Blockade of trans PD-L1 interaction with CD80 augments antitumor immunity.

PD-L1 has two receptors: PD-1 and CD80. Previous reports assumed that PD-L1 and CD80 interacted in trans, but recent reports showed that only cis PD-L1/CD80 interactions existed, and prevention of cis PD-L1/CD80 interactions on antigen-presenting cells (APCs) reduced antitumor immunity via augmenting PD-L1/PD-1 and CD80/CTLA4 interactions between T and APCs. Here, using tumor-bearing mice capable of cis and trans or trans only PD-L1/CD80 interactions, we show that trans PD-L1/CD80 interactions do exist between tumor and T cells, and the effects of trans PD-L1/CD80 interactions require tumor cell expression of MHC-I and T cell expression of CD28. The blockade of PD-L1/CD80 interactions in mice with both cis and trans interactions or with only trans interactions augments antitumor immunity by expanding IFN-γ-producing CD8+ T cells and IFN-γ-dependent NOS2-expressing tumor-associated macrophages. Our studies indicate that although cis and trans PD-L1/CD80 interactions may have opposite effects on antitumor immunity, the net effect of blocking PD-L1/CD80 interactions in vivo augments CD8+ T cell-mediated antitumor immunity.

Trafficking between clonally related peripheral T-helper cells and tissue-resident T-helper cells in chronic GVHD.

Chronic graft-versus-host disease (cGVHD) is an autoimmune-like syndrome. CXCR5-PD-1hi peripheral T-helper (Tph) cells have an important pathogenic role in autoimmune diseases, but the role of Tph cells in cGVHD remains unknown. We show that in patients with cGVHD, expansion of Tph cells among blood CD4+ T cells was associated with cGVHD severity. These cells augmented memory B-cell differentiation and production of immunoglobulin G via interleukin 21 (IL-21). Tph cell expansion was also observed in a murine model of cGVHD. This Tph cell expansion in the blood is associated with the expansion of pathogenic tissue-resident T-helper (Trh) cells that form lymphoid aggregates surrounded by collagen in graft-versus-host disease (GVHD) target tissues. Adoptive transfer experiments showed that Trh cells from GVHD target tissues give rise to Tph cells in the blood, and conversely, Tph cells from the blood give rise to Trh cells in GVHD target tissues. Tph cells in the blood and Trh cells in GVHD target tissues had highly overlapping T-cell receptor α and ß repertoires. Deficiency of IL-21R, B-cell lymphoma 6 (BCL6), or T-bet in donor T cells markedly reduced the proportions of Tph cells in the blood and Trh cells in GVHD target tissues and reduced T-B interaction in the lymphoid aggregates. These results indicate that clonally related pathogenic Tph cells and Trh cells traffic between the blood and cGVHD target tissues, and that IL-21R-BCL6 signaling and T-bet are required for the development and expansion of Tph and Trh cells in the pathogenesis of cGVHD.

Donor programmed cell death 1 ligand 1 is required for organ transplant tolerance in major histocompatibility complex-mismatched mixed chimeras although programmed cell death 1 ligand 1 and major histocompatibility complex class II are not required for inducing chimerism.

Induction of major histocompatibility complex (MHC) human leukocyte antigen (HLA)-mismatched mixed chimerism is a promising approach for organ transplantation tolerance; however, human leukocyte antigen-mismatched stable mixed chimerism has not been achieved in the clinic. Tolerogenic dendritic cell (DC) expression of MHC class II (MHC II) and programmed cell death 1 ligand 1 (PD-L1) is important for immune tolerance, but whether donor-MHC II or PD-L1 is required for the induction of stable MHC-mismatched mixed chimerism and transplant tolerance is unclear. Here, we show that a clinically applicable radiation-free regimen can establish stable MHC-mismatched mixed chimerism and organ transplant tolerance in murine models. Induction of MHC-mismatched mixed chimerism does not require donor cell expression of MHC II or PD-L1, but donor-type organ transplant tolerance in the mixed chimeras (MC) requires the donor hematopoietic cells and the organ transplants to express PD-L1. The PD-L1 expressed by donor hematopoietic cells and the programmed cell death 1 expressed by host cells augment host-type donor-reactive CD4+ and CD8+ T cell anergy/exhaustion and differentiation into peripheral regulatory T (pTreg) cells in association with the organ transplant tolerance in the MC. Conversely, host-type Treg cells augment the expansion of donor-type tolerogenic CD8+ DCs that express PD-L1. These results indicate that PD-L1 expressed by donor-type tolerogenic DCs and expansion of host-type pTreg cells in MHC-mismatched MCs play critical roles in mediating organ transplant tolerance.

Study on the COVID-19 infection status, prevention and control strategies among people entering Shenzhen.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) confirmed cases overseas have continued to rise in the last months, and many people overseas have chosen to return to China. This increases the risk of a large number of imported cases which may cause a relapse of the COVID-19 outbreak. In order to prevent imported infection, the Shenzhen government has implemented a closed-loop management strategy using nucleic acid testing (NAT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and requiring 14 days of medical observation for individuals with an overseas tour history (Hong Kong, Macao, Taiwan province and other countries). Our study aims to describe the status of COVID-19 infection among people entering Shenzhen, and to evaluate the effect of the closed-loop management strategy. METHODS: We undertook a descriptive study and risk analysis by the entry time, time of reporting, and local confirmed cases in countries of origin. The NAT were completed in Shenzhen Center for Disease Control and Prevention (CDC), ten district-level CDCs, and fever clinics. RESULTS: A total of 86,844 people from overseas entered Shenzhen from January 1 to April 18, 2020; there were 39 imported COVID cases and 293 close contacts. The infection rate of people entering was 4.49‰ [95% Confidence interval (CI): 3.26‰-6.05‰]. Fourteen imported cases (35.9%) came from the UK, and nine (23.08%) came from the USA. People entering from the USA since March 9 or from the UK since March 13 are the high-risk population. As of July 17, there have been no new confirmed cases in Shenzhen for 153 days, and the numbers of confirmed case, close contacts, and asymptomatic cases are 0. CONCLUSIONS: The closed-loop management has been effective in preventing imported infection and controlling domestic relapse. The distribution of entry time and report time for imported cases overseas was similar. This shows that it is important to implement closed-loop management at the port of entry.

Donor T cell STAT3 deficiency enables tissue PD-L1-dependent prevention of graft-versus-host disease while preserving graft-versus-leukemia activity.

STAT3 deficiency (STAT3-/-) in donor T cells prevents graft-versus-host disease (GVHD), but the impact on graft-versus-leukemia (GVL) activity and mechanisms of GVHD prevention remains unclear. Here, using murine models of GVHD, we show that STAT3-/- donor T cells induced only mild reversible acute GVHD while preserving GVL effects against nonsusceptible acute lymphoblastic leukemia (ALL) cells in a donor T cell dose-dependent manner. GVHD prevention depended on programmed death ligand 1/programmed cell death protein 1 (PD-L1/PD-1) signaling. In GVHD target tissues, STAT3 deficiency amplified PD-L1/PD-1 inhibition of glutathione (GSH)/Myc pathways that regulate metabolic reprogramming in activated T cells, with decreased glycolytic and mitochondrial ATP production and increased mitochondrial ROS production and dysfunction, leading to tissue-specific deletion of host-reactive T cells and prevention of GVHD. Mitochondrial STAT3 deficiency alone did not reduce GSH expression or prevent GVHD. In lymphoid tissues, the lack of host-tissue PD-L1 interaction with PD-1 reduced the inhibition of the GSH/Myc pathway despite reduced GSH production caused by STAT3 deficiency and allowed donor T cell functions that mediate GVL activity. Therefore, STAT3 deficiency in donor T cells augments PD-1 signaling-mediated inhibition of GSH/Myc pathways and augments dysfunction of T cells in GVHD target tissues while sparing T cells in lymphoid tissues, leading to prevention of GVHD while preserving GVL effects.

Tissue-resident PSGL1loCD4+ T cells promote B cell differentiation and chronic graft-versus-host disease-associated autoimmunity.

CD4+ T cell interactions with B cells play a critical role in the pathogenesis of systemic autoimmune diseases such as systemic lupus and chronic graft-versus-host disease (cGVHD). Extrafollicular CD44hiCD62LloPSGL1loCD4+ T cells (PSGL1loCD4+ T cells) are associated with the pathogenesis of lupus and cGVHD, but their causal role has not been established. With murine and humanized MHC-/-HLA-A2+DR4+ murine models of cGVHD, we showed that murine and human PSGL1loCD4+ T cells from GVHD target tissues have features of B cell helpers with upregulated expression of programmed cell death protein 1 (PD1) and inducible T cell costimulator (ICOS) and production of IL-21. They reside in nonlymphoid tissues without circulating in the blood and have features of tissue-resident memory T cells with upregulated expression of CD69. Murine PSGL1loCD4+ T cells from GVHD target tissues augmented B cell differentiation into plasma cells and production of autoantibodies via their PD1 interaction with PD-L2 on B cells. Human PSGL1loCD4+ T cells were apposed with memory B cells in the liver tissues of humanized mice and cGVHD patients. Human PSGL1loCD4+ T cells from humanized GVHD target tissues also augmented autologous memory B cell differentiation into plasma cells and antibody production in a PD1/PD-L2-dependent manner. Further preclinical studies targeting tissue-resident T cells to treat antibody-mediated features of autoimmune diseases are warranted.

The use of clozapine is protective for low bone mineral density induced by prolactin-raising antipsychotics in inpatients with schizophrenia.

Low bone mineral density (BMD) is common among patients with schizophrenia; however, the pathogenesis is still unclear. Different types of antipsychotics may have different effects on BMD in inpatients with schizophrenia. INTRODUCTION: This retrospective study aimed to evaluate the effects of prolactin-raising (PR) antipsychotics vs. clozapine combined with PR antipsychotics on BMD of patients with schizophrenia and analyzed clinically related factors that may affect BMD. METHODS: A total of 125 participants (males/females = 62/63) were included. Patients were treated with PR antipsychotics vs. clozapine combined with PR antipsychotics. They were similar in demographic and clinical characteristics. BMD was examined in their lumbar spine and proximal femur by a dual-energy X-ray (DEXA) absorption measurement device. Laboratory variables (including blood levels of prolactin, estradiol, testosterone, and cortisol) were collected. RESULTS: Among 125 inpatients with schizophrenia, the prevalence of osteoporosis and low BMD (including osteoporosis and osteopenia) was 26.4% and 64%. The average BMD T value in patients receiving clozapine combined with PR antipsychotics was significantly higher than in patients receiving PR antipsychotics (p < 0.05). Patients in the clozapine combined with PR antipsychotic group had higher testosterone levels than the PR antipsychotic group (Z = - 2.77, p = 0.006). Linear logistic regression analysis indicated that clozapine combined with PR antipsychotic treatment (p < 0.05) and higher estradiol level (p < 0.05) may be significantly associated with higher BMD. CONCLUSIONS: Our results suggest that the use of clozapine may be a protective factor for low BMD induced by PR antipsychotics in inpatients with schizophrenia. The possible mechanism is that clozapine may protect BMD by regulating estrogen and testosterone levels, but the mechanism by which clozapine regulates these two sex hormones needs further investigation.

Acute myeloid leukemia in an 86-year-old man with AML1/ETO treated with Homoharringtonine and Arsenic Trioxide: A case report.

RATIONALE: Acute myeloid leukemia (AML) is a malignantly clonal and highly heterogeneous disease. Although the treatment of AML has brought promising outcomes for younger patients, prognosis of the elderly remains dismal. Innovative regimens are increasingly necessary to be investigated. PATIENT CONCERNS: We present an 86-year-old AML patient with fever, cough, and sputum production. DIAGNOSES: A diagnosis of AML with maturation (AML-M2) and AML1/ETO was made. INTERVENTIONS: The patient was treated with a regimen of Homoharringtonine coupled with arsenic trioxide. OUTCOMES: The AML-M2 patient with AML1/ETO achieved incomplete remission, but showed few toxic side effects and improved survival. Besides, we analyzed the dynamic counts of complete blood cells during the treatment. The count of white blood cell had a positive correlation with the percentage of blast cells (r = 0.65), both of which had a negative correlation with the percentage of segmented neutrophils (r = -0.63, -0.89). LESSONS: Homoharringtonine and arsenic trioxide may induce both the apoptosis and differentiation of leukemic cells in AML-M2 with AML1/ETO.

MLL-PTD in a 13-year-old patient with blast phase myeloproliferative neoplasm: A case report.

RATIONALE: The risk of leukemic transformation in myeloproliferative neoplasm (MPN) has been increasing with time. Partial Tandem Duplications of the MLL gene (MLL-PTD) has been reported in de novo acute myeloid leukemia (AML), but not in MPN blast phase. The post-MPN AML developed adverse clinical outcomes, which showed no noticeable improvement over the past 15 years. Therefore, the mechanisms and therapeutic approaches of post-MPN AML need to be deeply studied. PATIENT CONCERNS: In this study, we present a JAK2V617F positive MPN patient who experienced fatigue and splenomegaly, transforming into JAK2V617F negative AML. DIAGNOSES: A diagnosis of acute monocytic leukemia was made in MPN blast phase. INTERVENTIONS: The patient received chemotherapy and allogeneic hematopoietic stem cell transplantation (Allo-SCT). OUTCOMES: The patient achieved complete remission twice, but relapsed twice. Relapse-free survival was only 3 months. She died about 24 months after her diagnosis. LESSONS: MLL-PTD occurs in the progression of JAK2V617F positive MPN into JAK2V617F negative AML, which may be a novel mechanism of MPN blast phase and helpful for post-MPN AML diagnosis. Allo-SCT may be a good choice for post-MPN AML with MLL-PTD. More therapeutic strategies need to be explored for a better prognosis in these patients.

Correction to: Pin1 inhibition exerts potent activity against acute myeloid leukemia through blocking multiple cancer-driving pathways.

The original article [1] contained minor typesetting errors affecting the following authors: Ziang Jeff Gao, Xiao Zhen Zhou, and Kun Ping Lu.

Pin1 inhibition exerts potent activity against acute myeloid leukemia through blocking multiple cancer-driving pathways.

BACKGROUND: The increasing genomic complexity of acute myeloid leukemia (AML), the most common form of acute leukemia, poses a major challenge to its therapy. To identify potent therapeutic targets with the ability to block multiple cancer-driving pathways is thus imperative. The unique peptidyl-prolyl cis-trans isomerase Pin1 has been reported to promote tumorigenesis through upregulation of numerous cancer-driving pathways. Although Pin1 is a key drug target for treating acute promyelocytic leukemia (APL) caused by a fusion oncogene, much less is known about the role of Pin1 in other heterogeneous leukemia. METHODS: The mRNA and protein levels of Pin1 were detected in samples from de novo leukemia patients and healthy controls using real-time quantitative RT-PCR (qRT-PCR) and western blot. The establishment of the lentiviral stable-expressed short hairpin RNA (shRNA) system and the tetracycline-inducible shRNA system for targeting Pin1 were used to analyze the biological function of Pin1 in AML cells. The expression of cancer-related Pin1 downstream oncoproteins in shPin1 (Pin1 knockdown) and Pin1 inhibitor all-trans retinoic acid (ATRA) treated leukemia cells were examined by western blot, followed by evaluating the effects of genetic and chemical inhibition of Pin1 in leukemia cells on transformed phenotype, including cell proliferation and colony formation ability, using trypan blue, cell counting assay, and colony formation assay in vitro, as well as the tumorigenesis ability using in vivo xenograft mouse models. RESULTS: First, we found that the expression of Pin1 mRNA and protein was significantly increased in both de novo leukemia clinical samples and multiple leukemia cell lines, compared with healthy controls. Furthermore, genetic or chemical inhibition of Pin1 in human multiple leukemia cell lines potently inhibited multiple Pin1 substrate oncoproteins and effectively suppressed leukemia cell proliferation and colony formation ability in cell culture models in vitro. Moreover, tetracycline-inducible Pin1 knockdown and slow-releasing ATRA potently inhibited tumorigenicity of U937 and HL-60 leukemia cells in xenograft mouse models. CONCLUSIONS: We demonstrate that Pin1 is highly overexpressed in human AML and is a promising therapeutic target to block multiple cancer-driving pathways in AML.