Preparation of CD52-targeted chimeric antigen receptor-modified T cells and their anti-leukemia effects / 中华血液学杂志

Objective: To construct chimeric antigen receptor (CAR) T cells targeting CD52 (CD52 CAR-T) and validate the effect of CD52 CAR-T cells on CD52-positive leukemia. Methods: A second-generation CD52-targeting CAR bearing 4-1BB costimulatory domain was ligated into a lentiviral vector through molecular cloning. Lentivirus was prepared and packaged by 293 T cells with a four-plasmid system. Fluorescein was used to label cell surface antigens to evaluate the phenotype of CD52 CAR-T cells after infection. Flow cytometry and ELISA were used to evaluate the specific cytotoxicity of CD52 CAR-T cells to CD52-positive cell lines in vitro. Results: ①A pCDH-CD52scFv-CD8α-4-1BB-CD3ζ-GFP expressing plasmid was successfully constructed and used to transduce T cells expressing a novel CD52-targeting CAR. ②On day 6, CD52-positive T cells were almost killed by CD52-targeted CAR-T post lentivirus transduction [CD52 CAR-T (4.48 ± 4.99) %, vs Vector-T (56.58±19.8) %, P=0.011]. ③T cells transduced with the CAR targeting CD52 showed low levels of apoptosis and could be expanded long-term ex vivo. ④The CD52 CAR could promote T cell differentiation into central and effector memory T cells, whereas the proportion of T cells with a CD45RA(+) effector memory phenotype were reduced. ⑤CD52 CAR-T cells could specifically kill CD52-positive HuT78-19t cells but had no killing effect on CD52-negative MOLT4-19t cells. For CD52 CAR-T cells, the percentage of residual of HuT78-19t cells was (2.66±1.60) % at an the E:T ratio of 1∶1 for 24 h, while (56.66±5.74) % of MOLT4-19t cells survived (P<0.001) . ⑥The results of a degranulation experiment confirmed that HuT78-19t cells significantly activated CD52 CAR-T cells but not MOLT4-19t cells[ (57.34±11.25) % vs (13.06± 4.23) %, P<0.001]. ⑦CD52 CAR-T cells released more cytokines when co-cultured with HuT78-19t cells than that of vector-T cells [IFN-γ: (3706±226) pg/ml, P<0.001; TNF-α: (1732±560) pg/ml, P<0.01]. Conclusions: We successfully prepared CD52 CAR-T cells with anti-leukemia effects, which might provide the foundation for further immunotherapy.

Preparation of CD33 targeted bispecific- and trispecific-T cell engagers and their cytotoxicity on leukemia cells / 中华血液学杂志

Objective: To investigate the effect of CD33-targeted bi-specific and tri-specific T-cell engagers on T-cell proliferation and explore their cytotoxicity on leukemia cells. Methods: The CD33-targeted bi-specific T-cell engager (CD33-BiTE) and tri-specific T-cell engager (CD33-TriTE) expression vectors were successfully constructed and expressed through a eukaryotic cell expression system. CD33-BiTE and CD33-TriTE were purified by affinity chromatography. The effects of CD33-BiTE and CD33-TriTE on T cells were analyzed through in vitro experiments. Results: ① CD33-BiTE and CD33-TriTE were successfully constructed and purified and could compete with flow cytometry antibodies for binding to the target cells. ② After 12 days of co-culture with CD33-BiTE and CD33-TriTE, the number of human T cells were expanded to 33.89±19.46 and 81.56±23.62 folds, respectively. CD33-TriTE induced a stronger proliferation of T cells than CD33-BiTE (P<0.05) . ③ Both CD33-BiTE and CD33-TriTE induced specific dose-dependent cytotoxicity on CD33(+) leukemia cells. ④ Compared to CD33-TriTE, leukemia cells were prone to express PD-L1 when co-cultured with T cells and CD33-BiTE. CD33-TriTE induced powerful cytotoxicity on leukemia cells with high PD-L1 expression. Conclusion: CD33-BiTE and CD33-TriTE expression vectors were constructed, and fusion proteins were expressed in eukaryotic cells. Our results support the proliferative and activating effects of BiTE and TriTE on T cells. Compared to that of CD33-BiTE, CD33-TriTE induced a stronger proliferative effect on T cells and a more powerful cytotoxicity on leukemia cells with high PD-L1 expression.

Functional investigation of chimeric antigen receptor T cells targeting LMP1 antigen / 中华血液学杂志

Objective: This study aimed to create a type of CAR-T cells that targets LMP1 antigen and study its immunotherapeutic effect on LMP1-positive hematological malignancies. Methods: To generate LMP1 CAR-T cells, a plasmid expressing LMP1 CAR was created using molecular cloning technology, and T cells were infected with LMP1 CAR lentivirus. The effects of LMP1 CAR-T cells on specific cytotoxicity against LMP1-positive tumor cell lines infected with the EB virus had been confirmed. Results: ① LMP1 protein expressing on EB virus-positive lymphoma cells surface was verified. ② The LMP1 CAR-expressing plasmid was created, and LMP1 CAR-T cells were obtained by infecting T cells with a lentivirus packaging system, with an infection efficiency of more than 80% . ③LMP1 CAR-T cells have a 4∶1 effect-to-target ratio in killing LMP1-positive lymphoma cells. The killing effect of LMP1 CAR-T cells on Raji cells was enhanced after 48 h of coculture, but there was no significant killing effect on Ramos, which are LMP1-negative lymphoma cells. ④After coculture with LMP1-positive lymphoma cells at a ratio of 1∶1 for 5 h, the degranulation effect was enhanced. The proportion of CD107a(+) T cells in the LMP1 CAR-T cell treatment group was significantly higher than that in the vector-T cell group [ (13.25±2.94) % vs (1.55±0.05) % , t=3.972, P=0.017]. ⑤After coculture with LMP1-positive lymphoma cells, the proportion of CD69(+) and CD25(+) T cells in the LMP1 CAR-T cell group was significantly higher than that in vector-T cell group [ (7.40±0.41) % vs (3.48±0.47) % , t=6.268, P=0.003; (73.00±4.73) % vs (57.67±2.60) % , t=2.842, P=0.047]. ⑥After coculture with LMP1-positive lymphoma cells, cytokine secretion in the LMP1 CAR-T cell group was higher than that in the vector-T cell group [interferon-gamma: (703±73) ng/L vs (422±87) ng/L, t=2.478, P=0.068; tumor necrosis factor-alpha: (215±35) ng/L vs (125±2) ng/L, t=2.536, P=0.064]. Conclusion: In this study, we found that the LMP1 protein is only found on the surface of the EBV-positive tumor cell. Simultaneously, we created an LMP1 CAR-expressing plasmid and obtained LMP1 CAR-T cells by infecting T cells with a lentivirus packaging system. Furthermore, we demonstrated that LMP1 CAR-T cells could specifically kill LMP1-positive tumor cells in vitro. The degranulation and activation effects of LMP1 CAR-T cells were enhanced after coculture with LMP1-positive tumor cells, indicating a potential clinical application.

Effect of Chemotherapeutic Drug-Induced Damage of Bone Marrow Stroma Cells on Normal Hematopoietic Cells / 中国实验血液学杂志

OBJECTIVE@#To explore the effect of damage of bone marrow stroma cells induced by chemotherapeutic drug on the function of normal hematopoitic cells.@*METHODS@#Senescence cells were detected by flow cytometry after SA-β-gal staining; real-time PCR was used to detect the expression of a serial molecules in bone marrow stromal cell line OP9 cells; the expression of γ-H2AX was determined by flow cytometry after histone γ-H2AX staining; the colony forming ability of hematopoietic cells was tested by colony formation assay.@*RESULTS@#The percentage of senescence cells in OP9 cells after DNR treatment was 2.24 times as much as that in untreated OP9 cells (P<0.05). Compared with normal OP9 cells, the expression levels of IL-6 and TNF-alpha in DNR-treated OP9 cells increased by 2.73 times (P<0.01) and 0.56 times (P<0.01), and the expression levels of N-cadherin, alpha smooth muscle actin (alpha-SMA), angiopoietin1 (Angpt1) and osteopontin (OPN) decreased by 69.54%（P<0.01），63.90%（P<0.01），87.41%（P<0.01）and 42.78%（P<0.01）respectively. After the co-culture with DNR-treated OP9 cells, the colony formation of normal hematopoietic cells decreased by 47.10% than that co-cultured with untreated OP9 cells (P< 0.05), meanwhile, the percentage of γ-H2AX+ cells in normal hematopoietic cells increased by 2.19 times (P<0.05).@*CONCLUSION@#After treatment with DNR, the senescence cell number of OP9 cells sgnificantly increases; the expression of TNF-α and IL-6 is up-regulated, while the expression of α-SMA, Angpt-1 and OPN is down-regulated as compared with normal OP9 cells. In addition, after co-culture of DNR-treated OP9 cells with normal hematopoietic cells, the colony formation ability of hematopoietic cells decreases and the genome instability of hematopoietic cells increases as compared with normal hematopoietic cells.

Oxidative Damage of Bone Marrow Stromal Cells Caused by Chemotherapy Drugs / 中国实验血液学杂志

OBJECTIVE@#To explore the oxidative damage of OP9 cells induced by daunorubicin (DNR) treatment.@*METHODS@#The TMRM probe was used to detect mitochondrial membrane potential by flow cytometry; the reactive oxygen species (ROS) was determined by flow cytometry DCFDA probe; the real-time PCR was used to detect the molecular expression of antioxidant enzyme，glutathione peroxidase (GPX) in OP9 cells; the expression of γ-H2AX was determined by flow cytometry.@*RESULTS@#Compared with normal OP9 cells, the positive rate of TMRM in DNR-treated OP9 cells decreased by 56.7% (P＜0.05); the positive rate of DCFDA in DNR-treated OP9 cells increased by 3.52 times (P＜0.01). Compared with normal OP9 cells, DNR-treated OP9 cells showed a decrease in the expression of GPX4 by 44.22% (P＜0.001); the expression of GPX7 decreased by 65.7% (P＜0.001); the expression of GPX8 decreased by 24.7% (P＜0.001); the positive rate of γ-H2AX in DNR-treated OP9 cells increased (P＜0.05).@*CONCLUSION@#After DNR treatment, mitochondrial membrane potential of OP9 cells decreases; the level of reactive oxygen species increases; the expression of glutathione peroxidase (GPX) molecules decreases significantly; genomic instability increases obviously; the oxidative damage of cells increased.

Exploration of Mechanism for Meisoindigo-Inducing K562 Cell Apoptosis by Using Quantitative Proteomic Analysis / 中国实验血液学杂志

OBJECTIVE@#To screen the differentially expressed proteins at the early stage of K562 cells treated with meisoindigo by using tandem mass tags (TMT)-based proteomics technology, and to explore the mechanism for meisoindigo-inducing apoptosis.@*METHODS@#The half inhibitory concentration (IC) of mesoindigo on K562 cells was determined by CCK8. The flow cytometry was used to assay the apoptosis of K562 cells treated by meisoindigo or DMSO. Total proteins were extracted from the cells treated with 0.2% DMSO (control) or 20 μmol/L meisoindigo (Test) for 2 hours. Then, the TMT-labeling HPLC-MS/MS was used to identify and quantify the peptides and their abundance, all the tests were repeated for 3 times. The Mascot software was used to identify the proteins; the GO annotations, enrichment and cluster analysis were used to analyze the differentially expressed proteins.@*RESULTS@#Meisoindigo-induced K562 cell apoptosis in a dose-dependent manner (r=0.98), 5 544 proteins were identified, 4792 of which were quantified. The protein with expression difference>1.5-folds in Test group accoanted for 8, out of which the expression of 4 proteins were up-regulated and 4 were down-regulated. The differentially expressed proteins mainly associated with reactive oxygen species (ROS).@*CONCLUSION@#Several proteins including DDIT4 were found to have dramatic changes in the early stage of K562 cells treated with meisoindigo by using quantitative proteomics technology. The ROS metabolic process may play important roles in meisoindigo-inducing apoptosis of K562 cells.

Expression and Asymmetric Division of Numb in Leukemia Cell K562 Line / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the role of asymmetric division in leukemia cells through detection of expression and asymmetric division of Numb in differentiated and undifferentiated K562 cells.</p><p><b>METHODS</b>Firstly, Hemin was used to induce K562 cell differentiation, and the expression of Numb was detected by the real-time quantitative RT-PCR and flow cytometry. After K562 cells were synchronized by nocodazole, the Numb protein was labeled by immunohistochemical staining, followed by the determination of the terminally differentiated cells through confocal microscopy. The fluorescence intensity was calculated by Image J software, and the cell division pattern was analyzed on the basis of the fluorescence intensities of Numb in 2 divided daughter cells.</p><p><b>RESULTS</b>Compared with the undifferentiated K562 cells, the level of Numb mRNA expression increased 2.3 times (P<0.001). The ratio of Numb positive cells was(67.37±5.01)% in differentiated K562 cells, while that was (43.97±5.72)% in undifferentiated K562 cells (P<0.01). Compared with undifferentiated K562 cells, the ratio of cells with asymmetric division in differentiated K562 cells increased 18.3%, the percentage of cells with symmetry self-renewal reduced 49.7%(P<0.001) and that with symmetry differentiation increased 32%(P<0.001).</p><p><b>CONCLUSION</b>In differentiated K562 cells, expression of Numb and proportion of cells with asymmetric division were higher than that in undifferentiated cells. With the differentiation of leukemia cells, the proportion of cells with asymmetrical division increases, and the proportion of cells with symmetrical self-renewal decreases. The stemness of leukemia cells is maintained mainly through the symmetrical self-renewal.</p>

Relationship between High Expression of c-FLIP and Drug Resistance of Leukemia Cells / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To explore the effect of c-FLIP expression on drug resistance of Kasumi-1 leukemia cells and its mechanisms.</p><p><b>METHODS</b>Tet-on inducible system was used to construct the conditional expression vector of c-FLIP by cloning the c-FLIP gene into lentivirus vector pLVX-Tight-Puro, then the Kasumi-1 cells were transfected with lentivirus pLVX-Tight-Puro-c-FLIP. The expression of c-FLIP was induced by doxycycline(Dox) for different time and doses, and verified by qRT-PCR and Western blot. On the basis of the overexpression of c-FLIP, the Kasumi-1-c-FLIP cells were treated with CH11 and PB in order to induce apoptosis, and the Giemsa staining was used to show the apoptotic cell morphology.</p><p><b>RESULTS</b>qRT-PCR and Western blot showed the overexpression of c-FLIP, the CH11 and PB can induce Kasumi-1 cell apoptosis, while the c-FLIP overexpression weakened this effects. Western blot showed that the c-FLIP blocked the caspase-8 activation.</p><p><b>CONCLUSION</b>The overexpression of c-FLIP inhibits the apoptosis caused by CH11 and PB, and leads to drug resistance in leukemia cells.</p>