Dataset Information

A radioligand for in vitro autoradiography of CSF1R in post-mortem CNS tissues.

ABSTRACT:

Background

Reactive microglia and recruited peripheral macrophages contribute to the pathogenesis of Alzheimer's dementia (AD). Monocytes, macrophages and microglia all express the marker colony-stimulating factor 1 receptor (CSF1R). 4-Cyano-N-(4-(4-methylpiperazin-1-yl)-2-(4-methylpiperidin-1-yl)phenyl)-1H-pyrrole-2-carboxamide (1) is a high-affinity antagonist for CSF1R. We report the radiosynthesis of both [³H]1 and [¹¹C]1. The PET imaging properties of [¹¹C]1 in mice and baboon were investigated. [³H]1 was studied in B_max measurement in post-mortem autoradiography in the frontal cortex, inferior parietal cortex and hippocampus from donors diagnosed with AD and age-matched controls. In vitro binding affinity of 1 was measured commercially. Nor-methyl-1 precursor was radiolabeled with [¹¹C]iodomethane or [³H]iodomethane to produce [¹¹C]1 and [³H]1, respectively. Ex vivo brain biodistribution of [¹¹C]1 was compared in normal mice versus lipopolysaccharide-administered (LPS) murine model of neuroinflammation. Dynamic PET imaging was performed in a healthy male Papio anubis baboon. Post-mortem autoradiography with [³H]1 was performed in frozen sections using a standard saturation binding technique.

Results

Compound 1 exhibits a high in vitro CSF1R binding affinity (0.59 nM). [¹¹C]1 was synthesized with high yield. [³H]1 was synthesized similarly (commercially). Biodistribution of [¹¹C]1 in healthy mice demonstrated moderate brain uptake. In LPS-treated mice the brain uptake of [¹¹C]1 was ~ 50% specific for CSF1R. PET/CT [¹¹C]1 study in baboon revealed low brain uptake (0.36 SUV) of [¹¹C]1. Autoradiography with [³H]1 gave significantly elevated B_max values in AD frontal cortex versus control (47.78 ± 26.80 fmol/mg vs. 12.80 ± 5.30 fmol/mg, respectively, P = 0.023) and elevated, but not significantly different binding in AD hippocampus grey matter and inferior parietal cortex (IPC) white matter.

Conclusions

Compound 1 exhibits a high in vitro CSF1R binding affinity. [¹¹C]1 specifically labels CSF1R in the mouse neuroinflammation, but lacks the ability to efficiently cross the blood-brain barrier in baboon PET. [³H]1 specifically labels CSF1R in post-mortem human brain. The binding of [³H]1 is significantly higher in the post-mortem frontal cortex of AD versus control subjects.

SUBMITTER: Foss CA

PROVIDER: S-EPMC11347546 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature

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Publications

A radioligand for in vitro autoradiography of CSF1R in post-mortem CNS tissues.

Foss Catherine A CA Naik Ravi R Das Deepankar D Cha Hyojin H Minn Il I Hall Andrew A Finley Paige P Wu Sophia Jiang SJ Du Yong Y Dannals Robert F RF Pomper Martin G MG Horti Andrew G AG

EJNMMI research 20240826 1

<h4>Background</h4>Reactive microglia and recruited peripheral macrophages contribute to the pathogenesis of Alzheimer's dementia (AD). Monocytes, macrophages and microglia all express the marker colony-stimulating factor 1 receptor (CSF1R). 4-Cyano-N-(4-(4-methylpiperazin-1-yl)-2-(4-methylpiperidin-1-yl)phenyl)-1H-pyrrole-2-carboxamide (1) is a high-affinity antagonist for CSF1R. We report the radiosynthesis of both [<sup>3</sup>H]1 and [<sup>11</sup>C]1. The PET imaging properties of [<sup>11< ...[more]

PMID: 39186197

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Project description:BackgroundRecovering high quality intact RNA from post-mortem tissue is of major concern for gene expression studies in animals and humans. Since the availability of post-mortem tissue is often associated with substantial delay, it is important that we understand the temporal variation in the stability of total RNA and of individual gene transcripts so as to be able to appropriately interpret the data generated from such studies. Hence, the objective of this experiment was to qualitatively and quantitatively assess the integrity of total and messenger RNA extracted from bovine skeletal muscle, subcutaneous adipose tissue and liver stored at 4 degrees C at a range of time points up to 22 days post-mortem. These conditions were designed to mimic the environment prevailing during the transport of beef from the abattoir to retail outlets.ResultsThe 28S and 18S rRNA molecules of total RNA were intact for up to 24 h post-mortem in liver and adipose tissues and up to 8 days post-mortem in skeletal muscle. The mRNA of housekeeping genes (GAPDH and ACTB) and two diet-related genes (RBP5 and SCD) were detectable up to 22 days post-mortem in skeletal muscle. While the mRNA stability of the two housekeeping genes was different in skeletal muscle and liver, they were similar to each other in adipose tissue. After 22 days post-mortem, the relative abundance of RBP5 gene was increased in skeletal muscle and in adipose tissue and decreased in liver. During this period, the relative abundance of SCD gene also increased in skeletal muscle whereas it decreased in both adipose tissue and liver.ConclusionStability of RNA in three tissues (skeletal muscle, subcutaneous adipose tissue and liver) subjected to long-term post-mortem storage at refrigeration temperature indicated that skeletal muscle can be a suitable tissue for recovering biologically useful RNA for gene expression studies even if the tissue is subjected to post-mortem storage for weeks, whereas adipose tissue and liver should be processed within 24 hours post-mortem.

Dataset Information

A radioligand for in vitro autoradiography of CSF1R in post-mortem CNS tissues.

Background

Results

Conclusions

Publications

A radioligand for in vitro autoradiography of CSF1R in post-mortem CNS tissues.

Similar Datasets

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