MEK1/2 inhibitors induce interleukin-5 expression in mouse macrophages and lymphocytes

MEK1/2 inhibitor inhibits neointima formation by activating miR-126-3p/ C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) axis

Endothelial dysfunction is an initial and essential step in vascular-remodeling diseases, including atherosclerosis and neointima formation. During vascular remodeling, activated endothelial cells can release pro-inflammatory factors that promote phenotypic switching of vascular smooth muscle cells (VSMCs) to the proliferative phenotype. We previously reported that MEK1/2 inhibitor, U0126, has a protective effect on the development of atherosclerosis and vascular calcification. However, the effect of MEK1/2 inhibitors on neointimal formation and the underlying mechanism is not fully understood. We determined that MEK1/2 inhibitor reduced carotid artery ligation-induced neointimal formation, while increased collagen and elastin levels and vascular integrality. Mechanistically, MEK1/2 inhibitor or ERK1/2 siRNA increased miR-126-3p level in endothelial cells, thereby inhibiting expression of regular of G-protein signaling 16 (RGS16), a miR-126-3p target gene, to activate the C-X-C motif chemokine ligand 12 (CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) signaling pathway. Accordingly, miR-126-3p was also increased by U0126 in serum and carotid artery. RGS16 was inhibited while CXCR4 and CXCL12 was increased by U0126 in neointimal areas, especially in the endothelium. Moreover, similar results were observed in atherosclerotic plaques of high-fat diet-fed apolipoprotein E deficiency (apoE^−/−) mice. In addition, vascular cell adhesion molecule 1 (VCAM-1), another miR-126-3p target gene, was reduced by U0126 in the neointimal areas, resulting reduced monocytes/macrophages accumulation. Taken together, our results indicate that MEK1/2 inhibitor can reduce neointima formation by activating endothelial miR-126-3p production to facilitate endothelium repair while reduce monocyte adhesion/infiltration.

ERK1/2 inhibition reduces vascular calcification by activating miR-126-3p-DKK1/LRP6 pathway

Rationale: Vascular microcalcification increases the risk of rupture of vulnerable atherosclerotic lesions. Inhibition of ERK1/2 reduces atherosclerosis in animal models while its role in vascular calcification and the underlying mechanisms remains incompletely understood.

Methods: Levels of activated ERK1/2, DKK1, LRP6 and BMP2 in human calcific aortic valves were determined. ApoE deficient mice received ERK1/2 inhibitor (U0126) treatment, followed by determination of atherosclerosis, calcification and miR-126-3p production. C57BL/6J mice were used to determine the effect of U0126 on Vitamin D₃ (VD₃)-induced medial arterial calcification. HUVECs, HAECs and HASMCs were used to determine the effects of ERK1/2 inhibitor or siRNA on SMC calcification and the involved mechanisms.

Results: We observed the calcification in human aortic valves was positively correlated to ERK1/2 activity. At cellular and animal levels, U0126 reduced intimal calcification in atherosclerotic lesions of high-fat diet-fed apoE deficient mice, medial arterial calcification in VD₃-treated C57BL/6J mice, and calcification in cultured SMCs and arterial rings. The reduction of calcification was attributed to ERK1/2 inhibition-reduced expression of ALP, BMP2 and RUNX2 by activating DKK1 and LRP6 expression, and consequently inactivating both canonical and non-canonical Wnt signaling pathways in SMCs. Furthermore, we determined ERK1/2 inhibition activated miR-126-3p production by facilitating its maturation through activation of AMPKα-mediated p53 phosphorylation, and the activated miR-126-3p from ECs and SMCs played a key role in anti-vascular calcification actions of ERK1/2 inhibition.

Conclusions: Our study demonstrates that activation of miR-126-3p production in ECs/SMCs and interactions between ECs and SMCs play an important role in reduction of vascular calcification by ERK1/2 inhibition.

Multi-omics analysis revealed crucial genes and pathways associated with black carp antiviral innate immunity

Multi-omics strategy contributes as an indispensable and efficient approach for the investigation of the innate immunity in vertebrates. To explore the crucial genes and pathways involved in the antiviral innate immunity of black carp (Mylopharyngodon piceus), the comparative phosphoproteomics and transcriptomics of Mylopharyngodon piceus kidney (MPK) cells with/without GCRV infection were performed in this manuscript. In phosphoproteomics analysis, 2637 phosphosites corresponding to 1532 proteins were identified and quantified, in which 1372 proteins were identified as differentially expressed proteins (DEPs) with 683 upregulated and 689 downregulated in GCRV infected cells. Functional annotation, enrichment analysis and pathway analysis highlighted that a large number of DEPs were enriched in immune related pathways including TLR pathway and NLR pathway. In transcriptomics analysis, a total of 2936 genes were identified as differentially expressed genes (DEGs), in which 2290 and 646 genes were upregulated and downregulated respectively after GCRV infection. As expected, pathway analysis based on DEGs also showed that a large proportion of DEGs were enriched in immune related pathways including TLR and RLR pathway. A combined list of DEPs and DEGs that enriched in above pathways were imported in Cytoscape for network analysis, reconstruction and visualization. The integrative study suggested that several significant DEPs and DEGs, such as MAP3K7 (TAK1), JUN, MAP2K2, CASP8, IL8 and IRF7 might be functionally crucial in host antiviral innate immunity. Thus, this study contributes as an indispensable reference map for the further investigation of the innate immune system of black carp.

MEK1/2 Inhibition in Murine Heart and Aorta After Oral Administration of Refametinib Supplemented Drinking Water

Upregulation of the RAS-RAF-MEK-ERK-MAPK pathway is involved in the development of several human tumors, aortic aneurysms, atherosclerosis, and cardiomyopathy. Refametinib, a highly selective MEK-inhibitor, has already shown antineoplastic activity in phase II trials. Furthermore, it showed potency to attenuate aortic root growth in murine models. Current formulations of this drug however necessitate oral gavage as a delivery method for long-term studies, which is labor-intensive and induces stress and occasional injury, potentially confounding results. Therefore, we developed a novel oral administration method for refametinib. A 2-hydroxypropyl-beta-cyclodextrin (HPBCD) based drinking water preparation of refametinib was formulated, for which a selective, analytical UHPLC-UV method was developed to assess the in-use stability. Next, 16 week old male wild-type C57Bl/6J mice received either a daily dose of 50 or 75 mg/kg/day refametinib or were given regular drinking water during 7 days. In both dosage groups the refametinib plasma levels were measured (n = 10 or 7, respectively). Furthermore, pERK/total ERK protein levels were calculated in the myocardial and aortic tissue of mice receiving a daily dose of 50 mg/kg/day refametinib and untreated mice (n = 4/group). After 7 days no significant degradation of refametinib was observed when dissolved in drinking water provided that drinking bottles were protected from UV/visible light. Furthermore, a dose-dependent increase in refametinib plasma levels was found whereby active plasma levels (> 1.2 µg/mL) were obtained even in the lowest dose-group of 50 mg/kg/day. A significant reduction of pERK/total ERK protein levels compared to untreated mice was observed in aortic and myocardial tissue of mice receiving a daily dose of 50 mg/kg/day refametinib. Importantly, a relatively high mortality rate was noted in the highest dose group (n = 5). This approach provides a valid alternative oral administration method for refametinib with a reduced risk of complications due to animal manipulation and without loss of functionality, which can be implemented in future research regarding the malignant upregulation of the RAS-RAF-MEK-ERK-MAPK pathway. However, care must be taken not to exceed the toxic dose.

Combination of MEK1/2 inhibitor and LXR ligand synergistically inhibit atherosclerosis in LDLR deficient mice

Combined LXR ligand (T0901317) and MEK1/2 inhibitor (U0126) not only reduces atherosclerosis in apoE deficient mice, but also blocks LXR ligand-induced fatty liver and hypertriglyceridemia. However, the atheroprotective function of combined T0901317 and U0126 should be further investigated in LDLR deficient (LDLR^-/-) mice since deficiency of LDLR not apoE can occur to humans with a high frequency. Herein, we validated the effectiveness of this combinational therapy on the development of atherosclerosis in LDLR^-/- mice to demonstrate its potential application in clinic. We found although T0901317 or U0126 alone reduced atherosclerotic plaques in en face and aortic root areas in HFD-fed LDLR^-/- mice, their combination inhibited lesions in a synergistic manner. Combined U0126 and T0901317 had no effect on serum total cholesterol levels. T0901317 deceased HDL-cholesterol levels, which was restored by combined U0126. Meanwhile, U0126 alleviated T0901317-induced triglyceride accumulation, the major adverse effect of T0901317 which limits its clinical utility. Mechanistically, U0126 reduced fatty acid de novo synthesis by inhibiting hepatic fatty acid synthase (FASN) expression, thereby correcting T0901317-induced triglyceride overproduction. In conclusion, our study demonstrates that combination of MEK1/2 inhibitor and LXR ligand can synergistically reduce atherosclerosis in LDLR deficient mice without lipogenic side effects.

IL-5 overexpression attenuates aortic dissection by reducing inflammation and smooth muscle cell apoptosis

BACKGROUND

As an inflammation-related cytokine, interleukin (IL)-5 has been reported to be involved in the development of cardiovascular diseases, such as chronic heart failure and atherosclerosis. However, the role of IL-5 in acute aortic dissection (AAD) has barely been explored.

METHODS

Aortic tissue samples from normal donors and patients with AAD were collected, and the expression and localization of IL-5 in aortic tissue were analyzed. In addition, a mouse AAD model was established by administering angiotensin II (Ang II) to β-aminopropionitrile (BAPN)-treated mice. Morphological examinations and histopathologic analyses were performed to evaluate the effects of IL-5 overexpression on the occurrence of AAD.

RESULTS

IL-5 expression was significantly decreased in aorta samples from AAD patients compared to those from donors, and macrophages were the main source of IL-5. In addition, IL-5 expression was decreased in plasma and aortic tissue samples from AAD mice. IL-5 overexpression markedly attenuated the occurrence of AAD in mice and produced corresponding decreases in the inflammatory response and cell apoptosis. In cocultures of macrophages and smooth muscle cells (SMCs), IL-5 overexpression in the macrophages significantly reduced Ang II-induced SMC apoptosis.

CONCLUSION

IL-5 overexpression suppresses the development of AAD by reducing inflammation and SMC apoptosis. These results suggest that IL-5 is a potential therapeutic target in AAD.

Interleukin-5 levels are decreased in the plasma of coronary artery disease patients and inhibit Th1 and Th17 differentiation in vitro

INTRODUCTION AND OBJECTIVES

Interleukin (IL)-5 is an anti-inflammatory cytokine that has been demonstrated to be involved in cardiovascular diseases, including aortic aneurysm and heart failure. This study aimed to investigate the involvement of IL-5 in coronary artery disease (CAD) and the possible mechanisms.

METHODS

We analyzed IL-5 expression in human coronary artery specimens collected from CAD patients and deceased donors. Plasma IL-5, IL-17, and interferon-γ levels in CAD patients were detected using ELISA kits, with samples from chest pain patients (non-CAD) as controls. Mouse CD4⁺T helper (Th) cells were separated, and the effect of IL-5 on Th1, regulatory T cell and Th17 differentiation and mRNA levels of their characteristic cytokines were detected using flow cytometry and reverse transcription-quantitative polymerase chain reaction, respectively.

RESULTS

IL-5 was significantly decreased in the coronary plaque of CAD patients compared with the deceased donors group, and IL-5 was mainly derived from macrophages in the coronary artery plaque. Compared with the non-CAD group, plasma IL-5 levels in the CAD groups were significantly lower, and the sequence from high to low was stable angina pectoris, unstable angina pectoris, and acute myocardial infarction. Binary linear regression analysis showed that IL-5 was independently correlated with the occurrence of CAD. Recombinant mouse IL-5 treatment decreased Th1 and Th17 levels and mRNA expression of their characteristic cytokines in oxidized low-density lipoprotein-treated CD4⁺Th cells.

CONCLUSION

IL-5 levels were decreased in CAD patients and inhibited oxidized low-density lipoprotein Th1 and Th17 differentiation in vitro.

MEK2 Negatively Regulates Lipopolysaccharide-Mediated IL-1β Production through HIF-1α Expression

LPS-activated macrophages require metabolic reprogramming and glucose uptake mediated by hypoxia-inducible factor (HIF)-1 α and glucose transporter 1 (Glut1) expression for proinflammatory cytokine production, especially IL-1β. This process is tightly regulated through activation of MAPK kinases, including the MEK/ERK pathway as well as several transcription factors including HIF-1α. Although MAPK kinase (MEK) 2 deficiency had no significant effect on NO, TNF-α, or IL-12 production in response to LPS challenge, MEK2-deficient murine bone marrow-derived macrophages (BMDMs) exhibited lower IL-10 production. Importantly, MEK2-deficient BMDMs exhibited a preserved ERK1/2 phosphorylation, higher HIF-1α and Glut1 levels, and substantially increased IL-1β as well as IL-6 production in response to LPS stimulation. Knockdown of HIF-1α expression via short interference RNA decreased the level of HIF-1α expression in MEK2-deficient BMDMs and decreased IL-1β production in response to LPS treatment. Furthermore, we performed gain of function experiments by overexpressing MEK2 protein in RAW264.7 cells. LPS stimulation of MEK2 overexpressed in RAW264.7 cells led to a marked decreased IL-1β production. Finally, we investigated the role of Mek1 and Mek2 double and triple mutation on ERK phosphorylation, HIF-1α expression, and IL-1β production. We found that MEK2 is the major kinase, which inversely proportionally regulates HIF-1α and IL-1β expression independent of ERK activation. Our findings demonstrate a novel regulatory function for MEK2 in response to TLR4 activation in IL-1β production through modulating HIF-1α expression.

MEK1/2 Inhibition Promotes Macrophage Reparative Properties

Macrophages have important functional roles in regulating the timely promotion and resolution of inflammation. Although many of the intracellular signaling pathways involved in the proinflammatory responses of macrophages are well characterized, the components that regulate macrophage reparative properties are less well understood. We identified the MEK1/2 pathway as a key regulator of macrophage reparative properties. Pharmacological inhibition of the MEK1/2 pathway by a MEK1/2 inhibitor (MEKi) significantly increased expression of IL-4/IL-13 (M2)-responsive genes in murine bone marrow-derived and alveolar macrophages. Deletion of the MEK1 gene using LysM^Cre+/+Mek1^fl/fl macrophages as an alternate approach yielded similar results. MEKi enhanced STAT6 phosphorylation, and MEKi-induced changes in M2 polarization were dependent on STAT6. In addition, MEKi treatment significantly increased murine and human macrophage efferocytosis of apoptotic cells, independent of macrophage polarization and STAT6. These phenotypes were associated with increased gene and protein expression of Mertk, Tyro3, and Abca1, three proteins that promote macrophage efferocytosis. We also studied the effects of MEKi on in vivo macrophage efferocytosis and polarization. MEKi-treated mice had increased efferocytosis of apoptotic polymorphonuclear leukocytes instilled into the peritoneum. Furthermore, administration of MEKi after LPS-induced lung injury led to improved recovery of weight, fewer neutrophils in the alveolar compartment, and greater macrophage M2 polarization. Collectively, these results show that MEK1/2 inhibition is capable of promoting the reparative properties of murine and human macrophages. These studies suggest that the MEK1/2 pathway may be a therapeutic target to promote the resolution of inflammation via modulation of macrophage functions.

Differential transcription profiles of long non-coding RNAs in primary human brain microvascular endothelial cells in response to meningitic Escherichia coli

Accumulating studies have indicated the influence of long non-coding RNAs (lncRNAs) on various biological processes as well as disease development and progression. However, the lncRNAs involved in bacterial meningitis and their regulatory effects are largely unknown. By RNA-sequencing, the transcriptional profiles of host lncRNAs in primary human brain microvascular endothelial cells (hBMECs) in response to meningitic Escherichia coli were demonstrated. Here, 25,257 lncRNAs were identified, including 24,645 annotated lncRNAs and 612 newly found ones. A total of 895 lncRNAs exhibited significant differences upon infection, among which 382 were upregulated and 513 were downregulated (≥2-fold, p < 0.05). Via bioinformatic analysis, the features of these lncRNAs, their possible functions, and the potential regulatory relationships between lncRNAs and mRNAs were predicted. Moreover, we compared the transcriptional specificity of these differential lncRNAs among hBMECs, human astrocyte cell U251, and human umbilical vein endothelial cells, and demonstrated the novel regulatory effects of proinflammatory cytokines on these differential lncRNAs. To our knowledge, this is the first time the transcriptional profiles of host lncRNAs involved in E. coli-induced meningitis have been reported, which shall provide novel insight into the regulatory mechanisms behind bacterial meningitis involving lncRNAs, and contribute to better prevention and therapy of CNS infection.