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Chemokines play a key role in the cellular infiltration of inflamed tissue. They are released by a wide variety of cell types during the initial phase of host response to injury, allergens, antigens, or invading microorganisms, and selectively attract leukocytes to inflammatory foci, inducing both migration and activation. Monocyte chemoattractant protein-1 (MCP-1), a member of the CC chemokine superfamily, functions in attracting monocytes, T lymphocytes, and basophils to sites of inflammation. MCP-1 is produced by monocytes, fibroblasts, vascular endothelial cells and smooth muscle cells in response to various stimuli such as tumour necrosis factor-a (TNF-a), interferon-g (IFN-g), and interleukin-1b (IL-1b). It also plays an important role in the pathogenesis of chronic inflammation, and overexpression of MCP-1 has been implicated in diseases including glomerulonephritis and rheumatoid arthritis. Oligonucleotide-directed triple helix formation offers a means to target specific sequences in DNA and interfere with gene expression at the transcriptional level. Triple helix-forming oligonucleotides (TFOs) bind to homopurine/homopyrimidine sequences, forming a stable, sequence-specific complex with the duplex DNA. Purine-rich sequences are frequent in gene regulatory regions and TFOs directed to promoter sequences have been shown to prevent binding of transcription factors and inhibit transcription initiation and elongation. Exogenous TFOs that bind homopurine/ homopyrimidine DNA sequences and form triple-helices can be rationally designed, while the intracellular delivery of single-stranded RNA TFOs has not been studied in detail before. In this study, expression vectors were constructed which directed transcription of either a 19 nt triplex-forming pyrimidine CU-TFO sequence targeting the human MCP-1 or two different 19 nt GU- or CA-control sequences, respectively, together with the vector encoded hygromycin resistance mRNA as one fusion transcript. HEK 293 cells were stable transfected with these vectors and several TFO and control cell lines were generated. Functional relevant triplex formation of a TFO with a corresponding 19 bp GC-rich AP-1/SP-1 site of the human MCP-1 promoter was shown. Binding of synthetic 19 nt CUTFO to the MCP-1 promoter duplex was verified by triplex blotting at pH 6.7. Underlining binding specificity, control sequences, including the GU- and CA-sequence, a TFO containing one single mismatch and a MCP-1 promoter duplex containing two mismatches, did not participate in triplex formation. Establishing a magnetic capture technique with streptavidin microbeads it was verified that at pH 7.0 the 19 nt TFO embedded in a 1.1 kb fusion transcript binds to a plasmid encoded MCP-1 promoter target duplex three times stronger than the controls. Finally, cell culture experiments revealed 76 ± 10.2% inhibition of MCP-1 protein secretion in TNF-a stimulated CU-TFO harboring cell lines and up to 88% after TNF-a and IFN-g costimulation in comparison to controls. Expression of interleukin-8 (IL-8) as one TNF-a inducible control gene was not affected by CU-TFO, demonstrating both highly specific and effective chemokine gene repression. Furthermore, another chemokine target, regulated upon activation normal T cell expressed and secreted (RANTES), which plays an essential role in inflammation by recruiting T lymphocytes, macrophages and eosinophils to inflammatory sites, was analysed using the triplex approach. A 28 nt TFO was designed targeting the murine RANTES gene promoter, and gel mobility shift assays demonstrated that the phosphodiester TFO formed a sequencespecific triplex with the double-stranded target DNA with a Kd of 2.5 x 10-7 M. It was analysed whether RANTES expression could be inhibited at the transcriptional level testing the TFO in two different cell lines, T helper-1 lymphocytes and brain microvascular endothelial cells (bend3 cells). Although there was a sequence-specific binding of the TFO detectable in the gel shift assays, there was no inhibitory effect of the exogenously added and phosphorothioate stabilised TFO on endogenous RANTES gene expression visible. Additionally, the small interfering RNA (siRNA) approach was tested as another strategy to inhibit expression of the pro-inflammatory chemokines MCP-1 and RANTES. Two different methods were pursuit, describing transient transfection with vector derived and synthetic siRNA. The vector pSUPER containing the siRNA coding sequence was used to suppress endogenous MCP-1 in HEK 293 cells. An empty vector without RNA sequence served as a control. Inhibition due to the siRNA was measured in stimulated and unstimulated cells. In TNF-a stimulated cells MCP-1 protein synthesis was decreased by 35 ± 11% after siRNA transfection. Using a synthetic double-stranded siRNA, the TNF-a induced MCP-1 protein secretion could be successfully inhibited about 62.3 ± 10.3% in HEK 293 cells, indicating that the siRNA is functional in these cells to suppress chemokine expression. The siRNA approach targeting murine RANTES in Th1 cells and b-end3 cells revealed no inhibition of endogenous gene expression. Gene therapy approaches rely on efficient transfer of genes to the desired target cells. A wide variety of viral and nonviral vectors have been developed and evaluated for their efficiency of transduction, sustained expression of the transgene, and safety. Among them, lentiviruses have been widely used for gene therapy applications. In order to improve the delivery of TFOs or siRNAs into the target cells, cloning of the lentiviral transfer vector SEW, the production of lentiviral particles by transient transfection were performed with the aim to generate lentiviral vector-derived TFOs in further experiments. Here, Th1 cells were transduced with infectious lentiviral particles and transduction efficacy was measured. Transduction efficacy higher than 82% could be achieved using the lentiviral vector SEW, opening optimal possibilities for the TFO or siRNA approach.
Patient therapy is based mainly on a combination of diagnosis, suitable monitoring or support devices and drug treatment and is usually employed for a pre-existing disease condition. Therapy remains predominantly symptom-based, although it is increasingly clear that individual treatment is possible and beneficial. However, reasonable precision medicine can only be realized with the coordinated use of diagnostics, devices and drugs in combination with extensive databases (4Ds), an approach that has not yet found sufficient implementation. The practical combination of 4Ds in health care is progressing, but several obstacles still hamper their extended use in precision medicine.
5-Lipoxygenase contributes to PPAR [gamma] activation in macrophages in response to apoptotic cells
(2012)
Background: One hallmark contributing to immune suppression during the late phase of sepsis is macrophage polarization to an anti-inflammatory phenotype upon contact with apoptotic cells (AC). Taking the important role of the nuclear receptor PPARγ for this phenotype switch into consideration, it remains elusive how AC activate PPARγ in macrophages. Therefore, we were interested to characterize the underlying principle.
Methods: Apoptosis was induced by treatment of Jurkat T cells for 3 hours with 0.5 μg/ml staurosporine. Necrotic cells (NC) were prepared by heating cells for 20 minutes to 65°C. PPARγ activation was followed by stably transducing RAW264.7 macrophages with a vector encoding the red fluorescent protein mRuby after PPARγ binding to 4 × PPRE sites downstream of the reporter gene sequence. This readout was established by treatment with the PPARγ agonist rosiglitazone (1 μM) and AC (5:1). Twenty-four hours after stimulation, mRuby expression was analysed by fluorescence microscopy. Lipid rafts of AC, NC, as well as living cells (LC) were enriched by sucrose gradient centrifugation. Fractions were analysed for lipid raft-associated marker proteins. Lipid rafts were incubated with transduced RAW264.7 macrophages as described above. 5-Lipoxygenase (5-LO) involvement was verified by pharmacological inhibition (MK-866, 1 μM) and overexpression.
Results: Assuming that the molecule responsible for PPARγ activation in macrophages is localized in the cell membrane of AC, most probably associated to lipid rafts, we isolated lipid rafts from AC, NC and LC. Mass spectrometric analysis of lipid rafts of AC showed the expression of 5-LO, whereas lipid rafts of LC did not. Moreover, incubating macrophages with lipid rafts of AC induced mRuby expression. In contrast, lipid rafts of NC and LC did not. To verify the involvement of 5-LO in activating PPARγ in macrophages, Jurkat T cells were incubated for 30 minutes with the 5-LO inhibitor MK-866 (1 μM) before apoptosis induction. In line with our hypothesis, these AC did not induce mRuby expression. Finally, although living Jurkat T cells overexpressing 5-LO did not activate PPARγ in macrophages, mRuby expression was significantly increased when AC were generated from 5-LO overexpressing compared with wild-type Jurkat cells.
Conclusion: Our results suggest that induction of apoptosis activates 5-LO, localizing to lipid rafts, necessary for PPARγ activation in macrophages. Therefore, it will be challenging to determine whether 5-LO activity in AC, generated from other cell types, correlates with PPARγ activation, contributing to an immune-suppressed phenotype in macrophages.
Since hyperactivity of the protein kinase DYRK1A is linked to several neurodegenerative disorders, DYRK1A inhibitors have been suggested as potential therapeutics for Down syndrome and Alzheimer’s disease. Most published inhibitors to date suffer from low selectivity against related kinases or from unfavorable physicochemical properties. In order to identify DYRK1A inhibitors with improved properties, a series of new chemicals based on [b]-annulated halogenated indoles were designed, synthesized, and evaluated for biological activity. Analysis of crystal structures revealed a typical type-I binding mode of the new inhibitor 4-chlorocyclohepta[b]indol-10(5H)-one in DYRK1A, exploiting mainly shape complementarity for tight binding. Conversion of the DYRK1A inhibitor 8-chloro-1,2,3,9-tetrahydro-4H-carbazol-4-one into a corresponding Mannich base hydrochloride improved the aqueous solubility but abrogated kinase inhibitory activity.
Bromodomains (BRDs) are conserved protein interaction modules which recognize (read) acetyl-lysine modifications, however their role(s) in regulating cellular states and their potential as targets for the development of targeted treatment strategies is poorly understood. Here we present a set of 25 chemical probes, selective small molecule inhibitors, covering 29 human bromodomain targets. We comprehensively evaluate the selectivity of this probe-set using BROMOscan and demonstrate the utility of the set identifying roles of BRDs in cellular processes and potential translational applications. For instance, we discovered crosstalk between histone acetylation and the glycolytic pathway resulting in a vulnerability of breast cancer cell lines under conditions of glucose deprivation or GLUT1 inhibition to inhibition of BRPF2/3 BRDs. This chemical probe-set will serve as a resource for future applications in the discovery of new physiological roles of bromodomain proteins in normal and disease states, and as a toolset for bromodomain target validation.
The prediction of protein–ligand interactions and their corresponding binding free energy is a challenging task in structure-based drug design and related applications. Docking and scoring is broadly used to propose the binding mode and underlying interactions as well as to provide a measure for ligand affinity or differentiate between active and inactive ligands. Various studies have revealed that most docking software packages reliably predict the binding mode, although scoring remains a challenge. Here, a diverse benchmark data set of 99 matched molecular pairs (3D-MMPs) with experimentally determined X-ray structures and corresponding binding affinities is introduced. This data set was used to study the predictive power of 13 commonly used scoring functions to demonstrate the applicability of the 3D-MMP data set as a valuable tool for benchmarking scoring functions.
Background: Human genetic research has implicated functional variants of more than one hundred genes in the modulation of persisting pain. Artificial intelligence and machine‐learning techniques may combine this knowledge with results of genetic research gathered in any context, which permits the identification of the key biological processes involved in chronic sensitization to pain.
Methods: Based on published evidence, a set of 110 genes carrying variants reported to be associated with modulation of the clinical phenotype of persisting pain in eight different clinical settings was submitted to unsupervised machine‐learning aimed at functional clustering. Subsequently, a mathematically supported subset of genes, comprising those most consistently involved in persisting pain, was analysed by means of computational functional genomics in the Gene Ontology knowledgebase.
Results: Clustering of genes with evidence for a modulation of persisting pain elucidated a functionally heterogeneous set. The situation cleared when the focus was narrowed to a genetic modulation consistently observed throughout several clinical settings. On this basis, two groups of biological processes, the immune system and nitric oxide signalling, emerged as major players in sensitization to persisting pain, which is biologically highly plausible and in agreement with other lines of pain research.
Conclusions: The present computational functional genomics‐based approach provided a computational systems‐biology perspective on chronic sensitization to pain. Human genetic control of persisting pain points to the immune system as a source of potential future targets for drugs directed against persisting pain. Contemporary machine‐learned methods provide innovative approaches to knowledge discovery from previous evidence.
Significance: We show that knowledge discovery in genetic databases and contemporary machine‐learned techniques can identify relevant biological processes involved in Persitent pain.
Background: The oral administration of the gum resin extracts of Indian frankincense (Boswellia serrata Roxb. ex Colebr) results in very low plasma concentrations of boswellic acids (BAs), being far below the pharmacologically active concentrations required in vitro for anti-inflammatory activity. For that reason the use of Indian frankincense in clinical practice and pharmaceutical development has substantially lagged behind. Recently the application of new formulation technologies resulted in a formulation of frankincense extract with lecithin, which revealed improved absorption and tissue penetration of BAs in a rodent study, leading for the first time to plasma concentrations of BAs in the range of their anti-inflammatory activity.
Purpose: In order to verify these encouraging results in humans, the absorption of a standardized Boswellia serrata extract (BE) and its lecithin formulation (CSP) was comparatively investigated in healthy volunteers.
Study design: According to a randomized cross-over design with two treatments, two sequences and two periods, 12 volunteers alternatively received the lecithin-formulated Boswellia extract (CSP) or the non-formulated Boswellia extract (BE) at a dosage of 2 × 250 mg capsules.
Methods: The plasma concentrations of the six major BAs (KBA, AKBA, βBA, αBA, AβBA, AαBA) were determined using LC/MS.
Results: With the exception of KBA, a significantly higher (both in terms of weight-to-weight and molar comparison) and quicker absorption of BAs from the lecithin formulation was observed, leading to Cmax in the range required for the interaction with their molecular targets.
Conclusion: These findings pave the way to further studies evaluating the clinical potential of BAs, and verify the beneficial effect of lecithin formulation to improve the absorption of poorly soluble phytochemicals.
CD4+CD25+ regulatory T cells (Tregs) represent a specialized subpopulation of T cells, which are essential for maintaining peripheral tolerance and preventing autoimmunity. The immunomodulatory effects of Tregs depend on their activation status. Here we show that, in contrast to conventional anti-CD4 monoclonal antibodies (mAbs), the humanized CD4-specific monoclonal antibody tregalizumab (BT-061) is able to selectively activate the suppressive properties of Tregs in vitro. BT-061 activates Tregs by binding to CD4 and activation of signaling downstream pathways. The specific functionality of BT-061 may be explained by the recognition of a unique, conformational epitope on domain 2 of the CD4 molecule that is not recognized by other anti-CD4 mAbs. We found that, due to this special epitope binding, BT-061 induces a unique phosphorylation of T-cell receptor complex-associated signaling molecules. This is sufficient to activate the function of Tregs without activating effector T cells. Furthermore, BT-061 does not induce the release of pro-inflammatory cytokines. These results demonstrate that BT-061 stimulation via the CD4 receptor is able to induce T-cell receptor-independent activation of Tregs. Selective activation of Tregs via CD4 is a promising approach for the treatment of autoimmune diseases where insufficient Treg activity has been described. Clinical investigation of this new approach is currently ongoing.
Activation of Mitochondrial complex II-dependent respiration is beneficial for α-Synucleinopathies
(2015)
Parkinson’s disease and dementia with Lewy bodies are major challenges in research and clinical medicine world-wide and contribute to the most common neurodegenerative disorders. Previously, specific mitochondrial polymorphisms have been found to enhance clearance of amyloid-β from the brain of APP-transgenic mice leading to beneficial clinical outcome. It has been discussed whether specific mitochondrial alterations contribute to disease progression or even prevent toxic peptide deposition, as seen in many neurodegenerative diseases. Here, we investigated α-synuclein-transgenic C57BL/6J mice with the A30P mutation, and a novel A30P C57BL/6J mouse model with three mitochondrial DNA polymorphisms in the ND3, COX3 and mtRNAArg genes, as found in the inbred NOD/LtJ mouse strain. We were able to detect that the new model has increased mitochondrial complex II-respiration which occurs in parallel to neuronal loss and improved motor performance, although it exhibits higher amounts of high molecular weight species of α-synuclein. High molecular weight aggregates of different peptides are controversially discussed in the light of neurodegeneration. A favourable hypothesis states that high molecular weight species are protective and of minor importance for the pathogenesis of neurodegenerative disorders as compared to the extreme neurotoxic monomers and oligomers. Summarising, our results point to a potentially protective and beneficial effect of specific mitochondrial polymorphisms which cause improved mitochondrial complex II-respiration in α-synucleinopathies, an effect that could be exploited further for pharmaceutical interventions.