Fully Automated Synthesis of Novel TSPO PET Imaging Ligand [18F]Fluoroethyltemazepam

Current advances in the structure-activity relationship (SAR) analysis of the old/new 18-kDa translocator protein ligands

The translocator protein 18 kDa (TSPO) is a crucial external mitochondrial protein involved in cholesterol translocation, which is essential for steroid production. As a primary marker of neuroinflammation, TSPO has been implicated in the development and progression of various neurodegenerative and neuropsychiatric disorders. This review highlights the structural diversity of TSPO ligands, many of which have undergone modifications from selective central benzodiazepine receptor (CBR) ligands to enhance their affinity for TSPO. The paper discusses the significant advancements in the design of these ligands, emphasizing their binding efficacy and specificity. Additionally, it provides an update on the progress of several TSPO ligands that have advanced to clinical trials. The review aims to elucidate the structure-activity relationships (SAR) that govern the interaction between TSPO and its ligands, thereby offering insights into the development of new therapeutic agents targeting TSPO for the treatment of neuroinflammatory conditions. Overall, this work provided an update on previous finding and serves as a valuable resource for researchers in the field.

Inhibiting the Proliferation of Colorectal Cancer Cells by Reducing TSPO/VDAC Expression

Background

We aimed to explore the mechanism of the effect of remimazolam (Rem) on the proliferation of colorectal cancer (CRC) cells with CRC as a disease context.

Methods

Translocation protein (TSPO) expression in CRC was determined by Western blotting and qRT-PCR in the Second Affiliated Hospital of Qiqihar Medical University from March 2019 to February 2022. TSPO-interacting proteins were predicted through string database. The proliferation was measured by CCK-8 and 5-ethynyl-2-deoxyuridine (EDU). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) and clonal colony on cells were formed to screen for the optimal concentration of Rem and to detect the viability. The expression of apoptosis-related proteins, Bcl-2 and P53, was determined by qRT-PCR and Western blotting. The effect of Rem on the expression of tumor markers, CEA and CA19-9, in CRC was examined through ELISA.

Results

TSPO expression in CRC tissues and cells was higher than that in ANT samples and normal intestinal epithelial cells. Over-expression of TSPO promoted the proliferation of HCT116 and the expression of tumor markers CEA and CA19-9 and inhibited the apoptosis of HCT116. Interference with TSPO inhibited the proliferation of HCT116 and the expression of CEA and CA19-9 and promoted the apoptosis of HCT116. 1 μg/mL Rem could inhibit the viability of HCT116, the proliferation of HCT116 and the expression of CEA and CA19-9, and improve the apoptosis of HCT116. TSPO could interact with VDAC and affect its protein expression, and Rem could inhibit the proliferation and the expression of CEA and CA19-9 through the TSPO/VDAC pathway, to promote its apoptosis.

Conclusion

Rem affects the proliferation of CRC cells by inhibiting the TSPO/VDAC pathway.

Novel PET Imaging of Inflammatory Targets and Cells for the Diagnosis and Monitoring of Giant Cell Arteritis and Polymyalgia Rheumatica

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are two interrelated inflammatory diseases affecting patients above 50 years of age. Patients with GCA suffer from granulomatous inflammation of medium- to large-sized arteries. This inflammation can lead to severe ischemic complications (e.g., irreversible vision loss and stroke) and aneurysm-related complications (such as aortic dissection). On the other hand, patients suffering from PMR present with proximal stiffness and pain due to inflammation of the shoulder and pelvic girdles. PMR is observed in 40-60% of patients with GCA, while up to 21% of patients suffering from PMR are also affected by GCA. Due to the risk of ischemic complications, GCA has to be promptly treated upon clinical suspicion. The treatment of both GCA and PMR still heavily relies on glucocorticoids (GCs), although novel targeted therapies are emerging. Imaging has a central position in the diagnosis of GCA and PMR. While [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) has proven to be a valuable tool for diagnosis of GCA and PMR, it possesses major drawbacks such as unspecific uptake in cells with high glucose metabolism, high background activity in several non-target organs and a decrease of diagnostic accuracy already after a short course of GC treatment. In recent years, our understanding of the immunopathogenesis of GCA and, to some extent, PMR has advanced. In this review, we summarize the current knowledge on the cellular heterogeneity in the immunopathology of GCA/PMR and discuss how recent advances in specific tissue infiltrating leukocyte and stromal cell profiles may be exploited as a source of novel targets for imaging. Finally, we discuss prospective novel PET radiotracers that may be useful for the diagnosis and treatment monitoring in GCA and PMR.

The 18-kDa Translocator Protein PET Tracers as a Diagnostic Marker for Neuroinflammation: Development and Current Standing

Translocator protein (TSPO, 18 kDa) is an evolutionary, well-preserved, and tryptophan-rich 169-amino-acid protein which localizes on the contact sites between the outer and inner mitochondrial membranes of steroid-synthesizing cells. This mitochondrial protein is implicated in an extensive range of cellular activities, including steroid synthesis, cholesterol transport, apoptosis, mitochondrial respiration, and cell proliferation. The upregulation of TSPO is well documented in diverse disease conditions including neuroinflammation, cancer, brain injury, and inflammation in peripheral organs. On the basis of these outcomes, TSPO has been assumed to be a fascinating subcellular target for early stage imaging of the diseased state and for therapeutic purposes. The main outline of this Review is to give an update on dealing with the advances made in TSPO PET tracers for neuroinflammation, synchronously emphasizing the approaches applied for the design and advancement of new tracers with reference to their structure-activity relationship (SAR).

Neuroproteomics Chip-Based Mass Spectrometry and Other Techniques for Alzheimer´S Disease Biomarkers – Update

Background:

Alzheimer's disease (AD) is a progressive neurodegenerative disease of growing interest given that there is cognitive damage and symptom onset acceleration. Therefore, it is important to find AD biomarkers for early diagnosis, disease progression, and discrimination of AD and other diseases.

Objective:

To update the relevance of mass spectrometry for the identification of peptides and proteins involved in AD useful as discriminating biomarkers.

Methods:

Proteomics and peptidomics technologies that show the highest possible specificity and selectivity for AD biomarkers are analyzed, together with the biological fluids used. In addition to positron emission tomography and magnetic resonance imaging, MALDI-TOF mass spectrometry is widely used to identify proteins and peptides involved in AD. The use of protein chips in SELDI technology and electroblotting chips for peptides makes feasible small amounts (L) of samples for analysis.

Results:

Suitable biomarkers are related to AD pathology, such as intracellular neurofibrillary tangles; extraneuronal senile plaques; neuronal and axonal degeneration; inflammation and oxidative stress. Recently, peptides were added to the candidate list, which are not amyloid-b or tau fragments, but are related to coagulation, brain plasticity, and complement/neuroinflammation systems involving the neurovascular unit.

Conclusion:

The progress made in the application of mass spectrometry and recent chip techniques is promising for discriminating between AD, mild cognitive impairment, and matched healthy controls. The application of this technique to blood samples from patients with AD has shown to be less invasive and fast enough to determine the diagnosis, stage of the disease, prognosis, and follow-up of the therapeutic response.