ABSTRACT
Objective To investigate the expression of sialic acid-binding immunoglobulin-like-lectin-1 (Siglec-1)in the peripheral blood mononuclear cell (PBMC) of patients with autoimmune thyroiditis ( AIT) and its relationship with AIT. To explore the moduratory role of activated Siglec-1 on the differentiation of T cells and the promotion of in flammation after PBMC culture. Methods The peripheral whole blood and serum samples were collected from 30 AIT patients with normal thyroid function and 30 sex-and age-matched controls. The expression of sSiglec-1 in serum was detected by ELISA. The expression of Siglec-1 in PBMC was detected by RT-PCR and WB. The expression of Siglec-1 in CD14+ monocytes and the proportion of Th1 and Th17 cells in each group were detected by flow cytometry. The PBMC in AIT or control was stimulated with NaI in the presence or absence of LPS for 72 h. The expression of Siglec-1 in CD14+ monocytes and the proportion of Th1 and Th17 cells were detected by flow cytometry. Results sSiglec-1 in serum, Siglec-1 mRNA, and Siglec-1 protein in AIT patients'PBMC were higher than those in control group ( P＜0. 01). The expression of Siglec-1 in CD14+ monocytes by flow cytometry and differentiation of Th1 and Th17 cells were significantly higher than that in control group ( both P＜0. 01). The expression of Siglec-1 in control and AIT patients was up-regulated by 5×10-5 mmol/L to 1×10-2 mmol/L stimulated with NaI in the presence or absence of LPS for 72 h (P＜0.01), but the differentiation of Th1 and Th17 cells was up-regulated only in patients (P＜0.01), and in a dose-dependent manner. Conclusion Elevated Siglec-1 expression in PBMCs and monocytes can potentially serve as a biomarker for AIT. Iodine may affect Th1 and Th17 cell differentiation by activating Siglec-1 to adjust the AIT immune response.
ABSTRACT
Sialoadhesin ( Siglec-1 or CD169 ) is a sialic acid-binding Ig-like lectin expressed selectively on macrophage subsets. In inflammatory response, Siglec-1 can modulate the secretion of MIP-1 alpha / beta, MCP-1, MIP-2 and other cytokines, and promote the occurrence of inflammatory reaction. During viral infection, Siglec-1 can promote the infection and phagocytosis of virus by mediating the binding of pathogens and macrophages. In the regulation of immunity, Siglec-1 can regulate innate immunity and adaptive immunity, by inhibiting the excessive expression of IFN-α and the activation of DC cells. This review mainly focuses on the new advances of research on Siglec-1 in pathogen infections, inflammation and immunoregulation.
ABSTRACT
Objective To construct lentiviral vectors containing small interfering RNA (siRNA) sequence of Siglec-1 and to screen the effective vector.Methods Three fragments of Siglec-1 siRNA were designed and cloned into pGCSIL-GFP lentiviral plasmid.And then the plasmid was cotransfected into 293T cells with pHelper 1.0 and pHelper 2.0 plasmids.Forty-eight hours later,culture supernatant with virus particles was collected and concentrated.Virus titer was determined by 10-fold serial dilution method and virus was transduced into primary cultured mouse bone marrow-derived macrophages (BMM).Flow cytometry and QRT-PCR were used to screen effective vector with inhibition ability.Results Three vshRNA lentiviral plasmids and a control plasmid were constructed successfully and verified by DNA sequencing.Virus titer was between 1×10s TU/ml and 1×109 TU/ml,which was suitable for in vitro and in vivo experiments.The Lv-1 could inhibit Siglec-1 expression effectively in vitro transduction of BMM.Conclusion Lentiviral vectors containing siRNA sequence of Siglec-1 were constructed successfully and an effective vector was screened,which may lay the foundation for using the vector in gene knockdown experiment in vivo.
ABSTRACT
Objective To explore the role of sialic acid-binding immunoglobulin-like lectin-one (Siglec-1) in the process of atherosclerotic inflammation induced by oxidized low-density hpepmtein (ox-LDL). Methods Ox-LDL was synthesized by oxidization of native LDL and different concentration of ox-LDL was added to the culture medium of RAW264.7. Forty-eight hours later, cells and supernatants were collected separately. The expression of Siglec-1 protein and mRNA were measured by flow cytometry(FCM) and real-time quantitative RT-PCR, respectively. The levels of monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1α(MIP-1α) and IL-8 in supernatants were determined by ELISA. Re-sults By the stimulation of ox-LDL, Siglec-1 protein and mRNA on RAW264.7 cells were significantly in-creased, meanwhile, the cytokines levels in culture supematants were significantly higher than that in the control group. And both Siglec-1 expression and cytokine secretion were ox-LDL dose-dependent. Conclu-sion Ox-LDL can increase Siglec-1 protein and mRNA expression and some inflammatory cytokines secre-tion on RAW264.7 cells in a dose-dependent manner. Manifested by enhanced Siglec-1 expression, the acti-vated macmphages may take a part in the development and progression of atherosclerosis.
ABSTRACT
Objective By in vitro culture of mouse macrophage cell line RAW264. 7 and primary mouse bone marrow macrophages, the expression of Siglec-1 when stimulated by ox-LDL was observed. Meanwhile, Siglec-1 was up-regulated by M-CSF and down-regulated by small interference RNA targeting Siglec-1 ( si-RNA-Siglec-1) , and the expression of chemokines and lipid uptake ability by macrophages were observed, to explore the role of Siglec-1 on macrophages in atherosclerosis. Methods LDL was oxidized by copper. According to preliminary experiment results, ox-LDL 100 μg/ml was selected as a stimulus. There were 6 experimental groups:normal control group,ox-LDL 100 μg/ml group, ox-LDL 100 μg/ml + si-RNA 2509 2 ng/ml group,ox-LDL 100 μg/ml + si-RNA 3618 2 ng/ml group,ox-LDL 100 μg/ml + M-CSF 5 ng/ml group and ox-LDL 100 μg/ml + M-CSF 10 ng/ml group. si-RNA-Siglec-1 was transfected into macrophage to inhibit the expression of Siglec-1, whereas M-CSF 10 ng/ml or 5 ng/ml were added into the culture medium to enhance the expression of Siglec-1. Quantitative real-time polymerase chain reaction ( qRT-PCR) was used to determine the interfere efficiency of si-RNA-Siglec-1 or M-CSF. After stimulation with ox-LDL for 48 h, cell culture supernatants were collected to determine MIP-1 alpha, MCP-1 and IL-8 concentration by ELISA (n =3 for each group) to evaluate the activation of macrophages. Internalization of lipid particles by macrophages was analyzed by oil red 0 staining. Results Observed by fluorescence microscope, si-RNA-Siglec-1 could be effectively transfected into macrophages with a transfection efficiency about 90% ;PCR results showed that si-RNA 2509 and si-RNA 3618 in a concentration of 40 pmol/L had an inhibition rate of 0. 54 ±0. 11 or 0. 52 ±0. 16 vs 1. 00 ±0. 24 (control group) , t =5. 227 and 4. 992, respectively, all P < 0.01, while M-CSF 10 ng/ml could increase Siglec-1 mRNA expression approximately 4-fold (4. 16 ± 1. 25 vs 1.00 ±0. 24, t =7. 448, P<0. 01). The secretion of MCP-1, MIP-1 alpha, and MIP-2 in si-RNA3618-Siglec-1 group [(359. 28±47. 80) pg/ml, (33. 76 ± 14. 28) ng/ml and (7.87±1.55) ng/ml for MCP-1,MIP-1 alpha, and MIP-2, respectively] was significantly reduced in compare with ox-LDL 100 μg/ml group [ (577. 89 ± 35. 95 ) pg/ml, (69. 17 ± 11. 82) ng/ml and (12.28 ± 1.19) ng/ml for MCP-1, MIP-1 alpha, and MIP-2, respectively], with P value of 0.01, 0.05 and 0.01. In contrary, ox-LDL 100 μg/ml plus M-CSF 10 ng/ml group could significantly promote macrophage chemokine secretion [ (672. 89 ± 43.80) pg/ml, (101.31 ±24.17) ng/ml and (14.81 ±0.54) ng/ml for MCP-1, MIP-1 alpha, and MIP-2, respectively], with P < 0.05 compared with ox-LDL 100 μg/ml group. Meanwhile, lipid intemalization and foam cell formation was inhibited in si-RNA3618-Siglec-l group while ox-LDL 100 μg/ml plus M-CSF 10 ng/ml group could enhance the phagocytosis of ox-LDL by macrophage. Conclusions Siglec-1 may served as a potential phagocytic receptor for ox-LDL involving in macrophage uptake of lipid and turn into foam cells. Furthermore, it can active macrophages and enhance the secretion of MIP-1 alpha, MCP-1 and IL-8, attracting more macrophages and lymphocytes to the site of inflammatory plaque. Targeted inhibition of Siglec-1 reduces macrophage uptake of lipid and secretion of chemokines. Siglec-1 may possibly serve as a potential target of treatment or delay the development of atherosclerosis.
ABSTRACT
Objective: To establish a real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) method for examining the expression of sialic acid-binding immunoglobulin-like lectin-one (Siglec-1)gene in the peripheral blood mononuclear cells (PBMCs) in patients with coronary heart disease (CHD),so as to explore the relationship between Siglec-1 mRNA expression and the development/progression of CHD. Methods: Based on the fluorescent SYBR Green method, a real-time quantitative RT-PCR was set up. The expression of Siglec-1 gene in the PBMCs of 57 patients with CHD and 38 healthy controls were measured by ABI PRISM 7000 Sequence Detection Systems. The blood lipid levels were determined in all the subjects by routine biochemical examination. Results: The mean Siglec-1 mRNA copy was significantly higher in the CHD group than that in the healthy control group (mean 3.23 folds, ranging 1.28-8.11 folds, P < 0.01). The expression in the acute myocardial infarction group,stable angina and unstable angina group were 3.32(1.38-7.97),2.56(0.88-7.42),and 3.35(1.25-8.96) folds that of the control group,respectively. No significant difference was observed in the normalized Siglec-1 mRNA copy number between CHD group with normal level of serum lipids and abnormal level of serum lipids. Conclusion: A real-time quantitative RT-PCR method for detecting the expression of Siglec-1 gene in PBMCs has been successfully established. The expression of Siglec-1 is dramatically increased in PBMCs in CHD patients.
ABSTRACT
Objective:To explore the role of sialic acid-binding immunoglobulin-like lectin-one (Siglec-1) in oxidized lowdensity lipoprotein (ox-LDL)-induced atherosclerotic inflammation. Methods: Ox-LDL was prepared by oxidization of native LDL ;different concentrations of ox-LDL were used to treat U937 cells for 48 h. Cells and supernatants were collected. The expression of Siglec-1 protein and mRNA was examined by flow cytometry (FCM) and real-time quantitative RT-PCR, respectively. The levels of MIP-1α, MCP-I and IL-8 in the supernatants were determined by ELISA. Results: Stimulation with ox-LDL significantly increased Siglec-1 protein and mRNA in U937 cells compared with the control group ( P < 0. 01). Meanwhile, the levels of MIP-Iα, MCP-I and IL-8 in the supernatants were also significantly increased in a concentration-dependent manner compared with those in the control group(P<0. 01). Conclusion: The proatherogenic effect of ox-LDL may be partly through up-regulating Siglec-1 expression in macrophages and enhancing the expression of inflammatory cytokines and chemokines. The activated macrophages recruit more macrophages and lymphocytes to the site of atherosclerotic plaques and exacerbate the inflammatory responses.