Role of AKT-glycogen synthase kinase axis in monocyte activation in human beings with and without type 2 diabetes

Modeling Foam Cell Formation in A Hydrogel-Based 3D-Intimal Model: A Study of The Role of Multi-Diseases During Early Atherosclerosis

Monocyte recruitment and transmigration are crucial in atherosclerotic plaque development. The multi-disease complexities aggravate the situation and continue to be a constant concern for understanding atherosclerosis plaque development. Herein, a 3D hydrogel-based model that integrates disease-induced microenvironments is sought to be designed, allowing us to explore the early stages of atherosclerosis, specifically examining monocyte fate in multi-disease complexities. As a proof-of-concept study, murine cells are employed to develop the model. The model is constructed with collagen embedded with murine aortic smooth muscle cells and a murine endothelial monolayer lining. The model achieves in vitro disease complexities using external stimuli such as glucose and lipopolysaccharide (LPS). Hyperglycemia exhibits a significant increase in monocyte adhesion but no enhancement in monocyte transmigration and foam cell conversion compared to euglycemia. Chronic infection achieved by LPS stimulation results in a remarkable augment in initial monocyte attachment and a significant increment in monocyte transmigration and foam cells in all concentrations. Moreover, the model exhibits synergistic sensitivity under multi-disease conditions such as hyperglycemia and infection, enhancing initial monocyte attachment, cell transmigration, and foam cell formation. Additionally, western blot data prove the enhanced levels of inflammatory biomarkers, indicating the model's capability to mimic disease-induced complexities during early atherosclerosis progression.

Platelet-Activating Factor Acetylhydrolase Expression in BRCA1 Mutant Ovarian Cancer as a Protective Factor and Potential Negative Regulator of the Wnt Signaling Pathway

Aberrantly activated Wnt/β-catenin signaling pathway, as well as platelet-activating factor (PAF), contribute to cancer progression and metastasis of many cancer entities. Nonetheless, the role of the degradation enzyme named platelet-activating factor acetylhydrolase (PLA2G7/PAF-AH) in ovarian cancer etiology is still unclear. This study investigated the functional impact of platelet-activating factor acetylhydrolase on BRCA1 mutant ovarian cancer biology and its crosstalk with the Wnt signaling pathway. PAF-AH, pGSK3β, and β-catenin expressions were analyzed in 156 ovarian cancer specimens by immunohistochemistry. PAF-AH expression was investigated in ovarian cancer tissue, serum of BRCA1-mutated patients, and in vitro in four ovarian cancer cell lines. Functional assays were performed after PLA2G7 silencing. The association of PAF-AH and β-catenin was examined by immunocytochemistry. In an established ovarian carcinoma collective, we identified PAF-AH as an independent positive prognostic factor for overall survival (median 59.9 vs. 27.4 months; p = 0.016). PAF-AH correlated strongly with the Wnt signaling proteins pGSK3β (Y216; nuclear: cc = 0.494, p < 0.001; cytoplasmic: cc = 0.488, p < 0.001) and β-catenin (nuclear: cc = 0.267, p = 0.001; cytoplasmic: cc = 0.291, p < 0.001). In particular, high levels of PAF-AH were found in tumor tissue and in the serum of BRCA1 mutation carriers. By in vitro expression analysis, a relevant gene and protein expression of PLA2G7/PAF-AH was detected exclusively in the BRCA1-negative ovarian cancer cell line UWB1.289 (p < 0.05). Functional assays showed enhanced viability, proliferation, and motility of UWB1.289 cells when PLA2G7/PAF-AH was downregulated, which underlines its protective character. Interestingly, by siRNA knockdown of PLA2G7/PAF-AH, the immunocytochemistry staining pattern of β-catenin changed from a predominantly membranous expression to a nuclear one, suggesting a negative regulatory role of PAF-AH on the Wnt/β-catenin pathway. Our data provide evidence that PAF-AH is a positive prognostic factor with functional impact, which seems particularly relevant in BRCA1 mutant ovarian cancer. For the first time, we show that its protective character may be mediated by a negative regulation of the Wnt/β-catenin pathway. Further studies need to specify this effect. Potential use of PAF-AH as a biomarker for predicting the disease risk of BRCA1 mutation carriers and for the prognosis of patients with BRCA1-negative ovarian cancer should be explored.

Sinomenine Suppress the Vitamin D3 and High Fat Induced Atherosclerosis in Rats via Suppress of Oxidative Stress and Inflammation

Atherosclerosis (AS) is a cardiovascular disease that arise due to dysfunction of lipid deposition and metabolism. AS is causes the mortality and morbidity worldwide. Sinomenine isolated from the Sinomenium acutum is used extensively against the various cardiac diseases in China. However, the anti-atherosclerosis effect of sinomenine still not explore. In this study, we explore the cardioprotective and anti-atherosclerosis effect of sinomenine against Vitamin D3 and High fat induced atherosclerosis in rats. Sprague Dawley (SD) rats were used in this study. The rats were received the vitamin D (60000) and High fat diet to induce the atherosclerosis and divided into groups and received the oral administration of sinomenine (2.5, 5 and 10 mg/kg) and simvastatin (5 mg/kg). Body weight, organ weight and biochemical parameters were estimated. The mRNA expression of MyD88, TLR4, NF-κB and IκB were estimated. Sinomenine treated rats significantly (p<0.001) suppressed the body weight and modulated the organ weight (hepatic, renal and heart). Sinomenine significantly (p<0.001) decreased the level of triacylglycerols (TG), low density lipoprotein cholesterol (LDL-c), total cholesterol (TC), very low-density lipoprotein cholesterol (VLDL-c) and augmented the level of high-density lipoprotein cholesterol (HDL-c). Sinomenine treatment also reduced the level of atherogenic index (TC/HDL-c and LDL-c/HDL-c). Sinomenine treatment decrease the ratio of HMG CoA/Mevalonate and level of collagen and total protein. Sinomenine significantly (p<0.001) altered the level of heart parameters, antioxidant parameters and inflammatory cytokines. Sinomenine significantly (p<0.001) reduced the expression of MyD88, TLR4, NF-κB and IκB. Taken together, sinomenine exhibited the protective effect against the atherosclerosis via alteration of TLR4/NF-κB signaling pathway.

The Role of Butyrate on Monocyte Migration and Inflammation Response in Patient with Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2DM) is a very serious global problem. In Indonesia, this disease attacks at the most productive age; consequently, it can reduce economic status and life expectancy. The pathogenesis of T2DM is very closely related to inflammation and macrophage accumulation. However, no anti-inflammatory agent has been proven to play a role in the management of T2DM. Butyrate is a short chain fatty acid produced from resistant starch fermentation in the intestinal lumen. It is able to bind to GPR41 and GPR43 receptors on monocytes, so that it can change the pattern of cytokine expression, activation, migration and cell differentiation. Hence, it is interesting to examine the anti-inflammation effect of butyrate and the effect on monocyte migration. A total of 37 subjects were examined in this study. They were divided into two groups, with and without butyrate treatment. We analyzed two pro-inflammatory cytokines (Tumor Necrosis Factor TNF-α and Interleukin IL-6) and one anti-inflammatory cytokine, IL 10. Monocytes were isolated in type 1 collagen gel for migration testing using the µ-slide chemotaxis IBIDI. Image analysis used ImageJ and Chemotaxis tool software. There was a significant difference in the TNFα/IL 10 ratio between healthy groups and T2DM. Butyrate also appears to suppress TNFα cytokine production and increase IL10 production. It also decreases the accumulation distance of monocyte migration in T2DM.

Regulation of platelet-activating factor-induced interleukin-8 expression by protein tyrosine phosphatase 1B

Background

Platelet-activating factor (PAF) is a potent lipid mediator whose involvement in the onset and progression of atherosclerosis is mediated by, among others, the modulation of cytokine expression patterns. The presence of multiple potential protein-tyrosine phosphatase (PTP) 1B substrates in PAF receptor signaling pathways brought us to investigate its involvement in PAF-induced cytokine expression in monocyte-derived dendritic cells (Mo-DCs) and to study the pathways involved in this modulation.

Methods

We used in-vitro-matured human dendritic cells and the HEK-293 cell line in our studies. PTP1B inhibition was though siRNAs and a selective inhibitor. Cytokine expression was studied with RT-PCR, luciferase assays and ELISA. Phosphorylation status of kinases and transcription factors was studied with western blotting.

Results

Here, we report that PTP1B was involved in the modulation of cytokine expression in PAF-stimulated Mo-DCs. A study of the down-regulation of PAF-induced IL-8 expression, by PTP1B, showed modulation of PAF-induced transactivation of the IL-8 promoter which was dependent on the presence of the C/EBPß -binding site. Results also suggested that PTP1B decreased PAF-induced IL-8 production by a glycogen synthase kinase (GSK)-3-dependent pathway via activation of the Src family kinases (SFK). These kinases activated an unidentified pathway at early stimulation times and the PI3K/Akt signaling pathway in a later phase. This change in GSK-3 activity decreased the C/EBPß phosphorylation levels of the threonine 235, a residue whose phosphorylation is known to increase C/EBPß transactivation potential, and consequently modified IL-8 expression.

Conclusion

The negative regulation of GSK-3 activity by PTP1B and the consequent decrease in phosphorylation of the C/EBPß transactivation domain could be an important negative feedback loop by which cells control their cytokine production after PAF stimulation.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0334-6) contains supplementary material, which is available to authorized users.

Vinexin β Ablation Inhibits Atherosclerosis in Apolipoprotein E-Deficient Mice by Inactivating the Akt-Nuclear Factor κB Inflammatory Axis

Background

Vinexin β is a novel adaptor protein that regulates cellular adhesion, cytoskeletal reorganization, signal transduction, and transcription; however, the exact role that vinexin β plays in atherosclerosis remains unknown.

Methods and Results

Immunoblot analysis showed that vinexin β expression is upregulated in the atherosclerotic lesions of both patients with coronary heart disease and hyperlipemic apolipoprotein E–deficient mice and is primarily localized in macrophages indicated by immunofluorescence staining. The high‐fat diet–induced double‐knockout mice exhibited lower aortic plaque burdens than apolipoprotein E^−/− littermates and decreased macrophage content. Vinexin β deficiency improved plaque stability by attenuating lipid accumulation and increasing smooth muscle cell content and collagen. Moreover, the bone marrow transplant experiment demonstrated that vinexin β deficiency exerts atheroprotective effects in hematopoietic cells. Consistent with these changes, the mRNA expression of proinflammatory cytokines were downregulated in vinexin β^−/− apolipoprotein E^−/− mice, whereas the anti‐inflammatory M2 macrophage markers were upregulated. The immunohistochemical staining and in vitro experiments showed that deficiency of vinexin β inhibited the accumulation of monocytes and the migration of macrophages induced by tumor necrosis factor α–stimulated human umbilical vein endothelial cells as well as macrophage proliferation. Finally, the inhibitory effects exerted by vinexin β deficiency on foam cell formation, nuclear factor κB activation, and inflammatory cytokine expression were largely reversed by constitutive Akt activation, whereas the increased expression of the nuclear factor κB subset promoted by adenoviral vinexin β was dramatically suppressed by inhibition of AKT.

Conclusions

Vinexin β deficiency attenuates atherogenesis primarily by suppressing vascular inflammation and inactivating Akt–nuclear factor κB signaling. Our data suggest that vinexin β could be a therapeutic target for the treatment of atherosclerosis.

Human Cytomegalovirus Stimulates the Synthesis of Select Akt-Dependent Antiapoptotic Proteins during Viral Entry To Promote Survival of Infected Monocytes

Primary peripheral blood monocytes are responsible for the hematogenous dissemination of human cytomegalovirus (HCMV) following a primary infection. To facilitate viral spread, we have previously shown HCMV to extend the short 48-h life span of monocytes. Mechanistically, HCMV upregulated two specific cellular antiapoptotic proteins, myeloid leukemia sequence 1 (Mcl-1) and heat shock protein 27 (HSP27), to block the two proteolytic cleavages necessary for the formation of fully active caspase 3 and the subsequent initiation of apoptosis. We now show that HCMV more robustly upregulated Mcl-1 than normal myeloid growth factors and that Mcl-1 was the only myeloid survival factor to rapidly induce HSP27 prior to the 48-h cell fate checkpoint. We determined that HCMV glycoproteins gB and gH signal through the cellular epidermal growth factor receptor (EGFR) and αvβ3 integrin, respectively, during viral entry in order to drive the increase of Mcl-1 and HSP27 in an Akt-dependent manner. Although Akt is known to regulate protein stability and transcription, we found that gB- and gH-initiated signaling preferentially and cooperatively stimulated the synthesis of Mcl-1 and HSP27 through mTOR-mediated translation. Overall, these data suggest that the unique signaling network generated during the viral entry process stimulates the upregulation of select antiapoptotic proteins allowing for the differentiation of short-lived monocytes into long-lived macrophages, a key step in the viral dissemination strategy.

IMPORTANCE

Human cytomegalovirus (HCMV) infection is endemic within the human population. Although primary infection is generally asymptomatic in immunocompetent individuals, HCMV is a significant cause of morbidity and mortality in the immunocompromised. The multiorgan inflammatory diseases associated with symptomatic HCMV infection are a direct consequence of the monocyte-mediated systemic spread of the virus. In order for peripheral blood monocytes to facilitate viral dissemination, HCMV subverts the short 48-h life span of monocytes by inducing the expression of cellular antiapoptotic proteins Mcl-1 and HSP27. Here, we demonstrate that the rapid and simultaneous upregulation of Mcl-1 and HSP27 is a distinctive feature of HCMV-induced monocyte survival. Moreover, we decipher the signaling pathways activated during viral entry needed for the robust synthesis of Mcl-1 and HSP27. Identifying the virus-specific mechanisms used to upregulate select cellular factors required for the survival of HCMV-infected monocytes is important to the development of new classes of anti-HCMV drugs.

ARAP3 functions in hematopoietic stem cells

ARAP3 is a GTPase-activating protein (GAP) that inactivates Arf6 and RhoA small GTPases. ARAP3 deficiency in mice causes a sprouting angiogenic defect resulting in embryonic lethality by E11. Mice with an ARAP3 R302,303A mutation (Arap3^KI/KI) that prevents activation by phosphoinositide-3-kinase (PI3K) have a similar angiogenic phenotype, although some animals survive to adulthood. Here, we report that hematopoietic stem cells (HSCs) from rare adult Arap3^KI/KI bone marrow are compromised in their ability to reconstitute recipient mice and to self-renew. To elucidate the potential cell-autonomous and non-cell-autonomous roles of ARAP3 in hematopoiesis, we conditionally deleted Arap3 in hematopoietic cells and in several cell types within the HSC niche. Excision of Arap3 in hematopoietic cells using Vav1-Cre does not alter the ability of ARAP3-deficient progenitor cells to proliferate and differentiate in vitro or ARAP3-deficient HSCs to provide multi-lineage reconstitution and to undergo self-renewal in vivo. Thus, our data suggest that ARAP3 does not play a cell-autonomous role in HSPCs. Deletion of Arap3 in osteoblasts and mesenchymal stromal cells using Prx1-Cre resulted in no discernable phenotypes in hematopoietic development or HSC homeostasis in adult mice. In contrast, deletion of Arap3 using vascular endothelial cadherin (VEC or Cdh5)-driven Cre resulted in embryonic lethality, however HSCs from surviving adult mice were largely normal. Reverse transplantations into VEC-driven Arap3 conditional knockout mice revealed no discernable difference in HSC frequencies or function in comparison to control mice. Taken together, our investigation suggests that despite a critical role for ARAP3 in embryonic vascular development, its loss in endothelial cells minimally impacts HSCs in adult bone marrow.

Insulin regulates monocyte trans-endothelial migration through surface expression of macrophage-1 antigen

During the pathogenesis of atherosclerosis, adhesion of monocytes to vascular endothelium and subsequent migration across the endothelium has been recognized as a key process in the chronic inflammatory response in atherosclerosis. As type 2 diabetes is closely associated with the pathogenesis of atherosclerosis, we investigated whether monocyte adhesion and migration were affected by insulin. We found that insulin activated Akt and induced subsequent migration in THP-1. However, glucose and insulin-like growth factor-1, which is a growth factor that is structurally similar to insulin, were not effective. Insulin-dependent migration of THP-1 was blocked by inhibition of PI3K or Akt and by silencing of Akt1. Insulin-dependent migration of bone marrow-derived monocytic cells (BDMCs) was attenuated by inhibition of PI3K and Akt. In addition, BDMCs from Akt1(-/-) mice showed defects in insulin-dependent migration. Stimulation of THP-1 with insulin caused adhesion with human vein endothelial cells (HUVECs) that was blocked by silencing of Akt1. However, stimulation of HUVECs did not cause adhesion with THP-1. Moreover, BDMCs from Akt1(-/-) mice showed defects in insulin-dependent adhesion with HUVECs. Insulin induced surface expression of Mac-1, and neutralization of Mac-1 blocked insulin-induced adhesion of THP-1 as well as BDMCs. Surface expression of Mac-1 was blocked in THP-1 with silenced Akt1, and in BDMCs isolated from mice lacking Akt1. Finally, trans-endothelial migration of THP-1 and BDMCs was blocked by Mac-1-neutralizing antibody, in THP-1 with silenced Akt1 and in BDMCs from Akt1(-/-) mice. These results suggest that insulin stimulates monocyte trans-endothelial migration through Akt-dependent surface expression of Mac-1, which may be part of the atherogenesis in type 2 diabetes.

Glycogen synthase kinase 3β inhibition prevents monocyte migration across brain endothelial cells via Rac1-GTPase suppression and down-regulation of active integrin conformation

Glycogen synthase kinase (GSK) 3β has been identified as a regulator of immune responses. We demonstrated previously that GSK3β inhibition in human brain microvascular endothelial cells (BMVECs) reduced monocyte adhesion/migration across BMVEC monolayers. Herein, we tested the idea that GSK3β inhibition in monocytes can diminish their ability to engage the brain endothelium and migrate across the blood-brain barrier. Pretreatment of primary monocytes with GSK3β inhibitors resulted in a decrease in adhesion (60%) and migration (85%), with similar results in U937 monocytic cells. Monocyte-BMVEC interactions resulted in diminished barrier integrity that was reversed by GSK3β suppression in monocytic cells. Because integrins mediate monocyte rolling/adhesion, we detected the active conformational form of very late antigen 4 after stimulation with a peptide mimicking monocyte engagement by vascular cell adhesion molecule-1. Peptide stimulation resulted in a 14- to 20-fold up-regulation of the active form of integrin in monocytes that was suppressed by GSK3β inhibitors (40% to 60%). Because small GTPases, such as Rac1, control leukocyte movement, we measured active Rac1 after monocyte activation with relevant stimuli. Stimulation enhanced the level of active Rac1 that was diminished by GSK3β inhibitors. Monocytes treated with GSK3β inhibitors showed increased levels of inhibitory sites of the actin-binding protein, cofilin, and vasodilator-stimulated phosphoprotein-regulating conformational changes of integrins. These results indicate that GSK3β inhibition in monocytes affects active integrin expression, cytoskeleton rearrangement, and adhesion via suppression of Rac1-diminishing inflammatory leukocyte responses.

Effect of hyperglycemia on human monocyte activation

Our recent study defined the chemokine-induced human monocyte signaling under normoglycemic condition. To explore the hyperglycemia-induced monocyte signaling, we performed adhesion, migration, and transmigration assays on human monocytes obtained from THP-1 cell line in the presence of normal (5 mM) and high (10 and 20 mM) glucose concentrations without chemokines. We observed augmented (P < 0.01) monocyte adhesion to human umbilical vein endothelial cell monolayer at 10 than 5 mM glucose with no further increase at 20-mM glucose concentration (P < 0.07 vs 10 mM; P < 0.01 vs 5 mM). But incremental increases in monocyte migration (P < 0.01), transmigration (P < 0.01), and stress fiber response (P < 0.01) were observed at 10- and 20-mM glucose concentrations in comparison to 5-mM glucose concentrations. We found gradational increase (P < 0.01) in phosphorylation of Akt(S473) and glycogen synthase kinase (GSK3β(S9)) in hyperglycemia (10 and 20 mM) when compared with 5 mM glucose. Furthermore, hyperglycemia (both 10 and 20 mM)-treated monocyte showed up-regulated phosphorylation of p101 and p110γ subunits of PI-3 kinase in comparison to 5 mM glucose. Hyperglycemia-induced monocyte migration was restored to basal levels in the presence of PI-3 kinase inhibitor, LY. These observations imply that modest hyperglycemia per se, as is commonly observed in diabetic individuals, is a potent stimulator of monocyte activity even without chemokines.

Effect of hyperglycemia on human monocyte activation

Our recent study defined the chemokine-induced human monocyte signaling under normoglycemic condition. To explore the hyperglycemia-induced monocyte signaling, we performed adhesion, migration, and transmigration assays on human monocytes obtained from THP-1 cell line in the presence of normal (5 mM) and high (10 and 20 mM) glucose concentrations without chemokines. We observed augmented (P < 0.01) monocyte adhesion to human umbilical vein endothelial cell monolayer at 10 than 5 mM glucose with no further increase at 20-mM glucose concentration (P < 0.07 vs 10 mM; P < 0.01 vs 5 mM). But incremental increases in monocyte migration (P < 0.01), transmigration (P < 0.01), and stress fiber response (P < 0.01) were observed at 10- and 20-mM glucose concentrations in comparison to 5-mM glucose concentrations. We found gradational increase (P < 0.01) in phosphorylation of Akt(S473) and glycogen synthase kinase (GSK3β(S9)) in hyperglycemia (10 and 20 mM) when compared with 5 mM glucose. Furthermore, hyperglycemia (both 10 and 20 mM)-treated monocyte showed up-regulated phosphorylation of p101 and p110γ subunits of PI-3 kinase in comparison to 5 mM glucose. Hyperglycemia-induced monocyte migration was restored to basal levels in the presence of PI-3 kinase inhibitor, LY. These observations imply that modest hyperglycemia per se, as is commonly observed in diabetic individuals, is a potent stimulator of monocyte activity even without chemokines.