RESUMO
Non-alcoholic Fatty Liver Disease (NAFLD) is the most common form of liver disease and is associated with metabolic dysregulation. Although G protein-coupled receptor 84 (GPR84) has been associated with inflammation, its role in metabolic regulation remains elusive. The aim of our study was to evaluate the potential of PBI-4547 for the treatment of NAFLD and to validate the role of its main target receptor, GPR84. We report that PBI-4547 is a fatty acid mimetic, acting concomitantly as a GPR84 antagonist and GPR40/GPR120 agonist. In a mouse model of diet-induced obesity, PBI-4547 treatment improved metabolic dysregulation, reduced hepatic steatosis, ballooning and NAFLD score. PBI-4547 stimulated fatty acid oxidation and induced gene expression of mitochondrial uncoupling proteins in the liver. Liver metabolomics revealed that PBI-4547 improved metabolic dysregulation induced by a high-fat diet regimen. In Gpr84-/- mice, PBI-4547 treatment failed to improve various key NAFLD-associated parameters, as was observed in wildtype littermates. Taken together, these results highlight a detrimental role for the GPR84 receptor in the context of meta-inflammation and suggest that GPR84 antagonism via PBI-4547 may reflect a novel treatment approach for NAFLD and its related complications.
Assuntos
Acetatos/farmacologia , Ácidos Graxos/farmacologia , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animais , Ligação Competitiva , Técnicas Biossensoriais , Colesterol/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Descoberta de Drogas , Feminino , Glucose/metabolismo , Teste de Tolerância a Glucose , Células HEK293 , Homeostase , Humanos , Ligantes , Espectroscopia de Ressonância Magnética , Masculino , Metabolômica , Camundongos , Mitocôndrias/metabolismo , Obesidade/metabolismo , Oxigênio/metabolismo , Plasmídeos/metabolismo , Ligação ProteicaRESUMO
Hepatic fibrosis is a major cause of morbidity and mortality for which there is currently no effective therapy. We previously showed that 2-(3-pentylphenyl)acetic acid (PBI-4050) is a dual G protein-coupled receptor GPR40 agonist/GPR84 antagonist that exerts antifibrotic, anti-inflammatory, and antiproliferative action. We evaluated PBI-4050 for the treatment of liver fibrosis in vivo and elucidated its mechanism of action on human hepatic stellate cells (HSCs). The antifibrotic effect of PBI-4050 was evaluated in carbon tetrachloride (CCl4)- and bile duct ligation-induced liver fibrosis rodent models. Treatment with PBI-4050 suppressed CCl4-induced serum aspartate aminotransferase levels, inflammatory marker nitric oxide synthase, epithelial to mesenchymal transition transcription factor Snail, and multiple profibrotic factors. PBI-4050 also decreased GPR84 mRNA expression in CCl4-induced injury, while restoring peroxisome proliferator-activated receptor γ (PPARγ) to the control level. Collagen deposition and α-smooth muscle actin (α-SMA) protein levels were also attenuated by PBI-4050 treatment in the bile duct ligation rat model. Transforming growth factor-ß-activated primary HSCs were used to examine the effect of PBI-4050 and its mechanism of action in vitro. PBI-4050 inhibited HSC proliferation by arresting cells in the G0/G1 cycle phase. Subsequent analysis demonstrated that PBI-4050 signals through a reduction of intracellular ATP levels, activation of liver kinase B1 (LKB1) and AMP-activated protein kinase (AMPK), and blockade of mammalian target of rapamycin (mTOR), resulting in reduced protein and mRNA levels of α-SMA and connective tissue growth factor and restored PPARγ mRNA expression. Our findings suggest that PBI-4050 may exert antifibrotic activity in the liver through a novel mechanism of action involving modulation of intracellular ATP levels and the LKB1/AMPK/mTOR pathway in stellate cells, and PBI-4050 may be a promising agent for treating liver fibrosis.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Trifosfato de Adenosina/metabolismo , Anti-Inflamatórios/farmacologia , Células Estreladas do Fígado/metabolismo , Cirrose Hepática/tratamento farmacológico , Proteínas Serina-Treonina Quinases/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Quinases Proteína-Quinases Ativadas por AMP , Animais , Tetracloreto de Carbono/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Células Estreladas do Fígado/efeitos dos fármacos , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Cirrose Hepática/metabolismo , Cirrose Hepática Experimental/induzido quimicamente , Cirrose Hepática Experimental/tratamento farmacológico , Cirrose Hepática Experimental/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , PPAR gama/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacosRESUMO
Numerous clinical conditions can lead to organ fibrosis and functional failure. There is a great need for therapies that could effectively target pathophysiological pathways involved in fibrosis. GPR40 and GPR84 are G protein-coupled receptors with free fatty acid ligands and are associated with metabolic and inflammatory disorders. Although GPR40 and GPR84 are involved in diverse physiological processes, no evidence has demonstrated the relevance of GPR40 and GPR84 in fibrosis pathways. Using PBI-4050 (3-pentylbenzeneacetic acid sodium salt), a synthetic analog of a medium-chain fatty acid that displays agonist and antagonist ligand affinity toward GPR40 and GPR84, respectively, we uncovered an antifibrotic pathway involving these receptors. In experiments using Gpr40- and Gpr84-knockout mice in models of kidney fibrosis (unilateral ureteral obstruction, long-term post-acute ischemic injury, and adenine-induced chronic kidney disease), we found that GPR40 is protective and GPR84 is deleterious in these diseases. Moreover, through binding to GPR40 and GPR84, PBI-4050 significantly attenuated fibrosis in many injury contexts, as evidenced by the antifibrotic activity observed in kidney, liver, heart, lung, pancreas, and skin fibrosis models. Therefore, GPR40 and GPR84 may represent promising molecular targets in fibrosis pathways. We conclude that PBI-4050 is a first-in-class compound that may be effective for managing inflammatory and fibrosis-related diseases.
Assuntos
Nefropatias/patologia , Receptores Acoplados a Proteínas G/metabolismo , Insuficiência Renal Crônica/patologia , Animais , Fibrose/genética , Fibrose/metabolismo , Fibrose/patologia , Nefropatias/genética , Nefropatias/metabolismo , Camundongos , Camundongos Knockout , Receptores Acoplados a Proteínas G/genética , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/metabolismoRESUMO
Depletion of cholinergic interneurons in the ventral striatum (nucleus accumbens or N.Acc.) in adult rats increases the locomotor activating effects of amphetamine. It also impairs sensorimotor gating processes, an effect reversed by the antipsychotic haloperidol. These behavioral effects are suggestive of pronounced hyper-responsiveness of the mesolimbic dopamine (DA) projection to the N.Acc. However, it is unclear whether local cholinergic depletion results predominantly in exaggerated presynaptic DA release or a postsynaptic upregulation of DAergic function. The purpose of the present study is to test the former possibility by employing in vivo voltammetry to examine changes in the levels of extracellular DA within the N.Acc. in response to either mild tail pinch stress or amphetamine administration. While both cholinergic-lesioned and control rats showed reliable stress-induced increases in extracellular DA on two consecutive test days, those in the lesioned rats were significantly less pronounced. In response to amphetamine, a separate cohort of lesioned rats also exhibited smaller increases in extracellular DA release than controls, despite showing greater locomotor activity. Moreover, the increased behavioral response to amphetamine in lesioned rats coincided temporally with decreasing levels of DA in the N.Acc. The results confirm that cholinergic depletion within the N.Acc. suppresses presynaptic DA release and suggest that lesion-induced behavioral effects are more likely due to postsynaptic DA receptor upregulation. The results are also discussed in the context of schizophrenia, where post mortem studies have revealed a selective loss of cholinergic interneurons within the ventral striatum.