RESUMO
A3 adenosine receptor (A3AR) positive allosteric modulators (PAMs) (2,4-disubstituted-1H-imidazo[4,5-c]quinolin-4-amines) allosterically increase the Emax of A3AR agonists, but not potency, due to concurrent orthosteric antagonism. Following mutagenesis/homology modeling of the proposed lipid-exposed allosteric binding site on the cytosolic side, we functionalized the scaffold, including heteroatom substitutions and exocyclic phenylamine extensions, to increase allosteric binding. Strategically appended linear alkyl-alkynyl chains with terminal amino/guanidino groups improved allosteric effects at both human and mouse A3ARs. The chain length, functionality, and attachment position were varied to modulate A3AR PAM activity. For example, 26 (MRS8247, p-alkyne-linked 8 methylenes) and homologues increased agonist Cl-IB-MECA's Emax and potency ([35S]GTPγS binding). The putative mechanism involves a flexible, terminally cationic chain penetrating the lipid environment for stable electrostatic anchoring to cytosolic phospholipid head groups, suggesting "lipid trolling", supported by molecular dynamic simulation of the active-state model. Thus, we have improved A3AR PAM activity through rational design based on an extrahelical, lipidic binding site.
Assuntos
Agonistas do Receptor A3 de Adenosina , Receptor A3 de Adenosina , Humanos , Regulação Alostérica/efeitos dos fármacos , Animais , Receptor A3 de Adenosina/metabolismo , Receptor A3 de Adenosina/química , Camundongos , Agonistas do Receptor A3 de Adenosina/farmacologia , Agonistas do Receptor A3 de Adenosina/química , Relação Estrutura-Atividade , Lipídeos/química , Cricetulus , Sítio Alostérico , Quinolinas/química , Quinolinas/farmacologia , Quinolinas/síntese química , Células CHORESUMO
Cardiovascular diseases (CVDs), particularly heart failure, are major contributors to early mortality globally. Heart failure poses a significant public health problem, with persistently poor long-term outcomes and an overall unsatisfactory prognosis for patients. Conventionally, treatments for heart failure have focused on lowering blood pressure; however, the development of more potent therapies targeting hemodynamic parameters presents challenges, including tolerability and safety risks, which could potentially restrict their clinical effectiveness. Adenosine has emerged as a key mediator in CVDs, acting as a retaliatory metabolite produced during cellular stress via ATP metabolism, and works as a signaling molecule regulating various physiological processes. Adenosine functions by interacting with different adenosine receptor (AR) subtypes expressed in cardiac cells, including A1AR, A2AAR, A2BAR, and A3AR. In addition to A1AR, A3AR has a multifaceted role in the cardiovascular system, since its activation contributes to reducing the damage to the heart in various pathological states, particularly ischemic heart disease, heart failure, and hypertension, although its role is not as well documented compared to other AR subtypes. Research on A3AR signaling has focused on identifying the intricate molecular mechanisms involved in CVDs through various pathways, including Gi or Gq protein-dependent signaling, ATP-sensitive potassium channels, MAPKs, and G protein-independent signaling. Several A3AR-specific agonists, such as piclidenoson and namodenoson, exert cardioprotective impacts during ischemia in the diverse animal models of heart disease. Thus, modulating A3ARs serves as a potential therapeutic approach, fueling considerable interest in developing compounds that target A3ARs as potential treatments for heart diseases.
Assuntos
Cardiopatias , Receptor A3 de Adenosina , Transdução de Sinais , Humanos , Animais , Transdução de Sinais/efeitos dos fármacos , Receptor A3 de Adenosina/metabolismo , Cardiopatias/metabolismo , Cardiopatias/tratamento farmacológico , Agonistas do Receptor A3 de Adenosina/uso terapêutico , Agonistas do Receptor A3 de Adenosina/farmacologia , Adenosina/metabolismoRESUMO
The A3 adenosine receptor (AR) is an important inflammatory and immunological target. However, the underlying mechanisms are not fully understood. Here, we report the gene regulation in HL-60 cells treated acutely with highly selective A3AR agonist MRS5698, positive allosteric modulator (PAM) LUF6000, or both. Both pro- and anti-inflammatory genes, such as IL-1a, IL-1ß, and NFκBIZ, are significantly upregulated. During our observations, LUF6000 alone produced a lesser effect, while the MRS5698 + LUF6000 group demonstrated generally greater effects than MRS5698 alone, consistent with allosteric enhancement. The number of genes up- and down-regulated are similar. Pathway analysis highlighted the critical involvement of signaling molecules, including IL-6 and IL-17. Important upstream regulators include IL-1a, IL-1ß, TNF-α, NF-κB, etc. PPAR, which modulates eicosanoid metabolism, was highly downregulated by the A3AR agonist. Considering previous pharmacological results and mathematical modeling, LUF6000's small enhancement of genetic upregulation suggested that MRS5698 is a nearly full agonist, which we demonstrated in both cAMP and calcium assays. The smaller effect of LUF6000 on MRS5698 in comparison to its effect on Cl-IB-MECA was shown in both HL-60 cells endogenously expressing the human (h) A3AR and in recombinant hA3AR-expressing CHO cells, consistent with its HL-60 cell genetic regulation patterns. In summary, by using both selective agonists and PAM, we identified genes that are closely relevant to immunity and inflammation to be regulated by A3AR in differentiated HL-60 cells, a cell model of neutrophil function. In addition, we demonstrated the previously uncharacterized allosteric signaling-enhancing effect of LUF6000 in cells endogenously expressing the hA3AR.
Assuntos
Agonistas do Receptor A3 de Adenosina , Receptor A3 de Adenosina , Humanos , Células HL-60 , Receptor A3 de Adenosina/metabolismo , Receptor A3 de Adenosina/genética , Agonistas do Receptor A3 de Adenosina/farmacologia , Regulação Alostérica/efeitos dos fármacos , Adenosina/análogos & derivados , Adenosina/farmacologiaRESUMO
Interest has been focused in recent years on the analgesic effects exerted by adenosine and its receptors, A1, A2A, A2B, and A3 adenosine receptor (AR) subtypes, in different in vivo models of chronic pain. In particular, it was demonstrated that selective A3AR agonists reduced pro-nociceptive N-type Ca2+ channels in dorsal root ganglion (DRG) neurons isolated from rats and, by this mechanism, inhibit post inflammatory visceral hypersensitivity. In the present study, we investigate the effect of a previously reported irreversibly binding A3AR agonist, ICBM, on Ca2+ currents (ICa) in rat DRG neurons. Present data demonstrate that ICBM, an isothiocyanate derivative designed for covalent binding to the receptor, concentration-dependently inhibits ICa. This effect is irreversible, since it persists after drug removal, differently from the prototypical A3AR agonist, Cl-IB-MECA. ICBM pre-exposure inhibits the effect of a subsequent Cl-IB-MECA application. Thus, covalent A3AR agonists such as ICBM may represent an innovative, beneficial, and longer-lasting strategy to achieve efficacious chronic pain control versus commonly used, reversible, A3AR agonists. However, the possible limitations of this drug and other covalent drugs may be, for example, a characteristic adverse effect profile, suggesting that more pre-clinical studies are needed.
Assuntos
Dor Crônica , Gânglios Espinais , Ratos , Animais , Gânglios Espinais/metabolismo , Dor Crônica/metabolismo , Neurônios/metabolismo , Adenosina/metabolismo , Receptores Purinérgicos P1/metabolismo , Receptor A3 de Adenosina/metabolismo , Agonistas do Receptor A3 de Adenosina/farmacologiaRESUMO
The adenosine A3 receptor (A3AR) is a G protein-coupled receptor (GPCR) that exerts immunomodulatory effects in pathophysiological conditions such as inflammation and cancer. Thus far, studies toward the downstream effects of A3AR activation have yielded contradictory results, thereby motivating the need for further investigations. Various chemical and biological tools have been developed for this purpose, ranging from fluorescent ligands to antibodies. Nevertheless, these probes are limited by their reversible mode of binding, relatively large size, and often low specificity. Therefore, in this work, we have developed a clickable and covalent affinity-based probe (AfBP) to target the human A3AR. Herein, we show validation of the synthesized AfBP in radioligand displacement, SDS-PAGE, and confocal microscopy experiments as well as utilization of the AfBP for the detection of endogenous A3AR expression in flow cytometry experiments. Ultimately, this AfBP will aid future studies toward the expression and function of the A3AR in pathologies.
Assuntos
Adenosina , Receptor A3 de Adenosina , Humanos , Adenosina/farmacologia , Receptor A3 de Adenosina/metabolismo , Expressão Gênica , Receptores Acoplados a Proteínas G , Agonistas do Receptor A3 de Adenosina/farmacologiaRESUMO
We previously reported 1H-imidazo[4,5-c]quinolin-4-amines as A3 adenosine receptor (A3AR) positive allosteric modulators (PAMs). A3AR agonists, but not PAMs, are in clinical trials for inflammatory diseases and liver conditions. We synthesized new analogues to distinguish 2-cyclopropyl antagonist 17 (orthosteric interaction demonstrated by binding and predicted computationally) from PAMs (derivatives with large 2-alkyl/cycloalkyl/bicycloalkyl groups). We predicted PAM binding at a hydrophobic site on the A3AR cytosolic interface. Although having low Caco-2 permeability and high plasma protein binding, hydrophobic 2-cyclohept-4-enyl-N-3,4-dichlorophenyl, MRS7788 18, and 2-heptan-4-yl-N-4-iodophenyl, MRS8054 39, derivatives were orally bioavailable in rat. 2-Heptan-4-yl-N-3,4-dichlorophenyl 14 and 2-cyclononyl-N-3,4-dichlorophenyl 20 derivatives and 39 greatly enhanced Cl-IB-MECA-stimulated [35S]GTPγS binding Emax, with only 12b trending toward decreasing the agonist EC50. A feasible route for radio-iodination at the p-position of a 4-phenylamino substituent suggests a potential radioligand for allosteric site binding. Herein, we advanced an allosteric approach to developing A3AR-activating drugs that are potentially event- and site-specific in action.
Assuntos
Agonistas do Receptor A3 de Adenosina , Receptores Purinérgicos P1 , Humanos , Ratos , Animais , Células CACO-2 , Regulação Alostérica , Receptores Purinérgicos P1/metabolismo , Agonistas do Receptor A3 de Adenosina/farmacologia , AminasRESUMO
The A3 adenosine receptor (A3AR) is overexpressed in pathological human cells. Piclidenoson and namodenoson are A3AR agonists with high affinity and selectivity to A3AR. Both induce apoptosis of cancer and inflammatory cells via a molecular mechanism entailing deregulation of the Wnt and the NF-κB signaling pathways. Our company conducted phase I studies showing the safety of these 2 molecules. In the phase II studies in psoriasis patients, piclidenoson was safe and demonstrated efficacy manifested in significant improvements in skin lesions. Namodenoson is currently being developed to treat liver cancer, where prolonged overall survival was observed in patients with advanced liver disease and a Child-Pugh B score of 7. A pivotal phase III study in this patient population has been approved by the FDA and the EMA and is currently underway. Namodenoson is also being developed to treat non-alcoholic steatohepatitis (NASH). A Phase IIa study has been successfully concluded and showed that namodenoson has anti-inflammatory, anti-fibrosis, and anti-steatosis effects. A phase IIb study in NASH is currently enrolling patients. In conclusion, A3AR agonists are promising drug candidates in advanced stages of clinical development and demonstrate safety and efficacy in their targeted indications.
Assuntos
Hepatopatia Gordurosa não Alcoólica , Agonistas do Receptor A3 de Adenosina/farmacologia , Agonistas do Receptor A3 de Adenosina/uso terapêutico , Anti-Inflamatórios/farmacologia , Ensaios Clínicos Fase II como Assunto , Humanos , NF-kappa B/metabolismo , Receptor A3 de Adenosina/metabolismo , Transdução de SinaisRESUMO
Ligands of the Gi protein-coupled adenosine A3 receptor (A3R) are receiving increasing interest as attractive therapeutic tools for the treatment of a number of pathological conditions of the central and peripheral nervous systems (CNS and PNS, respectively). Their safe pharmacological profiles emerging from clinical trials on different pathologies (e.g., rheumatoid arthritis, psoriasis and fatty liver diseases) confer a realistic translational potential to these compounds, thus encouraging the investigation of highly selective agonists and antagonists of A3R. The present review summarizes information on the effect of latest-generation A3R ligands, not yet available in commerce, obtained by using different in vitro and in vivo models of various PNS- or CNS-related disorders. This review places particular focus on brain ischemia insults and colitis, where the prototypical A3R agonist, Cl-IB-MECA, and antagonist, MRS1523, have been used in research studies as reference compounds to explore the effects of latest-generation ligands on this receptor. The advantages and weaknesses of these compounds in terms of therapeutic potential are discussed.
Assuntos
Agonistas do Receptor A3 de Adenosina , Artrite Reumatoide , Agonistas do Receptor A3 de Adenosina/farmacologia , Agonistas do Receptor A3 de Adenosina/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Humanos , Ligantes , Sistema Nervoso Periférico , Receptores Purinérgicos P1RESUMO
BACKGROUND: Chronic cerebral ischemia (CCI) is a major cause of subcortical ischemic vascular dementia. Here, we examined the neuroprotective action of the A3 adenosine receptor agonist N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (IB-MECA) on white matter lesions following CCI. METHODS: A CCI mouse model was established using unilateral common carotid artery occlusion. IB-MECA and 3-propyl-6-ethyl-5-[(ethylthio)carbonyl]-2 phenyl-4-propyl-3-pyridine carboxylate (MRS1523), an antagonist of the A3 adenosine receptor, were administered by intraperitoneal injection. The inhibitory avoidance test was used to examine changes in memory performance. Microtubule-associated protein 2 (MAP-2) and neurofilament were assessed by immunohistochemistry, while expressions of phosphorylated extracellular signal-regulated kinase (ERK), ERK, interferon-beta (IFN-ß), and glial fibrillary acidic protein (GFAP) were assessed by western blot assay. RESULTS: The memory retention score was reduced in vehicle-treated mice compared with IB-MECA-treated (p < 0.05) mice. Compared to sham-operated mice, p-ERK, GFAP and IFN-ß were increased, while MAP-2 and neurofilament were reduced in vehicle-treated mice (p < 0.01 for each). IB-MECA reduced ERK phosphorylation (p < 0.01) and GFAP expression (p < 0.05), but upregulated MAP-2 and IFN-ß (p < 0.01 for both), compared with vehicle. MRS1523 suppressed the effects of IB-MECA on the memory deficit, ERK phosphorylation, and on MAP-2, neurofilament, GFAP and IFN-ß levels. CONCLUSION: Our results suggest that A3 adenosine receptor stimulation ameliorates CCI-induced memory deficits, modulates the ERK signaling pathway, preserves MAP-2 and neurofilament expression, regulates GFAP expression, and upregulates the anti-inflammatory cytokine IFN-ß. Thus, the A3 adenosine receptor may be a therapeutic target for treatment of cognitive disorders and cerebral inflammatory diseases.
Assuntos
Adenosina , Isquemia Encefálica , Adenosina/análogos & derivados , Adenosina/farmacologia , Agonistas do Receptor A3 de Adenosina/farmacologia , Animais , Isquemia Encefálica/complicações , Isquemia Encefálica/tratamento farmacológico , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/etiologia , CamundongosRESUMO
Retinal ganglion cell (RGC) loss underlies several conditions which give rise to significant visual compromise, including glaucoma and ischaemic optic neuropathies. Neuroprotection of RGCs is a clinical well-defined unmet need in these diseases, and adenosine A3 receptor (A3R) activation emerges as a therapeutic pharmacological approach to protect RGCs. A porous biodegradable intraocular implant loaded with 2-Cl-IB-MECA (selective A3R agonist) was used as a strategy to protect RGCs. Drug-loaded PCL implants released 2-Cl-IB-MECA for an extended period and the released 2-Cl-IB-MECA limited glutamate-evoked calcium (Ca2+) rise in RGCs. Retinal thinning due to transient ischemia was not prevented by 2-Cl-IB-MECA-PCL implant. However, 2-Cl-IB-MECA-PCL implants decreased retinal cell death, promoted the survival of RGCs, preserved optic nerve structure and anterograde axonal transport. We further demonstrated that 2-Cl-IB-MECA-loaded PCL implants were able to enhance RGC function that was compromised by transient ischemia. Taking into consideration the beneficial effects afforded by 2-Cl-IB-MECA released from the PCL implant, this can be envisaged a good therapeutic strategy to protect RGCs.
Assuntos
Agonistas do Receptor A3 de Adenosina , Células Ganglionares da Retina , Agonistas do Receptor A3 de Adenosina/farmacologia , Humanos , Isquemia/tratamento farmacológico , Receptor A3 de Adenosina/metabolismo , Retina/metabolismoRESUMO
BACKGROUND: Lung cancer is the leading cause of mortality in India. Adenosine Receptor (AR) has emerged as a novel cancer-specific target. A3AR levels are upregulated in various tumor cells, which may mean that the specific AR may act as a biological marker and target specific ligands leading to cell growth inhibition. AIM: Our aim was to study the efficacy of the adenosine receptor agonist, AB MECA, by in silico (molecular docking) and in vitro (human cancer cells in xenografted mice) studies. METHODS: Molecular docking on the AB-meca and TNF-α was performed using AutoDock. A549 Human lung cancer 2 ×106 cells per microliter per mouse injected via intrabronchial route. Rat TNF-α level was assessed by ELISA method. RESULTS: AB Meca's predicted binding energy (beng) with TNF-α was 97.13 kcal/mol, and the compatible docking result of a small molecular inhibitor with TNF-α native ligand beng was 85.76 kcal/mol. In vivo, a single dose of lung cancer cell A549 is being researched to potentiate tumor development. Doxorubicin and A3AR agonist therapies have lowered TNF-alpha levels that were associated with in silico function. The A3AR Agonist showed myeloprotective effects in the groups treated along with doxorubicin. CONCLUSION: AB MECA's higher binding energy (beng) with TNF-α mediated reduction of tumor growth in our lung cancer in vivo model suggested that it may be an effective therapy for lung cancer.
Assuntos
Agonistas do Receptor A3 de Adenosina , Neoplasias Pulmonares , Adenosina/análogos & derivados , Agonistas do Receptor A3 de Adenosina/farmacologia , Animais , Modelos Animais de Doenças , Doxorrubicina , Xenoenxertos , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Camundongos , Simulação de Acoplamento Molecular , Ratos , Fator de Necrose Tumoral alfaRESUMO
Cisplatin is used to combat solid tumors. However, patients treated with cisplatin often develop cognitive impairments, sensorimotor deficits, and peripheral neuropathy. There is no FDA-approved treatment for these neurotoxicities. We investigated the capacity of a highly selective A3 adenosine receptor (AR) subtype (A3AR) agonist, MRS5980, to prevent and reverse cisplatin-induced neurotoxicities. MRS5980 prevented cisplatin-induced cognitive impairment (decreased executive function and impaired spatial and working memory), sensorimotor deficits, and neuropathic pain (mechanical allodynia and spontaneous pain) in both sexes. At the structural level, MRS5980 prevented the cisplatin-induced reduction in markers of synaptic integrity. In-situ hybridization detected Adora3 mRNA in neurons, microglia, astrocytes and oligodendrocytes. RNAseq analysis identified 164 genes, including genes related to mitochondrial function, of which expression was changed by cisplatin and normalized by MRS5980. Consistently, MRS5980 prevented cisplatin-induced mitochondrial dysfunction and decreased signs of oxidative stress. Transcriptomic analysis showed that the A3AR agonist upregulates genes related to repair pathways including NOTCH1 signaling and chromatin modification in the cortex of cisplatin-treated mice. Importantly, A3AR agonist administration after completion of cisplatin treatment resolved cognitive impairment, neuropathy and sensorimotor deficits. Our results highlight the efficacy of a selective A3AR agonist to prevent and reverse cisplatin-induced neurotoxicities via preventing brain mitochondrial damage and activating repair pathways. An A3AR agonist is already in cancer, clinical trials and our results demonstrate management of neurotoxic side effects of chemotherapy as an additional therapeutic benefit.
Assuntos
Agonistas do Receptor A3 de Adenosina/farmacologia , Antineoplásicos/efeitos adversos , Comprometimento Cognitivo Relacionado à Quimioterapia/tratamento farmacológico , Cisplatino/efeitos adversos , Receptor A3 de Adenosina/metabolismo , Memória Espacial/efeitos dos fármacos , Agonistas do Receptor A3 de Adenosina/uso terapêutico , Animais , Feminino , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Neurônios/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Dor/metabolismoRESUMO
Following our study of 4'-truncated (N)-methanocarba-adenosine derivatives that displayed unusually high mouse (m) A3AR affinity, we incorporated dopamine-related N6 substituents in the full agonist 5'-methylamide series. N6-(2-(4-Hydroxy-3-methoxy-phenyl)ethyl) derivative MRS7618 11 displayed Ki (nM) 0.563 at hA3AR (â¼20,000-fold selective) and 1.54 at mA3AR. 2-Alkyl ethers maintained A3 affinity, but with less selectivity than 2-alkynes. Parallel functional assays of G protein-dependent and ß-arrestin 2 (ßarr2)-dependent pathways indicate these are full agonists but not biased. Through use of computational modeling, we hypothesized that phenyl OH/OMe groups interact with polar residues, particularly Gln261, on the mA3AR extracellular loops as the basis for the affinity enhancement. Although the pharmacokinetics indicated facile clearance of parent O-methyl catechol nucleosides 21 and 31, prolonged mA3AR activation in vivo was observed in a hypothermia model, suggested potential formation of active metabolites through demethylation. Selected analogues induced mouse hypothermia following i.p. injection, indicative of peripheral A3AR agonism in vivo.
Assuntos
Agonistas do Receptor A3 de Adenosina/farmacologia , Dopamina/farmacologia , Receptor A3 de Adenosina/metabolismo , Agonistas do Receptor A3 de Adenosina/síntese química , Agonistas do Receptor A3 de Adenosina/química , Dopamina/síntese química , Dopamina/química , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
BACKGROUND AND PURPOSE: Treatment with A1R/A3R (adenosine A1 and A3 receptor) agonists in rodent models of acute ischemic stroke results in significantly reduced lesion volume, indicating activation of adenosine A1R or A3R is cerebroprotective. However, dosing and timing required for cerebroprotection has yet to be established, and whether adenosine A1R/A3R activation will lead to cerebroprotection in a gyrencephalic species has yet to be determined. METHODS: The current study used clinical study intervention timelines in a nonhuman primate model of transient, 4-hour middle cerebral artery occlusion to investigate a potential cerebroprotective effect of the dual adenosine A1R/A3R agonist AST-004. Bolus and then 22 hours intravenous infusion of AST-004 was initiated 2 hours after transient middle cerebral artery occlusion. Primary outcome measures included lesion volume, lesion growth kinetics, penumbra volume as well as initial pharmacokinetic-pharmacodynamic relationships measured up to 5 days after transient middle cerebral artery occlusion. Secondary outcome measures included physiological parameters and neurological function. RESULTS: Administration of AST-004 resulted in rapid and statistically significant decreases in lesion growth rate and total lesion volume. In addition, penumbra volume decline over time was significantly less under AST-004 treatment compared with vehicle treatment. These changes correlated with unbound AST-004 concentrations in the plasma and cerebrospinal fluid as well as estimated brain A1R and A3R occupancy. No relevant changes in physiological parameters were observed during AST-004 treatment. CONCLUSIONS: These findings suggest that administration of AST-004 and combined A1R/A3R agonism in the brain are efficacious pharmacological interventions in acute ischemic stroke and warrant further clinical evaluation.
Assuntos
Agonistas do Receptor A1 de Adenosina/uso terapêutico , Agonistas do Receptor A3 de Adenosina/uso terapêutico , Infarto Cerebral/diagnóstico por imagem , Infarto Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/tratamento farmacológico , Agonistas do Receptor A1 de Adenosina/sangue , Agonistas do Receptor A3 de Adenosina/sangue , Animais , Infarto Cerebral/sangue , Modelos Animais de Doenças , Macaca fascicularis , Imageamento por Ressonância Magnética/métodos , Masculino , Primatas , Acidente Vascular Cerebral/sangueRESUMO
A3 adenosine receptor (A3AR) agonists have emerged as potent relievers of neuropathic pain by a T cell-mediated production of IL-10. The H4 histamine receptor (H4R), also implicated in pain modulation, is expressed on T cells playing a preeminent role in its activation and release of IL-10. To improve the therapeutic opportunities, this study aimed to verify the hypothesis of a possible cross-talk between A3AR and H4R in the resolution of neuropathic pain. In the mouse model of Chronic Constriction Injury (CCI), the acute intraperitoneal co-administration of the A3AR agonist IB-MECA (0.5 mg/kg) and the H4R agonist VUF 8430 (10 mg/kg), were additive in counteracting mechano-allodynia increasing IL-10 plasma levels. In H4R-/- mice, IB-MECA activity was reduced, lower pain relief and lower modulation of plasma IL-1ß, TNF-α, IL-6 and IL-10 were shown. The complete anti-allodynia effect of IB-MECA in H4R-/- mice was restored after intravenous administration of CD4+ T cells obtained from naïve wild type mice. In conclusion, a role of the histaminergic system in the mechanism of A3AR-mediated neuropathic pain relief was suggested highlighting the driving force evoked by CD4+ T cells throughout IL-10 up-regulation.
Assuntos
Interleucina-10/genética , Neuralgia/tratamento farmacológico , Receptor A3 de Adenosina/genética , Receptores Histamínicos H4/genética , Adenosina/análogos & derivados , Adenosina/farmacologia , Agonistas do Receptor A3 de Adenosina/farmacologia , Animais , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Guanidinas/farmacologia , Humanos , Camundongos , Neuralgia/genética , Neuralgia/patologia , Receptores Histamínicos H4/agonistas , Tioureia/análogos & derivados , Tioureia/farmacologiaRESUMO
Agonists of the Gi protein-coupled A3 adenosine receptor (A3AR) have shown important pain-relieving properties in preclinical settings of several pain models. Active as a monotherapy against chronic pain, A3AR agonists can also be used in combination with classic opioid analgesics. Their safe pharmacological profile, as shown by clinical trials for other pathologies, i.e., rheumatoid arthritis, psoriasis and fatty liver diseases, confers a realistic translational potential, thus encouraging research studies on the molecular mechanisms underpinning their antinociceptive actions. A number of pathways, involving central and peripheral mechanisms, have been proposed. Recent evidence showed that the prototypical A3AR agonist Cl-IB-MECA and the new, highly selective, A3AR agonist MRS5980 inhibit neuronal (N-type) voltage-dependent Ca2+ currents in dorsal root ganglia, a known pain-related mechanism. Other proposed pathways involve reduced cytokine production, immune cell-mediated responses, as well as reduced microglia and astrocyte activation in the spinal cord. The aim of this review is to summarize up-to-date information on A3AR in the context of pain, including cellular and molecular mechanisms underlying this effect. Based on their safety profile shown in clinical trials for other pathologies, A3AR agonists are proposed as novel, promising non-narcotic agents for pain control.
Assuntos
Agonistas do Receptor A3 de Adenosina/uso terapêutico , Sinalização do Cálcio/efeitos dos fármacos , Gânglios Espinais , Dor , Receptor A3 de Adenosina/metabolismo , Animais , Astrócitos/metabolismo , Gânglios Espinais/metabolismo , Gânglios Espinais/fisiopatologia , Humanos , Microglia/metabolismo , Dor/tratamento farmacológico , Dor/metabolismo , Dor/fisiopatologiaRESUMO
Distinguishing compounds' agonistic or antagonistic behavior would be of great utility for the rational discovery of selective modulators. We synthesized truncated nucleoside derivatives and discovered 6c (Ki = 2.40 nM) as a potent human A3 adenosine receptor (hA3AR) agonist, and subtle chemical modification induced a shift from antagonist to agonist. We elucidated this shift by developing new hA3AR homology models that consider the pharmacological profiles of the ligands. Taken together with molecular dynamics (MD) simulation and three-dimensional (3D) structural network analysis of the receptor-ligand complex, the results indicated that the hydrogen bonding with Thr943.36 and His2727.43 could make a stable interaction between the 3'-amino group with TM3 and TM7, and the corresponding induced-fit effects may play important roles in rendering the agonistic effect. Our results provide a more precise understanding of the compounds' actions at the atomic level and a rationale for the design of new drugs with specific pharmacological profiles.
Assuntos
Agonistas do Receptor A3 de Adenosina/farmacologia , Antagonistas do Receptor A3 de Adenosina/farmacologia , Receptor A3 de Adenosina/química , Receptor A3 de Adenosina/metabolismo , Agonistas do Receptor A3 de Adenosina/química , Antagonistas do Receptor A3 de Adenosina/química , Animais , Células CHO , Domínio Catalítico , Cricetinae , Cricetulus , Células HEK293 , Humanos , Ligantes , Modelos Químicos , Modelos Moleculares , Simulação de Dinâmica Molecular , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
A series of adenosine and 2'-deoxyadenosine pairs modified with a 1,12-dicarba-closo-dodecaborane cluster or alternatively with a phenyl group at the same position was synthesized, and their affinity was determined at A1, A2A, A2B and A3 adenosine receptors (ARs). While AR affinity differences were noted, a general tendency to preferentially bind A3 AR over other ARs was observed for most tested ligands. In particular, 5'-ethylcarbamoyl-N6-(3-phenylpropyl)adenosine (18), N6-(3-phenylpropyl)-2-chloroadenosine (24) and N6-(3-phenylpropyl)adenosine (40) showed nanomolar A3 affinity (Ki 4.5, 6.4 and 7.5 nM, respectively). Among the boron cluster-containing compounds, the highest A3 affinity (Ki 206 nM) was for adenosine derivative 41 modified at C2. In the matched molecular pairs, analogs bearing boron clusters were found to show lower binding affinity for adenosine receptors than the corresponding phenyl analogs. Nevertheless, interestingly, several boron cluster modified adenosine ligands showed significantly higher A3 receptor selectivity than the corresponding phenyl analogs: 7vs. 8, 15vs. 16, 17vs. 18.
Assuntos
Agonistas do Receptor A3 de Adenosina/farmacologia , Adenosina/análogos & derivados , Adenosina/farmacologia , Receptor A3 de Adenosina/metabolismo , Adenosina/metabolismo , Agonistas do Receptor A3 de Adenosina/síntese química , Agonistas do Receptor A3 de Adenosina/metabolismo , Animais , Compostos de Boro/síntese química , Compostos de Boro/metabolismo , Compostos de Boro/farmacologia , Células CHO , Cricetulus , Células HEK293 , Humanos , Ligantes , Estrutura Molecular , Inibidores da Agregação Plaquetária/síntese química , Inibidores da Agregação Plaquetária/metabolismo , Inibidores da Agregação Plaquetária/farmacologia , Relação Estrutura-AtividadeRESUMO
Psoriasis is a chronic and relapsing inflammatory skin disease lacking a cure that affects approximately 2% of the population. Defective keratinocyte proliferation and differentiation, and aberrant immune responses are major factors in its pathogenesis. Available treatments for moderate to severe psoriasis are directed to immune system causing systemic immunosuppression over time, and thus concomitant serious side effects (i.e. infections and cancer) may appear. In recent years, the Gi protein-coupled A3 receptor (A3R) for adenosine has been suggested as a novel and very promising therapeutic target for psoriasis. Accordingly, selective, and high affinity A3R agonists are known to induce robust anti-inflammatory effects in animal models of autoimmune inflammatory diseases. Here, we demonstrated the efficacy of a selective A3R agonist, namely MRS5698, in preventing the psoriatic-like phenotype in the IL-23 mouse model of psoriasis. Subsequently, we photocaged this molecule with a coumarin moiety to yield the first photosensitive A3R agonist, MRS7344, which in photopharmacological experiments prevented the psoriatic-like phenotype in the IL-23 animal model. Thus, we have demonstrated the feasibility of using a non-invasive, site-specific, light-directed approach to psoriasis treatment.
Assuntos
Agonistas do Receptor A3 de Adenosina/farmacologia , Adenosina/análogos & derivados , Fotoquimioterapia , Psoríase/prevenção & controle , Receptor A3 de Adenosina/efeitos dos fármacos , Pele/efeitos dos fármacos , Adenosina/farmacologia , Animais , Modelos Animais de Doenças , Interleucina-23 , Ligantes , Psoríase/imunologia , Psoríase/metabolismo , Psoríase/patologia , Receptor A3 de Adenosina/metabolismo , Transdução de Sinais , Pele/imunologia , Pele/metabolismo , Pele/patologiaRESUMO
Kidney fibrosis is the final outcome of chronic kidney disease (CKD). Adenosine plays a significant role in protection against cellular damage by activating four subtypes of adenosine receptors (ARs), A1AR, A2AAR, A2BAR, and A3AR. A2AAR agonists protect against inflammation, and A3AR antagonists effectively inhibit the formation of fibrosis. Here, we showed for the first time that LJ-4459, a newly synthesized dual-acting ligand that is an A2AAR agonist and an A3AR antagonist, prevents the progression of tubulointerstitial fibrosis. Unilateral ureteral obstruction (UUO) surgery was performed on 6-week-old male C57BL/6 mice. LJ-4459 (1 and 10 mg/kg) was orally administered for 7 days, started at 1 day before UUO surgery. Pretreatment with LJ-4459 improved kidney morphology and prevented the progression of tubular injury as shown by decreases in urinary kidney injury molecular-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) excretion. Obstruction-induced tubulointerstitial fibrosis was attenuated by LJ-4459, as shown by a decrease in fibrotic protein expression in the kidney. LJ-4459 also inhibited inflammation and oxidative stress in the obstructed kidney, with reduced macrophage infiltration, reduced levels of pro-inflammatory cytokines, as well as reduced levels of reactive oxygen species (ROS). These data demonstrate that LJ-4459 has potential as a therapeutic agent against the progression of tubulointerstitial fibrosis.