Development of a novel formulation method to prepare liposomal Epacadostat.

BACKGROUND: One of the important metabolic pathways in cancer progression is tryptophan catabolism by the indoleamin-2,3-dioxygenase (IDO) enzyme, which suppresses the immune system and induces tolerance. Inhibition of IDO1 is an important therapeutic goal for immunotherapy in many cancers such as metastatic melanoma. Epacadostat (EPA) is a very strong inhibitor of IDO1, and its clinical studies are being performed in a higher clinical phase than other inhibitors. In this study, we have developed a new liposomal EPA formulation to reduce the dose, side effects, and treatment costs. METHODS: Liposomes containing EPA were formulated using a novel remote loading method. Their morphology, particle size, surface charge, total phospholipid content, and drug loading were evaluated. Validation method studies to assay of EPA were carried out according to ICHQ2B guidelines. For in-vivo study, B16F10 melanoma bearing C57BL/6 mice were treated with the free or liposomal forms of EPA, and then monitored for tumor size and survival rate. RESULTS: A validated method for EPA determination in liposomal form using UV-visible spectrophotometry was developed which was a precise, accurate and robust method. The particle size, zeta potential, and encapsulation efficacy of liposomes was 128.1 ± 1.1 nm, -16.5 ± 1 mV, and 64.9 ± 3.5, respectively. The half maximal inhibitory concentration (IC50) of liposomal EPA was 64 ng/ml that was lower than free EPA (128 ng/ml). In-vivo results also showed that tumor growth was slower in mice receiving liposomal EPA than in the group receiving free EPA. CONCLUSION: A new method was developed to load EPA into liposomes. Moreover, the use of the nanoliposomal EPA showed more efficacy than EPA in inhibiting the tumor growth in melanoma model. Therefore, it might be used in further clinical studies as a good candidate for immunotherapy alone or in combination with other treatments.

Indoleamine 2,3-dioxygenase 1 in coronary atherosclerotic plaque enhances tissue factor expression in activated macrophages.

BACKGROUND: Recent clinical studies have found that changes in the kynurenine (Kyn) pathway of tryptophan (Trp) metabolism are associated with cardiovascular events. However, the roles of the Kyn pathway on vascular wall thrombogenicity remain unknown. Indoleamine 2,3-dioxygenase 1 (IDO1) is a rate-limiting enzyme of the Kyn pathway. OBJECTIVE: The present study aimed to localize IDO1 in human coronary atherosclerotic plaques from patients with angina pectoris and define its role in plaque thrombogenicity. METHODS: Immunohistochemical methods were applied to localize IDO1 in coronary atherosclerotic plaques from patients with stable (SAP) and unstable (UAP) angina pectoris. The role of IDO1 in tissue factor (TF) expression was investigated in THP-1 macrophages activated by interferon (IFN)γ and tissue necrosis factor (TNF)α. RESULTS: We localized IDO1 mainly in CD68-positive macrophages within atherosclerotic plaques, and in close association with TF. Areas that were immunopositive for IDO1, TF, and CD3-positive T lymphocytes were significantly larger in plaques from patients with UAP than SAP. Macrophages activated by IFNγ and TNFα upregulated IDO1 expression, increased the Kyn/Trp ratio and enhanced TF expression and activity, but not TF pathway inhibitor expression. The IDO1 inhibitor epacadostat significantly reduced the Kyn/Trp ratio, TF expression and activity, as well as NF-κB (p65) binding activity in activated macrophages. Inhibition of the aryl hydrocarbon receptor that binds to Kyn, also reduced Kyn-induced TF expression in activated macrophages. CONCLUSION: Indoleamine 2,3-dioxygenase 1 expressed in coronary atherosclerotic plaques might contribute to thrombus formation through TF upregulation in activated macrophages.

Relationship between activation of IL-1β,IL-6 and downstream IDO activation with rat depression behaviors / 重庆医学

Objective To investigate the relationship between the rat depression behaviors induced by chronically unpredicted stress (CUS) with interleukin-1β (IL-1β),interleukin-6 (IL-6) protein expression and indole-2,3-dioxygenase (IDO) mRNA and protein expression.Methods Thirty male Sprague Dawley (SD)rats were divided into the control group (CG) and model group (MG).The solitary raise combined with CUS 28 d continued stimulus was used to establish the rat depression model.The open field test (OFT) and the force swimming test (FST) were used to evaluate the rat depression behaviors;qRT-PCR was used to determine the mRNA expression of IDO in hippocampus and cortex;Western blot was used to determine the protein expressions of IL-1β,IL-6 and IDO in hippocampus and cortex.Results Compared with the CG group,the OFT score in the rats of the MG group was significantly decreased(P＜0.01),the immobility time in FST was significantly extended (P＜0.00),the expression of IDO mRNA in hippocampus and cortex was significantly increased (P＜0.01) and the protein expression of IL-1β,IL-6 and IDO in hippocampus and cortex was significantly increased (P＜0.05).Conclusion The rat depression behaviors induced by CUS may be associated with the increase of intracerebral inflammatory cytokine expression and inducing IDO over-expression.