Human B-cell Research Articles

N-Glycosylation Site Analysis

The components driving to the improvement of human B-cell interceded autoimmunity are not completely caught on. In specific, it is hazy how auto reactive B cells emerge and elude resilience checkpoints that ordinarily control their improvement and extension. Whereas temporal, short-lived autoreactive B-cell reactions are regularly watched within the setting of outside, natural triggers such as contaminations, the advancement of long-lived, auto reactive B and plasma cells within the setting of immune system infection likely requires T-cell offer assistance and the inclusion of germinal centers (GCs) in lymph hubs or GC-like structures in aroused tissues. As these specialized structures are prepared with different control components to anticipate the advancement of auto reactivity , it is critical to understand why and how these defensive components come up short within the improvement of human autoimmunity.

Fc receptor-like 4 and 5 define human atypical memory B cells.

Atypical memory B cells accumulate in chronic infections and autoimmune conditions, and commonly express FCRL4 and FCRL5, respective IgA and IgG receptors. We characterized memory cells from tonsils on the basis of both FCRL4 and FCRL5 expression, defining three subsets with distinct surface proteins and gene expression. Atypical FCRL4+FCRL5+ memory cells had the most discrete surface protein expression and were enriched in cell adhesion pathways, consistent with functioning as tissue-resident cells. Atypical FCRL4-FCRL5+ memory cells expressed transcription factors and immunoglobulin genes that suggest poised differentiation into plasma cells. Accordingly, the FCRL4-FCRL5+ memory subset was enriched in pathways responding to endoplasmic reticulum stress and IFN-γ. We reconstructed ongoing B-cell responses as lineage trees, providing crucial in vivo developmental context. Each memory subset typically maintained its lineage, denoting mechanisms enforcing their phenotypes. Classical FCRL4-FCRL5- memory cells were infrequently detected in lineage trees, suggesting the majority were in a quiescent state. FCRL4-FCRL5+ cells were the most represented memory subset in lineage trees, indicating robust participation in ongoing responses. Together, these differences suggest FCRL4 and FCRL5 are unlikely to be passive markers but rather active drivers of human memory B-cell development and function.

Abstract 5356: Targeted in vivo delivery of NF-κB decoy oligodeoxynucleotide augments efficacy of radiation therapy against B-cell lymphomas

Abstract Despite recent advances in the treatment of non-Hodgkin B-cell lymphoma (BCL), significant numbers of patients relapse or remain refractory to current therapies. Treatment resistance in BCL is associated with survival signaling via NF-κB transcription factor. While NF-κB is an attractive molecular target in BCL and many other human cancers, as a transcription factor it remains undruggable. Here, we describe a B-cell-selective NF-κB inhibitor consisting of a NF-κB-specific decoy oligodeoxynucleotide (dODN) conjugated to a type B CpG ODN sequence targeting Toll-like receptor-9 (TLR9)-expressing B-cell lymphoma cells. Bc-NFκBdODN showed efficient uptake by human diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL), such as U2932, OCI-Ly3 and Jeko1, respectively. In addition, we confirmed that Bc-NFκBdODN inhibited nuclear translocation and DNA-binding activity of NF-κB together with the expression of CCND2 and MYC target genes. In vitro Bc-NFκBdODN enhanced direct and ionizing radiation-induced cytotoxicity in lymphoma cells. In xenotransplanted models of human U2932 and Ly3 lymphomas, local injections of Bc-NFκBdODN reduced NF-κB activity in whole tumors and effectively arrested lymphoma progression when combined with a single, local 3Gy or 10Gy dose of radiation. In immune-competent mice, intratumoral treatment with Bc-NFκBdODN abrogated growth of directly treated as well as distant A20 lymphomas and triggered CD8+ T cell-mediated anti-tumor immune responses. Bc-NFκBdODN but not control Bc-scrambled oligonucleotides downregulated PD-1 expression on CD8+ and CD4+ T cells, while reducing Treg percentage in tumor draining lymph nodes (TDLN). Bc-NFκBdODN treatment also downregulated PD-L1 on tumor-associated myeloid cells and reduced percentage of tumor-infiltrating M-MDSCs. Our results underscore clinical relevance of NF-κB-specific decoy strategy, which can restore efficacy of standard radiation therapy to benefit patients with resistant or relapsed BCL. Citation Format: Zhuoran zhang, Xingli Zhao, Dayson Moreira, Yu-Lin Su, Piotr Swiderski, Stephen Forman, Larry Kwak, Marcin Kortylewski. Targeted in vivo delivery of NF-κB decoy oligodeoxynucleotide augments efficacy of radiation therapy against B-cell lymphomas [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5356.

Abstract 4178: ETH-155008, a dual inhibitor of CDK and Pim in preclinical treatment of human B-cell lymphoma xenografts

Abstract Non-Hodgkin lymphomas (NHLs) are the most common hematologic malignancies. The treatment of lymphoma presents a challenge in clinical oncology. Despite significant therapeutic efficacy achieved with combination of chemotherapy and new targeted agents, a large number of patients eventually relapse. Cyclin-dependent kinases (CDKs) are therapeutic targets frequently deregulated in various cancers including solid tumors and hematopoietic malignances. It was also reported that Moloney murine leukemia virus (PIM) kinases are overexpressed in several hematopoietic and solid tumors, especially in B-cell lymphomas. We evaluated the inhibition of kinases' activities and cell proliferation in vitro, and antitumor activities in vivo of ETH-155008, a dual inhibitor of CDK4/6 and PIM in preclinical treatment of human B-cell lymphoma xenografts. ETH-155008 was found to have strong inhibitory activities against key target enzymes with IC50s for CDK4/D1 at 0.8nM, CDK6/D1 at 1.4nM, PIM-1 at 13.3 nM, and PIM-3 at 0.9 nM. ETH-155008 showed to have highly potent antiproliferative activities against cultured human B-cell lymphoma cells of WSU-DLCL2 (diffuse large B-cell lymphoma) and JeKo-1 (mantle cell lymphoma) with IC50s at 1.7nM and 20 nM, respectively. The in vivo antitumor activities of ETH-155008 were evaluated and compared with abemaciclib (CDK4/6 inhibitor) and Imbruvica (Bruton tyrosine kinase inhibitor) in the treatment of the two lymphoma models, respectively. Treatment with ETH-155008 (40 mg/kg/daily x 14-21 days) almost completely eradicated the tumor xenografts and some of the tumor-bearing mice were cured; while as control drugs abemaciclib produced a tumor growth inhibition (TGI) of 56-60% and ibrutinib with a TGI of 60-67% in the two xenograft models. ETH-155008 treatment showed very little toxicity (only 2-4% body weight loss) which were well below the maximum tolerated dose. ETH-155008 represents a novel dual inhibitor that may yet fulfill the promise of effective B-cell lymphoma therapy through dual targeting of CDK4/6 and PIM3. These preclinical results supported the safety and efficacy observed in the preclinical studies and worthy of further clinical evaluation. Citation Format: Changnian Liu, Zuopeng Sun, Chunping Xu, Pan Zhang, Bin Ji, James Zhang, Laura Liu, Chengzhi Yu. ETH-155008, a dual inhibitor of CDK and Pim in preclinical treatment of human B-cell lymphoma xenografts [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4178.

Abstract 4436: Combination therapy with an antibody specific for transferrin receptor 1 (ch128.1/IgG1) and bortezomib or lenalidomide results in increased survival in an in vivo model of human multiple myeloma

Abstract Multiple myeloma (MM) is a B-cell proliferative disorder of monoclonal malignant plasma cells. It is the second most common hematologic malignancy in the United States, after non-Hodgkin lymphoma (NHL). Clinical manifestations of MM include osteolytic bone lesions, hypercalcemia, renal failure, anemia, recurrent infections, and neuropathy. Standard treatments for MM include the proteasome inhibitor bortezomib, as well as lenalidomide, a thalidomide analog with immunomodulatory and antiangiogenic properties. Although the use of these two agents in combination with other therapies have significantly improved MM survival, the disease remains incurable. We previously developed a mouse/human chimeric antibody (ch128.1/IgG1) specific for human transferrin receptor 1 (TfR1). TfR1, also known as CD71, is a meaningful target for antibody-based cancer therapy, given its high expression on malignant cells and relevant role in cancer cell pathology. We have reported that treatment of SCID-Beige mice bearing disseminated human KMS-11, MM.1S, or MM.1R myeloma tumors with ch128.1/IgG1 results in significant antitumor activity in early and late disease stages. The mechanism of antitumor activity is Fc-mediated in which macrophages are considered to play a relevant role. Since combining multiple treatments with differing mechanisms of action is an effective antitumor strategy, and given the relevance of bortezomib and lenalidomide in MM therapy, we decided to explore, for the first time, the combination of these two agents with ch128.1/IgG1. We found that treatment with a single dose of ch128.1/IgG1, or multiple doses of bortezomib or lenalidomide used as single agents, results in significant antitumor activity in SCID-Beige mice bearing late stage disseminated human MM.1S tumors. However, this antitumor activity is superior when ch128.1/IgG1 was combined with bortezomib or lenalidomide, showing significantly longer survival compared to each therapy used alone. These results suggest that the addition of a ch128.1/IgG1 therapy arm in a combinatorial treatment regimen involving bortezomib and/or lenalidomide is a promising strategy against human B-cell malignancies such as MM. Citation Format: Pierre V. Candelaria, Miguel Nava, Otoniel Martinez-Maza, Tracy R. Daniels-Wells, Manuel L. Penichet. Combination therapy with an antibody specific for transferrin receptor 1 (ch128.1/IgG1) and bortezomib or lenalidomide results in increased survival in an in vivo model of human multiple myeloma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4436.

Abstract 4512: Mouse model for in vivo evaluation of efficacy and potential cytokine release syndrome of chimeric antigen receptor (CAR) T cell therapy

Abstract Chimeric antigen receptor (CAR) T-cell therapy holds great promise as cancer immunotherapy. While impressive responses have been achieved in patients with hematological malignancies there are challenges for CAR T therapy such as toxicity complications due to cytokine release syndrome (CRS) and limitations due to CAR T cell exhaustion. As increasing number of novel CAR T products are in the discovery and preclinical phase of development, preclinical models to assess efficacy as well as potential toxicity of CAR T in vivo are needed. Here, we describe a new NSG™ mice model to examine CAR T cells for efficacy and potential CRS. Immunodeficient NSG™ mice are commonly used to evaluate CAR T functions. However, human T cells can cause acute xeno-GVHD in NSG™ limiting the use of the model system. A system to study human T cell function in the absence of xeno-GVHD is required. A new NSG™ derivative NSG-MHC Class I/II knockout (KO) strain has MHC class I and MHC class II deficiency in addition to B, T and NK cell deficiency. NSG-MHC Class I/II KO mice are known to have a delayed onset of GVHD and can provide a useful background to study human immunity in the absence of GVHD [M. A. Brehm et al., FASEB J. 33, 3137–3151 (2019)]. Human B-cell lymphoma Raji tumor cells express high levels of CD19 and CD22 which are targets for CAR T therapy. Using NSG-MHC Class I/II KO mice and luciferase-tagged Raji-Luc tumor model we found that compared to controls CD22 CAR T and CD19 CAR T showed significant tumor growth inhibition by Xenogen imaging analysis. No body weight loss was observed with the CAR T treatments. As high tumor burdens are usually associated with the potential of causing CRS we examined CD19 CAR T cells on low and high tumor burdens and the data will be presented in context of efficacy. We have established a new mouse model using NSG-MHCI/II KO mice to enable evaluation of CAR T efficacy and propensity to induce cytokines simultaneously in vivo. Furthermore PBMC-humanized NSG-MHCI/II KO mice can also be established and used to examine CAR T cells prepared from the same PBMC donor to mimic autologous CAR T cell therapy. Citation Format: Jing Jiao, Chunting Ye, Danying Cai, Mingshan Cheng, James Keck. Mouse model for in vivo evaluation of efficacy and potential cytokine release syndrome of chimeric antigen receptor (CAR) T cell therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4512.

Vav family proteins constitute disparate branching points for distinct BCR signaling pathways.

Antigen recognition by B-cell antigen receptors (BCRs) activates distinct intracellular signaling pathways that control the differentiation fate of activated B lymphocytes. BCR-proximal signaling enzymes comprise protein tyrosine kinases, phosphatases, and plasma membrane lipid-modifying enzymes, whose function is furthermore coordinated by catalytically inert adaptor proteins. Here, we show that an additional class of enzymatic activity provided by guanine-nucleotide exchange factors (GEFs) of the Vav family controls BCR-proximal Ca2+ mobilization, cytoskeletal actin reorganization, and activation of the PI3 kinase/Akt pathway. Whereas Vav1 and Vav3 supported all of those signaling processes to different extents in a human B-cell model system, Vav2 facilitated Actin remodeling, and activation of Akt but did not promote Ca2+ signaling. On BCR activation, Vav1 was directly recruited to the phosphorylated BCR and to the central adaptor protein SLP65 via its Src homology 2 domain. Pharmacological inhibition or genetic inactivation of the substrates of Vav GEFs, small G proteins of the Rho/Rac family, impaired BCR-induced Ca2+ mobilization, probably because phospholipase Cγ2 requires activated Rac proteins for optimal activity. Our findings show that Vav family members are key relays of the BCR signalosome that differentially control distinct signaling pathways both in a catalysis-dependent and -independent manner.

Small-molecule active pharmaceutical ingredients of approved cancer therapeutics inhibit human aspartate/asparagine-β-hydroxylase

Human aspartate/asparagine-β-hydroxylase (AspH) is a 2-oxoglutarate (2OG) dependent oxygenase that catalyses the hydroxylation of Asp/Asn-residues of epidermal growth factor-like domains (EGFDs). AspH is reported to be upregulated on the cell surface of invasive cancer cells in a manner distinguishing healthy from cancer cells. We report studies on the effect of small-molecule active pharmaceutical ingredients (APIs) of human cancer therapeutics on the catalytic activity of AspH using a high-throughput mass spectrometry (MS)-based inhibition assay. Human B-cell lymphoma-2 (Bcl-2)-protein inhibitors, including the (R)-enantiomer of the natural product gossypol, were observed to efficiently inhibit AspH, as does the antitumor antibiotic bleomycin A2. The results may help in the design of AspH inhibitors with the potential of increased selectivity compared to the previously identified Fe(II)-chelating or 2OG-competitive inhibitors. With regard to the clinical use of bleomycin A2 and of the Bcl-2 inhibitor venetoclax, the results suggest that possible side-effects mediated through the inhibition of AspH and other 2OG oxygenases should be considered.

Inhibition of acid ceramidase regulates MHC class II antigen presentation and suppression of autoimmune arthritis

The bioactive sphingolipid ceramide affects immune responses although its effect on antigen (Ag) processing and delivery by HLA class II to CD4+T-cells remains unclear. Therefore, we examined the actions of a novel cell-permeable acid ceramidase (AC) inhibitor [(1R,2R) N myristoylamino-(4′-nitrophenyl)-propandiol-1,3] on antigen presentation and inflammatory cytokine production by Ag-presenting cells (APCs) such as B-cells, macrophages, and dendritic cells. We found that AC inhibition in APCs perturbed Ag-processing and presentation via HLA-DR4 (MHC class II) proteins as measured by coculture assay and T-cell production of IL-2. Mass spectral analyses showed that B13 treatment significantly raised levels of four types of ceramides in human B-cells. B13 treatment did not alter Ag internalization and class II protein expression, but significantly inhibited lysosomal cysteinyl cathepsins (B, S and L) and thiol-reductase (GILT), HLA class II Ag-processing, and generation of functional class II-peptide complexes. Ex vivo Ag presentation assays showed that inhibition of AC impaired primary and recall CD4+T-cell responses and cytokine production in response against type II collagen. Further, B13 delayed onset and reduced severity of inflamed joints and cytokine production in the collagen-induced arthritis mouse model in vivo. These findings suggest that inhibition of AC in APCs may dysregulate endolysosomal proteases and HLA class II-associated self-antigen presentation to CD4+T-cells, attenuating inflammatory cytokine production and suppressing host autoimmune responses.

Anti-CXCL4 Antibody Reactivity Is Present in Systemic Sclerosis (SSc) and Correlates with the SSc Type I Interferon Signature.

Systemic sclerosis (SSc) is characterized by skin/internal organ fibrosis, vasculopathy and autoimmunity. Chemokine (C-X-C motif) ligand 4 (CXCL4) is an SSc biomarker, predicting unfavorable prognosis and lung fibrosis. CXCL4 binds DNA/RNA and favors interferon (IFN)-α production by plasmacytoid dendritic cells (pDCs), contributing to the type I IFN (IFN-I) signature in SSc patients. However, whether CXCL4 is an autoantigen in SSc is unknown. Here, we show that at least half of SSc patients show consistent antibody reactivity to CXCL4. T-cell proliferation to CXCL4, tested in a limited number of patients, correlates with anti-CXCL4 antibody reactivity. Antibodies to CXCL4 mostly correlate with circulating IFN-α levels and are significantly higher in patients with lung fibrosis in two independent SSc cohorts. Antibodies to CXCL4 implement the CXCL4–DNA complex’s effect on IFN-α production by pDCs; CXCL4–DNA/RNA complexes stimulate purified human B-cells to become antibody-secreting plasma cells in vitro. These data indicate that CXCL4 is indeed an autoantigen in SSc and suggest that CXCL4, and CXCL4-specific autoantibodies, can fuel a harmful loop: CXCL4–DNA/RNA complexes induce IFN-α in pDCs and direct B-cell stimulation, including the secretion of anti-CXCL4 antibodies. Anti-CXCL4 antibodies may further increase pDC stimulation and IFN-α release in vivo, creating a vicious cycle which sustains the SSc IFN-I signature and general inflammation.

A Humanized Lym-1 CAR with Novel DAP10/DAP12 Signaling Domains Demonstrates Reduced Tonic Signaling and Increased Antitumor Activity in B-Cell Lymphoma Models.

The murine Lym-1 mAb targets a discontinuous epitope (Lym-1 epitope) on several subtypes of HLA-DR, which is upregulated in a majority of human B-cell lymphomas and leukemias. Unlike CD19, the Lym-1 epitope does not downregulate upon crosslinking, which may provide an advantage as a target for CAR T-cell therapy. Lym-1 CAR T cells with a conventional 4-1BB and CD3ζ (BB3z) signaling domain exhibited impaired ex vivo expansion. This study aimed to identify the underlying mechanisms and develop strategies to overcome this effect. A functional humanized Lym-1 antibody (huLym-1-B) was identified and its scFv form was used for CAR design. To overcome observed impaired expansion in vitro, a huLym-1-B CAR using DAP10 and DAP12 (DAP) signaling domains was evaluated for ex vivo expansion and in vivo function. Impaired expansion in huLym-1-B-BB3z CAR T cells was shown to be due to ligand-dependent suboptimal CAR signaling caused by interaction of the CAR binding domain and the surface of human T cells. Using the novel DAP signaling domain construct, the effects of suboptimal CAR signaling were overcome to produce huLym-1-B CAR T cells with improved expansion ex vivo and function in vivo. In addition, the Lym-1 epitope does not significantly downregulate in response to huLym-1-B-DAP CAR T cells both ex vivo and in vivo. DAP intracellular domains can serve as signaling motifs for CAR, and this new construct enables nonimpaired production of huLym-1-B CAR T cells with potent in vivo antitumor efficacy.

B lymphocytes contribute to indirect pathway T cell sensitization via acquisition of extracellular vesicles.

B cells have been implicated in transplant rejection via antibody-mediated mechanisms and more recently by presenting donor antigens to T cells. We have shown in patients with chronic antibody-mediated rejection that B cells control the indirect T cell alloresponses. To understand more about the role of B cells as antigen-presenting cells for CD4+ T cell with indirect allospecificity, B cells were depleted in C57BL/6 mice, using an anti-CD20 antibody, prior to receiving MHC class I-mismatched (Kd ) skin. The absence of B cells at the time of transplantation prolonged skin graft survival. To study the mechanisms behind this observation, T cells with indirect allospecificity were transferred in mice receiving a Kd skin transplant. T cell proliferation was markedly inhibited in the absence of recipient B cells, suggesting that B cells contribute to indirect pathway sensitization. Furthermore, we have shown that a possible way in which B cells present alloantigens is via acquisition of MHC-peptide complexes. Finally, we demonstrate that the addition of B cell depletion to the transfer of regulatory T cells (Tregs) with indirect alloresponse further prolonged skin graft survival. This study supports an important role for B cells in indirect T cell priming and further emphasizes the advantage of combination therapies in prolonging transplant survival.

MiR-28-5p mediates the anti-proliferative and pro-apoptotic effects of curcumin on human diffuse large B-cell lymphoma cells.

ObjectiveTo investigate the anti-proliferative and pro-apoptotic effects of curcumin on diffuse large B-cell lymphoma (DLBCL) cells and explore the mechanism.MethodsOCI-LY7 cells were treated with curcumin (2.5, 5, 10, 20, and 40 μM) for 24, 48, or 72 hours. Cell viability and apoptosis were determined using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyl tetrazolium bromide assay and TdT-mediated dUTP nick-end labeling staining, respectively. MiR-28-5p expression was detected via qRT-PCR. The binding site of miR-28-5p was predicted using online databases and verified using the dual-luciferase reporter assay. MiR-28-5p overexpression and inhibition were achieved via transfection with an miR-28-5p mimic and inhibitor, respectively.ResultsCurcumin decreased the viability of OCI-LY7 cells in a concentration- and time-dependent manner, and these effects were attenuated by miR-28-5p inhibition. MiR-28-5p expression was upregulated by curcumin. Curcumin increased the numbers of apoptotic cells and upregulated cleaved caspase-3 expression, and these effects were attenuated by miR-28-5p inhibition. The dual-luciferase reporter assay confirmed that miR-28-5p directly targets the 3′-untranslated region of BECN1. Curcumin downregulated BECN1 and microtubule-associated protein 1 light chain 3 beta-II/I expression and upregulated p62 expression.ConclusionsOur results described the curcumin exerted anti-proliferative and pro-apoptotic effects on OCI-LY7 cells through a mechanism potentially involving miR-28-5p.

Pan- and Isoform-specific Inhibition of the Bromodomain and Extra-terminal Proteins and Evaluation of Synergistic Potential With Entospletinib in Canine Lymphoma.

Canine B-cell lymphoma represents a useful in vivo model for human diffuse large B-cell lymphoma (DLBCL). Pan-Bromodomain and extra-terminal (BET) inhibition targeting BRD2/3/4 and selective inhibition of BRD4, as well as spleen tyrosine kinase (SYK) inhibition, are currently evaluated as haematologic cancer therapy. Herein, we characterized the differences in the biologic response of isoform-specific or pan-BET inhibition alone or in combination with SYK inhibition. I-BET151 (pan-inhibitor) and AZD5153 (BRD4 inhibitor) were combined with Entospletinib (SYK inhibitor) and comparatively analysed in the canine DLBCL cell line CLBL-1. Dose- and time-dependent cellular responses were analysed by cell number, metabolic activity, apoptosis/necrosis, and cell morphology. The synergistic potential was evaluated through the Bliss independence model. I-BET151 and AZD5153 showed significant dose- and time-dependent inhibitory effects. Adding Entospletinib to I-BET151 or AZD5153 had no additional synergistic effects. Entospletinib did not enhance the inhibitory effects of the pan- or isoform-specific BET.

Constitutive Activation of RAS/MAPK Pathway Cooperates with Trisomy 21 and Is Therapeutically Exploitable in Down Syndrome B-cell Leukemia.

Children with Down syndrome (constitutive trisomy 21) that develop acute lymphoblastic leukemia (DS-ALL) have a 3-fold increased likelihood of treatment-related mortality coupled with a higher cumulative incidence of relapse, compared with other children with B-cell acute lymphoblastic leukemia (B-ALL). This highlights the lack of suitable treatment for Down syndrome children with B-ALL. To facilitate the translation of new therapeutic agents into clinical trials, we built the first preclinical cohort of patient-derived xenograft (PDX) models of DS-ALL, comprehensively characterized at the genetic and transcriptomic levels, and have proven its suitability for preclinical studies by assessing the efficacy of drug combination between the MEK inhibitor trametinib and conventional chemotherapy agents. Whole-exome and RNA-sequencing experiments revealed a high incidence of somatic alterations leading to RAS/MAPK pathway activation in our cohort of DS-ALL, as well as in other pediatric B-ALL presenting somatic gain of the chromosome 21 (B-ALL+21). In murine and human B-cell precursors, activated KRASG12D functionally cooperates with trisomy 21 to deregulate transcriptional networks that promote increased proliferation and self renewal, as well as B-cell differentiation blockade. Moreover, we revealed that inhibition of RAS/MAPK pathway activation using the MEK1/2 inhibitor trametinib decreased leukemia burden in several PDX models of B-ALL+21, and enhanced survival of DS-ALL PDX in combination with conventional chemotherapy agents such as vincristine. Altogether, using novel and suitable PDX models, this study indicates that RAS/MAPK pathway inhibition represents a promising strategy to improve the outcome of Down syndrome children with B-cell precursor leukemia.

Marginal zone lymphoma expression of histidine-rich glycoprotein correlates with improved survival.

PurposeThe abundant hepatocyte‐expressed plasma protein histidine‐rich glycoprotein (HRG) enhances antitumor immunity by polarizing inflammatory and immune cells in several mouse models, however, the clinical relevance of HRG in human cancer is poorly explored. The expression and role of HRG in human B‐cell lymphomas was investigated in order to find new tools for prognosis and treatment.FindingsImmunohistochemical (IHC) analysis and RNA hybridization of tissue microarrays showed that (i) HRG was expressed by tumor cells in marginal zone lymphoma (MZL), in 36% of 59 cases. Expression was also detected in follicular lymphoma (22%), mantle cell lymphoma (19%), and indiffuse large B‐cell lymphoma (DLBCL;5%) while primary CNS lymphoma (PCNSL) lacked expression of HRG. (ii) MZL patients positive for HRG showed a superior overall survival outcome (HR = 0.086, 95% CI = 0.014‐0.518, P‐value = .007), indicating a protective role for HRG independent of stage, age and sex. (iii) HRG‐expressing MZL displayed significantly increased transcript and protein levels of the host defense peptide alpha defensin 1. In addition, global transcript analyses showed significant changes in gene ontology terms relating to immunity and inflammation, however, infiltration of immune and inflammatory cells detected by IHC was unaffected by HRG expression.ConclusionHRG expression by MZL tumor cells correlates with an altered transcription profile and improved overall survival.

Local reinfusion of B10 cells is effective in the treatment of pustular psoriasis.

Psoriasis is a common chronic skin disease characterized by epidermal proliferation and inflammation. Pustular psoriasis (PP) is one of the most serious and refractory. The number, differentiation, and function of B10 cells in patients with PP were analyzed, and the relationship between B10 cells and PP, an autoimmune disease, was explored. We established an Imiquimod psoriasis mouse model and subcutaneously injected B10 cells as treatment. We found that the proportion of B10 cells in the peripheral blood of patients with PP was lower than that of the normal controls. However, the number of B10 precursor cells increased. B10 cells in the peripheral blood may be mobilized to effector sites, such as the skin. In patients with PP, B10 cells do not display evident developmental disorders under the CD40 and TLR9 pathways. Normal human B10 cells were found to inhibit the secretion of IFN-γ and TNF-α by lymphocytes significantly. Whereas the function of B10 cells in patients with PP is impaired, and the inhibition is not apparent. Treatment with a B10 cells injection displays a certain therapeutic effect on PP. This study enriched the etiology and pathogenesis of PP. It provides a foundation for cell therapy for the treatment of autoimmune diseases.

EBNA2-deleted Epstein-Barr virus (EBV) isolate, P3HR1, causes Hodgkin-like lymphomas and diffuse large B cell lymphomas with type II and Wp-restricted latency types in humanized mice.

EBV transforms B cells in vitro and causes human B-cell lymphomas including classical Hodgkin lymphoma (CHL), Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL). The EBV latency protein, EBNA2, transcriptionally activates the promoters of all latent viral protein-coding genes expressed in type III EBV latency and is essential for EBV’s ability to transform B cells in vitro. However, EBNA2 is not expressed in EBV-infected CHLs and BLs in humans. EBV-positive CHLs have type II latency and are largely driven by the EBV LMP1/LMP2A proteins, while EBV-positive BLs, which usually have type I latency are largely driven by c-Myc translocations, and only express the EBNA1 protein and viral non-coding RNAs. Approximately 15% of human BLs contain naturally occurring EBNA2-deleted viruses that support a form of viral latency known as Wp-restricted (expressing the EBNA-LP, EBNA3A/3B/3C, EBNA1 and BHRF1 proteins), but whether Wp-restricted latency and/or EBNA2-deleted EBV can induce lymphomas in humanized mice, or in the absence of c-Myc translocations, is unknown. Here we show that a naturally occurring EBNA2-deleted EBV strain (P3HR1) isolated from a human BL induces EBV-positive B-cell lymphomas in a subset of infected cord blood-humanized (CBH) mice. Furthermore, we find that P3HR1-infected lymphoma cells support two different viral latency types and phenotypes that are mutually exclusive: 1) Large (often multinucleated), CD30-positive, CD45-negative cells reminiscent of the Reed-Sternberg (RS) cells in CHL that express high levels of LMP1 but not EBNA-LP (consistent with type II viral latency); and 2) smaller monomorphic CD30-negative DLBCL-like cells that express EBNA-LP and EBNA3A but not LMP1 (consistent with Wp-restricted latency). These results reveal that EBNA2 is not absolutely required for EBV to form tumors in CBH mice and suggest that P3HR1 virus can be used to model EBV positive lymphomas with both Wp-restricted and type II latency in vivo.

Optimization of canine CD20 chimeric antigen receptor T cell manufacturing and in vitro cytotoxic activity against B-cell lymphoma.

Canine B-cell lymphoma is one of the most common haematopoietic neoplasms in veterinary medicine, and it is considered a relevant model for human diffuse large B-cell lymphoma. Although the standard treatment consisting of multi-drug chemotherapy is effective in most cases, treatment is often challenging because of relapse and drug resistance. The adoptive transfer of autologous T cells genetically modified to express a CD19-specific chimeric antigen receptor (CD19 CAR-T cells) has been shown to be highly effective in human B-cell malignancies. However, there is no clinically available canine CAR-T cell therapy. We generated canine second-generation and third-generation CAR-T cells by retroviral gene transduction. Optimization was performed to investigate effective viral transduction protocols and favourable culture conditions for canine CAR-T cells. The RetroNectin-bound virus infection method resulted in more than 70% transduction efficiency. The effect of culture conditions on the phenotype of CAR-T cells was evaluated by the expression of surface markers. in vitro cytotoxicity assays of target cells cultured with CD20 CAR-transduced cells demonstrated that CD20 CAR-T cells exhibit cytotoxicity against CD20-expressing canine B-cell lymphoma cells and canine CD20-transduced murine cells, whereas no effect was observed against cells that lacked canine CD20 expression. Our study established virus-based canine CAR-T cell generation, providing fundamental data for a better understanding of canine adoptive T-cell therapy.

Bptf determines oncogenic addiction in aggressive B-cell lymphomas.

Chromatin remodeling factors contribute to establish aberrant gene expression programs in cancer cells and therefore represent valuable targets for therapeutic intervention. BPTF (Bromodomain PhD Transcription Factor), a core subunit of the nucleosome remodeling factor (NURF), modulates c-MYC oncogenic activity in pancreatic cancer. Here, we analyze the role of BPTF in c-MYC-driven B-cell lymphomagenesis using the Eμ-Myc transgenic mouse model of aggressive B-cell lymphoma. We find that BPTF is required for normal B-cell differentiation without evidence of haploinsufficiency. In contrast, deletion of one Bptf allele is sufficient to delay lymphomagenesis in Eμ-Myc mice. Tumors arising in a Bptf heterozygous background display decreased c-MYC levels and pathway activity, together with increased activation of the NF-κB pathway, a molecular signature characteristic of human diffuse large B-cell lymphoma (DLBCL). In human B-cell lymphoma samples, we find a strong correlation between BPTF and c-MYC mRNA and protein levels, together with an anti-correlation between BPTF and NF-κB pathway activity. Our results indicate that BPTF is a relevant therapeutic target in B-cell lymphomas and that, upon its inhibition, cells acquire distinct oncogenic dependencies.