 in cancer patients and requires further investigation.[Table: see text]

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[18f]-(2S,4R)-4-Fluoroglutamine As a New Positron Emission Tomography Tracer in Multiple Myeloma

Blood ◽

10.1182/blood-2019-127935 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5542-5542

Author(s):

Nicola Giuliani ◽

Silvia Valtorta ◽

Martina Chiu ◽

Denise Toscani ◽

Andrea Sartori ◽

...

Keyword(s):

Positron Emission Tomography ◽

Multiple Myeloma ◽

Fdg Pet ◽

Emission Tomography ◽

Extramedullary Disease ◽

Pet Tracer ◽

Positron Emission ◽

18F Fdg ◽

Pet Scans

High glycolitic activity of multiple myeloma (MM) cells is the rationale for the use of Positron Emission Tomography (PET) with 18F-fluorodeoxyglucose ([18F]FDG) to detect both medullary and extramedullary disease. However, FDG-PET has some limitations, since there is a good portion of MM patients who are false-negative. Besides enhanced glycolysis, glutamine (Gln) addiction has been recently described as a metabolic feature of MM by our group. To sustain high Gln demand, MM cells increase the expression of several Gln transporters (ASCT2, SNAT1, LAT1) and are endowed with fast Gln uptake. Yet, at variance with other Gln-addicted cancers, the possible exploitation of Gln as a PET tracer in MM has never been assessed and was investigated in this study. To this purpose, we have firstly synthesized enantiopure (2S,4R)-4-Fluoroglutamine (4-FGln) and validated it as a Gln analogue in human MM cell lines (RPMI8226 and JJN3) comparing its uptake with that of 3H-labelled Gln. The intracellular levels of 4-FGln were determined by HPLC-MS/MS employing a HILIC gradient separation and multiple reaction monitoring (MRM) detection. Both Gln and 4-FGln were actively accumulated by MM cells and exhibited a strong reciprocal competition, pointing to shared transporters. Inhibition analysis revealed that ASCT2 was the major entry route of both compounds, with minor contributions from the other transporters. However, compared with Gln, 4-FGln exhibited higher affinity for both ASCT2 and LAT1 transporters. On the basis of these results, we then tested [18F]4-FGln uptake for MM detection by Positron Emission Tomography (PET) in two different in vivo murine models. Firstly, to investigate sensitivity of human MM to [18F]4-FGln in vivo, JJN3 cells were subcutaneously injected in immunodeficient NSG mice In this xenograft model, [18F]4-FGln- and[18F]FDG-PET scans were performed after plasmacytomas became palpable and repeated after one week. All the tumours were positive for [18F]FDG and displayed [18F]4-FGln uptake with Standard Uptake Values (SUV) of 1.21±1.9 and 0.99±0.07 after 2 weeks, respectively. Thereafter, the effect of bortezomib (BOR) was investigated to evaluate the potential use of [18F]4-FGln to monitor anti-MM treatment. Ten NGS mice were injected with JJN3 cells and, after 14 days, treated twice weekly with BOR, 1mg/kg, or vehicle for two weeks. PET scans were performed before and after 5 and 12 days of BOR treatment. As expected, BOR reduced tumour size as compared to vehicle. At the first post-BOR PET scan, [18F]4-FGln (SUV mean: pre 0.85±0.31; post 0.45±0.10, P<0.05), but not [18F]FDG (SUV mean: pre 0.97±0.38, post 0.75±0.14) was already significantly reduced: [18F]FDG and [18F]4-FGln uptake was reduced of 22 and 45% respectively. With both radiotracers, BOR treated animals displayed SUV mean values significantly lower than those of vehicle treated animals at post treatment PET (SUV means [18F ]FDG: BOR 0.75±0.14; vehicle 1.27±0.34, P<0.05; SUV mean [18F]4-FGln: BOR 0.45±0.10 ; vehicle: 0.73±0.18 ; P <0.05). Thereafter, to mimic BOR-resistant MM in a syngeneic mouse model, C57BL/6 mice were injected intravenously with Vk12598 cells obtained from transgenic Vk*MYC mice repeatedly treated with sub-optimal doses of BOR. Upon injection into C57BL/6 mice, Vk12598 cells colonize the BM without lytic lesions and extensively colonize the spleen generating an aggressive MM that brings animals to death within five weeks. PET scans were performed with [18F]4-FGln and [18F]FDG before Vk*MYC MM cells injection and after three, four and five weeks. Blood samples for M-spike evaluation were obtained in parallel. Four weeks after MM cells injection a significant increase of both [18F]4-FGln and [18F]FDG uptake was detected in spleens (SUV mean: 1.14±0.23, P=0.018; 0.94±0.24, P= 0.005). In both MM models, the volume of distribution of [18F]4-F-Gln did not overlap that of [18F]FDG. In conclusion, our data indicate that [18F]-(2S,4R)-4-Fluoroglutamine is a new potential PET tracer in pre-clinical MM models especially of extramedullary disease, either in a BOR-sensitive or in a BOR-resistant context, supporting the exploitation of Gln addiction for diagnostic purposes in MM patients. Disclosures Giuliani: Janssen: Research Funding.

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One-Pot Radiosynthesis and Biological Evaluation of a Caspase-3 Selective 5-[123,125I]iodo-1,2,3-triazole derived Isatin SPECT Tracer

Scientific Reports ◽

10.1038/s41598-019-55992-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 3

Author(s):

Matthias Glaser ◽

Vineeth Rajkumar ◽

Seckou Diocou ◽

Thibault Gendron ◽

Ran Yan ◽

...

Keyword(s):

Caspase 3 ◽

Clinical Decision Making ◽

Cycloaddition Reaction ◽

Xenograft Model ◽

Biological Evaluation ◽

One Pot ◽

Tumour Uptake ◽

Pet Tracer ◽

Biodistribution Studies

AbstractInduction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [18F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (123,125I) was achieved in 55 ± 12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [18F]ICMT11 (Ki = 6.1 ± 0.9 nM and 12.4 ± 4.7 nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.

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