Evaluation of the novel folate receptor ligand [18F]fluoro-PEG-folate for macrophage targeting in a rat model of arthritis

Introduction

Detection of (subclinical) synovitis is relevant for both early diagnosis and monitoring of therapy of rheumatoid arthritis (RA). Previously, the potential of imaging (sub)clinical arthritis was demonstrated by targeting the translocator protein in activated macrophages using (R)-[¹¹C]PK11195 and positron emission tomography (PET). Images, however, also showed significant peri-articular background activity. The folate receptor (FR)-β is a potential alternative target for imaging activated macrophages. Therefore, the PET tracer [¹⁸F]fluoro-PEG-folate was synthesized and evaluated in both in vitro and ex vivo studies using a methylated BSA induced arthritis model.

Methods

[¹⁸F]fluoro-PEG-folate was synthesized in a two-step procedure. Relative binding affinities of non-radioactive fluoro-PEG-folate, folic acid and naturally circulating 5-methyltetrahydrofolate (5-Me-THF) to FR were determined using KB cells with high expression of FR. Both in vivo [¹⁸F]fluoro-PEG-folate PET and ex vivo tissue distribution studies were performed in arthritic and normal rats and results were compared with those of the established macrophage tracer (R)-[¹¹C]PK11195.

Results

[¹⁸F]fluoro-PEG-folate was synthesized with a purity >97%, a yield of 300 to 1,700 MBq and a specific activity between 40 and 70 GBq/µmol. Relative in vitro binding affinity for FR of F-PEG-folate was 1.8-fold lower than that of folic acid, but 3-fold higher than that of 5-Me-THF. In the rat model, [¹⁸F]fluoro-PEG-folate uptake in arthritic knees was increased compared with both contralateral knees and knees of normal rats. Uptake in arthritic knees could be blocked by an excess of glucosamine-folate, consistent with [¹⁸F]fluoro-PEG-folate being specifically bound to FR. Arthritic knee-to-bone and arthritic knee-to-blood ratios of [¹⁸F]fluoro-PEG-folate were increased compared with those of (R)-[¹¹C]PK11195. Reduction of 5-Me-THF levels in rat plasma to those mimicking human levels increased absolute [¹⁸F]fluoro-PEG-folate uptake in arthritic joints, but without improving target-to-background ratios.

Conclusions

The novel PET tracer [¹⁸F]fluoro-PEG-folate, designed to target FR on activated macrophages provided improved contrast in a rat model of arthritis compared with the accepted macrophage tracer (R)-[¹¹C]PK11195. These results warrant further exploration of [¹⁸F]fluoro-PEG-folate as a putative PET tracer for imaging (sub)clinical arthritis in RA patients.     

Transformation of chenodeoxycholic acid by thermophilic Geobacillus stearothermophilus

We performed a series of experiments with Geobacillus stearothermophilus, a thermophile isolated from oil-contaminated soil in the Kuwaiti desert. The organism has a good potential for the transformation of a broad spectrum of organic molecules such as steroids, amino acids, and aromatic hydrocarbons. In the present study, we tested its potential for the transformation of a bile component, chenodeoxycholic acid (CDCA). Five transformed products, namely, cholic acid, methylcholate, methylchenodeoxycholate, 3α-hydroxy-7-oxo-5β-cholanic acid, and 7α-hydroxy-3-oxo-5β-cholanic acid, were the major transformation products catalyzed by G. stearothermophilus. Under aerobic conditions, no evidence of side chain degradation, ring cleavage, or dehydrogenation was found among the metabolites of CDCA. CDCA transformation by a thermophile is reported for the first time.     

Studies on Geobacillus stearothermophilus – Part V: Transformation of 11α-hydroxyprogesterone

The influence of a hydroxyl group on the biotransformation of 11α-hydroxyprogesterone mediated by the thermophile Geobacillus stearothermophilus, was investigated. Bacterial transformation of 11α-hydroxyprogesterone resulted in the formation of previously reported six hydroxylated progesterone metabolites, identified as 11α-hydroxy-5α-pregnane-3, 6, 20-trione 1, 11α, 20α-dihydroxypregnene-3-one 2, 11α, 6β-dihydroxyprogesterone 3, 11α, 6α-dihydroxyprogesterone 4, 11α, 6β, 20α-trihydroxypregnene-3-one 5, 11α, 6α, 20α-trihydroxypregnene-3-one 6. All transformation products were identified through their spectral data and comparison with reference compounds.     

Relaxin family peptide receptors Rxfp1 and Rxfp2: mapping of the mRNA and protein distribution in the reproductive tract of the male rat

Background  

Relaxin is the endogenous ligand of the G-protein coupled receptor RXFP1, previously known as LGR7. In humans relaxin can also activate, but with lower affinity, the closely related receptor for the insulin-like peptide from Leydig cells, RXFP2, previously known as LGR8. The lack of relaxin impairs male fertility but the precise distribution and the function of relaxin receptors in the male reproductive tract is not known. We investigated the distribution of Rxfp1 and Rxfp2 in the reproductive tract of the male rat and the function of relaxin in the vas deferens, a tissue with high expression of both receptors.     

Improving inhaler adherence in patients with Chronic Obstructive Pulmonary Disease: a cost-effectiveness analysis

Background

The PHARMACOP-intervention significantly improved medication adherence and inhalation technique for patients with COPD compared with usual care. This study aimed to evaluate its cost-effectiveness.

Methods

An economic analysis was performed from the Belgian healthcare payer’s perspective. A Markov model was constructed in which a representative group of patients with COPD (mean age of 70 years, 66% male, 43% current smokers and mean Forced Expiratory Volume in 1 second of % predicted of 50), was followed for either receiving the 3-month PHARMACOP-intervention or usual care. Three types of costs were calculated: intervention costs, medication costs and exacerbation costs. Outcome measures included the number of hospital-treated exacerbations, cost per prevented hospital-treated exacerbation and cost per Quality Adjusted Life-Year. Follow-up was 1 year in the basecase analysis. Sensitivity and scenario analyses (including long-term follow-up) were performed to assess uncertainty.

Results

In the basecase analysis, the average overall costs per patient for the PHARMACOP-intervention and usual care were €2,221 and €2,448, respectively within the 1-year time horizon. This reflects cost savings of €227 for the PHARMACOP-intervention. The PHARMACOP-intervention resulted in the prevention of 0.07 hospital-treated exacerbations per patient (0.177 for PHARMACOP versus 0.244 for usual care). Results showed robust cost-savings in various sensitivity analyses.

Conclusions

Optimization of current pharmacotherapy (e.g. close monitoring of inhalation technique and medication adherence) has been shown to be cost-saving and should be considered before adding new therapies.     

Biologically relevant effects of mRNA amplification on gene expression profiles

Background  

Gene expression microarray technology permits the analysis of global gene expression profiles. The amount of sample needed limits the use of small excision biopsies and/or needle biopsies from human or animal tissues. Linear amplification techniques have been developed to increase the amount of sample derived cDNA. These amplified samples can be hybridised on microarrays. However, little information is available whether microarrays based on amplified and unamplified material yield comparable results.     

Chromosome phylogeny of the subfamily Pitheciinae (Platyrrhini,Primates) by classic cytogenetics and chromosome painting

Background  

The New World monkey (Platyrrhini) subfamily Pitheciinae is represented by the genera Pithecia, Chiropotes and Cacajao. In this work we studied the karyotypes of Pithecia irrorata (2n = 48) and Cacajao calvus rubicundus (2n = 45 in males and 2n = 46 in females) by G- and C-banding, NOR staining and chromosome painting using human and Saguinus oedipus whole chromosome probes. The karyotypes of both species were compared with each other and with Chiropotes utahicki (2n = 54) from the literature.     

Direct anti-metastatic efficacy by the DNA enzyme Dz13 and downregulated MMP-2, MMP-9 and MT1-MMP in tumours

The DNA enzyme Dz13, targeted against the oncogene c-Jun, is capable of inhibiting various model tumours in mice albeit in ectopic models of neoplasia. In previous studies using orthotopic models of disease, the inhibitory effects of Dz13 on secondary growth was a direct result of growth inhibition at the primary lesion site. Thus, the direct and genuine effects on metastasis were not gauged. In this study, Dz13 was able to inhibit both locoregional and distal metastasis of tumour cells in mice, in studies where the primary tumours were unaffected due to the late and clinically-mimicking nature of treatment commencement. In addition, the effect of Dz13 against tumours has now been extended to encompass breast and prostate cancer. Dz13 upregulated the matrix metalloproteinase (MMP)-2 and MMP-9, and decreased expression of MT1-MMP (MMP-14) in cultured tumour cells. However, in sections of ectopic tumours treated with Dz13, both MMP-2 and MMP-9 were downregulated. Thus, not only is Dz13 able to inhibit tumour growth at the primary site, but also able to decrease the ability of neoplastic cells to metastasise. These findings further highlight the growing potential of Dz13 as an antineoplastic agent.     

Clinical findings in an Arab boy with ring (14)(mos 46,XY,r(14)/45,XY,-14)

A five-month male Arab child with clinical features of ring(14) is reported. He had recurrent seizures and chest infections, microcephaly, elongated face, short palpebral fissures, broad nasal bridge, long philtrum, fish-like mouth with thin lips, micrognathia, low-set ears and retinal pigmentation with yellow-white spots on the maculae. In addition brachydactyly of fingers and toes, hypoplastic scrotum and mental deterioration were present.