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INTRODUCTION: Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is commonly performed to treat a variety of benign and malignant hematological diseases. Acute graft-versus-host disease (GVHD) is a major life-threatening complication that often occurs following allo-HSCT. Recently, improvements in methods to characterize the microbiota have led to a greater appreciation for how frequently and profoundly an alteration in microbial composition, or dysbiosis, can occur in allo-HSCT recipients to better decipher the complex interplay of between microbiota and allo-HSCT outcomes. AREAS COVERED: This article reviews the current knowledge of the microbiota’s impact on allo-HSCT outcomes, including effects of microbiota-derived metabolites, and crosstalk between commensals and the allogeneic immune response. This article also summarizes the effects of HSCT and transplant-related procedures on microbiota, and recent developments in interventional strategies. EXPERT OPINION: A growing body of literature indicate that the composition of the intestinal microbiota can function as a predictive biomarker for the risk and severity of acute GVHD, as well as overall survival, in patients undergoing allo-HSCT. Mechanisms underpinning this associations, however, are not well-understood, and clinical strategies that modulate the microbiome to improve outcomes have yet to be fully developed. There is an unmet need to determine mechanisms to improve the efficacy of allo-HSCT.

Background Pegfilgrastim has equivalent efficacy to daily granulocyte colony-stimulating factor (G-CSF) in enhancing neutrophil recovery after chemotherapy, but data on its use for peripheral blood stem cell (PBSC) mobilization are limited. We evaluated the safety and efficacy of CD34+ PBSC mobilization by low-dose (3.6 mg) pegfilgrastim after chemotherapy in patients with malignant lymphoma. Study design and methods Twenty patients with malignant lymphoma were enrolled in this study. Cytotoxic chemotherapy was started on day 1, and 3.6 mg of pegfilgrastim was subcutaneously administered on day 7. CD34+ cells were counted in the peripheral blood daily from days 11 to 14 using a flow cytometric analysis. Results In 19 of the 20 patients (95%), the CD34+ cell counts in the peripheral blood exceeded 10 × 106/L, with a mean value of 20.3 on day 11, 38.0 on day 12, 40.3 on day 13, and 40.1 on day 14. Older age was associated with lower maximum CD34+ cell mobilization. The most frequent adverse events associated with pegfilgrastim were back pain, nausea, appetite loss, and lactate dehydrogenase elevation. Conclusion Our data indicated that a single dose of 3.6 mg pegfilgrastim on day 7 after chemotherapy safely and effectively mobilized CD34+ cells.

Aim: To measure histological villous atrophy and to clarify the diagnostic accuracy of endoscopic villous atrophy in gastrointestinal graft-versus-host disease. Methods: Data for patients who underwent upper and/or lower endoscopic examinations after hematopoietic stem cell transplantation were retrospectively collected. In study 1, group A included 56 patients in whom GI-GVHD was histologically confirmed and group B included 60 patients in whom GI-GVHD was not histologically confirmed. Group C included 59 patients before HSCT. The lengths of villi and crypts in the duodenum and terminal ileum were histologically measured. In study 2, the diagnostic accuracies of villous atrophy of the duodenum and of the terminal ileum using magnifying endoscopy were evaluated. Results: In study 1, the lengths of villi and the villi/crypt (V/C) ratios of the duodenum and terminal ileum in group A were significantly smaller than those in the other groups (p

The diversity of the human microbiome heralds the difference of the impact that gut microbial metabolites exert on allogenic graft-versus-host (GVH) disease (GVHD), even though short-chain fatty acids and indole were demonstrated to reduce its severity. In this study, we dissected the role of choline-metabolized trimethylamine N-oxide (TMAO) in the GVHD process. Either TMAO or a high-choline diet enhanced the allogenic GVH reaction, whereas the analog of choline, 3,3-dimethyl-1-butanol reversed TMAO-induced GVHD severity. Interestingly, TMAO-induced alloreactive T-cell proliferation and differentiation into T-helper (Th) subtypes was seen in GVHD mice but not in in vitro cultures. We thus investigated the role of macrophage polarization, which was absent from the in vitro culture system. F4/80(+)CD11b(+)CD16/32(+) M1 macrophage and signature genes, IL-1β, IL-6, TNF-α, CXCL9, and CXCL10, were increased in TMAO-induced GVHD tissues and in TMAO-cultured bone marrow–derived macrophages (BMDMs). Inhibition of the NLRP3 inflammasome reversed TMAO-stimulated M1 features, indicating that NLRP3 is the key proteolytic activator involved in the macrophage’s response to TMAO stimulation. Consistently, mitochondrial reactive oxygen species and enhanced NF-κB nuclear relocalization were investigated in TMAO-stimulated BMDMs. In vivo depletion of NLRP3 in GVHD recipients not only blocked M1 polarization but also reversed GVHD severity in the presence of TMAO treatment. In conclusion, our data revealed that TMAO-induced GVHD progression resulted from Th1 and Th17 differentiation, which is mediated by the polarized M1 macrophage requiring NLRP3 inflammasome activation. It provides the link among the host choline diet, microbial metabolites, and GVH reaction, shedding light on alleviating GVHD by controlling choline intake.

Chronic graft-versus-host disease (GVHD) profoundly affects the quality of life of long-term survivors of allogeneic hematopoietic stem cell transplantation (SCT). The eyes are frequently involved, and dry eye syndrome is the most common manifestation of ocular chronic GVHD. We explored the role of heat shock protein 47 (HSP47) in ocular GVHD and developed a novel antifibrotic topical therapy using vitamin A–coupled liposomes containing HSP47 small interfering RNA (siRNA) against HSP47 (VA-lip HSP47). In a mouse model of chronic GVHD, infiltration of HSP47+ fibroblasts and massive fibrosis surrounding the lacrimal ducts were observed after allogeneic SCT, leading to impaired tear secretion. After ocular instillation, VA-lip HSP47 was distributed to the lacrimal glands, knocked down HSP47 expression in fibroblasts, reduced collagen deposition, and restored tear secretion after allogeneic SCT. Ocular instillation of VA-lip HSP47 also ameliorated established lacrimal gland fibrosis and dry eye syndrome. VA-lip HSP47 eye drops are a promising prophylactic and therapeutic option against dry eye syndrome in chronic GVHD.

Graft-versus-host disease (GVHD) and infection are major obstacles to successful allogeneic hematopoietic stem cell transplantation (HSCT). Intestinal goblet cells form the mucus layers, which spatially segregate gut microbiota from host tissues. Although it is well known that goblet cell loss is one of the histologic features of GVHD, effects of their loss in pathophysiology of GVHD remain to be elucidated. In mouse models of allogeneic HSCT, goblet cells in the colon were significantly reduced, resulting in disruption of the inner mucus layer of the colon and increased bacterial translocation into colonic mucosa. Pretransplant administration of interleukin-25 (IL-25), a growth factor for goblet cells, protected goblet cells against GVHD, prevented bacterial translocation, reduced plasma concentrations of interferon-γ (IFN-γ) and IL-6, and ameliorated GVHD. The protective role of IL-25 was dependent on Lypd8, an antimicrobial molecule produced by enterocytes in the colon that suppresses motility of flagellated bacteria. In clinical colon biopsies, low numbers of goblet cells were significantly associated with severe intestinal GVHD, increased transplant-related mortality, and poor survival after HSCT. Goblet cell loss is associated with poor transplant outcome, and administration of IL-25 represents an adjunct therapeutic strategy for GVHD by protecting goblet cells.

Sinusoidal obstruction syndrome (SOS)/hepatic veno-occlusive disease (VOD) is a well-documented complication after hematopoietic stem cell transplantation (HSCT). Transabdominal ultrasonography (US) enables the visualization of blood flow abnormalities and is therefore useful for the diagnosis of SOS/VOD. We herein prospectively evaluated accuracy of a novel US diagnostic scoring system of SOS/VOD based on US findings. We carried out US in 106 patients on day 14 and when SOS/VOD was suspected after allogeneic HSCT. Among 106 patients, 10 patients (9.4%) were diagnosed as SOS/VOD by Baltimore or Seattle criteria. According to univariate analysis of 17 US findings (US-17 screening), we established a novel scoring system (HokUS-10) consisting of 10 parameters, such as gallbladder wall thickening, ascites, and blood flow signal in the paraumbilical vein. The sensitivity and specificity were 100% and 95.8%, respectively. Diagnostic performance of the HokUS-10 was significantly better than US-17 screening. In 4 of 10 patients US detection of SOS/VOD preceded to clinical diagnosis. The HokUS-10 scoring system is useful in the diagnosis of SOS/VOD; however, our results should be validated in other cohorts.

Chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (SCT) is characterized by multiorgan fibrosis and profoundly affects the quality of life of transplant survivors. Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, plays a critical role in collagen synthesis in myofibroblasts. We explored the role of HSP47 in the fibrotic process of cutaneous chronic GVHD in mice. Immunohistochemical analysis showed massive fibrosis with elevated amounts of collagen deposits and accumulation of F4/80+ macrophages, as well as myofibroblasts expressing HSP47 and retinol-binding protein 1 in the skin after allogeneic SCT. Repeated injection of anti-colony-stimulating factor (CSF-1) receptor-blocking antibodies significantly reduced HSP47+ myofibroblasts in the skin, indicating a macrophage-dependent accumulation of myofibroblasts. Vitamin A-coupled liposomes carrying HSP47 small interfering RNA (siRNA) (VA-lip HSP47) delivered HSP47 siRNA to cells expressing vitamin A receptors and knocked down their HSP47 in vitro. Intravenously injected VA-lip HSP47 were specifically distributed to skin fibrotic lesions and did not affect collagen synthesis in healthy skin. VA-lip HSP47 knocked down HSP47 expression in myofibroblasts and significantly reduced collagen deposition without inducing systemic immunosuppression. It also abrogated fibrosis in the salivary glands. These results highlight a cascade of fibrosis in chronic GVHD; macrophage production of transforming growth factor β mediates fibroblast differentiation to HSP47+ myofibroblasts that produce collagen. VA-lip HSP47 represent a novel strategy to modulate fibrosis in chronic GVHD by targeting HSP47+ myofibroblasts without inducing immunosuppression.

Hayase et al. show that R-Spondin1 stimulates intestinal stem cells to differentiate to Paneth cells and enhances luminal secretion of α-defensins. Administration of R-Spondin1 or recombinant α-defensin prevents dysbiosis mediated by graft-versus-host disease, representing a novel approach to restore intestinal ecosystems and homeostasis., The intestinal microbial ecosystem is actively regulated by Paneth cell–derived antimicrobial peptides such as α-defensins. Various disorders, including graft-versus-host disease (GVHD), disrupt Paneth cell functions, resulting in unfavorably altered intestinal microbiota (dysbiosis), which further accelerates the underlying diseases. Current strategies to restore the gut ecosystem are bacteriotherapy such as fecal microbiota transplantation and probiotics, and no physiological approach has been developed so far. In this study, we demonstrate a novel approach to restore gut microbial ecology by Wnt agonist R-Spondin1 (R-Spo1) or recombinant α-defensin in mice. R-Spo1 stimulates intestinal stem cells to differentiate to Paneth cells and enhances luminal secretion of α-defensins. Administration of R-Spo1 or recombinant α-defensin prevents GVHD-mediated dysbiosis, thus representing a novel and physiological approach at modifying the gut ecosystem to restore intestinal homeostasis and host–microbiota cross talk toward therapeutic benefits.

Posttransplant high-dose cyclophosphamide (PTCY) has been increasingly used as graft-versus-host disease (GVHD) prophylaxis after HLA-haploidentical or matched hematopoietic stem cell transplantation (SCT). However, PTCY alone is insufficient and requires additional immunosuppressants such as calcineurin inhibitors. In the current study, we evaluated effects of a novel GVHD prophylaxis with PTCY in combination with short-term KRP203, a selective agonist of sphingosine-1-phosphate receptor 1 that regulates egress of lymphocytes from the secondary lymphoid organs (SLOs) in mice. Short-term oral administration of KRP203 alone induced apoptosis of donor T cells in the SLOs and ameliorated GVHD. Administration of KRP203 significantly preserved graft-versus-leukemia effects compared to cyclosporin. A combination of KRP203 on days 0 to +4 and PTCY on day +3 synergistically suppressed donor T-cell migration into the intestine and skin, and ameliorated GVHD more potently than PTCY alone. A combination of short-term KRP203 and PTCY is a promising novel calcineurin-free GVHD prophylaxis in HLA-haploidentical SCT.

The R-Spondin (R-Spo) family regulates WNT signaling and stimulates the proliferation and differentiation of intestinal stem cells (ISCs). R-Spo plays a critical role in maintaining intestinal homeostasis, but endogenous producers of R-Spo in the intestine remain to be investigated. We found that R-Spo3 was the major R-Spo family member produced in the intestine and it was predominantly produced by CD45−CD90+CD31+ lymphatic endothelial cells (LECs) in the lamina propria of the intestinal mucosa. Transcriptome analysis demonstrated that LECs highly expressed R-Spo receptor, Lgr5, suggesting an autocrine stimulatory loop in LECs. LECs were significantly reduced in number, and their R-Spo3 production was impaired in intestinal graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation. The impaired production of R-Spo3 in the intestine may be a novel mechanism of delayed tissue repair and defective mucosal defense in intestinal GVHD. We demonstrate a novel role of intestinal LECs in producing R-Spondin3 to maintain intestinal homeostasis.

The association between Wilms tumor 1 (WT1) expression, genetic abnormalities and homozygous single polymorphism (SNP) in WT1 gene was evaluated in 252 acute myelogenous leukemia (AML) patients. WT1 expression correlated with prognostic genetic abnormalities. Homozygous WT1 SNP rs16754 was associated with lower expression of WT1. WT1 expression had no prognostic impact in any cytogenetic group or SNP status. Background: The prognostic impact of WT1 expression at diagnosis of acute myelogenous leukemia (AML) has been controversial. The aim of this study was to determine the correlations of WT1 expression at diagnosis of AML with established prognostic alterations. Patients and Methods: We analyzed diagnostic bone marrow samples from 252 patients. WT1 expression, SNP in WT1 gene (rs16754), and Flt3-ITD mutation were analyzed for all patients. NPM1 mutation and CEBPA double mutation were analyzed for cytogenetically normal (CN)-AML. KIT mutation was analyzed for core-binding factor (CBF)-AML. Results: Within the cytogenetically favorable prognosis group, WT1 expression in AML with inv(16) or t(15;17) was significantly higher than that in AML with t(8;21). In cases with CN-AML, Flt3-ITD and NPM1 mutations were both correlated with higher expression of WT1, whereas CEBPA double mutation was related to lower WT1 expression. The existence of both Flt3- ITD and NPM1 mutations showed synergistically higher expression of WT1 in CN-AML. SNP in WT1 gene (rs16754) was significantly associated with lower expression of WT1. WT1 levels were not prognostic factors in the total cohort, in any cytogenetic group nor SNP status. Conclusion: Since WT1 expression correlated to known prognostic factors, the prognostic impact of WT1 levels might be misunderstood depending on the distribution of collaborative mutations in each cohort. We conclude that the prognostic significance of WT1 at diagnosis of AML is weak compared to other established prognostic factors.

Benign precursors of B lymphocytes, termed hematogones, are observed in the regenerative state of hematopoiesis following chemotherapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). Previous studies have demonstrated that expansion of hematogones correlates with better clinical outcomes after allo-HSCT. We retrospectively analyzed the association between hematogones and clinical outcomes in 309 consecutive patients who underwent allo-HSCT, which is the largest population-based cohort reported so far. The incidence of hematogones was significantly higher in complete remission (CR) patients at the time of transplantation than in non-CR patients, after myeloablative conditioning than after reduced-intensity conditioning, with tacrolimus-based graft-versus-host disease (GVHD) prophylaxis than with cyclosporine-based prophylaxis, and with disease other than malignant lymphoma (all P.05). Patients with hematogones developed less acute GVHD and infections than did those without them (P.05). Emergence of hematogones was associated with superior GVHD-free relapse-free survival and lower nonrelapse mortality, and was an independent prognostic factor for overall survival, irrespective of donor sources.

Although graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), cytomegalovirus (CMV) reactivation also occurs in patients after allo-HSCT and these conditions often clinically overlap. The aim of this study was to determine reliable endoscopic findings of CMV colitis in patients with gastrointestinal graft-versus-host-disease (GI-GVHD). Patients after allo-HSCT who were histologically confirmed to have GI-GVHD with or without CMV colitis and patients with an immunosuppressive condition were retrospectively analyzed. We divided the patients into three groups: GI-GVHD with CMV colitis (group A), GI-GVHD without CMV colitis (group B), and CMV colitis without undergoing allo-HSCT (group C). From medical records, the involved colorectal areas and endoscopic findings according to the groups were compared. A total of 70 patients were divided into three groups (group A: n = 19, group B: n = 28, group C: n = 23). Mucosal injuries in groups A and C frequently occurred in the cecum including ileocecal valves. On the other hand, there were no abnormal lesions on ileocecal valves in group B. Furthermore, ulcer lesions were more frequently observed in groups A and C than in group B (p

Graft-versus-host disease (GVHD) is the major complication after allogeneic stem cell transplantation (SCT). Emerging evidence indicates that GVHD leads to injury of intestinal stem cells. However, it remains to be investigated whether skin stem cells could be targeted in skin GVHD. Lgr5+ hair follicle stem cells (HFSCs) contribute to folliculogenesis and have a multipotent capacity to regenerate all epithelial cells in repair. We studied the fate of Lgr5+ HFSCs after SCT and explored the novel treatment to protect Lgr5+ HFSCs against GVHD using murine models of SCT. We found that GVHD reduced Lgr5+ HFSCs in association with impaired hair regeneration and wound healing in the skin after SCT. Topical corticosteroids, a standard of care for a wide range of skin disorders including GVHD, damaged HFSCs and failed to improve skin homeostasis, despite of their anti-inflammatory effects. In contrast, JAK1/2 inhibitor ruxolitinib significantly ameliorated skin GVHD, protected Lgr5+ HFSCs, and restored hair regeneration and wound healing after SCT. We, for the first time, found that GVHD targets Lgr5+ HFSCs and that topical ruxolitinib represents a novel strategy to protect skin stem cells and maintain skin homeostasis in GVHD.

Intestinal microbiota plays an important role in the regulation of allogeneic immune reaction after allogeneic hematopoietic stem cell transplantation (allo-SCT). Intestinal graft-vs-host disease (GVHD) is one of the major causes of mortality after allo-SCT and often complicated with intestinal dysbiosis. Recent studies suggest that antibiotic-induced dysbiosis is a risk factor for intestinal GVHD. We retrospectively evaluated the impacts of antibiotic use on the incidence of intestinal GVHD occurring before day 100 after allo-SCT. Among 213 patients who underwent allo-SCT, 200 patients achieving engraftment were analyzed. Antibiotics were classified into carbapenem, quinolone, penicillin, cephem, and glycopeptide. Among 128 patients who developed acute GVHD, intestinal GVHD developed in 36 patients. Patients with intestinal GVHD received significantly longer administration of carbapenem and glycopeptide compared to those without it in periengraftment period. In multivariate analysis, use of carbapenem for greater than 7 days was associated with an increased risk of intestinal GVHD. However, use of antibiotics for greater than 7 days was not associated with poor overall survival and high nonrelapse mortality. Long use of carbapenem in periengraftment period may be a risk for intestinal GVHD. Prospective studies are required to validate our findings.