The mTORC1 pathway participate in hyper-function of B cells in immune thrombocytopenia.

B cell hyper-function plays an important role in the pathogenesis of immune thrombocytopenia (ITP), but the molecular mechanisms underlying such changes remain unclear. We sought to identify regulators of B cell dysfunction in ITP patients through transcriptome sequencing and the use of inhibitors. B cells were isolated from PBMC of 25 ITP patients for B cell function test and transcriptome sequencing. For the potential regulatory factors identified by transcriptome sequencing, the corresponding protein inhibitors were used to explore the regulatory effect of the regulatory factors on B cell dysfunction in vitro. In this study, increased antibody production, enhanced terminal differentiation and highly expressed costimulatory molecules CD80 and CD86 were found in B cells of patients with ITP. In addition, RNA sequencing revealed highly activated mTOR pathway in these pathogenic B cells, indicating that the mTOR pathway may be involved in B cell hyper-function. Furthermore, mTOR inhibitors rapamycin or Torin1 effectively blocked the activation of mTORC1 in B cells, resulting in reduce antibody secretion, impaired differentiation of B cells into plasmablasts and downregulation of costimulatory molecules. Interestingly, as an unspecific inhibitor of mTORC2 besides mTORC1, Torin1 did not show a stronger capacity to modulate B cell function than rapamycin, suggesting that the regulation of B cells by Torin1 may depend on blockade of mTORC1 rather than mTORC2 pathway. These results indicated that the activation of mTORC1 pathway is involved in B cell dysfunction in patients with ITP, and inhibition of mTORC1 pathway might be a potential therapeutic approach for ITP.

Application of Gene Therapy in Hemophilia.

Gene therapy refers to introducing normal exogenous genes into target cells to correct or compensate for the diseases caused by defective and abnormal genes for the purpose of therapy. It holds out hope of a cure for single-gene genetic diseases such as thalassemia, hemophilia, etc. At present, gene therapy is performed in two ways: introducing exogenous genes, and gene editing. A great number of clinical trials of gene therapy in hemophilia have been carried out using viral vectors to introduce foreign genes into target cells. However, the production of neutralizing antibodies following injection and the inability to prepare viral vectors in large quantities limit their application. Although gene-editing methods like CRISPR avoid the above problems, the potential risks of off-target effects are still unknown. More trials and evidence are needed to elucidate the safety and accuracy of gene therapy. This paper will review the bench and clinical work of gene therapy in hemophilia in recent years, and summarize the challenges and prospects of gene therapy, so as to provide directions for future scientific research in this field.

Global burden and attributable risk factors of acute lymphoblastic leukemia in 204 countries and territories in 1990-2019: Estimation based on Global Burden of Disease Study 2019.

To provide a foundational guideline for policy-makers to efficiently allocate medical resources in the context of population aging and growth, the latest spatial distribution and temporal trend of acute lymphoblastic leukemia (ALL) along with attributable risk factors by sex and age were mapped. Based on the Global Burden of Disease Study 2019, estimated annual percentage change (EAPC) was calculated according to the relativity between age-standardized rate and calendar year, to quantify temporal trends in morbidity and mortality of ALL. We used applied Spearman rank correlation to estimate the relationship between the EAPC and potential influence factors. The population attributable fraction of potential risk factors for ALL-related disability-adjusted life years were estimated by the comparative risk assessment framework. As a result, we found that new ALL cases increased significantly by 1.29% worldwide, and the age-standardized incidence rate increased by 1.61% annually. The proportion of elder patients sharply increased, especially within the higher socio-demographic index (SDI) region. Smoking and high body mass index remained the predominant risk factors for ALL-related mortality. Notably, the contribution of high body mass index presented an increasing trend. In conclusion, the global burden of ALL has steadily increased, especially in Middle SDI region. Health measures and new drugs should be taken into consideration to improve the management and treatment of elders with ALL due to an increasing proportion in the higher SDI region. For Low SDI areas, attention should be paid to the environmental problems caused by industrial development.

Magnitude and Temporal Trend of the Chronic Myeloid Leukemia: On the Basis of the Global Burden of Disease Study 2019.

PURPOSE: To map the magnitudes and temporal trends of chronic myeloid leukemia (CML) along with its attributable risk factors, providing the essential foundation for targeted public policies at the national, regional, and global levels. MATERIALS AND METHODS: We retrieved annual data on CML burden in 204 countries and regions from the Global Burden of Disease Study 2019 in 1990-2019. The estimated annual percentage change (EAPC) was calculated to quantify the temporal trends of CML burden by region, sex, and age group. RESULTS: Globally, the age-standardized incidence rate of CML declined weakly over the past few years (EAPC: -1.04), but the number of incident cases increased by 54.1% to 65.8 × 103 in 2019. By contrast, a dramatic drop in death and disability-adjusted life years (DALYs) rate (EAPCs: -2.55; -2.69) led to a reduction in deaths and DALYs, especially in high-income regions. In 2019, the highest age-standardized death rate was observed in Ethiopia (1.89 per 100,000). The death rate of CML was pronounced among the population age above 70 years. DALYs of CML worldwide were primarily attributable to smoking (12.2%), high body mass index (5.0%), occupational exposure to benzene (0.9%), and occupational exposure to formaldehyde (0.3%) in 2019. CONCLUSION: Although the mortality rate of CML has decreased significantly, the management of patients with CML cannot be neglected, especially in elders and developing regions.

Novel factor VII gene mutations in six families with hereditary coagulation factor VII deficiency.

INTRODUCTION: Hereditary human coagulation factor VII (FVII) deficiency is an inherited autosomal recessive hemorrhagic disease involving mutations in the F7 gene. The sites and types of F7 mutations may influence the coagulation activities of plasma FVII (FVII: C) and severity of hemorrhage symptoms. However, the specific mutations that impact FVII activity are not completely known. METHODS: We tested the coagulation functions and plasma activities of FVII in seven patients recruited from six families with hereditary FVII deficiency and sequenced the F7 gene of the patients and their families. Then, we analyzed the genetic information from the six families and predicted the structures of the mutated proteins. RESULTS: In this study, we detected 11 F7 mutations, including four novel mutations, in which the mutations p.Phe84Ser and p.Gly156Cys encoded the Gla and EGF domains of FVII, respectively, while the mutation p.Ser339Leu encoded the recognition site of the enzymatic protein and maintained the conformation of the catalytic domain structure. Meanwhile, the mutation in the 5' untranslated region (UTR) was closely associated with the mRNA regulatory sequence. CONCLUSION: We have identified novel genetic mutations and performed pedigree analysis that shed light on the pathogenesis of hereditary human coagulation FVII deficiency and may contribute to the development of treatments for this disease.

Transcription factor competition at the γ-globin promoters controls hemoglobin switching.

BCL11A, the major regulator of fetal hemoglobin (HbF, α2γ2) level, represses γ-globin expression through direct promoter binding in adult erythroid cells in a switch to adult hemoglobin (HbA, α2ß2). To uncover how BCL11A initiates repression, we used CRISPR-Cas9, dCas9, dCas9-KRAB and dCas9-VP64 screens to dissect the γ-globin promoters and identified an activator element near the BCL11A-binding site. Using CUT&RUN and base editing, we demonstrate that a proximal CCAAT box is occupied by the activator NF-Y. BCL11A competes with NF-Y binding through steric hindrance to initiate repression. Occupancy of NF-Y is rapidly established following BCL11A depletion, and precedes γ-globin derepression and locus control region (LCR)-globin loop formation. Our findings reveal that the switch from fetal to adult globin gene expression within the >50-kb ß-globin gene cluster is initiated by competition between a stage-selective repressor and a ubiquitous activating factor within a remarkably discrete region of the γ-globin promoters.

Editing aberrant splice sites efficiently restores ß-globin expression in ß-thalassemia.

The thalassemias are compelling targets for therapeutic genome editing in part because monoallelic correction of a subset of hematopoietic stem cells (HSCs) would be sufficient for enduring disease amelioration. A primary challenge is the development of efficient repair strategies that are effective in HSCs. Here, we demonstrate that allelic disruption of aberrant splice sites, one of the major classes of thalassemia mutations, is a robust approach to restore gene function. We target the IVS1-110G>A mutation using Cas9 ribonucleoprotein (RNP) and the IVS2-654C>T mutation by Cas12a/Cpf1 RNP in primary CD34+ hematopoietic stem and progenitor cells (HSPCs) from ß-thalassemia patients. Each of these nuclease complexes achieves high efficiency and penetrance of therapeutic edits. Erythroid progeny of edited patient HSPCs show reversal of aberrant splicing and restoration of ß-globin expression. This strategy could enable correction of a substantial fraction of transfusion-dependent ß-thalassemia genotypes with currently available gene-editing technology.

Indirubin modulates CD4+ T-cell homeostasis via PD1/PTEN/AKT signalling pathway in immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by an immune mediated decrease in platelet number. Disturbance of CD4+ T-cell homeostasis with simultaneous decrease of CD4+ CD25+ Foxp3+ regulatory T cells (Tregs) as well as unrestricted proliferation and activation of peripheral CD4+ effector T cells underpin the pathophysiology of ITP. Indirubin is an active ingredient of a traditional Chinese herb called Indigofera tinctoria L. which is clinically used for the treatment of ITP patients. Whether indirubin targets the Tregs/effector T cell-axis to restore platelet number is unknown. In our in vitro studies, Indirubin could significantly enhance the number and function of Tregs and meanwhile dampen the activation of effector T cells in a dose-dependent manner. Indirubin was observed to restore the expression of programmed cell-death 1 (PD1) and phosphatase and tensin homolog (PTEN) on the CD4+ T cells of ITP patients, leading to the subsequent attenuation of the AKT/mTOR pathway. Furthermore, these observations were recapitulated in an active murine model of ITP with a prominent platelet response. Thus, our results identified a potentially novel mechanism of the therapeutic action of indirubin in the treatment of ITP through regulating the homeostasis of CD4+ T cells in a PD1/PTEN/AKT signalling pathway.

Low-dose decitabine promotes megakaryocyte maturation and platelet production in healthy controls and immune thrombocytopenia.

Impaired megakaryocyte maturation and insufficient platelet production have been shown to participate in the pathogenesis of immune thrombocytopenia (ITP). Our previous study demonstrated that low expression of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in megakaryocytes contributed to impaired platelet production in ITP. Decitabine (DAC), a demethylating agent, is known to promote cell differentiation and maturation at low doses. However, whether decitabine is potential in promoting megakaryocyte maturation and platelet release in ITP is unclear. In this study, we evaluated the effect of DAC on megakaryocyte maturation and platelet release in the presence of ITP plasma that has been shown to cause impaired megakaryocyte maturation and platelet production. We observed that low-dose DAC (10 nM) could significantly increase the number of mature polyploid (≥ 4N) megakaryocytes in cultures with plasma from healthy controls and more than one-half of ITP patients in vitro. Furthermore, the number of platelets released from these megakaryocytes significantly increased compared with those untreated with DAC. In these megakaryocytes, DAC significantly enhanced TRAIL expression via decreasing its promoter methylation status. These findings demonstrate that low-dose DAC can promote megakaryocyte maturation and platelet production and enhance TRAIL expression in megakaryocytes in healthy controls and ITP. The potential therapeutic role of low-dose DAC may be beneficial for thrombocytopenic disorders.

Elevated profiles of Th22 cells and correlations with Th17 cells in patients with immune thrombocytopenia.

T-helper (Th) 22 and Th17 cells are implicated in the pathogenesis of autoimmune diseases. However, the role of Th22 cells in the pathophysiology of immune thrombocytopenia (ITP) remains unclear. Th22, Th17 and Th1 cells in both ITP patients and healthy controls were examined by flow cytometry. Plasma interleukin-22 (IL-22) level was measured by enzyme linked immunosorbent assay (ELISA). Signal transducers and activators of transcription 3 (STAT-3) and transcription factor RAR-related organ receptor C (RORC) messenger RNA (mRNA) expressions were examined by quantitative reverse transcription polymerase chain reaction (RT-PCR). Th22 cells, Th17 cells, Th1 cells and plasma IL-22 were significantly higher in ITP patients than in healthy controls. Moreover, Th22 cells showed a positive correlation with the levels of plasma IL-22 as well as Th17 and Th1 cells in ITP patients. Significant up-regulations of both STAT-3 and RORC transcription factors were also observed. Additionally, the percentage of Th22 cells was higher in autoantibody-negative ITP patients than in autoantibody-positive patients. Our results demonstrate a possible role of Th22 cells in ITP, and thus, the blockade of IL-22 may be a reasonable therapeutic strategy for ITP.

Decreased indoleamine 2,3-dioxygenase expression in dendritic cells and role of indoleamine 2,3-dioxygenase-expressing dendritic cells in immune thrombocytopenia.

Indoleamine 2,3-dioxygenase (IDO) expression in dendritic cells (DCs) can induce or maintain peripheral immune tolerance. Impaired IDO-mediated tryptophan catabolism has been observed in autoimmune diseases. In order to investigate the effects of IDO-mediated tryptophan catabolism and IDO-expressing DCs in immune thrombocytopenia, the concentrations of kynurenine were detected by high-pressure liquid chromatography. The expressions of IDO were analyzed by flow cytometry and western blot analysis. The effects of IDO(+) DCs stimulated with CTLA-4-Ig on T cells proliferation and activation, lymphocyte apoptosis, and Tregs were measured by flow cytometry. We found that the expression of IDO in DCs of immune thrombocytopenia (ITP) patients was significantly decreased. CTLA-4-Ig significantly increased the expression of functional IDO in DCs of ITP patients. IDO(+) DCs stimulated with CTLA-4-Ig suppressed T cells proliferation and activation, promoted lymphocyte apoptosis, and increased the percentage of Tregs. These results suggest that decreased IDO expression in DCs may play a critical role in ITP. CTLA-4-Ig successfully corrected the disorder of IDO expression in ITP. IDO(+) DCs stimulated with CTLA-4-Ig inhibited immune responses by an IDO-dependent mechanism. Increasing the expression and activity of IDO in DCs might be a promising therapeutic approach for ITP.

Pathway of Toll-like receptor 7/B cell activating factor/B cell activating factor receptor plays a role in immune thrombocytopenia in vivo.

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by anti-platelet autoantibody-mediated platelet destruction. Antigen-presenting cell (APC) dysfunction is considered to play crucial roles in ITP. However, how APC affects autoreactive B cells in ITP is still unknown. Using a mouse model of immune thrombocytopenia, we demonstrated an increase in levels of TLR7 in splenic mononuclear cells (SMCs). Using both TLR7 agonist and TLR7 silencing lentivirus, we found stimulation of TLR7 decreased platelet counts and increased levels of platelet-associated IgG (PAIgG) in ITP mice, which correlates TLR7 with platelet destruction by autoantibodies. Levels of serum BAFF increased significantly in ITP mice and stimulation of TLR7 promoted secretion of BAFF. Among the three BAFF receptors, only BAFF receptor (BAFF-R) increased in ITP mice. However, activation of TLR7 showed no effect on the expression of BAFF receptors. These findings indicate that upregulation of TLR7 may augment BAFF secretion by APC and through ligation of BAFF-R promote autoreactive B cell survival and thus anti-platelet autoantibody production. The pathway of TLR7/BAFF/BAFF-R provides us with an explanation of how activation of APC affects autoantibody production by B cells in ITP and thus might provide a reasonable therapeutic strategy for ITP.