Cytotoxic T Lymphocyte Antigen-4 Down-Regulates T Helper 1 Cells by Increasing Expression of Signal Transducer and Activator of Transcription 3 in Acute Graft-versus-Host Disease.

Numerous previous studies have suggested that cytotoxic T lymphocyte antigen-4 (CTLA-4) plays an important role in acute graft-versus-host disease (GVHD). How CTLA-4 acts in regulating acute GVHD remains unknown, however. In the present study, we found that, compared with healthy controls, CTLA-4 plasma and relative mRNA levels in patients with acute GVHD were initially decreased and then markedly elevated after 28 days of treatment. CTLA-4 levels were higher in patients with grade I-II acute GVHD compared with those with grade III-IV acute GVHD both before and after treatment. Up-regulation of CTLA-4 significantly increased the luciferase activity and degree of phosphorylation of signal transducer and activator of transcription 3 (STAT3). Meanwhile, T cell activation was significantly inhibited, and levels of IFN-γ, IL-17, and IL-22 decreased. These findings suggest that CTLA-4 might be involved in the pathogenesis of acute GVHD, and may down-regulate T helper 1 cells by increasing STAT3 expression in acute GVHD.

Increased expression of T cell immune response cDNA 7 in patients with acute graft-versus-host disease.

Acute graft-versus-host disease (aGVHD) has become the important complication post-allogeneic hematopoietic stem cell transplantation. Abnormally activated T cells might play an important role in the pathogenesis of aGVHD. But its exact mechanism remains poorly understood. T cell immune response cDNA 7 (TIRC7) has been identified to be essential in T cell activation; however, the role of TIRC7 in aGVHD remains unclear. The purpose of this study was to measure the expression of TIRC7 and T helper (Th) cells in patients with aGVHD before and after treatment. We showed that TIRC7 levels in aGVHD patients were higher than those of healthy controls and markedly declined after treatment. The levels of IFN-γ (Th1), IL-17 (Th17), and IL-22 (Th22) were in accordance with the grade of aGVHD. In addition, TIRC7 levels were also associated with the severity of aGVHD. In conclusion, TIRC7 might be involved in the pathogenesis of aGVHD and TIRC7 level might be an indicator to evaluate the response of patients with aGVHD to treatment.

[Effect of Hemoglobin on Efficacy of CAR-T Therapy in Patients with Multiple Myeloma].

OBJECTIVE: To investigate the effect of hemoglobin (Hb) on the efficacy of chimeric antigen receptor T cell therapy (CAR-T) in patients with multiple myeloma (MM). METHODS: From June 2017 to December 2020, 76 MM patients who received CAR-T therapy in the Department of Hematology, The Affiliated Hospital of Xuzhou Medical University, with complete clinical data and evaluable efficacy, were selected as the research objects. According to the receiver operating characteristic (ROC) curve, the best cut-off value was obtained. The patients were divided into groups on the basis of Hb 105.5 g/L as the cut-off value. The age, sex, serum calcium, ß2-microglobulin, serum creatinine, lactate dehydrogenase (LDH), and the influencing factors of CAR-T treatment efficacy in MM patients were analyzed. RESULTS: Hb was an influencing factor of efficacy. Univariate analysis showed that Hb, LDH, and albumin affected the efficacy of CAR-T therapy. Multivariate analysis showed that Hb ( OR=1.039, 95% CI: 1.002-1.078) and LDH ( OR=1.014, 95% CI: 1.000-1.027) were the influencing factors for the efficacy of CAR-T therapy. CONCLUSION: The efficacy of CAR-T therapy in MM patients with low Hb is poor, and Hb is a factor affecting the efficacy of CAR-T therapy.

Cellular Immunotherapies for Multiple Myeloma: Current Status, Challenges, and Future Directions.

Multiple myeloma (MM) remains incurable due to relapse, although the use of proteasome inhibitors, immunomodulatory drugs, CD38-targeting antibodies, and autologous stem cell transplantation (auto-SCT) significantly improve the clinical outcomes of patients with newly diagnosed MM. In recent years, the introduction of chimeric antigen receptor T-cell (CAR T-cell) therapy has brought hope to patients with refractory and relapsed MM. The graft-versus-myeloma effect of allogeneic SCT provides the possibility for curing a subset of MM patients. In this review, we summarize the recent advances and challenges of cellular immunotherapies for MM, focusing on auto-SCT, allogeneic SCT, and CAR T-cell approaches. We also discuss future directions, and propose a specific algorithm for cellular therapies for MM and probability of minimal residual disease-directed therapy.

Clinical efficacy of recombinant human thrombopoietin combined with glucocorticoids in the treatment of immune thrombocytopenia.

OBJECTIVE: Herein, we aimed to determine the clinical efficacy of recombinant human thrombopoietin (rhTPO) combined with glucocorticoids for treating immune thrombocytopenia (ITP). METHODS: Clinical data of 87 patients with ITP admitted to our hospital were retrospectively analyzed, and patients were divided into two groups according to the treatment employed: 42 patients in the control group (CG) were prescribed glucocorticoids, and 45 patients in the study group (SG) received rhTPO combined with glucocorticoids. RESULTS: The total effective treatment rate in the SG (95.56%) was higher than that in the CG (76.19%) (P < 0.05). The SG achieved a platelet (PLT) count > 50 × 109/L faster and required fewer PLT transfusions than the CG (P < 0.05). At 1, 7, and 14 days after treatment, the PLT count increased in both groups and was higher in the SG than in the CG (P < 0.05). After treatment, CD3+, CD4+, and CD4+/CD8+ T cells increased, whereas CD8 + decreased in both groups, with the SG exhibiting a superior improvement to the CG (P < 0.05). Considering prothrombin time, activated partial thromboplastin time, and fibrinogen, differences between the two groups were not statistically significant, both before and after treatment (P > 0.05). CONCLUSION: rhTPO combined with glucocorticoids for treating ITP can effectively enhance the therapeutic effect, regulate the T lymphocyte subpopulation, rapidly increase the PLT level, and induce no significant effect on the coagulation function of patients, with good safety and high clinical promotion value.

[An absence of donor TH17 differentiation ameliorates dermal tissue damage].

OBJECTIVE: To explore the functions of TH17 cell in cutaneous graft-versus-host disease (GVHD). METHODS: A model of acute GVHD (aGVHD) was established with a major histocompatibility complex class I/II-disparate allogeneic bone marrow transplantation (BMT). Bone marrow monocytes and splenic T cells from donor C57/BL6 were enriched. The recipient BABL mice were irradiated ((60)Co source) with 7.5 Gy total body irradiation (TBI) and injected with 5 × 10(6) marrow monocytes and 5 × 10(5) T cells. The experimental mice were divided into 3 groups: lethal total body irradiation (TBI); allogeneic bone marrow transplantation (BMT) and recipients of halofuginone (HF). The symptoms of aGVHD were observed daily and detailed histopathologic analyses of recipient skin were performed at Day 6 post-transplantation. And Tri-color flow cytometry (FCM) was performed at Day 6 post-transplantation to measure the levels of interleukin (IL)-17, interferon (IFN)-γ and TH1/TH17. RESULTS: Clinical GVHD symptoms were observed in recipient mice. The administration of HF to lethally irradiated recipients led to very modest GVHD-induced cutaneous changes manifested predominantly by fur loss. However, the experimental animals receiving only allogeneic BMT showed significant fur loss and pathologic skin conditions. Consistent with the clinical evaluations, the histopathologic results demonstrated significantly increased pathologic cutaneous lesions in recipients undergoing only BMT. The median ratios of TH1/TH17 cells were 17.57 and 5.31 in the HF and BMT groups respectively. The difference had statistical significance (P < 0.05). The serum levels of IL-17 were(1.47 ± 0.18) and (2.81 ± 0.19) pg/ml in the TBI and BMT groups respectively (P < 0.05). But IL-17 could not be detected in the HF group. The serum levels of IFN-γ were (3.86 ± 0.32), (42.97 ± 0.42) and (9.89 ± 0.51) pg/ml in the TBI, BMT and HF groups respectively. The inter-group differences had statistical significance (P < 0.05). CONCLUSION: An absence of TH17 cell may alleviate the cutaneous GVHD but exacerbate the systemic GVHD.

Donor-derived CD19 CAR-T cell therapy of relapse of CD19-positive B-ALL post allotransplant.

Safety and efficacy of allogeneic anti-CD19 chimeric antigen receptor T cells (CAR-T cells) in persons with CD19-positive B-cell acute lymphoblastic leukemia (B-ALL) relapsing after an allotransplant remain unclear. Forty-three subjects with B-ALL relapsing post allotransplant received CAR-T cells were analyzed. 34 (79%; 95% confidence interval [CI]: 66, 92%) achieved complete histological remission (CR). Cytokine release syndrome (CRS) occurred in 38 (88%; 78, 98%) and was ≥grade-3 in 7. Two subjects died from multiorgan failure and CRS. Nine subjects (21%; 8, 34%) developed ≤grade-2 immune effector cell-associated neurotoxicity syndrome (ICANS). Two subjects developed ≤grade-2 acute graft-versus-host disease (GvHD). 1-year event-free survival (EFS) and survival was 43% (25, 62%). In 32 subjects with a complete histological remission without a second transplant, 1-year cumulative incidence of relapse was 41% (25, 62%) and 1-year EFS and survival, 59% (37, 81%). Therapy of B-ALL subjects relapsing post transplant with donor-derived CAR-T cells is safe and effective but associated with a high rate of CRS. Outcomes seem comparable to those achieved with alternative therapies but data from a randomized trial are lacking.

[Effects of pretreatment regimen on mice liver injury in hematopoietic stem cell transplantation].

OBJECTIVE: To investigate the effects of conditioning regimen on mice liver injury during hematopoietic stem cell transplantation. METHODS: Forty healthy 8-10 weeks old female BALB/c mice were randomly divided into control group, non-myeloablative total body irradiation group, myeloablative total body irradiation group, busulfan group and cyclophosphamide group with 8 mice each. The general condition of each mouse was continuously observed. Peripheral white blood cells were counted and pathological changes of liver were examined by hematoxylin and eosin stain under microscope. The ultrastructure changes of hepatocyte and liver vascular endothelium were detected under transmission electron microscope. RESULTS: Compared to control group, each experimental group showed that the count of white blood cells was decreased significantly after conditioning pretreatments (P < 0.05). The conditioning regimen had injury effects on the mice liver in each experimental group. There were various degrees of damage to the hepatocyte and liver vascular endothelium. CONCLUSION: Total body irradiation, Busulfan and Cyclophosphamide all led to the damage of liver vascular endothelium in hematopoietic stem cell transplantation, and may be the important triggers of hepatic veno-occlusive disease.

[Investigation on the prevalence of dental caries and family oral health behaviors in young children aged 1 to 3 years in Chengdu city].

PURPOSE: To investigate the prevalence of dental caries in young children aging 1 to 3 years in Chengdu city and the relationship with family oral hygiene habits. METHODS: One thousand children aging 1 to 3 years in 5 kindergartens in Chengdu city were selected as the study subjects, and examined for oral hygiene. They were divided into case group and control group according to the presence of dental caries. Questionnaires were sent out to two groups of children to find out their oral hygiene habits, and the results were compared and analyzed with SPSS 20.0 software package. RESULTS: Three hundred and thirty-one children suffered from dental caries, and the incidence of dental caries was 33.10%. There was no significant differences in sex, low birth weight, gestational age, medical history, parents' highest educational background and main caregivers between the case group and the control group (P>0.05); there were significant differences in age distribution, feeding methods and annual family income between two groups (P<0.05). In addition to the frequency of flossing and brushing, there were significant differences in other family oral hygiene behaviors between two groups (regular dental examination, frequency of sweets eaten by children, frequency of sweets eaten before sleep and frequency of sweets eaten by parents) (P<0.05). Multivariate analysis showed that age, annual family income, sleeping with bottles, regular examination of children's teeth, frequency of children eating sweets and frequency of children eating before sleep were all influencial factors of caries in young children (P<0.05). CONCLUSIONS: Prevalence of dental caries in young children in Chengdu city is high, and there is significant correlation between dental caries in young children and family oral health behavior, which is one of the influencing factors for dental caries in young children.

[Expression and Significance of PD-1, TIM-3 and VISTA on T Cell of Acute Myeloid Leukemia Patients].

OBJECTIVE: To study the expression of multiple negative costimulatory molecules on peripheral blood T cells in patients with acute myeloid leukemia (AML) and its affection on prognosis. METHODS: The peripheral blood samples from patients with newly diagnosed AML, complete remission (CR), and no-remission (NR) were collected, the expression levels PD-1、VISTA and TIM-3 in CD4+ and CD8+ T cells were detected by flow cytometry , and the clinical data of patients were analyzed. RESULTS: The expression levels of PD-1、VISTA and TIM-3 of CD4+ and CD8+ T cells in the newly diagnosed AML patients were significantly higher than those in control group (P＜0.05). The expression levels of PD-1、TIM-3 and VISTA of CD4+ and CD8+ T cells in the CR group were significantly lower than those in newly diagnosed and the NR group (P＜0.05). The TIM-3 expression level positively correlated with VISTA expression level of CD4+ and CD8+ T cells in newly diagnosed AML patients (r=0.85 and 0.73). The VISTA and PD-1 expression level of CD4+ T cells in newly diagnosed AML, NR after first induction chemotherapy and high risk patients significantly increased (P＜0.05), the TIM-3 expression level of CD8+ T cells in high risk group significantly increased (P＜0.05), and the VISTA expression level of CD8+ T cells in CBFß-MYH11 mutation-positive group significantly decreased (P＜0.05). CONCLUSION: The expression of PD-1、TIM-3 and VISTA in AML peripheral blood T cells may be involved in the immune escape of AML and can be the targets of treatment for acute myeloid leukemia patients.

[Irradiation-induced homing of donor endothelial progenitor cells in mice allo-HSCT model].

OBJECTIVE: To investigate the effect of allo-HSCT irradiation preconditioning on the homing of donor endothelial progenitor cells (EPCs). METHODS: The mononuclear cells were collected form mice bone morrows, then cultured in EGM-2 medium. The cells were identified after 5-7 days and were labeled with CFSE. The mice were divided randomly into four groups, control, EPCs transplantation, irradiation, and irradiation EPCs transplantation. The circulating ECs, circulating EPCs and CFSE positive cells in the peripheral blood, spleen and bone morrows of the mice were measured by FCS. The histological examination, electron microscope and immunofluorescence analyses of those tissues were also performed. The distribution of labeled EPCs was observed. RESULTS: The cells were identified as CD45low, CD133+ CD31+, Dil-ac-LDL+. The number of those cells in the irradiation group increased gradually after preconditioning and reached peak at day 3 or 5 and sustained the peak level for 2 days, which was significantly different from the control (P < 0.05). Under the light microscopy and TEM, damaged endothelium was detected. In the irradiation and EPCs transplantation groups, CFSE labeled cells increased and reached peak at 18 hours, and then decreased till 72 hours. Green fluorescent cells were observed in different tissues at different times, and the strongest fluorescence intensity occurred at 36 hours. CONCLUSIONS: The EPCs can be induced from mice bone morrow mononuclear cells, with expressed phenotypic characterization. Irradiation in transplantation preconditioning can cause severe endothelium injury, which can start the mobilization of EPCs. The endothelium injury can induce extrinsic EPCs homing to the tissues which are badly injured. Endothelial progenitor cells

[Prognostic Significance of CD45dimCD117+ Cells in Patients with Acute Myeloid Leukemia after Complete Remission].

OBJECTIVE: To investigate the predictive value of CD45dimCD117+ phenotype-abnormal cells (hereinafter referred to as "abnormal cells") for relapse and prognosis in adult patients with acute myeloid leukemia (AML) within 2 weeks after the first complete remission (CR1). METHODS: The clinical data of patients with newly diagnosed AML (non-acute promyelocytic leukemia) admitted in our department from July 1, 2014 to June 30, 2017 were analyzed retrospectively, and the relationship between clinical features at the initial diagnosis and the abnormal phenotype cells of CD45dimCD117+ within 2 weeks after CR1 with the prognosis were analyzed. RESULTS: A total of 91 patients with CD45dimCD117+ abnormal cells were detected. The median age was 51 years old, the median WBC count was 11.60×109/L, and the median ratio of bone marrow blast cells was 0.35 at initial diagnosis. According to the FAB classification, 1 (1.1%), 7 (7.7%), 38 (41.7%), 20 (22.0%), 21 (23.1%) and 4 (4.4%) patients were classifice as M0, M1, M2, M4, M5, and M6, respectively. According to the NCCN risk stratification, 30 (33.0%), 51 (56.0%), and 10 (11.0%) patients were determined as good, moderate, and poor prognosis, respectively. The median ratio of abnormal cells within 2 weeks after CR1 was 1.8500 (0.0236-8.0000)%. The median time from initiation of induction therapy to the acquisition of CR was 46 days, median recurrence-free survival time was 319 days, and median overall survival time was 352 days. A total of 45 patients relapsed, of which 14 died; 46 patients did not relapse, of which 3 died. The cutoff of abnormal cells by receiver operating characteristic curve (ROC) analysis was 2.055% (Se=0.733，Sp=0.761). The abnormal cell ratio was＞2.055% in 44 patients, the median ratio of abnormal cells was 3.075%, among which 33 patients relapsed and 12 patients died; the abnormal cell ratio was ＜2.055% in 47 patients, the median ratio of abnormal cells was 1.150%, 12 patients relapsed and 5 patients died. Regression analysis showed that WBC count＞50×109/L and abnormal cell ratio＞2.055% were independent risk factors for recurrence. The abnormal cell ratio＞2.055% group had a 2-year RFS rate of 54.3% and a 2-year OS rate of 52.8%. The abnormal cell ratio＜2.055% group had a 2-year RFS rate of 86.6% (P=0.018), and a 2-year OS rate of 85.3% (P＜0.05). CONCLUSION: For adult AML patients, CD45dimCD117+ phenotypical abnormal cells ratio＞2.055% within 2 weeks after CR1 is an independent risk factor for recurrence, which also is an dverse factor for RFS and OS.

[Effect of Stably Down-regulating FMI Expression of K562 Cells on Sensitivity of K562 cells to Imatinib Mesylate].

OBJECTIVE: To investigate the effect of stably down-regulating the FMI expression of K562 cells on the sensitivity of K562 cells to Imatinib (IM) and its possible mechanism. METHODS: Western-blot was used to detect the expression of FMI protein in K562 cells and peripheral blood mononuclear cells from the patients with chronic myelogenous leukemia, chronic myeloid blast crisis and healthy volunteers. The specific interference sequences targeting at the human FMI gene were designed and ligated into the lentiviral vector LV3; the three plasmid system-packaged lentivirus particles were used to transfect K562 cells to screen K562 cells that stably down-regulated FMI. CCK-8 assay and flow cytometry were used to determine effect of IM on cell proliferation and apoptosis. The transcription level of FMI and Fz8 in leukemia cells was detected by fluorescent quantitative PCR. The protein expression levels of FMI, Fz8, NFAT1, BCR-ABL and ß-catenin in leukemia cells were detected by Western-blot. RESULTS: The expression of FMI protein could be detected in peripheral blood mononuclear cells of the patients with CML-BC and K562 cells, the FMI expression could not be detected in all the patients with CML-CP and healthy volunteers. The recombinant lentiviral vector LV3/FMI had been successfully constructed the lentivirus was packaged, and the K562 cells stably down-regulating the FMI protein were screened. After stable down-regulation of FMI expression in K562 cells, the proliferation rate of leukemia cells decreased and the apoptosis rate was increased under the same drug concentration. Both the transcription and protein expression levels of Fz8 decreased. The NFAT1 total protein level increased, as well as the nuclear translocation of protein was enhanced. There was no significant change in the expression level of BCR-ABL fusion protein. The expression level of ß-catenin protein decreased. CONCLUSION: After the stable down-regulation of FMI expression, the sensitivity of K562 cells to IM and apoptosis of cells increase, which are performed possibly by inhibiting the FMI-Fz8 signaling pathway and activating the Ca2+-NFAT and Wnt/ß-catenin signaling pathway.

[Role of Ca2+-NFAT Signaling Pathway in Ph+ ALL Drug-resistance Mediated by Bone Marrow Stromal Cells].

OBJECTIVE: To explore the role of Ca2+-NFAT signaling pathway in Ph+-ALL drug resistance mediated by bone marrow stromal cells. METHODS: The transcription level of NFAT mRNA in Sup-B15 cells and Ph+ ALL primary cells was detected by polymerase chain reaction. The expression of P-glycoprotein in Sup-B15 cells was detected by flow cytometry. The change of NFAT protein in Sup-B15 cells was detected by Western blot. AnnexinV/7-AAD was used to label cells. Flow cytometry was used to detect cell apoptosis; Fluo 3-AM dye was used to label cells, and flow cytometry used to detect changes of Ca2+ concentration in leukemia cells. RESULTS: NFAT expression could be detected in both Sup-B15 and Ph+ ALL primary cells; P-glycoprotein could not be detected by flow cytometry; CAS could significantly inhibit NFAT protein expression in clinically applied drug concentrations (2.5, 5 µmol/L); Clinically applied concentration of CAS (2.5, 5 µmol / L) has no significant effect on the apoptosis of Sup-B15 cells, while higher concentration of CAS (10 µmol / L) could induce apoptosis of Sup-B15 cells. Bone marrow stromal cells OP9 could, decrease the sensitivity of Sup-B15 cells and Ph+ ALL primary cells to imatinib (IM); After co-culture with bone were marrow stromal cells, the Ca2+ concentration in Sup-B15 cells was enhanced, the levels of NFAT protein and nullear protein in sup-B15 cells also were enhanced. The addition of CAS in co-culture system could inlibit the Ca2+-NFAT signaling pathway, reduce the protective effect of OP9 on Sup-B15 cells.Conclution:The Ca2+-NFAT sigualing pathway, contributes to the survival of Ph+ ALL cells. Bone marrow stromal cells can mediate the resistance of Ph+ ALL cells to IM by activating Ca2+-NFAT signaling pathway.

[Multivariate Analysis of Factors Influencing Recovery from Hemorrhagic Cystitis after Allo-HSCT].

OBJECTIVE: To analyze the incidence of hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplantation and the factors affecting HC, so as to provide clinical evidence for further treatment of HC. METHODS: The HC of 113 patients after allogeneic hematopoietic stem cell transplantation in Affiliated Hospital of Xuzhou Medical University between the years 2014-2016 was analyzed respectively. All cases of HC were divided into HC group and non-HC(control) group. The follow-up time: from preeonditionig day to 180 d after transplantation. The 10 clinical parameters were selected for univariate analysis with COX regression analysis: sex, age (＜25 years and 25 years), primary disease, conditioning regimen with anti-thymoglobulin(ATG), sex-mismatch in recipients, haploidential HSCT, cytomegalovirus (CMV) viremia, EB viremia, graft-versus-host disease (GVHD), and primary disease relapse, the factors significant at the 0.1 level in univariate analysis should be further evaluated by multivariate analysis using a COX regression analysis. The difference was significant at P＜0.05 in multivariate analysis. RESULTS: The HC occured in 31 of 113 patients (27.4%), with 5 cases of grade I (5.5%), 19 of grade II (16.8%), 5 of grade III (4.4%), and 2 of grade IV (1.8%). The median time of HC onset was 37 days (26-70 d) after transplantation. The median duration of HC was 14 days (5-55d). Univariate analysis showed that conditioning with anti-thymoglobulin (ATG) (RR=6.170, 95%CI: 1.875-20.306, P＜0.01), CMV viremia (RR=7.633, 95%CI：2.318-25.133) (P＜0.01), haploidentical HSCT (RR=0.307, 95%CI：0.137-0.686, P＜0.01), GVHD (RR=1.891, 95%CI：0.918-3.898, P＞0.05) were the risk factors for recovery from HC. The multivatiate analysis of above-mentioned risk factors with statistical significance showed that only CMV viremia (RR=4.770, 95%CI: 1.394-16.326, P＜0.05) was the indentified risk factor affecting the recovery from HC. CONCLUSION: Monitoring CMV viremia and antivirotic treatment are effective measurs to prevent the occurrence of HC and promote the recovery from HC.

Disruption of R867 and Y613 interaction plays key roles in JAK2 R867Q mutation caused acute leukemia.

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, constitutively active somatic JAK2 mutations were important for the leukemogenesis of acute leukemia (AL). The JAK2 R867Q somatic mutation is detected in a subset of AL patients. However, roles of JAK2 R867Q mutation in the pathogenesis of AL remain unclear. In this study, homology modeling analysis showed that loss of interaction between R867 and Y613 disrupted the JAK2 JH1/JH2 domain's interactions was responsible for its activation. JAK2 R867Q and mutations (R867A and R867G) abolished this interaction caused JAK2 constitutive activation. While, mutations (R867K, Y613E, R867K/Y613E) repairing this interaction reduced JAK2 R867Q mutation's activity. Furthermore, our studies showed that abolished R867 and Y613 interaction disrupted JH1/JH2 domains' interactions and led to JAK2 constitutive activation. More importantly, mutations (R867Q, R867A and R867G) disrupted this interaction enhanced the activity of JAK2-STAT5 pathway and the proliferation of Ba/F3 and MV4-11 cells. Further study showed that JAK2 R867Q mutation promoted the expression of proliferation marker and inhibited the differentiation marker of Ba/F3 and MV4-11 cells. Thus our studies provide clues in understanding the pathogenesis of JAK2 R867Q mutation in AL.

Roles of T875N somatic mutation in the activity, structural stability of JAK2 and the transformation of OCI-AML3 cells.

Activating mutations in JAK2 have been described in patients with various hematologic malignancies including acute myeloid leukemia (AML) and myeloproliferative neoplasms. However, mechanism of these mutations in JAK2's activity, structural stability and pathology of AML remains poorly understood. The JAK2 T875N somatic mutation has been detected in about 5.2% of AML patients. But the structural basis and mechanism of JAK2 T875N mutation in the pathology of AML is still unclear. Our results suggested that JAK2 T875N mutation disrupted the T875 and D873 interaction which destroyed the compact structure of JH1 domain, forced it into the active conformation, facilitated the entrance of substrate and thus led to JAK2 hyperactivation. Mutations (T875N, T875A, D873A and D873G) disrupted the T875 and D873 interaction enhanced JAK2's activity, decreased its structural stability and JH2 domain's activity which further enhanced JAK2's activity, while mutations (T875R, D873E, T875R/D873E) repaired this interaction displayed opposite results. Moreover, JAK2 T875N mutation enhanced the activity of JAK2-STAT5 pathway, promoted the proliferation and transformation of OCI-AML3 cells. This study provides clues in understanding structural basis of T875N mutation caused JAK2 hyperactivation and its roles in the pathology of AML.

[Curative Efficacy of Rituximab for ITP Patients with Different Sensitivity to Hormone].

OBJECTIVE: To investigatc the curative efficacy of low dose rituximab for glucocorticoid ineffective on dependent ITP patients and its relation with sensitivity to glucocorticoid so as to provide reference basis for rational use of drugs in clinical treatmant. METHODS: Seventy-ninth ITP patients enrolled in this study included the glucocorticoid-ineffective patients (19 cases) and glucocorticoid-dependent patients (60 cases). All ITP patients were treated with regimen consisted of high dose dexamethasone plus low dose rituximab (dexal-methasone 40 mg/d for 4 days per os, ritaximab 100 mg by intravenous infusion at D7, 14, 21 and 28 respectively). The patients after treatment were followed-up for 12 month, and the relation of patients sensitivity to glucocorticoid with therapentic response of rituximab was analyzed. The changes of Treg cell ratio and BAFF, IL-2 and sCD40L levels before and after treatment were detected by flow cytometry and ELISA respectively. RESULTS: The overall response rate (ORR) of patients treated with above- mentioned regemen at 1, 3, 6 and 12 months after treatment was 79.7% (63/79), 69.6% (55/79), 63.3% (50/79) and 60.8% (48/79) respectivcly, out of which the ORR of glucocorticoid ineffective and glucocorticoid-dependent ITP patients treated with above-mentioned regimen at 1, 3, 6 and 12 months after treatment was 47.4% (9/19) vs 90.0% (54/60), 36.8% (7/19) vs 80.0% (48/60), 21.1% (4/19) vs 76.7% (46/60), 21.1% (4/19) vs 73.3% (44/60), and the difference between 2 groups was statistically significant. The detection of T reg cell showed that the T reg cell ratio in glucocorticoid- ineffective and dependent patients at 1, 3, 6 and 12 months after treatment was (1.70±0.43)% vs (3.47±0.72)%, (1.66±0.33)% vs (4.29±0.91)%, (1.71±0.37)% vs (4.44±0.97)%, (3.36±0.54)% vs (4.29±1.04)%, respectively. The detection of cytokines showed that the levels of BAFF, IL-2 and sCD40L in plasma of glucocorticoid-dependent patients at 1 month after treatment significanlly decreased (P＜0.05), the levels of BAFF, IL-2 and sCD40L in plasma of glucocorticoid-ineffective patients although decreased at 1 mouth after treatment, but there was no statistical difference as compared with glucocosticoid-depenment patients. CONCLUSION: The treatment of glucocorticoid-dependent ITP patients with rituximab is more effective. The regulatory effect of rituximab on the T-reg cells, BAFF, IL-2 and sCD40L may be one of its mechanisms.

Loss of K607 and E877 interaction is a key reason for JAK2 K607N mutation caused acute myeloid leukemia.

Oncogenic activation of tyrosine kinase signaling pathway is recurrent in human leukemia. The acquired Janus kinase 2 (JAK2) K607N somatic mutation was detected in about 6.8% of acute myeloid leukemia (AML) patients. However, roles of JAK2 K607N mutation in the leukemogenesis of AML remain unclear. In this study, loss of interaction between K607 and E877 was identified as key reasons for JAK2 K607N mutation constitutive activation. JAK2 K607N and mutations (K607A, K607G and E877A) abolished the K607 and E877 interaction caused JAK2 constitutive activation. While, mutations (K607R, E877D) repairing this interaction reduced K607N mutation's activity. Furthermore, our studies showed that disruption of K607 and E877 interaction abolished JH1/JH2 domains' interactions and led to JAK2 constitutive activation. More importantly, JAK2 K607N and mutations disrupted this interaction enhanced JAK2-STAT5 pathway activation and the proliferation of Ba/F3 cells. Thus our studies provide clues in understanding the leukemogenesis of JAK2 K607N mutation in AML.

[A Modified Protocol for Rapid Establishing Mouse Model with Ph+ Positive Acute Lymphoblastic Leukemia].

OBJECTIVE: To investigate a modified protocol of establishing mouse Ph+ ALL model so as to provide a more convenient and more powerful tool for Ph+ ALL studies. METHODS: Immature B cells from BALB/c mice were transfected with the Mig190 retrovirus and infused into irradiated syngeneic mice. The immunophenotype was identified by flow cytometry, the BCR-ABL was identified by RT-PCR and Western blot. Leukemia cells isolated from sick mice were re-infused into syngeneic mice without irradiation. RESULTS: The acute lymphoblastic leukemia was established in mice after Mig190 retroviral transfection, the lymphoblasts were observed by blood smears, the immunophenotype of these leukemic cells was CD19+, and the BCR-ABL was detected by RT-PCR and Western blot, the immunophenotype was conformed as Ph+ ALL, the isolated leukemia cells infused into mice rapidly developed B-ALL. CONCLUSION: A new protocol is established to generate mice with Ph+ ALL. This mouse model can provide a more simple and effective tool in comparison with the conversional protocols.