Melatonin Suppresses Macrophage M1 Polarization and ROS-Mediated Pyroptosis via Activating ApoE/LDLR Pathway in Influenza A-Induced Acute Lung Injury.

Influenza virus infection is one of the strongest pathogenic factors for the development of acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS). However, the underlying cellular and molecular mechanisms have not been clarified. In this study, we aim to investigate whether melatonin modulates macrophage polarization, oxidative stress, and pyroptosis via activating Apolipoprotein E/low-density lipoprotein receptor (ApoE/LDLR) pathway in influenza A-induced ALI. Here, wild-type (WT) and ApoE-/- mice were instilled intratracheally with influenza A (H3N2) and injected intraperitoneally with melatonin for 7 consecutive days. In vitro, WT and ApoE-/- murine bone marrow-derived macrophages (BMDMs) were pretreated with melatonin before H3N2 stimulation. The results showed that melatonin administration significantly attenuated H3N2-induced pulmonary damage, leukocyte infiltration, and edema; decreased the expression of proinflammatory M1 markers; enhanced anti-inflammatory M2 markers; and switched the polarization of alveolar macrophages (AMs) from M1 to M2 phenotype. Additionally, melatonin inhibited reactive oxygen species- (ROS-) mediated pyroptosis shown by downregulation of malonaldehyde (MDA) and ROS levels as well as inhibition of the NLRP3/GSDMD pathway and lactate dehydrogenase (LDH) release. Strikingly, the ApoE/LDLR pathway was activated when melatonin was applied in H3N2-infected macrophages and mice. ApoE knockout mostly abrogated the protective impacts of melatonin on H3N2-induced ALI and its regulatory ability on macrophage polarization, oxidative stress, and pyroptosis. Furthermore, recombinant ApoE3 (re-ApoE3) inhibited H3N2-induced M1 polarization of BMDMs with upregulation of MT1 and MT2 expression, but re-ApoE2 and re-ApoE4 failed to do this. Melatonin combined with re-ApoE3 played more beneficial protective effects on modulating macrophage polarization, oxidative stress, and pyroptosis in H3N2-infected ApoE-/- BMDMs. Our study indicated that melatonin attenuated influenza A- (H3N2-) induced ALI by inhibiting the M1 polarization of pulmonary macrophages and ROS-mediated pyroptosis via activating the ApoE/LDLR pathway. This study suggested that melatonin-ApoE/LDLR axis may serve as a novel therapeutic strategy for influenza virus-induced ALI.

[Abnormal expression of APRIL in colorectal cancer cells promotes tumor growth and metastasis].

OBJECTIVE: To investigate the effects of a proliferation-inducing ligand (APRlL) on colorectal cancer (CRC) cell growth and migration, and to observe the role of APRIL in CRC biological behavior. METHODS: The siRNA plasmid vector targeting APRIL gene (APRIL-siRNA) was transfected into human colorectal cancer SW480 cells and recombinant human APRIL (rhAPRIL) was used to stimulate human colorectal cancer HCT-116 cells. Cell proliferation activity was analyzed using cell counting kit-8 (CCK-8), cell cycle was detected by flow cytometry, and the protein expression of cyclin D1, p21 and Bcl-2 was detected by Western blot analysis. Tumor cell migration and invasion were measured by Transwell chambers. RT-PCR was applied to examine the mRNA expression level of MMP-2 and MMP-9. APRIL-siRNA was used to transfect directly SW480 cells, which were injected subcutaneously into nude mice, then the tumor growth and metastasis were observed. RESULTS: Cell proliferation ability of APRIL-siRNA-transfected SW480 cells was drastically repressed, and the percentage of G0/G1 phase cells was significantly increased (t = 4.12, P < 0.05), accompanied with depressed cyclin D1, Bcl-2 expression and elevated p21 expression. Cell proliferation ability of rhAPRIL-stimulated HCT-116 cells was promoted with a decreased G0/G1 phase ratio (t = 3.31, P < 0.05). cyclin D1 and Bcl-2 protein expression was up-regulated while p21 was down-regulated by rhAPRIL stimulation. Metastatic and invasive capacities of APRIL-siRNA-transfected SW480 cells were significantly inhibited compared with their respective controls (both P < 0.05), accompanied with the deregulated MMP-2 and MMP-9 mRNA expression. Metastatic and invasive capacities of rhAPRIL-stimulated HCT-116 cells were promoted with up-regulated MMP-2 and MMP-9 mRNA expression(both P < 0.05). Tumor growth in the group transfected with APRIL-siRNA appeared to be slower than that in the control groups and the expression of MMP-2, MMP-9 in tumor tissues was depressed in the APRIL-siRNA group. CONCLUSIONS: APRIL facilitates tumor growth and metastasis, and is associated with carcinogenesis and prognosis. Our findings suggest that APRIL might be used as a novel target for the intervention and therapy of colorectal cancer.

A sensitive method to quantify human cell-free circulating DNA in blood: relevance to myocardial infarction screening.

OBJECTIVES: Human cell-free circulating DNA (cf-DNA) derived mainly from cell apoptosis and necrosis can be measured by a variety of laboratory techniques, but almost all of these methods require sample preparation. We have developed a branched DNA (bDNA)-based Alu assay for quantifying cf-DNA in myocardial infarction (MI) patients. DESIGN AND METHODS: A total of 82 individuals were included in the study; 22 MI and 60 normal controls. cf-DNA was quantified using a bDNA-based Alu assay. RESULTS: cf-DNA was higher in serum compared to plasma and there was a difference between genders. cf-DNA was significantly higher in MI patients compared to the controls. There was no correlation between cf-DNA and creatine kinase-MB (CK-MB), troponin I (cTnI) or myoglobin (MYO). In serial specimens, cf-DNA was sensitive and peaked earlier than cTnI. CONCLUSIONS: The bDNA-based Alu assay is a novel method for quantifying human cf-DNA. Increased cf-DNA in MI patients might complement cTnI, CK-MB and MYO in a multiple marker format.

[Effects of the inhibitor of NF-kappaB and IFN-gamma on BAFF-R gene promoter activity].

AIM: To investigate the effects of IFN-gamma and the inhibitor of NF-kappaB(BAY11-7082) on BAFF-R gene promoter activity. METHODS: The fragments with different lengths of the 5'-flanking region of BAFF-R gene were amplified by PCR.Then PCR products were cloned into Luciferase reporter vector (pGL3-Basic) to construct eight recombinant plasmids. These recombinant plasmids were transiently transfected into KM3 cells to locate the promoter region with the highest activity. Then cells transfected with recombinant plasmid with the highest promoter activity were cultured on media in the absence or presence of IFN-gamma and BAY11-7082 and relative luciferase activity were tested and compared. Meanwhile BAFF-R mRNA expression were also examined and compared before and after IFN-gamma and BAY11-7082 were added into cell medium. RESULTS: IFN-gamma can promote BAFF-R promoter activity and up-regulate BAFF-R mRNA expression. And BAY11-7082 can inhibit BAFF-R promoter activity and down-regulate BAFF-R mRNA expression. CONCLUSION: IFN-gamma and the NF-kappaB pathway could be involved in regulating the transcription and mRNA expression of BAFF-R gene.

[Expression of B lymphocyte stimulator and its receptors in multiple myeloma cells: a mechanism for the cell growth and survival].

OBJECTIVE: To investigate the expression of B lymphocyte stimulator (BlyS) and its receptors in multiple myeloma (MM) cells, and to explore the relationship between BLyS and the development of human multiple myeloma. METHODS: Flow cytometry, RT-PCR and Western blot were used to examine the expression of BLyS and its receptors in MM (KM3 and CZ1) cells. Fluorescence immunocytochemical method and confocal laser scanning technique were applied to the localization of BLyS in KM3 cell. WST proliferation assay was used to examine the effect of BLyS on MM cells growth and survival. Linear correlation analysis was used to detect LDH and beta 2-microglobulin (beta2M) levels with BLyS protein and mRNA expressions in MM patients. RESULTS: (1) BLyS and its receptors were expressed in MM cells. (2) BLyS protein was localized on the KM3 plasma membrane. (3) BLyS promoted survival and proliferation of MM cells. (4) MM patients had significantly higher expression levels of BLyS [77.42% (24/31)] BLyS mRNA [93.55% (29/31)], which were significantly correlated with the levels of LDH and beta 2-microglobulin (beta2M). CONCLUSION: BLyS and its receptors in MM cell lines and MM patient bone marrow might have a potential role in the growth and survival of malignant plasma cells.

[Construction of eukaryotic expression vector for EBF3 and EGFP fusion protein and its expression in HepG2 cells].

AIM: To construct the eukaryotic expression vector for early human B-cell factor 3(EBF3) fused with the enhanced green fluorescent protein (EGFP) and express the fusion protein EBF3-EGFP in HepG2 cells. METHODS: The intact EBF3 gene was amplified from RNA isolated from the placental tissue by RT-PCR. Then it was inserted into the pEGFP-N1 vector to construct the recombinant eukaryotic expression vector pEGFP/EBF3. The fusion protein EBF3-EGFP was expressed in HepG2 cells by the transfection of pEGFP/EBF3 into the cells. RESULTS: The pEGFP/EBF3 recombinant expression vector was constructed and confirmed by DNA sequencing, enzymatic digestion and PCR identification. 24 h after the fusion protein EBF3-EGFP was transfected wiht pEGFP/EBF3, it was observed mainly in the cellular nucleus under the inverted fluorescence microscope. Both pEGFP/EBF3 and pEGFP-N1 were transfected into human HepG2 cells. 24 h after the transfection, the proportion of transfection was about 52% and 59%, respectively. Western blot analysis confirmed that the EBF3-EGFP fusion proteins of M(r) 87 000 were detected in the cytoplasmic and nuclear protein of HepG2 transfected with pEGFP/EBF3 for 24 h or 48 h. The cell proportion in S phase increased in HepG2 cells transfected with pEGFP/EBF3 in comparison with HepG2 cells transfected with pEGFP-N1 or untransfected. These findings suggested that the transfection of EBF3 gene into HepG2 induced the cell proliferation from G1 phase to G2 phase by increasing the number of cells. CONCLUSION: The construction of pEGFP/EBF3 eukaryotic expression vector and the expression of EBF3-EGFP fusion protein in HepG2 cells lay a foundation for further study of the relationship between EBF3 and its growth and the proliferation of tumor cells.