ALBERT

Description: Introduction Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by abnormal immune response. Though many therapies have been used, corticosteroid-resistance remains to be a challenge clinically. Extensive research has improved our understanding of ITP, showing that environmental factors affect the disease profile, such as Helicobacter pylori being proven to be associated with thrombocytopenia. Though evidence that the gut microbiota contributes to the development of auto-immune disorders is accumulating, there is no information available on relationship between gut microbiome and ITP. Berberine(BBR), a traditional compound isolated from a Chinese herb, has been widely used as a nonprescription drug to treat diarrhea. Recently, BBR has been reported to modulate microbiota structures, which contributes to improving metabolic disorders. Here, we hypothesized that BBR might modulate gut microbiota to treat ITP. Methods In order to investigate the relationship between gut microbiome and ITP, we performed deep shotgun sequencing on 253 fecal samples totally from consecutive ITP patients and healthy controls. Metagenome-wide association study (MWAS) was conducted, and clinical characteristics of patients were collected to analyze the correlation with gut microbiome (Nan Qin, et al. Nature. 2012). Certainly, a clinical cohort study was performed to assess the efficacy of BBR in corticosteroid-resistant ITP patients. To better characterize the role of gut microbiota in the development of ITP and to verify the modulating effect of BBR on gut microbiota structure, we performed colonization of mice with specific bacterium and established active murine models (immunized-splenocyte engraftment) of BBR treatment. Result We integrated the sequencing data into an existing gut microbial reference-gene catalog and identified 35275 genes that differ in abundance between ITP patients and healthy controls. We then clustered the genes into metagenomic species (MGS) and finally identified 15 MGS which were significantly different in both discovery cohort and validation cohort. Dysbiosis was detected in the gut microbiome of ITP patients, as both phylogenetic analysis and MGS annotation indicated that Lachnospiraceae bacterium, Clostridium asparagiforme were over-represented while Bacteroides spp was depleted in ITP patients comparing with healthy controls. Functionally, KEGG annotation showed that the most enriched orthologs in ITP patients were related to membrane transport. Moreover, the biosynthesis of microbe-associated molecular patterns (MAMPs) such as lipopolysaccharides (LPS), peptidoglycan biosynthesis and flagellin were highly abundant in patients. Gene biomarkers and cluster markers based on gut microbiome were established to identify ITP patients and were validated in an independent cohort. The alterations of gut microbiome in ITP patients are partly reversed after treatment. Furthermore, L. bacterium shows more abundant in corticosteroid-resistant ITP comparing with newly diagnosed ITP. Specifically, BBR treatment could improve the microbial dysbiosis of corticosteroid-resistant ITP patients, the complete response (CR), response(R), and overall response (OR) rates being 26.3%, 47.4% and 73.7%, respectively. Targeted QPCR assay determined that L. bacterium accumulated in corticosteroid-resistant ITP, consistent with the result of shotgun sequencing data. Gavage with L. bacterium results in significantly alterations of gut microbiota structure in mice comparing with mice without bacterial administration or those receiving Clostridium asparagiforme administration. Moreover, colonization of L. bacterium caused more severe thrombocytopenia and impaired the response to corticosteroid therapy in active ITP model. Intriguingly, BBR treatment, but not any other antibiotics, could reverse the effect of L. bacterium colonization on gut microbiota structure and enhance the response to corticosteroid therapy. Conclusion Our findings demonstrate that the gut microbiome alters in ITP and is partly normalized after treatment. Gut microbiota dysbiosis may contribute to the development of corticosteroid-resistant ITP. BBR may correct corticosteroid-resistance by modulating the gut microbiota structure, thus being a novel potential second-line candidate to treat ITP. Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Graft-versus-host disease (GVHD) is a major complication of hematopoietic stem cell transplantation. Mesenchymal stem cells (MSCs) can modulate immune response and have been used as a treatment for aGVHD. The immune-modulating factors of MSCs are secreted and reside in supernatant fractions that are enriched for extracellular vesicles (EVs). MSC-derived EVs (MSC-EVs) also exhibit immunosuppressive activity, providing many advantages compared to MSCs and have been proven therapeutic in aGVHD. Arsenic trioxide (ATO) exhibits potent antitumor effects and increasing studies indicate its immunosuppressive effects. However, ATO at high concentrations can cause severe adverse effects. If encapsulated in some kind of drug vehicles, ATO can be made less toxic. Therefore, we believed that the combination of MSC-EVs with a low dose of ATO would be an effective therapy for aGVHD. Methods: We used a classical GVHD model (BALB/c→B6) and developed 4 groups: the control group (TCD-BM), the GVHD control group (TCD-BM + spleen T cells), the MSC-EVs treatment group and the MSC-ATO-EVs (MSC-derived ATO-encapsulating EVs) treatment group. OS, GVHD clinical and histological scores were evaluated. A20-luc lymphoma cells were injected to generate the GVL model. Using flow cytometry analysis, we analyzed Th cell subsets, cytokines and transcription factors (Th1*IFN-γ/TNF-α*T-bet, Th2*IL-4*GATA3, Th17*IL-17*RORγt, Treg*IL-10*Foxp3) and sorted CD8+ SLECs, and CD8+ MPECs in BM and spleen of recipients. Dll4 expression was analyzed on DCs. B6 cells were incubated with or without BALB/c spleen cells and complete medium alone, with 10 mM ATO alone. T cell apoptosis was determined with Yopro-1 staining. We used MLR assays to examine Th subsets, cytokines and notch targeted genes with or without ATO or neutralizing Ab specific to Dll4 (anti-Dll4). Results: BALB/c mice receiving B6 TCD-BM alone developed no sign of GVHD, whereas all BALB/c mice receiving B6 donor TCD-BM + spleen T cells died of GVHD. In contrast, injection of MSC-EVs and MSC-ATO-EVs inhibited GVHD in T cell recipients, with 20% and 29% of them surviving without severe GVHD, respectively. These survival rates were accompanied by significantly lower clinical and histological scores. GVL effects mediated by MSC-EVs and MSC-ATO-EVs were comparable to those obtained in the GVHD control group. Compared to the control group, CD4+T and CD8+T cells increased substantially in T cell recipients, resulting in severe GVHD. In contrast, treatment with MSC-ATO-EVs significantly reduced the number of CD4+T and CD8+T cells, while MSC-EVs recipients retained approximately the same number of T cells as the GVHD group. Compared to the GVHD control group, Th2 and Treg cells derived from the spleen increased, while Th1 and Th17 cells were reduced significantly in both the MSC-EVs and MSC-ATO-EVs groups. We also detected lower serum levels of TNF-α and IFNγ as well as lower expression of RORγt and T-bet in blood and BM CD4+ T cells in these two groups, while the expression of GATA3 and Foxp3 increased significantly. Treatment with MSC-ATO-EVs markedly raised the MPEC/SLEC ratio compared to the MSC-EVs and GVHD control groups. We also examined Dll4high DCs in different organs and different groups and found that only MSC-ATO-EVs significantly reduced the Dll4high DCs, especially in the spleen and intestine. Treatment of stimulated B6 CD4+ T and CD8+ T cells with ATO increased production of H2O2. Yopro-1 staining of activated B6 CD4+ T and CD8+ T cells indicated that ATO dramatically triggered apoptosis in those cells. DCs were isolated and cultured with B6 mouse-derived CD4+ T or CD8+ T cells, with or without addition of ATO or anti-Dll4. ATO and anti-Dll4 both led to significant reduction of IFN-γ and TNF-α, while IL-4 and IL-10 increased slightly. We next assessed the notch pathway targeted genes in T cells and found there were significantly increased GATA3 and reduced Dtx expression levels. Conclusion: Altogether, our findings demonstrate that MSC-ATO-EVs might be a highly promising therapy for aGVHD through reducing T cell amounts and modulating Th subsets and CD8+ T cell differentiation. These effects can be explained with the inhibition of the Dll4-notch pathway by ATO. Therefore, further exploitation of the potential application of ATO in aGVHD and the mechanisms of action of ATO may improve outcomes after allo-HSCT. Disclosures No relevant conflicts of interest to declare.

Description: Background:Educated NK cells prevent autoreactive behavior but also permit cytotoxicity against target cells that have down-regulated HLA class I expression. When and how the process of education occurs has not been clearly discerned. Several groups reported that both the donor and host MHC could influence NK cell education in mouse models. In humans, Dulphy et al demonstrated that NK-cell education is shaped by donor HLA genotype. Moreover, our previous study found NK-cell education was shaped by host HLA genotype post allo-HSCT. However, due to the lack of single-KIR+ NK cells, functional analysis limited the full evaluation of the interaction between donor/host HLA and donor inhibitory KIR, so the contribution of donor HLA could not be excluded. Aims: In this research, we have investigated the relative contributions of donor and recipient HLA to NK cells education, the interplay between functional reconstitution and the involvement of donor/host HLA interaction in NK cell control of leukemia cells. Methods: Two cohorts of patients were enrolled in this study. We first prospectively enrolled 114 patients undergoing haplo-SCT between May 2016 and April 2017 to explore NK cell phenotypes and functional reconstitution. From June 2012 to April 2016, 276 AML/MDS patients that underwent haploidentical transplantation were enrolled in the second cohort to analyze the effect of donor-host KIR-HLA combinations on relapse post transplantation. Molecular HLA typing and KIR genotyping were performed according to the manufacturer's instructions (One Lambda, Canoga Park, CA, USA). Peripheral blood mononuclear cells of each sample were analyzed by 15-colors flow cytometry. The cytotoxicity and cytokine secretion of NK cells was determined using CD107a expression and IFN-γ production against the K562 cell line. Single-KIR+ NK cells were grouped into the following groups: (A) nsKIR: where both hosts and donors lacked HLA ligands for one donor KIR; (B) d-rsKIR, where donors and hosts, encoded HLA ligands for donor KIRs; (C) dsKIR, where donors, but not hosts, encoded HLA ligands for donor KIR; and (D) rsKIR, where hosts, but not donors, encoded HLA ligands for donor KIR. Results: 1. Donor KIR ligated by both donor and host HLA is associated with better single-KIR+ NK cell education among the same patients. KIR2DL2/L3 single+ NK cell exhibited higher reactivity compared to KIR2DL1 single+ NK cell in pairs of donors C1C1 or C1C2 and host C1C1. KIR2DL2/L3 single+ NK cell exhibited higher reactivity than KIR3DL1 single+ NK cell in pairs of donors Bw4C1Cx and host C1Cx. KIR2DL1 single+ NK cell exhibited comparable reactivity with KIR2DL2/L3 single+ NK cell in pairs of donor Bw4C1C2 and host Bw4C1C2. 2. Donor KIR ligated by both donor and host HLA contribute to better single-KIR+ NK cell education among the same single-KIR+ NK cells. KIR2DL2/L3 single+ NK cell in the group of d-rsKIR (C1Cx-C1Cx) exhibit higher reactivity compared with other groups (dsKIR (C1Cx-C2C2), rsKIR (C2C2- C1Cx)). KIR2DL1 single+ NK cells in group of d-rsKIR (C2Cx-C2Cx) exhibited higher reactivity compared with other groups (nsKIR (C1C1-C1C1), dsKIR (C2Cx-C1C1), rsKIR (C1C1-C2Cx)). KIR3DL1 single+ NK cells in groups of d-rsKIR (Bw4Bwx-Bw4Bwx) exhibited higher reactivity compared with other groups (nsKIR (Bw6Bw6-Bw6Bw6), dsKIR (Bw4Bwx-Bw6Bw6), rsKIR (Bw6Bw6-Bw4Bwx)). 3. Both donor and host HLA must coexist for maximum education of NK cells given donor 3 inhibitory KIRs. When both of donor and host presenting all HLA (Bw4C1C2), we showed a remarkable hierarchy of responses among NK populations. NK cells with two inhibitory KIRs for self-HLA exhibited higher NK responsiveness (CD107α and IFN-γ) compared with single KIR+ NK cells. NK cells with 3 inhibitory KIRs for self-HLA exhibited maximum responsiveness. 4. Both donor and host exhibiting all HLA (Bw4C1C2) for donor 3 inhibitory KIRs contributes to least relapse following haploidentical allo-HSCT. In the second cohort, the lowest relapse rate was found in d-rsKIR group (n=31, 0%) compared with rsKIR group (n=55 ,0% vs. 10.0±4.9%, P=0.115), dsKIR group (n=33, 0% vs 14.9%±7.0%, P=0.039), or nsKIR group (n=156, 0% vs. 18%±3.5%, P=0.022). Summary: This study demonstrated that when both donors and hosts present all the KIR ligands for donor KIRs, reconstituted NK cells would achieve better functional education and contribute to least relapse for the patients. Disclosures No relevant conflicts of interest to declare.

Description: Introduction Myeloid-derived suppressor cells (MDSCs) are proposed to control graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the definition of human MDSCs has not yet reached consensus. Granulocyte colony-stimulating factor (G-CSF) has been routinely used to mobilize stem cells to peripheral blood in healthy donors. It was also recognized as a novel mediator of T-cell tolerance. However, the effects of G-CSF administration on donor-derived MDSCs and the further regulatory effects of these MDSCs on GVHD remained unclear. Amis The aim of this study is to evaluate the in vitro and in vivo effects of G-CSF expanded, donor-derived MDSCs (HLA-DR-/lowCD16-CD33+) in preventing acute GVHD after allo-HSCT. Methods The frequency and cell numbers of different kinds of MDSCs in peripheral blood before and after G-CSF administration from 10 healthy donors were analyzed by flow cytometry. Cells morphological features were detected by May-Grünwald-Giemsa cytospin. Secondly, the suppressive and regulatory functions of HLA-DR-/lowCD16-CD33+ population on CD3+ T cells were assessed via in vitro experiments. A humanized xenogeneic acute GVHD model was established to determine whether this population could prevent acute GVHD in vivo. Furthermore, a clinical prospective cohort study enrolled one hundred consecutive transplant recipients was performed to assess the effects of HLA-DR-/lowCD16-CD33+ contained in HSC grafts on the occurrence of acute GVHD. Results The findings of this study include: First, a novel phenotype of HLA-DR-/lowCD16-CD33+ MDSCs with suppressive function and morphological features similar to those of immature monocyte was identified. The median of percentages of this subset were significantly increased both in peripheral blood (PB, 6.5% vs. 4.6%, P=0.0122) and peripheral blood stem cells harvest (PBSCs, 15.5% vs. 4.6%, P