Development Of aGVHD Research Articles

Gut microbiota and graft-versus-host disease in hematopoietic stem cell transplant patients

Background and Objectives: Graft-versus-host disease (GvHD) frequently complicates hematopoietic stem cell transplan- tation (HSCT). Emerging evidence suggests a correlation between gut microbiota and GvHD risk. This study aims to eluci- date the microbiota profiles in HSCT patients before and after transplantation and their association with GvHD. Materials and Methods: This study, conducted from December 2022 to December 2023, involved the collection of 15 stool samples from HSCT patients. Bacterial content was quantified using real-time PCR, while interleukin-6 levels were assessed via ELISA. Results: Among the 15 participants (8 male, 7 female), 9 underwent allogeneic HSCT (allo-HSCT) and 6 received autol- ogous HSCT. In the aGvHD group, there was a significant reduction in the abundance of Bacteroides and Bifidobacterium compared to those without aGvHD. Additionally, declines were observed in Clostridium and Firmicutes populations. The genus Blautia also showed reduced prevalence in the aGvHD group, whereas no significant differences were noted in the uncomplicated group. ELISA analysis revealed that interleukin-6 levels remained within the normal range (30-960 pg/ml) with no significant elevation in the aGvHD group. Conclusion: The study highlights a notable association between alterations in gut microbiota, specifically reductions in certain bacterial populations and the development of aGvHD following allo-HSCT.

IFN-γ induces acute graft-versus-host disease by promoting HMGB1-mediated nuclear-to-cytoplasm translocation and autophagic degradation of p53.

Acute graft-versus-host disease (aGVHD) poses a significant impediment to achieving a more favourable therapeutic outcome in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our prior investigations disclosed a correlation between p53 down-regulation in CD4+ T cells and the occurrence of aGVHD. Notably, the insufficiency of the CCCTC-binding factor (CTCF) emerged as a pivotal factor in repressing p53 expression. However, the existence of additional mechanisms contributing to the reduction in p53 expression remains unclear. Interferon (IFN)-γ, a pivotal proinflammatory cytokine, assumes a crucial role in regulating alloreactive T-cell responses and plays a complex part in aGVHD development. IFN-γ has the capacity to induce autophagy, a vital catabolic process facilitating protein degradation, in various cell types. Presently, whether IFN-γ participates in the development of aGVHD by instigating the autophagic degradation of p53 in CD4+ T cells remains an unresolved question. In the present study, we demonstrated that heightened levels of IFN-γ in the plasma during aGVHD promoted the activation, proliferation, and autophagic activity of CD4+ T cells. Furthermore, IFN-γ induced the nuclear-to-cytoplasm translocation and autophagy-dependent degradation of p53 in CD4+ T cells. The translocation and autophagic degradation of p53 were contingent upon HMGB1, which underwent up-regulation and translocation from the nucleus to the cytoplasm following IFN-γ stimulation. In conclusion, our data unveil a novel mechanism underlying p53 deficiency in CD4+ T cells among aGVHD patients. This deficiency is induced by IFN-γ and relies on autophagy, establishing a link between IFN-γ, HMGB1-mediated translocation, and the autophagic degradation of p53.

Human gut microbiota-reactive DP8α Tregs prevent acute graft-versus-host disease in a CD73-dependent manner.

Graft-versus-host disease (GvHD) is a life-threatening complication frequently occurring following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Since gut microbiota and regulatory T cells (Tregs) are believed to play roles in GvHD prevention, we investigated whether DP8α Tregs, which we have previously described to harbor a T cell receptor specificity for the gut commensal Faecalibacterium prausnitzii, could protect against GvHD, thereby linking the microbiota and its effect on GvHD. We observed a decrease in CD73+ DP8α Treg frequency in allo-HSCT patients 1 month after transplantation, which was associated with acute GvHD (aGvHD) development at 1 month after transplantation, as compared with aGvHD-free patients, without being correlated to hematological disease relapse. Importantly, CD73 activity was shown to be critical for DP8α Treg suppressive function. Moreover, the frequency of host-reactive DP8α Tregs was also lower in aGvHD patients, as compared with aGvHD-free patients, which could embody a protective mechanism responsible for the maintenance of this cell subset in GvHD-free patients. We also showed that human DP8α Tregs protected mice against xenogeneic GvHD through limiting deleterious inflammation and preserving gut integrity. Altogether, these results demonstrated that human DP8α Tregs mediate aGvHD prevention in a CD73-dependent manner, likely through host reactivity, advocating for the use of these cells for the development of innovative therapeutic strategies to preclude aGvHD-related inflammation.

Unravelling the potential of TIM-3 gene polymorphism in allogeneic hematopoietic stem cell transplantation - a preliminary study

BackgroundT-cell immunoglobulin and mucin-domain containing-3 (TIM-3) molecule is a key regulator of the immune response by exerting an inhibitory effect on various types of immune cells. Understanding the role of TIM-3 in hematopoietic stem cell transplantation (HSCT) may improve transplant outcomes. Our study evaluated the potential association between TIM-3 polymorphisms, namely rs1036199 (A > C) or rs10515746 (C > A), changes which are located in exon 3 and the promoter region of the TIM-3 gene, and post-HSCT outcomes. MethodsOne-hundred and twenty allogeneic HSCT patients and their respective donors were enrolled and genotyped for TIM-3 single nucleotide polymorphisms (SNPs) using real-time PCR with TaqMan assays. ResultsWe found that the presence of the rare alleles and heterozygous genotypes of studied SNP in recipients tended to protect against or increase the risk for acute graft-versus-host disease (aGvHD). For the rs1036199 polymorphism, recipients with the AC heterozygous genotype (p = 0.0287) or carrying the rarer C allele (p = 0.0334) showed a lower frequency of aGvHD development along all I-IV grades. A similar association was detected for the rs10515746 polymorphism as recipients with the CA genotype (p = 0.0095) or the recessive A allele (p = 0.0117) less frequently developed aGvHD. Furthermore, the rarer A allele of rs10515746 SNP was also associated with a prolonged aGvHD-free survival (p = 0.0424). Cytomegalovirus (CMV) infection was more common in patients transplanted with TIM-3 rs10515746 mismatched donors (p = 0.0229) and this association was also found to be independent of HLA incompatibility and pre-transplant CMV-IgG status. Multivariate analyses confirmed the role of these recessive alleles and donor-recipient TIM-3 incompatibility as an independent factor in aGvHD and CMV development. ConclusionsPolymorphism of TIM-3 molecule may affect the immune response in HSCT patients. The recessive alleles of rs1036199 and rs10515746 SNPs decreased the risk of developing aGvHD. TIM-3 donor-recipient genetic matching may also affect the risk of post-transplant CMV infection, indicating the potential value of genetic profiling in optimizing transplant strategies.

Dual roles of CD11b+CD33+HLA-DR-/lowCD14- myeloid-derived suppressor cells with a granulocytic morphology following allogeneic hematopoietic stem cell transplantation: from inflammation promoters to immune suppressors within 90 days.

Granulocytic myeloid-derived suppressor cells (G-MDSCs) show fast recovery following allogeneic hematopoietic stem cell transplantation (allo-HSCT) constituting the major part of peripheral blood in the early phase. Although G-MDSCs mediate immune suppression through multiple mechanisms, they may also promote inflammation under specific conditions. G-MDSCs were isolated from 82 patients following allo-HSCT within 90 days after allo-HSCT, and their interactions with autologous CD3+ T-cells were examined. T-cell proliferation was assessed by flow cytometry following CFSE staining, while differentiation and interferon-γ secretion were characterized using chemokine receptor profiling and ELISpot assays, respectively. NK cell cytotoxicity was evaluated through co-culture with K562 cells. An aGVHD xenogeneic model in humanized mice was employed to study the in vivo effects of human leukocytes. Furthermore, transcriptional alterations in G-MDSCs were analyzed via RNA sequencing to investigate functional transitions. G-MDSCs promoted inflammation in the early-stage, by facilitating cytokine secretion and proliferation of T cells, as well as their differentiation into pro-inflammatory T helper subsets. At day 28, patients with a higher number of G-MDSCs exhibited an increased risk of developing grades II-IV aGvHD. Besides, adoptive transfer of G-MDSCs from patients at day 28 into humanized mice exacerbated aGvHD. However, at day 90, G-MDSCs led to immunosuppression, characterized by upregulated expression of indoleamine 2,3-dioxygenase gene and interleukin-10 secretion, coupled with the inhibition of T cell proliferation. Furthermore, transcriptional analysis of G-MDSCs at day 28 and day 90 revealed that 1445 genes were differentially expressed. These genes were associated with various pathways, revealing the molecular signatures of early post-transplant differentiation in G-MDSCs. In addition, genes linked to the endoplasmic reticulum stress were upregulated in patients without aGvHD. The acquisition of immunosuppressive function by G-MDSCs may depend on the activation of CXCL2 and DERL1 genes. Our findings revealed the alteration in the immune characteristics of G-MDSCs within the first 90 days post-allo-HSCT. Moreover, the quantity of G-MDSCs at day 28 may serve as a predictive indicator for the development of aGvHD.

Suppression of P53 Pathway is an Important Factor Inducing Acute Graft-versus-Host Disease Through T Cell Activation Based on Bioinformatics Analysis.

Acute graft-versus-host disease (aGVHD) poses a significant impediment to achieving a more favourable therapeutic outcome in allogeneic hematopoietic stem cell transplantation (allo-HSCT). The tumour suppressor p53 plays a pivotal role in preventing aGVHD development. However, whether P53 pathway which contains p53 family members and other related genes participates in aGVHD development remains an unsolved question. Transcriptomic data was obtained from Gene Expression Omnibus (GEO) database. Gene set enrichment analysis was applied to determine the enrichment degree of signaling pathways. CIBERSORT and ssGSVA were used to evaluate immune cell compositions. Univariate and multivariate logistic regression analysis were performed to examine the independent diagnostic variables. qRT-PCR was utilized to validate the genes expression levels in our cohort. A total number of 102 patients (42 aGVHD patients vs 60 non-aGVHD patients) were obtained after integrating two datasets in GEO database (GSE73809 and GSE4624). P53 pathway was remarkably suppressed in T cells from aGVHD patients and negatively associated with activated T cells as well as T cells activation related signaling pathways, including T-cell receptor (TCR), mTORC1, MYC and E2F target pathways. A risk model for aGVHD built by four genes (DDIT3, FBXW7, TPRKB and TOB1) in P53 pathway, exhibiting high differentiate and predictive value. DDIT3 and FBXW7 mRNA expression levels significantly decreased in peripheral blood mononuclear cells (PBMCs) from aGVHD patients compared with non-aGVHD group in our patient cohort, consisting with bioinformatics analysis. P53 pathway plays a potential role in impeding T cell activation through suppressing its related signaling pathways, thereby preventing aGVHD development. P53 pathway may emerge as a promising therapeutic target in aGVHD treatment.

Blockade of CCR5 and CXCR3 attenuates murine acute graft-versus-host disease through modulating donor-derived T-cell distribution and function.

Lymphocyte trafficking via chemokine receptors such as C-C chemokine receptor 5 (CCR5) and CXCR3 plays a critical role in the pathogenesis of acute graft-versus-host disease (aGVHD). Our previous studies showed that the addition of CCR5 or CXCR3 antagonists could only slightly alleviate the development of aGVHD. Given the specificity of T lymphocytes bearing CXCR3 and CCR5, we investigated whether combined CCR5 and CXCR3 blockade could further attenuate murine aGVHD. A mouse model of aGVHD was established to assess the efficacy of CCR5 and/or CXCR3 blockade on the development of aGVHD. The distribution of lymphocytes was calculated by quantification of immunostaining cells. The immunomodulatory effect on T cells was assessed by evaluating T-cell proliferation, viability, and differentiation. Using the murine allogeneic hematopoietic stem cell transplantation model, we demonstrated that blockade of both CCR5 and CXCR3 could efficiently alleviate the development of aGVHD. Further investigation on the immune mechanisms for this prophylactic effect showed that more T cells were detained into secondary lymphoid organs (SLOs), which may lead to reduced infiltration of T cells into GVHD target organs. Our study also showed that T cells detained in SLOs dampened the activation, suppressed the polarization toward T helper type 1 (Th1) and T cytotoxic type 1 (Tc1) cells, and induced the production of Treg cells. These data suggest that concurrent blockade of CCR5 and CXCR3 attenuates murine aGVHD through modulating donor-derived T-cell distribution and function, and this might be applicable for aGVHD prophylaxis in clinical settings.

Altered lipid metabolism in patients with acute graft-versus-host disease after allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the sole curative option for many hematological malignancies and other diseases. Nevertheless, its application is limited due to the risk of life-threatening complications, mainly graft-versus-host disease (GVHD). Currently, in clinical practice, the risk of developing GVHD is estimated for every patient based on factors related to the donor and the host. In our prospective, observational study, we analyzed serum from 38 patients undergoing allo-HCT at our institution. We compared the metabolic profiles of patients who developed acute GVHD (aGVHD) with those without such complication by identification and comparison of metabolites masses on the XCMS platform. We observed that patients diagnosed with aGVHD had different metabolic profiles compared to the remaining patients and this alteration was noticeable already 7 days before the procedure. We identified dysregulated metabolites involved in bile acid transformation and cholesterol synthesis. Our study of the untargeted metabolome in allo-HCT recipients has revealed a potential link between lipid metabolism, specifically involving bile acid transformation and cholesterol synthesis, and the development of aGVHD. This finding might be an important indication for future research focused on understanding GVHD development, discovering prediction models, and investigating possible prophylactic interventions.

Lower incidence of grade II-IV acute Graft-versus-Host-Disease in pediatric patients recovering with high Vδ2+ T cells after allogeneic stem cell transplantation with unmanipulated bone marrow grafts: a prospective single-center cohort study.

Gamma delta (γδ) T cells represent a minor fraction of human T cell repertoire but play an important role in mediating anti-infectious and anti-tumorous effects in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We performed a prospective study to analyze the effect of different transplant modalities on immune reconstitution of γδ T cells and subsets. CD3, CD4 and CD8 T cells were analyzed in parallel. Secondly, we examined the impact of γδ T cell reconstitution on clinical outcomes including acute Graft-versus-Host-Disease (aGvHD) and viral infections. Our cohort includes 49 pediatric patients who received unmanipulated bone marrow grafts from matched unrelated (MUD) or matched related (MRD) donors. The cohort includes patients with malignant as well as non-malignant diseases. Cell counts were measured using flow cytometry at 15, 30, 60, 100, 180 and 240 days after transplantation. Cells were stained for CD3, CD4, CD8, CD45, TCRαβ, TCRγδ, TCRVδ1, TCRVδ2, HLA-DR and combinations. Patients with a MRD showed significantly higher Vδ2+ T cells than those with MUD at timepoints +30, +60, +100 (p<0.001, respectively) and +180 (p<0.01) in univariate analysis. These results remained significant in multivariate analysis. Patients recovering with a high relative abundance of total γδ T cells and Vδ2+ T cells had a significantly lower cumulative incidence of grade II-IV aGvHD after transplantation (p=0.03 and p=0.04, respectively). A high relative abundance of Vδ2+ T cells was also associated with a lower incidence of EBV infection (p=0.02). Patients with EBV infection on the other hand showed higher absolute Vδ1+ T cell counts at days +100 and +180 after transplantation (p=0.046 and 0.038, respectively) than those without EBV infection. This result remained significant in a multivariate time-averaged analysis (q<0.1). Our results suggest a protective role of γδ T cells and especially Vδ2+ T cell subset against the development of aGvHD and EBV infection after pediatric HSCT. Vδ1+ T cells might be involved in the immune response after EBV infection. Our results encourage further research on γδ T cells as prognostic markers after HSCT and as possible targets of adoptive T cell transfer strategies.

Monocytes as an early risk factor for acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Acute graft-versus-host disease (aGVHD) is a major complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and contributes to high morbidity and mortality. However, our current understanding of the development and progression of aGVHD after allo-HSCT remains limited. To identify the potential biomarkers for the prevention and treatment of aGVHD during the early hematopoietic reconstruction after transplantation, we meticulously performed a comparative analysis of single-cell RNA sequencing data from post-transplant patients with or without aGVHD. Prior to the onset of aGVHD, monocytes in the peripheral blood of patients with aGVHD experienced a dramatic rise and activation on day 21 post-transplantation. This phenomenon is closely aligned with clinical cohort results obtained from blood routine examinations. Furthermore, in vitro co-culture experiments showed that peripheral blood monocytes extracted from patients with aGVHD approximately 21 days post-transplantation induced a significantly higher proliferation rate of allogeneic T cells compared to those from patients without aGVHD. Our study indicates that monocytes could be a crucial early clinical risk factor for the development of aGVHD, and this insight could potentially guide the timing of monitoring efforts, recommending assessments at the pivotal juncture of approximately day 21 post-transplantation, shedding fresh light on the significance of early hematopoietic regeneration in relation to the onset of aGVHD.

Human leukocyte antigen evolutionary divergence as a novel risk factor for donor selection in acute lymphoblastic leukemia patients undergoing haploidentical hematopoietic stem cell transplantation.

The human leukocyte antigen (HLA) evolutionary divergence (HED) reflects immunopeptidome diversity and has been shown to predict the response of tumors to immunotherapy. Its impact on allogeneic hematopoietic stem cell transplantation (HSCT) is controversial in different studies. In this study, we retrospectively analyzed the clinical impact of class I and II HED in 225 acute lymphoblastic leukemia patients undergoing HSCT from related haploidentical donors. The HED for recipient, donor, and donor-recipient pair was calculated based on Grantham distance, which accounts for variations in the composition, polarity, and volume of each amino acid within the peptide-binding groove of two HLA alleles. The median value of HED scores was used as a cut-off to stratify patients with high or low HED. The class I HED for recipient (R_HEDclass I) showed the strongest association with cumulative incidence of relapse (12.2 vs. 25.0%, P = 0.00814) but not with acute graft-versus-host disease. The patients with high class II HED for donor-recipient (D/R_HEDclass II) showed a significantly higher cumulative incidence of severe aGVHD than those with low D/R_HEDclass II (24.0% vs. 6.1%, P = 0.0027). Multivariate analysis indicated that a high D/R_HEDclass II was an independent risk factor for the development of severe aGVHD (P = 0.007), and a high R_HEDclass I had a more than two-fold reduced risk of relapse (P = 0.028). However, there was no discernible difference in overall survival (OS) or disease-free survival (DFS) for patients with high or low HED, which was inconsistent with the previous investigation. While the observation are limited by the presented single center retrospective cohort, the results show that HED has poor prognostic value in OS or DFS, as well as the associations with relapse and aGVHD. In haploidentical setting, class II HED for donor-recipient pair (D/R_HEDclass II) is an independent and novel risk factor for finding the best haploidentical donor, which could potentially influence clinical practice if verified in larger cohorts.

A dynamic time-to-event model for prediction of acute graft-versus-host disease in patients after allogeneic hematopoietic stem cell transplantation.

Acute graft-versus-host disease (aGvHD) is a major cause of death for patients following allogeneic hematopoietic stem cell transplantation (HSCT). Effective management of moderate to severe aGvHD remains challenging despite recent advances in HSCT, emphasizing the importance of prophylaxis and risk factor identification. In this study, we analyzed data from 1479 adults who underwent HSCT between 2005 and 2017 to investigate the effects of aGvHD prophylaxis and time-dependent risk factors on the development of grades II-IV aGvHD within 100 days post-HSCT. Using a dynamic longitudinal time-to-event model, we observed a non-monotonic baseline hazard overtime with a low hazard during the first few days and a maximum hazard at day 17, described by Bateman function with a mean transit time of approximately 11 days. Multivariable analysis revealed significant time-dependent effects of white blood cell counts and cyclosporine A exposure as well as static effects of female donors for male recipients, patients with matched related donors, conditioning regimen consisting of fludarabine plus total body irradiation, and patient age in recipients of grafts from related donors on the risk to develop grades II-IV aGvHD. Additionally, we found that higher cumulative hazard on day 7 after allo-HSCT are associated with an increased incidence of grades II-IV aGvHD within 100 days indicating that an individual assessment of the cumulative hazard on day 7 could potentially serve as valuable predictor for later grades II-IV aGvHD development. Using the final model, stochastic simulations were performed to explore covariate effects on the cumulative incidence over time and to estimate risk ratios. Overall, the presented model showed good descriptive and predictive performance and provides valuable insights into the interplay of multiple static and time-dependent risk factors for the prediction of aGvHD.

Planning GvHD preemptive therapy: risk factors, biomarkers, and prognostic scores.

Prevention of acute and chronic graft-versus-host disease (aGvHD and cGvHD) is an important objective of allogeneic hematopoietic cell transplantation (HCT). While there is has been significant progress in preventative approaches in the peritransplant period to minimize development of GvHD, no preventative approach has completely eliminated development of either aGvHD or cGvHD. Recently, posttransplant immune biomarker profiling early post-HCT by the Mount Sinai Acute GvHD International Consortium group has resulted in a validated risk assignment algorithm and development of preemptive approaches to decrease aGvHD and mortality in high-risk patients. cGvHD risk assignment algorithms have been developed based on measurements at day 100 and may be used for future preemptive intervention trials to minimize cGvHD. This article discusses the current state of the art in aGvHD and cGvHD preemptive algorithms and therapeutic interventions and what is needed to move these into validated approaches.

Donor Macrophage Pyroptosis Contributed to the Development of aGVHD

Introduction Pyroptosis, a novel form of inflammation-related programmed cell death, often occurs in myeloid cells. Many studies have found that macrophage pyroptosis plays an important role in multiple inflammatory diseases, such as sepsis, liver injury, and autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis (Journal of Autoimmunity, 2018). Acute GVHD (graft versus host disease) is an immune disease involving various inflammatory factors, and macrophage dysfunction was observed in our previous study (Sci China Life Sci, 2020). During the initiation of aGVHD, large amounts of DAMPs and PAMPs are also released by radiotherapy and infection, which may trigger pyroptosis. However, whether macrophages undergo pyroptosis in aGVHD remains unknown and needs further exploration. Methods The peritoneal macrophages from aGVHD mice were collected after transplantation. Scanning electron microscopy was used to observe cell morphology. Flow cytometry, LDH release and PI staining were used to evaluate cell death. Target tissues, including skin, liver, colon and ileum, were obtained after transplantation for histopathologic analysis, immunofluorescence, immunohistochemical staining and Wb tests. Pyroptosis-related inflammatory factors, including IL-1β and IL-18, were evaluated by a BCA assay and immunohistochemistry. Macrophages and CD4 + T cells were isolated from the bone marrow and spleens of C57 mice. Macrophage-specific GSDMD knockdown mice using adeno-associated serotype 9 virus (AAV9) viral vectors and macrophage conditional GSDMD KO mice (GSDMD rlysm) were used to demonstrate the role of macrophage pyroptosis in the development of aGVHD. Intestinal tissues and peripheral blood from patients with aGVHD and without aGVHD were collected to further validate the occurrence of macrophage pyroptosis in aGVHD. Results Scanning electron microscopy images showed the formation of membrane pores in the peritoneal macrophages of aGVHD mice. Moreover, cell death and LDH release were significantly increased in the peritoneal macrophages of aGVHD mice. The number of GSDMD + macrophages and expression levels of IL-1β and IL-18 were significantly increased in the target tissues of aGVHD mice. The expression of GSDMD-N was also significantly increased in the liver tissue of aGVHD mice. These results indicated that aGVHD was accompanied by macrophage pyroptosis. In addition, elevated levels of IL-1β and IL-18 were observed in the serum and colons of aGVHD patients, which further demonstrated the occurrence of macrophage pyroptosis in aGVHD. To determine whether macrophage pyroptosis contributed to the development of aGVHD, we used macrophage-specific GSDMD knockdown mice with AAV9 viral vectors and WT mice as recipients or donors to compare their disease severity and overall survival. Less pathological damage to tumor tissues, lower clinical scores and longer survival were observed in recipients with macrophage-specific GSDMD knockdown in their donors, indicating that macrophage pyroptosis in donor mice promoted the development of aGVHD. Furthermore, similar results were observed in recipients when macrophage-conditioned GSDMD KO mice (GSDMD rlysm) were their donors. Given the important role of CD4 +T cells in the pathogenesis of aGVHD, the effects of macrophage pyroptosis on CD4 + T cells in vitro were further investigated. In vitro, macrophage pyroptosis promoted the proliferation of CD4 + T cells and increased the proportion of CD69 + cells among CD4 +T cells. The proportions of Th1 and Th17 cells were increased, and the proportion of Tregs was decreased after coculturing with pyroptosed macrophages. These results suggested that macrophage pyroptosis might be involved in the development of aGVHD by affecting CD4 +T cells. In addition, a reduced proportion of activated CD4 +T cells, Th1, Th17 cells and an increased proportion of Tregs were observed in recipients when their donors were macrophage-specific GSDMD knockdown or GSDMD rlysm, further demonstrating that macrophage pyroptosis from donors promoted the development of aGVHD by affecting the function of CD4 + T cells. Conclusions In conclusion, macrophage pyroptosis derived from donors were first found in aGVHD, and they might participate in the development of aGVHD by affecting the activation, proliferation and differentiation of CD4 + T cells.

Soluble LAG3: A Potential Marker for the Development and Activity of Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (aGVHD), usually developing within 100 days after hematopoietic stem cell transplantation (HSCT), is mainly attributed to donor T cell pro-inflammatory responses against mismatched host histocompatibility antigens. The persistence of increased effector T cell responses following HSCT is partially related to an altered function of T regulatory cells (Tregs) and their failure to prevent GVHD. Certain immune checkpoint molecules, such as cytotoxic T-lymphocyte antigen 4, programmed cell death protein 1 (PD1) and lymphocyte activation gene-3 (LAG3), highly expressed on Tregs, are involved in maintaining immune tolerance and preventing immune-mediated inflammation. LAG3 is a newly identified inhibitory receptor, found on most immune cells, including CD4+ and CD8+ T cells, Tregs, and dendritic cells. Previous studies have demonstrated a role of LAG3 expression on T cells in GVHD suppression. Its soluble isoform sLAG3, released from the cell membrane, has been recently reported to also contribute to enhanced immune-mediated responses in solid tumors and autoimmune diseases, such as anti-PD1-resistant melanoma, rheumatoid arthritis (RA), and ANCA-associated vasculitis. Given this evidence, the current study aimed to explore a potential role of sLAG3 in GVHD development. Serum samples of 25 patients (≥18 years old) who underwent allogeneic HSCT at Rambam from 01.2021 to 01.2023 were drawn on days -7, +100, +180 of transplant. Twelve serum samples obtained from the Biobank were used as healthy control (HC). All samples were assessed for the sLAG3 levels using a commercial ELISA kit. The median level measured in HC (56pg/mL) was considered a cutoff to define the “low and high level sLAG3 groups”. Twenty-three patients were included in the analysis [median age at transplant - 59.5 years (range 19-75); 52% males]. Seventeen patients had acute myeloid leukemia, 3 - myelodysplastic syndrome, 2 - acute lymphoblastic leukemia and 1 had primary myelofibrosis. Fourteen patients had a matched unrelated donor, 6- matched related donors, and 3 - haploidentical donors. Nineteen patients received calcineurin inhibitor (CNI) and methotrexate-based GVHD prophylaxis (13 with ATG); 4 patients received post-transplant cytoxan-based prophylaxis, with CNI and mycophenolate-mofetil. Overall, 17/23 (74%) patients developed GVHD: 9 - aGVHD and 8 - chronic GVHD (cGVHD). A low pre-transplant sLAG3 level (&amp;lt;56pg/mL) was found in 8/23 patients, while it was high (&amp;gt;56pg/mL) in 15/23. Notably, 9/15 (60%) patients in the “high sLAG3 group”, but none in the “low sLAG3 group” were diagnosed with aGVHD, suggesting a high sLAG3 level as a possible indicator for patient-pre-transplant susceptibility to aGVHD development, irrespective of transplant factors, such as conditioning regimen, donor type, etc. Four patients in each group developed cGVHD. Furthermore, there was a significant increase in sLAG3 levels between the baseline and GVHD diagnosis in patients who developed aGVHD (mean: from 156.1±172.8, to 323.9±201.3), but not in those who either had cGVHD (mean: from 119.71±90.5 to 150.1±147.1) or did not have GVHD (mean: from 49.7±36 to 52.1±22.2). Overall, 11/23 patients were in complete remission (CR) at the time of HSCT; 9/11 were in the high-sLAG3 group and 6 of them developed aGVHD. In the low-sLAG3 group, most patients (6/8) had some degree of active disease (persistent disease or minimal-residual disease). These findings may reflect high T-effector cell and/or low Treg activity, possibly contributing to both anti-leukemic effect and GVHD development. In conclusion: The current study demonstrates, for the first time, that the pre-transplant sLAG3 level is significantly increased and continues to further increase in patients who develop aGVHD following HSCT compared to those who don't. These findings suggest a potential role of sLAG3 as a predicting factor for aGVHD development as well as a marker of treatment response that could guide therapeutic decisions in this patient setting.

PB CD8 T N and CD4 T EM on day30 after Allo-HSCT Is a Predictive Marker for the Development of aGVHD

Introduction ： Acute GVHD (aGVHD) is a common complication 20-60 days after allo-HSCT and can be life-threatening in some cases. It has been reported to be associated with T-cell immune reconstitution, but the detailed mechanisms are not clear. Early post-transplant lymphocyte recovery is mainly due to homeostatic peripheral expansion (HPE), which is variable depending on various factors such as donor source, recipient's age. T cell-related cytokines, such as sIL-2R , IL-7 and TNFr1 are known biomarkers for the aGVHD, but there are few reports that predict the aGVHD incidence rate using the peripheral blood (PB) lymphocyte subset. We evaluated the effect of PB lymphocyte subset in early post-transplant period on aGVHD. Methods ： We retrospectively analyzed 83 patients (40 in AML, 12 in ALL, 1 in MPAL, 13 in MDS, 2 in MPN, 9 in malignant lymphoma/LPD and 3 in AA) who underwent the allo-HSCT in our hospital from 2013 to 2023. The median age of patients was 44 years (range:17-66). Sixteen received BM, 47 received PB (including 28 with haploidentical (9 with ATG, 19 with PTCY)), and 20 received CB. GVHD prophylaxis was FK506+MTX in 61 patients, CyA+MTX in 3 and MMF+FK506+CY in 19. The median observation period was 495 [38-2983] days. PB lymphocyte subset (Naïve Tcell (T N):CD45RA+CD62L+, Central memory Tcell (T CM) :CD45RA-CD62L+, Effector memory Tcell (T EM) :CD45RA-CD62L-, Effector memory Tcell re-expressed CD45RA (T EMRA) :CD45RA+CD62L-, Th1:CD3+4+CXCR3+CCR6-, Th2:CD3+4+CXCR3-CCR6-, Th17:CD3+4+CXCR3-CCR6+) at day30 (range:28-35) after transplantation were analyzed by FCM. Results ： Twenty-five patients had grade II-IV aGVHD, and 11 had grade Ⅲ-IV aGVHD. Patients with Grade II-IV aGVHD exhibited significantly lower proportion of CD8+T N as compared to non aGVHD groups (GVHD+: 17.7 ± 13.3%; GVHD-: 30.9 ± 16.3%; p &amp;lt; 0.001) . In contrast, the proportion of CD4+T EM and CD8+T EM were higher in the Grade II-IV acute GVHD group (GVHD+: 30.9 ± 23.1%; GVHD-: 21.9 ± 15.6%; p=0.04, GVHD+: 36.1 ± 16.2%; GVHD-: 22.7 ± 14.7%; p &amp;lt; 0.001, respectively). We found a strong statistical correlation between the proportion of CD8+T N and CD8+T EM. The cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD8+T N &amp;lt;20% group was 56.9% and 29.6% compared with 14.2% and 6.3% for the CD8+T N &amp;gt;20% group (p &amp;lt; 0.001 and p &amp;lt; 0.01). Similarly, the cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD4+T EM &amp;gt;30% group was 48.1% and 32.6% compared with 22.2% and 5.9% for the CD4+T EM &amp;lt;30% group (p= 0.02 and p &amp;lt; 0.01). Two-year NRM was higher in the CD8+T N &amp;lt;20% group than in the CD8+T N &amp;gt;20% group (26.3% vs 4.2%, p=0.008). The two-year cumulative incidence of relapse (CIR) was comparable between the two groups, but tended to be lower in the mismatched CR group (CD8+T N &amp;lt;20%: 33.1% versus CD8+T N &amp;gt;20%: 43.4%, p=0.31). Conclusion ： PB CD8 T N and CD4 T EM fraction on day30 is a predictive biomarker for the development of acute GVHD.

Graft-Versus-Host Disease after Anti-CD19 Chimeric Antigen Receptor T-Cell Infusion Post Allogeneic Hematopoietic Cell Transplantation: A Transplant Complications and Paediatric Disease Working Parties EBMT Joint Study

Background Anti-CD19 chimeric antigen receptor T-cells (CART) have been incorporated into the therapeutic landscape of B-acute lymphoblastic leukemia (B-ALL) and B-non-Hodgkin's lymphoma (B-NHL). The manufacturing process of commercially available autologous CART in patients relapsing after allogeneic hematopoietic cell transplant (allo-HCT) might include T-cells of donor origin. In this setting, there is limited data on graft-versus-host disease (GvHD) as an off-target effect in patients treated with CART after allo-HCT. We hereby report on a large, retrospective, EBMT registry-based study on GvHD in patients treated with CART therapy after allo-HCT. Methods Inclusion criteria were B-ALL and B-NHL adult and pediatric allo-HCT patients, treated with a first anti-CD19 CART (axicabtagene ciloleucel [axi-cel] and tisagenlecleucel [tisa-cel]) from 2018 to August 2022. The primary study endpoints were the cumulative incidences (CI) of new acute GvHD (aGvHD) and chronic GvHD (cGvHD). Secondary endpoints were the 1-year GvHD relapse-free survival (GRFS), non-relapse mortality (NRM), and overall survival (OS). Overall data was analyzed in a descriptive manner. Results A total of 257 allo-HCT patients treated with anti-CD19 CART were included. One hundred seventy-two patients (66.9%) were ≥18 years old. Tisa-cel was the therapy of choice in 184 patients (71.6%), whereas axi-cel was used in 73 patients (28.4%). More than half of the cohort (57.6%) underwent allo-HCT from unrelated donors. Notably, 109 patients (46.6%) and 38 patients (15%) had previously develop aGvHD and cGvHD between allo-HCT and CART infusion. Table 1 describes data on baseline patient, allo-HCT and CART characteristics of the whole cohort and of patients developing aGvHD and cGvHD. In total, 3 patients developed new aGvHD and 6 patients developed new cGvHD after CART therapy. The 100-day CI of new aGvHD was 1.6% (95% CI, 0.4-4.2) and the 12-month CI of new cGvHD was 2.8% (95% CI, 1.1-5.7). No GvHD was observed in the pediatric cohort. The median time from allo-HCT to CART infusion was 15.8 months (range, 3.8-220.3) and the median times from CART to the development of aGvHD and cGvHD were respectively 44 days (range, 8-81) and 144 days (range, 5-182). The 1-year GRFS and NRM were 52.1% (95% CI 45.6-59.4) and 4.7% (95% CI 2.5-8.1) respectively (Figure 1). With a median follow up of 18.8 months (95% CI, 16.2-23.7), the 1-year OS was 76.8% (95% CI 71.5-82.4). The most frequent cause of death was disease-related in 56 patients (74.6%). Conclusion Together, in this large cohort including adult and pediatric allo-HCT patients treated with tisa-cel and axi-cel after allo-HCT, these data show that the incidence of both aGvHD and cGvHD is very low. Of note, GvHD was not observed in the pediatric cohort. Furthermore, no excessive NRM was observed compared to previously published methods of treating relapse post allo-HCT, being disease progression a major hurdle to optimal outcomes in this cohort of patients.

Itaconate Inhibits Th1 Differentiation and aGVHD Via Nrf2

Background：Acute graft-versus-host disease (aGVHD) is one of the major complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT), which is caused by the differentiation of pathogenic T cells and resulted a high mortality. Development of novel therapies is critical for the prevention and treatment of aGVHD. Aims：The current study aimed to investigate the role of itaconate in the pathogenesis of aGVHD after allo-HSCT. Methods：To establish murine aGVHD model, lethally irradiated BALB/C (H-2 d) recipients were injected intravenously with 1×10 7 bone marrow (BM) cells and 5×10 6 splenocytes from C57BL/6 or Nrf2 deficiency (H-2 b) donors. Recipients were intraperitoneally injected with 30mg/kg itaconate once a day 3 days prior to BMT for a period of one week. To explore the potential mechanisms of itaconate in the regulation of aGVHD, we profiled the immune cell responses in splenocytes by flow cytometry 2 weeks post transplantation. To detect a CD4 or CD8 dependent manner, recipients were transplanted with TCD-BMs together with either CD4 or CD8 depleted splenocytes respectively. To elucidate the role of itaconate in Th1 development, naïve CD4 +T cells were sorted from WT or Nrf2 KO mice and induced in a Th1 polarization condition for 3 days. IFN-γ production was measured in the supernatant of Th1 cells by ELISA. RNA-Seq was performed to investigate the mechanism of itaconate involved in the regulation of Th1 cell differentiation. Immunofluorescence staining were performed to detect the function of itaconate on Nrf2 expression. The expression of Nrf2 downstream genes were determined by real-time PCR. Total ROS releasing in Th1 cells were detected by a DCFH-DA method. Results：The survival of receipts administrated with itaconate was significantly prolonged than control mice, companied by a lower aGVHD clinical score and decreased tissue damage. The proportions of CD3 +T, CD4 +T, CD8 +T cells were comparable between recipients treated with PBS or itaconate. T cell activations in recipients treated with itaconate were significantly suppressed compared to those of controls. However, itaconate didn't affect the percentages of Tregs and myeloid subsets, including DCs, macrophages and neutrophils. Interestingly, the population of IFN-γ producing CD4 +T, but not CD8 +T, was substantially decreased after itaconate treatment. Moreover, productions of IL-6 and IFN-γ in serum were significantly decreased. The protective effect of itaconate were diminished after depletion of donor derived CD4 +T cells or IFN-γ. RNA-seq and in vitro studies showed that itaconate could directly inhibit Th1 development by regulating oxidative stress response. Itaconate activated Nrf2 downstream genes, thus suppressed ROS production. Both in vitro and in vivo Th1 differentiation were abrogated after Nrf2 depletion. The protective role of itaconate in aGVHD was also diminished when utilizing Nrf2 deficient mice as donors. Conclusion：Itaconate significantly inhibited the activation and IFN-γ production of T cells, rather than interrupted the distribution of myeloid subsets, corresponding to mitigated aGVHD development. Itaconate directly suppressed Th1 differentiation and regulated aGVHD by a CD4 dependent manner. Mechanistically, itaconate promoted the expression of Nrf2 and its downstream genes thus suppressed ROS production, leading to a defective Th1 differentiation. Thus, our results revealed a protective role of itaconate in the pathogenesis of aGVHD by regulating Th1 differentiation.

Outcome improvement over time in reduced intensity conditioning hematopoietic transplantation: a 20-year experience.

The current study includes all consecutive patients (N = 484) who received a reduced-intensity conditioning regimen (RIC) allogeneic hematopoietic stem cell transplantation in our center from 1999 to 2020. Conditioning regimens were based on fludarabine with melphalan or busulfan, with low-dose thiotepa and pharmacological GVHD prophylaxis consisted of cyclosporine A (CsA)-methotrexate (MTX)/mofetil (MMF) (n = 271), tacrolimus-sirolimus (n = 145), and post-transplantation cyclophosphamide (PTCy)-tacrolimus (n = 68). The median time of overall follow-up in survivors was 8years (1-22years) and was at least 3years in all three GVHD prophylaxis groups. Thirty-three percent had a high or very high disease risk index, 56% ≥ 4 European bone marrow transplantation risk, and 65% ≥ 3 hematopoietic stem cell transplantation comorbidity index score-age score. Neutrophil and platelet engraftment was longer for PTCy-tacro (p 0.0001). Cumulative incidence of grade III-IV aGVHD was 17% at 200days, and that of moderate-severe cGvHD was 36% at 8years. GVHD prophylaxis was the only prognostic factor in the multivariable analyses for the development of aGVHD and moderate-severe cGVHD (p 0.0001). NRM and relapse incidences were 29% and 30% at 8years, while OS and PFS rates were 43% and 39% at 8years. At 3years, OS was highest in the PTCy-tacro group (68%) than in the tacro-siro (61%) and CsA-MTX/MMF (49%) cohorts (p < 0.01). In the three groups, respectively, the 200-day incidence of grade III-IV aGvHD (6% vs. 12% vs. 23%) and 3-year moderate-severe cGVHD (8% vs. 40% vs. 38%) were lower in the PTCy cohort. These better outcomes were confirmed in multivariable analyses. Based on our recent results, the PTCy could be considered as a real GvHD prophylaxis in the RIC setting due to improve best 3-year GvHD and survival outcomes.

HIF-1α-Dependent Autophagy Deficiency in Bone Marrow Endothelial Progenitor Cells Contributes to Acute Graft-Versus-Host Disease after Allotransplant

Background: Acute Graft-Versus-Host Disease (aGVHD) constitutes a prevalent component after allogeneic hematopoietic stem cell transplantation(allo-HSCT). Among the components of the Bone Marrow（BM)microenvironment, Endothelial Progenitor Cells (EPCs) hold significant importance in hematopoietic-supporting and immune reconstitution in post-transplantation patients. Consequently, a discernible correlation emerges between the impairment of EPCs and the incidence and severity of GVHD. Our recent study has shown impaired EPC function and heightened reactive oxygen species (ROS) levels in aGVHD patients (2018, BJH). Additionally, reduced levels of hypoxia-inducible factor-1α (HIF-1α) and autophagy were observed in BM EPCs from aGVHD patients in comparison to those without GVHD（non-GVHD）. HIF-1α is closely linked to ROS generation. Therefore， exploring the role of HIF-1α and autophagy in the development of aGVHD after allo-HSCT is significant. Aims： To conduct a comparative analysis of the functions of EPCs and assess the variations in the expression levels of HIF-1α and autophagy-related proteins between aGVHD and non-GVHD patients. Additionally, the study aims to assess whether the low HIF-1α level is responsible for the autophagy deficiency and mitochondrial dysfunction observed in EPCs of aGVHD patients, and to delineate the specific pathways through which this downregulation influences their capacity of hematopoiesis-supporting. Methods: The current prospective clinical case-matched study included 20 patients with aGVHD and 40 patients without GVHD. BM mononuclear cells（BMMNCs） were cultured as former publications reported. EPCs（CD34+, CD133+, CD309+) were flow-sorted for evaluating apoptosis, ROS, and autophagy levels. SiRNA transfection knocked down HIF-1α in human umbilical vein endothelial cells (HUVECs). Endothelial cells(ECs） gene expression levels were determined using Western blot, RT-qPCR. ECs function was assessed by angiogenesis, Transwell cell migration, CCK-8 cell proliferation, and JC-1 mitochondrial staining. ECs were co-cultured with hematopoietic stem cells （HSCs） for seven days, and HSCs were subjected to colony-forming unit assays and other experiments to evaluate hematopoietic stem cell function. ECs NAD+ and NADH levels were assessed by the kit. Results: Downregulation of autophagy signaling pathway in HUVECs following knockdown of HIF-1α, leading to inhibited cell proliferation, migration, and angiogenesis. Similarly, patients affected by aGVHD exhibited reduced HIF-1α expression, impaired autophagy, and cellular function in EPCs compared to non-GVHD patients. HSCs co-culturing with HUVECs with HIF-1α knockdown and EPCs from aGVHD patients resulted in increased apoptosis, elevated levels of ROS, and impaired colony formation ability. However, intervention with HIF-1α activators Roxadustat, which served to upregulate HIF-1α levels in ECs, activated autophagy, and improved cellular function, also enhanced the hematopoiesis-supporting ability. Furthermore, the knockdown of HIF-1α in HUVECs and EPCs of aGVHD patients led to the abnormal activation of SIRT1 and PARP1 and other NAD+-consuming proteins, which subsequently caused a decrease in NAD+ levels and resulted in abnormal mitochondrial membrane potential. The supplementation of NAD+ precursors, specifically β-nicotinamide mononucleotide, effectively increased NAD+ levels in ECs and restored cellular function. Conclusion: The results revealed that the autophagy deficiency was mediated by reduced expression of HIF-1α in EPCs of patients with aGVHD. The deficiency of autophagy also led to abnormal activation of SIRT1 and PARP1, which in turn affected the levels of NAD+ and mitochondrial membrane potential, ultimately impairing cellular function and hematopoiesis-supporting ability. These molecular changes may be identified as potential contributors to the pathogenesis of aGVHD after allo-HSCT. On the other hand, Roxadustat upregulates HIF-1α expression in ECs, which subsequently enhanced the autophagy level and improved mitochondrial function. As a result, cellular function and hematopoiesis-supporting ability were restored. This promising therapeutic approach highlights a novel strategy for preventing and treating of patients with aGVHD after allo-HSCT.