Blood-brain barrier transport kinetics of NOTA-modified proteins : the somatropin case

BACKGROUND: Chemical modifications such as PEG, polyamine and radiolabeling on proteins can alter their pharmacokinetic behaviour and their blood-brain barrier (BBB) transport characteristics. NOTA, i.e. 1,4,7-triazacyclononane-1,4,7-triacetic acid, is a bifunctional chelating agent that has attracted the interest of the scientific community for its high complexation constant with metals like gallium. Until now, the comparative BBB transport characteristics of NOTA-modified proteins versus unmodified proteins are not yet described. METHODS: Somatropin (i.e. recombinant human growth hormone), NOTA-conjugated somatropin and gallium-labelled NOTA-conjugated somatropin were investigated for their brain penetration characteristics (multiple time regression and capillary depletion) in an in vivo mice model to determine the blood-brain transfer properties. RESULTS: The three compounds showed comparable initial brain influx, with Kin = 0.38 ± 0.14 µL/(g×min), 0.36 ± 0.16 µL/(g×min) and 0.28 ± 0.18 µL/(g×min), respectively. Capillary depletion indicated that more than 80% of the influxed compounds reached the brain parenchyma. All three compounds were in vivo stable in serum and brain during the time frame of the experiments. CONCLUSIONS: Our results show that modification of NOTA as well as gallium chelation onto proteins, in casu somatropin, does not lead to a significantly changed pharmacokinetic profile at the blood-brain barrier

Quality of isotopically labelled internal standards for peptide quantification

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Safety and immunomodulatory properties of equine peripheral blood-derived mesenchymal stem cells in healthy cats

Objective: Due to the immunomodulatory properties of mesenchymal stem cells (MSCs) through stimulation of endogenous immune cells by paracrine signals and cell contact, they have been proposed as alternative treatment option for many inflammatory and immune-mediated diseases in veterinary medicine. However, the long-term cultivation possibilities of feline MSCs are currently compromised due to a restricted proliferation capacity. Therefore, the xenogeneic use of equine peripheral blood-derived MSCs (ePB-MSCs) would present an interesting alternative thanks to their superior cultivation properties. To the authors' knowledge, there are currently no safety reports concerning the xenogeneic use of ePB-MSCs in cats. Therefore, the overall goal of this preliminary study was to investigate if ePB-MSCs can safely be administered in healthy cats and by extension evaluating their immunogenic and immunomodulatory properties. Methods: Ten healthy cats were intravenously (i.v.) injected with 3 x 10(5) ePB-MSCs at three time points (T-0, T-1, T-2). All cats were daily inspected by the caretaker and underwent a physical examination with hematological and biochemical analysis at day 0 (T-0), week 2 (T-1), week 4 (T-2) and week 6 (T-3) by a veterinarian. Furthermore, a modified mixed lymphocyte reaction (MLR) was performed at T-0 and T-3 for each cat in order to evaluate immunogenic and immunomodulatory properties of the ePB-MSCs Results: No adverse clinical effects could be detected following repeated i.v. administration of ePB-MSCs in all cats. Significant lower protein (T-1: P-value = 0.002; T-2: P-value > 0.001; T-3: P-value = 0.004) and albumin levels (T-1: P-value = 0.003; T-2: P-value = 0.001) were seen after repeated administration of ePB-MSCs, compared to T-0. However, all biochemical and hematological parameters stayed within clinical acceptance level. In addition, the repeated injections did not induce a cellular immune response before and after repeated ePB-MSCs administration. Furthermore, convincing immunomodulatory properties of ePB-MSCs on feline peripheral blood mononuclear cells were confirmed in the MLR-assay Conclusion: This preliminary study demonstrates that ePB-MSCs can safely be administered in healthy cats and provide a promising alternative for the treatment of various inflammatory diseases in cats

Poly(glycerol sebacate) nanoparticles for encapsulation of hydrophobic anti-cancer drugs

Physical encapsulation of hydrophobic compounds into nanocarriers that are stable in aqueous medium is of high interest as it can increase solubilization of the drug, lower its toxicity, control its pharmacokinetic profile and thus overall improve the therapeutic efficacy. To increase solubilization of a drug in aqueous medium, the carrier should contain hydrophobic domains that can form non-covalent interactions with hydrophobic drug molecules. Apart from liposomes, polymers have been widely acknowledged as promising nanocarriers. In this paper, we report the design of poly(glycerol sebacate) (PGS), an inexpensive, water insoluble but biodegradable and biocompatible polymer, into nanocarriers for hydrophobic drugs. Mixing of alcoholic PGS solutions with water (i.e. solvent displacement) produced a fine and highly stable dispersion with a size that can be controlled by the PGS concentration and solvent to water ratio. These dispersions were used for the encapsulation of hydrophobic compounds such as a fluorescent dye and two drugs known for their anti-mitotic activity (i.e. paclitaxel (PTX) and flubendazole (FLU)). These formulations were then evaluated in vitro with cancer cells

Scintigraphic tracking of 99mTechnetium-labelled equine peripheral blood-derived mesenchymal stem cells after intravenous, intramuscular, and subcutaneous injection in healthy dogs

Background: Mesenchymal stem cell treatments in dogs have been investigated as a potential innovative alternative to current conventional therapies for a variety of conditions. So far, the precise mode of action of the MSCs has yet to be determined. The aim of this study was to gain more insights into the pharmacokinetics of MSCs by evaluating their biodistribution in healthy dogs after different injection routes. Methods: Three different studies were performed in healthy dogs to evaluate the biodistribution pattern of radiolabelled equine peripheral blood-derived mesenchymal stem cells following intravenous, intramuscular and subcutaneous administration in comparison with free (99m)Technetium. The labelling of the equine peripheral blood-derived mesenchymal stem cells was performed using stannous chloride as a reducing agent. Whole-body scans were obtained using a gamma camera during a 24-h follow-up. Results: The labelling efficiency ranged between 59.58 and 83.82%. Free (99m)Technetium accumulation was predominantly observed in the stomach, thyroid, bladder and salivary glands, while following intravenous injection, the (99m)Technetium-labelled equine peripheral blood-derived mesenchymal stem cells majorly accumulated in the liver throughout the follow-up period. After intramuscular and subcutaneous injection, the injected dose percentage remained very high at the injection site. Conclusions: A distinct difference was noted in the biodistribution pattern of the radiolabelled equine peripheral blood-derived mesenchymal stem cells compared to free (99m)Technetium indicating equine peripheral blood-derived mesenchymal stem cells have a specific pharmacokinetic pattern after systemic administration in healthy dogs. Furthermore, the biodistribution pattern of the used xenogeneic equine peripheral blood-derived mesenchymal stem cells appeared to be different from previously reported experiments using different sources of mesenchymal stem cells

Biological Characterisation of Somatropin-Derived Cryptic Peptides

© 2018, Springer Nature B.V. Little is known about possible cryptic peptides of the recombinant growth hormone (somatropin). In this study, six synthetic somatropin-derived peptides (SDPs) were selected based on their sequences which correspond to the binding interface of the growth hormone receptor (GHR). Their novelty was confirmed by in silico and in vitro proteolytic digestion of somatropin. Chemical characterisation of the SDPs, i.e. identification via LC–MS and purity quantification via HPLC-UV and U(H)PLC-MRM, was first performed. All the SDPs were stable in brain tissue homogenate, liver tissue homogenate and serum (t1/2 > 15 min). The metabolites in brain and serum, formed between 15 and 120 min, were also identified. The interactions towards the GHR and the human growth hormone binding protein (hGHBp) were also evaluated using GHR bioassay and native MS. No interaction was detected under the applied conditions. A last part of the study investigated the pharmacokinetics and tissue distribution of two peptides (i.e. SDP167–175 and SDP101–121), selected based on their position within somatropin. A high blood–brain barrier (BBB) influx was observed for SDP101–121, while SDP167–175 showed a negligible BBB influx. Based on the obtained results, the GHR binding of the selected SDPs is very low, requiring structural adaptations for further GHR-binding exploration.status: publishe

Biological characterisation of somatropin-derived cryptic peptides

Little is known about possible cryptic peptides of the recombinant growth hormone (somatropin). In this study, six synthetic somatropin-derived peptides (SDPs) were selected based on their sequences which correspond to the binding interface of the growth hormone receptor. Their novelty was confirmed by in silico and in vitro proteolytic digestion of somatropin. Chemical characterisation of the SDPs, i.e. identification via LC-MS and purity quantification via HPLC-UV and U(H)PLC-MRM, was first performed. All the SDPs were stable in brain tissue homogenate, liver tissue homogenate and serum (t1/2 > 15 min). The metabolites in brain and serum, formed between 15 min and 120 min, were also identified. The interactions towards the growth hormone receptor (GHR) and the human growth hormone binding protein (hGHBp) were also evaluated using GHR bioassay and native MS. No interaction was detected under the applied conditions. A last part of the study investigated the pharmacokinetics and tissue distribution of two peptides (i.e. SDP167-175 and SDP101-121), selected based on their position within somatropin. A high blood-brain barrier (BBB) influx was observed for SDP101-121, while SDP167-175 showed a negligible BBB influx. Based on the obtained results, the GHR binding of the selected SDPs is very low, requiring structural adaptations for further GHR-binding exploration

Biological characterisation of somatropin-derived cryptic peptides

Little is known about possible cryptic peptides of the recombinant growth hormone (somatropin). In this study, six synthetic somatropin-derived peptides (SDPs) were selected based on their sequences which correspond to the binding interface of the growth hormone receptor (GHR). Their novelty was confirmed by in silico and in vitro proteolytic digestion of somatropin. Chemical characterisation of the SDPs, i.e. identification via LC–MS and purity quantification via HPLC-UV and U(H)PLC-MRM, was first performed. All the SDPs were stable in brain tissue homogenate, liver tissue homogenate and serum (t1/2 > 15 min). The metabolites in brain and serum, formed between 15 and 120 min, were also identified. The interactions towards the GHR and the human growth hormone binding protein (hGHBp) were also evaluated using GHR bioassay and native MS. No interaction was detected under the applied conditions. A last part of the study investigated the pharmacokinetics and tissue distribution of two peptides (i.e. SDP167–175 and SDP101–121), selected based on their position within somatropin. A high blood–brain barrier (BBB) influx was observed for SDP101–121, while SDP167–175 showed a negligible BBB influx. Based on the obtained results, the GHR binding of the selected SDPs is very low, requiring structural adaptations for further GHR-binding exploration.Grants from the Research Foundation FWO (Flanders) and NRF (South-Africa) (Grant No. G0G7617N) to Liesa Tack and from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen) to Frederick Verbeke (Grant No. 131356).https://link.springer.com/journal/109892019-08-21hj2018Nuclear Medicin

The quorum sensing peptide EntF* promotes colorectal cancer metastasis in mice: a new factor in the host-microbiome interaction

Abstract Background Colorectal cancer, one of the most common malignancies worldwide, is associated with a high mortality rate, mainly caused by metastasis. Comparative metagenome-wide association analyses of healthy individuals and cancer patients suggest a role for the human intestinal microbiota in tumor progression. However, the microbial molecules involved in host-microbe communication are largely unknown, with current studies mainly focusing on short-chain fatty acids and amino acid metabolites as potential mediators. Quorum sensing peptides are not yet considered in this context since their presence in vivo and their ability to affect host cells have not been reported so far. Results Here, we show that EntF*, a metabolite of the quorum sensing peptide EntF produced by Enterococcus faecium, is naturally present in mice bloodstream. Moreover, by using an orthotopic mouse model, we show that EntF* promotes colorectal cancer metastasis in vivo, with metastatic lesions in liver and lung tissues. In vitro tests suggest that EntF* regulates E-cadherin expression and consequently the epithelial-mesenchymal transition, via the CXCR4 receptor. In addition, alanine-scanning analysis indicates that the first, second, sixth, and tenth amino acid of EntF* are critical for epithelial-mesenchymal transition and tumor metastasis. Conclusion Our work identifies a new class of molecules, quorum sensing peptides, as potential regulators of host-microbe interactions. We prove, for the first time, the presence of a selected quorum sensing peptide metabolite in a mouse model, and we demonstrate its effects on colorectal cancer metastasis. We believe that our work represents a starting point for future investigations on the role of microbiome in colorectal cancer metastasis and for the development of novel bio-therapeutics in other disease areas. </jats:sec