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G-protein-coupled receptors are integral membrane proteins that transduce chemical signals from the extracellular matrix into the cell. Traditional drug design has considered ligand-receptor interactions only under normal conditions. However, studies on opioids indicate that such interactions are very different in diseased tissues. In such microenvironments, protons play an important role in structural and functional alterations of both ligands and receptors. The pertinent literature strongly suggests that future drug design should take these aspects into account in order to reduce adverse side effects while preserving desired effects of novel compounds.
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OBJECTIVE: The effectiveness of µ-opioid receptor (MOPr) agonists for treatment of visceral pain is compromised by constipation, respiratory depression, sedation and addiction. We investigated whether a fentanyl analogue, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP), which preferentially activates MOPr in acidified diseased tissues, would inhibit pain in a preclinical model of inflammatory bowel disease (IBD) without side effects in healthy tissues. DESIGN: Antinociceptive actions of NFEPP and fentanyl were compared in control mice and mice with dextran sodium sulfate colitis by measuring visceromotor responses to colorectal distension. Patch clamp and extracellular recordings were used to assess nociceptor activation. Defecation, respiration and locomotion were assessed. Colonic migrating motor complexes were assessed by spatiotemporal mapping of isolated tissue. NFEPP-induced MOPr signalling and trafficking were studied in human embryonic kidney 293 cells. RESULTS: NFEPP inhibited visceromotor responses to colorectal distension in mice with colitis but not in control mice, consistent with acidification of the inflamed colon. Fentanyl inhibited responses in both groups. NFEPP inhibited the excitability of dorsal root ganglion neurons and suppressed mechanical sensitivity of colonic afferent fibres in acidified but not physiological conditions. Whereas fentanyl decreased defecation and caused respiratory depression and hyperactivity in mice with colitis, NFEPP was devoid of these effects. NFEPP did not affect colonic migrating motor complexes at physiological pH. NFEPP preferentially activated MOPr in acidified extracellular conditions to inhibit cAMP formation, recruit ß-arrestins and evoke MOPr endocytosis. CONCLUSION: In a preclinical IBD model, NFEPP preferentially activates MOPr in acidified microenvironments of inflamed tissues to induce antinociception without causing respiratory depression, constipation and hyperactivity.
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Colitis , Neoplasias Colorrectales , Enfermedades Inflamatorias del Intestino , Insuficiencia Respiratoria , Dolor Visceral , Animales , Colitis/inducido químicamente , Colon , Estreñimiento , Fentanilo/efectos adversos , Humanos , Enfermedades Inflamatorias del Intestino/complicaciones , Ratones , Receptores Opioides , Microambiente TumoralRESUMEN
Opioids are molecules whose binding to specialized G-Protein Coupled Receptors (GPCRs) triggers a signaling cascade that leads to the downregulation of pain pathways. Binding of an opioid to the membrane-embedded GPCR occurs when the opioid molecule is protonated, which provides a potential strategy to design nontoxic opioids that are protonated and bind to the GPCR only at the low pH of injured or inflamed tissue. Excellent model systems to study protonation-dependent binding of opioids to GPCRs are fentanyl, which is protonated and binds to the GPCR at both physiological and low pH, and the fluorinated fentanyl derivative NFEPP, which is protonated and binds to the GPCR only at low pH. The molecular mechanisms of fentanyl and NFEPP binding to the GPCR are largely unknown. To enable atomistic studies of opioid binding to GPCRs, we have carried out extensive quantum mechanical and classical mechanical computations to derive a potential energy function for fentanyl and NFEPP and present force field parameters for both opioid molecules. We find that fluorination alters the electronic ground state properties of fentanyl. As a consequence, fentanyl and NFEPP have distinct torsional and electrostatic properties likely to impact how they bind to receptors.
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Analgésicos Opioides , Fentanilo , Analgésicos , Fentanilo/uso terapéutico , Humanos , Dolor/tratamiento farmacológico , Receptores Opioides muRESUMEN
Intracellular persistence of Staphylococcus aureus favors bacterial spread and chronic infections. Here, we provide evidence for the existence of human CD4+ and CD8+ T cell memory against staphylococcal antigens. Notably, the latter could provide a missing link in our understanding of immune control of intracellular S. aureus. The analyses showed that pulsing of monocyte-derived dendritic cells (MoDC) with native staphylococcal protein antigens induced release of Th2-associated cytokines and mediators linked to T regulatory cell development (G-CSF, IL-2 and IL-10) from both CD4+ and CD8+ T cells, thus revealing a state of tolerance predominantly arising from preformed memory T cells. Furthermore, G-CSF was identified as a suppressor of CD8+ T cell-derived IFNγ secretion, thus confirming a tolerogenic role of this cytokine in the regulation of T cell responses to S. aureus. Nevertheless, delivery of in vitro transcribed mRNA-encoded staphylococcal antigens triggered Th1-biased responses, e.g. IFNγ and TNF release from both naïve and memory T cells. Collectively, our data highlight the potential of mRNA-adjuvanted antigen presentation to enable inflammatory responses, thus overriding the existing Th2/Treg-biased memory T cell response to native S. aureus antigens.
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Antígenos Bacterianos/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Células Dendríticas/inmunología , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/inmunología , Presentación de Antígeno , Citocinas/inmunología , Factor Estimulante de Colonias de Granulocitos/inmunología , Humanos , Tolerancia Inmunológica , Interleucina-10/inmunología , Interleucina-2/inmunología , Infecciones Estafilocócicas/microbiología , Linfocitos T Reguladores/inmunología , Células Th2/inmunologíaRESUMEN
Opioids are the oldest and most potent drugs for the treatment of severe pain. Their clinical application is undisputed in acute (e.g., postoperative) and cancer pain, but their long-term use in chronic pain has met increasing scrutiny. This article reviews mechanisms underlying opioid analgesia and other opioid actions. It discusses the structure, function, and plasticity of opioid receptors; the central and peripheral sites of analgesic actions and side effects; endogenous and exogenous opioid receptor ligands; and conventional and novel opioid compounds. Challenging clinical situations, such as the tension between chronic pain and addiction, are also illustrated.
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Analgésicos Opioides/uso terapéutico , Dolor/tratamiento farmacológico , Receptores Opioides/agonistas , Receptores Opioides/metabolismo , Analgésicos Opioides/farmacología , Dolor Crónico/tratamiento farmacológico , Tolerancia a Medicamentos , Humanos , Ligandos , Antagonistas de Narcóticos/uso terapéutico , Plasticidad Neuronal , Trastornos Relacionados con Opioides/etiología , Dolor/metabolismo , Receptores Opioides/efectos de los fármacos , Transducción de Señal , Factores de TiempoRESUMEN
The innate immune system harbors a multitude of different receptor systems and cells that are constantly prepared to sense and eliminate invading microbial pathogens. Staphylococcus aureus enters the body on its exposed epithelial surfaces, e.g., on skin and mucosa. The initial interaction with epithelial cells is governed by Toll-like receptor (TLR)-2-mediated local production of soluble mediators, including cytokines, chemokines, and antimicrobial peptides. The overall goal is to achieve a steady state of immune mediators and colonizing bacteria. Following cell and tissue invasion clearance of bacteria depends on intracellular microbial sensors and subsequent activation of the inflammasomes. Tissue-resident mast cells and macrophages recruit neutrophils, macrophages, and NK cells. This inflammatory response supports the generation of IL-17 producing NKT, γδ T cells, and T helper cells. Local dendritic cells migrate to the lymph nodes and fine-tune the adaptive immune response. The scope of this chapter is to provide an overview on the major cell types and receptors involved in innate immune defense against S. aureus. By segregating the different stages of infection from epithelial barrier to intracellular and systemic infection, this chapter highlights the different qualities of the innate immune response to S. aureus at different stages of invasiveness.
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Inmunidad Innata , Staphylococcus aureus , CitocinasRESUMEN
OBJECTIVE: The objective of this study was to investigate the effect of topical morphine on erosive/ulcerative lesions in patients with oral lichen planus (OLP). Previous studies reported on an enhanced remission of skin wounds when morphine was applied topically. MATERIALS AND METHODS: This was single-center, prospective, double-blind, placebo-controlled, randomized, multi-arm (3), phase II study (RCT). Patients diagnosed with erosive and/or ulcerative OLP applied 0.2 or 0.4 mg morphine dissolved in glycerine, three times a day for 5 days. The primary outcome was the extent of healing. Secondary outcomes were as follows: (1) effect on pain, (2) presence and severity of opioid-related central and local side effects, (3) whether patients required 'rescue medication' for treatment of pain, and (4) total intake of test substance. RESULTS: A total of 123 patients were screened for eligibility, 45 patients were recruited into the study, and 43 completed it. Patients applied a solution of either placebo or 0.2 or 0.4% morphine in groups of n = 12, n = 15, and n = 16, respectively. Extent of healing was similar in the three groups. Severity of pain was minor pre-treatment and throughout the course of the study. Only minor adverse events were reported (dry mouth, burning sensation). CONCLUSION: Morphine did not enhance wound healing compared to placebo-treated patients. Healing was observed in all groups, which may be attributed to an effect of glycerine or to the natural course of the disease. Patients experienced only mild levels of pain, rendering the model insensitive for assessing pain. CLINICAL RELEVANCE: OLP is a chronic disease and current treatment options are limited. Healing occurred in all three study groups, an effect we attribute to the carrier.
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Analgésicos Opioides/administración & dosificación , Liquen Plano Oral/tratamiento farmacológico , Morfina/administración & dosificación , Manejo del Dolor/métodos , Cicatrización de Heridas/efectos de los fármacos , Administración Tópica , Adolescente , Adulto , Anciano , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dimensión del Dolor , Estudios Prospectivos , Resultado del TratamientoRESUMEN
BACKGROUND: This study examined the development of chronic pain, a cardinal symptom of rheumatoid arthritis (RA), in mice with antigen- and collagen-induced arthritis (ACIA). Since the role of CD8+ T cells in arthritis is controversial, we investigated the consequences of CD8-depletion on arthritis development and opioid modulation of pain in this novel model of chronic autoimmune arthritis. METHODS: Disease severity in control and CD8-depleted animals was determined by histological assessment of knee-joint sections and measurement of autoantibody formation. Pain was evaluated by measuring mechanical allodynia and thermal hyperalgesia in von Frey and Hargreaves tests, respectively. The production and release of endogenous opioids and inflammatory cytokines was assessed in immunoassays. RESULTS: In ACIA, mice display persistent mechanical allodynia and thermal hyperalgesia for more than 2 months after induction of arthritis. The blockade of peripheral opioid receptors with naloxone-methiodide (NLXM) transiently increased thermal hyperalgesia, indicating that endogenous opioid peptides were released in the arthritic joint to inhibit pain. CD8+ T cell depletion did not affect autoantibody formation or severity of joint inflammation, but serum levels of the pro-inflammatory cytokines TNFα and IL-17 were increased. The release of opioid peptides from explanted arthritic knee cells and the NLXM effect were significantly reduced in the absence of CD8+ T cells. CONCLUSIONS: We have successfully modeled the development of chronic pain, a hallmark of RA, in ACIA. Furthermore, we detected a yet unknown protective role of CD8+ T cells in chronic ACIA since pro-inflammatory cytokines rose and opioid peptide release decreased in the absence of these cells.
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Analgésicos Opioides/metabolismo , Artritis Experimental/complicaciones , Artritis Experimental/patología , Linfocitos T CD8-positivos/patología , Inflamación/etiología , Animales , Anticuerpos/efectos adversos , Artritis Experimental/inmunología , Antígenos CD8/inmunología , Linfocitos T CD8-positivos/metabolismo , Colágeno/toxicidad , Modelos Animales de Enfermedad , Encefalinas/metabolismo , Femenino , Adyuvante de Freund/inmunología , Adyuvante de Freund/toxicidad , Lateralidad Funcional , Hiperalgesia/etiología , Inflamación/patología , Metionina/metabolismo , Ratones , Ratones Endogámicos BALB C , Dimensión del Dolor , Umbral del Dolor/fisiología , Factores de TiempoRESUMEN
The biochemical analysis of human cell membrane proteins remains a challenging task due to the difficulties in producing sufficient quantities of functional protein. G protein-coupled receptors (GPCRs) represent a main class of membrane proteins and drug targets, which are responsible for a huge number of signaling processes regulating various physiological functions in living cells. To circumvent the current bottlenecks in GPCR studies, we propose the synthesis of GPCRs in eukaryotic cell-free systems based on extracts generated from insect (Sf21) cells. Insect cell lysates harbor the fully active translational and translocational machinery allowing posttranslational modifications, such as glycosylation and phosphorylation of de novo synthesized proteins. Here, we demonstrate the production of several GPCRs in a eukaryotic cell-free system, performed within a short time and in a cost-effective manner. We were able to synthesize a variety of GPCRs ranging from 40 to 133 kDa in an insect-based cell-free system. Moreover, we have chosen the µ opioid receptor (MOR) as a model protein to analyze the ligand binding affinities of cell-free synthesized MOR in comparison to MOR expressed in a human cell line by "one-point" radioligand binding experiments. Biotechnol. Bioeng. 2017;114: 2328-2338. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.
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Fraccionamiento Celular/métodos , Mejoramiento Genético/métodos , Insectos/metabolismo , Ingeniería de Proteínas/métodos , Receptores Acoplados a Proteínas G/biosíntesis , Animales , Sistema Libre de Células/química , Sistema Libre de Células/metabolismo , Células HEK293 , Humanos , Insectos/química , Receptores Acoplados a Proteínas G/químicaRESUMEN
Antibody derivatives, such as the single chain fragment variable (scFv), can be developed as diagnostic and therapeutic tools in cancer research, especially in the form of fusion proteins. Such derivatives are easier to produce and modify than monoclonal antibodies (mAbs) and achieve better tissue/tumor penetration. The genetic modification of scFvs is also much more straightforward than the challenging chemical modification of mAbs. Therefore, we constructed two scFvs derived from the approved monoclonal antibodies cetuximab (scFv2112) and panitumumab (scFv1711), both of which are specific for the epidermal growth factor receptor (EGFR), a well-characterized solid tumor antigen. Both scFvs were genetically fused to the SNAP-tag, an engineered version of the human DNA repair enzyme O(6)-alkylguanine DNA alkyltransferase that allows the covalent coupling of benzylguanine (BG)-modified substrates such as fluorescent dyes. The SNAP-tag achieves controllable and irreversible protein modification and is an important tool for experimental studies in vitro and in vivo. The affinity constant of a scFv is a key functional parameter, especially in the context of a fusion protein. Therefore, we developed a method to define the affinity constants of scFv-SNAP fusion proteins by surface plasmon resonance (SPR) spectroscopy. We could confirm that both scFvs retained their functionality after fusion to the SNAP-tag in a variety of procedures and assays, including ELISA, flow cytometry, and confocal microscopy. The experimental procedures described herein, and the new protocol for affinity determination by SPR spectroscopy, are suitable for the preclinical evaluation of diverse antibody formats and derivatives.
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Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/metabolismo , Anticuerpos de Cadena Única/química , Anticuerpos de Cadena Única/metabolismo , Línea Celular Tumoral , Receptores ErbB/metabolismo , Humanos , PanitumumabRESUMEN
Antibody-based immunotherapy of leukemia requires the targeting of specific antigens on the surface of blasts. The Fc gamma receptor (CD64) has been investigated in detail, and CD64-targeting immunotherapy has shown promising efficacy in the targeted ablation of acute myeloid leukemia (AML), acute myelomonocytic leukemia (AMML) and chronic myeloid leukemia cells (CML). Here we investigate for the first time the potential of FcαRI (CD89) as a new target antigen expressed by different myeloid leukemic cell populations. For specific targeting and killing, we generated a recombinant fusion protein comprising an anti-human CD89 single-chain Fragment variable and the well-characterized truncated version of the potent Pseudomonas aeruginosa exotoxin A (ETA'). Our novel therapeutic approach achieved in vitro EC50 values in range 0.2-3 nM depending on the applied stimuli, that is, interferon gamma or tumor necrosis factor alpha. We also observed a dose-dependent apoptosis-mediated cytotoxicity, which resulted in the elimination of up to 90% of the target cells within 72 hr. These findings were also confirmed ex vivo using leukemic primary cells from peripheral blood samples of three previously untreated patients. We conclude that CD89-specific targeting of leukemia cell lines can be achieved in vitro and that the efficient elimination of leukemic primary cells supports the potential of CD89-ETA' as a potent, novel immunotherapeutic agent.
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Antígenos CD/inmunología , Antígenos de Neoplasias/inmunología , Leucemia Mieloide/inmunología , Receptores Fc/inmunología , ADP Ribosa Transferasas/inmunología , Anciano , Apoptosis/inmunología , Toxinas Bacterianas/inmunología , Exotoxinas/inmunología , Femenino , Células HL-60 , Humanos , Inmunoterapia/métodos , Interferón gamma/inmunología , Masculino , Persona de Mediana Edad , Proteínas Recombinantes de Fusión/inmunología , Células Tumorales Cultivadas , Factor de Necrosis Tumoral alfa/inmunología , Células U937 , Factores de Virulencia/inmunología , Exotoxina A de Pseudomonas aeruginosaRESUMEN
Previous work has indicated that surface imprinted polymers (SIPs) allow for highly specific cell detection through macromolecular cell imprints. The combination of SIPs with a heat-transfer-based read-out technique has led to the development of a selective, label-free, low-cost, and user-friendly cell detection assay. In this study, the breast cancer cell line ZR-75-1 is used to assess the potential of the platform for monitoring the quality of a cell culture in time. For this purpose, we show that the proposed methodology is able to discriminate between the original cell line (adherent growth, ZR-75-1a) and a descendant cell line (suspension growth, ZR-75-1s). Moreover, ZR-75-1a cells were cultured for a prolonged period of time and analyzed using the heat-transfer method (HTM) at regular time intervals. The results of these experiments demonstrate that the thermal resistance (Rth) signal decays after a certain number of cell culture passages. This can likely be attributed to a compromised quality of the cell culture due to cross-contamination with the ZR-75-1s cell line, a finding that was confirmed by classical STR DNA profiling. The cells do not express the same functional groups on their membrane, resulting in a weaker bond between cell and imprint, enabling cell removal by mechanical friction, provided by flushing the measuring chamber with buffer solution. These findings were further confirmed by HTM and illustrate that the biomimetic sensor platform can be used as an assay for monitoring the quality of cell cultures in time.
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Biomimética/métodos , Calor , Impresión Molecular , Sondas Moleculares/síntesis química , Polímeros/síntesis química , Técnicas de Cultivo de Célula , Línea Celular Tumoral , Humanos , Repeticiones de Microsatélite , Sondas Moleculares/metabolismo , Polímeros/metabolismo , Control de Calidad , Propiedades de SuperficieRESUMEN
PURPOSE: Ginkgo extract EGb 761 and cholinesterase inhibitors have been shown to be effective in the treatment of dementia patients. In addition to neuroprotective effects, Ginkgo extract EGb 761 has been reported to elevate brain levels of certain neurotransmitters such as dopamine, noradrenaline, and acetylcholine. In the present study, we investigated the impact of EGb 761, donepezil and the combination of both drugs on the central cholinergic system in aged rats. METHODS: 24 month old rats received EGb 761 (100 mg/kg/day), donepezil (1.5 mg/kg/day), the combination of both drugs or vehicle control by oral gavage for 14 days. We used microdialysis in rat hippocampus to monitor extracellular concentrations of acetylcholine (ACh), choline, glucose and lactate. Brain homogenates were prepared to measure activities of acetylcholinesterase (AChE), choline acetyltransferase (ChAT) and high affinity choline uptake (HACU). RESULTS: While EGb 761 alone had no effect, donepezil and the combination of donepezil and EGb 761 increased basal ACh levels by 2- to 3-fold. Concomitantly, significant reductions of AChE and HACU were measured in both groups. No differences were seen between donepezil and the combination in these parameters. Treatment with EGb 761 decreased extracellular choline release and showed a tendency to moderately elevate ChAT activity. CONCLUSIONS: We found that donepezil and EGb 761 do not display a pharmacological interaction when given together. Adding EGb 761 did not modify the effects of donepezil on the hippocampal cholinergic system. Reduced choline levels indicate neuroprotective properties of EGb 761. Therefore, the combination of EGb 761 and donepezil may be beneficial in the treatment of Alzheimer's disease (AD). This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.
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Inhibidores de la Colinesterasa/farmacología , Indanos/farmacología , Fármacos Neuroprotectores/farmacología , Piperidinas/farmacología , Extractos Vegetales/farmacología , Acetilcolina/metabolismo , Envejecimiento , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Colina/metabolismo , Colina O-Acetiltransferasa/metabolismo , Inhibidores de la Colinesterasa/administración & dosificación , Donepezilo , Interacciones Farmacológicas , Ginkgo biloba , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Indanos/administración & dosificación , Masculino , Microdiálisis , Fármacos Neuroprotectores/administración & dosificación , Piperidinas/administración & dosificación , Extractos Vegetales/administración & dosificación , Ratas , Ratas Sprague-DawleyRESUMEN
Transient receptor potential vanilloid 1 (TRPV1) is a nonselective ligand-gated cation channel responding to noxious heat, protons, and chemicals such as capsaicin. TRPV1 is expressed in sensory neurons and plays a critical role in pain associated with tissue injury, inflammation, and nerve lesions. Transient receptor potential ankyrin 1 (TRPA1) is coexpressed with TRPV1. It is activated by compounds that cause a burning sensation (e.g., mustard oil) and, indirectly, by components of the inflammatory milieu eliciting nociceptor excitation and pain hypersensitivity. Previous studies indicate an interaction of TRPV1 and TRPA1 signaling pathways. Here we sought to examine the molecular mechanisms underlying such interactions in nociceptive neurons. We first excluded physical interactions of both channels using radioligand binding studies. By microfluorimetry, electrophysiological experiments, cAMP measurements, and site-directed mutagenesis we found a sensitization of TRPV1 after TRPA1 stimulation with mustard oil in a calcium and cAMP/protein kinase A (PKA)-dependent manner. TRPA1 stimulation enhanced TRPV1 phosphorylation via the putative PKA phosphorylation site serine 116. We also detected calcium-sensitive increased TRPV1 activity after TRPA1 activation in dorsal root ganglion neurons. The inhibition of TRPA1 by HC-030031 (1,2,3,6-tetrahydro-1,3-dimethyl-N-[4-(1-methylethyl)phenyl]-2,6-dioxo-7H-purine-7-acetamide, 2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide) after its initial stimulation (and the calcium-insensitive TRPA1 mutant D477A) still showed increased capsaicin-induced TRPV1 activity. This excludes a calcium-induced additive TRPA1 current after TRPV1 stimulation. Our study shows sensitization of TRPV1 via activation of TRPA1, which involves adenylyl cyclase, increased cAMP, subsequent translocation and activation of PKA, and phosphorylation of TRPV1 at PKA phosphorylation residues. This suggests that cross-sensitization of TRP channels contributes to enhanced pain sensitivity in inflamed tissues.
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Canales de Calcio/fisiología , Proteínas del Tejido Nervioso/fisiología , Canales Catiónicos TRPV/fisiología , Canales de Potencial de Receptor Transitorio/fisiología , Adenilil Ciclasas/fisiología , Calcio/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/fisiología , Células HEK293 , Humanos , Fosforilación , Canal Catiónico TRPA1RESUMEN
Surface-imprinted polymers allow for specific cell detection based on simultaneous recognition of the cell shape, cell size, and cell membrane functionalities by macromolecular cell imprints. In this study, the specificity of detection and the detection sensitivity for target cells within a pool of non-target cells were analyzed for a cell-specific surface-imprinted polymer combined with a heat-transfer-based read-out technique (HTM). A modified Chinese hamster ovarian cell line (CHO-ldlD) was used as a model system on which the transmembrane protein mucin-1 (MUC1) could be excessively expressed and for which the occurrence of MUC1 glycosylation could be controlled. In specific cancer cells, the overexpressed MUC1 protein typically shows an aberrant apical distribution and glycosylation. We show that surface-imprinted polymers discriminate between cell types that (1) only differ in the expression of a specific membrane protein (MUC1) or (2) only differ in the membrane protein being glycosylated or not. Moreover, surface-imprinted polymers of cells carrying different glycoforms of the same membrane protein do target both types of cells. These findings illustrate the high specificity of cell detection that can be reached by the structural imprinting of cells in polymer layers. Competitiveness between target and non-target cells was proven to negatively affect the detection sensitivity of target cells. Furthermore, we show that the detection sensitivity can be increased significantly by repetitively exposing the surface to the sample and eliminating non-specifically bound cells by flushing between consecutive cell exposures.
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Calor , Impresión Molecular , Poliuretanos/química , Animales , Células CHO , Células Cultivadas , Cricetulus , Glicosilación , Microscopía Fluorescente , Mucina-1/biosíntesis , Mucina-1/química , Mucina-1/metabolismo , Poliuretanos/metabolismo , Propiedades de SuperficieRESUMEN
The concept that the immune system can communicate with peripheral sensory neurons to modulate pain is based mostly on documented interactions between opioid ligands and receptors. Such findings may have broad implications for the development of safer pain medication. Innovative strategies take into account that analgesics should be particularly active in pathological states rather than producing a general suppression of the central nervous system, as with conventional morphine- or cannabinoid-like drugs. Inflammation of peripheral tissue leads to increased functionality of opioid receptors on peripheral sensory neurons and to local production of endogenous opioid peptides. In addition, endocannabinoids were detected in leukocytes, but their role in pain modulation has yet to be addressed. Future aims include the development of peripherally restricted opioid agonists, selective targeting of opioid-containing immune cells to sites of painful injury, and the augmentation of peripheral ligand and receptor synthesis (e.g., by gene therapy). Similar approaches may be pursued for cannabinoids. The ultimate goal is to avoid detrimental side effects of currently available analgesics such as respiratory depression, cognitive impairment, addiction, gastrointestinal bleeding, and thromboembolic complications.
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Sistema Inmunológico/fisiología , Manejo del Dolor , Dolor/tratamiento farmacológico , Células Receptoras Sensoriales/inmunología , Humanos , Sistema Inmunológico/efectos de los fármacos , Sistema Inmunológico/patología , Inflamación/inmunología , Inflamación/patología , Dolor/inmunología , Receptores Opioides/efectos de los fármacos , Receptores Opioides/inmunología , Células Receptoras Sensoriales/efectos de los fármacos , Células Receptoras Sensoriales/patologíaAsunto(s)
Antígenos CD/inmunología , Inmunoterapia/métodos , Inmunotoxinas/uso terapéutico , Leucemia Mieloide/terapia , Receptores Fc/inmunología , Apoptosis/efectos de los fármacos , Humanos , Inmunotoxinas/farmacología , Leucemia Mieloide/patología , Proteínas Recombinantes de Fusión/farmacología , Proteínas Recombinantes de Fusión/uso terapéutico , Células Tumorales CultivadasRESUMEN
Inflammatory pain can be controlled by endogenous opioid peptides. Here we blocked the degradation of opioids in peripheral injured tissue to locally augment this physiological system. In rats with hindpaw inflammation, inhibitors of aminopeptidase N (APN; bestatin) or neutral endopeptidase (NEP; thiorphan), and a dual inhibitor, NH(2)-CH-Ph-P(O)(OH)CH(2)-CH-CH(2)Ph(p-Ph)-CONH-CH-CH(3)-COOH (P8B), were applied to injured paws. Combined bestatin (1.25-5 mg)/thiorphan (0.2-0.8 mg) or P8B (0.0625-1 mg) alone elevated mechanical nociceptive thresholds to 307 and 227% of vehicle-treated controls, respectively. This analgesia was abolished by antibodies to methionine-enkephalin, leucine-enkephalin, and dynorphin A 1-17, by peripherally restricted and by selective µ-, δ-, and κ-opioid receptor antagonists. Flow cytometry and photospectrometry revealed expression and metabolic activity of APN and NEP on macrophages, granulocytes, and sciatic nerves from inflamed tissue. Radioimmunoassays showed that inhibition of leukocytic APN and NEP by bestatin (5-500 µM)/thiorphan (1-100 µM) combinations or by P8B (1-100 µM) prevented the degradation of enkephalins. Blockade of neuronal peptidases by bestatin (0.5-10 mM)/thiorphan (0.1-5 mM) or by P8B (0.1-10 mM) additionally hindered dynorphin A 1-17 catabolism. Thus, leukocytes and peripheral nerves are important sources of APN and NEP in inflamed tissue, and their blockade promotes peripheral opioid analgesia.
Asunto(s)
Antígenos CD13/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Inflamación/prevención & control , Neprilisina/antagonistas & inhibidores , Dolor/prevención & control , Alanina/análogos & derivados , Alanina/farmacología , Secuencia de Aminoácidos , Animales , Anticuerpos/inmunología , Anticuerpos/farmacología , Antígenos CD13/metabolismo , Relación Dosis-Respuesta a Droga , Dinorfinas/inmunología , Dinorfinas/metabolismo , Dinorfinas/farmacología , Encefalina Leucina/inmunología , Encefalina Leucina/metabolismo , Encefalina Leucina/farmacología , Encefalina Metionina/inmunología , Encefalina Metionina/metabolismo , Encefalina Metionina/farmacología , Citometría de Flujo , Miembro Posterior/efectos de los fármacos , Miembro Posterior/inervación , Miembro Posterior/fisiopatología , Inflamación/complicaciones , Inflamación/enzimología , Leucina/análogos & derivados , Leucina/farmacología , Leucocitos/efectos de los fármacos , Leucocitos/enzimología , Masculino , Antagonistas de Narcóticos , Neprilisina/metabolismo , Neuronas/efectos de los fármacos , Neuronas/enzimología , Péptidos Opioides/inmunología , Péptidos Opioides/metabolismo , Péptidos Opioides/farmacología , Dolor/complicaciones , Dolor/enzimología , Umbral del Dolor/efectos de los fármacos , Ácidos Fosfínicos/farmacología , Ratas , Ratas Wistar , Receptores Opioides/metabolismo , Tiorfan/farmacologíaRESUMEN
N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide is a newly-designed pain killer selectively activating G-protein-coupled mu-opioid receptors (MOR) in acidic injured tissues, and therefore devoid of central side effects which are typically elicited at normal pH values in healthy tissues. However, the neuronal mechanisms underlying NFEPP's antinociceptive effects were not examined in detail so far. Voltage-dependent Ca2+ channels (VDCCs) in nociceptive neurons play a major role in the generation and inhibition of pain. In this study, we focused on the effects of NFEPP on calcium currents in rat dorsal root ganglion (DRG) neurons. The inhibitory role of the G-protein subunits Gi/o and Gßγ on VDCCs was investigated using the blockers pertussis toxin and gallein, respectively. GTPγS binding, calcium signals and MOR phosphorylation were also investigated. All experiments were performed at acidic and normal pH values using NFEPP in comparison to the conventional opioid agonist fentanyl. At low pH, NFEPP produced more efficient G-protein activation in transfected HEK293 cells and significantly reduced VDCCs in depolarized DRG neurons. The latter effect was mediated by Gßγ subunits, and NFEPP-mediated MOR phosphorylation was pH-dependent. Fentanyl's responses were not affected by pH changes. Our data indicate that NFEPP-induced MOR signaling is more effective at low pH and that the inhibition of calcium channels in DRG neurons underlies NFEPP's antinociceptive actions.
RESUMEN
We previously reported the successful design, synthesis and testing of the prototype opioid painkiller NFEPP that does not elicit adverse side effects. The design process of NFEPP was based on mathematical modelling of extracellular interactions between G-protein coupled receptors (GPCRs) and ligands, recognizing that GPCRs function differently under pathological versus healthy conditions. We now present an additional and novel stochastic model of GPCR function that includes intracellular dissociation of G-protein subunits and modulation of plasma membrane calcium channels and their dependence on parameters of inflamed and healthy tissue (pH, radicals). The model is validated against in vitro experimental data for the ligands NFEPP and fentanyl at different pH values and radical concentrations. We observe markedly reduced binding affinity and calcium channel inhibition for NFEPP at normal pH compared to lower pH, in contrast to the effect of fentanyl. For increasing radical concentrations, we find enhanced constitutive G-protein activation but reduced ligand binding affinity. Assessing the different effects, the results suggest that, compared to radicals, low pH is a more important determinant of overall GPCR function in an inflamed environment. Future drug design efforts should take this into account.