The association of intestinal microbiota diversity and outcomes of allogeneic hematopoietic cell transplantation: a systematic review and meta-analysis.

Growing evidence suggests that highly intestinal microbiota diversity modulates host inflammation and promotes immune tolerance. Several studies have reported that patients undergoing allo-HSCT have experienced microbiota disruption that is characterized by expansion of potentially pathogenic bacteria and loss of microbiota diversity. Thus, the primary aim of this meta-analysis was to determine the association of intestinal microbiota diversity and outcomes after allo-HSCT, and the secondary aim was to analyze the associations of some specific microbiota abundances with the outcomes of allo-HSCT. Electronic databases of Pubmed, Embase, Web of Science, and Cochrane Library were searched from inception to August 2023, and 17 studies were found eligible. The pooled estimate suggested that higher intestinal microbiota diversity was significantly associated with overall survival (OS) benefit (HR = 0.66, 95% CI: 0.55-0.78), as well as decreased risk of transplant-related mortality (HR = 0.56, 95% CI: 0.41-0.76), and lower incidence of grade II-IV aGVHD (HR = 0.41, 95% CI: 0.27-0.63). Furthermore, higher abundance of Clostridiales was associated with a superior OS (HR = 0.40, 95% CI: 0.18-0.87), while higher abundance of Enterococcus (HR = 2.03, 95% CI: 1.55-2.65), γ-proteobacteria (HR = 2.82, 95% CI: 1.53-5.20), and Candida (HR = 3.80, 95% CI: 1.32-10.94) was an adverse prognostic factor for OS. Overall, this meta-analysis highlights the protective role of higher intestinal microbiota diversity on outcomes after allo-HSCT during both pre-transplant and post-transplant periods. Some specific microbiota can be useful in the identification of patients at risk of mortality, offering new tools for individualized pre-emptive or therapeutic strategies to improve allo-HSCT outcomes.

Outcome after allogeneic hematopoietic stem cell transplantation following Venetoclax-based therapy among AML and MDS patients.

The use of Bcl-2 inhibitor Venetoclax (VEN) combined with hypomethylating agents or chemotherapy has shown efficacy in treating acute myeloid leukemia (AML) as frontline treatment and for relapse, allowing more patients to bridge to allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the influence of VEN-based therapy on the prognosis of subsequent allogeneic HSCT remains unknown. We retrospectively collected data from patients who proceeded to allo-HSCT between November 2018 and November 2020 after VEN-based therapy at five transplant centers in Zhejiang Province, China. A total of 39 patients were analyzed. Thirty-one patients were diagnosed with AML (28 de novo, 3 secondary to MDS), 6 with MDS, and 2 with CMML. The majority (74.4%) of patients received VEN-based therapy for the treatment of relapse (38.5%) or refractory disease (35.9%); 5 (12.8%) received it as an initial treatment, and 5 (12.8%) patients who were already in complete remission (CR) received VEN for further consolidation or deep remission before HSCT. Twenty-seven (69.2%) patients were in CR at the time of HSCT. Day + 100 cumulative incidences of grade I-IV acute graft-versus-host disease (aGVHD) and grade II-IV aGVHD were 43.6% and 15.4%, respectively. Of 34 evaluable patients, 6.4% and 25.6% developed chronic GVHD at 1 year and 2 years. The 100-day cytomegalovirus (CMV) reactivation occurred in 76.3% of patients and Epstein-Barr virus (EBV) reactivation occurred in 29.7% of patients. With a median follow-up of 14.7 months, overall survival, progression-free survival, relapse, and non-relapse mortality incidence at 1 year were 75.5%, 61.6%, 16.7%, and 21.7%, respectively. Both univariate and multivariate analysis revealed that relapsed/refractory (R/R) disease was associated with inferior PFS (HR 4.849, 95% CI 1.009-23.30; p = 0.049). Prior poor response to VEN was found to be a significant factor predicting higher risk of relapse (HR 4.37, 95% CI 1.130-16.9; p = 0.033). Our results showed that VEN-based regimen therapy followed by allo-HSCT in AML patients is feasible and does not increase the risk of transplant-related mortality and toxicity.

The CD226-ERK1/2-LAMP1 pathway is an important mechanism for Vγ9Vδ2 T cell cytotoxicity against chemotherapy-resistant acute myeloid leukemia blasts and leukemia stem cells.

Vγ9Vδ2 T cells are attractive effector cells for immunotherapy with potent cytotoxic activity against a variety of malignant cells. However, the effect of Vγ9Vδ2 T cells on chemotherapy-resistant acute myeloid leukemia (AML) blasts, especially highly refractory leukemia stem cells (LSCs) is still unknown. In this study, we investigated the effect of cytotoxicity of allogeneic Vγ9Vδ2 T cells on chemotherapy-resistant AML cell lines, as well as on primary AML blasts and LSCs obtained from refractory AML patients. The results indicated that Vγ9Vδ2 T cells can efficiently kill drug-resistant AML cell lines in vitro and in vivo, and the sensitivity of AML cells to Vγ9Vδ2 T cell-mediated cytotoxicity is not influenced by the sensitivity of AML cells to chemotherapy. We further found that Vγ9Vδ2 T cells exhibited a comparable effect of cytotoxicity against LSCs to primary AML blasts. More importantly, we revealed that the CD226-extracellular signal-regulatory kinase1/2 (ERK1/2)-lysosome-associated membrane protein 1 (LAMP1) pathway is an important mechanism for Vγ9Vδ2 T cell-induced cytotoxicity against AML cells. First, Vγ9Vδ2 T cells recognized AML cells by receptor-ligand interaction of CD226-Nectin-2, which then induced ERK1/2 phosphorylation in Vγ9Vδ2 T cells. Finally, triggering the movement of lytic granules toward AML cells induced cytolysis of AML cells. The expression level of Nectin-2 may be used as a novel marker to predict the susceptibility/resistance of AML cells to Vγ9Vδ2 T cell treatment.

Improved survival for young acute leukemia patients following a new donor hierarchy for allogeneic hematopoietic stem cell transplantation: A phase III randomized controlled study.

The aim of our study was to evaluate the most optimal donor for young acute leukemia (AL) patients with multiple donors available for allogeneic hematopoietic stem cell transplantation (allo-HSCT), including HLA-matched sibling donors (MSDs), HLA-matched unrelated donors (URDs), haploidentical parental donors (HPDs), and haploidentical sibling donors (HSDs). From March 2008 to December 2016, 430 AL patients ≤ 35 years of age were included in the discovery, retrospective study. Patients who received transplantation from a MSD or a HSD had better 5-year OS rates compared with patients who received transplantation from a URD or a HPD. A superior graft-versus-leukemia effect was observed for high-risk patients undergoing HSD-HSCT with a lower relapse rate (p = 0.014) and a higher disease-free survival (DFS) rate (p = 0.029) compared with those undergoing MSD-HSCT. Outcomes of high-risk patients receiving an URD or HPD were equivalent. For intermediate/standard-risk patients, either a MSD or HSD may be the front-line donor selection with comparable outcomes. HLA-matched unrelated donors were preferred over HPDs with reduced non-relapse mortality and higher overall survival (OS) and DFS rates. We further conducted an independent prospective randomized study to evaluate the survival advantage with the new donor hierarchy. Two hundred and fifty patients were randomly assigned to follow our new donor hierarchy or the traditional donor hierarchy at a 2:1 ratio. The new donor hierarchy contributed to significantly superior 2-year OS and DFS rates (OS: 76.2% vs. 67.8%, p = 0.046; DFS: 71.8% vs. 64.5%, p = 0.039).

How Do We Manage Hematopoietic Cell Transplant during the SARS-CoV-2 Pandemic?

Patients receiving a hematopoietic cell transplant are thought to be at increased risk of infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and coronavirus infectious disease 2019. Transplant activities at our center continue, and notably, no patient has been infected with SARS-CoV-2. Indeed, social distancing, masking, and education for patients and donors are major pillars of prevention. We recommend potential transplant recipients and donors to be tested for SARS-CoV-2 with qRT-PCR, serum antibody detection, and a lung CT scan pretransplant. If possible, stem cells from HLA-matched unrelated donors by local processing laboratories should be cryopreserved and shipped before initiating pretransplant conditioning. An alternative HLA-haplotype-matched related donor should be identified and evaluated as a backup. The interval immediately after discharge is the time of greatest risk for SARS-CoV-2 infection because of travel and exposure to infected persons. We recommend self-isolation and minimal contact with family members. Nonessential clinic visits should be deferred or substituted with telemedicine consultations if possible. These recommendations are based on our experience at a major transplant center in China. Although some recommendations are evidence based, other recommendations are not and warrant validation in controlled trials.

Effect of CSR contribution timing during COVID-19 pandemic on consumers' prepayment purchase intentions: Evidence from hospitality industry in China.

Corporate social responsibility (CSR) contributions are essential for hospitality companies during the COVID-19 pandemic. However, little is known about how CSR contribution timing during the pandemic might affect consumers' prepayment purchase intentions. This paper takes a hospitality company as an example, using two experiments to explore (a) the effect of CSR contribution timing on consumers' prepayment purchase intentions and (b) the potential roles of psychological contracts and distance to the COVID-19 risk center. Study 1 demonstrated that CSR contributions during the COVID-19 outbreak (vs. after its peak) led consumers to have higher prepayment purchase intentions, revealing the impact of CSR contribution timing. This effect was also driven by psychological contracts between consumers and the hospitality company. Study 2 showed that, when participants were in the peripheral area of a COVID-19 outbreak, CSR contributions during the outbreak (vs. after its peak) increased prepayment purchase intentions whereas the opposite effect occurred when consumers were in the risk center.

PTPN21-CDSlong isoform inhibits the response of acute lymphoblastic leukemia cells to NK-mediated lysis via the KIR/HLA-I axis.

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) is a member of the non-receptor tyrosine phosphatase family. We have found that PTPN21 is mutated in relapsed Philadelphia chromosome-negative acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem cell transplantation. PTPN21 consists of three types of isoforms according to the length of the protein encoded. However, the roles of different isoforms in leukemic cells have not been elucidated. In the study, PTPN21 isoform constitution in five ALL cell lines were identified by transcriptome polymerase chain reaction combined with Sanger sequencing, and the relationship between PTPN21 isoforms and sensitivity to natural killer (NK) cells mediated killing in ALL cell lines were further assessed by knock-out of different isoforms of PTPN21 using CRISPR-Cas9 technique. Subsequently, we explored the functional mechanisms through RNA sequencing and confirmatory testing. The results showed that there was no significant change when all PTPN21 isoforms were knocked out in ALL cells, but the sensitivity of NALM6 cells with PTPN21-CDSlong knock-out (NALM6-PTPN21lk ) to NK-mediated killing was significantly increased. Whole transcriptome sequencing and further validation testing showed that human leukocyte antigen class I (HLA-I) molecules were significantly decreased, accompanied by a significantly downregulated expression of antigen presenting-related chaperones in NALM6-PTPN21lk cells. Our results uncovered a previously unknown mechanism that PTPN21-CDSlong and CDSshort isoforms may play opposite roles in NK-mediated killing in ALL cells, and showed that the endogenous PTPN21-CDSlong isoform inhibited ALL cells to NK cell-mediated lysis by regulating the KIR-HLA-I axis.

Haploinsufficiency of NR3C1 drives glucocorticoid resistance in adult acute lymphoblastic leukemia cells by down-regulating the mitochondrial apoptosis axis, and is sensitive to Bcl-2 blockage.

BACKGROUND: Relapse represents the leading cause of death in both child and adult patients with acute lymphoblastic leukemia (ALL). Development of chemo-resistance is ultimately responsible for treatment failure and relapse, therefore understanding the molecular basis underlying resistance is imperative for developing innovative treatment strategies. Glucocorticoids (GCs) such dexamethasone and prednisolone are the backbone of combination chemotherapy regimens for treating all lymphoid tumors. However, the biological mechanisms of primary GC resistance in ALL is not completely understood. We previously performed a longitudinal whole-exome sequencing analysis on diagnosis/relapse pairs from adult patients with ALL. Our data revealed that relapse-specific truncation mutations in the NR3C1 gene, encoding the GC receptor, are frequently detected. METHODS: In the current study, we used discovery-based strategies including RNA sequencing (RNA-seq) and CRISPR/Cas9, followed by confirmatory testing, in human ALL cell lines, bone marrow blast samples from ALL patients and xenograft models, to elucidate the mechanisms responsible for resistance. RESULTS: Our results revealed a positive correlation between endogenous expression of NR3C1 in ALL cells and sensitivity to GCs and clinical outcomes. We further confirmed that ectopic expression of NR3C1 in ALL cells could reverse GC resistance, while deletion of NR3C1 confers resistance to GCs in ALL cell lines and xenograft models. RNA-seq analysis revealed a remarkable abundance of gene signatures involved in pathways in cancer, DNA replication, mismatch repair, P53 signalling, cell cycle, and apoptosis regulated by NR3C1. Significantly increased expression of pro-apoptotic genes including BCL2L11/Bim, BMF, BAD, BAX and BOK, and decreased transcription of anti-apoptotic genes including BCL2, BCL2L1 and BAG2 were observed in GC-resistant ALL cells following ectopic expression of NR3C1. Finally, we explored that GC resistance in ALL cells with haploinsufficiency of NR3C1 can be treated with Bcl-2 blockage. CONCLUSIONS: Our findings suggest that the status of NR3C1 gene mutations and basal expression levels of NR3C1 in ALL cells are associated with sensitivity to GCs and clinical treatment outcomes. Early intervention strategies by rational combination of Bcl-2 blockage may constitute a promising new treatment option to GC-resistant ALL and significantly improving the chances of treating poor prednisone responders.

Sequential treatment combining cladribine-based re-induction, myeloablative allogeneic HSCT, and prophylactic donor lymphocyte infusion: a promising treatment for refractory acute myeloid leukemia.

We describe the first multicenter prospective study to assess the efficacy, safety, and immune reconstitution of a novel sequential transplant approach in 24 patients with primary induction failure/relapsed acute myeloid leukemia (AML). The sequential regimen consisted of cladribine 5 mg/m2/day and cytarabine 2 g/m2/day for 5 days and mitoxantrone 7 mg/m2/day for 3 days, followed by myeloablative allogeneic hematopoietic stem cell transplantation (allo-HSCT) using intravenous busulfan (3.2 mg/kg/day) for 4 days and cyclophosphamide (60 mg/kg/day) for 2 days. Patients in CR without acute graft-versus-host disease at day + 90 received prophylactic donor lymphocyte infusion (pDLI). At the time of transplantation, a marrow blast infiltration > 20% or any level of circulating blasts was found in 62.5% of patients. The cumulative incidence of relapse at 2 years was 29.8%. Overall survival (OS) was 74.5% at 1 year and 56.5% at 2 years. Leukemia-free survival (LFS) at 1 and 2 years was 62.5 and 50.5%, respectively. Multivariate analysis demonstrated that haploidentical related donor, pDLI, and experiencing chronic graft-versus-host disease (cGVHD) were protective from relapse. Total T cells and T cell subsets in peripheral blood recovered at 3 months post-HSCT. The expressions of immune checkpoints (cytotoxic T lymphocyte antigen 4 and programmed death 1) were extremely low in T cells over the first 1 year post-transplantation.

Cotransplantation of haploidentical hematopoietic stem cells and allogeneic bone marrow-derived mesenchymal stromal cells as a first-line treatment in very severe aplastic anemia patients with refractory infections.

OBJECTIVES: In patients with very severe aplastic anemia (VSAA), neutropenia is prolonged and persistent, resulting in refractory overwhelming infections. Hematopoiesis recovery is urgently needed. METHODS: Six patients with de novo VSAA lacking HLA-identical sibling donors and those who experienced refractory infections underwent haploidentical related donor (HRD) hematopoietic stem cell transplantation (HSCT) as a first-line therapy. The conditioning regimen consisted of busulfan, cyclophosphamide, and rabbit antithymocyte globulin. Culture-expanded allogeneic bone marrow-derived mesenchymal stromal cells were infused on day 0 and day +14. RESULTS: From diagnosis to HSCT, 6 patients experienced a total of 28 episodes of persistent fever, and the median number was 4 (range, 3-7). All cases developed major bacterial infections and invasive pulmonary fungal infection pre-HSCT. The median time from diagnosis to HSCT was 2 months (range, 1-3.5 months). All patients achieved sustained, full donor chimerism, and the median time of myeloid recovery and platelet engraftment was 13 days (range, 9-19 days) and 15.5 days (range, 10-23 days), respectively. One patient died of aGVHD, and 5 patients are alive after a median follow-up of 21 months (range 17-40.5). CONCLUSIONS: Upfront HRD-HSCT may be a safe and promising choice for patients with VSAA in critical situations without suitably matched donors.

T-cell-replete haploidentical HSCT with low-dose anti-T-lymphocyte globulin compared with matched sibling HSCT and unrelated HSCT.

We developed an approach of T-cell-replete haploidentical hematopoietic stem cell transplantation (HSCT) with low-dose anti-T-lymphocyte globulin and prospectively compared outcomes of all contemporaneous T-cell-replete HSCT performed at our center using matched sibling donors (MSDs), unrelated donors (URDs), and haploidentical related donors (HRDs). From 2008 to 2013, 90 patients underwent MSD-HSCT, 116 underwent URD-HSCT, and 99 underwent HRD-HSCT. HRDs were associated with higher incidences of grades 2 to 4 (42.4%) and severe acute graft-versus-host disease (17.2%) and nonrelapse mortality (30.5%), compared with MSDs (15.6%, 5.6%, and 4.7%, respectively; P < .05), but were similar to URDs, even fully 10/10 HLA-matched URDs. For high-risk patients, a superior graft-versus-leukemia effect was observed in HRD-HSCT, with 5-year relapse rates of 15.4% in HRD-HSCT, 28.2% in URD-HSCT (P = .07), and 49.9% in MSD-HSCT (P = .002). Furthermore, 5-year disease-free survival rates were not significantly different for patients undergoing transplantation using 3 types of donors, with 63.6%, 58.4%, and 58.3% for MSD, URD, and HRD transplantation, respectively (P = .574). Our data indicate that outcomes after HSCT from suitably matched URDs and HRDs with low-dose anti-T-lymphocyte globulin are similar and that HRD improves outcomes of patients with high-risk leukemia. This trial was registered at www.chictr.org (Chinese Clinical Trial Registry) as #ChiCTR-OCH-12002490.

Mutations in tyrosine kinase and tyrosine phosphatase and their relevance to the target therapy in hematologic malignancies.

Protein tyrosine kinases and protein tyrosine phosphatases play pivotal roles in regulation of cellular phosphorylation and signal transduction with opposite functions. Accumulating evidences have uncovered the relevance of genetic alterations in these two family members to hematologic malignancies. This review underlines progress in understanding the pathogenesis of these genetic alterations including mutations and aberrant expression and the evolving protein tyrosine kinases and protein tyrosine phosphatases targeted therapeutic strategies in hematologic neoplasms.

Risk-factor analysis of poor graft function after allogeneic hematopoietic stem cell transplantation.

The objective of this study was to investigate the main risk factors for poor graft function (PGF) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), to allow the improvement of transplantation outcomes through preventive measures. Clinical data for 124 patients who received allo-HSCT were analyzed retrospectively. There were 83 males (66.9%) and 41 females (33.1%) with a median age of 28 years (4-60 years). The median follow-up time was 7 months (1-116 months). Factors analyzed included age, gender, disease diagnosis, source of hematopoietic stem cells, donor type, human leukocyte antigen (HLA) matching, conditioning regimen, numbers of infused mononuclear cells and CD34(+) cells, donor-recipient sex and blood-type matching, prophylactic treatment of graft-versus-host disease (GVHD), grades of GVHD, Epstein-Barr virus or cytomegalovirus (CMV) infection, post-transplantation lymphoproliferative disorders and hepatic veno-occlusive disease. Data were analyzed by univariate and multivariate conditional logistic regression analyses. Among the 124 patients who underwent allo-HSCT, 15 developed PGF (12.1%). Univariate logistic regression analysis identified age, donor-recipient blood type and CMV infection (in 30 days) as potential risk factors for PGF. Multivariate analysis of factors with P<0.1 in univariate analysis showed that age, donor-recipient blood type and CMV infection (in 30 days) were significant risk factors for PGF. Patients were divided into subgroups based on age <20, 20-30, 30-40, and >40 years. The risk of PGF increased 2.747-fold (odds ratio (OR)=2.625, 95% confidence interval: 1.411-5.347) for each increment in age level. Patients with mismatched blood type (OR=4.051) or CMV infection (OR=9.146) had an increased risk of PGF. We conclude that age, donor-recipient blood-type matching and CMV infection are major risk factors for PGF after allo-HSCT.

Analysis of factors influencing family farms' adoption of green prevention and control techniques on an integrative framework of the TPB and NAM.

The application of green prevention and control techniques (GCTs) is a vital measure for improving the quality of agricultural products and enhancing the safety of the ecological environment and agricultural production. However, realistically, limited by the small-scale, part-time and decentralized business model, the adoption of GCTs by family farms in China faces practical problems such as insufficient internal transformation force and ability, as well as low external supervision efficiency. To reveal the directions of promoting family farms' GCTs adoption behavior, we establish a comprehensive theoretical model through the application of a novel integrated approach combining two dominant psychological theories of behavior change: the Theory of Planned Behavior (TPB) and the Norm Activation Model (NAM). We apply this framework to targeted research of vegetable growers in Henan Province in China using survey data (sample n = 653) analyzed through structural equation modeling (SEM). The integrated TPB-NAM model provides insight into both internal motivation and external environmental conditions for farmers' predicted adoption of GCTs. First, internal motivation, value cognition and personal norms are all driving factors affecting the GCTs behavioral intention of vegetable family farms. When GCTs are driven by the dual motivations of "self-interest" (personal norms) and "others-interest" (value cognition), personal norms can be activated by two factors: awareness of consequences and responsibility attribution. Furthermore, social norms, capital endowment and government regulation are the pressure and obstacle factors affecting the GCTs application of vegetable family farms. Social norms can indirectly affect the application of GCTs by forming personal norms. In addition, there are differences between the influencing factors and mechanism of GCTs adoption behavior intention of family farms of different sizes. Based on this, we propose some specific policy suggestions from three aspects: enhance value cognition, improve environmental awareness and responsibility perception, fill in the shortcomings of capital endowment, and implement differentiated incentive and restraint policies.

Overexpression of PTPN21 promotes proliferation of EGF-stimulated acute lymphoblastic leukemia cells via the MAPK signaling pathways.

OBJECTIVES: This study aims to investigate the role of excessive Protein Tyrosine Phosphatase Non-Receptor Type 21 (PTPN21) in the proliferation of Acute Lymphoblastic Leukemia (ALL) cells with EGF stimulation. METHODS: PTPN21 was overexpressed in ALL cell lines by lentiviral transfection. Apoptosis was assayed by Annexin V/7-AAD staining. The proliferation and cell cycle of EGF-treated ALL cells were assessed by MTT and Ki-67/7-AAD staining respectively. The phosphorylation of Src tyrosine kinase and mediators of distinct MAPK pathways were assessed by Western blot. RESULTS: Overexpression of PTPN21 had minimal effect on the apoptosis of ALL cells, but significantly promoted the proliferation and cell cycle progression of ALL cells stimulated with EGF. The activity of Src tyrosine kinase and the MAPK pathways was elevated. Inhibition of MAPK pathways by specific inhibitors mitigated this pro-proliferative effect of excessive PTPN21 on EGF-stimulated ALL cells. CONCLUSION: PTPN21 may facilitate ALL progression by promoting cell proliferation via the Src/MAPK signaling pathways.

Gut microbiota, microbiota-derived metabolites, and graft-versus-host disease.

Allogeneic hematopoietic stem cell transplantation is one of the most effective treatment strategies for leukemia, lymphoma, and other hematologic malignancies. However, graft-versus-host disease (GVHD) can significantly reduce the survival rate and quality of life of patients after transplantation, and is therefore the greatest obstacle to transplantation. The recent development of new technologies, including high-throughput sequencing, metabolomics, and others, has facilitated great progress in understanding the complex interactions between gut microbiota, microbiota-derived metabolites, and the host. Of these interactions, the relationship between gut microbiota, microbial-associated metabolites, and GVHD has been most intensively researched. Studies have shown that GVHD patients often suffer from gut microbiota dysbiosis, which mainly manifests as decreased microbial diversity and changes in microbial composition and microbiota-derived metabolites, both of which are significant predictors of poor prognosis in GVHD patients. Therefore, the purpose of this review is to summarize what is known regarding changes in gut microbiota and microbiota-derived metabolites in GVHD, their relationship to GVHD prognosis, and corresponding clinical strategies designed to prevent microbial dysregulation and facilitate treatment of GVHD.

Structural analysis of PTPN21 reveals a dominant-negative effect of the FERM domain on its phosphatase activity.

PTPN21 belongs to the four-point-one, ezrin, radixin, moesin (FERM) domain-containing protein tyrosine phosphatases (PTP) and plays important roles in cytoskeleton-associated cellular processes like cell adhesion, motility, and cargo transport. Because of the presence of a WPE loop instead of a WPD loop in the phosphatase domain, it is often considered to lack phosphatase activity. However, many of PTPN21's biological functions require its catalytic activity. To reconcile these findings, we have determined the structures of individual PTPN21 FERM, PTP domains, and a complex between FERM-PTP. Combined with biochemical analysis, we have found that PTPN21 PTP is weakly active and is autoinhibited by association with its FERM domain. Disruption of FERM-PTP interaction results in enhanced ERK activation. The oncogenic HPV18 E7 protein binds to PTP at the same location as PTPN21 FERM, indicating that it may act by displacing the FERM domain from PTP. Our results provide mechanistic insight into PTPN21 and benefit functional studies of PTPN21-mediated processes.

C/EBPα-p30 confers AML cell susceptibility to the terminal unfolded protein response and resistance to Venetoclax by activating DDIT3 transcription.

BACKGROUND: Acute myeloid leukemia (AML) with biallelic (CEBPAbi) as well as single mutations located in the bZIP region is associated with a favorable prognosis, but the underlying mechanisms are still unclear. Here, we propose that two isoforms of C/EBPα regulate DNA damage-inducible transcript 3 (DDIT3) transcription in AML cells corporately, leading to altered susceptibility to endoplasmic reticulum (ER) stress and related drugs. METHODS: Human AML cell lines and murine myeloid precursor cell line 32Dcl3 cells were infected with recombinant lentiviruses to knock down CEBPA expression or over-express the two isoforms of C/EBPα. Quantitative real-time PCR and western immunoblotting were employed to determine gene expression levels. Cell apoptosis rates were assessed by flow cytometry. CFU assays were utilized to evaluate the differentiation potential of 32Dcl3 cells. Luciferase reporter analysis, ChIP-seq and ChIP-qPCR were used to validate the transcriptional regulatory ability and affinity of each C/EBPα isoform to specific sites at DDIT3 promoter. Finally, an AML xenograft model was generated to evaluate the in vivo therapeutic effect of agents. RESULTS: We found a negative correlation between CEBPA expression and DDIT3 levels in AML cells. After knockdown of CEBPA, DDIT3 expression was upregulated, resulting in increased apoptotic rate of AML cells induced by ER stress. Cebpa knockdown in mouse 32Dcl3 cells also led to impaired cell viability due to upregulation of Ddit3, thereby preventing leukemogenesis since their differentiation was blocked. Then we discovered that the two isoforms of C/EBPα regulate DDIT3 transcription in the opposite way. C/EBPα-p30 upregulated DDIT3 transcription when C/EBPα-p42 downregulated it instead. Both isoforms directly bound to the promoter region of DDIT3. However, C/EBPα-p30 has a unique binding site with stronger affinity than C/EBPα-p42. These findings indicated that balance of two isoforms of C/EBPα maintains protein homeostasis and surveil leukemia, and at least partially explained why AML cells with disrupted C/EBPα-p42 and/or overexpressed C/EBPα-p30 exhibit better response to chemotherapy stress. Additionally, we found that a low C/EBPα p42/p30 ratio induces resistance in AML cells to the BCL2 inhibitor venetoclax since BCL2 is a major target of DDIT3. This resistance can be overcome by combining ER stress inducers, such as tunicamycin and sorafenib in vitro and in vivo. CONCLUSION: Our results indicate that AML patients with a low C/EBPα p42/p30 ratio (e.g., CEBPAbi) may not benefit from monotherapy with BCL2 inhibitors. However, this issue can be resolved by combining ER stress inducers.