Graft-versus-host Disease Therapy Research Articles

Ex vivo-generated human CD1c+ regulatory B cells by a chemically defined system suppress immune responses and alleviate graft-versus-host disease

IL-10+ regulatory B cells (Bregs) show great promise in treating graft versus host disease (GVHD), a life-threatening complication of post-hematopoietic stem cell transplantation. However, obtaining high-quality human IL-10+ Bregs in vitro remains a challenge due to the lack of unique specific marker and the triggering of pro-inflammatory cytokines expression. Here, by uncovering the critical signaling pathways in Bregs induction by mesenchymal stromal cells (MSCs), we firstly established an efficient Bregs induction system based on MSCs and GSK-3β blockage (CHIR-99021), which had a robust capacity to induce IL-10+ Bregs while suppress TNF-α expression. Furthermore, these Bregs population could be identified and enriched by CD1c+. Mechanistically, MSCs induced the expansion of Bregs through the PKA-mediated phosphorylation of cAMP response element binding protein (CREB). Thus, we developed a chemical-defined inducing protocol by PKA-CREB agonist, instead of MSCs, which can also effectively induce CD1c+ Bregs with lower TNF-α expression. Importantly, induced CD1c+ Bregs suppressed the proliferation of PBMC and the inflammatory cytokines secretion of T cells. When adoptive transferred to a humanized mouse model of GVHD, induced CD1c+ Bregs effectively alleviated GVHD. Overall, we establish an efficient ex vivo induction system for human Bregs, which has implications in developing novel Bregs-based therapies for GVHD.

Study Protocol: Predicting the Quality of Response to Specific Treatments (PQRST) in Chronic Graft-versus-Host Disease

BackgroundChronic graft-versus-host disease (GVHD) is a leading cause of late morbidity and mortality after allogeneic hematopoietic cell transplantation. Despite significant progress in chronic GVHD therapies, challenges remain in understanding pleomorphic phenotypes and varying response to treatment. The goal of the Predicting the Quality of Response to Specific Treatments (PQRST) in chronic GVHD study is to identify predictors of treatment response. This report describing the study design seeks to raise awareness and invite collaborations with investigators who wish to access clinical data and research samples from this study. MethodsThis is a prospective, observational cohort study involving data collection from patients who are beginning first-, second-, or third-line systemic therapy for chronic GVHD with defined agents. Evaluable participants will have baseline assessments and research samples prior to starting the index therapy, and 1 month after starting treatment. Response assessments occur at 3 and 6 months after start of treatment, or if a new systemic therapy is started before 6 months. Target enrollment is approximately 200 patients at 8 institutions, with at least 6 months of follow up to determine response to index therapy. ResultsEnrollment started in July 2020 and was delayed due to the COVID-19 pandemic; as of 3/1/2024, 137 evaluable participants have been enrolled. DiscussionThe Chronic GVHD Consortium “PQRST” is a large longitudinal cohort study that aims to investigate predictors of treatment response by identifying biologically and clinically defined patient subgroups. We welcome investigators to collaborate in the use of these data.Trial registration: NCT04431479

Real-World Outcomes of Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation in Japan: Retrospective Analysis of the Transplant Registry Unified Management Program Registry

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important therapeutic option for patients with hematologic malignancies. However, the development of graft-versus-host disease (GVHD) after allo-HSCT remains a challenge. Although systemic steroid therapy is the established first-line therapy for acute GVHD (aGVHD) and chronic GVHD (cGVHD), many patients are unresponsive or resistant to corticosteroid therapy, and the response is insufficient. This study aimed to evaluate the clinical characteristics of patients who developed aGVHD and cGVHD after allo-HSCT. This noninterventional, retrospective study used large national registry data from the Transplant Registry Unified Management Program. The study included 29,690 patients with a hematologic disease who underwent their first allo-HSCT between January 2010 and December 2019. The primary study endpoints were the cumulative incidence of aGVHD and cGVHD. The secondary endpoints were overall survival (OS) and nonrelapse mortality (NRM) of patients with aGVHD and cGVHD and OS and NRM of patients who received second-line therapy for aGVHD. Of 29,690 patients who underwent allo-HSCT, the graft source was related bone marrow (RBM) in 2807, related peripheral blood (RPB) in 6167, unrelated bone marrow in 10,556, unrelated peripheral blood (UPB) in 774, and unrelated cord blood in 9339. The cumulative incidence of grade II-IV aGVHD at 100 days was high after the related and unrelated mismatched transplantation. The response rates for first- and second-line therapy for aGVHD were low in the RBM/RPB-mismatched (59.6%/61.6%) and UPB-mismatched subgroups (45.5%), respectively. The 3-year NRM in patients with aGVHD was high in the RPB and UPB mismatched subgroups (37.9% and 31.2%, respectively). Developing a novel treatment for steroid-refractory aGVHD is necessary to improve transplantation outcomes, particularly for patients undergoing HLA-mismatched allo-HSCT.

The Application of PBM Therapy in Patients Subjected to Oral GVHD: A Review.

Background: Oral graft-versus-host disease (GVHD) is characterized by mucosal lesions, salivary gland dysfunction etc., accompanied by pain and oral dysfunction. The efficacy of photobiomodulation (PBM) in managing pain and inflammation has been demonstrated. PBM has been applied in oral GVHD and is regarded as a potent adjunctive therapy. Objective: To review the application of PBM for oral GVHD and summarize its biological mechanisms and recommended parameters. Materials and Methods: The article provides an overview of the therapeutic effects of PBM in oral GVHD cases. It analyzes the biological mechanisms from different aspects and explores the potential prospects of PBM, and appropriate parameters and frequency for GVHD are recommended. Conclusions: The efficacy of PBM in oral GVHD has been demonstrated through symptom alleviation and function improvement. It is recommended as an adjuvant therapy for oral GVHD. However, further research is required to explore optimal devices, parameters, and potential complications associated with using PBM in oral GVHD.

AMPK drives both glycolytic and oxidative metabolism in murine and human T cells during graft-versus-host disease

AbstractAllogeneic T cells reprogram their metabolism during acute graft-versus-host disease (GVHD) in a process involving the cellular energy sensor adenosine monophosphate (AMP)–activated protein kinase (AMPK). Deletion of AMPK in donor T cells limits GVHD but still preserves homeostatic reconstitution and graft-versus-leukemia effects. In the current studies, murine AMPK knock-out (KO) T cells decreased oxidative metabolism at early time points posttransplant and lacked a compensatory increase in glycolysis after inhibition of the electron transport chain. Immunoprecipitation using an antibody specific to phosphorylated targets of AMPK determined that AMPK modified interactions of several glycolytic enzymes including aldolase, enolase, pyruvate kinase M, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), with enzyme assays confirming impaired aldolase and GAPDH activity in AMPK KO T cells. Importantly, these changes in glycolysis correlated with both an impaired ability of AMPK KO T cells to produce significant amounts of interferon gamma upon antigenic restimulation and a decrease in the total number of donor CD4 T cells recovered at later times posttransplant. Human T cells lacking AMPK gave similar results, with glycolytic compensation impaired both in vitro and after expansion in vivo. Xenogeneic GVHD results also mirrored those of the murine model, with reduced CD4/CD8 ratios and a significant improvement in disease severity. Together these data highlight a significant role for AMPK in controlling oxidative and glycolytic metabolism in both murine and human T cells and endorse further study of AMPK inhibition as a potential clinical target for future GVHD therapies.

Interleukin-27 Promotes the Generation of Myeloid-derived Suppressor Cells to Alleviate Graft-versus-host Disease.

Stimulation of myeloid-derived suppressor cell (MDSC) formation represents a potential curative therapeutic approach for graft-versus-host disease (GVHD), which significantly impacts the prognosis of allogeneic hematopoietic stem cell transplantation. However, the lack of an effective strategy for inducing MDSC production in vivo has hindered their clinical application. In our previous study, MDSC expansion was observed in interleukin (IL)-27-treated mice. In this study, we overexpressed exogenous IL-27 in mice using a recombinant adeno-associated virus vector to investigate its therapeutic and exacerbating effects in murine GVHD models. In our study, we demonstrated that exogenous administration of IL-27 significantly suppressed GVHD development in a mouse model. We found that IL-27 treatment indirectly inhibited the proliferation and activation of donor T cells by rapidly expanding recipient and donor myeloid cells, which act as MDSCs after irradiation or under inflammatory conditions, rather than through regulatory T-cell expansion. Additionally, IL-27 stimulated MDSC expansion by enhancing granulocyte-monocyte progenitor generation. Notably, we verified that IL-27 signaling in donor T cells exerted an antagonistic effect on GVHD prevention and treatment. Further investigation revealed that combination therapy involving IL-27 and T-cell depletion exhibited remarkable preventive effects on GVHD in both mouse and xenogeneic GVHD models. Collectively, these findings suggest that IL-27 promotes MDSC generation to reduce the incidence of GVHD, whereas targeted activation of IL-27 signaling in myeloid progenitors or its combination with T-cell depletion represents a potential strategy for GVHD therapy.

The MAGIC algorithm probability predicts treatment response and long-term outcomes to second-line therapy for acute GVHD

AbstractThe significance of biomarkers in second-line treatment for acute graft-versus-host disease (GVHD) has not been well characterized. We analyzed clinical data and serum samples at the initiation of second-line systemic treatment of acute GVHD from 167 patients from 17 centers of the Mount Sinai Acute GVHD International Consortium (MAGIC) between 2016 and 2021. Sixty-two patients received ruxolitinib-based therapy, whereas 102 received other systemic agents. In agreement with prospective trials, ruxolitinib resulted in a higher day 28 (D28) overall response Frate than nonruxolitinib therapies (55% vs 31%, P = .003) and patients who received ruxolitinib had significantly lower nonrelapse mortality (NRM) than those who received nonruxolitinib therapies (point estimates at 2-year: 35% vs 61%, P = .002). Biomarker analyses demonstrated that the benefit from ruxolitinib was observed only in patients with low MAGIC algorithm probabilities (MAPs) at the start of second-line treatment. Among patients with a low MAP, those who received ruxolitinib experienced significantly lower NRM than those who received nonruxolitinib therapies (point estimates at 2-year: 12% vs 41%, P = .016). However, patients with high MAP experienced high NRM regardless of treatment with ruxolitinib or nonruxolitinib therapies (point estimates at 2-year: 67% vs 80%, P = .65). A landmark analysis demonstrated that the relationship between the D28 response and NRM largely depends on the MAP level at the initiation of second-line therapy. In conclusion, MAP measured at second-line systemic treatment for acute GVHD predicts treatment response and NRM. The outcomes of patients with high MAP are poor regardless of treatment choice, and ruxolitinib appears to primarily benefit patients with low MAP.

Lipocalin-2: a novel potential therapy for GVHD

Czech et al. used mouse models of allogeneic hematopoietic stem cell transplantation (allo-HCT) to investigate the role of lipocalin-2 (LCN2) as a newfound regulator of intestinal graft-versus-host disease (GVHD). Administration of recombinant LCN2 protein after disease onset prevented GVHD progression, suggesting that it may play a role in reversing tissue damage that has already begun.

Graft-versus-host disease (GVHD): General review

Graft-versus-host disease (GVHD) is one of the major complications and source of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT) procedure. GVHD divided into two types, acute GVHD, and chronic GVHD. Traditionally as is known, acute GVHD accruing 3 months (100 days) after HCT, and the chronic GVHD accruing after 3 months (over 100 days) after HCT. Generally, the most common symptoms of GVHD development: skin can be presented with rare rush, biopsies can show dyskeratotic keratinocytes. Liver presented with damage to the bile ducts and elevation of bilirubin levels. Lung's damage, bronchiolitis. Endoscopy of the anterointernal can show damage to the cecum, ileum, and colon. In addition, damage to the upper intestinal system. Traditionally GVHD prophylaxis protocol consisted immunosuppression agents as calcineurin inhibitors such as Tacrolimus or Cyclosporine. In case of GVHD development, the standard first-line therapy of GVHD is corticosteroids (systemic and topical) including immunosuppression agent.

Placenta-Derived Decidua Stromal Cells: A New Frontier in the Therapy of Acute Graft-Versus-Host Disease.

Acute graft-versus-host disease (GVHD) is a frequent and potentially life-threatening complication following allogeneic hematopoietic cell transplantation (HCT). Mesenchymal stromal cells (MSCs), rare precursors found in all body tissues, possess immunosuppressive properties and can inhibit alloreactivity both in vitro and in vivo. Two decades ago, we introduced bone marrow-derived (BM) MSCs as a novel therapy for acute GVHD. While some patients responded to BM-MSCs, the response was not universal. Commercially available BM-MSCs are now used for acute GVHD treatment in Canada, Japan, and New Zealand. The fetus is protected from the mother's immune system by the placenta, and our research found that placenta-derived decidua stromal cells (DSCs) offer a stronger immunosuppressive effect than other sources of stromal cells. Safety studies in rabbits, rats, mice, and humans have shown negligible or no side effects from BM-MSCs or DSCs. In a phase I/II trial for severe acute GVHD, we treated 21 patients (median age, 49 years; range 1.6-72 years) with severe biopsy-proven gastrointestinal acute GVHD. The median cell dose of DSCs was 1.2 × 106 (range 0.9-2.9) cells/kg body weight, with a median of 2 (range 1-6) infusions given 1 week apart. The cell viability of DSCs was 93% (range, 69%-100%), and the median cell passage number was 4 (range, 2-4). All patients responded, with a complete response of acute GVHD in 11 patients and partial response in 10 and 1-year survival of 81%. Randomized trials are needed to prove the superiority of DSCs compared to ruxolitinib and/or other novel immunosuppressive therapies.

Separation of GVL from GVHD -location, location, location.

Allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for various hematologic malignancies. However, alloimmune response is a double-edged sword that mediates both beneficial graft-versus-leukemia (GVL) effects and harmful graft-versus-host disease (GVHD). Separation of GVL effects from GVHD has been a topic of intense research to improve transplant outcomes, but reliable clinical strategies have not yet been established. Target tissues of acute GVHD are the skin, liver, and intestine, while leukemic stem cells reside in the bone marrow. Tissue specific effector T-cell migration is determined by a combination of inflammatory and chemotactic signals that interact with specific receptors on T cells. Specific inhibition of donor T cell migration to GVHD target tissues while preserving migration to the bone marrow may represent a novel strategy to separate GVL from GVHD. Furthermore, tissue specific GVHD therapy, promoting tissue tolerance, and targeting of the tumor immune microenvironment may also help to separate GVHD and GVL.

IFNγ Primed MSCs Suppress Stimulated T Cells By Inducing Perturbations of Redox Homeostasis

Acute Graft versus host disease (GVHD) remains the primary cause of morbidity and nonrelapse mortality after allogeneic hematopoietic cell transplantation (HCT). Despite the current standard prophylaxis, approximately 50% of patients will develop acute GVHD. the outcome of patients with steroid-refractory and/or severe GVHD is poor; hence, more effective prophylaxis reducing the risk of these scenarios is greatly needed. In recent years, considerable attention has been directed toward mesenchymal stromal cells (MSCs) as prophylaxis and therapy for acute GVHD. Even though the immunosuppressive and immunomodulatory properties of MSCs are enhanced by proinflammatory cytokines such as interferon γ (γMSCs), relatively less attention has been focused on these cells. Our laboratory has shown human γMSCs are effective in GVHD prophylaxis in a fully mismatched murine HCT/GVHD model. When infused IV on day +1 after HCT, γMSCs traffic to the spleen, liver, and gut-associated lymphoid tissue (GALT) which is essential for effective prophylaxis. This may be a key element of the mechanism of prophylaxis as the gut and GALT are thought to be paramount for the development of GVHD. We now sought to understand the mechanism(s) of γMSC suppression of alloreactive T cells suppressive activity in this specific clinical and biological setting. In vivo, control mice transplanted with a fully MHC mismatched graft developed GVHD in 6-8 days (0% GVHD-free survival) while human γMSCs administration at day +1 completely prevented GVHD in the first 17 days (100% GVHD survival) but the animals developed acute GVHD in 21-28 days. Hence, a single dose of γMSCs is 100% effective early but is insufficient for overall GVHD prevention. The mechanism is highly effective but of relatively short duration, and seemingly reversible. In vitro, the reversible T cell suppressive activity was entirely contact-independent, while cell-to-cell contact could induce T cell death. Moreover, γMSC IDO1 expression, alone, was sufficient to suppress T cells. After 24 hours of T cell activation or γMSC suppression in vitro, we found the T cells were arrested in G0 inconsistent with most cell cycle regulation which would arrest cells in late G1 at the so-called restriction point. In scRNA Seq, we identified 16,478 expressed genes in both groups but only 98 genes were significantly differentially expressed (≥20% FC, Padj ≤ 10 -4). ROS response pathways were significantly enriched in the suppressed cells suggesting oxidative stress. Paradoxically, flow cytometric analysis of CM-H2DCFDA stained T cells revealed less ROS in suppressed cells compared to controls. Additionally, total NAD is elevated and the NAD/NADH ratio was 10-fold less in suppressed T cells compared to activated cells indicating an excess of reducing equivalents in the suppressed cells. Collectively these data define reductive stress. On this note, the upregulation of ROS response genes is also consistent with reductive stress. IDO1 activity seems to have induced reductive stress. The IDO1 catalytic activity converts tryptophan (Trp) to kynurenine (Kyn). We then found the addition of Trp (10 µM) to γMSC CM abolished suppression; supplementing fresh media with 15-fold excess Kyn had no effect. Moreover, RPMI without Trp and with dialyzed FBS also conferred suppression to activated T cells. These data suggest that among the many metabolites consumed or generated in γMSC CM, the lack of Trp induces T cell suppression. Trp supplementation of γMSC CM showed the expected level of ROS in activated T cells suggesting the Trp deficiency caused the reduced ROS. Supplementing γMSC CM with a graded concentration of hydrogen peroxide, we found that 100 nM hydrogen peroxide was not toxic to control cells, had ROS similar to activated T cells, and abolished suppression indicating the reduced ROS directly caused suppression. Kyn, nutritional deficiency, or an integrated stress response did not seem to play a measurable role in this setting. Collectively, our data suggest that IDO1-mediated Trp deficiency perturbs redox homeostasis (reductive stress) which suppresses activated T cells. We postulate that once redox homeostasis is restored, T cell activation proceeds. Future efforts will be directed toward identifying the link between Trp deficiency and redox homeostasis in this setting, and the genomic changes that directly mediate the lack of T cell proliferation.

The MAGIC Algorithm Probability Predicts Long-Term Outcomes and Treatment Response to Second-Line Therapy for Acute Gvhd

Introduction: Risk stratification approaches using clinical criteria or biomarkers in acute graft-versus-host disease (GVHD) have traditionally been implemented at diagnosis or initiation systemic treatment with corticosteroids. For patients who require second-line treatment, the significance of biomarkers at salvage therapy and the relationship between biomarker risk and choice of therapy are unknown. Methods: We studied adult patients who received second-line treatment for acute GVHD between January 2016 and December 2021 in the Mount Sinai Acute GVHD Consortium (MAGIC) database, which collects clinical data and longitudinal serum samples from allogeneic HCT recipients using a rigorous PRoBE study design. Exclusion criteria included relapse of underlying malignant disease prior to second-line therapy, missing response data, or missing serum sample. Serum samples collected from 7 days prior to 3 days after initiation of second-line therapy met criteria for biomarker analysis. The MAGIC algorithm probability (MAP) was calculated as a single value based on concentrations of ST2 and REG3α and was stratified at a threshold of 0.290 to define high MAP and low MAP groups. The primary objective evaluated the association between MAP and survival for patients receiving second-line therapy for acute GVHD. The key secondary objective was to investigate the MAP and choice of second-line systemic agent on Day 28 overall response rate (ORR) and survival. Results: In total, 316 adult patients received second-line treatment for acute GVHD; 149 patients (47%) were excluded for disease relapse (n=27), missing response data (n=48), or missing sample (n=74).Of the 167 evaluable patients, most had steroid-refractory acute GVHD (n=146, 87%), rather than steroid-dependent (n=8, 5%) or steroid-sensitive (n=14, 8%) disease. 62 patients received ruxolitinib while 102 received other systemic agents (best available therapy: BAT). Baseline clinical characteristics of the study population according to treatment choice were similar, except for donor type (Rux: MRD 15%, MUD 74%, haplo 11%; BAT: MRD 30%, MUD 67%, haplo 3%; P=0.014) and median days from corticosteroids to second-line treatment (Rux: 18, BAT: 12; P=0.02).In total, 81 patients had high MAPs and 86 patients had low MAPs, with similar distribution in each treatment cohort (P=0.53). For the entire cohort, the median follow-up for survivors was 22 months (range, 1.5-27).The MAP separated patients into 2 groups (high vs low) with significantly different mortality (NRM at 2 years, 76% vs 29%, P<.0001) and survival (OS at 2 years, 12% vs 63%, P<.0001). Patients who received ruxolitinib as second-line therapy had lower mortality (NRM at 2 years, 35% vs 60%, P<.002) and improved survival (OS at 2 years, 51% vs 32%, P<.008), compared to those who received other systemic agents. However, the outcomes of patients with high MAP were poor, regardless of second-line treatment choice ( Figure 1A). The MAP (low vs high), time from corticosteroids to second-line treatment (≥14 days vs < 14 days), GVHD grade at second-line (0-2 vs 3-4), and choice of second-line therapy (Rux vs BAT) were all significant (P<0.05) predictors of lower NRM and higher OS in multivariate analysis. The MAP also separated patients into 2 groups with significantly different D28 ORR (low: 49%, high: 30%, P<.0001). In agreement with prospective trials, ruxolitinib resulted in higher D28 response rates compared to other systemic therapies (ORR 54.9% vs 30.5%, P=0.005), which was observed in both low MAP (ORR, 64.5% vs 38.5%, P=0.017) and high MAP cohorts (ORR, 42.9% vs 22.6%, P=0.06) ( Figure 1B). The MAP (low vs high), GVHD grade at second line (0-2 vs 3-4), and choice of second-line therapy (Rux vs BAT) were significant predictors (P<0.05) of higher D28 ORR in multivariate analysis. Conclusion: The MAP measured at the initiation of second-line systemic treatment for acute GVHD predicts NRM and OS, as well as treatment response. The outcomes of patients with high MAP are poor, regardless of second-line treatment choice, and the higher CR rate in low MAP patients may drive higher survival rates. Incorporation of MAP into clinical trials in this setting warrants investigation. The results also support the current use of ruxolitinib as second-line treatment for acute GVHD, particularly in patients with low MAP.

Hospital survival following pediatric HSCT: changes in complications, ICU therapies and outcomes over 10 years.

Hematopoietic stem cell transplantation (HSCT) is an increasingly utilized therapy for malignant and non-malignant pediatric diseases. HSCT complications, including infection, organ dysfunction, and graft-versus-host-disease (GVHD) often require intensive care unit (ICU) therapies and are associated with mortality. Our aims were to identify the HSCT characteristics, complications and ICU therapies associated with (1) survival, and (2) survival changes over a ten-year period in a national dataset. A national sample from the Health Facts (Cerner Corporation, Kansas City, MO) database from 2009 to 2018 was utilized. Inclusion criteria were age 30 days to <22 years and HSCT procedure code. For patients with >1 HSCT, the first was analyzed. Data included demographics, hospital length of stay (LOS), hospital outcome, transplant type and indication. HSCT complications included GVHD and infections. ICU therapies were positive pressure ventilation (PPV), vasoactive infusion, and dialysis. Primary outcome was survival to discharge. Statistical methods included bivariate analyses and multivariate logistic regression. 473 patients underwent HSCT with 93% survival. 62% were allogeneic (89% survival) and 38% were autologous (98% survival). GVHD occurred in 33% of allogeneic HSCT. Infections occurred in 26% of all HSCT. ICU therapies included PPV (11% of patients), vasoactive (25%), and dialysis (3%). Decreased survival was associated with allogeneic HSCT (p < 0.01), GVHD (p = 0.02), infection (p < 0.01), and ICU therapies (p < 0.01). Survival improved from 89% (2009-2013) to 96% (2014-2018) (p < 0.01). Allogeneic survival improved (82%-94%, p < 0.01) while autologous survival was unchanged. Survival improvement over time was associated with decreasing infections (33%-21%, p < 0.01) and increasing vasoactive infusions (20%-28%, p = 0.05). On multivariate analysis, later time period was associated with improved survival (p < 0.01, adjusted OR 4.28). Hospital survival for HSCT improved from 89% to 96% from 2009 to 2018. Factors associated with mortality included allogeneic HSCT, GVHD, infections and ICU therapies. Improving survival coincided with decreasing infections and increasing vasoactive use.

Assessing cell chimerism in an acute graft-versus-host disease model established in TLR4 knockout mice.

Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation. To elucidate the role of Toll-like receptor 4 (TLR4), the major receptor for bacterial lipopolysaccharide, in the development of GVHD, we constructed a GVHD model in TLR4 knockout (TLR4-/-) mice and monitored the cell chimerism. In this study, we used polymerase chain reaction to identify whether TLR4 knockout (TLR4-/-) mice were established. Before transplantation, we pretreated mice with irradiation so as to obtain an appropriate irradiation dose. Flow cytometry was applied to measure the chimerism status, the distributions of antigen-presenting cells (APCs), and T-cells in TLR4+/+ and TLR4-/- recipient mice. The general condition of TLR4-/- recipients was better than that of TLR4+/+ recipients, and the TLR4-/- recipient mice showed less severe GVHD manifestations than the TLR4+/+ recipient mice. Most of the APCs and T-cells in the host mouse spleen were derived from donor cells, and CD4+ T-cells, including memory T-cells, were in the majority in host mice. In general, our data show that TLR4 deletion attenuated GVHD development, which suggests that TLR4 could be used as a novel target and therapeutic paradigm in GVHD therapies.

Exosomes, MDSCs and Tregs: A new frontier for GVHD prevention and treatment.

The development of graft versus host disease (GVHD) represents a long-standing complication of allogeneic hematopoietic cell transplantation (allo-HCT). Different approaches have been used to control the development of GVHD with most relying on variations of chemotherapy drugs to eliminate allo-reactive T cells. While these approaches have proven effective, it is generally accepted that safer, and less toxic GVHD prophylaxis drugs are required to reduce the health burden placed on allo-HCT recipients. In this review, we will summarize the emerging concepts revolving around three biologic-based therapies for GVHD using T regulatory cells (Tregs), myeloid-derived-suppressor-cells (MDSCs) and mesenchymal stromal cell (MSC) exosomes. This review will highlight how each specific modality is unique in its mechanism of action, but also share a common theme in their ability to preferentially activate and expand Treg populations in vivo. As these three GVHD prevention/treatment modalities continue their path toward clinical application, it is imperative the field understand both the biological advantages and disadvantages of each approach.

The Microbiome and Its Impact on Allogeneic Hematopoietic Cell Transplantation.

Allogeneic hematopoietic cell transplantation (alloHCT) is a standard curative therapy for a variety of benign and malignant hematological diseases. Previously, patients who underwent alloHCT were at high risk for complications with potentially life-threatening toxicities, including a variety of opportunistic infections as well as acute and chronic manifestations of graft-versus-host disease (GVHD), where the transplanted immune system can produce inflammatory damage to the patient. With recent advances, including newer conditioning regimens, advances in viral and fungal infection prophylaxis, and novel GVHD prophylactic and treatment strategies, improvements in clinical outcomes have steadily improved. One modality with great potential that has yet to be fully realized is targeting the microbiome to further improve clinical outcomes.In recent years, the intestinal microbiota, which includes bacteria, fungi, viruses, and other microbes that reside within the intestinal tract, has become established as a potent modulator of alloHCT outcomes. The composition of intestinal bacteria, in particular, has been found in large multicenter prospective studies to be strongly associated with GVHD, treatment-related mortality, and overall survival. Murine studies have demonstrated a causal relationship between intestinal microbiota injury and aggravated GVHD, and more recently, clinical interventional studies of repleting the intestinal microbiota with fecal microbiota transplantation have emerged as effective therapies for GVHD. How the composition of the intestinal bacterial microbiota, which is often highly variable in alloHCT patients, can modulate GVHD and other outcomes is not fully understood. Recent studies, however, have begun to make substantial headway, including identifying particular bacterial subsets and/or bacterial-derived metabolites that can mediate harm or benefit. Here, the authors review recent studies that have improved our mechanistic understanding of the relationship between the microbiota and alloHCT outcomes, as well as studies that are beginning to establish strategies to modulate the microbiota with the hope of optimizing clinical outcomes.

Extracorporeal photopheresis as an immunomodulatory treatment modality for chronic GvHD and the importance of emerging biomarkers.

Haematopoietic stem cell transplantation (HSCT) is the treatment of choice for malignant haematological diseases. Despite continuous improvements in pre- and post-transplantation procedures, the applicability of allo-HSCT is limited by life-threatening complications such as graft-versus-host disease (GvHD), engraftment failure, and opportunistic infections. Extracorporeal photopheresis (ECP) is used to treat steroid resistant GvHD with significant success. However, the molecular mechanisms driving its immunomodulatory action, whilst preserving immune function, require further understanding. As ECP is safe to administer with few significant adverse effects, it has the potential for earlier use in the post-HSCT treatment of GvHD. Thus, further understanding the immunomodulatory mechanisms of ECP action may justify more timely use in clinical practice, as well as identify biomarkers for using ECP as first line or pre-emptive GvHD therapy. This review aims to discuss technical aspects and response to ECP, review ECP as an immunomodulatory treatment modality for chronic GvHD including the effect on regulatory T cells and circulating vs. tissue-resident immune cells and consider the importance of emerging biomarkers for ECP response.

Recent advances in ocular graft-versus-host disease.

Ocular graft-versus-host-disease (GVHD) remains a significant clinical complication after allogeneic hematopoietic stem cell transplantation. Impaired visual function, pain, and other symptoms severely affect affected individuals' quality of life. However, the diagnosis of and therapy for ocular GVHD involve a multidisciplinary approach and remain challenging for both hematologists and ophthalmologists, as there are no unified international criteria. Through an exploration of the complex pathogenesis of ocular GVHD, this review comprehensively summarizes the pathogenic mechanism, related tear biomarkers, and clinical characteristics of this disease. Novel therapies based on the mechanisms are also discussed to provide insights into the ocular GVHD treatment.

Cellular senescence marker p16INK4a and NFKB1 gene polymorphisms in lower gastro-intestinal acute graft versus host disease

BackgroundLower gastrointestinal (GI) graft versus host disease (GVHD) represents a severe complication in allogeneic hematopoietic stem cell transplant (HSCT) recipients with high rates of transplant-related mortality. Deregulated innate immunity reactions are the features of its pathogenesis. Cellular senescence has been considered a program of the innate immunity. We focused on lower GI GVHD from the perspective of cellular senescence. ObjectiveWe analyzed the impact of p16INK4a expression, a hallmark of cellular senescence, in intestinal biopsies of patients with lower GI GVHD symptoms and NFKB1 gene polymorphisms (rs3774937 C/T and rs3774959 A/G) on HSCT outcome. Study designFifty-two single-center patients who presented with symptoms of lower GI GVHD were analyzed in a retrospective manner. Two SNPs located in the NFKB1 gene regions (rs3774937 C/T and rs3774959 A/G) were genotyped from the peripheral blood samples collected before the start of the conditioning. All patients underwent proctosigmoidoscopy with biopsy of the mucosa. The expression of p16INK4a was analyzed in normal intestinal crypts and stroma. ResultsFifty-two patients (50% male) received HSCT for hematological diseases (acute leukemias in 67%) and developed lower GI symptoms. Patients with p16INK4a expression in the intestinal stroma were in lower risk of developing histological grade 3–4 aGVHD (RR 0.18 [95% CI 0.05–0.65]; p = 0.009). The multivariate linear regression confirmed the independent effect of p16INK4a expression on time of the lower GI aGVHD symptoms onset (Coef. 38.9 [95% CI 12.7–65.1]; p = 0.005). The NFKB1 rs3774937 CC and TT/TC genotype were present in 40 and 80% of patients with p16INK4a expression, respectively (p = 0.04). The rs3774959 AA and GG/AG genotype were present among 43 and 82% of patients with p16INK4a expression, respectively (p = 0.02). Expression of p16INK4a was associated with no clinical variable but NFKB1 genotype. ConclusionsOur results address possible new mechanisms that may lead to better understanding of HSCT-related immune complications. Cellular senescence may bring novel approaches in GVHD diagnostics and therapy.