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Objective@#To investigate whether CD137-CD137L signaling can affect the autophagy of mouse vascular smooth muscle cells(VSMCs) through JNK signal pathway.@*Methods@#Primary culture of C57BL/6J mouse thoracic aorta VSMCs was performed by tissue block adherence method. VSMCs between the third to fifth passages were isolated and cultured. VSMCs were divided into 4 groups: control group, CD137 agonist group, JNK inhibition group, and DMSO group. VSMCs in CD137 agonist group were treated with recombinant protein of CD137L (10 μg/ml), VSMCs in JNK inhibition group were treated with JNK inhibitor SP600125 (10 μmol/L) for 30 minutes followed by recombinant protein of CD137L (10 μg/ml) and DMSO group was treated with the same amount of DMSO in JNK inhibition group for 30 minutes, then added recombinant protein of CD137L (10 μg/ml). Western blot was used to detect the protein expression of p-JNK, LCⅡ and p62 in each group. Fluorescence microscopy was used to track the changes of autophagy in cells which was infected with adenovirus expressing tandem mRFP-GFP-LC3. Transmission electron microscope (TEM) was used to observe intracellular autophagosomes and autolysosomes.@*Results@#(1) Compared with the control group, stimulating CD137-CD137L axis by recombinant protein of CD137L significantly upregulated the expression of p-JNK, LCⅡ and p62 (1.15±0.19 vs. 0.72±0.21, P<0.05;1.03±0.13 vs. 0.59±0.15, P<0.05, and 1.10±0.19 vs. 0.76±0.15, P<0.05). These effects could be reduced by JNK inhibitor (0.61±0.21 vs. 1.15±0.19, P<0.05;0.74±0.11 vs. 1.03±0.13, P<0.05, and 0.21±0.12 vs. 1.10±0.19, P<0.05). The expression of these proteins in DMSO group remained unchanged compared with CD137 agonist group (P>0.05). (2) Changes of autophagy in cells of various group: the number of total fluorescent spots and yellow fluorescent spots in CD137 agonist group was significantly increased compared to control group (total fluorescent spots:(93.00±14.11)/cell vs. (52.33±9.61)/cell, P<0.05, and (64.33±6.81)/cell vs. (25.67±3.51)/cell, P<0.05), moreover, the number of yellow fluorescent spots was higher than the red fluorescent spots fluorescent spots in CD137 agonist group. Compared with CD137 agonist group, pretreatment with JNK inhibitor significantly reduced the number of total fluorescent spots and yellow fluorescent spots ((53.00±3.17)/cell vs. (93.00±14.11)/cell, P<0.05,and (15.33±4.51)/cell vs. (64.33±6.81)/cell, P<0.05). The red fluorescent spots were higher than the yellow fluorescent spots in JNK inhibition group. The number of total fluorescent spots and yellow fluorescent spots in CD137 agonist group was not affected by pretreatment with DMSO (P>0.05). (3) The number of intracellular autophagosomes and autolysosomes was significantly higher in CD137 agonist group than in control group((17.67±6.03)/cell vs. (5.67±2.52)/cell, P<0.05), and the number of autophagosomes was higher than that of autolysosomes in CD137 agonist group((14.00±4.00)/cell vs. (3.67±2.08)/cell, P<0.05). The number of intracellular autophagosomes and autolysosomes was significantly lower in JNK inhibition group compared to CD137 agonist group((5.67±4.04)/cell vs. (17.67±6.03)/cell, P<0.05) and the number of autophagosomes was lower than that of autolysosomes in JNK inhibition group((1.33±1.53)/cell vs. (4.33±2.52)/cell, P<0.05). The number of intracellular autophagosomes and autolysosomes was similar between DMSO group and CD137 agonist group (P>0.05).@*Conclusion@#CD137-CD137L signal may influence autophagy of mouse VSMCs via JNK pathway.
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Objective@#To investigate whether CD137 signaling promoted the formation of atherosclerotic plaque calcification by inhibiting the fusion of autophagosome and lysosome.@*Methods@#(1) In vivo, CD137 agonist antibody and anti-CD137 antibody were used to stimulate and inhibit the CD137 signaling, respectively. Fifteen Apo E-/- mice were randomly divided into three groups: control group (intraperitoneal injection of IgG2b 200 µg) , CD137 agonist group (intraperitoneal injection of CD137 agonist antibody 200 µg) , anti-CD137 group (pretreatment with 200 µg anti-CD137 antibody for 24 hours, then injection of CD137 agonist antibody) . (2) In vitro, primary culture of mouse aortic VSMCs obtained through adherence methods for tissues explants. The cells was divided into three groups: control group, agonist-CD137 group (CD137 agonist antibody 10 μg/ml) , and anti-CD137 group (pretreatment with 10 μg/ml anti-CD137 antibody for 60 minutes, then incubated with 10 μg/ml CD137 agonist antibody) . Von kossa staining was used to detect the calcification in the cell and plaque. Immunohistochemical staining was used to observe the expression of LC3B, Beclin 1 and p62 which are associated with autophagy. The levels of autophagy related protein (LC3) , Beclin 1, p62, and the expression of Runx2 and bone morphogenetic protein 2, which is associated with osteogenic differentiation in the VSMCs, were determined by Western blot. The autophagy flow of each group was detected by fluorescence microscopy. The autophagy was observed by transmission electron microscope in vivo and in vitro.@*Results@#(1) In vivo, the calcified plaque area in CD137 agonist group was significantly larger than that in the control group (3.01%±0.45% vs. 0.27%±0.06%, P<0.01) , and calcified plaque area in anti-CD137 group was significantly smaller compared with that in the CD137 agonist group (1.23%±0.39% vs. 3.01%±0.45%, P<0.05) . Immunohistochemical staining showed that the expression of early autophagy marker protein LC3B and Beclin 1 were significantly upregulated in CD137 agonist group and anti-CD137 group than in control group, and the highest expression was observed in CD137 agonist group (P<0.05) . The expression of advanced autophagy marker protein p62 was higher in the CD137 agonist group than in the anti-CD137 group (P<0.05) . (2) In vitro, the ratio of autophagy related protein LC3 Ⅱ/Ⅰ and p62 protein expression were significantly higher in CD137 agonist group and anti-CD137 group than in control group (P<0.01) , while the expression of p62 protein was significantly higher in CD137 agonist group than that in anti-CD137 group (P<0.05) . In the cell calcification inducing experiment, the expression of BMP-2 and Runx2 protein was significantly higher in CD137 agonist group than that in control group (P<0.01) , but the levels of BMP-2 and Runx2 protein were lower in anti-CD137 group than in CD137 agonist group (P<0.05) .@*Conclusion@#Our results indicate that activation of CD137 signaling can promote the formation of atherosclerotic plaque calcification by inhibiting the fusion of autophagosome and lysosome.
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Objective@#To investigate whether CD137 induces primary vascular muscle cells (VSMCs) phenotype transformation through activating nuclear factor of activated T-cells 1(NFATc1) signaling.@*Methods@#VSMCs were obtained from aorta of C57BL/6J mice (8 weeks, male) through tissue-piece inoculating. Cells were divided into control group, CD137 agonist group (treated with CD137L recombinant protein) and anti-CD137 group (treated with anti-CD137 antibody). In si-RNA transfection assay, cells were divided into si-control group and si-NFATc1 group which were transfected with control or si-NFATc1 sequence respectively. The levels of NFATc1 and other phenotype related protein such as α-smooth muscle actin (α-SMA), smooth muscle myosin heavy chain (SM-MHC), vimentin were detected by Q-PCR and Western blot. Nuclear protein expression and activity of NFATc1 were detected by immunofluorescence and Western blot. Transwell assay was performed to measure the migration of VSMCs.@*Results@#According to Western blot, the expression of NFATc1 and vimentin was significantly upregulated (5.07±0.36 vs. 1.00±0.00, P<0.05; 3.23±0.27 vs. 1.00±0.00, P<0.05) while α-SMA and SM-MHC expressions was significantly downregulated (0.73±0.15 vs. 1.00±0.00, P<0.05; 0.45±0.05 vs. 1.00±0.00, P<0.05) in CD137 agonist group compare to control group. Compared with CD137 agonist group, the expression of NFATc1 and vimentin was significantly downregulated (1.56±0.27 vs. 5.07±0.36, P<0.05; 1.21±0.17 vs. 3.23±0.27, P<0.05), but the levels of α-SMA and SM-MHC were significantly upregulated (2.01±0.43 vs. 0.73±0.15, P<0.05; 2.85 ±0.32 vs. 0.45±0.05, P<0.05) in anti-CD137 group. Compared with si-con group, the expression of SM-MHC and α-SMA was significantly upregulated while the expression of vimentin was significantly downregulated in si-NFATc1 group. Transwell assay results demonstrated that migration cell numbers was significantly higher in CD137L group compared with control group(3.85±0.31 vs. 1.00±0.00, P<0.05), this effect was significantly attenuated by inhibiting NFATc1.@*Conclusion@#CD137 could induce VSMC phenotype transformation through activating NFATc1 signaling.
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Objective@#To explore whether CD137-CD137L signaling mediated exocytosis of autophagosome within vascular smooth muscle cells (VSMCs) could influence the formation of atherosclerotic calcification.@*Methods@#Fifteen 8-week-old male ApoE-/-(C57BL/6J-KO) mice fed with high fat diet for 5 weeks were randomly divided into three groups by using stochastic indicator method as follows: control group, n=5; agonist-CD137 group: agonist-CD137 antibody 200 μg/2 weeks for 4 weeks, ip, n=5; anti-CD137 group: 200 μg anti-CD137 antibody+ 200 μg agonist-CD137 antibody/2 weeks for 4 weeks, ip, n=5. Von Kossa staining was applied to observe the calcification of the thoracic aortic atherosclerotic plaque in each group. Immunohistochemistry was used to detect the expression of LC3 and Beclin1 which were the autophage markers of early-to-mid stage; Western blot was adopted to quantify protein level of microtubule-associated proteins 1 light chain 3B(LC3B) and mammalian ortholog of the yeast autophagy-related gene 6 (Beclin1). Transmission electron microscope (TME) was used to observe the formation of autophagosome in plaque. C57BL/6J mouse VSMCs were cultured by using tissue piece inoculation method. Groups of in vitro studies were the same as in vivo study: control group, agonist-CD137 group, anti-CD137 group, the agonist-CD137 groups was treated with agonist-CD137 antibody (10 μg/ml) and anti-CD137 group was treated with anti-CD137 antibody (10 μg/ml) for 30 minutes, followed by agonist-CD137 antibody (10 μg/ml). Von Kossa staining and osteogenesis phenotypic alkaline phosphatase (ALP) activity detection were adopted to observe calcification in VSMCs. Autophagosomes were separated from the supernatant of the agonist-CD137 group with density gradient centrifugation method. VSMCs were divided into two groups: positive group (containing complete medium with above autophagosomes to a final concentration 15 μg/ml) and negative group (only complete medium) after being pretreated with mixed inflammatory cytokines (IL-1β、IFN-γ and TNF-α, final concentration was 25 ng/ml respectively) for 24 hours and calcium deposition and osteogenesis phenotypic marker bone morphogenetic protein 2(BMP2) were then detected.@*Results@#(1) Compared with the control group, activation of the CD137-CD137L signal significantly increased the formation of calcification area in thoracic aortic atherosclerotic plaque of ApoE-/- mice((1.82±0.15)×104 μm2 vs. (0.34±0.08)×104 μm2, P<0.01), this effect was significantly attenuated by inhibiting this signal ((0.83±0.30)×104 μm2 vs. (1.82±0.15)×104 μm2, P<0.05); positive autophagy makers LC3B and Beclin1 were detected in both agonist-CD137 group and anti-CD137 groups and the expression of LC3B and Beclin1 was substantially higher in anti-CD137 group. Western blot analysis indicated that the expression of LC3B and Beclin1 in agonist-CD137 group was significantly upregulated compared with the control group (0.17±0.01 vs. 0.03±0.08, P<0.05, and 0.12±0.02 vs. 0.06±0.02, P<0.05), which could be significantly downregulated in anti-CD137 group (0.28±0.09 vs. 0.17±0.01, P<0.05 and 0.17±0.02 vs. 0.12±0.02, P<0.05). TME showed that the number (QTY /HP) of autophagosome of agonist-CD137 group and anti-CD137 group in plaque were both increased (14.67±2.52 vs. 3.67±1.53, P<0.01, and 15.33±2.08 vs. 3.67±1.53, P<0.01), while in the agonist-CD137 group, the number of extracellular autophagosome within thoracic aortic atherosclerotic plaque of ApoE-/- mice increased more substantially (5.33±1.53 vs. 1.33±0.58, P<0.01). (2) In vitro study showed that activating CD137-CD137L signal could promote calcium deposition in extracellular matrix and the activity of osteogenesis phenotypic ALP((6.73±0.02) μmol/mg protein vs. (1.07±0.03) μmol/mg protein, P<0.05), and ((563.20±0.72) U/mg protein vs. (117.50±0.64) U/mg protein, P<0.05), while these effects were significantly blunted in anti-CD137 group ((1.94±0.05) μmol/mg protein vs. (6.73±0.02) μmol/mg protein, P<0.05, and (236.10±0.14) U/mg protein vs. (563.20±0.72) U/mg protein, P<0.05). TME showed that the number of intracellular autophagosome in agonist-CD137 group and anti-CD137 group was both significantly higher than in control group ((21.65±1.34) μg/ml vs. (8.32±1.58) μg/ml, P<0.01, and (15.42±1.65) μg/ml vs. (8.32±1.58) μg/ml, P<0.05). After the density gradient centrifugation, exocytotic autophagosome in the medium of agonist-CD137 group was markedly higher than in control group ((14.67±1.53) μg/ml vs. (2.33±1.15) μg/ml, P<0.01). (3) Compared with the control group, autophagosomes isolated from culture supernatant (final concentration: 15 μg/ml) could significantly stimulate calcium deposition((2.30±0.10) μmol/mg protein vs. (0.15±0.40) μmol/mg protein, P<0.05) and enhance the expression of bone morphogenetic protein 2 (2.10±0.04 vs. 0.30±0.01, P<0.05).@*Conclusion@#CD137-CD137L signaling could mediate exocytosis of autophagosome within VSMCs, thus influence the formation of atherosclerotic calcification.
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Objective To investigate effects of Danhong on the serum levels of CD137, high-sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) in patients with non-ST elevation acute myocardial infarction complicating metabolic syndrome. Methods A total of 126 patients with non-ST elevation acute myocardial infarction complicating metabolic syndrome were enrolled and randomly divided into a conventional treatment group and a Danhong treatment group using a random-digit table, with 63 patients in each group. All patients underwent angiography or percutaneous coronary intervention. The patients in the Danhong treatment group treated with intravenous Danhong 20 ml on the basis of conventional treatment for 1 week. The serum levels of CD137, hs-CRP and Hcy were measured at hospital admission and 10 days after treatment. The severity of coronary artery disease was assessed by the Gensini-score. Results The levels of CD137, hs-CRP and Hcy in both groups after treatment were significantly lower than before treatment (conventional treatment group: t 12.393, 17.408 and 9.458; Danhong treatment group: t 16.110, 17.573 and 13.481; all P<0.01), and the Danhong treatment group were significantly decreased than the conventional treatment group (t 2.815, 3.224 and 3.157, all P<0.01). The serum levels of CD137 and hs-CRP before treatment were significantly correlated with Gensini scores in 126 patients (r 0.720 and 0.562,all P<0.01). Conclusions The serum levels of CD137 and hs-CRP are significantly correlated with the severity of coronary artery disease, intravenous Danhong may has protective effect for coronary artery disease via decreasing CD137 and hs-CRP.
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4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a major costimulatory receptor that is rapidly expressed on the surface of CD4+ and CD8+ T cells after antigen- or mitogen-induced activation. The interaction of 4-1BB with 4-1BBL regulates immunity and promotes the survival and expansion of activated T cells. In this study, the expression of 4-1BB and 4-1BBL was examined during regeneration of the murine thymus following acute cyclophosphamide-induced involution. Four-color flow cytometry showed that 4-1BB and 4-1BBL were present in the normal thymus and were preferentially expressed in the regenerating thymus, mainly in CD4+CD8+ double-positive (DP) thymocytes. Furthermore, the CD4loCD8lo, CD4+CD8lo and CD4loCD8+ thymocyte subsets, representing stages of thymocyte differentiation intermediate between DP and single-positive (SP) thymocytes, also expressed 4-1BB and 4-1BBL during thymus regeneration but to a lesser degree. Interestingly, the 4-1BB and 4-1BBL positive cells among the CD4+CD8+ DP thymocytes present during thymus regeneration were TCR(hi) and CD69+ unlike the corresponding controls. Moreover, the 4-1BB and 4-1BBL positive cells among the intermediate subsets present during thymus regeneration also exhibited TCRhi/int and CD69+/int phenotypes, indicating that 4-1BB and 4-1BBL are predominantly expressed by the positively selected population of the CD4+CD8+ DP and the intermediate thymocytes during thymus regeneration. RT-PCR and Western blot analyses confirmed the presence and elevated levels of 4-1BB and 4-1BBL mRNA and protein in thymocytes during thymus regeneration. We also found that the interaction of 4-1BB with 4-1BBL promoted thymocyte adhesion to thymic epithelial cells. Our results suggest that 4-1BB and 4-1BBL participate in T lymphopoiesis associated with positive selection during recovery from acute thymic involution.