miR-520e and its promoter region DNA methylation as potential biomarkers in atherosclerosis.

In atherosclerosis, DNA methylation plays a key regulatory role in the expression of related genes. However, the molecular mechaism of these processes in HUVECs are unclear. Here, using high-throughput sequencing from the Infinium HumanMethylation450 assay, we manifested that the cg19564375 methylation of miR-520e promoter region in the peripheral blood of acute coronary syndrome (ACS) patients was higher than that of healthy controls. As shown by RQ-MSP, the upstream DNA methylation level of the miR-520e promoter region was considerably increased in ACS patients. miR-520e was markedly down-regulated in ACS patients compared with healthy controls. In the ox-LDL-induced HUVECs injury model, DNA methylation of the upstream region of miR-520e was significantly increased. With increasing concentrations of the methylase inhibitor 5-Aza, miR-520e expression was upregulated. The silence of methyltransferase DNMT1, rather than DNMT3a or DNMT3b, abolished the influence of miR-520e expression by ox-LDL treatment in HUVECs. A dual luciferase reporter assay revealed that miR-520e regulated the TGFBR2 3'-UTR region. After silencing TGFBR2, the promoting effect of miR-520e inhibitor on cell proliferation and migration may be attenuated. In conclusion, the expression of miR-520e is modified by its promoter region DNA methylation, and miR520e and its promoter region DNA methylation may be potential biomarkers in atherosclerosis.

[IGF-1 activates the PI3K pathway through S1P/S1PR1 signaling to promote the migration of mouse alveolar epithelial cells].

Objective To investigate the effect of insulin-like growth factor 1 (IGF-1) on the migration of alveolar epithelial cells (AECs) and its related mechanisms. Methods The MLE-12 cells (mouse AEC line) were stimulated by IGF-1 and sphingosine 1 phosphate (S1P) in the presence or absence of the PI3K inhibitor Wortmannin. Then, the cell migration was detected by the scratch test and the expression of p-Akt was detected by Western blot. With AECs stimulated by IGF-1, the secretion and expression of S1P were tested by ELISA and Western blot respectively. In the blocking experiment, the effect of IGF-1 on cell migration or p-Akt expression was detected by scratch test or Western blot after the interference of AEC S1P receptor 1 (S1PR1) or the action of S1PR1 blocking antibody. Results After 12 hours of IGF-1 stimulation, the expression of p-Akt in AECs increased and the migration of AECs accelerated. When blocking PI3K signal, the effect of IGF-1 on promoting AEC migration was partially eliminated. IGF-1 induced AECs to produce S1P, which accelerated AEC migration through S1PR1. The expression of p-Akt in AECs increased after S1P stimulation. When blocking the PI3K pathway, the ability of S1P to accelerate the migration of AECs was reduced. When S1PR1 in AECs was blocked or interfered, the effect of IGF-1 on accelerating AEC migration and promoting AEC p-Akt expression was partially reduced. Conclusion IGF-1 activates the PI3K pathway through S1P-S1PR1 signal to promote the migration of AECs.

Vascular Endothelial Growth Factor Inhibits Phagocytosis of Apoptotic Cells by Airway Epithelial Cells.

Professional phagocytes such as dendritic cells and macrophages can ingest particles larger than 0.5 µm in diameter. Epithelial cells are nonprofessional phagocytes that cannot ingest pathogenic microorganisms, but they can ingest apoptotic cells. Inhibition of the engulfment of apoptotic cells by the airway epithelium can cause severe airway inflammation. Vascular endothelial growth factor (VEGF) is an angiogenesis-promoting factor that can mediate allergic airway inflammation and can promote airway epithelial cells (AECs) proliferation, but it is not clear whether it affects the engulfment of apoptotic cells by AECs. In the present study, VEGF inhibited engulfment of apoptotic cells by AECs via binding to VEGF receptor(R)2. This inhibitory effect of VEGF was not influenced by masking of phosphatidylserine (PS) on the surface of apoptotic cells and was partially mediated by the PI3K-Akt signaling pathway. VEGF inhibition of phagocytosis involved polymerization of actin and downregulation of the expression of the phagocytic-associated protein Beclin-1 in AECs. Since engulfment of apoptotic cells by AECs is an important mechanism for airway inflammation regression, VEGF inhibition of the engulfment of apoptotic cells by airway epithelial cells may be important for mediating allergic airway inflammation.

Alveolar Epithelial Cells Promote IGF-1 Production by Alveolar Macrophages Through TGF-ß to Suppress Endogenous Inflammatory Signals.

To maintain alveolar gas exchange, the alveolar surface has to limit unnecessary inflammatory responses. This involves crosstalk between alveolar epithelial cells (AECs) and alveolar macrophages (AMs) in response to damaging factors. We recently showed that insulin-like growth factor (IGF)-1 regulates the phagocytosis of AECs. AMs secrete IGF-1 into the bronchoalveolar lavage fluid (BALF) in response to inflammatory stimuli. However, whether AECs regulate the production of IGF-1 by AMs in response to inflammatory signals remains unclear, as well as the role of IGF-1 in controlling the alveolar balance in the crosstalk between AMs and AECs under inflammatory conditions. In this study, we demonstrated that IGF-1 was upregulated in BALF and lung tissues of acute lung injury (ALI) mice, and that the increased IGF-1 was mainly derived from AMs. In vitro experiments showed that the production and secretion of IGF-1 by AMs as well as the expression of TGF-ß were increased in LPS-stimulated AEC-conditioned medium (AEC-CM). Pharmacological blocking of TGF-ß in AECs and addition of TGF-ß neutralizing antibody to AEC-CM suggested that this AEC-derived cytokine mediates the increased production and secretion of IGF-1 from AMs. Blocking TGF-ß synthesis or treatment with TGF-ß neutralizing antibody attenuated the increase of IGF-1 in BALF in ALI mice. TGF-ß induced the production of IGF-1 by AMs through the PI3K/Akt signaling pathway. IGF-1 prevented LPS-induced p38 MAPK activation and the expression of the inflammatory factors MCP-1, TNF-α, and IL-1ß in AECs. However, IGF-1 upregulated PPARγ to increase the phagocytosis of apoptotic cells by AECs. Intratracheal instillation of IGF-1 decreased the number of polymorphonuclear neutrophils in BALF of ALI model mice, reduced alveolar congestion and edema, and suppressed inflammatory cell infiltration in lung tissues. These results elucidated a mechanism by which AECs used TGF-ß to regulate IGF-1 production from AMs to attenuate endogenous inflammatory signals during alveolar inflammation.

Yes-associated protein upregulates filopodia formation to promote alveolar epithelial-cell phagocytosis.

Cells engulf particles larger than 0.5 µm in diameter by phagocytosis, which is driven by cytoskeletal rearrangements. Phagocytosis by alveolar epithelial cells (AECs) helps to maintain the alveolar homeostasis. Yes-associated protein (YAP), a transcriptional coactivator of the Hippo pathway, affects proliferation, differentiation, and cytoskeletal rearrangement of AECs, but it is not clear whether YAP regulates phagocytosis. In this study, interference with YAP expression inhibited phagocytosis in MLE-12 cells and in primary cultures of AEC. Filopodia formation promoted phagocytosis in AECs, and YAP enhanced filopodia formation in AECs. Blocking PI3K signaling resulted in reduced YAP protein expression and inhibition of phagocytosis. The results indicate that YAP expression was regulated by PI3K signaling and promoted phagocytosis in AECs by upregulating filopodia formation.

[Phagocytosis of alveolar macrophages is suppressed in a mouse model of lipopolysaccharide-induced acute lung injury].

OBJECTIVE: To investigate the changes in phagocytic function of alveolar macrophages (AMs) in mice with lipopolysaccharide (LPS)-induced acute lung injury (ALI) and explore the possible mechanism. METHODS: Kunming mice were randomly divided into normal control group and ALI (induced by LPS instillation in the airway) model group. AMs were obtained from bronchoalveolar lavage fluid in both groups, and phagocytosis of the AMs was observed using flow cytometry and fluorescence microscopy. Western blotting and ELISA were used to detect the expression and secretion of IL-33 in the lung tissue of the mice. We also detected the secretion of IL-33 by an alveolar epithelial cell line MLE-12 in response to stimulation with different concentrations of LPS. The AMs from the normal control mice were treated with different concentrations of LPS and IL-33, and the changes in the phagocytic activity of the cells were observed. RESULTS: Compared with those in normal control group, the percentage of AMs phagocytosing fluorescent microspheres was significantly decreased, and the expression of IL-33 in lung tissue and IL-33 level in the bronchoalveolar lavage fluid were significantly increased in ALI mice (P < 0.01). LPS (100-1000 ng/mL) obviously promoted the secretion of IL-33 in cultured MLE-12 cells (P < 0.01). Both LPS (10-500 ng/mL) and IL-33 (100 ng/mL) significantly inhibited the phagocytic activity of the AMs from normal control mice (P < 0.01). CONCLUSIONS: The phagocytic activity of AMs is weakened in ALI mice possibly due to direct LPS stimulation and the inhibitory effect of the alarmin IL-33 produced by LPS-stimulated alveolar epithelial cells.

[CXCR2 participates in cerebral endothelial activation and neutrophil migration in mice with septic encephalopathy].

Objective To investigate the role of CXCR2 in the cerebral endothelial activation and migration of neutrophils into the brain in septic encephalopathy (SE) induced by lipopolysaccharide (LPS). Methods C57BL/6J mice and CXCR2-knockout mice were randomly divided into a normal control group, a wildtype mice group with LPS treatment and CXCR2-knockout mice group with LPS treatment. Mouse SE models were induced by intraperitoneal LPS injection. Naphthol AS-D chloroacetate histochemical staining of the brain section was performed to quantitate the neutrophils infiltrating into the cerebral cortex. TNF-α and CXCL1 concentrations in the brain and plasma were determined by ELISA. After the stimulation of LPS (1 µg/mL) and TNF-α (200 ng/mL), the levels of CXCR2 protein in the primary mouse brain microvascular endothelial cells isolated from the cerebral cortex were detected by Western blotting. The levels of F-actin and vascular cell adhesion molecule 1 (VCAM-1) protein in the primary mouse brain microvascular endothelial cells stimulated by CXCL1 (100 ng/mL) were detected by Western blotting. Results After intraperitoneal LPS injection, there was a significant increase in the level of TNF-α in the brain and plasma and there was also an evident increase in the level of CXCL1 in the brain of wild type mice (C57BL/6J mice). And intraperitoneal LPS injection caused increased neutrophil infiltration into the cerebral cortex in the wild type mice (C57BL/6J mice). But CXCR2-knockout mice displayed evidently reduced neutrophil infiltration into the cerebral cortex compared with the wildtype mice. In vitro LPS and TNF-α upregulated the expression of CXCR2 in the primary brain microvascular endothelial cells. CXCL1 increased remarkably the expression of endothelial F-actin and VCAM-1. Conclusion In the SE model, CXCR2 participates in the cerebral endothelial activation and neutrophil migration into the brain.

Insulin­like growth factor 1 inhibits phagocytosis of alveolar epithelial cells in asthmatic mice.

The phagocytosis of apoptotic cells by alveolar epithelial cells helps to eliminate airway inflammation. Insulin­like growth factor 1 (IGF­1) regulates cell metabolism and proliferation, and promotes cell survival, while it may also promote the proliferation and differentiation of alveolar epithelial cells during the repair of lung injury. The present study investigated the effect of IGF­1 on the phagocytic activity of alveolar epithelial cells, a nonprofessional phagocyte. IGF­1 was elevated in lung tissue and bronchoalveolar lavage fluid obtained from mice with ovalbumin­induced asthma. IGF­1 was reduced by 50% in the lung tissue and by nearly 100% in the bronchoalveolar lavage fluid in asthmatic mice established by depletion of alveolar macrophages using 2­chloroadenosine. In addition, interleukin­33 induced IGF­1 production in primary alveolar macrophages. It was also observed that IGF­1 inhibited the phagocytosis of fluorescent microspheres and apoptotic cells by MLE­12 alveolar epithelial cells. Antibody blocking of IGF­1 enhanced the phagocytosis of fluorescent microspheres and apoptotic cells, and significantly reduced inflammatory cell infiltration in airway and perivascular tissues. The elevated IGF­1 level in the lungs of asthma model mice was mainly produced in alveolar macrophages. Taken together, the current study demonstrated that IGF­1 inhibited phagocytosis by alveolar epithelial cells, and that IGF­1 blockade enhanced the phagocytic activity and alleviated airway inflammation. These results support the potential use of IGF­1 as a target in the treatment of asthma.

MicroRNA-20b promotes proliferation of H22 hepatocellular carcinoma cells by targeting PTEN.

MicroRNAs (miRNAs/miRs) are small, noncoding RNA molecules that are closely associated with the occurrence and development of tumors. miR-20b is overexpressed in hepatocellular carcinoma cell lines and tissues. However, it is not clear whether miR-20b can promote the proliferation of hepatocellular carcinoma cells. In the present study, the proliferation of H22 mouse hepatocellular carcinoma cells was detected using the Cell Counting Kit-8 assay. MiRanda software was used to predict the binding sites of miR-20b to the 3'-untranslated region (3'-UTR) of phosphatase and tensin homolog (PTEN). The 3'-UTR sequence of the PTEN gene was amplified using the polymerase chain reaction in H22 cells. The recombinant plasmid or empty plasmid was co-transfected with miR-20b mimics or miR-20b scramble into HeLa cells, and luciferase activity was assessed by Dual-Luciferase® Reporter Assay System 24 h post-transfection. In the present study, miR-20b knockdown significantly inhibited the proliferation of H22 mouse hepatocellular carcinoma cells. In addition, miR-20b inhibition upregulated the expression of PTEN, and it was revealed that miR-20b may directly target the 3'-untranslated region of the PTEN gene. Downregulation of PTEN partially reversed the anti-proliferative effect of miR-20b on H22 cells. In conclusion, miR-20b may promote H22 cell proliferation by targeting PTEN, providing a rationale for further study investigating novel therapeutic strategies for liver cancer.

IGF-1 Promotes Endocytosis of Alveolar Epithelial Cells through PI3K Signaling.

Airway inflammation can be mitigated when apoptotic cells are engulfed by pulmonary epithelial cells. Insulin-like growth factor 1 (IGF-1), a single chain polypeptide growth factor, is the main mediator of growth hormone activity in vivo. IGF-1 has many biological activities, such as the regulation of cell survival, proliferation, differentiation and metabolism. However, its effect on the engulfment of cells, especially by non-professional phagocytes such as alveolar epithelial cells (AECs), has not been fully elucidated. We report that IGF-1 increases endocytosis in a mouse alveolar epithelial cell line, MLE-12. The PI3K-Akt pathway is involved in this effect of IGF-1. Furthermore, IGF-1 can inhibit the production of interleukin-6 in lipopolysaccharide-stimulated AECs. We have found that IGF-1 can enhance endocytosis of AECs through the PI3K pathway and exhibit anti-inflammatory properties. These two observations suggest that IGF-1 is a potential mediator in the regulation of airway inflammation.

Upregulated IGF­1 in the lungs of asthmatic mice originates from alveolar macrophages.

Asthma is characterized by inflammation and remodeling of the airways. Insulin­like growth factor-1 (IGF­1) serves an important role in the repair of lung tissue injury and airway remodeling by elevating collagen and elastin content, increasing the thickness of smooth muscle and promoting the proliferation of lung epithelial and interstitial cells, as well as fibroblasts; however, the content of IGF­1 and its cellular origin in the lungs of patients with asthma remain unknown. In the present study, a mouse model of asthma was constructed. Following isolation of alveolar macrophages (AMs), the content of IGF­1 in lung tissue and bronchoalveolar lavage fluid (BALF) was detected by ELISA. The proliferation and phagocytosis of alveolar epithelial cells (AECs) stimulated by IGF­1 were detected by Cell Counting Kit­8 method and flow cytometry, respectively. In the present study, IGF­1 was upregulated in the lung tissues of asthmatic mice, and the content of IGF­1 in BALF was also elevated. Depletion of AMs by treating mice with 2­chloroadenosine via nose dripping reversed the increase of IGF­1 by 80% in lung tissues and by ~100% in BALF of asthmatic mice, suggesting that elevated IGF­1 in asthmatic mice predominantly originated from AMs. As IGF­1 promotes the proliferation and phagocytosis of AECs, AM­derived IGF­1 may serve an important role in the regulation of airway inflammation and remodeling in asthmatic mice.

Reduced peripheral blood regulatory B cell levels are not associated with the Expanded Disability Status Scale score in multiple sclerosis.

Objective To investigate levels of regulatory B (Breg) cells, plasma cells, and memory B cells in the peripheral blood, and interleukin (IL)-10 in the serum of multiple sclerosis (MS) patients, and to determine the correlation between Breg cell levels and the Expanded Disability Status Scale (EDSS) score. Methods Levels of Breg cells, plasma cells, and memory B cells in the peripheral blood of 12 MS patients were measured using flow cytometry. IL-10 serum levels were measured by enzyme-linked immunosorbent assay. The correlation between Breg cell levels and MS EDSS score was measured using Pearson's correlation coefficient. Results Compared with healthy controls, MS patients had decreased levels of CD19+CD24hiCD38hi Breg cells in their peripheral blood and reduced serum levels of IL-10; however, the ratios of CD19+CD27hiCD38hi plasma cells and CD19+CD27+CD24hi memory B cells to total B cells did not differ significantly between healthy controls and MS patients. CD19+CD24hiCD38hi Breg cell levels in the peripheral blood of MS patients were not significantly correlated with MS EDSS score. Conclusion Peripheral blood CD19+CD24hiCD38hi Breg cell levels and serum IL-10 levels were reduced in MS patients compared with controls, but Breg cell levels were not correlated with MS EDSS score.