Indoleamine 2,3-Dioxygenase 1 (IDO1) Promotes Cardiac Hypertrophy via a PI3K-AKT-mTOR-Dependent Mechanism

Indoleamine 2, 3-dioxygenase Regulates the Differentiation of T Lymphocytes to Promote the Growth of Gastric Cancer Cells through the PI3K/Akt/mTOR Pathway

To investigate the regulatory mechanism of indoleamine 2, 3-dioxygenase (IDO) in T lymphocyte differentiation and its role in promoting the growth of gastric cancer (GC) cells through the PI3K/Akt/mTOR pathway. GC cell lines (MFC and NCI-N87) and PBMC cells were co-cultured and IDO inhibitor 1-methyl-tryptophan (1-MT) was added. The proliferation was detected by CCK-8, the apoptosis was detected by flow cytometry, and the contents of TNF-α, IL-1β, IL-6, IL-8, and INF-γ were detected by ELISA. The expression levels of PI3K, p-PI3K, Akt, p-Akt, mTOR, and p-mTOR were tested using Western blot, and the proportion of CD4+/CD8+, CD4+CD25+Foxp3+Treg cells was detected by flow cytometry. C57BL/6 mice were used to establish the MFC GC mouse model and treated with 1-MT. The changes in body weight and tumor diameter were measured. Ki-67, CD4+, CD8+, and CD25+ expressions were detected by immunohistochemistry. IDO promoted the proliferation of MFC and NCI-N87 cells, inhibited apoptosis, and decreased the levels of TNF-α, IL-1β, IL-6, IL-8, and INF-γ in the supernatant after co-culture with BPMC. The expressions of p-AKT, p-mTOR, and p-PI3K increased after 1-MT treatment. The proportion of CD4+/CD8+ cells was increased and the proportion of Treg cells was decreased in PBMC cells after the addition of 1-MT. Overexpression of IDO suppressed T cells differentiation by inhibiting the PI3K/Akt/mTOR pathway. In vivo, 1-MT treatment reduced the tumor size and weight, increased CD4+ and CD8+ positive area proportion, and decreased Ki-67 and CD25+ positive area proportion. Co-culture of GC cells and immune cells promotes the proliferation of GC cells and inhibits apoptosis, which can be reversed by 1-MT. IDO may suppress the proliferation of T lymphocyte through inhibiting the PI3K/Akt/mTOR signaling pathway. This provides new evidence for the potential of exploiting IDO inhibitors for GC treatment.

IDO-1 inhibition improves outcome after fluid percussion injury in adult male rats

The enzyme indoleamine 2,3 dioxygenase 1 (IDO1) catalyzes the rate-limiting step in the kynurenine pathway (KP) which produces both neuroprotective and neurotoxic metabolites. Neuroinflammatory signals produced as a result of pathological conditions can increase production of IDO1 and boost its enzymatic capacity. IDO1 and the KP have been implicated in behavioral recovery after human traumatic brain injury (TBI), but their roles in experimental models of TBI are for the most part unknown. We hypothesized there is an increase in KP activity in the fluid percussion injury (FPI) model of TBI, and that administration of an IDO1 inhibitor will improve neurological recovery. In this study, adult male Sprague Dawley rats were subjected to FPI or sham injury and received twice-daily oral administration of the IDO1 inhibitor PF-06840003 (100 mg/kg) or vehicle control. FPI resulted in a significant increase in KP activity, as demonstrated by an increased ratio of kynurenine: tryptophan, in the perilesional neocortex and ipsilateral hippocampus 3 days postinjury (DPI), which normalized by 7 DPI. The increase in KP activity was prevented by PF-06840003. IDO1 inhibition also improved memory performance as assessed in the Barnes maze and anxiety behaviors as assessed in open field testing in the first 28 DPI. These results suggest increased KP activity after FPI may mediate neurological dysfunction, and IDO1 inhibition should be further investigated as a potential therapeutic target to improve recovery.

Comparison of moderate-intensity continuous training and high-intensity interval training effects on the Ido1-KYN-Ahr axis in the heart tissue of rats with occlusion of the left anterior descending artery

Myocardial infarction (MI) affects many molecular pathways in heart cells, including the Ido1-KYN-Ahr axis. This pathway has recently been introduced as a valuable therapeutic target in infarction. We examined the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on the axis in the heart tissue of male Wistar rats with occluded left anterior descending (OLAD). Thirty rats (age 10-12 weeks, mean weight 275 ± 25 g) were divided into five groups with 6 animals: Control (Ct) group, MICT group, rats with OLAD as MI group, rats with OLAD treated with MICT (MIMCT group) and rats with OLAD treated with HIIT (MIHIIT group). Rats performed the training protocols for 8 weeks, 5 days a week. HIIT included 7 sets of 4 min running with an intensity of 85-90% VO₂max and 3 min of recovery activation between sets. MICT included continuous running at the same distance as HIIT with an intensity of 50-60% VO₂max for 50 min. The expressions of Ahr, Cyp1a1, and Ido1 were assayed by real-time PCR. Malondialdehyde (MDA) and Kynurenine levels, and AHR, CYP1A1, and IDO1 proteins were detected using ELISA. Data were analyzed using the ANOVA and MANOVA tests. Compared to the CT group, MI caused an increase in all studied factors, but only statistically significant (P < 0.05) for MDA and IDO1. With a greater effect of HIIT, both protocols significantly lowered the proteins expressions in the MIHIIT and MIMCT groups, compared with the MI group (P < 0.001). In healthy rats, only AHR protein significantly decreased in the MICT group compared to the Ct group (P < 0.05). HIIT and MICT protocols significantly reduced the gene and protein expression of Cyp1a1 (P < 0.05) and Ido1 (P < 0.01), and HIIT had a greater effect. In conclusion, both protocols were effective at reducing the levels of Ido1-Kyn-Ahr axis components and oxidative stress in the infarcted heart tissue and HIIT had a higher significant effect.

The protective effect of Apelin-13 against cardiac hypertrophy through activating the PI3K-AKT-mTOR signaling pathway

Objectives

To determine the protective effect of Apelin-13 on cardiac hypertrophy through activating the PI3K-AKT-mTOR signaling pathway.

Materials and Methods

The phenylephrine-induced cardiomyocyte hypertrophy model was established in H9C2 cells in vitro. Electroporation transfection technology was utilized to prepare and screen the H9C2 cells inducing low expression of the angiotensin type one receptor-related protein (Si-APJ). H9C2 and Si-APJ cells were divided independently into five groups: the control group, the PE group, the PE+Apelin group, the PE+Rapa group, and the PE+Apelin+Rapa group. RT-PCR was performed to analyze the mRNA expression levels of myosin heavy chain 7 (MYH7). Expression of the PI3K/AKT/mTOR pathway proteins and MYH7 was investigated by western blot.

Results

The expression of PI3K/AKT/mTOR phosphorylated proteins was significantly higher in the PE group compared with the PE+Apelin group in H9C2 cells (P<0.05). Conversely, in Si-APJ H9C2 cells, the expression of PI3K/AKT/mTOR phosphorylated proteins was decreased (P<0.05). In H9C2 cells, the expression of MYH7 protein was increased in the PE group compared with the control group (P<0.05). In the same cell line, the expression of MYH7 in the PE+Apelin group was decreased significantly compared with the PE group (P<0.05). In Si-APJ H9C2 cells, compared with the control group, the expression of MYH7 in the PE group still increased significantly (P<0.05). In contrast, in the same cell line, there was no statistically significant difference in MYH7 expression between the PE+Apelin, PE+Rapa, and PE+Apelin+Rapa groups compared to the PE group (P>0.05).

Conclusion

Apelin-13 reduces PE-induced cardiac hypertrophy by activating the PI3K/AKT/mTOR signaling pathway.

Identification of biomarkers, pathways, and potential therapeutic targets for heart failure using next-generation sequencing data and bioinformatics analysis

BACKGROUND

Heart failure (HF) is the most common cardiovascular diseases and the leading cause of cardiovascular diseases related deaths. Increasing molecular targets have been discovered for HF prognosis and therapy. However, there is still an urgent need to identify novel biomarkers. Therefore, we evaluated biomarkers that might aid the diagnosis and treatment of HF.

METHODS

We searched next-generation sequencing (NGS) dataset (GSE161472) and identified differentially expressed genes (DEGs) by comparing 47 HF samples and 37 normal control samples using limma in R package. Gene ontology (GO) and pathway enrichment analyses of the DEGs were performed using the g: Profiler database. The protein-protein interaction (PPI) network was plotted with Human Integrated Protein-Protein Interaction rEference (HiPPIE) and visualized using Cytoscape. Module analysis of the PPI network was done using PEWCC1. Then, miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed by Cytoscape software. Finally, we performed receiver operating characteristic (ROC) curve analysis to predict the diagnostic effectiveness of the hub genes.

RESULTS

A total of 930 DEGs, 464 upregulated genes and 466 downregulated genes, were identified in HF. GO and REACTOME pathway enrichment results showed that DEGs mainly enriched in localization, small molecule metabolic process, SARS-CoV infections, and the citric acid tricarboxylic acid (TCA) cycle and respiratory electron transport. After combining the results of the PPI network miRNA-hub gene regulatory network and TF-hub gene regulatory network, 10 hub genes were selected, including heat shock protein 90 alpha family class A member 1 (HSP90AA1), arrestin beta 2 (ARRB2), myosin heavy chain 9 (MYH9), heat shock protein 90 alpha family class B member 1 (HSP90AB1), filamin A (FLNA), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), cullin 4A (CUL4A), YEATS domain containing 4 (YEATS4), and lysine acetyltransferase 2B (KAT2B).

CONCLUSIONS

This discovery-driven study might be useful to provide a novel insight into the diagnosis and treatment of HF. However, more experiments are needed in the future to investigate the functional roles of these genes in HF.

A fungicide, fenhexamid, is involved in the migration and angiogenesis in breast cancer cells expressing estrogen receptors

Fenhexamid (Fen) is used to eradicate gray mold of fruits and vegetables leading to greater detection of its residual concentration in wine than other fungicides. Here, we further investigated the malign influence of Fen on the migration and angiogenesis via regulation of the estrogen receptor (ER) and phosphoinositide 3-kinase (PI3K) pathways in breast cancer models. ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cells were exposed to 17β-estradiol (E2, 10^-9 M), Fen (10^-5 M and 10^-7 M), ICI 182,780 (ICI; an ER antagonist, 10^-8 M) or/and Pictilisib (Pic; a PI3K inhibitor, 10^-7 M), and subsequently subjected to migration assay, live cell motility monitoring, trans-chamber assay, immunofluorescence, angiogenesis assay, tumor spheroid formation, and Western blot analysis. In MCF-7 cells, E2 and Fen induced cell migration by regulating the cell migration-related proteins. Although expressions of N-cadherin and Vimentin remained unchanged E2 and Fen induced the decrease of E-cadherin and Occludin in the immunofluorescence assay and Western blot analysis. In addition, Fen increased vessel formation in HUVEC cells. Furthermore, Fen treatment induced the formation of larger and denser tumor spheroids in MCF-7 cells. Western blot further confirmed the increased expressions of vascular endothelial growth factor (VEGF) and sex-determining region Y-box 2 (SOX2) after exposure to Fen. We conclude that Fen plays an important role as an endocrine-disrupting chemical in breast cancer migration and metastasis through the regulation of ER and PI3K signaling pathways.

The Footprint of Kynurenine Pathway in Cardiovascular Diseases

Kynurenine pathway is the main route of tryptophan metabolism and produces several metabolites with various biologic properties. It has been uncovered that several cardiovascular diseases are associated with the overactivation of kynurenine pathway and kynurenine and its metabolites have diagnostic and prognostic value in cardiovascular diseases. Furthermore, it was found that several kynurenine metabolites can differently affect cardiovascular health. For instance, preclinical studies have shown that kynurenine, xanthurenic acid and cis-WOOH decrease blood pressure; kynurenine and 3-hydroxyanthranilic acid prevent atherosclerosis; kynurenic acid supplementation and kynurenine 3-monooxygenase (KMO) inhibition improve the outcome of stroke. Indoleamine 2,3-dioxygenase (IDO) overactivity and increased kynurenine levels improve cardiac and vascular transplantation outcomes, whereas exacerbating the outcome of myocardial ischemia, post-ischemic myocardial remodeling, and abdominal aorta aneurysm. IDO inhibition and KMO inhibition are also protective against viral myocarditis. In addition, dysregulation of kynurenine pathway is observed in several conditions such as senescence, depression, diabetes, chronic kidney disease (CKD), cirrhosis, and cancer closely connected to cardiovascular dysfunction. It is worth defining the exact effect of each metabolite of kynurenine pathway on cardiovascular health. This narrative review is the first review that separately discusses the involvement of kynurenine pathway in different cardiovascular diseases and dissects the underlying molecular mechanisms.

Kynurenine Pathway Metabolites as Potential Clinical Biomarkers in Coronary Artery Disease

Coronary artery disease (CAD) is one of the leading cause of mortality worldwide. Several risk factors including unhealthy lifestyle, genetic background, obesity, diabetes, hypercholesterolemia, hypertension, smoking, age, etc. contribute to the development of coronary atherosclerosis and subsequent coronary artery disease. Inflammation plays an important role in coronary artery disease development and progression. Pro-inflammatory signals promote the degradation of tryptophan via the kynurenine pathway resulting in the formation of several immunomodulatory metabolites. An unbalanced kynurenic pathway has been implicated in the pathomechanisms of various diseases including CAD. Significant improvements in detection methods in the last decades may allow simultaneous measurement of multiple metabolites of the kynurenine pathway and such a thorough analysis of the kynurenine pathway may be a valuable tool for risk stratification and determination of CAD prognosis. Nevertheless, imbalance in the activities of different branches of the kynurenine pathway may require careful interpretation. In this review, we aim to summarize clinical evidence supporting a possible use of kynurenine pathway metabolites as clinical biomarkers in various manifestations of CAD.

mTOR inhibitor improves testosterone-induced myocardial hypertrophy in hypertensive rats

Compelling evidence has described that the incidence of hypertension and left ventricular hypertrophy (LVH) in postmenopausal women is significantly increased worldwide. Our team's previous research identified that androgen was an underlying factor contributing to increased blood pressure and LVH in postmenopausal women. However, little is known about how androgens affect LVH in postmenopausal hypertensive women. The purpose of this study was to evaluate the role of mammalian rapamycin receptor (mTOR) signaling pathway in myocardial hypertrophy in androgen-induced postmenopausal hypertension and whether mTOR inhibitors can protect the myocardium from androgen-induced interference to prevent and treat cardiac hypertrophy. For that, ovariectomized (OVX) spontaneously hypertensive rats (SHR) aged 12 weeks were used to study the effects of testosterone (T 2.85 mg/kg/weekly i.m.) on blood pressure and myocardial tissue. On the basis of antihypertensive therapy (chlorthalidone 8 mg/kg/day ig), the improvement of blood pressure and myocardial hypertrophy in rats treated with different dose gradients of rapamycin (0.8 mg/kg/day vs 1.5 mg/kg/day vs 2 mg/kg/day i.p.) in OVX + estrogen (E 9.6 mg/kg/day, ig) + testosterone group was further evaluated. After testosterone intervention, the OVX female rats exhibited significant increments in the heart weight/tibial length (TL), area of cardiomyocytes and the mRNA expressions of ANP, β-myosin heavy chain and matrix metalloproteinase 9 accompanied by a significant reduction in the uterine weight/TL and tissue inhibitor of metalloproteinase 1. mTOR, ribosomal protein S6 kinase (S6K1), 4E-binding protein 1 (4EBP1) and eukaryotic translation initiation factor 4E in myocardial tissue of OVX + estrogen + testosterone group were expressed at higher levels than those of the other four groups. On the other hand, rapamycin abolished the effects of testosterone-induced cardiac hypertrophy, decreased the systolic and diastolic blood pressure of SHR, and inhibited the activation of mTOR/S6K1/4EBP1 signaling pathway in a concentration-dependent manner. Collectively, these data suggest that the mTOR/S6K1/4EBP1 pathway is an important therapeutic target for the prevention of LVH in postmenopausal hypertensive female rats with high testosterone levels. Our findings also support the standpoint that the mTOR inhibitor, rapamycin, can eliminate testosterone-induced cardiomyocyte hypertrophy.

Biomarkers of inflammation and left ventricular remodelling in psoriasis patients treated with infliximab

Objective: Psoriasis is an immune mediated disorder associated with T cell activation and cardiovascular disease (CVD). We explored the association of inflammation with left ventricular (LV) remodelling in psoriasis patients receiving treatment with the tumour necrosis factor-α (TNF-α) blocker infliximab. Methods: Psoriasis patients (n = 47, age 47 ± 14 years, 66% men) and 99 control subjects without psoriasis (age 47 ± 11 years, 72% men) were examined by echocardiography in a cross-sectional study. LV remodelling was assessed by LV mass index for height in the allometric power of 2.7. Serum concentrations of C-reactive protein (CRP), serum amyloid A (SAA), neopterin, kynurenine:tryptophan ratio (KTR) and the pyridoxic acid ratio (PAr) index were measured. Results: Serum concentration of neopterin (p = .007) was higher in psoriasis patients, while the other inflammatory biomarkers had similar levels. LV mass index was lower in patients than controls (35.6 ± 9.6 g/m^2.7 vs. 40.3 ± 9.8 g/m^2.7, p = .008). In the total study population, serum SAA (β = 0.18, p = .02), KTR (β = 0.20, p = .02) and the PAr index (β = 0.26, p = .002) were all associated with higher LV mass index independent of age, sex, body mass index, hypertension, smoking, renal function and psoriasis. Also in psoriasis patients, higher SAA level (β = 0.34, p = .02), KTR (β = 0.32, p = .02) and the PAr index (β = 0.29, p = .05) were associated with higher LV mass index independent of body mass index, hypertension and diabetes. Conclusion: Higher levels of the inflammatory biomarkers SAA, KTR and the PAr index were associated with greater LV mass index in psoriasis patients, indicating a role of chronic inflammation in LV remodelling evident even during treatment with TNF-α blockers.

Target Sestrin2 to Rescue the Damaged Organ: Mechanistic Insight into Its Function

Sestrin2 is a stress-inducible metabolic regulator and a conserved antioxidant protein which has been implicated in the pathogenesis of several diseases. Sestrin2 can protect against atherosclerosis, heart failure, hypertension, myocardial infarction, stroke, spinal cord injury neurodegeneration, nonalcoholic fatty liver disease (NAFLD), liver fibrosis, acute kidney injury (AKI), chronic kidney disease (CKD), and pulmonary inflammation. Oxidative stress and cellular damage signals can alter the expression of Sestrin2 to compensate for organ damage. Different stress signals such as those mediated by P53, Nrf2/ARE, HIF-1α, NF-κB, JNK/c-Jun, and TGF-β/Smad signaling pathways can induce Sestrin2 expression. Subsequently, Sestrin2 activates Nrf2 and AMPK. Furthermore, Sestrin2 is a major negative regulator of mTORC1. Sestrin2 indirectly regulates the expression of several genes and reprograms intracellular signaling pathways to attenuate oxidative stress and modulate a large number of cellular events such as protein synthesis, cell energy homeostasis, mitochondrial biogenesis, autophagy, mitophagy, endoplasmic reticulum (ER) stress, apoptosis, fibrogenesis, and lipogenesis. Sestrin2 vigorously enhances M2 macrophage polarization, attenuates inflammation, and prevents cell death. These alterations in molecular and cellular levels improve the clinical presentation of several diseases. This review will shed light on the beneficial effects of Sestrin2 on several diseases with an emphasis on underlying pathophysiological effects.